An oil power plant or standby power station is the plant that uses the oil engine as a prime mover. It also combines an oil engine with an electric generator to produce electrical energy by using oil fuel or liquid fuels like natural gas.
It is generally a compact station so it can be located when we actually require it.
And the oil power plant produces limited amounts of electricity.
Additionally, it acts as an emergency supply station for many countries and produces power in the range of 2 to 50 MW.
As a standby set, it can supply power during peak periods. For instance, places like hospitals, radio stations, telephone exchanges, industries, cinema theatres, and very suitable for mobile power generation, railways, and ships.
Oil power plant working principle
The working principle of the oil power station is very simple. Firstly, the air in a cylinder is compressed to raise the temperature. Secondly, the oil inside the engine is burned. The combustion produces the working fluid at high temperature and high pressure to convert the heat energy into mechanical energy.
And as the oil engine acts as a prime mover it rotates the rotor of the electrical generator and converts this mechanical energy into electrical energy.
This working principle is a cycle done by the processes: intake, compression, expansion, and exhaust.
Components of oil power plant
The oil power station consists of many components used to achieve the best of the plant. Let us illustrate:
It is the main part of the plant used to produce the power and it may be of the two-stroke or four strokes.
Fuel supply system
It consists of a storage tank where we store the oil supplied to the plant.
It involves the fuel tank where oil pump for usage, strainer which is used to remove suspended impurities of the oil, and fuel injection (transfer) pump which is used to inject the clean oil into the engine.
It is used to remove solid impurities from the oil transferred from the main tank to a small dry tank through this strainer.
Air intake system
It is used to remove the dust particles from the atmospheric air to supply fresh air to the engine for combustion. It may be a dry (or oil) bath filter or oil-immersed filter, and it consists of pipes to supply the fresh air and filters to remove dust particles from the air.
It’s used to remove the exhaust gas from the engine to the atmosphere, and we also add a silencer to this system to reduce the noise level of the system.
It’s very important in the oil power station to have a cooling system to maintain the overall temperature of the engine at an agreeable level. This cooling system requires a water source, a water pump that circulates water through a cylinder, and cooling towers which used to cool the hot water.
It’s used to minimize the wear of the rubbing surface of the engine as we store oil in a main lubricating oil tank then draw this oil from an oil pump to pass through the oil filter to remove impurities.
Engine starting system
Tt’s used in old conditions as a starter as it uses the air to push the engine and start an initial rotation until the engine run with its own power, and the starting methods may be:
Self-starters-which is used in small oil engines where motor draws heavy current and designed to work for continuously 30 Sec after it’s cooled.
They are located close to the main engine and driven through a clutch and gears as the clutch disengaged to start the engine.
Compressed air system
They are used in large oil engine and it ’s supplied from an air tank.
It’s used to control the speed of the engine by changing the fuel provide according to engine load.
Oil power plant layout
The layout of the oil power station illustrates the main and auxiliary components of the plant and the importance of each component as:
Also known as the compression ignition engine and consists of a cylinder, cylinder head, piston, inlet valve, an inlet port, exhaust valve, valve spring, cooling fins, wrist fines, wrist pin, connecting rod, crankcase, crank pin, crank, and crankshaft.
It is classified into a two-stroke engine and four-stroke engines.
Engine starting system
It is an arrangement to initially rotate the engine, and we used compressed air for starting the engine until it runs with its own power.
Fuel handling system
We use trucks, railway wagons (barges), or oil tankers to deliver the fuel oil to the plant site. The oil is delivered to the main tanks from engine day tanks which is capable to store oil equivalent to 8-hour consumption through strainers.
Liquid Fuel Handling System
And we heat the oil by hot water or steam to reduce viscosity and in order to reduce the pumping power input.
Fuel injection system
We can say that this system is the heart of the oil engine as it can be used as:
- Firstly as a filter ensuring oil from dirt.
- Secondly, meters the correct quantity of fuel to be injected into the cylinder.
- Thirdly, regulates the fuel supply.
- Fourthly, atomize the fuel oil for better mixing with the hot oil.
- Lastly, distribute the atomized fuel properly in the combustion chamber.
Air intake system
It’s used to transfer fresh air through louvers and air filter to the cylinder by an intake manifold, and we can fit a supercharger driven by the engine between the filter and the engine to augment the power.
It’s used to discharge the engine exhaust to the atmosphere with minimum noise.
We use an exhaust manifold to connect the engine cylinder exhaust to the exhaust pipe. Thus, to demand the fluctuating pressure of the exhaust line with a muffler or silencer. In other words, to in turn reduce most of the noise resulted when gases discharged directly to the atmosphere.
Oil-Based Power Plant Exhaust System
There is also a flexible tubing system to take up the facts of expansion and isolate the exhaust system from the engine vibration. And we may also use a heat recovery steam generator to generate low-pressure steam for process work.
Engine lubrication system
It’s used to provide a sufficient quantity of cool filtered oil to give adequate lubrication to the moving parts of the engine. It consists of a lubricating oil tank, pump, filter, and oil cooler. It is classified into:
Mixed lubrication system
It’s usually used in the two-stroke engine where we mix a small quantity of lubricating oil in the fuel tank.
Wet sump lubrication system
This may be a splash system, pressure fed system, or splash or pressure feed system.
Dry sump lubrication system
It’s usually used in a large stationary marine engine where we carry the supply of oil in an external tank with some help of scavenging pump through a strainer and filter.
It consists of a water source; a pump that circulates water through a cylinder and head jacket; and a cooling tower in which it can cool the hot water from the engine.
And we must take in consideration when planning for the layout the following:
- Firstly, the approximate dimensions of the equipment.
- Secondly, the location of the equipment and the minimum clearance between each part.
- Thirdly, natural lighting, and proper ventilation provision.
- Then again, the availability of future addition to the building with minimum changes.
- Additionally, provision for installing at least one spare unit in the future.
- Finally, provision for a small workshop, stores, office, and so on.
Application of oil power plant:
Since oil power station has a capacity in the range of 2 to 5MW, it can be used in many applications such as:
- A central station for medium or small power supplies.
- And for emergency services as a standby plant to hydroelectric power plants and steam power plants.
- We can be used with thermal or hydropower plants as a peak load plant in combinations.
- For mobile power generation, transportation systems like automobiles, railways, airplanes, and ships.
- A nursery station to transport the power from stations to small power plants, or supply power to small towns.
- It’s economical for industries where they require a small power in the order of 500 KW as it offers high overall efficiency.
- And also used for electrical power generation in capacities 100 to 500 H.P.
Advantages of oil power plant
The oil power station is simple in everything, thus, it has many advantages such as:
- The low initial cost which makes it easy to quickly install and commission it.
- The design is very simple and requires a small space.
- It can start and stop with quick facilities; as small generators can start and stop in a few seconds without any standby loss in the system.
- The thermal efficiency is quite higher than other types.
- We can build it near the load center and don’t cause a problem of ash disposal exists.
- The size of the plant is quite smaller than steam plants as they have the same capacity.
- It’s easy to design it for portable use.
- The cooling is easy and requires a small quantity of water.
- There isn’t any difficulty with varying loads.
- Also, the fuel cost required for operation is low.
- Replacement losses are smaller
- And it also requires fewer members of engineers.
Disadvantages of the oil power station
To be fair, as we illustrate the advantages; we will also illustrate the disadvantages of the oil plant which are:
- The higher running costs due to the high cost of the oil.
- The general use of this plant is to produce small power requirements.
- It can’t stand up for a long period of overload conditions.
- The lubricant cost is high.
- Complex and high-cost maintenance; which makes the life of the plant small from 7 to 10 years.
- Its capacity is only about 50 MW.
- It’s difficult to construct it for a large scale.
- Also, the noise produced by the plant is high.
The efficiency of the oil power station
We all know that efficiency is the output of the process to the input, but here with power plants we have three main types of efficiency which are:
This is the specific cost of production which includes fuel, labor, materials, and services cost; as compared to the energy output of the plant for a definite period of time.
It’s the capacity factor or load factor; which measures the actual output from the plant compared to the potential maximum output.
Energy conversion efficiency
It closely relates to the heat rate; which is the quantity of heat required by the electrical generator to generate 1 kWh of electricity.
So from all this information; we can say that the overall efficiency of the oil power plant is between 35-42%.