JP2005201541A - Combustion equipment with fuel booster pump in fuel supply line - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce power consumption by a fuel booster pump while keeping stability of combustion. <P>SOLUTION: In this combustion equipment, the fuel booster pump 7 for intensifying the supply pressure of fuel, and fuel valves 8, 9, 10 for controlling fuel supply, are installed at intermediate parts of a fuel supply line 4, and the combustion quantity can be adjusted to high combustion with a large combustion quantity and low combustion with a small combustion quantity by the operation of the fuel valves. A rotating speed regulating device 12 for changing the rotating speed of the fuel booster pump 7 is installed at the fuel booster pump 7 to perform control of increasing the rotating speed of the fuel booster pump 7 in high combustion and reducing the rotating speed of the fuel booster pump 7 in low combustion. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a combustion apparatus having a fuel booster pump in a fuel supply path.

  As described in Japanese Patent Laid-Open No. 7-233936, there is known a combustion apparatus in which a fuel valve is installed in a fuel supply path and the combustion amount is changed by opening and closing the fuel valve. In the combustion apparatus described in JP-A-7-233936, fuel is supplied by a fuel pump, the fuel pressure is adjusted by a fuel flow rate control valve, and the fuel supply to the burner is controlled by opening and closing the fuel valve. I have to.

In this case, the pressure of the fuel pump secondary side is increased by keeping the rotation speed of the fuel pump constant, and the fuel supply amount is increased or decreased by opening and closing the fuel flow rate adjustment valve and the fuel valve. However, it is necessary to supply fuel at the rated capacity of the fuel pump during a part of the boiler operation period, and when the combustion amount is small, the rotation speed may be smaller than the rated capacity. Maintaining the number of revolutions for the capacity was wasted power consumption.
JP-A-7-233936

  The problem to be solved by the present invention is to reduce the power consumption by the fuel booster pump while maintaining the stability of combustion.

  According to the first aspect of the present invention, a fuel booster pump that raises the fuel supply pressure and a fuel valve that controls the fuel supply are installed in the middle of the fuel supply path, and a high combustion with a large combustion amount by operating the fuel valve. In the combustion device that allows the combustion amount to be adjusted to low combustion with low combustion amount, a fuel booster pump is installed in the fuel booster pump to change the rotation number of the fuel booster pump, and the fuel booster pump at high combustion Is a combustion apparatus having a fuel booster pump in a fuel supply path, wherein control is performed to increase the rotational speed of the fuel booster and to lower the rotational speed of the fuel booster pump during low combustion.

  In the combustion apparatus having the fuel booster pump in the fuel supply path, when the combustion amount is changed from low combustion to high combustion, the number of revolutions of the fuel booster pump is first increased. The combustion apparatus having the fuel booster pump in the fuel supply path is characterized in that the operation for starting the operation and opening the fuel valve is controlled to be delayed from the start of the change in the rotation speed of the fuel booster pump.

  According to a third aspect of the present invention, in the combustion apparatus having a fuel booster pump in the fuel supply path, a pressure detection device that detects a fuel supply pressure upstream of the fuel booster pump in the fuel supply path is provided. In addition, when the fuel supply pressure falls below a predetermined value, the fuel booster pump is provided in the fuel supply path, which performs control to increase the rotation speed of the fuel booster pump even during low combustion. Combustion equipment.

  By implementing the present invention, it is possible to reduce power consumption by the fuel booster pump while maintaining combustion stability.

  FIG. 1 is a fuel supply flow chart in one embodiment, and FIG. 2 is a time chart showing a control situation in one embodiment. The embodiment relates to a boiler 1 that performs combustion control at three positions of high combustion, low combustion, and stop, and a combustion device is provided in the upper part of the boiler 1. The combustion device includes a burner 2 that performs combustion by mixing fuel and combustion air, a blower 3 that sends combustion air to the burner 2, a fuel supply path 4 that sends fuel to the burner, a control device 5 that controls the operation of the boiler, and the like. It is made up of. The fuel supply path 4 supplies gas fuel, and is provided with a pressure detection device 6, a fuel booster pump 7, and a pressure control valve 8 in order from the upstream side, and a parallel portion is provided on the downstream side of the pressure control valve 8. A low combustion fuel valve 9 and a high combustion fuel valve 10 are installed in parallel. The pressure control valve 8 detects the gas pressure on the secondary side and adjusts the opening so that the pressure becomes a predetermined pressure. If the pressure control valve secondary pressure is high, the gas pressure is reduced by narrowing the opening. Is reduced to a predetermined value. A damper 11 that adjusts the supply amount of combustion air is provided in the air passage connecting the blower 3 and the burner 2, and an inverter device 12 that adjusts the rotational speed of the fuel booster pump 7 is connected to the fuel booster pump 7, and the pressure is increased. The detection device 6, the inverter device 12, the pressure control valve 8, the low combustion fuel valve 9, the high combustion fuel valve 10, the blower 3, and the damper 11 are connected to the control device 5.

  The low combustion fuel valve 9 and the high combustion fuel valve 10 are electromagnetic valves that control the supply of fuel by opening and closing the valves, and both valves are closed when the combustion is stopped, and the low combustion fuel valve 9 is opened when the combustion is low. Thus, fuel is supplied through a pipe on the low combustion fuel valve 9 side, and at the time of high combustion, both the low combustion fuel valve 9 and the high combustion fuel valve 10 are opened, and the low combustion fuel valve 9 side pipe and the high combustion fuel valve are opened. Fuel is supplied from both 10 side pipes. The inverter device 12 changes the rotation speed of the fuel booster pump 7 by changing the frequency of the power supplied to the fuel booster pump 7, and the inverter device 12 is set with a high combustion frequency and a low combustion frequency. Keep it. The control device 5 outputs a frequency command to the inverter device 12 and adjusts the rotational speed of the fuel booster pump 7 by changing the frequency of the inverter device 12.

  The combustion air is supplied by operating the blower 3, and the combustion air supply amount is adjusted by the damper 11. The opening for high combustion and the opening for low combustion are set in the damper 11, and the opening is increased during high combustion, and the opening is decreased during low combustion to pass through the damper 11 to the burner 2. Adjust the amount of air reached.

  The operation of the inverter device 12, the pressure control valve 8, the low combustion fuel valve 9, the high combustion fuel valve 10, the blower 3, and the damper 11 is controlled by the control device 5 based on the operating state of the boiler. The frequency adjustment of the power supplied from the device 12 to the fuel booster pump 7 is performed in consideration of the supply side pressure detected by the pressure detection device 6. The output from the control device 5 to the inverter device 12 is basically a high combustion frequency during high combustion and a low combustion frequency during low combustion, but the supply gas pressure P1 detected by the pressure detection device 6 When the value is lower than the lower limit value, the frequency is set to be a high combustion frequency even during low combustion. The gas pressure that the control device 5 needs to detect is the supply pressure upstream of the fuel booster pump 7, but for the sake of illustration, FIG. 2 shows the post-pressurization pressure P2 that is the pressure on the secondary side of the fuel booster pump. The change of the post-adjustment pressure P3, which is the pressure on the secondary side of the pressure control valve, is described.

  Based on the time chart of FIG. 2, the operating state of each device will be described. When the operation of the boiler is stopped, the operation of each device is stopped so that fuel is not supplied to the burner 2. When starting combustion of a boiler, since it is dangerous if unburned gas remains in the boiler, pre-purge is first performed when starting combustion. In the pre-purge process, the blower 3 is operated, the damper 11 is set to an opening for high combustion, and the inside of the boiler 1 is ventilated by sending air into the boiler 1. At this time, in preparation for the start of combustion, the inverter device 12 outputs a command for a low combustion frequency, and the fuel booster pump 7 has a low combustion rotation speed. Therefore, the value of the post-pressurization pressure P2, which is the secondary side of the fuel booster pump, increases, but the pressure control valve 8, the low combustion fuel valve 9, and the high combustion fuel valve 10 remain closed. No fuel is sent to the fuel tank, and the value of the adjusted pressure P3, which is the secondary side of the pressure control valve, remains low.

  When the combustion is performed after the pre-purge process, the combustion starts from low combustion. When performing low combustion, the damper 11 is set to an opening for low combustion so that the amount of blown air is made low, and the pressure adjustment valve 8 and the low combustion fuel valve 9 are opened to supply fuel for low combustion. I do. When the fuel supply is started, the value of the post-adjustment pressure P3 increases, and the gas pressure temporarily decreases in the portion upstream of the pressure control valve 8. The pressure fluctuates immediately after the start of gas supply, but when a certain amount of time has passed and pressure regulation by the pressure regulating valve 8 begins to act, the value of the regulated pressure P3 becomes stable.

  In the case of low combustion, since the amount of fuel used in the burner 2 is small, it is not necessary to increase the rotational speed of the fuel booster pump 7. Therefore, the control device 5 outputs a command for a low combustion frequency to the inverter device 12, and reduces the power consumption by suppressing the fuel booster pump 7 to a low combustion rotation speed.

  When the control device 5 decides to shift from low combustion to high combustion, the control device 5 first instructs the inverter device 12 to change the power supply frequency of the fuel booster pump 7 from the low combustion frequency to the high combustion frequency. send. In the inverter device 12 that has received the high combustion frequency command, the frequency starts to increase and the rotational speed of the fuel booster pump 7 is increased. However, there is a time lag until the gas pressure on the secondary side of the fuel booster pump actually increases after the start of the increase in the power supply frequency, and the gas pressure does not increase immediately. When a predetermined delay time has elapsed since the command for changing to the high combustion frequency is output to the inverter device 12, the control device 5 changes the air supply amount adjusted by the damper 11 to the high combustion air amount. Then, by opening the high combustion fuel valve 10, the fuel supply amount is set to the high combustion fuel amount, and the combustion amount is set to the high combustion.

  The pressure increase of the fuel booster pump secondary pressure (pressure P2 after pressurization) due to the increase in the number of revolutions of the fuel booster pump 7 is due to the increase in the air supply amount and the fuel supply amount due to the operation of the damper 11 and the high combustion fuel valve 10. Therefore, when shifting from low combustion to high combustion, simultaneously with the change command to the high combustion frequency for the inverter device 12, the increase in the air supply amount by widening the opening of the damper 11 and the high combustion fuel valve 10 When the fuel supply amount is increased by opening the valve, the increase in the fuel booster pump secondary pressure (post-pressurization pressure P2) due to the increase in the rotation speed of the fuel booster pump 7 is caused by the damper 11 and the high combustion fuel valve 10. This is later than the increase in the air supply amount and fuel supply amount due to the operation of. In this case, the balance between the fuel supply amount and the combustion air supply amount is lost, and the combustion state is deteriorated. Therefore, when shifting from low combustion to high combustion, the gas pressure on the secondary side of the fuel booster pump is increased by giving a command to the inverter device 12 in advance to prevent the combustion state from deteriorating during the shift of the combustion amount. doing.

  When shifting from high combustion to low combustion, the delay that has been performed when shifting from low combustion to high combustion is not performed. When shifting from high combustion to low combustion, the control device 5 sends a command to the inverter device 12 to change the frequency of the fuel booster pump 7 from the high combustion frequency to the low combustion frequency, and then adjusts it with the damper 11. The amount of air supplied is changed to a low combustion air volume, and the high combustion fuel valve 10 is closed, whereby the fuel supply quantity is set to a low combustion fuel quantity and the combustion quantity is set to low combustion. When changing the rotational speed of the fuel booster pump 7 from the high combustion rotational speed to the low combustion rotational speed, a certain amount of time is required as in the case of changing from the low combustion rotational speed to the high combustion rotational speed. However, since the pressure control valve 8 for reducing the gas supply pressure to a predetermined pressure is provided on the downstream side of the fuel booster pump 7 in the fuel supply path, the pressure control valve is increased in proportion to the high gas pressure on the fuel booster pump secondary side. The gas pressure on the secondary side can be kept constant, and no delay time is required as in the case of shifting from low combustion to high combustion.

  At the time of low combustion, the power consumption is reduced by setting the rotational speed of the fuel booster pump 7 to the rotational speed for low combustion. However, the supply gas is supplied when another device connected to the same fuel supply path 4 starts operation. The pressure itself may temporarily drop. In this case, if the fuel booster pump 7 is operated at a low combustion speed, the gas pressure supplied to the burner 2 will be insufficient. Therefore, when the value of the supply gas pressure P1 detected by the pressure detection device 6 is lower than the lower limit value, the fuel gas supply pressure is increased by continuing the stable combustion by setting the rotation speed for high combustion. To be able to.

  The fuel booster pump 7 can reduce the power consumption by setting the rotational speed for low combustion during low combustion and setting the rotational speed for high combustion only when the fuel gas supply pressure needs to be increased. And when shifting to high combustion, change to the high combustion rotational speed is preceded, and when the fuel supply pressure decreases, the rotational speed for high combustion is set so that when the combustion amount shifts or the supply side pressure changes Can also prevent the combustion state from deteriorating.

Fuel supply flow chart in one embodiment of the present invention Time chart in one embodiment of the present invention

Explanation of symbols

1 boiler
2 Burner
3 Blower
4 Fuel supply route
5 Control device
6 Pressure detector
7 Fuel Booster Pump 8 Pressure Control Valve 9 Low Combustion Fuel Valve 10 High Combustion Fuel Valve 11 Damper
12 Inverter device

Claims (3)

  A fuel booster pump that raises the fuel supply pressure and a fuel valve that controls the fuel supply are installed in the middle of the fuel supply path, and the combustion of the fuel valve to high combustion with a large combustion amount and low combustion with a small combustion amount In a combustion device that allows the amount to be adjusted, a fuel speed booster pump that changes the speed of the fuel booster pump is installed in the fuel booster pump. A combustion apparatus having a fuel booster pump in a fuel supply path, characterized in that control is sometimes performed to reduce the rotational speed of the fuel booster pump.   In the combustion apparatus having the fuel booster pump in the fuel supply path according to claim 1, when the combustion amount is changed from low combustion to high combustion, an operation of increasing the rotational speed of the fuel booster pump is started first. A combustion apparatus having a fuel booster pump in a fuel supply path, wherein the operation of opening the fuel valve is delayed and started from the start of changing the rotational speed of the fuel booster pump.   3. A combustion apparatus having a fuel booster pump in a fuel supply path according to claim 1 or 2, wherein a pressure detection device for detecting a supply pressure of fuel is provided upstream of the fuel booster pump in the fuel supply path. A combustion apparatus having a fuel booster pump in a fuel supply path, wherein the control is performed to increase the rotational speed of the fuel booster pump even when the combustion pressure is lower than a predetermined value. .

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