Crankshaft, compressor

Horsepower is the work done in a cylinder on the gas by the piston connected to the driver during the complete compression cycle. The theoretical horsepower is that required to isen-tropically (adiabatically) compress a gas through a specified pressure range. The indicated horsepower is the actual work of compression developed in the compressor cylinder(s) as determined from an indicator card. Brake horsepower (bhp) is the actual horsepower input at the crankshaft of the compressor drive. It does not include the losses in the driver itself, but is rather the actual net horsepower that the driver must deliver to the compressor crankshaft. 

Power Take-Off From Engine or Transmission. This type of system is limited to tmcks and there are several take-off means available. Most are some form of electric power generation equipment, belt-driven from the engine crankshaft, which produces either a regulated a-c voltage or rectified direct current for the compressor and fan motors in the body. 

Babbitt ahoys ate suitable for hundreds of types of iastahations involving the movement of machinery, eg, the main, crankshaft, connecting tod big end, camshaft, and journal bearings associated with marine propulsion, tailtoad and automotive transportation, compressors, motors, generators, blowers, fans, rolling-mill equipment, etc. 

A more rare form of driver is the steam cylinder. Most arrangements combine the steam driver and compressor on the same frame with the steam cylinder opposite the compressor cylinder. Each cylinder s connecting rod is connected to a common throw on the crankshaft. A flywheel is used to provide inertia. For air service, the units are built as single- and two-stage units, with other combinations available for process service. 

The lowly piston, one of the more simple items, has one of the most important functions of the entire compressor. The piston must translate the energy from the crankshaft to the gas in the cylinder. The piston is... 

Larger compressors, normally above 150 to 200 horsepower, have forged steel crankshafts. Cast crankshafts are used in medium-size machines. Crankshafts should have removable balance weights to compensate for rotary unbalance as well as reciprocating unbalance. The crankshaft should be dynamically balanced when above 800 rpm. 

The cylinders are arranged on the main frame of the compressor to provide balanced crankshaft power loading (when possible), access for maintenance, piping convenience, and floor space to suit plant layout. Common designations by position of the cylinder are... 

Each valve opens and closes once for each revolution of the crankshaft. The valves in a compressor operating at 700 rpm for 8 hours per day and 250 days per year will have cycled (i.e., opened and closed) 42,000 times per hour, 336,000 times per day, or 84 million times in a year. The valves have less than i of a second to open, let the gas pass through, and to close. 

The oil pump is usually gear driven from the crankshaft so that it will start pumping oil immediately on start-up of the compressor. In compressors that work in an oil-free system, oil injectors are not used. Oil separators are installed on the discharge side after leaving the aftercooler. 

Few machines involve linear reciprocating motion exclusively. Most incorporate a combination of rotating and reciprocating linear motions to produce work. One example of such a machine is a reciprocating compressor. This unit contains a rotating crankshaft that transmits power to one or more reciprocating pistons, which move linearly in performing the work required to compress the media. 

Reciprocating compressors are positive-displacement types having one or more cylinders. Each cylinder is fitted with a piston driven by a crankshaft through a connecting rod. As the name implies, compressors within... 

In a two-cycle machine, all pistons complete a full cycle each time the crankshaft completes one revolution. Figure 44.9 illustrates the normal action of a two-cycle, or single-action, compressor. Inlet and discharge valves are located in the clearance space and connected through ports in the cylinder head to the inlet and discharge connections. 

Crankshafts on positive-displacement reciprocating compressors have offsets from the shaft centerline that provide... 

Horizontal reciprocating compressors (see Figure 44.10) should have X-Y data points on both the inboard and outboard main crankshaft bearings, if possible, to monitor the connecting rod or plunger frequencies and forces. 

Reciprocating Limitations of the frequency-domain analysis prevent total analysis of reciprocating compressors. It is limited to the evaluation of the rotary forces generated by the main crankshaft. Therefore, time-domain and phase analysis are required for complete diagnostics. 

Liquefaction by medium pressure (compression to 6—7 atm.) is obtained by two-stage vertical compressors made of special oast iron with water cooling and lubrication with concentrated sulphuric acid. The crankshaft of the compressor is located above the pistons. The compressors are built for a capacity of 5 000—40000 kg of chlorine per day. Compression takes place in two stages. At first the gas is compressed to 1.5—2 atm. overpressure. The gas heated by the compression to some 80 °C ) is led through a sulphuric acid separator. Sulphuric... 

One of the simplest devices for compressing fluids is a rotating-crankshaft compressor. In this instrument, a plunger piston is used to compress a volume of a few cubic centimetres of fluid. The thrust on the piston is generated by a hand screw with a capstan wheel. A typical pressure X volume value for... 

COMPRESSOR SEAL - Leak proof seal between crankshaft and compressor body in open type compressors. 

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