JP2005098540A - Boiler with washable economizer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a boiler capable of preventing a big fall of water level inside the boiler when washing an economizer and capable of sufficiently washing the economizer. <P>SOLUTION: The boiler has the economizer 7 for previously heating water to be supplied to the boiler 1, economizer washing devices 2, 11 and 12 for injecting the boiler water to a surface of the economizer, a water level detecting device 3 for detecting water level inside the boiler, and an operation control device 14 for controlling operation of the boiler. In the case of washing the economizer 7, when water level inside the boiler higher than the set water level is detected, injection of the boiler water to the surface of the economizer is started, and when water level inside the boiler less than the set level is detected, injection of the boiler water is stopped. The boiler water injection time is detected as the total washing time, and injection of the boiler water and interruption of injection are repeated till the total washing time reaches the set washing time, and when the total washing time reaches the set washing time, washing of the economizer is finished. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a boiler that cleans an economizer by spraying boiler water onto the economizer surface.

  It is widely practiced to improve boiler efficiency by providing an economizer that preheats water supplied to the boiler by the heat of combustion exhaust gas discharged from the boiler. Combustion exhaust gas contains soot, and if soot from the combustion exhaust gas adheres to the economizer surface that contacts the combustion exhaust gas, the deposited soot will cause a decrease in the heat exchange rate and corrosion, so the economizer surface must be cleaned periodically. It is necessary to remove the soot. For economizer cleaning, an economizer cleaning device consisting of an injection nozzle that injects canned water toward the economizer surface, a connecting pipe connecting the injection nozzle and the boiler can body, a cleaning valve provided in the middle of the connecting pipe, etc., is provided. The economizer is cleaned by spraying water onto the economizer surface. When boiler water is used as the cleaning water, if the cleaning water injection time is lengthened, a large amount of boiler water is used, so that the water level in the boiler decreases, the water level becomes abnormal and the boiler stops or the temperature of the can water drops. Steam generation may be reduced.

Therefore, in Japanese Patent No. 3397292, a cleaning time and a stop time are set, and a large amount of boiler water is prevented from being used at once by repeating the cleaning for the cleaning time and the stop for the stop time. . However, even in this case, if the cleaning is started in a state where the boiler water level is low, the boiler water level becomes low. Further, if the cleaning time is shortened, the water level can be prevented from being lowered, but there is a problem that the cleaning becomes insufficient.
Japanese Patent No. 3397292

  The problem to be solved by the present invention is to prevent the water level in the boiler from being significantly lowered during the economizer cleaning and to sufficiently clean the economizer.

  The invention described in claim 1 is an economizer for preheating water supplied to a boiler, an economizer cleaning device for injecting boiler water onto the economizer surface, a water level detection device for detecting the water level in the boiler, and an operation control device for controlling the operation of the boiler. When cleaning the economizer, the operation control unit detects that the water level in the boiler has exceeded the set water level, starts the boiler water injection to the economizer surface, and sets the water level in the boiler Control is performed to stop the boiler water injection by detecting that the water level is below the level, and the boiler water injection time is detected as the integrated cleaning time, and the integrated cleaning time is set to the preset cleaning time. The boiler water injection and injection interruption are repeated until the accumulated cleaning time reaches the set cleaning time, and the economizer cleaning is terminated. And wherein the door.

  The invention described in claim 2 is an economizer for preheating water supplied to the boiler, an economizer cleaning device for injecting boiler water onto the economizer surface, a water level detection device for detecting the water level in the boiler, and a pressure detection device for detecting the pressure in the boiler. If the boiler has an operation control device that controls the operation of the boiler, and the economizer is cleaned, the operation control device detects that the water level in the boiler has exceeded the set water level and the boiler water on the economizer surface Starts injection, detects that the water level in the boiler has become less than the set water level, and performs control to interrupt the boiler water injection, and cumulatively cleans the boiler water injection amount from the boiler water injection time and the boiler internal pressure at that time It is detected as the amount of water, and boiler water injection and injection interruption are performed until the integrated value of the integrated cleaning water amount reaches the preset cleaning water amount. Ri returns, the integrated value of the integrated amount of wash water to and performs control to end the cleaning of the economizer reaches the set amount of wash water.

  By implementing the present invention, the boiler water injection starts only when the water level in the boiler is higher than the set water level, and the boiler water injection is stopped when the boiler water level becomes lower than the set water level. Sometimes, the water level in the boiler can be prevented from significantly decreasing. Moreover, it is possible to prevent the economizer from being insufficiently cleaned due to the injection of boiler water more than necessary or the lack of boiler water injection amount.

  FIG. 1 is a schematic diagram of a boiler embodying the present invention, FIG. 2 is an explanatory diagram of the operation status of a cleaning valve in one embodiment, and FIGS. . The boiler 1 supplies water preheated by the economizer 7 from the lower part, heats the inside, and takes out steam from the upper part. A water supply pipe 8 is provided at the lower part of the boiler 1, and a steam outlet pipe 5 is provided at the upper part. An exhaust pipe 6 is connected to the boiler 1, and the combustion exhaust gas after heating the boiler is discharged through the exhaust pipe 6. The exhaust pipe 6 is provided with an economizer 7, and water supplied to the boiler 1 is pressurized by a water supply pump 4 and supplied into the boiler 1 through the economizer 7. In order to detect the water level in the boiler, a water level detection device 3 connected to the upper and lower parts in the boiler is provided. The water level detection device 3 detects a high water level electrode rod 9 for detecting a high water level, and detects a low water level. A low electrode rod 10 is provided. The lower end height of the high electrode rod 9 is set to the water level H, and the lower end height of the low electrode rod 10 is set to the water level L. If each electrode rod is in contact with water, a signal with water is output, and if it is not in contact with water. The water level is detected by outputting a signal indicating no water.

  Further, an operation control device 14 having a timer device 15 therein and a pressure detection device 13 for detecting the pressure in the boiler are provided, and the boiler water level detected by the water level detection device 3 and the pressure detection device 13 are detected. The information on the boiler internal pressure is transmitted to the operation control device 14. The operation control device 14 controls the operation of the water supply pump 4 based on the water level detected by the water level detection device 3. When the low electrode rod 10 detects no water due to a decrease in the water level in the boiler, the operation control device 14 is below the water level L. The operation of the feed water pump 4 is started, and when the water level in the boiler rises by the operation of the feed water pump 4 and the high electrode rod 9 detects the presence of water, it is determined that the water level is equal to or higher than the water level H. The operation of the feed water pump 4 is stopped.

  When the combustion exhaust gas is sent to the economizer 7, soot contained in the combustion exhaust gas adheres to the surface of the economizer 7, so the economizer 7 needs to be periodically cleaned. Above the economizer 7 in the exhaust cylinder 6, there is provided an injection nozzle 11 for injecting cleaning water onto the surface of the economizer, and this injection nozzle 11 is connected to a can water section at the bottom of the boiler by a connecting pipe 12. A cleaning valve 2 is provided in the middle of the communication pipe 12, and when the cleaning valve 2 is opened, boiler water is jetted from the jet nozzle 11. The injection nozzle 11, the communication pipe 12, and the cleaning valve 2 serve as an economizer cleaning device, and the operation control device 14 controls the opening and closing of the cleaning valve 2.

  The operation control device 14 measures the operation time of the boiler 1, and when the operation time from the previous economizer cleaning reaches the set time, it determines that it is the economizer cleaning time, and starts the economizer cleaning process. The operation control device 14 does not open the cleaning valve 2 only when the cleaning time is reached, but opens the cleaning valve 2 after detecting that the water level detected by the water level detection device 3 is higher than the water level H. Set to. When the water level becomes higher than the water level H by the operation of the water supply pump 4, the high electrode rod 9 detects the presence of water, and the operation control device 14 receives the water presence signal from the high electrode rod 9 and opens the cleaning valve 2. Control to open. When the cleaning valve 2 is opened, boiler water is injected from the injection nozzle 11 to the economizer 7. When the boiler water level is lowered by injecting boiler water from the injection nozzle 11 and the water level becomes lower than the water level L, the low electrode rod 10 detects the absence of water, and the operation control device 14 detects the low electrode rod 10. In response to the signal indicating no water, the control for closing the cleaning valve 2 is performed.

  The end of the economizer cleaning will be described with reference to FIG. 2 which is an embodiment in the case where the end of the economizer cleaning is determined based on the boiler water injection time. FIG. 2 shows a state before the economizer cleaning time and starts from a state where the water supply pump 4 is operating. When the water supply pump 4 is operated, the water level rises. When the water level rises to the water level H, the operation of the water supply pump 4 is stopped (a). When the operation time from the previous economizer cleaning measured by the operation control device 14 reaches the set value, the operation control device 14 determines that the economizer cleaning time has come, and starts the economizer cleaning process. However, since the cleaning valve 2 is actually opened and the boiler water is injected into the economizer 7 when it is detected that the water level has risen to the water level H, the boiler water is not immediately injected. Is in a standby state (b). Thereafter, when the water level drops to the water level L, the operation control device 14 starts the water supply by starting the operation of the water supply pump 4 (c).

  When the water level rises to the water level H by the operation of the water supply pump 4, the operation control device 14 stops the operation of the water supply pump 4, opens the cleaning valve 2 and injects boiler water from the injection nozzle 11 to clean the economizer 7. At the same time, the opening time of the cleaning valve 2 is measured by the timer device 15 (d). When the boiler water is injected into the economizer 7, the water level in the boiler decreases. When the water level decreases to the water level L, the operation control device 14 closes the cleaning valve 2 to stop the boiler water injection, and the economizer 7 Is stopped, and the water supply pump 4 is operated to start water supply to the boiler (e). At this time, the operation control device 14 calculates t1 (for example, 15 seconds), which is the time during which the cleaning valve 2 is opened, as the integrated cleaning time, and sets the integrated cleaning time in advance (for example, 40). In seconds). If the integrated cleaning time (15 seconds) is longer than the set cleaning time (40 seconds), the cleaning process of the economizer 7 is terminated. However, since the integrated cleaning time is shorter than the set cleaning time, the boiler water is simply stopped. The process continues.

  When the water level rises to the water level H due to the water supply, the operation control device 14 performs the control to stop the water supply pump 4 and the control to open the cleaning valve 2, start the second boiler water injection, and measure the opening time of the cleaning valve 2. (F). Also in this case, when the water level subsequently drops to the water level L, the operation control device 14 performs control for closing the cleaning valve 2 and control for operating the feed water pump 4 to stop the second boiler water injection and interrupt the cleaning ( g). In addition, the operation control device 14 calculates the total cleaning time (30 seconds) by adding the second cleaning valve opening time t2 (for example, 15 seconds) to the previously calculated first cleaning time. The calculated total cleaning time (30 seconds) is compared with the set cleaning time (40 seconds). If the accumulated cleaning time t1 + t2 is larger than the set cleaning time, the cleaning process of the economizer 7 is terminated. However, since the accumulated cleaning time is shorter than the set cleaning time, the cleaning process is continued.

  Similarly, when the water level rises to the water level H by the water supply, the operation control device 14 performs the control to stop the water supply pump 4 and the control to open the cleaning valve 2 to start the third boiler water injection (h). If it falls to L, the control which closes the washing valve 2 and the control which operates the feed water pump 4 will be performed, and the 3rd boiler water injection will be stopped (i). In addition, the operation control device 14 compares the accumulated cleaning time (45 seconds) obtained by adding the previous cleaning time and the third cleaning valve opening time t3 (eg, 15 seconds) with the set cleaning time (40 seconds). If the accumulated cleaning time is longer than the set cleaning time, the cleaning process of the economizer 7 is terminated.

  Next, the end of the economizer cleaning will be described with reference to FIGS. 3 and 4 which are examples in the case where the end of the economizer cleaning is determined based on the boiler water injection amount. FIG. 3 shows an example when the pressure inside the boiler is low (example: 0.5 MPa), and FIG. 4 shows an example when the pressure inside the boiler is high (example: 0.8 MPa). In FIG. 3, the state is the state before the economizer cleaning time, and the state is started from the state in which the water supply pump 4 is operating. When the water supply pump 4 is operated, the water level rises. When the water level rises to the water level H, the operation of the water supply pump 4 is stopped (A). When the operation time from the previous economizer cleaning measured by the operation control device 14 reaches the set value, the operation control device 14 determines that the economizer cleaning time has come, and starts the economizer cleaning process. However, the cleaning valve 2 is actually opened to start cleaning the economizer 7 when it is detected that the water level has risen to the water level H, so that the boiler water is not injected immediately, The injection is kept on standby (B). Thereafter, when the water level drops to the water level L, the operation control device 14 starts water supply by starting the operation of the water supply pump 4 (C).

  When the water level rises to the water level H by the operation of the water supply pump 4, the operation control device 14 stops the operation of the water supply pump 4, opens the cleaning valve 2 and injects boiler water from the injection nozzle 11 to clean the economizer 7. At the same time, the opening time of the cleaning valve 2 is measured by the timer device 15 (D). When the boiler water is injected into the economizer 7, the water level in the boiler decreases. When the water level decreases to the water level L, the operation control device 14 closes the cleaning valve 2 to stop the boiler water injection, and the economizer 7 Is stopped, and the water supply pump 4 is operated to start water supply to the boiler (E). At this time, the operation control device 14 calculates an accumulated cleaning water amount (for example, 5.9 kg) from t4 (for example, 15 seconds), which is the time during which the cleaning valve 2 is open, and the boiler internal pressure (0.5 MPa) at that time. . The calculated integrated cleaning water amount (5.9 kg) is compared with a preset cleaning water amount (eg, 13.0 kg). If the integrated cleaning water amount is larger than the set cleaning water amount, the cleaning process of the economizer 7 is completed. Since the integrated cleaning water amount is smaller than the set cleaning water amount, the cleaning process is continued only by interrupting the injection of boiler water.

  When the water level rises to the water level H due to the water supply, the operation control device 14 performs the control to stop the water supply pump 4 and the control to open the cleaning valve 2, start the second boiler water injection, and measure the opening time of the cleaning valve 2. (F) Also in this case, when the water level drops to the water level L, the operation control device 14 performs control to close the cleaning valve 2 and control to operate the feed water pump 4, and stops the second boiler water injection to interrupt cleaning (G). . Further, the operation control device 14 calculates the first accumulated washing water amount calculated from the second washing valve opening time t5 (for example, 15 seconds) and the boiler internal pressure (0.5 MPa) at that time. The integrated cleaning water amount (11.8 kg) is calculated by integrating the cleaning water amount (5.9 kg), and the calculated integrated cleaning water amount (11.8 kg) is compared with the set cleaning water amount (13.0 kg). If the accumulated washing water amount is larger than the set washing water amount, the cleaning process of the economizer 7 is terminated. However, since the accumulated washing water amount is smaller than the set washing water amount, the washing process is continued only by interrupting the boiler water injection.

  Similarly, when the water level rises to the water level H by water supply, the operation control device 14 performs control to stop the water supply pump 4 and control to open the cleaning valve 2 to start the third boiler water injection (H). When the water level drops to the water level L, control for closing the cleaning valve 2 and control for operating the feed water pump 4 are performed, and the third boiler water injection is stopped (I). In addition, the operation control device 14 adds the washing water amount (5.9 kg) calculated from the previous washing water amount (11.8 kg) to t6 (for example, 15 seconds) which is the third washing valve opening time and the boiler internal pressure at that time. ) To calculate the total amount of washing water (17.7 kg). The calculated integrated cleaning water amount is compared with the set cleaning water amount (13.0 kg), and if the integrated cleaning water amount is larger than the set cleaning water amount, the cleaning process of the economizer 7 is terminated.

  FIG. 4 also shows a state before the economizer cleaning time, and starts from a state where the water supply pump 4 is operating. When the water supply pump 4 is operated, the water level rises. When the water level rises to the water level H, the operation of the water supply pump 4 is stopped (J). When the operation time from the previous economizer cleaning measured by the operation control device 14 reaches the set value, the operation control device 14 determines that the economizer cleaning time has come, and starts the economizer cleaning process. However, since the cleaning valve 2 is actually opened and cleaning of the economizer 7 is started after the water level rises to the water level H, boiler water is not immediately injected (K). Thereafter, when the water level drops to the water level L, the operation control device 14 starts the water supply by starting the operation of the water supply pump 4 (L).

  When the water level rises to the water level H by the operation of the water supply pump 4, the operation control device 14 stops the operation of the water supply pump 4, opens the cleaning valve 2 and injects boiler water from the injection nozzle 11 to clean the economizer 7. At the same time, the opening time of the cleaning valve 2 is measured by the timer device 15 (M). When the boiler water is injected into the economizer 7, the water level in the boiler decreases. When the water level decreases to the water level L, the operation control device 14 closes the cleaning valve 2 to stop the injection of the boiler water, and the economizer 7 Is stopped and the water supply pump 4 is operated to start water supply to the boiler (N). At this time, the operation control device 14 calculates the accumulated amount of cleaning water (for example, 7.4 kg) from t7 (for example, 15 seconds), which is the time during which the cleaning valve 2 is open, and the boiler pressure (0.8 MPa) at that time. Compare the calculated integrated cleaning water amount (7.4 kg) with the set cleaning water amount (eg, 13.0 kg). If the integrated cleaning water amount is larger than the set cleaning water amount, the cleaning process of the economizer 7 is terminated. Since it is smaller than the amount of cleaning water, the cleaning process is continued only by interrupting the injection of boiler water.

  When the water level rises to the water level H due to the water supply, the operation control device 14 performs a control to stop the water supply pump 4 and a control to open the cleaning valve 2 to start the second boiler water injection (O). In this case as well, when the water level drops to the water level L, the operation control device 14 performs control to close the cleaning valve 2 and control to operate the feed water pump 4 to stop the second boiler water injection and interrupt cleaning (P). . In addition, the operation control device 14 calculates the first accumulated washing water amount from the second washing valve opening time t8 (for example, 15 seconds) and the boiler internal pressure (0.8 MPa) at that time. The accumulated washing water amount (14.8 kg) is calculated by integrating the washing water amount (7.4 kg). The calculated integrated cleaning water amount (14.8 kg) is compared with the set cleaning water amount (13.0 kg). When the integrated cleaning water amount becomes larger than the set cleaning water amount, the end of the cleaning process of the economizer 7 is determined.

  When the boiler water is injected from the injection nozzle 11, the boiler water injection amount decreases when the boiler internal pressure is low, and the boiler water injection amount increases when the boiler internal pressure is high. Therefore, in the case of FIG. 3 where the boiler internal pressure is low and the boiler water injection amount is small, the accumulated cleaning water amount does not reach the set cleaning water amount unless the boiler water injection is performed for three cycles, but the boiler internal pressure is high. In the case of FIG. 4 where the amount of boiler water injection per unit is large, the cumulative amount of cleaning water reaches the set amount of cleaning water by performing two cycles of boiler water injection. In this way, by changing the number of boiler water injections corresponding to the boiler water injection amount that changes according to the boiler internal pressure, it is possible to prevent the amount of boiler water used for economizer cleaning from becoming too large, and cleaning is insufficient. Can be prevented.

Outline diagram of boiler implementing the present invention Explanatory drawing of the operation status of the cleaning valve in one embodiment of the present invention Explanatory drawing of the operation status of the cleaning valve in another embodiment of the present invention Explanatory drawing of the operation status of the cleaning valve in another embodiment of the present invention

Explanation of symbols

1 boiler
2 Cleaning valve
3 Water level detector
4 Water supply pump
5 Steam extraction pipe
6 Exhaust pipe
7 Economizer 8 Water supply pipe 9 High electrode rod 10 Low electrode rod 11 Injection nozzle
12 communication pipe 13 pressure detection device 14 operation control device 15 timer device

Claims (2)

An economizer having an economizer for preheating water supplied to a boiler, an economizer cleaning device for injecting boiler water onto the economizer surface, a water level detection device for detecting the water level in the boiler, and an operation control device for controlling the operation of the boiler. When cleaning the boiler, the operation control unit detects that the boiler water level has exceeded the set water level, starts jetting boiler water onto the economizer surface, and detects that the boiler water level has fallen below the set water level. The boiler water injection is controlled to be interrupted, and the boiler water injection time is detected as the accumulated cleaning time, and the boiler water injection and injection are interrupted until the accumulated cleaning time reaches the preset cleaning time. The economizer is characterized in that the economizer cleaning is controlled when the accumulated cleaning time reaches the set cleaning time. Boiler to carry out the cleaning of The. An economizer that preheats water supplied to the boiler, an economizer cleaning device that injects boiler water onto the economizer surface, a water level detection device that detects the water level in the boiler, a pressure detection device that detects the pressure in the boiler, and an operation control that controls the operation of the boiler When the economizer is cleaned with a boiler equipped with a device, the operation control device detects that the water level in the boiler has exceeded the set water level, starts jetting boiler water onto the economizer surface, and the water level in the boiler is Control that interrupts boiler water injection by detecting that the water level is lower than the set water level, and also detects the boiler water injection amount as the cumulative cleaning water amount from the boiler water injection time and the boiler internal pressure at that time, Boiler water injection and injection interruption are repeated until the water volume reaches the preset cleaning water volume. Boiler to clean the economizer, characterized in that upon reaching the amount performs control to end the cleaning of the economizer.

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