Compressor piston

Total Hydrocarbon Gontent. The THC includes the methane combined in air, plus traces of other light hydrocarbons that are present in the atmosphere and escape removal during the production process. In the typical oxygen sample, methane usually constitutes more than 90% of total hydrocarbons. The rest may be ethane, ethylene, acetylene, propane, propylene, and butanes. Any oil aerosol produced in lubricated piston compressor plants is also included here. 

Figure 1 -9. A sectional and end view of a liquid piston compressor. (Courtesy of Nash Engineering Co.)...

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-iubed piston s circumferential labyrinths operate with a close clearance to the cylinder wall instead of rubbing. Courtesy of Sulzer)...

In much the same manner as pumps, compressors are classified as one of two general classes positive displacement or dynamic (see Figure 3-68) [23]. These two general classes of compressors are the same as that for pumps. The positive displacement class of compressors is an intermittent flow device, which is usually a reciprocating piston compressor or a rotary compressor (e.g., sliding vane, screws, etc.). The dynamic class of compressor is a continuous flow device, which is usually an axial-flow or centrifugal compressor (or mix of the two). 

Figure 3-71. Single-acting (trunk-type) reciprocating piston compressor [23].

Most reciprocating compressors have inlet and outlet valves (on the piston heads) that are actuated by a pressure difference. These are called self acting valves. There are some larger multistage reciprocating piston compressors that do have camshaft-controlled valves with rotary slide valves. 

The main disadvantages to multistage reciprocating piston compressors is that they cannot be practically constructed in machines capable of volumetric flowrates much beyond 1,000 actual cfm. Also, the higher-capacity compressors are rather large and bulky and generally require more maintenance than similar capacity rotary compressors. 

The first three factors are present in compressors, but they are small and on the whole can be neglected. The clearance volume problem, however, is unique to reciprocating piston compressors. The volumetric efficiency e estimates the effect of clearance. The volumetric efficiency can be approximated as... 

Figure 3-73. Volumetric efficiency for reciprocating piston compressors (with ciearance) [4].

The liquid compressor has rather low efficiency, about 50%. The liquid piston compressor may be staged. The main advantage to this type of compressor is that it can be used to compress gases with significant liquid content in the stream. 

The liquid-ring or liquid-piston compressor is shown in Figure 36.8. It has a rotor with multiple forward-turned blades that rotate about a central cone that contains inlet and discharge ports. Liquid is trapped between adjacent blades, which drive the liquid around the inside of an elliptical casing. As the rotor turns, the liquid face moves in and out of this space due to the casing shape, creating a liquid piston. Porting in the central cone is built-in and fixed and there are no valves. 

Figure 36.13 Three-piston compressor generates higher vibration levels...

Figure 4.14 Rolling piston compressor (Courtesy of Rotorx Company)...

Avoid high compression ratios on piston compressors. 

Real surfaces, radiation 441,443 RbavblI.. B. N, 274, 302, 3 1 Reboilers 494, 495, 496 Reciprocal rule 448 Reciprocating piston compressor 347... 

A piston compressor (in case of a Stirling type PTR) or a combination of a compressor and a set of switching valves (GM type PTR) are used to create the pressure oscillations. The regenerator of a PTR stores the heat of the gas during a half-cycle and, therefore, must have a high heat capacity, compared to the heat capacity of the gas. 

It is possible that the maintenance problems with multi-stage screw compressors are substantially smaller than with piston compressors, but so far only one publication has been found [2.30] comparing the technical data and operation cost of piston- and screw compressors for two brands. The maintenance cost of both systems are not discussed. 

The air required for combustion is compressed by rotating piston compressors or turbo blowers. The air is preheated in heat exchangers by hot gases containing carbon black leaving the reactor. This conserves energy and thus improves the carbon black yield. Preheated air temperatures of 500-700 °C are common. 

Fig. 4.1-2. Principles of pressure generation A, Single-stage plunger pump B, Two-stage double-acting piston compressor (intercooling)...

Fig. 4.1-29. Power range of various compressor types for high-pressure [24], D, Diaphragm compressor PI, Piston compressor, dry running (piston ring, labyrinth) P2, Piston compressor, lubricated (piston ring) P3, Ultra-high-pressure compressor, lubricated (plunger piston) TR, Radial turbo-compressor TA, Axial turbo-compressor S, Screw compressor.

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