JP2011074901A - Operation stop method of coal burning boiler facility and operation stop device for the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an operation stop method of a coal burning boiler facility for reducing the consumption of fuel oil to stop operation, and to provide an operation stop device for the coal burning boiler facility. <P>SOLUTION: In the operation stop method of the coal burning boiler facility including a coal burning boiler 3 equipped with a coal burner 1 and a fuel oil burner 2, a steam turbine 5 for driving a generator 4, a steam line 6 for supplying the steam turbine 5 with the steam generated by the coal burning boiler 3 and a turbine bypass line 8 for flowing the steam from the steam line 6 to the boiler while detouring the steam turbine 5, the method reduces a coal supplying amount to the coal burning burner 1 as well as reducing a generation load from a generator output of the coal burning boiler 3 during a normal operation and further reduces the generation load from a normal operation minimum load without switching to burning of the fuel oil burner 2, escapes steam unnecessary for the generation load to the turbine bypass line 8 to parallel off the generator 4 in accordance with reduction of the generation load. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for stopping operation of a coal-fired boiler facility for disconnecting a generator and a device for stopping the operation.

  In general, coal-fired boiler equipment is not required for a coal-fired boiler with a coal burner and a fuel oil burner, a steam turbine for driving a generator, a steam line for supplying steam generated in the coal-fired boiler to the steam turbine, and unnecessary A turbine bypass line that bypasses the steam turbine and passes the steam from the steam line to a boiler or the like and a turbine bypass valve that is disposed in the middle of the turbine bypass line is provided. The coal burner is supplied with coal from a coal mill, and the fuel oil burner of a coal-fired boiler is supplied with fuel oil from a fuel oil supply source such as light oil. .

  When starting operation of a coal fired boiler facility, the inside of the furnace is preheated by a fuel oil burner, the coal burner is ignited, operation is started through various operations thereafter, and during normal operation, a coal fired boiler is started. The steam is generated by the steam, the steam turbine is driven by the steam, and the generator generates power.

  On the other hand, when stopping the operation of coal-fired boiler equipment, in order to minimize the impact on the system, the generator load must be lowered enough to prevent deviations in the frequency of electricity generated, etc. The power generation load associated with the lower limit of the fuel flow rate of the coal burner's coal supply amount is too much larger than the power generation load at the time of disconnection, so use a fuel oil burner to reduce the power generation load. Yes.

  Specifically, as shown in FIG. 4 and FIG. 5, the power generation load starts to be reduced (step S102 in FIG. 4) from the normal operation load stage (step S101 in FIG. 4) where the coal is first burned by the coal burner. Here, in FIG. 5, the power generation load (generator output) and the coal burner supply amount (coal consumption) during normal operation are shown to be substantially constant, and the coal supply amount to the coal burner is reduced at the same time as the power generation load is reduced. I have to.

  Subsequently, the amount of coal supplied to the coal burner is reduced and the fuel oil burner is ignited at the time of a predetermined power generation load to co-fire coal and fuel oil (step S103 in FIG. 4). (Step S104 in FIG. 4). Further, the amount of coal supplied to the coal burner is further reduced to the lower limit value of the fuel flow rate and the flow rate of the fuel oil to the fuel oil burner is increased, so that the coal and fuel oil are co-fired at the normal operation minimum load (step of FIG. 4). S105). Thereafter, the supply of coal from the coal mill to the coal burner is stopped, the coal burner is extinguished, and the fuel oil is exclusively burned by the fuel oil burner (step S106 in FIG. 4). Here, in FIG. 5, the minimum normal operation load of the power generation load (generator output) is shown as an example of a substantially constant 30% load, and the fuel flow lower limit value of the coal burner coal supply amount (coal consumption) is substantially constant. Show. Further, the period of the normal operation minimum load includes the period of the fuel flow rate lower limit value of the coal burner and includes the time of extinguishing the coal burner. Further, the fuel oil consumption of the fuel oil burner increases during the normal operation minimum load period, and the fuel oil consumption of the fuel oil burner is maximized at the end of the normal operation minimum load period. Furthermore, in FIG. 5, after extinguishing the coal burner, 0 t / h is shown.

  Next, the power generation load is further reduced from the normal operation minimum load state (step S107 in FIG. 4) and the flow rate of the fuel oil to the fuel oil burner is decreased to the lower limit value of the fuel flow rate, and the turbine bypass valve is opened from a predetermined time. It opens small as the degree is small, and the pressure of the steam line is adjusted via the turbine bypass line (step S108 in FIG. 4). Then, after the generation load reaches a load capable of disconnecting the generator (step S109 in FIG. 4), the generator is disconnected after waiting for permission to release other conditions (step S110 in FIG. 4). Thereafter, the steam turbine is stopped (step S111 in FIG. 4), the fuel oil burner is extinguished and the turbine bypass valve is closed (step S112 in FIG. 4), and the operation of the coal fired boiler facility is stopped (step S113 in FIG. 4). ). Here, in FIG. 5, the power generation load is shown as being substantially constant from the time when the generator can be disconnected to the generator disconnection, and the fuel flow rate of the fuel oil burner (coal consumption) The lower limit value is shown substantially constant. In addition, before and after the generator is disconnected, the amount of fuel supplied to the fuel oil burner is the lower limit value of the fuel flow rate, and the pressure is appropriately adjusted by the turbine bypass valve. Further, in FIG. 5, 0 Mw is shown after the generator is disconnected by the power generation load.

  As prior art document information related to the present invention, for example, the following patent documents 1 and 2 already exist.

JP 2006-125808 A JP 58-18018 A

  However, in such a process for stopping the operation of coal-fired boiler facilities, a considerable amount of fuel oil must be used every time the operation is stopped, and the running cost increases due to the use of fuel oil more expensive than coal. was there.

  In view of such circumstances, the present invention intends to provide a method for stopping operation of coal-fired boiler equipment that reduces the amount of fuel oil used for operation stop and an operation stop device thereof.

A method for stopping operation of a coal-fired boiler facility according to the present invention includes a coal-fired boiler provided with a coal burner and a fuel oil burner, a steam turbine that drives a generator, and steam generated in the coal-fired boiler to a steam turbine. A method for shutting down coal-fired boiler equipment, comprising a supply steam line and a turbine bypass line that bypasses the steam turbine and flows steam from the steam line to the boiler,
Reduce the power generation load from the generator output during normal operation of the coal-fired boiler and reduce the amount of coal supplied to the coal burner. Steam unnecessary for the load is released to the turbine bypass line, and the generator is disconnected as the power generation load is reduced.

  In the method for stopping the operation of the coal fired boiler facility according to the present invention, it is preferable to release steam unnecessary for the power generation load to the turbine bypass line until the fuel flow rate lower limit value of the coal burner is reached and to disconnect the generator.

  Furthermore, in the method for stopping the operation of the coal fired boiler facility according to the present invention, it is preferable to extinguish the coal burner after disconnecting the generator as the power generation load is reduced.

  Furthermore, in the method for stopping the operation of the coal fired boiler facility of the present invention, it is preferable that the turbine bypass line is provided with a turbine bypass valve, and the steam is released to the turbine bypass line by adjusting the opening of the turbine bypass valve.

An operation stop device for a coal fired boiler facility according to the present invention includes a coal fired boiler provided with a coal burner and a fuel oil burner, a steam turbine for driving a generator, and steam generated in the coal fired boiler as a steam turbine. Operation of coal-fired boiler equipment having a steam line to be supplied, a turbine bypass line that bypasses the steam turbine and flows steam from the steam line to the boiler, and a turbine bypass valve that adjusts the flow rate of steam from the turbine bypass line A stop device,
When the operation is stopped, the power generation load is reduced from the generator output during normal operation of the coal-fired boiler and the amount of coal supplied to the coal burner is reduced. The steam is further reduced from the minimum load, and steam unnecessary for the power generation load is released to the turbine bypass line via the turbine bypass valve, and the generator is disconnected when the power generation load is reduced.

  According to the operation method and the operation stop device of the coal fired boiler facility of the present invention, the amount of coal supplied to the coal burner is reduced as the power generation load is reduced, and the power generation load is reduced without switching to the combustion of the fuel oil burner. Unnecessary steam escapes to the turbine bypass line and the generator is disconnected, greatly reducing the amount of fuel oil used to shut down operations, which was necessary in the past, and running using coal that is cheaper than fuel oil An excellent effect that the cost can be reduced can be obtained.

1 is an overall schematic configuration diagram showing a coal fired boiler facility of the present invention. It is a flowchart which shows the process of the operation stop of the coal burning boiler equipment of this invention. It is a figure which shows the time behavior about the electric power generation load (generator output) of this invention, the coal consumption by a coal burner, the fuel oil consumption by a fuel oil burner, and a turbine bypass valve opening degree. It is a flowchart which shows the process of the operation stop of the conventional coal burning boiler equipment. It is a figure which shows the time behavior about the conventional electric power generation load (generator output), the coal consumption by a coal burner, the fuel oil consumption by a fuel oil burner, and a turbine bypass valve opening degree.

  Embodiments of the present invention will be described below with reference to FIGS.

  The coal-fired boiler facility according to the embodiment includes a coal-fired boiler 3 in which a coal burner 1 and a fuel oil burner 2 are disposed, a steam turbine 5 that drives a generator 4, and steam generated in the coal-fired boiler 3. A steam line 6 that supplies steam to the steam turbine 5, a feed line 7 that feeds steam from the steam turbine 5 to a predetermined location, a steam that branches off from the steam line 6 on the upstream side of the steam turbine 5, and the boiler 3 and the like And a turbine bypass valve 9 disposed at a midway position of the turbine bypass line 8.

  The coal burner 1 is supplied with coal from a coal mill 10 through a coal supply line 11, and the fuel oil burner 2 of the coal-fired boiler 3 is supplied with fuel oil from a source of fuel oil such as light oil. Fuel oil is supplied through the supply line 12. Further, the coal-fired boiler 3 performs, as necessary, coal-only firing that burns only coal, fuel-only firing that burns only fuel oil, and mixed firing that burns by mixing coal and fuel oil. Here, the turbine bypass line 8 needs to have a capacity corresponding to the amount of steam generated at the fuel flow rate lower limit value of the coal burner 1.

  The steam turbine 5 is configured to be driven by steam from the steam line 6, and the steam that has driven the steam turbine 5 is supplied by a feed line 7 to save a car (not shown) or heat of the coal-fired boiler 3. It is fed to an exchanger (not shown) and used as main feed water or low-temperature reheat steam.

  The turbine bypass line 8 flows steam from the steam line 6 to the supply line 7 so as to bypass the steam turbine 5, and the flow rate of the steam is adjusted by the opening degree of the turbine bypass valve 9.

  The operation of the embodiment for carrying out the present invention will be described below.

  When starting the operation of the coal fired boiler facility, the inside of the furnace is preheated by the fuel oil burner 2 to ignite the coal burner 1, and the operation is started through various subsequent operations, as in the conventional example. During normal operation, steam is generated in the coal-fired boiler 3, and power is generated by the generator 4 via the steam turbine 5 using the steam.

  On the other hand, when the operation of the coal burning boiler facility is stopped, the amount of coal supplied to the coal burner 1 is reduced and the turbine bypass line 8 is applied without switching from the combustion of the coal burner 1 to the combustion of the fuel oil burner 2. Reduce power generation load.

  Specifically, as shown in FIG. 2 and FIG. 3, the power generation load starts to be reduced from the normal operation load stage (step S1 in FIG. 2) where the coal is first burned by the coal burner 1 (step S2 in FIG. 2). . Here, in FIG. 3, the power generation load (generator output) during normal operation and the coal supply amount (coal consumption) of the coal burner 1 are shown to be substantially constant, and the coal supply amount to the coal burner 1 is also reduced simultaneously with the reduction of the power generation load. I try to reduce it. Further, the power generation load during normal operation is not limited to 50% load as shown in FIG. 3, and may vary as required.

  Subsequently, the amount of coal supplied to the coal burner 1 is reduced in a state where the coal is exclusively burned (step S3 in FIG. 2), and the power generation load is reached to the stage of the normal operation minimum load (step S4 in FIG. 2). Here, in FIG. 3, the normal operation minimum load of the power generation load (generator output) is shown as a substantially constant 30% load, and the coal supply amount (coal consumption) of the coal burner 1 at the normal operation minimum load is shown as substantially constant. ing. Further, the normal operation minimum load of the power generation load is 30% load in this embodiment, but may be different depending on the equipment. Furthermore, it is preferable that the coal supply amount of the coal burner 1 fluctuates corresponding to the reduction in the power generation load until the generator 4 is disconnected.

  Next, the power generation load is further lowered from the state of the normal operation minimum load (step S5 in FIG. 2), and the amount of coal supplied to the coal burner 1 is further reduced to a fuel flow lower limit value while the coal is exclusively burned. When the load associated with the amount of coal supplied to the coal burner 1 exceeds the required power generation load as the power generation load is reduced, the turbine bypass valve 9 is opened (step S6 in FIG. 2), which is unnecessary for the power generation load. Steam escapes from the turbine bypass line 8 to the feed line 7. Here, the lower limit value of the fuel flow rate of the coal burner 1 differs depending on the burner capacity, and the turbine bypass line 8 needs to have a capacity corresponding to the amount of steam generated at the lower limit value of the fuel flow rate of the coal burner 1.

  Thereafter, the generator 4 is disconnected after waiting for permission to disconnect other conditions from the time when the generator load reaches a load that can disconnect the generator 4 (step S7 in FIG. 2) (step in FIG. 2). S8). Then, the steam turbine 5 is stopped (step S9 in FIG. 2), then the coal mill 10 is stopped to extinguish the coal burner 1, and the opening of the turbine bypass valve 9 is closed (step S10 in FIG. 2). The operation of the boiler equipment is stopped (step S11 in FIG. 2).

  Here, in FIG. 3, the period from the time when the generator 4 becomes a load that can be disconnected to the disconnection of the generator 4 is shown as being substantially constant, and 0 Mw is indicated after the generator 4 is disconnected. Further, the lower limit value of the fuel flow rate of the coal supply amount (coal consumption amount) of the coal burner 1 is shown as being substantially constant, and after the fire extinguishing of the coal burner 1 is shown as 0 t / h. Further, during the period before and after the generator 4 is disconnected, the coal supply amount of the coal burner 1 is the fuel flow rate lower limit value. Furthermore, the power generation load in the period from when the generator 4 can be disconnected to the disconnection of the generator 4 is not limited to a constant value, and may vary depending on conditions. The fuel flow rate lower limit value of the coal burner 1 may also vary depending on the conditions. Further, the opening degree of the turbine bypass valve 9 increases from the time when a load capable of disconnecting the generator 4 is reached and / or when the coal supply amount of the coal burner 1 reaches the fuel flow rate lower limit value. The large opening is 10-30% larger than the conventional small opening. Furthermore, it is preferable that the opening degree of the turbine bypass valve 9 is kept large until the coal burner 1 is extinguished. Further, the opening degree of the turbine bypass valve 9 may be adjusted as appropriate so that the amount of coal supplied to the coal burner 1 does not become too small during the reduction of the power generation load. Furthermore, the fuel oil supply amount (fuel oil consumption amount) of the fuel oil burner 2 does not change over to the combustion of the fuel oil burner 2 or the combustion of the fuel oil burner 2 in the process of shutdown. In FIG. 3, the fuel oil supply amount of the fuel oil burner 2 is indicated by 0 t / h. Also, the phantom line in FIG. 3 shows the fuel oil supply amount (fuel oil consumption) of the conventional fuel oil burner, and the portion surrounded by the phantom line and the solid line in FIG. Consumption).

  Further, when the conventional operation stop and the operation stop of the embodiment of the present invention are actually compared, in the case of the conventional operation stop, the amount of fuel oil (light oil) used by the fuel oil burner is about 50 to 60 t / time. Thus, when the operation of the embodiment of the present invention was stopped, the amount of fuel oil (light oil) used by the fuel oil burner was about 0 t / time. As a result, it is apparent that the stop processing according to the embodiment of the present invention can significantly reduce the amount of fuel oil used as compared with the prior art.

  Thus, according to the embodiment as described above, the amount of coal supplied to the coal burner 1 is reduced stepwise as the power generation load is reduced, and the fuel oil burner 2 is not switched to combustion or exclusive combustion. Steam that is unnecessary for the load is released to the turbine bypass line 8 and the generator 4 is disconnected, so that the amount of fuel oil used for shutting down operation, which has been necessary in the past, is greatly reduced, and coal is cheaper than fuel oil. The running cost can be reduced using

  In the embodiment, between the fuel flow rate lower limit value of the coal burner 1, steam unnecessary for the power generation load is released to the turbine bypass line 8, and the generator 4 is disconnected, the amount of coal supplied to the coal burner 1 is reduced to fuel. Since the steam is reduced step by step to the lower limit of the flow rate, and steam that is unnecessary for the power generation load is appropriately released to the turbine bypass line 8 and the generator 4 is disconnected, the amount of fuel oil used for shutting down the operation that has been conventionally required can be reduced. The running cost can be further reduced by using coal that is greatly reduced and cheaper than fuel oil.

  In the embodiment, if the coal burner 1 is extinguished after the generator 4 is disconnected along with the reduction in the power generation load, the coal burner 1 can be extinguished regardless of the reduction in the power generation load. It is possible to greatly reduce the amount of fuel oil used and at the same time to easily stop operation and reduce running costs.

  In the embodiment, when the turbine bypass line 8 is provided with the turbine bypass valve 9 and the opening degree of the turbine bypass valve 9 is adjusted to release the steam to the turbine bypass line 8, the flow rate of the steam is adjusted in accordance with the process of shutdown. Since it can be adjusted, the amount of fuel oil used for stopping the operation can be greatly reduced, and the running cost can be further reduced.

  Further, when a wide range burner having a low fuel flow rate lower limit value of the coal supply amount is used as the coal burner 1, steam that escapes to the turbine bypass line 8 as steam unnecessary for the power generation load is reduced. Therefore, it is possible to greatly reduce the amount of fuel oil used for the operation, and at the same time, it is possible to easily stop operation and reduce running cost.

  In addition, the operation stop method and the operation stop device of the coal fired boiler facility of the present invention are not limited to the above illustrated examples, and various changes can be made without departing from the gist of the present invention. Of course.

DESCRIPTION OF SYMBOLS 1 Coal burner 2 Fuel oil burner 3 Coal fired boiler 4 Generator 5 Steam turbine 6 Steam line 8 Turbine bypass line 9 Turbine bypass valve

Claims (5)

A coal-fired boiler provided with a coal burner and a fuel oil burner, a steam turbine that drives a generator, a steam line that supplies steam generated in the coal-fired boiler to the steam turbine, and bypasses the steam turbine A method for shutting down coal-fired boiler equipment having a turbine bypass line for flowing steam from the steam line to the boiler,
Reduce the power generation load from the generator output during normal operation of the coal-fired boiler and reduce the amount of coal supplied to the coal burner. A method for shutting down a coal-fired boiler facility, characterized in that steam unnecessary for a load is allowed to escape to a turbine bypass line and the generator is disconnected as the power generation load is reduced.   2. The method for stopping operation of coal-fired boiler equipment according to claim 1, wherein steam that is unnecessary for power generation load is released to a turbine bypass line and the generator is disconnected until a fuel flow rate lower limit value of the coal burner is reached.   The method for stopping operation of a coal-fired boiler facility according to claim 1 or 2, wherein the coal burner is extinguished after the generator is disconnected along with the reduction of the power generation load.   The operation stop of the coal fired boiler equipment according to any one of claims 1 to 3, wherein a turbine bypass valve is provided in the turbine bypass line, and steam is released to the turbine bypass line by adjusting an opening degree of the turbine bypass valve. Method. A coal-fired boiler provided with a coal burner and a fuel oil burner, a steam turbine that drives a generator, a steam line that supplies steam generated in the coal-fired boiler to the steam turbine, and bypasses the steam turbine A shutdown apparatus for coal-fired boiler equipment having a turbine bypass line for flowing steam from the steam line to the boiler, and a turbine bypass valve for adjusting the flow rate of steam from the turbine bypass line,
When the operation is stopped, the power generation load is reduced from the generator output during normal operation of the coal-fired boiler and the amount of coal supplied to the coal burner is reduced. Coal which is configured to further lower the minimum load, release steam unnecessary for the power generation load to the turbine bypass line via the turbine bypass valve, and disconnect the generator as the power generation load decreases. Operation stop device for fired boiler equipment.

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