Continuous heat exchanger

FIG. 11 -36 (Continued) Heat-exchanger-component nomenclature, (c) Outside-packed floating-head exchanger. Type AEP. (d) U-tuhe heat exchanger. Type CFU. (e) Kettle-type floating-head rehoder. Type AKT. (Standard of Tubular Exchanger Manufacturers Association, 6th ed., 1978. )... 

Table 3-4 (Continued) Heat Exchanger Tube Count...

N., Cabassud, M., Douglas, C., and Demissy, M. (2008) Dynamic behaviour of a continuous heat exchanger/reactor after flow failure. Int.J. Chem. React. Eng., 6 (A23), Available at http //nnnv.bepress.com/ijcre/vol6/A23. 

M. (2008) Evaluation of an intensified continuous heat-exchanger reactor for inherently safer characteristics. J. Loss Prev. Process Ind. 21 (5), 528-536. 

In this section, we will describe the so-called continuous heat exchangers which are used down to about 1K. For lower temperatures, due to the increasing importance of the Kapitza resistance (see Section 4.3) step exchangers are used. They will be described in Chapter 6 in connection with the dilution refrigerator. 

To reach lower temperatures, the exchange surface of continuous heat exchanger is not large enough, and step exchangers put in series are added. Step exchangers are usually made from a copper block in which channels for the passage of the two liquids are... 

Low acid foods have a pH > 4.5, require steriliz.aliun at temperatures above 100 C. and thus require treatment in pressure vessels. Heat preservation processes above 100 C can he carried out in batch or continuous heat-exchange equipment. 

The work of Furnas above described and those of others were reexamined by Lovell and Karnofsky (1943). Their mathematical studies were confined to packings composed of spheres of uniform diameter and made allowance for resistance to heat transfer by conduction within the solids. The equation obtained by Lovell and Karnofsky, without correcting for resistance, is of the form encountered in the design of continuous heat exchangers,... 

Regeneration of high acid concentrations from sulfuric acid, which has been only diluted by water, such as obtained from air or other gas drying functions, can be accomplished by boiling water in either a batch (pot) or continuous (heat exchanger) mode [63]. Temperatures of about 300°C are required for product acid concentrations of 95% or better at normal atmospheric pressure. If the pressure is reduced to 20 mm Fig, water removal may be accomplished at about 200° C. In both cases, lead or lead-lined equipment is necessary for the dilute acid stages to avoid corrosion problems. Steel may be used for containment of concentrations above 95% (65°Be). 

A recuperator is a low- to medium-temperature (up to about ISOOT or 700°C), continuous heat exchanger that uses the sensible energy from hot combustion products to preheat the incoming combustion air. These heat exchangers are commonly counterflow where the highest temperatures for both the combustion products and the combustion air are at one end of the exchanger with the coldest temperatures at the other end. Lower temperature recuperators are normally made of metal, while higher temperature recuperators may be made of... 

Recuperator. A continuous heat exchanger in which heat from furnace gases is transferred to incoming air or gas through walls (usually tubes) of metal or refractory material. 

Thus, the mathematic models for reactor design are also classified into continuous heat exchange bed and adiabatic one. Usually, the design of reactor adopts one-dimension quasi-homogeneous model which considers that when reactive gas passes the catalyst bed like a plug-flow, there exist no radial and axial return mixture, and microkinetics can be treated in intrinsic kinetics multiplied by an effective factor that involves the effects of transfer processes, and by an active coefficient that involves the effects of reduction, poisoning and declining etc. Macrokinetics can be... 

Regardless of the configuration of ammonia converters and their diameters, there are only two modes of heat extraction from the catalyst bed in situ heat-exchange or external heat-exchange. The former is called fixed bed with continuous heat exchange the reactor has only one bed housing all the catalysts, and is called a cold-type reactor (Fig. 8.6). The latter is called an adiabatic fixed bed reactor the reactor consists of two or more beds of catalyst, with heat exchange between the beds (Fig. 8.7). 

Fig. 8.6 Optimum operating line of temperature at the continuous heat-exchange...

Figures 8.6 and 8.7 respectively show the operating temperature profile in a continuous heat-exchange reactor and in an adiabatic fixed-bed reactor. The operating line in Fig. 8.6 is based on the heat balance, t2 = to + (14—15)Ay x 100%, where to is the entrance temperature, <2 is the outlet temperature. Ay is the net value of ammonia.

The radial-flow converter with two beds of indirect heat exchange The radial-flow converter with three beds of indirect heat exchange, The axial-flow converter with one bed continuously heat exchange by cool piping The axial and radial-flow converter with three beds and direct heat exchange between bed by cold gas. 

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