A multi-stage compressor unit including at least a first compressor stage including a first compressor element driven through a first gear-transmission and a second compressor stage including a second compressor element driven through a separate second gear-transmission. The first and second gear transmissions include a driving gear and a driven gear configured to be a multiplier, each of the driven gears is connected to a shaft of a rotor of the first compressor element or second compressor element respectively, where the first motor and the second motor re adapted to drive the first compressor stage and the second compressor stage separately. The gear ratio between the driven gear and the driving gear of either one of the first gear transmission and second gear transmission is situated between two and six.

A conical screw compressor or pump comprising: an inner element configured to rotate around a first axis; and an outer element configured to rotate around a second axis; wherein an outer surface of the inner element and an inner surface of the outer element comprise cooperating grooves and teeth that intermesh on rotation; the first axis and the second axis are each stationary and the first axis is inclined relative to the second axis; and the inner element and the outer element are configured to be, in operation, synchronously rotated, thereby to reduce or eliminate force exerted by the inner element on the outer element or vice versa.

A conical screw compressor or pump comprising: an inner element configured to rotate around a first axis; and an outer element configured to rotate around a second axis; wherein an outer surface of the inner element and an inner surface of the outer element comprise cooperating grooves and teeth that intermesh on rotation; the first axis and the second axis are each stationary and the first axis is inclined relative to the second axis; and the inner element and the outer element are configured to be, in operation, synchronously rotated, thereby to reduce or eliminate force exerted by the inner element on the outer element or vice versa.

A compressor includes a bore, a rotor disposed within the bore, a compressor inlet, a compressor outlet and a compression chamber defined between the bore and the rotor. A volume of the compression chamber gradually reduces from the compressor inlet to the compressor outlet. An economizer is configured to fluidically connect to the compression chamber. The economizer is configured to inject a working fluid into the compression chamber at an injection position. The injection position is changeable according to a working condition of the compressor.

A compressor includes a bore, a rotor disposed within the bore, a compressor inlet, a compressor outlet and a compression chamber defined between the bore and the rotor. A volume of the compression chamber gradually reduces from the compressor inlet to the compressor outlet. An economizer is configured to fluidically connect to the compression chamber. The economizer is configured to inject a working fluid into the compression chamber at an injection position. The injection position is changeable according to a working condition of the compressor.

A compressor system is provided that includes a contact cooled compressor and a coolant separator. The coolant separator is used to remove coolant fluid from a compressed flow stream produced by the contact cooled compressor during its operation. The coolant separator routes the removed coolant fluid back to the contact cooled compressor for further use. In some forms the coolant fluid is cooled prior to delivery back to the compressor. A stop valve can be provided in the coolant fluid return line to halt the flow of the fluid. A pressure sensitive member can be disposed to sense pressure of the coolant fluid that has been routed past the stop valve. Operation of the compressor can be changed as a result of the sensed pressure from the pressure sensitive member. Information from a temperature sensitive member can also be used to change operation of the compressor.

A compressor system is provided that includes a contact cooled compressor and a coolant separator. The coolant separator is used to remove coolant fluid from a compressed flow stream produced by the contact cooled compressor during its operation. The coolant separator routes the removed coolant fluid back to the contact cooled compressor for further use. In some forms the coolant fluid is cooled prior to delivery back to the compressor. A stop valve can be provided in the coolant fluid return line to halt the flow of the fluid. A pressure sensitive member can be disposed to sense pressure of the coolant fluid that has been routed past the stop valve. Operation of the compressor can be changed as a result of the sensed pressure from the pressure sensitive member. Information from a temperature sensitive member can also be used to change operation of the compressor.

A compressor includes a bore, a rotor disposed within the bore, a compressor inlet, a compressor outlet and a compression chamber defined between the bore and the rotor. A volume of the compression chamber gradually reduces from the compressor inlet to the compressor outlet. An economizer is configured to fluidically connect to the compression chamber. The economizer is configured to inject a working fluid into the compression chamber at an injection position. The injection position is changeable according to a working condition of the compressor.

A compressor includes a bore, a rotor disposed within the bore, a compressor inlet, a compressor outlet and a compression chamber defined between the bore and the rotor. A volume of the compression chamber gradually reduces from the compressor inlet to the compressor outlet. An economizer is configured to fluidically connect to the compression chamber. The economizer is configured to inject a working fluid into the compression chamber at an injection position. The injection position is changeable according to a working condition of the compressor.

An apparatus for a submersible screw pump includes a cylindrical rotor located inside of a cylindrical stator. The rotor has a screw thread formed in an opposite direction in relation to screw threads of the stator. The external surface of the rotor has a curvilinear shape and the internal surface of the stator has semicircular shapes without rectangular edges. These surface features of the rotor and stator obtain high speed performance for the apparatus with reduced vortices. A gap between the internal surface of the stator and the external surface of the rotor is 0.1-0.2 millimeters. A unloading thrust bearing is attached to a rotor shaft positioned between an intake thrust bearing and the intake end of the rotor. A cavity in the unloading thrust bearing is configured to receive production fluid from the discharge end of the rotor.