JP5586290B2 - Cross-flow boiler device and combustion control method for cross-flow boiler - Google Patents

Description

  The present invention relates to a once-through boiler device, and more particularly to a small multi-tube once-through boiler and a combustion control method for the once-through boiler.

  A simple combustion control method is employed in the combustion control of a once-through boiler device, particularly a small multi-tube once-through boiler. For example, the combustion load factor is set at a plurality of positions, the combustion load factor is selected corresponding to the load on the boiler, and the combustion of the boiler is controlled in stages so that the selected combustion load factor is obtained.

  For example, when the combustion load factor set in the four-position combustion control is low combustion 30%, medium combustion 65%, and high combustion 100%, the boiler load is 30%, 65%, or 100% However, it is only necessary to select the corresponding load factor to control the combustion of the boiler, but in reality the boiler load does not match the set load factor, and the control of the combustion corresponds to the boiler load. The combustion is staged by switching the rate (multi-position combustion control).

  For example, when the load on the boiler is 80%, the combustion is controlled so that the average combustion rate becomes 80% by appropriately switching between 65% medium combustion and 100% high combustion. When the boiler load is 30% or less, for example, 20%, the combustion load factor is controlled to 20% by combining 30% low combustion and combustion stop.

  FIG. 6 illustrates a conventional multi-tube once-through boiler apparatus employing a conventional combustion control method, for example, four-position combustion control.

  In FIG. 6, reference numeral 1 denotes a boiler body, and the boiler body 1 is disposed in a circumferential direction and at a required distance, and is surrounded by a plurality of heating tubes 2 and the heating tubes 2, and has an upper end. A cylindrical combustion chamber 3 whose lower end is closed, an annular lower header 4 connected to the lower part of the heating pipe 2, and an annular upper header 5 connected to the upper part of the heating pipe 2. A burner nozzle 6 for injecting fuel gas into the combustion chamber 3 is attached downward in the center of the upper header 5.

  A water supply pipe 8 is connected to the lower header 4, and the water supply pipe 8 is configured to supply water to the lower header 4 and from the lower header 4 to the water supply pump 9. A check valve 10 is provided to prevent water from flowing back.

  11 is a steam separator, and the upper side of the steam separator 11 and the upper surface of the upper header 5 are connected by a steam pipe 12, and the bottom of the steam separator 11 and the lower header 4 are connected. Are connected by a downcomer 13.

  Reference numeral 14 denotes a water level detection device 14 used for detecting the level (water level) of the water in the heating pipe 2, and the water level detection device 14 includes a water level detection container 15, and the water level detection container 15. The lower header 4 and the lower header 4 communicate with each other by a lower communication tube 16, and the upper end of the water level detection container 15 and the upper header 5 communicate with each other by an upper communication tube 17.

  Six water level detection electrode rods 18a, 18b, 18c, 18d, 18e, and 18f having different lengths are inserted into the water level detection vessel 15, and each of the water level detection electrode rods 18a, 18b, 18c, The lower end positions of 18d, 18e, and 18f have different heights, and are arranged such that the lower end positions become higher in the order of 18a, 18b, 18c, 18d, 18e, and 18f. Further, the water levels detected by the water level detection rods 18a, 18b, 18c, 18d, 18e, 18f are water level detection signals Ha, Hb, Hc, Hd, He, Hf (Ha <Hb <Hc <Hd <He <Hf). Is output to the water level control unit 20. Accordingly, the water level detection device 14 detects the water level of the boiler in stages.

  The water level controller 20 controls the drive of the water supply pump 9 based on the water level detection signals Ha, Hb, Hc, Hd, He, and Hf to adjust the amount of water supplied, so that the water level falls within a range of Hc <Hd, for example. Make sure it is retained.

  A fuel gas supply line 21 is connected to the burner nozzle 6, and a fuel gas supply amount switching unit 22 is provided in the fuel gas supply line 21. The fuel gas supply amount switching unit 22 has a plurality of gas on-off valves (not shown) that flow gas flows corresponding to the set combustion rate, and each time the combustion rate is switched, the flow rate corresponding to the combustion rate is changed. A gas valve is opened to supply gas, and the control device 19 selectively opens and closes the gas on-off valve based on signals from pressure switches 24, 25, and 26 (described later). The amount of fuel gas supplied to the burner nozzle 6 is set.

  The pressure switches 24, 25, and 26 are connected to the steam pipe 12, the pressure switches 24, 25, and 26 have different set values, and the pressure switches 24, 25, and 26 are respectively set steam pressures. When the pressure P of the steam flowing through the steam pipe 12 further decreases, the steam pressure detection signals Ph, Pm, Pl are output. The steam pressure detection signals Ph, Pm, Pl are input to the control device 19. The The pressure value is Ph <Pm <Pl.

  The steam pressure detection signals Ph, Pm, and Pl indicate boiler load states (Ph: high load (100% load), Pm: medium load: (65% load), Pl: low load (30% load)), respectively. The controller 19 is based on the vapor pressure detection signals Ph, Pm, Pl from the pressure switches 24, 25, 26, and the burner nozzle 6 is in a combustion state (100% combustion, 65% combustion, 30% combustion, combustion). Stop) is selected, and the fuel gas supply amount switching unit 22 is controlled to adjust the fuel gas supply amount to the burner nozzle 6 so that the selected combustion state is obtained.

  At the same time as controlling the combustion state of the burner nozzle 6, it outputs to the water level controller 20 whether the combustion state is high load, medium load, or low load.

  The water level control unit 20 controls the driving of the water supply pump 9 according to the input combustion state, so that the water level in the heating pipe 2 is controlled. That is, when a high load (100% combustion) is input, the water level is between Hb and Hc, and when a medium load (65% combustion) is input, the water level is between Hc and Hd. When a low load (30% combustion) is input, the water level control unit 20 controls the drive of the water supply pump 9 so that the water level is located between Hd and He, and adjusts the amount of water supply. .

  FIG. 7 shows the combustion state, the water level, and the state of the steam obtained. The region A surrounded by the curves 27a and 27b is a region where steam having good dryness is obtained, which is above the curve 27a. In the region B, the water level is too high, moisture is mixed into the steam and the dryness is lowered, and the region C below the curve 27b is a region where the water level is too low and the heating tube 2 is overheated.

  Therefore, the water level at 100% combustion to be controlled is Hb <Hc, the water level Hc <Hd at 65% combustion, and the water level Hd <He at 30% combustion are as shown in FIG. It is set to be between the curves 27b.

  As described above, when the combustion load factor is set at a plurality of positions and is intended to correspond to the boiler load, when the boiler load does not match the combustion load factor, for example, the boiler load is 80%. Then, the combustion state of the burner is controlled while switching between 100% combustion and 65% combustion.

  Furthermore, boiler load conditions may vary from customer to customer or from season to season, and the conventional once-through boiler combustion control for handling these boiler load conditions still requires the combustion state of the burner. Therefore, the auxiliary devices such as the solenoid valve and the water supply pump 9 constituting the fuel gas supply amount switching unit 22 are frequently turned ON / OFF, and the auxiliary devices are consumed. However, the life of the boiler equipment may be affected.

  Furthermore, when the load state of the boiler is 30% or less, for example, 20%, the burner is controlled to switch between 30% combustion and combustion stop (start / stop control), but when starting and stopping the boiler, , It is necessary to perform a post-purge with air each time it stops, and to perform a pre-purge every time it starts, and because a large amount of purge air replaces the inside of the boiler, the heat accumulated in the boiler is released into the atmosphere by the purge air As a result, there is a problem that energy loss increases.

JP-A-6-147402

  In view of such circumstances, the present invention adopts boiler combustion control by multiple position control, and without changing the configuration of the boiler, the multiple positions set to the burner combustion load factor closest to the load state of the operating boiler. Boiler combustion control reduces burner combustion state switching, enables stable steam supply, and reduces the burden on auxiliary machinery to extend the life of boiler equipment. This is intended to suppress energy loss by eliminating the on / off control.

  The present invention provides a burner nozzle, a fuel supply line that supplies fuel to the burner nozzle, and a fuel supply line that can adjust the flow rate of the fuel continuously and has a plurality of set combustion load factors. A flow rate adjusting means capable of adjusting to a corresponding flow rate, a water level detection device for detecting the water level of the boiler, and a water level control unit for controlling to one of a plurality of water levels set based on a water level detection result from the water level detection device; A pressure detector having a plurality of set pressure values and detecting whether or not the vapor pressure is a set pressure value; and controlling the flow rate adjusting means based on a vapor pressure detection result from the pressure detector to control the burner nozzle The combustion load factor of the burner nozzle corresponds to the steam pressure detection result, the combustion load factor of the burner nozzle is controlled stepwise, and the steam pressure from the pressure detector Those of the water level to be controlled on the basis of the output result in once-through boiler device and a control device for commanding the water level controller.

  In addition, the present invention relates to a once-through boiler apparatus capable of changing the combustion load factor corresponding to a plurality of pressure setting values of the pressure detector.

  Further, the present invention relates to a once-through boiler apparatus in which the change of the combustion load factor is performed in a range excluding a region where moisture is mixed into the steam and a region where the boiler heating pipe is overheated at a set water level. is there.

  Further, according to the present invention, the control device has a storage unit, the boiler operation data is stored in the storage unit over time, and a plurality of set combustion load factors can be updated based on the boiler operation data. This relates to the once-through boiler apparatus.

  The present invention also relates to a once-through boiler apparatus that has table data in which combustion load factors are patterned, and that enables updating of a plurality of combustion load factors set based on the table data.

  Further, the present invention relates to the once-through boiler device, wherein the flow rate adjusting means is a motor valve.

  According to the present invention, the fuel is a gas fuel, and the flow rate adjusting means includes a proportional valve provided in the fuel supply line and a damper for adjusting a supply amount of combustion air. The fuel gas is supplied at a flow rate corresponding to the adjustment pressure of the damper, and the control device relates to a once-through boiler device that controls the opening degree of the damper.

  According to the present invention, the fuel is a liquid fuel, and the flow rate adjusting means includes a return line connecting the downstream and the upstream of the fuel supply pump, and a motor valve provided in the return line, and the control device Relates to a once-through boiler device for controlling the opening degree of the motor valve.

  The present invention also provides a combustion control method for a once-through boiler that detects a water level in a plurality of stages by a water level detection device and performs stage combustion control at a combustion load factor corresponding to each stage water level, corresponding to each stage water level. According to the combustion control method for a once-through boiler, the combustion load factor is changed in a range excluding the region where moisture is mixed into the steam at each water level and the region where the boiler heating pipe is overheated according to the actual operating state of the boiler. Is.

  According to the present invention, a burner nozzle, a fuel supply line that supplies fuel to the burner nozzle, and a fuel supply line that can adjust the flow rate of the fuel continuously and have a plurality of set combustion load factors. Flow level adjustment means that can adjust the flow rate corresponding to each, a water level detection device that detects the water level of the boiler, and a water level control that controls to one of a plurality of water levels set based on the water level detection result from the water level detection device And a pressure detector that has a plurality of set pressure values and detects whether the vapor pressure is a set pressure value, and controls the flow rate adjusting means based on the vapor pressure detection result from the pressure detector. The amount of fuel supplied to the burner nozzle is set so that the combustion load factor of the burner nozzle corresponds to the vapor pressure detection result, and the combustion load factor of the burner nozzle is controlled stepwise and from the pressure detector. And a control device that instructs the water level control unit to control the water level to be controlled based on the atmospheric pressure detection result, so that it is possible to change the combustion load factor by the stage combustion control, and to match the actual load state and operating state of the boiler Optimum operation is possible, the number of operations of the auxiliary machine is reduced, the life of the boiler can be extended, and stable operation without pressure fluctuation is possible.

  Further, according to the present invention, the combustion load factor corresponding to a plurality of pressure setting values of the pressure detector can be changed. Therefore, even after once setting, the optimum load condition and operating condition of the boiler are optimal. The combustion load factor can be set.

  Further, according to the present invention, the combustion load factor is changed at a set water level in a range excluding a region where moisture is mixed into the steam and a region where the boiler heating pipe is overheated. Can be easily implemented by changing the threshold value without remodeling, and can also be applied to existing once-through boiler apparatuses.

  Further, according to the present invention, the control device has a storage unit, stores boiler operation data in the storage unit over time, and updates a plurality of set combustion load factors based on the boiler operation data. Since it is possible, optimal staged combustion control can be performed in accordance with the actual operation rate and load state, which could not be dealt with in the initial setting.

  Further, according to the present invention, the combustion load factor is tabled and the plurality of combustion load factors set based on the table data can be updated. Therefore, the combustion load factor can be easily updated. be able to.

  Further, according to the present invention, there is provided a combustion control method for a once-through boiler that detects a water level in a plurality of stages by a water level detection device and performs stage combustion control at a combustion load factor corresponding to the water level in each stage. The corresponding combustion load factor is changed in a range excluding the area where moisture is mixed into the steam at each water level and the area where the boiler's heating pipe is overheated according to the actual boiler operating condition. The combustion load factor can be changed, optimal operation is possible according to the actual load and operation status of the boiler, the number of operation of the auxiliary machine is reduced, the life of the boiler is extended, and stable operation without pressure fluctuation Further, it can be easily implemented by changing the threshold without modifying the water level detection device, and exhibits an excellent effect that it can be applied to an existing once-through boiler device.

It is a block diagram showing a schematic structure of a once-through boiler device concerning the 1st example of the present invention. It is a diagram which shows the combustion state in this invention, a water level, and the state of the vapor | steam obtained. It is a figure which shows an example of the data table for setting a combustion load factor. It is a block diagram which shows schematic structure of the once-through boiler apparatus which concerns on 2nd Example of this invention. It is a block diagram which shows schematic structure of the once-through boiler apparatus which concerns on the 3rd Example of this invention. It is a block diagram which shows schematic structure of the conventional once-through boiler apparatus. It is a diagram which shows the combustion state in the past, a water level, and the state of the vapor | steam obtained.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 shows a first embodiment of a once-through boiler apparatus to which the present invention is applied. In the first embodiment, gas is used as fuel and four-stage stage combustion control is performed.

  1 that are the same as those shown in FIG. 6 are given the same reference numerals, and descriptions thereof are omitted.

  The fuel gas supply line 21 is provided with a pressure adjusting unit 31 and a flow rate adjusting means 32 from the upstream side (the burner nozzle 6 is at the downstream end). The flow rate adjusting means 32 is electrically connected to the control device 19. The opening degree of the valve is controlled by the opening degree setting signal V.

  As the flow rate adjusting means 32, for example, a motor valve is used. A stepping motor is used as an actuator for adjusting the valve opening, and a one-pulse drive signal and a change in the valve opening for driving the stepping motor are defined. A corresponding number of pulses are given to the flow rate adjusting means 32 as the opening setting signal V. Note that a servo motor or the like may be used as a motor that can control the valve opening.

  The flow rate adjustment means 32 is set in steps by the opening degree setting signal V from the control device 19, but as the flow rate adjustment means 32 itself, the valve opening degree changes continuously. Therefore, the flow rate can be adjusted steplessly. Accordingly, by changing the setting of the opening setting signal V, the opening of the set valve can also be changed.

  The steam pipe 12 is provided with a pressure detector 33. The pressure detector 33 is, for example, an integrated pressure sensor and microcomputer, detects the vapor pressure P of the vapor flowing through the vapor pipe 12, and the vapor pressure P becomes a plurality of set vapor pressures. In this case, the vapor pressure detection signal P (Ph, Pm, Pl) is output to the control device 19. Alternatively, the control device 19 compares the pressure detection signal input from the pressure detector 33 with the set value, and when the set pressure is reached, the vapor pressure detection signal P (Ph, Pm, Pl) is input. It may be determined that it has been detected or detected.

  For the pressure detector 33, pressure switches 24, 25, and 26 that individually detect the set vapor pressures and output the vapor pressure detection signals Ph, Pm, and Pl, respectively, may be used as in the prior art. . Although not specifically shown, the fuel gas supply line 21 is provided with a shutoff valve for shutting off the fuel.

  The control device 19 includes an input unit 34 such as an operation panel, and a storage unit 35 such as a semiconductor memory and an HDD. The input unit 34 includes a display unit, a numeric keypad, and the like, and has high combustion, medium combustion, and low combustion. The combustion load factor can be set. In the storage unit 35, a sequence program for executing the four-stage stage combustion control, a water level control program for executing the water level control by the water level control unit 20, and a high combustion, medium operation by the operation from the input unit 34. Programs such as a combustion load factor setting program that enables changing and setting of the combustion load factor of combustion and low combustion, an operation state recording program that records the operation state of the boiler over time, and the like are stored in the storage unit 35. The operation state data is stored as time-dependent data.

  The water level detection device 14 is the same as the conventional one, or the existing water level detection device 14 is used. For example, combustion load factors of 100%, 65%, and 30% are set as initial settings for the staged combustion control of the once-through boiler device, and the water level detection device 14 is configured to detect the water level corresponding to the combustion load factor. Yes.

  FIG. 2 shows the combustion state, the water level, and the state of the steam obtained as in FIG. 7, and the region A surrounded by the curves 27a and 27b is a region where steam having a good dryness is obtained, In the region B above the curve 27a, the water level is too high, moisture is mixed in the steam and the dryness is lowered, and the region C below the curve 27b is a region where the water level is too low and the heating pipe 2 is overheated. It has become.

  Water levels detected by the water level detection electrode rods 18a, 18b, 18c, 18d, 18e, 18f, Hb <Hc (water level at 100% combustion), Hc <Hd (water level at 65% combustion), Hd <He The range in which steam with good dryness can be obtained (water level at 30% combustion) has a wide range, and as shown in FIG. 2, the combustion load factor is at a water level of Hb <Hc. Similarly, it is 40% to 75% at a water level of Hc <Hd, and 20% to 55% at a water level of Hd <He.

  Therefore, the combustion load factor is in the range of 75% to 100% for high combustion, the combustion load factor is in the range of 40% to 75% for medium combustion, and the combustion load factor is in the range of 20% to 55% for low combustion. Thus, even if the setting of the burner combustion load factor is changed, good quality steam can be obtained. The range of the combustion load factor is an example, and can be appropriately changed according to the situation.

  In the staged combustion control of the once-through boiler device, for example, if the boiler operating condition does not match the initial combustion load factor, for example, if the boiler operating condition does not fall below 35%, the low The initial combustion setting of 30% combustion is meaningless, and combustion phase control is not functioning effectively.

  In this embodiment, when the water level control is performed based on the detection result of the water level detection device 14, the fact that the combustion load factor corresponding to the controlled water level has a range is used, and the combustion load factor in the stage combustion control is The setting is changed, adapted to the actual operating state, the load switching frequency is decreased, the pressure fluctuation is reduced, and the stable once-through boiler apparatus can be operated.

  The operation will be described below.

  The pressure adjusting unit 31 adjusts the pressure (primary pressure) of the fuel gas supplied from the fuel gas supply line 21 to a predetermined value (secondary pressure). By adjusting the pressure supplied to the flow rate adjusting unit 32 to a predetermined value (a constant value), the flow rate is uniquely determined by adjusting the valve opening of the flow rate adjusting unit 32.

  The control device 19 performs step control on the valve opening degree of the flow rate adjusting means 32 so that the supply flow rate becomes the initial combustion load factor. For example, when the actuator of the flow rate adjusting means 32 is a stepping motor, the control device 19 outputs an opening setting signal (Vh) of the number of A pulses to the flow rate adjusting means 32 in high combustion, and in the middle combustion. An opening setting signal (Vm) for the number of B pulses and an opening setting signal (Vl: Vl <Vm <Vh) for the number of C pulses are output to the flow rate adjusting means 32 in low combustion.

  The control device 19 is supplied with vapor pressure detection signals Ph, Pm, Pl from the pressure detector 33, and the control device 19 receives the input vapor pressure detection signals Ph, Pm, Pl. Based on Pl, the load state is determined, and an opening setting signal to be output to the flow rate adjusting means 32 is determined.

  Thus, the control device 19 adjusts the gas flow rate supplied to the burner nozzle 6 by the flow rate adjusting means 32 stepwise based on the vapor pressure detection signals Ph, Pm, Pl from the pressure detector 33, The combustion of the burner nozzle 6 is step-controlled so as to correspond to the load.

  Further, boiler operation data such as the steam pressure detection signal P from the pressure detector 33, the switching history of the flow rate adjusting means 32, and the history of fluctuations in the boiler load factor are stored in the storage unit 35 over time and in time series. Accumulated. Further, the control device 19 calculates an optimum combustion load factor of high combustion, medium combustion, and low combustion based on the boiler operation data for every predetermined period such as one week or one month, and stores it in the storage unit 35. Record. The calculated combustion load factor is such that the combustion load factor is 75% to 100% for high combustion, 40% to 75% for medium combustion, and 20% to 55% for low combustion so that the steam quality does not deteriorate. It becomes a range.

  After a predetermined period, the set combustion load factor is compared with the calculated combustion load factor (hereinafter referred to as a new combustion load factor), and if there is a difference, the set combustion load factor is updated to the new combustion load factor. . Thereafter, each combustion load factor is finely adjusted so that fluctuations with respect to the target pressure (operating steam pressure) set by the pressure values of the steam pressure detection signals Ph, Pm, Pl are reduced. In the microcomputer-integrated pressure detector, the target pressure is calculated based on the pressure that generates the detection signal, and each combustion load factor is automatically finely adjusted so that the deviation is reduced.

  The update operation may be automatically performed by the control device 19, or the operator periodically displays the boiler operation data and the new combustion load factor on the display unit, and confirms whether the set combustion load factor is an appropriate operation. If it is determined that an update is necessary, the input unit 34 may be used to manually update the new combustion load factor. The new combustion load factor may be obtained by an operator based on boiler operation data.

  Further, the combustion load factor may be updated in advance at the time of delivery of the once-through boiler device based on the past data of the customer's boiler operating state.

  Also, as shown in FIG. 3, combustion load factor setting table data is prepared, combustion load factor setting is patterned by the table data, and combustion is performed manually or automatically by the control device 19 based on the table data. The load factor may be updated. When the combustion load factor setting is set based on the table data, the accumulation of boiler operation data with time may be omitted.

  The table data in FIG. 3 is, for example, set to set the combustion load factor corresponding to the season. In addition, it is good also as table data which sets a combustion load factor corresponding to outside temperature.

  A flow meter is provided on the downstream side of the flow rate adjusting means 32 to detect whether there is a deviation between the set flow rate and the adjusted flow rate. If there is a deviation, the opening degree of the flow rate adjusting means 32 is detected. May be corrected to improve the flow rate setting accuracy.

  As a modification of the flow rate adjusting means 32, a link may be connected to the valve rotation shaft, and the valve opening degree may be adjusted by rotating the valve via the link by an actuator such as a motor.

  FIG. 4 shows a second embodiment.

  In FIG. 4, the same components as those shown in FIGS. 6 and 1 are denoted by the same reference numerals, and the description thereof is omitted.

  In FIG. 4, 37 is a combustion air blower, 38 is a damper for adjusting the air volume provided on the downstream side of the combustion air blower 37, and 39 is a motor for adjusting the damper opening. As the motor 39, an actuator capable of adjusting the opening degree of the damper 38, such as a capacitor motor with a limit, a stepping motor, or a servo motor, is used.

  A proportional valve 40 is provided on the downstream side of the pressure adjustment unit 31 of the fuel gas supply line 21, and an adjustment pressure on the downstream side of the proportional valve 40 and an adjustment pressure on the downstream side of the damper 38 are fed back, and The supply amount of the fuel gas is adjusted by the flow rate adjusting means 32 so that the gas pressure (gas supply amount) is proportional to the pressure.

  In the case of the second embodiment, the damper 38, the motor 39, the proportional valve 40 and the like constitute the flow rate adjusting means 32.

  In the second embodiment, on the basis of the vapor pressure detection signal P from the pressure detector 33, the degree of opening of the damper 38 is adjusted stepwise via the motor 39 and supplied to the burner nozzle 6. The air flow rate is controlled step by step. The proportional valve 40 feeds back the adjustment pressure of the damper 38 so that the valve opening, that is, the adjustment gas flow rate of the proportional valve 40 is uniquely determined with respect to the adjustment pressure of the damper 38. Therefore, the flow rate of the fuel gas supplied to the burner nozzle 6 is controlled by the air volume control of the combustion air by the damper 38. The opening degree of the damper 38 can also be set manually. For example, when a capacitor motor with a limit is used as an actuator, the opening degree of the damper 38 can be set manually by setting the limit position or value. Can be set.

  FIG. 5 shows a third embodiment. In the third embodiment, the fuel is a liquid fuel such as oil. In FIG. 5, the same components as those shown in FIGS. 6 and 1 are denoted by the same reference numerals, and the description thereof is omitted.

  A burner nozzle 6 'for liquid is used as the burner nozzle, and a fuel supply line 41 is connected to the burner nozzle 6'. The fuel supply line 41 is connected to the fuel supply line 41 from the upstream side by a fuel supply pump 42, a first cutoff valve 43, A two shut-off valve 44 is provided. The first shut-off valve 43 and the second shut-off valve 44 are used when stopping the supply of fuel, or when stopping the fuel in an emergency, and the fuel supply line 41 is fully closed. Further, during operation, the first cutoff valve 43 and the second cutoff valve 44 are fully opened.

  A return line 45 is provided between the first shut-off valve 43 and the second shut-off valve 44 and the upstream side of the fuel supply pump 42. The return line 45 has a motor valve 46 for adjusting the flow rate. Is provided. A stepping motor or a servo motor is used as a motor as an actuator used for the motor valve 46.

  The fuel supply pump 42 is configured to send a specified flow rate (a constant flow rate), and the return line 45 returns a part of the sent flow rate to the upstream side of the fuel supply pump 42, and the return amount is the motor. It is determined by the valve opening degree of the valve 46. If the return amount by the return line 45 is large, the amount of fuel supplied to the burner nozzle 6 'is small and the combustion is low, and if the return amount is small, the amount of fuel supplied to the burner nozzle 6' is large and the combustion is high. It becomes.

  The control device 19 outputs an opening setting signal to the motor valve 46 based on the steam detection signal P from the pressure detector 33, and the valve opening of the motor valve 46 is determined stepwise by the opening setting signal. The When the valve opening of the motor valve 46 is determined, the return amount of fuel is determined, that is, the fuel supply amount to the burner nozzle 6 'is determined, and the combustion state of the burner nozzle 6' is controlled.

  In the third embodiment, the return line 45, the motor valve 46 and the like constitute the flow rate adjusting means 32.

  In the above embodiment, the four-position stage combustion control has been described. Needless to say, the three-position stage combustion control and the five-position stage combustion control can be similarly implemented.

DESCRIPTION OF SYMBOLS 1 Boiler main body 2 Heating pipe 3 Combustion chamber 6 Burner nozzle 14 Water level detection apparatus 19 Control apparatus 20 Water level control part 21 Fuel gas supply line 31 Pressure adjustment part 32 Flow rate adjustment means 33 Pressure detector 34 Input part 35 Memory | storage part 37 Combustion air blower 38 Damper 39 Motor 40 Proportional valve 41 Fuel supply line 42 Fuel supply pump 45 Return line 46 Motor valve

Claims (9)

A multi-flow boiler device that performs multi-position combustion control in which a plurality of combustion load factors are set, a combustion load factor corresponding to a boiler load is selected from the plurality of combustion load factors, and combustion is controlled,
Burner nozzles and a fuel supply line for supplying fuel to the burner nozzle, provided in the fuel supply line, flow rate corresponding to each of said plurality of combustion load factor, which is set with a flow rate of the fuel is adjustable stepless A flow level adjusting means that can be adjusted to the water level, a water level detection device that detects the water level of the boiler, a water level control unit that controls to one of a plurality of water levels set based on a water level detection result from the water level detection device, A pressure detector having a set pressure value and detecting whether the vapor pressure is the set pressure value;
Among the fuel supply amount of the plurality of combustion load factor to said burner nozzles by controlling the flow rate adjusting means based on the vapor pressure detection result from the pressure detector, selects a combustion load factor corresponding to the vapor pressure detection result and, and a control unit for commanding the vapor pressure detected water level to be controlled based on the results from the pressure detector with stepwise control combustion load factor of the burner nozzles to the water level controller,
Further, the control device is capable of changing the set plurality of combustion load factors, respectively . The multi-position combustion control is four-position combustion control, and the plurality of set combustion load ratios are 75% to 100% for high combustion, 40% to 75% for medium combustion, and 20% to low combustion, respectively. The set combustion load factor can be changed within the range of 75% to 100% for high combustion, 40% to 75% for medium combustion, and 20% to 55% for low combustion. The once-through boiler apparatus according to claim 1.   3. The once-through boiler apparatus according to claim 2, wherein the combustion load factor is changed in a range excluding a region where moisture is mixed into the steam and a region where the boiler heating pipe is overheated at a set water level. The control device has a storage unit, stores boiler operation data over time in the storage unit, calculates an optimum new combustion load factor based on the boiler operation data, and sets the new combustion load factor and the set combustion The once-through boiler apparatus according to claim 1, wherein the load factor is compared and, if there is a difference, the update to the new combustion load factor is possible. A seasonal combustion load factor, or the table data patterned to correspond to the outside air temperature, and selects the season when running the boiler unit, or a combustion load factor corresponding to the ambient temperature from the table data, the The once-through boiler apparatus according to claim 1, wherein a plurality of combustion load factors can be updated.   The once-through boiler apparatus according to claim 1, wherein the flow rate adjusting means is a motor valve.   The fuel is a gas fuel, and the flow rate adjusting means has a proportional valve provided in the fuel supply line and a damper for adjusting a supply amount of combustion air, and the proportional valve is an adjustment pressure of the damper. The once-through boiler apparatus according to claim 1, wherein a fuel gas having a flow rate corresponding to is supplied and the control device controls an opening degree of the damper.   The fuel is a liquid fuel, and the flow rate adjusting means has a return line connecting the downstream and upstream of the fuel supply pump, and a motor valve provided in the return line, and the control device The once-through boiler apparatus according to claim 1, wherein the opening degree is controlled. A combustion control method for a once-through boiler that performs multi-position combustion control in which a plurality of combustion load factors are set, a combustion load factor corresponding to a boiler load is selected from the plurality of combustion load factors, and combustion is controlled, A combustion control method for a once-through boiler that detects a water level in a plurality of stages by a water level detection device and performs stage combustion control at a combustion load ratio corresponding to the water level in each stage among the plurality of combustion load ratios ,
Obtain boiler operation data over time, calculate the optimal new combustion load factor based on the acquired boiler operation data, compare the new combustion load factor and the set combustion load factor, if there is a difference, It is possible to change to a new combustion load factor,
The change to the new combustion load factor is performed in a range that excludes a region where moisture is mixed into steam at each water level and a region where the boiler heating pipe is overheated, and a combustion control method for a once-through boiler.

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