Operation Process

PT 3—Operations Course Description This course combines systems into operational processes with emphasis on operation under various conditions. Topics include typical duties of an operator. Instruction focuses on the principles of chemical engineering and process equipment. Emphasis on scale-up from laboratory bench to pilot unit. Describe unit operation concepts solve elementary chemical mass/energy balance problems interpret analytical data and apply distillation and fluid flow principles. The purpose of this class is to provide adult learners with the opportunity to work in a self-directed work team, operate a complex distillation system, collect and analyze data. 

Start and stop process equipment, and follow and write operational procedures. The course is advanced and requires the learner to apply classroom skills to real-life operational activities. Students are required to qualify and operate a process unit and perform the following steps  

Orientation to and overview of the operating unit Safety, health, and environment review On-the-job training in drawing process flow diagrams Develop and use standard operational procedures Work in self-directed teams Complete operational assignments Collect, organize, and analyze data 

Orientation and Overview of Unit (includes all safety aspects) 

Draw Simple Process Flow Diagrams of Operating Unit (includes listing primary equipment, flows, and instrumentation) 

As is by now evident to the reader, the phenomenon of solubility in supercritical fluids is not new. Since 1879 (or 1861, if we include the high-pressure, near-critical liquid carbon dioxide studies of Gore), solubility, phase, and spectroscopic studies have been performed on a large number of solute-SCF mixtures. They were made for their inherent scientific and technical interest and value. And they received a resurgence of interest with the work of Diepen, Scheffer, and coworkers in the late 1940s and early 1950s. 

Besides the theoretical interest in the unusual phase behavior encountered in these systems, the principles involved can be applied in operations wherein the nonideality is intentionally created. The magnitude of solubility of a compound of low volatility in a gas above its critical temperature. .. is sufficient to consider the gas as an extracting medium, that is fluid-liquid or fluid-solid extraction analogous to liquid-liquid extraction and leaching. In this case the solute is removed and the solvent recovered by partial decompression. Thus compression of a gas over a mixture of compounds could selectively dissolve one compound, permitting it to be removed from the mixture. Partial decompression of the fluid elsewhere would drop out the dissolved compound, and the gas could be reused for further extraction. 

Schematic diagram of a simplified supercritical fluid extraction process solubility data for naphthalene in CO2 is 

At 90 bar and 36°C the equilibrium solubility of naphthalene in CO2 is only 2.5 wt%, therefore naphthalene falls out of solution. The precipitated naphthalene is collected in the separator and the CO2 stream is recompressed to the initial extraction conditions of 55°C and 300 bar and is recycled to the extractor. 

It is informative to follow the process cycle on a Mollier diagram for CO2 to determine the energy requirements of this SCF process relative to some other process, such as the vaporization of the naphthalene at its boiling point 

It is noteworthy that once the state of a substance is fixed by conditions 1-6, all physical properties (except for the form of a solid), including viscosity, thermal eonduetivity, color, refractive index, and density, take on definite values. Furthermore, the state of a substance is independent of its position in a gravitational field and its velocity. Although there are other conditions (magnetic field strength, surface area) whose values are needed under certain conditions, the six conditions listed above are usually sufficient to fix the state of a substance. 

Throughout the chemical engineering literature, many kinds of equipment, so-called unit operations, are described, including distillation columns, absorbers, strippers, evaporators, decanters, heat exchangers, filters, and centrifuges. Just to mention a few. The members of this large collection, many of which are listed in Tables 4.1 and 4.2, in connection with process simulators, all involve one or more of these basic operations  

Operations on solids, such as size reduction and enlargement 

Since these are the building blocks of nearly all chemical processes, it is common to create flowsheets involving these basic operations as a flrst step in process synthesis. Then, in a task integration step, operations are combined where feasible. In the remainder of this section, before considering the steps in process synthesis, each of the basic operations is considered in some detail. 

Chemical reaction operations are at the heart of many chemical processes. They are inserted into a flowsheet to effect differences in the molecular types between raw material and product streams. To this end, they involve the chemistry of electron transfers, free-radical exchanges, and other reaction mechanisms, to convert the molecular types of the raw materials into products of other molecular types that have the properties sought by a company s customers. Clearly, the positioning of the reaction operations in the flowsheet involves many 

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Given the choice of a batch rather than continuous process, does this need a different approach to the synthesis of the reaction and separation and recycle system In fact, a different approach is not needed. We start by assuming the process to be continuous and then, if choosing to use batch operation, replace continuous steps by batch steps. It is simpler to start with continuous process operation... 

Process operations. The third source of process waste we can classify under the general category of process operations. Operations such as start-up and shutdown of continuous processes, product changeover, equipment cleaning for maintenance, tank filling, etc. all produce waste. 

If air is used, then a single pass with respect to each feedstock is used and no recycle to the reactor (Fig. 10.4a).-Thus the process operates at near stoichiometric feed rates to achieve high conversions. Typically, between 0.7 and 1.0 kg of vent gases are emitted per kilogram of dichloroethane produced. ... 

The third source of process waste after the reactor and separation and recycle systems is process operations. 

Sources of waste in process operations a. Start-up I shutdown in continuous processes... 

Process operation for waste minimization. Many of the problems associated with waste from process operations can be mitigated if the... 

There are many other sources of waste associated with process operations which can only be taken care of in the later stages of design or after the plant has been built and has become operational. For example, poor operating practice can mean that the process operates under conditions for which it was not designed, leading to waste. Such problems might be solved by an increased level of automation or better management of the process. These considerations are outside the scope of this text. 

Knowing where waste is going is the key to reducing it. When reducing waste from process operations, a steady-state mass balance is not usually comprehensive enough. A balance that takes into account start-up, shutdown, and product changeovers is required. 

Clearly, some of these measures to reduce waste in process operations—such as design for low process inventory—can be taken into consideration at the early stages of design, but many cannot. We should be aware of the problem and do whatever we can in the early stages to prevent problems later. 

Ziegler process) and telomerization of alkenes to medium chain derivatives for detergents and fats. Both processes operate by insertion of an alkene into AIR bonds. 

As a consequence, other than its use in the ndM method, the refractive index is very often used in process operations because it can indicate smaii differences in product quality that would be missed by other measurements. The only restriction is that the color of the sample should be less than 5 on the ASTM D 1500 scale. 

The modern reforming process operates with continuous regeneration of the catalyst, at low pressure (2 to 5 bar) and high temperature (510-530°C). 

In this chapter the general equations of laminar, non-Newtonian, non-isothermal, incompressible flow, commonly used to model polymer processing operations, are presented. Throughout this chapter, for the simplicity of presentation, vector notations are used and all of the equations are given in a fixed (stationary or Eulerian) coordinate system. 

Pittman, J. F.T. and Nakazawa, S., 1984. Finite element analysis of polymer processing operations. In Pittman, J.F. T., Zienkiewicz, O.C., Wood, R.D. and Alexander, J. M. (eds), Num,erical Analysis of Forming Processes, Wiley, Chichester. 

The term supermicropores has been proposed for the pores in which adsorption occurs by the secondary process the pores in which the primary process operates would then be termed, simply, micropores (or alternatively ultramicropores, or ultrapores ). 

Preprocessor. A device in a data-acquisition system that performs a significant amount of data reduction by extracting specific information from raw signal representations in advance of the main processing operation. A preprocessor can constitute the whole of a data-acquisition interface, in which case it must also perform the data-acquisition task (conversion of spectrometer signal to computer representation), or it can specialize solely in data treatment. 

Mechanisms of Filter Retention. In general, filtrative processes operate via three mechanisms inertial impaction, diffusional interception, and direct interception (2). Whereas these mechanisms operate concomitantly, the relative importance and role of each may vary. 

A measurement of particle moisture content will normally be taken at the exit of the dryer. This allows the process operators to make such adjustments as may be needed to maintain moisture within the desired range. Various instmments are used, none of which are entirely satisfactory, and periodic hand samples are used in some mills. Considering the importance of moisture sensing and control at the dryers, it is unfortunate that a truly efficient, consistent, and accurate sensing system is not yet available to the industry. The primary reasons for the difficulty of measuring moisture at the dryer exit are the extreme and adverse conditions of heat, dust, and moisture present at this location. 

The ion-exclusion process for sucrose purification has been practiced commercially by Firm Sugar (104). This process operates in a cycHc-batch mode and provides a sucrose product that does not contain the highly molassogenic salt impurities and thus can be recycled to the crystallizers for additional sucrose recovery. 

Single-Cell Protein. Systems involving single-cell proteins are often very large throughput, continuous processing operations such as the Pmteen process developed by ICI. These are ideal for air-lift bioreactors of which the pressure cycle fermenter is a special case (50). 

The Carnot cycle is formulated directly from the second law of thermodynamics. It is a perfectly reversible, adiabatic cycle consisting of two constant entropy processes and two constant temperature processes. It defines the ultimate efficiency for any process operating between two temperatures. The coefficient of performance (COP) of the reverse Carnot cycle (refrigerator) is expressed as... 

Control technology requirements vary according to the scale of operation and type of emission problem. For instance, electrostatic precipitator design requirements for fly-ash control from 1000-MW coal-fired power boilers differ from those for a chemical process operation. In the discussion that follows, priority is given to control technology for the CPI as opposed to the somewhat special needs of other industries. 

Change the manner of process operation to prevent or reduce formation of, or air entrainment of, a pollutant. 

The lime—soda process is practiced mainly in isolated areas in some process operations, in the Kraft recovery process, and in the production of alurnina. It is not as efficient a route as electrolytic production. 

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