RU2783035C1 - Method for automatic control of low-temperature gas separation unit with air cooling apparatus in the north of rf - Google Patents

Abstract

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.

3 cl, 2 dwg

Description

The invention relates to the field of production and preparation of gas and gas condensate for long-distance transport, in particular to automatic maintenance of the temperature regime of technological processes of a low-temperature gas separation unit (hereinafter referred to as the unit), using air coolers (AVO), operating in the conditions of the North of the Russian Federation.

A known method of automating the installation of low-temperature gas separation [see, for example, page 406, R.Ya. Isakovich, V.I. Loginov, V.E. Popadko. Automation of production processes in the oil and gas industry. Textbook for universities, M., Nedra, 1983, 424 pp.], which maintains the separation temperature at the installation using a control valve (KR), which changes the flow of cold gas discharged from the low-temperature separator through a heat exchanger.

The disadvantage of this method is that maintaining the temperature regime at the installation is controlled by the amount of gas passing through the heat exchanger, which causes fluctuations in the temperature of the gas supplied to the main gas pipeline (MGP). Accordingly, there is no control and maintenance of the required temperature of dried gas and unstable gas condensate (OGC) supplied to the MGP and the main condensate pipeline (MCP) in order to protect permafrost soils from thawing during underground pipelines in the North of the Russian Federation [see. for example, pp. 33-34, Ananenkov A.G., Stavkin G.P., Andreev O.P., Arabsky A.K., Salikhov Z.S., Talybov E.G. Automatic process control system for gas production facilities. - M.: Nedra-Businesscenter LLC, 2003. - 343 p.: ill.; page 19; Dmitriev V.M., Ganja T.V. and others. Intellectualization of control of technological processes in hydrocarbon deposits. Tomsk: V-Spectrum, 2012. - 212 p.].

A known method of automating the installation of low-temperature gas separation [see, for example, p. 112, B.F. Taranenko, V.T. Hermann. Automatic control of gas production facilities. M., "Nedra", 1976, 213 pp.], which automatically maintains the set value of the separation temperature at the plant by maintaining the necessary pressure drop at the regulator fitting installed at the inlet to the low-temperature separator, by correcting the pressure at the outlet of the first installation reduction steps.

The disadvantage of this method is that the maintenance of the temperature regime at the plant is carried out by regulating the pressure drop across the reducing valve installed at the inlet to the low-temperature separator of the plant. This, in turn, imposes restrictions on the inlet pressure and gas flow through the installation. Also, this method does not provide for the control and maintenance of the required temperature of the dried gas and oil and gas supplied, respectively, to the MGP and MCP, in order to protect permafrost soils from thawing during underground laying of pipelines in the North of the Russian Federation [see. for example, pp. 33-34, Ananenkov A.G., Stavkin G.P., Andreev O.P., Arabsky A.K., Salikhov Z.S., Talybov E.G. Automatic process control system for gas production facilities. - M .: OOO "Nedra-Business Center", 2003. - 343 p.: ill.; p. 19, Dmitriev V.M., Ganja T.V. and others. Intellectualization of control of technological processes in hydrocarbon deposits. Tomsk: V-Spectrum, 2012. - 212 p.].

The closest in technical essence to the claimed invention is a method for automatically maintaining the temperature regime of technological processes of a low-temperature gas separation plant using air coolers in the Far North [see, RF patent for inventions No. 2685460], which includes preliminary purification of the extracted gas condensate mixture from mechanical impurities , separating NGK and an aqueous solution of inhibitor (VRI) in the separator of the first separation stage, cooling it in the air cooler and separating it into gas and NGK in the low-temperature separator of the second separation stage. After that, NGC and VRI are diverted to a liquid separator (LJ) for degassing, and then NGC from the RJ is pumped to the MCP, the flow of the released gas - the weathering gas from the RJ is transported for disposal or compressed and fed to the MGP, and the VRI is fed to the inhibitor regeneration shop installation. The method provides for the supply of a gas condensate mixture from the outlet of the separator of the first separation stage to the inlet of the air cooler, controlled by a separate automatic control system (ACS) of the air cooler, which together provide the necessary decrease in the temperature of the gas condensate mixture at the outlet of the air cooler to the values specified by the technological regulations, if the atmospheric air temperature guarantees the implementation of such a mode . After leaving the ACU, the cooled gas condensate mixture is divided into two streams and is fed for additional cooling through the pipeline to the inlet of the first section of the recuperative heat exchanger, then TO, "gas-gas" and to the inlet of the first section of TO "gas-condensate" through the gas condensate mixture flow rate CR. This CR, by regulating the flow rate of the gas condensate mixture passing through it, ensures the maintenance of the specified temperature of the oil and gas complex at the outlet of the second section of the TO "gas-condensate". Further, the flows of the gas condensate mixture from the outlets of the first sections of these TO are combined and fed through the CR, which acts as a controlled reducer, to a low-temperature gas separator equipped with a temperature sensor. In this separator, it is finally separated into dried cold gas and a mixture of NGK and VRI. This mixture is fed to the inlet of the second section of the TO "gas-condensate" and then to the RJ for separation into components. The cold 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-to-gas HT, and the second to the bypass of this section, equipped with a gas flow control valve, which changes the ratio of gas flows passing through the HT and bypass, providing real-time correction of the gas temperature necessary to supply it to the MGP.

A significant disadvantage of this method is that the change in the operating mode of the installation in cases of reaching the temperature of the dried gas / LTC entering / supplied to the MGP / MCP, as well as in the low-temperature separator of its limit values - upper or lower, indicated in the technological schedule of the installation, is carried out manually operator, which reduces the quality of process control.

The aim of the invention is to improve the quality of process control to maintain the temperature regime of the installation using air coolers operating in the conditions of the North of the Russian Federation, within the limits and restrictions provided for by the technological regulations of the installation, and to reduce the role of the human factor in the process control to maintain the temperature regime of the installation.

The technical result achieved from the implementation of the proposed method is to improve the quality of process control to maintain the temperature regime of the installation using air coolers operating in the conditions of the North of the Russian Federation by eliminating the human factor when making managerial decisions on managing the process, taking into account the norms and restrictions provided for by its technological regulations for various modes of its operation, providing:

- maintenance of the specified temperature regime of technological processes of the installation, ensuring its efficient operation;

- control and maintenance of the required temperature of dried gas and oil and gas supplied, respectively, to MGP and MCP, in order to protect permafrost soils from thawing during underground laying of gas pipelines in the North of the Russian Federation.

The efficiency of the low-temperature gas separation unit is determined by the value of the pressure drop between its inlet and outlet - the higher the pressure drop, the easier it is to obtain the set (minus) temperature in the low-temperature separator of the unit as a result of throttling. It is obvious that at the stage of the life cycle of fields with increasing gas production, characterized by its high pressure at the inlet of the installation, the set operating mode can be maintained due to reservoir pressure (reservoir energy). At the stages of the life cycle of fields with constant and declining gas production, and there are currently quite a lot of such in the North of the Russian Federation, the pressure drop between the inlet and outlet of the installation drops due to a decrease in reservoir pressure. In this case, it is possible to ensure the specified temperature regime in the low-temperature separator of the installation by attracting an additional source of cold. In the natural and climatic conditions of the North of the Russian Federation, given that there are stable colds for about eight months a year, air coolers are used as an additional source of cold during this period. By controlling the temperature of the produced gas condensate mixture with the help of an air cooler, it is possible to compensate for the missing part of the cold, determined by a decrease in the pressure drop between the inlet and outlet of the installation. As a result, for quite a long time it is possible to maintain the required temperature regime of the installation by using the potential of atmospheric air as a refrigerant, reducing the cost of gas production.

In addition, as a rule, in the North of the Russian Federation, underground laying of MHL and MCP is used in permafrost soils, which, in case of thawing, become subsiding and can destroy MGP and MCP. To avoid this, the unit provides for year-round cooling of gas and gas condensate to a temperature of -2°C, which significantly increases the reliability of the MGP and MCP operation, and reduces the likelihood of emergencies that can lead to serious environmental, human and material losses.

In addition, installations located in the North of the Russian Federation, depending on the current situation with the supply of produced products to consumers, implement one of three possible types of their operation:

1. Supports the flow rate of the produced gas condensate mixture through the installation, if there are no peak loads for dry gas or oil and gas.

2. Maintains dry gas flow through the plant during peak dry gas loads, such as extreme cold weather.

3. Maintains OGK consumption for the installation when there are peak loads on OGK, for example, due to accidents at other fields or due to the need to increase supplies to the consumer.

The inventive method provides automatic control and maintenance of a given temperature regime at installations for low-temperature gas separation with air coolers operating in the conditions of the North of the Russian Federation and implementing the first type of operation, which provides for the implementation of the plan for the production of gas condensate mixture. The method includes maintaining the required temperature value of the dried gas/NGK entering/supplying to the MGP/MKP, as well as the temperature in the low-temperature separator with automatic switching of the technological process to a new mode, if such a need arises. This increases the reliability of operation of the plant and the efficiency of the process of preparing gas and gas condensate for long-distance transport.

The specified problem is solved, and the technical result is achieved due to the fact that the method of automatic control of the low-temperature gas separation unit with air coolers in the North of the Russian Federation includes preliminary cleaning of the produced gas condensate mixture from mechanical impurities and separation of the mixture of oil and gas and VRI in the separator of the first separation stage. This mixture of NGK and VRI is diverted from the cubic part of the separator to the RJ, and the gas condensate mixture from the outlet of the separator of the first stage of separation is fed to the inlet of the air cooler, which is put into operation by the automated process control system (APCS) when the specified temperature difference of the gas condensate mixture and atmospheric air is reached . To do this, the automated process control system sends a corresponding signal to the ACS ACS input, which controls the operation of the ACS, ensuring that the temperature of the gas condensate mixture at its outlet decreases to the specified values necessary to maintain the required temperature in the low-temperature separator. Next, the gas condensate mixture pre-cooled in ACU is divided into two streams. The first of these streams is directed to the pipe space of the first section of the gas-gas TO, where it is cooled by a counterflow of dried gas coming from the low-temperature separator and passing through the second section of the gas-to-gas TO. The second flow of the gas condensate mixture is fed through the CR into the pipe space of the first section of the gas-condensate HT, where it is cooled by the counterflow of the mixture of NGK and VRI, which is discharged from the bottom part of the low-temperature separator and passes through the second section of the HT "gas-condensate". At the same time, the flow rate of the gas condensate mixture for these flows is distributed by the automated process control system using the CR installed at the inlet of the first section of the gas-condensate TO, so that the temperature of the oil and gas complex entering the MCP is within the range specified by the technological regulations. These two flows of gas condensate mixture, after their exit from the first sections of TO "gas-gas" and TO "gas-condensate", are combined and fed to the input of the CR, which acts as a controlled gearbox. This reducer performs adiabatic expansion of the gas condensate mixture and sends it to a low-temperature separator equipped with a temperature sensor, in which the final separation of the gas condensate mixture into dried cold gas and a mixture of oil and gas condensate with VRI is carried out. A mixture of NGK with VRI from the bottom part of the low-temperature separator is fed to the inlet of the second section of the TO "gas-condensate" and further, into the RJ, in which NGK, VRI and weathering gas are separated. NGK with the help of a pumping unit is fed from the RJ to the MCP. VRI is sent to the plant inhibitor regeneration shop. The weathering gas is sent for disposal or pumped to the 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 TO, and the second - to the bypass of this section, equipped with a gas flow control valve. With the help of this CR, the ACS TP regulates the ratio of the dried gas flows passing through the second section of the gas-gas TO and bypass, providing real-time correction of the temperature of the dried gas to the set values required by the technological schedule of the installation when gas is supplied to the MGP.

где n - число допустимых шагов ее изменения. При этом изменение уставки АСУ ТП осуществляет в направлении, обеспечивающем купирование выявленного нарушения регламента эксплуатации установки. После каждого шага изменения значения уставки АСУ ТП удерживает режим управления технологическими процессами установки с новым значением уставки в течение интервала времени не менее τ_const, являющегося индивидуальной характеристикой установки, определяемой экспериментально. И если все контролируемые параметры технологического процесса за это время окажутся в пределах установленных им границ, АСУ ТП фиксирует это новое значение уставки плана расхода добываемой газоконденсатной смеси как рабочее и генерирует сообщение оператору об автоматической смене режима работы установки и его новых характеристиках. Далее АСУ ТП в тандеме с САУ АВО реализуют вновь выбранный режим эксплуатации установки. В противном случае АСУ ТП изменяет значение уставки еще на один шаг в том же направлении.At the same time, the automated process control system in tandem with the automatic control system of the AVO from the moment the unit is put into operation, maintains the flow of the produced gas condensate mixture through the unit and implements the oil and gas production plan. To do this, the APCS uses the initially set values of the settings of the controlled parameters and the limits of their permissible deviations from the values of the settings, which are entered into the database (DB) of the APCS before the installation is put into operation. And as soon as the APCS detects the output of one of the controlled parameters beyond the established limits, which violates the technological schedule of the unit, the APCS starts to step by step change the setting value of the flow plan for the produced gas condensate mixture Q _{GKS_PLAN} for the installation. It is allowed to change this setting within the interval determined by the inequality Q _{min_GKS} ≤ Q _{GKS_PLAN} ≤ Q _{max_GKS} , where Q _{min_GKS} is the minimum allowable, and Q _{max_GKS} is the maximum allowable flow rate of the produced gas condensate mixture at the installation. The step size ΔQ _{GKS_PLAN for} changing this setting is assigned from the relation

where n is the number of allowed steps to change it. At the same time, the change in the setting of the automated process control system is carried out in the direction that ensures the relief of the identified violation of the operating regulations of the installation. After each step of changing the setpoint value, the APCS maintains the plant process control mode with a new setpoint value for a time interval of at least τ _const , which is an individual characteristic of the plant, determined experimentally. And if all controlled parameters of the technological process during this time turn out to be within the limits set by it, the automated process control system fixes this new value of the 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 of the installation and its new characteristics. Further, the APCS in tandem with the ACS ACS implement the newly selected operating mode of the installation. Otherwise, the APCS changes the setpoint value one more step in the same direction.

Before the plant is put into operation, the maintenance personnel enters into the APCS database the setpoint value of the gas condensate mixture production plan for the installation Q _{GKS_PLAN} and the value of its change step ΔQ _{GKS_PLAN} with the boundaries of the interval of allowable changes in the plan from Q _{min_GKS} to Q _{max_GKS.} Enters the following values: temperature settings in the low-temperature separator and boundaries of the interval of permissible changes in the actual temperature T _HC from it, given by the inequality T°C _{min_HC} ≤ T°C _HC ≤ T°C _{max_HC} ; temperature settings of the dried gas entering the MGP and the limits of the interval of permissible changes in the actual temperature Т°С _EG from it, given by the inequality Т°C _{min_OG} ≤ Т°С _OG ≤ Т°C _{max_OG} ; temperature settings for oil and gas supplied to the MCP, and the limits of the interval of permissible changes in the actual temperature T°С of _{oil and gas from it, given by the inequality T°C min_NGK ≤} T°С _{oil and gas ≤ T°C max_NGK .}

The boundaries of the allowable movement S _{KR 2} of the working body of the KR, which controls the flow of the produced gas condensate mixture at the installation, are set, from the value of S _{min_KP 2} - “minimum open” to “fully open”. After entering the specified parameters into the APCS database, the installation is put into operation. From this moment on, the automated process control system conducts the technological processes of the installation using four PID controllers built on its basis, each of which, according to a given algorithm, controls its parameter with the help of a CR connected to it.

In the event that the possibilities to support this type of plant operation are exhausted, the automated process control system generates a message to the operator about the need to make a decision to change the operating mode of gas well clusters, or the operating mode of the plant with the connection of turbo-expander units. The corresponding message is generated if, in the Q _{GCS_PLAN} setpoint correction mode, using the KR installed at the installation inlet and controlling the flow rate of the produced gas condensate mixture, it is revealed that one of the limits of permissible variations in the flow rate of the produced gas condensate mixture Q _{min_GCS} or Q _{max_GCS has been reached} , or the working body of this KP will move to the "fully open" position or reach the minimum allowable position S _{min_KP2} .

In FIG. 1 shows the basic technological scheme of the installation. It uses the following notation:

1 - input line of the installation;

2 - KR of the flow rate of the produced gas condensate mixture for the installation;

3 - flow sensor of the produced gas condensate mixture at the installation;

4 - separator of the first stage of separation;

5 - gas temperature sensor at the air cooler inlet;

6 - outdoor air temperature sensor;

7 - ACS AVO gas;

8 - AVO;

9 - gas temperature sensor at the outlet of the air cooler;

10 - KR flow rate of the gas condensate mixture passing through TO "gas-condensate" 13;

11 - automated process control system of the installation;

12 - TO "gas-gas";

13 - TO "gas-condensate";

14 - KR flow rate of dried gas passing through the bypass of the second section TO "gas-gas" 12;

15 - RJ;

16 - reducing CR of the gas condensate mixture passing through the installation;

17 - temperature sensor of the dried gas entering the MGP;

18 - low-temperature separator;

19 - temperature sensor installed in the low-temperature separator 18;

20 - pumping unit for supplying oil and gas to the MCP;

21 - temperature sensor of NGK supplied to the MCP;

In FIG. Figure 2 shows a block diagram of automatic temperature control of technological processes of the installation. It uses the following notation:

22 - signal from the flow sensor 3 of the produced gas condensate mixture according to the installation, fed to the feedback input PV of the PID controller 30;

23 - setpoint signal for the flow rate of the produced gas condensate mixture for the installation, fed to the input of the task SP of the PID controller 30;

24 - signal from the temperature sensor 17 of the dry gas supplied to the MGP, fed to the feedback input PV of the PID controller 31;

25 - setpoint signal for the temperature of the dried gas supplied to the MGP, supplied to the input of the task SP of the PID controller 31;

26 - signal from the temperature sensor 21 of the NGK supplied to the MCP, coming to the feedback input PV of the PID controller 32;

27 - temperature setpoint signal of the OGK supplied to the MCP, supplied to the input of the task SP of the PID controller 32;

28 - signal from the temperature sensor 19 installed in the low-temperature separator 18, fed to the feedback input PV of the PID controller 33;

29 - temperature setpoint signal in the low-temperature separator 18, fed to the input of the SP task of the PID controller 33;

30 - PID controller for maintaining the flow rate of the produced gas condensate mixture for the installation;

31 - PID controller for maintaining the temperature of the dried gas supplied to the MGP;

32 - PID controller for maintaining the temperature of the oil and gas supplied to the MCP;

33 - PID controller for maintaining the temperature in the low-temperature separator 18;

34 - control signal KR 2;

35 - control signal KR 14;

36 - control signal KR 10;

37 - setpoint signal for ACS AVO 7.

PID controllers 30, 31, 32 and 33 are implemented on the basis of automated process control system 11. The method of automatic control of the installation of low-temperature gas separation from air coolers to the North of the Russian Federation is implemented as follows.

The produced gas condensate mixture through the inlet line 1 of the installation, equipped with a flow sensor 3 and KR 2, enters the inlet of the separator of the first separation stage 4, in which it is initially purified from mechanical impurities and partially separated OGK and VRI. As OGK and VRI accumulate in the lower part of the separator of the first separation stage 4, they are diverted to RJ 15. The gas condensate mixture, partially purified from drip moisture and formation fluid, from the outlet of the separator of the first separation stage 4 through the pipeline enters the ABO 8 inlet, where it is preliminarily (intermediate) cooling due to heat exchange with the air. Obviously, this operating mode of the unit is relevant only when the outdoor air temperature is lower than the temperature of the gas condensate mixture at the ACU inlet. These parameters are measured and controlled by ACS AVO 7 using temperature sensors 5, 6, and its minimum allowable value is set when configuring ACS AVO 7, taking into account the passport data of AVO 8 before starting the installation. The gas condensate mixture from the outlet of the AVO 8 is divided into two streams and fed for further cooling to the inlets of the first sections TO 12 "gas-gas" and TO 13 "gas-condensate". At the same time, the gas condensate mixture enters the TO 13 inlet through the gas condensate mixture flow rate CR 10, which, by changing its flow rate, maintains the specified temperature of the gas-condensate mixture supplied to the MCP. Next, the flows of the gas condensate mixture leaving the first sections TO 12 and TO 13 are combined and fed to KR 16, which acts as a reducer. As a result of the reduction at its outlet, the gas-liquid mixture is cooled, after which it is fed into the low-temperature separator 18, equipped with a temperature sensor 19. In this separator, the final separation of the gas from the NGK and VRI with impurities takes place, which, as they accumulate in the lower part of the separator, they are removed through the second section TO 13 "gas-condensate" in RJ 15. The dried and cooled gas from the outlet of the low-temperature separator 18 is divided into two streams, one of which is fed to the inlet of the second section TO 12 "gas-gas", and the second is sent through its bypass. KR 14 regulates the gas flow through the bypass, changing its flow rate through the second section of TO 12, and maintains the desired temperature of the dried gas entering the MGP, which is equipped with a temperature sensor 17. The mixture of OGK with VRI discharged into RZh 15 from separators 4 and 18 is subjected to separation on fractions and degassing. The flow of the released gas (weathering gas) from RJ 15 is sent for disposal or compressed and fed to the MGP. The NGK flow is transported either to a warehouse, or, using a pump unit 20, it is fed to the MCP, which is equipped with a temperature sensor 21. The WRI flow is fed for regeneration to the inhibitor regeneration shop.

Implementing this method, ACS TP 8 in tandem with ACS AVO 7 solves the following tasks:

a) Evaluates when it is possible to use AVO 8 to provide a given temperature in the low-temperature separator 18, in accordance with the technological schedule of the installation. To do this, ACS AVO 7 in real time with a given discreteness measures the temperature of the ambient air T _{ok.air with} sensor 6, and with sensor 5 the temperature T _{in.AVO of the} gas condensate mixture entering the inlet of AVO 8, and transmits these values to the APCS 11. Using the results of these measurements, APCS 11 monitors compliance with the condition:

T _in.AVO - T _ok.air > ΔT _add. ,

where ΔТ _add. - temperature difference, starting from which AVO 8 can be used to maintain the temperature regime of technological processes implemented at the plant, the value of which is determined based on the passport data of AVO 8.

In case of violation of the specified inequality, the automated process control system 11 of the installation generates a message to the operator about the achievement of the limit value for the use of AVO 8 and the need to make a decision to change the operating mode of the installation (switching to a turbo-expander cooling mode, changing the operating mode of clusters of gas production wells, etc.).

b) Maintains the set temperature value in the low-temperature separator 18 by controlling the degree of cooling of the gas condensate mixture passing through the air cooler 8. To do this, the automatic control system of the air cooler 7 measures the temperature of this mixture at the outlet of the coolant cooler 8 using sensor 9 and controls the thermal performance of the coolant cooler 8 by changing the speed of the wheels , the angle of inclination of the blades and the order in which the fans are switched on by changing the position of the blinds, the number and order of the fan sections involved. To do this, the parameters of this system are selected during design, taking into account the performance of the air cooler and the climatic conditions of the installation location. ACS AVO 7 also provides protection for AVO 8.

To maintain a given flow rate of the produced gas condensate mixture through the unit, which enters the separator of the first separation stage 4, the APCS 11 uses the PID controller 30. To do this, the APCS 11 sends a signal 23 to its task input SP - the value of the setpoint for the flow rate of the produced gas condensate mixture through the installation. Its value is set by the dispatching service of the gas producing enterprise. At the same time, the process control system 11 sends a signal 22 from the flow sensor 3 to the feedback input PV of the same PID controller - the value of the actual flow rate of the produced gas condensate mixture at the installation. Comparing these two signals, the PID controller 30 generates a signal 34 at its output CV, which controls the degree of opening/closing of the CR 2, maintaining the flow rate of the produced gas condensate mixture entering the separator 4 of the first separation stage, set by the task.

To maintain the temperature of the dry gas entering the MGP, the APCS 11 uses a PID controller 31. To do this, the APCS 11 sends a signal 25 to its input of the task SP - the value of the set temperature of the dried gas supplied to the MGP, set in accordance with the technological schedule of the installation . At the same time, ACS TP 11 sends a signal 24 to the feedback input PV of the same PID controller - the value of the actual temperature of the dried gas, measured by sensor 17 installed at the MGP inlet. As a result of processing these signals, the PID controller 31 at its output CV generates a signal 35 that controls the degree of opening / closing of the CR 14, maintaining the temperature of the dried gas entering the MGP by regulating its flow through the bypass of the second section TO 12 "gas-gas".

To maintain the temperature of the OGK supplied to the MCP, the APCS 11 uses a PID controller 32. To do this, the APCS 11 sends a signal 27 to its setpoint input SP - the value of the temperature setpoint of the OGK supplied to the MCP, set in accordance with the technological schedule of the installation. At the same time, ACS TP 11 sends a signal 26 to the feedback input PV of the same PID controller - the value of the actual temperature of the oil and gas complex, measured by sensor 21 installed at the input to the MCP. As a result of their processing, the PID controller 32 at its output CV generates a signal 36 that controls the degree of opening / closing of the CR 10, maintaining the temperature of the oil and gas complex entering the MCP by controlling the flow rate of the produced gas condensate mixture passing through the first section of TO 13 "gas-condensate" .

To maintain the temperature of the gas condensate mixture in the low-temperature separator 18, the ACS TP 11 uses a PID controller 33. To do this, the ACS TP 11 sends a signal 29 to its input of the task SP - the value of the temperature setpoint in the low-temperature separator 18, set in accordance with the technological schedule of the installation. At the same time, the process control system 11 sends a signal 28 to the feedback input PV of the same PID controller - the actual temperature value measured by sensor 19 installed in the low-temperature separator 18. As a result of their processing, the PID controller 33 at its output CV generates a signal 37 that sets the value the temperature of the produced gas condensate mixture at the outlet of the air cooler 8, which in the form of a set point is fed to the input of the automatic control system of the air cooler 7, which uses it and the parameters controlled by it to control the thermal performance of the air cooler 8.

Before putting the unit into operation, the service personnel enters into the DB of the automated process control system 11 the initial values of the following parameters - the degree of opening of the KR 2, KR 10, KR 14, the reducing KR 16 and the lower limit of variations in the position of the working body of the KR 2 - S _{min_KR2} , as well as the setting values for PID controllers 30, 31, 32, 33:

- flow plan of the produced gas condensate mixture for the installation Q _{GKS_PLAN} ;

- temperature of the dried gas Т°С _{setpoint_OG} entering the MGP;

- temperature of NGK T°C _{setpoint_NGK} supplied to MCP;

- temperature in the low-temperature separator - T°C _{setpoint_HC.}

In addition, the maintenance personnel enters into the ACS database the boundaries of permissible changes and restrictions for a number of parameters necessary for its operation:

где n - число допустимых шагов изменения уставки Q_{ГКС_ПЛАН}. В дополнение к этому вводят границы допустимых положений S_{КР 2} рабочего органа КР 2, которые могут варьироваться от «полностью открыт» до «прикрыт до строго заданного, нижнего значения S_{min_КР 2}». В результате АСУ ТП 11 ограничивает работу КР 2 требованием одновременно соблюдать систему из двух неравенств с возможностью пошагового изменения уставки плана добычи газоконденсатной смесиa) setting of the gas condensate mixture production plan Q _{GKS_PLAN} and its allowable variations from Q _{min_GKS} - the minimum allowable value, and up to Q _{max_GKS} - the maximum allowable setting value. At the same time, the automated process control system is allowed to change the setting Q _{GKS_PLAN} only if necessary and step by step, by the value ΔQ _{GKS_PLAN} , which is assigned from the ratio

where n is the number of allowable steps for changing the setpoint Q _{GKS_PLAN} . In addition to this, the limits of permissible positions S _{CR 2} of the working body CR 2 are introduced, which can vary from "fully open" to "covered to a strictly specified, lower value S _{min_CR 2} ". As a result, APCS 11 limits the operation of CG 2 by the requirement to simultaneously comply with a system of two inequalities with the possibility of step-by-step change of the gas condensate mixture production plan set point

b) the temperature setting of the dry gas entering the MGP and the boundaries within which the actual temperature Т°С of the _{exhaust gas} of the dried gas should be, which are given by the inequality

T°C _{min_exhaust} ≤ T°C _exhaust ≤ T°C _{max_exhaust} ,

where Т°C _{min_OG is the} minimum allowable temperature and Т°C _{max_OG is} the maximum allowable dry gas temperature.

c) the temperature setting of the oil and gas complex entering the MCP and the boundaries within which the actual temperature Т°С of the _oil and gas complex of the oil and gas complex should be, which are given by the inequality

T°C _{min_NGK} ≤ T°С _NGK ≤ T°C _{max_NGK} ,

where T°C _{min_NGK is the} minimum allowed value, and T°C _{max_NGK is} the maximum allowable value of the NGK temperature.

d) the temperature setting in the low-temperature separator and the boundaries within which the actual temperature T ° C _HC in it should be, which are given by the inequality

T°C _{min_HC} ≤ T°C _HC ≤ T°C _{max_HC} ,

where T°C _{min_HC is the} minimum allowable temperature and T°C _{max_HC is} the maximum allowable temperature value in the low temperature separator.

During operation of the installation, the position of the working bodies of KR 10 and KR 14, in contrast to the position of KR 2, can change from “fully open” to “fully closed”.

The setting for the flow rate plan of the produced gas condensate mixture at the Q _{GKS_PLAN unit} in the form of a signal 23 is fed to the input of the SP task of the PID controller 30, and the temperature settings in the form of signals 25, 27 and 29 of the ACS TP 11 are fed to the input of the SP task of the PID controllers 31, 32 and 33, respectively, which control the temperatures in the MGP, MCP and in the low temperature separator 18.

During the operation of the plant, the automated control system TP 11 monitors in real time the position of the working bodies KR 2, KR 10, KR 14, as well as the temperature in the low-temperature separator 18 using sensor 19, the temperature of the dried gas/NGK entering/supplied to the MGP/MKP , using sensors 17 and 21, respectively.

Controlling the specified parameters, ACS TP 11 manages the process taking into account the above restrictions and maintains stable fulfillment of the planned target for the consumption of the produced gas condensate mixture - the basic, first type of operation. If during operation it is not possible to achieve the set temperature in the low-temperature separator 18 or the set temperature of the dried gas/NGK entering/supplying to the MGP/MKP, or the working body of the KR 10 or KR 14 will move to one of its extreme positions - either closed or open , then APCS 11 automatically switches to the next mode, which provides for managing the flow plan of the produced gas condensate mixture Q _{GKS_PLAN} for the installation within the allowable variations. This mode of APCS 11 implements with the help of PID controller 30 and controlled by him KR 2 within the limits set by the system of inequalities (1), changing the value of the initially set set point according to the production plan by one step. At the same time, ACS TP 11 generates a message to the operator of the installation about the automatic transfer of the installation to the next mode of operation.

The APCS 11 implements this mode by increasing/decreasing the value of the set value of the flow rate plan for the produced gas condensate mixture for the installation, depending on the current situation in one direction or another, up to the value

Q _{GKS_PLAN} ± ΔQ _{GKS_PLAN} = Q _{GKS_PLAN} ± (Q _{max_GKS} - Q _{min_GKS} )/n.

The APCS sends this changed value in the form of a signal 23 to the input SP of the PID controller 30. Comparing its value with the actual flow rate of the produced gas condensate mixture, the PID controller 30 generates a control signal 34 at its output CV and sets the corresponding value of the degree of opening/closing of the CR 2. This leads to a change in the flow rate of the produced gas condensate mixture passing through the air cooler 8 and the magnitude of the pressure drop between the inlet and outlet of the installation, thereby increasing/lowering the temperature in the low-temperature separator 18, which, in turn, leads to an increase/decrease in the temperature of the gas/NGK entering the IHL / MCP.

Adjustment of the setting value of the plan for the flow rate of the produced gas condensate mixture Q _{GKS_PLAN} for the installation of ACS TP 11 is carried out step by step depending on the direction of the violation and taking into account the inertia of the technological processes of the installation. The number of steps n, covering the entire interval of allowable variations of the change in the flow rate setpoint of the produced gas condensate mixture at the Q _{GKS_PLAN} installation, is usually set equal to 10, 5 steps in each direction from the initially set value. At the same time, at each step, the APCS 11 implements 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. In particular, for the installations of the Zapolyarnoye field, the time τ _const is required for the completion of transient processes of the order of 10 minutes. If, during the implementation of the first step, it is possible to eliminate the violation that occurred during the technological process - to reach the set temperature in the low-temperature separator 18 or the set temperature of the dried gas/NGK entering/supplying to the MGP/MKP, or the working body of the KR 10 or KR 14 will go into one of its operating positions, then APCS 11 continues to work, fixing the value of this setting as a task. Otherwise, the process control system will continue the search by changing the setpoint value by one more step.

This mode of correction of the setpoint Q _{GKS_PLAN} using KR 2, due to changes in the parameters of the state of the environment and other reasons, allows the APCS 11 to repeatedly return to previously implemented modes of operation, including the original one.

If in the setting correction mode Q _{GKS_PLAN} with the help of KR 2 one of the limits of permissible variations in the flow rate of the produced gas condensate mixture Q _{min_GKS} or Q _{max_GKS} is reached, or the working body of KR 2 switches to the “fully open” state or S _{min_KR2} , APCS 11 generates about this message to the plant operator to make a decision on changing the operating mode of gas well clusters, or the operating mode of the plant with the connection of turbo-expander units.

The adjustment of the used PID controllers is carried out by the maintenance personnel at the time the system is put into operation for a specific operating mode of the installation according to the method described, for example, in the "Encyclopedia of process control systems", clause 5.5, PID controller, resource: http://www.bookasutp .ru/Chapter5_5. aspx#HandTuning.

The method for automatic control of a low-temperature gas separation unit from air coolers to the North of the Russian Federation was implemented at Gazprom PJSC Gazprom dobycha Yamburg LLC at the Zapolyarnoye oil and gas condensate field at GTP 1 V and GTP 2 V. The results of operation showed its high efficiency. The claimed invention can be widely used in other existing and newly developed gas condensate fields of the Russian Federation. The use of this method makes it possible to automatically maintain the temperature regime at plants located in the regions of the North of the Russian Federation, within the framework of technological standards and restrictions provided for by their technological regulations, which makes it possible to:

- keep in automatic mode the dynamically changing temperature regime of technological processes of the installation, ensuring its efficient operation, taking into account the dynamics of the current values of external and internal parameters and tolerances for variations in the boundary values of controlled parameters;

- to control and maintain the required temperature of dry gas and oil and gas supplied to MGP and MCP, respectively, in order to protect permafrost soils from thawing during underground laying of gas and condensate pipelines in the North of the Russian Federation.

Claims (3)

1. A method for automatic control of a low-temperature gas separation unit, further the unit, with air coolers (AVO) in the North of the Russian Federation, including preliminary purification of the produced gas condensate mixture from mechanical impurities and separation of a mixture of unstable gas condensate (NGC) and an aqueous solution of inhibitor (VRI) in separator of the first separation stage, after which the mixture of NGK and VRI from the bottom part of the separator is diverted to the liquid separator (LJ), and the gas condensate mixture from the outlet of the separator of the first separation stage is fed to the air cooler inlet, which is put into operation by the automatic process control system (APCS) upon reaching a predetermined temperature difference between the gas condensate mixture and atmospheric air, by applying 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 decreases to the specified values necessary to maintain the required temperature gas-condensate mixture, 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, then TO, "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 TO "gas-gas", and the second flow through the valve-regulator (KR) is fed into the pipe space of the first section of TO "gas-condensate", where it is cooled by a counter-flow of a mixture of NGK and VRI discharged from the bottom part low-temperature separator and passing through the second section of the HT "gas-condensate", while the flow rate of the gas condensate mixture over these streams is distributed by the process control system using the CR installed at the inlet of the first section of the HT "gas-condensate", so that the temperature of the OGK entering the the main condensate pipeline (MCP) was in the range specified by the technological regulations, and after the exit of the gas condensate mixture From the first sections of the TO "gas-gas" and TO "gas-condensate" its flows are combined and fed through the CR, 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 OGK with VRI, which is fed from the bottom part of the low-temperature separator to the inlet of the second section of the gas-condensate TO and further into the RJ, in which NGK, VRI and weathering gas are separated, after which NGK with using a pumping unit, it is fed to the MCP, the VRI is sent to the plant inhibitor regeneration shop, and the weathering gas is sent for utilization or injection into the main gas pipeline (MGP), and the cold dried gas leaving the low-temperature separator is divided into two streams, one of which is fed to the input of the second section of the TO "gas-gas", and the second - to the bypass of this section, equipped with a gas flow control valve, with the help of which the AU U TP regulates the ratio of dry gas flows passing through the second section of the gas-to-gas TO 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, characterized in that the process control system in tandem with ACS AVO from the moment the unit is put into operation, they 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 setpoints of controlled parameters, which are entered into the database (DB) of the process control system before the unit is put into operation, and how only the automated process control system will detect the output of one of the controlled parameters beyond the established limits, violating the technological regulations for the operation of the installation, the automated process control system step by step changes the setting value of the flow rate plan for the produced gas condensate mixture Q _{GKS_PLAN} according to the installation by the value ΔQ _{GKS_PLAN} in the interval determined by the inequality Q _{min_GKS} ≤ Q _{GKS_PLAN} ≤ Q _{max_GKS} , g de Q _{min_GCS} is the minimum allowable, a Q _{max_GKS} is the maximum allowable value of the flow rate of the produced gas condensate mixture in the installation, and in the direction that provides relief of the identified violation of the installation operation regulations, and the step size ΔQ _{GKS_PLAN} is assigned from the ratio

where n is the number of allowable steps for changing the setpoint Q _{GKS_PLAN} , and after each step the APCS keeps the process control mode of the plant with a new setpoint value for a time interval of at least τ _const , which is an individual characteristic of the plant, determined experimentally, and if all controlled parameters of the process process during this time will be within the limits set by it, the APCS fixes this value of the new setpoint of the flow plan 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 the ACS AVO is implemented again the selected operating mode of the installation, otherwise the APCS changes the setpoint value by one more step in the same direction. 2. The method according to claim 1, characterized in that before the unit is put into operation, the operating personnel enters into the APCS database the values of the setpoint of the gas condensate mixture production plan for the unit Q _{GKS_PLAN} and the step value of its allowable change ΔQ _{GKS_PLAN} with the boundaries of the interval of allowable changes from Q _{min_GKS} to Q _{max_GCS} , and also enters the value of the temperature setpoint in the low-temperature separator and the boundaries of the interval of permissible changes in the actual temperature T°С _HC from it, given by the inequality T°C _{min_HC} ≤ T°C _HC ≤ T°C _{max_HC} , in MHP, and the boundaries of the interval of permissible changes in the actual temperature Т°С of the _{exhaust gas} from it, given by the inequality T°C _{min_OG} ≤ Т°С of the _{exhaust gas} ≤ Т°C _{max_OG} , the temperature setting of the oil and gas condensate entering the MCP, and the boundaries of the interval of permissible changes in the actual temperature T °С _NGK from it, given by the inequality T°C _{min_NGK} ≤ T°С _NGK ≤ T°C _{max_NGK} , and also set the boundaries of the allowable movement S _{CR 2} of the working body CR, control which controls the flow rate of the produced gas condensate mixture through the unit, from the “minimum open” position S _{min_KR 2} to the “fully open” position, after which it launches the unit into operation, the technological processes in which are carried out by the automated process control system using four PID controllers built on its basis , each of which, according to a given algorithm, controls its own parameter with the help of a RC connected to it. 3. The method according to claim 2, characterized in that the automated process control system generates a message to the plant operator to make a decision on changing the operation mode of the gas production well clusters or the operation mode of the installation with the connection of turbo-expander units, if in the correction mode of the Q _{GKS_PLAN} setpoint using the KR installed on at the inlet of the installation and controlling the flow rate of the produced gas condensate mixture, as soon as it is revealed that one of the limits of permissible variations in the flow rate of the produced gas condensate mixture Q _{min_GCS} or Q _{max_GCS has} been reached, or the working body of this CR will switch to the “fully open” position or has reached the minimum allowable position S _{min_CR 2} .

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