Multistage expander

Turboexpanders can be classified as either axial or radial. Axial flow expanders nave either impulse or reaction type blades and are suitable for multistage expanders because they permit a much easier flow path from one stage to the next. However, radial turboexpanders nave lower stresses at a given tip speed, which permits them to run at higher speeds. This results in higher efficiencies with correspondingly lower energy requirements. As a consequence, most turboexpanders built today are of the radial type. 

Most of the large tail gas expanders are axial type. Multistage uncooled expanders, illustrated in Figures 4-21 through 4-23, are... 

Continuous, surface blowdown arrangements employ a multistage nozzle valve that permits the BW to expand and flash gradually and safely across each successive orifice and chamber with almost no noise. This effect reduces the flow velocity and virtually eliminates the risk of wire drawing. The BD valve is provided with a regulating lever and calibrated dial (or an electric actuator) for either manual or automatic BD rate adjustment. Continuous blowdown arrangements are entirely suitable for incorporation into FSHR systems. They are commonly employed for WT boilers. 

Guyton, K. Z. Bhan, P. Kuppusamy, P. Zweier, J. L. Trush, M. A. Kensler, T. W. Free radical-derived quinone methide mediates skin tumor promotion by butylated hydroxytoluene hydroperoxide expanded role for electrophiles in multistage carcinogenesis. Proc. Natl. Acad. Sci. USA 1991, 88, 946-950. 

An increase in the average temperature during the heat-addition process can also be accomplished by regenerating the steam. A portion of the partially expanded steam between the stages of a multistage turbine is drawn off to preheat the condensed liquid before it is returned to the boiler. In this way, the amount of heat added at low temperature is reduced. So the average temperature during the heat-addition process is increased. 

A number of other optimization strategies will be discussed later in this chapter. The savings resulting from replacing the letdown valves with expander turbine generators will be discussed in Section 2.13. The optimization of multistage chillers will be covered in connection with hydrogen liquefaction in Section 2.15.3, and coolant distribution controls will be covered under pump optimization in Section 2.17.2. 

Needless to say, kinetic parameters established in this way are empirical factors dependent on the definition of other variables,e.g., averaging of particle size distribution to determine R. Nevertheless, the model provides a rational approach to the complex physical and chemical phenomena of multistage, multireaction leaching. It is intended to expand the model to include countercurrent operations. 

That efficiency of HHP could be improved at use of the multistage modes, replacing hydrides (instead of one hydride) should have lower values of a heat capacity. Also it is necessary to remember, that the most systems suggested for triple heat pumps, more reduce, than expand areas, temperatures possible for double hydride systems. Thus hydraulic and gas hydrogen systems for installations with three hydrides considerably become complicated. 

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