Cooling units

The equipment needed includes a balance tank, regenerative heating unit, positive pump, plates for heating to pasteurization temperature, tube or plates for hoi ding the product for the specified time, a flow-diversion valve (FDV), and a cooling unit (Fig. 4). Often the homogenizer and booster pump also are incorporated into the HTST circuit. 

Carbon steel and alloy combinations appear in Table 11-12 Alloys in chemical- and petrochemical-plant sei vice in approximate order of use are stainless-steel series 300, nickel. Monel, copper alloy, aluminum, Inconel, stainless-steel series 400, and other alloys. In petroleum-refinery sei vice the frequency order shifts, with copper alloy (for water-cooled units) in first place and low-alloy steel in second place. In some segments of the petroleum industiy copper alloy, stainless series 400, low-alloy steel, and aluminum are becoming the most commonly used alloys. 

Ground area and. space requirement.s. Comparisons of the overall space requirements for plants using air cooling versus water cooling are not consistent. Some air-cooled units are installed above other equipment—pipe racks, shell-and-tube exchangers, etc. Some plants avoid such inst ations because of safety considerations, as discussed later. 

Example. A water-cooled unit with an evaporator temperature of-40°F will require 3 horsepower/ton of refrigeration. A ton of refrigeration is equal to 12,000 BTU/hr. Here are equations for these curves in the fonn ... 

Water flows inside the tubes, and vapors eondense on the shell side. Cooling water is normally chilled, as in a cooling tower, and reused. Air-eooled surfaee eondensers and some water-cooled units eondense inside the tubes. Air-cooled condensers are usually construeted with extended surfaee fins. 

Although these units find initial application in areas of limited water, they have not been limited to this situation. In many instances they are more economical than cooling tower systems and have been successfully applied in combination with cooling towers (see Figure 10-184). Economic comparisons should include such items as tower costs, basin, make-up facilities, water treatment, pumps for circulation, power supply, blow down, piping, etc. For small installations of air-cooled units, they should be compared... 

Ground space often < cooling towers can also serve dual purpose by mounting air-cooled units above other equipment or on pipe ways or roofe of buildings. Vibration is no problem. 

Tj, Tj = inlet and outlet tube-side fluid temperature of fin unit FV = face velocity, ft/min, entering face area of air cooled unit... 

Heat generated by the compressor and prime mover must be dispersed. For air-cooled units sited in enclosed rooms this heat must be removed in order to limit the temperature rise. It is sometimes possible to recover this heat for use elsewhere. Intake openings should be located so that dust and other foreign matter do not enter with the air. 

Ventilation around a compressor is vital. On a motor-driven, air-cooled unit, the heat radiated to the surrounding air is at least 65 per cent of the power input. On a water-jacketed unit with an aftercooler and outside receiver, the heat radiated to the surrounding air may be 15 to 25 per cent of the total energy input, which is still a substantial amount of heat. Positive outside ventilation is recommended for any compressor room where the ambient temperature may exceed 104°F. 

In conventional compressed air systems, vapor and liquid removal is limited. Most two-stage compressors will include an intercooler between stages. On air-cooled units for 100 to 200psig service, the air between stages is not cooled sufficiently to cause substantial liquid drop out and provision is not usually made for its removal. Water-cooled intercoolers used on larger compressors will usually cool sufficiently to condense considerable moisture at cooler pressure. Drainage facilities must always... 

Dairy work Applications include vessels for milk storage and sterilisation, cooling units, cream separators and cheese and butter-making equipment, as well as general dairy fittings, bottle-washing machinery and tankers for bulk milk transport. Extensive use is made of these steels in equipment used in production of ice cream and dried milk. 

The requirement for transport air-conditioning or refrigeration is for an air cooling, air-cooled unit with reliable availability of service. 

Winter heating items fitted within room air-conditioners may be electric resistance elements, hot water or steam coils, or reverse cycle (heat pump). One model of water-cooled unit operates with a condenser water temperature high enough to be used also in the heating coil. 

Fluorescence microscopy measurements were performed with a Zeiss Axioplan microscope (Zeiss Co. Germany) equipped with a mercury lamp and a 40X objective. Images were acquired by CCD camera CH250 (Photometrix Co., Germany) cooled at -40°C by a liquid cooling unit CH260 (Photometrix Co., Germany). 

ISPP imits are not the only micro device imits of interest for space applications micro fuel cells, compact cleanup units for water treatment, portable heating and cooling units and devices for chemical processing and mining are considered [91]. 

Fig. 1 Polymerisation reactor with its cooling unit and bursting disc.

This experiment requires a horizontal electrophoresis apparatus, power supply, and a gel-pouring tray with a comb to form sample wells. The FB 1001 apparatus available from Fisher Biotech and an apparatus available from EdVotek both are appropriate. The gel-pouring tray with combs is also available from EdVotek. Directions for preparing the tray accompany the unit. The Fisher apparatus includes a cooling unit that allows running at a constant temperature. In the EdVotek apparatus, the gel is under buffer. Since samples are loaded after the gel is immersed in buffer, sucrose must be added to increase sample density. 

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