Reactor heat integration characteristics

The heat integration characteristics of reactors depend both on the decisions made for the removal or addition of heat and the reactor mixing characteristics. In the first instance, adiabatic operation is considered, since this gives the simplest design. 

Adiabatic operation. If adiabatic operation leads to an acceptable temperature rise for exothermic reactors or an acceptable fall for endothermic reactors, then this is the option normally chosen. If this is the case, then the feed stream to the reactor requires heating and the efiluent stream requires cooling. The heat integration characteristics are thus a cold stream (the reactor feed) and a hot stream (the reactor efiluent). The heat of reaction appears as elevated temperature of the efiluent stream in the case of exothermic reaction or reduced temperature in the case of endothermic reaction. 

Heat carriers. If adiabatic operation produces an unacceptable rise or fall in temperature, then the option discussed in Chap. 2 is to introduce a heat carrier. The operation is still adiabatic, but an inert material is introduced with the reactor feed as a heat carrier. The heat integration characteristics are as before. The reactor feed is a cold stream and the reactor efiluent a hot stream. The heat carrier serves to increase the heat capacity fiow rate of both streams. 

For indirect heat transfer, the heat integration characteristics of the reactor can be broken down into three cases ... 

Cold shot. Injection of cold fresh feed for exothermic reactions or preheated feed for endothermic reactions to intermediate points in the reactor can be used to control the temperature in the reactor. Again, the heat integration characteristics are similar to adiabatic operation. The feed is a cold stream if it needs to be increased in temperature or vaporized and the product a hot stream if it needs to be decreased in temperature or condensed. If heat is provided to the cold shot or hot shot streams, these are additional cold streams. 

We first review in Part 1 the basics of plantwide control. We illustrate its importance by highlighting the unique characteristics that arise when operating and controlling complex integrated processes. The steps of our design procedure are described. In Part 2, we examine how the control of individual unit operations fits within the context of a plantwide perspective. Reactors, heat exchangers, distillation columns, and other unit operations are discussed. Then, the application of the procedure is illustrated in Part 3 with four industrial process examples the Eastman plantwide control process, the butane isomerization process, the HDA process, and the vinyl acetate monomer process. 

X.K., Myrstad, R., Venvik, H.J., Pfeifer, P., and Holmen, A. (2011) Characteristics of 16. an integrated micro packed bed reactor-heat exchanger for methanol synthesis... 

Characteristics of an Integrated Micro Packed Bed Reactor-Heat Exchanger for methanol synthesis from syngas. Chemical Engineering Journal, Vol. 167, 496-503. 

Hayer F, Bakhtiary-Davijany H, Myrstad R, Holmen A, Pfeifer P, Venvik HJ. Characteristics of integrated micro packed bed reactor-heat exchanger configurations in the direct synthesis of dimethyl ether. Chemical Engineering and Processing 2013 70 77-85. 

The adiabatic integral reactor has the characteristics of uniform diameter, filling with homogeneous catalyst, and good insulation. The feeds preheated to a certain temperature infiood into the reactor, and measure axially the reaction heat and the corresponding temperature distribution of kinetic law. However, the data acquisition and mathematic explanation are difficult for the reactors. 

H. Hofmann Industrial process kinetics and parameter estimation, Adv.Chem.Ser. 109(1972)519-534 /2/ P. Trambouze, H. van Landeghem and J.P. Wauquier Les reac-teurs chimiques. Edition Technip, Paris 1984 /3/ H. Hofmann, G. Emig and W. Rdder The use of an integral reactor with sidestream-analysis for the investigation of complex reactions, EFCE Publ.Ser. 37(1984)4 19-426 /4/ S. Yagi and D. Kunii Studies on the effective thermal conductivities in packed beds, AIChE J. (1957)373-381 /5/ D. Kunii and J.M. Smith Heat transfer characteristics of porous rocks, AIChE J. (1960)71-78 /6/ N. Wakao and J.M. Smith Diffusion in catalyst pellets, Chem.Eng.Sci. 17(1962)825-834... 

Liquid metal fuel reactors are classified on the basis of their heat-transfer characteristics (Fig. 18-1) [21]. If heat is transferred within the core the reactor is said to be internally cooled. If heat is transported by the fuel to the primary heat exchanger external to the core, the reactor is externally cooled. The term "integral reactor" implies an externally cooled system, but one so compact that the reactor and primary heat exchangers can be placed in the same container. 

Taking into account that energy stored in the coolant (heating, chemical and compression potential energy) is minimal in comparison with other coolants used and previously mentioned physical special characteristics of fast reactors and RI integral design, one could look forward to designing the RI of ultimately achievable self-protection. 

The operational and safety performance of the advanced marine reactor MRX, which is based on the features such as an integral type PWR, a water filled containment vessel and a passive decay heat removal system, depends strongly on the characteristics of the hydrothermal dynamics. JAERI has a plan to study experimentally the hydrothermal characteristics of MRX under oscillating conditions by setting a synthetic hydrothermal dynamics test facility (SHTF) on board. This facility uses electric heaters and a core characteristics simulator instead of nuclear fuel. 

The unique operating characteristics of micro-reactors, compared to conventional batch reactors, include a high surface-area-to-volume ratio, enhanced heat transfer diffusion-dominated mass transfer, spatial and temporal control of reagents and products, the generation of concentration gradients and the opportunity to integrate processes and measurement systems in an automated manner. Some of characteristics are discussed here ... 

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