Summary
Sometimes, employee performance falls short of expectations. You decide, you need to "talk" of employees, their performance is not enough. 14 counseling skills will help.
1. This is about the performance behavior. You should be concerned about the behavior, only when the impact on performance.
2. Ensure that the employee is absolutely sure of two things
• You expect accurate performance
• How will the measured performance.
If there is the slightest doubt, strongly enhanced standard.
3. Clear objectives for our interview. Clear about employees, and then start again.
4. To avoid the question of "why"? Guess they produce, opinions and defense. If you want accurate information, put forward the problems began, "What?" "Who are you?" "Which one? "" When "and" how? '
5. "Challenged" rather than "condemn the practice. You want to find out what happened, and how to ensure it does not happen again. Criticism of individuals will not be able to achieve this.
6. Interpretation: Check the information that you receive and unchanged definitions. Remember, you do not want to win an argument. You want to get the information, you can do better employee performance.
7. Ask employees they believe, how they should handle the situation. You want to improve, not strengthen underperforming.
8. Avoid controversy. Did not you want to prove who is right and who is wrong. You want the concrete improvement of the performance, not a debate victory.
9. Encourage the employee's contribution. Not only do you want them to speak freely at any time. You want to improve their proposals, in order to ensure that a similar problem will not happen again.
10. Focus on the future. What is done. What will happen the next time something really important.
11. Strengthening positive performance. Make sure employees know that he or she is doing good, you want them to continue to do a good job.
12. Gains the agreement of the action to be taken. Clear that employees have any questions, you would expect the performance in the future.
13. Solicit their opinions, it is necessary for the improvement of the system to ensure that the error does not happen again. , Problems that may arise due to a bad system, rather than employees of error.
14. Avoid threats. Focus on future business performance and the contribution of the staff.
Other issues
Try them serious performance deficiencies. Do not want to repeat until you have to take remedial measures before a failure occurs. It is easier to correct than many mistakes cumulative effect of an error.
Resist the temptation, the the error terminated staff unless extremely detrimental to the business. It costs far less than the recovery performance from existing employees, rather than the termination of his or her alternatives.
But Leon ... you are a "soft"
You might think that I was a "soft" errors staff. I did not. I just want to make sure you give him or her every opportunity to improve. This is the most suitable for you.
If you just want to give them a rocket "to do so this is your choice., However, do not deceive yourself that the" rocket "will establish a long-term performance improvement.
Conclusion
When the time to take action worse performance, ensure that you do what. Self stumble won the parameters and playing mind games will not improve their performance.
November 04, 2012
All of the little gray squirrels would show up in droves and rush around Target
I went for a walk one day and saw a squirrel collecting acorns for the upcoming winter. I think his life will be how easy it is, as long as he can go all the acorn needs of the target.
My sales target to attract squirrels and imagine what will happen.
The little gray squirrel will show in droves, catch on target. Each of them can be pushed filled with acorns big red cart. Squirrels shopping shelves are empty, they filled every available corner, in their trees.
Will have more than enough acorns in the winter, so hunger has never been a problem, but it comes at a price - the the squirrel homes become so squirrels are no longer out their own tree house comfortable.
When spring came, still a lot of acorns on a tree, but there are so many fresh food - is targeting fresh food - squirrel leaves on the trees and stock. They decided to continue last year's acorns ... they still good, there is no reason to get rid of them ... right? And the beginning of the cycle.
This is a stupid picture, is not it? However, this is exactly what happens in our world today.
Marketers know, what we desire, it is available to us. We use a new, bigger, better time.
As consumers, we tend to forget, all the shops are interested in one thing ... profit.
The way they make their money is very simple, they provide to our temptations. They pay close attention to the needs of their customers, they will buy something (two very different things, but I can save this discussion another time).
Jewelry store to buy what they predict that their customers will buy it, put it on a shelf, and tell you all this. They do not care if you've got a another one is good, if you need it or not. They care about is whether you will buy it.
If for some reason they do not sell the products, lower prices, so it is tempt you. If you mark it down does not work, they get rid of it. Even the money spent in the store, their inventory, they do not waste valuable shelf space is not currently anything useful to them, that is ... their money.
So, this is everything with you?
First of all, just because a storage stock, it does not mean you have to buy it. The store's goal is to sell your product, you can not make you happy.
You do not buy "the latest and the most intelligent, but because it is available. Give permission control, and ask yourself if you really need the product, you will how to use it. Ask yourself if there is something that you have to work instead. Ask yourself, if it will eventually sit on your shelf.
Second, suppose you are the manager of a store, and take a few minutes to look at your office. Is there something in there, beyond their shelf life? Is there something you have never used? Things you're wasting your space is not for you to make money?
Of course, your product may be "good", there is nothing to say, you can not use them, but if you want to this year's model, and then recognize the pattern last year is not worth anything, let it go. You spend the money has gone, now it is about shelf space.
Now imagine this ... what your space and life, if you only keep the things to help you reach your goal?
My sales target to attract squirrels and imagine what will happen.
The little gray squirrel will show in droves, catch on target. Each of them can be pushed filled with acorns big red cart. Squirrels shopping shelves are empty, they filled every available corner, in their trees.
Will have more than enough acorns in the winter, so hunger has never been a problem, but it comes at a price - the the squirrel homes become so squirrels are no longer out their own tree house comfortable.
When spring came, still a lot of acorns on a tree, but there are so many fresh food - is targeting fresh food - squirrel leaves on the trees and stock. They decided to continue last year's acorns ... they still good, there is no reason to get rid of them ... right? And the beginning of the cycle.
This is a stupid picture, is not it? However, this is exactly what happens in our world today.
Marketers know, what we desire, it is available to us. We use a new, bigger, better time.
As consumers, we tend to forget, all the shops are interested in one thing ... profit.
The way they make their money is very simple, they provide to our temptations. They pay close attention to the needs of their customers, they will buy something (two very different things, but I can save this discussion another time).
Jewelry store to buy what they predict that their customers will buy it, put it on a shelf, and tell you all this. They do not care if you've got a another one is good, if you need it or not. They care about is whether you will buy it.
If for some reason they do not sell the products, lower prices, so it is tempt you. If you mark it down does not work, they get rid of it. Even the money spent in the store, their inventory, they do not waste valuable shelf space is not currently anything useful to them, that is ... their money.
So, this is everything with you?
First of all, just because a storage stock, it does not mean you have to buy it. The store's goal is to sell your product, you can not make you happy.
You do not buy "the latest and the most intelligent, but because it is available. Give permission control, and ask yourself if you really need the product, you will how to use it. Ask yourself if there is something that you have to work instead. Ask yourself, if it will eventually sit on your shelf.
Second, suppose you are the manager of a store, and take a few minutes to look at your office. Is there something in there, beyond their shelf life? Is there something you have never used? Things you're wasting your space is not for you to make money?
Of course, your product may be "good", there is nothing to say, you can not use them, but if you want to this year's model, and then recognize the pattern last year is not worth anything, let it go. You spend the money has gone, now it is about shelf space.
Now imagine this ... what your space and life, if you only keep the things to help you reach your goal?
November 01, 2012
Booklet Tips - Doing It Right - Not
You may know some details of my booklet story, and, no doubt, certain things stuck with you more than others. For instance, the thing that makes great copy is how many booklets have been sold (over a million) in four languages and various formats without spending a penny on advertising. Every word of that is completely true as stated, without the slightest embellishment.
However, you may not know these details:
* There was one typo in each of the first 50,000 copies sold.
* Month one unwittingly generated a $200 checking account bank fee.
* The first print run had no clean right angles on the cover trim.
* The next several print runs had streaky covers.
* Sales that fell through rarely were about price, content, or production.
* The first large-quantity sale did not include a shipping charge.
* The choice buyers had was "yes or no" - having only one product.
* Years later I learned the Spanish version was a mediocre translation.
* Every sale was a "one-night stand," with nothing to bundle or follow.
These are some of the many things I like to gingerly refer to as learning opportunities. And they are but a few of the highlights of the past 20+ years of being in the booklet business. While I constantly made my best effort to do things right, there were things I simply didn't know... yet. And they were costly lessons in time, money, or both in each and every case. Rest assured that none of the experiences in that list was repeated, ever!
It's not uncommon to hear booklet authors and would-be booklet authors express a desire to do a booklet the "right way." While there is now a trail that's been blazed in the past two decades about many things that work, please know there is no "right way," no one-size-fits-all. Your way will be, well, your way. It may look a bit like how others have done it.
Pieces of it will be the starting point for you. It will be unique, though.
The best and most important advice, like so many other things in life, is to just do it. You'll find your own successes and your own learning opportunities. And you'll find them because of who you are, how you live your life, who your connections are, where you have the willingness to explore, how you've structured your products and services format-wise and price-wise, and many other variables.
Thinking that there is a right way to do this (or lots of other things) is likely to keep you stuck in place, not moving forward, not sharing the best of what you've got and who you are with those who value your knowledge and point of view. While I encourage you to do the very best you can, did you notice that having a typo in the first 50,000 copies didn't stop things from
ultimately reaching well over a million copies sold? What are you waiting for?
ACTION - Start your (next) booklet today, using the basics of what makes sense to you, while considering guidance that's worked for others. Keep in mind that your journey will be unique to you and that your ideas have merit. You will find what's right for you.
However, you may not know these details:
* There was one typo in each of the first 50,000 copies sold.
* Month one unwittingly generated a $200 checking account bank fee.
* The first print run had no clean right angles on the cover trim.
* The next several print runs had streaky covers.
* Sales that fell through rarely were about price, content, or production.
* The first large-quantity sale did not include a shipping charge.
* The choice buyers had was "yes or no" - having only one product.
* Years later I learned the Spanish version was a mediocre translation.
* Every sale was a "one-night stand," with nothing to bundle or follow.
These are some of the many things I like to gingerly refer to as learning opportunities. And they are but a few of the highlights of the past 20+ years of being in the booklet business. While I constantly made my best effort to do things right, there were things I simply didn't know... yet. And they were costly lessons in time, money, or both in each and every case. Rest assured that none of the experiences in that list was repeated, ever!
It's not uncommon to hear booklet authors and would-be booklet authors express a desire to do a booklet the "right way." While there is now a trail that's been blazed in the past two decades about many things that work, please know there is no "right way," no one-size-fits-all. Your way will be, well, your way. It may look a bit like how others have done it.
Pieces of it will be the starting point for you. It will be unique, though.
The best and most important advice, like so many other things in life, is to just do it. You'll find your own successes and your own learning opportunities. And you'll find them because of who you are, how you live your life, who your connections are, where you have the willingness to explore, how you've structured your products and services format-wise and price-wise, and many other variables.
Thinking that there is a right way to do this (or lots of other things) is likely to keep you stuck in place, not moving forward, not sharing the best of what you've got and who you are with those who value your knowledge and point of view. While I encourage you to do the very best you can, did you notice that having a typo in the first 50,000 copies didn't stop things from
ultimately reaching well over a million copies sold? What are you waiting for?
ACTION - Start your (next) booklet today, using the basics of what makes sense to you, while considering guidance that's worked for others. Keep in mind that your journey will be unique to you and that your ideas have merit. You will find what's right for you.
October 31, 2012
The Secret Behind Attraction Marketing
Did you know that Attraction between people is not a choice, it is a biological response.
Furthermore there exists Attraction Triggers and if we learn how to switch these attraction triggers within ourselves, we automatically begin to attract other people.
Two of the most important triggers in existence are VALUE and STATUS.
Did you know that If you can establish a relationship with a person of greater status or value, your personal value and status automatically increases, while through that conversation, new doors open, opportunities are found that would never have been found, new insight knowledge can be gained, new alliances can be found, new partnerships can be formed with other people who you would never have access to.
The key to success in today's marketplace is this "If you are going to sell something to someone, you have to find a way to get invited into their world as a welcome GUEST instead of a PEST.
There exists two ways that you can reach prospects
1. Play the numbers game- Traditional way
2. Position yourself in the marketplace in a manner that allows interested prospects to find you and contact you.
Option 1- chasing the prospect
Option 2- Prospect chasing you- Here you are perceived as the expert and suddenly you hold all the power and value in that situation. All of a sudden, this isn't about selling, the prospect invited you into their world.
You are in a position of a knowledgeable service provider whose expertise is sought out and pursued.
This is where you have to be in today's marketplace in order to break through the infinite noise that is out there.
When I came across this statement, it changed my way of thinking. The statement is as follows "Nobody who bought a drill actually wanted a drill, they actually wanted a hole, therefore if you want to go out and sell drills, advertise information about making holes".
This statement is a game changer that if it is applied in your business, you would experience STRATOSPHERIC SUCCESS.
Sales people market their opportunity directly, but the more excellent way is to market and promote useful information.
When your audience sees you as an expert who wants to help, instead of a sales person who wants to sell, they are gladly going to come and pursue you, when they are going to make that purchase.
You become the HUNTED, instead of the HUNTER.
EXPERTS NEVER HAVE TO ADVERTISE!!!!!!!!
They never have to promote a sales pitch, somehow in a funny way they always seem to have a line of eager customers waiting outside their door.
STOP ADVERTISING YOUR OPPORTUNITY, START ADVERTISING YOUR EXPERTISE AND KNOWLEDGE!!!!!
Do you have something to offer THEM as a LEADER AND MENTOR?
The key to success in today's marketplace is this "If you are going to sell something to someone, you have to find a way to get invited into their world as a welcome GUEST instead of a PEST.
You become the HUNTED, instead of the HUNTER.
EXPERTS NEVER HAVE TO ADVERTISE!!!!!!!
They never have to promote a sales pitch, somehow in a funny way they always seem to have a line of eager customers waiting outside their door.
STOP ADVERTISING YOUR OPPORTUNITY, START ADVERTISING YOUR EXPERTISE AND KNOWLEDGE!!!!!
Do you have something to offer THEM as a LEADER AND MENTOR?
Furthermore there exists Attraction Triggers and if we learn how to switch these attraction triggers within ourselves, we automatically begin to attract other people.
Two of the most important triggers in existence are VALUE and STATUS.
Did you know that If you can establish a relationship with a person of greater status or value, your personal value and status automatically increases, while through that conversation, new doors open, opportunities are found that would never have been found, new insight knowledge can be gained, new alliances can be found, new partnerships can be formed with other people who you would never have access to.
The key to success in today's marketplace is this "If you are going to sell something to someone, you have to find a way to get invited into their world as a welcome GUEST instead of a PEST.
There exists two ways that you can reach prospects
1. Play the numbers game- Traditional way
2. Position yourself in the marketplace in a manner that allows interested prospects to find you and contact you.
Option 1- chasing the prospect
Option 2- Prospect chasing you- Here you are perceived as the expert and suddenly you hold all the power and value in that situation. All of a sudden, this isn't about selling, the prospect invited you into their world.
You are in a position of a knowledgeable service provider whose expertise is sought out and pursued.
This is where you have to be in today's marketplace in order to break through the infinite noise that is out there.
When I came across this statement, it changed my way of thinking. The statement is as follows "Nobody who bought a drill actually wanted a drill, they actually wanted a hole, therefore if you want to go out and sell drills, advertise information about making holes".
This statement is a game changer that if it is applied in your business, you would experience STRATOSPHERIC SUCCESS.
Sales people market their opportunity directly, but the more excellent way is to market and promote useful information.
When your audience sees you as an expert who wants to help, instead of a sales person who wants to sell, they are gladly going to come and pursue you, when they are going to make that purchase.
You become the HUNTED, instead of the HUNTER.
EXPERTS NEVER HAVE TO ADVERTISE!!!!!!!!
They never have to promote a sales pitch, somehow in a funny way they always seem to have a line of eager customers waiting outside their door.
STOP ADVERTISING YOUR OPPORTUNITY, START ADVERTISING YOUR EXPERTISE AND KNOWLEDGE!!!!!
Do you have something to offer THEM as a LEADER AND MENTOR?
The key to success in today's marketplace is this "If you are going to sell something to someone, you have to find a way to get invited into their world as a welcome GUEST instead of a PEST.
You become the HUNTED, instead of the HUNTER.
EXPERTS NEVER HAVE TO ADVERTISE!!!!!!!
They never have to promote a sales pitch, somehow in a funny way they always seem to have a line of eager customers waiting outside their door.
STOP ADVERTISING YOUR OPPORTUNITY, START ADVERTISING YOUR EXPERTISE AND KNOWLEDGE!!!!!
Do you have something to offer THEM as a LEADER AND MENTOR?
Select the Right NOx Control Technology
Most major industrialized urban areas in the U.S. are unable to meet the National Ambient Air Quality Standards (NAAQS) for ozone. Atmospheric studies have shown that ozone formation is the result of a complex set of chemical reactions involving volatile organic compounds (VOCs) and nitrogen oxides (NOx). Those studies indicate that many urban areas with VOC/NOx ratios greater tan 15:1 can reduce ambient ozone levels only by reducing NOx emissions. Many states, therefore, are implementing NOx control regulations for combustion devices in order to achieve compliance with the NAAQS ozone standard.
This article discusses the characterization of NOx emissions from industrial combustion devices. It then provides guidance on how to evaluate the applicable NOx control technologies and select an appropriate control method.
Characterizing Emissions
Most industrial combustion devices have not been tested to establish their baseline NOx emission levels. Rather, the NOx emissions from these units have been simply estimated using various factors. In light of recent regulations, however, it is mandatory that the NOx emissions from affected units now be known with certainty. This will establish each unit's present compliance status and allow definition of fee applicable control technologies for those units that will require modification to achieve compliance.
It is, therefore, important to test each combustion device to verify its NOx emissions characteristics. The testing process should be streamlined to provide timely and necessary information for making decisions regarding the applicability of NOx control technologies.
The basic approach is to select one device from a class of units (that is, of same design and size) for characterization testing (NOx, CO2, and 02). Testing is conducted at three load points that represent the normal operating range of the unit, with excess oxygen variation testing conducted at each load point. Figure 1 illustrates the typical characterization test results. The remaining units in the class are tested at only one load point, at or near full load.
The operational data obtained during testing, in conjunction with the NOx and CO data, are used to define the compliance status of each unit, as well as the applicable NOx control technologies for those devices that must be modified. In most instances, this approach will allow multiple units to be tested in one day and provide the necessary operational data the engineer needs to properly evaluate the potential NOx control technologies.
Fundamental Concepts
Reasonably available control technology (RACT) standards for NOx emissions are defined in terms of an emission limit, such as 0.2 lb NOx/MMBtu, rather than mandating Specific NOx control technologies. Depending on the fuel fired and the design of the combustion device, a myriad of control technologies may be viable options. Before selecting RACT for a particular combustion device, it is necessary to understand how NOx emissions are formed so that the appropriate control strategy may be formulated.
NOx emissions formed during the combustion process are a function of the fuel composition, the operating mode, and the basic design of the boiler and combustion equipment. Each of these parameters can play a significant role in the final level of NOx emissions.
NOx formation is attributed to three distinct mechanisms:
1. Thermal NOx Formation;
2. Prompt (i.e.. rapidly forming) NO formation; and
3. Fuel NOx formation.
Each of these mechanisms is driven by three basic parameters - temperature of combustion, time above threshold temperatures in an oxidizing or reducing atmosphere, and turbulence during initial combustion.
Thermal NOx formation in gas-, oil-. and coal-fired devices results from thermal fixation of atmospheric nitrogen in the combustion air. Early investigations of NOx formation were based upon kinetic analyses for gaseous fuel combustion. These analyses by Zeldovich yielded an Arrhenius-type equation showing the relative importance of time, temperature, and oxygen and nitrogen concentrations on NOx formation in a pre-mixed flame (that is, the reactants are thoroughly mixed before combustion).
While thermal NOx formation in combustion devices cannot actually be determined using the Zeldovich relationship, it does illustrate the importance of the major factors that Influence thermal NOx formation, and that NOx formation increases exponentially with combustion temperatures above 2.800°F.
Experimentally measured NOx formation rates near the flame zone are higher than those predicted by the Zeldovich relationship. This rapidly forming NO is referred to as prompt NO. The discrepancy between the predicted and measured thermal NOx values is attributed to the simplifying assumptions used in the derivation of the Zeldovich equation, such as the equilibrium assumption that O = ½ 02. Near the hydrocarbon-air flame zone, the concentration of the formed radicals, such as O and OH, can exceed the equilibrium values, which enhances the rate of NOx formation. However, the importance of prompt NO in NOx emissions is negligible in comparison to thermal and fuel NOx.
When nitrogen is introduced with the fuel, completely different characteristics are observed. The NOx formed from the reaction of the fuel nitrogen with oxygen is termed fuel NOx. The most common form of fuel nitrogen is organically bound nitrogen present in liquid or solid fuels where individual nitrogen atoms are bonded to carbon or other atoms. These bonds break more easily than the diatomic N2 bonds so that fuel NOx formation rates can be much higher than those of thermal NOx. In addition, any nitrogen compounds (e.g., ammonia) introduced into the furnace react in much the same way.
Fuel NOx is much more sensitive to stoichiometry than to thermal conditions. For this reason, traditional thermal treatments, such as flue gas recirculation and water injection, do not effectively reduce NOx emissions from liquid and solid fuel combustion.
NOx emissions can be controlled either during the combustion process or after combustion is complete. Combustion control technologies rely on air or fuel staging techniques to take advantage of the kinetics of NOx formation or introducing inerts that inhibit the formation of NOx during combustion, or both. Post-combustion control technologies rely on introducing reactants in specified temperature regimes that destroy NOx either with or without the use of catalyst to promote the destruction.
Conbustion Control
The simplest of the combustion control technologies is low-excess-air operation--that is, reducing the excess air level to the point of some constraint, such as carbon monoxide formation, flame length, flame stability, and so on. Unfortunately, low-excess-air operation has proven to yield only moderate NOx reductions, if any.
Three technologies that have demonstrated their effectiveness in controlling NOx emissions are off-stoichiometric combustion. low-NOx burners, and combustion temperature reduction. The first two are applicable to all fuels, while the third is applicable only to natural gas and low-nitro-gen-content fuel oils.
Off-stoichiometric, or staged, combustion is achieved by modifying the primary combustion zone stoichiometry - that is, the air/fuel ratio. This may be accomplished operationally or by equipment modifications.
An operational technique known us burners-out-of-service (BOOS) involves terminating the fuel flow to selected burners while leaving the air registers open. The remaining burners operate fuel-rich, thereby limiting oxygen availability, lowering peak flame temperatures, and reducing NOx formation. The unreacted products combine with the air from the terminated-fuel burners to complete burnout before exiting the furnace. Figure 2 illustrates the effectiveness of this technique applied to electric utility boilers. Staged combustion can also be achieved by installing air-only ports, referred to as overfire air (OFA) ports, above the burner zone. redirecting a portion of the air from the burners to the OFA ports. A variation of this concept, lance air, consists of installing air tubes around the periphery of each burner to supply staged air.
BOOS, overfire air, and lance air achieve similar results. These techniques are generally applicable only to larger, multiple-burner, combustion devices.
Low-NOx burners are designed to achieve the staging effect internally. The air and fuel flow fields are partitioned and controlled to achieve the desired air/fuel ratio, which reduces NOx formation and results in complete burnout within the furnace. Low-NOx burners are applicable lo practically all combustion devices with circular burner designs.
Combustion temperature reduction is effective at reducing thermal N0x but not fuel NOx. One way to reduce the combustion temperature is to introduce a diluent. Flue gas recirculation (FGR) is one such technique.
FGR recirculates a portion of the flue gas leaving the combustion process back into the windbox. The recirculated flue gas, usually on the order of 10-20% of the combustion air provides sufficient dilution to decrease NOx emission. Figure 3 correlates the degree of emission reduction with the amount of flue gas recirculated.
On gas-fired units, emissions arc reduced well beyond the levels normally achievable with staged combustion control. In fact, FGR is probably the most effective and least troublesome system for NOx reduction for gas-fired combustors.
An advantage of FGR is that it can be used with most other combustion control methods. Many industrial low-NOx burner systems on the market today incorporate induced FGR. In these designs, a duct is installed between the stack and forced-draft inlet (suction). Flue gas products are recirculated through the forced-draft fan, thus eliminating the need for a separate fan.
Water injection is another method that works on the principle of combustion dilution, very similar to FGR. In addition to dilution, it reduces the combustion air temperature by absorbing the latent heat of vaporization of the water before the combustion air reaches the primary combustion zone.
Few full-scale retrofit or test trials of water injection have been performed. Until recently, water injection has not been used as a primary NOx control method on any combustion devices other than gas turbines because of the efficiency penalty resulting from the absorption of usable energy to evaporate the water. In some cases, water injection represents a viable option to consider when moderate NOx reductions are required to achieve compliance.
Reduction of the air preheat temperature is another viable technique for culling NOx emissions. This lowers peak flame temperatures, thereby reducing NOx formation. The efficiency penalty, however, may be substantial. A rule of thumb is a 1% efficiency loss for each 40º F reduction in preheat. In some cases this may be offset by adding or enlarging the existing economizer.
Post-Combustion Control
There are two technologies for controlling NOx emissions after formation in the combustion process - selective catalytic reduction (SCR) and selective noncatalytic reduction (SNCR). Both of these processes have seen very limited application in the U.S. for external combustion devices. In selective catalytic reduction, a gas mixture of ammonia with a carrier gas (typically compressed air) is injected upstream of a catalytic reactor operating at temperatures between 450º F and 750º F. NOx control efficiencies are typically in the 70-90% percent range, depending on the type of catalyst, the amount of ammonia injected, the initial NOx level, and the age of the catalyst.
The retrofit of SCR on existing combustion devices can be complex and costly. Apart from the ammonia storage, preparation, and control monitoring requirements, significant modifications to the convective pass ducts may be necessary.
In selective noncatalytic reduction, ammonia- or urea-based reagents are injected into the furnace exit region, where the flue gas is in the range of 1,700-2,000º F. The efficiency of this process depends on the temperature of the gas, the reagent mixing with the gas, the residence time within the temperature window, and the amount of reagent injected relative to the concentration of NOx present. The optimum gas temperature for die reaction is about 1,750°F; deviations from this temperature result in a lower NOx reduction efficiency. Application of SNCR, therefore, must be carefully assessed, as its effectiveness is very dependent on combustion device design and operation.
Technology Selection
As noted previously, selection of applicable NOx control technologies depends on a number of fuel, design, and operational factors. After identifying the applicable control technologies, an economic evaluation must be conducted to rank the technologies according to their cost effectiveness. Management can then select the optimum NOx control technology for the specific unit.
It should be noted that the efficiencies of NOx control technologies are not additive, but rather multiplicative. Efficiencies for existing combustion devices have been demonstrated in terms of percent reduction from baseline emissions level. This must be taken into account when considering combinations of technology.
Consider, for example, the following hypothetical case. Assume a baseline NOx emissions level of 100 ppmv and control technology efficiencies as follows: low-excess-air operation (LEA), 10%; low-NOx burners (LNB), 40%; and flue gas recirculation (FGR). 60%. The three controls are installed in the progressive order of LEA-LNB-FGR.
It should also he noted that combining same-principle technologies (for example, two types of staged combustion) would not provide a further significant NOx reduction than either of the combination, since they operate on the same principle.
It must be emphasized that virtually all of the available control technologies have the potential for adversely affecting the performance and/or operation of the unit. The operation data obtained during the NOx characterization testing, therefore, must be carefully evaluated in light of such potential impacts before selecting applicable control technologies. Operational limitations such as flame envelope, furnace pressure, forced-draft fan capacity, and the like must he identified for each potential technology and their corresponding impacts quantified. (Reference (4), for example, discusses these items, in detail.)
As anyone familiar with combustion processes knows, one technology does not fit all. Careful consideration must he used to select the appropriate, compatible control technology or technologies to ensure compliance at least cost with minimal impact on performance, operation, and capacity.
This article discusses the characterization of NOx emissions from industrial combustion devices. It then provides guidance on how to evaluate the applicable NOx control technologies and select an appropriate control method.
Characterizing Emissions
Most industrial combustion devices have not been tested to establish their baseline NOx emission levels. Rather, the NOx emissions from these units have been simply estimated using various factors. In light of recent regulations, however, it is mandatory that the NOx emissions from affected units now be known with certainty. This will establish each unit's present compliance status and allow definition of fee applicable control technologies for those units that will require modification to achieve compliance.
It is, therefore, important to test each combustion device to verify its NOx emissions characteristics. The testing process should be streamlined to provide timely and necessary information for making decisions regarding the applicability of NOx control technologies.
The basic approach is to select one device from a class of units (that is, of same design and size) for characterization testing (NOx, CO2, and 02). Testing is conducted at three load points that represent the normal operating range of the unit, with excess oxygen variation testing conducted at each load point. Figure 1 illustrates the typical characterization test results. The remaining units in the class are tested at only one load point, at or near full load.
The operational data obtained during testing, in conjunction with the NOx and CO data, are used to define the compliance status of each unit, as well as the applicable NOx control technologies for those devices that must be modified. In most instances, this approach will allow multiple units to be tested in one day and provide the necessary operational data the engineer needs to properly evaluate the potential NOx control technologies.
Fundamental Concepts
Reasonably available control technology (RACT) standards for NOx emissions are defined in terms of an emission limit, such as 0.2 lb NOx/MMBtu, rather than mandating Specific NOx control technologies. Depending on the fuel fired and the design of the combustion device, a myriad of control technologies may be viable options. Before selecting RACT for a particular combustion device, it is necessary to understand how NOx emissions are formed so that the appropriate control strategy may be formulated.
NOx emissions formed during the combustion process are a function of the fuel composition, the operating mode, and the basic design of the boiler and combustion equipment. Each of these parameters can play a significant role in the final level of NOx emissions.
NOx formation is attributed to three distinct mechanisms:
1. Thermal NOx Formation;
2. Prompt (i.e.. rapidly forming) NO formation; and
3. Fuel NOx formation.
Each of these mechanisms is driven by three basic parameters - temperature of combustion, time above threshold temperatures in an oxidizing or reducing atmosphere, and turbulence during initial combustion.
Thermal NOx formation in gas-, oil-. and coal-fired devices results from thermal fixation of atmospheric nitrogen in the combustion air. Early investigations of NOx formation were based upon kinetic analyses for gaseous fuel combustion. These analyses by Zeldovich yielded an Arrhenius-type equation showing the relative importance of time, temperature, and oxygen and nitrogen concentrations on NOx formation in a pre-mixed flame (that is, the reactants are thoroughly mixed before combustion).
While thermal NOx formation in combustion devices cannot actually be determined using the Zeldovich relationship, it does illustrate the importance of the major factors that Influence thermal NOx formation, and that NOx formation increases exponentially with combustion temperatures above 2.800°F.
Experimentally measured NOx formation rates near the flame zone are higher than those predicted by the Zeldovich relationship. This rapidly forming NO is referred to as prompt NO. The discrepancy between the predicted and measured thermal NOx values is attributed to the simplifying assumptions used in the derivation of the Zeldovich equation, such as the equilibrium assumption that O = ½ 02. Near the hydrocarbon-air flame zone, the concentration of the formed radicals, such as O and OH, can exceed the equilibrium values, which enhances the rate of NOx formation. However, the importance of prompt NO in NOx emissions is negligible in comparison to thermal and fuel NOx.
When nitrogen is introduced with the fuel, completely different characteristics are observed. The NOx formed from the reaction of the fuel nitrogen with oxygen is termed fuel NOx. The most common form of fuel nitrogen is organically bound nitrogen present in liquid or solid fuels where individual nitrogen atoms are bonded to carbon or other atoms. These bonds break more easily than the diatomic N2 bonds so that fuel NOx formation rates can be much higher than those of thermal NOx. In addition, any nitrogen compounds (e.g., ammonia) introduced into the furnace react in much the same way.
Fuel NOx is much more sensitive to stoichiometry than to thermal conditions. For this reason, traditional thermal treatments, such as flue gas recirculation and water injection, do not effectively reduce NOx emissions from liquid and solid fuel combustion.
NOx emissions can be controlled either during the combustion process or after combustion is complete. Combustion control technologies rely on air or fuel staging techniques to take advantage of the kinetics of NOx formation or introducing inerts that inhibit the formation of NOx during combustion, or both. Post-combustion control technologies rely on introducing reactants in specified temperature regimes that destroy NOx either with or without the use of catalyst to promote the destruction.
Conbustion Control
The simplest of the combustion control technologies is low-excess-air operation--that is, reducing the excess air level to the point of some constraint, such as carbon monoxide formation, flame length, flame stability, and so on. Unfortunately, low-excess-air operation has proven to yield only moderate NOx reductions, if any.
Three technologies that have demonstrated their effectiveness in controlling NOx emissions are off-stoichiometric combustion. low-NOx burners, and combustion temperature reduction. The first two are applicable to all fuels, while the third is applicable only to natural gas and low-nitro-gen-content fuel oils.
Off-stoichiometric, or staged, combustion is achieved by modifying the primary combustion zone stoichiometry - that is, the air/fuel ratio. This may be accomplished operationally or by equipment modifications.
An operational technique known us burners-out-of-service (BOOS) involves terminating the fuel flow to selected burners while leaving the air registers open. The remaining burners operate fuel-rich, thereby limiting oxygen availability, lowering peak flame temperatures, and reducing NOx formation. The unreacted products combine with the air from the terminated-fuel burners to complete burnout before exiting the furnace. Figure 2 illustrates the effectiveness of this technique applied to electric utility boilers. Staged combustion can also be achieved by installing air-only ports, referred to as overfire air (OFA) ports, above the burner zone. redirecting a portion of the air from the burners to the OFA ports. A variation of this concept, lance air, consists of installing air tubes around the periphery of each burner to supply staged air.
BOOS, overfire air, and lance air achieve similar results. These techniques are generally applicable only to larger, multiple-burner, combustion devices.
Low-NOx burners are designed to achieve the staging effect internally. The air and fuel flow fields are partitioned and controlled to achieve the desired air/fuel ratio, which reduces NOx formation and results in complete burnout within the furnace. Low-NOx burners are applicable lo practically all combustion devices with circular burner designs.
Combustion temperature reduction is effective at reducing thermal N0x but not fuel NOx. One way to reduce the combustion temperature is to introduce a diluent. Flue gas recirculation (FGR) is one such technique.
FGR recirculates a portion of the flue gas leaving the combustion process back into the windbox. The recirculated flue gas, usually on the order of 10-20% of the combustion air provides sufficient dilution to decrease NOx emission. Figure 3 correlates the degree of emission reduction with the amount of flue gas recirculated.
On gas-fired units, emissions arc reduced well beyond the levels normally achievable with staged combustion control. In fact, FGR is probably the most effective and least troublesome system for NOx reduction for gas-fired combustors.
An advantage of FGR is that it can be used with most other combustion control methods. Many industrial low-NOx burner systems on the market today incorporate induced FGR. In these designs, a duct is installed between the stack and forced-draft inlet (suction). Flue gas products are recirculated through the forced-draft fan, thus eliminating the need for a separate fan.
Water injection is another method that works on the principle of combustion dilution, very similar to FGR. In addition to dilution, it reduces the combustion air temperature by absorbing the latent heat of vaporization of the water before the combustion air reaches the primary combustion zone.
Few full-scale retrofit or test trials of water injection have been performed. Until recently, water injection has not been used as a primary NOx control method on any combustion devices other than gas turbines because of the efficiency penalty resulting from the absorption of usable energy to evaporate the water. In some cases, water injection represents a viable option to consider when moderate NOx reductions are required to achieve compliance.
Reduction of the air preheat temperature is another viable technique for culling NOx emissions. This lowers peak flame temperatures, thereby reducing NOx formation. The efficiency penalty, however, may be substantial. A rule of thumb is a 1% efficiency loss for each 40º F reduction in preheat. In some cases this may be offset by adding or enlarging the existing economizer.
Post-Combustion Control
There are two technologies for controlling NOx emissions after formation in the combustion process - selective catalytic reduction (SCR) and selective noncatalytic reduction (SNCR). Both of these processes have seen very limited application in the U.S. for external combustion devices. In selective catalytic reduction, a gas mixture of ammonia with a carrier gas (typically compressed air) is injected upstream of a catalytic reactor operating at temperatures between 450º F and 750º F. NOx control efficiencies are typically in the 70-90% percent range, depending on the type of catalyst, the amount of ammonia injected, the initial NOx level, and the age of the catalyst.
The retrofit of SCR on existing combustion devices can be complex and costly. Apart from the ammonia storage, preparation, and control monitoring requirements, significant modifications to the convective pass ducts may be necessary.
In selective noncatalytic reduction, ammonia- or urea-based reagents are injected into the furnace exit region, where the flue gas is in the range of 1,700-2,000º F. The efficiency of this process depends on the temperature of the gas, the reagent mixing with the gas, the residence time within the temperature window, and the amount of reagent injected relative to the concentration of NOx present. The optimum gas temperature for die reaction is about 1,750°F; deviations from this temperature result in a lower NOx reduction efficiency. Application of SNCR, therefore, must be carefully assessed, as its effectiveness is very dependent on combustion device design and operation.
Technology Selection
As noted previously, selection of applicable NOx control technologies depends on a number of fuel, design, and operational factors. After identifying the applicable control technologies, an economic evaluation must be conducted to rank the technologies according to their cost effectiveness. Management can then select the optimum NOx control technology for the specific unit.
It should be noted that the efficiencies of NOx control technologies are not additive, but rather multiplicative. Efficiencies for existing combustion devices have been demonstrated in terms of percent reduction from baseline emissions level. This must be taken into account when considering combinations of technology.
Consider, for example, the following hypothetical case. Assume a baseline NOx emissions level of 100 ppmv and control technology efficiencies as follows: low-excess-air operation (LEA), 10%; low-NOx burners (LNB), 40%; and flue gas recirculation (FGR). 60%. The three controls are installed in the progressive order of LEA-LNB-FGR.
It should also he noted that combining same-principle technologies (for example, two types of staged combustion) would not provide a further significant NOx reduction than either of the combination, since they operate on the same principle.
It must be emphasized that virtually all of the available control technologies have the potential for adversely affecting the performance and/or operation of the unit. The operation data obtained during the NOx characterization testing, therefore, must be carefully evaluated in light of such potential impacts before selecting applicable control technologies. Operational limitations such as flame envelope, furnace pressure, forced-draft fan capacity, and the like must he identified for each potential technology and their corresponding impacts quantified. (Reference (4), for example, discusses these items, in detail.)
As anyone familiar with combustion processes knows, one technology does not fit all. Careful consideration must he used to select the appropriate, compatible control technology or technologies to ensure compliance at least cost with minimal impact on performance, operation, and capacity.
The Art of Listening
Why is this? Typically we approach a conversation with another person as if they were a blank canvas upon which we can write words that they will receive and understand exactly as we intend. When they don't "get" our message exactly as we intend, we get irritated and think they must not be listening, don't understand, are playing games or being hostile.
But are we really speaking to a blank canvas? Of course not. The other person is living in his or her internal conversation. The one in their head that they refer to mostly as "self talk." Before you even open your mouth, he is already listening, to himself. Why? Because people are always listening to their own internal conversation.
So the question is not whether we are listening when someone speaks to us. It's a question of how we are listening. We always have an internal conversation going on as we listen to another person and that conversation filters everything we hear. Virtually everyone listens in one or more of a particular set of ways. Some of these internal filtering conversations are: get to the point, what am I going to say next, do I agree with you or not?, is what you are saying right?, whose going to win in this conversation?, find the flaw, why are you attacking me?, are you approving of me?, and a few others.
Do people decide in advance how they are going to listen? Of course not. All of these ways of listening are automatic and unconscious. Our conversation is what it is. It has a mind of its own. We listen how we listen, we react to the things we react to without much forethought and it's just that way. The fact is, you were born into a paradigm where you were trained to listen in these ways, just like everyone else, without any thought on your part whatsoever.
People are not aware of the power of their listening. We live the life of the victim, as if someone "out there" is out to get us. Let's be clear. There is no such thing as a victim. We shape our world with how we listen. If we listen attack, guess how everything shows up for us? Like an attack! If we listen agree/disagree, then that's what's available to us in any discussion. You get no new information, no new ideas, and no ability for anyone to make a difference with you. All you get to do is agree or disagree.
Here's the worst part of all: If you really analyze all of these ways of listening, you will see that your attention is on yourself and your only concern is your own self-interests. You are concerned with protecting yourself because each of these ways of listening is fundamentally adversarial in nature. You're over there; I'm over here. You show up as a threat to me and I have to protect myself from you.
Why can't we all get along? In most interactions, we have person X with his attention on himself and concerned with his own self-interests and person Y with her attention on herself and concerned with protecting herself. When they talk to each other, do they have a meaningful, intimate conversation? No way. Most conversations resemble two television sets tuned to different channels broadcasting at each other.
This is the work of the ego. The ego has only one concern: its survival. For the ego, you are the center of the universe, everyone else is separate from you and, what's worse, they are all enemies.
This is why we rarely experience true communication between people. Each person's primary concern is his or her own self-interest and desire to make sure the other person hears what he or she has to say. People place very little or no attention on making sure they understand the other person. This is the root cause of most miscommunication and upsets between spouses, parents and children, team members, bosses and employees.
Given how critical our listening is to our success in every aspect of our lives, it is amazing to me that we don't all have a profound understanding of the phenomenon of listening. Listening consists of only two components. The first component is: Who do you have your attention on? The second component is: What's your internal conversation? That's it. All that "stuff" about body language, facial expression, eye contact, and the like flows directly from those two components. Understand them and you will unshackle yourself and acquire the freedom to be effective not only as a leader but in all your relationships.
Once you become aware of how you listen, which means becoming conscious of where you have your attention and your internal dialog when others are speaking to you, you can choose not to listen that way any longer. Implementing this choice will take focus, commitment and staying conscious.
Since you have your attention on yourself when you listen unconsciously, you need to put your attention on the other person to generate a more constructive way of listening. That part is simple but critical in importance. While it's simple, it is not easy. Why? Because of that ego again. Remember, it's only concerned with its survival and tells you that everyone "out there" is the enemy. It does tell you that, which is why it's totally natural, in the world of your ego, to go through life with your attention on yourself.
In addition, listen with compassion, for what the other person is committed to, for the goodness in people, how can everyone be included and everybody win.
What are the advantages of listening in one or more of these ways? You get real communication, understanding, intimacy, trust and an appreciation of the other person's position. That creates satisfaction, happiness, a sense of well being, self-confidence, joy, aliveness and ultimately rich, meaningful, quality relationships. In a business setting, the payoff is productivity, creativity, teamwork, enthusiasm, no turnover, success and of course money, results and accomplishment. You get all of this by switching the way you listen.
Scott Hunter, author, speaker and industry leader, helps people GET UNSTUCK.
Stay informed and current with insight from Scott himself.
But are we really speaking to a blank canvas? Of course not. The other person is living in his or her internal conversation. The one in their head that they refer to mostly as "self talk." Before you even open your mouth, he is already listening, to himself. Why? Because people are always listening to their own internal conversation.
So the question is not whether we are listening when someone speaks to us. It's a question of how we are listening. We always have an internal conversation going on as we listen to another person and that conversation filters everything we hear. Virtually everyone listens in one or more of a particular set of ways. Some of these internal filtering conversations are: get to the point, what am I going to say next, do I agree with you or not?, is what you are saying right?, whose going to win in this conversation?, find the flaw, why are you attacking me?, are you approving of me?, and a few others.
Do people decide in advance how they are going to listen? Of course not. All of these ways of listening are automatic and unconscious. Our conversation is what it is. It has a mind of its own. We listen how we listen, we react to the things we react to without much forethought and it's just that way. The fact is, you were born into a paradigm where you were trained to listen in these ways, just like everyone else, without any thought on your part whatsoever.
People are not aware of the power of their listening. We live the life of the victim, as if someone "out there" is out to get us. Let's be clear. There is no such thing as a victim. We shape our world with how we listen. If we listen attack, guess how everything shows up for us? Like an attack! If we listen agree/disagree, then that's what's available to us in any discussion. You get no new information, no new ideas, and no ability for anyone to make a difference with you. All you get to do is agree or disagree.
Here's the worst part of all: If you really analyze all of these ways of listening, you will see that your attention is on yourself and your only concern is your own self-interests. You are concerned with protecting yourself because each of these ways of listening is fundamentally adversarial in nature. You're over there; I'm over here. You show up as a threat to me and I have to protect myself from you.
Why can't we all get along? In most interactions, we have person X with his attention on himself and concerned with his own self-interests and person Y with her attention on herself and concerned with protecting herself. When they talk to each other, do they have a meaningful, intimate conversation? No way. Most conversations resemble two television sets tuned to different channels broadcasting at each other.
This is the work of the ego. The ego has only one concern: its survival. For the ego, you are the center of the universe, everyone else is separate from you and, what's worse, they are all enemies.
This is why we rarely experience true communication between people. Each person's primary concern is his or her own self-interest and desire to make sure the other person hears what he or she has to say. People place very little or no attention on making sure they understand the other person. This is the root cause of most miscommunication and upsets between spouses, parents and children, team members, bosses and employees.
Given how critical our listening is to our success in every aspect of our lives, it is amazing to me that we don't all have a profound understanding of the phenomenon of listening. Listening consists of only two components. The first component is: Who do you have your attention on? The second component is: What's your internal conversation? That's it. All that "stuff" about body language, facial expression, eye contact, and the like flows directly from those two components. Understand them and you will unshackle yourself and acquire the freedom to be effective not only as a leader but in all your relationships.
Once you become aware of how you listen, which means becoming conscious of where you have your attention and your internal dialog when others are speaking to you, you can choose not to listen that way any longer. Implementing this choice will take focus, commitment and staying conscious.
Since you have your attention on yourself when you listen unconsciously, you need to put your attention on the other person to generate a more constructive way of listening. That part is simple but critical in importance. While it's simple, it is not easy. Why? Because of that ego again. Remember, it's only concerned with its survival and tells you that everyone "out there" is the enemy. It does tell you that, which is why it's totally natural, in the world of your ego, to go through life with your attention on yourself.
In addition, listen with compassion, for what the other person is committed to, for the goodness in people, how can everyone be included and everybody win.
What are the advantages of listening in one or more of these ways? You get real communication, understanding, intimacy, trust and an appreciation of the other person's position. That creates satisfaction, happiness, a sense of well being, self-confidence, joy, aliveness and ultimately rich, meaningful, quality relationships. In a business setting, the payoff is productivity, creativity, teamwork, enthusiasm, no turnover, success and of course money, results and accomplishment. You get all of this by switching the way you listen.
Scott Hunter, author, speaker and industry leader, helps people GET UNSTUCK.
Stay informed and current with insight from Scott himself.
The Theory of Cost-Effective NOx Reduction for Saving the Environment
NOx IFGR is one of the primary air pollutants emitted from combustion processes and environmental regulations are the only driver forcing industry to install NOx control systems. In the Houston Galveston area alone, there is over 6,000 point sources that would need to be controlled to comply with the new State Implementation Plan adopted by the TNRCC. Many in the industry are in the process of evaluating control techniques to comply with the new regulations.
Before evaluating NOx control strategies, it is important to establish the present baseline emission levels and to understand the NOx formation mechanism. Most of the NOx formed during combustion of gas and light oil is from high temperature oxidation (or "fixation") of atmospheric nitrogen and is referred to as Thermal NOx. NO is the major constituent of thermal NOx and its formation can be modeled by the Zeldovich equation:
[NO] = k 1 ·exp (-k2/T) · [N2] ·[O2]1/2 · t
where, [ ] = mole fraction, k's = constants, T = temperature, and t = residence time. The equation indicates that NOx formation is an exponential function of temperature and a square root function of oxygen concentration. Thus, by manipulating the temperature or oxygen concentration, the formation of thermal NOx can be controlled. Systems manipulating the oxygen concentration are referred to as stoichiometry-based combustion control techniques (e.g. Low NOx Burners or LNBs) and those reducing the temperature are referred to as dilution-based combustion control techniques (e.g. Flue Gas Recirculation or FGR). LNBs control NOx emissions by providing air staging to create an initial, fuel-rich zone (partial combustion zone) followed by an air-rich zone to complete the combustion process.
Some burner designs incorporate fuel staging that results in lower levels of NOx. Since NOx formation is a square root function of oxygen concentration, the reduction capability of stoichiometry-based technologies is limited. According to the theory, NOx formation should increase with oxygen concentration or with the amount of excess air. In practice, however, increasing the amount of air lowers NOx formation due to reduction in flame temperature. Typical reduction in NOx as a function of actual air to theoretical air ratio is shown in Figure 1. For comparison, typical NOx reduction as a function of flue gas recirculation rate.
Reduction in NOx due to fuel staging or varying the oxygen levels can be as high as 40%. NOx reduction due to dilution with flue gas can be as high as 80%. Newer LNB designs such as ULNBs attempt to capture the concept of dilution by incorporating internal recirculation to obtain lower levels of NOx. Unfortunately, to obtain the desired levels of internal recirculation, higher fuel gas pressure and a larger burner throat are required. In retrofit applications, larger burners result in a need to rebuild furnace floor. Rebuilding furnace floor is both expensive and time consuming; and, increases the LNB installation cost exponentially! Performance of ULNBs is also very sensitive to several factors including hydrogen in fuel gas, air preheat, particulates, liquid droplets and air leakage. Fuel gas containing hydrogen, air leakage into the furnace and air pre-heat result in increasing NOx emissions from ULNB. Changing the fuel gas system to remove hydrogen, particulates and droplets from fuel gas and sealing the furnace to ensure no air leakage also increases the cost of installing ULNB significantly. Eliminating air pre-heat for ULNB application not only increases installation costs, but also increases operating costs in terms of additional fuel cost.
Most combustion experts agree that once the air preheater is removed, the unit never returns to the original operation! Furthermore, at reduced loads, the internal recirculation rate is reduced due to lower fuel flow. This results in limiting the turndown ratio of the newer burner designs. To avoid limitations of the newer burner design but to capture the concept of lower NOx reduction, some burner vendors offer external FGR along with LNB, but for a cost equivalent to that of SCR! Since the total installed cost of burner systems is an order of magnitude higher than FGR; and, since most of the NOx reduction in the newer burners is due to FGR, the most cost-effective alternative is the proven standalone FGR technology.
In a typical FGR application, about 5 to 25 % of the flue gases is recycled back to the combustion zone resulting in NOx reduction as high as 80%. Thus, NOx levels that can be achieved with newer burners can also be achieved by external FGR- at a significantly lower cost and without limiting the turndown capability of the unit. Elimination of air pre-heater operation to reduce NOx is not necessary with FGR. Major cost of traditional FGR technology is due to an additional hot gas fan requirement to transport the flue gas.
To reduce the cost even further, a very cost-effective technology has been developed that eliminates the need for a separate FGR fan and windbox mixing devices. The proprietary Induced FGR technology (IFGR) technology is based on utilizing the existing forced draft fan to induce flue gas into the combustion air at the fan inlet. FDF capacity required for IFGR is equivalent to operating the fan with extra 1 to 4 % O2 in flue. IFGR technology (patent pending) reduces NOx emissions by as much as 80%, and typically improves the combustion efficiency and performance. IFGR technology requires very minor modifications and can be installed in less than a week. IFGR has relatively little or no impact on performance and operation.
For fan limited units, there are several low cost debottle-necking options to accommodate IFGR flow. For operators of natural draft units planning on installing SCR technology, A modified technology exists called Slip Stream FGR technology (patent pending), where a slipstream from downstream of SCR fan is recirculated back into the flame zone to obtain high levels of NOx reduction. A combination of FGR based systems with post-combustion SCR technology is more cost-effective compared to application of only SCR technology. This is because when SCR is used in combination with FGR systems, the costs associated with catalyst and ammonia-handling systems are significantly reduced due to lower NOx concentration. In certain situations, reduction in ammonia usage alone payback technology costs in less than 6 months. BCCA estimates about $ 8 billion will be spent in the Houston-Galveston area to comply with the rules. It is believes that the approach presented here can reduce the costs by more than 35%.
Before evaluating NOx control strategies, it is important to establish the present baseline emission levels and to understand the NOx formation mechanism. Most of the NOx formed during combustion of gas and light oil is from high temperature oxidation (or "fixation") of atmospheric nitrogen and is referred to as Thermal NOx. NO is the major constituent of thermal NOx and its formation can be modeled by the Zeldovich equation:
[NO] = k 1 ·exp (-k2/T) · [N2] ·[O2]1/2 · t
where, [ ] = mole fraction, k's = constants, T = temperature, and t = residence time. The equation indicates that NOx formation is an exponential function of temperature and a square root function of oxygen concentration. Thus, by manipulating the temperature or oxygen concentration, the formation of thermal NOx can be controlled. Systems manipulating the oxygen concentration are referred to as stoichiometry-based combustion control techniques (e.g. Low NOx Burners or LNBs) and those reducing the temperature are referred to as dilution-based combustion control techniques (e.g. Flue Gas Recirculation or FGR). LNBs control NOx emissions by providing air staging to create an initial, fuel-rich zone (partial combustion zone) followed by an air-rich zone to complete the combustion process.
Some burner designs incorporate fuel staging that results in lower levels of NOx. Since NOx formation is a square root function of oxygen concentration, the reduction capability of stoichiometry-based technologies is limited. According to the theory, NOx formation should increase with oxygen concentration or with the amount of excess air. In practice, however, increasing the amount of air lowers NOx formation due to reduction in flame temperature. Typical reduction in NOx as a function of actual air to theoretical air ratio is shown in Figure 1. For comparison, typical NOx reduction as a function of flue gas recirculation rate.
Reduction in NOx due to fuel staging or varying the oxygen levels can be as high as 40%. NOx reduction due to dilution with flue gas can be as high as 80%. Newer LNB designs such as ULNBs attempt to capture the concept of dilution by incorporating internal recirculation to obtain lower levels of NOx. Unfortunately, to obtain the desired levels of internal recirculation, higher fuel gas pressure and a larger burner throat are required. In retrofit applications, larger burners result in a need to rebuild furnace floor. Rebuilding furnace floor is both expensive and time consuming; and, increases the LNB installation cost exponentially! Performance of ULNBs is also very sensitive to several factors including hydrogen in fuel gas, air preheat, particulates, liquid droplets and air leakage. Fuel gas containing hydrogen, air leakage into the furnace and air pre-heat result in increasing NOx emissions from ULNB. Changing the fuel gas system to remove hydrogen, particulates and droplets from fuel gas and sealing the furnace to ensure no air leakage also increases the cost of installing ULNB significantly. Eliminating air pre-heat for ULNB application not only increases installation costs, but also increases operating costs in terms of additional fuel cost.
Most combustion experts agree that once the air preheater is removed, the unit never returns to the original operation! Furthermore, at reduced loads, the internal recirculation rate is reduced due to lower fuel flow. This results in limiting the turndown ratio of the newer burner designs. To avoid limitations of the newer burner design but to capture the concept of lower NOx reduction, some burner vendors offer external FGR along with LNB, but for a cost equivalent to that of SCR! Since the total installed cost of burner systems is an order of magnitude higher than FGR; and, since most of the NOx reduction in the newer burners is due to FGR, the most cost-effective alternative is the proven standalone FGR technology.
In a typical FGR application, about 5 to 25 % of the flue gases is recycled back to the combustion zone resulting in NOx reduction as high as 80%. Thus, NOx levels that can be achieved with newer burners can also be achieved by external FGR- at a significantly lower cost and without limiting the turndown capability of the unit. Elimination of air pre-heater operation to reduce NOx is not necessary with FGR. Major cost of traditional FGR technology is due to an additional hot gas fan requirement to transport the flue gas.
To reduce the cost even further, a very cost-effective technology has been developed that eliminates the need for a separate FGR fan and windbox mixing devices. The proprietary Induced FGR technology (IFGR) technology is based on utilizing the existing forced draft fan to induce flue gas into the combustion air at the fan inlet. FDF capacity required for IFGR is equivalent to operating the fan with extra 1 to 4 % O2 in flue. IFGR technology (patent pending) reduces NOx emissions by as much as 80%, and typically improves the combustion efficiency and performance. IFGR technology requires very minor modifications and can be installed in less than a week. IFGR has relatively little or no impact on performance and operation.
For fan limited units, there are several low cost debottle-necking options to accommodate IFGR flow. For operators of natural draft units planning on installing SCR technology, A modified technology exists called Slip Stream FGR technology (patent pending), where a slipstream from downstream of SCR fan is recirculated back into the flame zone to obtain high levels of NOx reduction. A combination of FGR based systems with post-combustion SCR technology is more cost-effective compared to application of only SCR technology. This is because when SCR is used in combination with FGR systems, the costs associated with catalyst and ammonia-handling systems are significantly reduced due to lower NOx concentration. In certain situations, reduction in ammonia usage alone payback technology costs in less than 6 months. BCCA estimates about $ 8 billion will be spent in the Houston-Galveston area to comply with the rules. It is believes that the approach presented here can reduce the costs by more than 35%.
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