A MINI PROJECT ON
STUDY OF POWER GENERATION TECHNOLOGY
IN GAS TURBINE
A Project Report submitted in the partial fulfilment of
Project based training
by
K.SUNDEEP DEV 08A01A0312
G.SATYANARAYANA 08A01A0308
Under the esteemed guidance of
K.K.Nanda DGM (TOOL ROOM)
BHEL , HYDERABAD
CONTENTS
1. Abstract
2. Acknowledgement
3. About BHEL
4. Turbines
4.1 Types of turbines
5. Introduction to gas turbine
5.1 Simple gas turbine
5.2 Gas turbine operating cycle
5.3 Classification of gas turbine
6. Open cycle gas turbine
6.1 Closed cycle gas turbine
6.2 Factors effecting gas turbine performance
6.3 Advantages of gas turbine
6.4 Disadvantages of gas turbine
6.5 Applications of gas turbine
ABSTRACT
The gas turbine represents the most satisfactory way of producing very large quantities of power in a self-contained and compact unit. The gas turbine may have a future use in conjunction with the oil engine. A gas turbine is used in aviation and marine fields because it is self contained, light weight not requiring cool water and generally fit into the overall shape of the structure. Gas turbine is generally selected for power generation because of its simplicity, lack of cooling water, needs quick installation, and quick starting. It is used in oil and gas industry because of cheaper supply of fuel and low installation cost.
ACKNOWLEDGEMENT
We are very thankful to BHEL Ramachandrapuram Unit for permitting and providing all the requisite facilities to carry out this project in the Technology department.
We are extremely grateful to our onsite project guide Sri K.K.NANDA (Dy.General Manager, TOOL ROOM) for his valuable guidance in our project.
We convey our heart full thanks to Sri K. Ajay Kumar (Engineer, Technology/T&C) who was responsible for the entire project to happen.
We would like to thank our Head of the Department K.P.SIREESHA for his full- fledged encouragement in our project.
ABOUT BHEL
Bharat Heavy Electricals Limited (BHEL) is the largest Engineering and Manufacturing Enterprise in India in the energy related and infrastructure sector today. BHEL is one of the “NAVARATNA” Companies in India, which has played a leading role in the development of Power Generation and Transmission and is poised to help the country achieve its targeted generation capacity of two lakh megawatts by the end of 11th plan. In 2010-11, BHEL has amassed the provisional turnover of Rs 43,451 Crs. with an outstanding Order Book of more than Rs.1, 64,130 Crs. It has presence in more than sixty countries spanning all the six continents of the world.
The beginning of BHEL can be traced to its roots in the Planning Commission in Feb. 1947 when the Advisory Board of the Commission recommended the need to set up indigenous power equipment manufacturing plant. With the establishment of Heavy Electricals (India) Limited at Bhopal in 1956 under the collaboration of AEI (UK), India laid its foundation for self sufficiency in production of Heavy Electrical Equipments. In the next five years, three more plants were started by Govt. of India at Tiruchy, Hyderabad and Haridwar under a different company known as Bharat Heavy Electricals Limited. In pursuance of the recommendations of the action committee on Public Enterprises, the operations of all the four plants were integrated from July 1972. The BHEL Corporation was formed in January 1974 and HE(I)L, Bhopal was merged with BHEL.
Today BHEL has 15 manufacturing divisions, 4 Power Sector Regional Centres, 4 Overseas offices, 1 Subsidiary and over 100 project sites, service centers etc. BHEL caters to six major lines of business i.e. Power, Industry, Transmission, Transportation, Oil and Electronics. The company has the capabilities for executing power projects from concept to commissioning.
BHEL has acquired certifications to Quality Management Systems (ISO 9001), Environmental Management Systems (ISO 14001) and Occupational Health & Safety Management Systems (OHSAS 18001) and is also well on its journey towards Total Quality Management. BHEL manufactures a complete line of heavy duty industrial gas turbines for all utility and industry applications. They are installed in refineries, petro chemical plants, gas compression stations. and power generation plants in India and abroad.
Product profile of BHEL:
1. Gas Turbines
2. Steam Turbines
3. Compressors
4. Turbo Generators
5. Heat Exchangers
6. Pumps
7. Pulverizes
8. Switch Gears
9. Oil Rings
Evolution and growth of BHEL Hyderabad unit
The Hyderabad Unit of BHEL is located at Ramachandrapuram which is around 30KM from the historic city of Charminar. Foundation Stone of the Plant was laid in 1959 and the production commenced in the year 1965. The Unit was set up mainly to manufacture 60MW and 110MW Steam Turbo generator sets for State Electricity Boards and also 12 MW TG Sets.
From this small beginning, the Ramachandrapuram Unit has been growing steadily in different phases of development and today it caters to a wide spectrum of business in Power, Industry, Transmission, Oil and Gas. It now boasts the largest number of products under a single roof as compared to any of the other BHEL Units.
BHEL –the largest Gas Turbine manufacturer in India, with the state-of-art facilities in all areas of Gas Turbine manufacture provide complete engineering in house for meeting specific customer requirement. With over 100 machines and cumulative fired hours of over four million hours .BHEL has supplied gas turbines for variety of applications in India and abroad .BHEL also has the world’s largest experience of firing highly volatile naphtha fuel on heavy duty gas turbines.
Specific features of BHEL
1. Capability to fire a wide range of gaseous and liquid fuels and a mix of such fuels
ranging from clean fuels like natural gas. Distillate oil, naptha.
2. Facilities like Black start, fast start and emergency start.
3. Suitable for power generation and mechanical drive applications. Models below
100MW suitable for 50Hz and 60Hz.
4. All machining equipment like generators, compressors etc manufactured in
house. Design of combustion system as per international emission
norms. Machines designed as per major international codes like API etc.
5. Suitable for IGCC applications.
6. Suitable for indoor and outdoor applications.
7. Use of water or steam injection for abatement of NOX emmissionsand power
augmentation.
BHEL equipped with precision and sophisticated machine tools like CNC Broaching machine5 Axis Milling Machine and over speed vacuum balancing tunnel offers conversion, modification and up gradation services-through joint venture with Gefor all existing gas turbines. Services are also offered for all field support, retrofits and repairs, inspections and technical consultancy on “operation & maintenance of Gas Turbine Based Power Plants”
TURBINE
A turbine is a rotary engine that extracts energy from a fluid flow and converts it into useful work. The simplest turbine have one moving part, a rotor assembly, which is a shaft or drum with blades attached. Moving fluid acts an the blade or the blades react to the flow, so that they move and impart rotational energy to the rotor. Early turbines examples are wind mills and water wheels.
Its chief operation is to convert energy into mechanical form in the
Cylinder which is the heart of various reciprocating engines principally diesel and
Spark ignition..The advantages offered by the turbine are its relative compactness and the fact that the reciprocating output of the turbine is usually what is want to turn a wheel, propeller, generator or pump.
Gas, steam and water turbines usually have a casing around the blades that contains and controls the working fluid.
4.1Types of Turbines:
1. Steam Turbines
2. Gas Turbines
3. Transonic Turbines
4. Contra rotating Turbines
5. Sartor less Turbines
6. Ceramic Turbines
7. Shrouded Turbines
8. Shroud less Turbines
9. Blade less Turbines
10. Water Turbines
a) Pelton wheel Turbine
b) Francis Turbine
c) Kaplan Turbine
11. Wind Turbines, it operates without nozzle
INTRODUCTION TO GAS TURBINE
Gas turbine is rotary type of I.C. engine. The cyclic events of gas turbine are similar to reciprocating type I.C. engine, but each event in the gas turbine is carried out in different devices.
A simple gas turbine is comprised of three main sections a compressor, a combustor, and a power turbine. The gas-turbine operates on the principle of the Brayton cycle, where compressed air is mixed with fuel, and burned under constant pressure conditions. The resulting hot gas is allowed to expand through a turbine to perform work. In a 33% efficient gas-turbine approximately two / thirds of this work is spent compressing the air, the rest is available for other work i.e. (mechanical drive, electrical generation).
The air is first compressed in a rotary compressor before passing to combustion chamber where fuel is injected and ignited. The hot burnt gases expand through the blades of a turbine where the kinetic energy of burnt gases is utilized to produce power. Finally the gases are exhausted from the turbine unit.
The part of power developed is used to drive the compressor, thus the overall efficiency of the gas turbine unit is lowered. Gas turbines are comparatively small weight and size as that of steam turbines.
5.1 SIMPLE GAS TURBINE
A schematic diagram for a simple-cycle, single-shaft gas turbine is shown in figure. Air enters the axial flow compressor at point -1 at ambient conditions. Since these conditions vary from day to day and from location to location, it is convenient to consider some standard conditions for comparative purpose. The standard conditions used by the gas turbine industry are 59°F (15°C), 14.7-PSI (1.013 bar) absolute, and 60% relative humidity, which are established by the International Standards Organization (ISO). These conditions are frequently referred to as ISO conditions.
Air entering the compressor at point- 1 is compressed to some higher pressure. No heat is added; however, the temperature of the air rises due to compression, so that the air at the discharge of the compressor is at a higher temperature and pressure.
Upon leaving the compressor, air enters the combustion system at point-2, where fuel is injected and combustion takes place. The combustion process occurs at essentially constant pressure. Although very high local temperatures are reached within the primary combustion zone (approaching stoichiometric conditions), the combustion system is designed to provide mixing, burning, dilution, and cooling.
Thus, by the time the combustion mixture leaves the combustion system and enters the turbine at point-3, it is a mixed average temperature. In the turbine section of the gas turbine, the energy of the hot gases is converted into work. This conversion actually takes place in two steps. In nozzle section of the turbine, the hot gases are expanded and a portion of the thermal energy is converted into kinetic energy. In the subsequent bucket section of the turbine, a portion of the kinetic energy is transferred to the rotating buckets and converted to work. Some of the work developed by the turbine is used to drive the compressor, and remainder is available for useful work at the output flange of the gas turbine. Typically, more than 50% of the work developed by the turbine sections is used to power the axial flow compressor.
5.2 GAS TURBINE OPERATING CYCLE
p-v diagram and T-S diagrams were given above.
The four steps of the cycle are:
- (1-2) Isentropic Compression
- (2-3) Reversible Constant Pressure Heat Addition
- (3-4) Isentropic Expansion
- (4-1) Reversible Constant Pressure Heat Rejection
5.3 CLASSIFICATION OF GAS TURBINES
Gas turbines are classified as follows:
1. According to path of working fluid:
a) Open-cycle gas turbine
b) Closed-cycle gas turbine
c) Semi-closed cycle gas turbine
2. According to basis of combustion process:
a) Constant pressure type gas turbine
b) Constant volume type gas turbine
OPEN-CYCLE GAS TURBINE
The rotary compressor takes in air from atmosphere and raises the pressure to required level. The compressed air from compressor enters combustion chamber where it mixes with fuel, and ignition takes place at constant pressure. The hot gases expands through turbine blades producing power, after expansion gases are exhausted into atmosphere. Part of the turbine power is used to drive the compressor and remaining is utilized to generate electricity.
Open gas turbine cycle is the most basic gas turbine unit. The working fluid does not circulate through the system, therefore it is not a true cycle. It consists of a compressor, a combustion chamber and a gas turbine. The compressor and the gas turbine are mounted on the same shaft. The compressor unit is either centrifugal or axial flow type
6.1 CLOSED CYCLE GAS TURBINE
In this case the same working fluid (air) is continuously circulated. Air is first compressed adiabatically in a compressor and high compressed air enters the heat exchanger where air is heated at high pressure by external source. Here air is not in direct contact with fuel i.e., air is not in contact with products of combustion. Hot air is now expanded adiabatically through turbine blades producing power. The air leaving the turbine enters the coolers where it is cooled to initial temperature by circulating cooling water. Cooled air is recirculated to the compressor and the cycle is repeated.
6.2 FACTORS AFFECTING GAS TURBINE PERFORMANCE
Since the gas turbine is an ambient air-breathing engine. Its performance will be changed by anything affecting the mass flow of the air intake to the compressor, most obviously changes from the reference conditions of 59°F (15°C) and 14.7 psia (1.0 13 bar). Figure-2.6 illustrates how ambient temperature affects output, heat rate, heat consumption, and exhaust flow for a typical single shaft gas turbine. Each turbine model will have its own temperature-effect curve, as it depends on the cycle parameters and components efficiencies as well as air mass flow.
Correction for altitude or barometric pressure is more straightforward. The less dense air reduces the airflow and output proportionately heat rate and other cycle parameters are not affected. Similarly, moist air, being less dense than dry air, will also have an effect on output and heat rate. In past, this effect was thought to be too small to be considered (figure 2.8). However, with the increasing size of gas turbines and utilization of humidity to bias water and steam injection for NOx control, this effect has greater significance. It should be noted that this humidity effect is a result of the control system approximation of firing temperature used on GE heavy-duty gas turbines. Single shaft turbines that use turbine exhaust temperature biased by compressor discharge pressure will reduce power as a result of ambient humidity because the density losses due to compressor inlet air temperature. The control system is set to follow the inlet air temperature function. Inserting air filtration, silencing, evaporative coolers, chillers in the inlet, or exhaust heat recovery devices causes pressure losses in the system. The effects of these pressure losses are somewhat unique to each design.Fuel type will also impact performance. The natural gas produces more output than does distillate oil. This is due to the higher specific heat in the combustion Products of natural gas, resulting from the higher water vapor content produced by the higher hydrogen/carbon ratio of methane.As a result of these influences, each turbine model will have some application guidelines on flows, temperatures, and shaft output to preserve its design life. In most cases of operation with lower heating value fuels, it can be assumed that output and efficiency will be equal to or higher than that obtained on natural gas. In the case of higher heating value fuels, such as refinery gases, output and efficiency may be equal to or lower than that obtained on natural gas.
Advantages of gas turbines:
· Comparatively small weight and size.
· Due to absence of reciprocating parts, frictional losses are minimum. Thus mechanical efficiency is high.
· Torque produced is uniform and continuous.
· Balancing is perfect.
· Poor quality of fuels can be used.
· Small working pressures are required.
· Much higher speeds may be developed.
· Combustion is continuous.
Disadvantages include:
· Part of power produced is utilized for driving the compressor.
· Not a self starting unit.
Fuels used in gas turbine:
· Liquid fuels- oil and refined kerosene.
· Gaseous fuels- blast furnance gas, coal gas.
· Solid fuels - pulverized coal.
Applications of gas turbine:
The gas turbine is used in a wide range of applications. Common uses include power generation in plants and military and commercial aircraft. In Jet Engine applications, the power output of the turbine is used to provide thrust for the aircraft.