METHOD FOR AUTOMATIC CONTROL OF A LOW-TEMPERATURE GAS SEPARATION UNIT WITH TURBO-EXPANDER UNITS IN THE EXTREME NORTH OF THE RUSSIAN FEDERATION 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 with turbo-expander units (TEU) in the Far North of the Russian Federation includes preliminary purification of the produced gas condensate mixture from mechanical impurities with partial separation of a mixture of unstable gas condensate (UGC) and an aqueous solution of an inhibitor (ASI) in the separator of the first separation stage, which is discharged from the bottom part of the separator to the liquid separator (LS), and the gas condensate mixture leaving the separator of the first separation stage is divided into two streams and fed for pre-cooling to the inlet of the first sections of the recuperative heat exchangers (HE) "gas-gas" and "gas -condensate". The gas condensate mixture is distributed among the streams using a control valve (CV) installed at the inlet of the gas-condensate HE so as to maintain the specified temperature of the UGC supplied to the main condensate pipeline. After passing the first sections of HE, both flows of the gas condensate mixture are combined and fed to the inlet of the TEU turbine, the rotation of which is controlled by the TEU rotor speed sensor. The gas condensate mixture, passing through the turbine, is cooled and enters a low-temperature separator equipped with a temperature sensor, in which it is separated into dried cold gas and a mixture of UGC and ASI, which is fed from the bottom part of the low-temperature separator to the inlet of the second section of the HE "gas-condensate" and further into the LS, where it is degassed and separated into fractions, and then from the LS of the UGC is pumped to the MCP, the weathering gas is sent for utilization and/or compressed and sent to the MGP, ASI is sent to the inhibitor regeneration shop. The cold dried 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-to-gas HE, and the second to the bypass of this section, equipped with a gas flow CV, and this CV changes the ratio of gas flows through the HE and bypass, providing real-time correction of the temperature of the gas entering the TEU compressor, which pressurizes the gas to the operating pressure and the set temperature, after which it is fed to the MGP. From the moment the unit is put into operation, the automated process control system ensures the fulfillment of the plan for supplying dry gas to the MGP, using for this the set values ​​of the settings of the controlled parameters and the limits of permissible deviations of their values ​​from the settings. As soon as the automated process control system detects that one of the controlled parameters goes beyond the limits set for it, violating the technological regulations for the operation of the installation, the automated process control system changes the value of the pressure set point P_in by one step. produced gas condensate mixture at the inlet of the installation by the value ΔP_in in the interval determined by the inequality P_min≤P_in≤P_max, where P_min is the minimum allowable and P_max is the maximum allowable value of the gas condensate mixture pressure setpoint at the unit inlet. The value of ΔP_in are assigned from the ratio ΔP_in=(P_max-P_min)/n, where n is the number of allowed steps for changing the P_in setting, and this change in the setting of the APCS is carried out in the direction that allows to eliminate the violation that has occurred. At the same time, the automated process control system monitors that the working body of the CR, which controls the pressure at the inlet of the installation, is within the allowable limits of its movement, and keeps the control mode of the technological processes of the installation with a new setpoint value for a time interval of at least τ_const, which is an individual characteristic of the installation determined experimentally. If the other controlled parameters of the technological process during this time return within the limits set for them, then the process control system fixes this value in its database (DB) as a new pressure setting for the produced gas condensate mixture at the inlet to the installation to implement the plan for the flow rate of dried gas supplied in MGP, and generates a message to the operator about the automatic change of the operating mode of the installation and its new characteristics, and then the automated process control system implements this 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 installation and the efficiency of the process of preparing gas and gas condensate for long-distance transport.

3 cl, 2 dwg