Pumping and Compression

When recycling material to the reactor for whatever reason, the pressure drop through the reactor, separator (if there is one), the heat transfer equipment upstream and downstream of the reactor, control valves, and so on must be overcome. This means the pressure of any material to be recycled must be increased. Again, for the case of a liquid recycle, the cost of this pressure increase is usually small. On the other hand, to increase the pressure of material in the gas phase for recycle requires a compressor and is expensive. 

For gas-phase reactions, the pressure drop through the reactor is usually less than 10% of the inlet pressure6. The pressure drop through trickle-bed reactors is usually less than 1 bar. A value of 0.5 bar is often a reasonable first estimate for packed and trickle-bed reactors, although pressure drops can be higher. The pressure drop through lluidized-bed reactors is usually between 0.02 and 0.1 bar. 

Heat exchangers for liquids normally have a pressure drop in the range 0.35 to 0.7 bar (see Chapter 15). For gases, heat exchangers have a pressure drop typically between 1 bar for high-pressure gases (10 bar and above), down to 0.01 bar for gases under vacuum conditions (see Chapter 15). 

Pressure drop in the transmission pipes is a combination of pressure losses in the pipes and pipe fittings7. Pipe fittings include bends, isolation valves, control valves, orifice plates, expansions, reductions, and so on. If the fluid is assumed to be incompressible and the change in kinetic energy from inlet to outlet is neglected, then  

It should be noted that Equations 13.9 and 13.10 apply to smooth pipes, whereas the pipes used for transmission of fluids usually have some surface roughness, which increases the friction factor. However, for short fluid transmission pipes, the overall pressure drop is usually dominated by the pressure drop in the pipe fittings (valves, bends, etc). Thus, for short transmission pipes, there is little point in calculating the straight pipe pressure drop accurately. If the transmission pipe is long ( 100 m) and straight, then the Fanning friction factor can be correlated as7  

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If the piping layout is known, then the above correlations can be used to estimate the pressure drop through the pipes. This might be the case, for example, in a retrofit situation. In preliminary design, it might be necessary to make some allowance for a cost of pumping and compression without... 

System test—turn off all modules and power-up to perform startup diagnostics. Perform static leak test of the pump and compression test of the autosampler as suggested by the manufacturer. 

Organic waste materials in an aqueous medium are pumped and compressed from atmospheric pressure to the reactor s working pressure. Air is always compressed to the... 

When we consider that we lose work potential in chemical reactors, in heat exchangers, and in mixing operations and combine this with the need for work in separation processes, pumping, and compression, it becomes dear that chemical processes are usually very inefficient from an energy standpoint. Of course, energy conservation is usually of secondary importance in chemical processing safety, quality, and productivity are more important, Nevertheless, it is economically sound... 

The first phase selectively separates the n-butenes from a feedstock previously vapo< rized around lOO C. at 0. 10 Pa absolute, by circulation in an upflow stream through the adsorbent The isobutene-rich fraction of the residual C4 cut also contains a heavier hydrocarbon such as hexaDe.-an eluant used in subsequent operations, which is displaced from the pores it initially occupied. This eifruent is cooled to 4CPC and partly condensed. The liquid and gaseous fracuons are separated, and then pumped and compressed respectively at 0.6.10 Pa absolute, to allow the production, by simple distillation, of isobutene at the top and the eluant at the bottom. 

The flow diagram of the installed SCWO bench scale plant (Figure I) shows that feed, water and air are pumped and compressed separately, typically to 26-30 MPa. After preheating and mixing, the reactants are fed into the pipe reactor (PR) or double pipe reactor where oxidation takes place. After cooling and gas-liquid separation, the aqueous product and the off-gas are analysed. The whole SCWO bench scale apparatus is controlled automatically. 

Utilities savings for a once-through vs. recycle operation arise from lower pumping and compression costs as a result of the possible lower design pressure and also of lower hydrogen consumption. Additional savings are realized as a result of the lower oil and gas circulation rates required, because recycle of oil from the fractionator s bottom is not necessary. 

Mine gas is one of the main safety problems in coal production, which does great harm to coal mine safety production and people s life and property. Since 1980s, people pay more and more attentions to the comprehensive utilization of mine gas. At present, the widely used technique is pumping coal seam gas by gas drainage pumps, and compress it by gas compressor, and then used in industrial and civil fuel, or power generation, etc. According to this way, not only improve the safety of coal mine production, but also relieve the strain on energy, protect the environment, which achieves to use for extraction, from extraction to promote safe virtuous circle development of coal mines. 

Coyne, G.S. (1997) The Laboratory Companion A Practical Guide to Materials, Equipment, and Technique, Wiley, New York. Useful guide to the proper use of laboratory equipment such as vacuum pumps and compressed gases. Also gives relevant safety information. 

Hair spray consists of a resin dissolved in a solvent (usually ethanol but can be isopropanol) and a propulsion system to place the product onto the hair. The propulsion system is mainly the condensed gas aerosol (hydrocarbon blends or dimethyl ether) but pump and compressed gas systems are available. 

Other delivery mechanisms have also become available in the last few years, such as liquid or slow release sticks. In the future, these products will be developed further along with pumps and compressed gas aerosols but they tend to be more expensive to produce than the aerosol and are not as convenient for the consumer. 

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