Thermal Economy

Because of the elevation of boiling point by dissolved solids, the difference in temperatures of saturated vapor and boiling solution may be 3-10T which reduces the driving force available for heat transfer. In backward feed [Fig. 8.17(b)] the more concentrated solution is heated with steam at higher pressure which makes for lesser heating surface requirements. Forward feed under the influence of pressure differences in the several vessels requires more surface but avoids the complications of operating pumps under severe conditions. 

Several comprehensive examples of heat balances and surface 

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To realize a process integrated quality control the conception shown in fig. 2 was followed. The casting process which is influenced by process parameters like thermal economy, alloy composition or black wash will be pursued with particulary to the problematic nature adjusted sensoring systems. On basic factors orientated sensoring systems like microfocus radioscopy, and tomography will be employed and correlated with sensoring systems which can be applicated under industrial conditions. 

The basic fluid-bed unit consists of a refractory-lined vessel, a perforated plate that supports a bed of granular material and distributes air, a section above the fluid bed referred to as freeboard, an air blower to move air through the unit, a cyclone to remove all but the smallest particulates and return them to the fluid bed, an air preheater for thermal economy, an auxiUary heater for start-up, and a system to move and distribute the feed in the bed. Air is distributed across the cross section of the bed by a distributor to fluidize the granular soflds. Over a proper range of airflow velocities, usually 0.8-3.0 m/s, the sohds become suspended in the air and move freely through the bed. 

LCA [Leading Concept for Ammonia, formerly Low-Cost Ammonia] A process for making ammonia from air and natural gas. Essentially a simplified form of the standard ammonia synthesis process, more suitable for smaller plants. Thermal economies are achieved in the steam reforming section. Developed by ICI from 1985 to 1988. Two units began operating at the ICI plant in Severnside, UK, in 1988. The first non-ICI installation was designed by KTI for Mississippi Chemicals, Yazoo City, MS. The name appears to be no longer used. 

Ethvlene reactor, 573.574.588.593 circulating sand, 593 flame reactor, 573 Evaporators, 208-211 backward and forward feed, 211 heat transfer coefficients, 211 sketches, 209-211 thermal economy, 210 Extended surfaces, heat transfer, 188... 

Differences in thermal economies are stated in the comparisons of Table 9.2 and other tables. Some equipment cost data are in Chapter 21. When the capacity is large enough, continuous dryers are less expensive than batch units. Those operating at atmospheric pressure cost about 1/3 as much as those at vacuum. Once-through... 

Most dryers, especially those that directly contact hot combustion gases with the wet solids, operate best with liquid or gaseous fuels. With escalating prices of fuel oils and natural gas, dryers will increasingly use coal when possible. Direct-fired rotary dryers are the easiest to adapt to this source of fuel. Another trend is the development of more efficient drying systems for the use of nontraditional dryers. Better thermal economy is obtained with fluid-bed, spray, and flash dryers, but the rotary is currently more economical for very-high-tonnage operation of products with low unit value. 

For reasons of thermal economy it is necessary to prevent as effectively as possible the infiltration of ambient air into the rotary kiln at the feed (or inlet) and at the discharge (or outlet) end respectively. Specially designed seals are used which have to withstand high temperatures and also the wear caused by the abrasive dust contained in the kiln gases. Various forms of construction are employed. Figs. 11 and 12 show examples. An important requ irement is that the seals should continue... 

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