JP2012163270A - Once-through boiler device and method of controlling combustion of once-through boiler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an once-through boiler device that performs stage control of combustion and can perform combustion control smoothly corresponding to a load and a method of controlling combustion of an once-through boiler.SOLUTION: The once-through boiler device includes a pressure detector 33 for detecting vapor pressure and a controller 19 that controls flow amount adjustment means 32 based on vapor pressure detection results from the pressure detector to perform control a fuel supply amount to a burner nozzle 6 such that the combustion load rate of the burner nozzle corresponds to the vapor pressure detection results. The controller can perform combustion control through a stage combustion control mode wherein combustion is controlled by switching a plurality of set combustion load factors and a proportional combustion control mode wherein proportional combustion control is performed corresponding to the combustion load factor within a set combustion load factor. When the vapor pressure to be detected is high load or low load, the stage combustion control is performed. For a middle load, the proportional combustion control is executed.

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 4-position combustion control is 20% low combustion, 60% medium combustion, 100% high combustion, or when the load on the boiler is any of 20%, 60%, 100% However, it is only necessary to control the combustion of the boiler by selecting the corresponding load factor, but in reality, the load on the boiler does not match the set load factor, and the control of the combustion is performed so that the control of the boiler corresponds to the load on the boiler. The combustion is staged by switching the load factor (multi-position combustion control).

  For example, when the load on the boiler is 80%, the combustion is controlled so that the average combustion load factor becomes 80% by appropriately switching between 60% medium combustion and 100% high combustion. When the boiler load is 20% or less, for example, 10%, the combustion load factor is controlled to 10% by combining 20% low combustion and combustion stop.

  For this reason, when the load on the boiler is 80%, even if the load on the boiler is constant, 60% medium combustion and 100% high combustion are frequently repeated. For this reason, although the load of the boiler is constant, the pressure fluctuation occurs. In a once-through boiler, the water level is controlled in accordance with the combustion load factor. However, if the combustion load factor is frequently switched, the water level in the water pipe cannot follow the switching of the combustion load factor, and moisture is contained in the steam. Mixing, the dryness decreases, and the quality of the steam deteriorates. Further, in response to switching of the combustion state of the burner, switching of the operation state of the fan for sending combustion air is performed, but there is a problem that energy efficiency is lowered due to rapid acceleration and deceleration.

JP-A-6-147402 JP 2007-278539 A

  In view of such circumstances, the present invention provides a once-through boiler apparatus and a once-through boiler combustion control method capable of performing combustion control corresponding to an actual boiler load while performing stage control of boiler combustion. is there.

  The present invention relates to a burner nozzle, a fuel supply line for supplying fuel to the burner nozzle, a flow rate adjusting means provided in the fuel supply line and capable of adjusting the flow rate of fuel to a flow rate corresponding to a combustion load factor, and a water level of a boiler A water level detection device that detects the water level in stages, a water level control unit that controls the water level in one of a plurality of steps set based on the water level detection result from the water level detection device, and a pressure detector that detects the vapor pressure A control device for controlling the flow rate adjusting means based on the vapor pressure detection result from the pressure detector to control the fuel supply amount to the burner nozzle so that the combustion load factor of the burner nozzle corresponds to the vapor pressure detection result; The control device includes a staged combustion control mode in which combustion control is performed by switching a plurality of set combustion load factors, and proportional combustion corresponding to the combustion load factor within a range of the set combustion load factors Combustion control in a proportional combustion control mode is possible, and when the detected vapor pressure is high load or low load, the staged combustion control is executed, and when the detected steam pressure is medium load, the proportional combustion control is executed. The present invention relates to a once-through boiler device.

  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 fuel supply pump that supplies fuel from the burner nozzle, a return line that connects the downstream and upstream sides of the fuel supply pump, and the return line. The control device relates to a once-through boiler device that controls the opening degree of the motor valve.

  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.

  The present invention also relates to a once-through boiler apparatus in which the burner nozzle has a plurality of spray nozzles, and the spray nozzle is selected according to a high combustion load factor, a medium combustion load factor, and a low combustion load factor.

  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 the water level in each stage. At the water level corresponding to the high combustion load factor and the water level corresponding to the low combustion load factor, the combustion is controlled in stages so as to correspond to the target load by switching the preset combustion load factor, and at the water level corresponding to the medium combustion load factor. The invention relates to a combustion control method for a once-through boiler in which combustion is controlled by proportional control according to the actual operating state of the boiler.

  According to the present invention, a burner nozzle, a fuel supply line for supplying fuel to the burner nozzle, a flow rate adjusting means provided in the fuel supply line and capable of adjusting the flow rate of fuel to a flow rate corresponding to a combustion load factor, and a boiler A water level detection device for detecting the water level in stages, a water level control unit for controlling the water level in one of a plurality of stages set based on the water level detection result from the water level detection device, and pressure detection for detecting the vapor pressure And a control for controlling the flow rate adjusting means based on the vapor pressure detection result from the pressure detector to control the fuel supply amount to the burner nozzle so that the combustion load factor of the burner nozzle corresponds to the vapor pressure detection result The control device is configured to perform a combustion control by switching a plurality of set combustion load factors, and a ratio corresponding to the combustion load factor within a range of the set combustion load factors. Combustion control is possible in the proportional combustion control mode that performs combustion control. When the detected vapor pressure is high load or low load, the staged combustion control is executed, and when the detected steam pressure is medium load, the proportional combustion control is executed. Therefore, switching of the combustion rate at the most frequently used medium load is eliminated, pressure fluctuation can be suppressed, and it is possible to respond smoothly to the actual boiler load, reducing the consumption of auxiliary machinery, The energy efficiency of the fan that blows fuel air can be improved.

  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. Stage control is possible, and the cost can be reduced and the present invention can also be applied to an existing once-through boiler apparatus.

  According to the present invention, the burner nozzle has a plurality of spray nozzles, and the spray nozzle is selected according to a high combustion load factor, a medium combustion load factor, and a low combustion load factor. The fuel can be used, and the equipment cost can be reduced.

  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. Among them, at the water level corresponding to the high combustion load factor and the water level corresponding to the low combustion load factor, the combustion combustion is controlled in stages so as to correspond to the target load by switching the preset combustion load factor, and corresponds to the medium combustion load factor. At the water level, the combustion is controlled by proportional control according to the actual operating state of the boiler.Therefore, switching of the combustion rate at the most frequently used medium load is eliminated, pressure fluctuation can be suppressed, and the actual boiler load can be reduced. It can respond smoothly, and exhibits excellent effects such as reducing the consumption of auxiliary equipment and improving the energy efficiency of the fan that blows fuel air.

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 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.

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

  FIG. 1 shows an outline of a once-through boiler apparatus according to an embodiment of the present invention.

  In FIG. 1, reference numeral 1 denotes a boiler body, and the boiler body 1 is surrounded by a plurality of heating pipes 2 and the heating pipes 2 in a ridge direction standing at a predetermined interval in the circumferential direction. 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.

  14 is a water level detection device used for detecting the level (water level) of the water in the heating pipe 2, and has the same configuration as the water level detection device provided in the existing once-through boiler device. The detection device 14 includes a water level detection container 15. The bottom of the water level detection container 15 and the lower header 4 are communicated with each other by a lower communication pipe 16, and the upper end of the water level detection container 15 and the upper pipe are connected. The stopper 5 is communicated with the upper communication pipe 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 electrode rods 18a, 18b, 18c, 18d, 18e, and 18f are water level detection signals Ha, Hb, Hc, Hd, He, and 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.

  FIG. 2 shows the combustion state, the water level, and the resulting steam state. The region A surrounded by the curves 27a and 27b is a region where steam with good dryness is obtained, which is above the curve 27a. The region B is a region where the water level is too high and 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 tube 2 is overheated.

  Water levels detected by the water level detection electrode rods 18a, 18b, 18c, 18d, 18e, and 18f, Hb <Hc (water level at high combustion (100%)), Hc <Hd (medium combustion (40% to 80%)) ) And Hd <He (water level at low combustion (20%)), the range in which steam with good dryness can be obtained has a width, as shown in FIG. Furthermore, the combustion load factor is 75% to 100% at a water level of Hb <Hc, similarly, the combustion load factor is 40% to 80% at a water level of Hc <Hd, and the combustion load factor is 20% at a water level of Hd <He. ~ 55%.

  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 80% 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 FIG. 1, reference numeral 19 denotes a control device. 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. The combustion load factor of high combustion, medium combustion, and low combustion can be set. The control device 19 controls the valve opening degree of the flow rate adjusting means 32 described later based on a vapor pressure detection signal described later and a set combustion load factor.

  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. A combustion load factor setting program that can change and set the combustion load factor for combustion and low combustion is stored.

  The control device 19 sends a water level command corresponding to the combustion state to the water level control unit 20, and the water level control unit 20 is based on the water level detection signals Ha, Hb, Hc, Hd, He, and Hf. 9 is controlled to adjust the supply amount of water so that the water level is maintained within a predetermined range. For example, if the water level command is high load (100% combustion), the water level is between Hb and Hc, and if the water level is medium load (80% to 40% combustion), the water level is between Hc and Hd. In addition, when the load is low (20% combustion), the water level control unit 20 controls the driving of the water supply pump 9 to adjust the amount of water supply so that the water level is located between Hd and He. To do.

  In the present 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 medium load that is most frequently used is proportional. Combustion control is executed, phased combustion control is adapted to the actual operating state, load switching frequency is reduced, pressure fluctuation is reduced, and stable once-through boiler apparatus can be operated.

  A fuel gas supply line 21 is connected to the burner nozzle 6, and a pressure adjusting unit 31 and a flow rate adjusting means 32 are provided on the fuel gas supply line 21 from the upstream side (the burner nozzle 6 is at the downstream end). It is electrically connected to the control device 19, and the opening degree of the valve is controlled by the opening degree command signal V from the control device 19, and the flow rate of fuel supplied to the burner nozzle 6 is adjusted. Yes.

  As the flow rate adjusting means 32, a flow rate adjusting valve, such as a motor valve, capable of continuously adjusting the flow rate 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 degree command signal V. Note that a servo motor or the like may be used as a motor that can control the valve opening.

  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 detects the vapor pressure detection signal P (Ph, Pm (Pmh, Pmm). , Pml) and Pl) are output to the control device 19. A threshold corresponding to the boiler load and a target pressure value PM are set in the control device 19 in advance, and the combustion pressure is changed by comparing the vapor pressure detection signal P input from the pressure detector 33 with the threshold. The pressure adjusting unit 31, the flow rate adjusting unit 32, and the water level control unit 20 are controlled to do so. The target pressure value is set in the range of Pmh <PM <Pml.

  The steam pressure detection signals Ph, Pm, and Pl indicate the load state of the boiler, respectively, corresponding to the pressure value, Ph is a high load, Pm is a medium load, and Pl is a low load, Ph <Pm < Pl. Further, Pmh <Pmm <Pml, where Pml represents the upper limit value of the medium load, Pmh represents the lower limit value of the medium load, Pmm corresponds to the load state in real time, and is in the range of Pmh to Pml. For example, Ph: high load (100% load), Pm: medium load (Pmh: 80% load to Pml: 40% load), and Pl: low load (20% load).

  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 command 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 command signal (Vm: Vmh, Vmm, Vml) of the number of B pulses, and an opening command signal (Vl) of the number of C pulses are output to the flow rate adjusting means 32 in low combustion.

  Here, Vh> Vm> Vl and Vmh> Vmm> Vml. Further, Vmh is an upper limit value in the middle combustion state, Vml is a lower limit value in the middle combustion state, and Vmm is a target in accordance with a vapor pressure detection signal P (described later) from the pressure detector 33 in the range of Vmh to Vml. Fluctuate to maintain pressure.

  Vapor pressure detection signals Ph, Pm (Pmh, Pmm, Pml), Pl are input from the pressure detector 33 to the control device 19, and the control device 19 receives the input vapor pressure detection signals Ph, Pm, Pl. Based on the above, the load state is determined, and the opening degree command signal V is determined and output to the flow rate adjusting means 32.

  The control device 19 selects a combustion control mode based on the determination of the load state. That is, when the load state is 100%, that is, when the vapor pressure detection signal is Ph, the fixed combustion control mode with a combustion load factor of 100%, and when the load state is 100% to 80%, that is, the vapor pressure detection signal is Ph. In the case of .about.Pmh, the opening degree command signal Vh or Vmh is outputted from the control device 19 to the flow rate adjusting means 32, and the stepwise combustion control mode is executed by switching between the combustion load factor 100% and the combustion load factor 80%. Is done.

  When the load state is 80% to 40%, that is, when the vapor pressure detection signal is Pmh to Pml, the opening degree command signal Vmm is output to the flow rate adjusting means 32, corresponding to the pressure fluctuation, and the target pressure Thus, the proportional combustion control mode in which the load factor is varied is executed.

  In the proportional combustion control mode, the steam pressure detection signal Pmm detected by the pressure detector 33 is fed back to the control device 19 in real time, and the control device 19 calculates the steam pressure fluctuation over time, and the steam pressure fluctuation is calculated. The reflected opening command signal Vmm is output to the flow rate adjusting means 32, and the opening degree of the flow rate adjusting means 32 is proportionally controlled so as to eliminate the deviation between the pressure detected by the pressure detector 33 and the target pressure PM. . The water level corresponding to the load state of 80% to 40% may be maintained between Hc and Hd, and the water level may be controlled in the same manner as before.

  Further, when the load state is 40% to 20%, that is, when the vapor pressure detection signal is Pml to Pl, the opening degree command signal Vml or Vl is output from the control device 19 to the flow rate adjusting means 32, and combustion is performed. A staged combustion control mode is executed by switching between a load factor of 40% and a combustion load factor of 20%. When the load state is 20% to 0%, an opening degree command signal Vml or a close signal is output, and a staged combustion control mode is performed by switching between a combustion load factor of 20% and combustion stop.

  When the load is increased from the combustion load factor of 20% (when shifting from low combustion to intermediate combustion), the intermediate combustion load factor may be once increased to 60% and further increased and decreased to reach the target value. . In this case, hunting between the 20% combustion load factor and the 40% combustion load factor is prevented. Similarly, when reducing the load from the combustion load factor of 100% (when shifting from high combustion to medium combustion), once set the medium combustion load factor to 60%, and further increase and decrease to reach the target value. Thus, hunting between the 80% combustion load factor and the 100% combustion load factor is prevented.

  In actual steady operation, since the load state falls within the range of approximately 80% to 40%, the proportional combustion control mode is executed, the load switching frequency is reduced, and the pressure fluctuation is reduced.

  In parallel with the combustion control, the supply amount of the combustion air is also controlled. Control of the supply amount of combustion air is performed by controlling a blower (not shown). Like the combustion load factor, step control is performed for high and low loads, and proportional control is performed for medium loads. . In addition, when the operation of the blower is controlled by an inverter, there is no rapid increase or decrease in speed with respect to a medium load, and power consumption can be reduced.

  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. Based on the accumulated data, the timing for switching the combustion control mode corresponding to high combustion, medium combustion, and low combustion (threshold value of the vapor pressure detection signal P for switching the combustion control mode), etc. shall be optimized in accordance with the operating state. Is possible.

  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. 3 shows a second embodiment. The second embodiment shows a system for controlling the fuel flow rate according to the load based on the damper secondary air pressure that changes with the opening of the air damper.

  In FIG. 3, the same components as those shown in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted.

  In FIG. 3, 37 is a combustion air blower, 38 is an air damper for adjusting the air volume provided on the downstream side of the combustion air blower 37, and 39 is a damper motor for adjusting the air damper opening. As the damper motor 39, an actuator capable of adjusting the opening degree of the air damper 38, such as a condenser 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 adjusting unit 31 of the fuel gas supply line 21, and the adjusted pressure on the downstream side of the proportional valve 40 and the adjusted pressure on the downstream side of the air damper 38 are fed back to the downstream side of the air damper 38. 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 on the side.

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

  In the second embodiment, the combustion air supplied to the burner nozzle 6 by adjusting the opening degree of the air damper 38 via the damper motor 39 based on the vapor pressure detection signal P from the pressure detector 33. The flow rate is controlled.

  In the case of high combustion, a high combustion opening command signal Vh is output from the control device 19 to the damper motor 39, the air damper opening becomes the high combustion opening, the air pressure on the damper secondary side rises, and the pressure is The fuel is introduced into the proportional valve 40 by 36, and the secondary pressure of the fuel is increased by the magnification set on the proportional valve 40 side, so that a high combustion fuel flow rate is set.

  When the operating pressure rises (load decreases) during continuous operation with high combustion and the vapor pressure detection signal from the pressure detector 33 becomes Pml, the control device 19 uses the medium combustion opening command signal Vmh in advance. The opening of the air damper 38 is closed so that the set middle combustion upper limit load is reached, and the fuel flow rate is similarly set to decrease. Thereafter, the intermediate combustion opening is adjusted by proportional control so that the target pressure is reached by the opening command signal Vmm, and the fuel flow rate is increased or decreased.

  Further, when the pressure rises (load decreases) during operation at a preset middle combustion lower limit load and the vapor pressure detection signal becomes Pmh, a low combustion opening command signal Vl is output to the damper motor 39 and set in advance. By closing the opening of the air damper 38 so as to achieve the low combustion opening, the air pressure is further lowered, the fuel flow rate is set to decrease, and fluctuations in the target pressure are prevented.

  Further, when the pressure drops (increases in load) during operation at a preset low combustion load, the air damper 38 is opened to a preset middle combustion lower limit opening by a middle combustion opening command signal Vml, and thereafter The middle combustion damper opening is opened and closed by the opening command signal Vmm so as to reach the target pressure.

  Further, when the pressure drops (increases the load) during operation at a preset middle combustion upper limit load, a high combustion opening command signal Vh is output, and the air damper 38 has a high combustion damper opening, and the target pressure is reduced. Prevent fluctuations.

  FIG. 4 shows a third embodiment. In the third embodiment, the fuel is a liquid fuel such as oil. 4 that are the same as those shown in FIG. 1 are given the same reference numerals, and descriptions thereof are omitted.

  As the burner nozzle, a burner nozzle 50 for liquid is used, and the burner nozzle 50 includes a high combustion jet nozzle 51, a medium combustion jet nozzle 52, and a low combustion jet nozzle 53. 51 is connected to the fuel supply line 41 via the first electromagnetic valve 44, and the middle combustion jet nozzle 52 is connected to the fuel supply line 41 via the second electromagnetic valve 47, and the low combustion jet oil The nozzle 53 is connected to the fuel supply line 41 via a third electromagnetic valve 48. The fuel supply line 41 is provided with a fuel supply pump 42.

  It should be noted that the high combustion jet nozzle 51, the medium combustion jet nozzle 52, and the low combustion jet nozzle 53 may have different spray amounts or the same amount.

  The first solenoid valve 44, the second solenoid valve 47, and the third solenoid valve 48 are used when stopping the supply of fuel, or when stopping the fuel in an emergency, and the like. Close completely. In operation, the solenoid valves 44, 47, 48 are alternatively fully opened according to the combustion state.

  A return line 45 is provided for connecting the first solenoid valve 44, the second solenoid valve 47, the third solenoid valve 48 and the fuel supply pump 42 to the upstream side of the fuel supply pump 42; The return line 45 is provided with a motor valve 46 for adjusting the flow rate. A stepping motor or a servo motor is used as a motor as an actuator used for the motor valve 46.

  In the case of the third embodiment, the first electromagnetic valve 44, the second electromagnetic valve 47, the third electromagnetic valve 48, the return line 45, the motor valve 46, etc. constitute the flow rate adjusting means 32.

  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 50 decreases, and if the return amount is small, the amount of fuel supplied to the burner nozzle 50 increases.

  In the state where fuel oil is supplied to the high combustion fountain nozzle 51 used for high combustion or low combustion or the low combustion fountain nozzle 53, the motor valve 46 is fully closed, and medium combustion used for medium combustion. When the fuel oil is supplied to the fuel nozzle 52, the opening degree of the motor valve 46 is adjusted, and the amount of fuel oil supplied to the flow rate adjusting means 32 is adjusted in proportion to the load state. That is, in the middle combustion load range, the return oil amount is adjusted by changing the opening of the motor valve 46, the amount of oil sprayed from the burner can be increased or decreased, and the combustion load is controlled proportionally so that the target operating pressure is reached. To do.

  At the time of ignition (low combustion), the oil pump is started by the operation signal V and the open signal Vl from the controller 19, the motor valve 46 is fully closed by the close signal Vmm, and the third electromagnetic valve 48 is opened by the open signal Vl. Is opened, and a preset low combustion oil amount is sprayed. The first solenoid valve 44 and the second solenoid valve 47 are fully closed.

  When the combustion pressure is lower than the target operating pressure after the start of combustion, the engine shifts to intermediate combustion. At this time, the motor valve 46 is set to open by the signal Vmm so that the low combustion oil amount + the intermediate combustion oil amount becomes the middle combustion lower limit load in advance. After that, the second electromagnetic valve 47 is opened by the open signal Vm and shifts to middle combustion. Thereafter, the return oil amount is adjusted to increase or decrease the opening degree of the motor valve 46 so as to reach the target pressure, and the intermediate combustion oil amount is adjusted by the open / close signal Vmm.

  Further, when the pressure drops during operation at a preset middle combustion upper limit load (load increase), the motor valve 46 is preliminarily set to the rated oil amount with a low combustion oil amount + medium combustion oil amount + high combustion oil amount by a signal Vmm. After the valve opening is set, the first solenoid valve 44 is opened by the open signal Vh (that is, the first solenoid valve 44, the second solenoid valve 47, and the third solenoid valve 48 are opened). Shifts to high combustion and prevents fluctuations in target pressure.

  When the operating pressure rises (load decreases) during continuous operation at high combustion, the opening of the motor valve 46 is set in advance by the signal Vmm so that the low combustion oil amount + medium combustion oil amount becomes the middle combustion upper limit load, Thereafter, the open signal Vh is turned OFF, the first electromagnetic valve 44 is closed, and the medium combustion is started. After that, the return oil amount is adjusted to increase or decrease the opening degree of the motor valve 46 so as to reach the target pressure by the open / close signal Vmm, and the intermediate combustion oil amount is adjusted.

  Further, when the pressure rises (load decreases) during operation at a preset middle combustion lower limit load, the motor valve 46 is fully closed by the closing signal Vmm, and then the opening signal Vm is turned OFF and the second electromagnetic valve 47 is turned on. The target pressure fluctuation is prevented by closing and shifting to low combustion.

  Also, it is necessary to change the air flow rate as the fuel flow rate changes. This is set to an air flow rate adapted to each operation load by similarly controlling the opening degree of the air damper by the above-mentioned signals (Vh, Vm (Vmh, Vmm, Vml), Vl). In the case of using an inverter for the operation of the blower, the air flow rate is adjusted according to each operation load by changing the frequency to the operation load similarly.

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 Storage part 36 Conduit 37 For combustion Air blower 38 Air damper 39 Damper motor 40 Proportional valve 41 Fuel supply line 42 Fuel supply pump 44 First solenoid valve 45 Return line 46 Motor valve 47 Second solenoid valve 48 Third solenoid valve

Claims (6)

  Burner nozzle, fuel supply line for supplying fuel to the burner nozzle, flow rate adjusting means provided in the fuel supply line and capable of adjusting the flow rate of the fuel to a flow rate corresponding to the combustion load factor, and the water level of the boiler in stages A water level detection device for detecting, a water level control unit for controlling the water level in one of a plurality of stages set based on a water level detection result from the water level detection device, a pressure detector for detecting vapor pressure, and the pressure detection A control device for controlling the flow rate adjusting means based on the vapor pressure detection result from the vessel so as to control the fuel supply amount to the burner nozzle so that the combustion load factor of the burner nozzle corresponds to the vapor pressure detection result; The control apparatus performs a staged combustion control mode in which combustion control is performed by switching a plurality of set combustion load factors, and performs proportional combustion control corresponding to the combustion load factors within a range of the set combustion load factors Example Combustion control in the combustion control mode is possible, and when the detected vapor pressure is high load or low load, the staged combustion control is executed, and when the detected vapor pressure is medium load, the proportional combustion control is executed. Once-through boiler device.   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 includes a fuel supply pump that supplies fuel from the burner nozzle, a return line that connects the downstream and upstream sides of the fuel supply pump, and a motor valve provided in the return line. The once-through boiler device according to claim 1, wherein the control device controls an opening degree of the motor valve.   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. Once-through boiler device.   The once-through boiler apparatus according to claim 3, wherein the burner nozzle has a plurality of spray nozzles, and the spray nozzle is selected according to a high combustion load factor, a medium combustion load factor, and a low combustion load factor.   This is a once-through boiler combustion control method that detects the water level in multiple stages using a water level detection device and performs staged combustion control with the combustion load factor corresponding to the water level at each stage. At the water level corresponding to the corresponding water level and low combustion load factor, the combustion is controlled in stages so as to correspond to the target load by switching the preset combustion load factor, and at the water level corresponding to the medium combustion load factor, the actual boiler A combustion control method for a once-through boiler, wherein combustion is controlled by proportional control according to an operating state.

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