Abstract:
An oil-free rotary gas-compressor system includes an oil-free rotary gas-compressor (2) having a high, built-in pressure ratio and an injector arrangement (13) for injecting a vaporizable liquid, preferably water, into the compressor (2) for cooling the gas during the compression process. It is known in high-speed compressors to utilize water injection which is so restricted that the water is completely vaporized, to thereby obtain a good cooling effect. The efficiency of the compressor is limited, however. In known systems, high compressor efficiencies are obtained by injecting large quantites of water, although the compressor speed must then be considerably reduced, resulting in a lower compressor capacity. According to the present invention, a correspondingly high efficiency can be obtained, however, in a high-speed compressor when the water is injected into the compressor in a weight quantity which is greater than the maximum amount of liquid permitted for obtaining a complete vaporization of the liquid during the compression of the gas up to an amount that is four times greater than said maximum amount.
Abstract:
The invention relates to a method of manufacturing a rotor (12) for a helical screw machine that includes a metal shaft (2) and helical lobes (9) mutually separated by intermediate grooves (13), comprising the steps of providing the shaft (2) with a blind axially extending passageway (10); connecting the passageway (10) with the barrel surface of the shaft (2) by means of at least one channel (11) extending outwardly from the shaft; inserting the rotor shaft (2) in a mold (1) that includes two mutually spaced end-walls (4, 5) which have respective rotor shaft receiving openings (6 and 7), said openings (4, 5) embracing the rotor shaft (2, 19) at least in a generally sealing fashion; heating the mold (1) and the shaft (2) to the curing temperature of the polymer; delivering polymer-forming materials to the mold (1); maintaining the barrel wall (3) of the mold (1) at said curing temperature until the polymer has cured; and removing the rotor from the mold (1). The method is characterized by the further steps of disposing the outwardly extending channel (11) on the shaft (2) such that said channel will be located generally in the middle of the mold (1) when the shaft (2) is inserted therein; and pressing the polymer into the axially extending passageway (10) at an overpressure of at least 1 bar.
Abstract:
A rotary screw compressor having one or more stages (10, 20) is provided with a lift valve (14, 24) on each stage for unloading the compressor at starting up and rest periods. Each lift valve (14, 24) is biased by a spring (15, 25) towards an open position and can be closed by an actuator (17, 27). Each valve actuator (17, 27) is automatically controlled by an air conduit (32) establishing air communication between the discharge channel (23) of the compressor and each valve actuator (17, 27).
Abstract:
A rotary screw compressor having two rotors, liquid injection, a liquid separator (10), and a hydraulic thrust balancing piston (11) connected to at least one of the rotors. In order to vary the balancing force if suction and delivery pressures vary, there is provided first (5) and second (4) throttling devices in the return pipe from the oil separator to the liquid injection port. Between the first and second throttling devices there is a connection to a pipe branch (7) which ends in a cylinder (14) which houses the balancing piston (11). The balancing pressure acting on the balancing piston (11) will thereby vary as suction and delivery pressures vary in a way determined by the relation between the degree of throttling in the two throttling devices.
Abstract:
A rotor for a rotary screw machine has helical lobes (12) and grooves (14). A shell structure (18) forming the external surface of the rotor is made of pressed metal power. The rotor is manufactured by cold isostatic pressing of a powder in a vessel having a surface shaping rotor. The pressure is applied radially by means of a cast bag in which high pressure liquids acts. After the pressing process, the rotor blank is sintered and attached to a shaft (16).
Abstract:
A method of manufacturing rotors having helical lands and intermediate grooves wherein a multi-layer rotor body (2) is moulded or otherwise formed on a shaft (1) to only a small degree of accuracy, whereafter an outer layer (3) of polymer-based material is moulded on the rotor body to a high degree of accuracy. For the purpose of eliminating shrinkage-induced distortion of the lands of the rotor body (2) subsequent to applying the outer layer, the rotor body is produced in a multiple of layers (21, 22), by casting or like moulding processes, with each of the body layers having a thickness which is greater than that of the high accuracy outer layer (3).
Abstract:
A screw compressor of the kind incorporating at least one male rotor and one female rotor, with helically extending lands and grooves. The female rotor (1) is injection moulded from a plastics material having a modulus of elasticity of at most 25,000 N/mm.sup.2. The lands (3) of the female rotor have a thickness (a) which is so adapted to the modulus of elasticity of the plastics material as to allow the lands to be deflected resiliently when clashing with the other rotor (2), as a result of dimensional deviations of the order likely to occur during hardening or curing of the plastics material, or at prevailing temperature variations, but not as a result of the pressure exerted by the working fluid. Due to the injection moulding the surface smoothness is fine enough to make subsequent finishing unnecessary and damages caused by lack of machining are avoided because of the resilient deflecting of the lands of the female rotor when clashing with the other rotor.
Abstract:
The present invention relates to a compressor (1) that has an associated coolant circulation system (1, 4, 6, 8, 11, 13), and also to a method of maintaining a low bacteria content in the coolant circulating system (1, 4, 6, 8, 11, 13), in which method gas and coolant are supplied to the compressor (1) during running of the system and the gas is compressed in the compressor (1) to an outlet pressure, the gas and the coolant are removed together from the compressor (1) and then separated into a respective gas and a liquid phase, whereafter the gas is passed to a recipient and the liquid is cooled before being returned to the compressor as coolant. The method is characterized by creating bacteria-killing conditions intermittently in the system by appropriating the heat-generating capacity of the compressor (1) to raise the temperature of the circulating coolant to at least 55° C. for a duration of at least 15 seconds.
Abstract:
A rotary screw compressor for oil-free air, wherein at least one of the shaft journals (11) of the rotors (10) has a seal arrangement between the rotor (10d) and an oil-lubricated bearing (12). The seal arrangement includes at least three frictionless seals (13, 14, 15) separated by annular chambers (16,17). The outermost annular chamber (17) is connected to a source of pressurized air through a supply channel (19) for supplying blocking air to the seal, and another (16) of the annular chambers communicates with a withdrawal channel (18).
Abstract:
The invention relates to a rotary screw machine in which the shaft journals (20, 22) of the rotors (10) are journalled in a main thrust bearing (24) and a thrust balancing bearing (26). The thrust balancing bearing (26) is preloaded by springs (36) and by fluid pressure means (40, 44). According to the invention the fluid pressure means (40, 44) can excert a force on the thrust balancing bearing (26) in either axial direction. This increases the possibility for an optimal distribution of the forces on the thrust bearings (24, 26) at various running conditions.