Reactor single heat-exchangers

For small- to medium-scale stationary applications, Johnston and Haynes [128] proposed a series of adiabatic reactors with heat exchangers in between rather than directly removing the heat in a single reactor. Thus a saw-tooth-like temperature... 

Commonly used levels of decomposition are catalyst surface, single catalyst pellet, catalyst bed, reactor including heat exchangers, mixing and distributing devices, and an entire unit with the catalytic reactor as one of its elements. Each lower element is a component of the higher level. It is invariable to the dimension of an upper element and can be studied separately. 

Crystallizing, batch processing design calculations, 99-100 CSTR (continuous stirred tank reactor) external heat exchanger, 714 reactor performance, 706-712 single-phase transfer medium, 714 Cumene catalyst, replacing, 721-726 Cumene process feed section, troubleshooting, 784-787 Cumene reactor... 

Figure 12-1. The Union Carbide Unipol process for producing HDPE (1) reactor, (2) single-stage centrifugal compressor, (3) heat exchanger, (4) discharge tank.

Simpler optimization problems exist in which the process models represent flow through a single pipe, flow in parallel pipes, compressors, heat exchangers, and so on. Other flow optimization problems occur in chemical reactors, for which various types of process models have been proposed for the flow behavior, including well-mixed tanks, tanks with dead space and bypassing, plug flow vessels, dispersion models, and so on. This subject is treated in Chapter 14. 

In the case where a rapid removal or addition of heat is needed, it may not be possible to use a single fixed bed or large diameter. In this case, the reactor can be built up of a number of tubes, containing the catalyst particles and encased in a single body (Smith, 1981). Then, the heat exchange can be easily done by circulating a fluid in the space between the tubes. 

In many situations, the monolith reactor can be represented by a single channel. This assumption is correct for the isothermal or adiabatic reactor with uniform inlet flow distribution. If the actual conditions in the reactor are significantly different, more parallel channels with heat exchange have to be simulated (cf., e.g. Chen et al., 1988 Jahn et al., 1997, 2001 Tischer and Deutschmann, 2005 Wanker et al., 2000 Young and Finlayson, 1976). In this section we will further discuss effective single channel models. 

The parallel reactor for the screening of the titer-plates consists of several modules, each of them is responsible for just a single operation (Fig. 4.12). The gas flow for example is preheated and evenly distributed within the distribution module and delivered to the wells on the titer-plate. The latter is clamped between the distribution module and the insulation module and also treated as a separate reaction module. The insulation module separates the heated section of the parallel reactor from the unheated section and is further cooled by the heat exchanger module on top of it. The last module, just above the heat exchanger module, is a multi-port valve that delivers the product gas to the gas-chromatograph. 

After coating, the titer-plates are inserted into the reactor to test their activity. The reaction conditions were held constant in the following experiments. The reactor was heated to 475 °C and held at a pressure of 0.2 bar (g). The heat exchanger was operated at 50 °C, and the throughput for a single well was adjusted to 1 ml min-1, resulting in a total space velocity of 9000 h 1. The residence time in the wells was 0.4 s. 

We start by studying the steady-state design and economics of a process with a single adiabatic reactor. The design considers the entire plantwide process reactor, heat exchangers, gas recycle compressor, preheat furnace, condenser, and separator. The economic objective function is total annual cost, which includes annual capital cost (reactor, catalyst, compressor, and heat exchangers) and energy cost (compressor work and furnace fuel). 

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