Contact feed

Pirimiphos- methyl Contacted, feeding and breathing nervous poison, nonsystemic quickly penetrates into tissues 1.5 Ilia1 After the first record of occurrence of caterpillars, entirely before flowering... 

Multi-stage reactor first reactor for contacting feed with a medium pore shape-selective zeolite catalyst for converting the C3-olefinics to liquid hydrocarbons comprising C5+, in second stage the process conditions should be effective to convert a major amount of ethene... 

CLOSED FEED WATER HEATER - An indirect-contact feed water heater. Steam and water are separated by tubes. 

The current tendency to replace tubular feedheaters by direct contact feed-heaters in the LP stages is reducing enormously the amount of surface available to release corrosion products to the condensate stream, and so reduces the need to operate the polishing unit at high temperature. It will, therefore, become possible to Increase the life of the powdered resin and possibly its efficiency also. 

Another suspended growth method is the upward-flow anaerobic sludge blanket illustrated in Fig. 11.6a. Here the sludge is contacted by upward flow of the feed at a velocity such that the sludge is not carried out of the top of the digester. 

CaH24N.,03P2,(Me2N)2P(0)0P(0)(NMe2)z. It is not highly toxic to insects when used as a contact insecticide, but is readily absorbed by the roots and leaves of plants and translocated in the sap, so that the plant becomes toxic to species feeding on it. 

A schematic of the MGCC process is shown in Figure 9. The mixed Cg aromatic feed is sent to an extractor (unit A) where it is in contact with HF—BF and hexane. The MX—HF—BF complex is sent to the decomposer (unit B) or the isomerization section (unit D). In the decomposer, BF is stripped and taken overhead from a condensor—separator (unit C), whereas HF in hexane is recycled from the bottom of C. Recovered MX is sent to column E for further purification. The remaining Cg aromatic compounds and hexane are sent to raffinate column E where residual BE and HE are separated, as well as hexane for recycle. Higher boiling materials are rejected in column H, and EB and OX are recovered in columns I and J. The overhead from J is fed to unit K for PX separation. The raffinate or mother Hquor is then recycled for isomerization. 

An adsorbent attracts molecules from the gas, the molecules become concentrated on the surface of the adsorbent, and are removed from the gas phase. Many process concepts have been developed to allow the efficient contact of feed gas mixtures with adsorbents to carry out desired separations and to allow efficient regeneration of the adsorbent for subsequent reuse. In nonregenerative appHcations, the adsorbent is used only once and is not regenerated. 

Industrial-scale adsorption processes can be classified as batch or continuous (53,54). In a batch process, the adsorbent bed is saturated and regenerated in a cychc operation. In a continuous process, a countercurrent staged contact between the adsorbent and the feed and desorbent is estabhshed by either a tme or a simulated recirculation of the adsorbent. 

Humidification. For wiater operation, or for special process requirements, humidification maybe required (see Simultaneous HEAT and mass transfer). Humidification can be effected by an air washer which employs direct water sprays (see Evaporation). Regulation is maintained by cycling the water sprays or by temperature control of the air or water. Where a large humidification capacity is required, an ejector which direcdy mixes air and water in a no22le may be employed. Steam may be used to power the no22le. Live low pressure steam can also be released directly into the air stream. Capillary-type humidifiers employ wetted porous media to provide extended air and water contact. Pan-type humidifiers are employed where the required capacity is small. A water filled pan is located on one side of the air duct. The water is heated electrically or by steam. The use of steam, however, necessitates additional boiler feed water treatment and may add odors to the air stream. Direct use of steam for humidification also requires careful attention to indoor air quahty. 

In the simplest case, the feed solution consists of a solvent A containing a consolute component C, which is brought into contact with a second solvent B. Eor efficient contact there must be a large interfacial area across which component C can transfer until equiHbrium is reached or closely approached. On the laboratory scale this can be achieved in a few minutes simply by hand agitation of the two Hquid phases in a stoppered flask or separatory fuimel. Under continuous flow conditions it is usually necessary to use mechanical agitation to promote coalescence of the phases. After sufficient time and agitation, the system approaches equiHbrium which can be expressed in terms of the extraction factor S for component C ... 

In order to maintain a definite contact area, soHd supports for the solvent membrane can be introduced (85). Those typically consist of hydrophobic polymeric films having pore sizes between 0.02 and 1 p.m. Figure 9c illustrates a hoUow fiber membrane where the feed solution flows around the fiber, the solvent—extractant phase is supported on the fiber wall, and the strip solution flows within the fiber. Supported membranes can also be used in conventional extraction where the supported phase is continuously fed and removed. This technique is known as dispersion-free solvent extraction (86,87). The level of research interest in membrane extraction is reflected by the fact that the 1990 International Solvent Extraction Conference (20) featured over 50 papers on this area, mainly as appHed to metals extraction. Pilot-scale studies of treatment of metal waste streams by Hquid membrane extraction have been reported (88). The developments in membrane technology have been reviewed (89). Despite the research interest and potential, membranes have yet to be appHed at an industrial production scale (90). 

An important variation of this filter is based on replacing the rigid outer waU necessary for containing the feed and the cake on the rotating table by an endless mbber belt. The belt is held under tension and rotates with the table. It is in contact with the table rim except for the sector where the discharge screw is positioned, and where the belt is deflected away from the table to aUow the soHds to be pushed off the table. The cloth can also be washed in this section by high pressure water sprays. This filter, recendy developed in Belgium, is avaUable in sizes up to 250 m, operated at speeds of 2 minutes per revolution, and cake thicknesses up to 200 mm. 

A variation to the top-feed dmm filter is the dual dmm filter which uses two dmms of the same size in contact with each other and rotating in opposite directions. The feed enters into the V-shaped space formed on top of the two dmms and the cake that starts forming initially contains coarser particles due to the settling which takes place in the feed zone. This is beneficial to the clarity of the filtrate because the coarser particles act as a precoat. Erom the point of view, however, of the final moisture content of the cake the stratification of the soHds in the cake may lead to somewhat wetter cakes. Utilization of the area of the dmms is poor since there are dead spaces under the two dmms. The primary appHcation of the dual dmm filters is in dewatering coarse mineral or coal suspensions at feed concentrations greater than 200 kg/m. ... 

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