Refrigeration plants in the chemical industry
The pharmaceutical industry, as already mentioned, the user refrigeration in freeze-drying processes. Approach, which seems to be popular in the industry, which is also to cool the liquid, and distribute this cold fluids (antifreeze, ethylene glycol or alcohol, for example) the place where refrigeration is needed. Low alcohol can cool jacket vessel, or glycol can be sent by air-cooling coils are located in the room where the powder filling occurs that must be maintained at low humidity.
Chemical, petrochemical and oil-refining industry, often require large refrigeration plants. Some important operations frequently require cooling:
- the splitting of a single gas other way liquefaction more than one gas
- the condensation of gases, such as the capture of removal of gas from liquid storage tank
- solidification of one substance in the mixture to separate it from the other
- contents stored liquid at low temperatures to control the pressure in the vessel, containing the
- removing the heat of reaction
- humidity control for hygroscopic substances
Two main concepts in the provision of refrigeration are direct and indirect.
In direct cooling of the product itself refrigerant and compressed, liquefied and strangled in the form of a liquid at low temperatures. The petrochemical industry is often used propane, ethane, ethylene, for example, as refrigerants. Often these chemical plants, large and traditionally use high-capacity centrifugal compressors, as shown in Fig. 1.6. Object, as shown in the liquefied petroleum gas fractionation plant, where 8 in two stages centrifuges compress propane in the refrigeration cycle. An alternative approach, to provide indirect cooling using a skid-mounted package that uses ammonia or suitable refrigerant freon. Or ammonia refrigerant freon from the package serves as a heat exchanger performing cooling, or in some cases, the pump delivers a low-average temperature of the refrigerant in heat exchanger. The frame is mounted package in Fig. 1.7 provides the low-temperature refrigeration due to the combination of two schemes, one with the use of R-22 and other carbon dioxide.
List only a few industries and temperature range of their cooling requirements: pre-cooling the air before separation10, -100C (-148F); condensation of hydrocarbons vapors11 occurring at -55C (-67F); and in the manufacture of such substances as ammonia/urea, aniline dyes, butadiene, butyl rubber, chlorine, pesticides/herbicides, synthetic rubber, vinyl chloride, and xylenes, as well as in the recovery of solvents.