A stable discharge pressure of compressed hydrogen gas generated from the electrolysis of water is achieved and maintained at the outlet of a “hybrid” multistage compression system comprising at least a first section comprising at least one centrifugal compressor powered at least in part by electricity generated from at least one renewable energy source and a further section downstream of the first section, wherein the further section comprises at least one reciprocating compressor.

Operation of a multistage compression system comprising at least one centrifugal compressor having a dry gas seal with opposed seal faces, for compressing a gas feed having a variable flow rate is improved by operating the or at least one centrifugal compressor in a low power mode where the opposed faces of the dry gas seal are not in contact during periods when gas flow through the centrifugal compressor(s) is not sufficient for normal operation. Such operation not only reduces damage to the dry gas seals and hence improves reliability, but also reduces the overall power requirement of the overall compression system.

Energy efficiency and/or operational stability of a multistage compression system comprising a plurality (N) of centrifugal compressors that is compressing a gas feed having a variable flow rate is improved by adjusting reversibly the load on each compressor in response to changes in the flow rate of the gas feed using a main recycle system to enable operation of the centrifugal compressors at turndown capacity during periods when the flow rate is below total turndown capacity for all of the compressors, and if necessary, using the local recycle systems in order to avoid activation of anti-surge control, and switching one or more centrifugal compressors into low power mode or shutdown mode as required.

A gas compressor includes inverters, a plurality of compressor units and a control device for controlling each of the inverters. The control device increases the number of compressor bodies to be operated after confirming that the rotational speed of the operational motors will reach a steady value immediately after causing the number of the compressor bodies to be operated to increase.

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 method for evacuating a process space by initially evacuating the process space to a pressure limit value using two compressors operated in parallel, and on reaching or undershooting the pressure limit value, the process space is subsequently evacuated using the two compressors operated in series.

A gas compressing system including a plurality of n compressors connected in parallel. Each compressor has a suction line connected to a common suction manifold and a discharge line connected to a common discharge manifold configured to deliver compressed gas to a downstream load. The system also includes a process controller configured to control an average speed of the compressors based upon a discharge pressure in the common discharge manifold or a discharge flow through the common discharge manifold. The system further includes an adaptive load sharing optimizing controller configured to determine the speed of each compressor in the plurality of n compressors. A method of controlling a gas compressing system is also provided.

Centrifugal compressors can incorporate a side stream flow of intermediate pressure vapor between stages of that compressor. The side stream flow can be controlled by a side stream injection port controlled by a capacity control valve that has a curved surface facing a flow of refrigerant from the first stage to the second stage. The capacity control valve can allow or obstruct flow through the side stream injection port. The capacity control valve can extend and retract in a direction substantially perpendicular to the direction of flow from the first stage impeller to the second stage impeller. The side stream injection port and the capacity control valve can be ring-shaped. The side stream injection port and the capacity control valve can allow at least some of the side stream to be introduced on a side of the capacity control valve opposite the curved surface.

Method to operate a vacuum system comprising at least a first vacuum pump and a second vacuum pump wherein the first vacuum pump and the second vacuum pump are connectable to a vacuum chamber to maintain a set pressure inside the vacuum chamber. The first vacuum pump is a Variable Speed Drive pump wherein the first vacuum pump and the second vacuum pump are connected in series. The method comprises the steps of controlling the performance of the first vacuum pump and the performance of the first vacuum pump is controlled to be equal to or higher than the performance of the second vacuum pump while maintaining the set pressure in the vacuum chamber.

The invention relates to a method of installing a subsea system (1) comprising the steps of: —installing at least one first foundation structure (13′) on a seabed, wherein the first foundation structure (13′) comprises a connection interface (50′) connectable to a second foundation structure (13″), —installing a first compressor train on the foundation structure (13′), the first compressor train comprising at least a first compressor (8′), —connecting the first compressor train to at least one well flow line (2), —connecting a first compressed fluid line (9′) to an outlet (15′) of the first compressor (8′) and to a common outlet (16) for the compressed fluid in the subsea system (1), wherein the first compressed fluid line (9′) comprises a flow regulating device (24′), —connecting a first connection line (10′,12′) to the first compressed fluid line (9′) at a position upstream of the flow regulating device (24′) and/or to a line (2, 6′) at a position upstream of the first compressor (8), and wherein the first connection line (10′, 12′) is connectable to an additional compressor train positioned on the second foundation structure (13″), the first connection line (10′) comprising a flow regulation device (20′,22′), —connecting a second connection line (11′) to the first compressed fluid line (9′) at a position downstream of the flow regulation device (24′) and wherein the second connection line (11′) is connectable to the additional compressor train positioned on the second foundation structure (13″), the second connection line (11′) comprising a flow regulation device (21′). It is further described an associated a subsea system.