Industrial hydrogenation reactor temperature control

In addition to understanding the interaction of radiation with water, the nuclear industry must obviously also take into account the excess production of molecular hydrogen and hydrogen peroxide, and control this excess in order to avoid explosive conditions and corrosion of the water circuitries. Due to the working conditions of the current reactors (T > 310 °C, P > 100 atm in Pressurized Water Reactor, PWR), it is mandatory to predict the evolution ofthe chemistry when submitted to high temperature and pressure. Nevertheless, a few experiments have shown that the linear Arrhenius law model is not applicable at temperatures above 250 °C. Hydrogen production overestimates have been necessary in... 

The ratio of cycHc to linear oligomers, as well as the chain length of the linear sdoxanes, is controlled by the conditions of hydrolysis, such as the ratio of chlorosilane to water, temperature, contact time, and solvents (60,61). Commercially, hydrolysis of dim ethyl dichi oro sil a n e is performed by either batch or a continuous process (62). In the typical industrial operation, the dimethyl dichi orosilane is mixed with 22% a2eotropic aqueous hydrochloric acid in a continuous reactor. The mixture of hydrolysate and 32% concentrated acid is separated in a decanter. After separation, the anhydrous hydrogen chloride is converted to methyl chloride, which is then reused in the direct process. The hydrolysate is washed for removal of residual acid, neutralized, dried, and filtered (63). The typical yield of cycHc oligomers is between 35 and 50%. The mixture of cycHc oligomers consists mainly of tetramer and pentamer. Only a small amount of cycHc trimer is formed. 

Three-phase slurry reactors are commonly used in fine-chemical industries for the catalytic hydrogenation of organic substrates to a variety of products and intermediates (1-2). The most common types of catalysts are precious metals such as Pt and Pd supported on powdered carbon supports (3). The behavior of the gas-liquid-sluny reactors is affected by a complex interplay of multiple variables including the temperature, pressure, stirring rates, feed composition, etc. (1-2,4). Often these types of reactors are operated away from the optimal conditions due to the difficulty in identifying and optimizing the critical variables involved in the process. This not only leads to lost productivity but also increases the cost of down stream processing (purification), and pollution control (undesired by-products). 

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 ... 

It is clear that in industrial operations, it is difficult to control many process variables to drive reactions to optimal product distributions. There are four primary control variables for reformers reactor inlet temperatures, reactor pressures, hydrogen content, and feed rate. There are other variables such as feedstock properties and catalyst type. But these variables are generally fixed for a given period of time. 

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