Patent RU-2743726-C1 (RU)
Title: Method for optimizing the process of washing the inhibitor from unstable gas condensate at low-temperature gas separation plants of oil-and-gas condensate fields in the north of the russian federation
Inventor: ARNO OLEG BORISOVICH
IPC: F17D3/16
Filed: 2020-07-14
Granted: 2021-02-25
Abstract: FIELD: oil and gas.  
     SUBSTANCE: invention relates to the field of preparation of natural gas and gas condensate for long-distance transport, in particular to the automatic control of the washing out of the inhibitor - methanol from unstable gas condensate (UGC) at low-temperature gas separation (LTS) installations (hereinafter referred to as the unit) located in the regions of the North of the Russian Federation. The method includes automatic maintenance by an automated process control system (APCS), within specified boundaries, of technological parameters of the process of preparing gas and gas condensate for long-distance transport. For this, the APCS searches for the optimal flow rate of a low-concentration water-methanol solution (WMS), which will be supplied to the injection input of the injector when the unit is started up, periodically, or when the operating mode of the unit is changed, as well as at the request of the operator for the current parameters of the technological process. The search process is carried out taking into account its inertia of technological processes in the unit. At the end of the search, the APCS records the found value of the optimal low-concentration WMS flow rate as a setpoint in its database until the next search cycle. After fixing the value of the set point, the APCS maintains the supply of the found optimal low concentration WMS flow rate in the mode of proportional-integral-derivative (PID) control. This flow of the low concentration WMS is fed through an injector into a combined gas-liquid mixture stream entering the second stage liquid separator (LS) from the intermediate and low temperature gas separators. The automated process control system monitors the concentration of methanol in WMS discharged from the LS of the second separation stage for regeneration, and its consumption. At the same time, the automated process control system controls the flow rate of the UGC supplied from the LS of the second separation stage to the main condensate pipeline. And as soon as it detects a deviation of the current value of the WTS flow rate, or the concentration of methanol in it, or a change in the flow rate of the UGC from the set values, taking into account the set boundaries of deviation from the optimal flow rate of low concentration WTS recorded in the APCS database for this cycle, it immediately switches to mode for determining its new value.  
     EFFECT: automatic maintenance of the maximum possible flushing of methanol from the UGC in the real mode of operation of the unit with minimal energy consumption for maintaining the technological process of methanol regeneration within the framework of technological norms and restrictions imposed by the technological regulations of the unit, a significant increase in the quality of the UGC supplied to the main condensate pipeline. 
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