Patent RU-2709045-C1 (RU)
Title: Method of automatic control of capacity of low-temperature gas separation unit
Inventor: ARABSKIJ ANATOLIJ KUZMICH
IPC: B01D53/26
Filed: 2019-01-09
Granted: 2019-12-13
Abstract: FIELD: oil and gas industry. 
     SUBSTANCE: invention relates to production, collection and preparation of natural gas and gas condensate for transportation, in particular, to automatic control of capacity of low-temperature gas separation units. Method for automatic control of capacity of installation of low-temperature gas separation includes control of means of automated process control system (APCS) of installation of low-temperature separation of gas flow of dried gas, supplied to main gas line (MGL), consumption of unstable gas condensate (UGC) supplied to main condensate line (MCL), level of UGC in buffer tank, gas pressure in MGL and condensate pressure in MCL. Assignment of a gas producer operator to the UGC production level is transmitted to a database (DB APCS), which executes it using a PID controller for maintaining flow rate UGC in the MCL, implemented on the basis of APCS, to the SP setting input of which the APCS supplies the dispatcher setting signal, and to its feedback input PV sends a signal of current flow rate UGC to MCL, comparing which this PID-controller generates at its output CV control signal setting capacity of pump unit, which provides a given volume of supply UGC from buffer capacity in MCL. Simultaneously, the APCS monitors the level of UGC in the buffer tank, which holds within the predetermined limits with the help of the PID-control of maintaining the production level of the UGC of the plant, the SP input of which sends the signal of the current flow rate UGC to the MCL, and to the PV input of the same PID-controller supplies a signal of current flow rate UGC coming from the low-temperature gas separation unit to the buffer tank, by comparing which said PID-controller generates at its output CV a control signal supplied to the control valve, controlling flow rate of produced gas-condensate mixture supplied to low-temperature gas separation unit. PID controller for maintaining production level UGC operates in dynamic mode determined by value of proportionality coefficient K p , supplied to input of same PID-controller and continuously calculated in real time by the unit for rapid calculation of the proportionality coefficient depending on the value of the process settings and the current readings of the UGC level sensor in the buffer tank controlled by the APCS. Unit for rapid calculation of the proportionality coefficient realizes its calculations based on a certain mathematical relationship. 
     EFFECT: technical result consists in automatic maintenance of specified value of production level of UGC and its required margin in buffer capacity; real-time monitoring of pressure and flow rate values of gas and UGC supplied to main gas line MGL and main condensate line MCL, respectively; maintenance of stable operation mode of the plant during transient processes, providing transportation of UGC by MCL in single-phase state, exclusion of "swinging" of operating mode of installation and appearance of gas plugs and their accumulations in condensate line. 
     6 cl, 2 dwg