JP2006152081A - Coal gasification plant and method for operating the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive coal gasification plant that effectively solves the problem on pipeline corrosion and enables the fuel gas to be promptly fed to the bypass line on an emergency. <P>SOLUTION: In the coal gasification combined power generator 1 equipped with a coal gasification furnace 3, a dust remover 5, a gas purifier 7, a gas turbine 11 or the like and the main line 15 for connecting these apparatuses and the bypass line 33 for linking the output side of the coal gasification furnace 3 to the flare stack 39, a dust remover by-pass valve 35 that is set on the upper stream of the bypass line 33 for opening and closing the bypass line 33 and the treated gas-controlling valve 41 that is set on the downstream side of the bypass line 33 for controlling the gas flow, further the first nitrogen-charging line 37 is equipped for feeding inert gas into the bypass line 33. <P>COPYRIGHT: (C)2006,JPO&amp;NCIPI

Description

  The present invention relates to a coal gasification plant that gasifies coal and uses it as fuel for a gas turbine or the like, and an operation method thereof.

Conventionally, a coal gasification plant has been attracting attention as an effective use of abundant coal. In such a coal gasification plant, in order to discharge fuel gas that cannot be used downstream at the time of start-up, and to depressurize the inside of the plant at the time of a normal stop or emergency stop, a bypass for discharging the fuel gas in the plant A line is provided. Since the fuel gas flowing through the bypass line is corrosive, countermeasures against the corrosion of the bypass line are required.
As a coal gasification plant with such a countermeasure against corrosion, for example, one disclosed in Patent Document 1 has been proposed.
This is to provide a heater for heating the line upstream of the bypass valve arranged on the bypass line and opening and closing the same, thereby heating the upstream side of the bypass valve to prevent the fuel gas from condensing. In addition to this, a gas with less moisture is injected upstream of the bypass valve to prevent the fuel gas from flowing into the bypass line.

Japanese Patent Laid-Open No. 10-298563 (paragraphs [0003] to [0007] and FIGS. 1 to 3)

By the way, what was described in patent document 1 is a thing for the process at the time of starting, and was inadequate as a countermeasure against corrosion including the time of operation.
When a malfunction occurs in the coal gasification plant during operation, it is necessary to flow the fuel gas through the bypass line and depressurize the plant to stop the plant. At this time, in order to perform urgent processing, it is necessary to keep the pressure of the bypass line substantially the same as that in the plant. Otherwise, when fuel gas of about 3 MPa flows into the bypass line under atmospheric pressure, the inflow speed reaches the sonic speed, and the bypass valve and the bypass line are rapidly worn and damaged. For this reason, in the conventional system, the normal operation has to open the bypass valve to allow the fuel gas to flow into the bypass line and retain it to balance the pressure. In order to prevent corrosion of the bypass line, heating was performed to prevent the fuel gas from condensing, or the bypass line was formed of an expensive corrosion-resistant material.
In many cases, the gas processing equipment cannot be arranged in the vicinity of the plant, and there is a problem that the bypass line becomes long and the manufacturing cost increases.

  In view of the above problems, an object of the present invention is to effectively solve the problem of corrosion of the bypass line, and to supply emergency fuel gas to the bypass line immediately and to provide an inexpensive coal gasification plant.

In order to solve the above problems, the present invention employs the following means.
That is, a coal gasification plant according to the present invention includes a coal gasification furnace that gasifies coal to generate fuel gas, a dust removal device that removes solids in the fuel gas, sulfides in the fuel gas, and the like. A gas refining device that supplies the gas turbine as fuel, the coal gasification furnace, the dust removal device, the gas refining device, the gas turbine, and the like, and the coal gas in the main system line In a coal gasification plant comprising a bypass line that connects an outlet side of a gasification furnace and a gas processing facility, a bypass valve that is provided upstream of the bypass line and opens and closes the bypass line; and A processing gas control valve for adjusting the flow rate provided in the downstream portion, and an inert gas provided on the downstream side of the bypass valve to the bypass line A first inert gas input line for supplying, characterized in that is provided.

At the start of the coal gasifier, the fuel gas produced by the coal gas furnace is insufficient as fuel, for example, low calorie, so the bypass line is not the main system line until the coal gasifier is in sufficient condition. The gas is treated by a gas treatment device and discharged out of the system.
According to the present invention, after the temperature rise and pressure increase of the coal gasification furnace is completed and the bypass valve is closed, the inert gas is supplied from the first inert gas introduction line to the downstream side of the bypass valve, and the bypass line is supplied. The remaining fuel gas is discharged to the gas processing facility. Even after the remaining combustion gas is discharged, the inert gas is supplied from the first inert gas input line, the fuel gas leaking from the bypass valve is discharged to the gas processing device, and the pressure of the bypass line is controlled by the processing gas control valve. It is adjusted to be approximately the same as the line.

Thus, the fuel gas flowing into the bypass line at startup and the fuel gas leaking from the bypass valve during normal operation are discharged to the gas processing facility by the inert gas supplied from the first inert gas input line. The fuel gas will not stay in the bypass line. For this reason, the fuel gas is cooled and dew condensation does not occur, so that corrosive substances such as sulfuric acid are not generated. Therefore, the occurrence of corrosion in the bypass line can be effectively prevented.
Further, as a countermeasure against corrosion of the bypass line, means such as heating the bypass line so as not to condense or forming the bypass line with an expensive corrosion-resistant material is not required, so that a coal gasification plant can be manufactured at a low cost.

Furthermore, during normal operation, the pressure in the bypass line is maintained substantially the same as the pressure in the main system line, so that even if the bypass valve is opened, the fuel gas containing dust such as unburned char exceeds the speed of sound, for example. It does not spout into the bypass line at high speed. For this reason, since the bypass valve can be opened without considering damage to the bypass line during operation, the bypass valve can be opened immediately in case of an emergency or stop, and the equipment in the main system line can be decompressed.
As the inert gas, nitrogen gas is preferable in view of availability and price.

  Further, in the coal gasification plant of the present invention, a first branch line that connects the dust removal device and the gas purification device in the main system line and the bypass line, and the first branch line is provided. The first branch bypass valve and a second inert gas input line provided on the downstream side of the first branch bypass valve are provided.

When starting the dust removal device after starting the coal gasification furnace, the bypass valve is closed and the first branch bypass valve is opened. As a result, the fuel gas generated in the coal gasification furnace is separated from unburned char and the like by the dust removing device, flows into the bypass line via the first branch line, is processed by the gas processing device, and is discharged outside the system. Discharged.
According to the present invention, after the start-up process of the dust removing device is completed and the first branch bypass valve is closed, the inert gas is supplied to the downstream side of the first branch bypass valve from the second inert gas introduction line, The fuel gas remaining in the first branch line is discharged to the gas processing facility. Even after the remaining combustion gas is discharged, the inert gas is supplied from the second inert gas input line, the fuel gas leaking from the first branch bypass valve is discharged to the gas processing device, and the pressure of the bypass line is controlled by the processing gas control valve. Is adjusted to be approximately the same as the main system line.

As described above, the fuel gas flowing into the first branch line at the time of startup and the fuel gas leaking from the first branch bypass valve during normal operation are treated by the inert gas supplied from the second inert gas input line. Therefore, the fuel gas does not stay in the first branch line and the bypass line together with the inert gas from the first inert gas input line.
For this reason, the fuel gas is cooled and dew condensation does not occur, so that corrosive substances such as sulfuric acid are not generated. Therefore, the occurrence of corrosion in the first branch line and the bypass line can be effectively prevented.
In addition, as a countermeasure against corrosion of the first branch line and bypass line, there is no need to heat them so as to prevent condensation or to form them with expensive corrosion-resistant materials. it can.

  Further, during normal operation, the pressure in the bypass line and the first branch line is maintained substantially the same as the pressure in the main system line, so that even if the bypass valve or the first branch bypass valve is opened, the fuel gas is at a sonic speed, for example. It does not spout to the bypass line or the first branch line at such an ultra high speed. For this reason, since the bypass valve can be opened without considering damage to the bypass line or the like during operation, the bypass valve can be opened immediately in case of an emergency or stop, and the equipment in the main system line can be decompressed.

  Furthermore, the coal gasification plant of the present invention includes a second branch line connecting the outlet of the gas purification device in the main system line and the bypass line, and a second branch provided in the second branch line. A bypass valve and a third inert gas introduction line provided on the downstream side of the second branch bypass valve are provided.

For example, when starting the gas purification device after starting the coal gasification furnace and the dust removal device, the bypass valve and the first branch bypass valve are closed and the second branch bypass valve is opened. As a result, the fuel gas generated in the coal gasification furnace passes through the dust removal device and the gas purification device, flows into the bypass line via the second branch line, and is processed and discharged by the gas processing device.
According to the present invention, after the start-up process of the gas purifier is completed and the second branch bypass valve is closed, the inert gas is supplied to the downstream side of the second branch bypass valve from the third inert gas introduction line. The fuel gas remaining in the second branch line is discharged to the gas processing facility. Even after the remaining combustion gas is discharged, the inert gas is supplied from the third inert gas input line, the fuel gas leaking from the second branch bypass valve is discharged to the gas processing device, and the pressure of the bypass line is controlled by the processing gas control valve. Is adjusted to be approximately the same as the main system line.

As described above, the fuel gas flowing into the second branch line at the start-up and the fuel gas leaking from the second branch bypass valve during the normal operation are processed by the inert gas supplied from the third inert gas input line. Therefore, the fuel gas does not stay in the first branch line, the second branch line, and the bypass line together with the inert gas from the first inert gas input line and the second inert gas input line. .
For this reason, the fuel gas is cooled and no condensation occurs to generate corrosive substances such as sulfuric acid, so that the occurrence of corrosion in the first branch line, the second branch line, and the bypass line can be effectively prevented.
In addition, as a countermeasure against corrosion of the second branch line and the bypass line, it is not necessary to carry out means such as heating them so as to prevent condensation or forming them with expensive corrosion-resistant materials. Can be manufactured.
Note that when the inert gas supplied from the first inert gas input line can discharge the fuel gas remaining in the downstream portion of the first branch line from the first branch bypass valve, for example, The inert gas input line can be omitted.

The operation method of the coal gasification plant of the present invention is a gas turbine in which a fuel gas is generated from coal by a coal gasification furnace, solids are removed from the fuel gas by a dust removing device, and then desulfurized and the like by a gas purification device. In a method for operating a coal gasification plant that supplies fuel as a fuel,
At the time of start-up, after closing the bypass valve provided in the bypass line, the fuel gas flowing into the bypass line branched from the outlet portion of the coal gasification furnace and connected to the gas processing facility, the bypass valve The exhaust gas is discharged from the bypass line by the inert gas supplied to the downstream side of the gas, and the pressure in the bypass line is maintained at substantially the same level as the pressure of the fuel gas by the inert gas constantly supplied during normal operation. It is characterized by doing.

According to the present invention, at the time of start-up, the fuel gas flowing into the bypass line is discharged to the gas processing facility by the inert gas supplied to the downstream side of the bypass valve. Since the inert gas is always supplied during normal operation, the fuel gas leaking from the bypass valve is discharged to the gas processing facility by the inert gas. Further, in this case, the inert gas almost flows through the bypass line.
As described above, since the fuel gas does not stay in the bypass line, the fuel gas is not cooled and condensed, and corrosive substances such as sulfuric acid are not generated. Therefore, the occurrence of corrosion in the bypass line can be effectively prevented.
Further, as a countermeasure against corrosion of the bypass line, means such as heating the bypass line so as not to condense or forming the bypass line with an expensive corrosion-resistant material is not required, so that a coal gasification plant can be manufactured at a low cost.
Furthermore, during normal operation, the pressure in the bypass line is maintained at approximately the same level as the pressure of the fuel gas. Therefore, in an emergency, the fuel gas is immediately flowed into the bypass line without considering the damage to the bypass line. The inside can be depressurized.

  In the operation method of the coal gasification plant of the present invention, at the time of start-up, the fuel gas that branches from the outlet portion of the dust removal device and flows into the first branch line connected to the bypass line, After closing the first branch valve provided in the branch line, the inert gas supplied to the downstream side of the first branch valve is discharged from the first branch line and the bypass line, and is always supplied during normal operation. The pressure in the first branch line and the bypass line is maintained at substantially the same level as the pressure of the fuel gas by the inert gas.

According to the present invention, at start-up, the fuel gas flowing into the first branch line is discharged to the gas processing facility by the inert gas supplied downstream of the first branch valve. Since the inert gas is always supplied during normal operation, the fuel gas leaking from the first branch valve is discharged to the gas processing facility by the inert gas. Further, in this case, the inert gas almost flows through the bypass line.
As described above, since the fuel gas does not stay in the first branch line and the bypass line, the fuel gas is not cooled and condensed, and corrosive substances such as sulfuric acid are not generated. Therefore, the occurrence of corrosion in the first branch line and the bypass line can be effectively prevented.
In addition, as a countermeasure against corrosion of the bypass line and the like, it is not necessary to heat the bypass line or the like so as to prevent condensation or to form the bypass line or the like with an expensive corrosion-resistant material. it can.
Furthermore, during normal operation, the pressure in the first branch line and bypass line is maintained at approximately the same level as the pressure of the fuel gas. It is possible to immediately flow into them and reduce the pressure in the plant.

  Furthermore, in the operation method of the coal gasification plant of the present invention, at the time of start-up, the fuel gas branched from the outlet portion of the gas purifier and introduced into the second branch line connected to the bypass line, After closing the second branch valve provided in the two branch line, the inert gas supplied to the downstream side of the second branch valve is discharged from the second branch line and the bypass line, and during normal operation, The inert gas maintains the pressure in the second branch line and the bypass line at substantially the same level as the pressure of the fuel gas.

According to the present invention, at the time of start-up, the fuel gas flowing into the second branch line is discharged to the gas processing facility by the inert gas supplied downstream of the second branch valve. Since the inert gas is always supplied during normal operation, the fuel gas leaking from the second branch valve is discharged to the gas processing facility by the inert gas. Further, in this case, the inert gas almost flows through the bypass line.
As described above, since the fuel gas does not stay at least in the second branch line and the bypass line, the fuel gas is not cooled and condensed, and corrosive substances such as sulfuric acid are not generated. Therefore, the occurrence of corrosion in the second branch line and the bypass line can be effectively prevented.
In addition, as a countermeasure against corrosion of the bypass line etc., there is no need to heat the bypass line etc. so as to prevent condensation, or to form the bypass line etc. with an expensive corrosion-resistant material. it can.
Furthermore, during normal operation, at least the pressure in the second branch line and the bypass line is maintained at approximately the same level as the pressure of the fuel gas, so that the fuel gas is considered to be damaged in the second branch line and the bypass line in an emergency. It is possible to immediately flow into them without reducing the pressure in the plant.

According to the coal gasification plant of the present invention, the fuel gas that has flowed into the bypass line or the like at startup and the fuel gas that leaks from the bypass valve or the like during normal operation are generated by the inert gas supplied downstream of the bypass valve or the like. Since it is discharged to the gas processing facility, it is possible to effectively prevent the occurrence of corrosion in the bypass line.
In addition, as a countermeasure against corrosion of the bypass line, it is not necessary to heat the bypass line so as to prevent condensation or to form the bypass line with an expensive corrosion-resistant material, so that a coal gasification plant can be manufactured at a low cost.
In addition, during normal operation, the pressure in the bypass line is maintained approximately the same as the pressure in the main system line, so the bypass valve is opened immediately in the event of an emergency or stop, and the equipment in the main system line is decompressed. be able to.

According to the operation method of the coal gasification plant of the present invention, the fuel gas flowing into the bypass line or the like at startup and the fuel gas leaking from the bypass valve or the like during normal operation are not supplied to the downstream side of the bypass valve or the like. Since it is discharged to the gas processing facility by the active gas, it is possible to effectively prevent the occurrence of corrosion in the bypass line or the like.
In addition, as a countermeasure against corrosion of the bypass line etc., there is no need to heat the bypass line etc. so as to prevent condensation, or to form the bypass line etc. with an expensive corrosion-resistant material. it can.
Furthermore, during normal operation, the pressure in the bypass line is maintained at approximately the same level as the pressure of the fuel gas. Therefore, in an emergency, the fuel gas is immediately allowed to flow into the bypass line without considering damage to the bypass line. The pressure inside the plant can be reduced.

Hereinafter, a combined coal gasification combined power generation apparatus (coal gasification plant) 1 according to an embodiment of the present invention will be described with reference to FIG.
FIG. 1 is a block diagram showing a schematic configuration of a coal gasification combined power generation device 1.
The coal gasification combined power generation apparatus 1 includes a coal gasification furnace 3, a dust removal device 5, a gas purification device 7, a gas turbine combustor 9, a gas turbine 11, and an exhaust heat recovery boiler 13. ing.
Each of these devices is connected by a main system line 15.

The coal gasifier 3 is supplied with pulverized coal 17, a gasifying agent 19 and char 21 under pressure. The pulverized coal 17 is supplied as a pulverized coal of several μm to several hundred μm by pulverizing raw coal in a pre-process (not shown). As the gasifying agent 19, air or oxygen is supplied. The char 21 is an unburned component contained in the fuel gas generated in the coal gasification furnace 3 as will be described later.
In the coal gasification furnace 3, by burning these pulverized coal 17, the gasifying agent 19 and the char 21, the carbon in the pulverized coal 17 and the char 21 reacts with CO ₂ and H ₂ O in the high temperature gas. An endothermic reaction to generate CO and H ₂ is performed. These CO and H ₂ are used as fuel gas for the gas turbine.

The fuel gas generated in the coal gasification furnace 3 contains char, which is an unburned solid content, and is led to the dust removing device 5 through the main system line 15. The dust removing device 5 includes a porous filter, and captures and collects the char 21 mixed in the fuel gas by passing through the porous filter. The char 21 thus collected is returned to the coal gasifier 3 and recycled.
A dust removal device inlet valve 23 is provided on the upstream side of the dust removal device 5 in the main system line 15.

The fuel gas that has passed through the dust removal device 5 is sent to the gas purification device 7.
In the gas purification device 7, for example, sulfide is removed from the fuel gas. The gas purification device 7 is usually a wet type, and a COS converter that converts COS in fuel gas into H ₂ S using a catalyst, a gas cooling tower, a gas washing tower, and H ₂ filled with an H ₂ S absorption liquid. It is composed of an S absorption tower and a heat exchanger for raising the temperature of the cooled fuel gas.
The fuel gas desulfurized and the like in the gas purification device 7 is guided to the gas turbine combustor 9 through the main system line 15.
A flow control valve 25 is provided on the upstream side of the gas turbine combustor 9 in the main system line 15.

An air compressor 27 is connected to the gas turbine 11 through the same rotating shaft.
The air compressor 27 is configured to send compressed air to the gas turbine combustor 9. In the gas turbine combustor 9, the fuel gas sent from the gas purification device 7 is combusted by the high-pressure air from the air compressor 27 and supplied to the gas turbine 11 as the combustion gas.
A generator 29 connected to a rotating shaft driven by the gas turbine 11 is provided on the opposite side of the air compressor 27 across the gas turbine 11.

The combustion exhaust gas from the gas turbine 11 is guided to the exhaust heat recovery boiler 13. The exhaust heat recovery boiler 13 generates steam by the combustion exhaust gas from the gas turbine 11, and the gas that has passed through the exhaust heat recovery boiler 13 is released from the chimney 31 to the atmosphere.
The exhaust heat recovery boiler 13 is configured to drive, for example, a steam turbine (not shown) connected to the generator 29 with the generated steam. The steam turbine may drive a generator other than the generator 29.

A bypass line 33 is connected to a position (exit side of the coal gasification furnace 3) A between the coal gasification furnace 3 and the dust removal apparatus inlet valve 23 in the main system line 15. The other end of the bypass line 33 is connected to a flare stack (gas treatment facility) 39.
In a gas processing facility, it is normal to incinerate gas, and in addition to the flare stack incinerated at the top of the chimney as in this embodiment, a ground flare that forms a cover on the ground and incinerate in it may be used. .
Since the flare stack 39 is incinerated, it is often installed away from the main body (for example, several hundred meters away) in consideration of safety and arrangement.

A dust removal device bypass valve (bypass valve) 35 that opens and closes the bypass line 33 is provided upstream of the bypass line 33 (position close to the main system line 15).
A first nitrogen charging line (first inert gas charging line) 37 for supplying nitrogen gas is connected to the bypass line 33 immediately downstream of the dust removing device bypass valve 35.
A processing gas regulating valve 41 that regulates the flow rate of gas passing through the bypass line 33 is provided in a downstream portion of the bypass line 33 (position close to the flare stack 39).
A pressure sensor 43 that measures the pressure in the bypass line 33 is provided on the upstream side of the processing gas control valve 41 in the bypass line 33. The processing gas control valve 41 is controlled so that the opening degree is adjusted according to the measured value of the pressure sensor 43.

A first branch line 45 that connects the bypass line 33 and the position B between the dust removing device 5 and the gas purification device 7 in the main system line 15 is connected. The first branch line 45 is provided with a gas purification bypass valve (first branch valve) 47 that opens and closes the first branch line 45.
A second nitrogen input line (second inert gas input line) 49 for supplying nitrogen gas is connected to the first branch line 45 immediately downstream of the gas purification bypass valve 47.

A second branch line 51 that connects the bypass line 33 and the position C between the gas purification device 7 and the flow rate control valve 25 in the main system line 15 is connected. The second branch line 51 is provided with a gas turbine bypass valve (second branch valve) 53 that opens and closes the second branch line 51.
A third nitrogen input line (third inert gas input line) 55 for supplying nitrogen gas is connected to the second branch line 51 immediately downstream of the gas turbine bypass valve 53.
In the present embodiment, nitrogen gas is used from the standpoint of availability as an inert gas and price, but this may be any non-burning gas such as carbon dioxide, argon, helium, or combustion exhaust gas.
Moreover, as an inert gas supplied, a thing with little moisture is suitable.

Operation | movement of the coal gasification combined cycle power generation apparatus 1 concerning this embodiment demonstrated above is demonstrated.
First, the procedure at the time of starting of the coal gasification combined cycle generator 1 will be described.
In this embodiment, the gas ventilation of the coal gasification combined power generation device 1 is performed in the order of the coal gasification furnace 3, the dust removal device, the gas purification device 7, and the gas turbine 11.

When the coal gasification furnace 3 is started, the dust removal device inlet valve 23 of the main system line 15 is closed so that the fuel gas generated in the coal gasification furnace 3 is not sent to the dust removal device 5. Then, the dust removal device bypass valve 35 of the bypass line 33 is opened so that the fuel gas generated in the coal gasification furnace 3 is discharged to the flare stack 39 through the bypass line 33.
In this state, the coal gasification furnace 3 is started. The starting fuel gas generated in the coal gasification furnace 3 is sent from the dust removing device bypass valve 35 to the flare stack 39 through the bypass line 33. Then, it is burned in the flare stack 39 and released into the atmosphere.

When the temperature of the coal gasification furnace 3 is sufficiently raised, the dust removal device inlet valve 23 is opened, and the fuel gas generated in the coal gasification furnace 3 is sent to the dust removal device 5. At the same time, the dust removal device bypass valve 35 is closed, and the supply of fuel gas from the coal gasification furnace 3 to the bypass line 33 is stopped.
In this state, nitrogen gas is supplied from the first nitrogen input line 37 to the bypass line 33, and the fuel gas remaining in the bypass line 33 is guided to the flare stack 39, incinerated, and discharged.

Next, the start-up operation of the dust removing device 5 is started and the gas purification bypass valve 47 is opened. The fuel gas from the dust removing device 5 is sent to the flare stack 39 through the first branch line 45 and the bypass line 33. Then, it is burned in the flare stack 39 and released into the atmosphere.
When the start-up operation of the dust removing device 5 is completed, the gas purification bypass valve 47 is closed and the fuel gas is sent to the gas purification device 7. At the same time, the dust removal device bypass valve 35 is closed, and the fuel gas is not supplied from the coal gasification furnace 3 to the bypass line 33.

In this state, nitrogen gas is supplied from the second nitrogen input line 49 to the first branch line 45, and the fuel gas remaining downstream from the gas purification bypass valve 47 of the first branch line 45 is led to the flare stack 39 and incinerated. Then discharge.
If the position of the gas purification bypass valve 47 is brought closer to the bypass line 33, the downstream distance from the gas purification bypass valve 47 of the first branch line 45 is shortened, so that the nitrogen supplied from the first nitrogen input line 37 is reduced. Residual combustion gas in this part can be discharged by the gas.
In this case, the second nitrogen gas input line 49 can be omitted.

Next, the start operation of the gas purifier 7 is started while the control valve 25 is closed, and the gas turbine bypass valve 53 is opened. The fuel gas from the gas purifier 7 is sent to the flare stack 39 through the second branch line 51 and the bypass line 33. Then, it is burned in the flare stack 39 and released into the atmosphere.
When the start-up operation of the gas purification device 7 is completed, the control valve 25 is opened and the fuel gas is sent to the turbine combustion device 9. At the same time, the gas turbine bypass valve 53 is closed, and the fuel gas is not supplied to the second branch line 51 and the bypass line 33.
In this state, nitrogen gas is supplied from the third nitrogen input line 55 to the second branch line 51, the gas turbine bypass valve 53 of the second branch line 51, the gas purification bypass valve 47 is closed, and the fuel gas remaining further downstream. Is led to the flare stack 39, incinerated and discharged.

  Thus, at the time of start-up, the fuel gas remaining after flowing into the bypass line 33 and the like from the main system line 15 side is supplied from the first nitrogen input line 37, the second nitrogen input line 49, or the third nitrogen input line 55. Since the nitrogen gas is sent to the flare stack 39 and burned, the fuel gas does not stay in the bypass line.

The coal gasification combined power generation device 1 activated in this way enters a normal operation.
In the coal gasification furnace 3, by burning the pulverized coal 17, the gasifying agent 19 and the char 21 supplied under pressure, the carbon in the pulverized coal 17 and the char 21 is converted into CO ₂ and H ₂ in the high-temperature gas. A fuel gas containing CO or H ₂ as a component is generated by reacting with O.
The fuel gas generated in the coal gasification furnace 3 is guided to the dust removing device 5 through the main system line 15, and the mixed char 21 is collected by the dust removing device 5. Then, the recovered char 21 is returned to the coal gasification furnace 3 and recycled.

The fuel gas that has passed through the dust removal device 5 is sent to the gas purification device 7, and for example, sulfide is removed from the fuel gas.
The fuel gas desulfurized or the like in the gas purification device 7 is guided to the gas turbine combustor 9 by the main system line 15 and burned with the compressed air sent from the air compressor 27.
In the gas turbine combustor 9, the fuel gas sent from the gas purification device 7 is combusted by the high-pressure air from the air compressor 27 and supplied to the gas turbine 11 as the combustion gas.
The gas turbine 11 is rotationally driven by the combustion gas, and a generator 29 connected to the rotational shaft converts the rotational driving force into electric power.

The combustion exhaust gas that has passed through the gas turbine 11 is guided to the exhaust heat recovery boiler 13, and steam is generated using the sensible heat of the combustion exhaust gas. The steam generated in the exhaust heat recovery boiler 13 is used for, for example, power generation by driving a steam turbine (not shown).
The combustion exhaust gas that has passed through the exhaust heat recovery boiler 13 is guided to the chimney 31 and released from the chimney 31 into the atmosphere.

At this time, the dust removal device bypass valve 35, the gas purification bypass valve 47, and the gas turbine bypass valve 53 are closed, and the fuel gas is not guided from the main system line 15 to the bypass line 33.
On the other hand, nitrogen gas is continuously supplied from the first nitrogen input line 37, the second nitrogen input line 49 and the third nitrogen input line 55. First, the processing gas control valve 41 is closed, and the pressure in the bypass line 33 is increased to a pressure of about 3 MPa in the main system line 15. Thereafter, the opening / closing amount of the processing gas control valve 41 is controlled by a pressure sensor 43 that measures the pressure in the bypass line 33, and is constantly adjusted to be substantially equal to the pressure of the main system line 15. That is, the nitrogen gas flows from the processing gas control valve 41 to the flare stack 39 almost always.

  As described above, the dust remover bypass valve 35, the gas purification bypass valve 47, and the gas turbine bypass valve 53 are closed, but fuel inevitably leaks from the main system line 15. The leaked fuel gas is sent to the flare stack 39 through the bypass line 33 by the nitrogen gas constantly supplied from the first nitrogen input line 37, the second nitrogen input line 49, and the third nitrogen input line 55, and incinerated. Processed and released into the atmosphere.

As described above, the fuel gas that leaks from the main system line 15 side during normal operation together with the fuel gas that flows into the bypass line 33 and the like from the main system line 15 side during the start-up is the first nitrogen input line 37, Since the nitrogen gas supplied from the second nitrogen charging line 49 or the third nitrogen charging line 55 is sent to the flare stack 39 and burned, the fuel gas does not stay in the bypass line.
For this reason, the fuel gas is cooled and no condensation occurs and corrosive substances such as sulfuric acid are not generated. Therefore, the bypass line 33 on the downstream side of the dust removing device bypass valve 35, the gas purification bypass valve 47 and the gas turbine bypass valve 53, the first Corrosion generation at the branch line 45 and the second branch line 51 can be effectively prevented.

  Further, as a countermeasure against corrosion of the long bypass line 33, the first branch line 45 and the second branch line 51 on the downstream side of the dust removing device bypass valve 35, the gas purification bypass valve 47 and the gas turbine bypass valve 53, no condensation is caused. Since a means for heating or forming them with an expensive corrosion-resistant material becomes unnecessary, the coal gasification combined power generation device 1 can be manufactured at low cost.

Next, when the coal gasification combined power generation device 1 is stopped, the gas turbine bypass valve 53 is opened. Even in this case, since the pressures of the main system line 15 and the bypass line 33 are balanced, the fuel gas does not explode into the bypass line 33 explosively. Therefore, the processing gas control valve 41 is then opened. As a result, nitrogen gas in the bypass line 33 is released from the flare stack 39, and the pressure in the bypass line 33 decreases, and accordingly, the combustion gas in the main system line 15 passes through the second branch line 51 to the bypass line 33. It flows in, is incinerated by the flare stack 39, and is released into the atmosphere.
Thereby, the main system | strain line 15 is pressure-reduced and each apparatus can be stopped.
Although only the gas turbine bypass valve 53 is opened here, the dust removing device bypass valve 35 or the gas purification bypass valve 47 may be opened, or a plurality of these may be opened simultaneously.

Further, for example, in an emergency such as a gas leak in the coal gasification furnace 3, the dust removal device inlet valve 23 is closed and the dust removal device bypass valve 35 is opened. Even in this case, since the pressures of the main system line 15 and the bypass line 33 are balanced, the fuel gas does not explode into the bypass line 33 explosively. For this reason, the process gas control valve 41 is simultaneously opened. As a result, nitrogen gas in the bypass line 33 is released from the flare stack 39 and the pressure in the bypass line 33 decreases, and accordingly, the combustion gas from the coal gasifier 3 passes through the dust removal device bypass valve 35 and bypass line 33. And is incinerated by the flare stack 39 and released into the atmosphere.
Thereby, since the coal gasification furnace 3 is pressure-reduced, the coal gasification furnace 3 can be stopped and inspected.
When an abnormality occurs in the dust removal device 5, the gas purification bypass valve 47 is opened to decompress the dust removal device 5, and when an abnormality occurs in the gas purification device 7, the gas turbine bypass valve 53 is opened. What is necessary is just to open an optimal valve by the place where abnormality occurred.

  Thus, during normal operation, nitrogen gas is always supplied from the first nitrogen input line 37, the second nitrogen input line 49, and the third nitrogen input line 55, and the bypass line 33 and the first branch line are supplied by the processing gas control valve 41. 45 and the pressure in the second branch line 51 are maintained to be equal to the pressure in the main system line 15, so that any one of the dust removing device bypass valve 35, the gas purification bypass valve 47, and the gas turbine bypass valve 53 is used. Even if it is opened, the fuel gas does not explode explosively from the main system line 15 toward the bypass line 33, for example, at an extremely high speed such as sound speed.

For this reason, the dust removal device bypass valve 35, the gas purification bypass valve 47, and the gas turbine bypass valve 53 are opened without considering damage to the bypass line 33, the first branch line 45, and the second branch line 51 during operation. Can do.
For this reason, in an emergency or when the operation is stopped, the dust removing device bypass valve 35, the gas purification bypass valve 47, and the gas turbine bypass valve 53 can be immediately opened to reduce the pressure in the equipment in the main system line.

It is a block diagram which shows schematic structure of the coal gasification combined cycle power generation apparatus which concerns on one Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Coal gasification combined cycle power generation device 3 Coal gasification furnace 5 Dust removal device 7 Gas purification device 11 Gas turbine 15 Main system line 33 Bypass line 35 Dust removal device bypass valve 37 First nitrogen input line 39 Flare stack 41 Process gas control valve 45 One branch line 47 Gas purification bypass valve 49 Second nitrogen input line 51 Second branch line 53 Gas turbine bypass valve 55 Third nitrogen input line

Claims (6)

A coal gasifier that gasifies coal to produce fuel gas;
A dust removing device for removing solids in the fuel gas;
A gas refining device for removing sulfides in the fuel gas and supplying the fuel gas to the gas turbine; and
A main system line for connecting the coal gasifier, the dust removal device, the gas purification device, the gas turbine, and the like;
In a coal gasification plant comprising a bypass line connecting an outlet side of the coal gasification furnace in the main system line and a gas processing facility,
A bypass valve that is provided upstream of the bypass line and opens and closes the bypass line;
A processing gas regulating valve provided at a downstream portion of the bypass line and performing flow rate regulation;
A first inert gas input line that is provided downstream of the bypass valve and supplies an inert gas to the bypass line;
A coal gasification plant characterized by comprising: A first branch line connecting the dust removal device and the gas purification device in the main system line, and the bypass line;
A first branch bypass valve provided in the first branch line;
A second inert gas input line provided downstream of the first branch bypass valve;
The coal gasification plant according to claim 1, wherein the coal gasification plant is provided. A second branch line connecting the outlet of the gas purifier in the main system line and the bypass line;
A second branch bypass valve provided in the second branch line;
A third inert gas input line provided downstream of the second branch bypass valve;
The coal gasification plant according to claim 1, wherein the coal gasification plant is provided. Method of operating a coal gasification plant that generates fuel gas from coal by a coal gasification furnace, removes solids from the fuel gas by a dust removal device, and then desulfurizes the gas by a gas purification device and supplies the gas turbine as fuel In
At the time of start-up, after closing the bypass valve provided in the bypass line, the fuel gas flowing into a bypass line branched from an outlet portion of the coal gasification furnace and connected to a gas processing facility is bypassed. The exhaust gas is discharged from the bypass line by an inert gas supplied to the downstream side of the gas, and the pressure in the bypass line is maintained at substantially the same level as the pressure of the fuel gas by the inert gas during normal operation. The operation method of the coal gasification plant. After starting, after closing the first branch valve provided in the first branch line, the fuel gas flowing into the first branch line branched from the outlet of the dust removing device and connected to the bypass line The exhaust gas is discharged from the first branch line and the bypass line by an inert gas downstream of the first branch valve, and the pressure in the first branch line and the bypass line by the inert gas during normal operation. Is maintained at substantially the same level as the pressure of the fuel gas, the method of operating a coal gasification plant according to claim 4. Upon startup, the fuel gas branched from the outlet of the gas purifier and introduced into the second branch line connected to the bypass line was closed, and the second branch valve provided in the second branch line was closed Thereafter, the inert gas supplied to the downstream side of the second branch valve is discharged from the second branch line and the bypass line, and during normal operation, the inert gas supplies the inside of the second branch line and the bypass. 6. The method for operating a coal gasification plant according to claim 4, wherein the pressure in the line is maintained at substantially the same level as the pressure of the fuel gas.

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