JP2005042679A - Method and apparatus for protection of reheater of boiler - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and apparatus for protecting a reheater of a boiler which can certainly prevent the temperature of the reheater from increasing in excess of the tolerance range due to a decrease in amount of steam passing therethrough and which can improve the reliability of the whole installations. <P>SOLUTION: A reheat steam temperature detector 37 for detecting the reheat steam temperature 36 is provided on the upstream side of the connecting portion where a reheater spray line 31 is connected to a reheat steam line 30. The reheat steam temperature 36 detected by the reheat steam temperature detector 37 is input to a controller 29. When the reheat steam temperature 36 becomes higher than a set value, a control signal 28' which throttles a control valve 25 arranged in the middle of a line 24 for supplying air from outside of the system, is output from controller 29. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a boiler reheater protection method and apparatus.

  FIG. 3 shows an example of a boiler. In FIG. 3, 1 is a boiler body having a furnace 1a and a rear heat transfer section 1b, and 2 is a fuel such as pulverized coal injected into the furnace 1a of the boiler body 1. Burner, 3 is the primary superheater, 4 is the secondary superheater, 5 is the tertiary superheater, 6 is the final superheater, 7 is the primary reheater, 8 is the secondary reheater, and 9 is the economizer A combustion gas is generated by injecting fuel from the burner 2 into the furnace 1a of the boiler body 1 and burning it, and the generated combustion gas is circulated to produce a secondary superheater 4 and a tertiary superheater 5 , The final superheater 6, the secondary reheater 8, the primary superheater 3, the primary reheater 7 and the economizer 9 are heat exchanged, and the exhaust gas after the heat exchange is discharged to the exhaust gas duct 10 to the downstream side. After removing nitrogen oxides, sulfur oxides, etc. with the installed denitration and desulfurization equipment (not shown), and then to the atmosphere It is adapted to output.

  On the other hand, FIG. 4 represents an example of the above-described boiler feed water / steam system, and the boiler feed water is heated by the evaporator 11 formed on the furnace wall of the furnace 1a of the boiler body 1 where the fuel is burned, The steam separated from water and steam by the brackish water separator 13 through the nose part 12, and the steam separated from the water by the brackish water separator 13 passes through the ceiling of the boiler body 1 and the peripheral wall 14 of the rear heat transfer part, and is primarily heated. The superheater 3, the secondary superheater 4, the tertiary superheater 5 and the final superheater 6 are superheated and guided to the high-pressure turbine 15, and the high-pressure turbine 15 is driven to generate electric power, and the high-pressure turbine 15 is driven. The subsequent steam is guided to the primary reheater 7 and the secondary reheater 8, reheated by the primary reheater 7 and the secondary reheater 8, and then introduced into the intermediate / low pressure turbine 16. The medium / low pressure turbine 16 is driven to generate electric power, The steam after driving the pressure turbine 16 is guided to the condenser 17 and returned to the boiler feed water. The boiler feed water passes through the condensate demineralizer 18, the low-pressure feed water heater 19, and the deaerator 20. The feed pump 21 is pumped to the economizer 9 through the high-pressure feed water heater 22, heated by the economizer 9, fed to the evaporator 11, and circulated.

  By the way, in the case of the boiler as described above, the outside air supply line 24 is branched from the main steam line 23 on the outlet side of the final superheater 6 as a superheater, and a part of the steam is supplied outside the system such as a factory. There is something like that.

  A control valve 25 such as a pressure control valve or a flow rate control valve and a detector 26 such as a pressure detector or a flow rate detector are provided in the middle of the outside air supply line 24, and further detected by the detector 26. A controller 29 is provided for outputting a control signal 28 to the control valve 25 in accordance with the detected value 27 such as the steam pressure or steam flow.

  Further, a reheater spray line 31 is connected in the middle of the reheat steam line 30 between the primary reheater 7 and the secondary reheater 8 to cope with a transient temperature change of the reheat steam. ing.

  For example, as shown in FIG. 5, the controller 29 compares a detected value 27 such as a steam pressure or a steam flow detected by the detector 26 with a set value 32 and outputs a deviation 33 thereof. And a proportional-integral regulator 35 that outputs a control signal 28 for eliminating the deviation 33 by proportionally integrating the deviation 33 output from the subtractor 34 to the control valve 25. ing.

  In the boiler as described above, when a part of the steam is supplied to the outside of the system such as a factory, the steam pressure of the steam flowing through the outside air supply line 24 by the detector 26 such as a pressure detector or a flow rate detector or the like. A steam flow rate or the like is detected and input to the controller 29. The subtracter 34 of the controller 29 compares the detected value 27 such as the steam pressure or the steam flow detected by the detector 26 with the set value 32, and The deviation 33 is output to the proportional-plus-integral adjuster 35, and the proportional-plus-integral adjuster 35 performs the proportional-integral processing on the deviation 33 output from the subtractor 34 so that the control signal 28 for eliminating the deviation 33 is a pressure regulating valve or By outputting to the control valve 25 such as a flow rate control valve and adjusting the opening of the control valve 25, the pressure control or flow rate control of the steam supplied to the outside of the system is performed.

Patent Document 1 is an example of a boiler that supplies a part of steam to the outside of a system such as a factory.
Japanese Patent Laid-Open No. 10-325307

  However, in the boiler as shown in FIG. 3 to FIG. 5, normally, all of the steam excluding the portion extracted from the high-pressure turbine 15 flows to the primary reheater 7 and the secondary reheater 8. Since the heat transfer area of the reheater is determined, a part of the steam is sent from the outside air supply line 24 to the outside of the system such as a factory, and the primary reheater 7 and the secondary reheater. When the amount of steam passing through 8 is reduced, the reheat steam from the reheater spray line 31 connected in the middle of the reheat steam line 30 between the primary reheater 7 and the secondary reheater 8 is supplied to the reheat steam. Even if spraying is performed, there is a possibility that the temperature of the primary reheater 7 located on the upstream side of the reheater spray line 31 connection point of the reheat steam line 30 may rise beyond an allowable range. .

  In view of such circumstances, the present invention can reliably prevent the temperature of the reheater from rising beyond an allowable range as the amount of passing steam decreases, and can improve the reliability of the entire equipment. It is an object of the present invention to provide a boiler reheater protection method and apparatus.

The present invention is a boiler reheater protection method for sending a part of steam out of the system,
The present invention relates to a boiler reheater protection method characterized by detecting the reheat steam temperature and restricting the steam sent to the outside of the system when the reheat steam temperature exceeds a set value.

  The boiler reheater protection method can be applied to a method in which a part of the steam is sent out of the system from the outlet side of the superheater.

Further, the present invention is a boiler reheater protection device having an external air supply line for supplying a part of steam to the outside of the system,
A reheat steam temperature detector for detecting the reheat steam temperature;
And a controller for outputting a control signal for restricting a control valve provided in the middle of the external air supply line when the reheat steam temperature detected by the reheat steam temperature detector exceeds a set value. This is a boiler reheat protection device characterized by the following.

  The boiler reheater protection device can be applied to a system in which the outside air supply line is branched from the main steam line on the outlet side of the superheater.

  Furthermore, the boiler reheater protection device can be applied to a control valve that is a pressure control valve or a control valve that is a flow rate control valve.

  According to the above means, the following operation can be obtained.

  When the reheat steam temperature exceeds the set value, the control valve installed in the middle of the external air supply line is throttled, so the amount of steam sent from the external air supply line to the outside of the factory is reduced. Thus, the amount of steam passing through the reheater is secured by that amount, and the temperature of the reheater is prevented from rising beyond an allowable range, and the reheater can be protected.

  According to the boiler reheater protection method and apparatus of the present invention, it is possible to reliably prevent the temperature of the reheater from rising beyond an allowable range as the amount of passing steam decreases, An excellent effect of improving the reliability can be achieved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  1 and 2 are examples of embodiments for carrying out the present invention. In the figure, the same reference numerals as those in FIGS. 3 to 5 denote the same components, and the basic configuration is shown in FIGS. Although it is the same as the conventional one shown in FIG. 5, the feature of this example is that, as shown in FIGS. 1 and 2, the reheat steam line 30 is located upstream of the connection point of the reheater spray line 31. The reheat steam temperature detector 37 for detecting the reheat steam temperature 36 is provided, and the reheat steam temperature 36 detected by the reheat steam temperature detector 37 is input to the controller 29. Is set to output a control signal 28 ′ for restricting the control valve 25 provided in the middle of the outside air supply line 24 from the controller 29.

  In the case of this illustrated example, the controller 29 compares the detected value 27 such as the steam pressure or the steam flow detected by the detector 26 with the set value 32 and outputs a deviation 33 as shown in FIG. In addition to the subtractor 34 that performs the proportional integration processing on the deviation 33 output from the subtractor 34 and outputs the control signal 28 for eliminating the deviation 33, the reheat steam temperature The subheater 40 that compares the reheat steam temperature 36 detected by the detector 37 with the set value 38 and outputs a deviation 39 thereof, and the deviation 39 output from the subtractor 40 is subjected to proportional integration processing to produce the deviation 39. The lower one of the proportional integration controller 42 for outputting the control signal 41 for eliminating the control signal 28, the control signal 28 output from the proportional integration controller 35 and the control signal 41 output from the proportional integration controller 42. Select and control signal 2 Has provided comprising constituting a low selector 43 to be output to the control valve 25 as a '.

  Next, the operation of the illustrated example will be described.

  When a part of the steam is sent to the outside of the system such as a factory, the pressure or flow rate of the steam flowing through the outside air supply line 24 is detected by a detector 26 such as a pressure detector or a flow rate detector. Then, the detected value 27 such as the steam pressure or the steam flow rate detected by the detector 26 is compared with the set value 32 in the subtractor 34 of the controller 29, and the deviation 33 is adjusted by proportional integral adjustment. The deviation 33 output from the subtractor 34 is proportionally integrated in the proportional-integral regulator 35 and a control signal 28 for eliminating the deviation 33 is output. A reheat steam temperature 36 on the upstream side of the reheater spray line 31 connection point of the reheat steam line 30 is detected by the heat steam temperature detector 37 and input to the controller 29. 40, the reheat steam temperature 36 detected by the reheat steam temperature detector 37 is compared with the set value 38, and a deviation 39 thereof is output to the proportional-plus-integral controller 42. The deviation 39 output from 40 is subjected to proportional integration processing, and a control signal 41 for eliminating the deviation 39 is output. The control signal 28 output from the proportional integration controller 35 and the proportional integration controller 42 are output. The lower one of the control signals 41 is selected by the low selector 43, and is output as a control signal 28 'to a control valve 25 such as a pressure control valve or a flow control valve, and the opening of the control valve 25 is adjusted. Thus, the pressure control or flow rate control of the steam supplied to the outside of the system is performed.

  As a result, when the reheat steam temperature 36 becomes equal to or higher than the set value 38, the control signal 41 output from the proportional-plus-integral regulator 42 is selected by the low selector 43 and is provided in the middle of the external air supply line 24. Since the control valve 25 is throttled, the amount of steam sent from the outside air supply line 24 to the outside of the system such as the factory is reduced, and the amount of steam passing through the primary reheater 7 and the secondary reheater 8 correspondingly decreases. Therefore, it is avoided that the temperature of the primary reheater 7 and the secondary reheater 8 rises beyond the allowable range, and the primary reheater 7 and the secondary reheater 8 are protected. It becomes possible to do.

  Thus, it is possible to reliably prevent the temperature of the primary reheater 7 and the secondary reheater 8 from rising beyond the allowable range as the passing steam amount decreases, and to improve the reliability of the entire equipment. obtain.

  The boiler reheater protection method and apparatus according to the present invention are not limited to the illustrated examples described above, and various modifications can be made without departing from the scope of the present invention.

It is a schematic block diagram of an example of embodiment which implements this invention. It is a block diagram of a controller in an example of an embodiment which implements the present invention. It is a whole outline block diagram which shows an example of a common boiler. It is a schematic block diagram which shows an example of the feed water / steam system of the boiler shown by FIG. FIG. 5 is a block diagram of the controller shown in FIG. 4.

Explanation of symbols

1 Boiler body 6 Final superheater (superheater)
7 Primary reheater (reheater)
8 Secondary reheater (Reheater)
23 Main steam line 24 Out-system air supply line 25 Control valve 28 'Control signal 29 Controller 30 Reheat steam line 31 Reheater spray line 36 Reheat steam temperature 37 Reheat steam temperature detector 38 Set value 39 Deviation 40 Subtraction 41 Control signal 42 Proportional integral regulator 43 Low selector

Claims (6)

A boiler reheater protection method for sending a part of steam out of the system,
A boiler reheater protection method, characterized by detecting a reheat steam temperature and restricting steam to be sent out of the system when the reheat steam temperature is equal to or higher than a set value.   The boiler reheat protection method according to claim 1, wherein a part of the steam is sent out of the system from the outlet side of the superheater. A boiler reheat protection device having an external air supply line for supplying a part of steam to the outside of the system,
A reheat steam temperature detector for detecting the reheat steam temperature;
And a controller for outputting a control signal for restricting a control valve provided in the middle of the external air supply line when the reheat steam temperature detected by the reheat steam temperature detector exceeds a set value. Boiler reheater protection device.   The boiler reheater protection device according to claim 3, wherein the outside air supply line is branched from the main steam line on the outlet side of the superheater.   The boiler reheater protection device according to claim 3 or 4, wherein the control valve is a pressure control valve.   The boiler reheat protector according to claim 3 or 4, wherein the control valve is a flow control valve.

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