Abstract
The present disclosure describes an assembly configured to mitigate the harmful effects of smelt fouling, airflow interference, and operator exposure to hot air from the furnace and wind box through use of an extractable startup burner and an isolation chamber engaged to a windbox. The present disclosure also describes a method for safely extracting a startup burner from an active recovery boiler as has method for inserting an extractable startup burner into a recovery boiler during operation.
Claims
1. A multi-door isolation chamber and removable startup burner assembly configured to engage a recovery boiler furnace wall around an opening in a recovery boiler furnace, the multi-door isolation chamber and removable startup burner assembly comprising: a removable startup burner; a housing; an inner door configured to selectively occlude a first multi-door isolation chamber opening defined by a side of the housing; an outer door distally disposed from the inner door, wherein the outer door is configured to selectively occlude a second multi-door isolation chamber opening defined by an outer face of the multi-door isolation chamber; and an internal space defined by the housing, the inner door, and the outer door, wherein the internal space is configured to encompass the removable startup burner, wherein the internal space is configured to isolate an extracted portion of the removable startup burner, and wherein the internal space is configured to align with the opening in the recovery boiler furnace.
2. The multi-door isolation chamber of claim 1, wherein the inner door further comprises a first inner door opposite a second inner door.
3. The multi-door isolation chamber of claim 2, wherein the first inner door further comprises a cut-out section configured to complement a portion of a perimeter of the removable startup burner.
4. The multi-door isolation chamber of claim 3, wherein the second inner door is configured to complement the cut-out section of the first inner door in a closed position.
5. The multi-door isolation chamber of claim 2, wherein the first inner door and second inner door further comprise a runner slidably engaged to a track disposed proximate to an inner wall of the multi-door isolation chamber.
6. The multi-door isolation chamber of claim 2, wherein the first inner door and the second inner door are hingedly mounted proximate to an inner wall of the multi-door isolation chamber.
7. The multi-door isolation chamber of claim 1, wherein the recovery boiler furnace wall is a windbox.
8. The multi-door isolation chamber of claim 1 further comprising a support engaged to the housing, wherein the support is configured to support the removable startup burner.
9. The multi-door isolation chamber of claim 1, wherein the outer door further comprises a first outer door opposite a second outer door, wherein the first outer door and second outer door further comprise a cut-out section configured to complement a portion of a perimeter of the removable startup burner.
10. An isolation chamber and removable startup burner assembly comprising: a removable startup burner; a housing, the housing having at least one side wall defining an internal space, the at least one side wall having an inner wall surface, wherein the internal space is configured to encompass the removable startup burner, wherein the housing is configured engage a recovery boiler furnace wall around an opening, and wherein the internal space is configured to align with the opening in the recovery boiler furnace; a valve disposed at a first end of the housing, wherein the valve is configured to separate the internal space from the opening in the recovery boiler furnace wall when the removable startup burner is not extending through the valve; and a plug having an area configured to be disposed within the internal space, such that an outer perimeter of the plug forms a seal with the inner wall surface.
11. The isolation chamber of claim 10, wherein the housing is a burner guide sleeve.
12. The isolation chamber of claim 10, wherein the recovery boiler furnace wall is a windbox.
13. The isolation chamber of claim 12, wherein the housing is disposed in the windbox.
14. The isolation chamber of claim 12, wherein the plug comprises poly-amide-based plastic or other high-density, lightweight material configured to withstand air temperature in the windbox.
15. The isolation chamber of claim 10, wherein the valve is a flapper valve.
16. The isolation chamber of claim 14, wherein the housing further comprises a front lip at the first end, and wherein a flapper valve is hingedly engaged to the housing such that the flapper valve is disposed on the front lip when the removable startup burner is not extending through the flapper valve.
17. The isolation chamber of claim 10, wherein the plug further defines a plug orifice, and wherein the removable startup burner is configured to be disposed in the plug orifice such that a body of the removable startup burner creates a seal with the plug.
18. The isolation chamber of claim 17, wherein the body of the removable startup burner is configured to slide through the plug orifice.
19. The isolation chamber of claim 10, wherein a length of the area of the plug disposed within the internal space corresponds to a distance between the valve and a second end of the housing.
20. An isolation chamber comprising: a housing, the housing having at least one side wall defining an internal space, the at least one side wall having an inner wall surface, wherein the internal space is configured to encompass a removable startup burner, wherein the housing is configured to engage with a recovery boiler furnace wall around an opening, and wherein the internal space is configured to align with the opening in the recovery boiler furnace; a valve disposed at a first end of the housing, wherein the valve is configured to separate the internal space from the opening in the recovery boiler furnace wall when the removable startup burner is not extending through the valve, wherein the housing further comprises a front lip at the first end, and wherein the valve is a flapper valve hingedly engaged to the housing such that the flapper valve is disposed on the front lip when the removable startup burner is not extending through the flapper valve; and a plug having an area configured to be disposed within the internal space, such that an outer perimeter of the plug forms a seal with the inner wall surface.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) The foregoing will be apparent from the following more particular description of exemplary embodiments of the disclosure, as illustrated in the accompanying drawings. The drawings are not necessarily to scale, with emphasis instead being placed upon illustrating the disclosed embodiments.
(2) FIG. 1 is a side-view of an exemplary embodiment of a recovery boiler with windboxes and several multi-door isolation chambers engaged to the sides of the windboxes.
(3) FIG. 2a is a perspective view of an exemplary embodiment of the multi-door isolation chamber, the windbox, and the path by which the startup burner may be removed from the windbox.
(4) FIG. 2b is a cross-sectional view of an exemplary embodiment of the multi-door isolation chamber, the windbox, and the path by which the startup burner may be removed from the windbox.
(5) FIG. 3 is a burner end view of an exemplary embodiment of the multi-door isolation chamber, the throat, and the swirler with the outer doors of the multi-door isolation chamber engaged to the front plate of the multi-door isolation chamber via hinges.
(6) FIG. 4 is a top-down view of an exemplary embodiment of the multi-door isolation chamber mounted to the outer wall of the chemical recovery boiler and the startup burner extending through the windbox and into the furnace.
(7) FIG. 5a is a front view of an exemplary first inner door and second inner door of the multi-door isolation chamber configured to substantially completely isolate a startup burner in the multi-door isolation chamber.
(8) FIG. 5b a front view of an exemplary embodiment of the first inner door and second inner door of the multi-door isolation chamber that are slidably engaged proximate to the windbox along a track.
(9) FIG. 6a is a side view of an exemplary cooling carriage affixed to the outer wall of a windbox.
(10) FIG. 6b is a front view of an exemplary cooling carriage depicting the extended carriage's position relative to the multi-door isolation chamber.
(11) FIG. 7 is a side view of an exemplary burner guide sleeve with a plug and flapper seal.
DETAILED DESCRIPTION OF THE INVENTION
(12) The following detailed description of the preferred embodiments is presented only for illustrative and descriptive purposes and is not intended to be exhaustive or to limit the scope and spirit of the invention. The embodiments were selected and described to best explain the principles of the invention and its practical application. One of ordinary skill in the art will recognize that many variations can be made to the invention disclosed in this specification without departing from the scope and spirit of the invention.
(13) Although the drawings represent embodiments of various features and components according to the present disclosure, the drawings are not necessarily to scale and certain features may be exaggerated in order to better illustrate embodiments of the present disclosure, and such exemplifications are not to be construed as limiting the scope of the present disclosure.
(14) The present disclosure describes an isolation chamber that may be used with a startup burner configured to be removed or replaced while the boiler is operating. Natural gas, oil, propane, or other fuel known to those having ordinary skill in the art may fuel the startup burner. Although the startup burner may be used in boilers or process furnaces generally, subsequent exemplary uses will refer to recovery boilers used in the pulp and paper industry.
(15) FIG. 1 depicts an exemplary embodiment of the isolation chamber 106 attached to windboxes 190 of a recovery boiler 107. The windboxes 190 generally span the sides of the furnace 199 horizontally and may contain throats (FIG. 2, 240), housings (FIG. 4, 491), startup burners (FIG. 2, 200), or other instruments such as air nozzles or probes to record furnace conditions (not depicted). Recovery boilers 107 generally have a primary windbox 190a, a secondary windbox 190b, and tertiary windbox 190c spanning the sides of the furnace 199. The primary windbox 190a is generally closest to the ground and the tertiary windbox 190c is generally furthest from the ground. In certain exemplary embodiments, exemplary isolation chambers 106 may be attached to the primary windbox 190a and secondary windbox 190b. In other embodiments, at least one exemplary isolation chamber 106 may be attached to the primary windbox 190a. In still other embodiments, exemplary isolation chambers 106 may be attached to any one of the primary windbox 190a, secondary windbox 190b, or tertiary windbox 190c. In other exemplary embodiments, at least one exemplary isolation chamber 106 may be attached to each of the primary windbox 190a, secondary windbox 190b, and tertiary windbox 190c.
(16) FIG. 2a depicts a perspective view of the exemplary multi-door isolation chamber 206 engaged to a mounting plate 218 secured to the outer wall 222 of the windbox 290. In this exemplary embodiment, the multi-door isolation chamber 206 is generally in the shape of a rectangular prism (i.e. box-shaped); however, on other embodiments, the multi-door isolation chamber 206 may be generally cylindrical, generally in the shape of a geometric prism having greater than three edges, or generally irregularly shaped. A generally irregularly shaped isolation chamber 206 may have a sample cross sectional area at a first position (e.g. a measurement of cross sectional area measured along a first plane) that differs from a sample cross sectional area at a second position (e.g. a measurement of cross sectional area measured along a second plane parallel to the first plane).
(17) The startup burner 200 may comprise an inlet 207 through which natural gas, air, or other fuel enters the startup burner 200. The inlet 207 is generally located at the supply end of the startup burner. The fuel generally flows along the length of the startup burner 200 and into the furnace 299. Air enters the furnace through throat 240, and may flow across swirler 250. The swirler rotates thereby aiding fuel and air mixing. Operators may monitor the fuel input and amount of air entering the furnace 299 from the windbox 290 to increase furnace temperature and melt or burn away smelt accumulations. During operation, a startup burner 200 may extend through the multi-door isolation chamber 206 and traverse the windbox 290. Water wall tubes 270 may bend to create an open area, which defines a throat 240. In other embodiments, the throats 240 may be further defined by a reinforcing element (not depicted) disposed within the opening defined by the water wall tubes 270. The reinforcing element may generally conform to the hole defined by the bend water wall tubes 270 and may be made from carbon steel or other material configured to withstand furnace heat.
(18) An exemplary startup burner assembly 241 may have an observation port 260 through which operators may view the inside of the windbox 290, throat 240, and furnace 299. An operator may look through the observation port 260 to determine the amount of smelt accumulation around the throat 240. If smelt has accumulated, an operator may insert a rod (not depicted) through port 251 to dislodge the smelt accumulations while the recovery boiler is operational. In an exemplary method, an operator may insert the rod through the multi-door isolation chamber 206.
(19) In the exemplary startup burner assembly 241 of FIG. 2a, the multi-door isolation chamber 206 is configured isolate the startup burner 200 from the furnace 299 and windbox 290 by using outer doors 210, 216 and inner doors (FIG. 2b 220, 226). The outer door comprises a bottom outer door 210 engaging handle 230b and a top outer door 216 engaging handle 230c. Handle 230d engages top inner door 226, while handle 230a engages bottom inner door 220. The outer doors 210, 216 and inner doors 220, 226 desirably open inwardly toward the furnace 299 and windbox 290. In this configuration, pressure generated by the furnace 299 and windbox 290 exerts an outward force on the inner doors 220, 226 and outer doors 210, 216. Inwardly opening doors may reduce the risk of sudden release of hot air and potential smelt splatter if the pivot mechanism 266 fails. If both inner doors 220, 226 and outer doors 210, 216 were configured to open outwardly, the pivot mechanisms 266 keeping the inner doors 220, 226 and outer doors 210, 216 closed would be more likely to experience prolonged stress due to the windbox-pressure and therefore be more likely to fail spontaneously and expose personnel and nearby equipment to hot, high-pressure air from the windbox 290. Although the inner doors 220, 226 and outer doors 210, 216 desirably open inwardly, other exemplary embodiments may comprise one or more inner doors 220, 226 and outer doors 210, 216 opening outwardly away from the windbox 290 and furnace 299. The bottom inner door 220 and bottom outer door 210 pivot at the bottom of the multi-door isolation chamber 206 in FIG. 2a. Likewise, the top inner door 226 and top outer door 216 pivot at the top of the multi-door isolation chamber 206. In other exemplary embodiments, the outer and inner door may comprise two or more doors, one or more of which may pivot on the right side of the isolation chamber 206, and one or more of which may pivot on the left side of the isolation chamber 206 (see FIG. 5). In other exemplary configurations, an odd number of outer doors may be used. In yet other embodiments, an odd number of inner doors may be used. The bottom outer door 210 may have a cut-out portion 213 configured to support the startup burner 200. The outer door may be a singular outer door. The inner door may be a singular inner door. Nothing in this disclosure limits the combination of aspects of one embodiment with aspects of one or more other embodiments.
(20) FIG. 2b is a cross sectional view of an exemplary startup burner assembly 241. The startup burner 200 may be extracted through the windbox 290 and bottom inner door 220 of the multi-door isolation chamber 206. Operators may then use handle 230a to close the bottom inner door 220 of the multi-door isolation chamber 206. In this exemplary embodiment, the bottom inner door 220 may be a plate of carbon steel or other material suitable to withstand the heat and pressure of the windbox 290 and an occasional splatter of black liquor (not pictured) through the throats 240 of the furnace 299. Bottom inner door 220 may be configured to provide support for the startup burner 200 as the startup burner 200 is extracted from the windbox 290. The bottom inner door 220, when closed, may occupy a portion of the opening 221 created in windbox mounting plate 218. In other exemplary embodiments, the bottom inner door 220, when closed, may be configured to occupy substantially all of the opening 221; in this manner, a portion of the startup burner 200 may be substantially completely isolated in the internal space 225 of the multi-door isolation chamber 206.
(21) In still other exemplary embodiments, the bottom inner door 220, when closed, may be configured to occupy half of the opening 221. In yet other exemplary embodiments, the bottom inner door 220, when closed, may be configured to occupy a portion of the opening 221. In this manner, a portion of the startup burner 200 may be partially isolated in the internal space 225 defined by the multi-door isolation chamber 206.
(22) Thus protected from the furnace environment and so isolated from the windbox 290, an operator may open the outer door 210 of the multi-door isolation chamber 206 and remove the startup burner 200 from the multi-door isolation chamber 206 with reduced risk of burns due to hot air or molten smelt. In addition to being protected, the operator, by extracting the startup burner 200, may extend the useful life of the startup burner 200 by removing the startup burner 200 from the recovery boiler completely. By having the startup burner 200 completely removed from the recovery boiler, the operator may maintain, repair, or replace the startup burner 200 while the recovery boiler is operational, while substantially eliminating the risk of injury from the recovery boiler.
(23) The outer doors 210, 216 and inner doors 220, 226 desirably open inwardly toward the windbox 290 and furnace 299. The pressure created by the furnace 299 and moving air within the windbox 290 exerts a force against the closed inner doors 220, 226 and outer doors 210, 216. By opening inwardly, the closed inner doors 220, 226 and outer doors 210, 216 remain locked in position, thereby reducing the risk that door failure will expose operators to immediate harm. An insulating liner 273 may be disposed within the multi-door isolation chamber 206.
(24) FIG. 3 depicts a burner end view of an exemplary multi-door isolation chamber 306 in which the outer doors 310, 316 and inner doors 320, 326 of the multi-door isolation chamber 306 have pivot mechanisms (see 266), which rotate outer doors 310, 316 and inner doors 320, 326 of the multi-door isolation chamber 306. This embodiment further comprises an observation port 360. The swirler 350 is disposed around the fuel nozzle tip 398 and of the startup burner 300. The fuel nozzle tip 398 is located at the firing end of the startup burner 300. In an exemplary method, an operator may look through the observation port 360 to determine the amount of smelt accumulation around the throat 340. If smelt has accumulated, an operator may insert a rod through the multi-door isolation chamber 306 to dislodge the smelt accumulations while the recovery boiler is operational. By inserting a rod through the exemplary multi-door isolation chamber 306, an operator may have a more direct path to the throat 340 and may avoid damage to the swirler 350, which may have been previously caused by poor visibility and suboptimal access due to mechanical interference. An operator may close the bottom inner door 320 to support the startup burner 300 while dislodging smelt. The closed bottom inner door 320 partially protects the operator from stray smelt splatter from the furnace 299. An operator may desirably close either the top outer door 316 or bottom outer door 310 to provide additional protection from stray smelt splatter when cleaning the throat 340. In other embodiments, an operator may extend the rod through a port 351 in the outer wall 322 of the windbox 290. When operators desire to ignite the startup burner 300, operators generally insert an igniter assembly (FIG. 4, 480) through mounting tube 383.
(25) FIG. 4 is a top-down view of an exemplary startup burner 400 and the swirler 450 extending through the multi-door isolation chamber 406 and the windbox 490 to engage the throat 440. Water wall tubes 470 form the envelope of the furnace 499 and absorb furnace heat. The startup burner 400 may be removed from the windbox 490 through a housing 491 that spans the length of the windbox 490. In some embodiments, the housing 491 may have a variable position damper 492 that may be opened and closed to allow air from the windbox 490 into the housing 491 and into the furnace 499 through the swirler 450 and throat 440. This air maintains combustion at the fuel nozzle tip 498 of the startup burner 400 when active. When the startup burner 400 is dormant or extracted, the variable position damper 492 may be closed substantially completely to prevent air from entering the furnace 499 through the throat 440. In other embodiments, the variable position dampener 492 may be partially open to accommodate a desired air flow.
(26) The startup burner 400 may further be removed from the windbox 490 and housing 491 by using the handle 430a to open the bottom inner door 220 of the multi-door isolation chamber 406 and by pulling the startup burner 400 through the internal space 425 of the multi-door isolation chamber 406. After closing the inner doors 220, 226 the startup burner 400 may be partially or substantially completely isolated. Once isolated, the startup burner 400 may be removed through the outer doors 210, 216 of the multi-door isolation chamber 406.
(27) An igniter assembly 480 of the startup burner 400 is depicted in this exemplary embodiment. The igniter assembly 480 may comprise an ionizing flame rod and spark rod 481 and intake ports 482. Air and natural gas may flow through these intake ports 482. A mounting tube 483 can position the igniter assembly 480. This igniter assembly 480 may further comprise safety equipment used to ensure continuous ignition at the fuel nozzle tip 498 of the startup burner 400. The swirler 450 stabilizes and shapes the main flame within the furnace 499. In an exemplary embodiment, the mounting tube 483 of the igniter assembly 480 can engage the outer wall 422 of the windbox 490 outside insulation chamber 406. In another exemplary embodiment, the igniter assembly 480 may be co-extensive with the startup burner 400 and access the windbox 490 through the isolation chamber 406. In an exemplary embodiment, a flapper valve 484 may be engaged to at least one end of the mounting tube 483. This flapper valve 484 may be used to prevent pressure loss from the windbox 490 when the igniter assembly 480 is not in place.
(28) FIG. 5a is an exemplary embodiment of the multi-door isolation chamber 206 comprising a first inner door 526 and a second inner door 527 that may rotate on a pivot mechanism 535 such as a hinge or slide along tracks 532 (shown in FIG. 5b). It is to be understood by one skilled in the art that outer doors (see FIG. 2, 210, 216) may be configured in similar manner to the inner doors 526, 527 as described herein. A multi-door isolation chamber 206 comprising two or more inner doors 526, 527 may be desirable to isolate the startup burner 500 completely in the multi-door isolation chamber 206 prior to extraction. By closing the two or more inner doors 526, 527, operators substantially reduce the probability that operators will contact stray droplets of liquor flung through the throat 440 of the furnace 499 because these inner doors 526, 527 may be used to close the opening 221 defined by the outer walls of the windbox 290. The first inner door 526 may have a cut-out section 523 configured to complement the perimeter 504 of the startup burner 500. The outer doors may have a cut-out section (see 213) configured to support the startup burner. The first inner door 526 may be substantially closed when removing the startup burner 500 (shown in FIG. 5b) such that the cut-out section 523 may be used to support the startup burner 500 as the startup burner 500 is extracted from the windbox 290 of the recovery boiler 107. Once the startup burner 500 is inside the multi-door isolation chamber 206, the second inner door 527 may be closed to substantially completely isolate the startup burner 500 in the multi-door isolation chamber 206. In this embodiment, the second inner door 527 has a flange 528 configured to complement the cut-out section 523 of the first inner door 526. In other embodiments, this flange 528 may be omitted. Although two inner doors 526, 527 are used, it is understood that configurations of inner and outer doors known to those having ordinary skill in the art may be used to isolate the startup burner 500 from the windbox environment and furnace environment.
(29) FIG. 5b depicts an exemplary multi-door isolation chamber 206, which comprises a first inner door 526 and a second inner door 527, each having runners 531 configured to slide along tracks 532 disposed on the windbox mounting plate 218. In other embodiments, these tracks 532 may be engaged to the inner wall of the multi-door isolation chamber 406. In still other embodiments, one track per first and second inner door may be utilized. The first inner door 526 may have a cut-out section 523 configured to complement the perimeter 504 of the startup burner 500. The first inner door 526 may be substantially closed when removing the startup burner 500 such that the cut-out section 523 may be used to support the startup burner 500 as the startup burner 500 is extracted from the windbox 290 of the recovery boiler 107. Once the startup burner 500 is inside the multi-door isolation chamber 206, the second inner door 527 may be closed to substantially isolate the startup burner 500 in the multi-door isolation chamber 206. In this embodiment, the second inner door 527 has a flange 528 configured to complement the cut-out section 523 of the first inner door 526. In other embodiments, this flange 528 may be omitted.
(30) FIG. 6a is a side view of an exemplary cooling carriage 642 that may be used to hold the startup burner 600 and permit cooling after the startup burner 600 has been removed from the multi-door isolation chamber 606. In this exemplary embodiment, a structural brace 644 having a first end 643 and a second end 645 may be mounted to the outer wall 622 of the windbox 690. In another exemplary embodiment, the second end 645 may be mounted to the recovery boiler 107 such that the cooling carriage 642 remains aligned with the isolation chamber 606 as the recovery boiler expands during operations. A main support beam 648 may have a first end 647 attached to the first end of the structural brace 643 and a second end 649 perpendicularly attached to the outer wall 622 of the windbox 690. In another exemplary embodiment, the second end 649 may be mounted to the recovery boiler 107 such that the cooling carriage 642 remains aligned with the isolation chamber 606 as the recovery boiler expands during operations. A carriage assembly linkage 655 may be rotatably mounted to the main support beam 648 such that the carriage assembly linkage 655 may be secured away from the path 602 of the startup burner 600 when not in use. Rollers 657 may be mounted on at least one end of the carriage assembly linkage 655. These rollers 657 may extend below the path 602 of the startup burner 600 and support the startup burner 600 after the startup burner 600 has been removed from the multi-door isolation chamber 606. Operators may remove the startup burner 600 from the cooling carriage 642 after the fuel nozzle tip 698 of the startup burner 600 has cooled. In other embodiments, at least one clamp, ring, hook, or other similar securing means (not shown) may be used singularly or in combination with other securing means to support the startup burner 600 as it cools.
(31) In an exemplary method, operators may deactivate the startup burner 600 and extract the startup burner 600 and swirler 650 through the housing 691. Operators may then close an inner door 620 and rest the bottom of the startup burner 603 on a cut-out portion 623 of an inner door 620. Once the inner door 620 is closed, operators may pull the startup burner 600 through the internal space 425 of the multi-door isolation chamber 606 and through the outer door of the multi-door isolation chamber 610. Operators may then place the startup burner 600 on the rollers 657 of the carriage assembly linkage 655 and allow the startup burner 600 to cool. Once cool, the operators may remove the startup burner 600 from the cooling carriage 642 and store the cooling carriage 642 away until further needed.
(32) In another exemplary method, the inner door 620 need not be closed before the operator removes the startup burner 600 from the multi-door isolation chamber 606.
(33) FIG. 6b is a front view of an exemplary cooling carriage 642. The elements correspond to the elements described in FIG. 6a. In this exemplary embodiment, the rollers 657 may be contoured to support the startup burner 600 either singularly or in combination with at least one other roller.
(34) FIG. 7 depicts an alternative exemplary isolation chamber in the form of a burner guide sleeve 775. This exemplary burner guide sleeve 775 comprises a plug 771 at an outer end 777 of the burner guide sleeve 775 and a flapper valve 784 at an inner end 778 of the burner guide sleeve 775. The burner guide sleeve 775 generally extends into the windbox 790 and may support the startup burner 700 at least partially. The plug 771 may be used to prevent hot air flow from the windbox 790 when the startup burner 700 is in use. The plug 771 may be fixed to the startup burner 700. In another embodiment, the plug 770 may be slidably engaged to the startup burner 700. The plug may be made from a high-density, lightweight material configured to withstand air temperature in the windbox 790. The plug 771 may desirably fill the inner perimeter of the guide sleeve 775 so as to form a seal. In embodiments where the plug 771 is fixed to the startup burner 700, the length 708 of the plug may be at least the length 709 of the distance between the flapper valve 776 and the throat 740. In embodiments where the plug 771 is not fixed to the startup burner 700 but is still configured to maintain a seal, the length 708 of the plug 771 may be less than the length 709 between the flapper valve 776 to the throat 740. In exemplary embodiments in which the startup burner has been extracted from the windbox, the plug 771 may desirably fill the inner perimeter of the guide sleeve and extend through the windbox in substantially the same manner as the startup burner 700 such that the plug 771 may have an end corresponding to the firing end of the startup burner 700 and swirler 750 that substantially blocks the hole left by the extracted swirler 750. The plug 771 may be made of a material generally known in the art, including a poly-amide-based plastic, or other suitable material configured to withstand the heat of the recovery boiler.
(35) The flapper valve 784 may rest on the startup burner 700 when the startup burner 700 interfaces with the throat 740 and furnace 799. When the startup burner 700 is removed past the flapper valve 784, the flapper valve 784 generally closes and rests on the front lip 794 of the guide sleeve 775 at an angle A. The burner guide sleeve 775 may extend partially through the housing 791 within the windbox 790.
(36) It will be understood that the modifications of FIGS. 3 through 7 could be employed in combination with one another as well as individually in the assembly of FIG. 1 and the assembly illustrated in FIG. 2.
(37) While this invention has been particularly shown and described with references to exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention encompassed by the appended claims.
