Regenerative heat exchange

Regenerative heat exchangers of both the fixed-bed and moving-bed types (67) have been considered for MHD use. The more recent efforts have focused on the fixed-bed type (68), which operates intermittently through recycling. A complete preheater subsystem for a plant requites several regenerators with switch-over valves to deflver a continuous supply of preheated air. The outlet temperature of the air then varies between a maximum and a minimum value during the preheat cycle. 

There are two types of heat exchangers Regenerative and Recuperative. The term regenerative heat exchanger is used for a system in which the... 

The reverse flow reactor (RFR) concept was originally patented by Cottrell in 1938 [64] in the United States and further developed and appHed to different purposes by several researchers, for example, Matros and coworkers [65]. This technology has found its application also in the field of catalytic oxidation [66]. The incinerator containing two sets of regenerative-type heat exchangers and at least two catalyst honeycombs uses flow reversal to recover the heat produced in exothermal oxidation reactions [67]. A regenerative heat exchanger can typically achieve a heat... 

To date, electrochemical C02 transport has not been applied to situations other than manned spacecraft life support. It appears possible that commercial MCFC s can provide an economical means for providing food-grade C02 [34]. In this scheme (Fig. 23b) the MCFC acts as a concentrator for C02 (and some 02) from the flue gas emitted from a power plant burning relatively clean fuel (e.g. natural gas). Electric power input is required, as is considerable regenerative heat exchange. Despite these charges, the process would be economical if the MCFC stacks become commercially available at projected prices [34]. 

SWITGTHERM A catalytic process for oxidizing volatile organic compounds (VOCs). It involves regenerative heat exchange, which permits autothermal operation at VOC concentrations in the range 250 to 650 ppm. Developed in Poland and now used in over 100 installations there. 

Rotary kiln incinerators, 13 175-176 Rotary kilns, 15 52-53, 603, 26 611-612 puffing and loss of flame in, 13 182 in thermal waste treatment, 25 833-834 Rotary lobe pumps, 21 73 Rotary molds, 18 50 Rotary regenerative heat exchanger,... 

The thermal efficiency of the Rankine cycle can be increased by the use of regenerative heat exchange as shown in Fig. 2.15. In the regenerative cycle, a portion of the partially expanded steam is drawn off between the high-and low-pressure turbines. The steam is used to preheat the condensed... 

Regenerative heat exchange in chemical reactors offers clear benefits, such as simplicity, robustness, low costs, and high efficiencies, against which must be set its inherently unsteady-state operation, the limited potential for an exact regulation of temperature profiles, and the restriction of its use to gaseous reaction media. 

In the evaluation of the regenerative heat exchange option, it is instructive to consider the heat exchange techniques presently employed in the following chemical processes styrene synthesis, steam reforming, and hydrogen cyanide production (Table 1). 

TABLE 2 Advantages and Disadvantages of Reactive, Recuperative, and Regenerative Heat Exchange in Hydrogen Cyanide Manufacture... 

Experimental measurements yielded only a fivefold extension of the reaction cycle time, a difference largely caused by heat storage effects in the small-scale equipment used, which disproportionately enhanced the cooling effect observed in the inert bed control experiment. Despite this less satisfactory result, the desorptive cooling concept would still seem to offer potential for dramatic improvement in performance for regenerative heat exchange processes. 

The benefits obtained by integrating adsorption into regenerative heat exchange demonstrate the synergies available between these two related processes. Similar advantages accrue when heat regeneration is incorporated into adsorptive reactors, in which concentration profiles are manipulated to improve reactor performance through selective ad- and desorption of components in the reaction medium. 

See the figure below. In the regenerative heat exchanger, the air temperature is raised in step B -> B, while the air temperature decreases in step D -> D. Heat addition (replacing combustion) is in step B - C. 

Figure 24. Autothermal reaction control with direct (regenerative) heat exchange for an irreversible reaction [14], A) Basic arrangement B) Local concentration and temperature profiles prior to flow reversal in steady state C) Variation of outlet temperature with time in steady state.

C. What is a regenerative heat exchanger How does a static pe of regenerative heat exchanger differ from a dynamic type ... 

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