Plant refrigerating systems

In order to calculate the refrigeration work requirements of oxygen plants, it is necessary to focus attention on specific refrigeration cycles. Two Claude type cycles are used in this report. One is a low pressure cycle in which all of the process air is used to produce the refrigeration. The expander exhaust is at 6 atm. Such a system involves about the lowest pressure that would be used in any air plant refrigeration system. This cycle is shown in Figs. 1 and 2. 

The following information was used in olefin plant case studies to determine if the ethylene/propylene cascaded refrigeration systems had enough horsepower for various plant operations. The propylene was condensed against cooling water at 110°F and the ethylene was condensed against propylene at -20°F. For comparison, the horsepower requirements for each refrigerant alone are also shown. 

The facility stores ammonia to supply nearby fertilizer manufacturers. It is transported to the plant by ship, transferred and stored in the tank for transfer as needed. The facility mainly consists of a storage tank, a refrigeration system, a control system, and a pipe connecting the tank with the plants. Ammonia is transported and stored as a refrigerated liquid (-33 C) at atmospheric pressure. 

Assume that this load can be handled best in two units operating in parallel. In this scenario, if one condenser develops trouble, the entire refrigeration system, and con-sequendy the plant process, is not shut down. 

Figure 11 -59. Representative expander refrigeration systems for temperature requirements and/or power recovery. (A) Expander coupled to a generator recovers pressure-loss energy for conversion to electric power. (B) System for power recovery from reactors in chemical processing plants. (C) Typical waste-heat recovery system using expansion turbines to generate electrical power. (Used by permission Bui. 2781005601. Atlas Copco Comptec, Inc.)...

Life expectancies are 15-20 years for refrigeration systems, and somewhat less for small packaged equipment. Where the need is for a shorter period, such as a limited production run or for a temporary building, equipment of lower quality or secondhand plant could be considered. 

A building or process having a large number of separated cooling loads could have a refrigeration system for each of these loads. It will usually be more convenient to concentrate the cooling into one plant. 

Dairy farms have bulk-storage tanks with their own refrigeration plants. These are usually made in the form of a double-skin, insulated tank, having the evaporator coils in the jacket, which also contains water. The refrigeration system runs throughout the 24 hours and... 

The user will not normally add oil to a refrigeration system, apart from an industrial R.717 plant which will have a routine for the draining of parts of the circuit and replenishing the compressor sump. 

Air-cooled acid plants, 18 822 Air-cooled condensers, 23 218 in refrigeration systems, 21 537 Air cooler fans, as a source of noise, 19 522 Air core, in hydrocyclones, 22 285, 286 Aircraft... 

A combined split-shaft gas turbine power plant and gas refrigeration system to be used in an airplane, as illustrated in Fig. 6.41a, has been designed by a junior engineer. 

During the cruise condition, the split-shaft gas turbine power plant required to produce 240 kW and 10% of the compressed air, is used in the gas refrigeration system, which is required to remove 7kW from the cabin. 

Figure 6.41a Combined gas turbine power plant and gas refrigeration system design. 

Flow Sheet and Mass Balances. Figure 2 represents a flow sheet of the 15,000-gallon-per-day pilot plant. The four major components are the freezer, the wash-separation column, the ice melter, and the vapor-handling device. The other essential components are the deaerator, which removes air from the saline water before it enters into the evacuated freezer the auxiliary refrigeration system, which removes heat leakage into the system and thermal inefficiencies of the process an ice scraper, pumps, controls, and instruments. 

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