High heat exchangers

Case G GlaxoSmithKline Fine Chemical from Carbonyl Process (41). The fine chemical is produced in a high-heat exchange reactor. The residence time is thereby reduced by a factor of 1800( ) compared to a conventional batch reactor. The reactive content is thereby considerably reduced hence the process is safer. 

But via, for instance, high-heat exchange reactors (HEX reactors) that allow a much shorter reaction time and at the optimal temperature, process intensification can also reduce the formation of by-products considerably. A by-product reduction by a factor of 4 is achieved via a HEX reactor (46). This means a considerable reduction in feedstock cost and waste handling. 

Consider the following problem. In the petrochemical industry, many reactions are oxidations and hydrogenations that are very exothermic. Thus, to control the temperature in an industrial reactor the configuration is typically a bundle of tubes (between 1 and 2 inches in diameter and thousands in number) that are bathed in a heat exchange fluid. The high heat exchange surface area per reactor volume allows the large heat release to be effectively removed. Suppose that a new catalyst is to be prepared for ultimate use in a reactor of this type to conduct a gas-phase reaction. How are appropriate reaction rate data obtained for this situation ... 

However, besides the high heat exchange coefficients, fluidized beds are also suitable for isothermal operations even if a highly exothermic reaction is occurring. This has been demonstrated a.o. by Deshmukh et al. [46,47], who carried out oxidative dehydrogenation of methanol in laboratory-scale membrane fluidized bed reactors. The authors found virtually isothermal conditions even for very high methanol feed concentrations. This important... 

The selected diameter of micro fuel element, which is 1.8 mm, secures an exceptionally high heat exchange surface in the core, which results in a considerably lower heat flows and temperatures as compared to conventional BWRs or PWRs. The low thermal energy stored in the core secures high level of intrinsic safety in design basis and beyond design accidents. 

Microstructured reactors (microreactors) represent a new type of reaction equipment for applications in chemistry. Small dimensions of microchannels provide a short diffusion time, better temperature and pressure control, large specific surface area, high heat exchanging efficiency, and a higher level of safety [1]. 

Following the pinch rules, there should be no heat transfer across either the process pinch or the utility pinch by process-to-process heat exchange. Also, there must be no use of inappropriate utilities. This means that above the utility pinch in Fig. 16.17a, high-pressure steam should be used and no low-pressure steam or cooling water. Between the utility pinch and the process pinch, low-pressure steam should be used and no high-pressure steam or cooling water. Below the process pinch in Fig. 16.17, only cooling water should be used. The appropriate utility streams have been included with the process streams in Fig. 16.17a. 

In order to maintain high energy efficiency and ensure a long service life of the materials of construction in the combustion chamber, turbine and jet nozzle, a clean burning flame must be obtained that minimizes the heat exchange by radiation and limits the formation of carbon deposits. These qualities are determined by two procedures that determine respectively the smoke point and the luminometer index. 

If high wellhead pressures are available over long periods, cooling can be achieved by expanding gas through a valve, a process known as Joule Thomson (JT) throttling. The valve is normally used in combination with a liquid gas separator and a heat exchanger, and inhibition measures must be taken to avoid hydrate formation. The whole process is often termed low temperature separation (LTS). 

The effectiveness of the approach is demonstrated on two rqjresentative NDT techniques intapretation of data acquired with an ultrasonic rail inspection system and interpretation of eddy-current data from heat exchangers in (petro-)chemical industry. The results show that it is possible to provide a high level of automation in combination with efficient operator support for highly variable NDT measurements where up to now use of automated interpretation was only limited. 

Very strong stirring equipment is needed for mixing because of the high viscosity, and long tubular reactors with low cross-sectional area are needed for heat exchange. 

K AIE 20, has emerged as a highly efficient, noncorrosive, and nonhazardous flux for brazing aluminum parts of heat exchangers. Nocolok 100 Flux (Alcan Aluminum Corp.) developed by Alcan (Aluminum Co. of Canada) has been the first commercial product. Its use and mechanistic aspects of the associated brazing process have been weU documented (33—37). 

If food can be heated quickly to a temperature of I3I°C a lethaUty equivalent to 6 min at I2I°C can be accumulated in 36 s. This rapid heating and cooling of hquid foods, such as milk, can be performed in a heat exchanger and is known as high temperature—short time (HTST) processing. HTST processing can yield heat-preserved foods of superior quahty because heat-induced flavor, color, and nutrient losses are minimized. 

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