JP5692807B2 - Multi-can boiler - Google Patents

Description

  The present invention relates to a multi-can installed boiler that adjusts the amount of steam supplied by changing the number of combustion.

  A multi-can installation boiler comprising a plurality of boilers and a number control device for controlling the number of combustion of the boilers is widely used. The unit control device controls the combustion amount of the boiler so that the pressure value of the steam supplied from the boiler is maintained within the pressure adjustment range, and adjusts the steam supply amount by increasing or decreasing the combustion amount. . The boiler combustion amount adjustment is generally a boiler that adjusts the combustion amount step by step as described in Japanese Patent No. 2294080, and includes three-position combustion control of high combustion, low combustion, and standby for combustion, and high combustion.・ Four-position combustion control of medium combustion, low combustion, and combustion standby is performed.

  FIG. 4 shows a combustion pattern when the number of boilers is controlled by three boilers that perform combustion control at four positions of high combustion, medium combustion, low combustion, and combustion standby. In the figure, the combustion state of the boiler is indicated by “H” for high combustion, “M” for intermediate combustion, “L” for low combustion, and “−” for standby for combustion. In an individual boiler, assuming that the combustion amount at high combustion is 100%, the combustion amount is 66.7% for medium combustion and 33.3% for low combustion. In FIG. 4, the combustion amount in each combustion state when the combustion amount in the entire system of the multi-can installation boiler is 100% is shown. Combustion volume of the entire system is 0% when all boilers are on standby, 11.1% when there is only one low combustion, 22.2% when there is only one medium combustion, and high combustion If there is only one, it will be 33.3%, and if all three boilers are in high combustion, it will be 100%. In this example, the combustion amount in one high combustion unit and the combustion amount in three low combustion units are equal, and the combustion amount in one medium combustion unit and the combustion amount in two low combustion units are equal. Therefore, in the case of “H--”, in the case of “ML-”, in the case of “LLL”, the combustion amounts are all the same 33.3%.

  In the figure, the reason why the route for increasing the combustion amount is different from the route for decreasing the combustion amount is to reduce the increase or decrease in the number of combustion. When changing the combustion amount with a boiler, when changing between low combustion and middle combustion, or between middle combustion and high combustion, it is only necessary to change the supply amount of fuel and combustion air It can be changed in a short time. However, when combustion is started from a state where combustion is stopped, a preparation step such as furnace ventilation is required. Further, since steam cannot be supplied until the steam generation temperature rises from the cold can state, it takes a relatively long time to start supplying steam from the output of the combustion command. In addition, there is a problem that the amount of heat released increases due to ventilation in the furnace that is performed when combustion starts and stops.

  Therefore, in the unit control of the multi-can boiler, the unit control pattern is determined so that the change in the number of combustion is reduced. For example, when the combustion amount is increased by one step from “H−”, “HL−” is used. However, when the combustion amount is decreased by one step from “HL−”, it is not returned to “H−−”. Let it be “ML-”. In this case, if "HL-" is returned to "H--", then when the combustion amount increases, combustion of one boiler that has stopped combustion must be started, and steam is immediately generated. Since steam cannot be supplied, the increase in the steam supply amount is delayed and the steam pressure value decreases. However, when "ML-" is set, the combustion amount can be increased by increasing the combustion rate of one of the medium combustion units. In this case, the steam supply amount can be increased quickly, so that the steam pressure Decrease in value can be suppressed. Therefore, the change of the combustion amount is dealt with only by changing the combustion state within the same number of combustion as much as possible, and the number of combustion is changed only when the change of the number of combustion is unavoidable.

Japanese Patent No. 294080

  The problem to be solved by the present invention is to install a plurality of boilers that can adjust the combustion amount in stages, and to maintain the pressure value of the steam supplied from the boiler within the adjustment range. An object of the present invention is to provide a multi-can installation boiler that controls the number of units with higher followability to load fluctuations than conventional ones in a multi-can installation boiler that controls the combustion amount of each boiler.

  The invention according to claim 1 is provided with a plurality of boilers that adjust the combustion amount in stages, such as high combustion, low combustion, combustion standby, high combustion, medium combustion, low combustion, combustion standby, In a multi-can installation boiler that controls the combustion amount of each boiler so that the pressure value of the steam supplied by the boiler is maintained within the pressure adjustment range, the combustion amount set in stages in the boiler is When low combustion is set so that the difference in low combustion is narrower than between other combustion amounts, and when the combustion amount is changed by fluctuations in the steam pressure value, It is characterized in that the change in the combustion amount between other combustion amounts is given priority over the change in the combustion amount during low combustion.

  The invention according to claim 2 is characterized in that, in the multi-can boiler, the combustion amount change between the combustion amounts with the largest difference in the combustion amount is performed with higher priority. .

  According to the third aspect of the present invention, in the multi-can boiler, when the amount of combustion is increased, if the number of burned boilers is less than a preset number increase pattern setting value, priority is given to an increase in the number of burned units. When the number of boiler combustions becomes equal to or greater than the number increase pattern set value, priority is given to increasing the combustion amount without changing the number of combustions.

  By implementing the present invention, when the change in the amount of steam is required and the change in the amount of combustion is performed, the change in the amount of steam supplied can be greatly changed at an early stage. As a result, it can be expected to improve the follow-up performance of the unit control with respect to the load fluctuation.

Flow chart of boiler with multiple cans Explanatory diagram of combustion pattern in one embodiment of the present invention Explanatory drawing of combustion pattern in another embodiment of the present invention Explanatory diagram of combustion pattern in the prior art Explanatory diagram of combustion pattern in the prior art

  An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a flowchart of a multi-can installation boiler system in one embodiment of the present invention, FIGS. 2 and 3 are explanatory diagrams of combustion patterns in the embodiment of the present invention, and FIGS. 4 and 5 are conventional techniques for comparison. It is a combustion pattern explanatory drawing. FIGS. 3 and 5 show the case where the setting value of the unit increase pattern is set to three, and when the number of boiler combustion units is less than the unit increase pattern set value, the operation giving the highest priority to changing the number of combustion units is performed. It is. 2 and 4 show the case where the operation with the highest priority on changing the number of combustion is not performed (the set value of the number increase pattern is one).

  The set value of the number increase pattern is determined according to the installation environment of the multi-can installation boiler. For example, when the load factor variation of the multi-can boiler is small and is low for most of the period, the number increase pattern set value is set to a small number. When the number increase pattern set value is one as described in FIGS. 2 and 4, the control is performed so that the number of combustion is not increased as much as possible. In this case, even if the load factor increases from 0% to 66%, the number of boilers burned increases only to two, and the third boiler does not burn. Therefore, the number of times of increase / decrease in the number of combustion is reduced. Also, when the load factor is low immediately after the start of the multi-can boiler, but the load factor increases rapidly when the factory operation is started, the number increase pattern set value is set to a large number. When the number increase pattern set value is set to 3 as described in FIG. 3 and FIG. 5, the control is performed to increase the number of combustion immediately after starting the multi-can installation boiler. If the combustion amount is increased from the low combustion state, the combustion amount can be increased in a short time. Therefore, if all three boilers start combustion at an early stage, it is possible to follow a subsequent sudden increase in load.

  In FIG. 1, boilers 1 to 3 can be installed in parallel, and a steam header 4 for collecting steam generated in each boiler 1 is provided. The steam pipes 5 are connected between the boilers 1 and the steam headers 4, and the steam generated in the boilers 1 is collected in the steam headers 4 and then sent to a steam use section (not shown). The steam header 4 is provided with a pressure detection device 6 that detects a steam pressure value, and the steam pressure value detected by the pressure detection device 6 is sent to the number control device 3. In the number control device 3, a combustion pattern that determines the number of combustion of boilers is set according to the steam pressure value, and the number control device 3 determines whether or not combustion is performed in each boiler. Each boiler is provided with an operation control device 2, and the operation control device 2 receives the combustion request signal from the number control device 3 and burns the boiler.

  The number control of the boiler performed by the number control device 3 is performed based on the combustion pattern set in the number control device 3, and the lower the steam pressure value detected by the pressure detection device 6, the more the combustion amount of the boiler is increased. The higher the steam pressure value, the lower the combustion amount. When the amount of steam generated is larger than the amount of steam used, the steam pressure value increases, and when the amount of steam generated is smaller than the amount of steam used, the steam pressure value decreases. Therefore, the number control device 3 reduces the combustion amount of the boiler if the steam pressure value is high, and increases the combustion amount of the boiler if the steam pressure value is low so that the steam pressure value is kept within the control pressure range. Implement control.

  In the number control device 3, priority is set for each boiler 1, and it is determined which combustion is performed from the highest priority to the highest priority. The combustion pattern will be described based on FIG. The boiler controls the amount of combustion at four positions: high combustion, medium combustion, low combustion, and combustion standby, so that the difference in combustion amount between standby and low combustion is narrower than other combustion amounts. Set low combustion. Further, the difference in the combustion amount between the low combustion and the medium combustion and the difference in the combustion amount between the medium combustion and the high combustion are also made different. In this embodiment, it is assumed that the low combustion is 20% of the high combustion and the middle combustion is the combustion amount of 50% of the high combustion. In this case, the difference in the combustion amount between standby and low combustion is 20%, the difference in combustion amount between low combustion and medium combustion is 30%, and the difference in combustion amount between medium combustion and high combustion is 50%. .

  In the figure, the combustion state of the boiler is indicated by “H” for high combustion, “M” for intermediate combustion, “L” for low combustion, and “−” for standby for combustion. Moreover, the combustion amount in each combustion state when the combustion amount when all the three installed boilers having the same capacity perform high combustion is assumed to be 100% is described. Low combustion is 20% of high combustion, medium combustion is 50% of high combustion, and the number of installed boilers is 3, so the amount of combustion for the entire multi-can boiler is 6.7% , 16.7% for one medium combustion unit and 33.3% for one high combustion unit. In this case, the difference in the combustion amount between standby combustion and low combustion in one boiler is 6.7%, the difference between low combustion and medium combustion is 10.0%, and the difference between medium combustion and high combustion is 16. 7%. (There is an apparent shift due to rounding.)

  In the case of FIG. 4 of the conventional example, one low combustion unit was 11.1%, one middle combustion unit was 22.2%, and one high combustion unit was 33.3%. Therefore, “H--”, “ML-” ”And“ LLL ”are all burned up to 33.3%. However, in this example, the ratio of low combustion / medium combustion / high combustion is different, so that “H--” is 33.3%, “ML-” is 23.3%, and “LLL” is 20.0%. It is different in each. In this embodiment, since the number control is performed so that the increase / decrease in the number of combustion is reduced, the basic setting is the same as in FIG. 4, but is partially different from FIG.

  The idea of the present invention is that when changing the combustion amount, priority is given to changing the combustion amount in a portion where the difference in the combustion amount is set large. When the combustion amount is increased from “HL−”, “HM−” is the same in this embodiment and the conventional example. However, when the combustion amount is decreased from “HM−”, it is returned to “HL−”, which is the original combustion state in the conventional example, but in this embodiment, it is changed to “MM−”. . Here, the combustion amount will decrease even if the change from "HM-" to "HL-", but in this case the change in combustion amount will be 10.0% from 50.0% to 40.0%. The change in the combustion amount when changing from “HM−” to “MM−” is 16.7%, from 50.0% to 33.3%.

  When the combustion amount needs to be reduced, the steam pressure value has risen because the steam supply amount is excessive, and the increase in the steam pressure value is stopped by reducing the combustion amount. If so, the effect of stopping the increase in the steam pressure value is greater when the combustion amount is 33.3% than when the combustion amount is 40.0%. In other words, when reducing the combustion amount, if a high combustion boiler exists, priority is given to changing the high combustion with the largest difference in combustion amount to medium combustion, and if there is no high combustion boiler, The steam supply amount is changed quickly by giving priority to the low combustion of the medium combustion boiler.

  Further, when the combustion amount is increased after “MM−” is set, it is returned to “HM−”, and when the combustion amount is decreased from “MM−”, it is changed to “ML−”. . When the combustion amount is increased from “ML−”, it is changed to “HL−” instead of returning to “MM−”. Even when increasing the amount of combustion, if there is a medium-burning boiler, the highest priority is to make the medium combustion high, and if there is a low-burning boiler without medium combustion, the low combustion is set to medium combustion. This is the next priority. When there is neither medium combustion nor low combustion and only a combustion standby boiler increases the combustion amount, the combustion standby boiler is set to low combustion.

  The combustion amount is decreased in the state where there is both high combustion and medium combustion, when changing from “HHM” to “HMM”, when changing from “HMM” to “MMM”, from “HML” to “MML”. There is a case to change to. In this case as well, the change is performed with priority given to changing the high combustion to the medium combustion. In addition, the combustion amount is increased in a state where there are both medium combustion and low combustion, when changing from “MLL” to “HLL”, when changing from “MML” to “HML”, from “HML” to “HML” It may be changed to “HHL”. Also in this case, the change is performed with priority given to changing the middle combustion to the high combustion.

  In this embodiment, when the combustion amount is increased in a state where there is a medium combustion boiler and a low combustion boiler, the effect of increasing the combustion amount is larger when the middle combustion is set to the higher combustion than when the low combustion is changed to the middle combustion. When the combustion amount is reduced in a state where there are a high combustion boiler and a medium combustion boiler, the effect of reducing the combustion amount is greater when the high combustion is set to the intermediate combustion than to reduce the intermediate combustion to the low combustion. Therefore, the effect of preventing the decrease in the steam pressure value and the prevention of the increase in the steam pressure value can be enhanced at an earlier stage by performing the above, and an improvement in the followability to the load fluctuation can be expected.

  For example, in FIG. 2, when the steam pressure value rises by three stages from “HHH”, the combustion state is “MMM” and the total combustion amount becomes 50.0%. In the case of FIG. 4, when the steam pressure value is increased by the same three levels from “HHH”, it is “HML” and the total combustion amount is 66.7%. When the combustion amount is decreased by increasing the steam pressure value, the amount of combustion in FIG. 2 of the present invention is larger than that in FIG. 4 of the prior art, so that the followability to load fluctuation is improved accordingly. become.

  In another embodiment shown in FIG. 3 and FIG. 5 corresponding thereto, when the number of burned boilers is less than 3 which is the number increase pattern set value, an operation that gives the highest priority to the change in the number of burned is performed. In this case, the number of combustion increases at an early stage is different from that of the embodiment of FIG. 2, but other concepts are the same as those of the embodiment of FIG. In the case of FIG. 3 as well, when increasing the amount of combustion, when there is a medium combustion boiler, the highest priority is given to making the middle combustion high combustion, and when there is a low combustion boiler without medium combustion The next priority is to make low combustion medium combustion. If neither medium combustion nor low combustion is present and only the combustion standby boiler increases the combustion amount, the combustion standby boiler is set to low combustion. In addition, when reducing the amount of combustion, when there is a high combustion boiler, the highest priority should be given to high combustion as medium combustion, and when there is no high combustion and there is a medium combustion boiler, medium combustion is reduced. The next priority is to burn. When neither high combustion nor medium combustion is present and only a low combustion boiler reduces the combustion amount, the low combustion boiler is set as a combustion standby.

  The combustion amount is decreased in the state where there is both high combustion and medium combustion, when changing from “HHM” to “HMM”, when changing from “HMM” to “MMM”, from “HML” to “MML”. It is a case to change to. In this case as well, the change is made with priority given to changing the high combustion to the medium combustion. In addition, the combustion amount is increased in a state where there are both medium combustion and low combustion, when changing from “MLL” to “HLL”, when changing from “MML” to “HML”, from “HML” to “HML” It may be changed to “HHL”. Also in this case, the change is performed with priority given to changing the middle combustion to the high combustion.

  The present invention is not limited to the embodiments described above, and many modifications can be made by those having ordinary knowledge in the art within the technical idea of the present invention.

1 boiler
2 Operation control device
3 Number control device 4 Steam header 5 Steam piping 6 Pressure detection device

Claims (3)

  The pressure value of the steam supplied by the boiler is installed with multiple boilers that adjust the combustion amount in stages, such as high combustion, low combustion, standby for combustion, high combustion, medium combustion, low combustion, standby for combustion In a multi-can installed boiler that controls the amount of combustion in each boiler so that is maintained within the pressure adjustment range, the amount of combustion that is set in stages in the boiler is the difference between combustion standby and low combustion. If low combustion is set so that it is narrower than that, and the combustion amount is changed by changing the steam pressure value, the combustion amount is changed between standby and low combustion when the difference in combustion amount is set small A multi-can installation boiler characterized in that the combustion amount change between other combustion amounts is prioritized.   2. The multi-can installation boiler according to claim 1, wherein the combustion amount change between the combustion amounts with the largest difference in combustion amount is performed with higher priority. In the multi-can boiler according to claim 1 or 2, when the amount of combustion is increased, if the number of boilers is less than a preset number increase pattern set value, priority is given to increasing the number of combustion. A multi-can installation boiler characterized in that, when the number of boilers to be burned is equal to or greater than the number increase pattern setting value, priority is given to increasing the combustion amount without changing the number of combustion.

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