Tube bundle location

Economizers, which are tube bundles located in the exit-gas system... 

Superheaters and reheaters are tube bundles located in either the boiler furnace section or the convection-pass section. They are designed to increase the temperature of generated steam prior to its being passed to a turbine. Many larger power boiler designs incorporate a steam reheater in addition to one or two banks of superheaters. 

Basically, there are two types of air cooler according to tube bundle location relative to air fan in the unit For forced draft air cooler, tube bundles are located at the discharge side of air fans. For induced draft air cooler, tube bundles are located at suction side of air fans. See Figure S for the difference of these two types of air cooler. Most air coolers are of forced draft type. 

The other space-saving approach is to use the Kobe (Kobe Steel) type of channel enclosure, which does not have all the external head bolts of typical TEMA Type B or Type C head enclosures. These exchangers require special tools to remove the tube bundles and trained maintenance personnel to do the work. These exchangers should never be located in stmctures because of the need to be able to access the channel from grade as it is difficult to remove the channel cover plate by using special equipment. 

Forced and Induced Draft The forced-draft unit, which is illustrated in Fig. 11-43 pushes air across the finnedtube surface. The fans are located oelow the tube bundles. The induced-draft design has the fan above the bundle, and the air is pulled across the finned tube surface. In theoiy, a primaiy advantage of the forced-draft unit is that less power is required. This is true when the air-temperature rise exceeds 30°C (54°F). 

Interdeck arrangement The tube bundle is located between banks of primary boiler tubes... 

A type of tube bundle superheater located in the radiant section of a WT boiler. 

Heat exchangers need to be sited so that the tube bundles can be easily withdrawn for cleaning and tube replacement. Vessels that require frequent replacement of catalyst or packing should be located on the outside of buildings. Equipment that requires dismantling for maintenance, such as compressors and large pumps, should be placed under cover. 

The multitubular fixed-bed reactor (Fig. IB) constitutes the oldest and still predominant representative of this class. The catalyst packing is located in the individual tubes of the tube bundle. The heat-transfer medium is circulated around the tube bundle and through an external heat exchanger, in which the heat of reaction is supplied or removed ( Fig. 16). Whereas with endothermic reactions circulating gas can be used as heat transfer medium, for strongly exothermic reactions exclusively liquid or boiling heat transfer media are used. Only in this way can the catalyst temperature (c.g., in the case of partial oxidations) be held in the narrow temperature range necessary for selective reaction control. 

Stratco Reactors. These reactors designed by Stratco, Inc. produce about 34% of the alkylate produced worldwide (P. Pyror, personal communication). In 2003, Stratco was purchased by E.I. du Pont de Nemours, Inc. A reactor, often called a Contactor, is a horizontal cylindrical vessel, as shown in Fig. 1, with the following features. An impeller at one end recirculates the acid/hydrocarbon dispersion many times (on average) over a U-tube bundle to regulate the temperature of the dispersion at about 5-10°C. A cylindrical circulation shell located in the reactor provides an annular space so that the dispersion flows from one end of the reactor to the other, where it makes a 180° turn and flows back over the tube bundle. 

Access for initial construction and maintenance is a necessary part of planning. For example, overhead eciuipment must have space for lowering into place, and heat-exchange equipment should be located near access areas where trucks or hoists can be placed for pulling and replacing tube bundles. Thus, space should be provided for repair and replacement equipment, such as cranes and forked trucks, and for snow-removal cciuipmcnt, as well as access way around doors and underground hatches. 

Insufficient heat transfer improper impeller selection/fouled tubes/no baffling/ tube bundles poorly located so as not to supply good baffling. 

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