Heat pipe based air preheater for thermal power plants

Ace p.

Order the writing of a tailor-made Computer science Thesis

Free quote online

Dissertation Format .doc

Heat pipe based air preheater for thermal power plants

Download

Read an extract

Reader
Abstract
Contents
Extract

Abstract

Modern day thermal power plants try to utilize more & more heat available from burning of coal. In the process reducing the heat loss to the surroundings and increasing the efficiency. Devices like economizer and air preheater are manifestations for the same purpose. Most of the power plants in India rely on air preheaters of the Ljungstrom type – the regenerative variety or the tubular type – the recuperative variety. These air pre heaters have limitations with respect to having a large size and less efficiency of heat transfer.

The captive power plant of HINDALCO Industries Limited at Renusagar also uses air pre heaters of Ljungstrom type for its older units & of tubular type for its new units. These air pre heaters have inherent drawbacks of low heat transfer and more soot formation. These can be removed by using the Heat Pipe technology for air pre heating.

The problem before the team is to develop a “Heat Pipe based Air Pre Heater for Thermal Power Plants” based on the design specifications of the current air pre heater being used by Messrs. HINDALCO Industries Limited and to test its feasibility by making a scaled model of the heat pipe air pre heater and testing it in the laboratory. This is a collaborative project between the students of the institute and Messrs. HINDALCO Industries Limited with the latter providing information about its on-site resources, processes and parameters. And the former sharing the results of the project and findings with the industry.

Introduction
1. Introduction to the project
2. Need of computerization
3. Proposed software
4. Importance of the work
System analysis
1. Analysis methodology
2. Feasibility analysis
3. Choice of the platform
4. Software used
5. Hardware used
System design
1. Design methodology
2. Database design
3. Form/screen design
4. Input modules/forms of the project
Tools used
1. Visual basic
2. Oracle
3. MS Access
Testing and implementation
1. Testing methodology
2. Unit testing
3. Module testing
4. System testing
5. White box/black box testing
6. Implementation manual
7. Post implementation modification
Conclusion
Annexure
Bibliography

Get this table of contents for free after login.

Extract

[...] For a wrapped screen wick structure the effective thermal conductivity Where Kw - thermal conductivity of the wick Kl - thermal conductivity of liquid ε - wick porosity For the wick structure with rectangular grooves, we have Where w - groove width, wire spacing (meter) wf - frictional groove width(fin) kf -thermal conductivity of frictional δ - groove depth 4.4 MODELLING OF EVAPORATOR SECTION The evaporator section is heat pipe air pre heater of a thermal power plant takes in heat from hot flue gases and transfers it to the fluid inside the heat pipe. [...]

[...] below 0.1 atm, the vapor pressure limit may be approached while Above 20atm, the container thickness must be increased to a point where the heat pipe operation is limited by the increased thermal resistance. The important requirements of a wick structure are listed below: Should be compatible with the wick and container material High latent heat High thermal conductivity High surface tension Low liquid and vapor viscosities Wettability of wick and wall materials THE WICK The wick structure in a heat pipe facilitates liquid return to the evaporator from the condenser. [...]

[...] of air (minutes) Evaporator Inlet at outlet(oC) 11.4 Graphs - 11.5 Results & Discussions The temperature rise in scaled heat pipe air preheated model = 4oC However, theoretically calculated temperature rise for our model based on the mathematical modeling equations should be 6oC. The discrepancies in the actual and theoretical computations can be attributed to the following empirical factors - Use of non-ideal apparatus material Although we have used constants for ideal material from data books but the material collected from the markets is not of the exact composition. [...]

[...] It is given by, Φi = 1.1 μw) ^ ( 0.25 ) when Di μo 2100 G is the shell side mass velocity across the tubes Np is the number of tube passes μi is the viscosity at arithmetic average temperature of fluid μw is the viscosity of fluid at average temperature of inside tube wall surface Shell Side Pressure Drop For the case of flow across the tubes, we have, = {Bo (2f')G^2 Nr} / ( ρo ) where, f' is a special correction factor shell side flow f' = [ 0.23 + 0.11 / (St 1.08 ] (Dd μf) Nr is the number of rows of tubes across which shell fluid flows Bo is the correction factor, and, Bo = number of baffles + CONFIGURATION OF HEAT PIPE - 4.7 CONFIGURATION OF HEAT PIPE BASED AIR PREHEATER 5. [...]

[...] = Re = G*Di/12/μg = 25952 Constant fi = 0.0036 = 0.004 Correction Factor = Bi = 27.5 Constant φ = 4.35 In the existing tubular type air preheater, pressure drop is equivalent to pressure drop on the tube side, hence, pressure drop is = 985 Mpsf - Tubular APH In the proposed heat pipe based air preheater , the pressure drop is the loss in pressure occurring on the shell side. f' = 0.002 Bo = 1 No of tubes in row, Nr = 60 (practical case) Hence, = 426 Mpsf Heat Pipe APH 7. [...]

doc