A centrifugal compressor and a method of operating a centrifugal compressor. The centrifugal compressor includes: an impeller configured to suction a gas to be compressed; a diffuser disposed downstream of the impeller to pressurize the gas, the diffuser comprising a movable ring, a main passage in which the gas flows past the ring, and an openable branch passage; and a circulation loop comprising an inlet and an outlet, the outlet being in communication with an inlet of the impeller; the branch passage is disposed to be in communication with the main passage and the circulation loop when the ring moves into the main passage so that a portion of the gas in the main passage passes through the circulation loop and returns to the impeller so as to be suctioned, and to be closed when the ring is withdrawn from the main passage.

A casing treatment for a compressor includes one or more cavities in a casing disposed radially outwardly of tips of the compressor rotor blades. A liner is moveable relative to the casing between a first position and a second position. The liner is shaped to add a volume to the tip clearance gap when moving from the second position toward the first position. The liner is displaceable between the first and second positions in coordination with at least the rotation of inlet guide vanes (IGVs) between IGV positions.

A method for handling the shutdown of a turbomachine string installed in a plant for the liquefaction of a gaseous product comprising at least two turbomachine strings comprises the steps of detecting the shutdown of a first turbomachine string; promptly increasing the driving torque on a shaft of a second turbomachine string when the shutdown is detected; maintaining the driving torque increase on the shaft of the second turbomachine string until a preset speed of the motor driver is reached or a predetermined period of time expires.

A system of interlocks for controlling flow of low temperature process streams in a manufacturing process through a cold box to equipment or piping not specified for such temperatures by opening and closing valves and starting and stopping pumps. At least one interlock affects streams heated in the cold box. At least one interlock affects the streams cooled in the cold box. The interlocks are activated by temperatures of process lines to prevent exposure of equipment and piping to low temperatures while preventing the shutdown of the cold box. An override controller including a predictive failure capability is also provided.

An antisurge controller for a turbocompressor system stores multiple control algorithms in a memory for the antisurge controller. The antisurge controller identifies capabilities of field devices in the turbocompressor system. The field devices include an antisurge valve and multiple sensors. The antisurge controller selects one of the multiple control algorithms based on the identified capabilities and applies the selected control algorithm to the turbocompressor system. The selected control algorithm provides the smallest surge control margin, of the surge control margins in the multiple control algorithms, that are supported by the identified capabilities.

An air pump is provided, the air pump comprising: an air pump housing; a first check valve; a main air pump; an airway switching device; an air-supplementing pump; an air pressure sensor; and a control device. The control device is electrically connected to the main air pump, the airway switching device, the air-supplementing pump, and the air pressure sensor, and is configured to: send a main air pump stop signal based on the air pressure sensor detecting a threshold pressure in the inflatable body during operation of the main air pump; and send an air-supplementing pump operation signal based on the air pressure sensor detecting a pressure lower than the threshold pressure in the inflatable body when the main air pump is not in operation.

A system of interlocks for controlling flow of low temperature process streams in a manufacturing process through a cold box to equipment or piping not specified for such temperatures by opening and closing valves and starting and stopping pumps. At least one interlock affects streams heated in the cold box. At least one interlock affects the streams cooled in the cold box. The interlocks are activated by temperatures of process lines to prevent exposure of equipment and piping to low temperatures while preventing the shutdown of the cold box. An override controller including a predictive failure capability is also provided.

A centrifugal compressor for a chiller system includes a casing having an inlet portion and an outlet portion, a recirculation structure including a recirculation path and a recirculation discharge cavity, an impeller disposed downstream of the recirculation discharge cavity, a plurality of recirculation discharge guide vanes disposed to surround the recirculation discharge cavity, and a diffuser disposed in the outlet portion downstream of the impeller. The recirculation structure is configured to impart a swirl to a flow of refrigerant into the inlet portion. The recirculation path supplies the refrigerant from the diffuser to the recirculation discharge cavity. The recirculation path includes a recirculation pipe that introduces the refrigerant toward the plurality of recirculation discharge guide vanes. An annular groove is disposed between the recirculation pipe and the plurality of recirculation discharge guide vanes. An annular plate is disposed between the annular groove and the recirculation discharge cavity.

The present disclosure is directed to turbine engines and systems for active stability control of rotating compression systems utilizing an electric machine operatively coupled thereto. In one exemplary aspect, an electric machine operatively coupled with a compression system, e.g., via a shaft system, is controlled to provide shaft damping for instability fluctuations of the pressurized fluid stream within the compression system. Based on control data indicative of a system state of the compression system, a control parameter of the electric machine is adjusted to control or change an output of the shaft system. Adjusting the shaft system output by adjusting one or more control parameters of the electric machine allows the compression system to dampen instability fluctuations of the fluid stream within the compression system. A method for active stability control of a compression system operatively coupled with an electric machine via a shaft system is also provided.

An inline valve includes a sliding piston having a radially outer stop portion with a forward end. A radially inner sliding portion is connected to the radially outer stop portion by an arm. A housing includes an outer housing body surrounding the piston. The housing has a stop surface selectively in contact with the forward end of the radially outer stop portion of the piston to block flow for a housing inlet to a housing outlet. The radially inner sliding portion slides on a support tube. At least a portion of the radially inner sliding portion is formed of a first material having better wear resistance than a second material forming the outer stop portion of the piston. The second material has a greater resistance to high temperature and pressure than the first material. A vent valve for a compressor is also disclosed.