Trim Coolers

Trim Coolers Conventional air-cooled heat exchangers can cool the process fluid to within 8.3°C (15°F) of the design dry-biilb temperature. When a lower process outlet temperature is required, a trim cooler is installed in series with the air-cooled heat exchanger. The water-cooled trim cooler can be designed for a 5.6 to 11.1°C (10 to 20°F) approach to the wet-biilb temperature (which in the United States is about 8.3°C (15°F) less than the diy-bulb temperature). In arid areas the difference between diy- and wet-bulb temperatures is much greater. 

Check pressure drop between Fin-Fans and Trim Coolers... 

Step 8. Several control valves now remain unassigned. Steam flow to the trim heater controls reactor inlet temperature. Cooling water flow to the trim cooler is used to control the exit process temperature and provide the required condensation in the reactor effluent stream. Liquid recirculation in the absorber is flow-controlled to achieve product recovery, while the cooling water flow to the absorber cooler controls the recirculating liquid temperature. Acetic acid flow to the top of the absorber is flow-controlled to meet recovery specifications on the overhead gas stream. Cooling water flow to the cooler on this acetic acid feed to the absorber is regulated to control the stream temperature. Cooling water flow in the column condenser controls decanter temperature. 

Description The feed, either paraffinic or olefinic C -Cg fraction, is heated through heat exchangers and a furnace to the desired temperature. The vaporized feed is fed to the top of the aromatization reactor. There are two reactors in series are in operation, and the other two reactors are in regeneration or standby. The effluent from the bottom of the second reactor is fed to the aromatization feed/effluent heat exchanger. After the feed/effluent heat exchanger, the reactor effluent is further cooled by air coolers and trim coolers with cooling water and chilled water. This cold effluent is then sent to the aromatization effluent separator (low pressure) where the rich net gas stream is separated from the aromatic-rich liquid. 

According to the diagram shown here, the major part of the remaining heat in the raw gas is used in a downstream heat exchanger to heat up boiler feed water before the raw gas flows through a trim cooler to be cooled to ambient temperature. Needless to say, other ways of utilizing the heat are conceivable from case to case. 

If not used as quench water, the tar and oi -laden gas liquor from the waste heat boiler is split up in the tar separator (see Sect. 5.1) into a dusty tar, a thin tar, and a gas liquor fraction. The condensate from the feed water preheater, like some of the condensate from the waste heat boiler, is used as quench water in the wash cooler. The trim cooler condensate, which essentially contains only hydrocarbons with boiling points of less than 100 °C, is sent to the oil separator to be separated into an oil fraction and a gas liquor fraction. The gas liquor passes an additional oil trap and then goes to the Phenosolvan unit. 

Air cooled induced draft preferred to forced draft to minimize hot gas recirculation. Include a water-cooled trim cooler . Ensure the exit tubes are flooded so that the vapor does not bypass condenser. If extreme cold conditions are expected, allow for fan to operate in reverse to counteract the overcooling by the natural circulation of cold air. 

Samyudia [9] developed a nonlinear SFE model by applying fundamental dynamic mass and energy balances for five units extractor, flash, stripper, reboiler and trim-cooler. The dynamics of the compressor and condenser are assumed to be much faster than the rest of the process, and steady state models are used for these units. The process was then linearised at the operating point and steady state values given in Table 1. This resulted in a linear state space perturbation model ... 

Liz and I were recently working a job at a refinery in Illinois. The pumparound trim cooler steam generator for the fractionator was thought to be leaking water into the pumparound return hot gas-oil... 

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