Types Of Compressors
Centrifugal Compressors
Similar to multistage centrifugal pumps, centrifugal compressors, as shown in Figure 10-9, use a series of rotating impellers to impart velocity head to the gas. This is then converted to pressure head as the gas is slowed in the compressor case. They are either turbine or electric motor driven and range in size from 1,000 [...]
21Sep2009 | admin | Comments Off | ContinuedHelical-Lobe (Screw) Rotary Compressors
Screw compressors are rotary positive displacement machines. Two helical rotors are rotated by a series of timing gears as shown in Figure 10-8 so that gas trapped in the space between them is transported from the suction to the discharge piping. In low-pressure air service, non-lubricated
screw compressors can deliver a clean, oil-free air. In hydrocarbon [...]
Vane-Type Rotary Compressors
Rotary compressors are positive-displacement machines. Figure 10-7 shows a typical vane compressor. The operation is similar to that of a vane pump. A number of vanes, typically from 8 to 20, fit into slots in a rotating shaft. The vanes slide into and out of the slots as the shaft rotates and the volume contained [...]
21Sep2009 | admin | Comments Off | ContinuedReciprocating Compressors #3
Low-speed units are typically integral in design as shown in Figure 10-4. “Integral” means that the power cylinders that turn the crank shaft are in the same case (same housing) as the cylinders that do the compressing of the gas. There is one crank shaft. Typically, integrals are considered low-speed units. They tend to operate [...]
21Sep2009 | admin | Comments Off | ContinuedReciprocating Compressors #2
A compressor may have any number of stages. Each stage normally contains a suction scrubber to separate any liquids that carry over or condense in the gas line prior to the compressor cylinder (or case for centrifugal compressors). When gas is compressed, its temperature increases. Therefore, after passing through the cylinder the gas is usually [...]
21Sep2009 | admin | Comments Off | ContinuedReciprocating Compressors #1
A reciprocating compressor is a positive-displacement machine in which the compressing and displacing element is a piston moving linearly within a cylinder. Figure 10-1 shows the action of a reciprocating
compressor.
In Position 1 the piston is moving away from the cylinder head and the suction valve is open, allowing the cylinder pressure to equal suction pressure [...]
21Sep2009 | admin | Comments Off | Continued