Reactor supercritical

A large scale supercritical reactor for chemical synthesis has recently been built in the UK and it seems likely that more synthetic processes using CO2 as a solvent will appear in the near future [35],... 

Figure 8. Schematic representation of our technique for recovering solid products from reactions in supercritical fluids (a) shows the supercritical reactor connected to a computer controlled syringe pump (Lee Scientific Model 501) filled with scC02. (b) shows how the scC02 is used to drive the supercritical reaction mixture (colored) through an expansion valve (Jasco 880/81 Back-pressure Regulator) where the products dissolved in the fluid are precipitated.

An additional complication with SCF processes is the possibility of complex phase behavior. A thorough understanding of the phase behavior of each reaction mixture is desirable, but not always possible. There is an extensive literature devoted to the investigation and prediction of phase behavior of SCFs [11], and the subject is introduced in chapter 1.2. Spectroscopic monitoring can provide at least an indication of phase behavior for example, which compounds are dissolved in which phase, as well as a method for monitoring the progress of reactions and identifying intermediates and products. It is best to resist the temptation to treat a supercritical reactor as a black box, and simply... 

This chapter first explains enzyme nomenclature, describes enzymatic, supercritical reactor configurations, and gives a compilation of published experimental results. The- most important topics concerning enzymatic reactions in SCFs are then covered. These are factors affecting enzyme stability, the role of water in enzymatic catalysis, and the effect of pressure on reaction rates. Studies on mass transfer effects are also reviewed as are factors that have an effect on reaction selectivities. Finally, a rough cost calculation for a hypothetical industrial process is given. 

As the neutron flux increases in a supercritical reactor, the second term in (19.23a) becomes negligible compared to Nq and the equation can be sinq>lified to... 

In an approximation of order m, equation (52) is an algebraic equation of degree m and, for a supercritical reactor, for example, has one positive root and m — 1 distinct negative roots. 

Continuous Reactor. Figure 3c also shows the schematic of a continuous fixed-bed supercritical reactor unit (49). The catalyst particles are loaded in the reactor between glass wool supported by steel mesh. The catalyst bed temperature is measured using a profile thermocouple placed axially in the reactor. The temperature and pressure of the system are controlled with the help of heaters... 

Office of Fossil Energy Efforts to qualify and improve corrosion resistance of materials needed for advanced supercritical reactors or combined-cycle gasification. 

In addition to phase behaviour, it is also important to evaluate the density of the reaction mixture. This variable plays a major role in both reaction equilibrium and kinetics. The control of density is more complex in supercritical reactors, where it can change dramatically with small perturbations in temperature, pressure or composition. The more direct application of density, in the case of continuous reactors, is to calculate the residence time of the reaction mixture for a given operating pressure and temperature. It is important to keep in mind that the volumetric flow measured downstream of the reactor can be very different from the flow inside the reactor due to the high variability of the density at supercritical conditions. In the case of batch reactors there are two... 

In a supercritical reactor, the neutron density increases exponentially. If a source is added to this supercritical reactor, the neutron density still increases exponentially, but at a faster rate. As in the case of the critical reactor, the... 

The concept of a SCWR based on natural circulation was also investigated in the 1960s (see Harden, 1963 Cornelius, 1965a,b, for examples). The renewed interest in supercritical reactors has recently driven significant additional research. 

If one writes the time behavior of all neutrons, h, in a supercritical reactor with no sources as... 

This experiment is designed to acquaint the participant with the use of the danger coefficient method to measure the absorption cross sections of certain elements. The experiment consists of a measurement of the sensitivity of the AGN-201 reactor at the core center with a standard l/v-absorber and subsequent cross-section measurements of a selected group of materials in terms of the reactor sensitivity. Reactivity will be determined by measurement of positive periods with and without the material in the reactor core. The excess reactivity of the supercritical reactor is related directly to the positive period measurement through the basic inhour equation. The results of the experiment will be compared with the known thermal cross sections and a complete analysis of any discrepancies will be made. 

The reactivity changes that occur in the reactor when an absorber is placed at its center will be measured in terms of asymptotic positive periods. The stable period of a supercritical reactor is related to the reactivity through the basic inhour equation. This expression involves the prompt neutron lifetime and the delayed neutron parameters (see Appendix B). 

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