Description

The reciprocating compressor is the patriarch of the compressor family. In the process industry, the reciprocating compressor is probably the oldest of the compressors with wide application ranging from consumer to industrial usage. This compressor is manufactured in a broad range of configurations and its pressure range is the broadest in the compressor family extending from vacuum to 40,000 psig. The reciprocating compressor declined in popularity from the late 1950s through the mid 1970s. Higher maintenance cost and lower capacity, when compared to the centrifugal compressor, contributed to this decline. However, recent rises in energy cost and the advent of new specialty process plants have given the more flexible, higher efficiency, though lower capacity, reciprocating compressor a more prominent role in new plant design.

The reciprocating compressor is a positive displacement, intermittent flow machine and operates at a fixed volume in its basic configuration.

One method of volume variations is by speed modulation. Another, more common method, is the use of clearance pockets, with or without valve unloading. With clearance pockets, the cylinder performance is modified. With valve unloading, one or more inlet valves are physically open. Capacity may be regulated in a single- or double-acting cylinder with single or multiple cylinder configuration.

A unique feature of the reciprocating compressor is the possibility of multiple services on one compressor frame. On a multistage frame, each cylinder can be used for a separate gas service. For example, one cylinder may be dedicated to propane refrigeration, while the balance of the cylinders may be devoted to product gas.

Lubrication of compressor cylinders can be tailored to the application. The cylinders may be designed for normal hydrocarbon lubricants or can be modified for synthetic lubricants. The cylinder may also be designed for self lubrication, generally referred to as nonlubed. A compromise lubrication method that uses the nonlubed design but requires a small amount of lubricant is referred to as the mini-lube system.

An unusual nonlubed compressor is a labyrinth piston compressor, shown in Figure 3-1. The piston does not touch the sides of the cylinder

Figure 3-1. Labyrinth piston compressor. This non-lubed piston's circumferential labyrinths operate with a close clearance to the cylinder wall instead of rubbing. (Courtesy of Sulzer)

Figure 3-1. Labyrinth piston compressor. This non-lubed piston's circumferential labyrinths operate with a close clearance to the cylinder wall instead of rubbing. (Courtesy of Sulzer)

that is equipped with a series of circumferential labyrinths operating with a close clearance to the cylinder wall. Efficiency is sacrificed (due to gas bypass) in order to obtain a low maintenance cylinder. This design is mentioned primarily because it is unique and not widely manufactured.

Another feature necessary to the reciprocating compressor is cylinder cooling. Most process compressors are furnished with water jackets as an integral part of the cylinder. Alternatively, particularly in the smaller size compressors, the cylinder can be designed for air cooling.

Renewable Energy Eco Friendly

Renewable Energy Eco Friendly

Renewable energy is energy that is generated from sunlight, rain, tides, geothermal heat and wind. These sources are naturally and constantly replenished, which is why they are deemed as renewable.

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