Pilot plants types

In general, pilot-plant space can be divided into five basic types separate buildings, containment cells or barricades, open bays, walk-in hoods, and laboratory areas. A summary of the advantages and disadvantages of each has been given (1). 

The space required for a pilot plant varies tremendously with its size and type. A small unit may require only part of a laboratory (perhaps 5—10 m ), whereas an average pilot plant of 50,000 to 200,000 may require a large room or building (perhaps 500—2000 m ), excluding extended feed or product storage. 

Three types of computer control systems are commonly used for pilot-plant instmmentation. The first is a centralized system, usually based on a minicomputer or occasionally a mainframe. These systems have large storage capacities, substantial memories, and much associated equipment. They typically control all the pilot plants in an area or faciUty. Centralized systems are economical if a large number of units are involved but are becoming less common due to their high installation and maintenance costs as well as the limitation that any failure of the central system shuts down all pilot plants involved. 

Instrumentation. Pilot plants are usually heavily instmmented compared to commercial plants. It is not uncommon for a pilot plant to have an order of magnitude more control loops and analytical instmments than a commercial plant because of the need for additional information no longer requked at the commercial stage. A discussion of all the specific types of instmmentation used on pilot plants is beyond the scope of this article. Further information on some of the more common instmmentation is available (1,51). 

Specific reactor characteristics depend on the particular use of the reactor as a laboratory, pilot plant, or industrial unit. AH reactors have in common selected characteristics of four basic reactor types the weH-stirred batch reactor, the semibatch reactor, the continuous-flow stirred-tank reactor, and the tubular reactor (Fig. 1). A reactor may be represented by or modeled after one or a combination of these. SuitabHity of a model depends on the extent to which the impacts of the reactions, and thermal and transport processes, are predicted for conditions outside of the database used in developing the model (1-4). 

Figure 14-12 illustrates the influence of system composition and degree of reaetant eonversion upon the numerical values of for the absorption of CO9 into sodium hydroxide solutions at constant conditions of temperature, pressure, and type of packing. An excellent experimental study of the influence of operating variables upon overall values is that of Field et al. (Pilot-Plant Studie.s of the Hot Carbonate Proce.s.s for Removing Carbon Dioxide and Hydrogen Sulfide, U.S. Bureau of Mines Bulletin 597, 1962). 

In the Premier Mill the rotor is shaped hke the frustrum of a cone, similar to that in Fig. 20-53. Surfaces are smooth, and adjustment of the clearance can be made from 25 [Lm (0.001 in) upward. A small impeller helps to feed material into the rotor gap. The mill is jacketed for temperature control. Direct-connected hquid-type mills are available with 15- to 38-cm (6- to 15-in) rotors. These mills operate at 3600 r/min at capacities up to 2 mVh (500 gal/h). They are powered with up to 28 kW (40 hp). Working parts are made of Invar alloy, which does not expand enough to change the grinding gap if heating occurs. The rotor is faced with Stellite or silicon carbide tor wear resistance. For pilot-plant operations, the Premier Mill is available with 7.5- and 10-cm (3- and 4-in) rotors. These mills are belt-driven and operate at 7200 to 17,000 r/min with capacities of 0,02 to 2 mVh (5 to 50 gal/h). 

Laboratory investigations may possibly establish reaction mechanisms, but quantitative data for design purposes require pilot plant work with equipment of the type expected to be used in the plant. 

Experimental analysis involves the use of thermal hazard analysis tests to verify the results of screening as well as to identify reaction rates and kinetics. The goal of this level of testing is to provide additional information by which the materials and processes may be characterized. The decision on the type of experimental analysis that should be undertaken is dependent on a number of factors, including perceived hazard, planned pilot plant scale, sample availability, regulations, equipment availability, etc. 

The use of pilot-plant filter assemblies is both eommon and a elassieal approaeh to design methodology development. These eombine the filter with pumps, reeeivers, mixers, ete., in a single eompaet unit and may be rented at a nominal fee from filter manufaeturers, who supply operating instruetions and sometimes an operator. Preliminary tests are often run at the filter manufacturer s laboratory. Rough tests indicate what filter type to try in the pilot plant. 

The objeetive of seale-up in reaetor design is to determine a eri-terion or eriteria on whieh to base the transfer of the laboratory seale into a full-seale eommereial unit. Before proeeeding from a laboratory to an industrial seale, additional investigations are required. However, it is diffieult to define these additional steps to gather all the information as promptly as possibe and at minimum eost. The mediodology of proeess development leading to seale-up beeomes die prineipal faetor for die sueeess of die operation. In aehieving diis purpose, experiments are elassified into diree main types laboratory, pilot plant, and demonstration units. 

Pilot plant experiments vary over a wide range, aeeounting for industrial eonstraints (e.g., duration of operation, eontrol parameters, equipment reliability, and impurities in the raw materials). Seale-up problems are investigated during pilot plant experiments. A pilot plant is an experimental rig, whieh displays the part of the operation that eorresponds to an industrial plant. It allows for simultaneous analysis of the physieal and ehemieal meehanisms. A pilot plant is indispensable for measuring the extent of the possible interaetions between these two types of meehanisms. It ean be small to minimize extraneous eosts sueh as the total operation eost as well as other eonstraints. 

For example, Flamilton et al. [10] employed dimensional similitude in eombination with mathematieal modeling in the design of a pilot plant and in evaluating the results to provide the basis for seale-up to a eommereial seale plant involving a reaetion of the type... 

Assume that the sealed-up reaetor has the same bottom head type (e.g., ASME standard F D) as the pilot plant seale reaetor. Equation 13-25 then beeomes... 

This is another common processing operation, usually for chemical reactions and neutralizations or other mass transfer functions. Pilot plant or research data are.needed to accomplish a proper design or scale-up. Therefore, generalizations can only assist in alerting the designer as to what type of mixing system to expect. 

There is a redundancy of flexibility in the design of FCC catalysts. Variation in the amount and type of zeolite, as well as the type of active matrix, provide a great deal of catalyst options that the refiner can employ to fit its needs. For smaller refiners, it may not be practical to employ pilot plant facilities to evaluate different catalysts. In this case, the above methodology can still be used with emphasis shifted toward using the MAT data to compare the candidate catalysts. It is important that MAT data are properly corrected for temperatu. soaking time, and catalyst strippability effects. 

Degussa AG uses immobilised acylase to produce a variety of L-amino adds, for example L-methionine (80,000 tonnes per annum). The prindples of the process are the same as those of the Tanabe-process, described above. Degussa uses a new type of reactor, an enzyme membrane reactor, on a pilot plant scale to produce L-methionine, L-phenylalanine and L-valine in an amount of 200 tonnes per annum. 

The process engineer also develops tests and interprets data and information from the research pilot plant. He aids in scaling-up the research type flow cycle lo one of commercial feasibility. 

This chapter treats the effects of temperature on the three types of ideal reactors batch, piston flow, and continuous-flow stirred tank. Three major questions in reactor design are addressed. What is the optimal temperature for a reaction How can this temperature be achieved or at least approximated in practice How can results from the laboratory or pilot plant be scaled up ... 

This paper demonstrates the technical feasibility of a plastics energy recovery plant using circulating fluidised bed technology from Ahlstrom of Finland. Full details are given of a two-phase test run conducted at Ahlstrom s pilot plant in Karhula, in order to obtain information on the process behaviour when combusting different types of plastics waste. Results are presented and conclusions drawn. 

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