JP6481452B2 - Boiler equipment - Google Patents

Description

  The present invention relates to a boiler device. More specifically, the present invention relates to a boiler device including a can body and a feed water heater that heats feed water supplied to the can body.

  Conventionally, a boiler apparatus has been proposed that includes a can body that generates steam by heating water with combustion gas generated by burning fuel, and a feed water heater that heats water (feed water) supplied to the can body. Has been. The feed water heater improves the heat utilization efficiency (boiler efficiency) of the boiler device by heating the feed water using the heat of the combustion gas discharged after being used to generate steam in the can.

  Here, the water supply to the can body is controlled based on the water level inside the can body. That is, water supply is performed when the water level of the can body becomes low, and water supply is stopped when the water level of the can body becomes high. Therefore, in a boiler device provided with a feed water heater, when the feed water is stopped and the feed water stays in the feed water heater, the feed water may be heated excessively to boil.

  In order to prevent boiling of feed water in such a feed water heater, the feed water flow rate is continuously changed according to the water level of the can body, and even when the water level of the can body becomes high, the constant flow rate (minimum flow rate) Has proposed a boiler apparatus that performs continuous water supply control for supplying water (for example, see Patent Document 1).

JP 2012-2385 A

  However, in order to continuously change the feed water flow rate according to the water level of the can body, it is necessary to configure the boiler device including a feed water flow meter for measuring the feed water flow rate, which increases the manufacturing cost of the boiler device. End up.

  Therefore, an object of this invention is to provide the boiler apparatus which can suppress that feed water boils in a feed water heater, without making manufacturing cost high.

  The present invention is a boiler device that burns fuel to generate steam from feed water, the can body, a water supply line that supplies water to the can body, and the water supply line that is disposed in the water supply line and is supplied to the can body There was a feed water heater for heating feed water with combustion gas generated by combustion of the fuel, a feed water pump arranged in the feed water line and driven according to an input frequency, and a feed request for the can body A water supply control unit that drives the water supply pump at a first frequency to supply water to the can body, and drives the water supply pump at a second frequency lower than the first frequency when the water supply is not requested. A water level measurement unit that measures the water level inside the can body, a water level change amount calculation unit that calculates a change rate of the water level measured by the water level measurement unit, and when there is no water supply request to the can body, The water level change calculation As the rate of change of the water level to be calculated becomes a set target speed by the parts, relating to a boiler apparatus and a second frequency control unit for controlling the value of the second frequency.

  Further, the boiler device stores a combustion state acquisition unit that acquires the combustion state of the boiler device, a plurality of combustion states, and a plurality of target speeds that are respectively set corresponding to the plurality of combustion states in association with each other. A storage unit, wherein the second frequency control unit extracts a target speed corresponding to the combustion state acquired by the combustion state acquisition unit from the storage unit, and is calculated by the water level change amount calculation unit. It is preferable to control the value of the second frequency so that the change speed of the water level becomes the extracted target speed.

  According to the boiler device of the present invention, it is possible to effectively suppress boiling of feed water in the feed water heater without increasing the manufacturing cost.

It is a figure showing the whole boiler device composition concerning one embodiment of the present invention. It is a functional block diagram which shows the structure of the control apparatus in the boiler apparatus of this invention. It is a flowchart which shows the flow of the water supply control of a boiler apparatus.

  Hereinafter, a preferred embodiment of the boiler device 1 of the present invention will be described with reference to the drawings. The boiler device 1 of this embodiment is a steam boiler that generates steam by heating water, and supplies steam to the load device 50 that uses steam.

As shown in FIG. 1, the boiler apparatus 1 of this embodiment is the boiler main body 10, the feed water line L1, the economizer 20 as a feed water heater, the fuel supply line L2, the steam supply line L3, and the boiler apparatus 1. And a control device 100 for controlling the operation of
In addition, the “line” in this specification is a general term for a line capable of flowing a fluid such as a flow path, a radial path, and a pipeline. Each line is provided with devices such as various valves, various sensors, check valves, orifices, strainers and the like as necessary, but the illustration is omitted as appropriate in FIG.

The boiler body 10 generates steam by burning fuel and heating feed water. The boiler body 10 includes a cylindrical can body 11 that constitutes an outer shape, a burner 12, an exhaust pipe 13, an in-can pressure sensor 14, and a water level meter 15 as a water level measuring unit.
The can 11 includes a plurality of water pipes, a lower header, an upper header, and a combustion chamber (all not shown). In the can 11, the feed water introduced into the plurality of water pipes from the later-described feed water line L <b> 1 through the lower header is heated by the combustion gas generated by burning the fuel supplied from the fuel supply line L <b> 2 and is vaporized. Is generated.

The burner 12 is disposed on the top of the can 11. The burner 12 burns the fuel supplied to the can body 11 from the fuel supply line L2.
The exhaust cylinder 13 discharges the combustion gas generated in the can 11 and used for generating steam to the outside as exhaust gas. The proximal end side of the exhaust tube 13 is connected to the side surface of the can body 11, and the distal end side extends upward.

The in-can pressure sensor 14 measures the pressure (vapor pressure) inside the can body 11. The water level meter 15 measures the water level inside the can 11 (water levels of a plurality of water pipes).
The in-can pressure sensor 14 and the water level gauge 15 are electrically connected to a control device 100 described later. The pressure inside the can body 11 measured by the pressure sensor 14 inside the can and the water level inside the can body 11 measured by the water level meter 15 are transmitted to the control device 100 as detection signals.

  The water supply line L1 supplies the water supply W1 to the can 11. The upstream end of the water supply line L1 is connected to a water supply source (not shown). The downstream end of the water supply line L1 is connected to the lower portion (lower header) of the can 11. A water supply pump 16 is disposed in the water supply line L1.

The feed water pump 16 creates a pressure difference by the rotation of the impeller (impeller), sucks in the feed water W1, and discharges it toward the can body 11. The feed water pump 16 includes an impeller, a drive motor that rotates the impeller, and an inverter that controls the rotation speed of the drive motor.
The water supply pump 16 is electrically connected to the control device 100. Then, when the inverter inputs a predetermined frequency based on the control signal from the control device 100, the drive motor rotates according to the input frequency, and the discharge force of the water supply by the water supply pump 16 is controlled.

  The economizer 20 is disposed in the water supply line L <b> 1 and heats the water supply W <b> 1 supplied to the can body 11 with the combustion gas generated in the can body 11. More specifically, the economizer 20 is configured by passing a part on the downstream side of the water supply pump 16 in the water supply line L <b> 1 through the exhaust pipe 13. The water supply W1 flowing through the water supply line L1 is heated by exchanging heat with the exhaust gas flowing through the exhaust pipe 13, and supplied to the can body 11.

The fuel supply line L2 supplies the burner 12 with the fuel sent from a fuel supply source (not shown).
The steam supply line L3 supplies the load device 50 with the steam W2 generated in the can body 11 (a plurality of water pipes).

  The control device 100 controls the operation of the boiler device 1. In the present embodiment, the boiler device 1 is configured by a stage value control boiler capable of combustion at a plurality of stepwise combustion positions (for example, four positions of a combustion stop position, a low combustion position, a middle combustion position, and a high combustion position). The And the control apparatus 100 controls the combustion state (combustion position) of the boiler apparatus 1, the water supply to the can 11 according to the said combustion state, etc.

  In the present embodiment, the control device 100 controls the frequency at which the water supply pump 16 is driven according to the presence or absence of a water supply request from the can 11, thereby suppressing the water supply from boiling in the economizer 20. That is, the boiling of the water supply in the economizer 20 occurs when the flow of the water supply W1 stagnates in the water supply line L1 when there is no water supply request. On the other hand, when there is no water supply request in the state where the boiler apparatus 1 is burning (when water supply is stopped), the water level inside the can 11 decreases at a predetermined speed.

  Therefore, in the present embodiment, there is no water supply request by controlling the drive frequency (second frequency described later) of the water supply pump 16 when there is no water supply request based on the amount of change in the water level inside the can 11. In this case, the water supply W1 is supplied to the can body 11 at a flow rate that does not increase the water level inside the can body 11, and the boiling of the water supply W1 in the economizer 20 is suppressed.

  As illustrated in FIG. 2, the control device 100 includes a microprocessor (not shown) including a CPU that functions as the control unit 110 and a memory that functions as the storage unit 120.

  The storage unit 120 stores various information for operating the boiler device 1. In the present embodiment, the storage unit 120 has information on the target water level (band) of the can body 11 set according to the combustion position of the boiler device 1, information on a first frequency described later, and a second frequency described later. The information on the target speed of the water level change used for determining is stored.

  The control unit 110 includes a water supply control unit 111, a water level change amount calculation unit 112, a combustion state acquisition unit 113, and a second frequency control unit 114.

  The water supply control unit 111 drives the water supply pump 16 at the first frequency when there is a water supply request to the can body 11 to supply water to the can body 11, and when there is no water supply request, the first water supply control unit 111 is smaller than the first frequency. The water supply pump 16 is driven at two frequencies.

Here, the first frequency is a frequency at which the water supply pump 16 is driven so that the flow rate of the water supply W1 flowing through the water supply line L1 is equal to or higher than a preset first flow rate when a water supply request is made. It is set and stored in the storage unit 120.
The second frequency is determined by a water level change amount calculation unit 112 and a second frequency control unit 114 which will be described later.

  The water level change amount calculation unit 112 calculates the change speed of the water level measured by the water level meter 15. The water level change rate calculation unit 112 calculates the water level change rate at predetermined time intervals (for example, every second).

  The combustion state acquisition unit 113 acquires the combustion state (combustion position) of the boiler device 1. In the present embodiment, the combustion state acquisition unit 113 acquires information related to the combustion position of the boiler device 1 determined based on the pressure inside the can body measured by the can pressure sensor 14.

The second frequency control unit 114 controls the second frequency so that the change speed of the water level calculated by the water level change amount calculation unit 112 becomes the set target speed when there is no water supply request to the can body 11. To do.
More specifically, the storage unit 120 stores a plurality of combustion positions and a plurality of target speeds respectively set corresponding to the plurality of combustion positions in association with each other. This target speed is set as a speed at which the water level is lowered more slowly than when the water supply to the can 11 is not performed when there is no water supply request, and is stored in the storage unit 120. .
The second frequency control unit 114 first extracts the target speed corresponding to the combustion position acquired by the combustion state acquisition unit 113 from the storage unit 120. Next, the value of the second frequency is controlled so that the change speed of the water level inside the can 11 calculated by the water level change amount calculation unit 112 becomes the target speed.
The control of the second frequency by the second frequency control unit 114 is performed by PI control or PID control. That is, when the change speed of the water level calculated by the water level change amount calculation unit 112 is faster than the target speed, the second frequency control unit 114 increases the second frequency and canisters the water W1 supplied by the water supply pump 16. The supply amount to 11 is increased. When the change speed of the water level calculated by the water level change amount calculation unit 112 is slower than the target speed, the second frequency control unit 114 decreases the second frequency and canister the water supply W1 by the water supply pump 16. 11 is reduced.

  Next, the flow of water supply control of the boiler device 1 of the present embodiment will be described with reference to FIG. FIG. 3 is a flowchart showing a flow of water supply control in the boiler device 1 of the first embodiment.

  First, in step ST1, the combustion state acquisition unit 113 acquires the combustion state (combustion position) of the boiler device 1. Then, the process proceeds to step ST2.

  In step ST <b> 2, the control unit 110 determines whether there is a water supply request to the can 11. When it is determined by the control unit 110 that there is a water supply request to the can body 11 (YES), the process proceeds to step ST3. If the control unit 110 determines that there is no water supply request to the can body 11 (NO), the process proceeds to step ST4.

  In step ST3, the water supply control unit 111 drives the water supply pump 16 at the first frequency to supply the can body 11 with the water supply W1 at the first flow rate. Then, the process returns to step ST1.

  In step ST <b> 4, the water level change amount calculation unit 112 calculates the water level change rate measured by the water level gauge 15. Then, the process proceeds to step ST5.

  In step ST <b> 5, the control unit 110 extracts from the storage unit 120 the value of the target speed set according to the combustion position of the boiler device 1 acquired by the combustion state acquisition unit 113. Then, the process proceeds to step ST6.

  In step ST6, the second frequency control unit 114 calculates the second frequency so that the water level change rate calculated by the water level change amount calculation unit 112 becomes the extracted target speed. Then, the process proceeds to step ST7.

  In step ST7, the water supply controller 111 drives the water supply pump 16 at the second frequency to supply the water supply W1 to the can body 11. Then, the process returns to step ST1.

  According to the boiler apparatus 1 of this embodiment demonstrated above, there exist the following effects.

  (1) The boiler device 1 is driven by the economizer 20, the water level meter 15, the feed water pump 16 driven according to the input frequency, and the feed water pump 16 is driven at the first frequency when there is a feed water request. When there is no request, the water supply control unit 111 that drives the water supply pump 16 at a second frequency lower than the first frequency, the water level change amount calculation unit 112 that calculates the change rate of the water level, and there is no water supply request to the can body In this case, a second frequency control unit 114 that controls the value of the second frequency so that the water level change rate calculated by the water level change amount calculation unit 112 becomes the set target speed is included. Thereby, when there is no water supply request | requirement, since the water supply to the can body 11 can be performed with the flow volume which does not raise the water level of the can body 11, the water supply W1 can be prevented from staying in the economizer 20 and boiling. Therefore, since continuous water supply control is performed without providing a water supply flow meter, it is possible to suppress boiling of the water supply W1 in the economizer 20 without increasing the manufacturing cost.

  (2) When the combustion position of the boiler apparatus 1 is high, the evaporation rate of the feed water in the can 11 is faster than when the combustion position is low. Therefore, when there is no water supply request, the flow rate (second flow rate) of the feed water W1 that can be circulated through the feed water line L1 within a range in which the water level of the can 11 does not rise is lower when the combustion position is higher. Larger than the case. Therefore, the boiler device 1 includes a combustion state acquisition unit 113 that acquires the combustion state (combustion position) of the boiler device 1, and the storage unit 120 includes a plurality of combustion states (combustion positions) and the plurality of combustions. A plurality of target velocities set corresponding to the states are stored in association with each other. Thereby, when there is no water supply request | requirement, since the water supply W1 can be distribute | circulated with a more suitable flow volume according to the combustion state of the boiler apparatus 1, the boiling of the water supply W1 in the economizer 20 can be suppressed more suitably.

As mentioned above, although each preferred embodiment of the boiler apparatus of the present invention was described, the present invention is not limited to the above-mentioned embodiment, and can be changed suitably.
For example, in the present embodiment, the boiler device is configured by a step value control boiler, but the present invention is not limited to this. That is, you may comprise a boiler apparatus with the continuous control boiler which can change a combustion amount continuously.

1 Boiler device 11 Can body 15 Water level gauge (water level measuring part)
16 Water supply pump 20 Economizer (Water heater)
111 Water Supply Control Unit 112 Water Level Change Calculation Unit 113 Combustion State Acquisition Unit 114 Second Frequency Control Unit 120 Storage Unit L1 Water Supply Line

Claims (1)

A boiler device that burns fuel to generate steam from feed water,
Can body,
A water supply line for supplying water to the can body;
A feed water heater that heats the feed water that is disposed in the feed water line and is supplied to the can body by combustion gas generated by burning the fuel;
A water supply pump arranged in the water supply line and driven according to the input frequency;
When there is a water supply request to the can body, the water pump is driven at a first frequency to supply water to the can body, and when there is no water supply request, at a second frequency smaller than the first frequency. A water supply control unit for driving the water supply pump;
A water level measuring unit for measuring the water level inside the can body;
A water level change amount calculating unit for calculating a change rate of the water level measured by the water level measuring unit;
Second frequency control for controlling the value of the second frequency so that the change speed of the water level calculated by the water level change amount calculation unit becomes a set target speed when there is no water supply request to the can body. And
A combustion state acquisition unit for acquiring the combustion state of the boiler device;
A storage unit that associates and stores a plurality of combustion states and a plurality of target speeds respectively set corresponding to the plurality of combustion states ;
The second frequency control unit extracts a target speed corresponding to the combustion state acquired by the combustion state acquisition unit from the storage unit, and a water level change rate calculated by the water level change amount calculation unit is extracted. boiler apparatus that controls the value of the second frequency so that the target speed.

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