JP2018204821A - boiler - Google Patents

Abstract

To provide a boiler capable of suitably controlling a water level in the case the components of a fuel gas are changed.SOLUTION: Provided is a boiler 1 comprising: a can body 10 including a water pipe 12; a fuel feed line 50 feeding a fuel gas to the can body 10; a water level control unit 81 controlling the water level of the water pipe 12 according to combustion conditions; a heat quantity acquisition unit 82 acquiring the heat quantity of the fuel gas fed to the can body 10; and a water level correction unit 83 correcting the water level of the water pipe 12 based on the heat quantity acquired by the heat quantity acquisition unit 82 and the pre-set standard heat quantity of the fuel gas.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a boiler.

  2. Description of the Related Art Conventionally, there has been known a boiler that includes a can having a plurality of water pipes, heats water inside the water pipe by burning fuel gas, and generates steam. In such a boiler, the water level of the water pipe is controlled according to the combustion state (see, for example, Patent Document 1). Specifically, when the combustion state of the boiler is high, the water level of the water pipe is set low in order to prevent a decrease in the dryness of the steam due to the intense boiling of water inside the water pipe. When the combustion state of the boiler is low, the water level of the water pipe is set high in order to prevent the water pipe from overheating.

JP-A-6-147407

  By the way, LNG (Liquid Natural Gas) is widely spread as a fuel gas due to the increase in environmental awareness. One method for supplying LNG is so-called LNG satellite supply in which LNG is transported in a liquid state and vaporized at a supply destination that uses LNG. Although LNG satellite supply can reduce the introduction cost and is used in various fields, the fuel gas tends to be more susceptible to the external environment than the method of transporting the fuel gas through the pipeline. .

  For example, LNG may be supplied to the boiler in a state different from the component ratio assumed by the difference in the specific gravity of the gas constituting the LNG during the vaporization process, the temperature of the vaporization process, or the like. When such component fluctuations occur in the fuel gas, the calorific value of the fuel gas supplied to the boiler will fluctuate.

  The heating value of the fuel gas used in the boiler is set in advance, and the combustion state of the boiler is associated with the water level of the water pipe corresponding to the combustion state based on the set heating value (reference heating value). It has been. Therefore, if the calorific value of the fuel gas supplied to the boiler changes, the water level controlled corresponding to the combustion state based on the reference calorific value will not match the appropriate water level corresponding to the actual combustion state. End up.

  Therefore, an object of this invention is to provide the boiler which can control a water level suitably, when the component of fuel gas changes.

  The present inventor supplies a can body having a water pipe, a fuel supply line that supplies fuel gas to the can body, a water level control unit that controls the water level of the water pipe according to a combustion state, and the can body. The water level of the water pipe is corrected based on a calorific value acquisition unit that acquires the calorific value of the fuel gas, a calorific value acquired by the calorific value acquisition unit, and a preset reference calorific value of the fuel gas. And a water level correction unit.

  The water level correction unit corrects the water level so that the water level of the water pipe is higher when the heat generation amount acquired by the heat generation amount acquisition unit is lower than the reference heat generation amount, and is acquired by the heat generation amount acquisition unit. When the generated calorific value is higher than the reference calorific value, it is preferable to correct the water level so that the water level of the water pipe is lowered.

  Further, it is preferable that the apparatus further includes a calorific value detection unit that is disposed in the fuel supply line and detects the calorific value of the fuel gas, and the calorific value acquisition unit acquires the calorific value detected by the calorific value detection unit.

  According to the boiler of this invention, when the component of fuel gas changes, a water level can be controlled suitably.

It is a figure showing typically one embodiment of the boiler of the present invention. It is a block diagram which shows the structure of a control part.

Hereinafter, a preferred embodiment of the boiler of the present invention will be described with reference to the drawings. The boiler 1 of the present embodiment is a steam boiler that generates steam by heating water, and supplies steam to a load device (not shown).
The boiler 1 of this embodiment includes a can body 10, a blower 20 that sends combustion air to the can body 10, an air supply duct 30 that connects the can body 10 and the blower 20, and the combustion air circulates, and the can body. An exhaust pipe 80 through which combustion gas (exhaust gas) discharged from 10 circulates, a fuel supply line 50 for supplying fuel gas to the can body 10, a water supply line 60 for supplying water to the can body 10, and fuel gas and combustion And a control device 70 for controlling the supply amount of working air and the like.

  The can 10 includes a boiler housing 11, a plurality of water pipes 12, a lower header 13, an upper header 14, and a burner 15.

  The boiler casing 11 constitutes the outer shape of the can body 10. An air supply port 16 is formed on one side surface of the boiler housing 11, and an exhaust port 17 is formed on a side surface opposite to the side surface on which the air supply port 16 is formed.

  The plurality of water pipes 12 are disposed so as to extend in the vertical direction inside the boiler housing 11 and are disposed at predetermined intervals in the longitudinal direction and the width direction of the boiler housing 11.

  The lower header 13 is disposed at the lower part of the boiler casing 11. The lower header 13 is connected to the lower ends of the plurality of water pipes 12. The upper header 14 is disposed on the upper portion of the boiler casing 11. The upper header 14 is connected to the upper ends of the plurality of water pipes 12.

  The burner 15 is disposed in the air supply port 16. The mixture of fuel gas and combustion air is burned by the burner 15, and the water in the water pipe 12 is heated to generate steam.

  The blower 20 includes a blower body 21 having a fan and a motor that rotates the fan, and an inverter 22 that increases or decreases the number of rotations of the fan (motor). The blower 20 feeds combustion air into the can body 10 when the fan rotates at a predetermined rotation speed in accordance with the frequency input to the inverter 22.

  In the present embodiment, the flow rate of the combustion air is set according to a required load required from a load device (not shown). The blower 20 is controlled by the control device 70 via the inverter 22 so that the flow rate of the fuel air is set.

The air supply duct 30 supplies combustion air to be mixed with the fuel gas to the can body 10. The air supply duct 30 has an upstream end connected to the blower 20 and a downstream end connected to the air supply port 16. The air supply duct 30 supplies the combustion air sent from the blower 20 to the can body 10.
In the air supply duct 30, a damper 31, a punching metal 32, and an air differential pressure sensor 33 are arranged.

  The damper 31 is in a closed state in which the combustion air flow path inside the air supply duct 30 is closed and rotated 90 degrees from this closed state to open the combustion air flow path in the air supply duct 30. It is arranged to be rotatable between states.

  The punching metal 32 is a metal plate in which a plurality of through holes are formed, and functions as a combustion air decompression member that decompresses the combustion air that circulates. The punching metal 32 is disposed on the downstream side of the damper 31 inside the air supply duct 30. The punching metal 32 decompresses the combustion air flowing through the damper 31 to the air supply duct 30.

  The air differential pressure sensor 33 is an air flow rate detection unit for detecting the flow rate of combustion air. The air differential pressure sensor 33 detects a differential pressure between the upstream pressure and the downstream pressure of the punching metal 32. The flow rate of the fuel air is calculated based on this differential pressure information.

  The exhaust cylinder 80 is connected to the exhaust port 17 at the base end side and is formed in a cylindrical shape. Combustion gas (exhaust gas) generated in the can body 10 is discharged to the outside of the can body 10 through the exhaust cylinder 80.

The fuel supply line 50 has an upstream side connected to a fuel supply source (not shown) and a downstream side connected to the air supply duct 30. The downstream end of the fuel supply line 50 is connected to the downstream side of the air supply duct 30 from the position where the punching metal 32 is disposed.
In the fuel supply line 50, a fuel gas flow meter 51, a calorimeter 52 as a calorific value detection unit, an on-off valve 53, a governor 54, a flow rate adjusting valve 55, an orifice 56, and a nozzle 57 are arranged. .

  The fuel gas flow meter 51 measures the flow rate of the fuel gas flowing through the fuel supply line 50. The fuel gas flow meter 51 of the present embodiment is disposed on the most upstream side of the fuel supply line 50.

  The calorimeter 52 acquires the calorific value of the fuel gas. The calorimeter 52 is disposed downstream of the fuel gas flow meter 51 in the fuel supply line 50. As the calorimeter 52, an appropriate one such as one that samples and measures the fuel gas flowing through the fuel supply line 50 and obtains the calorific value thereof can be adopted.

  The on-off valve 53 opens or closes the fuel supply line 50 to supply and stop the fuel gas. The on-off valve 53 of the present embodiment is disposed downstream of the fuel gas flow meter 51 in the fuel supply line 50.

  The governor 54 functions as a pressure adjusting means for suppressing pressure fluctuation of the fuel gas flowing through the fuel supply line 50. The governor 54 is disposed downstream of the on-off valve 53 in the fuel supply line 50.

  The flow rate adjustment valve 55 adjusts the flow rate of the fuel gas flowing through the fuel supply line 50. The flow rate adjustment valve 55 is configured to be able to adjust the opening degree. The flow rate adjustment valve 55 is disposed on the downstream side of the governor 54 in the fuel supply line 50.

  The orifice 56 functions as a fuel gas decompression member that decompresses the fuel gas flowing through the fuel supply line 50. The orifice 56 is disposed on the downstream side of the flow rate adjustment valve 55 in the fuel supply line 50.

  The nozzle 57 is disposed at the downstream end of the fuel supply line 50 and ejects fuel gas into the air supply duct 30. The fuel gas ejected from the nozzle 57 is mixed with the combustion air sent by the blower 20, and the mixed gas is burned by the burner 15.

  The water supply line 60 supplies water to the can body 10. The upstream side of the water supply line 60 is connected to a water supply source (not shown), and the downstream side is connected to the lower header 13. A water supply valve 61 is disposed in the water supply line 60.

Next, the control device 70 will be described. The control device 70 includes a control unit 71 that controls the combustion state of the boiler 1 and a storage unit 72 that stores various types of information.
The control device 70 is electrically connected to each of the sensors described above, and controls the flow rate adjustment valve 55 and the blower 20 based on signals from these sensors and the required load from the load device, and determines the combustion state of the boiler 1. Control. Further, the control device 70 controls the water level of the water pipe 12 by adjusting the opening / closing or opening of the water supply valve 61 according to the combustion state of the boiler 1.

The boiler 1 has a heat value of the fuel gas used in advance, and a suitable water level of the water pipe 12 is set for each combustion state of the boiler 1 based on the set heat value (reference heat value). ing. Specifically, when the combustion state of the boiler 1 is high, the water level of the water pipe 12 is set low in order to prevent a decrease in the dryness of steam due to the intense boiling of water inside the water pipe 12. . Further, when the combustion state of the boiler 1 is low, the water level of the water pipe 12 is set high in order to prevent the water pipe 12 from overheating.
Therefore, if the calorific value of the fuel gas supplied to the boiler 1 changes, the water level controlled corresponding to the combustion state based on the reference calorific value does not match the appropriate water level corresponding to the actual combustion state. End up.

Therefore, in the present embodiment, when the component of the fuel gas supplied to the fuel supply line 50 fluctuates, by correcting the water level of the water pipe 12 set in advance according to the amount of fluctuation of the fuel gas component, Even when the fuel gas component changes, suitable water level control is realized.
In order to realize such a function, as shown in FIG. 2, the control unit 71 includes a water level control unit 81, a calorific value acquisition unit 82, and a water level correction unit 83.

  The water level control unit 81 controls the water level of the water pipe 12 according to the combustion state of the boiler 1. For example, when the boiler 1 is a stage value control boiler that burns at a plurality of staged combustion positions, the storage unit 72 associates each combustion position with the water level of the water pipe 12 corresponding to the combustion position. Remembered. And the water level control part 81 determines the target water level of the water pipe 12 according to the combustion position of the boiler 1, and controls water supply so that the water level of the water pipe 12 may become the set target water level. When the boiler 1 is a continuous control boiler capable of continuously increasing or decreasing the combustion amount, the storage unit 72 stores a table in which the combustion amount (combustion rate) of the boiler 1 and the water level of the water pipe 12 are associated with each other. . And the water level control part 81 determines the target water level of the water pipe 12 according to the combustion amount (combustion rate) of the boiler 1, and controls water supply so that the water level of the water pipe 12 becomes the set target water level.

  The calorific value acquisition unit 82 acquires the calorific value of the fuel gas supplied to the can body. In the present embodiment, the calorific value acquisition unit 82 acquires the calorific value of the fuel gas flowing through the fuel supply line 50 measured by the calorimeter 52.

The water level correction unit 83 corrects the water level of the water pipe 12 based on the calorific value acquired by the calorific value acquisition unit 82 and a preset reference calorific value of the fuel gas. In other words, the heat generation amount of the fuel gas used in the boiler 1 is set as the reference heat generation amount in the storage unit 72 of the control device 70. And the water level correction | amendment part 83 correct | amends the set target water level, when the difference exceeding the predetermined | prescribed range generate | occur | produces between the calorific value acquired by the calorific value acquisition part 82, and the reference | standard calorific value.
In this embodiment, the water level correction | amendment part 83 correct | amends a target water level so that the water level of the water pipe 12 may become high, when the calorific value acquired by the calorific value acquisition part 82 is lower than a reference | standard calorific value. Further, when the heat generation amount acquired by the heat generation amount acquisition unit 82 is higher than the reference heat generation amount, the target water level is corrected so that the water level of the water pipe 12 is lowered.

Next, the flow of water level control in this embodiment will be described.
In the state where the boiler 1 is burning, the water level control unit 81 controls the water supply valve 61 with the water level set corresponding to the combustion state of the boiler 1 as the target water level, and controls the water level of the water pipe 12.
On the other hand, the calorific value acquisition unit 82 acquires the calorific value of the fuel gas flowing through the fuel supply line 50 measured by the calorimeter 52.

The water level correction unit 83 monitors the heat generation amount of the fuel gas acquired by the heat generation amount acquisition unit 82, and a difference exceeding a predetermined range between the heat generation amount of the fuel gas and the reference heat generation amount stored in the storage unit 72. The target water level is corrected in the event that occurs.
Thereby, when the calorific value of the fuel gas supplied to the can 10 varies, the water level of the water pipe 12 can be corrected according to the actual combustion state, not the apparent combustion state instructed to the boiler 1. . Thus, the water level can be suitably controlled when the fuel gas component changes.

Here, in the present embodiment, the water level correction unit 83 is configured such that the heat generation amount acquired by the heat generation amount acquisition unit 82 is lower than the reference heat generation amount (that is, the actual combustion state is lower than the apparent combustion state). The target water level is corrected so that the water level of the water pipe 12 becomes high. In addition, when the heat generation amount acquired by the heat generation amount acquisition unit 82 is higher than the reference heat generation amount (that is, when the actual combustion state is higher than the apparent combustion state), the target water level is set so that the water level of the water pipe 12 is lowered. Correct.
Thereby, when the actual combustion state is lower than the apparent combustion state, overheating of the water tube 12 can be suppressed by increasing the water level of the water tube 12, and the actual combustion state is higher than the apparent combustion state. In that case, by lowering the water level of the water pipe 12, it is possible to suppress a decrease in the dryness of the generated steam.

As mentioned above, although one preferable embodiment of the boiler of this invention was described, this invention is not restrict | limited to the above-mentioned embodiment, It can change suitably.
For example, in the present embodiment, the calorific value acquisition unit 82 acquires the calorific value of the fuel gas measured by the calorimeter 52, but is not limited thereto. That is, when fuel gas (for example, LNG) is supplied from a satellite supply facility to a boiler, the boiler is configured without a calorimeter, and the calorific value of the fuel gas stored in the satellite supply facility (as determined in advance). May be acquired by the calorific value acquisition unit.

DESCRIPTION OF SYMBOLS 1 Boiler 10 Can body 12 Water pipe 50 Fuel supply line 81 Water level control part 82 Calorific value acquisition part 83 Water level correction part 52 Calorimeter (calorific value detection part)

Claims (3)

A can having a water pipe;
A fuel supply line for supplying fuel gas to the can body;
A water level control unit for controlling the water level of the water pipe according to the combustion state;
A calorific value acquisition unit for acquiring the calorific value of the fuel gas supplied to the can;
A boiler comprising a water level correction unit that corrects the water level of the water pipe based on a heat generation amount acquired by the heat generation amount acquisition unit and a preset reference heat generation amount of fuel gas. The water level correction unit is
When the calorific value acquired by the calorific value acquisition unit is lower than the reference calorific value, the water level is corrected so that the water level of the water pipe becomes high,
The boiler according to claim 1, wherein when the heat generation amount acquired by the heat generation amount acquisition unit is higher than the reference heat generation amount, the water level is corrected so that the water level of the water pipe is lowered. A calorific value detection unit arranged in the fuel supply line for detecting the calorific value of the fuel gas;
The boiler according to claim 1 or 2, wherein the heat generation amount acquisition unit acquires the heat generation amount detected by the heat amount detection unit.

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