How does a compressor work in a refinery?

 

Refinery compressor workings.

Introduction:

The refining process is crucial to the production of various petroleum products such as gasoline, diesel, jet fuel, lubricants, and many others. During the refining process, crude oil is separated into different components through various chemical and physical processes. One of the critical components in the refining process is the compressor. Compressors are used to increase the pressure of gases or vapors, which are then processed in the refinery. In this article, we will discuss the working of a compressor in a refinery.

Types of Compressors:

There are two main types of compressors used in refineries - positive displacement compressors and dynamic compressors.

Positive displacement compressors work by trapping a volume of gas and compressing it into a smaller space, thus increasing the pressure. These compressors include reciprocating compressors and rotary compressors. Reciprocating compressors work by using a piston that moves back and forth in a cylinder, compressing the gas. Rotary compressors use two rotating screws or vanes to compress the gas.

Dynamic compressors work by imparting velocity to the gas, which is then converted into pressure through a diffuser. These compressors include centrifugal compressors and axial compressors. Centrifugal compressors use a rotating impeller to accelerate the gas, which is then slowed down and diffused to increase the pressure. Axial compressors use rotating blades to accelerate the gas along the axis of the compressor.

Working of a Compressor:

The working of a compressor in a refinery depends on its type. Let us discuss the working of each type of compressor in detail.

1. Reciprocating Compressors:

Reciprocating compressors work by using a piston that moves back and forth in a cylinder. The piston is driven by a crankshaft, which is powered by an electric motor or a diesel engine. As the piston moves back, it creates a vacuum in the cylinder, which draws in the gas. As the piston moves forward, it compresses the gas, which is then discharged through a valve. The process is repeated continuously, with the gas being compressed and discharged in each cycle.

Reciprocating compressors are commonly used in refineries for low-pressure applications, such as in the production of hydrogen.

2. Rotary Compressors:

Rotary compressors work by using two rotating screws or vanes to compress the gas. The gas is drawn in through an inlet port and trapped between the screws or vanes. As the screws or vanes rotate, the gas is compressed and discharged through an outlet port.

Rotary compressors are commonly used in refineries for high-pressure applications, such as in the production of ammonia.

3. Centrifugal Compressors:

Centrifugal compressors work by using a rotating impeller to accelerate the gas, which is then slowed down and diffused to increase the pressure. The gas is drawn in through an inlet and directed towards the impeller. The impeller rotates at high speed, imparting velocity to the gas. The gas is then directed towards a diffuser, where its velocity is reduced, and the pressure is increased.

Centrifugal compressors are commonly used in refineries for high-pressure applications, such as in the production of ethylene.

4. Axial Compressors:

Axial compressors work by using rotating blades to accelerate the gas along the axis of the compressor. The gas is drawn in through an inlet and directed towards the blades. The blades rotate at high speed, imparting velocity to the gas. The gas is then directed towards a diffuser, where its velocity is reduced, and the pressure is increased.

Axial compressors are commonly used in refineries for high-flow, low-pressure applications, such as in the production of air for combustion.