Design equipment

The design and instrumentation of individual equipment items are beyond the scope of this text. 

All work equipment must be eonstrueted or adapted to be suitable for its use, and its seleetion should have regard to the working eonditions and risks to health and safety of persons where it is used and any additional risks it poses (Provision and Use of Work Equipment 1998 Reg. 2). 

In addition to guarding dangerous maehinery (Reg. 11) measures are required to prevent or adequately eontrol hazards from work equipment due to  

The seleetion of materials of eonstmetion is subjeet to the eonsiderations of eoiTosion suimnarized on page 54. 

Consideration should be given to the safety features listed in Table 7.21. 

The process vessels are equipped with vents to prevent pressure build up by inert gases. These vents are also used to depressurise and flush equipment during emergencies and prior to maintenance. Usually, vents are connected to air pollution control equipment, except major relief vents which, due to large flows, would overload the treatment system. 

To prevent leaks from relief vents, rupture disks can be used in combination with safety valves, possibly with a previous safety risk analysis . The pressure between the mpture disc and the safety valve is monitored to detect any leaks. If the safety valves are connected to an incinerator, rupture disks may not be necessary. 

Technical provisions to prevent and minimise fugitive emissions of air pollutants include  

Prevention and reduction of VOC emissions. Cross-media effects No further information submitted. 

Depending on the situation, the implementation may lead to different eosts. The data shown in Table 12.3 are based on an estimate of the central cost estimation department of a polyethylene producer. 

Corrosion monitoring must be coupled with diagnostic work and remedial action. In some cases of corrosion, remedial action may be obvious or easily deduced. In other cases, diagnostic work precedes a decision or remedial action. The options for remedying corrosion problems in a process plant are (i) install a CP system (ii) install an anodic protection system (iii) change equipment design (iv) improve feed stock purity (v) alter process variables (vi) change the alloy/material (vii) institute inhibitor additions (viii) institute planned maintenance. 

Corrosion control methods used in this industrial sector consist of (i) equipment design (ii) process design (iii) the use of corrosion inhibitors. 

Pulp and paper industrial equipment design consists of proper material seleetion in conjunction with the process chemicals and prevention of stagnant fluids in the process equipment. In the absence of corrosion, low-alloy carbon steel would be the material of choice if corrosion were not a problem. However, for many processes, stainless steel and even nickel-base and titanium alloys are required for better performance in corrosive environments. At present, current US paper mills are constructed of about one-third carbon steel and two-thirds stainless steels. There are several grades in the group of stainless steels. The relative cost of the stainless steels is dependent on the concentration of the major alloying elements (Cr, Ni, Mo), the volume produced, and the form in which it is supplied such as tube, pipe, plate, or block. It is useful to note that stainless steels are 10-20% more expensive than low-alloy carbon steels. 

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Extraction, a unit operation, is a complex and rapidly developing subject area (1,2). The chemistry of extraction and extractants has been comprehensively described (3,4). The main advantage of solvent extraction as an industrial process Hes in its versatiHty because of the enormous potential choice of solvents and extractants. The industrial appHcation of solvent extraction, including equipment design and operation, is a subject in itself (5). The fundamentals and technology of metal extraction processes have been described (6,7), as has the role of solvent extraction in relation to the overall development and feasibiHty of processes (8). The control of extraction columns has also been discussed (9). 

As the throughput in a contactor represented by the superficial velocities and is increased, the holdup / increases in a nonlinear fashion. A flooding point is reached at which the countercurrent flow of the two Hquid phases cannot be maintained. The flow rates at which flooding occurs depend on system properties, in particular density difference and interfacial tension, and on the equipment design and the amount of agitation suppHed (40,65). 

Laboratory experiments using rodents, or the use of gas analysis, tend to be confused by the dominant variable of fuel—air ratio as well as important effects of burning configuration, heat input, equipment design, and toxicity criteria used, ie, death vs incapacitation, time to death, lethal concentration, etc (154,155). Some comparisons of polyurethane foam combustion toxicity with and without phosphoms flame retardants show no consistent positive or negative effect. Moreover, data from small-scale tests have doubtful relevance to real fine ha2ards. 

Liquid metals, however, present several disadvantages. Their weights must be considered with regard to equipment design. Additionally, Hquid metals are difficult to contain and special pumps must be used for system safety. Alkali metals react violentiy with water and bum ia air. Liquid metals also may become radioactive whea used for cooling auclear reactors (qv). 

For proper operation under anticipated use, recommended lubricants are designated by the equipment designer, ie, the designer specifies both the type of fluid and the fluid s viscosity. 

D. R. Bennett and co-workers, Cyogenic Air Separation Equipment Design, AIChE Tutorial on Cryogenic Technology, Houston, Tex., 1993. 

Food Processing. One of the first appHcations of RO was ia the food processiag (qv) iadustry. The primary advantage of RO over the traditionally used processes ia the food iadustry is that RO operates at low temperatures which can prevent the denaturation of some materials used ia foodstuffs. Because high temperatures are not required, energy costs are reduced as well. Moreover, RO is relatively simple ia terms of the equipment design. These factors lead ultimately to a reduction ia capital and operating costs, accompanied by an iacrease ia product quaUty. 

Effects of Rate Conditions. It is essential for commercial a-quartz crystals to have usable perfection growth at a high rate and at pressure and temperature conditions that allow economical equipment design. The dependence of rate on the process parameters has been studied (8,14) and may be summarized as follows. Growth rate depends on crystallographic direction the (0001) is one of the fastest directions. Because AS is approximately linear with AT, the growth rate is linear with AT. Growth rate has an Arrhenius equation dependence on the temperature in the crystallization zone ... 

Clean Air Act 1990 Amendments will lead to a phase out of 1,1,1-trichloroethane by the year 2005, which in turn will likely result in a slight resurgence of trichloroethylene in vapor-degreasing appHcations. The total production, however, will probably stay relatively low because regulations will require equipment designed to assure minimum emissions. 

Electrical engineering Equipment design Expert systems Extraction Failure analysis Flow analysis Safety... 

Process simulators stop generally at the process specifications for the equipment. For the detailed mechanical design of the equipment, such as heat exchangers and distillation columns, stand-alone programs are often used. They make process calculations, size the equipment, calculate thermal and mechanical stresses, design mechanical support of the parts of the equipment, design inlet and outlet nozzles, etc. 

Spreadsheet Applications. The types of appHcations handled with spreadsheets are a microcosm of the types of problems and situations handled with fuU-blown appHcation programs that are mn on microcomputers, minis, and mainframes and include engineering computations, process simulation, equipment design and rating, process optimization, reactor kinetics—design, cost estimation, feedback control, data analysis, and unsteady-state simulation (eg, batch distillation optimization). 

Overall Eactor Estimates. The next level of fixed capital estimate is based on a preliminary design that includes a flow sheet, material balances, energy balances, and enough equipment design to size all of the principal process equipment, including pumps and tanks. 

Multiblock Copolymers. Replacement of conventional vulcanized mbber is the main appHcation for the polar polyurethane, polyester, and polyamide block copolymers. Like styrenic block copolymers, they can be molded or extmded using equipment designed for processing thermoplastics. Melt temperatures during processing are between 175 and 225°C, and predrying is requited scrap is reusable. They are mostiy used as essentially pure materials, although some work on blends with various thermoplastics such as plasticized and unplasticized PVC and also ABS and polycarbonate (14,18,67—69) has been reported. Plasticizers intended for use with PVC have also been blended with polyester block copolymers (67). 

Generalized Correla.tions. A simple and rehable method for the prediction of vapor—Hquid behavior has been sought for many years to avoid experimentally measuring the thermodynamic and physical properties of every substance involved in a process. Whereas the complexity of fluids makes universal behavior prediction an elusive task, methods based on the theory of corresponding states have proven extremely useful and accurate while still retaining computational simplicity. Methods derived from corresponding states theory are commonly used in process and equipment design. 

Numerous other methods have been used to predict properties of gases and Hquids. These include group contribution, reference substance, approaches, and many others. However, corresponding states theory has been one of the most thoroughly investigated methods and has become an important basis for the development of correlation and property estimation techniques. The methods derived from the corresponding states theory for Hquid and gas property estimation have proved invaluable for work such as process and equipment design. 

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