Compressors pipe sizing

For smaller, high-speed compressors the piping sizing rules of thumb discussed above, in conjunction with pulsation bottles sized from Figure 11 -24, should be sufficient for individual field compressors. These niles of thumb can also be used for preliminary sizing of piping and bottles in preparation for an analog study. 

Use 22-in. or 24-in. pipe, or check size of suction opening and if reasonably close (in building, close to compressor), within about 2 in., use the same pipe size as cylinder suction. Do not use this approach if the suction drum is removed from the compressor and the suction connection is smaller than the size calculated. Use the larger pipe size. 

Compressor piping should be sized in the normal manner, and the pressure drop taken through an orifice plate or a short pipe spool placed on the inlet end of the suction bottles or on the outlet end of the discharge bottles. 

Paige, P. M., Shortcuts to Optimum-Size Compressor Piping, Chem. Eng, p. 168, March 13, (1967). 

The intake pipe on an air compressor should be as short and direct as possible. If the total run of the inlet piping is unavoidably long, the diameter should be increased. The pipe size should be greater than the compressor s air-inlet connection. 

Discharge piping should be the full size of the compressor s discharge connection. The pipe size should not be reduced until the point along the pipeline is reached where the flow has become steady and non-pulsating. With a... 

Pressure drops on the high-pressure side will be small enough to have little effect on the performance of the complete system. Pressure losses in the suction pipe and its fittings, especially if this is long, should be checked, and a correction made for the actual compressor suction pressure. For low-temperature applications, pipe sizes may have to be increased to avoid excessive frictional losses at these low pressures. 

Conveying characteristics also will provide useful information when an existing plant needs to be upgraded to achieve say, a higher conveying rate of solids. For example, it will be possible to determine whether the system and the material will be able to cope with the increased pressure and/or air flow requirements (i.e., whether the combination of pipe size and blower/compressor rating will be sufficient). 

The simplest way of cutting costs is to standardize extraction plants. In batch processes with solid feed materials it is advisable to standardize the plants by using the payload volume of feed-material and calculating the capacity corresponding to the given bulk density and the elaborated cycle time. To justify these efforts a certain market size for the materials in question must be given, and the number of plants of the selected size that can be sold. The individual sizes depend on the availability of individual plant components, such as pumps, compressors, piping and armatures. For standardized pressures see Chapter 7.3.1. 

An important design tool is the use of "Dynamic Simulation". This computer modeling technique was used to verify that the control systems were adequate for the purchased equipment (such as pumps, compressors, control valves, heat exchangers and pipe sizing) and were in fact going to meet our stated control objective. 

For pipe sizing, process equipment sizes are required. These include types and sizes of vessels, heat exchangers, pumps, compressors, intercoolers, scrubbers, silencers, floor space of lube and seal-oil console, furnace and heater details, control and switch house arrangements. 

The 2-K method for both liquid and gas discharges through holes and pipes provides the capability to include entrance and exit effects, pumps and compressors, changes in elevation, changes in pipe size, pipe fittings, and pipe lengths. The discharge coefficient is inherent in the calculation and docs not require an arbitrary selection. 

Like compressors, pipes do not come in all possible sizes. To select an available size, use a table of standard pipe sizes and choose one close to the diameter estimated for the assumed velocity. The pipe Schedule Number is an indicator of... 

Table 6-3 Assumed Pipe Sizes for Compressor Outlet Pressure Sensitivity Study.21...

Prepare/supervise preparation of piping or mechanical flow diagram (or P and ID), with necessary preliminary sizing of all pipe lines, distillation equipment, pumps, compressors, etc., and representation of all instrumentation for detailing by instrument engineers. 

This indicates a 350 size compressor with 12 in. diam. suction piping and 8 in. discharge. 

Use either a 40-in. l.D. header for these three compressors (two running or equivalent with three) or bring in two parallel headers, cross tied, of about half the flow area each, which equals (5,210) (3.408)/ (2,000) (2) or 4.53 fti. This corresponds to a pipe diameter of 2 ft, 5 in., say 2 ft, 6 in. This is still a large pipe, and space arrangements may dictate which is preferred. If this header is coming to the compressors from a great distance, the pressure drop must be checked to be certain that the system drop will ensure specified pressure at the suction of the cylinders. In some cases, the header size can be made slightly smaller if the pressure... 

Size the discharge surge drum and associated piping for a single-acting, single-cylinder, motor-driven compressor with the following performance characteristics ... 

Design suction and discharge bottles for an ethylene compressor. Suction drum is to be sized for an orifice meter a short distance upstream. Discharge drum is to be sized for prevention of piping vibration. 

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