JP2014234978A - Boiler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect a backflow of steam caused by leakage of a check valve in a boiler for leading out steam into a steam passage including the check valve.SOLUTION: A boiler includes: a can body 2 for leading out steam into a steam passage 7 including a check valve 8; a burner 3 for heating water in the can body 2; a water level sensor 13 for detecting a water level in the can body 2; and a pressure sensor 14 for detecting pressure in the can body 2. In a state where combustion of the burner 3 is stopped and water supply by a water pump 5 is stopped, on the basis of each of detection signals of the pressure sensor 14 and the water level sensor 13, a backflow of the steam caused by leakage of the check valve 8 is detected. Specifically, when there is a rise equal to or more than a setting in the detection water level by the water level sensor 13 after the stop of a drop of the detection pressure by the pressure sensor 14 for a preset period of time, in a state where the combustion of the burner 3 is stopped and the water supply by the water supply pump 5 is stopped, it is determined that there is a backflow.

Description

  The present invention relates to a boiler, and more particularly, to a steam boiler that guides steam to a steam path provided with a check valve.

  A check valve may be provided in the steam path from the boiler to prevent the backflow of steam. In particular, as disclosed in, for example, Patent Document 1 below, in a boiler multi-can installation system provided with a plurality of boilers, steam from each boiler is sent to various steam-using facilities via the steam header. In order to prevent the reverse flow of steam from the boiler to each boiler, a check valve is provided in the steam path from each boiler to the steam header. This is because in the boiler multi-can installation system, the operating load of the steam is monitored based on the pressure of the steam header, and the number of operating boilers is changed, but the steam does not flow back to the stopped boiler.

JP 9-236208 A

  However, the check valve provided in the steam path may leak (malfunction), and steam may flow back to the boiler. When the steam flows back into the stopped boiler, the steam is condensed by heat radiation, and condensed water accumulates in the separator and the can body. Such a situation reduces the dryness of the steam at the next steaming. Further, since the condensed water of the back-flowed steam is almost pure water, the concentration of the boiler can water cannot be maintained properly, and the can body and the separator may be corroded.

  Therefore, the problem to be solved by the present invention is to detect the backflow of steam to the boiler due to leakage of the check valve in the boiler that leads the steam to the steam path provided with the check valve.

  The present invention has been made to solve the above-mentioned problems, and the invention according to claim 1 is directed to supply water from a water supply path having a water supply pump to lead steam to a steam path having a check valve. A can body, a burner or an electric heater for heating water in the can body, a water level sensor for detecting the water level in the can body, a pressure sensor for detecting the pressure in the can body, and heating by the burner or the electric heater Is stopped and water supply by the water supply pump is stopped, and based on the detection signals of the pressure sensor and the water level sensor, the back flow of steam from the steam path to the can body due to leakage of the check valve is detected. It is a boiler provided with the detection means to do.

  According to the first aspect of the present invention, in the state where the heating by the burner or the electric heater is stopped and the water supply by the water supply pump is stopped, the steam due to the leakage of the check valve is detected based on the detection signals of the pressure sensor and the water level sensor. Can be detected.

  Further, in the invention according to claim 2, the detection means is configured such that when the heating by the burner or the electric heater is stopped and the water supply by the water supply pump is stopped, the decrease in the detection pressure by the pressure sensor is not set time. 2. The boiler according to claim 1, wherein when the detected water level of the water level sensor is higher than a set level, the backflow is detected. 3.

  According to the second aspect of the present invention, in a state where the heating by the burner or the electric heater is stopped and the water supply by the water supply pump is stopped, first, it waits for the decrease in the detected pressure by the pressure sensor, and then the water level When the detection water level of the sensor is higher than the set value, it is detected that there is a backflow of steam due to the leakage of the check valve. This makes it possible to detect the rise of the water level more accurately by detecting the rise of the water level due to the condensation of the backflow steam due to the leakage of the check valve, not the rise of the water level due to the condensation of the residual steam between the can body and the check valve. It is possible to detect the reverse flow of steam.

  ADVANTAGE OF THE INVENTION According to this invention, the reverse flow of the vapor | steam to the boiler by the leak of a non-return valve is detectable in the boiler which guide | induces a vapor | steam to the steam path provided with the non-return valve.

It is the schematic which shows the use condition of one Example of the boiler of this invention.

Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic view showing a use state of an embodiment of a boiler 1 of the present invention.

  The boiler 1 of this embodiment is a multi-tube type once-through boiler, and includes a can body 2 in which an upper header and a lower header are connected by a large number of water tubes. The can body 2 may be a rectangular parallelepiped square can body, but in the present embodiment, the can body 2 is a vertical cylindrical round can body. In this case, the burner 3 is provided in the upper center of the can body 2 downward. Moreover, the circumference | surroundings of the can body 2 are covered with a heat insulating material and a can body cover.

  Water (soft water) is supplied to the can body 2 through the water supply channel 4. A water supply pump 5 is provided in the water supply path 4. By controlling the water supply pump 5, the water level in the can body 2 is maintained as desired.

  The water in the can 2 is heated and vaporized by the combustion of fuel by the burner 3. The steam is separated through the steam 6 in the separator 6 and then led out through the steam path 7. A check valve 8 is provided in the steam path 7 to prevent the backflow of steam to the can body 2. The combustion gas from the burner 3 is discharged to the outside as exhaust gas after heat exchange with water in the can 2.

  More specifically, in the illustrated example, the steam from the can body 2 is supplied to the steam header 9 via the steam path 7 after the dryness is improved in the separator 6. The steam header 9 is also connected with a steam path 10 from another boiler (this steam path also includes a check valve) and a steam path 11 to the steam using facility. And the boiler 1 of a present Example comprises a boiler multi-can installation system with one or several other boilers. At that time, the other boilers can be configured in the same manner as the boiler 1 of the present embodiment described here.

  The steam header 9 is provided with a steam pressure sensor 12. The steam pressure sensor 12 monitors the steam use load in the steam use facility, and the number of boilers 1 operated according to the increase or decrease of the steam load, depending on the demand. The combustion amount of each boiler 1 is adjusted. When the combustion of the boiler 1 is stopped in relation to the steam load, steam may flow backward from the steam header 9 to the stopped boiler 1, so that the steam path 7 from the boiler 1 to the steam header 9 As described above, the check valve 8 is provided.

  The boiler 1 is further provided with a water level sensor 13 for detecting the water level in the can body 2. The configuration of the water level sensor 13 is not particularly limited, but a water level sensor that can obtain a continuous output according to the water level is preferably used. For example, a capacitance type or differential pressure type water level sensor is used.

  The boiler 1 is further provided with a pressure sensor 14 that detects the pressure in the can 2. Although the pressure sensor 14 may be provided on the can body 2, in the illustrated example, the pressure sensor 14 is provided on a connection pipe between the water level detection cylinder of the water level sensor 13 and the lower header.

  The boiler 1 is controlled by a controller (not shown). This controller supplies water into the can body 2 by the feed water pump 5 and combustion by the burner 3 (for fuel and combustion) based on detection signals from the vapor pressure sensor 12, the water level sensor 13 and the pressure sensor 14 and the elapsed time. Air supply). The controller also functions as detection means for detecting the backflow of steam from the steam header 9 to the can body 2 due to leakage of the check valve 8.

  That is, the controller controls the water supply pump 5 based on the detection signal of the water level sensor 13 to control the water supply into the can body 2 so as to maintain the water level in the can body 2 as desired. Further, the controller adjusts the amount of combustion in the burner 3 based on the detection signal of the vapor pressure sensor 12 and, if desired, the amount of combustion. Further, the controller moves to the can body 2 due to leakage of the check valve 8 based on the detection signals of the pressure sensor 14 and the water level sensor 13 in a state where combustion by the burner 3 is stopped and water supply by the water supply pump 5 is stopped. Detects the backflow of steam.

  More specifically, the controller monitors the pressure detected by the pressure sensor 14 in a state where combustion of the burner 3 is stopped and water supply by the water supply pump 5 is stopped. When the boiler 1 is stopped (that is, the combustion of the burner 3 is stopped), the steam accumulated in the pipe (from the can body 2 to the check valve 8) is gradually condensed, the pressure detected by the pressure sensor 14 decreases, and the water level The detection water level of the sensor 13 rises. Therefore, the process waits until the detected pressure of the pressure sensor 14 decreases for a set time. At this time, it may wait for the pressure to drop to the set pressure, or may wait for the pressure drop at the set speed or more to disappear.

  Thereafter, the controller monitors the water level detected by the water level sensor 13. If a leak occurs in the check valve 8 and there is a backflow of steam to the can body 2, the steam condenses in the can body 2 of the boiler 1 that is stopped, and the water level in the can body 2 It will rise gradually. Therefore, when there is an increase in the detected water level of the water level sensor 13 or more, it is detected that there is a backflow, and that is notified to the user. For example, the controller notifies by an alarm in the boiler 1 or the number controller (a personal computer connected to each boiler 1).

  According to the boiler 1 of the present embodiment, leakage of the check valve 8 can be automatically detected, and an indication of replacement of the check valve 8 can be shown. When leakage of the check valve 8 is detected, the user may maintain the check valve 8 as desired. Thereby, the fall of the dryness of a vapor | steam can be prevented, and corrosion of the can 2 and the separator 6 by reducing the concentration of can water too much can be prevented. Furthermore, by automatically detecting and maintaining the leakage of the check valve 8 at an early stage, wasteful steam condensation is suppressed, leading to energy saving.

  In addition, when leakage of the check valve 8 is detected (especially after the state has continued for a predetermined time), the water in the can body 2 is replaced by blowing, or the amount of chemicals added to the water supply is increased to take anti-corrosion measures. You may make it perform.

  The boiler 1 of the present invention is not limited to the configuration of the above embodiment, and can be changed as appropriate. In particular, if the backflow of steam due to leakage of the check valve 8 is detected based on the detection signals of the pressure sensor 14 and the water level sensor 13 in a state where the combustion is stopped and the water supply is stopped, the other configurations are appropriate. Can be changed.

  For example, in the above-described embodiment, the boiler 1 is installed in multiple cans, but may be used as a single can. Moreover, in the said Example, although the boiler 1 was controlled based on the pressure (detected pressure of the steam pressure sensor 12) in the steam header 9, the pressure in the can 2 (detected pressure of the pressure sensor 14) depending on the case. May be controlled based on

  Furthermore, although the said Example demonstrated the example applied to the fuel-fired boiler which burns a fuel in the burner 3, it is applicable similarly to the electric boiler using an electric heater.

DESCRIPTION OF SYMBOLS 1 Boiler 2 Can body 3 Burner 4 Water supply path 5 Water supply pump 6 Separator 7 Steam path 8 Check valve 9 Steam header 10 Steam path (from other boilers) 11 Steam path (to steam use equipment) 12 Steam pressure sensor 13 Water level sensor 14 Pressure sensor

Claims (2)

A can body that is supplied with water from a water supply channel provided with a water supply pump and leads steam to a steam channel provided with a check valve;
A burner or an electric heater for heating the water in the can,
A water level sensor for detecting the water level in the can body;
A pressure sensor for detecting the pressure in the can;
In the state where heating by the burner or the electric heater is stopped and water supply by the water supply pump is stopped, the can body is removed from the steam path due to leakage of the check valve based on the detection signals of the pressure sensor and the water level sensor. And a detecting means for detecting a backflow of steam to the boiler. In the state where the heating by the burner or the electric heater is stopped and the water supply by the water supply pump is stopped, the detection means increases the detected water level of the water level sensor after the detection pressure of the pressure sensor has been reduced for a set time. 2. The boiler according to claim 1, wherein when there is more than a setting, it is detected that the backflow exists.

Images