JP2001201001A - Multi-boiler installing system provded with device for controlling the number of boilers - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a phenomenon of generating vibration deteriorating stability of steam pressure in a multi-boiler installing system for a boiler. SOLUTION: There is provided a multi-boiler installing system for a boiler in which a plurality of boilers capable of adjusting an amount of combustion are installed. After steam generated at each of the boilers are collected, the collected steam are supplied to a steam application equipment 2 and a device 3 for controlling the number of boilers is installed to perform controlling over the number of boilers, in such a way that a steam pressure value at a steam complex segment 4 may keep less than a predetermined control pressure range. The number of boilers to perform controlling combustion is calculated in advance as the number of boilers performing combustion in reference to calories consumed at the steam application equipment 2. In the case that the steam pressure value exceeds an upper limit pressure in the range of control pressure with the upper limit pressure of the control pressure range being applied as an interface, combustions at all the boilers are stopped. In turn, if the steam pressure value is lower than an upper limit pressure in the range of control pressure, all the boilers corresponding to the calculated number of boilers showing combustion are operated to burn and an amount of combustion of the boiler performing combustion is adjusted in response to the steam pressure value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a boiler multi-can installation system.

[0002]

2. Description of the Related Art A boiler multi-can installation system is known in which a large number of boilers (three or more) are installed and the combustion state of each boiler is adjusted so that the steam pressure is kept within a predetermined control pressure range. . In the case of a multi-can steam boiler installation system, the steam generated by each boiler is collected in a steam header and supplied to equipment that uses steam, and the number of steam boilers is determined based on the steam pressure value detected by a pressure detector installed in the steam header. Perform control. In unit number control, a number of pressure sections are set, the boiler combustion state is determined for each pressure section, and the boiler combustion state to be performed is determined based on which pressure section the steam pressure value detected by the steam header corresponds to. Control the heat output of the boiler. The pressure sections are set at regular intervals, and the heat output of the boiler decreases as the steam pressure value moves to the high pressure side pressure section, and conversely, the heat output of the boiler increases as the steam pressure value moves to the low pressure side pressure section. Since the heat output of the boiler is the amount of steam generated, and the required heat of the equipment using steam is the amount of steam used, if the amount of steam generated is greater than the amount of steam used, the steam pressure at the steam header will increase, Is smaller than the amount of steam used, the steam pressure decreases, and the steam pressure is controlled so as to be kept within the control pressure range.

[0003] In the case of multi-can installation, each boiler controls the combustion in three positions of high combustion, low combustion, and stop, and the low combustion generally uses a boiler having a heat output about half that of the high combustion. It is. In this case, by setting the boiler that is stopped to low combustion or low combustion to high combustion, the heat output increases, and conversely, the boiler that is performing low combustion is stopped or high combustion is performed. By making the boiler low burning, the heat output is reduced. In addition, the unit control consists of a group of multiple boilers,
Combustion is controlled for each set so that the boilers in the set have the same combustion state, and the combustion states of a plurality of boilers may be changed at the same time. When changing the combustion amount between low combustion and high combustion, it can be done only by changing the supply amount of fuel and air, so the steam generation amount can be changed in a short time. When the combustion is started, a relatively long time is required from the combustion start command to the actual start of the generation of steam because a time such as a pre-purge is required.

If the number of boilers is large and the number of pressure sections is increased and the pressure range of the pressure sections is set to be narrow, the steam pressure value is set between the output of the start of combustion and the actual generation of steam. Is reduced to become a pressure section on the lower pressure side, and combustion may be started for a boiler which normally does not need to perform combustion. In this case, when the steam supply starts, the heat output becomes too large, so that the steam pressure sharply increases, and conversely, an output must be performed to reduce the number of burned fuels. Oscillation may occur.

FIG. 3 shows an example of conventional unit control in the case where eight boilers of three-position combustion control for controlling combustion in high combustion, low combustion, and stop and the control pressure width is set to 0.70 MPa to 0.85 MPa. It is. For simplicity, the value of the heat output per boiler is set to 1 for low combustion and 2 for high combustion. Set 15 pressure divisions within the control pressure range of 0.70MPa to 0.85MPa, and two pressure divisions above and below the control pressure width, determine a total of 17 pressure divisions, and determine the boiler combustion state for each pressure division ing. The priority order of combustion is determined for the eight boilers, and combustion is performed in order from the one with the highest priority. The combustion state of the boiler is indicated by "H" for high combustion, "L" for low combustion, and "-" for stop,
The values of the heat output of the entire boiler in each combustion state are described.

[0006] If the steam pressure value is in the pressure section higher than 0.85 MPa, all the boilers are stopped and the heat output value is 0,
When the steam pressure value is in the pressure category of 0.84MPa ~ 0.85MPa, only the boiler with the highest priority is low combustion and the other boilers are stopped, the heat output value is 1, the steam pressure value is 0.83MPa ~
In the case of the pressure category of 0.84MPa, the first and second priority boilers are set to low combustion, the heat output value is 2, the steam pressure value is less than 0.70MPa, and all the boilers are The combustion state is defined as high combustion, until the heat output value becomes 16 (rated heat output of the boiler).

[0007] The amount of heat required in equipment using steam (heat amount WN)
However, when the rated heat output of the boiler is greater than 50%, all the boilers continue to burn, and the amount of steam generated by changing the ratio of high combustion to low combustion in the boiler that is burning If the required heat amount is smaller than 50% of the rated heat output of the boiler, the heat output is adjusted by increasing or decreasing the number of boilers that perform combustion.

[0008] For example, when the value of the required calorific value of the equipment using steam is 4.
5 (heat value WN = 4.5) and the steam pressure value at a certain point in time falls within the pressure range of 0.80 MPa to 0.81 MPa, the unit controller burns five boilers with low combustion. In this case, the value of the heat output is 5, and since the heat output is larger than the required amount of heat, the steam pressure value increases. Steam pressure value is 0.81 ~
When entering the pressure category of 0.82, the unit control device stops the boiler having the fifth priority in performing low combustion and sets the heat output value to 4.

If the heat output value is 4, the steam pressure drops because the heat output becomes smaller than the required amount of heat, and when the steam pressure value falls within the pressure category of 0.80 MPa to 0.81 MPa, the number control unit is given priority. Produces an output that makes the fifth boiler low in combustion. However, when starting the combustion of the boiler whose combustion has been stopped, steam cannot be generated immediately, and the steam pressure value continues to decrease until the fifth priority boiler starts supplying steam. Therefore, if the steam pressure value falls to the pressure range of 0.79 MPa to 0.80 MPa during the preparation for combustion, the unit control device also starts the combustion of the sixth-priority boiler.

When the fifth and sixth priority boilers start burning, the heat output value becomes 6, which is much larger than the required heat quantity (heat quantity WN = 4.5). Soaring. If the steam pressure rises from 0.82MPa to 0.83MPa, the unit controller will stop the three boilers and reduce the value of the heat output to 3, causing an oscillation phenomenon due to repeated large pressure fluctuations Will be done.

[0011] When oscillation is caused, the stability of steam is deteriorated. In addition, the boiler ventilates the furnace every time the combustion starts and stops. Heat is lost, and the life of the device is shortened when the number of times the device is started and stopped is increased.

[0012]

SUMMARY OF THE INVENTION An object of the present invention is to prevent an oscillation phenomenon that deteriorates the stability of steam pressure in a boiler multi-can installation system.

[0013]

A number of boilers capable of controlling the amount of combustion are installed, and the steam generated by each boiler is supplied to a steam-using device after being collected. A boiler multi-can installation system provided with a unit control device for controlling the number of boilers so that the steam pressure value is kept within a predetermined control pressure range. The number of boilers performing the calculation is calculated as the number of combustion units, and when the steam pressure value exceeds the upper limit pressure of the control pressure range, the combustion of all boilers is stopped, and the control pressure range When the pressure falls below the upper limit pressure, all the boilers corresponding to the calculated number of combustion units are burned, and the heat output of the boiler performing combustion is adjusted according to the steam pressure value.

If the boiler controls combustion at three positions of high combustion, low combustion, and stop, the control pressure range is divided by the calculated number of combustion units, and the number of combustion units within the control pressure range is divided. Pressure ranges are set above and below the control pressure range and the control pressure range.All boilers are stopped when the pressure range exceeds the upper limit pressure of the control pressure range. All boilers are operated at low combustion, and the pressure division and combustion state are set so that the lower the pressure division, the lower the number of boilers that perform low combustion and the number of boilers that perform high combustion. Set.

When the number of boilers is controlled by grouping a plurality of boilers, and the boilers in the group control the combustion in units of groups so that the boilers are in the same combustion state, the use of the above-mentioned steam-using equipment Instead of calculating the number of boilers that perform combustion control from the required heat quantity, the number of boilers that perform combustion control is calculated as the number of combustion groups, and the above-described control is performed using the number of combustion groups instead of the number of combustion units.

The number of boilers to be burned is calculated by multiplying the required amount of heat to be used in the steam-using device by a predetermined constant and dividing by the heat output that can be generated by one boiler. It is calculated by multiplying the required amount of heat used by the steam-using device by a predetermined constant and dividing by the heat output that can be generated by a set of boilers, which is a unit of combustion control.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an installation example of a multi-can installation boiler embodying the present invention, and FIG. 2 is an explanatory diagram of pressure divisions and a combustion state of the boiler when the amount of heat required in equipment using steam is small. High combustion
A large number of boilers for performing combustion control at three positions of low combustion and stop are installed, and a steam header 4 for collecting steam generated by each boiler 1 is provided. The generated steam is sent to the steam-using device 2 after being collected in the steam header 4, and the steam header 4 is provided with a pressure detector 6 for detecting the steam pressure. Each boiler is provided with an operation control device 7, and the operation control device 7 receives a combustion request signal from the number control device 3 and controls the boiler combustion.

The number control device 3 is also connected to the pressure detector 6 and the steam-using device 2, and stores a steam pressure value detected by the pressure detector 6 and a value of a necessary heat amount used in the steam-using device 2. The calorie WN is taken in. If the steam-using device 2 has a plurality of heat exchangers, the calorie WN is a value obtained by integrating the calorific values W1 and W2 obtained from the temperature difference and the flow rate on the secondary side of the heat exchanger. The control of the number of boilers performed by the number control device 3 is performed based on the steam pressure value and the amount of heat WN and the combustion state set in the number control device 3, and the lower the steam pressure value detected by the pressure detector 6, the lower the steam pressure value. The heat output is increased, and the higher the steam pressure value, the lower the heat output. The heat output of the boiler is the amount of steam generated, and the required heat of the steam-using equipment is the amount of steam used.If the amount of steam generated is larger than the amount of steam used, the steam pressure increases and the steam generated If the amount is smaller than the amount of steam used, the steam pressure will decrease,
Control is performed so that the steam pressure value is kept within the control pressure range.

In this embodiment, eight three-position combustion control boilers for controlling combustion in high combustion, low combustion, and stop are installed, and the control pressure width is set to 0.70 MPa to 0.85 MPa. The value of the heat output per vehicle is set to 1 in the case of low combustion and 2 in the case of high combustion, which is the same as the condition described in the section of the prior art. Note that the value of the heat output can be determined by previously setting the converted evaporation amount or the actual evaporation amount. In FIG. 2 as well, the high combustion state is represented by "H", the low combustion state is represented by "L", and the stopped state is represented by "-", and the total heat output in each combustion state is numerically described. .

An equation for calculating the number of boilers to be burned is input to the number control device 3.
Multiplied by 1.4 (constant) to the required amount of heat (heat amount WN) to be used in the boiler, the heat output (heat amount W
Determined by dividing by b). When the value of the heat amount WN used in the steam-using device 2 is 4.5 (heat amount WN = 4.5), the heat output value that can be generated by one boiler is the heat output value at the time of high combustion. Since the value is 2 (heat amount Wb = 2), the number control device 3 calculates the heat amount WN = 4.5 and the heat amount Wb = 2 by using the calculation formula of the number of combustion units (the number of combustion units = heat amount WN ×
The number of combustion units is calculated by substituting the heat amount into 1.4 ÷ heat amount Wb). By substituting the value into the calculation formula, the number of combustion units = 4.5 × 1.4 ÷ 2
= 3.15, and three units rounded to 3.15 are the number of combustion units.

The number control device 3 divides the control pressure range by the calculated number of combustion units, that is, by three, and sets three within the control pressure range.
Set two pressure categories. Within the control pressure range of 0.70 MPa to 0.85 MPa, 0.70 MPa to 0.75 MPa, 0.75 MPa to 0.80 MPa, 0.80 MPa
Three pressure sections of MPa to 0.85 MPa are set, and the combustion state of the boiler is set to each of the five pressure sections including 0.85 MPa to 0.70 MPa above and below the control pressure range. For the setting of the combustion state, all boilers are stopped if the pressure section is higher than 0.85 MPa, which is the upper limit of the control pressure range, and three boilers calculated as the number of combustion units are burned in four pressure sections lower than 0.85 MPa. The remaining 5 boilers are not burned.
The combustion state in the pressure category for burning the boiler is 0.80MPa
If the pressure class is ~ 0.85MPa, all three boilers have low combustion.If the pressure class is 0.75MPa ~ 0.80MPa, it is one high combustion and two low combustion units, if the pressure class is 0.70MPa ~ 0.75MPa. If the pressure classification is lower than 0.70MPa, two high boilers and one low combustion boiler, all three boilers are set to high combustion.

The number control device 3 determines the pattern of the combustion state of the boiler according to which pressure category the steam pressure value in the steam header 4 detected by the pressure detector 6 corresponds to. For example, when the steam pressure value is within the pressure range of 0.75 MPa to 0.80 MPa, the unit control device 3 outputs a high combustion request signal to the first-priority boiler, A low combustion request signal is output to the second boiler. The boiler with the highest priority performs high combustion, the second and third boilers perform low combustion, and the steam generated from each boiler collects in the steam header 4. Based on the relationship between the amount of steam generated from the boiler and the amount of steam used in the steam-using device 2, the steam pressure value in the steam header 4 rises or falls. Output a request signal.

When one boiler is set to high combustion and two boilers are set to low combustion, the heat output value is 4, which is smaller than the required heat value of 4.5. It is going down. However, since the pressure width of the pressure section is set as wide as 0.05 MPa, the frequency of the steam pressure value reaching another pressure section decreases as the pressure width increases, and the frequency of changing the steam generation amount is small. Steam pressure value is 0.70MPa ~ 0.75M
When the pressure falls within the Pa pressure category, the unit controller sets the second-priority boiler that has performed low combustion to high combustion and sets the heat output value to 5. Changing the combustion state between low combustion and high combustion only involves changing the supply amounts of fuel and air, so that the heat output can be changed in a short time. Assuming a value of 5 for the heat output, the steam pressure starts to rise. Similarly, when the steam pressure value changes, the heat output decreases when entering the high pressure side pressure section, and increases when entering the low pressure side pressure section.

When the required amount of heat in the steam-using device 2 changes and the number of combustion units calculated by the calculation formula changes, the pressure division based on the newly calculated number of combustion units, The combustion state is reset, and the number is controlled based on the newly determined combustion state.

In this embodiment, the boiler combustion control is performed on a unit basis. However, in the unit number control, a plurality of boilers are grouped, and the boilers in the group are fired on a group basis so as to have the same combustion state. Is also controlled. The case where the number of boilers for performing the combustion control is calculated instead of calculating the number of the boilers for performing the combustion control from the required amount of heat used by the steam-using device is also the same as that of the above-described embodiment in the case where the number of the boilers is controlled. The number is calculated as a number, and the number control is performed using the number of combustion groups instead of the number of combustion units. When controlling the number of units in pairs, the number control device 3
Is input with an expression for calculating the number of combustion units of the boiler, and the number of combustion units is determined by the required amount of heat (heat amount W
N) is multiplied by 1.4 (constant) and divided by the heat output (heat amount Wb) that can be generated by one set of boilers.

4 and 5 show 10 boilers installed and 2 boilers installed.
FIG. 4 shows another embodiment of the present invention, and FIG. 5 shows an example of conventional control. When two boilers having a heat output value of 2 that can be generated by one unit are controlled by a set of two boilers, the heat output value that can be generated by one set of boilers is 4 (heat amount Wb = 4). When the value of the required heat amount in the steam-using device is 8 (heat amount WN = 8), the heat amount WN = 8 and the heat amount Wb = 4 are calculated by the formula for calculating the number of combustion groups (the number of combustion groups = heat amount WN × 1.4}. Substituting into the heat quantity Wb), the number of combustion groups = 8 × 1.4 / 4 = 2.8, and three sets obtained by rounding 2.8 are the number of combustion groups. In the case of FIG. 4, the inside of the control pressure range is divided by the number of combustion groups, and the combustion state is controlled in units of two units, and the control content is the same as in the above-described embodiment.

The number of combustion units or the number of combustion groups is determined in accordance with the required amount of heat in the steam-using equipment 2. If the steam pressure value is lower than the upper limit pressure of the control pressure range, the number of combustion units or the number of combustion groups of the boiler is determined. By changing only the combustion state without changing the combustion temperature, the frequency of starting and stopping the combustion can be extremely reduced, and the oscillation phenomenon occurs even when the required heat amount is less than 50% of the rated heat output. It will not be. Since the start and stop of combustion are small, the amount of heat discharged by ventilation in the furnace every time the start and stop of combustion can be reduced, and the life of the equipment can be prolonged. Also,
Since the balance between the amount of steam used and the amount of steam supplied is not greatly disrupted, and the steam pressure value does not fluctuate greatly, and the interval between the pressure sections is increased, the combustion state is frequently changed with slight pressure fluctuation. Can be eliminated.

[0028]

By practicing the present invention, it is possible to prevent repeated oscillation of starting and stopping combustion, and to obtain effects such as stabilization of steam pressure, improvement of efficiency, and extension of equipment life.

[Brief description of the drawings]

FIG. 1 is an installation example of a boiler multi-can installation system for implementing the present invention.

FIG. 2 is an explanatory view of a pressure section and a boiler combustion state in one embodiment of the present invention.

FIG. 3 is an explanatory diagram of a pressure class and a boiler combustion state in a conventional case.

FIG. 4 is an explanatory diagram of a pressure class and a boiler combustion state in another embodiment of the present invention.

FIG. 5 is an explanatory diagram of a pressure class and a boiler combustion state in a conventional case.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Boiler 2 Equipment using steam 3 Unit control device 4 Steam header 5 Steam piping 6 Pressure detector 7 Operation control device

Claims (4)

[Claims] 1. A large number of boilers capable of controlling the amount of combustion are installed, and steam generated in each boiler is supplied to a steam-using device through a steam collecting section, and a steam pressure value of the steam collecting section is set to a predetermined value. A boiler multi-can installation system equipped with a unit control device that controls the number of boilers so as to keep within the control pressure range, and the number of boilers that perform combustion control is determined based on the required amount of heat used by steam-using equipment. If the steam pressure value exceeds the upper limit pressure of the control pressure range, the combustion of all boilers is stopped, and if the steam pressure value falls below the upper limit pressure of the control pressure range. Is a system for burning all the boilers for the calculated number of combustion units, and a boiler multi-can installation system provided with a unit number control device for adjusting the heat output of the boilers performing combustion in accordance with the steam pressure value. 2. The boiler multi-can installation system provided with the number control device according to claim 1, wherein the boiler controls combustion in three positions of high combustion, low combustion, and stop, and the control pressure Divide by the number of calculated number of combustion units within the width, set the pressure division for the number of combustion units within the control pressure width and the pressure division above and below the control pressure width, and set the pressure division exceeding the upper limit pressure of the control pressure width Then, all the boilers are stopped, and in the pressure section one stage lower than the pressure section, all the boilers for the number of combustion units are operated at low combustion, and the number of the boilers performing low combustion is reduced as the pressure section becomes lower by one step. A multi-can installation system for a boiler provided with a number control device, wherein a pressure division and a combustion state are set so as to increase the number of boilers performing high combustion while reducing the number. 3. The boiler multi-can installation system provided with the number control device according to claim 1 or 2, wherein the number of boilers is controlled by setting a plurality of boilers as a set, and the boilers in the set are in the same combustion state. The number of boilers that perform combustion control is calculated as the number of combustion groups instead of calculating the number of boilers that perform combustion control from the required amount of heat used by the steam-using equipment. And a boiler multi-can installation system provided with a number control device for performing the above-described control with the number of combustion groups instead of the number of combustion units. 4. A multi-can installation system for a boiler provided with the number control device according to claim 1, wherein the number of combustion units is multiplied by a predetermined amount of heat required by the steam-using device, Calculated by dividing by the heat output that can be generated by one boiler. The number of combustion units is calculated by multiplying the required amount of heat used by the steam-using equipment by a predetermined constant, and a set of boilers as a unit of combustion control A boiler multi-can installation system provided with a unit control device, which is calculated by dividing by a heat output that can be generated in the boiler.