A compressor replaces a volumetric machine that uses a piston to compress the gas and deliver it at high pressure. Reciprocating compressor have a piston that moves downward, reducing the pressure in the cylinder and creating a vacuum. This pressure difference forces the intake chamber valve to open and carry gas or air. As the cylinder rises, the pressure increases, causing gas or air to escape from the cylinder through the exhaust chamber. Reciprocating compressor is used in different industries and for different purposes. These compressors have low power than centrifugal compressors. The main applications of reciprocating compressors are listed below:
- Processing and transportation of natural gas
- Chemical plant
- Clarification
- Cooling technology
As mentioned above, reciprocating compressors appear in almost every workplace, including diving, dental offices, automotive repairs, and agriculture. Pneumatic tools such as drill bits and angle grinders are of great importance in the industry because they are generally lighter and safer than electric-powered tools, which underlines the importance of reciprocating compressors.
MAJOR COMPONENTS OF A RECIPROCATING COMPRESSOR
- Frame
- Cylinders
- Distance Piece
- Piston
- Piston rings
- Cross Head
- Crankshaft
- Connecting Rod
- Valve
FRAME
In a compressor, the first thing you will notice is its heavy and sturdy frame, which includes all the rotating parts such as cylinders and rails. This frame is also called Lengeh and has a square or rectangular shape. Its function is to support the crankshaft. However, there are separate compressors or integral compressors; for the second case, the compressor and the power cylinder of the engine are mounted on a frame and driven by the same crankshaft.
Cylinder
Cylinders are pressure vessels that contain gas for compression, so they are one of the most important components of a reciprocating compressor. In large cylinders, the low-pressure parts made of cast iron and can remove from the mainframe. Alternatively, a small cylindrical high-pressure steel compressor is connected directly to the compressor body. The cylinder supports the valve delivery plate and the inlet port. It sometimes has an interchangeable sleeve or sleeve so that the covered portion of the cylinder has a removable surface. The coating is not slippery. Therefore, they ensure that if the cylinder is worn or damaged, it can be easily replaced by purchasing an expensive new system.
The role of the cylinder in the reciprocating compressor is to cool the engine temperature during the engine compression cycle, which generates heat.
This can be done by using a water jacket or cylinder fins to provide air cooling.
DISTANCE PIECE
The distance separates the compressor cylinder from the frame. In the unique design, a structure uses that increases the distance between the diaphragm and the packing cylinder to prevent any part of the piston shaft from entering the crankshaft and the cylinder packing gland. In the double version, the same structure uses, where no part of the rod enters the chamber and the crankshaft locates close to the cylinder.
On the other hand, the long-stroke section helps to separate the part of the piston shaft that enters the crankshaft. The other part of the rod entering the cylinder transfers its lubrication to the long-stroke part.
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PISTON
The working conditions of the reciprocating compressor are very dependent on the piston. Because the piston is the part that compresses the air, the piston must be light, strong, and compatible with compressed gas. It also transfers energy from the crankshaft to the gas inside the cylinder to prevent the refrigerator from leaking out of the space. Between the piston and the cylinder wall, this part is usually covered by the piston ring. The replacement compressor piston can also be made of aluminum or cast iron and move up and down the cylinder. Its movement is due to the absorption and compression of the refrigerant.
PISTON RINGS
The piston ring screws onto the piston. As the piston moves up and down the cylinder, the piston ring makes contact with the cylinder wall. Due to the amount of friction created during this movement, the ring must be changed regularly so that the compressor is in good condition. In some cases, a support belt or ring is used as an additional piston ring. Although the ring needs to be softer than the cylinder wall and cylinder liner, different piston rings can be used; these rings are metallic and non-metallic.
CROSSHEAD
The cross allows the piston to enter the perforated cylinder. Using a crossover allows the compressor to use a narrow piston, resulting in longer stroke and higher efficiency.
CRANKSHAFT
The crankshaft is the main shaft of the reciprocating compressor, and the other is the crankshaft. The shaft rotates around the axis of the frame and moves the piston, piston rod, and connecting rod. This part made with a forged steel crankshaft. Used for large compressors with an operating capacity greater than 150 kW (200 hp). For machines using motors below 150 kW, use a malleable iron crankshaft. As the crankshaft rotates, the crankshaft also rotates, allowing the piston to react with the cylinder.
VALVE
The function of the compressor valve is to allow gas to flow in the right direction while preventing gases from flowing in an unwanted direction. Therefore, these valves are located at each operating end of the cylinder. At one end, there is a series of inlet valves that allow gas to enter the cylinder, and at the other end, there are two outlet valves. The cross allows the piston to enter the perforated cylinder. Using a crossover allows the compressor to use a narrow piston, resulting in longer stroke and higher efficiency.
Advantage of Reciprocating Compressor
- A reciprocating has the self-priming capability
- There is no need for priming
- It doesn’t have cavitation problems.
Disadvantages of Reciprocating Compressor:
- It has less power than a centrifugal compressor
- It can’t deliver pulsating free flow
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