JP2016061490A - Boiler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a boiler capable of easily detecting that steam has flowed backward into a boiler body.SOLUTION: A boiler 20 for configuring a boiler group 2 comprising a plurality of units of boilers 20 includes: a boiler body 21 having a plurality of water pipes 22 connected to an upper header 23 and a lower header 24; a gas-water separator 7 communicated with each of the headers 23, 24; a steam check valve 95 provided at a steam delivery line L5 connected to the gas-water separator 7; a condensate water electric conductivity sensor 422; and a determination unit 10. The condensate water electric conductivity sensor 422 detects electric conductivity of condensate water W5 generated in a region between the plurality of water pipes 22 and the steam check valve 95. The determination unit 10 determines presence/absence of flowing back of steam SM4 to the stopped boiler 20 out of the plurality of units of boilers 20, based on the detection value of the condensate water electric conductivity sensor 422.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a boiler constituting a boiler group including a plurality of boilers.

  Conventionally, a boiler body that is supplied with boiler feed water, a burner that heats the inside of the boiler body, a drainage unit that discharges boiler water stored in the boiler body to the outside, and drains the concentrated boiler water There is known a boiler including a discharge control unit that controls to discharge from the unit. In such a boiler, steam is generated by heating the boiler water in the boiler body with a burner. If the boiler is continuously operated in this state, the boiler water may be excessively concentrated. The boiler may cause a so-called “carry over” phenomenon in which a dissolved substance contained in the boiler water is mixed into the steam and carried out of the boiler.

  Thus, in the boiler, when the concentration of boiler water increases, carry-over is caused, resulting in a decrease in the dryness of steam and damage to related equipment such as valves. Therefore, a blow-down process for discharging the concentrated boiler water from the drainage unit is performed in order to improve the quality of the boiler water so that the degree of concentration does not become too high. The blow-down process is a process in which fresh makeup water is periodically supplied from the outside and a part of boiler water having a high concentration is discharged to the outside to dilute the boiler water. Further, when the boiler water is diluted and the pH value and the chemical concentration are lowered, the boiler body is corroded. Therefore, when blow-down processing is performed, chemicals such as anticorrosives (corrosion inhibitors) are added to the boiler water. ) (Hereinafter also referred to as “medical injection process”) is also executed (see, for example, Patent Document 1). In the boiler described in Patent Document 1, in the chemical injection process, it is executed to supply an amount of medicine according to the amount of makeup water to the boiler.

  By the way, in recent years, in a group of boilers composed of a plurality of boilers (for example, a multi-can installation system for small once-through boilers), a reverse flow phenomenon has been confirmed in which steam generated from a burning boiler flows into a standby boiler when combustion is stopped. (For example, see Patent Documents 2 and 3). Usually, a steam check valve for preventing the backflow of steam to the boiler is provided in the steam delivery line of the boiler. However, when the seal of the valve body and the valve seat becomes incomplete due to deterioration of the steam check valve over time, the above-described steam backflow phenomenon occurs. And the high temperature steam which flowed back changes into condensed water by absorbing heat by low-temperature parts (for example, metal material and boiler water), such as a boiler body and a steam separator.

JP-A-5-18507 JP 2013-195021 A JP 2013-204921 A

  When the backflowed steam is changed to condensed water, the boiler water is diluted with condensed water. As a result, there is a problem that the pH value of the boiler water and the silica concentration are lower than the predetermined range, and the boiler body is easily corroded.

  An object of this invention is to provide the boiler which can detect easily that the vapor | steam flowed back in the boiler main body.

  The present invention is a boiler constituting a boiler group composed of a plurality of boilers, and includes an upper header, a lower header, and a plurality of water pipes connected to the upper header and the lower header; A burner that heats the inside of the boiler body by burning, a steam separator connected to the upper header and the lower header, and a steam reverse line provided in a steam delivery line connected to the steam separator A detection value of the condensed water electrical conductivity sensor, a condensed water electrical conductivity sensor for detecting electrical conductivity of the condensed water generated in a region between the stop valve, the plurality of water pipes and the steam check valve; And a determination unit that determines whether or not there is a backflow of steam to a stopped boiler among a plurality of boilers.

  The condensed water electrical conductivity sensor detects the electrical conductivity of condensed water staying in the upper header or the electrical conductivity of condensed water staying in the steam separator, and the determination Preferably, the unit determines that a backflow of steam to the stopped boiler is occurring when the detected value of the condensed water electrical conductivity sensor exceeds a first predetermined value.

  Moreover, it further comprises a boiler water electrical conductivity sensor for detecting the electrical conductivity of boiler water, the condensed water electrical conductivity sensor is for detecting the electrical conductivity of the condensed water staying in the upper header, When the difference between the detected value of the boiler water electrical conductivity sensor and the detected value of the condensed water electrical conductivity sensor is less than a second predetermined value, the determination unit reversely flows steam to the stopped boiler. It is preferable to determine that has occurred.

  ADVANTAGE OF THE INVENTION According to this invention, the boiler which can detect easily that the vapor | steam flowed back into the boiler main body can be provided.

It is a figure showing the outline of boiler system 1 containing a plurality of boilers 20 concerning a 1st embodiment of the present invention. It is a figure which shows the relationship between the combustion pattern and priority of each boiler, and the steam pressure zone of a steam pressure control range. It is a figure showing the outline of boiler system 1 concerning a 1st embodiment of the present invention. It is a functional block diagram concerning control of boiler system 1 concerning a 1st embodiment of the present invention. It is a schematic sectional drawing which shows the electrode part 430 of the condensed water electrical conductivity sensor 422 of the boiler system 1 which concerns on 1st Embodiment of this invention. It is a schematic plan view which shows the electrode part 430 of the condensed water electrical conductivity sensor 422 of the boiler system 1 which concerns on 1st Embodiment of this invention. It is a flowchart which shows the process sequence of the backflow detection in the boiler 2 which concerns on 1st Embodiment of this invention. It is a flowchart which shows the process sequence of the backflow detection in the boiler 2 which concerns on 2nd Embodiment of this invention.

  Hereinafter, with reference to drawings, boiler system 1 concerning a 1st embodiment of the present invention is explained. FIG. 1 is a diagram showing an outline of a boiler system 1 including a plurality of boilers 20 according to the first embodiment of the present invention. FIG. 2 is a diagram showing the relationship between the combustion pattern and priority of each boiler and the steam pressure zone of the steam pressure control range.

  As shown in FIG. 1, the boiler system 1 of the present embodiment includes a boiler group 2 including a plurality (three) of boilers 20, and a steam header 50 as a steam collecting unit that collects steam generated in the boiler 20. And a vapor pressure sensor 51 as a vapor pressure measuring means and a number control device 53 as a number control means. The boiler 20 constitutes a boiler group 2 including a plurality of (three) boilers 20.

  The upstream side of the steam header 50 is connected to the boiler group 2 (each boiler 20) via a steam pipe 61. The downstream side of the steam header 50 is connected to a steam use facility 58 (load device) via a steam pipe 62. The steam header 50 collects and accumulates the steam generated in the boiler group 2 to adjust the pressure difference and pressure fluctuation of each boiler 20 and supplies the steam whose pressure is adjusted to the steam using equipment 58. It is like that.

  The vapor pressure sensor 51 is electrically connected to the number control device 53 via a signal line 71. The steam pressure sensor 51 measures the steam pressure inside the steam header 50 (the pressure of steam generated in the boiler group 2), and the number of signals (steam pressure signal) related to the measured steam pressure via the signal line 71. It transmits to the control apparatus 53.

  The boiler system 1 of the present embodiment is capable of supplying steam generated by the boiler group 2 to the steam using facility 58 via the steam header 50. The load required in the boiler system 1 (required load) is substituted by the steam pressure (physical quantity) inside the steam header 50 measured by the steam pressure sensor 51 when controlling the number of units.

  If the load increases due to an increase in demand for the steam use facility 58 and the amount of steam supplied becomes insufficient, the steam pressure inside the steam header 50 will decrease. On the other hand, if the load decreases due to a decrease in demand for the steam use facility 58 and the supply steam amount becomes excessive, the steam pressure inside the steam header 50 increases. For this reason, it is possible to monitor the load variation by the vapor pressure signal from the vapor pressure sensor 51. The boiler system 1 calculates the amount of evaporation corresponding to the amount of steam consumed by the steam using equipment 58 based on this steam pressure.

  The boiler 20 is composed of a step value control boiler having a plurality of stepwise combustion positions. A step-value control boiler controls the amount of combustion by selectively turning combustion on / off, adjusting the size of the flame, etc., and gradually changes the amount of combustion according to the selected combustion position. It is a boiler that can be increased or decreased.

  The amount of combustion at each combustion position is set so as to generate an amount of steam corresponding to the pressure difference of the steam pressure (control target) in the steam header 50 to be controlled. In each of the three boilers 20 composed of the step value control boilers, the combustion amount and the combustion capacity (combustion amount in the high combustion state) at each combustion position are set equal.

The boiler 20 in this embodiment is
1) Combustion stop state (combustion stop position: 0%)
2) Low combustion state (low combustion position: 50%)
3) High combustion state (high combustion position: 100%)
The so-called three-position control, which is controllable to the three stages of combustion states (combustion position, load factor), is performed. In this case, assuming that the combustion amount in the high combustion state is 1.0, the combustion amount of each boiler 20 can be changed in 0.5 increments.

  Note that the N position control means that the combustion amount of the step value control boiler can be controlled step by step to the N position including the combustion stop state. The number of combustion positions may be 2 positions (that is, only on / off), 4 positions (combustion stop position, low combustion position, middle combustion position, and high combustion position), or 5 positions or more.

  In the boiler group 2, a combustion pattern is set that is a combination of each boiler 20 and each combustion position. In the present embodiment, as shown in FIG. 2, the combustion pattern is “H” when the boiler is in a high combustion state, “L” when the boiler is in a low combustion state, and “−” when the combustion is in a combustion stop state. ". As the combustion pattern, a pattern having a smaller combustion amount is selected as the vapor pressure detected by the vapor pressure sensor 51 is higher, and a pattern having a larger combustion amount is selected as the vapor pressure is decreased. As shown in FIG. 2, the vapor pressure control range is divided into seven vapor pressure zones, and a corresponding combustion pattern, in other words, a combustion state (combustion position) is set for each vapor pressure zone. The amount of combustion is determined depending on which pressure zone corresponds. Seven combustion patterns are set corresponding to the seven vapor pressure zones.

  Priorities are set for the plurality of boilers 20, respectively. In the present embodiment, as shown in FIG. 2, among the three boilers 20, the priority of Unit 1 is first, the priority of Unit 2 is second, and the priority of Unit 3 is third. Is set to In the seven steam pressure zones, all boilers 20 are in the combustion stop state “−” in the highest steam pressure zone, and all boilers 20 are in the high combustion state “H” in the lowest steam pressure zone. It is. From the highest steam pressure zone to the lowest steam pressure zone, the combustion state is changed from “−” → “L” → “H” in order from Unit 1 to Unit 3.

  In the present embodiment, after the boiler having the higher priority is changed from the low combustion state “L” to the high combustion state “H”, the next highest boiler is changed from the combustion stop state “−” to the low combustion state “L”. Is changed. After the boiler with the highest priority is changed from the combustion stop state “−” to the low combustion state “L” and before it is changed to the high combustion state “H”, the boiler with the next highest priority is stopped. The state “−” may be changed to the low combustion state “L”.

  As shown in FIG. 1, the boiler 20 measures a boiler body 21 in which combustion is performed, a local control device 25 that controls a combustion position (combustion state) of each boiler 20, and a vapor pressure inside each boiler 20. And a local vapor pressure measuring unit 29 as vapor pressure measuring means.

  The local control device 25 can control each boiler 20 and change the combustion position (combustion state) according to the required load. The local control device 25 controls each boiler 20 based on the number control signal from the number control device 53 during the number control, and directly controls the boiler 20 during the local control.

  The local vapor pressure measurement unit 29 is constituted by, for example, a vapor pressure sensor and a vapor pressure switch or only a vapor pressure switch, and measures the vapor pressure inside the upper header 23 (described later) of each boiler 20. The local vapor pressure measurement unit 29 measures the vapor pressure used when performing local control of each boiler 20.

  Each boiler 20 is electrically connected to the number control device 53 via a signal line 72. Each boiler 20 is supplied with makeup water W1 and fuel F. From each boiler 20, dry steam SM2 is sent out (see FIG. 3). Each boiler 20 and the configuration around each boiler 20 will be described later.

  The local control device 25 transmits a signal used by the number control device 53 during the number control to the number control device 53 via the signal line 72. Examples of the signal used in the number control device 53 include a signal such as a load required for the boiler 20, an actual combustion state of the boiler 20, and other data. In addition, when the controlled boiler 20 is operable, the local control device 25 transmits a signal indicating that the boiler 20 is operable (operable signal) to the number control device 53 via the signal line 72.

  When the number control is performed, the local control device 25 shifts the combustion position to the lower side (to the combustion stop position) when the steam pressure inside the steam header 50 measured by the steam pressure sensor 51 becomes higher. The combustion of each boiler 20 is reduced so that the amount of evaporation is reduced, while when the vapor pressure inside the steam header 50 becomes low, the combustion position is shifted to the higher side to increase the amount of evaporation. Control the position.

  When local control is performed, the local control device 25 shifts the combustion position to the lower side (combustion stop position) when the steam pressure inside the boiler 20 measured by the local steam pressure measuring unit 29 becomes higher. The combustion of each boiler 20 is reduced so that the amount of evaporation is reduced, while when the vapor pressure inside the boiler 20 becomes low, the combustion position is shifted to the higher side to increase the amount of evaporation. Control the position.

  The number control device 53 is electrically connected to each boiler 20 via a signal line 72. The number control device 53 controls the number of the boilers 20 so that the boilers 20 are operated with high boiler efficiency (combustion efficiency). In addition, when local control is performed in each boiler 20, the number control by the number control device 53 is not performed.

  The number control device 53 calculates the required combustion amount of the boiler group 2 and the combustion state of each boiler 20 corresponding to the required combustion amount based on a signal such as a required load received from each boiler 20. A unit number control signal is transmitted to the local control device 25. Thereby, the number control device 53 controls the amount of combustion of each boiler 20 and controls the number of boiler groups 2.

  The number control device 53 receives the vapor pressure signal from the vapor pressure sensor 51 via the signal line 71. The number control device 53 sets a necessary combustion amount corresponding to the required load based on the vapor pressure signal from the vapor pressure sensor 51, and instructs each boiler 20 to change the combustion position according to the necessary combustion amount. A combustion amount of the boiler 20 is controlled.

  More specifically, the number control device 53 selects a combustion pattern based on the vapor pressure measured by the vapor pressure sensor 51 so that the vapor pressure falls within a predetermined vapor pressure control range (see FIG. 2). The number control device 53 instructs the boiler 20 to raise the combustion position from the combustion stop position to the low combustion position or from the low combustion position to the high combustion position when the combustion amount is insufficient due to fluctuations in the required load. . If the combustion amount is excessive due to fluctuations in the required load, an instruction to lower the combustion position from the high combustion position to the low combustion position, from the low combustion position to the combustion stop position, or from the high combustion position to the combustion stop position, To 20.

  In addition, combustion of the boiler 20 or its stop can also be handled per virtual boiler. In the virtual boiler, differences in combustion position (combustion amount) in the boiler (low combustion position, medium combustion position, high combustion position, etc.) are regarded as independent boilers, and the respective evaporation amounts are virtually assumed in the boiler. For example, in the case of an on / off boiler (two-position boiler), there is one virtual boiler, which matches the actual number of physical boilers. Further, even if the three-position boiler is physically one unit, it can be virtually counted as two units of a low combustion amount boiler and a (high combustion amount-low combustion amount) boiler. The four-position boiler can be virtually counted as a low combustion amount boiler, a (medium combustion amount-low combustion amount) boiler, and a (high combustion amount-medium combustion amount) boiler. Therefore, if the three-position boiler is in a low combustion state, it can be handled for control if a combustion instruction is given to the low combustion amount boiler, while the (high combustion amount−low combustion amount) boiler can be handled. On the other hand, if a combustion stop instruction is given, it can be handled for control.

  The number control device 53 is connected to the local control device 25 of each boiler 20 via a signal line 72. The number control device 53 gives various instructions to the local control device 25 of each boiler 20 via the signal line 72 and receives various data from the local control device 25 to the three boilers 20. The above control is performed. When the local control device 25 of each boiler 20 receives a combustion position change instruction signal from the number control device 53, it controls the boiler 20 according to the instruction. If the actual combustion amount is insufficient with respect to the required combustion amount determined from the load amount of the boiler system having a plurality of boilers, the combustion instruction is given to the boiler 20, and if the actual combustion amount is excessive, The boiler 20 is instructed to stop combustion.

  Next, the configuration of each boiler 20 and the configuration around each boiler 20 will be described. FIG. 3 is a diagram showing an outline of the boiler system 1 according to the first embodiment of the present invention. FIG. 4 is a functional block diagram relating to control of the boiler system 1 according to the first embodiment of the present invention. FIG. 5 is a schematic cross-sectional view showing the first condensed water electrical conductivity sensor 422 of the boiler system 1 according to the first embodiment of the present invention. FIG. 6 is a schematic plan view showing the first condensed water electrical conductivity sensor 422 of the boiler system 1 according to the first embodiment of the present invention. Since each boiler 20 has the same configuration, only one boiler 20 will be described.

  As shown in FIG. 3, the boiler system 1 includes a boiler 20, a hard water softening device 3, a water supply tank 5, a corrosion inhibitor adding device 81, a steam header 50, and a hardness sensor 41. In FIG. 3, the path of electrical connection is indicated by a broken line.

  The boiler system 1 includes a makeup water line L1, a fuel supply line L2, a blow line L3 as a discharge unit, a steam extraction line L4, a steam delivery line L5 as a steam pipe 61, and a precipitation line L6. A drug addition line L7. The “line” in the present specification is a general term for lines capable of flowing a fluid such as a flow path, a path, and a pipeline. In addition, the “boiler feed water” in this specification means water supplied to the boiler body 21 (supplementary water such as soft water or pure water, or water in which condensate and make-up water are mixed in the case of condensate recovery). means. “Boiler water” means water stored in the boiler body (including both non-concentrated and concentrated states).

  The boiler 20 is a device that generates steam to be supplied to a steam using facility (not shown). The boiler 20 includes a boiler body 21, a burner 27, a combustion chamber 26, a water level detector 28 as a water level detecting means, Feed water pump 6 as boiler water supply means, steam separator 7, control device 10 as a determination unit, blow valve 93, main steam valve 94, steam check valve 95, boiler water electrical conductivity A sensor 421, a first condensed water electrical conductivity sensor 422 as a condensed water electrical conductivity sensor, and a second condensed water electrical conductivity sensor 423 are provided. The boiler body 21 forms a pressure vessel including a plurality of water pipes 22, an upper header 23, and a lower header 24.

As will be described later, the boiler 20 according to the present embodiment has a multi-tube once-through boiler structure. In addition, the one with a gauge pressure of 1 MPa or less and a heat transfer area of 10 m ² or less is referred to as a small once-through boiler (Occupational Safety and Health Law Enforcement Ordinance, Article 4, Item 4).

  The makeup water line L <b> 1 is a line that supplies makeup water (boiler feed water) W <b> 1 to the boiler body 21. The upstream end of the makeup water line L1 is connected to a supply source (not shown) of the makeup water W1. The downstream end of the makeup water line L1 is connected to a lower header 24 (described later) of the boiler body 21. The makeup water line L1 is provided with a water softening device 3, a hardness sensor 41, a water supply tank 5, a connection portion J1, and a water supply pump 6 in order from the supply source to the boiler 20.

  The hard water softening device 3 generates soft water by replacing hardness components contained in raw water such as tap water, ground water, and industrial water with sodium ions (or potassium ions). The water softening device 3 has a cation exchange resin bed 3a. The cation exchange resin bed 3a performs water softening treatment of the makeup water W1 supplied to the boiler body 21. The hard water softening device 3 supplies treated water (soft water) obtained by softening the raw water W0 with the cation exchange resin bed 3a toward the boiler 20 as make-up water (boiler feed water) W1.

  The hardness sensor 41 detects the hardness of the makeup water W <b> 1 softened by the water softening device 3. Information regarding the hardness of the makeup water W1 detected by the hardness sensor 41 is transmitted to the control device 10 as a detection signal.

  The water supply tank 5 stores the treated water softened by the hard water softening device 3 as makeup water W1. The makeup water W <b> 1 stored in the feed water tank 5 is supplied to the boiler body 21 by the feed water pump 6. The feed water pump 6 sucks the makeup water W1 from the feed water tank 5, and sends the makeup water W1 flowing through the makeup water line L1 toward the boiler body 21. The feed water pump 6 is electrically connected to the control device 10. The timing at which the feed water pump 6 sends the makeup water W1 to the boiler body 21 is controlled by a drive signal transmitted from the control device 10.

  The downstream end of the drug addition line L7 is connected to the connecting part J1. A corrosion inhibitor addition device 81 is connected to the upstream end of the chemical addition line L7. The corrosion inhibitor adding device 81 is a device that adds (supplies) a corrosion inhibitor (chemical) to the makeup water W <b> 1 supplied to the boiler body 21. The corrosion inhibitor addition device 81 can execute a chemical supply process for supplying a corrosion inhibitor to the boiler water W2 stored in the boiler body 21 so that the corrosion-inhibiting water quality can suppress the corrosion of the boiler body 21. . The corrosion inhibitor is a chemical mainly used for suppressing corrosion of the water pipe 22 and the lower header 24.

  The corrosion inhibitor adding device 81 is electrically connected to the control device 10. The timing and amount of addition of the corrosion inhibitor from the corrosion inhibitor addition device 81 to the connection portion J1 of the makeup water line L1 are controlled by a drive signal transmitted from a corrosion inhibitor addition control unit 103 (described later) of the control device 10. Is done.

  The boiler body 21 is composed of a group of water pipes erected in the vertical direction between upper and lower headers, and constitutes the main part of the outer shape of the boiler 20. In the boiler body 21, supply water W1 supplied through the supply water line L1 is stored as boiler water W2. The boiler water W2 includes water that once accumulates in the boiler body 21 as the boiler water W2 and then taken out as steam and returns to the boiler body 21. For example, the boiler water W <b> 2 includes separated water W <b> 4 that is separated by the steam separator 7 (described later) and returned to the boiler body 21.

  The plurality of water pipes 22 are arranged extending in the vertical direction of the boiler body 21. The upper header 23 is disposed on the upper portion of the boiler body 21. The upper header 23 is configured by, for example, an annular container. The upper header 23 is connected to the upper ends of a plurality of water pipes 22. The upper header 23 is connected to one end of a steam extraction line L4 described later.

  A first condensed water electrical conductivity sensor 422 is attached to the upper header 23. As will be described later, wet steam SM1 is generated from the boiler water W2 in the heated water pipe 22 and becomes dry steam SM2 in the steam separator 7. The dry steam SM2 is sent to the steam header 50 through the steam delivery line L5. The first condensate electric conductivity sensor 422 is configured such that, among the steam SM3 accumulated in the steam header 50, the backflow steam SM4 that has flowed back through the steam delivery line L5 and the steam discharge line L4 due to the malfunction of the steam check valve 95 is generated. It is a sensor which detects the electrical conductivity of the condensed water which stays in the upper header 23 among the condensed water W5 produced by cooling. The first condensed water electrical conductivity sensor 422 is electrically connected to the control device 10. The detection value of the first condensed water electrical conductivity sensor 422 is transmitted to the control device 10 as a detection signal. The electrode part of the first condensed water electrical conductivity sensor 422 will be described later.

  The lower header 24 is disposed below the boiler body 21. The lower header 24 is constituted by, for example, an annular container. The lower header 24 is connected to the lower ends of a plurality of water pipes 22. One end of the side wall of the lower header 24 is connected to the end of the makeup water line L1. The other end of the side wall of the lower header 24 is connected to the end of the precipitation line L6. The combustion chamber 26 is configured by a space surrounded by a plurality of water pipes 22.

  The burner 27 heats the inside of the boiler body 21 by burning. The burner 27 is disposed in the central portion on the upper side of the boiler body 21. The burner 27 includes a fuel injection nozzle and an air supply nozzle (both not shown). The burner 27 injects fuel from the fuel injection nozzle toward the combustion chamber 26 of the boiler body 21 and supplies air from the air supply nozzle into the boiler body 21 to burn the fuel.

  The water level detector 28 is a device that can continuously detect the water level of the boiler water W2 stored in the water pipe 22 (boiler body 21). The water level detector 28 is electrically connected to the control device 10. The detection signal of the boiler water W2 detected by the water level detector 28 is transmitted to the control device 10.

  In the present embodiment, the water level detector 28 is a continuous level sensor, and for example, a capacitance type sensor, a pressure type sensor, an ultrasonic type sensor or the like is used. FIG. 3 shows an example in which a capacitive sensor is provided as the water level detector 28. The water level detector 28 includes a water level detection cylinder 28a and an electrode rod 28b. The upper end of the water level detection cylinder 28a is connected to the upper header 23 via a connection line. The lower end portion of the water level detection cylinder 28a is connected to the lower header 24 via a connection line. The water level detection cylinder 28 a has an upper end connected to the upper header 23 and a lower end connected to the lower header 24, thereby storing the boiler water W <b> 2 at the same level as the water pipe 22. The water level detector 28 uses the insulating film coated on the surface of the electrode rod 28b as a dielectric, and measures the electrostatic capacitance between the electrode rod 28b and the water level detection tube 28a, so that the water level detector 28a is inside the water level detection tube 28a. It is possible to detect the water level of the boiler water W2 in contact with the electrode rod 28b. The water level detector 28 can continuously detect the change in the water level of the boiler water W2 inside the water level detection cylinder 28a based on the change in the measured capacitance.

  The fuel supply line L <b> 2 is a line that supplies the fuel F burned by the burner 27 to the burner 27. The upstream end of the fuel supply line L2 is connected to a fuel F supply source (not shown). The downstream end of the fuel supply line L2 is connected to the burner 27. A fuel supply valve 92 is provided in the fuel supply line L2. The fuel supply valve 92 is a valve that adjusts the amount of fuel supplied to the burner 27. The fuel supply valve 92 can open and close the fuel supply line L2. The opening and closing of the fuel supply valve 92 is controlled by a drive signal from the control device 10.

  The steam extraction line L4 is a line that takes out the wet steam SM1 generated from the boiler water W2 in the water pipe 22 from the upper header 23 and introduces it into the steam separator 7. The upstream end of the steam extraction line L4 is connected to the upper surface of the upper header 23 of the boiler body 21. The downstream end portion of the steam extraction line L4 is connected to the upper side of the side portion of the steam / water separator 7.

  The steam separator 7 is a device that separates the wet steam SM1 introduced from the upper header 23 through the steam extraction line L4 into dry steam SM2 and moisture (hereinafter also referred to as “separated water W4”). As described above, the separated water W4 separated by the steam separator 7 is also a part of the boiler water W2.

  The steam delivery line L <b> 5 is a line that sends out the dry steam SM <b> 2 separated by the steam separator 7 toward the steam header 50. The upstream end of the steam delivery line L5 is connected to the upper surface of the steam separator 7. The downstream end of the steam delivery line L <b> 5 is connected to the steam header 50.

  The steam delivery line L5 is provided with a main steam valve 94, a steam check valve 95, and a steam header 50 in order from the steam / water separator 7 to a load device (not shown). The main steam valve 94 is a valve that can manually switch the open / close state of the steam delivery line L5. The steam check valve 95 is a valve that prevents the backflow of the steam SM3 from the steam header 50. The steam header 50 is equipment for collecting dry steam SM2 from a plurality of installed boilers (not shown) and distributing the collected steam SM3 to steam using equipment (not shown).

  The precipitation line L6 is a line that causes the separated water W4 separated by the steam separator 7 to flow toward the lower header 24 of the boiler body 21. The upstream end of the precipitation line L6 is connected to the lower part of the steam separator 7. The downstream end of the precipitation line L <b> 6 is connected to the lower header 24. The precipitation line L6 is provided with a connection portion J2, and a boiler water electrical conductivity sensor 421 is attached to the lower header 24 side of the connection portion J2. Moreover, the 2nd condensed water electrical conductivity sensor 423 is attached to the steam-water separator 7 side of the connection part J2.

  The boiler water electrical conductivity sensor 421 is a sensor that detects the electrical conductivity of the boiler water W2 (separated water W4). The electrode part of the boiler water electrical conductivity sensor 421 is located at a lower height than the water surface of the boiler water W2 of the water pipe 22. The boiler water electrical conductivity sensor 421 is electrically connected to the control device 10. The detection value of the boiler water electrical conductivity sensor 421 is transmitted to the control device 10 as a detection signal.

  The second condensate electric conductivity sensor 423 is generated by cooling the back-flow steam SM4 flowing back through the steam delivery line L5 due to the malfunction of the steam check valve 95 among the steam SM3 accumulated in the steam header 50. It is a sensor which detects the electrical conductivity of the condensed water which stays in the steam separator 7 among the condensed water W5. The second condensed water electrical conductivity sensor 423 is electrically connected to the control device 10. The detection value of the second condensed water electrical conductivity sensor 423 is transmitted to the control device 10 as a detection signal.

  As shown in FIGS. 5 and 6, the first condensed water electrical conductivity sensor 422 and the second condensed water electrical conductivity sensor 423 include an electrode portion 430 having a first electrode 431 and a second electrode 432. . The first electrode 431 and the second electrode 432 of the first condensed water electrical conductivity sensor 422 and the first electrode 431 and the second electrode 432 of the second condensed water electrical conductivity sensor 423 have the same configuration. Yes. Therefore, in the following description, only the first electrode 431 and the second electrode 432 of the first condensed water electrical conductivity sensor 422 will be described.

  The first electrode 431 has a substantially cylindrical shape. A central portion in the longitudinal direction of the first electrode 431 has a large diameter portion 434 having a large inner diameter and outer diameter. The large diameter portion 434 is fixed in the lower wall portion of the upper header 23. One end portion of the first electrode 431 in the longitudinal direction protrudes upward from the upper surface of the lower wall portion of the upper header 23. One end of the first electrode 431 in the longitudinal direction has a notch 437 (see FIG. 6) extending in the direction of the other end from one end in the longitudinal direction of the first electrode 431 to the insulating member 435. Further, a drain notch 438 is provided on the opposite side of the notch 437 in the radial direction in a cross-sectional view. The drain notch 438 is provided in a part of the first electrode 431 in the longitudinal direction.

  The other end portion in the longitudinal direction of the first electrode 431 protrudes downward from the lower surface of the lower wall portion of the upper header 23. A nut 433 is screwed to the other end. The space surrounded by the inner surface of the large diameter portion 434 is filled with an insulating member 435 and fixed. The second electrode 432 has a straight bar shape. The second electrode 432 is supported by the insulating member 435 and is fixed to the first electrode 431 in a positional relationship that coincides with the axial center position of the first electrode 431. As shown in FIG. 5, one end portion of the second electrode 432 protrudes upward from the insulating member 435 and is surrounded by one end portion of the first electrode 431.

  Condensed water W5 generated by cooling the backflow steam SM4 can flow from the notch 437 into the space 436 surrounded by one end of the first electrode 431 as indicated by an arrow A. When the condensed water W5 existing in the space 436 comes into contact with the first electrode 431 and the second electrode 432, the electric conductivity of the condensed water staying in the upper header 23 can be detected.

  In the case of the second condensed water electrical conductivity sensor 423, the axial centers of the first electrode 431 and the second electrode 432 have a positional relationship extending horizontally. That is, the electrode part of the 2nd condensed water electrical conductivity sensor 423 is attached to the horizontal direction with respect to the precipitation line L6 plumbed vertically. The attached electrode part protrudes into the precipitation line L6, and the notch part 437 is located above. As a result, the condensed water W5 flowing into the space 436 from the notch 437 temporarily contacts the first electrode 431 and the second electrode 432, and therefore the condensed water staying in the steam separator 7 is used. The electrical conductivity can be detected. Then, as shown by the arrow B, the condensed water W5 can flow out of the space 436 through the drainage notch 438.

  The upstream end of the blow line L3 is connected to the connecting part J2. The blow line L3 is a line that discharges the separated water W4 (boiler water W2) flowing through the precipitation line L6 (precipitation pipe) to the outside of the boiler 20 through the connection portion J2. A blow valve 93 is provided in the blow line L3. The blow valve 93 can open and close the blow line L3. The opening / closing of the blow valve 93 is controlled by a drive signal from the control device 10. By opening the blow valve 93, the separated water W4 (boiler water W2) flowing through the precipitation line L6 (precipitation pipe) is discharged to the outside.

  Next, with reference to FIG. 4, the function which concerns on control of the boiler system 1 of this embodiment is demonstrated. The control apparatus 10 controls each part in the boiler system 1 of this embodiment. The control device 10 is electrically connected to each measurement device in the boiler system 1 and receives measurement information from each measurement device. Further, the control device 10 is electrically connected to the feed water pump 6 and controls the feed water pump 6 so as to send the makeup water W <b> 1 toward the boiler 20 in accordance with the water level of the boiler water W <b> 2 in the boiler body 21.

  In addition, the control device 10 includes a control unit 100 and a memory unit 110. The control unit 100 includes a valve control unit 101, a timer unit 102, and a corrosion inhibitor addition control unit 103.

  The valve control unit 101 controls the open / close state of the fuel supply valve 92 and the blow valve 93. The timer unit 102 measures an operation stop time after the boiler 20 stops operating.

  The controller 100 supplies the makeup water W1 to the boiler body 21 so that the amount of the boiler water W2 stored in the boiler body 21 becomes the preset reference water storage amount X when the boiler 20 is started. The feed water pump 6 is controlled. Thereby, the amount of boiler water W2 stored in the boiler body 21 is maintained at a preset reference water storage amount X.

  The corrosion inhibitor addition control unit 103 performs a chemical suppression process for adding a corrosion inhibitor to the boiler water W <b> 2 stored in the boiler body 21 so as to obtain a corrosion-suppressed water quality that can suppress the corrosion of the boiler body 21. This can be performed by the agent addition device 81. Thereby, the water quality of the boiler water W2 maintained at the reference water storage amount X is maintained to be the corrosion-inhibiting water quality.

  The memory unit 110 stores a control program for operating the boiler system 1 of the present embodiment, predetermined parameters, various tables, and the like. In the present embodiment, the memory unit 110 includes, for example, a first predetermined value that is compared with a detected value of the first condensed water electrical conductivity sensor 422 or a detected value of the second condensed water electrical conductivity sensor 423, or boiler water. A second predetermined value to be compared with the difference between the detected value of the electrical conductivity sensor 421 and the detected value of the first condensed water electrical conductivity sensor 422 is stored. In addition, the memory unit 110 includes, for example, the detected water level value when the boiler 20 is stopped, and the makeup water W <b> 1 supplied to the boiler body 21 that is necessary to obtain a corrosion-suppressing water quality that can suppress the corrosion of the boiler body 21. The amount of corrosion inhibitor added corresponding to the amount is stored. Further, the memory unit 110 stores the amount of water stored in the boiler water W2 corresponding to the detected water level value of the boiler water W2.

  Next, the operation of the boiler system 1 of the present embodiment will be briefly described with reference to FIG. First, the makeup water W1 is supplied to the water supply tank 5 from a supply source (not shown). At this time, the makeup water W1 supplied from the supply source is removed from the hardness component in the water softening device 3 and becomes softened water. Then, the softened water generated by the hard water softening device 3 is stored in the water supply tank 5 as makeup water (boiler feed water) W1. Here, the fuel supply valve 92 and the blow valve 93 are closed.

  Next, by operating the feed water pump 6, the makeup water W1 (boiler feed water) stored in the feed water tank 5 is sent out toward the lower header 24 of the boiler body 21 through the makeup water line L1. The makeup water W1 supplied to the boiler 20 is stored as boiler water W2 in the lower header 24 and each water pipe 22.

  The feed water pump 6 supplies makeup water W1 to the boiler body 21 so that the amount of boiler water W2 stored in the boiler body 21 becomes a preset reference water storage amount X. The makeup water W1 supplied to the boiler body 21 is stored as boiler water W2 in the lower header 24 and each water pipe 22. When the makeup water W <b> 1 is supplied to the lower header 24 and each water pipe 22, the corrosion inhibitor addition control unit 103 corresponds to the makeup water W <b> 1 so that the corrosion suppression water quality can suppress the corrosion of the boiler body 21. The corrosion inhibitor adding device 81 is controlled so as to supply the corrosion inhibitor. Thereby, about the pH value of boiler water W2, acid consumption (pH 8.3), or silica concentration, it maintains so that it may become a corrosion suppression water quality.

  Next, the fuel is supplied to the burner 27 by switching the fuel supply valve 92 from the closed state to the open state. When the burner 27 is ignited, the burner 27 starts combustion.

  The boiler water W2 stored in the lower header 24 and each water pipe 22 rises inside each water pipe 22 while being heated by the burner 27 through the water pipe wall, and then becomes wet steam SM1. And the wet steam SM1 produced | generated inside each water pipe 22 is collected by the upper header 23, and is introduce | transduced into the steam-water separator 7 via the steam extraction line L4.

  The wet steam SM1 introduced into the steam separator 7 is separated into dry steam SM2 and separated water W4. The dry steam SM2 separated by the steam separator 7 is collected in the steam header 50 through the steam delivery line L5 by switching the main steam valve 94 from the closed state to the open state. The steam SM3 collected in the steam header 50 is supplied to a steam using device (not shown). The separated water W4 separated by the steam separator 7 is returned to the lower header 24 through the precipitation line L6.

When the operation of the boiler 20 is stopped, for example, when the sealing performance of the steam check valve 95 deteriorates due to aging or the like, steam may flow backward from the steam header 50 to the boiler body 21. The backflow steam SM4 is stored as condensed water W5 in the boiler body 21. The boiler body 21 is supplied with make-up water W1 so that the boiler water W2 has a preset reference water storage amount X when the boiler 20 is started. The boiler water W2 is supplied with an amount of corrosion inhibitor corresponding to the amount of water supplied to the supplied makeup water W1.
The boiler 20 which concerns on this invention performs the process of the flowchart shown in FIG. 7 as follows.

  Next, an operation in which the first condensed water electrical conductivity sensor 422 detects the condensed water W5 generated from the backflow steam SM4 during the period from the stop of operation to the next activation in the boiler 20 of the present embodiment will be described. FIG. 7 is a flowchart showing a processing procedure of backflow detection in the boiler 2 according to the first embodiment of the present invention.

  As shown in FIG. 7, in step ST <b> 11, the boiler system 1 stops the operation of the boiler 20. The timer unit 102 starts measuring the operation stop time after the operation of the boiler 20 is stopped.

  In step ST12, the control device 10 measures whether or not the operation stop time of the boiler 20 timed by the timer unit 102 has passed a predetermined time. The predetermined time is, for example, 1 hour. When the operation stop time of the boiler 20 has elapsed (YES), the process proceeds to step ST13. On the other hand, if the operation stop time of the boiler 20 does not elapse (NO), the process returns to step ST12.

  In step ST13, the control apparatus 10 determines the presence or absence of the backflow of the vapor | steam to the boiler 20 which has stopped among several boilers based on the detected value of the 1st condensed water electrical conductivity sensor 422. Specifically, the electrical conductivity of the condensed water W5 staying in the upper header 23 is detected by the first condensed water electrical conductivity sensor 422, and it is determined whether or not the detected value exceeds the first predetermined value. The control apparatus 10 performs. The control device 10 determines that there is a backflow of steam to the boiler 20 when the detection value of the first condensed water electrical conductivity sensor 422 exceeds the first predetermined value. Here, the first predetermined value is, for example, 3 μS / cm. A very small amount of boiler water W2 remains in the dry steam SM2 generated by the steam separator 7, and the boiler water W2 contained in the wet steam SM1 adheres to the inner wall of the steam extraction line L4. doing. Therefore, an electrical conductivity of about 5 μS / cm is detected in the condensed water W5 generated from the backflow steam SM4. In the state in which the backflow steam SM4 does not flow into the upper header 23 and the condensed water W5 is not in contact with the first electrode 431 and the second electrode 432, the detection value of the first condensed water electrical conductivity sensor 422 is 0 μS / cm.

  When the detected value of the first condensate water conductivity sensor 422 exceeds the first predetermined value (YES), the control device 10 indicates that a backflow of steam to the stopped boiler 20 has occurred. The process of the control device 10 is determined and proceeds to step ST14. On the other hand, when the detected value of the first condensed water conductivity sensor 422 does not exceed the first predetermined value (NO), the process of the control device 10 returns.

  In step ST14, the control device 10 performs a process for the backflow of steam. Specifically, the following four processing patterns are exemplified.

  (1) When it is determined that there is a backflow of steam to the boiler 20, the control device 10 controls the corrosion inhibitor addition device 81 of the boiler 20 via the corrosion inhibitor addition control unit 103. More specifically, the corrosion inhibitor addition control unit 103 calculates a stored water amount Y at the time of stopping the boiler water W2 stored in the boiler body 21 based on a detected water level value of the boiler water W2 when the operation of the boiler 20 is stopped. Then, the corrosion inhibitor addition control unit 103 calculates a stop water shortage amount Z obtained by subtracting the stop time storage amount Y from a preset reference water storage amount X. Then, the corrosion inhibitor addition control unit 103 adds the amount of corrosion inhibitor necessary for the water quality of the boiler water W2 having the insufficient water amount Z at the time of stoppage to become the corrosion-suppressing water quality when the target boiler 20 is started next time. As described above, the chemical supply processing is executed in the corrosion inhibitor addition apparatus 81. Thereby, even if a vapor | steam flows backward to the boiler main body 21, the water quality of the boiler water W2 is maintained so that it may become a corrosion suppression water quality.

  (2) When it is determined that there is a backflow of steam to the boiler 20, the control device 10 controls the number control device 53 so as to raise the priority of the boiler 20. As a result, the time until the boiler 20 that has been shut down is changed to the next combustion state is shortened, and the diluted state of the boiler water W2 is quickly eliminated.

  (3) When it is determined that there is a backflow of steam to the boiler 20, the control device 10 controls the burner 27 so as to forcibly burn in the boiler 20. Thereby, concentration of the boiler water W2 of the boiler 20 which has stopped operation proceeds, and the water quality reaches the corrosion-suppressed water quality.

  (4) When the control device 10 determines that there is a backflow of steam to the boiler 20, a notification device (not shown) so as to prompt the administrator of the boiler system 1 to maintain the steam check valve 95. Notification of the occurrence of an abnormality is performed via

  According to the boiler 20 which concerns on 1st Embodiment mentioned above, the following effects are acquired, for example.

  The boiler 20 in this embodiment constitutes a boiler group including a plurality of boilers, a boiler body 21 having a plurality of water pipes 22, a burner 27 that heats the inside of the boiler body 21 by burning, and an upper header 23. And the steam / water separator 7 communicated with the lower header 24, a steam check valve 95 provided in the steam delivery line L 5 connected to the steam / water separator 7, a plurality of water pipes 22 and a steam check valve 95, Based on the detected values of the condensed water electrical conductivity sensors 422 and 423 and the condensed water electrical conductivity sensors 422 and 423 for detecting the electrical conductivity of the condensed water W5 generated in the region between the boilers 20 And a control device 10 as a determination unit that determines whether or not the steam SM4 flows backward to the boiler 20 that is stopped.

  Therefore, the stay of the condensed water W5 generated from the backflow steam SM4 can be easily detected from the detection values of the condensed water electrical conductivity sensors 422 and 423. Thereby, the control apparatus 10 can start the process with respect to backflow generation | occurrence | production of a vapor | steam.

  Further, the control device 10 as the determination unit stops when the detection value of the first condensate water conductivity sensor 422 or the detection value of the second condensate water conductivity sensor 423 exceeds the first predetermined value. It is determined that the back flow of the steam SM4 to the boiler 20 is occurring. Therefore, by setting the first predetermined value to be an extremely small value, it is possible to reliably detect the condensed water W5 staying in the upper header 23 and to improve the accuracy of determining the steam backflow.

  Next, the boiler by 2nd Embodiment is demonstrated based on FIG. FIG. 8 is a flowchart showing a processing procedure of backflow detection in the boiler 2 according to the second embodiment of the present invention.

  In the boiler according to the second embodiment, the processing by the control device 10 is different from the processing by the control device 10 of the boiler 20 according to the first embodiment. In other words, the control device 10 determines whether the boiler 20 is stopped among the plurality of boilers 20 based on the difference between the detected value of the boiler water conductivity sensor 421 and the detected value of the first condensed water conductivity sensor 422. The presence or absence of the back flow of the steam SM4 to is determined. Since the configuration other than this is the same as the configuration of the boiler 20 according to the first embodiment, the description of the same configuration is omitted.

  Hereinafter, the condensed water W5 generated from the backflow steam SM4 is detected by the boiler water electrical conductivity sensor 421 and the first condensed water electrical conductivity sensor 422 between the time when the operation of the boiler 20 of the present embodiment is stopped and the next time it is started. The operation to be performed will be described.

  As shown in FIG. 8, in step ST21, the boiler system 1 stops the operation of the boiler 20. The timer unit 102 starts measuring the operation stop time after the operation of the boiler 20 is stopped.

  In step ST22, the control device 10 measures whether or not the operation stop time of the boiler 20 timed by the timer unit 102 has passed a predetermined time. The predetermined time is, for example, 1 hour. When the operation stop time of the boiler 20 has elapsed (YES), the process proceeds to step ST23. On the other hand, when the operation stop time of the boiler 20 does not elapse (NO), the process returns to step ST22.

  In step ST23, the electrical conductivity of the condensed water W5 staying in the upper header 23 is detected by the first condensed water electrical conductivity sensor 422. And the control apparatus 10 judges whether the detection value of the 1st condensed water electrical conductivity sensor 422 exceeded the 1st predetermined value. Here, the first predetermined value is, for example, 3 μS / cm. A very small amount of boiler water W2 remains in the dry steam SM2 generated by the steam separator 7, and the boiler water W2 contained in the wet steam SM1 adheres to the inner wall of the steam extraction line L4. doing. Therefore, an electrical conductivity of about 5 μS / cm is detected in the condensed water W5 generated from the backflow steam SM4. In the state in which the backflow steam SM4 does not flow into the upper header 23 and the condensed water W5 is not in contact with the first electrode 431 and the second electrode 432, the detection value of the first condensed water electrical conductivity sensor 422 is 0 μS / cm.

  When the detected value of the 1st condensed water electrical conductivity sensor 422 exceeds the 1st predetermined value (YES), the process of the control apparatus 10 transfers to step ST24. On the other hand, when the detected value of the first condensed water conductivity sensor 422 does not exceed the first predetermined value (NO), the process of the control device 10 returns.

  In step ST24, the control apparatus 10 acquires the detection value (A value) of the boiler water electrical conductivity sensor 421. Moreover, the control apparatus 10 acquires the detection value (B value) of the 1st condensed water electrical conductivity sensor 422. FIG. And the control apparatus 10 calculates the difference (AB) of these detection values. And the process of the control apparatus 10 transfers to step ST25.

  In step ST25, the control device 10 determines whether or not the difference (A−B) in the detection values calculated in step ST24 is below a second predetermined value. Here, the second predetermined value is, for example, 1795 μS / cm. The detected value of the boiler water electrical conductivity sensor 421 is the separated water W4 (boiler water W2 carried over) in the steam separator 7 when the boiler is operating, and is about 2000 μS / cm when the concentration is sufficiently high. Indicates the value of.

  During the boiler operation, the enrichment becomes higher toward the water surface of the water pipe 22 from the lower header 24. Therefore, when a predetermined time elapses after the boiler stops, the whole boiler water W2 is mixed and the boiler water conductivity is increased. The detection value of the sensor 421 is slightly reduced to show a value of about 1800 μS / cm. On the other hand, as described above, the detected value of the first condensed water conductivity sensor 422 shows a value of about 5 μS / cm when the condensed water W5 generated from the backflow steam SM4 stays. When the condensed water W5 does not stay, it becomes 0 μS / cm. Therefore, when a backflow occurs, the difference between the detection value of the boiler water conductivity sensor 421 and the detection value of the first condensed water conductivity sensor 422 (for example, 1795 μS / cm) indicates that the backflow occurs. It becomes smaller than the difference (for example, 1800 μS / cm) in the absence.

  Therefore, when the difference (A−B) in the detected values is less than the second predetermined value (YES), the control device 10 determines that the backflow of steam to the stopped boiler 20 has occurred. And the process of the control apparatus 10 transfers to step ST26. On the other hand, when the detected value difference (A−B) is equal to or larger than the second predetermined value (NO), the process of the control device 10 returns. In step ST26, the control apparatus 10 performs the same process as the process for the backflow of steam in step ST14 of the first embodiment.

According to the boiler 20 which concerns on 2nd Embodiment mentioned above, the following effects are acquired, for example.
As described above, the control device 10 serving as the determination unit determines that the difference between the detected value of the boiler water electrical conductivity sensor 421 and the detected value of the first condensed water electrical conductivity sensor 422 is less than the second predetermined value. Then, it is determined that the back flow of the steam SM4 to the stopped boiler 20 has occurred. Therefore, by the control different from the first embodiment, the condensed water W5 staying in the upper header 23 can be reliably detected, and the determination accuracy of the steam backflow can be improved.

The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and can be implemented in various forms.
For example, in the first embodiment, the detection value of the first condensed water electrical conductivity sensor 422 is used for the determination of the steam backflow, but the present invention is not limited to this. For example, instead of the detection value of the first condensate water conductivity sensor 422, the detection value of the second condensate water conductivity sensor 423 may be used for determination of steam backflow. In this case, the steam backflow is determined by detecting the condensed water W5 staying in the steam separator 7.

  In addition, the configuration of the electrode unit included in the first condensed water electrical conductivity sensor 422 and the second condensed water electrical conductivity sensor 423 is not limited to the configuration of the electrode unit 430. If there is no problem in the inflow and outflow of the condensed water W5 to the electrode part, other configurations can be adopted.

2 Boiler group 7 Air-water separator 10 Control device (determination unit)
23 upper header 24 lower header 20 boiler 21 boiler body 22 water pipe 27 burner 95 steam check valve 421 boiler water electrical conductivity sensor 422 first condensed water electrical conductivity sensor (condensed water electrical conductivity sensor)
423 Second Condensate Water Conductivity Sensor (Condensate Water Conductivity Sensor)
L5 Steam delivery line W2 Boiler water W5 Condensate SM4 Back-flow steam (steam)

Claims (3)

A boiler constituting a boiler group composed of a plurality of boilers,
A boiler body having an upper header, a lower header, and a plurality of water pipes connected to the upper header and the lower header;
A burner that heats the inside of the boiler body by burning;
A steam separator connected to the upper header and the lower header;
A steam check valve provided in a steam delivery line connected to the steam separator;
A condensed water electrical conductivity sensor for detecting electrical conductivity of condensed water generated in a region between the plurality of water pipes and the steam check valve;
A boiler provided with a judgment part which judges the existence of the backflow of the steam to the boiler which has stopped among a plurality of boilers based on the detection value of the condensed water electrical conductivity sensor. The condensed water electrical conductivity sensor detects the electrical conductivity of condensed water staying in the upper header, or the electrical conductivity of condensed water staying in the steam separator,
The said determination part determines that the backflow of the vapor | steam to the boiler which has stopped has generate | occur | produced when the detected value of the said condensed water electrical conductivity sensor exceeds a 1st predetermined value. Boiler. A boiler water conductivity sensor for detecting boiler water electrical conductivity;
The condensed water electrical conductivity sensor detects electrical conductivity of condensed water staying in the upper header,
When the difference between the detected value of the boiler water electrical conductivity sensor and the detected value of the condensed water electrical conductivity sensor is less than a second predetermined value, the determination unit reversely flows steam to the stopped boiler. The boiler according to claim 1, wherein it is determined that the occurrence has occurred.

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