Efficient Use of Steam

Llewellyn, D. T. (1992) Steels Metallurgy and Applications (Butterworth-Heinemann). Lyle, O. (1947) Efficient Use of Steam (HMSO). 

Steam is introduced at the bottom of the stripper through a pipe grid and it mostly rises up counter current to the downwardly flowing dense stripper bed. Most strippers have baffles in order to achieve the most efficient use of steam. Normal steam rates are 2 to 4 Lb of steam per 1000 Lb of catalyst. Steam superficial velocities in the stripper are normally 0.5 to 1.0 Ft/S. 

The problem with this approach is that if the steam generated in the boilers is at a very high pressure and/or the ratio of power to fuel costs is high, then the value of low-pressure steam can be extremely low or even negative. This is not sensible and discourages efficient use of low-pressure steam, since it leads to low-pressure steam with a value considerably less than its fuel value. 

MW plant and 3.3% for the 200 MW plant. Not surprisingly, the savings become less as the plant becomes smaller. The costs ia Figure 12b are based on the capital cost curve (Fig. 12a) and fuel costs based on the modified EGAS reference steam plant efficiency of 34.3%. The cost comparisons are based on a coal price of 1.00/GJ ( 1.05/MBtu). Higher fuel costs would iacrease the attractiveness of MHD because of its more efficient use of the fuel. 

Therefore, merely reducing coal use will not he sufficient to satisfy the Protocol. Any plan to comply with the Protocol needs to assume substitution, first by non-combustion energy sources—that is by renewables or nuclear energy—and second by natural gas. This would have to be accompanied by achievement of far greater efficiencies in energy production (for example by introduction of far more fuel-efficient steam gas turbines, driven by natural gas) and by more efficient use of energy. 

De-ionized water is required for high-pressure boiler make-up and in many chemical process applications. Where a process has a large-scale steam demand, high-pressure turbine generators are often installed to generate power before providing the process with pass-out steam, thus making the most efficient use of the fuel. If the process does not return the steam as condensate, the... 

Salts or other dissolved solids in the evaporating water will plate out on the exterior of the tubes. With time, a serious loss in heat-transfer efficiency results. Use of steam condensate can avoid this particular difficulty. 

Energy savings can be achieved by the efficient use of low-pressure steam, e.g. use of 60-80 kPa gauge (10-12 psig) steam in absorption-... 

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