Equipment multiple phase

Many operations treat particle-liquid mixing in chemical industry. The first aim of solid-liquid mixing is to make a solid particle float. However, mixing performance of operations/equipment is not clear. Additionally, when many kinds of particles are involved, it is not known whether there is any difference in the mixedness between the following two cases the case where all particles are treated as a particle (two-phase mixing—particle and continuous liquid phase) and the case where every particle is treated individually (multiple-phase mixing—each particle and continuous liquid phase). Therefore, a solution to this unsolved problem is not imperative. 

The multiple phase contact inside the column is promoted by internal mass transfer equipment. Three groups of mass transfer equipment are commonly differentiated, which are separation trays, random packings and structured packings. Besides mass transfer equipment, further column internals are required in rectification to ensure the proper operation of the mass transfer equipment. Such internals may include support and hold-down plates, liquid distributors and redistributors, vapour distributor devices, gas-liquid phase separators and liquid collectors that usually do not participate on mass transfer. 

One dilemma in answering these questions is that laboratory scale experimentation may not be able to provide a suitable model for scale-up. BiU, Vijay, and Marco may have to make a decision on the fix without quantitative information. Fortunately, most mixing problems can be addressed with more certainty than those involving fast, complex reactions in multiple phases. These issues are discussed in Chapters 13 and 17 as well as in Chapter 12 (liquid-liquid mixing). In addition, comparisons between impellers and general information on the components of stirred vessels may be found in Chapter 6, and the help that can be provided by mixing equipment suppliers is discussed in Chapter 22. 

Mass transfer processes are complicated, usually involving turbulent flow, heat transfer, multiple phases, chemical reactions, unsteady operation, as well as the influences from internal construction of the equipment and many other factors. To study such complicated system, we propose a novel scientific computing framework in which all the relevant equations on mass transfer, fluid-dynamics, heat transfer, chemical reactions, and all other influencing factors are involved and solved numerically. This is the main task and research methodology of computational mass transfer (CMT). 

Most chemical processes involve two important operations (reaction and separalion) that are typically carried out in different sections of the plant and use different equipment. The reaction section of the process can use several types of reactors [continuous stirred-tank reactor (CSTR), tubular, or batch] and operate under a wide variety of conditions (catalyzed, adiabatic, cooled or heated, single phase, multiple phases, etc.). The separation section can have several types of operations (distillation, extraction, crystallization, adsorption, etc.), with distillation being by far the most commonly used method. Recycle streams between the two sections of these conventional multiunit flowsheets are often incorporated in the process for a variety of reasons to improve conversion and yield, to minimize the production of undesirable byproducts, to improve energy efficiency, and to improve dynamic controllability. 

Distillation appHcations can be characterized by the type of materials separated, such as petroleum appHcations, gas separations, electrolyte separations, etc. These appHcations have specific characteristics in terms of the way or the correlations by which the physical properties are deterrnined or estimated the special configurations of the process equipment such as having side strippers, multiple product withdrawals, and internal pump arounds the presence of reactions or two Hquid phases etc. Various distillation programs can model these special characteristics of the appHcations to varying degrees and with more or less accuracy and efficiency. 

A major disadvantage of this system is the limitation of the single-pass gas-chlorination phase. Unless increased pressure is used, this equipment is unable to achieve higher concentrations of chlorine as an aid to a more complete and controllable reaction with the chlorite ion. The French have developed a variation of this process using a multiple-pass enrichment loop on the chlorinator to achieve a much higher concentration of chlorine and thereby quickly attain the optimum pH for maximum conversion to chlorine dioxide. By using a multiple-pass recirculation system, the chlorine solution concentrates to a level of 5-6 g/1. At this concentration, the pH of the solution reduces to 3.0 and thereby provides the low pH level necessary for efficient chlorine dioxide production. A single pass results in a chlorine concentration in water of about 1 g/1, which produces a pH of 4 to 5. If sodium chlorite solution is added at this pH, only about 60 percent yield of chlorine dioxide is achieved. The remainder is unreacted chlorine (in solution) and... 

Separations are an important phase in almost all chemical engineering processes. Separations are needed because the chemical species from a single source stream must be sent to multiple destinations with specified concentrations. The sources usually are raw material inputs and reactor effluents the destinations are reactor inputs and product and waste streams. To achieve a desired species allocation you must determine the best types and sequence of separators to be used, evaluate the physical or chemical property differences to be exploited at each separator, fix the phases at each separator, and prescribe operating conditions for the entire process. Optimization is involved both in the design of the equipment and in the determination of the optimal operating conditions for the equipment. 

How does the team characterize the process for which the pilot plant is to be manufactured The first question that needs to be answered is What is the ultimate goal for the facility Is it to support development for solid dosage forms, liquid products, or biologically derived products Or does it have to serve multiple functions The answer to this question will allow us to focus and generate more accurate plans. Until later on in the design phase, this process characterization should be kept broad and not very detailed. Included in the evaluation should be the ancillary service equipment and support services, such as electrical and air handling requirements. 

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