METHOD FOR AUTOMATICALLY MAINTAINING THE DENSITY OF UNSTABLE GAS CONDENSATE AT THE OUTPUT OF LOW-TEMPERATURE GAS SEPARATION UNITS OF THE NORTHERN PETROLEUM AND GAS CONDENSATE FIELDS 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 in the Far North, in particular, to automatic maintenance of the density of unstable gas condensate (UGC) supplied to the main condensate pipeline (MCP) at a low-temperature gas separation unit (hereinafter the unit). In the method, the supplied gas condensate mixture is purified from mechanical impurities, separated into dried gas and a mixture of UGC with an aqueous inhibitor solution (AIS), the dried gas is directed to the main gas pipeline (MGP) and the mixture is directed to the degassing separator (DS), wherefrom the AIS is removed for regeneration of the inhibitor, UGC is pumped into the MCP, and the flash gas, through the adjustment valve (AV) for adjusting the pressure in the DS, is directed to the flash gas compressor to be injected into the MGP, and the automated process control system (APCS) of the unit overlooking the above processes controls the density ρ_act of UGC supplied to the MCP by a density sensor and the flash gas pressure P_act in the DS by a pressure sensor. The pressure in the DS is adjusted by the AV installed at the output thereof and controlled by a stage of proportional integral derivative controls (PID controls). The APCS transmits a signal of the UGC density setpoint ρ_set the to the setpoint input SP of the first PID control, and the feedback input PV of the same PID control receives a signal of the actual density value ρ_act from the UGC density sensor, comparing which, said control generates a signal of the pressure setpoint P_set, allowing for the required UGC density at the output of the DS, at the output CV and transmits said setpoint to the setpoint input SP of the second PID control of the pressure maintenance stage in the DS, and the feedback input PV of the same PID control receives a signal of the actual pressure value P_act from the pressure sensor installed in the DS, comparing which, said PID control, at the output CV, forms a control signal for the AV standing at the output of the DS, maintaining the required pressure of gas therein. The density of the UGC supplied to the MCP is automatically maintained by two stages of PID controls controlled by the APCS, the first whereof maintains the set UGC density ρ_set after the unit is put to operation, adjusting the pressure of gas in the DS using the AV installed at the output thereof, and the second stage goes into operation at the command of the APCS after the first stage of PID controls exhausts all capabilities for controlling the density of the UGC supplied to the MCP, and the APCS sends this command to the Start\Stop input of the second PID control of the second stage of the system, followed by this PID control transmitting a control signal from the CV output to the AV, adjusting the flow rate of the produced gas condensate mixture for the unit, and starts changing the degree of opening/closing thereof until certain conditions are satisfied. Only then the APCS stops controlling the flow rate of the produced gas condensate mixture by the second stage of the system, and controls the density of the UGC supplied to the MCP again using the first stage of PID controls.

EFFECT: increased quality of controlling a technological process.

6 cl, 2 dwg