The Ins & Outs of Sizing a Reciprocating Compressor
In any compression application there are two conditions that are the most important. They are the inlet and the discharge conditions. These two conditions can be viewed as where we are coming from and where we need to go. The process required to determine how to get from one condition to another is similar to a road map. It must get us there in the most efficient and reliable manner. The first step in the selection process is to select the type of compressor. There are many types of compressors, the three main types being screw, centrifugal, and reciprocating. Each compressor type has its' own unique advantages and disadvantages, depending on the application. The goal of this paper is to go through the steps required to size a reciprocating compressor after it has been decided that this is a favorable option. The process includes utilizing fundamental compressor thermodynamics and a basic list of frames and cylinders that are available. The process accounts for the manner in which different gases affect the selection and includes adding sidestreams (positive or negative). The process also includes the comparison of the selection against all equipment limitations and the steps required to ensue that the component design limitations are not exceeded. Current technology allows us to use a manufacturer's program to size a reciprocating compressor and predict performance. Ideally, the program user can expect to input certain key operation parameters, run the program and obtain a correctly sized compressor with properly selected components. However, certain methods can be employed to modify the program output, thus improving the selection.