ENG8001 Assignment 2: Air Pre-Heater for Boiler Efficiency Improvement

This report presents research on improving boiler efficiency through the use of air pre-heaters. The study explores the fundamentals of boiler operation, including water tube and fire tube boilers, and discusses the role of air pre-heaters in preheating combustion air to increase efficiency. The methodology includes design considerations, operational calculations, and an analysis of factors affecting boiler performance, such as flue gas temperature and seal leakage. The report also examines the impact of air pre-heater design on heat transfer, the importance of minimizing flue gas temperature, and the significance of air pre-heater efficiency. It also covers safety and ethical considerations. The research aims to optimize boiler performance, reduce fuel consumption, and minimize environmental impact by efficiently extracting heat from flue gases. The report concludes with timelines and references to support the findings.

ENGINEERING RESEARCH METHOD 1
Using the Pre-Heater Air to Improve the Quality of Pressurized Boiler
By Name
Institution
Name
Course

ENGINEERING RESEARCH METHOD 2
Abstract
The heat transferring of heat where the temperature of air and water is increased by passing heat
from another media like flue gas is known as air pre-heater and economizer (ZHANG et al,
2006). The hot air is to ensure that there is a rapid burning in the space heating as well as for the
drying coal where the factory for milling is used. The above important boiler accessory that
offers this duty is an air pre-heater. Where the cost shows that money can be minimized or
thorough burning can be achieved, the use of pre-heater is taken into considerate but not the
working of the steam generator. One has to weigh between the cost benefit and the cost price of
the air preheater before making its decision. The quality of the boiler is directly proportional to
the measure of cold or heat of the burning air in the space. It is arrived through raising the flue
gas temperature in the air pre-heater and heat exchanger zone. In each and every boiler factory, a
huge amount of energy reduces via flue gasses. Therefore the quality of heat energy extracted
from the flue gas can increase the quality of the boiler significantly.

ENGINEERING RESEARCH METHOD 3
Introduction
A closed pipe which gives a way for burning and exchange of heat and water until they turn to
hot steam and water is known as boiler. When there is hot water and steam under high pressure,
then there is possibility of exchanging heat for the process. Steam is needed for heating by many
manufacturing processes. It is also needed for the generation of electricity. Heating water in a
sealed pipe produces steam. Steam boiler is equipment that allows hot gases or fire to heat the
water in a narrow space thereby producing steam. The boiler efficiency can be increased by
reusing the flue gas heat and employing other invented methods and techniques. These
techniques include raising the capacity of the economizer through altering tube structure, raising
heat exchange tubes, designing flue gas flow moving to the economizer, lowering the condensing
temperature through restoring with the low-sulfur fuel, drying the biomass fuel by flue gas heat
before entering the boiler,( Hume et al., 2018) or through controlling of boilers’ burning using an
automatic method to allow the burning quality to increase thereby reducing the toxic gases freed
to the surrounding. There is considerably loss of power when the quality of the boiler is raised.
Loosing boilers’ heat that is using the fixed fuel happens mostly from losing heat with flue gas,
and the through evaporation of hydrogen in the fuel. Preheating air by using the recovery heat
before it enters the burning chamber, decreasing the amount of heat loss with exhaust gases by
controlling the amount of burning air and drying of fuel by using recovery heat before it enters
the burning chamber (Masoumi, & Izakmehri, 2011)are the methods which improve boiler
efficiency. The flue gases can either move through the tubes or outside whereby during which
water is on the other side of the tube. During the flowing of the flue gases via the tubes, the
boiler is known smoke tube boiler and during flowing of water via the pipe, it is called water
tube boiler.

ENGINEERING RESEARCH METHOD 4
Research includes
 Ways of increasing of the boiler efficiency and Operation
 Calculation and the design
Background research
Preheating air being taken inside is known in the steam boiler systems to an extent of bringing in
a multiple of heat exchangers for this reason. Such heat exchanger is usually called the main air
preheater. At about 600 degrees of the flue gases before being depleted via a stack, they are
directed to main air preheater to give flue gas to air heat transfer. The temperature of the flue
gases is inadequate in some cases to increase income air temperature to a required level. Adding
some of the air preheaters may therefore be considered. Some years back, different points in the
steam cycle were tapped for the provision of the steam or hot water being added to air preheaters.
The temperature of the air coming into the main air preheater side of the boiler must be of high
sufficient beside the requirements of the burning system and cycle efficiency to avoid the
temperature of the flue gases from dropping below the required point and the condensation point.
Methodology
 Water tube boiler-it allows water which is heated externally by fire to circulate inside a
tube. Through burning the fuel in the furnace, hot gas is created which then heats water in
the vapor generating tube. Water heated then climbs up into the steam drum. From the
surface of the drum, the saturated vapors is removed.
 Fire tube boiler- this is where heated gases by fire are moved by one or more tubes
flowing via the closed water container. Thermal conduction, liquid heating and the action
of creating steam are methods by which heat is moved to the tubes’ walls (Axelbaum et
al., 2017). The boiler of the fire tube grew as high pressure water tube boilers, fire tube

ENGINEERING RESEARCH METHOD 5
boilers with many small tubes, flued boilers with one or two large flues and low pressure
tank boilers. They have got advantage over flued boilers having one big flue due to the
fact that more small tubes allow for the larger surface area to be heated of such boiler
capacity.
 Air pre-heater- it enables the boiler to preheat the burning air. It includes the
regenerative and recuperative types of air heaters (Indah et al., 2018). The other name of
recuperative air heaters is known as tubular. It is given in boilers of an average or small
vast of steam generating. The air pre-heater type turns bigger in size in case it is to be
used for a very large volume of boilers such as 600 tons/hr and more for the steam
generation. In these cases, regenerative air pre-heaters are required. Regenerative air pre-
heaters being bounded can have unchanging and revolving hood. Very large volume of
the boilers is obtained when the two types of the air pre-heaters are combined with the
tubular operating in the primary air heating and the regenerative working on the
secondary air heating.
Design and calculation
Given the boiler a 210MW with the specifications below, appropriate formulae can be used to
determine its efficiency.

ENGINEERING RESEARCH METHOD 6
The flue gas outlet temperature is directly proportional to the main dry and wet losses. The boiler
efficiency can be increased by minimizing the flue gas temperature after air preheater
(Panditharatne & Gamage, 2019). The outlet temperature of the air preheater is controlled by the
inlet temperature of the flue gas to air preheater, seal leakage of the air preheater, heat action of
air preheater and inlet air temperature to the air preheater.
How air preheater works
Heat quality of the air preheater is measured by;
 air preheater gas side quality
 air preheater air side quality
 Ratio of X
Given, T gi=¿ inlet temperature of the air pre-heater gas
go=¿T ❑ APH gas outlet temperature
ai=¿T ❑ Inlet temperature of the APH air
ao=¿ T❑ Outlet temperature of the APH air
T go ( nl ) =¿ Outlet temperature of the APH gas at no seal leakage
Gas side efficiency=
T go ( nl ) =¿
Al = weight percentage of the leakage air by seals.
= seal leakage percentage through the capacity × 0.9
=
Cpa / Cpg = 0.95
efficiency air side =

ENGINEERING RESEARCH METHOD 7
ratio of X =
Analysis
The action features of the boilers such as quality and evaporation ratio decreases with time
because of bad burning, bad working and maitanance and fauling surface of the thermal transfer
(Narendran et al., 2016) . Factors such like reduction of the fuel quality, water quality among
others can lead bad perfoming of the boiler. Testing of the boiler efficiency assists in finding out
of the deviation value of the boiler efficiency from the good efficiency and corrective action of
the target challenge.
Timelines
18/9/20
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20/9/20
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23/9/20
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25/9/20
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26/9/20
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28/9/20
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29/9/20
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Project
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Backgrou
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calculatio
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Analysis
Conclusi
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on
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proposal
Conclusion
In the research carried out for air pre heater, the research is based on passing the burning air
through it. The accurate design and operation for the air burning can raise the efficiency of the
boiler by either 2% or 3% (Boopathi et al., 2016). The fuel usage is as well minimized. Through
minimizing the leakage of the air preheater, the power auxiliary usage is again minimized hence
saving the fuel intake and making the profit.
Safety issues
While perfoming any combustion experiment, the it is advisable to put on preper attire that can
protect our body from burning incase of fire outbreak.
Ethical issues
Fire extinguishers should provided in the room where the experiment is carried out.

ENGINEERING RESEARCH METHOD 10
References
Masoumi, M.E. and Izakmehri, Z., 2011. Improving of refinery furnaces efficiency using
mathematical modeling. International Journal of Modeling and Optimization, 1(1), p.74.
LI, Q.H., ZHANG, Y.G., CHEN, Y., MENG, A.H., PANG, J.F. and CHEN, C.H., 2016.
Combination Utilization of Air Preheater with Low-Pressure Economizer in MSW Incineration
Power Plants [J]. Journal of Power Engineering, 6.
Panditharatne, V. and Gamage, P.N., 2019. Impact of Service Quality on Customer Satisfaction:
Evidence from Boiler Water and Cooling Tower Water Treatment Chemical Industry in Sri
Lanka. Available at SSRN 3323841.
Axelbaum, R., Xia, F. and Kumfer, B., Washington University in St Louis, 2017. Radiant boiler
for pressurized oxy-combustion and method of radiant trapping to control heat flux in high
temperature particle-laden flows at elevated pressure. U.S. Patent Application 15/541,229.
Hume, S., Yang, Z., Kumfer, B., Axelbaum, R., Dhungel, B., Slater, J., Panesar, R. and Melling,
P., 2018. Improving Flexibility and Performance of Staged Pressurized Oxy-Combustion (No.
DOE-EPRI-29087-2). Electric Power Research Institute.
Narendran, V., Sivamani, S., Hariram, V., Gnanaprakash, M., Raffiq, A.M. and Kumar, D.S.,
2016. Theoretical and Numerical Analysis of Convective Recuperator for an Oil Fired Water
Tube Boiler to Improve the Boiler Performance. Indian Journal of Science and Technology,
9(42), p.9.
Indah, N. and Kusuma, Y., 2018, March. Compressed Air Quality, A Case Study In Paiton Coal
Fired Power Plant Unit 1 And 2. In IOP Conference Series: Materials Science and Engineering
(Vol. 343, No. 1, p. 012031). IOP Publishing.

ENGINEERING RESEARCH METHOD 11
Boopathi, R., Ganapathyraman, G.V., Manimaran, P., Prabakaran, A. and Prabakara, S., 2016.
Performance Analysis of Economiser, Air Pre-Heater and Electrostatic Precipitator of 210MW
Power Plant Boiler. International Journal of Engineering Research and Advanced Technology, 2.