UA59178A - Method for controlling pressure when supplying gas to customers with the possibility to limit the gas flow rate - Google Patents

Abstract

The proposed method for controlling pressure when supplying gas to customers with the possibility to limit the gas flow rate is distinctive by that a single actuator is used for controlling gas pressure and limiting gas flow rate. The pressure at the inlet of the actuator would be constant if the gas flow rate is below the specified value, and would be decreased linearly up to the minimal allowable value if the gas flow rate increases. The gas pressure can be set according to a daily or season schedule. When the gas pressure is equal to the minimal allowable value, the gas supply would be terminated. The present invention provides the possibility to enhance the quality in controlling gas pressure and provide reliable operation of the process equipment of customers.

Description

Description of the invention

The invention relates to the regulation and management of the supply of natural gas to consumers. Method 2 can be used to limit gas consumption to that provided by gas supply contracts.

Control and regulation of gas consumption is an urgent task in connection with the low discipline of calculations for consumed gas. Maintaining gas pressure at a constant level at which the consumer's equipment is designed is important for the operation of technological equipment. When the gas pressure decreases, the equipment begins to work in unexpected modes, less efficiently, with increased emissions of harmful substances, etc. When the gas pressure drops below a certain value, emergency situations will occur, for example, extinguishing (disruption) of the flame in the burners, filling furnaces and rooms with an explosive mixture of gas and air and the subsequent ignition of this mixture when re-igniting is attempted or for other reasons.

Thus, the main task of the gas supplier is to maintain the gas pressure at the level determined by the gas supply contract (hereinafter, the contract pressure) and to prevent the gas pressure from falling below the permissible level for safe operation (minimum safe pressure).

A well-known and widespread method of regulating gas pressure using automatic pressure regulators that maintain a constant pressure "after itself" (see Kyazimov K.G., Gusev V.E. Operation and repair of gas supply systems. Kyiv, 1999, p. 75- 93). The contract gas pressure task is performed in these regulators manually by changing the spring force.

The closest to the proposed method is the method of regulating the flow rate and pressure when supplying gas to consumers, described in the patent of the Russian Federation Mo2176100, IPC" p05016/00, 27/00, date of publication of the application 2001.11.20. According to this method of regulating the pressure when supplying gas to consumers with the possibility limitation of flow in the consumer pipeline is carried out by one executive mechanism, which receives, through the selection selector, a control signal generated by the pressure regulator when the gas flow rate is below the set value, 79 or generated by the flow regulator when the gas flow rate is above the set value.

The disadvantage of this method is that when the gas consumption exceeds the contractual one, only the flow regulation is performed, while the pressure may fall below the minimum safe level, resulting in the danger of accidents. In addition, when the consumption is limited, sharp fluctuations in pressure are possible, which negatively affects the operation of the technological equipment of gas consumers. со 3о The invention is based on the task of improving the quality of regulation and the safety of the operation of the consumer's technological equipment by changing the parameters of the method and introducing new operations. --

The problem is solved by the fact that in the method of pressure regulation when supplying gas to consumers with the possibility of limiting the consumption, which includes one executive mechanism, according to the invention, the pressure at the output of the executive mechanism is maintained equal to the specified value, when the gas consumption is below the specified value, then, with an increase in flow, the pressure is linearly reduced to the value of the minimum safe pressure.

The first additional significant feature is that the pressure value at the output of the actuator is set by a smoothly changing function. " and The second additional significant feature is that the value of the specified gas flow rate can be variable, for example, a daily schedule. c The third additional significant feature is that in the scheme of the gas tract, in front of the executive mechanism "z" of pressure regulation, a cut-off executive mechanism is included, which cuts off the gas supply when the minimum safe pressure is reached.

The fourth additional significant feature is that, in addition to pressure and flow, gas temperature is also measured, and with 15, gas flow is corrected for temperature and pressure.

Figure 1 shows a diagram explaining the proposed method. The main elements of the scheme are the primary (Ce) pressure transducers 1 and flow rate 2, the computing element C and the executive mechanism 4. - Fig. 2 shows an example of a linear graph of the relationship between pressure and flow, which can be implemented in the proposed method. - And 50 Fig. 3 shows an example of a graph with a smooth change in the pressure-flow ratio, which can be implemented in the proposed method.

The scheme explaining the essence of the method is shown in Fig. 1. The scheme includes primary pressure 1 and flow 2 converters, the signals from which are sent to the computing element 3, which performs the operations of comparing the measured values of pressure and flow with the specified ones (Runtr; OScontr), as well as with the value of the minimum safe pressure (P min bez), calculates the necessary regulatory influence and issues a control signal to the executive mechanism 4. c. If the gas consumption is less than the specified (contractual) one, then the computing element C with the help of executive mechanism 4 maintains the gas pressure at the level of the specified (contractual) pressure. If the gas consumption is greater than the contractual one, then the computing element C with the help of executive mechanism 4 linearly reduces the gas pressure, limiting further uncontrolled growth of gas consumption. A decrease in pressure has a negative effect on the consumer's 60 technological equipment and is a warning about overtime gas consumption. Pressure reduction is possible only to the value of the minimum safe pressure to prevent the occurrence of emergency situations.

The value of the pressure maintained at the outlet can be determined by computing element 4 according to the following equations:

At b"Skontr RR kontr" KO (O-Skontr)

If the calculated ReP umin without; It is accepted RR min without.

Where: o - measured gas consumption;

P - pressure maintained at the output of the executive mechanism;

K - slope coefficient of direct adjustment.

The graph of the pressure change when the gas flow rate changes for the above equations is shown in Fig. 2. On modern computing elements, it is easy to implement a smooth decrease in pressure, an example of which is shown in Fig.3. In addition, pressure reduction can begin already when the consumption approaches the contractual value, thus reducing overtime consumption.

Gas consumption is characterized by seasonal and daily irregularities. For more optimal use of gas pipeline capacity, it is possible to set the contract cost as a function of time or other parameters.

At the dead-end branches of the gas pipeline with one consumer, upon reaching the minimum safe pressure and in the absence of payment for the consumed gas, it is possible to completely stop the supply of gas with the following procedure of connecting the gas with purging the gas pipeline and other necessary operations, when the relationship between the supplier and the gas consumer will be settled. For this, in the proposed method, it is necessary to introduce another executive mechanism 5 to reliably shut off the gas supply.

Since the values of pressure and gas flow are input to the calculating element Z, when an additional element - a temperature converter - is introduced, it would be possible to adjust the gas flow according to temperature and pressure, which will make it possible to get rid of the influence of these factors on the density and, accordingly, gas flow.

Claims (5)

Formula of the invention 25 " 1. The method of pressure regulation when supplying gas to consumers with the possibility of limiting the flow, which includes one executive mechanism, which is characterized by the fact that the pressure at the output of the executive mechanism is maintained equal to the specified value when the gas flow is below the specified value, then, when the flow rate increases, the pressure is linearly reduced to the value of the minimum safe pressure. 2. The method of pressure regulation during the supply of gas to consumers with the possibility of limiting consumption according to claim 1, which differs in that the pressure value at the output of the executive mechanism is set by a function that changes smoothly. C. The method of pressure regulation when supplying gas to consumers with the possibility of limiting the consumption according to claim 1, (o) 35, which differs in that the value of the specified gas consumption can be variable, for example, according to a daily schedule. 4. The method of pressure regulation when supplying gas to consumers with the possibility of limiting consumption according to claim 1, which differs in that the circuit of the gas tract in front of the executive mechanism of pressure regulation includes a cut-off executive mechanism that shuts off the gas supply when the minimum safe pressure is reached. " 5. The method of pressure regulation during the supply of gas to consumers with the possibility of limiting the consumption according to claim 1, which differs in that, in addition to the pressure and consumption, the temperature of the gas is also measured, and the gas consumption is corrected by temperature and pressure. . and? 1 se) - - and IR e) 60 b5