Sealing structure for flue gas recirculation furnace bottom device of small gas boiler

Abstract

A sealing structure for a flue gas recirculation furnace bottom device of a small gas-fired boiler. The subcritical box-type gas-fired boiler adopts a low-oxygen combustion method. The flue gas for flue gas recirculation comes from the outlet of the economizer and is pressurized by two flue gas recirculation fans before being sent to the flue gas recirculation furnace bottom device to achieve flue gas recirculation. The components of the present invention include: a side water-cooled wall lower header (1), a front water-cooled wall tube panel (2), a rear water-cooled wall tube panel (8), a front water-cooled wall lower header (3), a rear water-cooled wall lower header (7) and a flue gas recirculation smoke box (5). The front side of the flue gas recirculation smoke box is welded to the front water-cooled wall tube panel and the side water-cooled wall lower header, and the rear side is welded to the rear water-cooled wall tube panel and the side water-cooled wall lower header by comb plate assemblies. The side water-cooled wall lower header and the guard plate (13) of the flue gas recirculation smoke box are welded to form a sealed box body by connecting steel plates (9). The present invention is a sealing structure for a flue gas recirculation furnace bottom device of a small gas-fired boiler.

Description

Technical Field

[0001] The invention relates to a sealing structure for a flue gas recirculation furnace bottom device of a small gas boiler. Background Art

[0002] In recent years, the steel mills have built coke oven gas boilers to generate electricity and improve the overall economy of the steel mills, which has reached a consensus in the industry. Under this market background, a subcritical box-type gas boiler with higher parameters that can better meet the market demand at the current stage has been developed, and it has quickly gained recognition from users for its superior and reliable performance characteristics, compact structure, good sealing and small footprint. This boiler adopts low-oxygen combustion, and the reheater system adopts flue gas recirculation temperature control. The flue gas for flue gas recirculation comes from the economizer outlet, and is pressurized by two flue gas recirculation fans and sent to the flue gas recirculation furnace bottom device to achieve flue gas recirculation. Summary of the invention

[0003] The object of the present invention is to provide a sealing structure for a flue gas recirculation furnace bottom device of a small gas boiler.

[0004] The above purpose is achieved through the following technical solutions:

[0005] A sealing structure for a flue gas recirculation furnace bottom device of a small gas boiler, comprising: a side water-cooled wall lower header, a front water-cooled wall tube panel, a rear water-cooled wall tube panel, a front water-cooled wall lower header, a rear water-cooled wall lower header and a flue gas recirculation smoke box, wherein the front side of the flue gas recirculation smoke box is welded with the front water-cooled wall tube panel and the side water-cooled wall lower header, and the rear side of the flue gas recirculation smoke box is welded with the rear water-cooled wall tube panel and the side water-cooled wall lower header respectively through comb plate assemblies, and the side water-cooled wall lower header and the guard plate of the flue gas recirculation smoke box are welded with connecting steel plates to form a sealed box body;

[0006] The comb plate assembly comprises two end comb plates and a plurality of connecting comb plates;

[0007] The two end comb plates and the plurality of connecting comb plates are arranged in parallel, one side of the end comb plates and the two sides of the connecting comb plates are provided with cutouts for absorbing thermal expansion differences, and the cutouts of two adjacent comb plates are butted to form an expansion gap;

[0008] A metal expansion joint is buckled on the expansion gap, the height of the metal expansion joint is longer than the length of the expansion gap, and the four sides of the metal expansion joint are welded to the comb-shaped plate.

[0009] The sealing structure for the flue gas recirculation furnace bottom device of a small gas boiler is characterized in that the bottom of the comb-shaped plate group is welded to the guard plate of the flue gas recirculation smoke box.

[0010] The sealing structure for the flue gas recirculation furnace bottom device of a small gas boiler is characterized in that: a plurality of upper notches are provided at the upper end of the end comb-shaped plate, a side notch is provided on one side, and a cutout is provided on the other side;

[0011] The upper end of the connecting comb plate is provided with a plurality of upper notches, and both sides have cutouts;

[0012] The two end comb plates and the plurality of connecting comb plates are arranged in parallel, the side water-cooled wall lower header is located in the side notch of the end comb plate and welded, and the front water-cooled wall lower header is located in the upper notch of the comb plate and welded.

[0013] The sealing structure for the flue gas recirculation furnace bottom device of a small gas boiler is characterized in that the side notches and the upper notches are both semicircular notches. Beneficial Effects

[0014] 1. The sealing structure of the present invention can suspend the flue gas recirculation furnace bottom device at the lower part of the furnace to form a sealed box structure, which expands with the furnace without restricting the thermal expansion of the flue itself and the relative thermal displacement between the flue and the header and water-cooled wall.

[0015] The lower part of the side underwater header of the present invention is sealed by directly welding the connecting steel plate to the smoke recirculation smoke box guard plate, which can reduce the volume of the smoke recirculation furnace bottom device and increase the smoke speed of the gas boiler combustion.

[0016] The present invention forms an expansion gap by opening a notch on the side of the comb-shaped plate. The notches of two adjacent comb-shaped plates form an expansion gap, which can absorb the thermal expansion difference between the front and rear water-cooled wall tube panels and the sealing comb-shaped plate caused by the different temperatures between the two. A metal expansion joint is designed at this gap. The expansion joint is generally longer than the notch in the height direction to ensure that the expansion joint can be completely sealed. The expansion joint is sealed and welded to the sealing comb-shaped plate around it to ensure the sealing of the box. This expansion joint can absorb the thermal expansion of the boiler in the left and right directions. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Attached Figure 1 It is a schematic diagram of the structure of the present invention;

[0018] Attached Figure 2 Yes Figure 1 AA section view;

[0019] Attached Figure 3 Yes Figure 2 FF section view;

[0020] Attached Figure 4 Yes Figure 3 K-direction schematic diagram;

[0021] Attached Figure 5 It is a structural schematic diagram of the end comb plate;

[0022] Attached Figure 6 It is a schematic diagram of the structure of connecting the comb plates;

[0023] In the figure: 1. Side water-cooled wall lower header; 2. Front water-cooled wall tube screen; 3. Front water-cooled wall lower header; 4. Comb plate; 5. Flue gas recirculation smoke box; 6. Metal expansion joint; 7. Rear water-cooled wall lower header; 8. Rear water-cooled wall tube screen; 9. Connecting steel plate; 10. End comb plate; 11. Connecting comb plate; 12. Side notch; 13. Guard plate; 14. Upper notch; 15. Incision. DETAILED DESCRIPTION Example 1

[0024] A sealing structure for a flue gas recirculation furnace bottom device of a small gas boiler, comprising: a side water-cooled wall lower header 1, a front water-cooled wall tube panel 2, a rear water-cooled wall tube panel 8, a front water-cooled wall lower header 3, a rear water-cooled wall lower header 7 and a flue gas recirculation smoke box 5, wherein the front side of the flue gas recirculation smoke box is welded to the front water-cooled wall tube panel and the side water-cooled wall lower header, and the rear side of the flue gas recirculation smoke box is welded to the rear water-cooled wall tube panel and the side water-cooled wall lower header respectively through comb plate assemblies, and the side water-cooled wall lower header and the guard plate 13 of the flue gas recirculation smoke box are welded to form a sealed box body through a connecting steel plate 9;

[0025] The comb plate assembly comprises two end comb plates 10 and a plurality of connecting comb plates 11;

[0026] The two end comb plates and the plurality of connecting comb plates are arranged in parallel, one side of the end comb plates and the two sides of the connecting comb plates are provided with cutouts 15 for absorbing thermal expansion differences, and the cutouts of two adjacent comb plates are butted to form an expansion gap;

[0027] A metal expansion joint 6 is buckled on the expansion gap. The height of the metal expansion joint is longer than the length of the expansion gap. The four sides of the metal expansion joint are welded to the comb-shaped plate. Example 2

[0028] According to the sealing structure for the flue gas recirculation furnace bottom device of a small gas boiler described in Example 1, the bottom of the comb plate group is welded to the guard plate of the flue gas recirculation smoke box. Example 3

[0029] According to the sealing structure for the flue gas recirculation furnace bottom device of a small gas boiler described in Example 1 or 2, the upper end of the end comb plate is provided with a plurality of upper notches 14, a side notch 12 is provided on one side, and a notch 15 is provided on the other side;

[0030] The upper end of the connecting comb plate is provided with a plurality of upper notches, and both sides have cutouts;

[0031] The two end comb plates and the plurality of connecting comb plates are arranged in parallel, the side water-cooled wall lower header is located in the side notch of the end comb plate and welded, and the front water-cooled wall lower header is located in the upper notch of the comb plate and welded. Example 4

[0032] According to the sealing structure for a flue gas recirculation furnace bottom device of a small gas boiler described in Example 1, 2 or 3, the side notches and the upper notches are both semicircular notches.

Claims

1. A sealing structure for a flue gas recirculation furnace bottom device of a small gas boiler, comprising: The side water-cooled wall lower header, the front water-cooled wall tube panel, the rear water-cooled wall tube panel, the front water-cooled wall lower header, the rear water-cooled wall lower header and the flue gas recirculation smoke box are characterized in that: the front side of the flue gas recirculation smoke box and the front water-cooled wall tube panel and the side water-cooled wall lower header are welded by comb plate assemblies, and the rear side and the rear water-cooled wall tube panel and the side water-cooled wall lower header are welded by connecting steel plates to form a sealed box body; The comb plate assembly comprises two end comb plates and a plurality of connecting comb plates; The two end comb plates and the plurality of connecting comb plates are arranged in parallel, one side of the end comb plates and the two sides of the connecting comb plates are provided with cutouts for absorbing thermal expansion differences, and the cutouts of two adjacent comb plates are butted to form an expansion gap; A metal expansion joint is buckled on the expansion gap, the height of the metal expansion joint is longer than the length of the expansion gap, and the four sides of the metal expansion joint are welded to the end comb plate and / or the connecting comb plate.

2. The sealing structure for a flue gas recirculation furnace bottom device of a small gas boiler according to claim 1 is characterized in that: The bottom of the comb plate assembly is welded to the guard plate of the flue gas recirculation smoke box.

3. The sealing structure for a flue gas recirculation furnace bottom device of a small gas boiler according to claim 2 is characterized in that: The upper end of the end comb plate is provided with a plurality of upper notches, a side notch is provided on one side, and a notch is provided on the other side; The upper end of the connecting comb plate is provided with a plurality of upper notches, and both sides have cutouts; The side water-cooled wall lower header is located in the side notch of the end comb-shaped plate and welded, and the front water-cooled wall lower header is located in the upper notch of the end comb-shaped plate and / or the connecting comb-shaped plate and welded.

4. The sealing structure for a flue gas recirculation furnace bottom device of a small gas boiler according to claim 3 is characterized in that: The side notches and the upper notches are both semicircular notches.

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