METHOD FOR AUTOMATIC CONTROL OF LOW-TEMPERATURE GAS SEPARATION UNIT WITH AIR COOLING APPARATUS 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 air coolers (AC) in the North of the Russian Federation includes preliminary purification of the produced gas condensate mixture from mechanical impurities and separation of a mixture of unstable gas condensate (UGC) and an aqueous solution of inhibitor (ASI) in the first stage separator separation, after which the mixture of UGC and ASI from the cubic part of the separator is diverted to the liquid separator (LS), and the gas condensate mixture from the outlet of the separator of the first separation stage is fed to the inlet of the air cooler, which is put into operation by the automatic process control system (APCS) when the specified value is reached. temperature difference between the gas condensate mixture and atmospheric air, by sending a corresponding signal to the input of the automatic control system (ACS) of the air cooler, which controls the operation of the air cooler, ensuring that the temperature of the gas condensate mixture at its outlet is lowered to the set values necessary to maintain the required temperature in the low-temperature separator, after which the gas-condensate mixture pre-cooled in the air cooler is divided into two streams, the first of which is sent to the pipe space of the first section of the recuperative heat exchanger (HE) "gas-gas", where it is cooled by a counter-flow of dried gas coming from the low-temperature separator and passing through the second section of the HE "gas-gas", and the second flow through the valve-regulator (VR) is fed into the pipe space of the first section of the HE "gas-condensate", where it is cooled by a counter-flow of a mixture of UGC and ASI discharged from the bottom part of the low-temperature separator and passing through the second section of the HE "gas-condensate". The flow rate of the gas condensate mixture for these flows is distributed by the automated process control system using the VR installed at the inlet of the first section of the gas-condensate HE, so that the temperature of the oil and gas complex entering the main condensate pipeline (MCP) is within the range specified by the technological regulations, and after the gas condensate mixture from the first sections of HE "gas-gas" and HE "gas-condensate", its flows are combined and fed through the VR, which acts as a controlled reducer, on which the adiabatic expansion of the gas condensate mixture is carried out and sent to a low-temperature separator equipped with a temperature sensor, in which final separation of the gas condensate mixture into dried cold gas and a mixture of UGC with ASI, which is fed from the bottom part of the low-temperature separator to the inlet of the second section of the gas-condensate HE and further into the LS, in which UGC, ASI and weathering gas are separated, after which UGC with using a pumping unit, they are fed into the MCP, ASI is sent to the inhibitor regeneration shop gas, and weathering gas - for utilization or injection into the main gas pipeline (MGP). 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-gas HE, and the second to the bypass of this section, equipped with a gas flow control valve, with the help of which the process control system regulates the ratio of flows dried gas passing through the second section of the gas-to-gas HE and bypass, providing real-time correction of the temperature of the dried gas to the set values required by the technological regulations of the installation when gas is supplied to the MGP. APCS in tandem with ACS AC from the moment the unit is put into operation, maintain the flow rate of the produced gas condensate mixture for the unit and implement the oil and gas production plan using the initially set values of the settings of controlled parameters, which are entered into the database (DB) of the APCS before the unit is put into operation. As soon as the automated process control system detects that one of the controlled parameters goes beyond the established limits, violating the technological operation schedule of the unit, the automated process control system step by step changes the setting value of the flow rate plan for the produced gas condensate mixture Q_{GCM_PLAN} according to the installation by the value ΔQ_{GCM_PLAN} in the interval determined by the inequality Q_{min_GCM} ≤ Q_{GCM_PLAN} ≤Q_{max_GCM}, where Q_{min_GCM} is the minimum allowable, and Q_{max_GCM} is the maximum allowable value of the flow rate of the produced gas condensate mixture through the unit, and in the direction that ensures the relief of the identified violation of the unit operation regulations. The step size ΔQ_{GCM_PLAN} is assigned from the ratio where n is the number of allowable steps for changing the Q_{GCM_PLAN} setpoint. After each step, the APCS maintains the process control mode 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 all controlled parameters of the technological process during this time are within the limits set by it, the APCS fixes this value of the new setpoint of the flow rate of the produced gas condensate mixture as a working one and generates a message to the operator about the automatic change of the operating mode and its new characteristics, and then the APCS in tandem with ACS AC implement the newly selected mode of operation 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.

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