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Increasing The Efficiency of Boiler By The Utilization of The Exhaust Gases Temperature

A Research Proposal


University college of  engineering and technology,UOS

Dr. Engr. Muddassarullah


M.Saleem(B.Sc. Mechanical Engineering)

                           ROLL NO:                      BMEF14M003

University College of Engineering and Technology, University of Sargodha


Mechanical Engineering Department 1

1-Introduction: 2

2-Literature review: 2

3-Aims and objectives: 3

4-Experimentations: 4

4.1- LTE connected to waste warmth recuperation and RH Regenerative Heater applied 4

4.2-ESP Electrostatic Precipitator 4

4.3-Exhaust gas resistance 4

5-Design: 5

5.1-Thermodynamic process: 6

6-Project Plane: 6


6.2-Gantt chart: 7

7-Conclusions: 8

8-References: 8


The good and cheap fossil fuel in Pakistan for power generation is coal. It is concluded from the statically data that the electrically generated from coal n Pakistan is 0.04% of world (41%) power generation from coal. Coal fired power plants are also the main cause of the air pollution. Now a days, the world’s biggest problem is to provide cheap and plenty of electricity, keeping the environment free from pollution. The power generation from coal acts as a particular challenges. In most of countries coal is available and abundant at cheap rates, remarkably in US, China and Pakistan.

In coal combustion, it discharges large quantity of pollutants and carbon dioxide as compared to other power generation method. The steam temperature and pressure are direct related to the efficiency of fossil fuel power plant. To enhance the efficiency power of the plant there is a great need to reduce emission of carbon dioxide that act as pollution.

The result of the R and D program have shown that the construction of boiler and we need high strength alloy for the construction of piping and tubing for boiler. Now a day, the best energy source for the electricity production is coal. From the performance point of view the coal is used to increase electricity production.

At the global level we are interested to know how much the coal fired power is efficient. The efficiency of the different boilers may differ from each other, due to difference in the design of boiler, plant design and maintenance practice. Thus the theoretical design efficiency is not only related with measurement mathematically but related with actual operational efficiency of existing power plants and issue in real world.

2-Literature review:

According to Zhang DK. the methods like low temperature economics (LTE),    Down stream of air preheat from the stream Rankine cycle to preheat the condensed water .the different stage of stream turbine preheated the condensed water in multistage, then the water is provide to boiler at the temp ranging from 250- 300[1].

According to Horst TA, Tegethoof W, Eilts P   [3,5] from the exhaust gas are responsible of almost 80% of total boilers heat loss. In a CEPP almost 80% of total energy given for improving the efficiency of the heat loss in exhaust flue gases in minimized.

By Strömberg L To save portion of stream bleeds from turbines, installing LTEs, to generate heat for the preheating condensed water from 6the flue gas, instead of stream removel. The saved stream can improved the overall power efficiency by passing the stem through different stages. The( R and D) and industry communities are paying attention for the used LTE for gaining waste heat from the exhaust gases.[6]

Xu G Theanalization of LTE installation in boiler for the exhaust gases based on the real data an existing 1000MW typical power generation unit in China were used to off design performance of turbines was done by [7]. .

According to Wang C, the demonstration for potential of energy off improvement by LTE, was done by the enthalpy drop method.[8]

Pei X Detailed study about the 350MW CFPP is presented in ref [9] also the thermodynamics laws were applied to study the variation of the thermal system and increase in efficiency due waste heat recovery ref [9].

Keeping the aim to increase more efficiency from the waste gases the recovery system completely studied in ref [10], [11].

 EspatoleroS in down stream of economizer parallel to the air preheater, in a bybass flue two stage LTEs were installed stage ref [10].  

All the modification of waste heat recovery system were done by focusing on LTE, by heating the condensed water the flue gas and steam cycle and AP was recovered in the system using in CFPP. [10],

In Yang YP air preheating was divided into two process. Air preheaters and LTE was arranged between two Aps ref [11].

3-Aims and objectives:

In this paper, a new and highly integrated boiler cold-end system for the waste heat recovery, which includes the economizer, AP and LTE, was proposed. the flue gas waste heat is not only used to heat the condensed water, but also to preheat the combustion air. The energy efficiency gain and economic benefits achievable are analysed and discussed.

• Measure of waste warmth recouped

• Thermodynamic advantages

• Economic Benefits


4.1- LTE connected to waste warmth recuperation and RH Regenerative Heater applied

LTE is introduced, part of the waste warmth of the pipe gas is recuperated to warm the low-temperature stabiles water, consequently overthrow a segment of the steam drains. The steam drains are then ready to go through the accompanying phases of the steam turbines, which immediate to more power yield and diminished carbon dioxide discharge under the steady coal ignition rate. Along these lines, the low grade warmth of the fumes pipe gas is overhauled by the LTE for an increment in net plant vitality effectiveness and the power plant will be more environment-accommodating with lower GHG discharges After the multistage preheating in the RHs, the sustain water is further warmed in the economizer in the pipe channel and afterward streams into the warmers in the heater (e.g., into the water-cooled divider and super warmers).

AP Air Preheater

Downstream of the economizer, the encompassing air is warmed in the AP and afterward streams into the heater to bolster the coal burning procedure. In the wake of warming the air in the AP, the vent gas is dumped into the earth as fumes.

4.2-ESP Electrostatic Precipitator

Additionally, the ESP is orchestrated downstream of the LTE in the evaporator chilly end stoop with waste warmth recuperation. The de-cleaning proficiency of ESP will be enhanced with lower working temperature also, the hindering impact of the fly cinder in the vent gas will control the low-temperature warm exchanger from the corrosive erosion.

4.3-Exhaust gas resistance

The helper warm move surfaces introduced in the pipe conduit of the evaporator chilly end will bring about an expansion in the pipe gas resistance. For the economizer and LTE, the pipe gas pressure drop can be figured as the followings

Δpf= Eu * ρ * w2y * z

Δpf representation to the augmentation of vent gas weight drop (Pa), Eu speaks to qualities of tube resistance, q is the thickness of the vent gas (kg/m3), wy is the normal speed of the pipe gas (m/s), and z is the aggregate tube numbers along the course of exhaust gas stream. The expansion in the warmth exchange zone prompts to extra weight resistance in the rotational air preheater in the proposed kettle frosty end plan in a CFPP.


For CFPPs with a routine LTE outline, the waste warmth recouped from the fumes vent gas is equivalent to the pipe gas enthalpy drop between the channel and outlet of the LTE. The enthalpy of the vent gas per kilogram of coal can be resolved as takes after:

I= I0g+(α+1)I0α

  I0g and I0α are the hypothetical enthalpies of the vent gas and air, Separately, α is the excess air ratio.At that point the warmth discharged by the fumes vent gas can be ascertained from:

QR = βj(I0in+I0out)

β the coal combustion rate (kg/s), and Iin and Iout represent the flue gas enthalpies per kilogram of coal (kJ/kg-coal) at the inlet and outlet of the LTE, respectively. In the proposed kettle chilly end outline, the general measure of squander warm recuperated is like that in the routine plan in any case, contrasts by that a bit of the waste warmth is changed to warm the burning air. In this manner, the warmth discharged in the LTE is less.

In particular, the vent gas squander warm recuperated in the AP is reflected by the temperature increment of the hot air temperature in the proposed heater frosty end plan, as appeared in Eq.

QR-A = β.α(I0αp+I0αc)

Represents the theoretical hot air enthalpies in the purposed and the conventional boiler cold per kilogram ofcoal (kJ/kg-coal), respectively. Therefore, the heat recovered by the

LTE can be calculated using QR-A = β.α(I0αp+I0αc) in the proposed boiler cold-end design.

ESP   Electrostatic Precipitator RH Regenerative Heater

AP  Air Preheater                       LTE Low-temperature Economizer

FWP  Feedwater Pump          CP Condenser Pump

COND   Condenser                     FGD Flue Gas Desulfurization

Under the states of the economizer, AP, and LTE, the measure of warmth exchanged by radiation can be dismissed. For the gas – water warmer, e.g., the economizer and LTE, high recurrence finned tubes with inline positions are chosen.

5.1-Thermodynamic process:

The power cycle capacity and heating rate are regularly utilized as a part of the electric power industry to assess the heat execution of force cycle.

In CFPPs with pipe gas squander warm recuperation, the gross power yield can be increment by ΔW, under the steady coal ignition rate. Besides, the extra net power yield is computed as takes after:

ΔWnet = ΔW- ΔWf          (MWe)

Where ΔWnet is the additional power output (MWe) and ΔWf is the in crement in the fan power (MWe). As the APs not only recover the waste heat but the LTE also recovers waste heat from the exhaust gases in cold end bolier.

6-Project Plane:

The project team consists of two senior investigators, one graduate student, one draft man and one laboratory engineer. The project organisation and distribution of responsibilities will be based on the educational background, past experience, and project needs. All team members will be involved in all five stages of the project and one progress report will submitted at the end of each stage.


 Equipment & Materials

ESP Electrostatic Precipitator                             RS   90,000

RH Regenerative Heater                 RS   10,000

AP Air Preheater                                          RS 190,000

LTE Low-temperature Economizer                             RS  10,000

FWP Feedwater Pump     RS  10,000

CP Condenser Pump     RS   2,000

COND Condenser     RS   30,000

FGD Flue Gas Desulfurization                                          RS   70,000

6.2-Gantt chart:



Jan Feb Mar Apr May Jun July Aug Sep Oct Nov Dec

Research Possible Topics


Design Survey

Proposed Design

Solid Work Model

Research and Analysis

Cost Analysis & Material


Theoretical vs Experiment

Complete Project


Another idea for boiler cold end plan with waste warmth recuperation has been proposed in this study and an average ultra-supercritical 1000MW CFPP with the two evaporator cool end outline choices have been quantitatively analyzed in light of the thermodynamics also, financial investigations. In the proposed kettle chilly end outline, the temperature of the ignition air can increment by 160C, which produces 16.2MWth additional warmth that is invested in the heater also, the steam seep from RH5 can be somewhat substituted through the use of the LTE. Computations demonstrate that the extra net power yield can achieve 13.3MWe, which is much more prominent than that of the CFPP with a routine evaporator icy end and the exergy decimation in the proposed evaporator icy end outline is 10.3 MWth lower than that in the routine plan.


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