An improved variable geometry diffuser (VGD) mechanism for use with a centrifugal compressor. This VGD mechanism extends substantially completely into the diffuser gap so that the VGD mechanism may be used more fully to control other operational functions. The VGD mechanism may be used to minimize compressor backspin and associated transient loads during compressor shut down by preventing a reverse flow of refrigerant gas through the diffuser gap during compressor shutdown, which is prevented because the diffuser gap is substantially blocked by the full extension of the diffuser ring. During start-up, transient surge and stall also can be effectively eliminated as gas flow through the diffuser gap can be impeded as load and impeller speed increase, thereby alleviating the problems caused by startup loads at low speeds. The VGD mechanism can be used for capacity control as well so as to achieve more effective turndown at low loads.

The present application discloses a diffuser system and a centrifugal compressor comprising the same. The diffuser system comprises: a passage through which a compressed gas is flowable; and a wall defining the passage, the wall comprising a movable part which is driven to enter the passage so as to change a flow area of the passage, wherein the movable part comprises an elastomer configured to expand to guide the flow of the compressed gas when at least a portion of the movable part enters the passage, and to retract when the movable part withdraws from the passage. The diffuser system involved in the present application re-orients a flow route of the compressed gas in the passage.

A turbocharger includes a compressor equipped with an inlet-adjustment mechanism disposed in the air inlet of the compressor, the inlet-adjustment mechanism including a plurality of arcuate blades distributed about a circumference of a circle and partially overlapping one another so as to form an uninterrupted 360-degree blade ring. Each blade is pivotable about a respective fixed pivot point such that the ring is adjustable between a maximum-open position and a minimum-open position, the ring being adjustable via simultaneous coordinated pivoting of the blades about the respective fixed pivot points. The blades are structured and arranged to form said uninterrupted 360-degree blade ring in the maximum-open position and the minimum-open position and any intermediate position therebetween.

A compression system comprises a compressor, an inlet duct, a throttling valve installed in the inlet duct, an outlet duct, an anti-surge valve fluidly coupling the outlet duct with a portion of the inlet duct downstream of the throttling valve and a recycle valve fluidly coupling the outlet duct with a portion of the inlet duct upstream of the throttling valve. Keeping the recycle valve open, the anti-surge valve closed and the throttling valve partially closed allows lowering the pressure of the flow entering the compressor during its start-up.

A centrifugal compressor includes: an impeller; an inlet pipe portion forming an intake passage to introduce air to the impeller; and a throttle mechanism capable of reducing a flow passage area of the intake passage upstream of the impeller. The throttle mechanism includes an annular portion configured to move between a first position and a second position upstream of the first position in an axial direction of the impeller, and a strut supporting the annular portion. The strut extends toward at least one of an outer side in a radial direction of the impeller or a downstream side in the axial direction of the impeller with an increase in distance from the annular portion.

A gas compressor includes: a compressor main body that compresses gas and discharges the compressed gas; an electric motor that supplies driving force; a power conversion device that supplies predetermined frequency power to the electric motor; at least one of a suction throttle valve disposed on the suction side of the compression main body and an air release valve that releases the compressed gas in a discharge piping system to an atmospheric pressure environment, and a controller. The gas compressor performs unload operation of reducing, when a discharge pressure reaches a predetermined pressure, a load on the compressor main body by closing the suction throttle valve or opening the air release valve. The gas compressor further includes a current value detector that detects a current value inputted to the power conversion device and outputs the current value to the controller.

A centrifugal compressor includes: an impeller; an inlet pipe portion forming an intake passage to introduce air to the impeller; and a throttle mechanism capable of reducing a flow passage area of the intake passage upstream of the impeller. The throttle mechanism includes an annular portion configured to move between a first position and a second position upstream of the first position in an axial direction of the impeller, and a strut supporting the annular portion. The strut extends toward at least one of an outer side in a radial direction of the impeller or a downstream side in the axial direction of the impeller with an increase in distance from the annular portion.

An example centrifugal compressor includes a housing that defines an inlet chamber and includes first and second openings that define a recirculation passage in fluid communication with the inlet chamber. An impeller is disposed within the housing and is rotatable about a longitudinal axis to draw fluid into the inlet chamber. The first and second openings are at different axial locations along the longitudinal axis. A plurality of inlet guide vanes are rotatable and situated in the inlet chamber. The centrifugal compressor includes a ring and a controller for moving the ring along the longitudinal axis between a first position and a second position when rotating the inlet guide vanes. The ring obstructs at least one of the first and second openings more in the second position than in the first position.

A compressor includes a rotation shaft that is capable of rotating around a main axis, an impeller provided integrally with the rotation shaft, a casing that covers the impeller from an outer circumferential side and forms a flow path through which a working fluid circulates, a discharge scroll that is provided at an end of the flow path on a downstream side and extends in a spiral shape around the main axis, a discharge nozzle that communicates with the discharge scroll on the downstream side and extends from the discharge scroll in a tangent direction around the main axis, and a pressure loss body that has a plate shape extending in a direction orthogonal to an axis of the discharge nozzle extending in a radial direction orthogonal to the main axis and is capable of blocking a part of a flow path cross-section of the discharge nozzle.

Method for controlling a compressor comprising a last stage (40) and a compressor load controller (90), a set point outlet pressure corresponding to the consumer needed pressure, being given in the load controller (90) comprising the steps of: a—measuring the temperature at the inlet of the last stage (40), b—measuring the ratio between the outlet and inlet pressure of the last stage (40), c—computing a coefficient (Ψ) based on the value of the inlet temperature (Tin) and on the pressure ratio (Pout/Pin), d—if the coefficient (Ψ) is in a predetermined range, changing the set point outlet pressure by a new greater set point outlet pressure until the coefficient (Ψ) computed with the new set point outlet pressure goes out of the predetermined range, and e—adapting the pressure of the fluid coming out of the compressor in a pressure regulator (100) to the consumer needed pressure.