JP5211795B2 - Purge method and apparatus for emergency stop of gasification equipment - Google Patents

Description

  The present invention relates to a purge method and apparatus for emergency stop of gasification equipment that can be purged safely and inexpensively at the time of emergency stop in gasification equipment.

  FIG. 3 shows an example of a conventional gasification facility. This gasification facility is a circulating fluidized bed gasification facility called a two-column type comprising a gasification furnace 1 (fluidized bed gasification furnace) and a combustion furnace 8. Shows the case. There exists patent document 1 as a prior art document of such a circulating fluidized bed gasification equipment.

  A gasification furnace 1 (fluidized bed gasification furnace) constituting the gasification facility of FIG. 3 forms a fluidized bed 4 of a fluidized medium (eg, sand, limestone, etc.) with water vapor 3 supplied from a lower diffuser 2. The raw material 5 (coal, biomass, tire chips, etc.) charged from the top is gasified to produce gasified gas and combustible solids (char), and the char and fluid medium generated in the gasification furnace 1 The mixture 6 is introduced into a combustion furnace 8 constituting a gasification facility through an introduction pipe 7.

  A combustion furnace 8 constituting a gasification facility is supplied with a flow gas 10 such as air or oxygen from the lower part of an air diffuser 9 to form a fluidized bed, thereby burning and circulating the char from the introduction pipe 7. The medium is heated, and the flue gas 12 led out from the upper part of the combustion furnace 8 by the flow through the flue gas pipe 11 is introduced into a medium separator 13 such as a hot cyclone to be turned into the fluid medium 14 and the flue gas 15. The separated fluid medium 14 is supplied to the gasification furnace 1 through the downcomer 16, and the exhaust gas 15 from which the fluid medium 14 is separated by the medium separator 13 is an induction fan 11a. And is discharged from the chimney 11b.

  The gasification furnace 1 is provided with a mechanism for blocking gas movement with the combustion furnace 8.

  The gasification gas 18 generated in the gasification furnace 1 (fluidized bed gasification furnace) is taken out by a lead-out pipe 19 and separated into solids by, for example, a solid separation device (not shown), and then led to the spray tower 20. ing. In the spray tower 20, water vapor (and tar, fine powder, etc.) in the gasification gas 18 is removed by spraying water W by the spray 21 and cooling, and the gasification gas 18 from which the water vapor and the like have been removed is attracted. It is led to a downstream device 23 having a fan 22. The gasified gas 18 attracted by the attracting fan 22 of the downstream device 23 is guided to the gas purifying device 24 to purify the gasified gas.

  Here, in the gasification equipment provided with the spray tower 20 as described above, the gasification gas 18 is cooled to about 90 ° C. or lower, which is generally lower than the condensation temperature of water vapor, by spraying water W in the spray tower 20. Yes. This is because the heat resistance temperature of the induction fan 22 in the downstream device 23 installed downstream of the spray tower 20 is particularly low, so that the induction fan 22 is protected by cooling the gasification gas 18 to a low temperature.

  During normal operation in the gasification facility as described above, the fluidized bed 4 is formed by the water vapor 3 in the gasification furnace 1, and when the raw material 5 such as coal, biomass, tire chips, etc. is input thereto, the raw material 5 is Gasified by steam gasification, gasified gas 18 and combustible solids (char) are generated, and char generated in the gasification furnace 1 is introduced into the combustion furnace 8 from the introduction pipe 7 as a mixture 6 together with the fluidized medium. Then, fluid combustion is performed by the fluid gas 10 supplied from the lower part of the combustion furnace 8, and the combustion exhaust gas 12 from the combustion furnace 8 is introduced into a medium separator 13 such as a hot cyclone through the exhaust gas pipe 11, In the medium separator 13, the fluid medium 14 is separated from the combustion exhaust gas 12, and the separated fluid medium 14 is returned to the gasifier 1 through the downcomer 16 and circulated. .

As described above, the fluid medium is heated to a high temperature by char combustion in the combustion furnace 8 and separated by the medium separator 13, and the high temperature fluid medium 14 is supplied to the gasifier 1 through the downcomer 16. Thus, the inside of the gasification furnace 1 is maintained at a high temperature suitable for gasification. Therefore, in the gasification furnace 1, the gas generated by thermal decomposition of the supplied raw material 5 and the residual raw material react with water vapor. As a result, a water gasification reaction [C + H ₂ O = H ₂ + CO] or a hydrogen conversion reaction [CO + H ₂ O = H ₂ + CO ₂ ] occurs, and a combustible gasification gas such as H ₂ or CO is generated.

  The gasification gas 18 generated in the gasification furnace 1 is taken out by a lead-out pipe 19 and solid content is separated by a solid separation device (not shown), for example, and then guided to a spray tower 20 and water W is injected by a spray 21. Thus, the water vapor (and tar, fine powder, etc.) in the gasified gas 18 is removed. The gasified gas 18 from which water vapor or the like has been removed is supplied to a downstream device 23 having an induction fan 22 and a gas purification device 24.

  Incidentally, when heat is insufficient during normal operation in the gasification facility, that is, when sufficient heat for gasification of the raw material 5 cannot be obtained in the gasification furnace 1, a virtual line in FIG. As shown, auxiliary fuel 5a such as coal, biomass, tire chips, etc., which is the same as the raw material supplied to the gasification furnace 1 is auxiliaryly introduced into the combustion furnace 8 to burn and compensate for the lack of heat. ing. In addition, during the preheating operation in the previous stage before the normal operation in the gasification facility, the raw material is not charged into the gasification furnace 1, and the coal, biomass, and tire chips are shown as indicated by phantom lines. Auxiliary fuel 5a such as the above is injected into the combustion furnace 8 for preheating and combusted, and the fluidized medium that has become hot as the auxiliary fuel 5a burns in the combustion furnace 8 passes through the exhaust gas pipe 11 together with the combustion exhaust gas 12. By being separated by the medium separation device 13 and supplied to the gasification furnace 1 through the downcomer 16, circulation preheating of the gasification equipment is performed.

  In the gasification facility of FIG. 3, when the temperature of the combustion furnace 8 falls below a set temperature for some reason, combustion cannot be continued, so that a large amount of unburned fuel accumulates in the combustion furnace 8. Will end up.

  Further, in the gasification facility provided with the spray tower 20 as shown in FIG. 3, when the spray tower 20 trips for some reason, the high-temperature gasification gas 18 is introduced into the downstream device 23, thereby This causes a problem that the attracting fan 22 burns out.

  Therefore, in order to avoid such an unfavorable state, in the conventional gasification equipment, when the temperature of the combustion furnace 8 falls below the set temperature or when the spray tower 20 trips, A system fuel emergency shutoff (MFT: Master Fuel Trip) is operated to stop the gasification facility in an emergency.

  As described above, when the gasification facility is urgently stopped, the gasification furnace 1 and the outlet pipe 19 are filled with the highly combustible gasification gas 18. When air from the outside is mixed with the gas 18, there is a possibility of causing rapid combustion. Therefore, it is necessary to purge the inside of the gasification furnace 1 and the inside of the outlet pipe 19 with a nonflammable inert gas, The downstream device 23 needs to perform a purge to be replaced with a non-flammable inert gas and maintain the induction fan 22 at a low temperature that does not cause burning.

Conventionally, when purging a gasification facility as shown in FIG. 3, the gasification furnace 1 is generally supplied by supplying an inert gas such as nitrogen (N ₂ ) or argon (Ar) to the gasification furnace 1. And the downstream apparatus 23 was purged with an inert gas.

However, in order to purge the gasification equipment, in general, an inert gas (N ₂ ) of about 5 times the volume of the gasification furnace 1 is required, and thus a large amount of inert gas is required. A large-sized inert gas production apparatus is required, and there is a problem that the cost for purging is greatly increased.

Further, as described above, in the method of purging the gasification furnace 1 with the inert gas (N ₂ ), when the spray tower 20 trips, the high-temperature gasification gas 18 is introduced into the downstream device 23. Therefore, there is a problem that the attracting fan 22 is burned out.

On the other hand, Patent Document 2 discloses an operation method in which the gas in the apparatus is purged with water vapor when the partial gasification / decomposition apparatus is started and stopped.
JP 2005-041959 A Japanese Patent No. 3881712

  However, when purging at the time of emergency stop of the gasification facility shown in FIG. 3 using the water vapor purging method disclosed in Patent Document 2, the fluidized bed 4 of the gasification furnace 1 is fluidized and purged. In order to supply high-temperature and high-pressure steam for this purpose, even if such an attempt is made to supply such high-temperature and high-pressure steam with an auxiliary boiler, the auxiliary boiler generates high-temperature and high-pressure steam that can fluidize the fluidized bed 4 after starting. Since it takes a long time to produce the gas, there is a problem that it cannot be purged when the gasification facility is stopped in an emergency.

  Even if the supply of water vapor becomes possible, if the spray tower 20 trips, the problem is that the high-temperature gasification gas 18 and water vapor are introduced into the downstream device 23 and the induction fan 22 is burned out. is there.

  The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a purging method and apparatus at the time of emergency stop of gasification equipment that can be purged safely and inexpensively at the time of emergency stop in gasification equipment. is there.

The present invention supplies a raw material and a gasifying agent to a gasification furnace to perform gasification of the raw material. A purge method at the time of emergency stop of gasification equipment that is led to a downstream device,
An emergency shutoff valve is provided at the outlet pipe at the outlet of the spray tower, a flare stack is provided through the emergency shutoff valve in the outlet pipe upstream from the emergency shutoff valve,
During an emergency stop, shut off the spray tower outlet with an emergency shut-off valve and stop the spray tower operation,
Steam is supplied upstream from the emergency shut-off valve, gasified gas upstream from the emergency shut-off valve is released, the emergency shut-off valve is opened and discharged to the flare stack, and the upstream from the emergency shut-off valve is purged with water vapor. ,
The present invention relates to a purge method at the time of emergency stop of gasification equipment, wherein an inert gas is supplied to a downstream outlet of the emergency shutoff valve, and a downstream device is purged with the inert gas.

  In the purge method at the time of emergency stop of the gasification facility, it is preferable that the steam is steam generated by an exhaust heat recovery boiler provided in the gasification facility.

The present invention supplies a raw material and a gasifying agent to a gasification furnace to perform gasification of the raw material, guides the gasification gas generated in the gasification furnace to a spray tower by a lead-out pipe, cools, and then includes an induction fan A purge device for emergency stop of gasification equipment that is led to a downstream device,
An emergency shut-off valve in the outlet pipe at the outlet of the spray tower;
A flare stack that escapes to the outlet pipe upstream from the emergency shutoff valve and is connected via the emergency shutoff valve;
Water vapor supply means for supplying water vapor to at least the gasification furnace;
An inert gas supply means connected to the outlet pipe at the downstream outlet of the emergency shutoff valve;
The purging apparatus at the time of emergency stop of the gasification facility characterized by having.

  In the purge method at the time of emergency stop of the gasification facility, it is preferable that the steam supply means is an exhaust heat recovery boiler provided in the gasification facility.

  According to the purge method and apparatus at the time of emergency stop of the gasification facility of the present invention, at the time of emergency stop, the outlet of the spray tower is shut off by the emergency shut-off valve and the operation of the spray tower is stopped, and the upstream position from the emergency shut-off valve is set. Supplies steam and releases the gasification gas upstream from the emergency shut-off valve, opens the emergency shut-off valve and discharges it to the flare stack, purges the upstream from the emergency shut-off valve with water vapor, and discharges it to the outlet of the shut-off valve. Since the downstream device is purged with the inert gas by supplying the active gas, the gasification gas upstream of the emergency shutoff valve can be purged safely and quickly with water vapor, and the outlet of the emergency shutoff valve By purging the downstream device with an inert gas and purging the downstream device with the inert gas, the downstream device is safely purged with a small amount of inert gas without introducing a high-temperature gas. It can be an excellent effect that the door can be.

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

  FIG. 1 shows an example of the purging apparatus at the time of emergency stop of the present invention applied to the gasification furnace of FIG. 3, and the same components as those in FIG. Only the characteristic part will be described.

  In the purge apparatus shown in FIG. 1, an emergency shutoff valve 50 is installed in the outlet pipe 19 at the outlet of the spray tower 20. Further, a flare stack 52 is connected to the outlet position of the gasification furnace 1 in the outlet pipe 19 upstream from the emergency shutoff valve 50 via a relief emergency shutoff valve 51.

  Further, the exhaust pipe 19 and the exhaust gas pipe 11 are provided with an exhaust heat recovery boiler 55 in which heat exchangers 53 and 54 are arranged, respectively, and water W from the pump 56 is sequentially led to the heat exchangers 53 and 54. The steam 57 is generated and supplied to the lower part of the diffuser 2 of the gasifier 1 through the steam pipe 58, and the steam 57 is supplied through the steam pipe 60 having the steam shut-off valve 59. Water vapor supply means 61 is provided to supply the spray tower 20. The water vapor 57 supplied to the gasification furnace 1 by the water vapor pipe 58 can be supplied as a gasifying agent when the gasification furnace 1 gasifies the raw material 5, and is also used for purging at an emergency stop. Can be supplied to the gasifier 1. On the other hand, in the case of a gasification furnace in which another gasifying agent 62 such as air or carbon dioxide is supplied to the gasification furnace 1 to perform gasification, the water vapor pipe 58 is provided with a water vapor shut-off valve 63 for emergency. When stopping, the supply of the gasifying agent 62 is stopped, and the water vapor shutoff valve 63 is opened to supply the water vapor 57 from the water vapor pipe 58 to the gasifier 1.

  Further, the outlet pipe 19 at the outlet of the emergency shut-off valve 50 is provided with an inert gas supply means 66 for supplying an inert gas 65 via an inert gas shut-off valve 64.

  Further, in order to allow the upstream of the downstream device 23 to be purged even when the downstream device 23 is tripped, a downstream device shutoff valve 67 is provided in the outlet pipe 19 at the inlet of the downstream device 23 as indicated by a virtual line. The flare stack 69 is connected to the outlet pipe 19 at the inlet of the downstream device shutoff valve 67 through the emergency shutoff valve 68. The flare stack 69 can also be used as the flare stack 52.

  Next, the operation of the embodiment of FIG. 1 will be described.

  When the gasification facility of FIG. 1 is operated, it is operated in the same manner as the gasification facility of FIG. 3 to generate the gasification gas 18. If the gasification facility is urgently stopped from this operation state, Supply of the raw material 5 to the furnace 1 is interrupted. At the same time, the emergency shut-off valve 50 at the outlet of the spray tower 20 is closed and the operation of the spray tower 20 is stopped. At this time, the flow gas 10 (air) is supplied to the combustion furnace 8, and the combustion of the char and the circulation of the circulation medium are continued.

  In this state, the water vapor 57 from the water vapor supply means 61 is supplied to the lower part of the gasification furnace 1 through the water vapor pipe 58, and the water vapor shut-off valve 59 is opened to supply the water vapor 57 from the water vapor supply means 61 through the water vapor pipe 60 to the spray tower. 20 is supplied. At this time, when gasification in the gasification furnace 1 is performed by the steam 57 from the steam pipe 58, the supply of the steam 57 to the gasification furnace 1 is continued even during an emergency stop. When gasification is performed by supplying the gasifying agent 62 to the gasification furnace 1, the supply of the other gasifying agents 62 is stopped, and the water vapor shut-off valve 63 is opened to supply the water vapor 57 from the water vapor pipe 58. The gasification furnace 1 is supplied.

  Further, the downstream device 23 is purged with the inert gas 65 by opening the inert gas cutoff valve 64 to supply the inert gas 65 from the inert gas supply means 66 to the outlet of the emergency cutoff valve 50. .

  As described above, when the water vapor 57 from the water vapor supply means 61 is supplied to the gasification furnace 1 by the water vapor pipe 58, the raw material remaining in the gasification furnace 1 is gasified by the water vapor 57, and the generated gasification gas Is discharged from the emergency shut-off valve 51 to the flare stack 52 and burned. Since the raw material in the gasification furnace 1 is reduced by gasification and is reduced by being introduced into the combustion furnace 8 as char, the generation of gasification gas is reduced. It becomes purged.

  Further, the steam 57 supplied to the spray tower 20 by the steam pipe 60 flows back through the outlet pipe 19 toward the gasification furnace 1, and the gasified gas in the outlet pipe 19 is discharged to the flare stack 52. The outlet pipe 19 upstream of the column 20 is purged with water vapor 57. As a result, the gasification gas system composed of the outlet pipe 19 in the gasification furnace 1 and upstream of the spray tower 20 is purged with the steam 57.

  Note that the combustion furnace 8 continues to operate even during the emergency stop, and the combustion furnace 8 has a high residual heat, so that the exhaust gas 15 led out from the exhaust pipe 11 has a high temperature. Water vapor 57 sufficient to fluidize and purge the fluidized bed 4 of the gasification furnace 1 can be supplied from the supply means 61.

  If sufficient purging with water vapor due to the residual heat of the combustor 8 cannot be performed, by supplying auxiliary fuel 5a (see FIG. 3), water vapor 57 sufficient for purging can be supplied.

  Thus, since the gasified gas 18 upstream of the emergency shutoff valve 50 is discharged to the flare stack 52 by the steam 57 and replaced with the steam 57, the outlet pipe 19 and the gas upstream of the emergency shutoff valve 50 are used. The gasification gas system of the chemical reactor 1 can be purged safely and quickly.

  Further, since the inert gas 65 from the inert gas supply means 66 is supplied to the outlet of the emergency shut-off valve 50 and the downstream device 23 is purged with the inert gas 65, a high-temperature gas is guided to the downstream device 23. Therefore, the purge can be performed safely and with a small amount of the inert gas 65 used.

  Further, as indicated by phantom lines in FIG. 1, a downstream device shutoff valve 67 is provided in the outlet pipe 19 at the inlet of the downstream device 23, and escapes to the outlet pipe 19 at the inlet of the downstream device shutoff valve 67 via an emergency shutoff valve 68. When the flare stack 69 is connected, the upstream gasification gas system of the downstream device 23 can be purged with an inert gas even when the downstream device 23 trips.

  FIG. 2 shows another example of the present invention, in which a flare stack 71 is connected between the spray tower 20 which is an inlet of the emergency shut-off valve 50 and the emergency shut-off valve 50 via a relief emergency shut-off valve 70. The steam 57 from the steam supply means 61 is supplied only to the gasifier 1 through the steam pipe 58. Other configurations are the same as those in FIG.

  In the configuration of FIG. 2, when the gasification facility is urgently stopped from the operation state, the supply of the raw material 5 to the gasification furnace 1 is shut off. At the same time, the emergency shut-off valve 50 at the outlet of the spray tower 20 is closed and the operation of the spray tower 20 is stopped. At this time, flowing gas 10 (air) is supplied to the combustion furnace 8, and char combustion and circulation of the circulation medium are performed.

  In this state, when the water vapor 57 from the water vapor supply means 61 is supplied to the lower part of the gasification furnace 1 through the water vapor pipe 58, the raw material remaining in the gasification furnace 1 is gasified by the water vapor 57, and the generated gasification gas is It is led to the spray tower by the lead-out pipe 19 and further discharged from the emergency shut-off valve 70 to the flare stack 71 and burned. Since the raw material in the gasification furnace 1 is reduced by gasification and reduced by being introduced into the combustion furnace 8 as char, the generation of gasification gas is reduced, thereby reducing the gasification furnace 1 and the spray tower 20. The gasification gas system composed of the outlet pipe 19 on the upstream side is purged with the water vapor 57.

  When the spray tower 20 is tripped, the operation for stopping the spray tower 20 is eliminated, and the purge can be performed in exactly the same manner as described above.

  In addition, this invention is not limited only to the said form, Of course, a various change can be added in the range which does not deviate from the summary of this invention.

It is a schematic block diagram which shows an example of the purge apparatus at the time of emergency stop of this invention. It is a schematic block diagram which shows the other example of the purge apparatus at the time of the emergency stop of this invention. It is a schematic block diagram which shows an example of the conventional gasification installation.

Explanation of symbols

1 Gasification furnace (fluidized bed gasification furnace)
DESCRIPTION OF SYMBOLS 5 Raw material 8 Combustion furnace 18 Gasification gas 19 Outlet pipe 20 Spray tower 22 Induction fan 23 Downstream apparatus 50 Emergency shut-off valve 51 Escape emergency shut-off valve 52 Flare stack 55 Waste heat recovery boiler 57 Water vapor 61 Steam supply means 66 Inert gas supply means 70 Escape emergency shut-off valve 71 Flare stack

Claims (4)

The raw material and gasifying agent are supplied to the gasification furnace to gasify the raw material, the gasified gas generated in the gasification furnace is cooled by guiding it to the spray tower through the outlet pipe, It is a purge method at the time of emergency stop of gasification equipment that is to be guided,
An emergency shutoff valve is provided at the outlet pipe at the outlet of the spray tower, a flare stack is provided through the emergency shutoff valve in the outlet pipe upstream from the emergency shutoff valve,
During an emergency stop, shut off the spray tower outlet with an emergency shut-off valve and stop the spray tower operation,
Steam is supplied upstream from the emergency shut-off valve, gasified gas upstream from the emergency shut-off valve is released, the emergency shut-off valve is opened and discharged to the flare stack, and the upstream from the emergency shut-off valve is purged with water vapor. ,
An inert gas is supplied to the downstream outlet of the emergency shut-off valve, and the downstream device is purged with the inert gas.   The purging method at the time of emergency stop of gasification equipment according to claim 1, wherein the steam is steam generated by an exhaust heat recovery boiler provided in the gasification equipment. The raw material and gasifying agent are supplied to the gasification furnace to gasify the raw material, the gasified gas generated in the gasification furnace is cooled by guiding it to the spray tower through the outlet pipe, It is a purge device at the time of emergency stop of gasification equipment to be guided,
An emergency shut-off valve in the outlet pipe at the outlet of the spray tower;
A flare stack that escapes to the outlet pipe upstream from the emergency shutoff valve and is connected via the emergency shutoff valve;
Water vapor supply means for supplying water vapor to at least the gasification furnace;
An inert gas supply means connected to the outlet pipe at the downstream outlet of the emergency shutoff valve;
A purge apparatus for emergency stop of gasification equipment, comprising:   The purge apparatus for emergency stop of gasification equipment according to claim 3, wherein the steam supply means is an exhaust heat recovery boiler provided in the gasification equipment.

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