Pipe-coil heat exchangers

Piping systems Heat exchanger fouls Internal coil leaks... 

The pipe system heat exchange surface consists of 37 unified coil-type steam generating modules (Fig. IV-9) covered by a box-shaped casing. By feed water and steam, the steam generating modules are correspondingly integrated into two independent sections of 18 and 19 modules. 

The heatable areas of the diyer are the vessel wall and the screw. The diyer makes maximum use of the product-heated areas—the filling volume of the vessel (up to the knuckle of the dished head) is the usable product loading. The top cover of the vessel is easily heated by either a half-pipe coil or heat tracing, which ensures that no vapor condensation will occur in the process area. In addition to the conical vessel heated area, heating the screw effectively increases the heat exchange area by 15-30 percent. This is accomphshed via rotary joints at the base of the screw. The screw can be neated with the same... 

Pipe Coil Pipe coil for submersion in coil-box of water or sprayed with water Is simplest type of exchanger. Condensing, or relatively low heat loads on sensible transfer. Transfer coefficient is low, requires relatively large space if heat load is high. 0.5-0.7... 

The resistance of titanium in nitric acid is good at most concentrations and at temperatures up to boiling . Thus tubular heat exchangers are used in ammonium nitrate production for preheating the acid prior to its introduction into the reactor via titanium sparge pipes. In explosives manufacture, concentrated nitric acid is cooled in titanium coils and titanium tanks are... 

Cooling system failure could occur due to failure of pumps or controls supplying cooling media to the reactor vessel jacket, coils, or overhead reflux condensers. Piping to or from the condensers could become plugged or any of the heat exchange surfaces could become excessively fouled. 

The annual cycle energy system (ACES) has two basic components a very large insulated storage tank of water and a heating-only heat pump. The tank contains coils of pipe filled with brine (salt water) warmed by the water in the tank. The brine circulates through a heat exchanger and transfers its heat to the heat pump refrigerant. 

Select steam traps for the following five types of equipment (1) where the steam directly heats solid materials, as in autoclaves, retorts, and sterilizers (2) where the steam indirectly heats a liquid through a metallic surface, as in heat exchangers and kettles where the quantity of liquid heated is known and unknown (3) where the steam indirectly heats a solid through a metallic surface, as in dryers using cylinders or chambers and platen presses and (4) where the steam indirectly heats air through metallic surfaces, as in unit heaters, pipe coils, and radiators. 

Chapter 7, Reactor Design, discusses continuous and batch stirred-tank reactors and die packed-bed catalytic reactor, which are frequently used. Heat exchangers for stirred-tank reactors described are the simple jacket, simple jacket with a spiral baffle, simple jacket with agitation nozzles, partial pipe-coil jacket, dimple jacket, and the internal pipe coil. The amount of heat removed or added determines what jacket is selected. Other topics discussed are jacket pressure drop and mechanical considerations. Chapter 7 also describes methods for removing or adding heat in packed-bed catalytic reactors. Also considered are flow distribution methods to approach plug flow in packed beds. 

The most commonly used heat exchangers are the coil and double pipe for small heat-exchange areas and die sheU-and-tube design for large areas. Devore et al. [13] recommend that if ... 

Figure 7.3 compares calculated overall heat-transfer coefficients for several reactor heat exchangers, using water for both the jacket and reactor fluid. The figure shows that the highest heat-transfer coefficient is obtained with internal coils and the lowest with the simple jacket (called the conventional jacket in Figure 7.3) without a spiral baffle or agitation. It is assumed that the flow rate for the internal coil is the coil flow rate and not the jacket flow rate, as plotted in Figure 7.3. Heat-transfer coefficients for the half-pipe coil, agitated, and baffled jackets are conparable.

Most of the simulators allow heat input or removal from a plug-flow reactor. Heat transfer can be with a constant wall temperature (as encountered in a fired tube, steam-jacketed pipe, or immersed coil) or with counter-current flow of a utility stream (as in a heat exchanger tube or jacketed pipe with cooling water). 

A mixing reactor was developed by Hoechst AG at the end of the 1970 s, whose square cross-section was filled with meander-shaped heat exchange tubes [382, 385], see Fig. 8.8. The individual coils of piping are inclined in an opposing sense to the neighboring position, whereby a network results, which is similar to that of the Sulzer SMX mixer. This device has been commercialized by Sulzer AG as the SMR mixer. 

Small tubes are commonly employed where the reaction is rapid and/or the heat of reaction must be removed rapidly. The two conventional types of tubular reactors are (1) coils immersed in a constant-temperature bath and (2) a jacketed pipeline in which the inner tube is designed to withstand the reaction pressure. A modification of the conventional jacketed-pipe reactor can be used where it is desirable to minimize the thickness of the inner tube in order to reduce the area required for heat transfer. An example of this type of equipment is the liquid-phase heat exchanger of the Bureau of Mines, in which the outside pipe has an outside diameter of 4 2 ill- wall thickness of 1.005 in. The outside diameter of the inner tube is in., but the wall thickness is only 0.16 in. The worldng... 

In the operation of large units, heating of the ingoing materials is best accomplished by heat exchange wiUi the outgoing materials and adding additional heat by means of high-pressure pipe coils. A pipe coil is the... 

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