JP4178100B2 - Steam supply method and steam supply system - Google Patents

Description

  The present invention relates to a steam supply method that effectively uses steam supplied to a soot blower path, and a steam supply system that realizes the steam supply method.

  In general, in a thermal power plant, water is evaporated by a boiler that burns coal powder, heavy oil, and the like to generate high-pressure steam, and the turbine is rotated by this steam to generate power. Thus, since coal etc. are used for the fuel of a boiler, soot adheres to the surface and wall surface of the tubular body arranged in the boiler in order to let water pass, and the heat transfer efficiency to the water in a tubular body falls. The problem occurs.

  Therefore, a rod-like device called a soot blower, which has a steam injection port on its peripheral surface, is inserted into the boiler, and is rotated around the axis while extending between the tubes and along the wall surface. Soot is washed off by injecting high-temperature steam supplied from the boiler onto the surface and wall surface of the boiler.

  The steam sprayed by the soot blower may cause cracks in the pipe body due to the low temperature, and therefore it is necessary to maintain a certain high temperature. Specifically, since the pipe for sending steam to the soot blower passes steam only when the soot blower is operated, it has been cooled for a while after the steam has started to pass. Therefore, in order to supply high-temperature steam to the soot blower, an operation of “warming up” is performed in which the steam is passed through the pipe line for a predetermined time (for example, 10 minutes) to warm it.

For this warming up, steam of 250 m ³ or more may be used in one day. The steam used for warming has a high temperature, high pressure, and high water quality similar to that of pure water used for steam generation in a boiler, and is generally collected and discharged into a blow tank.

  Steam generated in the boiler of a thermal power plant is converted into steam for heating air, high pressure steam (for example, 0.65 to 2.0 MPa), low pressure steam (for example, 0.65 MPa or less), etc. in addition to power generation and soot blower. It is also used for the following purposes.

  The air heating steam is sent to an air heater called a steam air heater, and heats the air supplied from the ventilator. The steam air heater heats the air and supplies it to the boiler by heat exchange between the air heating steam and the air.

  The high-pressure steam is used, for example, as turbine ground steam that prevents the steam from leaking from a fitting portion between the casing that covers the turbine and the turbine shaft, or as heavy oil injection steam for injecting fuel heavy oil into the boiler. The Turbine ground steam is fed into a fitting portion between the casing that covers the turbine and the turbine shaft, and the pressure prevents steam leakage from the inside of the casing.

  The low-pressure steam heats the ammonia used to neutralize nitrogen oxide (NOx) contained in the exhaust gas of the boiler, which is a device that fluidizes the heavy oil by heating the pipeline that sends the heavy oil to the boiler. Used in ammonia vaporizers for vaporization.

  Patent Document 1 listed below discloses an automatic soot blower control device that performs an appropriate soot blower operation and that can perform a stable operation of the boiler even after the operation.

Japanese Patent Laid-Open No. 06-347017

  The soot blower automatic control device determines the heat transfer surface on which the soot blower is to be operated, and operates the corresponding soot blower. Is collected in the drainage tank and discharged as water, and its energy is not utilized.

  An object of the present invention is to provide a steam supply method that effectively uses steam generated in a boiler and sent to a soot blower path, and a steam supply system that realizes the steam supply method.

The steam supply method of the present invention is for sending steam sent from a boiler to a device that uses high-pressure steam (for example, a device that injects heavy oil into the boiler), to a soot blower that cleans the inside of the boiler. The boiler is constantly supplied to the soot blower path during boiler operation, and the steam passing through this path is sent to a device that uses low-pressure steam (for example, steamless or ammonia vaporizer) and the steam pressure is being boiler operated. , Characterized by constant adjustment .

  In the steam supply method of the present invention, it is preferable that the pressure of the steam sent from the soot blower path to the apparatus using the low pressure steam is adjusted by a pressure regulating valve provided on the downstream side of the soot blower path.

Alternatively, it is preferable that the operation / non-operation of each soot blower is switched by a valve provided in a path that branches from the soot blower path and reaches each of the plurality of soot blowers for cleaning the inside of the boiler. Moreover, it is preferable to send the vapor | steam produced | generated with the said boiler and passing through the said soot blower path | route to the condenser for supplying water to the said boiler .

A steam supply system of the present invention is a steam supply system for supplying steam generated in a boiler to another, a main path for supplying the steam from the boiler to a turbine, and a high pressure branched from the main path A high pressure path leading to an apparatus that uses steam, a soot blower path branched from the high pressure path so that steam sent from the boiler to the high pressure path is constantly supplied during boiler operation , and a soot blower path. The low-pressure path for sending the steam to the equipment using low-pressure steam and the pressure of the steam sent from the soot-blower path to the equipment using the low-pressure steam are constantly adjusted during boiler operation. And a pressure regulating valve .

  In the above-described system, a path that branches from the soot blower path and reaches each of the plurality of soot blowers for cleaning the inside of the boiler, and a valve that is provided in the path and switches operation / non-operation of each soot blower is provided. preferable.

Alternatively, in the steam supply system of the present invention, it is preferable to provide a path to send the steam which has passed through the soot blower for the route is generated in the boiler, the condenser for supplying water to the boiler. Moreover, it is preferable to provide a drain tank on the path | route which sends the said vapor | steam to a condenser .

According to the steam supply method of the present invention, steam that is sent from a boiler to a device that uses high-pressure steam is constantly supplied to a soot blower path for sending high-temperature steam to a soot blower that cleans the inside of the boiler during boiler operation. This eliminates the need for the work or operation of warming up the soot blower path when the soot blower is activated. Further, by adjusting the steam passing through the soot blower path to a predetermined pressure and sending it to a device that uses low-pressure steam, the steam can be effectively used without waste without being drained.

In the steam supply method of the present invention, the pressure of the steam sent from the soot blower path to the low-pressure steam using device can be adjusted by the pressure regulating valve provided on the downstream side of the soot blower path. Alternatively , by providing a valve in the path leading to each of a plurality of soot blowers that branch off from the soot blower path and clean the inside of the boiler, each soot blower can be switched on / off, thereby allowing the soot blower to be activated to operate. Correspondingly, an appropriate valve can be opened. Further, the steam generated by the boiler and passed through the soot blower path can be reused by sending it to a condenser for supplying water to the boiler.

According to the steam supply system of the present invention, the steam sent from the boiler to the device using high-pressure steam is always supplied during the boiler operation, and the soot blower path that is constantly supplied to the device using the low-pressure steam. By providing a low pressure path to be sent, and a pressure regulating valve that is provided downstream of the soot blower path and constantly adjusts the pressure of the steam sent from the soot blower path to the device that uses the low pressure steam during boiler operation , The work or operation of warming up the soot blower path when starting the soot blower is not necessary. Further, it is possible to adjust the vapor passing through the soot blower for paths to a predetermined pressure, it can be sent to the device using the low pressure steam, without waste effectively utilized without the drainage steam.

Further, the operation is performed by including a path that branches from the soot blower path and reaches each of the plurality of soot blowers for cleaning the inside of the boiler, and a valve that is provided in the path and switches between operation and non-operation of each soot blower. An appropriate valve can be opened corresponding to the soot blower. Further , the steam generated in the boiler and passed through the soot blower path can be reused by sending it to a condenser for supplying water to the boiler.

Further, by providing a path for sending the steam that has passed through the soot blower path to a condenser for supplying water to the boiler, the steam used for warming up the soot blower path is not drained when the soot blower is started, and this is recovered. It can be sent to water and reused for steam generation. In this case, a drain tank can be provided on the condensate path.

  FIG. 1 shows a steam supply system of a thermal power plant to which the steam supply method of the first embodiment of the present invention is applied.

This thermal power plant is a steam supply system for supplying steam generated in the boiler 1 to others.
A main path 3 for supplying steam generated in the boiler to the turbine 2;
A high-pressure path 4 branched from the main path 3 to a device that uses high-pressure steam (hereinafter referred to as a “high-pressure device”);
A soot blower path 6 branched from the high pressure path 4 to constantly supply steam;
A low pressure path 7 for sending the steam that has passed through the soot blower path 6 to a device that uses low pressure steam (hereinafter referred to as "low pressure device");
A warm air path 9 is provided that branches from the low pressure path 7 and reaches a steam air heater 8 that heats the air sent to the boiler 1.

  The steam used for power generation in the turbine 2 is sent to a condenser 10 that supplies water to the boiler 1, and is pumped by a pump 11 and resupplied to the boiler 1.

  In the high-pressure path 4, two valves 12 and 13 are installed as flow rate adjusting means upstream from the branch point to the soot blower path 6. Of these two valves, the upstream valve 12 is a main valve that switches inflow / shutoff of the steam sent from the main path 3, and the downstream valve 13 is a predetermined pressure (for example, the steam flowing through the high pressure path 4) , 2.0 MPa).

  In this thermal power plant, the pressure change in the high pressure device is detected, and the pressure of the steam supplied to the high pressure device through the high pressure path 4 is automatically adjusted. Specifically, when the pressure in the high-pressure device rises (for example, higher than the current set pressure of the pressure regulating valve 13 on the high-pressure path 4), the set pressure of the pressure regulating valve 13 on the high-pressure path 4 is decreased. On the other hand, when the pressure in the apparatus decreases, control is performed to increase the set pressure of the pressure regulating valve 13, and a predetermined pressure (for example, 2.0 MPa) state is maintained on average. Thereby, it is possible to constantly supply steam having a stable pressure to the high-pressure device.

  The high pressure device is, for example, a device that prevents leakage of steam from a fitting portion between a casing that covers the turbine 2 and the turbine shaft, a heavy oil injection device that injects fuel heavy oil into the boiler 1, and the like.

  The soot blower path 6 is also provided with two valves 15 and 16 as flow rate adjusting means. Of these two valves, the upstream valve 15 is a main valve that switches inflow / shutoff of steam sent from the high-pressure path 4, and the downstream valve 16 is used when steam leaks from the main valve 15. This is a manual spare valve.

  Also, in this thermal power plant, a plurality of (for example, 4 to 40) soot blowers 20 for cleaning the inside of the boiler 1 are installed, and there are paths that branch from the soot blower path 6 to reach the soot blowers 20. ing. A valve 18 is provided on each path, and an appropriate valve 18 is opened corresponding to the soot blower to be operated.

  Two valves 21 and 22 are installed on the downstream side of the soot blower path 6 as flow rate adjusting means. Of these two valves, the upstream valve 21 is a manual valve for shutting off the supply of steam to the low pressure device during maintenance or the like, and the downstream valve 22 passes through the low pressure path 7. It is a pressure regulating valve that regulates the vapor sent to the low pressure device to a predetermined pressure (for example, 0.65 MPa).

  In the steam supply system of the first embodiment, the soot blower path 6 refers to the path to the pressure regulating valve 22, and the low pressure path 7 refers to the path from the pressure regulating valve 22 to the low pressure device.

  As a low-pressure device, for example, a device called steamless for heating a pipeline for sending fuel heavy oil to a boiler to fluidize heavy oil, or neutralizing nitrogen oxides (NOx) contained in boiler exhaust gas There is an ammonia vaporizer that vaporizes ammonia for heat. In the low pressure path 7, it is preferable to install a temperature control spray 23 as a temperature control means for lowering the temperature of the steam supplied to the low pressure device. As the pressure regulating valve 22 installed in the low pressure path 7, it is preferable to adopt a valve that matches the vapor pressure used in the low pressure device. This temperature control spray 23 detects the temperature of the steam passing through the low pressure path 7 and in the low pressure path 7 (for example, the inside of the pipe body) in order to bring this temperature close to (for example, lower) the predetermined temperature. It is a device that jets water.

  Further, also for the low-pressure device, as in the above-described high-pressure device, the pressure regulating valve 22 is controlled based on the change in the pressure in the device, and the pressure of the supplied steam is kept at an appropriate value.

The steam air heater 8 is a device that heats the air sent from the ventilator 25 using the heat of the steam supplied from the boiler 1. In the steam air heater 8, for exchanging heat between the air from the steam and aerator 25 boiler 1, the water is generated. After this water is collected in the drain tank 26 as drain water, it is sent to the condenser 10 and resupplied to the boiler 1. The air heated by the steam air heater 8 is further heated by the gas air heater 27 that performs heat exchange between the air and the exhaust gas of the boiler 1 and supplied to the boiler 1.

  The flow of steam in the steam supply system to which the steam supply method of the first embodiment is applied will be described.

  First, steam generated in the boiler 1 is supplied to the turbine 2 through the main path 3 and is also supplied to the high-pressure path 4 branched from the main path 3. The steam used for power generation in the turbine 2 is sent to the condenser 10 and supplied again to the boiler 1.

  The steam sent from the main path 3 to the high-pressure path 4 is supplied to the high-pressure device and also to the soot blower path 6 side. The steam that has passed through the soot blower path 6 is supplied to the low pressure device through the low pressure path 7, and is supplied to the steam air heater 8 through the warm air path 9 branched from the low pressure path 7, for combustion of the boiler 1. After being used to heat the air, the drain water generated thereby is sent to the condenser 10 via the drain tank 26.

  The steam supply system described above can be applied to existing facilities of a thermal power plant, or can be applied when a thermal power plant is newly established. Specifically, in the former case, the existing high-pressure path 4 and soot blower path 6 are used, and the existing equipment is modified by connecting the low-pressure path 7 for supplying steam to the low-pressure device to the soot blower path 6. In the latter case, it can be applied by newly laying these routes along with the establishment of a thermal power plant.

  Further, when the steam supply method and the steam supply system of the first embodiment are applied, steam is constantly supplied to the soot blower path 6, so that high-temperature and high-pressure steam always flows through the soot blower path 6. There is no need to warm up the soot blower path 6 during startup. Thereby, the steam produced | generated with the boiler 1 can be used effectively, without draining at all.

  Although the first embodiment of the present invention has been described above, the second embodiment of the present invention will be described below.

  FIG. 2 shows a steam supply system of a thermal power plant to which the steam supply method of the second embodiment is applied. The equipment of this thermal power plant and the applied steam supply system are basically the same as the steam supply system of the first embodiment. The difference from the steam supply system of the first embodiment (FIG. 1) is that a backup path 30 is provided that branches from the high-pressure path 4 and reaches a device that uses low-pressure steam. Specifically, the path branched from the high pressure path 4 is connected to the low pressure path 7 so as to reach the low pressure device via the temperature control spray 23.

  The preliminary path 30 is provided with a pressure adjusting valve 32 that adjusts the pressure of the steam sent to the low pressure device to a predetermined pressure (for example, 0.63 MPa) as a flow rate adjusting means.

  The steam flow in this thermal power plant is basically the same as in the first embodiment, but the difference from the first embodiment is that the standby path 30 is branched from the high pressure path 4 and reaches the low pressure device. However, steam is supplied to the low-pressure apparatus as a backup path for the soot blower path 6 and the low-pressure path 7.

  Specifically, for example, when steam is not supplied or cannot be supplied to the soot blower path 6 such as during maintenance or failure of the soot blower 20 or the low pressure path 7, by closing the main valve 15 of the soot blower path 6, The flow of steam to the soot blower path 6 is blocked. In this case, the steam used in the low-pressure apparatus is secured only by the steam supplied through the preliminary path 30.

  Further, the set pressure (for example, 0.63 MPa) of the pressure regulating valve 32 installed on the preliminary path 30 of the second embodiment is set to the set pressure of the pressure regulating valve 22 installed between the soot blower path 6 and the low pressure path 7. (For example, 0.65 MPa), when the low pressure device requires 0.65 MPa steam, the pressure regulating valve 32 on the preliminary path 30 is shut off, and the soot blower path 6 and the low pressure path 7 is opened, and steam having a predetermined pressure (for example, 0.65 MPa) is supplied through the low pressure path 7.

  As described above, when the pressure regulating valve 32 on the auxiliary path 30 is shut off and only the steam from the low pressure path 7 side is supplied to the low pressure apparatus, for example, the steam pressure in the low pressure apparatus is the pressure regulating valve 22. When the pressure exceeds the set pressure, the pressure regulating valve 22 is closed (the pressure regulating valve 32 is closed at this time), and the steam in the low pressure device is consumed, so that the pressure in the low pressure device gradually decreases. . When the pressure in the low pressure device drops to the set pressure of the pressure adjustment valve 22, the pressure adjustment valve 22 is opened again to perform pressure control.

  Further, when the pressure regulating valve 32 on the preliminary path 30 is closed, when the soot blower path 6 is damaged, the steam leaks due to the damage or the like, and the soot blower path 6 Vapor pressure may decrease. In this case, the steam pressure in the soot blower path 6 is lowered, so that the steam pressure in the low pressure device to which steam is supplied is also lowered. At this time, the pressure regulating valve 22 operates in the opening direction to recover the pressure in the low pressure device. However, the steam passage amount of the pressure regulating valve 22 itself is reduced due to the damage of the soot blower path 6, and the low pressure device. Insufficient amount of steam to regain the pressure inside can not be supplied, and the pressure in the low pressure device continues to fall. In such a case, if the steam pressure in the low pressure device falls below the set pressure of the pressure regulating valve 32 installed in the preliminary path 30, the pressure regulating valve 32 opens and steam starts to be supplied from the preliminary path 30 side to the low pressure apparatus. The control is performed so as to recover (for example, increase) the pressure in the low-pressure apparatus. Thus, the pressure regulating valve 32 and the auxiliary path 30 can play a role of backing up the steam supply from the soot blower path 6 side. Further, when the steam flow in the soot blower path 6 is stopped for maintenance, the pressure regulating valve 32 and the backup path 30 can play a backup role similar to the above.

  Further, the steam supply to the steam air heater 8 can be received from the steam supply path 9 by connecting the warm air path 9 to the backup path 30 as shown by a broken line in the figure.

  Next, a third embodiment of the present invention will be described.

  FIG. 3 shows a steam supply system of a thermal power plant to which the steam supply method of the third embodiment is applied. The equipment of this thermal power plant is basically the same as the thermal power plant of the first embodiment. The difference from the steam supply system of the thermal power plant of the first embodiment is that the low-pressure path 35 for supplying steam to the low-pressure device is branched from the high-pressure path 4 and the steam passing through the soot blower path 6 is recovered. This is a point where a condensate passage 37 to be sent to the water bottle 10 is provided.

  The low pressure path 35 is provided with a pressure regulating valve 36 that regulates the vapor sent to the low pressure device to a predetermined pressure (for example, 0.65 MPa), and a temperature regulating spray 40 that regulates the temperature of the vapor. The condensate path 37 is provided with a motor-operated valve 38 that switches inflow / shut-off of steam flowing therethrough.

  The flow of steam in the steam supply system of this thermal power plant will be described.

  The steam generated in the boiler 1 is supplied to the turbine 2 through the main path 3 and is also supplied to the high-pressure path 4 branched from the main path 3. The steam used in the turbine 2 is sent to the condenser 10 and supplied again to the boiler 1.

  The steam sent from the main path 3 to the high-pressure path 4 is supplied to the high-pressure apparatus side and is also supplied to the low-pressure path 35 branched from the high-pressure path 4. The steam passing through the low-pressure path 35 is supplied to the low-pressure apparatus side, and flows in the order of the steam air heater 8, the drain tank 26, and the condenser 10 through the warm air path 9 branched from the low-pressure path 35. 1 is supplied again.

  The soot blower path 6 branched from the high pressure path 4 was configured to allow steam to pass when the soot blower 20 was started. Specifically, when starting the soot blower 20, when the main valve 15 of the soot blower path 6 is opened, the motor-operated valve 38 on the condensate path 37 corresponds to a predetermined time (for example, 10 minutes). Shut off after opening. Thus, after warming up the soot blower path 6 for a predetermined time (for example, 10 minutes), high-temperature steam is supplied to the soot blower 20, and when the operation of the soot blower 20 is finished, the main valve 15 on the soot blower path 6 is turned off. It closes again and the inflow of steam to the soot blower path 6 side is blocked.

  In the third embodiment, the steam used for warming up the soot blower path 6 is not drained as in the prior art, but is sent to the condenser 10, so that the steam that has passed through the soot blower path 6 can be used effectively. it can.

  Next, a fourth embodiment of the present invention will be described.

  FIG. 4 shows a steam supply system of a thermal power plant to which the steam supply method of the fourth embodiment is applied. The facilities and the steam supply system of this thermal power plant are basically the same as those of the thermal power plant in the third embodiment (FIG. 3). The difference from the third embodiment is that a drain tank 26 is provided on a condensate path 37 for sending steam that has passed through the soot blower path 6 to the condenser 10. Specifically, the drain tank 26 installed on the path from the steam air heater 8 to the condenser 10 may be diverted to reach the condenser 10 through this.

  Also in the fourth embodiment, the steam used for warming up the soot blower path 6 is not drained, but is recovered in the drain tank 26 and sent to the condenser 10 for effective use.

  As described above, the steam supply method and the steam supply system of the present invention have been described. However, in any of the steam supply systems of the second to fourth embodiments, as described in the first embodiment, the existing equipment is modified. The steam supply system of the present invention can be newly applied when constructing a thermal power plant.

  In the steam supply method and the steam supply system of the third and fourth embodiments, the steam that has passed through the soot blower path 6 is partially or entirely water, and is directly supplied to the condenser 10 or a drain tank. 26 can be supplied to the condenser 10 via.

The figure which shows the vapor | steam supply system comprised so that a vapor | steam might be always supplied to the path | route for soot blowers. The figure which shows the steam supply system provided with the backup path | route which backs up the path | route for soot blowers. The figure which shows the steam supply system comprised so that warming steam might be sent to a condenser. The figure which shows the steam supply system comprised so that warming steam might be sent to a condenser via a drain tank.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Boiler, 2 ... Turbine, 3 ... Main path, 4 ... High pressure path, 6 ... Soot blower path, 7, 35 ... Low pressure path, 8 ... Steam air heater, 9 ... Warm air path, 10 ... Condenser, 11 ... Pump , 12, 15 ... Main valve, 13, 22, 32, 36 ... Pressure regulating valve, 16 ... Preliminary valve, 18, 21 ... Valve, 20 ... Soot blower, 23, 40 ... Temperature control spray, 25 ... Aerator, 26 ... Drain tank, 27 ... Gas air heater, 30 ... Preliminary path, 37 ... Condensate path, 38 ... Motorized valve.

Claims (8)

  During operation of the boiler, steam sent from the boiler (1) to a device using high-pressure steam is sent to a soot blower path (6) for sending hot steam to the soot blower (20) for cleaning the inside of the boiler (1). A steam supply method characterized by constantly supplying and sending the steam that has passed through the path (6) to a device that uses low-pressure steam, and constantly adjusting the pressure of the steam during boiler operation.   2. The steam supply method according to claim 1, wherein the steam to be sent from the soot blower path (6) to the apparatus using the low pressure steam by the pressure regulating valve (22) provided on the downstream side of the soot blower path (6). A steam supply method characterized by adjusting a pressure.   The steam supply method according to claim 1 or 2, wherein a valve (18) is provided in a path that branches from the soot blower path (6) and reaches each of a plurality of soot blowers (20) for cleaning the inside of the boiler (1). ) To switch the operation / non-operation of each soot blower.   The steam supply method according to any one of claims 1 to 3, wherein steam generated in the boiler (1) and passed through the soot blower path (6) is supplied to the boiler (1). A steam supply method, characterized by being sent to a water vessel (10).   In a steam supply system for supplying steam generated in the boiler (1) to the other, a main path (3) for supplying the steam from the boiler (1) to the turbine (2), and the main path (3) A high-pressure path (4) that branches from the apparatus to the device that uses high-pressure steam, and the high-pressure path so that steam sent from the boiler (1) to the high-pressure path (4) is constantly supplied during boiler operation. The soot blower path (6) branched from (4), the low pressure path (7) for sending the steam that has passed through the soot blower path (6) to a device that uses low pressure steam, and the soot blower path (6). A steam provided on the downstream side and provided with a pressure regulating valve (22) that constantly adjusts the pressure of steam sent from the soot blower path (6) to the device using the low pressure steam during boiler operation. Supply system. 6. The steam supply system according to claim 5 , wherein a path branched from the soot blower path (6) to each of a plurality of soot blowers (20) for cleaning the inside of the boiler (1) is provided in the path. A steam supply system comprising a valve (18) for switching operation / non-operation of each soot blower. The steam supply system according to claim 5 or 6 , wherein the steam (10) for supplying steam generated in the boiler (1) and passing through the soot blower path (6) to the boiler (1). A steam supply system comprising a route (9, 37) for sending to The steam supply system according to claim 7 , wherein a drain tank (26) is provided on a path for sending the steam to the condenser (10).

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