METHOD FOR AUTOMATIC CONTROL OF A LOW-TEMPERATURE GAS SEPARATION UNIT WITH AIR COOLING APPARATUS 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 air coolers (AC) in the Far North of the Russian Federation includes preliminary purification of the produced gas condensate mixture from mechanical impurities and partial separation of a mixture of unstable gas condensate (UGC) and an aqueous inhibitor solution (ASI) in the separator of the first separation stage, 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 temperature difference is reached gas condensate mixture and atmospheric air, by applying an appropriate signal to the input of the automatic control system (ACS) of the air cooler, which controls the work of the air cooler, ensuring that the temperature of the gas condensate mixture at its outlet decreases 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 with the help of the VR installed at the inlet of the first section of the gas-condensate HE, so that the temperature of the UGC supplied to the main condensate pipeline (MCP) is within the range specified by the technological regulations. After the exit of 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 the final separation of the gas condensate mixture into dry cold gas and a mixture of UGC with ASI is carried out, 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 then into the LS, in which UGC, ASI and weathering gas are separated, after whereupon the UGC is fed to the MCP with the help of a pumping unit, the ASI is sent to the installation inhibitor regeneration shop, the weathering gas is sent 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, they supply the volume of dried gas specified by the plan to the MGP, for which they use the initially set values ​​of the settings of the controlled parameters and the limits of their permissible deviations from the values ​​of the settings. As soon as the automated process control system detects that one of the controlled parameters goes beyond the established limits, which violates the technological regulations for the operation of the installation, the automated process control system changes the value of the pressure setpoint P_in by one step 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 pressure of the gas condensate mixture 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. At the same time, the automated process control system monitors that the working body of the VR, 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 other controlled parameters of the technological process during this time return within the limits set for them, then the automated process control system fixes this value as a new setting for the implementation of the plan for the flow of dried gas supplied to the MGP and generates a message to the operator about the automatic change of the operating mode of the installation and its new characteristics, and further automated process control systems in tandem with ACS AC implement 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