Evaluation process physical properties

There are some aspects of process design in which decisions are based primarily on past experience rather than on quantitative performance models. Problems of this type include the selection of constraction materials, the selection of appropriate models for evaluating the physical properties of homogeneous and heterogeneous mixtures of components, and the selection of safety systems. Advances in expert systems technology and information management will have a profound impact on expressing the solutions to these problems. 

The synthesis by computer-aided molecular design of new compounds that conform to various physical property requirements can reduce the time and effort required using traditional empirical approaches. This process generates chemical structures and evaluates certain physical properties. The generation process must be consistent with given structural constraints and this goal is obtained as explained at point 2. 

In the development phase of catalyst research, testing of the catalyst s chemical and physical properties and evaluation of the catalyst s performance ate two essential tasks. In the manufacturing process, many of the same analyses and evaluations are used for quaHty assurance. A number of the testing procedures outlined eadier for catalyst supports can also be appHed to catalysts (32). 

Check the toxicity of process materials, identify short and long term effects for various modes of entry into the body and different exposure tolerance Identify the relationship between odour and toxicity for all process materials Determine the means for industrial hygiene recognition, evaluation and control Determine relevant physical properties of process materials under all process conditions, check source and reliability of data... 

Materials information includes toxicity, permissible exposure limits, physical properties, reactivity, corrosivity, thermal and chemical and hazardous effects of inadvertent mixing of different materials.Process information consists of 1) process flow diagrams, 2) process chemistry descriptions, 3) maximum amounts of chemicals, 4) safe ranges for temperatures, pressures, flows oi 5) evaluation of the con.sequences of deviations. 

The second slop is to obtain all the information about the process that will be needed for a Ihorongh evaluation including but not limited to the process materials used and their physical properties, the chemistry and tlicnnodynamics of the process, a plant layout, and a description of all the equipment used including controls and instrumentation. The last part of the information gathering step nitty be viewed as the preliminary formation of the What If questions. 

A wide variety of physical properties are important in the evaluation of ionic liquids (ILs) for potential use in industrial processes. These include pure component properties such as density, isothermal compressibility, volume expansivity, viscosity, heat capacity, and thermal conductivity. However, a wide variety of mixture properties are also important, the most vital of these being the phase behavior of ionic liquids with other compounds. Knowledge of the phase behavior of ionic liquids with gases, liquids, and solids is necessary to assess the feasibility of their use for reactions, separations, and materials processing. Even from the limited data currently available, it is clear that the cation, the substituents on the cation, and the anion can be chosen to enhance or suppress the solubility of ionic liquids in other compounds and the solubility of other compounds in the ionic liquids. For instance, an increase in allcyl chain length decreases the mutual solubility with water, but some anions ([BFJ , for example) can increase mutual solubility with water (compared to [PFg] , for instance) [1-3]. While many mixture properties and many types of phase behavior are important, we focus here on the solubility of gases in room temperature IFs. 

Therefore, when developing an estimate of process engineering time required, it is important to recognize the amount of effort that may be necessary to collect physical property data before any real work can commence. This same concern exists when evaluating K values and activity data for systems. 

Results of regression are given in Table 7.4-4. The cycle time is size-dependent whereby this dependency is stronger for the semicontinuous process at these particular process conditions. The exponent p is almost the. same for both processes and is approximately 1/3. Clearly, the physical properties of the reaction mixture and thermokinetic data are needed to evaluate processing times and cycle times at a large scale. 

The DIPPR databases were developed in the United States by the Design Institute for Physical Properties of the American Institute of Chemical Engineers. The DIPPR projects are aimed at providing evaluated process design data for the design of chemical processes and equipment (www.aiche.org/dippr/projects.htm). The Project 801 has been made available to university departments see Rowley et al. (2004) and http.//dippr.byu. edu/description/htm. 

The model equations in Section II,A have been formulated to describe the energy and mass transfer processes occurring in two-phase tubular systems. The accuracy of these model equations in representing the physical processes depends on the parameters of the equations being correctly evaluated. Constitutive equations that relate each of the parameters to the physical properties, system properties, and dependent variables of the system are discussed in the following sections. 

Finding the pressure drop corresponding to a total mass flux Gm from this equation requires a stepwise procedure using physical property data from which the densities of both the gas phase and the mixture can be determined as a function of pressure. For example, if the upstream pressure P and the mass flux Gm are known, the equation is used to evaluate the pressure gradient at point 1 and hence the change in pressure AP over a finite length AL, and hence the pressure Px+i = Px — AP. The densities are then determined at pressure P1+i. And the process is repeated at successive increments until the end of the pipe is reached. 

The safety evaluation has to be closely integrated into existing preliminary process design environments to make it readily available during design. The safety tools also benefit from the existing databanks and simulation programs since they can be used for physical property and phase conditions calculations. 

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. 

A general account of how the CHETAH program may be applied to estimation of chemical hazards in relation to process research and development has been given [10], Progressively enhanced and user-friendly versions of CHETAH, which give an overall hazard assessment and are capable of running on personal computers are available from ASTM [11], Comments critical of the criteria used for hazard evaluation in the 1994 CHETAH program [12] led to amendments and enhancements incorporated in the 1998 Windows version. The pure compound physical properties databank has since been expanded from 400 to 1500 compounds and the... 

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