Leaking Heat Exchangers

Tube leaks may occur in the reboiler, condenser, preheater, precooler, or any other heat exchanger linked with the column. Several experiences where leakage caused poor performance have been reported (71, 238, 239). The effect of a leaking heat exchanger tube depends on the magnitude, the direction, and the location of the leak. 

Effects of heat exchanger tube leaks into the column include off-spec products and/or undesirable chemical reactions. In some cases, this reaction may lead to rapid corrosion or plugging. It is important to realize that material leaking at the condenser or at an intermediate exchanger may travel to the column base and decompose there. In one vacuum column, water leaking at the condenser reached the reboiler and caused a pressure surge and tray damage (358). 

Effects of heat exchanger tube leaks out of the column include inability to maintain column pressiure, erratic performance of reboiler or condenser, and erratic performance in other units because of contamination of the heat transfer medium. One classic experience (239) of an extremely sick column performance caused by a leaking reboiler was described in Sec. 1.2. 

Techniques for detecting leaks out of the colunm are similar to tiiose for leaks into the column, except that the heat transfer medium, rather that the products, should be analyzed. Often, testing a heat exchanger drain or vent can reveal the presence of a leak. Specific sjmip- 

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Reactions have often taken place in waste containers because assorted substances were added indiscriminately [8]. Leaking heat exchangers can also cause contamination as described above. 

Leaking heat exchangers released vapors which ignited. 

At Lawrence Livermore National Laboratory site 300, these compounds along with trichloroethylene (TCE) were used in heat-exchanger pipes at their materials testing facility [421-423]. Subsurface contamination by these compounds resulted from leaking heat-exchanger pipes. TBOS and TKEBS were present as light non-aqueous phase liquids whereas TCE was present as a dense... 

The feed stream. Water may be present in the feed storage tank, may enter the feed from a leaking heat exchanger, or may not be entirely removed in an upstream removal facility. 

FIGURE 24-2 "Wet glycol may contaminate dry glycol because of a leaking heat exchanger. 

Leak size determination at a refinery heat exchanger... 

Most fast reactors that use Na or NaK as coolant utilize an intermediate heat exchanger (IHX) that transfers heat from the radioactive core coolant to a nonradio active Hquid-metal coolant loop, which has the reactor s steam generator. This helps minimize the spread of contamination in the event of a leak or fire. 

Steam can be contaminated with soHds even when carryover is not occurring. Contaminated spray attemperating water, used to control superheated steam temperature at the turbine inlet, can introduce soHds into steam. A heat exchanger coil may be placed in the boiler mud dmm to provide attemperation of the superheated steam. Because the mud dmm is at a higher pressure than superheated steam, contamination will occur if leaks develop in the cod. 

Testing for leaks in heat exchangers was discussed by Rubin [Chem. Eng., 68, 160-166 (July 24, 1961)]. 

Even the best modern low-temperature air separation plant has an efficiency only a small fraction of the theoretical optimum, that is, about 15 to 20 percent. The principal sources of inefficiency are threefold (1) the nonideality of the refrigerating process, (2) the imperfection of the heat exchangers, and (3) losses of refrigeration through heat leak. 

Implement procedures for leak/pressure testing of jacket, coil or heat exchanger prior to operation... 

Rich glycol is leaking into lean glycol in the glycol heat exchanger or in the glycol pump... 

No one realized, when a site for the furnace was decided, that flammable vapors could come out of the cooling tower. Direct contact condensers are not common, but flammable vapors can appear in many cooling towers if there are leaks on water-cooled heat exchangers. After the incident, a combustible gas detector was mounted permanently between the furnace and the tower (Figure 2-8). 

A leak in another heat exchanger allowed flammable gas to enter a cooling-water return line. The gas was ignited by welding, which was being carried out on the cooling tower. The atmosphere had been tested before work started, five hours earlier (see Section 1.3.2). 

GHXTLK Glycol heat exchanger tube leak... 

Equipment Failure pumps, tubes in heat exchangers and furnaces, turbine drivers and governor, compressor cylinder valves are examples of equipment which might fail and cause overpressure in the process. If an exchanger tube splits or develops a leak, high pressure fluid will enter the low side, overpressuring either the shell or the channels and associated system as the case may be. 

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