Dry desulfurization system for flue gas of gas-fired boiler

Abstract

The invention belongs to the technical field of flue gas treatment, and particularly discloses a gas-fired boiler flue gas dry desulfurization system which comprises a gas-fired boiler and a slaked lime bin, the gas-fired boiler is communicated with a desulfurization tower through a flue gas pipeline, the slaked lime bin is communicated with the desulfurization tower through a desulfurization agent conveying pipeline, and four ash buckets are connected to the desulfurization tower in series. The fourth ash bucket is communicated with a chimney through a flue gas discharge pipe, the lower parts of the ash buckets are communicated with desulfurized fly ash pipelines, the desulfurized fly ash pipelines are connected with desulfurized fly ash bins, and the flue gas discharge pipe is provided with an induced draft fan. Aiming at the problem that a desulfurizing agent is deposited in a tower to form hardening due to high water content of slaked lime in a traditional semi-dry desulfurization process, the invention designs a flue gas dry desulfurization system to realize full-dry desulfurization treatment on boiler flue gas, so as to solve the problem that the water content of the slaked lime in the traditional semi-dry desulfurization process is high, and the boiler flue gas cannot be desulfurized easily. And desulfurized fly ash formed after reaction with flue gas is easy to deposit and harden in the desulfurization tower, so that the flue is blocked and normal circulation of the flue gas is influenced are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of flue gas treatment, and in particular to a flue gas dry desulfurization system for a gas boiler. Background Art

[0002] my country's energy source is mainly coal, which produces a large amount of pollutants when burned, such as coal smoke, dust, SO2, NO X According to statistics, more than 80% of air pollution comes from coal combustion, and acid rain and other hazards have occurred in seriously polluted areas. Although gas boilers emit fewer pollutants than coal boilers, they still produce sulfides such as sulfur dioxide during combustion, which pollute the atmosphere. With the tightening of environmental protection regulations, such as the ultra-low emission requirement that the SO2 concentration in the flue gas is ≤35mg / Nm 3 , and gas boiler flue gas desulfurization has gradually become a mandatory link in the steel, electricity and other industries. Therefore, it is very necessary to desulfurize the gas boiler flue gas.

[0003] Desulfurization processes can be categorized into wet, semi-dry, and dry desulfurization, depending on whether water is added during the desulfurization process and the dry and wet forms of the desulfurization products. Semi-dry desulfurization is the most commonly used desulfurization process. While widely used, the traditional semi-dry desulfurization process has certain drawbacks. It primarily involves reacting quicklime with water to produce slaked lime, which then neutralizes sulfides in the flue gas to produce solid products such as CaSO₄ (calcium sulfate). Water is then removed through a drying process, ultimately resulting in dry desulfurized ash. However, the slaked lime in this desulfurization process has a high water content, and the resulting desulfurized ash, formed after reacting with the flue gas, is prone to depositing on equipment surfaces, particularly on the ash hopper chute and the inner walls of the desulfurization tower, forming compaction. Severe compaction can lead to blockage of the desulfurization tower walls or inlet flue, impeding flue gas flow and even posing the risk of bed collapse. In this case, the entire desulfurization system must be shut down for cleaning, which not only consumes significant manpower and resources but also seriously impacts production continuity.

[0004] Therefore, in order to solve the above problems, it is necessary to design a dry desulfurization system for gas boiler flue gas to solve the problem that the traditional semi-dry desulfurization process has a high water content in slaked lime, and the desulfurization ash formed after reacting with the flue gas is easily deposited and compacted in the desulfurization tower, resulting in obstruction of the flue and affecting the normal circulation of the flue gas, which ultimately causes the desulfurization system to be shut down for cleaning and increases the labor intensity of the staff. Summary of the Invention

[0005] The purpose of the present invention is to provide a dry desulfurization system for flue gas from a gas boiler to solve the problem in the traditional semi-dry desulfurization process that the desulfurization ash formed after the reaction with the flue gas has a high water content in the slaked lime and is easily deposited and compacted in the desulfurization tower, resulting in obstruction of the flue and affecting the normal circulation of the flue gas.

[0006] To achieve the above-mentioned purpose, the basic scheme provided by the present invention is: a dry desulfurization system for flue gas from a gas-fired boiler, comprising a gas-fired boiler and a slaked lime silo, the gas-fired boiler being connected to a flue gas pipe, the flue gas pipe being provided with a flue gas control valve, the other end of the flue gas pipe being connected to a desulfurization tower, the slaked lime silo being provided with a variable frequency feeder, the variable frequency feeder being connected to a conveying pipe, the slaked lime silo and the desulfurization tower being connected through a conveying pipe, four ash hoppers being connected in series on the desulfurization tower, a rotary blowing system being provided above each of the ash hoppers, a desulfurization ash pipe being connected below each of the ash hoppers, a desulfurization ash pipe being connected to a desulfurization ash silo, the fourth ash hopper of the four ash hoppers in series being connected to a flue gas exhaust pipe, the other end of the flue gas exhaust pipe being connected to a chimney, and an induced draft fan being provided on the flue gas exhaust pipe.

[0007] The working principle of the present invention is as follows: first, the desulfurizer in the slaked lime bin is sprayed into the desulfurization tower through a frequency conversion feeder through a conveying pipe, and then the flue gas control valve is opened to allow the flue gas in the gas boiler to enter the desulfurization tower through the flue gas pipe, so that it reacts with the desulfurizer. The flue gas after the reaction enters four ash hoppers connected in series in turn, and the flue gas and desulfurizer are diverted through filter bags in the ash hopper, so that the desulfurizer adheres to the filter bags in the ash hopper, and then the desulfurizer attached to the filter bags is blown off by a rotary blowing system, and then the blown off desulfurizer is discharged to the desulfurization ash bin through the desulfurization ash pipe. The purified flue gas is drawn to the chimney by the induced draft fan through the flue gas exhaust pipe for discharge.

[0008] The beneficial effects of the present invention are as follows: (1) the present invention completely eliminates the atomizing water spraying link by removing the quicklime bin, atomizing water gun and chute and other equipment, thereby solving the problem of desulfurization ash easily depositing and forming compaction in the desulfurization tower from the source, thereby avoiding the occurrence of a situation where the entire line is shut down for cleaning due to compaction of the desulfurizer; (2) due to the removal of the atomizing water gun and chute and other equipment, the monitoring of the pressure drop of the desulfurization tower, the control of the water intake and the adjustment of the desulfurizer recirculation are eliminated, which reduces the labor consumption and the labor intensity of the staff; (3) by arranging a gas guide component in the desulfurization tower, the flue gas and the desulfurizer can be more fully contacted, and the guide vanes can make the flue gas rotate and rise, thereby extending the residence time of the flue gas in the tower and promoting the uniform distribution of the flue gas, thereby improving the desulfurization effect.

[0009] Option 2, which is the preferred option of the basic option, the desulfurization tower includes a tower body, the lower end of the tower body is provided with a flue gas inlet, the flue gas inlet and the flue gas pipe are detachably connected, the upper end of the tower body is provided with a flue gas outlet and a desulfurizer inlet, the flue gas outlet is detachably connected to the ash hopper, the desulfurizer inlet and the conveying pipe are detachably connected, a defogger assembly is detachably connected in the tower body, the defogger assembly is located below the flue gas outlet, and a blowing assembly is provided in the tower body; the detachable connection between the flue gas inlet and the flue gas pipe, the flue gas outlet and the ash hopper, and the desulfurizer inlet and the conveying pipe can quickly disassemble and assemble the flue gas inlet and the flue gas outlet, which is convenient for staff to carry out maintenance, and the defogger plate can remove droplets and dust particles in the flue gas, ensuring the quality of the flue gas while reducing the impact on subsequent equipment, protecting downstream equipment, and reducing equipment maintenance costs and failure rates.

[0010] Option three is the preferred option of the basic option. The injection assembly includes a injection main pipe, which is connected to the conveying pipeline. The injection main pipe is connected to a injection ring pipe, and the injection ring pipe is connected to several injection branch pipes. Each of the injection branch pipes is threadedly connected to several nozzles. The desulfurizer injection pipe adopts an annular pipe, which can fully cover the desulfurization tower, so that the desulfurizer and flue gas can react better. The injection branch pipe and the nozzle are threadedly connected, which is convenient for quick replacement of blocked nozzles.

[0011] Option 4 is the preferred option of the basic option. The flue gas inlet and flue gas duct, the flue gas outlet and ash hopper, the desulfurizer inlet and the delivery duct are all flange-connected. The defogger assembly includes a fixed plate on which are welded several S-shaped defogger plates. A mounting block is provided in the tower body, and both ends of the fixed plate are bolted to the mounting block. The flange connection method enables quick disassembly and assembly of the flue gas inlet and outlet, making maintenance easier.

[0012] Option 5 is the preferred option of the basic option. The flue gas inlet is tilted downward by 10°-15°. The tilted flue gas inlet can extend the flow path of the flue gas in the tower, thereby increasing the contact time between the flue gas and the desulfurizer, allowing the desulfurizer to more fully react chemically with pollutants such as sulfur dioxide in the flue gas, thereby improving the desulfurization effect.

[0013] Option six is ​​the preferred option of the basic option. A gas guide assembly is provided in the tower body, and the gas guide assembly includes a guide ring. The guide ring is fixedly connected to the inner wall of the tower body. The inner side of the guide ring is conical with a larger upper part and a smaller lower part. A number of guide blades are welded to the inner side of the guide ring, and the guide blades are all inclined at 30°-40°. The gas guide assembly can guide the flue gas to flow in a rotational manner, thereby promoting the uniform distribution of the flue gas, so that the flue gas can contact the desulfurizer more evenly, thereby achieving the effect of improving the desulfurization reaction.

[0014] Option seven is the preferred option of the basic option. The nozzle is a conical spiral nozzle. The conical spiral nozzle can increase the contact area between the desulfurizer and the flue gas, so that the desulfurizer can more fully react chemically with pollutants such as sulfur dioxide in the flue gas, thereby improving the desulfurization efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a process flow diagram of a gas boiler flue gas dry desulfurization system according to the present invention; Figure 2 This is a three-dimensional diagram of a desulfurization tower in a dry flue gas desulfurization system for a gas boiler according to the present invention; Figure 3 It is a three-dimensional cross-sectional view of a desulfurization tower in a dry desulfurization system for flue gas from a gas boiler according to the present invention; Figure 4 It is a sectional front view of a desulfurization tower in a dry desulfurization system for flue gas from a gas boiler according to the present invention. DETAILED DESCRIPTION

[0016] The present invention will be further described in detail below through specific embodiments: The figure marks in the drawings of the specification include: 1. gas boiler; 2. slaked lime silo; 3. flue gas duct; 4. flue gas control valve; 5. desulfurization tower; 501. tower body; 502. flue gas inlet; 503. flue gas outlet; 504. desulfurizer inlet; 6. variable frequency feeder; 7. conveying pipeline; 8. ash hopper; 9. rotary injection system; 10. desulfurization ash pipeline; 11. desulfurization ash silo; 12. flue gas discharge pipe; 13. chimney; 14. induced draft fan; 15. demisting assembly; 1501. fixing plate; 1502. S-type demisting plate; 16. mounting block; 17. injection assembly; 1701. injection main pipe; 1702. injection ring pipe; 1703. injection branch pipe; 1704. nozzle; 18. gas guide assembly; 1801. guide ring; 1802. guide blade.

[0017] Example 1 A gas boiler flue gas dry desulfurization system, such as Figure 1 The figure includes a gas boiler 1 and a slaked lime silo 2, the gas boiler 1 is connected to a flue gas pipe 3, the flue gas pipe 3 is provided with a flue gas control valve 4, the other end of the flue gas pipe 3 is connected to a desulfurization tower 5, the slaked lime silo 2 is provided with a frequency conversion feeder 6, the frequency conversion feeder 6 is connected to a conveying pipe 7, the slaked lime silo 2 and the desulfurization tower 5 are connected through the conveying pipe 7, four ash hoppers 8 are connected in series on the desulfurization tower 5, a rotary blowing system 9 is provided above each ash hopper 8, a desulfurization ash pipe 10 is connected to the bottom of each ash hopper 8, the desulfurization ash pipe 10 is connected to a desulfurization ash silo 11, the fourth ash hopper 8 of the four ash hoppers 8 in series is connected to a flue gas exhaust pipe 12, the other end of the flue gas exhaust pipe 12 is connected to a chimney 13, and a draft fan 14 is provided on the flue gas exhaust pipe 12.

[0018] The implementation method of this embodiment is as follows: first, the water content in the slaked lime silo 2 is ≤1.5wt%, the content of calcium hydroxide is ≥88wt%, D(90) ≤30um, and the specific surface area is ≥40m 2 / g, natural bulk density ≤0.4t / m 3 The desulfurizer is fed into the desulfurization tower 5 through the transmission pipeline 7 at a blowing rate of 42t-125t per hour by the frequency conversion feeder 6, and then the flue gas control valve 4 is opened to make the flue gas in the gas boiler 1 flow at a rate of 500000Nm 3 -750000Nm 3 The flow rate enters the desulfurization tower 5 through the flue gas duct 3, so that the flue gas reacts with the desulfurizer in the desulfurization tower 5. The flue gas after the reaction enters four ash hoppers 8 in series in turn, and the flue gas and desulfurizer are separated by filter bags in the ash hopper 8, so that the desulfurizer adheres to the filter bags in the ash hopper 8. When the pressure difference of the filter bags in the ash hopper 8 exceeds 1.8KPa, the rotary blowing system 9 is turned on to spray the filter bags to blow off the desulfurizer attached to the filter bags, and then the blown-off desulfurizer is transported to the desulfurization ash bin 11 through the desulfurization ash duct 10, and the purified flue gas is drawn to the chimney 13 through the induced draft fan 14 through the flue gas exhaust pipe 12 for discharge.

[0019] Example 2 A gas boiler flue gas dry desulfurization system, such as Figures 2 to 4As shown, the desulfurization tower 5 includes a tower body 501, a flue gas inlet 502 is provided at the lower end of the tower body 501, the flue gas inlet 502 is inclined downward by 10°-15°, the flue gas inlet 502 is flange-connected to the flue gas pipe 3, a flue gas outlet 503 is provided at the upper end of the tower body 501, a desulfurizer inlet 504 is flange-connected to the flue gas hopper 8, and the desulfurizer inlet 504 is flange-connected to the conveying pipe 7, a demisting assembly 15 is detachably connected to the tower body 501, the demisting assembly 15 is located below the flue gas outlet 503, the demisting assembly 15 includes a fixing plate 1501, a plurality of S-shaped demisting plates 1502 are welded on the fixing plate 1501, a mounting block 16 is provided in the tower body 501, and both ends of the fixing plate 1501 are bolted to the mounting block 16, the tower body 501 A blowing assembly 17 is provided inside, which includes a blowing main pipe 1701, which is connected to the conveying pipe 7, and a blowing ring pipe 1702 is connected to the blowing main pipe 1701, and a plurality of blowing branch pipes 1703 are connected to the blowing ring pipe 1702, and each blowing branch pipe 1703 is threadedly connected to a plurality of nozzles 1704, and the nozzle 1704 is a conical spiral nozzle. A gas guide assembly 18 is provided in the tower body 501, and the gas guide assembly 18 includes a guide ring 1801, which is fixedly connected to the inner wall of the tower body 501, and the inner side of the guide ring 1801 is conical with a larger upper part and a smaller lower part. A plurality of guide blades 1802 are welded to the inner side of the guide ring 1801, and the guide blades 1802 are all inclined at 30°-40°.

[0020] The implementation method of this embodiment is: when the boiler flue gas is desulfurized, first, the desulfurizer enters the injection main pipe 1701 through the desulfurizer inlet 504 on the tower body 501, and then enters the injection branch pipe 1703 in sequence through the injection ring pipe 1702, and finally is sprayed out from the nozzle 1704, and then the boiler flue gas is passed into the desulfurization tower 5 from the flue gas inlet 502. After the boiler flue gas enters the tower body from the flue gas inlet 502, it passes through the guide vanes 1802 to rotate the flue gas upward, so that it is fully in contact with the desulfurizer and reacts. The flue gas after the reaction continues to move upward, passes through the S-shaped demister plate 1502 and is discharged from the flue gas outlet 503.

[0021] The above is only an embodiment of the present invention, and the common knowledge such as the specific structure and characteristics of the scheme is not described in detail here. It should be pointed out that for those skilled in the art, without departing from the structure of the present invention, several variations and improvements can be made, which should also be regarded as the scope of protection of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A gas boiler flue gas dry desulfurization system, characterized in that: The invention comprises a gas boiler (1) and a slaked lime bin (2), wherein the gas boiler (1) is connected to a flue gas pipe (3), the flue gas pipe (3) is provided with a flue gas control valve (4), the other end of the flue gas pipe (3) is connected to a desulfurization tower (5), the slaked lime bin (2) is provided with a variable frequency feeder (6), the variable frequency feeder (6) is connected to a conveying pipe (7), the slaked lime bin (2) and the desulfurization tower (5) are connected via the conveying pipe (7), and the desulfurization tower (5) is connected in series with a variable frequency feeder (6). There are four ash hoppers (8), each of which is provided with a rotary spraying system (9) above, each of which is connected to a desulfurization ash pipe (10) below, and the desulfurization ash pipe (10) is connected to a desulfurization ash bin (11), the fourth ash hopper (8) of the four ash hoppers (8) connected in series is connected to a flue gas exhaust pipe (12), the other end of the flue gas exhaust pipe (12) is connected to a chimney (13), and an induced draft fan (14) is provided on the flue gas exhaust pipe (12).

2. A gas boiler flue gas dry desulfurization system according to claim 1, characterized in that: The desulfurization tower (5) comprises a tower body (501), a flue gas inlet (502) is provided at the lower end of the tower body (501), the flue gas inlet (502) and the flue gas pipeline (3) are detachably connected, a flue gas outlet (503) and a desulfurizer inlet (504) are provided at the upper end of the tower body (501), the flue gas outlet (503) and the ash hopper (8) are detachably connected, the desulfurizer inlet (504) and the conveying pipeline (7) are detachably connected, a demisting assembly (15) is detachably connected in the tower body (501), the demisting assembly (15) is located below the flue gas outlet (503), and a spraying assembly (17) is provided in the tower body (501).

3. A gas boiler flue gas dry desulfurization system according to claim 2, characterized in that: The spray assembly (17) includes a spray main pipe (1701), the spray main pipe (1701) is connected to the conveying pipeline (7), the spray main pipe (1701) is connected to a spray ring pipe (1702), the spray ring pipe (1702) is connected to a plurality of spray branch pipes (1703), and each of the spray branch pipes (1703) is threadedly connected to a plurality of nozzles (1704).

4. A gas boiler flue gas dry desulfurization system according to claim 2, characterized in that: The flue gas inlet (502) and the flue gas duct (3), the flue gas outlet (503) and the ash hopper (8), and the desulfurizer inlet (504) and the conveying duct (7) are all flange-connected. The demisting assembly (15) includes a fixed plate (1501), and a plurality of S-shaped demisting plates (1502) are welded to the fixed plate (1501). A mounting block (16) is provided in the tower body (501), and both ends of the fixed plate (1501) are bolt-connected to the mounting block (16).

5. A gas boiler flue gas dry desulfurization system according to claim 2, characterized in that: The flue gas inlet (502) is inclined downward by 10°-15°.

6. A gas boiler flue gas dry desulfurization system according to claim 2, characterized in that: A gas guide assembly (18) is provided in the tower body (501), and the gas guide assembly (18) comprises a guide ring (1801). The guide ring (1801) is fixedly connected to the inner wall of the tower body (501), and the inner side of the guide ring (1801) is in a conical shape with a larger upper portion and a smaller lower portion. A plurality of guide blades (1802) are welded to the inner side of the guide ring (1801), and the guide blades (1802) are all arranged at an inclination of 30°-40°.

7. A gas boiler flue gas dry desulfurization system according to claim 3, characterized in that: The nozzle (1704) is a conical spiral nozzle.

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