Recuperative Processes

Continuous recuperative furnaces employing metallic recuperators (heat exchangers) have been in use since the 1940s. Operation of these furnaces is simplified and the combustion process is more precisely controlled no reversal of air flow causes temperature variations. The recuperator metal must be caretiiUy selected because of chemical attack at high temperature. Recuperative furnaces are often used in the production of textile fiber glass because they maintain a constant temperature. 

Low flow, low concentration streams are best handled by a catalytic recuperative oxidizer. When the concentration of the stream is between 15% to 20% LEL (Lower Explosion Limit) then both a catalytic recuperative or thermal recuperative is the best technologies. For process streams between 20% to 25% LEL then thermal recuperative is the preferred solution. 

Process Stream % LEL Catalytic Recuperative Oxidizer Thermal Recuperative Oxidizer Regenerative Catalytic Oxidizer Regenerative Thermal Oxidizer Rotor Concentrator with Thermal Oxidizer... 

One of the advantages of the thermal recuperative oxidizer is that it is possible to process organics that may be a poison or be detrimental to catalyst. In addition, if the organic concentration is very high, for example the organic level is of the 20 to 25% LEL, then thermal recuperative oxidation is appropriate. 

A secondary fan draws the air and forces it through the secondary heat exchanger, where the reduced air volume temperature is raised to the required desorption temperature. The preheated air is then used to desorb the air in one portion of the wheel. As the air exits the desorption section the organic concentration is approximately 10 times the concentration of the original process stream. This low volume, higher concentration stream then enters the induced draft section of a catalytic or thermal recuperative oxidizer, where the organics are destroyed. 

Consider next a similar recuperative cycle, but one in which the compression process approximates to isothermal rather than isentropic, with the work input equal to the heat rejected (this may be achieved in a series of small compressions of polytropic efficiency Tjp, followed by a series of constant pressure heat rejections). It may then be shown that the thermal efficiency of this cycle is given by... 

The SRCO catalytic combustion unit treats volatile organic compound (VOC) laden process exhaust air. SRCO stands for self-recuperative catalytic oxidizer. The SRCO can be furnished as a complete operating vacuum extraction and catalytic oxidation system or as a stand-alone catalytic oxidizer to interface with an existing vacuum extraction and/or air stripper system. HD-SRCO stands for halogenated destruction self-recuperative catalytic oxidizer. This system is basically the same as the SRCO system, except that it remediates halogenated hydrocarbons using a different catalyst. 

However, given that a brief nap comprises mainly stage 1 sleep with limited slow-wave sleep, the significant improvements in alertness and performance produced by brief naps are disproportionate to the recuperative effect that would be predicted by Process S. Furthermore, Process S is not consistent with findings that brief naps may be at least as recuperative as longer naps (e.g., Ref. 20, 38, 40). Evans et al. (26) also reported that nonnappers, who had significantly more slow-wave sleep in their naps than habitual nappers, actually obtained less subjective benefit. 

It is not surprising that the homeostatic theory does not completely account for the beneficial effects of brief naps, as the theory was derived from experimental studies of long nocturnal sleep episodes rather than comparably shorter-duration napping studies. Hence the homeostatic theory may simply not be an appropriate theory of the recuperative effects of napping. The incongruence between existing scientific evidence from napping studies and Process S warrants the consideration of an alternative explanation. 

A second method of process intensification for recuperative reactors is to enhance performance by using a reactive coolant or heating medium, since the heat effects associated with reactions are usually much larger than those available with phase changes or simpler heating and cooling procedures. The coupling of an exothermic auxiliary heat source reaction with the desired endothermic reaction, or vice... 

The operation of regenerative and reactive processes for the manipulation of temperature profiles in chemical reactors is usually more complex than convective and recuperative techniques, due to the inherent dynamics and high sensitivities involved. Regenerative and reactive processes can, however, permit... 

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