An integrated moving bed desulfurization device for horizontal boiler system

Abstract

The application discloses a built-in mobile bed desulfurization device for horizontal boiler system. The device is arranged in the high-temperature flue gas in the medium-temperature section of the boiler shell and comprises a multilayer mobile bed steel frame, more than one mobile bed insert is arranged in each layer of the mobile bed frame along the direction of the high-temperature flue gas flow, each mobile bed insert comprises a porous plate made air-permeable shell, a pneumatic conveying feeding port is arranged on the upper section of one side of the shell and is used for conveying granular desulfurizer filler into the air-permeable shell, a by-product discharging screw conveyor is arranged at the bottom of the shell, and a discharging pipe is arranged at the bottom of one side of the shell and corresponds to the by-product discharging screw conveyor. The device can be directly arranged in the horizontal boiler shell, only one set of desulfurizer storage and transportation circulating discharge system needs to be arranged outside the boiler, a desulfurization tower and a bag-type dust collector do not need to be arranged, project land occupation is greatly saved, and construction cost is low.

Description

Technical Field

[0001] This invention relates to the field of boiler flue gas desulfurization technology and equipment, and particularly to a built-in moving bed desulfurization device for horizontal boiler systems, mainly targeting low concentration levels (<200mg / m³). 3 This horizontal boiler flue gas desulfurization device can be directly installed inside the medium- or low-temperature section of the horizontal boiler (usable at <400℃). No additional desulfurization facilities are needed at the boiler outlet flue to achieve compliant emissions. Compared to traditional low-concentration levels (<200mg / m³), this device achieves significantly higher emissions. 3 Compared with traditional boiler flue gas desulfurization technology, it has significant advantages such as small footprint, simple system, and low construction and operating costs. Background Technology

[0002] SO2 is a gaseous pollutant with a relatively large content and wide impact among air pollutants. It mainly comes from the combustion of fossil fuels (coal, oil and natural gas) and the roasting and smelting processes of sulfide ores.

[0003] SO2 control technologies are mainly divided into pre-combustion desulfurization technologies (mainly referring to raw coal purification and coal gas fine desulfurization), clean combustion desulfurization technologies (coal briquette desulfurization, circulating fluidized bed combustion desulfurization, coal-water slurry, etc.), and post-combustion desulfurization technologies (end-of-pipe treatment).

[0004] In recent years, the national standards for ultra-low emissions in the power, metallurgical, and cement building materials industries have been successively issued, and boiler flue gas desulfurization has become increasingly stringent. Most industrial enterprises' desulfurization and purification projects require flue gas sulfur dioxide concentrations to be below 35 mg / Nm³. 3 The ultra-low emission requirements.

[0005] With increasing environmental pressure in my country and increasingly stringent national emission requirements, flue gas desulfurization (FGD) technology has developed rapidly. Currently, there are dozens of FGD technologies. Based on whether water is added during the desulfurization process and the dry / wet state of the desulfurization products, FGD processes are divided into three main categories: wet, semi-dry, and dry. A brief introduction to the most widely used mainstream FGD processes is as follows:

[0006] The wet scrubbing process uses an absorption tower. After entering the tower, the flue gas undergoes a thorough reaction with an alkaline solution to achieve desulfurization. Wet scrubbing is effective at removing acidic gases and requires less absorbent. However, it has drawbacks including a complex process, numerous supporting equipment, tailing of exhaust gases, the need for a secondary purification system to achieve ultra-clean emissions, and the need for wastewater treatment.

[0007] Semi-dry desulfurization involves injecting an absorbent into a reaction tower. While SO2 gas reacts with the absorbent, the waste heat of the flue gas evaporates the moisture in the absorbent. This process ensures sufficient mass and heat transfer between the absorbent and pollutants, improving efficiency and drying the reaction products, which are then discharged as dry solids. The semi-dry process is relatively mature and requires simple equipment. Its advantages include: high purification efficiency; easy treatment of byproducts; controllable temperature and humidity; good adaptability to load fluctuations; adjustable absorbent dosage based on pollutant concentration in the flue gas; and low water consumption.

[0008] Dry desulfurization processes typically involve injecting lime powder / sodium carbonate / sodium bicarbonate into the system's flue gas duct or desulfurization reactor via a spray system. There, they react with acidic gases to form solid compounds, which are then collected along with fly ash by dry dust collectors or similar equipment. The biggest advantages of this combined process are its simplicity, ease of maintenance, low cost, small footprint, lack of wastewater, and absence of tailing phenomena in the desulfurized flue gas.

[0009] In the past two years, a new type of dry desulfurization technology has emerged: the fixed-bed dry desulfurization process. This process uses a fixed-bed-like technology, where desulfurizing agents (lime, sodium bicarbonate, magnesium oxide, etc.) and catalyst granules are packed into a desulfurization reactor. After the flue gas passes through, the SO2 in it is oxidized to SO3 and then solidified into calcium sulfate. This process produces no wastewater, is simple to operate, has a wide applicable flue gas temperature range (not exceeding 400℃), requires little space, and has low investment.

[0010] Compared to the complex wet and semi-dry desulfurization processes, dry desulfurization processes have the advantages of low investment and operating costs, no wastewater, and no white smoke, making them particularly suitable for the treatment of low-sulfur flue gas. However, their disadvantages are that for desulfurization projects involving large flow rates and low concentrations of boiler flue gas, the amount of desulfurizing agent required is relatively large, and in some projects, uneven airflow can easily lead to uneven reaction of the desulfurizing agent in the packing layer, resulting in low utilization of the effective components of the desulfurizing agent. Summary of the Invention

[0011] To overcome the above-mentioned defects, the present invention aims to provide a built-in moving bed desulfurization device for horizontal boiler systems, which is particularly suitable for desulfurization of large-flow, low-concentration boiler flue gas. In addition to having many advantages of fixed-bed dry desulfurization, it can also realize the online recycling of desulfurizing agent and the replacement of desulfurizing agent as needed.

[0012] To achieve the above objectives, the present invention provides a built-in moving bed desulfurization device for a horizontal boiler system, wherein an insert-type moving bed is installed inside the boiler shell in the medium-temperature section facing the high-temperature flue gas, and the insert-type moving bed comprises:

[0013] The mobile bed steel frame is a multi-layered structure integrally formed.

[0014] One or more movable bed inserts are provided in each layer of the movable bed frame along the direction of high-temperature flue gas flow;

[0015] Each mobile bed insert includes:

[0016] The permeable shell is made of a perforated plate. A pneumatic conveying inlet is provided on the upper part of one side of the shell for conveying granular desulfurizing agent filler into the permeable shell. A by-product discharge screw conveyor is provided at the bottom of the shell, and a discharge pipe is provided on the bottom of one side of the shell corresponding to the by-product discharge screw conveyor.

[0017] Furthermore, a desulfurizing agent storage, transportation, circulation, and discharge system is set up outside the boiler shell, including at least: a desulfurizing agent silo, and a pneumatic conveying device is set at the bottom outlet of the desulfurizing agent silo. The pneumatic conveying device is connected to the pneumatic conveying inlet through a pneumatic conveying pipeline.

[0018] It also includes an elevator, with a feed inlet at the bottom of the elevator, which is connected to the discharge pipe of the by-product discharge screw conveyor via a discharge pipe; and a discharge outlet at the top of the elevator, which corresponds to the feed inlet of the desulfurizing agent silo.

[0019] Furthermore, the pneumatic conveying device consists of a Venturi transmitter and a Roots blower for feeding.

[0020] Furthermore, an inspection manhole is provided on one side of each layer of the moving bed frame.

[0021] Furthermore, a star-shaped unloader and a desulfurizing agent weighing device are installed at the bottom of the desulfurizing agent silo.

[0022] Furthermore, the desulfurizing agent filler is a granular calcium-based desulfurizing agent.

[0023] Furthermore, the flue gas flow direction is perpendicular to the desulfurizing agent flow direction.

[0024] This invention employs an in-furnace adsorption and purification technology using a moving bed filled with granular calcium-based desulfurizing agent. Compared to commonly used boiler flue gas desulfurization technologies such as circulating fluidized bed (CFB) desulfurization, sodium bicarbonate (SDS) desulfurization, and calcium-based ultrafine powder dry desulfurization, it has several significant advantages and is more suitable for application in various low-concentration (<200 mg / m³) flue gas desulfurization applications. 3 (On the horizontal boiler flue gas desulfurization project)

[0025] 1. The device of the present invention can be directly installed inside the shell of a horizontal boiler. Only one desulfurizing agent storage, transportation and circulation system needs to be installed outside the boiler. Compared with traditional desulfurization technology, there is no need to install a desulfurization tower and a bag filter, which saves a lot of land and reduces construction costs.

[0026] 2. The device of the present invention can be directly installed inside the shell of a horizontal boiler, which can easily realize the simultaneous design, manufacture and installation of the desulfurization device and the boiler equipment, saving the overall construction period;

[0027] 3. The purification principle of this invention is to use dry adsorption purification with granular calcium-based desulfurizing agent without introducing any other substances, thus avoiding the impact on the flue gas system caused by introducing new materials into the flue gas due to other desulfurization processes such as wet spraying, semi-dry spraying liquid, and dry powder spraying.

[0028] 4. The device of the present invention adopts a plate-type moving bed structure. The structure design of this type of moving bed is flexible. Different plate modules and the number of layers of plate packing can be designed according to the boiler shell size and the sulfur concentration in the flue gas. It has obvious advantages in terms of site layout and online switching control.

[0029] 5. The device of the present invention is applicable to a wide range of flue gas volumes. The external dimensions of the insert-type moving bed can be designed according to the scale of flue gas volume to be processed in the project, and theoretically it is not limited by the scale of flue gas volume.

[0030] 6. The purification system of this invention has a relatively simple structure. Apart from the discharge screw conveyor, no other transmission equipment is required inside the moving bed. No one needs to be on duty when the equipment is running normally, and the workload of personnel inspection and maintenance is minimal.

[0031] 7. The device of this invention has low system resistance, fewer transmission devices, and low energy consumption;

[0032] 8. The device of this invention produces no wastewater and does not generate secondary pollution. The waste granular desulfurizer after adsorption saturation can be directly bagged at the bottom of the desulfurizer silo or transported by truck.

[0033] 9. After being purified by the device of this invention, the flue gas is still dry flue gas. The system does not require corrosion protection and there is no "white smoke" phenomenon. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the elevation layout of the present invention;

[0035] Figure 2 This is a schematic diagram of the elevation structure of the present invention;

[0036] Figure 3 This is a top view of the structure of the present invention;

[0037] Figure 4 This is a schematic diagram of the porous plate structure of the present invention.

[0038] Drawing number explanation:

[0039] 1. Boiler body; 2. Granular calcium-based desulfurizer; 3. Inlet and outlet moving bed inserts made of perforated plates; 4. Pneumatic conveying inlet; 5. By-product discharge screw conveyor; 6. Moving bed frame foundation; 7. Moving bed steel frame; 8. Sealing plate; 9. Inspection manhole; 10. Feed pneumatic conveying pipeline; 11. Discharge pipeline; 12. Desulfurizer weighing device; 13. Venturi transmitter; 14. Feeding Roots blower; 15. Bucket elevator; 16. Desulfurizer silo; 17. Rotary rotary valve; 18. External discharge outlet pipe. Detailed Implementation

[0040] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0041] In the description of this invention, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0042] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0043] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0044] The built-in moving bed desulfurization device for horizontal boiler systems of the present invention has multiple sets of insert-type moving bed structures in the medium temperature section (between the high pressure evaporator and the economizer) inside the boiler shell (1), including the following specific contents: granular calcium-based desulfurizing agent (2), inlet and outlet moving bed inserts made of perforated plates (3), pneumatic conveying inlet (4), by-product discharge screw conveyor (5), moving bed frame foundation (6), moving bed steel frame (7), sealing plate (8), and inspection manhole (9);

[0045] A desulfurizing agent storage, transportation, circulation, and discharge system is set up outside the boiler shell, including the following components: feed pneumatic conveying pipeline (10), discharge pipeline (11), desulfurizing agent weighing device (12), Venturi transmitter (13), feed Roots blower (14), bucket elevator (15), desulfurizing agent silo (16), rotary valve (17), and discharge outlet pipe (18).

[0046] After passing through the high-pressure evaporator and denitrification catalyst inside the boiler shell (1), the flue gas enters the moving bed insert (3) made of perforated plate and interacts with the desulfurizing agent packing layer (2-4 layers of moving bed desulfurizing agent packing layer are set according to the different concentrations of sulfur dioxide in the flue gas). Under the action of granular calcium-based desulfurizing agent (2), the sulfur dioxide in the flue gas is converted into calcium sulfite and other substances and adsorbed on the granular calcium-based desulfurizing agent (2). After desulfurization and purification, the flue gas enters the back end process of the boiler (1) through the moving bed insert (3) made of perforated plate and is finally discharged into the atmosphere through the chimney.

[0047] The following is combined with Figures 1 to 4 The built-in moving bed desulfurization device for horizontal boiler systems of the present invention will be further described below:

[0048] After passing through high-temperature evaporators and denitrification facilities, the flue gas temperature drops to approximately 330℃-400℃. Within this temperature range, a built-in moving bed desulfurization device is installed inside the boiler body shell.

[0049] A moving bed steel frame foundation (6) is set at the bottom of the boiler shell, and the lower part is connected to the concrete foundation by the boiler support. On the moving bed steel frame foundation (6), a moving bed steel structure frame is set up to build and support the multi-layer insert-type moving bed.

[0050] like Figure 2 and Figure 3 As shown, each layer of the insert-type moving bed is equipped with multiple moving bed inserts.

[0051] Each moving bed insert uses an inlet and outlet perforated plate as the support structure for the moving bed packing, which also has the functions of rectification and flow equalization. For projects with special air intake conditions, airflow distribution devices such as guide plates can be set at the front end of the inlet perforated plate to further improve the airflow uniformity. A pneumatic conveying inlet 4 is set on the upper section of one side of each moving bed insert for conveying granular desulfurizing agent packing into the permeable shell; a by-product discharge screw conveyor is set at the bottom of the shell, and a discharge pipe is set on the bottom of one side of the shell corresponding to the by-product discharge screw conveyor. Using a screw conveyor as the equipment for transferring granular calcium-based desulfurizing agent (2) to the outside of the boiler ensures the overall airtightness of the equipment, and at the same time, it is not easy to crush and pulverize the desulfurizing agent.

[0052] The desulfurizing agent filler uses granular calcium-based desulfurizing agent (2). This type of desulfurizing agent has the advantages of a wide temperature window (use range 50℃-450℃), low resistance, and no secondary pollution. The desulfurization efficiency of this type of desulfurizing agent will not be affected in the medium temperature section of the boiler (flue gas temperature <400℃).

[0053] As shown in the figure, after the granular calcium-based desulfurizer (2) passes through the star-shaped unloader (17) and desulfurizer weighing device (12) at the bottom of the silo, it is fed into the interior of the insert-type moving bed through the pneumatic conveying inlet (4) via the feeding Roots blower (14) and Venturi emitter (13) via the feeding pneumatic conveying pipe (10). The packing is supported on both sides by the inlet and outlet perforated plates and simultaneously achieves the function of air permeability. After running for a period of time, the granular calcium-based desulfurizer (2) is discharged into the bucket elevator (15) through the discharge pipe (11) via the by-product discharge conveyor (5) and finally returns to the desulfurizer silo (16). After the granular calcium-based desulfurizer is recycled for a period of time, it is discharged from the system through the external discharge outlet pipe (18).

[0054] A sealing plate (8) is installed on the top of the multi-layered insert-type moving bed to prevent short circuit of unpurified flue gas.

[0055] Depending on the sulfur dioxide concentration in the boiler flue gas, two or four layers of granular calcium-based desulfurizing agent (2) packing layers are set. If the sulfur dioxide concentration is below 100 mg / m3, two layers of packing are generally set; if the sulfur dioxide concentration is above 100 mg / m3, four layers of packing are generally set.

[0056] Each moving bed insert is fed from the top and discharged from the bottom, realizing online material flow, circulation, and renewal. Top feeding adopts pneumatic conveying, while bottom discharge adopts screw conveying. The power medium for pneumatic conveying comes from the compressed air generated by the feeding Roots blower (14). The screw conveyor (5) directly transfers the desulfurizer to the bucket elevator (15), and then the bucket elevator (15) transports the desulfurizer back to the desulfurizer silo (16).

[0057] The desulfurizing agent silo (16) is unloaded at the bottom by a star-shaped unloader (17), and at the same time connected to a desulfurizing agent weighing device (12) for measuring the amount of desulfurizing agent used. The measured desulfurizing agent is sent to the moving bed inside the boiler through the lower venturi transmitter (13) and the feeding pipe (10).

[0058] During the operation of the desulfurization unit, the sulfur dioxide concentration level can be monitored in real time by the inlet and outlet CEMS online detection devices. When the concentration level is low for a long time, the movement of the moving bed can be reduced, and the circulation volume and the amount of new material replacement can be reduced. When the sulfur dioxide concentration level is high, the circulation volume and the amount of new material added can be increased to achieve the goal of ultra-low emissions.

[0059] The desulfurization principle of the desulfurizing agent in this invention is as follows:

[0060] The main reaction formula for desulfurization using granular calcium-based desulfurizers is: SO2 + 1 / 2 O2 + Ca(OH)2 → CaSO4 + H2O. Technically, this method utilizes a purification device with a fixed bed or intermittent moving bed structure, filled with granular desulfurizer. After the flue gas passes through, the sulfur dioxide is reacted and solidified into calcium sulfate (gypsum) solid.

[0061] Selection of granular calcium-based desulfurizer:

[0062] The device of this invention can use commercially available granular calcium-based desulfurizers. These desulfurizers are processed with calcium hydroxide as the main active component and other accelerators added. They exhibit good removal efficiency for sulfur dioxide within a temperature window range of 50℃ to 400℃.

[0063] The entire process uses no water and produces no wastewater. The operation and control process consists of only one step, making the technology simple.

[0064] The desulfurization effect can be achieved by adjusting the contact time as required, reaching 100% removal. It is not sensitive to short-term fluctuations in flue gas conditions or flue gas temperature, and is suitable for almost all flue gas conditions.

[0065] The present invention has been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described above. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention. Many other changes and modifications made without departing from the concept and scope of the present invention should be considered within the scope of protection of the present invention.

[0066] In the description of this specification, specific features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.

[0067] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A built-in moving bed desulfurization device for a horizontal boiler system, characterized in that, An insert-type moving bed is installed inside the boiler shell in the intermediate temperature section facing the high-temperature flue gas. The insert-type moving bed includes: The mobile bed steel frame is a multi-layer structure integrally formed. One or more movable bed inserts are installed in the steel frame of each movable bed along the direction of high-temperature flue gas flow; Each mobile bed insert includes: The permeable shell is made of a perforated plate. A pneumatic conveying inlet is provided on the upper part of one side of the shell for conveying granular desulfurizing agent filler into the permeable shell. A by-product discharge screw conveyor is provided at the bottom of the shell, and a discharge pipe is provided on the bottom of one side of the shell corresponding to the by-product discharge screw conveyor.

2. The built-in moving bed desulfurization device for a horizontal boiler system as described in claim 1, characterized in that, A desulfurizing agent storage, transportation, circulation and discharge system is set up outside the boiler shell, including at least: a desulfurizing agent silo, and a pneumatic conveying device is set at the bottom outlet of the desulfurizing agent silo. The pneumatic conveying device is connected to the pneumatic conveying inlet through a pneumatic conveying pipeline. It also includes an elevator, with a feed inlet at the bottom of the elevator, which is connected to the discharge pipe of the by-product discharge screw conveyor via a discharge pipe; and a discharge outlet at the top of the elevator, which corresponds to the feed inlet of the desulfurizing agent silo.

3. The built-in moving bed desulfurization device for a horizontal boiler system as described in claim 1, characterized in that, The pneumatic conveying device consists of a Venturi transmitter and a Roots blower for feeding.

4. The built-in moving bed desulfurization device for a horizontal boiler system as described in claim 2, characterized in that, Each layer of the movable bed frame is equipped with an inspection manhole on one side.

5. The built-in moving bed desulfurization device for a horizontal boiler system as described in claim 1, characterized in that, The bottom of the desulfurizing agent silo is equipped with a star-shaped unloader and a desulfurizing agent weighing device.

6. The built-in moving bed desulfurization device for a horizontal boiler system as described in claim 1, characterized in that, The desulfurizing agent filler is a granular calcium-based desulfurizing agent.

7. The built-in moving bed desulfurization device for a horizontal boiler system as described in claim 1, characterized in that, The direction of the high-temperature flue gas flow is perpendicular to the direction of the desulfurizing agent flow.

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