Shell and coil

Liquid cooling is mostlyin shell-and-tube or shell-and-coil evaporators. 

Evaporators of this general type with dry expansion circuits will have the refrigerant within the tubes, in order to maintain a suitable continuous velocity for oil transport, and the liquid in the shell. These can be made as shell-and-tube, with the refrigerant constrained to a number of passes, or maybe shell-and-coil (see Figure 7.4). In both these configurations, baffles are needed on the water side to improve the turbulence, and the tubes maybe finned on the outside. Internal swirl strips or wires will help to keep liquid refrigerant in contact with the tube wall. 

The hot water used to control the temperature in the helical test section is heated by steam in a shell and coil heat exchanger. The hot water temperature in the exchanger outlet line controls the steam flow. From the exchanger the hot water flows to a 12-gallon high pressure surge tank, where the fine control of the temperature is obtained by electrical heaters. The water is then pumped to the helix test section through a rotameter and returned to the heater. 

This design is not used frequently due to the minimal contact area between the shell and coil. It does however alleviate one of the problems of constructing a half-pipe coil. That is the cutting of the coils in half and the subsequent wastage. Some techniques have been developed to form flat ships into half pipe coils to save wastage and labor. There is just as much welding required for attaching a full pipe coil as there is with the half pipe. 

Ethylene. Usually fed at low temperature to horizontal shell and coil type vaporizers at very low temperatures (-155°F or -104°C) so stainless steel or other high impact value material is normally used. Typical designs include steel shells with stainless steel vaporizing bundle designed to avoid surging and withstand thermal shock conditions. 

Another growing field is that of nonmetallic heat exchanger designs which typically are of the shell and tube or coiled-tubing type. The graphite units were previously discussed but numerous other materi- s are available. The materials include Teflon, PVDF, glass, ceramic, and others as the need arises. 

Most fish is still caught at sea and must be cooled soon after it is taken on board, and kept cold until it can be sold, frozen or otherwise processed [45]. The general practice is to put the fish into refrigerated sea water tanks, kept down to 0°C by direct expansion coils or a remote shell-and-tube evaporator. The sea water must be clean and maybe chlorine dosed. At this condition, fish can be kept for up to four days. 

Figure 5.1 Few common types of heat exchangers, (a) Double-tube type (b) shell-and-tube type (c) coil-type and (d) plate-type.

A wide variety of heat exchangers are available, some of which you may have seen plate, spiral, and coil—to name just three. But 99 percent of the heat exchangers I have worked with are ordinary shell-and-tube exchangers, the design of which has not changed since the 1920s. 

There are various types of cooling water heat exchangers to be found in use today, and the permutations of these may number almost as many as the applications in which they are employed. Jackets on chemical reaction vessels are a specific type of heat exchanger, as are the coil bundles in evaporative condensers, plate and frame and shell and tube heat exchangers. 

Fig. 109. Production diagram of 0,0-diethyl-0-(4-nitrophenyl)thiophosphate (thiophos) 1 - synthesis reactor 2 - coil 3-5 - batch boxes 6-8 - flushing settling boxes 7, 9, 12 - collectors 10 - shell-and-tube heat exchangers 11 - condenser 13- container for dry thiophos...

The hard outer skeleton of insects and shellfish contains chitin, a polymer very like cellulose but made of acetyl glucosamine instead of glucose itself. It coils up in a similar way and provides the toughness of crab shells and beetle cases. 

A steam chest is a heat exchanger placed inside another piece of equipment, such as an evaporator. In the figure steam is introduced into a set of tubular coils (or straight tubes) place inside the evaporator shell and submerged in the liquid. Steam condenses and is withdrawn as liquid condensate. A trap at the chest exit prevents the steam itself from escaping. 

All of the equipment in contact with the glycol (including the absorber tower, flash tank, regenerator shell and firetube, and the preheat coils) are made from 316L stainless steel. All other components are made from carbon steel. 

The largest number of species of mollusks are in the class Gastropoda, which includes snails with a coiled shell, and others lacking a shell. The next largest group are the bivalves (class Bivalvia), the chitons (class Am-phineura), and octopus and squid, (class Cephalopoda). The other classes of mollusks are the class Scaphopoda (consisting of a few species of small mollusks with a tapered, tubular shell) and the class Monoplacophora, a... 

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