METHOD FOR AUTOMATIC CONTROL OF LOW-TEMPERATURE GAS SEPARATION UNIT WITH TURBO-EXPANDER UNITS IN THE NORTH OF RF Russian patent published in 2022 - IPC E21B43/34 F17D3/01 F25J3/08 

FIELD: gas industry.

SUBSTANCE: invention relates to the field of production and preparation of gas and gas condensate for long-distance transport. A method for automatic control of a low-temperature gas separation unit (hereinafter referred to as the unit) with turbo-expander units (TEU) includes preliminary purification of the produced gas condensate mixture from mechanical impurities and partial separation of the mixture of unstable gas condensate (UGC) with an aqueous inhibitor solution (AIS) in the separator of the first separation stage with subsequent removal of this mixture from the cubic part of the separator to the liquid separator (LS). The gas-liquid mixture leaving the separator is divided into two streams and supplied for pre-cooling to the inlet of the first sections of the recuperative heat exchangers (HE) "gas-gas" and "gas-condensate", distributing this mixture among the streams using a control valve (CV) , which is installed at the inlet of the first section of the HE "gas-condensate", and these gas-liquid mixture flows from the outlets of the first sections of these HE are combined and fed to the inlet of the TEU turbine, equipped with a rotor speed sensor, passing through which the gas-liquid mixture expands adiabatically, and its temperature decreases to values ​​close to those stipulated by the technological regulations of the plant, and this cooled gas-liquid mixture is fed into a low-temperature gas separator equipped with a temperature sensor, in which it is finally separated into dried cold gas and a mixture of oil and gas with AIS, which is removed from the low-temperature separator of the second separation stage through the second section HE "gas-condensate" in the CV for degassing and separation into fraction, and the cold dry gas leaving the low-temperature separator is divided into two streams, one of which is fed to the inlet of the second section of the gas-gas HE, and the second to the bypass of this section, equipped with a gas flow control valve, which changes the ratio of the cooled gas streams through the second section of the HE "gas-gas". Further, these gas flows leaving the second section of the gas-gas TO and bypass are combined and fed into the TDA compressor, which compresses the gas to the working pressure, and is sent to the main gas pipeline (MGP), from the UGC UGC it is sent to the main condensate pipeline (MCP), AIS - to the inhibitor regeneration shop, and weathering gas - for disposal or injection into the MGP. From the moment the unit is put into operation, the automated process control system (APCS) implements the operating mode of the unit using the initially set values ​​of the settings of the controlled parameters, and also monitors that the current value of the V_set_TEU setpoint for the TDA rotor rotation speed does not go beyond the upper or the lower limit of permissible rotational speeds. As soon as the automated process control system detects the output of one of the controlled parameters beyond the established limits, violating the technological schedule of the installation, the automated process control system step by step changes the setting value of the flow rate plan for the produced gas condensate mixture Q_{MCP_PLAN} according to the installation by the value ΔQ_{MCP_PLAN} in the interval determined by the inequality carries out in the direction that determines the violation. After each step, the APCS maintains the process control mode of the installation with a new setpoint value Q_{MCP_PLAN} for a certain time interval, and if the values ​​of the other above-mentioned controlled parameters of the technological processes during this time are within the limits set for them, then the APCS fixes this value of the new setpoint Q_{MCP_PLAN} of the flow plan for the produced gas condensate mixture as a working one in its database (DB) and generates a message to the operator about the automatic transition to a new operating mode and displays its characteristics, after which the automated process control system implements the newly selected operating mode of the installation. Otherwise, the APCS changes the setpoint value by one more step in the same direction.

EFFECT: increasing the reliability of operation of the plant and the efficiency of the process of preparing gas and gas condensate for long-distance transport.

3 cl, 2 dwg