Importance of Test Block for Boiler PA, FD, Secondary Air Fans, ID fans

When undertaking 3T boiler tuning projects, it has been observed that some boilers do not get tuned properly after several attempts.

The main reason that can be attributed to this, is the fan performance does not match the design specifications.

Fans have issues with impellers or tongue clearance or bearings or leakages in ducts where in the fan delivery pressure does not suffice to furnace operations.

Why the fan design pressure is important ?
The fan pressures are a function derived by furnace dimensions, bed height & bed weight. For PF the flame length, curvature, flame spread etc..

For the same furnace dimension if there is a drop in fan design pressure, it gets compensated to volume & increases load on ID fans & the user ends up in losing Boiler Efficiency in the Direct Method.


In the test block these fans do not conform to the pressure volume curve, as provided by OEM.

There are two primary problems with the fans

1) Pressure compensating to volume means the air delivery pressure reduces, increases volume delivery
2) Volume compensates to pressure means the air delivery volume reduces

Both the above problematic fans give distinct combustion problems & many times the client will never know that there is an issue with the fans, they keep suspecting the fuel or any other mechanical part in the boiler.

These boilers have functionally lower efficiency in the Direct Method & 3T conditions cannot be implemented.

The FD fan had an issue of low delivery pressure from commissioning & went undetected for 2 decades at one client. There are several examples where this type of problem go undetected.

For the fan testing there are many codes like BS 848 / AMCA 210 / ISO 5801 / ASME PTC 11 etc.

Whether the boiler is Stoker / FBC / AFBC / CFBC / PF, the test block has to be conducted on all fans to conform all parameters of design, which should be checked every time during annual shutdown.

What should be done if the pressure, volume curve by design & actual installation does not match ?

Check the original drawing & verify what is not matching, repair & reconduct the test block.

Even after all the repairs do not produce matching curves, replace the fan after thorough verification at the time of installation.

Check the following regularly during shutdowns for a consistent & smooth operation, long life of boilers, with excellent combustion characteristics :
1) Test block of fans & take necessary action
2) Test block all air & flue gas ducts, to check pressure drop across all points to conform to design parameters

Advantages of Fans correction ::

Improves fan performance, air delivery by pressure & volume, sets off many combustion issues, faced in operations.

The boiler becomes fully tunable to 3T exercise, where in highest efficiency by Direct Method can be realized.

This issue of fans conforming to design pressure & volume is of very high importance & criticality, as these very parameters define inter relationships with others.

PA pressure is critical to coal density & volume of flow, furnace dimensions.
FD pressure is critical for combustion, C + O2 reaction stability, controls turbulence & time functions in 3T, flame height or length, curvature, bed resistance, flue gas velocity, furnace dimensions etc.

A correct fan profile will relieve the user of many tensions in the combustion front,

If you have any questions, please mail me at sap@chargewave.in

Big Boiler vs. Small Boiler -- Combustion & heat dynamics

What are the differences between PF Boiler, Super Critical Boiler, CFBC Boiler, AFBC, FBC, Stoker & Manual fired Boilers ?

Design & Engineering Point of View :
There is higher steaming capacity in PF, Super Critical, CFB & the others are of lower capacity & manual fired boilers have lowest capacity.

The Engineering side for large boilers up to Stokers is to
1) deliver the fuel in the required crushed size & all fuel handling systems, coal crushers, coal mills etc. are performing this task
2) deliver the air required for combustion + excess air, through the air fans
3) deliver water, cooling towers, tubes etc., to handle the steaming capacity
4) operate through DCS or PLC systems to automate handling processes

From PF to Stokers, the difference is the fuel size input into the system, rest others being common.

For a manual fired boiler, the fuel size is 4 inches or 100 mm, to stoker which is 12mm to 25 mm, FBC & AFBC < 8mm, CFBC < 4 to 6 mm & PF it is around 300 microns.

Do the Combustion reactions change due to Boiler design ?
Not at all. Interesting thing is there is no difference what so ever in the combustion reactions, from manual fired to PF boilers. They are the same.

Why there is an Efficiency difference in Boilers ?
Air to Fuel ratio, factor of time & distance play a major role in Boiler Design.

For example, in a Manual fired boiler, the first pass to second or third pass, the flue gases pass through, generating the steam.

The distance between the flame & the heating surface area, dictates the Efficiency of the system.

The Engineering feats of design & capacity however cannot over rule the basics of Boiler design.

Simply put, the more the time taken for heat to reach the surface areas, the lower is the Efficiency. The quicker the heat travels, higher is the Efficiency.

What has been accomplished in different Boiler Designs, as a factor of time & distance ?
1) In a manual fired Boiler, the time & distance is more, therefore lower Efficiency
2) In a stoker, the fire is surrounded by water tubes, reducing the time, therefore higher efficiency of the Boiler than manual fired one
3) In a FBC, AFBC & CFBC where the fire is, the heat absorbers are present, reducing the time lag therefore higher efficiency than Stokers
4) In PF, the environment is similar to that of Stokers, however the volume of flame generated is higher, therefore higher Efficiency

Heat travels & flows like water, lesser the time, more intensity it has.

What is the role of flame temperature ?
It reduces progressively with distance travelled. Flame temperature role is in conjunction with heat intensity only & not individually.

What is the most important factor, heat intensity or flame temperature ?
It is the intensity which is more important than the temperature. Intensity can be explained like concentrated temperature. In many boilers, the temperatures are operated very high, even then the Efficiency in the Direct Method & steaming capacity is low. The reason is the intensity is low.

Thermal Zones in a Boiler
The Boiler has primarily 9 thermal zones, 6 within the boiler & rest outside the Boiler.

The first 3 thermal zones are
1) Pre combustion zone
2) Combustion zone
3) Tail zone or finishing zone

The fuel which is input, has to complete its preliminary heating in the pre-combustion area of the zone & starts combustion in the Combustion zone & should finish in the tail zone.

Where the fuel characteristics change, the zones shift, & Boilers where such occurrences are present, have lower steaming capacity, with higher steam temperatures.

The Heat absorption systems are exactly placed in the Combustion zone & tail zone.

The above zones are responsible for steam generation. There will be no steam tonnage generated in any other part of the boiler other than the first three zones, where the flame is present.

The next 3 thermal zones
1) the first starts soon after the flame is invisible & extends upto 500 deg C flue gas temperature
2) the second zone & third zones are together up to 300 / 330 deg C

These zones are responsible for building up the pressure & temperature & span the Boiler drum, tube verticals, super heaters.

The last 3 thermal zones
The APH, Economizer & the radiation

The Boilers other than once through design, do not have capacity to absorb heat below 300 deg C, as the heat intensity is not sufficient to cause absorption in the Boiler internals. Such boilers come with APH & Economizers to absorb the heat.

If you examine the design of APH & Economizer, the heating surface area is very low but handles very high volume of flue gas, heat gets concentrated in the lower surface area, developing intensity & therefore exchange of heat.

The first 3 zones are critical for Steaming capacity
The middle 3 zones are critical for steam temperature & pressure
The last 3 zones are important for waste heat recovery

Does the heat exchange by Radiant heat in a Boiler ?
My studies indicate otherwise. If the radiant heat was the answer, the boiler should have performed well with high flame or bed temperatures, the ground reality is, it is not. It is the heat intensity & heat concentration, which transfers the heat.

Heat travels most efficiently in a medium & least in vacuum & the transfer medium in the Boiler is flue gases. The flue gases are freely moving in the furnace. When heat is exchanged, there is drop in its temperature. Every where in the Boiler, the flue gas temperature only is transferring the heat.

When heat transfer medium becomes important, then density also becomes important. Heat travels more efficiently in denser mediums & less in low density. The flue gas density is a very important parameter for heat transfer.

The Boiler is not a super conductor of heat that whatever is put in, it absorbs some & leaves some other, challenging laws of thermal coefficient of absorption of the metals. The metallurgy employed for boiler banks, super heaters, does not have super conducting or super absorbing capacity. There are physical limits.

When there is more heat concentration than what the tubes can absorb, thermal stresses, DNB get created.

Nowadays super conduction is achieved in below minus 150 deg C temperatures & not in higher temperatures like what exist in a boiler. If this is the case, how come that the GCV input vs. exchange is matching by Efficiency methods ?. See the explanation below

Missing explanation about Heat
There are several missing things about heat.

Heat is the only parameter in physics which is represented quantitatively i.e. Kcal / Kg & has no qualitative factor to talk about, other than temperature. All other parameters, steam, power, metals, anything & everything, have a qualitative factor & quantitative factors. Temperature is only measuring degree of hotness or coldness. Temperature alone cannot indicate quality.

Surprising ? Yes it is.

So how do you achieve heat quality ?, by intensity and managing time & distance. The angle at which the heat wave hits the absorbing surface also is important.

The intensity can be explained as total volume of identical temperature heat, and higher heat volume per m3 generates higher intensity.

The boiler tubes are designed to absorb a particular concentration of heat say for example 150,000 Kcal / m3 (depends upon design). If the heat available is above this value, the heat absorption cannot happen, as capacity of the absorber has been breached.

Similar way there is a minimum concentration or intensity which is required, below which the heat absorption will be poor. This information is said as Min. 60% operating capacity is required for Boiler to be Efficient.

Combustion Reactions in different types of Boiler Design -- Reaction point of View
There is no difference whatsoever in the combustion reactions for any boiler, be it PF, CFB or Manual fired. The reactions & heating properties are exactly identical.

Does High Thermal Efficiency mean, that the Boiler Design is Efficient ?
In recent times, Thermal Efficiency which indicates heat absorption capacity of the boiler and assumes that 100% energy is generated in the reactions, has taken center stage in Boiler Operations & its performance assessment.

Even more, new boilers come with Thermal Efficiency of 87 to 89% reported on NCV basis. Higher thermal efficiency only means, the boiler is designed to capture more heat energy leaving the generation part to the operator.

The engineering feat for heat absorption can be appreciated, however the critical part is to conduct the reactions efficiently.

Good heat generation is not achieved by Design, it is achieved by 3T operations alone.

Steam Attemperation & connection to Thermal Zones
Boiler Steam not requiring any attemperation, is a good design from drum capacity & indicates the thermal zones have not shifted. Frequent or excess attemperation means that the thermal zones are shifting & raising the steam temperature. Check the first 3 thermal zones first, & analyse what caused the shift in the first place.

I have corrected many operations in the Boiler from lower generation capacity issue to higher steam temperature & pressure issues, all were caused due to shifting of thermal zones & upon correction delivered the results.

Have questions ?

write to sap@chargewave.in

SAP

Efficiencies terminology & Questions for Boilers

Important Efficiencies & what they represent.

Thermal Efficiency : Thermal Capture or heat capture efficiency of the Boiler. It determines the heat exchanging efficiency in the Boiler.
Verified by the Loss method & 100 minus Losses = Thermal Efficiency

Fuel to Fluid Efficiency or Boiler Efficiency : It is energy input by heat vs. what is converted to steam.

Output / Input %, verified by the Direct Method

Here
Output is Steam MT * Steam Net Enthalpy
Input is fuel CV * fuel quantity

Reaction Efficiency : Efficiency of C, O2 reaction or Efficiency of the reaction conditions (turbulence) created by operations

Combustion Efficiency : Efficiency of how much fuel is consumed in the furnace & what is left over.
100 minus LOI = Combustion Efficiency

Design Efficiency : Efficiency of the Boiler by Design, for design fuel, design air, design air & flue gas velocities, design conditions of all aspects in operation

Most important of the above are represented in ascending order below

1. Design Efficiency
2. Reaction Efficiency
3. Boiler Efficiency
4. Combustion Efficiency
5. Thermal Efficiency

There are others, however for Boiler Operations, the above are good enough.

Thermal Efficiency & Boiler Efficiency are similar & equal ?

No. Thermal Efficiency assumes 100% energy is generated & measures losses, it is more representative of heat exchange or heat absorption capacity of the boiler. 

Boiler Efficiency, measures the actual heat generated vs. heat absorption. It measures the reaction condition side of the Boiler.

Thermal Efficiency is more or less constant in any operation load of the Boiler & seldom changes.

There are 27 distinct turbulence conditions that can be created in Boiler Operations.

Thermal Efficiency is constant in all the 27 conditions, irrespective of the operation load.

Boiler Efficiency varies in 26 conditions, as reaction conditions created change. Boiler Efficiency is load dependent, lower the load, lower the Efficiency & only > 75% loads, only all thermal zones get loaded & Boiler starts to operate in higher efficiency.

Only in 1 operational (3T) condition, the Boiler Efficiency is close to Thermal Efficiency & also Design Efficiency, however the operation load has to be > 75%.

This also means that in 26 conditions, energy generated is far less than the potential of the fuel.

If every calorie offered by the fuel is your target, Boiler Efficiency method is the Key to identify which of the 27 conditions, the Boiler operates & correction is possible.

We offer consultancy for Boilers to identify & bring the operation to the 27th condition.

For any comments, write to sap@chargewave.in

SAP

Critical factors in Boiler Design & Operation

When anyone thinks about a boiler, the first thing which flashes is the steam, steam quality, turbine etc.

However when the Boiler Design aspects are looked into, the most critical factors are presented in ascending order

1) Density of the fuel
    a) Fuel density is the most critical factor, as increase in density reduces flame throw for PF boilers, reduces fluidization in FBC, AFBC & CFBC boilers, reduces fuel flows
   b) The PA Fans are designed for the fuel density & volume delivery
   c) The furnace dimensions (more width or height) are determined again by fuel density & volume delivery
   d) The FD fans are designed for handling the fuel density & its reactivity patterns
   e) reactivity and reaction efficiency of the fuel is also a function of its density, as higher density slows the combustion reactions & lower density speeds it up
   f) The air & flue gas velocities are also determined as a function of fuel density
  g) The air duct dimensions are also function of fuel density
  h) Direct Method Efficiency of the boiler also is a dependent parameter of fuel density
  i) Time, turbulence & temperature or the 3T equilibrium is a dependent parameter of fuel density
  j) LOI in the fly ash, clinker, etc., density of the fuel plays a major role
 k) Flue gas density which is the heat carrier in the furnace also is dependent upon fuel density

The density of the fuel commands the entire combustion process, hence it is the most critical parameter. Most of the combustion related problems arise from change in density of the fuel.

In fact 70% to 80% design work is attributed to combustion related issues, fuel handling etc..

In almost every Boiler installation, the density goes unchecked & is not reported. Many times, when I ask what is the fuel density, it is checked almost the first time ever.


Ask the OEM, what is the fuel density consideration for design.

2) The rest of the boiler, viz., bank, bed tubes, etc. fall in the reminder work

3) Critical parameter is also the steam drum size, ensure the steam drum size is big enough to hold at least 20% to 30% of the steaming capacity as water holding capacity.
   
    When the boiler drum is small, the thermal stresses get created, as there will always be conditions where heat produced > heat absorption. If this condition occurs, if clinker is formed, it is good, as the heat has been removed through clinker.

If the clinker has not formed, then there is a good chance of the tube surfaces getting heated up, becoming red hot & become stressed, readying them for failure.

As the water is the only coolant removing the heat in the whole boiler system, water supply or its velocity >> steam velocity. This measure will keep thermal stresses at bay.

In big steam drum boilers, the boiler tube failure is a slow or remote possibility, due to more than sufficient cooling arrangement.

In small steam drum boilers, the tube failures are high, as the tubes display highest characteristics for easy erosion only when they are red hot.

Steam drum size is a determinant factor in natural circulation rates, which is never measured in Boiler operation.

4) Fuel density in usage : This is also a very critical parameter. Often it happens, that the fuel for which the boiler stands designed, is no longer available. The decisions for purchasing a fuel should include its density as a parameter, which removes much of the anxiety in operations

5) 3T condition : The Boiler should operate in 3T condition, this is most critical parameter in operation

If you have any comments or queries, please send to sap@chargewave.in

SAP

Fuel Additives -- Are they necessary ?

What are Fuel Additives
Fuel Additives are organic or inorganic chemical formulations mostly employed for the LOI reduction, clinker problems, reducing O2 in combustion, in Boilers.The formulations come in as liquids & powders or even as sticks.

What is the role & function of Fuel Additives in combustion ? Actually speaking none.

Boiler Operation Types
There are 27 distinct Boiler operation types, methods or conditions.
Out of these 13 cause higher flue gas or air velocity, another 13 cause deficient flue gas or air velocity. The 27th condition is where the flue gas velocity is neither higher or lower, it is exact.

Air or Flue gas velocity impact
Increased air velocity ejects the fuel out of the system & deficient air velocity produces un-burnt carbon. However both get classified as LOI.

How to check air velocity ?
When the LOI is segregated & checked for Volatile matter presence, the air velocity behaviour can be verified.

If the LOI shows VM presence, the boiler is working with higher air velocity & is ejecting the fuel out.

If the LOI shows no VM presence, the boiler is working with deficient air velocity.

For boilers where switching between high load & low load is frequent, the VM presence will be 50-50, means present in some samples & absent in some samples.

Fuel Additives -- Limitations
Fuel Additives can perform some what in the 13 conditions where there is deficient flue gas velocity. Deficient air velocity produces Fixed Carbon, no volatile matter ash which require higher combustion temperature.

However in the rest 14 conditions, there is no effect of Fuel Additives whatsoever.

If the Boiler employs a fuel additive and there is some result attributed, then the possibility is that the operation is of deficient air velocity types.

Clinker Problems -- the Truth & the Story
The ash fusion temperature, chemistry of fuel, ash, iron etc, causes clinkers is a good story. The truth is that deficient air velocity can only produce clinkers.

Deficient air velocity operations, produce Fixed carbon in Ash & also have clinker problems.

Deficient air velocity is produced by increased bed height or bed thickness, improper settings of PA, FD.

Clinker formation is caused primarily due to low FD or PA pressure & increased bed height.

The heat energy is like water, it flows. When the flue gases cannot pick up the heat due to low velocity, the heat flows to the ash & forms clinker.

The only heat carrier in the boiler is the flue gas only & it has to flow quite clear.

In some cases, the bed volume itself is very low, however the operating load of the boiler will be higher, meaning lower bed volume handles more heat energy, when load drops & heat has no flowing opportunity to water side, it flows to fuel and causes clinker.

I have solved many clinker formation problems in CFBC, AFBC, FBC, Manual fired boilers, by correction of bed thickness & air pressure.

Lowering O2% while using a Fuel Additive
Some Fuel Additive formulations have O2 releasing compounds, which release O2 or nascent Oxygen. The density of the flue gas is a very important parameter in heat carriage. If the density is higher, it carries more heat & vice versa.

When O2 is reduced due to Fuel Additive usage, the results may be good for Indirect Method assessment, which shows increase in Efficiency, however the reaction conditions will take a good beating, along with flue gas density.

Many times, reducing O2%, only will cause increase in fuel consumption & lower Direct Method Efficiency.

Where there is measurement of fuel, the activity of lowering O2% can be discarded, as the effect of increased consumption can be noticed.

However where is no measurement of fuel or the installation follows Indirect Method, the real effect cannot be known till very long time, as there is no counter check or verification.

Do Fuel Additives reduce fuel consumption ?
If there is LOI, due to deficient air velocity operations, Yes to an extent of 0.2 to 1%, as per the scale of LOI occurrence.
In all other cases, they have no effect

Fuel Additives are Combustion Catalysts ?
The Combustion reaction itself, happens very quickly. Catalyzing already an over speeding reaction only worsens the case. 
When already the combustion is suffering, employing a catalyst, only increases the suffering.

Will increased reactivity improve the combustion ?
Yes. Only in 3T condition. A Fuel Additive cannot produce a 3T condition.
3T condition is a physical reaction environment condition produced by fans, WBP & fuel

IS CATALYSIS OF COMBUSTION REACTION REQUIRED ?
Not at all. Only correction of reaction conditions is required, which takes care of every thing.

How to eliminate Fuel Additives usage

Fuel Additives are only needed when there are incorrect Boiler operation which cause deficient air or flue gas velocity. 

Deficient air velocity correction or boiler switching to 3T operations, eliminate usage of Fuel Additives, once & for all.

In 3T condition,
1. the air velocity is exact, therefore raising the reaction efficiency of Carbon & oxygen
2. high reaction efficiency conditions or environment exists, the LOI is automatically near zero
3. the air pressure is right, the clinker formation also gets eliminated

Fuel Additives are not needed, however become compulsive due to improper operational issues.

The above information is for solid fuel fired boilers.

For Oil fired & Gas fired Boilers
Turbulence correction or 3T operation, eliminates all the combustion issues


Any comments write to sap@chargewave.in

SAP

Power Plants CO2 emissions -- Challenges & Opportunities

In the present moment, the CO2 emissions are taking center stage in every discussion. What are the challenges & opportunities ?

Challenges : As the power demand is ever increasing, so are the CO2 emissions as most of the plants are either coal or biomass based ones

What are the opportunities for CO2 reduction ?
Is the CO2 capture alone the solution ?
Are there any other options ?

While CO2 capture is expensive to invest, the cheapest alternative is to employ the 3T (time, turbulence, temperature) equilibrium condition in Boiler Operations.

What 3T can achieve is much bigger as an immediate alternative, as it brings down the Boudouard Reaction to within the theoretical limits and the fuel consumption itself is reduced.

While the CO2 emission is directly proportional to the fuel employed per ton of Steam, when the fuel consumption itself lowers, the CO2 gets lowered too.

We also manufacture chemicals, which can block Boudouard Reaction & lower the fuel consumption.

Together 3T + chemicals the is maximum reduction option at hand.

The biggest challenge is not measuring the fuel or its GCV and the employment of Indirect Method.

Unless the Indirect Method is debated, unshackled, understood & restructured, the possibility of CO2 emissions reduction is remote.

Any queries ?

You can contact me at sap@chargewave.in

SAP

Thermal Efficiency & Indirect Method -- Limitations & Opportunities

Thermal Efficiency -- Limitations & Opportunities

Thermal Efficiency, is a term which has to be clearly understood in relationship with Boiler Operations.

What does it indicate ?
1. Boiler is first a carbon & oxygen reactor, where the energy generation is taking place
2. After the energy is generated, it is exchanged throughout the boiler in different thermal zones

So, we can measure two efficiencies based upon 2 different phenomenon

1. Efficiency of the reaction (carbon & oxygen reactor)
2. Efficiency of the heat capture or heat exchange

The Indirect method focusses on Efficiency of heat exchange part and assumes 100% energy is generated from the combustion of fuel.

What is considered in the Indirect Method
Losses from stack, LOI, radiation, blowdown, moisture, Hydrogen etc., so these are the energy losses what the boiler cannot capture.

Where is the energy generation here ??? 
Energy generation has no mention. 100% energy generation is an assumption. 

What is ignored in the Indirect Method

 Reaction conditions created in the furnace by the fans
 Reaction Efficiency of Carbon & oxygen
 Boudouard Reaction (CO2 + C --> 2CO -- 6000 Kcal / Kg) condition assessment
 Actual measurement of energy generated in the reaction

My question is why assume that Energy generated is 100% ?. What is the guarantee that it has been generated & is available ?

If the Boudouard Reaction is higher than the theoretical limit, more heat is consumed in the Endothermic reaction & less is available for heat transfer.
 
If only 85% energy has been generated in the furnace, then 85% minus losses will be the Thermal Efficiency.

Can the formula be modified to Heat generated minus Losses = Thermal Efficiency ? to include what they have forgotten ?

CO2 is measured & assumed that it is formed by C + O2 reaction only, where as there are two routes for CO2 formation, one directly by C + O2 reaction & another by 2CO + O2 reaction.

The question is how heat capture efficiency can explain heat generation as an assumption, when there are two distinct processes happening.

Is heat absorption more critical than its generation ?
Is the reaction condition not at all important ?
Is the heat generation so simple and easy that it could be assumed to be 100% always ?


Questions ?
I was asked at one of the presentations, that the Indirect Method is the only reliable method to assess the Thermal Efficiency ?

I replied, how the boiler designer would assess the efficiency on the drawing board or at the designing stage ?
Is the Indirect Method assessment the only way after commissioning of the Boiler, for derivation ?
How the designer would know, the efficiency at the design stage ?
Is there another possibility or processes of derivation ?

In fact, the Boiler has to have the necessary combustion air + excess air. How do we assess this ? In the boiler if you reduce excess air, combustion air is also reduced, & when it happens it promotes Boudouard Reaction.

Higher Thermal Efficiency by design is a factor of excess air, lower the excess air, higher is the heat capture, this is an offshoot of heat exchanger.

Does higher Thermal Efficiency mean the reaction efficiency is high enough ? Not at all.

There are 27 different or distinct ways or methods, a boiler can be operated, in which only 1 method aligns the 3T's & the rest do not.


Interesting facts about Indirect Method
1. Even if the load of the boiler is 10% or 20% or < 60% or 100% the Efficiency is always higher than 82% plus & does not change
2. Design Efficiency of the boiler can be exceeded in this method ?
    Several commissioning reports of boiler installations & also in Energy Audit reports, this is observed, is this true ?
3. Can the boiler function higher than its design efficiency ?
4. 100% energy generation is assumed in 100 minus losses formula
5. Fuel, GCV of fuel can be back calculated without consideration to reaction efficiency, actual fuel GCV or actual fuel quantity fired
6. Time, turbulence & temperature equilibrium present or absent, it has no effect on heat generation
7. In precise measurement of fuel, fuel GCV, the Thermal Efficiency is always greater than Direct Method Boiler Efficiency
8. In all the 27 types of Boiler operations, the Indirect Method shows similar values
9. Lesser Direct Method Efficiency does not raise the stack temperature or other losses (again indicating it is a measurement of heat exchange capacity)
10. Fuel density, furnace draft, operating loads etc. have no impact on the Efficiency

Is the Indirect Method so efficient ?
1) does it mean that there is no need to use Bomb Calorimeters, fuel measurement systems, Boiler instrumentation ? Is the design enough ?
2) does it mean that it has all solutions for combustion problems ?
3) does it mean following the Indirect Method has no validation system vis-a-vis measurement of fuel & its CV


Why is the Indirect Method followed ?
1) Heat exchange capacity of the Boiler does not change & very stable
2) It is easy to report & measure
3) Everyone says it is scientific so, it has to be
4) Everyone follows it
5) No one asks for validation, includes Managements, Auditors, Operators
6) Method is recommended by OEM's & Auditors
7) Fuel quantification & its CV have lot of variations, is cumbersome which justifies not validating it & hence forth skipped altogether
8) Reason no. 7 justified & supported by OEM's, Auditors & others irrespectively 

It is a fact that in 98% of the installations, the Indirect Method cannot be validated in the input fuel or its CV, as the boilers function at much lower efficiency than what is factually reported. Observations show that the fuel quantities & its CV's are tailored when Efficiencies are low.

If the Indirect Method cannot be validated in the input fuel or its CV, why do we follow it in the first place ?


Fuel can be measured precisely by weight by bunker weighing systems instead of belt weighing systems which have errors, stacking fuel in separate identifiable lots, will resolve fuel measurement. Frequent sampling from feeders & increasing no. of samples, will lower the error in the CV measurement.

A bold, factual assessment will reveal all the short comings of the Indirect Method, open opportunities for correction & cost savings.

The reverse ash reconciliation method also can be employed, to calculate the coal input. There are options for measurement, however they have to exercised.

Its time, there is a thorough review of this method, which does not allow actual heat generation assessment in the Boiler & change the operations which support the 3T condition.

What if the the formula is changed to

"Heat generated minus Losses = Thermal Efficiency %"

Heat generated = Fuel Quantity x Fuel CV
Losses = The same as in the Indirect Method

A MAGIC WILL UNFOLD WITH LOT OF OPPORTUNITY 

Opportunity to see a great magic in the above formula, as the heat generated can be increased by invoking the 3T equilibrium. I have already done this in many boilers. There is a great cost saving when you adopt the above change.

It is not all that difficult, it is the first step to Boiler Operation mastery.

Start the step for fuel measurement & the guarantee is that you can save a min. of 4 to 5% fuel in this method. The average saving I got is > 8% till date, only by tuning the boilers for 3T.

If you have questions, please write to sap@chargewave.in

Regards
SAP