INDUSTRIAL TRAINING AT EGBIN THERMAL POWER PLANT TRAINING REPORT ON ACTIVITIES BETWEEN 8TH AND 20TH OF FEBUARY
SUBMITTED BY: OSUDE BENEDICT SUBMITTED TO: METIN BILIN
INDEX
1.ACKNOWLEDGEMENT 2.INTRODUCTION 3.LOCAL AND SITE REQUIREMENTS 4.MAJOR INPUTS OF THE POWER PLANT 5.FUNCTIONAL DESCRIPTION 6.CONCLUSION 7.TRAINING 8.BIBLIOGRAGHY
ACKNOWLEGDEMENT
This present report would not have been possible without the help; I have received from various quarters of the company. I extend a special thanks to Mr. Adewale Shino; the training division supervisor and Mrs. Rita. S. Ogunbor for their guidance and special kind of operation throughout the duration of my training. I also convey my special thanks to all staff members for plant familiarization and understanding various plant processes.
INTRODUCTION.
Egbin power station commenced operations in 1985 with two 220 MW steam turbines each having its own dual fuel gas/oil fired boiler. Two additional and similar 220 MW units were commissioned in 1986 and a further 2 in 1987 bringing the total installed capacity of the facility to 1320 MW. Egbin Power PLC was incorporated on November 8th 2005 owning all of the assets of the station. Egbin Power PLC is the largest generating station in what was the state-owned National Electric Power Authority (now Power Holding Company of Nigeria - PHCN). PHCN was responsible for generation, transmission and distribution of electricity across Nigeria. As part of government reforms initiated in 2001, PHCN is being unbundled and the units are being divested to the private sector. Egbin Power PLC is one of the unbundled units. The company will be privatized through an international competitive tender under a World Bank funded Project. The facility is the largest thermal power station in Nigeria and is fed with gas from the Delta via the Escravos - Lagos pipeline. The company employs 552 staff and between 2000 and 2005 averaged generation of some 7,130GWh annually. The station exports into the national grid although it is close Lagos, the commercial capital of Nigeria with an estimated 18 million residents in.
Main station plant
6 x 220 MW generating sets. Gas supply system Oil storage facility Water Treatment Plant Sea water cooling system Auxiliary Boiler (Hitachi) Workshops
Installed capacity
Available Capacity (Feb-2007)
1,320 MW
880 MW (awaiting remedial work by OEM)
Energy generated
8,592 GWh
Staff
552 employees
LOCAL AND SITE REQUIREMENTS
An ideal thermal plant is that which result in a lower unit cost in the production and distribution of electricity to the consumers. The factors favouring the P.H.C.N in this regard are: 1. Availabili Availability ty of Raw Material Material Raw material should be available in sufficient quantities. For any thermal plant, liquid fuels such as L.D.O. (Light diesel Oil) and H.F.O. (Heavy furnace oil) are required in sufficient quantities every day. Since, there is well defined arrangement done by the oil sector for transporting gas from the delta region by means of pipe lines. 2. Availability of Water Supply For any thermal plant, water is always required in huge quantities for the purpose of cooling for P.H.C.N.; water is taken from a feed supplied directly from the water corporation. 3. Waste control The site must have the facility for the control and and manag anage ement ment of emitt mitte ed fume fumes s. Sinc Since e the power plant is situated at the outskirt of the
com commerc mercia ial l sta state the the lar large amou amount nt of fum fumes emitted daily won’t be much of a problem to the residential areas nearby.
MAJOR INPUTS OF THE POWER PLANT. 1. Fuel Fuel oil oil
This is a fraction obtained from petroleum distillation, either as a distillate or a residue. Broadly speaking, fuel oil is any liquid petroleum product that is burned in a furnace or boiler for the generation of heat or used in an engine for the generation of power, except oils having a flash point of approximately 40 °C (104 °F) and oils burned in cotton or wool-wick burners. In this sense, diesel is a type of fuel oil. Fuel oil is made of long hydrocarbon chains, particularly alkanes, cycloalkanes and aromat ics. The term fuel oil is also used in a stricter sense to refer only to the heaviest commercial fuel that can be obtained from crude oil, heavier than gasoline and naphtha. 2. Wate Water r
Water for the power station is supplied by the water corporation. This water is lifted as raw water is stored in big wells where it is sent for the treatment for removing turbidity in water. In the water treatment plant it undergoes many process and at last we get pure and dematerialized water, this water is stored in the DM water tanks from where the dematerialized water sent to the boiler and the filtered water which is not dematerialized is sent to plant and colony for personal use with the help of portable pumps.
FUNTIONAL DESCRIPTION OF THE POWER PLANT.
The working principle of the thermal plant can be best explained with the help of the figure above. But the Egbin thermal plant was remodelled to use liquefied petroleum gas (LPG) instead of coal to heat the water, the rest of the equipments remain the same. The primary fuel is supplied directly from the refinery, the direct feed of the fuel goes into a reservoir and then the feed to the combustion
chamber is controlled in other to supply just enough fuel to heat up the water.
THE BOILER .
The boiler comes in the form of an enclosed vessel where the combustion process takes place and the heat is then transferred to the water until it turns to steam. The steam under pressure then transfers the heat to the process. When water is boiled into steam its volume increases about 1,600 times, producing a force that is almost as explosive as gunpowder. This causes the boiler to be extremely dangerous equipment that must be treated with utmost care.
The boiler system comprises of feed water system, steam system and fuel system. The feed water system provides water to the boiler and regulates it automatically to meet the steam demand. Various valves provide access for maintenance and repair. The steam system collects and controls the steam produced in the boiler. Steam is directed through a piping system to the point of use. Throughout the system, steam pressure is regulated using valves and checked with steam pressure gauges. The fuel system includes all equipment used to provide fuel to generate the necessary heat. The equipment required in the fuel system depends on the type of fuel used in the system.
The water supplied to the boiler that is converted into steam is called feed water. The two sources of feed water are: Condensate or condensed steam returned from the processes and Makeup water (treated raw water) which must come from outside the boiler room and plant processes. •
•
THE TURBINE. TURBINE.
Turbine is a rotary engine that converts the energy of the moving steam into mechanical energy. The basic element in a turbine is a wheel or rotor with paddles, propellers, blades, or buckets arranged on its circumference in such a fashion that the moving fluid exerts a tangential force that turns the wheel and imparts energy to it. This mechanical energy is then transferred through a drive shaft to the compressor.
THE DEAERATOR .
The deaerator is a device that removes air and other dissolved gases from the feed water to steam generating boilers. Oxygen in the boiler feed water in particular, cause it causes serious corrosion damage in steam systems by attaching to the walls of metal piping and other metallic equipment and forming oxides (rust). It also combines with any dissolved carbon dioxide to form carbonic acid that causes further corrosion. Most deaerators are designed to remove oxygen down to levels of 7 ppb by weight (0.0005cm³/L) or less.
HEAT EXCHANGERS. EXCHANGERS.
Heat exchangers transfers heat efficiently from one part of the system to another. The proper design, operation and maintenance of heat exchangers will make the process energy efficient and minimize energy losses. Heat exchanger performance can deteriorate with time, off design operations and other interferences such as fouling, scaling etc. It is necessary to assess periodically the heat exchanger performance in order to maintain them at a high efficiency level. Heat exchangers may be classified according to their flow arrangement. In parallel-flow heat exchangers, the two fluids enter the exchanger at the same end, and travel in parallel to one another to the other side. In counterflow heat exchangers the fluids enter the exchanger from opposite ends. This is the
type used in the Egbin power plant because it can transfer the most heat.
In a cross-flow heat exchanger, the fluids travel roughly perpendicular to one another through the exchanger. For efficiency, heat exchangers are designed to maximize the surface area of the wall between the two fluids, while minimizing resistance to fluid flow through the exchanger. The exchanger's performance can also be affected by the addition of fins or corrugations in one or both directions, which increase surface area and may channel fluid flow or induce turbulence.
SUPER-HEATER .
The super heater is a device in a steam engine that heats the steam generated by the boiler again, increasing its thermal energy and decreasing the likelihood that it will condense inside the engine. Super heaters increase the efficiency of the steam engine, and were widely adopted. Steam which has been superheated is logically known as superheated steam; nonsuperheated steam is called saturated steam or wet steam
THE CONDENSER.
The surface condenser is very much like tube heat exchanger in which cooling water is circulated through the tubes. The exhaust steam from the low pressure turbine enters the shell where it is cooled and converted to condensate (water) by flowing over the tubes. Such condensers use steam ejectors or rotary motordriven exhausters for continuous removal of air and gases from the steam side to maintain vacuum. For best efficiency, the temperature in the condenser must be kept as low as practical in order to achieve the lowest possible pressure in the condensing steam. Since the condenser temperature can almost always be kept significantly below 100oC where the vapor pressure of water is much less than atmospheric pressure, the condenser generally works under vacuum. Thus leaks of non-condensable air into the closed loop must be prevented. Plants
operating in hot climates may have to reduce output if their source of condenser cooling water becomes warmer; unfortunately this usually coincides with periods of high electrical demand for air conditioning. The condenser generally uses either circulating cooling water from a cooling tower to reject waste heat to the atmosphere, or through water from the water corporation.
THE ECONOMISER.
Economisers, or are mechanical devices that reduce energy consumption, or to perform another useful function like preheating a fluid. The term economiser is used for other purposes as well. In simple terms, an economizer is a heat exchanger. FEED WATER HEATER.
In the case of a conventional steam-electric power plant utilizing a drum boiler, the surface condenser removes the latent heat of vaporization from the steam as it changes states from vapour to liquid. The heat content in the steam is referred to as Enthalpy. The condensate pump then pumps the condensate water through a feed water heater. The feed water heating equipment then raises the temperature of the water by utilizing extraction steam from various stages of the turbine. Preheating the feed water reduces the irreversibility involved in steam generation and therefore improves the thermodynamic efficiency of the system. This reduces plant operating costs and also helps to avoid thermal shock to the boiler metal when the feed water is introduced back into the steam cycle.
THE ELECTRICAL GENERATOR.
The electrical generator converts mechanical energy to electrical energy, generally using electromagnetic induction. A generator forces electric charges to move through an external electrical circuit, but it does not create electricity or charge, which is already present in the wire of its windings. It is somewhat analogous to a water pump, which
creates a flow of water but does not create the water inside. The source of mechanical energy is turbine steam engine.
TRAINING.
I received a formal training in terms of my individual project and familiarising with the plant. On the other hand i was given to opportunity to investigate how different types of people interact in the workplace. At PHCN, I was given invaluable exposure to the real-world of power generation. All the dry theoretical material that I have learnt over the years at university has taken on real and significant relevance and I have seen how my studies can be applied to a practical organisation.
CONCLUSION.
I have learned how science and engineering can interact in useful ways and how remarkable practice can occur even when it is educationally driven; at PHCN, while deadlines and budgets are important, creativity is not limited.
I was lucky enough to work with a group of enthusiastic and communicative people. It has been a unique opportunity and one that I will not soon forget.
BIBLIOGRAPHY
Wikipedia http://www.wikipedia.org/wiki/Main
Scribd http://www.scribd.com
PHCN http://www.phcnonline.com/TI http://www.phcnonline.com/TIMSClient/conta MSClient/contact.htm ct.htm
