Method for separating air by cryogenic distillation, wherein air is compressed in a compressor and is subsequently sent to a heat exchanger, with the air cooled in the exchanger being sent to a check valve downstream of the heat exchanger and subsequently to a turbine, the valve being positioned so that air from a short-circuiting duct cannot return to the exchanger from the compressor.

Methods and systems for recovering alkenes (e.g. ethylene, propylene) and nitrogen from process gas streams, including multi-step condensing of the process gas stream, are provided herein.

In a method for separating a synthesis gas containing carbon monoxide and hydrogen, a synthesis gas flow from a synthesis gas source is compressed in a compressor and separated into at least three gaseous products. If there is insufficient synthesis gas, at least three separation products are recycled in the compressor in order to separate said products.

The invention relates to a control system which comprises: a plurality of flow valves on channels of reaction fluid, which are i) in a closed position or ii) in an open position; a plurality of control pipes connected to a source of control fluid and to a respective control pipe, all or part of the flow valves switching to the closed position when the pressure of the control fluid in the control pipe drops below a predetermined threshold; a discharge pipe connected to the control pipes, in order to discharge the control fluid from the control pipes; a safety device connected i) to each control pipe and ii) to the discharge pipe and configured to have, selectively: i) a service configuration, wherein the control fluid flows to each control pipe, thus opening each flow valve, and ii) a safety configuration, wherein the control fluid is discharged through the discharge pipe, thus closing each flow valve.

A compressor system is described, comprising: at least a first compressor having a suction side) and a delivery side); an anti-surge line; an anti-surge valve arranged along the anti-surge line and controlled for recirculating a gas flow from the delivery side back to the suction side of the compressor; a heat removal arrangement between the anti-surge valve and the suction side of the compressor.

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.

In a method for cooling a flow containing at least 35% carbon dioxide and at least 0.2 ?g/Nm.sup.3 of mercury, the mercury being in liquid and/or gas form, the flow is cooled in a first brazed aluminum plate-fin heat exchanger from a first temperature to a second temperature higher than ?38.6? C. to form a cold flow at the second temperature, and the flow cooled to the second temperature is cooled in a second heat exchanger, which is a tube and shell heat exchanger, to a third temperature lower than ?38.6? C.

A system and method for supplying a backup product in an air separation device, as well as a system and method for supplying a lower-pressure product to a user by means of pressurization of a cryogenic liquid pump during normal operation of an air separation device, i.e., when the cryogenic liquid pump is in the cold standby state. By means of the system and method, a cryogenic liquid product taken from a storage tank is pressurized by the cryogenic liquid pump to produce a lower-pressure product by taking full advantage of the low-speed operation of the cryogenic liquid pump in the cold standby state, and the lower-pressure product is transmitted to product supply lines of a user, to achieve the function of supplying the lower-pressure product to the user. The system and method not only reduce the energy loss of the cryogenic liquid pump in the cold standby state for a long time, but also avoid the bleeding rate of the cryogenic liquid product generated by sending a part of the cryogenic liquid product back to the storage tank, so that the advantage of quickly starting the cryogenic liquid pump from the cold standby state is ensured, and the requirements of the user to the higher-pressure product and the lower-pressure product can be satisfied.

An apparatus for separation of air by cryogenic distillation comprising: a system of columns; a first turbine; a warm compressor coupled to the first turbine; a second turbine; a cold compressor coupled to the second turbine; a heat exchanger; means for sending air cooled in the heat exchanger at an intermediate temperature of the heat exchanger to the cold compressor; means for sending expanded air from the second turbine to the system of columns; means for sending air compressed in the cold compressor to an intermediate point of the heat exchanger and then at least in part to the system of columns via a first valve; means for sending air compressed in the cold compressor to the inlet of the first turbine via a second valve without passing through the heat exchanger, wherein the means for sending air compressed in the cold compressor to the inlet of the first turbine via the second valve without passing through the heat exchanger is also connected to the inlet of the first turbine; means for sending a fraction of air cooled in the heat exchanger to an intermediate temperature of the latter to the first turbine; means for sending expanded air from the first turbine to the system of columns; and a bypass line provided with an expansion valve configured to send air from the cold compressor to the system of columns without passing through the heat exchanger.

The invention relates to a method for cooling and/or liquefying a user fluid flow, the method using a cooling and/or liquefying system comprising a low-temperature refrigeration device, the refrigeration device comprising a working circuit forming a loop and containing a working fluid, the refrigeration device comprising a cooling exchanger intended to extract heat from the user fluid flow by heat exchange with the working fluid circulating in the working circuit, the working circuit forming a cycle comprising, in a series: a compression mechanism a cooling mechanism, an expansion mechanism, and a reheating mechanism, the system comprising a pipe for circulation of the user fluid flow to be cooled in heat exchange with the cooling exchanger of the refrigeration device, the method comprising a step of cooling a user fluid flow in the cooling exchanger and after this cooling step, a step of cleaning impurities solidified in the cooling exchanger, the cleaning step comprising stopping of the refrigeration device and simultaneously, circulation of a user fluid flow in the cooling exchanger.