Compressed air supply

Steam is the preferred atomizing medium, since it is more economic than compressed air. Steam consumption is typically less than 0.5 per cent of the fuel burnt on a mass basis, although this rises in direct proportion to turndown ratio. On very large burners, the steam flow is modulated in proportion to fuel burnt. Turndown ratios range from about 5 1 for small shell boilers to 12 1 in watertube applications, making this one of the most versatile burners. The steam condition is important in that it must be dry saturated or slightly superheated at the nozzle to avoid condensate formation. On small or non-continuously running plant where no steam is available for start-up a compressed air supply must be provided until steam becomes available from the boiler. 

Figure 41.1 shows a typical compressed air supply system. The following describes the functions of the system components ... 

Most plants are highly dependent upon their compressed air supply and it should be assured that the air is in at least reasonable condition at all times, even if the drying system is out of use for maintenance or repair. It is possible that the line condensation would be so bad that some air applications would be handicapped or even shut down if there were no protection. A vital part of the entire endeavor to separate water in the conventional compressed air system is also the trapping of dirt, pipe scale and other contaminates. This is still necessary with a dried air system. As a minimum, all branch lines should be taken off the top of the main and all feeder lines off the top of branch lines. 

The outlet of the compressed air supply point is opened and purged for 5 min. Adjust to a flow volume of about 30 1/min. Then the compressed air is passed through an air sampler equipped with a 0.22 pm filter. Sampling time should be about 5 min. This procedure should be performed three times. One filter should later be incubated for anaerobic, the other for aerobic viable count. Viable count should be < 200 CFU/m. ... 

Compressed air. The pressure of the compressed air supply should be measured during a complete operational cycle of the equipment. Record the pressure at the beginning, middle, and end of the cycle. 

Another Incident with Nitrogen Backup for a Compressed Air Supply... 

The procedure was to clear the transfer fine of the waxy material with compressed air supply just before the transfer fine was put in service. On the evening of the accident, an operator connected an air hose to a 90 psig (6 bar) supply to clear the entire 200 meters (600 ft.) of feed line. The operator then walked to the elevated tank to determine if air could be heard rushing out of the tank vent. He heard nothing. The operator spoke to two maintenance employees working near the end of the 20-m3 (700 ft3 or 5,300 gallon) tank and left the area to find his supervisor. Shortly after that, one end of the tank blew off, and the two maintenance mechanics plunged some 40 ft. (12 m) to their deaths. [7]... 

Industrial clean compressed air supply systems normally operate at about 550 kPa to 710 kPa (80 psi to 100 psi) and this pressure may be sufficient for many forming applications. Certain pressure forming equipment operate at pressures up to about 2500 kPa (360 psi), with some processes operating up to at least 4 MPa (580 psi). These pressures are very low when compared to those commonly used for injection molding or extrusion (Chapters 4 and 5). 

Check the electrical connections to the heating coil. Connect the T tube to a compressed-air supply turn on the air, adjust to a barely audible flow, and attach the T tube to the top of the inner vessel. Turn on the stirring motor. 

The procedure was to clear the transfer line of the waxy material with a compressed air supply just before the transfer line was put in service. On the evening of the accident, an operator connected an air hose to a 90 psig (6 bar) supply to clear the entire 200 meters (600 ft.) of feed line. The operator then walked to the elevated tank to determine if air... 

A device using an alternative principle to that of the jet and ultrasonic nebulizers has been described but has not been adopted to any extent. The Babington nebulizer, shown in Fig. 7, uses a principle that was first devised for fuel atomization [143]. Liquid (for the purposes of this discussion, a drug solution) is supplied to the outer surface of a hollow sphere. A thin film forms over the entire surface of the sphere. Compressed air supplied to the interior of the sphere expands through a small rectangular orifice at the top of the dome. Fine liquid particles form as escaping air ruptures a portion of the liquid film... 

Figure 6.4. Detailed diagram of hardware configuration for post-column addition of SPR. (1 = Conductivity detector Waters 431 detector, four electrode cell design 2 = waste line 4 x 0.009 in. stainless connected to 431 + 24 X 1/16 X 0.060 in PTFE tubing 3 = tee to 431 15 x 1/16 x 0.010 in PTFE to 431 inlet 4 = column to lee shortest 1/16 x 0.010 in PTFE from column to tee 5 = tee Unmount tee from check valve block for shortest path length 6 = analytical colunm Waters 1C PAK A or 1C PAK A HR 7 = check valve to tee 2 x 1/8 in o.d. PTFE 8 = check valve 9 = polisher column to check valve 3 x 1/8 in o.d. PTFE 10 = polisher column 8 x 25 mm containing AGI x 8, 200 mesh 11 = reservoir to polisher column 12 x 1/8 in. o.d. PTFE 12 = air supply minimum of 90 p.s.i. compressed air supply 13 = reservoir for SPR reconfigure with outlet on left side. From Ret [9] with permission.)...

Underground, the mine is crossed by a major slip-fault, with the result that one half of the workings is about 20 feet lower than the other. Two sloping haulageways were driven to connect the upper and lower sections to enable wagons to be drawn up these inclines two steam winches were installed, adapted to operate on compressed air supplied by compressors housed on the surface. Generally, however, loaded trucks were manoeuvred manually throughout the level areas of the quarry. 

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