Process/reactor design equipment requirements

Before the details of a particular reactor are specified, the biochemical engineer must develop a process strategy that suits the biokinetic requirements of the particular organisms in use and that integrates the bioreactor into the entire process. Reactor costs, raw material costs, downstream processing requirements, and the need for auxiliary equipment will all influence the final process design. A complete discussion of this topic is beyond the scope of this chapter, but a few comments on reactor choice for particular bioprocesses is appropriate. 

Frontal polymerization carried out as described above can be turned into a continuous process. In order to do this, it is necessary to move the newly formed polymer and the reactive mixture in the direction opposite to the direction of spreading of a thermal front at a velocity equal to the velocity of the front development to feed the reactor with a fresh reactive mass.254 Control of the process, choice of process parameters and proper design of the equipment require solving the system of equations modelling the main physical and chemical processes characteristic of frontal reactions. 

As mentioned, the aim of the study is to develop desulfurization equipment of industrial interest so understanding its general performance is important. Several sets of typical operation data measured under stable operations are listed in Table 7.5. The comparable data are depending on coal type, S02 content in flue gas ranges from 1400 to 11400 mg/m while the permitted discharge level in China is normally 1200 mg/m3. The data show that the designed equipment exhibits satisfactory global performance and meets the requirements for desulfurization by wet process. Under moderate operation conditions, the content of S02 in the cleaned gas can achieve a much lower level than that permitted. Even if the mole ratio of Ca/S is as low as 1.0, a sulfur-removal efficiency of nearly 90% can be achieved (see the fourth row in Table 7.5) while the pressure drop across the reactor is very small, ca. 400 Pa only. 

The 2" phase (2006-2009) R D activities undertake a SI process optimization and the performance tests of various chemical reactors selected for the SI cycle. The 2" phase research covers a dynamic code development for the SI process, a construction of a lab. scale( l 000 NL/h) SI process, and integrated operations of the process at prototypical pressures. On the other hand, conceptual and basic designs of a pilot scale( 100 Nm /li) SI process and its equipment will also be carried out according to the optimized process established from the theoretical evaluation using a commercial-base computer code and the experiences of the lab. scale construction and operations. Preliminary performance tests of the equipment, mechanical devices, and accessories for the pilot scale SI process should be carried out to obtain the design basis. Not only the several catalysts based on non-noble metals required for section II in the SI cycle but also a membrane for the separation of the hydrogen required for section III will be developed during the 2" phase research period. 

Note The polymerization conditions summarized above have been greatly simplified only to illustrate the significantly different process conditions required for the commercial manufacture of each type of polyethylene. The different process conditions necessary to produce each type of polyethylene have resulted in the use of enormously different equipment and reactor designs needed for the manufacture of LDPE and HDPE in the commercial plants. 

Armed with the PFS and the questions for the various process options the team can then discuss the most appropriate way forward. For example considering question 2, production staff may comment that this particular plant only runs on the day shift, so a 10-hour reaction is not viable the chemical engineer may conclude that the problem is likely to be one of mass transfer, and other reactor design options such as a spinning disc reactor should be considered. The SHE advisor may comment that not only is solvent 1 volatile but it is also moderately harmful and would require specialist handling equipment, hence it is very important to find an alternative. As waste minimization starts at the reaction stage it is critical to study this area in particular detail. Questions that can be asked include ... 

The latest development is now to combine continuous photochemistry with microstmctured equipment. Only very recenfly photochemical conversions in microreactors have received a considerable amount of attention due to the problem often encountered in conventional photoreactors that the distribution of radiation is inhomogeneous in the reaction zone. During the scale-up process, such inhomogeneities often require intensive modeling and design considerations usually on the basis of photon transport models [66], and such models have been, for example, developed for biomedical and analytical purposes [67]. The problem of the intensity distribution in a reactor is illustrated in Figure 3.10. It is obvious that spatial restriction of the irradiation zone in a microphotoreactor to a... 

A.1(X)6. All auxiliary systems associated with the reactor process system and the experimental facilities, such as compressed air, process sampling and equipment and floor drainage systems, shall be discussed in this section. The discussion should include the design bases, a system description, a safety evaluation, testing and inspection requirements, and instrumentation requirements. 

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