28-12-2012, 12:30 PM
SUMMER TRAINING PROJECT REPORT BHEL
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INRODUCTION TO ORGANISATION
BHEL – An Overview
Bharat Heavy Electricals limited, BHEL, is the largest engineering and manufacturing enterprise in India with global credentials. Today it ranks among the leading power Equipment manufacturers in the world. Set up in mid-fifties, BHEL has diversified its products base over the years and today BHEL caters to the need of all key sectors of the economy. BHEL‘s products cater to the wide spectrum of customers in various fields like power generation & transmission, oil exploration & production, transportation, steel & metals, fertilizers & petrochemicals, refineries, cement plant, heavy engineering industries, non-conventional energy
sources, defence equipments, etc. More than 65% of the installed capacity for electrical power in India is contributed by BHEL. The wide network of BHEL‘s 14 manufacturing divisions, 8 service centres, 4 power sector regional centres, 18 regional offices and over 150 sites spread all over India & abroad enables the company to promptly serve its customers & provide them suitable products systems and services at competitive rates. BHEL manufactures almost all high technology products required for power sectors viz. Steam Turbines, Gas Turbines, Nuclear turbines, Generators, Boilers, Heat Recovery System Generators, Pump & Compressors, Heat Exchangers, and Control Instrumentation etc. BHEL has carried out ‘System Engineering’ and ‘Turnkey Execution’ of projects involving coal, liquid & gas based power plants not only in India but also in countries like Malta, Cyprus, Malaysia, Saudi Arabia, Oman, Libya etc. BHEL‘s technology for products/systems is at par with the latest/best in the world. BHEL has collaborated with leading companies in world like M/s Siemens, Germany; M/s General Electric, USA; M/s Alstom, France etc.
Manufacturing & Testing Facilities
BHEL Haridwar plant is equipped with most modern and sophisticated machine tools, facilities and test equipment to manufacture and test turbo generators up to 1000MW rating, which includes:
• New state-of-the-art total impregnation facility for impregnation wound stators of TARI/THRI type Turbo generators up to 350MW.
• CNC taping machine for insulation of TG winding bars.
• Most modern micalastic insulation plant for stator bars.
• Over speed and vacuum balancing tunnel.
• Waldrich rotor slot milling machine up to maximum barrel length of 7000mm, barrel diameter of 1400mm and rotor weight of 200 tonnes.
• Koellmann rotor slot milling machine up to maximum barrel length of 7000mm, barrel diameter of 1800mm and rotor weight of 225tonnes.
• Two computerised test beds to test large size Turbo generators up to 1000MW.
• Wotan CNC horizontal Boring machine.
• Centre lathe machine up to maximum length of 16m and dia. of 3.15m.
• Insulation life test assessment facility.
Beside these BHEL, Haridwar has also set up a “Generator Research Institute” with an objective to develop basic know-how and know-why through experimental studies for reliable, efficient and optimum design of turbo generators and to improve their performance in service.
Global Services-Engineering & Commercial
Global services – engineering as well as commercial – inclusive of services after sale are accorded the utmost importance in BHEL. BHEL has a service network with regional headquarters in the four regions of the country. They are backed by core Power Sector Technical Services and Field engineering Group. Services are provided in the following significant areas:
Residual Life assessment (RLA) – Due to aging, material grade of sets degrade as a function of time dependent material damage mechanisms such as creep, fatigue, corrosion, erosion, wear, embrittlement etc. The residual life of components is evaluated through sophisticated NDT stress analysis & metallurgical techniques. It fare warns the impending failure and helps in reducing costly plant breakdowns by recommending replacement of defective components, retrofits etc.
Quality & Reliability
Quality is prime concern for BHEL. Turbo generators manufactured by BHEL are certified ISO: 9001. The certificate is testimonial of BHEL‘s tryst with quality. It is endeavour to achieve excellence in all business processes BHEL has adopted and implemented new concepts to ensure compliance to standards/specifications at various stages of the project viz. engineering, manufacturing, testing, erection, commissioning etc.
Quality through Measurement (QTM) – provides web based management information for review, improvement and control of processes by measurement methodology. Weightage to processes and their attributes are decided on the basis of the impact of the process non – conformity based on the customer needs.
Critical to Quality (CTQ) – customer‘s special requirements are scrutinised vigorously during contact review and parameters critical to quality are identified.
Root Cause Analysis (RCA) – product and processes non – conformity data is utilised for improving products, processes and systems.
ABOUT THE PROJECT
The project is mainly concerned with the building of a COMBINED CYCLE POWER PLANT to generate 1500 MW of electrical power for the national power grid. This mega project of erection & commissioning of the generation plant, worth up to Rs. 4,500 Crores has been taken up by the leading Public Sector Electrical Company of India, Bharat Heavy Electricals Ltd.(BHEL). The plant is mainly designed to work on the principle of Combined Cycle generation plant where the gas turbines are the primary source of generation &work in synchronization with the Steam turbines to generate power of the rated capacity. The project site is located in the outskirts of the national capital, Delhi in a place called Bawana. The on-going project will be handed over by BHEL to the main client of the project, Pragati Power Corporation Ltd. (PPCL) on completion of work. The Bawana project is an extension in third phase to the already functional Pragati Power stations that aim at providing quality power to the national capital. This power station is unique in its own way as it is slated to be the highest rated Combined cycle power project i.e. of 750 MW (2X750 MW). The plant mainly comprises of two 750 MW units, where in each unit there are two gas turbines & one steam turbine having maximum rating of 250 MW each. As of date the two gas turbines are already functional along with the steam turbine that gives a total of 750 MW of power with one Gas turbine from the second unit (250 MW). So currently the total capacity of the generation plant stands at 1000 MW. The modern day generation plant is laced with all the latest power generation techniques that makes it eligible to meet all the national standards for environment friendly power generation & is also capable of coping with adverse conditions that may arise due to the natural hazards.
Combined cycle
In electric power generation a combined cycle is an assembly of heat engines that work in tandem off the same source of heat, converting it into mechanical energy, which in turn usually drives electrical generators. The principle is that the exhaust of one heat engine is used as the heat source for another, thus extracting more useful energy from the heat, increasing the system's overall efficiency. This works because heat engines are only able to use a portion of the energy their fuel generates (usually less than 50%). In an ordinary (non combined cycle) heat engine the remaining heat (e.g., hot exhaust fumes) from combustion is generally wasted.
Combining two or more thermodynamic cycle’s results in improved overall efficiency, reducing fuel costs. In stationary power plants, a widely used combination is a gas turbine (operating by the Brayton cycle) burning natural gas or synthesis gas from coal, whose hot exhaust powers a steam power plant (operating by the Rankine cycle). This is called a Combined Cycle Gas Turbine (CCGT) plant, and can achieve a thermal efficiency of around 60%, in contrast to a single cycle steam power plant which is limited to efficiencies of around 35-42%. Many new gas power plants in North America and Europe are of this type. Such an arrangement is also used for marine propulsion, and is called a combined gas and steam (COGAS) plant. Multiple stage turbine or steam cycles are also common.
Other historically successful combined cycles have used hot cycles with mercury vapour turbines.
Design principle
The efficiency of a heat engine, the fraction of input heat energy that
can be converted to useful work, is limited by the temperature
Difference between the heat entering the engine and the exhaust heat
leaving the engine.
In a thermal power station, water is the working medium. High
pressure steam requires strong, bulky components. High temperatures
require expensive alloys made from nickel or cobalt, rather than inexpensive steel. These alloys limit practical steam temperatures to 655 °C while the lower temperature of a steam plant is fixed by the boiling point of water. With these limits, a steam plant has a fixed upper efficiency of 35 -42%.
ABOUT COMBINED CYCLE POWER PLANTS
GAS TURBINES
Working of a gas turbine:-
A gas turbine also called Combustion turbine is a type of internal combustion engine. It has an upstream rotating compressor coupled to a downstream turbine, and a combustion chamber is in between.
Energy is added to the gas stream in the combustor where fuel is mixed with air and ignited. In the high pressure environment of the combustor, combustion of the fuel increases the temperature. The products of the combustion are forced into the turbine section. There the high velocity & volume of the gas is directed through a nozzle over the turbine blades, spinning the turbine which powers the compressor and for some turbines drive their mechanical output. The energy given up to the turbine comes from the reduction in the temperature & pressure of the exhaust gas. Energy can be extracted in the form of shaft power, compressed air or thrust or any combination of these and used to power generators.
GAS TURBINES FOR POWER GENERATION:-
Industrial gas turbines differ from aero derivative. In those the frames bearings and blading are of heavier construction. Industrial gas turbine range in size from truck mounted mobile plants to enormous complex system. This can be particularly efficient up to 60%. When waste heat from gas turbine is recovered by a heat recovery steam generator (HRSG), it powers a combined cycle configuration. The exhaust is used for space or water heating or drives an ABSORPTION CHILLER for cooling or refrigeration. Such engines require a dedicated enclosure both to protect the engines from foreign elements& the operators from noise.
CONSTRUCTION OF GAS TURBINES:-
The construction of gas turbines can take a little as several weeks to a few months, compared to years for base load power plants. Their other main advantage is the ability to be turned on or off within minutes, supplying power during the peak demands. Since single cycle power plants are less efficient than combined cycle power plants, they are usually used as peaking power plants, which operate anywhere from several hours per day to a few dozen hours per year, depending on the electricity demand to the generating capacity of the region. In area with shortage of base load & load following power plant capacity or low fuel cost may regularly operate during most hours of the day. A large single cycle gas turbine typically produces 100-400 MW of power & has 35-40% of efficiency.