Method for automatic load distribution between low-temperature separation process lines with turbo-expander units at complex gas treatment plants 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 loads for gas production at oil and gas condensate fields (OGCF) in the North of the Russian Federation, implementing automatic load distribution between process lines (PL) for low-temperature gas separation with turbo-expander units (TEU), with simultaneous maintenance of the level of unstable gas condensate (UGC) in three-phase liquid separators (LS), its density and flow control when feeding into the main condensate pipeline (MCP), as well as control of the flow of dried gas at the CGTU. The purpose of the invention is to ensure automatic load distribution between the PL with the TEU during peak loads for gas production at the CGTU, maintaining the filling level of the OGC in the LS within the required limits, controlling its density and flow rate taking into account the state of the equipment involved in the process of preparing natural gas for long-distance transportation, while observing the standards and restrictions stipulated by the process regulations of the installation for various modes of its operation. The claimed method allows, at the CGTU, during peak loads of dry gas consumption by consumers, to ensure automatic load distribution between the PL with the TEU and the preparation of OGC from natural gas at all stages of the OGCF operation.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 loads for gas production at oil and gas condensate fields (OGCF) in the North of the Russian Federation, implementing automatic load distribution between process lines (PL) for low-temperature gas separation with turbo-expander units (TEU), with simultaneous maintenance of the level of unstable gas condensate (UGC) in three-phase liquid separators, hereinafter referred to as RL, its density and flow control when feeding into the main condensate pipeline (MCP), as well as control of the flow of dried gas at the IGTU.

[0002] A method for automatic control of gas preparation at a TL for long-distance transport is known, which allows for automatic maintenance of the gas separation temperature in a low-temperature separator at a given gas flow rate by using a TDA [see p. 312, Bekirov T.M., Lanchakov G.A. Gas and condensate processing technology. Moscow: OOO Nedra-Business Center. 1999. - 596 p.].

[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 level of the natural gas filling 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.

[0004] The closest in technical essence to the claimed invention is a method for automatic load distribution between low-temperature gas separation TLs from a TDA at a gas treatment plant in the north of the Russian Federation [RU Patent No. 2743690], including monitoring a number of parameters by means of the automated process control system (APCS) of the gas treatment plant. Among them are the flow rate of dried gas entering the main gas pipeline (MGP) and the flow rate of NGK entering the MCP. The APCS maintains the gas separation temperature in the low-temperature separator of each TL and controls their operating mode by varying the degree of adiabatic expansion of the gas with the performance of external mechanical work in the TDA located before each low-temperature separator. Having received a task for the NGK flow rate of the GTP, the APCS executes it using a proportional-integral-differentiative (PID) controller to maintain the NGK flow rate in the MCP.The APCS receives the NGK preparation task signal, entered into its database (DB) by maintenance personnel at the dispatcher's direction, to the SP input of this PID controller. Simultaneously, it receives the current NGK flow rate signal in the MCP to its PV feedback input. By comparing the task and the current NGK flow rate, this PID controller generates a task signal at its CV output, which is sent to the SP input of the PID controllers of all gas pipelines. Simultaneously, the APCS receives the actual flow rate of dry gas in the gas treatment plant to the PV feedback input of these PID controllers. A signal representing the proportionality coefficient K value is also simultaneously sent to the Kr input of the PID controller of each pipeline. п_i (where i is the TL line number), which determines the degree of influence of this PID controller on the controlled gas-liquid mixture flow control valve (RV) along its TL, installed after the first-stage separator. In this case, the value of the proportionality coefficient K п_iis determined individually for each TL by its proportionality coefficient calculation unit depending on the rotation speed of the TDA rotor, recorded by the APCS using the rotor speed sensor.

[0005] A significant disadvantage 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 maintaining the density of the NGK in the TL is carried out practically “blindly”, without precise process control, which reduces the quality of the NGK supplied to consumers, and there is no control over the level of filling it with RZ, which is a potential source of emergency situations or malfunctions in the operation of the UKPG, which can occur both when it is overfilled and when it is underfilled.

[0006] According to the technological process of collecting and preparing natural gas for long-distance transportation, natural gas from the production well clusters enters the UKPG - the switching valve building, from where it is distributed through a common raw gas manifold 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 the production and preparation of oil and gas: a textbook for universities. - M .: OOO Nedra-Business Center, 2008. - 399 p.]. For example, at the Zapolyarnoye OGCF, UKPG-V and UKPG-2V use four gas TL.

[0007] During operation, for various reasons, such as sudden water discharges and / or sand production in wells during natural gas production, equipment corrosion, etc., the condition of gas pipeline equipment changes, including deterioration of separator performance, which degrades their separation properties. This increases the carryover of liquid droplets and mechanical impurities, leading to a decrease in the efficiency of recuperative heat exchangers (RHEs) due to contamination of the surface of their heat exchange tubes. The formation of hydrate and other deposits in gas treatment units (GTUs) leads to changes in the pressure drop across them, which ultimately impacts their efficiency, i.e., the quality of the recovered natural gas, particularly its density.

[0008] Clearly, the condition of the gas pipeline equipment at the gas treatment plant (GTP) varies unevenly. Therefore, the actual performance status of all gas pipeline equipment will differ. Consequently, to improve the efficiency of the natural gas preparation process for long-distance transportation, the load distribution between the GTP pipelines during real-time operation should be carried out taking into account the actual condition of each line's equipment. This significantly improves the quality of the natural gas and oil and gas condensate prepared 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 operating mode of the unit and, accordingly, to a change in the actual flow rate of gas condensate entering the buffer tank (BV). This may result in situations of overfilling or underfilling of the BV, which may lead to a stoppage of the technological process or to a failure of the gas treatment plant, or may cause gas locks and their accumulation in the BV. 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 TDA during peak loads for gas production at the UKPG with the maintenance of the filling level of the NGK in the RZh within the required limits, the control of its density and consumption 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 TDA during peak loads for gas production at the UKPG with the maintenance of the level of NGK in the RZh, the control of its consumption and density at the UKPG taking into account the state of the equipment involved in the process of preparing natural gas for long-distance transportation, 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 the TL with TDA during peak gas production loads at the gas processing plant (GPP) and maintains the required fill level of the NGK in the gas processing plant (GPP), controls its density, and controls the GPP flow rate, taking into account the equipment condition of each TL. This improves the quality of the NGK preparation supplied to consumers and prevents the formation of gas locks and their accumulation in the GPP, increasing the reliability of its operation and reducing the risk of complications and accidents that could lead to serious environmental, human, and material losses.

[0013] The specified 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 turboexpander units 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 and the consumption of the NGK , entering the low-temperature separator. The automated process control system automatically maintains the gas separation temperature in the low-temperature separator of each TL by varying the degree of adiabatic expansion of the gas with the implementation of external mechanical work in the TDA located before each low-temperature separator, and fulfilling the task of the gas production enterprise (GPE) dispatcher for the volume of dried gas preparation. , which is entered as a setpoint in the APCS database. The APCS also implements the dry gas production plan by monitoring the equality using PID controllers to maintain the flow rate of the dried gas. Each of these PID controllers controls the flow rate of the gas-liquid mixture according to its own TL, to the SP input of which the APCS 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 in the MGP. By comparing the values ​​of these signals, each PID controller generates a control signal at its CV output—the flow rate of the gas-liquid mixture along its TL, at which the total contribution of all TLs will ensure the specified planned volume of dry gas preparation. according to the UKPG. 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 i-th TL (i is the TL number) to the process of maintaining a specified volume of dried gas preparation at the gas treatment plant in real time. This is achieved by setting the degree of influence of this PID controller on the KR of the gas-liquid mixture flow rate controlled by it at its TL, located at the outlet of the first-stage separator. In this case, the value of the proportionality coefficient is determined for each TL by its proportionality coefficient calculation unit.

[0014] At moments of peak load for the consumption of dry gas, the automated process control system of the gas treatment plant implements the adjusted planned task for its preparation and 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 is maintained by the AGPP process control system, which maintains the NGK density by controlling the temperature in the low-temperature separator TL, which must be maintained to achieve the specified NGK density. Temperature control is achieved using a cascade of two PID controllers and a TDA. To achieve this, the AGPP process control system 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's RJ 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 condensate. The generated setpoint value in the form of a corresponding signal is sent to the SP input of the second PID controller of the temperature maintenance cascade in the low-temperature separator of the i-th TL. At this time, the actual temperature value signal is sent to its PV feedback input in the low-temperature separator, recorded by the temperature sensor in the low-temperature separator of the i-th TL. As a result of processing these signals, the second PID controller generates a speed reference signal at its CV output The TDA rotor. This task is implemented by the KR located at the TDA compressor outlet, which regulates the TDA rotor speed by changing the volume of dry gas passing through its compressor. This results in temperature control in the low-temperature separator, which is based on the condition , corresponding to the system maintaining 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; temperatures in the low-temperature separator of the i-th TL; speeds rotation of the i-th TL TDA rotor; dry gas flow rate The i-th TL. This control unit performs the specified 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 conduct 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;

[0018] And - minimum and maximum temperature settings in the low-temperature separator of the i-th TL, respectively;

[0019] And - settings for the minimum and maximum rotation speed of the i-th TL TDA rotor;

[0020] And - settings of the minimum and maximum flow rate of dried gas of the i-th TL, respectively.

[0021] The values ​​of these settings are set by the service personnel based on the passport data provided by the manufacturer of this equipment, as well as the requirements of the technological regulations for this installation.

[0022] If, as a result of checking the normal process conditions, the i-th control unit determines that they are met in a given measurement cycle simultaneously for all inequalities comprising it, it generates a logical "zero" signal at its output O. It feeds this signal to the start / stop input of the PID controller, which controls the dry gas preparation volume at the i-th TL, allowing it to control the KP of the gas condensate mixture flow rate.

[0023] But if during the technological process at least one of the values , , And When the i-th TL reaches its preset limit value or goes beyond its specified limits during the next measurement cycle, this control unit generates a logical "one" signal at its output O. It feeds this signal to the "start / stop" input of the PID controller, which controls the dry gas processing 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 of these actions, the i-th TL is excluded from the control process. However, it continues to operate with the process parameters recorded at the time of its exclusion from the control process.However, 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 process 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. As soon as the i-th TL's comprehensive normal process conditions are 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.

[0024] 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:

[0025] - if the performance of the TL needs to be increased, i.e. , then the value he calculates using the formula:

[0026]

[0027] - and if the TL performance needs to be reduced, i.e. , then the value he calculates using the formula:

[0028]

[0029] where - the actual 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;

[0030] 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;

[0031] And - settings of the minimum and maximum values ​​of the proportionality coefficient for the PID controller of the i-th TL.

[0032] Settings And They are assigned based on the state of the process equipment of this transmission line, taking into account the process standards and limitations stipulated by the installation's process regulations. The signals of their values ​​are fed to inputs I4 and I5 of the proportionality coefficient calculation unit for this line's PID controller, respectively.

[0033] Settings And , And For all TL, the operating personnel enters the data into the APCS database of the gas treatment plant before commissioning the plant. During operation, all calculations according to the given formulas, they are limited by the following condition:

[0034]

[0035] If all the TL units have exhausted their capabilities to comply with their individual conditions for the normal operation 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 of dry gas and NGK, as well as the density of NGK at the gas treatment plant and the need to change its operating mode.

[0036] From the moment of the peak load of dry gas consumption, the supply of dry gas to the MGP is set by adjusting the planned target for its preparation, and the resulting excess of NGK preparation is sent to the NGK tank farms of the GDP and / or the NGK processing complex with subsequent adjustment of the NGK supply plan to consumers under the MCP.

[0037] Fig. 1 shows the basic process diagram of the CGTP with TDA, and Fig. 2 shows the structural diagram of the automatic control of the load distribution between the TL with TDA and maintaining the required limits of the level of NGK in the RZ, controlling its density and consumption at the CGTP.

[0038] The following notations are used in Fig. 1:

[0039] 1 - raw gas collector;

[0040] 2 - collector of aqueous inhibitor solution (AIC);

[0041] 3 i - separator of the first stage of separation of the i-th TL, i = 1, 2, …, n, where n is the number of TL at the gas treatment plant;

[0042] 4 i - KR of the gas-liquid mixture flow rate of the i-th TL;

[0043] 5 i - RZ i-th TL;

[0044] 6 i - flow sensor of the i-th TL NGK with density measurement function;

[0045] 7 i - oil level sensor in the i-th TL;

[0046] 8 - industrial control system of the gas treatment plant;

[0047] 9 i - TO "gas-gas" i-th TL;

[0048] 10 i - TO "gas condensate" i-th TL;

[0049] 11 - collector of weathered gases;

[0050] 12 i - intermediate separator of the i-th TL separation;

[0051] 13 i - TDA i-th TL;

[0052] 14 i - rotor speed sensor of the i-th TL TDA;

[0053] 15 i - low-temperature separator of the i-th TL;

[0054] 16 i - dry gas flow sensor of the i-th TL;

[0055] 17 i - temperature sensor in the low-temperature separator of the i-th TL;

[0056] 18 i - KR for maintaining the rotation speed of the rotor of the i-th TL TDA;

[0057] 19 - IGP;

[0058] 20 - Manual transmission.

[0059] For simplicity, Fig. 1 shows the connections of sensors and the control system with the APCS only for the 1st TL.

[0060] The following notations are used in Fig. 2:

[0061] 21 i - actual temperature signal in low-temperature separator 15 i ;

[0062] 22 i - signal of actual density of oil and gas at the output of RZh 5 i i-th TL (comes from sensor 6 i );

[0063] 23 - setpoint signal - the specified density of the oil and gas complex at the gas treatment plant (received from the database of the automated process control system of the gas treatment plant to the input of the SP task of all PID controllers 24);

[0064] 24 i - PID controller for maintaining the density of the oil and gas complex according to the i-th TL;

[0065] 25 i - PID controller for maintaining temperature in the low-temperature separator 15 i ;

[0066] 26 i - signal for setting the cooling capacity of TDA 13 i i-th TL;

[0067] 27 i - setpoint signal - minimum level of NGC in RZh 5 i ;

[0068] 28 i - signal of the actual level of the oil and gas in RZh 5 i (comes from sensor 7 i );

[0069] 29 i - setpoint signal - the maximum level of NGC in the RZh 5 i ;

[0070] 30 i - setpoint signal - minimum temperature in the low-temperature separator 15 i i-th TL;

[0071] 31 i - setpoint signal - maximum temperature in the low-temperature separator 15 i i-th TL;

[0072] 32 i - setpoint signal - minimum rotor speed of TDA 13 i i-th TL;

[0073] 33 i - actual speed signal rotation of the TDA 13 rotor i i-th TL (comes from sensor 14 i );

[0074] 34 i - setpoint signal - maximum rotor speed of TDA 13 i i-th TL;

[0075] 35 i - setpoint signal - minimum flow rate of dried gas of the i-th TL;

[0076] 36 i - actual consumption signal dried gas of the i-th TL (comes from sensor 16 i );

[0077] 37 i - setpoint signal - maximum flow rate of dried gas of the i-th TL;

[0078] 38 i - a block for monitoring the compliance of the technological process parameters of the i-th TL with the limits established for them;

[0079] 39 - setpoint signal - plan for the preparation of dry gas at the gas treatment plant (received from the database of the automated process control system of the gas treatment plant, set by the gas treatment plant dispatcher);

[0080] 40 - actual consumption signal dried gas at the gas processing plant (value ACS TP 8 determines by summing the readings of sensors 16 i );

[0081] 41 i - setpoint signal - minimum value of the proportionality coefficient of the PID controller 44 i i-th TL;

[0082] 42 i - setpoint signal - maximum value of the proportionality coefficient of the PID controller 44 i i-th TL;

[0083] 43 i - block for calculating the proportionality coefficient of the PID controller 44 i i-th TL;

[0084] 44 i- PID controller for maintaining the flow rate of dried gas of the i-th TL;

[0085] 45 i - control signal KR 4 i flow rate of the gas-liquid mixture of the i-th TL.

[0086] The process of preparing natural gas for long-distance transportation at the TL shown in Fig. 1 includes:

[0087] - primary separation of natural gas in the inlet separator 3 i ;

[0088] - cooling the inlet flow of gas-liquid mixture in TO 9 i "gas-gas" with a flow of cooled gas and TO 10 i "gas-condensate" with a flow of cooled condensate mixture with VRI;

[0089] - intermediate separation of gas-liquid mixture in separator 12 i for its subsequent division;

[0090] - cooling of the gas-liquid mixture due to the operation of the TDA 13 i , in which adiabatic expansion of gas occurs in the turbine section with energy being transferred to the machine shaft to cool the gas-liquid mixture in its compressor section;

[0091] - final separation of the cooled gas-liquid mixture in a low-temperature separator 15 i .

[0092] PID controllers 241, …, 24 n , 251, …, 25 n , 441, …, 44 n , blocks 381, …, 38 n , 431, …, 43 n implemented on the basis of APCS 8.

[0093] The method for automatically distributing the load between low-temperature separation process lines with turboexpander units at integrated gas treatment plants during peak gas production loads is implemented as follows.

[0094] Natural gas from the production well clusters enters the building of the switching valves of the gas treatment plant, from where it is distributed between the TL through the raw gas collector 1 and fed to the first stage separator 3 i In it, the liquid phase (formation water with dissolved inhibitor and condensed hydrocarbon condensate) is separated, which enters the RZh 5 iThe separated gas-liquid mixture passes through the flow control valve 4 i , after which it is divided into two streams, which are sent to the first sections of TO 9 i "gas-gas" and TO 10 i "gas-condensate" for cold recovery from the gas flow and the mixture of VRI with NGK, removed from the intermediate separator 12 i and low-temperature separator 15 i To prevent hydrate formation in the gas-liquid mixture flow before maintenance 9 i "gas-gas" and TO 10 i A hydrate inhibitor is injected into the "gas-condensate" system (its supply line is not shown in Fig. 1). Then, the cooled gas-liquid mixture flows from the outlets of TO 9 i "gas-gas" and TO 10 i "gas-condensate" is combined and its total flow is 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 12 i the gas-liquid mixture is fed to the input of the turbine section of the TDA 13 i, equipped with a rotor speed sensor 14 i . Next, from the exit of TDA 13 i , the cooled gas-liquid mixture enters the low-temperature separator 15 i , where the mixture of condensed liquid hydrocarbons and VRI is finally separated from it.

[0095] The temperature reduction of the gas-liquid mixture in this process is achieved by adiabatic expansion of the gas flow in the TDA13 turbine i with the performance of external mechanical work. The expansion of the gas with the removal of energy leads to a significant decrease in its temperature, i.e., the generation of "cold."

[0096] Specified density The NGK is automatically maintained by regulating the separation of light hydrocarbon fractions from the gas condensate mixture. This regulation is accomplished by varying the temperature in the low-temperature separator 15. i , controlling the cooling capacity of the TDA 13 i, which is regulated by changing the rotation speed of its rotor. For this, the readings from temperature sensor 17 are used. i , which is installed in the low-temperature separator 15 i and sensor 14 i rotor speed of TDA 13 i i-th TL. Control and regulation of the rotor speed of TDA 13 i carried out using KR18 i .

[0097] Dried gas leaving low temperature separator 15 i , are directed through the second section of TO 9 i "gas-gas" in the TDA 13 compressor i , which compresses this gas and feeds it through the KR 18 i in MGP 19 through a pipeline equipped with a gas flow sensor 16 i .

[0098] Outgoing from the intermediate separator 12 i and low-temperature separator 15 i the mixture of NGK with VRI passes through the second section of the heat exchanger TO 10 i "gas condensate." It is then mixed with the liquid phase, which is removed from separator 3i , and enters the Russian Federation 5 i equipped with a NGK 7 level sensor i .

[0099] NGK flow from RZh 5 i is discharged through a pipeline equipped with a Coriolis flow meter 6 i with the function of measuring the density of the oil and gas and fed to the MKP 20 for transportation to consumers.

[0100] In the process of working in RZh 5 i a weathered gas is formed, which is fed through a pipeline to the weathered gas collector 11, from where it is used for internal needs and / or sent for compression with subsequent injection into the MGP 19, or for disposal.

[0101] The VRI discharged from the lower part of the 5th stage of the 5th stage of the 2nd ...

[0102] Peak gas production loads occur, for example, due to the onset of severe cold weather, especially in winter. Therefore, during this period, the Valanginian gas treatment plants typically maintain an upwardly adjusted planned target for the preparation of dry gas supplied to consumers, which is accomplished as follows.

[0103] The GDP dispatcher sets the adjusted upward volume of dry gas preparation for the gas treatment plant using the setpoint , the value of which the maintenance personnel enters into the APCS 8 database. It sends a signal of this setting 39 to the SP input of PID controllers 44 of all TL. At the same time, the APCS 8 sends a common signal 40 - the value of the actual flow rate of the dried gas - to the PV feedback input of these PID controllers. according to the UKPG, which it determines by summing up the readings of 16 sensors i consumption of dried gas for all TL.

[0104] PID controllers 44 continuously monitor the difference in values ​​between the plan preparation of dry gas at the gas processing plant and its actual value - total flow rate of dried gas for all TL, recorded by 6 sensors i If the comparison reveals that:

[0105] ,

[0106] then at the output of PID controllers 44, control signals will be generated to increase the passage of the gas-liquid mixture through the gas treatment plant, and if:

[0107] ,

[0108] The opposite is true: the output of PID controllers 44 will generate control signals to reduce the flow of gas-liquid mixture through the gas-liquid treatment plant. As a result, the flow rate of dry gas through the gas-liquid treatment plant will be increased in the first case, or decreased in the second case, by all PID controllers 44 controlling the KR 4 ​​until the gas-liquid treatment plant's capacity reaches the planned target. for the preparation of dried gas, i.e. until the following condition is met:

[0109] .

[0110] 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 44 i signal 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 43 i according to the following formulas:

[0111] if the performance of the TL needs to be increased, i.e. , That:

[0112]

[0113] - if the TL performance needs to be reduced, i.e. , That:

[0114]

[0115] where - current value of the level of NGC in RZh 5 i ; , - settings for the minimum and maximum levels of NGK in RZh 5 i , respectively; , - settings of the minimum and maximum values ​​of the proportionality coefficient, respectively, of the PID controller 44 i The values ​​of these settings are entered into the APCS 8 database by the UKPG maintenance personnel, taking into account the state of the process equipment of each TL at the time of plant startup and the requirements of technological standards and restrictions stipulated by the technological regulations of the plant.

[0116] Calculation according to formulas (1) and (2) is limited by the condition:

[0117]

[0118] When the dry gas capacity of the gas treatment plant needs to be increased, the TLs with a higher refrigeration capacity reserve, i.e., those with the ability to increase the refrigeration capacity of the TDA, will be used first. Conversely, when the dry gas capacity of the gas treatment plant decreases, attention will be given to unloading the TLs operating at or near maximum capacity, i.e., those with a high reserve for reducing the refrigeration capacity of the TDA.

[0119] Automatic maintenance of the set density of NGK for each TL, the ACS TP 8 implements it as follows.

[0120] The maintenance personnel enters the set value of the NGK density in the APCS DB of the integrated gas treatment plant, from where it is sent in the form of signal 23 to the input of the SP task of all PID controllers 24 for maintaining the density of the oil and gas complex in the liquid phase 5 of all the TL. At the same time, an individual signal 22 is sent to the PV feedback input of each of these PID controllers i - the value of the density of the NGC , measured by sensor 6 i , controlling the density of the NGK at the outlet of the RZh 5 i As a result of their processing, the PID controller 24 i generates the current temperature setpoint value at its CV output , which must be maintained in the separator 15 i low-temperature gas separation to achieve a given density of the NGK corresponding to the condition . Then this signal goes to the SP input of the PID controller 25 i , and signal 21 is fed to its PV feedback input i - actual temperature value in low-temperature separator 15 i , coming from sensor 17 i . As a result of processing these signals, the PID controller 25 i generates a CV signal 26 at its output i speed control TDA 13 rotor i This signal is 26. i arrives at KR 18 i , regulating the rotor speed of the TDA13i by changing the volume of dried gas passing through its compressor, and, consequently, controlling the temperature in the separator 15 i , seeking to fulfill the condition .

[0121] Block 38 i in each measurement cycle, it checks the compliance of the actual values ​​of the following parameters with the complex individual condition of normal conduct of the technological process of the i-th TL: the level of the NGC in RZh 5 i (signal 28 i ); temperatures in the low-temperature separator (signal 21 i ); speeds rotation of the TDA 13 rotor i (signal 33 i ); consumption of dried gas (signal 36 i ). This check block 38 i is carried out using the following inequalities:

[0122]

[0123] where - setting - minimum value of the NGK level in the RZh 5 i i-th TL;

[0124] - setting - maximum value of the NGK level in the RZh 5 i i-th TL;

[0125] - setpoint - minimum temperature in the low-temperature separator of the i-th TL;

[0126] - setpoint - maximum temperature in the low-temperature separator of the i-th TL.

[0127] - setting - minimum rotor speed of TDA 13 i i-th TL;

[0128] - setpoint - maximum rotor speed of TDA 13 i i-th TL.

[0129] - setpoint - minimum flow rate of dried gas for the i-th TL;

[0130] - setpoint - maximum flow rate of dried gas for the i-th TL;

[0131] Setting values , , , , , 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.

[0132] If, as a result of checking the normal process conditions, control unit 38 i If the unit determines that it is observed in a given measurement cycle simultaneously for all the inequalities that comprise it, it generates a logical "zero" signal at its output O. The unit then feeds this signal to the "start / stop" input of PID controller 46. i , which controls the volume of preparation of dried gas at the i-th TL, allowing it to control its own KR of the gas-liquid mixture flow rate through it.

[0133] But if during the technological process at least one of the values , , or 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 38 i generates a logical “one” signal at its output O, which is fed to the start / stop input of the PID controller 44 i, which controls the volume of dry gas preparation at the i-th TL. Having received this signal, PID controller 44 i suspends its operation, leaving at its CV output the value of the control signal calculated in the previous calculation cycle.

[0134] At the same time, when such a situation arises, the APCS 8 generates a message to the plant operator about the situation 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 of its exclusion from the control process.

[0135] When the i-th TL is removed from the control process due to a violation, all changes in the gas dehydration load will be automatically distributed among the TLs whose operating parameters correspond to their individual normal process conditions. This operating mode will continue until maintenance personnel eliminate the cause of the process violation that caused the i-th TL to be removed from the control process.

[0136] 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 38 i sets a logical "zero" signal at its output O, which is fed to the "start / stop" input of PID controller 44 i , allowing its inclusion in the general control system for automatic load distribution between the TL UKPG.

[0137] 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 NGK density and the need to change the operating mode of the gas treatment plant.

[0138] This method of managing the performance of the dry gas preparation plant and the NGK, during peak gas production loads, allows for the load to be distributed between the TL taking into account the condition of their equipment, as well as automatically maintaining the density of the NGK depending on the value of the current refrigeration capacity of the TDA 15 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.

[0139] 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:

[0140] http: / / www.bookasutp.ru / Chapter5_5.aspx#HandTiming.

[0141] A method for automatically distributing the load between low-temperature separation process lines with turboexpander 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 the Russian Federation.

[0142] Using this method ensures the specified degree of oil and gas condensate extraction from natural gas at the oil and gas condensate processing plant (OGCP) during peak gas production loads and during the constant, declining, and final stages of operation, while adhering to the standards and limitations on process parameters stipulated by the plant's process regulations. At the same time, the specified quality of natural gas and gas condensate treatment for long-distance transportation is ensured by taking into account the actual condition of the OGCP equipment and reduces the likelihood of emergency situations at the facility.

Claims

1. A method for automatically distributing the load between process lines (PL) of low-temperature separation with turboexpander units (TEU) 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 by changing the degree of adiabatic expansion of the gas with the performance of external mechanical work in the TDA, located in front of each low-temperature separator, and the fulfillment of 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, and the automated process control system 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-liquid 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 in the MGP, by comparing which each PID controller generates a control signal at its CV output - the value of the gas-liquid mixture flow rate along 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 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-liquid mixture flow rate according to its TL, located at the outlet of the first stage 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 TL, which must be maintained in it to achieve the specified density of the NGK, which it implements using a cascade of two PID controllers and a TDA, and for this, a setpoint signal is sent to the input of the SP task of the first of the PID controllers of the APCS , 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 NGK, coming from the three-phase liquid separators (RL) of 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 i-th TL, and at this time the signal of the actual temperature value is sent to its feedback input PV in the low-temperature separator, recorded by the temperature sensor in the low-temperature separator i-th TL, and as a result of processing these signals, the second PID controller at its CV output generates a signal to change the rotation speed the TDA rotor, which is implemented by the KR located at the outlet of the TDA compressor, which regulates the rotation speed of the TDA rotor by changing the volume of dried gas passing through its compressor and, consequently, controls the temperature in the low-temperature separator, ensuring that the condition is met , corresponding to the system's support of the required temperature in the low-temperature separator 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 ​​with the requirements of the process: the level of NGK in RZh; temperatures in the low-temperature separator TL; speeds rotation of the rotor of the TDAi-th TL; flow rate of dried gas i-th TL, and this control block 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 – minimum and maximum temperature settings in the low-temperature separator of the TL, respectively; And – settings for the minimum and maximum rotation speed of the rotor of the i-th TL TDA; And – the minimum and maximum flow rate settings of the dried gas 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 conditions 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 the dried gas of the i-th TL, allowing it to control the KP flow rate of the gas condensate mixture along 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 for 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 conditions 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 i-th TL to be removed 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 the start / stop input of the PID controller that controls the volume of dry gas preparation for 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 actual value of the oil and gas level in 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 i-th TL are set according to the TL passport, and their signals are fed to the inputs I1 and I3 of the proportionality coefficient calculation unit 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 of dried gas and NGK, as well as the density of 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, the supply of dry gas to the MGP is set by adjusting the planned target for its preparation, and the resulting excess of NGK preparation is sent to the NGK tank 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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