Cylinder Cooling

Traditional compressor cylinder designs require cooling water jackets to promote uniform distribution of heat created by gas compression and friction. Some of the perceived advantages of water-cooled cylinders are reduced suction gas preheat, better cylinder lubrication, prolonged parts life, and reduced maintenance. 

Many manufacturers, users, and compressor applications still require that compressor cylinders be supplied with liquid-cooled cylinders. Figure 11-21 includes schematics of several types of liquid coolant systems. 

Cold suction gas provides cooling for the compressor and is sufficient to keep small machines at an acceptable working temperature. Refrigerantshaving high discharge temperatures (mainly ammonia) require the use of water-cooled cylinder heads. Oil coolers are needed under some working conditions which will be specified by the manufacturer. These maybe water cooled or take refrigerant from the system. 

Soap chips are made by running a thin sheet of melted soap onto a cool cylinder and scraping off the soaps in small broken pieces. Soap granules are dried miniature soap bubbles. Soap powders and scouring soaps contain some soap, a scouring agent (abrasive) such as powdered pumice or finely divided sand, and builders like sodium carbonate and trlsodlum phosphate. Builders make the soaps act more rapidly. The cleansing action of soap has been discussed in Unit 5. 

A two-stage double-acting compressor with water cooled cylinder jackets and intercooler is shown in Figure 7.18(c). Selected dimensional and performance data are in Table 7.7. Drives may be with steam cylinders, turbines, gas engines or electrical motors. A specification form is included in Appendix B. Efficiency data are discussed in Section 7.6, Theory and Calculations of Gas Compression Temperature Rise, Compression Ratio, Volumetric Efficiency. 

A second method involves the installation of cooling cylinders and wall scrapers (Figure 9). On large reactors this is complex and expensive. Great problems will ensue if the scraped-off material remains stuck to the scraper blades. Cleaning and dismanteling are extremely difficult. 

Figure 9. Reactor with cooling cylinder and scraper blades...

The web passes the screen vertically into the drier above the drying or pre-gelling of the print is by means of hot air blown on both sides of the web, the air being heated by thermal oil or, more usually, by direct gas firing. The volume of air circulated and its temperature are controlled and can be varied. After drying or pre-gelling the web must be cooled so that it will not carry heat to the next screen, and this is done by passing it round two water-cooled cylinders. 

The printing stations are connected mechanically a common line shaft system drives the cooling cylinders, screens, and web so that once the screens have been brought into registration this can be maintained by the accuracy of the drive. (However, a facility to adjust registration is provided at each printing station.)... 

The last three design concepts listed have the common feature that the gap width at a point on the cooling cylinder will vary as the shaft rotates. In the case of the oval tube the gap width varies when seen from a point rotating with the shaft. 

A-unit shaft to ensure rapid melting of the solidihed margarine inside the cooling cylinder. 

Figure 33 shows an SSHE with four cooling cylinders, one pin worker, and one inversion crystallizer mounted for production of low-fat spreads using the inversion technique. 

The crystallization process is normally controlled through a variation of flow rate, refrigerant evaporation temperature, or by changing the layout of the intermediate worker unit and cooling cylinders according to the oil blends used. 

Horizontal Cylinders. For a heated horizontal cylinder in perpendicular cross flow, the angle of the approaching stream, ( > in Fig. 4.47, greatly affects the heat flow in the mixed convection regime. For ( > = 0 the forced flow assists the natural convection and the dependence of the average Nus-selt number on Re resembles path A in Fig. 4.44. For = 90° there is a sharper transition from natural to forced convection than when 4> = 0, while for opposed flow (( > = 180°) there is a minimum as shown by path B in Fig. 4.44. For a cooled cylinder the same description applies except that ( > is measured from the vertical axis extending upward from the cylinder. 

EXPLOSION and FIRE CONCERNS noncombustible liquid nonflammable gas NFPA rating (not rated) contact with chemically-active metals (such as potassium (K), sodium (Na), calcium (Ca), powdered aluminum (Al), zinc (Zn) and magnesium (Mg)) will cause fires and explosions contact with flames and/or hot surfaces will emit hydrogen bromide, hydrogen fluoride, free bromine, and small amounts of carbonyl halides product is relatively toxic to humans at levels below fire extinguishing concentration product will not extinguish fires resulting from contact with chemically-active metals use water spray to cool cylinders involved in fires use media suitable for flammable materials in area. 

When larger quantities (about 1 kg.) must be sublimed in a single operation, the metal is condensed in an apparatus of larger capacity, using a water-cooled cylinder. 

Gas Hydraulic diameter Power for fixed flow area Power for fixed heat-transfer area Power for internally cooled cylinder Heat-transfer area for fixed flow area... 

Fig. 10.4 (a) Cavitation corrosion of a water-cooled cylinder casing of a diesel engine. Corrosion holes have penetrated the wall, (b) The water pump propeller in the same diesel engine corroded by cavitation... 

A03560 7.0 Si, 0.3 Mg Heat-treated (T6) 228 (33) 164 (24) 3.5 Aircraft pump parts, automotive transmission cases, water-cooled cylinder blocks... 

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