EP0298671A2

EP0298671A2 - Cyclone separator having water-steam cooled walls

Info

Publication number: EP0298671A2
Application number: EP88306056A
Authority: EP
Inventors: Byram J. Magol; John David Fay; Michael Garkawe
Original assignee: Foster Wheeler Energy Corp
Current assignee: Foster Wheeler Energy Corp
Priority date: 1987-07-06
Filing date: 1988-07-01
Publication date: 1989-01-11
Also published as: JPS6480456A; EP0298671A3; JPH0418906B2; AU617675B2; AU1872588A

Abstract

A cyclone separator has an outer cylinder is formed by a plurality of vertically-extending, spaced, parallel tubes and extends around an inner pipe in a coaxial relationship therewith to define an annular chamber. A portion of the tubes forming the outer cylinder are bent out of the plane of the cylinder to form an inlet opening in a tangential relationship to the annular chamber for receiving gases containing solid particles and directing same through the annular chamber for separating the solid particles from the gas by centrifugal forces. The tubes are bent radially inwardly towards the inner pipe to support the inner cylinder steam and/or water is passed through the tubes to cool the outer cylinder.

Description

This invention relates to a cyclone separator and, more particularly, to such a separator for separating solid fuel particles from gases discharged from a combustion system or the like.
Conventional cyclone separators are normally provided with a monolithic external refractory wall which is abrasion resistant and insulative so that the outer casing runs relatively cool. Typically, these walls are formed by an insulative refractory material sandwiched between an inner hard refractory material and an outer metal casing. In order to achieve proper insulation, these layers must be relatively thick which adds to the bulk, weight, and cost of the separator. Also, the outside metal casing of these designs cannot be further insulated from the outside since to do so could raise its temperature as high as 815°C(1500°F) which is far in excess of the maximum temperature it can tolerate.
Further, most conventional cyclone separators require relatively expensive, high temperature, refractory-lined ductwork and expansion joints between the reactor and the cyclone, and between the cyclone and the heat recovery section, which are fairly sophisticated and expensive. Still further, conventional separators formed in the above manner require a relatively long time to heat up before going online to eliminate premature cracking of the refractory walls, which is inconvenient and adds to the cost of the process. Also these type of conventional cyclone separators require a separate roof tube circuit which further adds to the cost of the system.
The present invention is therefore directed at a cyclone separator in which heat losses are reduced and the requirement for internal refractory insulation is minimized. To this end, a cyclone separator according to this invention has an inner cyclinder and an outer cylinder defining an annular chamber therebetween, the outer cylinder comprising a plurality of tubes extending vertically in parallel relationship for at least a portion of their lengths, with the upper end portions thereof being bent inwardly to extend from the outer cylinder to the inner cylinder. Means are provided for directing gases with entrained particulate material into the annular chamber for substantially circular movement therearound to enable separation of particulate material from these gases by centrifugal forces, with the separated material falling to the bottom of the separator and the gases discharging upwardly from the separator through the inner cylinder. Provision is also made for passing steam and/or water through the tubes to cool the outer cylinder. Normally, a portion of the tubes forming the outer cylinder of the separator are bent out of the plane of the outer cylinder wall to form an inlet opening for receiving the gases and directing same tangentiallly into the annular chamber. The upper end portions of the tubes can be extended to form an outlet chamber for said discharged gases.
The inwardly extending portions of the tubes forming the outer cylinder of a separator according to the invention can be attached to the inner cyliner to support same. The inwardly extending tube portions can also be used to form a roof over the annular chamber. The upper end portions of the tubes can in some embodiments extend inwardly to the inner cylinder and thereafter outwardly from the inner cylinder. In such a case, the outwardly extending tube portions, rather than the inwardly extending portions, may form a roof over the annular chamber.
The tubes are usually disposed in a spaced relationship in the outer cylinder of a separator of the invention. In one embodiment, each tube has a continuous fin extending from diametrically opposite portions thereof, each fin being aligned with a corresponding fin on an adjacent tube. In another embodiment, a continuous fin extends between adjacent tubes to form a gas-tight structure.
A cyclone separator according to the invention will normally include some refractory lining for the outer cylinder. In one variant, a refractory material extends around the inner and outer surfaces of the outer cylinder. In another variant, a refractory material extnds around the inner surface of the outer cylinder and insulation, possibly of another material, around the outer surface thereof.
The means for passing steam and/or water through the tubes of the outer cylinder may take a number of formed. One such means comprises a ring header connected to the lower ends of the tubes, with an hopper extends downwardly from the ring header for receiving the separated particulate material. Another suitable means comprises a first ring header connected to the upper ends of the tubes and a second ring header connected to the lower ends of the tubes, from which an hopper may depend.
In cyclone separators according to the invention, upper and lower end portions of the tubes of the outer cylinder may be configured to form two opposite side walls of enclosures respectively above and below the outer cylind4er which thus comprises intermediate portions of the tubes. Another optional feature is the provision of a plurality of support tubes connected to the outer cylinder for supporting the separator relative to a building.
The bulk, weight, cost of separators of the invention can be much less than that of conventional separators. Particularly, a separator roof-type circuit is not necessarily required. The need for expensive high temperature refractor-lined ductwork and expansion joints between the furnace and the cyclone separator and between the latter and the heat recovery section can be substantially reduced or eliminated. Further, a cyclone separator of the invention can be put into use relatively quickly without any significant warm-up period. Additionally, the temperature of the outer walls of the separator can be maintained the same as the temperature of the walls of the adjoining reactor.
Embodiments of the invention will now be described by way of example and with reference to the accompanying drawings wherein:

Figure 1 is a perspective/schematic view of a cyclone separator according to a first embodiment of the invention showing only the tubes forming the outer cylinder;
Figure 2 is a cross-sectional view taken along the portion of the wall of the outer cylinder of Figure 1 designated by the line 2-2, and showing the insulative materials surrounding the tubes.
Figure 3 is a schematic view of a cyclone separator according to a second embodiment of the invention and an adjacent heat recovery area of a boiler system;
Figure 4 is an enlarged perspective view of the tubes forming the outer cylinder of the separator of Figure 3;
Figure 5 is an enlarged, cross-sectional view taken along the portion of the wall of the outer cylinder of Figure 3 designated by the line 5-5, and showing the insulative materials surrounding the tubes;
Figure 6 is a perspective/schematic view of a cyclone separator according to a third embodiment of the invention showing only the tubes forming the outer cyliners; and
Figure 7 is an enlarged, cross-sectional view taken along the portion of the wall of the outer cylinder of Figure 6 designated by the line 7-7, and showing the insulative materials surrounding the tubes.

Referring to Figure 1 of the drawings, the reference numeral 10 refers in general to the cyclone separator of the first embodiment which includes a front header 12 and a rear header 14 forming the lower end portion of a side wall 16 of the separator. A front header 18 and a rear header 20 form the lower end portion of the other side wall 22 of the separator. The headers 12, 14, 18 and 20 extend to either side of a hopper 21 disposed at the lower portion of the separator for reasons to be described.
A group of vertically extending spaced parallel tubes 24 are connected at their lower ends to the header 12 and form the front portion of the wall 16, and another group of vertically extending spaced parallel tubes 26 are connected to the header 14 and form the rear portion of the wall 16. In a similar manner, a group of vertically extending spaced parallel tubes 28 are connected to the header 18 and form the front portion of the wall 22, and another group of vertically extending spaced parallel tubes 30 extend from the header 20 and form the rear portion of the wall 22.
The groups of tubes 24, 26, 28 and 30 extend vertically upwardly for a relatively small length and then are bent inwardly and angularly so that they together form a closed right cylinder shown in general by the reference number 32, with the tubes 24 and 28 together forming the front half of the cylinder 32 and the tubes 26 and 30 together forming the rear half of the cylinder 32.
A portion of the tubes 24 and 28 are bent out of the plane of the cylinder 32 as shown by the reference numeral 24a and 28a to form an inlet passage to the interior of the cylinder for reasons that will be described.
At the upper end of the cylinder 32, the tubes 24, 26, 28 and 30 are bent radially inwardly, as shown by the reference numberal 36, and then upwardly, as shown by the reference numeral 38, to define a circular opening which, of course, is of a diameter less than that of the diameter of the cylinder 32. The tubes 24, 26, 28 and 30 are then bent radially outwardly as shown by the reference numeral 44 and then vertically upwardly as shown by the reference numeral 46. The upper end portions of the tube group 26 thus form a sidewall which is connected to an upper header 48 and the upper end portions of the tube group 30 form a sidewall which is connected to an upper header 50. The upper end portions of the tubes 24 and 28 are bent horizontally to extend across the upper end portion of the cylinder 32 to form a roof 52 and are connected at their free ends to upper headers 54 and 56, respectively. A portion of the upper portions of the tubes 24 and 26 have been deleted for the convenience of presentation.
It is understood that a portion of the tubes 24, 26, 28 and 30 do not bend in the manner discussed above but rather extend vertically for the entire length of the cylinder 32 for the purpose of enabling the separator to be supported from the roof of a building or structure in which the separator 10 is located. These latter tubes are shown by the reference numeral 60 and extend from the header 18 in the manner discussed above, then straight up for the length of the cylinder 32 before bending horizontally to form a portion of the roof 52. Although not shown in the drawings, it is understood that a plurality of lugs, or the like, are connected to the tubes 60 and are adapted to tbe connected to hangers, or the like (not shown), which extend from the roof of the building to support the separator 10 without the need for steel supports at the bottom of the cylinders. It is also understood that the tubes 60 can be spaced out over the entire diameter of the cylinder 32, as needed.
An inner pipe, or barrel 61 is disposed within the cylinder 32 and is formed from a solid, metallic material such as stainless steel, and has an upper end portion extending approximately flush with the opening formed by the vertical bent tube portions 38. The pipe 61 extends from the latter opening to an area coincidental with the inlet formed by the bent tube groups 24a and 28a. Thus an annular passage is formed between the outer surface of the pipe 61 and the inner surface of the cylinder 32, for reasons that will be described.
The tubes 24, 26, 28 and 30 are disposed between an insulative material and an erosion preventing structure which are omitted from Figure 1 for the convenience of presentation but which are shown in Figure 2. More particularly, the details of a wall portion of the cylinder 32 formed by the group of tubes 24 are shown in Figure 2. More particularly, each tube 24 has a pair of fins 62 and 64 extending from diametrically opposed portions of its wall, with a slight spacing being provided between the fin 62 of one tube and the fin 64 of an adjacent tube. A seal plate 66 is provided in a slightly spaced relationship to the plane of the tubes 24 and a heat insulative refractory material is disposed between the outer surface of the tubes and the inner wall of the seal plate. A plurality of tiles 70 extend adjacent the inner wall of the tubes 24 and are interlocked to protect the tubes from erosion.
In operation, and assuming the separator 10 is part of a boiler system including a fluidized bed reactor, or the like, disposed adjacent the separator, the inlet formed by the bent tubes 24a and 28a receives hot gases from the reactor which gases contain entrained fine solid particulate fuel material from the fluidized bed. The gases containing the particulate material thus swirl around the annular chamber defined between the cylinder 32 and the inner pipe 61 and the solid particles are propelled by centrifugal forces against the inner wall of the cylinder 32 where they collect and fall downwardly by gravity into the hopper in a conventional manner.
The relatively clean gases in the annular chamber are prevented from flowing upwardly by the roof 52 and thus pass into and through the inner pipe 61 before exiting in a direction shown by the arrows in Figure 1 through an outlet defined by the sidewalls connected to the headers 48 and 50. It is understood that a plurality of screen tubes (not shown) can be provided in the path of the gases exiting in this manner and the gases can then pass to a heat recovery area disposed adjacent the separator 10.
Water from an external source is passed into the headers 12, 14, 18 and 20 and thus passes upwardly through the groups of tubes 24, 26, 28 and 30 before exiting, via the headers 48, 50, 54 and 56, to external circuitry which may form a portion of the boiler system including the separator 10.
It is understood that several variations may be made in the foregoing. For example, the fins 62 and 64 extending from each tube can be welded together to form a gas tight structure or, alternatively, can be eliminated and the tubes welded directly together.
In the embodiment of Figures 3 and 4, the reference numeral 110 refers in general to the cyclone separator of the second embodiment which includes a lower ring header 112 and an upper header 114. The header 112 extends immediately above, and is connected to, a hopper 116 disposed at the lower portion of the separator 110.
A group of vertically-extending, spaced, parallel tubes 120 are connected at their lower ends to the header 112 and extend vertically for the greater parts of their lengths to form a right circular cylinder 122.
A portion of the tubes 120 are bent out of the plane of the cylinder 122, as shown by the reference numerals 120a, and, as shown in Figure 4, approximately half of these bent tube portions are bent away from the other half to form an inlet passage 124 to the interior of the cylinder for reasons that will be described.
At the upper end of the cylinder 122 and tubes 120 are bent radially inwardly, as shown by the reference numeral 120b and then upwardly as shown by the reference numeral 120c, to define a circular opening which, of course, is of a diameter less than that of the diameter of the cylinder 122. The tubes 120 are then bent radially outwardly as shown by the reference numeral 120d, and a portion of these bent tube portions 120d are bent upwardly as shown by the reference numeral 120e. As better shown in Figure 4 the best tube portions 120e form approximately one-half of a right circular cylinder 126. The remaining portions of the bent tube portions 120d extend horizontally are bent at right angles in a horizontal plane, and then vertically, as shown by the reference numeral 120f, to form two vertically extending, spaced walls one of which is shown by the reference numeral 128. The tube portions 120e and the vertically extending tube portions 120f are bent to form horizontal tube portions 120g which form a roof 130 for an enclosure 132 defined by the tube portions 120d, the partial cylinder 126 and the walls 128.
The enclosure 132 has an outlet opening 132a which discharges to a heat recovery area, shown in general by the reference numeral 136.
The lower header 112 can be connected to a source of cooling fluid, such as water which passes from the header 112, through the tubes 120, and into the upper header 114 which is converted to a header 137 forming a portion of the water flow circuitry of the heat recovery area 136.
An inner pipe, or barrel, 138 is disposed within the cylinder 122, is formed from a solid, metallic material, such as stainless steel, and has an upper end portion extending slightly above the plane of the tube portions 120d. The pipe 138 extends immediately adjacent the tube portions 120c, and its length substantially coincides with the inlet passage formed by the bent tube portions 120a. Thus, an annular Chamber 134 is formed between the outer surface of the pipe 138 and the inner surface of the cylinder 122, and the tube portions 120b form a roof for said chamber.
The tubes 120 are disposed between an insulative material and an erosion preventing structure which are omitted from Figure 4 for the convenience of presentation but which are shown in Figure 5. More particularly, a fin 140 is welded to, and extends from, the corresponding walls of each pair of adjacent tubes 120. A lagging, or panel 142 of a lightweight material, such as aluminum, is provided in a slightly spaced relationship to the plane of the tubes 120, and a heat insulative material 144 is disposed between the outer surface of the tubes 120 and the inner wall of the lagging 134. A plurality of tiles 146 extend adjacent the inner wall of the cylinder 122 and are connected by anchors 148 extending from the inner walls of the tubes 120. A layer of refractory material 150 is disposed between the tiles 146 and the tubes 120.
In operation, and assuming the separator 110 is part of a boiler system including a fluidized bed reactor, or the like, disposed adjacent to the separator, the inlet passage 124 formed by the bent tube portions 120a receives hot gases from the reactor which gases contain entrained fine solid particulate fuel, ash, limestone, etc. from the fluidized bed. The gases containing the particulate material thus enter and swirl around in the annular chamber 134 defined between the cylinder 122 and the inner pipe 138, and the entrained solid particles are propelled by centrifugal forces against the inner wall of the cylinder 122 where they collect and fall downwardly by gravity into the hopper 116. The relatively clean gases remaining in the annular chamber 134 are prevented from flowing upwardly by the roof formed by the tube portions 120b and their corresponding fins 140, and thus enter the pipe 138 through its lower end. The gases thus pass through the length of the pipe 138 before exiting from the upper end of the pipe to the enclosure 132 which directs the hot gases radially outwardly to the heat recovery area 136.
Water or steam from an external source is passed into the lower header 112 and passes upwardly through the tubes 120 before exiting, via the upper header 114 to the header 137 of the heat recovery area 136. The water thus maintains the cylinder 122 and the enclosure 132 at a relatively low temperature.
Referring to Figure 6 of the drawings, the reference numeral 210 refers in general to the cyclone separator of the third embodiment which includes a lower ring header 212 and an upper ring header 214. The header 212 extends immediately above, and is connected to, a hopper 216 disposed at the lower portion of the separator 210.
A group of vertically-extending, spaced, parallel tubes 220 are connected at their lower ends to the header 212 and extend vertically for the greater parts of their lengths to form a right circular cylinder 222.
A portion of the tubes 220 are bent out of the plane of the cylinder 222, as shown by the reference numerals 220a, to form an inlet passage 224 to the interior of the cylinder for reasons that will be described.
At the upper end of the cylinder 222 the tubes 220 are bent radially inwardly as shown by the reference numeral 220b, and then upwardly as shown by the reference numeral 220C to define a circular opening which, of course, is of a diameter less than that of the diameter of the cylinder 222. The tubes 220 are then bent radially outwardly as shown by the reference numeral 220d, with their respective ends being connected to the upper header 214. The tube portions 220b thus form a roof for the cyclone.
A plurality of vertical pipes 228 extend upwardly from the upper header 214, it being understood that the lower header 212 can be connected to a source of cooling fluid, such as water, or steam, which passes from the header 212, through the tubes 220, and into the upper header 214 before being discharged, via the pipes 228, to external equipment. The direction of flow for the cooling fluid could also be reversed.
An inner pipe, or barrel, 230 is disposed within the cylinder 222, is formed from a solid, metallic material, such as stainless steel, and has an upper end portion extending slightly above the plane formed by the header 214 and the upper tube portions 220d. The pipe 230 extends immediately adjacent the tube portions 220c, and its length approximately coincides with the inlet passage formed by the bent tube portions 220a. Thus, an annular passage is formed between the outer surface of the pipe 230 and the inner surface of the cylinder 222, for reasons that will be described, and the tube portions 220b form a roof for the chamber.
The tubes 220 are disposed between an insulative material and an erosion preventing structure which are omitted from Figure 6 for the convenience of presentation but which are shown in Figure 7. More particularly, a fin 232 is welded to, and extends from, the adjacent walls of each pair of adjacent tubes 220. A lagging, or panel 234 of a lightweight material, such as aluminum, is provided in a slightly spaced relationship to the plane of the tubes 220, and a heat insulative material 236 is disposed between the outer surface of the tubes 220 and the inner wall of the lagging 234. A plurality of tiles 238 extend adjacent the inner wall of the cylinder 222 and are connected by anchors 40 extending from the fins 232. A layer of refractory 242 is designed between the tiles 238 and the tubes 220.
It is understood that an upper hood, or the like (not shown), preferably rectangular in cross section, can be provided above the plane formed by the upper header 214 and the tube portions 220d and can be connected to the pipe 230 by a plurality of conical plates or the like (not shown). The hood can be top supported from the roof of the structure in which the separator 210 is placed and the remaining portion of the separator can be supported from hangers connected to header 214, or pipes 228.
In operation, and assuming the separator 210 is part of a boiler system including a fluidized bed reactor, or the like, disposed adjacent the separator, the inlet passage 224 formed by the bent tube portions 220a received hot gases from the reactor which gases contain entrained fine solid particulate fuel material from the fluidized bed. The gases containing the particulate material thus enter and swirl around in the annular chamber defined between the cylinder 222 and the inner pipe 230, and the entrained solid particles are propelled by centrifugal forces against the inner wall of the cylinder 222 where they collect and fall downwardly by gravity into the hopper 216. The relatively clean gases remaining in the annular chamber are prevented from flowing upwardly by the roof formed by the tube portions 220b and their corresponding fins 32, and thus enter the pipe 230 through its lower end. The gases thus pass through the length of the pipe before exiting from the upper end of the pipe to the aforementioned hood, or the like, for directing the hot gases to external equipment for further use.
Water, or steam from an external source is passed into the lower header 212 and passes upwardly through the tubes 220 before exiting, via the upper header 214 and the pipes 228, to external circuitry which may form a portion of the boiler system including the separator 210. The water thus maintains the wall of cylinder 222 at a relatively low temperature.
Several advantages result from the foregoing arrangements. For example, each separator described reduces heat losses and minimizes the requirement for internal refractory insulation. Also, the bulk, weight, and cost of the separator is much less than that of conventional separators. The invention also minimizes the need for expensive high temperature refractory-lined ductwork and expansion joints between the reactor and cyclone separator, and between the latter and the heat recovery section. Still further, by utilizing the tube portions to form a roof for the annular chamber between the cylinder and the pipe, the requirement for additional roof circuitry is eliminated.

Claims

1. A cyclone separator having an inner cylinder and an outer cylinder defining an annular chamber therebetween, the outer cylinder comprising a plurality of tubes extending vertically in parallel relationship for at least a portion of their lengths, with the upper end portions thereof being bent inwardly to extend from the outer cylinder to the inner cylinder; means for directing gases with entrained particulate material into the annular chamber for substantially circular movement therearound to enable separation of said particulate material from said gases by centrifugal forces, such separated material falling to the bottom of the separator and said gases discharging upwardly from the separator through the cylinder; and means for passing at least one of steam and water through the tubes to cool the outer cylinder.

2. A cyclone separator according to Claim 1 wherein a portion of said tubes are bent out of the plane of the outer cylinder to form an inlet opening for receiving said gases and directing same tangentially into the annular chamber.

3. A cyclone separator according to Claim 1 or Claim 2 wherein the inwardly extending portions of the tubes are attached to the inner cylinder to support same.

4. A cyclone separator according to Claim 3 wherein said inwardly extending tube portions form a roof over the annular chamber.

5. A cyclone separator according to Claim 3 or Claim 4 wherein said upper end portions of the tubes extend inwardly to the inner cylinder and thereafter outwardly from the inner cylinder.

6. A cyclone separator according to Claim 3 and Claim 5 wherein said outwardly extending tube portions form a roof over the annular chamber.

7. A cyclone separator according to any preceding Claim wherein the tubes are disposed in a spaced relationship.

8. A cyclone separator according to Claim 7 wherein each tube has a continuous fin extending from diametrically opposite portions thereof, each fin being aligned with a corresponding fin on an adjacent tube.

9. A cyclone separator according to Claim 7 wherein a continous fin extends between adjacent tubes to form a gas-tight structure.

10. A cyclone separator according to any preceding Claim including a refractory material extending around the inner and outer surfaces of the outer cylinder.

11. A cyclone separator according to any of Claims 1 to 9 including a refractory material extending around the inner surface of the outer cylinder and insulation around the outer surface thereof.

12. A cyclone separator according to any preceding Claim wherein the upper end portions of the tubes are extended to form an outlet chamber for said discharged gases.

13. A cyclone separator according to any preceding Claim wherein the passing means comprises a ring header connected to the lower ends of the tubes, and wherein an hopper extends downwardly from the ring header for receiving said separated particulate material.

14. A cyclone separator according to any of Claims 1 to 12 wherein the passing means comprises a first ring header connected to the upper ends of the tubes and a second ring header connected to the lower ends of the tubes.

15. A cyclone separator according to any preceding Claim wherein upper and lower end portions of the tubes are configured to form two opposite side walls of enclosures respectively above and below the outer cylinder comprising intermediate portions of the tubes.

16. A cyclone separator according to any preceding Claim including a plurality of support tubes connected to the outer cylinder for supporting the separator relative to a building.