Method for automatic load distribution between low-temperature separation process lines with air cooling units at complex gas treatment units at peak gas production loads

Abstract

FIELD: gas production.SUBSTANCE: invention relates to the field of production and preparation of natural gas from Valanginian deposits for long-distance transportation at complex gas treatment units (CGTU) during peak gas production loads at oil and gas condensate fields (OGCF) in the Far North of the Russian Federation, in particular to the automatic load distribution between process lines (PL) of low-temperature separation with air cooling units (ACU) during peak gas production loads, ensuring maintenance within the required limits of the level of unstable gas condensate (OGC) in three-phase liquid separators (LS), control of its density and flow rate at the CGTU when feeding into the main condensate pipeline (MCP). The purpose of the invention is to provide automatic load distribution between PL with ACU during peak loads for gas production and maintaining the required filling level of the natural gas storage tank in the natural gas storage tank, managing its density and consumption at the gas treatment plant, taking into account the condition of the equipment involved in the process of preparing natural gas for long-distance transport, while adhering to the standards and restrictions stipulated by the process regulations of the unit for its various operating modes. Automatic load distribution between the transformer substation is provided with the automatic cooling system and preparation of the OGC from natural gas at all stages of the CGTU operation using dry gas at the CGTU at peak loads of consumption on the part of consumers.EFFECT: maintaining the filling level of OGC in the LS within the required limits, controlling its density and consumption at the CGTU, taking into account the condition of the equipment involved in the process of preparing natural gas for long-distance transport, while observing the standards and restrictions stipulated by the process regulations of the unit for its various operating modes.4 cl, 2 dwg

Description

[0001] The invention relates to the field of production and preparation of natural gas from Valanginian deposits (hereinafter referred to as natural gas) for long-distance transportation at integrated gas treatment units (IGTU) during peak gas production loads at oil and gas condensate fields (OGCF) in the Far North of the Russian Federation, in particular, to the automatic load distribution between process lines (PL) of low-temperature separation with air cooling units (ACU) during peak gas production loads, ensuring maintenance within the required limits of the level of unstable gas condensate (OGC) in three-phase liquid separators, hereinafter referred to as RL, control of its density and flow rate at the IGTU when feeding into the main condensate pipeline (MCP).

[0002] A known method for automating a low-temperature gas separation unit includes automatically maintaining set temperatures and pressures in the unit [see, for example, p. 406, R.Ya. Isakovich, V.I. Loginov, V.E. Popadko. Automation of Production Processes in the Oil and Gas Industry. Textbook for Universities, Moscow, Nedra, 1983, 424 p.]. The degree of degassing of the oil and gas condensate in this method is maintained by heating it using a heating coil installed in the tank of the degasser-separator.

[0003] The disadvantage of this method is that, due to the inertia of the heating process and the lack of control over the density of the natural gas supplied to the MCP, the degree of degassing and the maintenance of the natural gas density during its supply to the MCP are carried out virtually "blindly," significantly reducing the quality of the natural gas supplied to consumers. Furthermore, when distributing the load between gas pipelines at the gas treatment plant, the condition of the equipment involved in preparing the natural gas for long-distance transport, which affects the quality of the product supplied to consumers, is completely ignored. There is also no control over the filling level of the liquid, which is a potential source of emergency situations or malfunctions in the gas treatment plant, which can occur both due to overfilling and underfilling.Moreover, all these problems are significantly exacerbated when an order is received to switch the plant to the maximum possible volume of dry gas preparation during peak loads at its consumers, for example, due to weather conditions.

[0004] The closest in technical essence to the claimed invention is a method for automatic load distribution between low-temperature gas separation lines at a gas treatment plant (GTP) using air-cooled units at the Northern Russian Federation NGKM [RU Patent No. 2743869], which includes monitoring a number of parameters by means of the GTP's automated process control system (APCS). These include the flow rate of dried gas entering the main gas pipeline (MGP) and the flow rate of NGK entering the MCP. The ACS maintains the gas separation temperature in each low-temperature separator and controls its operating mode at a given gas flow rate. The ACS, having received a target for the GTP's NGK production volume, executes it using a proportional-integral-differentiative (PID) controller for maintaining the NGK flow rate in the MCP.The APCS sends a dispatcher's setpoint signal to the SP input of this PID controller, and simultaneously sends a signal of the current flow rate of the NGK in the MCP to its PV feedback input. By comparing the setpoint and the current flow rate of the NGK, this PID controller generates a setpoint signal for the flow rate of dry gas through the gas treatment plant at its CV output, at which it will supply the required volume of NGK to the MCP. This setpoint signal is sent to the SP input of the PID controllers of all low-temperature gas separation TLs. The APCS sends a signal of the actual flow rate of dry gas through the gas treatment plant to the PV feedback input of these PID controllers. The proportionality coefficient signal K, calculated individually for each TL, is also simultaneously sent to the Kp input of the PID controllers. п_i , (where i is the TL number), which determines the degree of influence of this PID controller on the gas flow control valve (GV) controlled by it according to its TL. The value of the proportionality coefficient K п_iFor each low-temperature separator, the proportionality coefficient calculation unit determines its refrigeration capacity based on the refrigeration capacity of its air-cooled cooler installed after the first-stage separator. The air-cooler operation is controlled by an individual automatic control system (ACS) in accordance with the APCS task, generated taking into account the current process parameters in each low-temperature separator and the environmental conditions. The ACS monitors the refrigeration capacity of the gas air-cooler and sends a corresponding signal to the proportionality coefficient calculation unit of its low-temperature separator.

[0005] A significant drawback of this method is that, due to the lack of control over the density of the NGK supplied to the MCP, the degree of degassing and the maintenance of the NGK density in the TL are carried out virtually blindly, without precise process control. This reduces the quality of the NGK supplied to consumers. There is no control over the filling level of the RL, which is a potential source of emergency situations or malfunctions in the CGTU, which can occur both due to overfilling and underfilling. Moreover, all these problems are significantly exacerbated when an order is received to switch the plant to the maximum possible volume of dry gas treatment during peak loads at its consumers, for example, due to weather conditions.

[0006] According to the technological process of collecting and preparing natural gas for long-distance transportation, natural gas from the clusters of production wells enters the UKPG - the switching valve building, from where it is distributed through a common raw gas collector to several (up to 8, and in the future - even more) identical gas TL [see p. 361, Andreev E.B. et al. Automation of technological processes for oil and gas production and preparation: a textbook for universities. - M .: OOO "Nedra-Business Center", 2008. - 399 p.]. For example, at the Zapolyarnoye OGCF, four TL of low-temperature gas separation are used in UKPG-1V and UKPG-2V.

[0007] During operation, for various reasons, such as sudden water blowouts and sand production in wells during natural gas production, equipment corrosion, etc., the condition of the gas treatment plant equipment changes, leading to deterioration in the performance of the separators. This results in increased carryover of liquid droplets and mechanical impurities, which reduces the efficiency of the recuperative heat exchangers (RHEs) due to contamination of the surface of their heat exchange tubes. The formation of hydrate and other deposits in the GPP units leads to changes in the pressure drop across them, which ultimately impacts their performance, i.e., the quality of the recovered natural gas, specifically its density.

[0008] It is clear that the condition of the gas pipeline equipment at the gas treatment plant (GTP) varies unevenly. Therefore, the actual performance of each pipeline will differ. Therefore, to improve the efficiency of the natural gas preparation process for long-distance transportation, it is necessary to distribute the load between the GTP pipelines in real-time, taking into account the actual condition of each line. This will significantly improve the quality of natural gas preparation for long-distance transportation while adhering to the standards and limitations of the GTP process regulations.

[0009] In practice, it is necessary to shut down or restart producing gas condensate wells, for example, during gas-hydrodynamic studies, when refining the reservoir pressure at a given site, etc., which leads to changes in the unit's operating mode and, accordingly, to a change in the actual flow rate of gas condensate from the unit to the gas condensate. This may result in situations of overfilling or underfilling of the gas condensate, which may lead to a shutdown of the technological process or a failure of the gas condensate treatment plant, or may cause gas locks and their accumulation in the gas condensate treatment plant. Such changes may entail a number of adverse consequences and become a source of serious complications and accidents in the gas field. In some cases, these factors can lead to significant material, human, and environmental losses [see, for example, A.A. Korshak, A.I. Zabaznov, V.V. Novoselov et al. Pipeline transportation of unstable gas condensate. - M: VNIIOENG, 1994, p. 224].

[0010] The purpose of the invention is the automatic distribution of the load between the TL with the AVO during peak loads for gas production and maintaining the filling level of the NGK in the RZh within the required limits, controlling its density and consumption at the UKPG taking into account the state of the equipment involved in the process of preparing natural gas for long-distance transport, while observing the standards and restrictions stipulated by the technological regulations of the installation for various modes of its operation.

[0011] The technical results achieved from the implementation of the invention are the automatic distribution of the load between the TL with the AVO during peak loads for gas production and maintaining the filling level of the NGK in the RZh within the required limits, controlling its density and consumption at the UKPG taking into account the state of the equipment involved in the process of preparing natural gas for long-distance transport, while observing the standards and restrictions stipulated by the technological regulations of the installation for various modes of its operation.

[0012] The claimed method ensures automatic load distribution between pipelines with automatic cooling systems during peak gas production loads and maintains the required filling level of the gas-to-liquid mixture within the required limits, controls its density, and controls the flow rate at the gas-to-liquid treatment plant, taking into account the equipment condition of each pipeline. This improves the quality of gas-to-liquid mixture supplied to consumers and prevents the formation of gas locks and their accumulation in the gas-to-liquid treatment plant, increasing its operational reliability and reducing the risk of complications and accidents at the gas-to-liquid treatment plant, which could lead to serious environmental, human, and material losses.

[0013] The stated problem is solved, and the technical result is achieved due to the fact that the method of automatic load distribution between low-temperature separation process lines with air cooling devices at integrated gas treatment plants during peak gas production loads includes control of the flow rate of dried gas by means of the automated process control system of the integrated gas treatment plant. , coming into the MGP, the consumption of oil and gas , entering the MCP. The automated process control system automatically maintains the gas separation temperature in the low-temperature separator of each TL at a given gas flow rate by varying the gas throttling degree at the nozzle located before this separator, and fulfills the task of the gas production enterprise (GPE) dispatcher regarding the volume of dried gas preparation. The task for the volume of dry gas preparation is entered as a setpoint in the database (DB) of the automated process control system, which implements the plan for the production of dry gas by monitoring the observance of equality using PID controllers to maintain the flow rate of dried gas in the gas distribution system. For this purpose, the automated process control system sends a setpoint signal to the SP input of these PID controllers. , and at the same time, the PV feedback input of these PID controllers of the APCS sends a signal of the actual flow rate of the dried gas by the gas condensate treatment plant, comparing which each PID controller generates a control signal at its CV output - the value of the gas condensate mixture flow rate for its TL, at which the total contribution of all TL will ensure the specified planned volume of dry gas preparation according to the UKPG. Also, at the same time, a signal of the proportionality coefficient value is fed to the Kp input of the PID controller of each TL , which determines the degree of contribution of the i-th TL, where i is the TL number, to the process of maintaining a given volume of dry gas preparation at the gas treatment plant in real time. This proportionality coefficient sets the degree of influence of the PID controller on the controlled KR of the gas condensate mixture flow rate according to its TL, located before the low-temperature separator. In this case, the value of the proportionality coefficient is determined for each TL by its proportionality coefficient calculation unit.

[0014] The automated process control system of the gas treatment plant implements the execution of the adjusted planned task for the preparation of dry gas at moments of peak load for its consumption, automatically maintains the density of the NGK prepared by each TL individually, achieving its compliance with the task - the density setpoint The NGK for the CGTP. This is achieved by controlling the temperature in the TL's low-temperature separator, which must be maintained to achieve the specified NGK density. This required temperature is maintained using a cascade of two PID controllers and an air-cooling unit controlled by the TL's own ACS. To achieve this, the APCS sends a setpoint signal to the SP input of the first PID controller. , common to all TL, and to its feedback input PV it supplies an individual signal of the density value of the NGC , recorded by the density sensor measuring the oil and gas component, coming from the i-th TL to the MCP. As a result of processing these signals, the first PID controller of the cascade generates a setpoint value at its CV output - setting the temperature that must be maintained in the low-temperature separation separator to achieve the specified density of the oil and gas mixture. Setpoint signal is fed to the input of the SP task of the second PID controller of the temperature maintenance cascade in the low-temperature separator of the i-th TL. At this time, the automated process control system of the gas treatment plant sends a signal of the actual temperature value to its feedback input PV In the low-temperature separator, recorded by the temperature sensor in the low-temperature separator of the i-th TL. By processing these signals, the second PID controller, at its CV output, generates a setpoint signal to change the degree of pre-cooling of the gas-liquid mixture as it passes through the air-cooling unit. This signal is fed to the setpoint input of the i-th TL's ACS, which automatically selects the appropriate operating mode for the unit, ensuring the required pre-cooling of the gas-liquid mixture passing through the air-cooling unit. As a result of this operation, the system maintains the required temperature in the low-temperature separator of the i-th TL.

[0015] In each measurement cycle, the process parameter compliance control unit for the i-th TL checks the compliance of the actual values ​​of the process parameters with the established limits: the level of the NGK in RZh; consumption of dry gas ; temperatures in the low-temperature separator of the i-th TL. This control unit performs this check by assessing the compliance of the controlled parameters with the specified limits, using the following inequalities, which represent a complex individual condition for the normal operation of the i-th TL technological process:

[0016]

[0017] where And - settings for the minimum and maximum values ​​of the oil and gas level in the RZh, respectively; And - settings of the minimum and maximum flow rate of dried gas of the i-th TL, respectively; And - minimum and maximum temperature settings in the low-temperature separator of the i-th TL, respectively. Maintenance personnel set these setpoints based on the equipment manufacturer's specifications and the requirements of the process regulations for the unit.

[0018] If, as a result of checking the condition for normal operation of the technological process, the i-th control block establishes that it is observed in the given measurement cycle simultaneously for all the inequalities that make it up, then it generates a logical “zero” signal at its output O, which is then fed to the start / stop input of the PID controller that controls the volume of preparation of the dried gas at the i-th TL, allowing it to control the KR flow rate of the gas condensate mixture through it.

[0019] But if during the technological process at least one of the values , And If the i-th TL reaches its preset limit value or exceeds its specified limits during the next measurement cycle, this control unit generates a logical "one" signal at its output O, which is fed to the "start / stop" input of the PID controller, which controls the dry gas preparation volume at the i-th TL. As soon as this PID controller receives this signal, it pauses its operation, storing the previous control signal value calculated in the previous calculation cycle at its CV output. As a result, the i-th TL is excluded from the control process, but it continues to operate with the process parameters recorded at the time of its exclusion from the control process.

[0020] When the i-th TL is removed from the control process, all changes in the gas dehydration load are automatically distributed among the operating TLs whose operating parameters correspond to their individual normal process conditions. This operating mode continues until maintenance personnel eliminate the cause of the process disruption that caused the i-th TL to be removed from the control process. Once compliance with the integrated normal process conditions for the i-th TL is restored, its control unit sets a logical "zero" signal at its output O. This signal is fed to the "start / stop" input of the PID controller, which controls the volume of dehydrated gas preparation at the i-th TL, permitting its inclusion in the overall control system for automatic load distribution among the CGTP TLs.

[0021] Proportionality coefficient value calculates an individual block for calculating the proportionality coefficient for the PID controller that controls the volume of dry gas preparation at the i-th TL, using the following formulas:

[0022] - if the performance of the TL needs to be increased, i.e. , then the value he calculates using the formula:

[0023]

[0024] - and if the TL performance needs to be reduced, i.e. , then the value he calculates using the formula:

[0025]

[0026] where - the current value of the oil and gas level in the RZh of the i-th TL, controlled by the level sensor, the signal of which is fed to the input I2 of the proportionality coefficient calculation block for the PID controller of the i-th TL;

[0027] And - the minimum and maximum levels of the NGK in the RP of the i-th TL are set according to the RP passport, and their signals are fed to the inputs I1 and I3 of the proportionality coefficient calculation block for the PID controller of the i-th TL, respectively;

[0028] And - the settings of the minimum and maximum values ​​of the proportionality coefficient for the PID controller of the i-th TL, which are assigned based on the state of the process equipment of this TL, taking into account the technological standards and restrictions provided for by the technological regulations of the installation, and their signals are fed to inputs I4 and I5 of the proportionality coefficient calculation block for the PID controller of this line, respectively.

[0029] All specified settings for all TL are entered by the operating personnel into the DB of the automated process control system of the gas treatment plant before putting the plant into operation, and during operation all calculations according to the given formulas, they are limited by the following condition:

[0030]

[0031] If all the TL units have exhausted their capabilities to comply with their individual conditions for the normal conduct of the technological process, the APCS generates a message to the unit operator about the impossibility of maintaining the specified values ​​of the flow rate and density of the NGK for the GPP and the need to change its operating mode.

[0032] During periods of peak demand for dry gas, its supply to the gas treatment plant is set by adjusting the planned target of the gas treatment plant for the preparation of dry gas. , and the resulting excess of NGK preparation is sent to the NGK reservoir farms of the GDP and / or the NGK processing complex with subsequent adjustment of the NGK supply plan to consumers under the MCP.

[0033] Figure 1 shows a high-level flow diagram of a CGTU using an air-cooled cooler. To simplify the presentation of the application, Figure 1 shows the sensor and control system connections for only one – the first – TL. Figure 2 shows a block diagram of the automatic control of load distribution between TLs with air-cooled coolers and maintaining the required oil and gas level in the liquid fuel, as well as control of its density and flow rate at the CGTU.

[0034] The following notations are used in Fig. 1:

[0035] 1 - raw gas collector;

[0036] 2 - collector of aqueous inhibitor solution (AIC);

[0037] 3 i - first stage separator of the i-th TL, (i = 1, 2, …, n, where n is the number of TL at the gas treatment plant);

[0038] 4 i - AVO i-th TL, equipped with self-propelled guns;

[0039] 5 i - RZ i-th TL;

[0040] 6 i - sensor for measuring the flow rate and density of the i-th TL oil and gas complex;

[0041] 7 i - oil level sensor in the i-th TL;

[0042] 8 - industrial control system of the gas treatment plant;

[0043] 9 i - TO "gas-gas" i-th TL;

[0044] 10 i - TO "gas condensate" i-th TL;

[0045] 11 - vented gas collector;

[0046] 12 i - intermediate separator of the i-th TL;

[0047] 13 i - dry gas flow sensor of the i-th TL;

[0048] 14 i - KR of gas condensate mixture flow rate of the i-th TL;

[0049] 15 i - low-temperature separator i-th TL;

[0050] 16 i - temperature sensor in the low-temperature separator of the i-th TL;

[0051] 17 - IGP;

[0052] 18 - Manual transmission.

[0053] The following notations are used in Fig. 2:

[0054] 19 i - actual temperature signal in low-temperature separator 15 i (comes from sensor 16 i ) i-th TL;

[0055] 20 i - signal of actual density of oil and gas (comes from the flow and density sensor NGK 6 i ) i-th TL;

[0056] 21 - setpoint signal - density of the oil and gas complex by the gas treatment plant (comes from the automated process control system 8 to the input of the SP task of all PID controllers 22);

[0057] 22 i - PID controller for maintaining the density of the i-th TL oil and gas pipeline;

[0058] 23 i - PID controller for maintaining temperature in the low-temperature separator 15 i i-th TL;

[0059] 24 i - signal for changing the refrigeration capacity of AVO 4 i i-th TL;

[0060] 25 i - setpoint signal minimum level value in RZh 4 i i-th TL;

[0061] 26 i - actual value signal level of NGK in RZh 4 i (comes from sensor 7 i ) i-th TL;

[0062] 27 i - setpoint signal - the maximum level of NGC in the RZh 4 i i-th TL;

[0063] 28 i - setpoint signal - minimum temperature in the low-temperature separator 15 i i-th TL;

[0064] 29 i - setpoint signal - maximum temperature in the low-temperature separator 15 i i-th TL;

[0065] 30 i - setpoint signal - minimum flow rate of dried gas of the i-th TL;

[0066] 31 i - actual consumption signal dried gas of the i-th TL (comes from sensor 16 i );

[0067] 32 i - setpoint signal - maximum flow rate of dried gas of the i-th TL;

[0068] 33 i - a block for monitoring the compliance of the technological process parameters with the established boundaries of the i-th TL;

[0069] 34 - preparation plan setting signal dried gas from the gas processing plant (comes from the automated process control system 8);

[0070] 35 - actual consumption signal dried gas according to the gas processing plant (APCS 8 is determined by summing the readings of sensors 13);

[0071] 36 i - setpoint signal - minimum value of the proportionality coefficient for the PID controller 39 i i-th TL;

[0072] 37 i - setpoint signal - maximum value of the proportionality coefficient for the PID controller 39 i i-th TL;

[0073] 38 i - block for calculating the proportionality coefficient for PID controller 39 i i-th TL;

[0074] 39 i - PID controller for maintaining the flow rate of dried gas of the i-th TL;

[0075] 40 i - control signal sent to KR 14 i consumption of gas condensate mixture of the i-th TL.

[0076] The process of preparing natural gas for long-distance transportation at the gas treatment plant, the structural diagram of which is shown in Fig. 1, includes:

[0077] - primary separation of natural gas in inlet separators 3 i ;

[0078] - cooling the inlet flow of gas condensate mixture in TO 9 i "gas-gas" with a flow of cooled gas and in TO 10 i"gas-condensate" flow of cooled mixture of VRI with NGK;

[0079] - intermediate separation of gas condensate mixture in separators 12 i for its subsequent division;

[0080] - cooling of gas condensate mixture by throttling the flow at KR 14 i ;

[0081] final separation of cooled gas condensate mixture in low-temperature separators 15 i .

[0082] - maintaining the specified density of oil and gas in RZh 5 i by controlling the temperature in the low-temperature separator 15 i .

[0083] PID controllers 221…, 22 n , 231…, 23 n , 391…, 39 n , control units 331…, 33 n , as well as blocks for calculating the proportionality coefficient 381…, 38 n implemented on the basis of APCS 8.

[0084] The method for automatic load distribution between low-temperature separation process lines with air cooling devices at integrated gas treatment plants for oil and gas condensate plants during peak gas production loads is implemented as follows.

[0085] Natural gas from production well clusters enters the gas treatment plant (GTP) in the switching valve building, from where it is distributed through raw gas manifold 1 via inlet lines to the gas transfer lines. For simplicity, we will consider the operating principle of only one gas transfer line, the i-th gas transfer line, since all gas transfer lines operate in the same manner.

[0086] Natural gas is fed through inlet line 1 to the first stage separator 3 i , in which the liquid phase (formation water with dissolved inhibitor and condensed hydrocarbon condensate) is separated, which is fed to the RZh 5 i The separated gas condensate mixture is then fed to AVO 4 i, equipped with its own automatic control system, where it is pre-cooled to a temperature that ensures the specified technological mode in the low-temperature separator 15 i (if the ambient temperature allows its implementation). Coming from the output of AVO 4 i the gas condensate mixture is divided into two streams and sent to TO 9 i "gas-gas" and TO 10 i "gas-condensate" for cold recovery from the throttled (cooled) gas flow and the separated mixture of VRI and condensate removed from separators 12 i and 15 i , respectively. To prevent hydrate formation, a hydrate inhibitor (not shown in Fig. 1) is injected into the mixture flow before the TO. Then, the cooled gas-liquid mixture flows from the TO 9 outlets i "gas-gas" and TO 10 i "gas-condensate" is combined and fed to the input of the intermediate separator 12 i , where further separation of the liquid phase occurs. From the outlet of the intermediate separator 12i gas-liquid mixture through KR 14 i the gas condensate mixture flow rate is fed into the low-temperature separator 15 i , where condensed liquid hydrocarbons and VRI are finally separated from the gas condensate mixture flow.

[0087] Dried gas from low-temperature separator 15 i passes through maintenance 9 i "gas-gas", where it is heated and through a pipeline equipped with a gas flow sensor 13 i , enters the MGP 17. The liquid phase is a mixture of NGK and VRI from the low-temperature 15 i and intermediate separator 12 i , passing through TO 10 i "gas-condensate" gives off cold to the oncoming flow of gas-condensate mixture, after which it mixes with the liquid phase removed from separator 3 i , and then goes to RZh 5 i .

[0088] Specified density The NGK is automatically maintained by regulating the separation of light hydrocarbon fractions from the gas-liquid mixture in a low-temperature separator 15 i , realized by changing the temperature within it. This temperature change is achieved by controlling the preliminary cooling of the gas-liquid mixture as it passes through the AVO 4 i , the control system of which regulates cooling based on the task (signal 24 i ) to change its cooling capacity, formed by a cascade of PID controllers 22 i and 23 i based on the density setting NGK by UKPG, actual density of NGK and actual temperature in low-temperature separator 15 i i-th TL. Preliminary cooling of the gas-liquid mixture is performed by AVO 4 i taking into account the current state of the atmospheric air and can be implemented as described in Russian patent No. 2692164.

[0089] Weathered gas, a mixture of low-density hydrocarbons, from RZh 5 i is removed through the exhaust gas collector 11 and sent for compression (not shown in Fig. 1) for further feeding to the MGP 17, or for disposal. The exhaust gas discharged from the lower part of the RZh 5 i , through the VRI 2 collector, it is sent for regeneration to the inhibitor regeneration shop of the UKPG (not shown in Fig. 1). The NGK flow is diverted through a pipeline equipped with a Coriolis flow meter 6 i with the function of measuring the density of the oil and gas complex, its flows from all the transport lines are combined and fed to the MKP 18 for further transportation to consumers.

[0090] Peak gas production loads occur, for example, due to the onset of severe cold weather, especially in winter, due to the demand for dry gas from consumers. During this period, the Valanginian gas treatment plants typically implement an upwardly adjusted planned target for the preparation of dry gas supplied to consumers. During such periods, the volume of gas treatment at the NGK , as a rule, exceeds the specified planned supply volume of oil and gas to consumers via the MCP. In this situation, excess NGK preparation is sent to the NGK GDP tank farms and / or the NGK processing complex, with subsequent adjustment of the NGK supply plan. to consumers via the MCP. At such times, the preparation of dry gas occurs as follows.

[0091] The adjusted task of the GDP dispatcher for the volume of dry gas preparation at the CGTP is maintained by the APCS 8 using PID controllers 39. For this, the APCS 8 sends signal 34 to the input of the SP task of the PID controllers 39 - the setpoint value - a plan for preparing dry gas for the gas treatment plant. Simultaneously, a common signal 35, the actual flow rate of dry gas, is sent to the PV feedback input of all these PID controllers of the APCS 8. for the gas treatment plant, which the automated process control system 8 determines by summing up the readings of the gas flow sensors 13 for all TL.

[0092] PID controllers 39 continuously monitor the compliance of the actual dry gas preparation all TL UKPG to the planned task determined by the setpoint The operator sets this setpoint based on the daily plan for dry gas preparation via the gas distribution system, released by its dispatcher, and enters it into the CGTP automated process control system database. If compliance monitoring reveals that:

[0093] ,

[0094] Then PID controllers 39 generate a control signal at their output to increase the flow of the produced gas condensate mixture through the gas treatment plant. If it is determined that:

[0095] ,

[0096] Then PID controllers 39 generate a control signal at their output to reduce the flow of the produced gas condensate mixture through the gas condensate treatment plant. As a result, the flow rate of dry gas and, accordingly, the flow rate of NGK through the gas condensate treatment plant will be increased in the first case, or decreased in the second case, by all PID controllers 39 controlling their KR 14 simultaneously. This increase or decrease in TL performance is carried out until the gas condensate treatment plant reaches its planned target. for the preparation of dried gas, i.e. until the compliance condition is met:

[0097] .

[0098] Load distribution between TL is carried out taking into account the state of the process equipment by applying to the Kp input of the PID controller 39 isignal of the value of the proportionality coefficient K п_i , which is calculated individually for each i-th TL by its proportionality coefficient calculation unit 38 i according to the following formulas:

[0099] - if the TL performance needs to be increased, i.e. , then the value is determined by the formula:

[0100]

[0101] - if the TL performance needs to be reduced, i.e. , then, meaning is determined by the formula:

[0102]

[0103] where - current value of the level of NGC in RZh 5 i , which comes from level sensor 7 i , installed on RZh 5 i ,; , - settings - minimum and maximum level of NGK in RZh 5 i , accordingly, is established by the service personnel in accordance with his passport; , - settings - the minimum and maximum values ​​of the proportionality coefficient, respectively, are also set by the operating personnel. Values , are determined based on the state of the technological equipment of each TL at the time of starting up the installation, taking into account the technological standards and restrictions stipulated by the technological regulations of the installation.

[0104] Calculation according to formulas (1) and (2) are limited by the following conditions:

[0105]

[0106] When the dry gas capacity of the gas treatment unit (GTU) needs to be increased, the refrigeration units (TL) with a higher refrigeration capacity reserve will be used first, i.e., with the ability to increase the heat exchange between the gas condensate mixture and the atmospheric air in the ACU. Conversely, when the GTU's dry gas capacity decreases, attention will be given to reducing the load on TLs operating at or near maximum capacity, i.e., with a high reserve capacity to reduce the heat exchange between the gas condensate mixture and the atmospheric air in the ACU.

[0107] To maintain the set value of the NGK density, the maintenance personnel sets the set value , which is loaded into the APCS 8 database. From it, the setpoint In the form of signal 21, it feeds the SP input of all PID controllers 22, each of which maintains the density of the oil and gas complex in the RZh 5 of its TL. Simultaneously, it feeds the PV feedback input of each of these PID controllers 22 iACS TP 8 sends an individual signal 20 i - the value of the actual density of the oil and gas complex , recorded with sensor 6 i , measuring the density of the NGK coming from RZh 5 i in the MCP 18. As a result of processing these signals, each PID controller 22 generates a setpoint value at its CV output - setting the temperature that must be maintained in separator 15 i low-temperature separation to achieve the specified density of the oil and gas condensate. The signal from each of these settings is then fed to the SP input of the corresponding PID controller 23 i . At the same time, signal 19 is fed to the PV feedback input of this PID controller. i - actual temperature value in low-temperature separator 15 i , recorded by sensor 16 i . As a result, at the output of the CV PID controller 23 i generates a task signal 24 ito change the degree of preliminary cooling of the gas-liquid mixture when it passes through the AVO 4 i , which is fed to the input of its automatic control system, which automatically selects the appropriate operating mode of the device, providing the required preliminary cooling of the gas condensate mixture passing through the AVO 4 i As a result, the system maintains the required temperature in the low-temperature separator 15 i i-th TL.

[0108] Control unit 33 i in each measurement cycle, it checks the compliance of the actual values ​​with the requirements of the technological process: the level of the NGC in RZh 5 i (signal 26 i ); consumption of dried gas (signal 31 i ); temperature in the low-temperature separator (signal 19 i ) i-th TL. This check is carried out by control unit 33 iis carried out by assessing the compliance of the controlled parameters with the specified limits, using for this the following inequalities, which represent a complex individual condition for the normal conduct of the technological process of the i-th TL:

[0109]

[0110] where - setting the minimum level in RZh 4 i i-th TL;

[0111] - setting the maximum level in RZh 4 i i-th TL;

[0112] - setting of the minimum flow rate of dried gas of the i-th TL;

[0113] - setting of the maximum flow rate of dried gas of the i-th TL;

[0114] - setting the minimum temperature in the low-temperature separator to 15 i ;

[0115] - setting the maximum temperature in the low-temperature separator to 15 i .

[0116] Meanings , , , , And are set on the basis of the passport data provided by the manufacturer of this equipment, as well as the requirements of the technological regulations for this installation.

[0117] If as a result of checking the normal process conditions, control unit 33 i establishes that it is observed in a given measurement cycle simultaneously for all inequalities, then it generates a logical “zero” signal at its output O, which is then fed to the start / stop input of the PID controller 39 i , controlling the volume of preparation of dried gas at the i-th TL, allowing it to control KR 14 i consumption of gas condensate mixture through it.

[0118] If during the technological process the values , And If the i-th lines reach their set limit values ​​or go beyond their frame values, then individual control unit 33 igenerates a logical “one” signal at its output O, which is fed to the “start / stop” input of PID controller 39 i , which controls the volume of dry gas preparation at the i-th TL. Having received this signal, the PID controller 39 i pauses its operation, storing at its CV output the previous value of the control signal, which was calculated in the previous calculation cycle.

[0119] When such a situation occurs, the APCS 8 generates a message for the plant operator, informing it of a problem on the i-th TL, and this line is excluded from the control process. However, it continues to operate with the process parameters recorded at the time it was excluded from the control process.

[0120] When the i-th TL is removed from the control process, all changes in the gas dehydration load will be automatically distributed among the operating TLs whose operating parameters correspond to their individual process conditions. This operating mode will continue until maintenance personnel eliminate the cause of the process disruption that caused the i-th TL to be removed from the control process.

[0121] As soon as compliance with the individual complex condition for the normal conduct of the technological process for the i-th TL is restored, control unit 33 i sets a logical "zero" signal at its output O, which is fed to the "start / stop" input of PID controller 39 i , allowing its inclusion in the general control system for automatic load distribution between the TL UKPG.

[0122] If all TLs have exhausted their capabilities to comply with the individual complex condition for the normal conduct of the technological process, the APCS 8 generates a message to the plant operator about the impossibility of maintaining the specified value of the density of the oil and gas complex at the gas treatment plant and the need to change its operating mode.

[0123] This method of managing the performance of the NGK preparation unit allows distributing the load between the TL taking into account the condition of their equipment, as well as the density of the NGK depending on the value of the current refrigeration capacity of the AVO 4 i , monitor the level of NGC in the RZh 5 i , which, in turn, leads to the production of NGK and dry gas with more stable quality characteristics and reduces the likelihood of emergency situations at the gas treatment plant.

[0124] The adjustment of the PID controllers used is carried out by the maintenance personnel at the moment of starting the system for a specific operating mode of the installation according to the method described, for example, in the “Encyclopedia of APCS”, clause 5.5, PID controller, resource:

[0125] http: / / www.bookasutp.ru / Chapter5_5.aspx#HandTuning.

[0126] A method for automatically distributing the load between low-temperature separation process lines with air-cooled units at integrated gas treatment units during peak gas production loads has been implemented at Gazprom PJSC and Gazprom Dobycha Yamburg LLC at the Zapolyarnoye oil, gas, and condensate field at UKPG 1V and UKPG 2V. Operational results have demonstrated its high efficiency. The claimed invention can be widely used at other operating and newly developed gas condensate fields in northern Russia.

[0127] The use of this method allows the gas treatment plant to provide a specified volume of dry gas preparation and obtain NGK with the required quality characteristics from natural gas at all stages of the NGKM operation, while adhering to the standards and limitations of the plant's process regulations. Moreover, all specified product characteristics supplied to consumers are achieved while simultaneously taking into account the actual condition of the equipment at each process line of the CGTU.

Claims

1. A method for automatically distributing the load between process lines (PL) of low-temperature separation with air cooling units (ACU) at integrated gas treatment plants (IGTP) during peak gas production loads, including monitoring of the flow rate of dried gas by means of the automated process control system (APCS) of the IGTP , entering the main gas pipeline (MGP), the flow rate of unstable gas condensate (NGC) , entering the main condensate pipeline (MCP), automatic maintenance of the gas separation temperature in the low-temperature separator of each TL at a given value of gas flow through it by changing the degree of gas throttling at the nozzle located in front of this separator, and fulfilling the task of the gas production enterprise (GPE) dispatcher for the volume of preparation of dried gas , which is entered as a setpoint in the database (DB) of the automated process control system, which implements the plan for the production of dry gas, monitoring the observance of equality using proportional-integral-differentiative (PID) controllers for maintaining the flow rate of dried gas, each of which controls the flow rate of the gas condensate mixture according to its own TL, to the input of the SP task of which the automated process control system sends a setpoint signal , and the actual flow rate of dried gas is sent to the PV feedback input of these PID controllers of the APCS by the gas condensate treatment plant, comparing which each PID controller generates a control signal at its CV output - the value of the gas condensate mixture flow rate for its TL, at which the total contribution of all TL will ensure the specified planned volume of dry gas preparation according to the UKPG, and also simultaneously a signal of the proportionality coefficient value is fed to the Kp input of the PID controller of each TL , which determines the degree of contribution of the given i-th TL, where i is the TL number, to the process of maintaining a given volume of dried gas preparation at the gas treatment plant in real time by setting the degree of influence of this PID controller on the controlled by it valve-regulator (VR) of the gas condensate mixture flow rate at its TL, located in front of the low-temperature separator, while the value of the proportionality coefficient is determined for each TL by its proportionality coefficient calculation unit, characterized in that the automated process control system of the gas treatment plant implements the adjusted planned task for the preparation of dry gas at moments of peak load for its consumption, automatically maintains the density of the NGK prepared by each TL individually, achieving its compliance with the task - the density setpoint The NGK for the UKPG, by controlling the temperature in the low-temperature separator of the TL, which must be maintained in it to achieve the specified density of the NGK, which it implements with the help of a cascade of two PID controllers and an AVO, controlled by its automatic control system (ACS) of this TL, and for this, a setpoint signal is sent to the input of the SP task of the first of the PID controllers of the ACS TP , common to all TL, and to its feedback input PV it supplies an individual signal of the density value of the NGC , recorded by the density sensor of the NGK coming from the three-phase liquid separator (LS), the i-th TL in the MCP, and as a result of processing these signals, the first PID controller of the cascade generates a setpoint value at its CV output - setting the temperature that must be maintained in the low-temperature separator to achieve the specified density of the NGK, and this signal is sent to the input of the SP setting of the second PID controller of the temperature maintenance cascade in the low-temperature separator of the i-th TL, and at this time the actual temperature value signal is sent to its feedback input PV in the low-temperature separator, recorded by the temperature sensor in the low-temperature separator of the i-th TL, and as a result of processing these signals, the second PID controller at its output CV generates a signal for changing the degree of preliminary cooling of the gas-liquid mixture as it passes through the AVO, which is fed to the input of its ACS, which automatically selects the appropriate operating mode of the apparatus, providing the required preliminary cooling of the gas-liquid mixture passing through the AVO, and as a result, the system maintains the required temperature in the low-temperature separator of the i-th TL, and in each measurement cycle, the control unit for compliance of the process parameters with the established limits for the i-th TL checks the compliance of the actual values ​​of the process requirements: the level of NGK in RZh; actual consumption of dry gas ; temperatures in the low-temperature separator of the i-th TL, and this control unit carries out the specified check by assessing the compliance of the controlled parameters with the specified limits, using for this the following inequalities, which represent a complex individual condition for the normal conduct of the technological process of the i-th TL: Where And - settings for the minimum and maximum values ​​of the oil and gas level in the RZh, respectively; And - settings of the minimum and maximum flow rate of dried gas of the i-th TL, respectively; And - the minimum and maximum temperature settings in the low-temperature separator of the i-th TL, respectively, and the values ​​of these settings are set by the operating personnel based on the passport data provided by the manufacturer of this equipment, as well as the requirements of the process regulations for this installation, and if, as a result of checking the condition for the normal conduct of the technological process, the i-th control unit establishes that it is observed in this measurement cycle simultaneously for all the inequalities that make it up, then at its output O it generates a logical “zero” signal, which is then fed to the start / stop input of the PID controller that controls the volume of preparation of dried gas at the i-th TL, allowing it to control the KR flow rate of the gas condensate mixture through it, but if during the technological process at least one of the values , And If the i-th TL in the next measurement cycle reaches its set limit value or goes beyond the specified boundaries, then this control unit generates a logical "one" signal at its output O, and this signal is fed to the "start\stop" input of the PID controller that controls the volume of dry gas preparation at the i-th TL, and as soon as this PID controller receives this signal, it suspends its operation, storing at its CV output the previous value of the control signal, which was calculated in the previous calculation cycle, as a result of which this i-th TL is excluded from the control process, but it continues to function with the process parameters recorded at the time of its exclusion from the control process, and during the removal of the i-th TL from the control process, all changes in the gas drying load are automatically distributed between the operating TL,the technological operating parameters of which correspond to their individual condition of normal technological process management, and this mode of their operation continues until the maintenance personnel eliminate the cause of the disruption of the technological process that caused the withdrawal of the i-th TL from the control process, and as soon as compliance with the complex condition of normal technological process management for the i-th TL is restored, its control unit sets a logical "zero" signal at its output O, which feeds into the "start / stop" input of the PID controller that controls the volume of dry gas preparation at the i-th TL, allowing its inclusion in the general control system of automatic load distribution between the TL of the UKPG.

2. The method according to paragraph 1, characterized in that the value of the proportionality coefficient calculates an individual block for calculating the proportionality coefficient for the PID controller that controls the volume of dry gas preparation at the i-th TL, using the following formulas: - if the productivity of the TL needs to be increased, i.e. , then the value he calculates using the formula - and if the productivity of the TL needs to be reduced, i.e. , then the value he calculates using the formula Where - the current value of the oil and gas level in the RZh of the i-th TL, controlled by the level sensor, the signal of which is fed to the input I2 of the proportionality coefficient calculation block for the PID controller of the i-th TL; And - the minimum and maximum levels of the NGK in the RP of the i-th TL are set according to the RP passport, and their signals are fed to the inputs I1 and I3 of the proportionality coefficient calculation block for the PID controller of the i-th TL, respectively; And - the settings of the minimum and maximum values ​​of the proportionality coefficient for the PID controller of the i-th TL, which are assigned based on the state of the process equipment of this TL taking into account the technological standards and limitations provided for by the technological regulations of the installation, and their signals are fed to the inputs I4 and I5 of the block for calculating the proportionality coefficient for the PID controller of this line, respectively, and all the specified settings for all TL are entered by the maintenance personnel into the DB of the automated process control system of the gas treatment plant before putting the installation into operation, and during operation all calculations according to the given formulas, they are limited by the following condition:

3. The method according to paragraph 1, characterized in that the automated process control system generates a message to the plant operator about the impossibility of maintaining the specified values ​​of the flow rate and density of the NGK at the gas treatment plant and the need to change its operating mode if all the TL of the plant have exhausted their capabilities to comply with their individual conditions for the normal conduct of the technological process.

4. The method according to paragraph 1, characterized in that, during the peak load of dry gas consumption, its supply to the MGP is set by adjusting the planned target of the UKPG for the preparation of dry gas. , and the resulting excess of NGK preparation is sent to the NGK reservoir farms of the GDP and / or the NGK processing complex with subsequent adjustment of the NGK supply plan to consumers under the MCP.

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