Design plants

Several constraints were faced in the design phase of the project. For example, special attention was given to the fact that 400 Series stainless steel, carbon, and some grades of aluminum were not compatible with the process. Additionally, the expander discharge temperature was required to stay between 35-70°F. The operating rpm of the expander wheel was determined by the rpm required by the third stage of the air compressor. 

The required suction pressure to the expander is not available until the oxidizer tower reaches design pressure. With two compressors in operation this takes approximately 15 min. Since the expander wheel is mounted on the compressor pinion, enough flow must be available at startup to prevent overheating. The calculated windage loss of the expander wheel (40 hp) requires about 16,000 Ib/lir of flow to prevent overheating. 

Startup flow to the expander is designed to be supplied from the discharge of the compressor through a throttle valve and cooler. A careful study of the characteristics of the compressor blow-off valve and the expander startup valve was performed by Solvay process engineers. Based on these calculations, the startup cooler and valve were sized to supply the minimum required flow to tlie expander wheel. 

The first step in the design of an industrial reverse osmosis plant is to determine the amount of water to be treated, peak demand, product water quality. 

Tt = Total elapsed test time (either 5, 10 or 15 minutes) 

Ti = Initial time in seconds required to collect the 500 ml sample 

Tf = Time in seconds required to collect the second 500 ml sample after test time Tt (normally after 15 minutes).11 

Manufacturers of hollow fine fiber elements usually require that the pretreated feedwater have an SDI of 3.0 or below In order for the element warranty to be effective. One manufacturer of spiral wound element requires that the pretreated feedwater have a turbidity of less than 1.0 turbidity unit to maintain the element warranty. As a general rule, if hollow fine fiber elements are to be used, the pretreated feedwater should have an SDI of 3.0 or less and, if spiral wound elements are to be used, an SDI of 5.0 or less. However, spiral wound elements have been used to recover municipal wastes with an SDI in excess of 5.0 after pretreatment. 

The objective of the review of the design of the nuclear power plant is to determine the adequacy of the design and its documentation in an assessment against current international standards and practices. (The term nuclear power plant includes all SSCs on the site, as stated in para. 3.1.) 

Adequate space should be left around each machine to permit free and easy movement for operating it and to allow for maintenance activ-ihes. Walkways should be identified by suitable lining and not allowed to be used for storage purposes. Services, such as air, water, electrical power, necessary for the work being carried out should be conveniently situated for fhe operators use. Machines in sequential operations should be positioned to require the minimum amount of handling of product. Wherever possible that handling should be automated or by mechanical means. 

The emission of noise and fumes by machinery which can affect the operator and those on adjacent machines should be reduced to a minimum. 

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Peters, M. S., and Timmerhaus, K. B., Plant Design and Economics for Chemical Engineers, McGraw-Hill, New York, 1980. 

PALLUZi Pilot Plant Design, Construction, and Operation... 

An extraction plant should operate at steady state in accordance with the flow-sheet design for the process. However, fluctuation in feed streams can cause changes in product quaUty unless a sophisticated system of feed-forward control is used (103). Upsets of operation caused by flooding in the column always force shutdowns. Therefore, interface control could be of utmost importance. The plant design should be based on (/) process control (qv) decisions made by trained technical personnel, (2) off-line analysis or limited on-line automatic analysis, and (J) control panels equipped with manual and automatic control for motor speed, flow, interface level, pressure, temperature, etc. 

Cost. The cost of fresh solvent is reflected in the operating costs in the form of solvent make-up charges. Avoidance of solvent losses, and hence a reduction of operating costs, may be obtainable through better plant design which is usually associated with increased capital costs. 

Disposal of exhausted soHds can be easily overlooked at the plant design stage, particularly when these have no intrinsic value alternative disposal methods might include landfiU of inert material or incineration, hydrolysis, or pyrolysis of organic materials. Liquid, soHd, and gaseous emissions are aU subject to the usual environmental considerations. 

Fig. 1. Fine chemicals plant design showing successive additions of processing equipment, where A represents the reaction vessel with agitator B, centrifuge C, dryer D, crystaUi2ation vessel E, raw material feed tanks F, centrifuge which may have an automatic discharge G, mother Hquor tank H,...

Apart from determinating the optimum size of equipment, the degree of flexibiHty is another key plant design parameter. FlexibiHty means cost, thus only as much flexibiHty as required by the processes should be buHt. Excessive flexibiHty is counterproductive (2). 

Eor this example the cost of the battery limits plant is about four times the purchase cost of the equipment. This number is about two for module I-type plants designed and iastalled by the fine chemicals company itself, and about six for expanded module IV-type plants designed and built by contractors. 

T. Kletz, Plant Design for Safety, A UserFriendly Approach, Hemisphere Publishing, New York, 1991. 

For central station power generation the open cycle system using electrically conducting coal combustion products as the working fluid is employed. The fuel typically is pulverized coal burned directly in the MHD combustor, although in some plant designs cleaner fuels made from coal by gasification or by beneficiation have been considered (8—10) (see Fuels, synthetic). 

Fig. 3. MHD power plant design burning low heating value (LHV) gas produced from coal by chemical regeneration.

The basic seed processing plant design is based on 70% removal of the sulfur contained in the coal used (Montana Rosebud), which satisfies NSPS requirements. Virtually complete sulfur removal appears to be feasible and can be considered as a design alternative to minimize potential corrosion problems related to sulfur in the gas. The estimated reduction in plant performance for complete removal is on the order of 1/4 percentage point. The size of the seed processing plant would have to be increased by roughly 40% but the corresponding additional cost appears tolerable. The constmction time for the 500 MW plant is estimated to be ca five years. 

Combustor. In the majority of MHD plant designs the MHD combustor bums coal directly. Because MHD power generation is able to utilize pulverized coal in an environmentally acceptable fashion, there is usually no need to make cleaner fuels from coal, eg, by gasification or by beneficiation. A discussion of combustion techniques for MHD plants is available (70). 

R. L. Loftness, Nuclear Power Plants Design, Operating Experience and Economics, D. Van Nostrand Co. Inc., Princeton, N.J., 1964. 

In addition to utiHty patents, some countries pubHsh patent documents under different or less stringent standards for patentabiHty and with shorter patent terms. For example, plant patents cover asexually reproduced plants. Design patents cover the decorative aspects of a product. UtiHty models and petty patents cover products with differences from the prior art that need not meet the nonobviousness standards set for utiHty patents. 

Scale-up is the process of developing a plant design from experimental data obtained from a unit many orders of magnitude smaller. This activity is considered successful if the commercial plant produces the product at plaimed rates, for plaimed costs, and of desired quaUty. This step from pilot plant to full-scale operation is perhaps the most precarious of all the phases of developing a new process because the highest expenses ate committed at the stages when the greatest risks occur. 

Process plant design has come a long way from the early 1930s when process designers used the rule-of-thumb that a process faciUty could not be scaled-up more than 10-fold (2). American Oil s Ultracracking unit (Texas City, Texas) for example, was designed from data from a small pilot plant with a scale-up factor of 80,000 (3). 

Pilot-plant design specifications should be estabUshed only after careful consideration of the experimental program because decisions on the accuracy of instmments, analyzers, and other equipment should be based on the requirements of the experiments planned for the unit. FlexibiUty and versatihty ate important but costly when provided unnecessarily or too profusely they can result in a unit that is difficult or impossible to operate successfully... 

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