Piping arrangements exchangers

One of the simplest and cheapest types of heat exchanger is the concentric pipe arrangement known as the double-pipe heat exchanger. Such equipment can be made up from standard fittings and is useful where only a small heal transfer area is required. Several units can be connected in series to extend the capacity. ... 

Double-pipe exchangers-the simplest type with concentric pipe arrangement used for cooling and heating several units can be connected in series to extend their capacity. ... 

Single-pass Tube Side. For these conditions, no baffle is in either the head or the return end of the unit. The tube-side fluid enters one end of the exchanger and leaves from the opposite end. In general, these baffles are not as convenient from a connecting pipe arrangement viewpoint as units with an even number of passes in which the tube-side fluid enters and leaves at the same end of the exchanger. See Figures 10-IC and 10-lG and Table 10-1. 

Longitudinal fins can also be used, but their application is restricted to small heat exchangers in the form of a concentric pipe heat exchanger, similar to the schematic in Figure 15.5a. In this arrangement, the inner tube would be the extended surface tube with the fins in the annular space to enhance the heat transfer. Longitudinal fins can increase the surface area by a factor of 14 to 20 relative to plain tubes. 

One type of heat exchanger has already been mentioned, that of a double-pipe arrangement as shown in Fig. 10-2. Either counterflow or parallel flow may be... 

Consider the double-pipe heat exchanger shown in Fig. 10-2. The fluids may flow in either parallel flow or counterflow, and the temperature profiles for these two cases are indicated in Fig. 10-7. We propose to calculate the heat transfer in this double-pipe arrangement with... 

If a heat exchanger other than the double-pipe type is used, the heat transfer is calculated by using a correction factor applied to the LMTD for a counterflow double-pipe arrangement with the same hot and cold fluid temperatures. The heat-transfer equation then takes the form... 

Hot water at 90°C flows on the inside of a 2.5-cm-ID steel tube with 0.8-mm wall thickness at a velocity of 4 m/s. This tube forms the inside of a double-pipe heat exchanger. The outer pipe has a 3.75-cm ID, and engine oil at 20°C flows in the annular space at a velocity of 7 m/s. Calculate the overall heat-transfer coefficient for this arrangement. The tube length is 6.0 m. 

Consider a water-to-water double-pipe heal exchanger whose flow arrangement is not known. The temperature measurements indicate that the cold water enters at 20°C and leaves at 50 C, while the hot water enters at 80°C and leaves at 45 C. 

Another example is shown in Figure 7-63. Relocating nozzles on the exchanger shell (sketch B) results in a simpler piping arrangement than shown on sketch A. 

Lines interconnecting exchangers with other process equipment can run just above the required headroom or about on the same level as the yard piping. Reboiler line elevations are determined by the draw-off and return line nozzles on the tower. Symmetrical reboiler piping arrangements — between the tower draw-off and reboiler inlet nozzles and between reboiler outlets and return... 

Access to valve headwheels and instruments will influence piping arrangement around heat exchangers. Valve handwheels should be accessible from grade and from a convenient access way. These access ways should be used for arranging manifolds, control valves and instruments. 

EXHIBir6<31 Piping Arrangement for Horizontal %ell and Tube Exchangers... 

EXHIBIT 6-38 Piping Arrangement for High-Tcmpcrature, High-Pressure Feed Exchangers... 

The reactor visualized by the Columbia group was one in which an extremely dense suspension of uranium in D2O would be pumped through a large number of pipes arranged inside a heavy-water moderator. It was planned that both the slurry and the moderator would be circulated through heat exchangers for cooling [6]. 

Double-pipe exchangers are often piped in complex series-parallel arrangements on both sides. The MTD to be used has been derived for some of these arrangements and is reported in Kern (Process Heat Transfer, McGraw-Hill, New York, 1950). More complex cases may require trial-and-error balancing of the heat loads ana rate equations for subsections or even for individual exchangers in the bank. 

Normally, heat exchanger tubes are arranged in a staggered manner. The continuous plate is considered as being built up of regular hexagons, with a hole in the center for the pipes. This arrangement is shown in Fig. 9.9. 

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