The heating requirement depends upon the climatic conditions and viscosity of

The heating requirement depends upon the climatic

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hazards. The heating requirement depends upon the climatic conditions and viscosity of the fuel used. If the heating is required, then it is generally done in the storage tank by passing the hot jacket water through a coil dipped in the storage tank. Injection of Fuel^to the Engine. The functions of the fuel injection system are to meter small amount of oil, inject into the cinder at proper time, atomize and mix with the air. The efficiency of the engine depends upon the propj|jriixing of fuel with air. Mixing becomes more difficult with an increase in'speed and increase in cylind«fdiameter.
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Presently, in all didesel power plants "solid injection" is used. The fuel at a pressure of 100 to 200 r>ar is injected through nozzle into the compressed air which also helps to atomise the oil. The common methods which are used for fuel injection system are individual pump, common rail and distributor system. 2. Air-supply System. A large diesel engine power plant requires considerable amount of air as 4 to 8 m3/kW-hr. The air contains lot of dust and, therefore, it is necessary to remove this dust from air before entering into the cylinder which would otherwise cause excessive wear in the engine. An air-supply system of a diesel power plant begins with an intake located outside the building provided with filters. The filters used may be oil-impingement, oil-bath or drag type depending upon the dust type and dust concentrations in the air. In many parts of western countries, the outside air temperature may reach such a level that it causes misfiring at low loads on the plant. Under such circumstances, the air intake system needs heating and necessary heating of air is provided by using the heat from the exhaust gases. 3. Exhaust System. The following points should be taken into consideration for the design of exhaust system of a big power plant. (a)The noise should be reduced to a tolerable degree. (b)It should be exhausted well above the ground level to reduce the air pollution at breathing level. (c)The pressure loss in the system should be reduced to minimum. (d)The vibrations of exhaust system must be isolated from the plant by use of flexible exhaust pipe. {e) Aprovision should be made to extract the heat from exhaust if the heating is required for fuel oil heating or building heating or process heating. In many cases, the temperature of the exhaust gases under full load conditions may be of the order of 400°C. With the recovery of heat from hot jacket water and exhaust, gases and its use either for heating oil or buildings in cold weather increase the thermal efficiency to 80%. Nearly 40% of the heat in the fuel can be recovered from the hot jacket water and exhaust gases. The heat from the exhaust can also be used for generating the steam at low pressure which can be used for process heating. Nearly 2 kg of steam at 8 bar pressure can be generated per kW per hour, when the mass of exhaust gases can be taken as 10 kg/kW-hr.
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