JP2018087651A - Gas combustion system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas combustion system capable of attaining the improvement of a turndown ratio.SOLUTION: Provided is a gas combustion system 1 comprising: a pressure detection part 11 detecting the pressure in one piping 21 through which a gas G is circulated; a plurality of gas combustion burners 12 provided at the downstream side of the pressure detection part 11 and combusting the gas G circulating through the piping 21; automatic selector valves 13 individually provided between each of a plurality of the gas combustion burners 12 and the pressure detection part 11 and switching whether the gas G circulating through the piping 21 shall be fed to the gas combustion burners 12 or not; and a selector valve control part 14 controlling the opening and closing of the automatic selector valve 13 in such a manner that the gas G is combusted with the gas combustion burners 12 by the number corresponding to the inner pipe pressure detected in the pressure detection part 11.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a gas combustion system for burning gas.

  Conventionally, a gas burner is known in which high-temperature combustion exhaust gas is used as combustion air, or a low calorific value gas can be used as combustion gas (for example, Patent Document 1). One such combustion gas is hydrogen. Since hydrogen has a wide explosion range, it is difficult to handle in combustion compared to other gases.

JP 56-64210 A

  It is relatively easy to mix combustion air and hydrogen immediately before combustion to form a diffusion flame, and a diffusion burner for hydrogen combustion has already been used. However, gas combustion burners for burning combustion gas, not limited to hydrogen, are required to efficiently burn combustion gas in order to effectively use the combustion gas.

  An object of the present invention is to provide a gas combustion system capable of improving the turndown ratio.

  In order to achieve the above object, a gas combustion system according to an aspect of the present invention includes a pressure detection unit that detects an in-pipe pressure of one pipe through which a gas flows, and the pipe provided downstream of the pressure detection unit. A plurality of gas combustion burners for burning the gas flowing through the gas, and supplying the gas flowing through the piping separately provided between each of the plurality of gas combustion burners and the pressure detection unit to the gas combustion burner A switching valve that switches whether or not to perform, and a switching valve control unit that controls opening and closing of the switching valve so that the gas is burned by the number of the gas combustion burners according to the pressure in the pipe detected by the pressure detection unit It is characterized by providing.

  According to one embodiment of the present invention, the turndown ratio can be improved.

It is a figure which shows schematic structure of the installation in which the gas combustion system 1 by one Embodiment of this invention is used. It is a block diagram showing a schematic structure of gas combustion system 1 by one embodiment of the present invention. It is a graph for demonstrating control of the automatic switching valve 13 and the gas combustion burner 12 with which the gas combustion system 1 by one Embodiment of this invention was equipped. FIG. 4A is a diagram for explaining a control simulation of the gas G in the PID control unit 16 provided in the gas combustion system 1 according to an embodiment of the present invention. FIG. 4B shows a simulation result with respect to the step increase of the gas G, and FIG. 4C shows a simulation result with respect to the repeated fluctuation of the gas G. It is a figure which shows schematic structure of the automatic switching valve 20 with which the gas combustion system by the modification of one Embodiment of this invention was equipped.

A gas combustion system according to an embodiment of the present invention will be described with reference to FIGS.
As shown in FIG. 1, a gas supply facility P2 that supplies gas to the boiler facility P1 is connected to the boiler facility P1 provided with the gas combustion system 1 according to the present embodiment. The gas supply facility P2 is, for example, a factory of a chemical manufacturer. The boiler facility P1 and the gas supply facility P2 are connected by a pipe 22. The gas G generated as a by-product in the gas supply facility P2 is supplied to the boiler facility P1 through the pipe 22. A plurality of other facilities (not shown) are connected to the pipe 22. A plurality of other facilities acquire and use the gas G supplied by the gas supply facility P2, as indicated by curved arrows in FIG. The supply amount of the gas G supplied by the gas supply facility P2 is kept constant. For this reason, since supply_amount | feed_rate of the gas G supplied to the boiler equipment P1 is fluctuate | varied according to the acquisition condition of the gas G of several other equipment, the in-pipe pressure of the piping 22 also fluctuates.

  The boiler equipment P1 is connected to the pipe 22 and the pipe 21 through which the gas G flows, the change rate limiter P11 that limits the change rate of the flow rate of the gas G flowing through the pipe 21, the gas combustion system 1 and the gas combustion amount And a combustion part P10 provided with a limiter 3. The rate-of-change limiter P11 limits the rate of change in the flow rate of the gas G so that the change in the flow rate of the gas G flowing through the pipe 21 is within a certain range even if the pressure in the pipe 22 fluctuates. Yes. The change rate limiter P11 is, for example, a pressure detector that detects the in-pipe pressure of the pipe 21, a pressure control valve that adjusts the in-pipe pressure of the pipe 21, a pressure control unit that controls the pressure control valve based on the detected in-pipe pressure, A shut-off valve that shuts off the gas G when the internal pressure of the pipe 21 suddenly increases or decreases is provided.

  The gas combustion amount limiter 3 provided in the combustion unit P10 is configured such that even if the inflow amount of the gas G flowing from the change rate limiter P11 increases, the supply amount of the gas G supplied to the gas combustion system 1 is the gas combustion system. 1 is limited so as not to exceed the amount of combustion of a plurality of gas combustion burners (details will be described later). The gas combustion amount limiter 3 is, for example, a flow meter that measures the inflow amount of the gas G flowing from the change rate limiter P11, a flow rate adjustment valve that adjusts the supply amount of the gas G supplied to the gas combustion system 1, and a flow meter. A flow rate control unit that controls the flow rate control valve based on the detected flow rate of the gas G is provided.

<Schematic configuration of gas combustion system>
Next, a schematic configuration of the gas combustion system 1 according to the present embodiment will be described with reference to FIG. As shown in FIG. 2, the gas combustion system 1 according to the present embodiment includes a pressure detection unit 11 that detects the in-pipe pressure of one pipe 21 through which the gas G flows. In the present embodiment, the gas G flowing through the pipe 21 is hydrogen.

  The gas combustion system 1 includes a plurality of gas combustion burners 12 that combusts a gas G that is provided on the downstream side of the pressure detection unit 11 and flows through a pipe 21, and each of the plurality of gas combustion burners 12 and the pressure detection unit 11. And an automatic switching valve (an example of a switching valve) 13 for switching whether or not to supply the gas G flowing through the pipe 21 to the gas combustion burner 12. Of the plurality of gas combustion burners 12, the gas combustion burner 12a is connected to the automatic switching valve 13a of the plurality of automatic switching valves 13, and the gas combustion burner 12b is connected to the automatic switching valve 13b, and the gas combustion burner An automatic switching valve 13c is connected to 12c, an automatic switching valve 13d is connected to the gas combustion burner 12d, an automatic switching valve 13e is connected to the gas combustion burner 12e, and an automatic switching valve 13f is connected to the gas combustion burner 12f. It is connected.

  In FIG. 2, the automatic switching valves 13a, 13b, 13c, 13d, and 13e are in the open state, the gas combustion burners 12a, 12b, 12c, 12d, and 12e burn the gas G, and the automatic switching valve 13f is in the closed state. The state where the gas combustion burner 12f does not burn the gas G is shown. In FIG. 2, the automatic switching valve 13 in the open state is illustrated in white, and the automatic switching valve 13 in the closed state is illustrated with shading.

  Hereinafter, successive reference signs may be represented by a minimum value and a maximum value and “˜” between these numbers. For example, “automatic switching valves 13a, 13b, 13c, 13d, 13e, and 13f” may be expressed as “automatic switching valves 13a to 13f”. Hereinafter, the gas combustion burners 12a to 12f may be collectively referred to as “gas combustion burner 12”, and the automatic switching valves 13a to 13f may be collectively referred to as “automatic switching valve 13”.

  Although illustration is omitted, a water pipe is disposed around each of the plurality of gas combustion burners 12. The water flowing through the water pipe absorbs heat generated by the gas G being burned by the gas combustion burner 12 and becomes steam. The generated steam is used in a predetermined plant (not shown).

  As shown in FIG. 2, the gas combustion system 1 opens and closes the automatic switching valve 13 so that the gas G is burned by the number of gas combustion burners 12 corresponding to the pressure in the pipe 21 detected by the pressure detector 11. The switching valve control part 14 which controls is provided. The switching valve control unit 14 is configured to be able to individually open and close the automatic switching valve 13. In a predetermined storage area provided in the switching valve control unit 14, an open command pipe pressure that defines the number of automatic switching valves 13 to be opened with respect to the pipe pressure of the pipe 21 is stored, and the automatic operation to close the valve is performed. The closed command pipe pressure defining the number of switching valves 13a to 13f is stored. When the in-pipe pressure of the pipe 21 detected by the pressure detection unit 11 is rising, the switching valve control unit 14 should be automatically opened based on the open command in-pipe pressure stored in the storage area. The number of switching valves 13 is determined. Further, when the in-pipe pressure of the pipe 21 detected by the pressure detection unit 11 is reduced, the switching valve control unit 14 should be closed based on the close command in-pipe pressure stored in the storage area. The number of automatic switching valves 13 is determined.

  Further, the gas combustion system 1 includes a backup type shut-off unit (an example of a shut-off valve) 17 provided in the pipe 21 on the upstream side of the pressure detection unit 11 and shuts off the supply of the gas G to the gas combustion burner 12, and a pressure detection unit. 11 and a shutoff valve control unit 18 that controls the opening and closing of the backup type shutoff unit 17 based on the pressure in the pipe 21 between the backup type shutoff unit 17.

  The backup type shut-off unit 17 includes a plurality (two in this example) of shut-off valves 171 and 172 provided in series with the pipe 21. The shutoff valve 171 and the shutoff valve 172 are each controlled by the shutoff valve control unit 18. The shutoff valve control unit 18 outputs an instruction signal to shut off the flow of the gas G to both the shutoff valve 171 and the shutoff valve 172 at the same time. The backup type shut-off unit 17 has a plurality of shut-off valves 171, 172, so that even if one of the shut-off valve 171 and the shut-off valve 172 malfunctions and does not operate, an instruction signal from the shut-off valve control unit 18 Therefore, the flow of the gas G in the pipe 21 can be surely cut off.

  The shut-off valve control unit 18 includes a plurality (three in this example) of pressure detectors 181, 182, and 183 that detect the pressure in the pipe 21 between the pressure detection unit 11 and the backup type shut-off unit 17. It has a backup type pressure detector 18a. The pressure detector 181, the pressure detector 181, and the pressure detector 181 are provided in series with the pipe 21. When at least two of the pressure detectors 181, 182, and 183 detect the pressure in the pipe 21 that is equal to or higher than a predetermined value, the shut-off valve control unit 18 backs up an instruction signal for shutting off the gas G pipe 21. It outputs to the mold | die cutoff part 17. FIG. Thus, the shut-off valve control unit 18 has a so-called “2 out of 3” configuration.

  Further, the gas combustion system 1 opens and closes the pressure control valve 15 based on the pressure control valve 15 provided in the pipe 21 on the upstream side of the pressure detection unit 11 and the pressure in the pipe 21 on the upstream side of the pressure control valve 15. And a PID control unit 16 for performing PID control. Further, the gas combustion system 1 includes a pressure detector 19 that detects the in-pipe pressure of the pipe 21 on the upstream side of the pressure control valve 15. The PID control unit 16 controls the pressure control valve 15 based on the pressure in the pipe 21 detected by the pressure detector 19.

  The pressure control valve 15 controls the pressure in the pipe 21 on the primary side (that is, the upstream side) and stabilizes the pressure on the supply side (that is, the downstream side). The pressure control valve 15 is designed to give a sufficient pressure loss. Accordingly, the gas combustion system 1 is configured such that the pressure fluctuation on the downstream side due to the automatic point extinguishing of the gas combustion burner 12 does not easily affect the control of the pressure control valve 15.

  The internal pressure of the pipe 21 in the receiving part of the boiler facility P1 is several MPa, whereas the internal pressure of the pipe 21 in the combustion part P10 is several hundred kPa. Thus, the in-pipe pressure of the pipe 21 in the combustion part P10 is one digit or more lower than the in-pipe pressure of the pipe 21 in the receiving part of the boiler facility P1. For this reason, if the in-pipe pressure of the pipe 21 fluctuates by several% at the receiving part of the boiler facility P1, the in-pipe pressure of the pipe 21 in the combustion part P10 may increase several times. The gas combustion system 1 is provided with a PID control unit 16 so that the in-pipe pressure of the pipe 21 in the combustion unit P10 does not rapidly change even if the in-pipe pressure of the pipe 21 in the receiving unit of the boiler facility P1 fluctuates. . The PID control unit 16 controls the pipe 21 so that the pressure inside the pipe 21 varies more slowly on the downstream side than on the upstream side of the PID control unit 16.

  The PID control unit 16 adjusts the proportional operation and integral operation of the control so that the rapid valve operation of the pressure control valve 15 does not affect the control of the downstream gas combustion burner 12. Control of the pressure in the pipe 21 by the PID control unit 16 will be described later.

<Control method of automatic switching valve and gas combustion burner>
Next, a control method of the gas combustion burner 12 in the gas combustion system 1 will be described with reference to FIG. 2 and FIG. In the graph of the gas flow rate characteristic shown in FIG. 3, the horizontal axis indicates the in-pipe pressure (kPa) of the pipe 21 detected by the pressure detection unit 11, and the vertical axis flows through the pipe 21 in the portion where the pressure detection unit 11 is provided. The flow rate of gas G (normalyube (NM3) / h) is shown.

The closed command pipe pressures CP0, CP1, CP3, and CP5 indicated by straight lines in FIG. 3 indicate the pipe pressure of the pipe 21 for switching the automatic switching valve 13 from the open state to the closed state. The closed command pipe pressures CP0, CP1, CP3, CP5 are stored in a predetermined storage area provided in the switching valve control unit 14. The closed command pipe pressure CP0 is a pressure for switching the automatic switching valve 13 to a closed state when one automatic switching valve 13 is open. The closed command pipe pressure CP1 is a pressure when the two automatic switching valves 13 are opened. The closing command pipe pressure CP3 is a pressure for switching one of the four automatic switching valves 13 to the closed state when the four automatic switching valves 13 are in the closed state. The pressure CP5 is a pressure for switching one of the six automatic switching valves 13 to the closed state when the six automatic switching valves 13 are in the open state. Although not shown in the drawings, the predetermined storage area of the switching valve control unit 14 includes a closing command pipe pressure CP2 for switching any one of the three automatic switching valves 13 to a closed state when the three automatic switching valves 13 are open, and 5 The closed command pipe pressure CP4 for switching one of the automatic switching valves 13 to the closed state when the two automatic switching valves 13 are in the open state is stored.
The close command pipe pressure CP2 is set between the close command pipe pressure CP1 and the close command pipe pressure CP3, and the close command pipe pressure CP4 is set between the close command pipe pressure CP3 and the close command pipe pressure CP5. Hereinafter, the closed command pipe pressures CP0 to CP5 are collectively referred to as “closed command pipe pressure CP”.

  Open command pipe pressures OP1, OP2, OP4, and OP6 indicated by straight lines in FIG. 3 indicate the pipe pressure of the pipe 21 for switching the automatic switching valve 13 from the closed state to the open state. The opening command pipe pressures OP1, OP2, OP4, and OP6 are stored in a predetermined storage area provided in the switching valve control unit 14. The open command pipe pressure OP1 is a pressure for switching any one of the automatic switching valves 13 to an open state when all the automatic switching valves 13 are closed, and the open command pipe pressure OP2 is a state in which one automatic switching valve 13 is open. Is the pressure for switching any one of the five automatic switching valves 13 in the closed state to the open state, and the open command pipe pressure OP4 is the closed state when the three automatic switching valves 13 are in the open state. Is the pressure for switching any one of the three automatic switching valves 13 to the open state, and the open command pipe pressure CP6 is the closed automatic switching valve 13 when the five automatic switching valves 13 are open. Is a pressure for switching to the open state. Although illustration is omitted, in a predetermined storage area of the switching valve control unit 14, one of the four automatic switching valves 13 in the closed state is opened when the two automatic switching valves 13 are in the opened state. Open command in-pipe pressure OP3 for switching to one of the two automatic switching valves 13 in the closed state when the four automatic switching valves 13 are in the open state. Is stored. The open command pipe pressure OP3 is set between the open command pipe pressure OP2 and the open command pipe pressure OP4, and the open command pipe pressure OP5 is set between the open command pipe pressure OP4 and the open command pipe pressure OP6. Hereinafter, the open command pipe pressures OP1 to OP6 are collectively referred to as “open command pipe pressure OP”.

  Further, characteristics C0, C1, C3, and C5 indicated by curves in FIG. 3 indicate characteristics of the flow rate of the gas G with respect to the pipe internal pressure of the pipe 21 in the portion where the pressure detection unit 11 is provided. Characteristic C0 indicates a characteristic when all automatic switching valves 13 are closed, characteristic C1 indicates a characteristic when one automatic switching valve 13 is open, and characteristic C3 indicates that three automatic switching valves 13 are open. The characteristic C5 shows the characteristic when the five automatic switching valves 13 are open.

  As shown in FIG. 3, the open command pipe pressure OP and the close command pipe pressure CP are set so as to be shifted depending on the number of automatic switching valves 13 for switching between open and closed states. The number of open states of the automatic switching valve 13 is equal to the number of gas combustion burners 12 combusting the gas G. For this reason, the open command pipe pressure OP and the close command pipe pressure CP are set to be shifted depending on the number of gas combustion burners 12 for burning the gas G. Further, the open command pipe pressure OP and the close command pipe pressure CP are set higher as the number of gas combustion burners 12 for burning the gas G is larger.

  More specifically, the open command pipe pressure OP1 is a pressure at which the gas G is combusted by any one of the gas combustion burners 12a to 12f. The open command pipe pressure OP2 is a pressure at which the gas G is combusted by any two of the gas combustion burners 12a to 12f. The open command pipe pressure OP4 is a pressure at which the gas G is combusted by any four of the gas combustion burners 12a to 12f. The open command pipe pressure OP6 is a pressure at which the gas G is combusted by all of the gas combustion burners 12a to 12f. Accordingly, the open command pipe pressure OP1, the open command pipe pressure OP2, the open command pipe pressure OP4, and the open command pipe pressure OP6 increase in the number of the gas combustion burners 12 that burn the gas G in this order.

  On the other hand, as shown in FIG. 3, the open command pipe pressure OP1 is set such that the pipe pressure of the pipe 21 detected by the pressure detector 11 is, for example, 160 kPa, and the open command pipe pressure OP2 is set in the pipe 21 detected by the pressure detector 11. The in-pipe pressure is set to, for example, 170 kPa, the open command in-pipe pressure OP4 is set to, for example, the in-pipe pressure of the pipe 21 detected by the pressure detection unit 11, and the open command in-pipe pressure OP6 is set to, for example, 180 kPa. Is set to 200 kPa, for example. As described above, the open command pipe pressure OP1, the open command pipe pressure OP2, the open command pipe pressure OP4, and the open command pipe pressure OP6 increase in the pipe pressure of the pipe 21 detected by the pressure detector 11 in this order. Therefore, the open command pipe pressure OP is set to be higher in the pipe 21 detected by the pressure detector 11 as the number of the gas combustion burners 12 that burn the gas G is larger.

  Further, the closed command pipe pressure CP0 is a pressure at which the gas G is not burned by any of the gas combustion burners 12a to 12f. The closed command pipe pressure CP1 is a pressure for switching the gas G to be burned by any one of the gas combustion burners 12a to 12f. The closed command pipe pressure CP3 is a pressure for switching so that the gas G is burned by any three of the gas combustion burners 12a to 12f. The closed command pipe pressure CP5 is a pressure for switching so that the gas G is burned by any five of the gas combustion burners 12a to 12f. Therefore, the closed command pipe pressure CP0, the closed command pipe pressure CP1, the closed command pipe pressure CP3, and the closed command pipe pressure CP5 increase in the number of gas combustion burners 12 that burn the gas G in this order.

  On the other hand, as shown in FIG. 3, the closed command pipe pressure CP0 is set to 11 kPa, for example, in the pipe 21 detected by the pressure detector 11, and the closed command pipe pressure CP1 is set to the pipe 21 detected by the pressure detector 11. The in-pipe pressure is set to, for example, 30 kPa, the close command in-pipe pressure CP3 is set to, for example, the in-pipe pressure of the pipe 21 detected by the pressure detection unit 11, and the close command in-pipe pressure CP5 is set to, for example, the pipe 21 detected by the pressure detection unit 11. The in-tube pressure is set to 60 kPa, for example. As described above, the closed command pipe pressure CP0, the closed command pipe pressure CP1, the close command pipe pressure CP3, and the close command pipe pressure CP5 increase in the pipe pressure of the pipe 21 detected by the pressure detector 11 in this order. Therefore, the closed command pipe pressure CP is set such that the pipe pressure of the pipe 21 detected by the pressure detection unit 11 is higher as the number of gas combustion burners 12 that burn the gas G is larger.

  For example, when the automatic switching valves 13a to 13f are in a closed state and none of the gas combustion burners 12a to 12f burns the gas G, the flow of the gas G flowing through the pipe 21 as shown by the characteristic C0 in FIG. It is assumed that the amount increases and the pipe pressure of the pipe 21 detected by the pressure detection unit 11 becomes equal to or higher than the open command pipe pressure OP1. The switching valve control unit 14 determines that the pipe pressure of the pipe 21 has become equal to or higher than the open command pipe pressure OP1 based on the detection signal input from the pressure detection unit 11, and changes the automatic switching valve 13a from the closed state to the open state, for example. Switch. Thereby, the gas combustion burner 12a burns the gas G that has reached through the automatic switching valve 13a.

  When the gas combustion burner 12a burns the gas G, the pressure inside the pipe 21 in the portion where the pressure detection unit 11 is provided (that is, the portion immediately before the pipe 21 branches) decreases. Here, when the combustion amount of the gas G burned by the gas combustion burner 12a is larger than the increase amount of the inflow amount of the gas G flowing from the upstream side of the pipe 21, the in-pipe pressure detected by the pressure detector 11 is detected. Gradually decreases to a pressure equal to or lower than the closed command pipe pressure CP0. As a result, the switching valve control unit 14 determines that the pipe pressure of the pipe 21 has become equal to or lower than the closing command pipe pressure CP0 based on the detection signal input from the pressure detection unit 11, and closes the automatic switching valve 13a from the open state. Switch to state. Thereby, since the flow of the gas G to the gas combustion burner 12a is blocked by the automatic switching valve 13a, the gas G does not reach the gas combustion burner 12a, and the gas combustion burner 12a stops the combustion of the gas G.

  On the other hand, if the combustion amount of the gas G burned by the gas combustion burner 12a is smaller than the increase in the inflow amount of the gas G flowing from the upstream side of the piping 21, the piping 21 detected by the pressure detection unit 11 Although the pressure in the pipe temporarily decreases with the start of combustion in the gas combustion burner 12, as the characteristic time C1 in FIG. Become. Accordingly, the switching valve control unit 14 determines that the pipe pressure of the pipe 21 has become equal to or higher than the open command pipe pressure OP2 based on the detection signal input from the pressure detection unit 11, and maintains the open state of the automatic switching valve 13a. For example, the automatic switching valve 13b is switched from the closed state to the open state. Thereby, since the gas G reaches the gas combustion burner 12b through the automatic switching valve 13b, the gas G is combusted by both the gas combustion burner 12a and the gas combustion burner 12b.

  When the pipe pressure of the pipe 21 detected by the pressure detection unit 11 by burning the gas G by the gas combustion burners 12a and 12b becomes equal to or lower than the closed command pipe pressure CP1, the switching valve control unit 14 sets the automatic switching valve 13a, for example. While maintaining the open state, the automatic switching valve 13b is switched from the open state to the closed state. On the other hand, even if the gas G is burned by the gas combustion burners 12a and 12b, the pipe pressure of the pipe 21 detected by the pressure detection unit 11 without the pipe pressure of the pipe 21 being lowered is higher than the open command pipe pressure OP3 (not shown). Then, the switching valve control unit 14 switches, for example, the automatic switching valve 13c from the closed state to the opened state while maintaining the automatic switching valves 13a and 13b in the opened state. Thereby, since the gas G reaches | attains the gas combustion burner 12c through the automatic switching valve 13c, the gas G is combusted by the gas combustion burners 12a-12c. Thus, the gas combustion system 1 can increase the combustion amount of the gas G burned by the gas combustion burner 12.

  When the in-pipe pressure of the pipe 21 detected by the pressure detection unit 11 by burning the gas G by the gas combustion burners 12a to 12c becomes equal to or less than the closed command in-pipe pressure CP2, the switching valve control unit 14 may, for example, automatically switch valves 13a, The automatic switching valve 13c is switched from the open state to the closed state while maintaining 13b in the open state. Thereby, the gas combustion burner 12 can reduce the combustion amount of the gas G.

  On the other hand, when the automatic switching valves 13a to 13c are in the open state and the gas G is burned by the gas combustion burners 12a to 12c, as shown by the characteristic C3 in FIG. Is increased, and the pipe pressure of the pipe 21 detected by the pressure detection unit 11 becomes equal to or higher than the open command pipe pressure OP4. The switching valve control unit 14 determines that the pipe pressure of the pipe 21 has become equal to or higher than the open command pipe pressure OP4 based on the detection signal input from the pressure detection unit 11, and opens the automatic switching valves 13a, 13b, and 13c, for example. The automatic switching valve 13d is switched from the closed state to the open state while maintaining the above. Accordingly, the gas G reaches the gas combustion burner 12d through the automatic switching valve 13d, so that the gas G is combusted by the gas combustion burners 12a to 12d. Thus, the gas combustion system 1 can increase the combustion amount of the gas G burned by the gas combustion burner 12.

  When the in-pipe pressure of the pipe 21 detected by the pressure detection unit 11 by burning the gas G by the gas combustion burners 12a to 12d becomes equal to or lower than the close command in-pipe pressure CP3, the switching valve control unit 14 may, for example, automatically switch the valves 13a to 13a. The automatic switching valve 13d is switched from the open state to the closed state while maintaining 13c in the open state. Thereby, the gas combustion burner 12 can reduce the combustion amount of the gas G.

  On the other hand, even if the gas G is combusted by the gas combustion burners 12a to 12d, the pipe pressure of the pipe 21 detected by the pressure detector 11 without the pipe pressure of the pipe 21 being lowered is higher than the open command pipe pressure OP5 (not shown). Then, the switching valve control unit 14 switches, for example, the automatic switching valve 13e from the closed state to the opened state while maintaining the automatic switching valves 13a to 13d in the opened state. Thereby, since the gas G reaches the gas combustion burner 12e through the automatic switching valve 13e, the gas G is combusted by the gas combustion burners 12a to 12e. Thus, the gas combustion system 1 can increase the combustion amount of the gas G burned by the gas combustion burner 12.

  When the pipe pressure of the pipe 21 detected by the pressure detection unit 11 by burning the gas G by the gas combustion burners 12a to 12e becomes equal to or lower than the closed command pipe pressure CP4 (not shown), the switching valve control unit 14 is automatically The automatic switching valve 13e is switched from the open state to the closed state while maintaining the switching valves 13a to 13d in the open state. Thereby, the gas combustion burner 12 can reduce the combustion amount of the gas G.

  On the other hand, when the automatic switching valves 13a to 13e are in the open state and the gas G is burned by the gas combustion burners 12a to 12e, as shown by the characteristic C5 in FIG. Is increased, and the in-pipe pressure of the pipe 21 detected by the pressure detector 11 becomes equal to or higher than the open command pipe pressure OP6. The switching valve control unit 14 determines that the pipe pressure of the pipe 21 has become equal to or higher than the open command pipe pressure OP6 based on the detection signal input from the pressure detection unit 11, and maintains the automatic switching valves 13a to 13e in the open state, for example. The automatic switching valve 13f is switched from the closed state to the open state while keeping the state. As a result, the gas G reaches the gas combustion burner 12f through the automatic switching valve 13f, so that the gas G is combusted by the gas combustion burners 12a to 12f. Thus, the gas combustion system 1 can increase the combustion amount of the gas G burned by the gas combustion burner 12.

  When the in-pipe pressure of the pipe 21 detected by the pressure detection unit 11 by burning the gas G by the gas combustion burners 12a to 12f becomes equal to or less than the closed command in-pipe pressure CP5, the switching valve control unit 14 includes, for example, automatic switching valves 13a to 13a. The automatic switching valve 13f is switched from the open state to the closed state while maintaining 13e in the open state. In the gas combustion system 1, the combustion amount of the gas G combusted simultaneously by the gas combustion burners 12a to 12f is configured so as to be able to absorb the maximum flow rate of the gas G flowing into the boiler facility P1 (see FIG. 1). For this reason, after each gas combustion burner 12a-12f starts combustion of the gas G, the pipe | tube pressure of the piping 21 which the pressure detection part 11 detects does not become more than the open command pipe | tube pressure OP6.

  As described above, in the gas combustion system 1, it is possible to automatically extinguish a plurality of gas combustion burners 12 from one to the maximum number (six in this example). For this reason, the gas combustion system 1 can suppress the minimum combustion flow rate to the capacity restriction for one of the plurality of gas combustion burners 12. Further, the open command pipe pressure OP and the close command pipe pressure CP are set higher as the number of gas combustion burners 12a to 12f for burning the gas G is larger. Thereby, since the gas combustion system 1 can adjust and change the setting value of the pipe | tube internal pressure of the piping 21 for every number of the gas combustion burners 12a-12f, one gas combustion burner 12a-12f is ensured one by one. Point fire extinguishes and can cope with flow rate fluctuation smoothly.

<Gas Control Method by PID Control Unit>
Next, a method for controlling the gas G flowing through the pipe 21 by the PID control unit 16 will be described with reference to FIG. The horizontal axis of the graphs shown in FIGS. 4A to 4C represents the elapsed time (seconds). The vertical axis on the left side of the graphs shown in FIG. 4A to FIG. 4C shows the flow rate (NM3 / h) of the gas G flowing through the pipe 21 and the pipe pressure (kPa) in the pipe 21 detected by the pressure detector 11. Represents. Also, the right vertical axis of the graphs shown in FIGS. 4A to 4C is the flow rate of the gas G flowing through the pipe 21 on the downstream side of the PID control unit 16 (the output amount of the PID control unit 16) (%). Represents.

  A curve IF shown in FIGS. 4A to 4C shows a time transition of the inflow amount of the gas G flowing into the pressure control valve 15, and a curve MV shows a time transition of the output amount of the PID control unit 16. The curve BC shows the time transition of the combustion amount of the gas G burned by the gas combustion burner 12, and the curve GP shows the time transition of the in-pipe pressure of the pipe 21 detected by the pressure detector 11.

Further, in the control simulation of the pressure inside the pipe 21 shown in FIGS. 4A to 4C, the proportional band of PID control is set to 230, the integration time is set to 50 seconds, and the volume of the pipe 21 is 3.37 m ³ is set, the pipe length of the pipe 21 is set to 400 meters, and the initial pressure at an elapsed time of 0 seconds is set to 600 kPa.

  As shown by the curve IF in FIG. 4 (a), it is assumed that the inflow amount of the gas G flowing into the pressure control valve 15 is stepped down from 2300 NM3 / h to 300 NM3 / h at a rate of change of 730 NM / min. As indicated by the curve MV, the PID controller 16 controls the flow of the gas G so that the rate of change of the gas G on the downstream side is smaller and gentler than the rate of change of the gas G on the upstream side. For this reason, as shown by a curve BC in FIG. 4A, the combustion amount of the gas G burned by the gas combustion burner 12 does not fluctuate stepwise but fluctuates gently.

  Further, as shown by the curve MV in FIG. 4A, the pressure loss of the pressure control valve 15 is set in the range of 30% to 70%. For this reason, as shown by the curve GP in FIG. 4A, the in-pipe pressure of the pipe 21 detected by the pressure detection unit 11 varies in the flow rate of the gas G into the pressure control valve 15 (that is, the pressure control valve 15 It is not affected by fluctuations in the pipe pressure of the pipe 21 on the upstream side. That is, the in-pipe pressure of the pipe 21 detected by the pressure detection unit 11 changes gently without changing in steps at the timing when the inflow amount of the gas G to the pressure control valve 15 changes in steps.

  As shown by the curve IF in FIG. 4B, it is assumed that the inflow amount of the gas G flowing into the pressure control valve 15 is increased stepwise from 300 NM3 / h to 2300 NM3 / h with a change rate of 730 NM / min. As indicated by the curve MV, the PID controller 16 controls the flow of the gas G so that the rate of change of the gas G on the downstream side is smaller and gentler than the rate of change of the gas G on the upstream side. For this reason, as shown by a curve BC in FIG. 4B, the combustion amount of the gas G burned by the gas combustion burner 12 does not fluctuate stepwise but fluctuates gently.

  Further, as shown by the curve MV in FIG. 4B, the pressure loss of the pressure control valve 15 is set in the range of 30% to 70%. For this reason, as shown by a curve GP in FIG. 4B, the pipe pressure of the pipe 21 detected by the pressure detection unit 11 varies in the amount of gas G flowing into the pressure control valve 15 (that is, the pressure control valve 15 It is not affected by fluctuations in the pipe pressure of the pipe 21 on the upstream side. That is, the in-pipe pressure of the pipe 21 detected by the pressure detection unit 11 changes gently without changing in steps at the timing when the inflow amount of the gas G to the pressure control valve 15 changes in steps.

  As shown by a curve IF in FIG. 4C, it is assumed that the inflow amount of the gas G flowing into the pressure control valve 15 repeatedly fluctuates between 300 NM3 / h and 2300 NM3 / h at a change rate of 730 NM / min. As indicated by the curve MV, the PID controller 16 controls the flow of the gas G so that the rate of change of the gas G on the downstream side is smaller and gentler than the rate of change of the gas G on the upstream side. For this reason, as shown by a curve BC in FIG. 4C, the combustion amount of the gas G burned by the gas combustion burner 12 does not fluctuate in a saw-like manner but fluctuates gently in the vicinity of the maximum value and the minimum value. To do.

  Further, as indicated by a curve MV in FIG. 4C, the pressure loss of the pressure control valve 15 is set in the range of 30% to 70%. For this reason, as shown by a curve GP in FIG. 4C, the pipe pressure of the pipe 21 detected by the pressure detection unit 11 varies in the amount of gas G flowing into the pressure control valve 15 (that is, the pressure control valve 15 It is not affected by fluctuations in the pipe pressure of the pipe 21 on the upstream side. That is, the in-pipe pressure of the pipe 21 detected by the pressure detection unit 11 changes gently without changing in a saw-like manner at the timing when the inflow amount of the gas G to the pressure control valve 15 changes in a saw-like manner.

  In this way, the PID control unit 16 changes the flow rate of the gas G on the upstream side and the rapid fluctuation of the pressure in the pipe 21 to the flow rate of the gas G to the automatic switching valve 13 and the gas G in the gas combustion burner 12. Control can be performed so as not to affect the amount of combustion.

<Modification>
Next, the gas combustion system by the modification of this embodiment is demonstrated using FIG. The gas combustion system according to this modification is characterized in that it includes a plurality of automatic switching valves 20 instead of the plurality of automatic switching valves 13 of the gas combustion system 1 shown in FIG. A plurality (six in this example) of automatic switching valves 20 provided in the gas combustion system according to this modification have the same configuration. In FIG. 5, one automatic switching valve 20 among the plurality of automatic switching valves 20 is illustrated. Further, in FIG. 5, for easy understanding, the gas combustion burner 12 provided on the downstream side of the automatic switching valve 20 and the switching valve control unit 14 for controlling the automatic switching valve 20 are shown together. .

  As shown in FIG. 5, the automatic switching valve 20 includes a pressure detector (an example of a detector) 211 that detects the pressure of the gas combustion burner 12 provided downstream of the automatic switching valve 20, and opening and closing of the automatic switching valve 20. And a limit switch (an example of a detection unit) 213 for detecting the state. By providing the pressure detector 211 and the limit switch 213, the automatic switching valve 20 can change the sequence of the open / close timing according to the characteristics and flow range of each gas combustion burner 12, and can ensure stable combustion in a wide combustion range.

  As described above, the gas combustion system 1 according to the present embodiment can change the number of the plurality of gas combustion burners 12 that combust the gas G according to the pressure in the pipe 21. That is, the gas combustion system 1 can change the number of the gas combustion burners 12 that combust the gas G according to fluctuations in the flow rate of the gas G flowing through the pipe 21. Thereby, according to the gas combustion system 1, since the minimum combustion amount of the gas G can be changed according to the flow volume of the gas G which distribute | circulates the piping 21, the improvement of a turndown ratio can be aimed at. Moreover, according to the gas combustion system 1 by this embodiment, hydrogen can be burned stably in a wide flow rate range.

  Conventionally, hydrogen is a substance that has been used in various fields. However, it is difficult to say that it is effectively used as a fuel for boilers and the like that are becoming cheaper. As described above, the amount of hydrogen generated as a by-product in a chemical manufacturer, petrochemical company, or the like may fluctuate or the supply demand of the supplier may fluctuate greatly. For this reason, for example, it is conceivable to install a hydrogen buffer tank that absorbs fluctuations of the generated hydrogen. However, the hydrogen buffer tank has a problem in installation location and cost. For this reason, in actuality, the generated hydrogen fluctuation is often incinerated by the flare equipment.

  When the flare equipment is used to burn the combustion gas without being limited to hydrogen, it is desired to recover the heat radiation loss to the atmosphere in the flare processing. When combustion gas is used as fuel for boilers, etc., stable controllability over a wide range of combustion amounts, especially controllability over the entire range of high and low combustion loads while reducing the minimum combustion flow rate to the limit, and suppressing the base of combustion gas amount Is required.

  The gas combustion system 1 according to the present embodiment includes a plurality of gas combustion burners 12 to stabilize hydrogen and other combustion gases generated as a by-product in a chemical manufacturer, a petrochemical company, etc. in a wide combustion amount range. Controllability, in particular, controllability over the entire range of high and low combustion loads can be ensured while reducing the minimum combustion flow rate, and the base of the combustion gas amount can be suppressed. Thereby, according to the gas combustion system 1, it is not necessary to install a gas buffer tank, and the gas byproduced by a chemical manufacturer, a petrochemical company, etc. can be utilized effectively.

The present invention can be modified in various ways regardless of the above embodiment.
In the said embodiment, although demonstrated using hydrogen as gas G, the gas combustion system 1 by this embodiment is applicable to combustible gas other than hydrogen. Also in this case, the same effect as the gas combustion system 1 by the said embodiment is acquired.

  In the gas combustion system 1 according to the above embodiment, the plurality of gas combustion burners 12 have the same configuration, but at least one of the plurality of gas combustion burners 12 has a different configuration (for example, different combustion performance). Even if it is, the effect similar to the gas combustion system 1 by the said embodiment is acquired.

  The plurality of gas combustion burners 12 may be unitized. Also in this case, the gas combustion burner 12 can ensure a wide combustion amount range.

  The above embodiments exemplify apparatuses and methods for embodying the technical idea of the present invention, and the technical idea of the present invention specifies the material, shape, structure, arrangement, etc. of the component parts. It is not what you do. The technical idea of the present invention can be variously modified within the technical scope defined by the claims described in the claims.

DESCRIPTION OF SYMBOLS 1 Gas combustion system 3 Gas combustion amount limiter 11 Pressure detection part 12,12a, 12b, 12c, 12d, 12e, 12f Gas combustion burner 13,13a, 13b, 13c, 13d, 13e, 13f Automatic switching valve 14 Switching valve control Unit 15 pressure control valve 16 PID control unit 17 backup type shut-off unit 18 shut-off valve control unit 18a backup type pressure detection unit 19, 181, 182, 183, 211 pressure detector 20 automatic switching valve 21, 22 piping 171, 172 shut-off valve 213 Limit switch P1 Boiler equipment P2 Gas supply equipment P10 Combustion part P11 Change rate limiter

Claims (7)

A pressure detector for detecting the pressure in one pipe through which gas flows;
A plurality of gas combustion burners that are provided on the downstream side of the pressure detection unit and burn the gas flowing through the pipe;
A switching valve for switching whether to supply the gas flowing through the pipe to the gas combustion burner individually provided between each of the plurality of gas combustion burners and the pressure detection unit;
A gas combustion system comprising: a switching valve control unit that controls opening and closing of the switching valve so that the gas is burned by the number of the gas combustion burners according to the number of pipe pressures detected by the pressure detection unit. The open command pipe pressure for switching the switching valve from the closed state to the open state and the close command pipe pressure for switching the switching valve from the open state to the closed state are set to be shifted by the number of the gas combustion burners that burn the gas. The gas combustion system according to claim 1. The gas combustion system according to claim 2, wherein the open command pipe pressure and the close command pipe pressure are set higher as the number of the gas combustion burners for burning the gas is larger. A pressure control valve provided in the pipe upstream of the pressure detector;
The gas combustion system according to any one of claims 1 to 3, further comprising: a PID control unit that performs PID control of opening and closing of the pressure control valve based on an in-pipe pressure of the pipe on the upstream side of the pressure control valve. A shutoff valve that is provided in the pipe upstream of the pressure detector and shuts off the supply of the gas to the gas combustion burner;
The gas according to any one of claims 1 to 4, further comprising: a shutoff valve control unit that controls opening and closing of the shutoff valve based on an in-pipe pressure of the pipe between the pressure detection unit and the shutoff valve. Combustion system. The switch valve has a detector that detects a pressure of the gas combustion burner provided downstream of the switch valve, and a detection unit that detects an open / closed state of the switch valve. The gas combustion system according to one item. The gas combustion system according to any one of claims 1 to 6, wherein the gas is hydrogen.

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