Process operations material transfer

Green, D. W., J. D. Maloney, and R. H. Perry. 2008. Perry s Chemical Engineers Handbook, 8th ed. New York McGraw-Hill. Perry s has sections on both chemical and physical property data, and chemical engineering fundamentals processes operations (heat transfer, distillation, kinetics) construction materials, process machinery, waste management, and safety. Also available in electronic format. 

A related problem is the allocation of costs when a raw material for one process operation is produced internally by another process operation of the same organization (17). The transfer or captive price assigned to the raw material can range from the production cost to a market price that reflects a total profit margin for the material producer, depending on the accounting procedures adopted. 

Vacuum systems are typically used when flows do not exceed 6800 kg/h (15,000 Ib/h), the equivalent conveyor length is less than 305 m (1000 ft), and several points are to be supplied from one source. They are widely used for finely divided materi s. Of special interest are vacuum systems designed for flows under 7.6 kg/min (1000 Ib/h), used to transfer materials short distances from storage bins or bulk containers to process units. This type of conveyor is widely used in plastics and other processing operations where the variety of conditions requires flexibility in choosing pickup devices, power sources, and receivers. Capital investment can be kept low, often in the range of 2000 to 7000. 

Location of Transfer Stations Whenever possible, transfer stations should be located (1) as near as possible to the weighted center of the individual solid-waste-produciion ares to be served, (2) within easy access of major arterial highways as well as near secondary or supplemental means of transportation, (3) where there will be a minimum of pubhc and environmental objection to the transfer operations, and (4) where construction and operation will be most economical. Additionally, if the transfer-station site is to be used for processing operations involving material recovery and/or energy production, the requirements for those operations must be considered. 

All processes may be classified as batch, continuous, or semibatch depending on how materials are transferred into and out of the system. Also, the process operation may be characterized as unsteady state (i.e., transient) or steady state, depending on whether the process variables (e.g., pressure, temperature, compositions, flowrate, etc.) are changing with time or not, respectively. In a batch process, the entire feed material (i.e., charge) is added instantaneously to the system marking the beginning of the process, and all the contents of the system including the products are removed at a later time, at the end of the process. In a continuous process, the materials enter and leave the system as continuous streams, but not necessarily at the same rate. In a semibalch process, the feed may be added at once but the products removed continuously, or vice versa. It is evident that batch and semibatch processes are inherently unsteady state, whereas continuous processes may be operated in a steady or unsteady-state mode. Start-up and shut-down procedures of a steady continuous production process are examples of transient operation. 

In production processes, raw material are converted into desired products using a series unit operations of unit operations. Such unit operations may be few in number and they are linked together in a logical sequence. Typical unit operations include such activities as the transport of solids and liquids, the transfer of heat, crysallisation, collection and drying. 

In the processing of materials it is often necessary either to increase the amount of vapour present in a gas stream, an operation known as humidification or to reduce the vapour present, a process referred to as dehumidification. In humidification, the vapour content may be increased by passing the gas over a liquid which then evaporates into the gas stream. This transfer into the main stream takes place by diffusion, and at the interface simultaneous heat and mass transfer take place according to the relations considered in previous chapters. In the reverse operation, that is dehumidification, partial condensation must be effected and the condensed vapour removed. 

Polymer flow issues are concerns on the part of plant operations personnel that can arise when one proposes to put an in-line NIR probe (or pair of probes) into a polymer reactor or transfer line. These concerns tend to be plant or process-specific. Plant personnel are likely to be concerned if the probe will change the pressure drop in the line, create a cold spot in the reactor or line, protrude into the flow stream, or create dead spots (e.g. recessed probes or the downstream side of protruding probes). There may also be plant- or process-specific resfricfions on where probes (or analyzers) can be located, on pipe sizes, on the use of welds, and on materials of construction. It is critical to involve plant operations personnel (including process operators) as early as possible in discussions about probe design and location. 

Typically, medium to small processing facilities are under the jurisdictional coverage of local fire and building codes that require automatic sprinkler protection. These processing operations should be fire protected by automatic sprinklers that extend overall areas that store, process, or transfer flammable or combustible materials. The physical limits of the areas requiring protection can... 

Process operation is defined as any work with substances in which the containers used for reactions, transfers and other handling of substances are designed to be easily manipulated by one person. This does not include operations whose function is to produce commercial quantities of material. 

Materials in a colloidal state are frequently preferred in industrial processing operations because their large surface areas per unit volume enhance chemical reactivity, adsorptive capacity, heat transfer rates, and so on. Therefore, one cannot overlook the importance of the flow behavior and properties of colloids since they exert a significant influence on the performance, efficiency, and economy of the process. Note that some examples of this (e.g., ceramic processing, electrophoretic display devices, and food colloids) were mentioned in the vignettes presented in Chapter 1. In addition, one often uses the flow properties and behavior of the products as measures of the microstructure (or, morphology ) of the products and as a means of quality control (e.g., printing inks, toners, paints, skin creams, blood substitutes,... 

Exothermic chemical reactions Endothermic processes pressure Material handling and transfer Enclosed or indoor process units Access relief pressure Drainage and spill control Toxic materials Sub-atmospheric Operation in or near flammable range Dust explosion... 

Material transfer operations between process steps such as charging the final lubricated blend into the tablet press hopper have the potential to impact the blend content uniformity when drag and excipients are not evenly distributed within the powder... 

Gas, or vapor molecules, after the degasitication process, can go through the pore structure of crystalline and ordered nanoporous materials through a series of channels and/or cavities. Each layer of these channels and cavities is separated by a dense, gas-impermeable division, and within this adsorption space the molecules are subjected to force fields. The interaction with this adsorption field within the adsorption space is the base for the use of these materials in adsorption processes. Sorption operations used for separation processes imply molecular transfer from a gas or a liquid to the adsorbent pore network [2],... 

Activities in the FCC, hydrocracker, motor and BTX reformer submatrices represent (1) feed streams from each of the crude operations and from other process units, (2) material transfers between process units simulating... 

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