JP5787742B2 - Filter element playback method - Google Patents

Description

  The present invention relates to a gasification apparatus including a gasification furnace for gasifying carbon-based fine powder raw materials such as pulverized coal, and more specifically, a filter for filtering and collecting and collecting char contained in generated gas. The present invention relates to a filter element regeneration method for an apparatus.

A coal gasification apparatus that gasifies pulverized coal, which is one of carbon-based pulverized raw materials, is widely known as described in Patent Document 1, for example. According to this, in the gasification furnace, the temperature obtained by oxidizing a part of the pulverized raw materials such as pulverized coal and char becomes high temperature, and the remaining fine pulverized raw material is heated to carbon monoxide CO and hydrogen H _2. The product gas is decomposed or converted into a main product. After the product gas is recovered by the heat recovery boiler, the char in the product gas is collected by the cyclone, and the fine char that could not be collected by the cyclone is collected by the char filter. Supply to the place of use. This prevents troubles in the downstream device due to char. The collected char is collected in a hopper, and is again put into the gasification furnace from the hopper through a char transport pipe. In addition to pulverized coal, Patent Document 2 discloses a technique for gasifying organic waste.

  The char filter is provided with a cylindrical filter element having pores, and the produced gas is vented from the outer surface side to the inner surface side of the cylindrical filter element, and char contained in the produced gas is collected by the filtration surface on the outer surface side. To do. Then, in accordance with the period or the filter differential pressure, the backwash gas is pulsated from the inner surface side of the filter element so that the char collected on the outer surface side is removed and recovered.

  In this way, the collected char is removed from the filter element by backwashing, but the char that cannot be removed by backwashing forms a permanent layer while collecting and backwashing repeatedly. The remaining filter differential pressure gradually increases.

  As described above, Patent Document 3 proposes a method of regenerating a filter element in which the filter differential pressure is not recovered even when backwashing is repeated. According to this, a gas adjusted to an oxygen concentration of 5 to 15 Vol% under normal pressure is supplied to the char filter while adjusting the flow rate, and the filter element is heated in the gas at 400 to 450 ° C. The char can be removed by oxidation.

JP 2003-336080 A JP 2006-241229 A JP 2006-192337 A

  The filter element regeneration method described in Patent Literature 3 can promote the oxidation reaction (combustion) of char by increasing the heating temperature. However, when the heating temperature is increased, there is a problem that even if the filter container is made of heat-resistant steel, there is a problem that the filter container is distorted due to the thermal effect, which may shorten the life of the filter device. Therefore, since the heating temperature is limited, it may take a long time (for example, several days) for char to completely burn. Further, ancillary facilities such as a heating device for heating the filter element, a temperature control device, and a device for generating a gas with adjusted oxygen concentration and flow rate are required.

On the other hand, it is conceivable that the filter element is back-washed and the permanent layer is simply washed off before the gasification furnace is operated or after the operation is completed, with the aeration of the product gas stopped. However, in general the product gas from it contained sulfur in the coal, this sulfur by corrosion not a little inner side of the container wall of the filter container is exposed to the product gas, corrosives (FeS) is generated The Therefore, if the filter element is backwashed with the aeration of the product gas stopped, the corroded material may peel off from the container wall and enter the filtration section on the inner surface side of the filter element along with the backwash gas, causing clogging. There is. When the filtration part on the inner surface side of the filter element is clogged, there is a problem that the removal by backwashing is hindered.

  The problem to be solved by the present invention is that the adhering char of the filter element that could not be removed by backwashing during gasification operation can be removed by backwashing, and the corroded material on the container wall in which the filter element is accommodated Accordingly, it is an object of the present invention to provide a filter element regeneration method capable of avoiding clogging of the filtration part on the inner surface side of the filter element.

  In order to solve the above-mentioned problems, the filter element regeneration method of the present invention includes a product gas discharged from a gasification furnace for gasifying a carbon-based fine powder material through a filter element having pores and included in the product gas. In the filter element regeneration method of the filter device for collecting the collected char, backwashing the filter element with backwashing gas, and collecting the collected char, the gasification operation including when the gasification furnace is started Before regeneration or after completion of the gasification operation, the regeneration is supplied to the filter device with a regeneration gas having a concentration of char and soot lower than the concentration of char and soot contained in the product gas and vented to the filter element. While maintaining the gas speed below the rated filtration rate of the filter element, backwash with the backwash gas and attach to the filter element. It characterized in that it played to remove the char.

  According to the present invention, since the filter element is back-washed before or after the gasification operation is started including the start of the gasification furnace, there is no adhesion of new char and dust, and the gasification operation is not performed. The attached char and dust of the filter element that could not be removed by backwashing can be efficiently removed. In particular, since the filter device is backwashed while supplying a regeneration gas having a low char and dust concentration, the flow of the regeneration gas is directed from the outer surface side to the inner surface side of the filter element, so that the filter element is accommodated. Even if the corroded material on the wall of the filter container is peeled off, it is not accompanied by the backwash gas, so that it is possible to avoid clogging due to entering the filtration part on the inner surface side of the filter element. Therefore, even if pulverized coal, which is a carbon-based pulverized raw material containing sulfur, is gasified and the inner wall of the filter container containing the filter element corrodes with sulfur, and FeS is generated, the FeS remains on the inner surface side of the filter element. It is possible to prevent the pressure loss of the filter element from increasing by clogging the filtration part. In particular, by keeping the speed of the regeneration gas that passes through the filter element at or below the rated filtration speed of the filter element, for example, 45% or less, preferably 1/3 or less, the effect of removing by backwashing can be enhanced.

  In the present invention, as the regeneration gas, a purge gas such as nitrogen gas, which is an inert gas for purging the system, can be used before the gasification operation of the gasification apparatus including the gasification furnace starts or after the gasification operation ends. . Further, as the regeneration gas, the combustion exhaust gas of the startup fuel in the process of raising the temperature and increasing the pressure of the gasifier using the startup fuel can be used. Further, a warm-up gas that raises and raises the pressure of the gasification furnace and the filter device can be used as the regeneration gas. Furthermore, as the regeneration gas, a product gas at a stage where the internal pressures of the gasification furnace and the filter device are adjusted to be the same can be used. Furthermore, as the regeneration gas, an inert gas such as nitrogen gas used for adjusting the internal pressure of the filter device to the same pressure as that of the gasifier system can be used. According to these methods, since it is not necessary to newly provide a special incidental facility to generate the regeneration gas, the configuration of the apparatus for carrying out the filter element regeneration method of the present invention can be simplified.

  According to the filter element regeneration method of the present invention, the adhered char of the filter element that could not be removed by backwashing during gasification operation can be removed by backwashing, and the corrosion of the container wall in which the filter element is accommodated An object can be prevented from entering the filtration part on the inner surface side of the filter element.

It is a figure which shows the whole structure of the coal gasifier of one Embodiment provided with the char filter to which this invention is applied. It is a figure which shows the structure of one Embodiment of the char filter of FIG. It is a figure which shows an example of the change of filter differential pressure (DELTA) P at the time of dust collection of a char filter apparatus at the time of gasification operation, and backwashing. It is a figure explaining the mechanism of char collection and backwashing of the char filter to which the present invention is applied. It is a figure explaining the backwashing operation | movement at the time of gasification operation | movement, and the backwashing operation | movement under the conditions without a low filtration rate and dust which used the purge gas before and behind gasification operation. It is a figure which shows the relationship between the gasifier load and the removal rate of the permanent layer adhering to the element. The cross-sectional view of a main portion of the char filter for explaining the reproducing method of the filter Jer main cement of the present invention. FIG. It is a figure which shows the data of the confirmation test of the relationship between the loss coefficient K with respect to gasifier load, and recovery differential pressure (DELTA) P.

  In FIG. 1, the whole structure of the coal gasifier of one Embodiment provided with the filter apparatus of this invention is shown. As shown in the figure, the coal gasifier of the present embodiment includes a gasification furnace 1 for gasifying pulverized coal, a heat recovery boiler 2 for recovering the heat of the generated gas, and a cyclone 3 for collecting char in the generated gas. The char filter 4 is a filter device that collects fine char that has not been collected by the cyclone 3.

A plurality of gasification burners 7 and char burners 8 are installed in the gasification furnace 1 as necessary. Although not shown in the figure, the pulverized raw material such as pulverized coal and char is conveyed to the gasification burner 7 and the char burner 8 by an inert gas such as nitrogen. In addition, the oxidizer is conveyed to the gasification burner 7 and the char burner 8 separately from the pulverized coal and char and other pulverized raw materials, and the pulverized raw material and the oxidant are separately ejected from these burners, and the gasification furnace. In 1, the fine powder material and the oxidizing agent are mixed. The gasification furnace 1 is a product gas mainly composed of carbon monoxide CO and hydrogen H ₂ under a high temperature due to oxidation heat of a part of the fine powder raw material supplied to the gasification burner 7 and the char burner 8. 9 is gasified. On the other hand, the residue of the fine powder raw material is melted by the oxidation heat of the gasification burner 7 and the char burner 8 and falls into the cooling water pool 10 at the bottom of the gasification furnace 1, rapidly cooled, solidified and crushed. The slag 11 is discharged out of the system.

  The generated gas 9 generated in the gasification furnace 1 is guided to the heat recovery boiler 2, and exchanges heat with water 13 as a heat medium to generate steam 14 to be recovered. The product gas 9 that has passed through the heat recovery boiler 2 is guided to the cyclone 3 and the char filter 4, and the char 16 in the product gas 9 is collected. The product gas 9 that has passed through the char filter 4 is supplied to the equipment in use as the dust removal product gas 15.

  The char 16 collected by the cyclone 3 and the char filter 4 is collected by the hopper 5, cut out by the rotary valve 6, and supplied to the char burner 8 through the char conveyance path 17. Further, a bypass line 18 that bypasses the char filter 4 by connecting the outlet of the cyclone 3 and the outlet of the char filter 4 is provided.

  FIG. 2 shows a cross-sectional structure of an embodiment of the char filter 4 according to this embodiment. As shown in the figure, the char filter 4 has an upper part of a cylindrical filter container 20 partitioned by a partition member 21, and a plurality of cylindrical metal filter elements 22 are suspended from through holes formed in the partition member 21. Is provided. The upper end of the filter element 22 is opened to the upper space 23 of the filter container 20 partitioned by the partition member 21, and the lower end is closed. The introduction pipe 24 for the product gas 9 is introduced from the lower part of the filter container 20, and the tip of the introduction pipe 24 is vertically raised at the center of the plurality of suspended filter elements 22 and is partitioned by the partition member 21. An opening is formed above the lower space 25 of the container 20. A discharge pipe 26 for the dust removal product gas 15 is connected to the upper space 23 of the filter container 20. In the upper space 23 of the filter container 20, a plurality of backwash gas nozzles 29 for supplying backwash gas 28 via backwash gas supply valves 27 are provided toward the upper openings of the filter elements 22. . A char discharge pipe 30 is provided at the bottom of the lower space 25 of the filter container 20. Further, a differential pressure gauge 31 for detecting the differential pressure between the upper space 23 and the lower space 25 of the filter container 20 and a pressure gauge 32 for measuring the pressure in the lower space 25 are provided.

  The filter element 22 includes an element 22a that filters char on the outer surface, and an FSF (Fail Safe Fuse) 22b that is a rough opening element attached to the inner surface of the element 22a for safety measures. The filter element 22 is a solid content in the product gas 9 by allowing the produced gas to flow from the outer surface side to the inner surface side of the cylinder and collecting char 16 and dust in the produced gas 9 on the outer filtration surface. The char and soot are removed, and the dedusted product gas 15 from which the char and soot in the product gas 9 are removed is discharged from the exhaust pipe 26.

  When the filter element 22 collects char, the ventilation resistance increases, and the filter differential pressure ΔP measured by the differential pressure gauge 31 installed in the char filter 4 increases. Therefore, when the filter differential pressure ΔP reaches a predetermined set value, the backwash gas supply valve 27 is instantaneously opened, and the backwash gas 28 is blown into the inner surface side of the filter element 22 to be collected on the outer surface side of the filter element 22. I'm trying to pay off the char 16 By this back washing operation, the filter element 22 is washed, and the filter differential pressure ΔP is restored to the filter differential pressure before the char 16 is collected.

  Next, the differential pressure change during char collection and backwashing by the char filter 4 and the principle of char collection by the filter element 22 will be described. FIG. 3 shows a change example of the filter differential pressure ΔP when the char filter 4 collects dust and backwash, and FIG. 4 shows the principle of dust collection and backwashing by the filter element 22. As shown in FIG. 4A, when the char 16 in the product gas 9 is filtered on the outer surface of the cylindrical filter element 22, the filtration area increases as the char 16 is collected on the outer surface of the filter element 22. Decrease gradually. Thereby, the ventilation resistance of the filter element 22 gradually increases, and the filter differential pressure ΔP gradually increases. FIG. 4B shows a state where the char 16 is collected on the outer surface of the filter element 22. At the time of this collection, the fine char 16 enters a little from the outer surface of the filter element 22 to form a permanent layer 35. If the char 16 is continuously collected in this manner, the differential pressure ΔP of the filter element 22 further increases.

  Therefore, when the filter differential pressure ΔP increases, the filter element 22 is backwashed to recover the differential pressure. Conventionally, there are two methods for backwashing the filter element 22: a differential pressure type for backwashing when the filter differential pressure ΔP reaches a set value or more, and a timer type for backwashing at regular time intervals. It goes without saying that may be adopted. The change example of the filter differential pressure ΔP in FIG. 3 is an example of a backwash operation by a timer type. That is, as shown in FIG. 3, after performing the collection operation for a certain time, the operation of performing the backwash operation instantaneously (pulse-like) is repeated. As a result, the char 16 collected as shown in FIG. 4B is removed from the filter element 22 as shown in FIG. 4C when backwashing is performed. However, the permanent layer 35 is left on the outer surface of the filter element 22. Thus, the filter differential pressure ΔP after the char 16 adhering to the backwash operation is removed is referred to as a recovery differential pressure. This recovery differential pressure usually recovers almost to the differential pressure before char 16 collection. However, as the char 16 is repeatedly collected and backwashed, the char 16 that cannot be removed by the backwash operation remains after forming the permanent layer 35, so that the filter differential pressure ΔP gradually increases as shown in FIG. Become.

  The reason why the permanent layer 35 is formed is as follows. As shown in FIG. 4B, when the char 16 during the gasification operation is collected, the fine char from the outer surface to a depth of several tens μm or about a hundred μm is formed in the pores inside the filter element 22. 16 enters. Then, on the outer surface of the filter element 22, a char deposition layer is formed in which the char 16 filtered from the generated gas 9 is deposited. A permanent layer 35 is formed by the char entry portion inside the filter element 22 and the char deposition layer on the outer surface. In this way, the char 16 is filtered from the product gas 9 using the permanent layer 35 and the filter element 22 as a filter body. Therefore, in the backwash operation during the normal gasification operation, as shown in FIG. 4C, the pressure difference of the filter element 22 is removed by removing the deposited layer of the char 16 that has been filtered and deposited by the permanent layer 35. ΔP will be recovered. However, the permanent layer 35 is gradually thickened, or the permanent layer is consolidated and strengthened by the dynamic pressure of the generated gas, or the clogging of fine char that has entered the pores is strengthened. There is a problem that the differential pressure ΔP of the element 22 cannot be recovered.

Here, the thickness of the permanent layer 35 is examined. The thickness of the permanent layer 35, particularly the thickness of the char deposition layer formed on the outer surface of the filter element 22, is determined by the concentration of the char 16 in the product gas 9 at the time of char collection, the flow rate of the product gas 9 or the filtration rate. And the backwashing gas pressure during backwashing, the backwashing gas flow rate, and the backwashing time and backwashing interval. Now, if the conditions of the backwashing operation do not change depending on the operating conditions of the coal gasifier, that is, if the effect of removing the filter element 22 is the same, the thickness of the permanent layer 35 is the char concentration and the char concentration when the char 16 is collected. It is thought that it depends on the filtration rate. In general, when the filtration rate is as low as several cm / sec, the filter differential pressure ΔP is expressed by the following equation (1). From the equation (1), the filtration rate and the differential pressure of the filter element 22 are in a proportional relationship, and it is considered effective to regenerate the filter element 22 if the filtration rate is reduced during the backwash operation.
ΔP = K ・ μ ・ Vf (1)
Where ΔP: differential pressure (Pa) of the filter element 22
Vf: Filtration rate (m / s)
μ: Gas viscosity coefficient (kg · s · m ² , × 10 ⁶ )
K: Loss coefficient (m ⁻¹ , × 10 ¹⁰ )

  FIG. 5 (a) shows the backwashing operation during the gasification operation, and FIG. 5 (b) shows the mechanism of removal by the backwashing operation under conditions of low filtration rate (low flow rate) and no dust such as char 16. 5A and 5B, the backwash conditions such as backwash gas pressure, backwash interval, and backwash time are not changed. FIG. 5A shows a case where the rated load of the gasification operation is assumed and the filtration rate is high and the char concentration is high. The char 16 filtered from the product gas 9 and deposited on the permanent layer 35 is subjected to the backwash operation. It seems that they are being paid off. The figure (b) is based on the assumption that the coal gasifier is warming up. The gas flow rate is lower than in the gasification operation, the filtration rate is low, and the char 16 is not present in the gas. In addition to the char 16 deposited on the permanent layer 35, a part of the permanent layer 35 formed on the outer surface of the filter element 22 is peeled off. As shown in FIG. 5B, when the back washing operation is performed under the condition of low flow rate and no dust such as char 16, a part of the permanent layer 35 formed on the outer surface of the filter element 22 is removed, and the permanent layer is removed. The thickness of 35 is reduced, the ventilation resistance of the filter element 22 is reduced, and the differential pressure of the char filter 4 is restored.

The filter differential pressure ΔP shown in the equation (1) is generally expressed as the sum of the differential pressure ΔPe of the filter element 22 and the differential pressure ΔPp of the permanent layer 35 as shown in the equation (2). The permanent layer 35 formed on the outer surface of the filter element 22 is assumed to be a layer formed by adhering particles of the char 16, and considering the differential pressure of the permanent layer 35 as the fluid resistance of the particle-packed layer, Kozeny Kalman's Can be estimated from the formula.
ΔP = ΔPe + ΔPp (2)

  Based on these findings, the relationship between the gasifier load and the removal rate of the permanent layer 35 formed on the outer surface of the filter element 22 is shown in the lower part of FIG. In the figure, the pressure difference ΔPp of the permanent layer 35 is estimated from the amount of gas produced at each gasifier load, the char concentration, etc., and the permanent layer 35 is based on the pressure difference ΔPp at the gasifier load rating (100%). The removal rate was determined. The removal rate of the permanent layer 35 when the gasifier load is 100% is 0%, and the removal rate of the permanent layer 35 is 0% when the gasifier load is 0% where there is no product gas 9 and no char 16 exists. Yes. The upper part of FIG. 6 shows a state in which the permanent layer 35 and the char 16 corresponding to the gasifier load are removed. Moreover, although demonstrated in FIG. 5, the backwashing gas pressure of backwashing operation, the backwashing interval, and the backwashing time were made constant also in this calculation.

  The char 16 in the product gas 9 is filtered and adhered on the outer surface of the filter element 22. Next, when the back washing operation is performed, the attached char 16 is removed from the filter element 22. Therefore, it is considered that the thickness of the permanent layer 35 is determined by the balance between the concentration of the char 16 in the generated gas 9 and the effect of removing by the back washing operation. Here, when the gasification furnace load is lowered, the concentration of the char 16 in the product gas 9 is lowered. That is, the amount of char 16 attached to the filter element 22 is reduced. Furthermore, since the flow rate or flow velocity of the product gas 9 is reduced, the dynamic pressure of the product gas that presses the char 16 attached to the filter element 22 is also reduced. When the normal backwash operation is performed under the operating conditions below the rated load of the gasifier, that is, under the condition that the concentration of the char 16 and the gas flow rate or flow velocity of the product gas 9 are lowered, the same as the rated conditions. Since there is a payout effect, char can be paid off more effectively. Accordingly, even a part of the permanent layer 35 attached to the filter element 22 can be removed, and the char filter 4 can be regenerated.

  That is, as shown in the graph of FIG. 6, when the backwash operation is performed under conditions of a low char concentration and a low filtration rate below the rated load, the removal rate of the permanent layer 35 tends to increase as the gasifier load decreases. Become. When the gasifier load is 45% or less, the removal rate of the permanent layer 35 is 80% or more, and a relatively stable removal effect can be expected. Therefore, when the char filter 4 is sufficiently regenerated by backwashing under conditions below the rated load, the gasification furnace load is 45% or less, the gas flow rate or gas flow rate, that is, the filtration rate is 45% or less of the rated load. Is considered desirable.

  Further, by performing the backwashing operation while venting the produced gas or the like to the char filter 4, the corrosive substance of the sulfur in the produced gas 9 and the container 20 is not accompanied by the backwashed gas, and the element 22 a of the filter element 22. Alternatively, entry into the FSF 22b can be prevented.

Based on these findings, the conditions for effectively removing the permanent layer 35, which is the attached char of the filter element 22 that has not been removed by backwashing during the gasification operation, by backwashing satisfy the following conditions I and II. is important.
(I) Before the gasification operation including the start time or after the gasification operation is completed, backwashing is performed while a regeneration gas such as a generated gas having a low dust concentration is passed through the filter element 22 (II). When the filter element 22 is regenerated, the gas flow rate of the regeneration gas that is ventilated is kept below the rated filtration rate of the filter element 22, that is, the gas flow rate of the regeneration gas that is flowing is low. As the regeneration gas with low dust concentration to be ventilated, in addition to the generated gas with low dust concentration, purge gas such as nitrogen gas which is an inert gas, start-up fuel used for temperature rise and pressure increase at start-up of coal gasifier, etc. Combustion exhaust gas (warm-up gas) or the like can be applied.

  In view of the knowledge described above, a specific example in which the method for regenerating the filter element 22 of the present invention is applied to the char filter 4 of the coal gasifier shown in FIG. 1 will be described below.

  Example 1 of the regeneration method of the filter element 22 of the char filter 4 of the coal gasifier according to the present invention shown in FIG. 1 will be described based on the cross-sectional configuration diagram of the main part of the char filter 4 shown in FIG. . For convenience, the state at the time of char collection operation is shown on the left side of FIG. 7, and the state at the time of backwashing operation is shown on the right side. In the preparatory stage before the gasification operation, the coal gasifier is configured so that excess oxygen or air does not remain in the system of the coal gasifier including the gasification furnace 1, the heat recovery boiler 2, the char filter 4, and the like. Purge is performed by supplying purge gas inside. In general, the purge gas is a gas that does not contain soot, and nitrogen gas that is an inert gas is often used.

  Here, when the filter element 22 is regenerated, the flow rate of the purge gas as the regeneration gas 37 is set to be equal to or lower than the rated flow rate of the product gas 9 of the gasification furnace 1. In this embodiment, the purge gas flow rate is adjusted so that the filtration rate of the filter element 22 of the char filter 4 is less than the rated filtration rate, preferably 45% or less. In this way, by setting the gas flow rate lower than the rated flow rate of the product gas 9, the fine char 16 that has entered the pores of the filter element 22 during the gasification operation is not pressed by the dynamic pressure of the purge gas. Since the char deposition layer such as the permanent layer 35 does not become strong, the clogging of the permanent layer 35 can be prevented.

  Even if the inner surface of the upper space 23 of the filter container 20 is corroded by sulfur contained in the product gas 9 at the time of gasification operation, the peeled corroded material 36 is accompanied by the purge gas and the dedusted product gas 15 It is discharged from the discharge pipe 26. As a result, even if the backwash operation is performed, the corrosive material does not enter the FSF 22b of the filter element 22 along with the backwash gas 28.

Further, since nitrogen gas is used as the purge gas, as described with reference to FIG. 5, there is no char or dust in the gas filtered by the filter element 22, and it is less than the rated load of the gasification furnace 1, preferably the filter element. The backwashing operation equivalent to that at the time of gasification operation is performed under a small purge gas flow rate at which the filtration rate is 45% or less of the rated filtration rate of 22. As a result, according to the present embodiment, char and dust are not newly attached, and the char 16 and the permanent layer 35 attached to the filter element 22 are not contaminated on the inner surface which is the clean surface of the filter element 22. Department can be dismissed. Thereby, the char 16 and the permanent layer 35 adhering to the filter element 22 that could not be removed by backwashing during the gasification operation can be removed by backwashing, and the filter container 20 in which the filter element 22 is accommodated can be removed. It is possible to avoid clogging of the filtration part on the inner surface side of the filter element 22 due to corrosive substances.

  In the above description, the case where the purge operation of the coal gasifier is performed before the gasification operation is described as an example, but the purge operation is also performed after the gasification operation. That is, since the produced gas 9 obtained by gasifying coal contains carbon monoxide gas, which is a toxic gas, and hydrogen gas, which is a combustible gas, these gases do not remain in the system of the coal gasifier. Thus, purging is mainly performed with nitrogen gas. Also during the purge after the gasification operation, the purge gas flow rate below the flow rate of the product gas 9 at the rated load of the gasification furnace 1, preferably the filter element 22 of the char filter 4 is the same as before the gasification operation. Backwash operation is performed by adjusting the purge gas flow rate to a filtration rate that is 45% or less of the rated filtration rate. Thereby, the filter element can be regenerated without contaminating the inner surface, which is the clean side of the filter element 22.

  The second embodiment of the regeneration method of the filter element 22 of the char filter 4 of the coal gasifier according to the present invention shown in FIG. 1 is similar to the first embodiment in the cross-sectional configuration of the main part of the char filter 4 shown in FIG. This will be described with reference to the drawings. In the first embodiment, the method of regenerating the filter element 22 in the purge of the coal gasifier with nitrogen gas in the preparation stage before the gasification operation has been described. At the start of normal gasification operation, after the coal gasifier is purged, the temperature and pressure of the coal gasifier are increased by the combustion exhaust gas of the starting fuel. The second embodiment is characterized in that the filter element 22 is regenerated using the combustion exhaust gas as the regeneration gas 37 in the process of raising the temperature and increasing the pressure of the coal gasifier. The regeneration of the filter element 22 according to the second embodiment may be continued following the first embodiment, or may be performed independently instead of the regeneration of the filter element 22 of the first embodiment.

  When the coal gasifier is started, liquid fuel such as light oil is mainly used as a starter fuel, and the coal gasifier is heated with the combustion exhaust gas and the pressure is increased. A small amount of soot is present in the combustion exhaust gas at the time of start-up, but the concentration of soot and char is very small compared to during steady-state coal gasification operation. ) Can be satisfied. Therefore, in the second embodiment, the filter element 22 is back-washed while adjusting the flow rate of the combustion exhaust gas used for the temperature rise and pressure increase at the start of the coal gasifier so as to satisfy the above condition (II). Reproduce. That is, the flow rate of the combustion exhaust gas at the start-up is adjusted so that the filtration rate is equal to or less than the rated flow rate of the product gas 9 of the coal gasifier, preferably 45% or less of the rated filtration rate of the filter element 22. Here, the combustion exhaust gas flow rate of the starting fuel is a flow rate that is approximately 1/3 of the rated flow rate of the product gas 9 of the coal gasifier (about 30% of the gasifier load). It can be a flow rate.

  As described above, according to the second embodiment, the char filter element 22 is newly added to the char filter element 22 by repeatedly performing the back-washing operation of the char filter element 22 while the coal gasifier is heated and pressurized by the combustion exhaust gas of the starting fuel. Part of the char 16 and the permanent layer 35 adhering during the gasification operation can be wiped off without adhering soot. Moreover, since the filter element 22 is back-washed while ventilating at a low flow rate, it is possible to prevent the corroded material 36 on the inner surface of the filter container 20 from entering the inner surface of the filter element 22, so that the inner surface of the filter element 22 is soiled. The filter element 22 can be efficiently regenerated without any trouble.

  A third embodiment of the regeneration method of the filter element 22 of the char filter 4 of the coal gasifier according to the present invention shown in FIG. 1 is similar to the first embodiment in the cross-sectional configuration of the main part of the char filter 4 shown in FIG. This will be described with reference to the drawings. In the second embodiment, the case where the filter element 22 is regenerated when the temperature of the entire coal gasifier is increased and the pressure is increased with the combustion exhaust gas of the starting fuel is shown. However, in the operation of raising the temperature and raising the pressure of the coal gasifier, the char filter 4 may be separated from the system of the gasification furnace 1, the heat recovery boiler 2, and the cyclone 3 to raise and raise the pressure. That is, the char filter 4 may be bypassed by the bypass line 18 of FIG. That is, although not shown in FIG. 1, the product gas inlet / outlet valve provided in the char filter 4 is closed, the valve installed in the bypass line 18 is opened, and the char filter 4 is bypassed. The temperature and pressure of the coal gasifier other than the char filter 4 are increased by the combustion exhaust gas of the starting fuel from the gasification furnace 1.

  On the other hand, a gas such as nitrogen gas is used for raising the temperature and raising the pressure of the char filter 4. For example, after indirectly heating nitrogen gas with a heat exchanger using steam or the like as a heat source to warm it to a predetermined temperature, the char filter 4 is adjusted by adjusting the inlet / outlet valve of the warm-up line, which is not shown in FIG. The temperature is increased and the pressure is increased by aeration. In the present embodiment, nitrogen gas at the time of temperature rise and pressure increase of the char filter 4 is used as the regeneration gas 37 and the flow rate of the nitrogen gas is adjusted to be equal to or lower than the filtration rate at the rated load of the char filter 4. Preferably, the flow rate of nitrogen gas is set to be 45% or less of the filtration rate at the rated load. Accordingly, since the above conditions (I) and (II) are satisfied, a part of the char 16 and the permanent layer 35 adhering during the gasification operation is removed without adhering new dust to the char filter element 22. Can do. Moreover, since the filter element 22 is back-washed while ventilating at a low flow rate, it is possible to prevent the corroded material 36 on the inner surface of the filter container 20 from entering the inner surface of the filter element 22, so that the inner surface of the filter element 22 is soiled. The filter element 22 can be efficiently regenerated without any trouble.

  Example 4 of the regeneration method of the filter element 22 of the char filter 4 of the coal gasifier according to the present invention shown in FIG. 1 is similar to Example 1 in cross-sectional configuration of the main part of the char filter 4 shown in FIG. This will be described with reference to the drawings. In the second embodiment, the method of regenerating the filter element 22 is shown when the temperature and pressure of the entire coal gasifier are increased, or in the third embodiment, when the temperature and pressure of the char filter 4 are increased and separated from other devices. . In the third embodiment, after the temperature rise and pressure increase of the char filter 4 are completed, an operation of gradually opening the gas inlet / outlet valve of the char filter 4 and gradually closing the bypass valve is performed. At this time, a pressure equalizing operation is performed to slowly equalize the pressures of the gasification furnace 1 and the char filter 4 while adjusting the gas amount of the warming-up combustion exhaust gas so as not to exceed the maximum filtration rate of the char filter 4.

  In the fourth embodiment, the warming-up combustion exhaust gas during the pressure equalization operation is used as the regeneration gas 37, and the gas flow rate of the combustion exhaust gas is equal to or lower than the generated gas flow rate at the rated load of the coal gasifier, preferably a char filter. 4 is adjusted so that the filtration rate of the filter element 22 is 45% or less of the filtration rate at the rated load. Then, the backwashing gas supply valve 25 is instantly opened to perform the backwashing operation of the filter element 22. According to the fourth embodiment, the flue gas used in the pressure equalization operation does not contain soot and the filtration rate is 45% or less of the rated load, so the above conditions (I) and (II) are satisfied. Thus, the filter element 22 can be backwashed. Therefore, by repeatedly performing the backwashing operation of the filter element 22 during the pressure equalizing operation, part of the permanent layer 35 can be removed in addition to the char 16 adhering during the gasification operation, and the filter element 22 is regenerated. Can do. In addition, since the combustion exhaust gas for temperature rise and pressure increase is vented to the filter element 22, even if the corrosive matter 36 generated on the inner surface of the upper space 23 of the filter container 20 is peeled off during the gasification operation, the filter element 22. It is possible to prevent the flow back to the inner surface. Thereby, the filter element 22 can be efficiently regenerated without contaminating the inner surface of the filter element 22. Note that the regeneration of the filter element 22 according to the fourth embodiment may be performed using a product gas obtained by gasifying coal with a low load in the gasification furnace 1 as a regeneration gas.

  FIG. 8 shows the results of testing the influence of the gasifier load (percentage of the rated load) that correlates with the filtration rate with respect to the loss factor K and the recovery differential pressure ΔP of the filter element 22. This test is a result of a confirmation test in which the inventors actually performed the regeneration method of the filter element 22 of the present invention using the filter element 22 in a laboratory-scale backwash test apparatus.

  First, in order to simulate the gasification operation, dust collection and backwashing operations were repeatedly performed by the filter element 22 at a gas flow rate corresponding to the rated load while supplying dust. After the recovery differential pressure ΔP of the filter element 22 was stabilized, the dust supply was stopped and the gas flow rate was reduced to a gasifier load equivalent to 60%. At this time, the recovery differential pressure ΔP decreased to about 60% according to the filtration rate, but the loss factor K hardly decreased. This can be inferred that the filter element 22 is not being regenerated. Further, when the gas flow rate was reduced to a gasifier load equivalent to 20%, the loss factor K rapidly decreased. From this, it was confirmed that when the gas flow rate was reduced to 20% corresponding to the gasifier load, the filter element 22 was regenerated, and part or all of the permanent layer 35 was removed.

As described above, the present invention collects char contained in the product gas by filtering the produced gas discharged from the gasification furnace that gasifies the carbon-based fine powder raw material through a filter element having pores, In the filter element regeneration method of a filter device for collecting the char collected by backwashing the filter element with backwash gas, the filter device before the gasification operation including the start of the gasification furnace or after the gasification operation is completed. Is supplied with a regeneration gas 37 in which the concentration of char and dust is lower than the concentration of char and dust contained in the product gas, and the speed of the regeneration gas 37 vented to the filter element is kept below the rated filtration rate of the filter element. However, it is characterized by removing the char attached to the filter element by backwashing with backwashing gas and regenerating.
That is, when the gasifier is purged in the gasifier system when the gasifier is started or stopped, when the temperature of the startup fuel is raised and increased by the combustion exhaust gas when the gasifier is started, the gasifier and the char filter are individually connected. When the char filter is warmed up when the temperature is increased and the pressure is increased, and when the pressure is adjusted after the char filter is heated and the pressure is increased, the back washing operation of the filter element is repeatedly performed. As a result, without removing the filter element from the filter vessel, the gasification furnace is started or stopped without preventing the backflow of the corrosive substances generated during the gasification operation and contaminating the clean inner surface of the filter element. The filter element can be efficiently regenerated in a short time. In addition, the filter element can be regenerated without a separate regenerating facility such as a heating device as compared with the case of regenerating by heating. As a result, there is no distortion caused by heat to the filter container, so that the life of the char filter can be extended.

As described above, according to the present invention, it is possible to prevent an increase in the filter differential pressure generated at each gasification operation, and to achieve stable operation and improved reliability of the gasifier. Furthermore, the stop period for regenerating the filter element can be shortened, and the gasification plant can be operated economically.
In particular, the char filter is in an important position for determining the continuous and stable operation of the coal gasification plant. When the recovery differential pressure of the char filter increases, the operation of the gasifier is forced to stop. Therefore, by applying the filter element regeneration method of the present invention, there is an effect that the filter element can be easily regenerated without being removed from the filter container for the regeneration process by the backwashing operation.

DESCRIPTION OF SYMBOLS 1 Gasification furnace 2 Heat recovery boiler 3 Cyclone 4 Char filter 7 Gasification burner 8 Char burner 9 Product gas 15 Dedusted product gas 16 Char 18 Bypass line 20 Filter container 21 Partition member 22 Filter element 23 Upper space 27 Backwash gas Supply valve 28 Backwash gas 36 Corrosive 37 Regeneration gas

Claims (5)

The product gas discharged from the gasification furnace that gasifies the carbon-based fine powder raw material is filtered through a filter element having pores to collect char contained in the product gas, and the filter element is backwashed with a backwash gas. In the filter element regeneration method of the filter device for washing and collecting the collected char,
Before the gasification operation of the gasification furnace is started or after the gasification operation is completed, the filter device is supplied with a regeneration gas whose char and dust concentrations are lower than the char and dust concentrations contained in the product gas, While maintaining the speed of the regeneration gas vented to the filter element below the rated filtration rate of the filter element, the backwashing gas is backwashed to remove char attached to the filter element and regenerate. A characteristic filter element regeneration method.   The purge gas for purging the system of a gasification apparatus including the gasification furnace before or after the gasification operation of the gasification furnace is started as the regeneration gas. The filter element regeneration method as described.   2. The filter element regeneration method according to claim 1, wherein as the regeneration gas, combustion exhaust gas of the startup fuel in the process of raising the temperature and increasing the pressure of the gasifier using the startup fuel is used.   2. The filter element regeneration method according to claim 1, wherein a warm-up gas that raises and raises the pressure of the gasification furnace and the filter device is used as the regeneration gas. Claims wherein the regeneration gas, characterized by using the combustion exhaust gas and the product gas of the startup fuel that put the step of adjusting the internal pressure of the gasification furnace and the filter device according startup fuel the same Item 2. A filter element regeneration method according to Item 1 .

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