GB2293777A - Fuse apparatus for shutting down failed filters - Google Patents

Abstract

A fuse 225 for protecting process equipment and the environment from particle contamination including: a vessel with a tube sheet across the top of the vessel; two or more tubular filters 215 open at the top and arranged in filter clusters, each filter containing a permeable material; and at least one seal 220 placed between the tube sheet and each of the filters; fuses connecting to the top of the tube sheet for preventing passage of the particle-containing gas in the event of failure of one or more of the filters or seals; where the open bottom of a single fuse surrounds the open tops of one filter cluster and corresponding seals; the fuses containing a permeable material having a higher permeability than the permeability of the permeable filter material; and in the event of failure of one or more filters or seals, the flow of the particle-containing gas through the fuse causes substantially complete blockage of the fuse; and a backflushing conduit for removing solid particles collected on the outside of the filters of the filter cluster. <IMAGE>

Description

FUSE APPARATUS FOR SHUTTING DOWN FAILED FILTERS I. FIELD OF THE INVENTION The invention relates to a mechanical fuse apparatus for shutting down operation of a particulate filter when the filter or its seal fails.

II. BACKGROUND OF THE INVENTION In many industrial processes, particularly elevated or high temperature, high pressure processes, gases are produced containing quantities of solid particles which must be removed before the gases may be used, treated further, or released. For example, the ordinary combustion of coal, for example in coal-fired power plants, produces an effluent gas containing flyash particles which cannot be released to the atmosphere.

Similarly, the gasification or partial oxidation of coal for the production of synthesis gas often produces a product gas stream which contains from one percent to 20 percent by weight, based on the total weight of the gas and solids, of various solid particles which comprise flyslag or flyash and, in some cases, unburned coal. Fluid catalytic processes often produce gas or liquid streams containing residual catalyst "fines" which cannot be allowed to contaminate either the product or the environment and which can damage downstream equipment.

In a previously used method, residual solidscontaining gases are passed continuously or intermittently through a filter or bank of discrete filters. Intermittently, the filters are cleaned or purged so that they do not become totally clogged. For example, the filters may be subjected to a back-flush of gas or liquid, the particles removed being allowed to collect in the bottom of the filter vessel for continuous or periodic removal. Sonic, ultrasonic, or subsonic removal may also be employed.

A problem common to many filtration systems is the possibility of failure of the filter/seal or one or more filters/seals in a bank thereof. For example, if one filter in a bank or cluster of filters fails, substantial flow of the fluid will channel through the failed filter, allowing substantial bypass of solids, thereby rendering the whole filter bank ineffective. A method of dealing with this problem is described in USSR Patent Number 434,965 ("USSR"). In USSR a lower filter bag is placed below the tube sheet and an upper filter bag is placed above the tube sheet. A backflushing conduit is used to clean both the lower and upper filter bags. The disclosure in USSR merely shows that multiple filters arranged in series can serve as a means for increasing reliability.In the event of failure of one filter in a series, other filters in the series will continue to perform the filtering function.

The approach in USSR is not satisfactory from both an economic and operational viewpoint. Economically, putting two filters in series has the effect of doubling the cost for filters. Operationally, the upper filter bag has the same or substantially similar likelihood of failure as the lower filter bag since the are both of the same design and material. Accordingly, a need exists, for a filter arrangement which safeguards the environment and downstream equipment from particulate contamination in the event of filter failure, but does not have the economic and operational drawbacks of previously known filter apparatus.

III. SUMMARY OF THE INVENTION Accordingly, the invention includes a fuse for protecting process equipment and the environment from particle contamination. By way of analogy, an electrical fuse stops the flow of electricity when the electrical wire becomes overloaded. This protective action by the electrical fuse protects the circuit from severe damage such as fire or melt down. The term "fuse" as used in this specification and appended claims means an apparatus or article of manufacture used to stop flow of a particle-containing gas in the event of failure of a seal or porous filter.The fuse of the invention includes: (a) a vessel having a tube sheet affixed across a top portion of the vessel; (b) a plurality of filters arranged in filter clusters, each filter including a permeable material, (1) the filters having at least one wall surrounding a hollow duct along the longitudinal axis and the filters having a closed bottom portion and an open top portion; (2) the open top portion of the filters flexibly attached to the tube sheet and the filters disposed below the tube sheet; (3) the center axis of the filters being substantially aligned with the center axis of the vessel; and (4) the filters being for removing particles from particle-containing gas when particle-containing gas is passed from the outside of the filters to the inside of the filters; and (c) a plurality of seals, at least one seal removably disposed between the tube sheet and each of the filters, for reducing particle leakage and for reducing stress on the top portion of the filters when lateral or rotational force is applied to the filters; (d) a fuse connected to the top of the tube sheet for preventing passage of the particle-containing gas in the event of failure of one or more of the filters or seals; (1) the fuse being open at a bottom portion and closed at a top portion; (2) where the open bottom portion of one fuse is in communication with and surrounds the open top portions of one filter cluster and corresponding seals; (3) the fuse including a permeable material having a higher permeability than the permeability of the permeable filter material;; (4) the permeable fuse material having not more than 25% of the sum of the surface area of the permeable filter material contained in one filter cluster; and (5) where the permeability of the permeable material of the fuse is adapted to be sufficiently high where when passing the gas of the particle-containing gas through the filter cluster and fuse, the sum of the pressure drop through the filter cluster and fuse is not substantially greater than the pressure drop through the filter cluster, and is adapted to be sufficiently low that in the event of failure of one or more filters or seals, the flow of the particlecontaining gas through the fuse causes substantially complete blockage of the fuse; and (e) a backflushing conduit having an outlet disposed above the tube sheet, adapted to supplying a backflushing gas to the inside of the filters of the filter cluster through the open top portion of the filters of the filter cluster for removing solid particles collected on the outside of the filters of the filter cluster and for not substantially removing particles collected on the inside of the fuse.

IV. BRIEF DESCRIPTION OF THE DRAWING Figure 1, the sole figure, depicts one embodiment of the invention which includes a single fuse above a single filter.

V. DESCRIPTION OF THE PREFERRED EMBODIMENTS-OVERVIEW OF CONCEPT The invention relates to an apparatus where a fuse is provided, suitably positioned above the outlet of a filter, for receiving and allowing passage of the flow of fluid and any negligible amount of solids which may pass through the filter during normal operation, so that, should failure of the filter occur, the fuse will plug due to the much higher solids flow rate. The permeable material of the fuse is composed of a material having greater pore size and greater permeability than the permeable material of the filter.

The permeability and pore size should also be low enough to prohibit passage of large amounts of particulates when a filter or seal fails and insure that the fuse plugs upon such failure. To accomplish the results of the invention, the fuse must be positioned so that, should the filter fail and the fuse come into use, normal cleaning of the filters does not remove the particles collected on the fuse. If backflushing of the filter is employed to clean these filters, the outlet of the flushing mechanism must not be located so as to clean the fuse as well. As used herein, the term "permeable material" is to be understood, unless indicated to the contrary, to include the singular or plural, i.e., one or more kinds of particle trapping substances.Thus, the "permeable material" of a cluster of filters might include more than one kind of filtering substance, and a single filter may include more than one kind of filtering substance.

VI. PREFERRED EMBODIMENTS-OVERVIEW OF SPECIFIC EMBODIMENT In a preferred form, the invention includes a fuse for protecting process equipment and the environment from particle contamination including: (a) a vessel having a tube sheet affixed across a top portion of the vessel; (b) a plurality of filters arranged in filter clusters, each filter comprising a permeable material, (1) the filters having at least one wall surrounding a hollow duct along the longitudinal axis and the filters having a closed bottom portion and an open top portion; (2) the open top portion of the filters flexibly attached to the tube sheet and the filters disposed below the tube sheet; (3) the center axis of the filters being substantially aligned with the center axis of the vessel; and (4) the filters being for removing particles from particle-containing gas when particle-containing gas is passed from the outside of the filters to the inside of the filters; and (c) a plurality of seals, at least one seal removably disposed between the tube sheet and each of the filters, for reducing particle leakage and for reducing stress on the top portion of the filters when lateral or rotational force is applied to the filters; (d) a plurality of fuses connecting to the top of the tube sheet for preventing passage of the particle-containing gas in the event of failure of one or more of the filters or seals; (1) the fuse being open at a bottom portion and closed at a top portion; (2) where the open bottom portion of the fuse is in communication with and surrounds the open top portions of one filter cluster and corresponding seals;; (3) the fuses comprising a permeable material having a higher permeability than the permeability of the permeable filter material; (4) the permeable fuse material having not more than 25% of the sum of the surface area of the permeable filter material contained in one filter cluster; and (5) where the permeability of the permeable material of the fuse is adapted to be sufficiently high where when passing the gas of the particle-containing gas through the filter cluster and fuse, the sum of the pressure drop through the filter cluster and fuse is not substantially greater than the pressure drop through the filter cluster, and is adapted to be sufficiently low that in the event of failure of one or more filters or seals, the flow of the particle-containing gas through the fuse causes substantially complete blockage of the fuse; and (e) a backflushing conduit having an outlet disposed above the tube sheet, adapted to supplying a backflushing gas to the inside of the filters of the filter cluster through the open top portion of the filters of the filter cluster for removing solid particles collected on the outside of the filters of the filter cluster and for not substantially removing particles collected on the inside of the fuse.

VII.PREFERRED EMBODIMENTS - DETAILS ON SPECIFIC ASPECTS A. THE FILTERS 1. Filter Material: The filter is made of rigid or flexible, felted or non-felted material, or woven or non-woven material.

The filters includes in whole or in part a permeable material such as porous ceramic, porous metal, porous plastic, or porous fabric. Porous ceramic can be composed, e.g., of layered silicon carbide ceramic formed by bonding or sintering individual particles.

Multiple or single layer permeable material substances may be used. If the invention is adapted for high temperature, high pressure use, the filters employed are typically composed of metal, ceramic, glass, or high temperature plastics. "High temperature, high pressure service," in the context of the invention, refers to temperatures of perhaps 100 "C to 1500 "C (preferably 200 OC to 650 C), and pressures of from one atmosphere to 50 atmospheres or greater.

2. Filter Shape: In the apparatus according to this invention, each filter has at least one wall surrounding a hollow duct along the filter's longitudinal axis. The filters have a closed bottom portion and an open top portion. In one embodiment, the filters are elongated and tubular or cylindrical in shape.

3. Connection Of Filters To Tube Plate: In one embodiment, the filters in each filter cluster are positioned with a common mount, i.e., a tube sheet. The open top portion of each filter is attached to either the top or bottom of the tube sheet.

When attached to the top of the tube sheet, a recess may be machined into the tube sheet to provide a place of the top portion of the filter to lie in. The open top portion of the filters may be flared to lie in such a recess.

4. Filter Number and Spacing: The total number of filters in the fuse apparatus is typically from about three to about 2000 filters, or more typically from about 50 to about 2000 filters, or from about 100 to about 1500 filters. The total number of filters is divided and grouped in clusters. In the filter clusters a plurality of filters is employed.

Typically the number of filters in each filter cluster is from about 3 to about 200 filters, or more typically from about 10 to about 80 filters, or from about 20 to about 70 filters. The spacing between the filters in each filter cluster, and of the clusters to each other, is a function of the particulate concentration of the fluid-particulate mixture introduced into the vessel and will vary accordingly.

B. THE SEALS Seals are typically placed between the filter and the tube sheet and between the fuse and the tube sheet in the respective attachment of the filter and fuse to the tube sheet. The seals reduce leakage past the filter and fuse, and cushion the filter from lateral and rotational forces caused by the gas flow patterns below the tube sheet. In high temperature use, the seals are typically of a material selected from ceramic fiber, glass fiber, other high temperature materials, and mixtures of these materials.

C. THE FUSE The fuse may be constructed of the same or a different type substance as the filter. The fuse material has a greater permeability and greater pore size than the filter material utilized. Preferably, the permeability level and pore size of the fuse will be greater than that of the filter material by a factor of at least 3, preferably at least 5. This ensures that, in normal operation, the fuse will allow particles through that are greater in size than the filter and that any particles normally penetrating the filter do not block the fuse, but in the event of failure of one or more filters or seals, the fuse will become plugged by the much higher solids flow rate.

The permeability of the permeable material of the fuse is chosen to be sufficiently high so that during passing of the gas of the particle-containing gas through the filter cluster and fuse, the sum of the pressure drop through the filter cluster and fuse is not substantially greater than the pressure drop through the filter cluster. Typically, such added pressure drop is not greater than about 20% or more typically 10%. It is possible to have the added pressure drop not more than about 5%. Also, the permeable material of the fuse is chosen to be sufficiently low so that in the event of failure of one or more filters or seals, the flow of the particle-containing gas through the fuse causes substantially complete blockage of the use.

As indicated, however, the pore size and permeability of the permeable material of the fuse plugs on failure of the filter. Preferably, and not by way of limitation, the pore size and permeability of the material of the fuse should not be greater than about 20 or 30 times that of the mean particle size of the particles being filtered. The surface area of the permeable material in a fuse is substantially smaller than the sum of the surface area of the permeable filter material contained in one filter cluster, preferably not more than about 25% or about 20%, more preferably, not more than about 15% or about 10%.

In addition to the fuse having a greater permeability than the filters, the fuse is also more robust than the filters. The term "robust" as used in this specification, including the claims, means the fuse is less prone to structural, operational failure, and damage upon normal or improper installation than the filters. The design differences inherently cause the fuse to be more robust. These design differences include a substantially smaller size. Also, the fuse is not subject to the high lateral and/or rotational forces to which the filters are subject. The fuse is also directly attached, typically with a seal, to the top of the tube sheet as apposed to the hanging attachment of the filters to the tube sheet.Such attachment differences for the fuse results in reduced likelihood of damage of the fuses upon normal or improper installation compared to the likelihood of damage to the filters upon normal or improper installation of the filters.

D. CONNECTING MEANS The fuse may be directly connected to the top of the tube sheet. A seal is typically placed between the top of the tube sheet and the open bottom portion of the fuse for preventing particles from by-passing the fuse. Although direct connection is optional, a connecting member is typically used for passing gaseous or particle effluent from the filters to the fuse. The connecting member is typically tubular and has an open top portion and open bottom portion. The open top portion of the connecting member is in communication with and affixed to the open bottom portion of the fuse. The open bottom portion of the connecting member is in communication with and affixed to the top of the tube sheet. The connecting member is optionally venturi-shaped. That is, it is narrower at the center then at the ends.The venturi shape is used to increase the flow rate of the backflushing gas.

E. BACKFLUSHING CONDUIT A backflushing conduit is used to clean the filters. The backflushing conduit can optionally penetrate the fuse or the connecting member in order to position the outlet of the backflushing conduit above the tube sheet. The outlet is positioned and designed so that during backflushing, if the fuse is plugged due to seal or filter failure, the fuse is not substantially unplugged by the backflushing. During operation of the fuse apparatus, it is not intended that gas from the outlet of the backflushing pass through the fuse. However, small amounts may in fact pass through the fuse without significant detriment to the operation of the fuse apparatus.

F. UTILITY While the apparatus of the invention is adapted to a wide variety of service conditions, it is eminently adapted to use in the context where a high pressure, elevated or high temperature fluid (liquid or gas) containing solids is processed. Thus, the apparatus may be used, e.g., for solids removal from combustion gases, in an integrated process for the gasification of coal (removal of flyash from synthesis gas), in fluid catalytic processes, in plant emissions control, incineration, and in smelting operations.

G. DETAILED DESCRIPTION OF THE DRAWING In order to illustrate the invention more fully, reference is made to the accompanying drawing. Figure 1 illustrates an embodiment where a single filter is provided with a single fuse.

Vessel 205 houses the other members of the invention. Tube sheet 210 is fixed across the top portion of the vessel 205. Filter 215 is flexibly attached to tube sheet 210, sealed by seal 220, and is disposed below the tube sheet 210. The longitudinal axis of filters 215 is typically aligned with the center axis of vessel 205.

A single fuse 225 is provided with each filter 215.

Fuse 225 is attached to tube sheet 210.

Backflushing conduit 240 in this embodiment penetrates a top portion of fuse 225. Outlet 245 of backflushing conduit 240 is located, in this embodiment, above filter top open portion 216.

H. DESCRIPTION OF THE APPARATUS IN USE IN A PROCESS With reference to Figure 1, the invention will be illustrated by description of removal of flyash from synthesis gas resulting from a coal gasification process. The fuse apparatus, however, could have other applications such as in removal of flyash from flue gas from a coal-fired furnace such as is used in power plants. All values stated are merely exemplary.

1. Normal Operation: A synthesis gas containing some flyash is introduced by any suitable means at elevated pressure, e.g., about 24.5 bar (350 psig), and elevated temperature, e.g., 260 C, into vessel 205, preferably, in a direction tangential to vessel 205. Alternatively, the mixture may be injected in other ways, such as radially (not shown).

The synthesis gas passes through filter 215. The majority of the flyash particles do not pass through the filter and remain on the outer surface of the filter. The synthesis gas then passes out open top portion 216 of the filters and through permeable fuse 225. The synthesis gas continues to further processing.

2. Operation When Filter or Seal Fails: If filter 215 or seal 220 fails so as to allow flyash particles to bypass the filter, the particles cause fuse 225 to plug rapidly. The operation of the failed filter 215 will be discontinued.

According to the invention, a backflushing conduit 240 is placed so as to clean the filter. Outlet 245 of backflushing conduit 240 must located so that cleaning of deposits on the inside of a plugged fuse cannot occur. Thus, in the unit illustrated, backflushing conduit 240 is provided, at or near the open top portion 216 of the filter, for periodically backflushing the filters with a suitable gas. For example, backflushing conduit 240 may be provided through fuse 225 and thus provide the flushing gas, such as nitrogen, to outlet 245 which empties, as mentioned, at or near the open top portion 216 of the filter.

Fuse 225 may comprise all permeable material as shown, or may comprise an impermeable portion and a permeable material. In this case, the entry of backflushing conduit 240 into a top portion of fuse 225 must be adequately sealed.

Claims (20)

1. A fuse apparatus for protecting process equipment and the environment from particle contamination comprising: (a) a vessel having a tube sheet affixed across a top portion of said vessel; (b) a filter comprising a permeable material, (1) said filter having at least one wall surrounding a hollow duct along the longitudinal axis and said filter having a closed bottom portion and an open top portion; (2) said open top portion of said filter flexibly attached to said tube sheet and said filter disposed below said tube sheet; (3) the center axis of said filter being substantially aligned with the center axis of said vessel; and (4) said filter being for removing particles from particle-containing gas when particle-containing gas is passed from the outside of said filter to the inside of said filter; and (c) at least one seal removably disposed between said tube sheet and said filter, for reducing particle leakage and for reducing stress on the top portion of said filter when lateral or rotational force is applied to said filter; (d) a fuse connecting to the top of said tube sheet for preventing passage of said particle-containing gas in the event of failure of said filter or seal; (1) said fuse being open at a bottom portion and closed at a top portion; (2) wherein said open bottom portion of said fuse is in communication with and surrounds the open top portions of said filter and seal; (3) said fuse comprising a permeable material having a higher permeability than the permeability of said permeable filter material; (4) said permeable fuse material having not more than 25% of the surface area of said permeable filter material contained in said filter; and (5) wherein the permeability of the permeable material of said fuse is adapted to be sufficiently high wherein when passing said gas of said particle-containing gas through said filter and fuse, the sum of the pressure drop through the filter and fuse is not substantially greater than the pressure drop through said filter, and is adapted to be sufficiently low that in the event of failure of said filter or seal, the flow of said particle-containing gas through said fuse causes substantially complete blockage of said fuse; and (e) a backflushing conduit having an outlet disposed above said tube sheet, adapted to supplying a backflushing gas to the inside of said filter through the open top portion of said filter for removing solid particles collected on the outside of said filter and for not substantially removing particles collected on the inside of the fuse.

2. The fuse apparatus according to claim 1, said permeable fuse material having not more than 20% of the surface area of said permeable filter material contained in said filter.

3. The fuse apparatus according to claim 1, said permeable fuse material having not more than 15% of the surface area of said permeable filter material contained in said filter.

4. The fuse apparatus according to claim 1, said permeable fuse material having not more than 10% of the surface area of said permeable filter material contained in said filter.

5. The fuse apparatus according to claim 4, wherein said permeable fuse material comprises porous metal.

6. The fuse apparatus according to claim 4, wherein said permeable fuse material comprises porous ceramic.

7. The fuse apparatus according to claim 4, wherein said permeable filter material comprises porous metal.

8. The fuse apparatus according to claim 4, wherein said permeable filter material comprises porous ceramic.

9. The fuse apparatus according to claim 8, wherein said particle-containing gas comprises synthesis gas and flyash.

10. The fuse apparatus according to claim 8, wherein said particle-containing gas comprises flue gas and flyash.

11. The fuse apparatus according to claim 2, further comprising a connecting member for passing gaseous or particle effluent from said filter to said fuse, said connecting member being tubular and having a open top portion and open bottom portion, wherein said open top portion of said connecting member is in communication with and affixed to the open bottom portion of said fuse and the open bottom portion of said connecting member is in communication with and affixed to the top of said tube sheet.

12. A fuse apparatus for protecting process equipment and the environment from particle contamination comprising: (a) a vessel having a tube sheet affixed across a top portion of said vessel; (b) an elongated tubular filter comprising a permeable material selected from the group consisting of porous metal, porous ceramic, and mixtures thereof; (1) said filter having a closed bottom portion and an open top portion; (2) said open top portion of said filter being flexibly attached to the top of said tube sheet and said filter being disposed below said tube sheet; (3) the center axis of said filter being substantially aligned with the center axis of said vessel; and (4) said filter being for removing particles from particle-containing gas when synthesis gas containing flyash is passed from the outside of said filter to the inside of said filter; and (c) a seal constructed of a material selected from the group consisting of porous metal wool, mineral wool, porous ceramic fiber, glass fiber, and mixtures thereof; at least one seal removably disposed between said tube sheet and said filter, for reducing particle leakage and for reducing stress on the top portion of said filter when lateral or rotational force is applied to said filter; (d) a fuse connected to the top of said tube sheet for preventing passage of said particle-containing gas in the event of failure of one or more of said filter or seal; (1) said fuse being open at a bottom portion and closed at a top portion; (2) wherein said open bottom portion of said fuse is in communication with and surrounds the open top portion of said filter and seal;; (3) said fuse comprising a permeable material selected from the group consisting of porous metal, porous ceramic, and mixtures thereof; having a higher permeability than the permeability of said permeable filter material; (4) said permeable fuse material having not more than 20% of the surface area of said permeable filter material contained in said filter; and (5) wherein the permeability of the permeable material of said fuse is sufficiently high that when passing said gas of said particle-containing gas through said filter and fuse, the sum of the pressure drop through the filter and fuse is not more than 10% greater than the pressure drop through said filter, and is sufficiently low that in the event of failure of said filter or seal, the flow of said particle-containing gas through said fuse causes substantially complete blockage of said fuse; and (e) a connecting member for connecting said fuse to said tube sheet and for passing synthesis gas or flyash effluent from said filter to said fuse, said connecting member being tubular and having a open top portion and open bottom portion, wherein said open top portion of said connecting member is in communication with and affixed to the open bottom portion of said fuse and said open bottom portion of said connecting member is in communication with and affixed to the top of said tube sheet; and (f) a backflushing conduit having an outlet disposed above said tube sheet, adapted to supplying a backflushing gas to the inside of said filter through the open top portion of said filter for removing solid particles collected on the outside of said filter and for not substantially removing particles collected on the inside of the fuse.

13. The fuse apparatus according to claim 12, wherein said seal is constructed of a material selected from the group consisting of porous ceramic fiber, glass fiber, and mixtures thereof.

14. The fuse apparatus according to claim 12, wherein said connecting member is venturi shaped.

15. The fuse apparatus according to claim 14, wherein the permeability of the permeable material of said fuse is adapted wherein the passing of said gas of said particle-containing gas through said filter and fuse, causes the sum of the pressure drop through the filter and fuse to be not more than about 20 percent greater than the pressure drop through the filter.

16. The fuse apparatus according to claim 15, wherein the permeability of the permeable material of said fuse is adapted wherein the passing of said gas of said particle-containing gas through said filter and fuse, causes the sum of the pressure drop through the filter and fuse to be not more than about five percent greater than the pressure drop through the filter.

17. The fuse apparatus according to claim 15, wherein said backflushing conduit penetrates said fuse.

18. The fuse apparatus according to claim 15, wherein said backflushing conduit penetrates said connecting member.

19. The fuse apparatus according to claim 12, wherein said fuse is more robust than said filter.

20. A fuse apparatus for protecting process equipment and the environment from particle contamination comprising: (a) a vessel having a tube sheet affixed across a top portion of said vessel; (b) an elongated tubular filter comprising a permeable material selected from the group consisting of porous metal, porous ceramic, and mixtures thereof; (1) said open top portion of said filter being flexibly attached to the top of said tube sheet and said filter being disposed below said tube sheet; (2) the center axis of said filter being substantially aligned with the center axis of said vessel; and (3) said filter being for removing particles from particle-containing gas when synthesis gas containing flyash is passed from the outside of said filter to the inside of said filter; and (c) a seal constructed of porous ceramic fiber or glass fiber; at least one seal removably disposed between said tube sheet and said filter, for reducing particle leakage and for reducing stress on the top portion of said filter when lateral or rotational force is applied to said filter; (d) a fuse connected to the top of said tube sheet for preventing passage of said particle-containing gas in the event of failure of said filter or seal; (1) said fuse being open at a bottom portion and closed at a top portion; (2) wherein said open bottom portion of said fuse is in communication with and surrounds the open top portion of said filter and seal; (3) said fuse comprising a permeable material selected from the group consisting of porous metal, porous ceramic, and mixtures thereof; having a higher permeability than the permeability of said permeable filter material; (4) said permeable fuse material having not more than 10% of the surface area of said permeable filter material contained in said filter; (5) wherein the permeability of the permeable material of said fuse is sufficiently high that when passing said gas of said particle-containing gas through said filter and fuse, the sum of the pressure drop through the filter and fuse is not more than 10% greater than the pressure drop through said filter, and is sufficiently low that in the event of failure of one or more filter or seals, the flow of said particle-containing gas through said fuse causes substantially complete blockage of said fuse; and (6) said fuse being more robust than said filter; and (e) a venturi-shaped connecting member for connecting said fuse to said tube sheet and for passing synthesis gas or flyash effluent from said filter to said fuse, said connecting member being tubular and having a open top portion and open bottom portion, wherein said open top portion of said connecting member is in communication with and affixed to the open bottom portion of said fuse and said open bottom portion of said connecting member is in communication with and affixed to the top of said tube sheet; and (f) a backflushing conduit penetrating said fuse and having an outlet disposed above said tube sheet and below said permeable material of said fuse, adapted to supplying a backflushing gas to the inside of said filter through the open top portion of said filter for removing solid particles collected on the outside of said filter and for not substantially removing particles collected on the inside of the fuse.