Chemical compressor

Hydride chemical compressors have two attractive features. Only low grade (low temperature) energy sources are required. 

Figure 16. Prototype hydride chemical compressor constructed by Ergenics and Denver Research Institute (top) front view (bottom) topview showing metal hydride tube bundle...

The rapid kinetics of Reaction 1, the high volumetric hydrogen storage densities, and the wide range of hydrogen decomposition pressures of the AB5 hydrides initiated proposals to use them as chemical compressors, cryogenic... 

Reciprocating Compressors. Prior to 1895, when Linde developed his air Hquefaction apparatus, none of the chemical processes used industrially required pressures much in excess of I MPa (145 psi) and the need for a continuous supply of air at 20 MPa provided the impetus for the development of reciprocating compressors. The introduction of ammonia, methanol, and urea processes in the early part of the twentieth century, and the need to take advantage of the economy of scale in ammonia plants, led to a threefold increase in the power required for compression from 1920 to 1940. The development of reciprocating compressors was not easy Htfle was known about the effects of cycles of fluctuating pressure on the behavior of the... 

Successful operation of the gaseous diffusion process requires a special, fine-pored diffusion barrier, mechanically rehable and chemically resistant to corrosive attack by the process gas. For an effective separating barrier, the diameter of the pores must approach the range of the mean free path of the gas molecules, and in order to keep the total barrier area required as small as possible, the number of pores per unit area must be large. Seals are needed on the compressors to prevent both the escape of process gas and the inflow of harm fill impurities. Some of the problems of cascade operation are discussed in Reference 16. 

In selec ting the machines of choice, the use of specific speed and diameter best describe the flow. Figure 10-67 shows the characteristics of the three types of compressors. Other considerations in chemical plant service such as problems with gases which may be corrosive or have abrasive solids in suspension must be dealt with. Gases at elevated temperatures may create a potential explosion hazard, while air at the same temperatures may be handled qmte normally minute amounts of lubricating oil or water may contaminate the process gas and so may not be permissible, and for continuous-process use, a high degree of equipment rehability is required, since frequent shutdowns for inspec tion or maintenance cannot be tolerated. 

Continuous-Flow Compressors Continuous-flow compressors are machines where the flow is continuous, unlike positive displacement machines where the flow is fluctuating. Continuous-flow compressors are also classified as turbomachines. These types of machines are widely used in the chemical and petroleum industiy for many services. They are also used extensively in many other industries such as the iron and steel industry, pipeKne boosters, and on offshore platforms for reinjection compressors. Continuous-flow machines are usually much smaller in size and produce much less vibration than their counterpart, positive displacement units. 

Axial Flow Compressors Axial flow compressors are used mainly as compressors for gas turbines. They are also used in the steel industiy as blast furnace blowers and in the chemical industry for large nitric acid plants. Thev are mainly used for apphcations where the head required is low and the flow large. 

High-Pressure Compressors There is a definite trend in the chemical industry toward the use of high-pressure compressors with discharge pressures of from 34.5 to 172 MPa (5000 to 25,000 IbFin ) and wim capacities from 8.5 X 10 to 42.5 X 10 mVh (5000 to 25,000 ftVmin). These require special design, and a complete knowledge of the characteristics of the gas is necessary. In most cases, these types of applications use the barrel-type centrifugal compressor. 

The choice of a bubble column or an agitated vessel depends primarily on the solubihty of the gas in the liquid, the corrosiveness of the liquid (often a gas compressor can be made of inexpensive material, whereas a mechanical agitator may have to be made of exotic, expensive materials), and the rate of chemical reac tion as compared with the mass-transfer rate. Bubble columns and agitated vessels are seldom used for gas absorption except in chemical reac tors. As a general rule. 

There may be many types of the drives in an industry, particularly when it is a process industry. The most common drives are fans, pumps, and compressors etc., employed for the various utilities, storage and process activities of the plant. The plant may be chemical or a petrochemical, water treatment or sewage disposal, paper and pulp unit or even a crane or a hoist application. 

The Guidelines for Process Equipment Reliability Data with Data Tables covers a variety of components used in the chemical process industry, including electrical equipment, analyzers, instrumentation and controls, detectors, heat exchangers, piping systems, rotating equipment (pump, compressor, and fan), valves, and fire protection systems. 

API Std 618, Reciprocating Compressors for Petroleum, Chemical, and Gas Industry Services, 4th Edition, June 1995... 

This standard could be adapted to the fuel compressor for the natural gas to be brought up to the injection pressure required for the gas turbine. Covers the minimum requirements for reciprocating compressors and their drivers used in petroleum, chemical, and gas industry services for handling process air or gas with either lubricated or nonlubricated cylinders. Compressors covered by this standard are of moderate-to-low speed and in critical services. The nonlubricated cylinder types of compressors are used for injecting fuel in gas turbines at the high pressure needed. Also covered are related lubricating systems, controls, instrumentation, intercoolers, after-coolers, pulsation suppression devices, and other auxiliary equipment. 

Boyce, M.P., How to Achieve On-Line Availability of Centrifugal Compressors, Chemical Weekly, June 1978, pp. 115-127. 

Gonzalez, Fr., Boyce, Me. P., Solutions to Field Problems of a Gas Turbine-Axial Flow Chemical Process Compressor Train Based on Computer Simulation of the Process, Proceedings of the 28th Turbomachinery Symposium, Texas A M University, p. 77, 1999. 

Carryover of oils (e.g., compressor lube oils), brine, corrosion inhibitors, well treating chemicals sand, corrosion scales, etc., from inlet separator... 

Troyan, J. E., series Hints for Plant Startup, Chemical Enginnering, Part I—Troubleshooting New Processes, November 14, 1960, p. 223 Part II—Troubleshooting New Equipment, March 20, 1961, p. 147 Part III—Pumps, Compressors, and Agitators, May 1, 1961, p. 91. 

The compressors to be covered in this book are those using mechanical motion to effect the compression. These types of compressors are commonly used in the process and gas transport/distribution industries. A partial list of these industries includes chemical, petrochemical, refinery, pulp and paper, and utilities. A few typical applications are air separation, vapor extraction, refrigeration, steam recompression, process and plant air. 

Ldmister, Wayne C. and McGarry, R, J., Gas Compressor Design, Isen-tropic Temperature and Enthalpy Changes, Chemical Engineering Progress, Vol. 45, No. 7, July, 1949, pp. 421-434. 

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