A dry low-temperature oxidation device and method for desulfurized ash

Abstract

The application discloses a desulfurization ash dry low-temperature oxidation device and method. The device comprises a device body, the inside of the device body is sequentially divided into a crushing and heating section, an oxidation section and a discharge section from top to bottom, a partition plate is arranged between adjacent sections, and a material port is arranged on the partition plate; the crushing and heating section, the oxidation section and the discharge section are all provided with independent motor-driven stirring shafts; the crushing and heating section is provided with a heat tracing device, and the crushing and heating section is provided with a feeding port and an exhaust port; an oxidant injection device is arranged above the stirring shaft of the oxidation section; and the discharge section is provided with a discharge port. The application can realize low-temperature oxidation of desulfurization ash in a dry powder state, and has the advantages of simple operation, high equipment integration, small land occupation, low operation energy consumption and no secondary pollution.

Description

Technical Field

[0001] This invention relates to the field of environmental engineering technology, and in particular to a dry low-temperature oxidation device and method for desulfurization ash. Background Technology

[0002] Desulfurization ash is a byproduct collected by the dust removal system after desulfurization in semi-dry flue gas desulfurization processes. Its main components include calcium sulfate (CaSO4), calcium sulfite (CaSO3), and dust. Due to the unstable chemical properties of calcium sulfite (CaSO3), its high content severely limits the comprehensive utilization of desulfurization ash, leading to secondary pollution.

[0003] There are generally different methods for treating calcium sulfite (CaSO3) in desulfurization ash, including high-temperature decomposition, high-temperature oxidation, and low-temperature oxidation. For example:

[0004] Chinese patent application CN105396455A discloses a method and system for reusing desulfurization ash from a circulating fluidized bed. This method uses high-temperature decomposition to convert calcium sulfate (CaSO4) and calcium sulfite (CaSO3) in the desulfurization ash into calcium oxide (CaO). However, this method requires a large amount of energy because the decomposition temperature of calcium sulfite (CaSO3) is 650℃ and the decomposition temperature of calcium sulfate (CaSO4) is even higher at 1300℃, making it uneconomical in practical applications.

[0005] Chinese patent application CN114409290A discloses an apparatus and method for modifying desulfurized ash by heating with blast furnace gas. The method uses blast furnace gas as a heat source fuel to oxidize the desulfurized ash at 300-450°C. Although the oxidation temperature is lower than the decomposition temperature, the method still requires the consumption of high-calorific-value fuel, resulting in a complex system, large footprint, and poor economic efficiency.

[0006] Chinese patent application CN109455752A discloses a method and apparatus for preparing calcium sulfate from desulfurization ash. The method involves reacting desulfurization ash with a strong oxidant in a solution state to achieve low-temperature oxidation. However, this method requires pH adjustment and pressure filtration and drying after oxidation, making the operation complex and generating wastewater, thus causing secondary pollution.

[0007] Therefore, it is of great significance to develop a new desulfurization ash disposal device that can reduce disposal costs and avoid secondary pollution. Summary of the Invention

[0008] According to one embodiment of the present invention, the objective is to provide a dry low-temperature oxidation device and method for desulfurization ash, achieving low-temperature oxidation of desulfurization ash in a dry powder state, reducing disposal costs, avoiding wastewater generation, and minimizing secondary pollution. The above objective can be achieved through the following technical solutions:

[0009] According to one aspect of the present invention, a dry low-temperature oxidation device for desulfurized ash is provided, comprising a device body, wherein the device body is internally divided into a crushing and heating section, an oxidation section, and a discharge section from top to bottom, with partitions provided between adjacent sections and material inlets on the partitions; each of the crushing and heating section, the oxidation section, and the discharge section is provided with an independent motor-driven stirring shaft; the crushing and heating section is provided with a heating device and has a feed inlet and an exhaust outlet; an oxidant injection device is provided above the stirring shaft of the oxidation section; and the discharge section is provided with a discharge outlet.

[0010] Optionally, the partition has a U-shaped structure.

[0011] Optionally, both ends of the partition are connected to inclined plates, which are fixedly installed on the inner wall of the device body.

[0012] Optionally, the partition between the crushing heating section and the oxidation section has a double-layer structure, and the heat tracing device is installed inside it.

[0013] Optionally, the motor is a variable frequency drive (VFD) motor.

[0014] Optionally, the stirring shaft is provided with several sets of stirring blades.

[0015] Optionally, the material inlet is located at the end of the partition and on the side of the direction of desulfurization ash flow.

[0016] Optionally, the oxidant injection device is externally connected to an oxidant supply system. Optionally, the oxidant solution in the oxidant supply system is one or more of hydrogen peroxide, potassium permanganate, and hypochlorite.

[0017] Optionally, the heat tracing device is used to control the heating temperature within the crushing heating section to be between 100℃ and 150℃. Optionally, the heat tracing device is a steam heat tracing device or an electric heating type heat tracing device.

[0018] Optionally, the oxidant injection device includes several sets of distribution branches arranged along the stirring shaft, and each set of distribution branches is provided with several sets of nozzles.

[0019] According to another aspect of the present invention, a dry low-temperature oxidation method for desulfurized ash is provided, comprising: feeding desulfurized ash into a crushing and heating section through a feed inlet; crushing and heating the ash under the action of a stirring shaft and a heating device in the crushing and heating section to form dry powdery desulfurized ash; and feeding the ash into an oxidation section through a material inlet on a partition plate under the action of a stirring shaft in the oxidation section; reacting the ash with an oxidant injected by an oxidant injection device under the action of a stirring shaft in the oxidation section; and discharging the ash into a discharge section through a material inlet on a partition plate under the action of a stirring shaft in the discharge section; and discharging the ash through a discharge port under the action of a stirring shaft in the discharge section. The gas generated by heating in the crushing and heating section, as well as the gas and water vapor generated after the oxidation reaction in the oxidation section, are discharged through the exhaust port of the crushing and heating section.

[0020] Optionally, the heating temperature can be controlled to be 100℃~150℃ by a heat tracing device.

[0021] Optionally, the heat tracing device uses steam heating or electric heating.

[0022] Optionally, it also includes: controlling the rotational speed of the stirring shaft in each section by controlling the motor in each section, thereby controlling the material's forward speed and residence time in each section.

[0023] Optionally, the desulfurization ash flows in a zigzag pattern within the unit body. More preferably, the desulfurization ash flows in an S-shape within the unit body.

[0024] Optionally, it also includes: adjusting the amount of oxidant injected via an oxidant injection device.

[0025] Optionally, the gas is discharged through the exhaust port and then enters a cooling and dust removal device for cooling and dust removal treatment.

[0026] Optionally, it also includes: providing an oxidant solution via an oxidant supply system.

[0027] According to one embodiment of the present invention, low-temperature oxidation of desulfurization ash in dry powder state can be achieved, giving full play to the secondary utilization value of desulfurization ash, reducing disposal costs, with high equipment integration, small footprint, and no wastewater generation or secondary pollution. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the structure of a dry low-temperature oxidation device for desulfurized ash in one embodiment of the present invention;

[0029] Figure 2 This is a side cross-sectional schematic diagram of a desulfurization ash dry low-temperature oxidation device in one embodiment of the present invention.

[0030] Figure label:

[0031] 1-Purpose unit, 2-Crushing and heating section, 3-Oxidation section, 4-Discharge section, 5-Baffle plate, 6-Material inlet, 7-Motor, 8-Agitator shaft, 9-Feed inlet, 10-Exhaust outlet, 11-Heating device, 12-Oxidant injection device, 13-Discharge outlet. Detailed Implementation

[0032] The technical solution of the present invention will be clearly and completely described below with reference to embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0033] Figure 1 This illustration schematically depicts a dry low-temperature oxidation device for desulfurized ash provided in one embodiment of this application. For example... Figure 1 As shown, the device includes a main body 1, which is divided into a crushing and heating section 2, an oxidation section 3, and a discharge section 4 from top to bottom. A partition 5 is provided between adjacent sections, and a material inlet 6 is provided on the partition 5. Each of the crushing and heating section 2, the oxidation section 3, and the discharge section 4 is equipped with an independent stirring shaft 8 driven by a motor 7. The crushing and heating section 2 is equipped with a heating device 11, and this section is equipped with a feed inlet 9 and an exhaust outlet 10. The oxidation section 3 is equipped with an oxidant injection device 12. The discharge section 4 is equipped with a discharge outlet 13.

[0034] In a preferred embodiment, such as Figure 2 As shown, the partition 5 inside the device body 1 is configured as a U-shaped structure, which can concentrate materials and facilitate corresponding processing in each section, thus improving the stirring and pushing effect of the stirring shaft 8 and increasing processing efficiency. Furthermore, inclined plates are connected to both ends of the U-shaped structure, with the other end of the inclined plate fixedly installed on the inner wall of the device body 1. The inclined plate installation ensures that the sidewalls of the U-shaped structure are far from the inner wall of the device body 1, preventing friction and collision during material stirring and reducing service life; it also prevents dead corners in each section, avoiding material accumulation and thus improving processing efficiency. Preferably, the inclined plate and the U-shaped structure are integrally formed to improve stability and isolation effect. In an optional embodiment, such as... Figure 2 As shown, the bottom of the discharge section 4 can also be set as a U-shaped partition 5, and the discharge port 13 is set on the partition 5, which is more conducive to the centralized pushing of materials and improves the processing efficiency.

[0035] In this application, the stirring shaft 8 in each section is controlled by an independent motor 7, such as Figure 1As shown, the motor 7 can be fixedly installed on the outer wall of the device body 1, and the stirring shaft 8 is horizontally arranged in each section. Furthermore, the motor 7 is a frequency converter controlled motor. The frequency converter of each stirring shaft 8 controls the forward speed and residence time of the desulfurized ash in the corresponding section of the device body 1. For example, by reducing the rotational speed of the stirring shaft 8 through frequency conversion, the forward speed of the material is reduced, thereby extending the residence time of the material in that section. In addition, the amount of oxidant injected can be adjusted to achieve the desired oxidation effect. During operation, the control methods are flexible, enabling continuous large-scale production. Furthermore, several sets of stirring blades are provided on the stirring shaft 8 to effectively perform crushing, stirring, and pushing actions, improving the desulfurized ash treatment efficiency.

[0036] Furthermore, both the material inlet 6 and the discharge outlet 13 are positioned at the end of the partition 5, and on the side facing the direction of desulfurization ash flow, to fully utilize the role of the stirring shaft 8 and improve the desulfurization ash treatment efficiency. For example, Figure 1 As shown, a material inlet 6 is provided on the left side of the partition plate 5 between the crushing and heating section 2 and the oxidation section 3, and another material inlet 6 is provided on the right side of the partition plate 5 between the oxidation section 3 and the discharge section 4. A discharge outlet 13 is provided on the left side of the bottom partition plate 5 of the discharge section 4. In this way, the desulfurization ash flows in an S-shape within the device body 1 under the action of each stirring shaft 8, and is finally discharged through the discharge outlet 13. Through the above method, the material can be fully processed in each section, such as full stirring, crushing and heating in the crushing and heating section 2, and full mixing and oxidation reaction in the oxidation section 3.

[0037] In a preferred embodiment, the partition 5 between the crushing heating section 2 and the oxidation section 3 is configured as a double-layer structure, and a heat tracing device 11 is installed inside the double-layer structure. The heat tracing device 11 can be a steam-heated or electrically heated type. By placing the heat tracing device 11 inside the U-shaped partition 5, the heating uniformity within this section is improved, which can more effectively remove free water from the desulfurization ash, prevent excessive moisture after subsequent oxidant injection, ensure oxidation in a dry powder state, and provide a suitable temperature for the oxidation section by placing the heat tracing device inside the partition separating the crushing heating section and the oxidation section, which is more conducive to the subsequent oxidation reaction. Furthermore, the heating temperature in the crushing heating section 2 is controlled at 100℃~150℃ by the heat tracing device 11, achieving low energy consumption and low cost operation while effectively removing free water from the desulfurization ash; and the heating is conducive to the subsequent oxidation reaction, realizing dry low-temperature oxidation. It has the advantages of low oxidation temperature, high reaction efficiency, low energy consumption, and low operating cost.

[0038] Furthermore, the oxidant injection device 12 is positioned above the stirring shaft 8 within the oxidation section 3 to inject oxidant and control the injection volume. The injection volume can be controlled by adjusting valves, such as those on the distribution branch pipe and / or at the nozzle. Additionally, the oxidant injection device 12 is connected to an external oxidant supply system, whose oxidant solution is one or more of hydrogen peroxide, potassium permanganate, and hypochlorite. The oxidant and desulfurization ash are thoroughly mixed within the oxidation section 3, undergoing low-temperature oxidation. In this invention, "low-temperature oxidation" within the oxidation section 3 refers to temperatures below 200°C, in contrast to the previously mentioned high-temperature decomposition and oxidation. The discharge section 4 is essentially a continuation of the oxidation section 3. No oxidant is injected into the discharge section 4; the desulfurization ash remains in the subsequent stage of the oxidation reaction within this discharge section 4 before being discharged.

[0039] Preferably, the oxidant injection device 12 includes several sets of distribution branches arranged along the stirring shaft 8, and several sets of nozzles arranged on each set of distribution branches; for example, three sets of distribution branches are arranged at intervals along the stirring shaft 8, and seven sets of nozzles are arranged on each set of distribution branches, so that the oxidant and dry powder desulfurization ash can undergo a full oxidation reaction in the oxidation section 3.

[0040] In addition, a cooling and dust removal device can be connected to the exhaust port 10 of the crushing and heating section 2 to cool and remove dust from the gas generated in the crushing and heating section 2.

[0041] When the desulfurization ash is subjected to dry low-temperature oxidation treatment using the desulfurization ash dry low-temperature oxidation device of this application, the desulfurization ash enters the device body 1 from the feed port 9, passes through the crushing and heating section 2, oxidation section 3 and discharge section 4 in sequence, and is discharged through the discharge port 13 after completing the oxidation reaction.

[0042] Specifically, the process includes: desulfurization ash is first fed into the crushing and heating section 2 through the feed inlet 9. Under the action of the stirring shaft 8 and the heating device 11 in the crushing and heating section 2, the ash is stirred, crushed, and heated to 100℃~150℃ to obtain dry powder desulfurization ash. The dry powder desulfurization ash then enters the oxidation section 3 through the material inlet 6 on the left side of the partition 5 under the action of the stirring shaft 8. In the oxidation section 3, under the action of the stirring shaft 8, it undergoes a full oxidation reaction with the oxidant injected by the oxidant injection device 12. Under the action of the stirring shaft 8, it then enters the discharge section 4 through the material inlet 6 on the right side of the partition 5. Finally, under the action of the stirring shaft 8 in the discharge section 4, it is discharged through the discharge outlet 13 on the left side. Furthermore, during the treatment process, the residence time of the material in each section can be controlled by adjusting the independent motors 7 of each section, coordinating with the oxidant injection device 12 to achieve the desired oxidation effect. During the process, the gas generated by heating in the crushing and heating section 2 (or the dust contained in the desulfurization ash), the gas generated by the oxidation reaction in the oxidation section 3, and the water vapor evaporated from the oxidant (flowing counter-currently to the desulfurization ash) are discharged from the exhaust port 10 at the top. They can be further transported to external cooling and dust removal equipment for cooling and dust removal treatment.

[0043] The apparatus described in this application enables low-temperature oxidation of desulfurization ash in a dry powder state, achieving efficient and continuous production. It offers advantages such as simple operation, high equipment integration, small footprint, low energy consumption, and no secondary pollution, while also reducing disposal costs. This has practical significance in improving the secondary utilization value of desulfurization ash. Some embodiments of this application also possess the following advantages:

[0044] 1) This application incorporates a heat tracing device in the crushing and heating section. On one hand, heating the desulfurization ash, for example, to 100℃~150℃, removes free water from the ash, preventing excessive moisture content after subsequent oxidant injection. This ensures oxidation in a dry powder state, avoiding wastewater generation and operational complexity issues associated with reactions in solution conditions. On the other hand, heating the ash increases its temperature, facilitating efficient and rapid subsequent oxidation reactions. This approach offers advantages such as low oxidation temperature, high reaction efficiency, low energy consumption, and low operating costs.

[0045] 2) This application sets up an independent motor-driven stirring shaft in each section, which can realize the control of the residence time of desulfurization ash in each section. At the same time, an oxidant injection device is set in the oxidation section. By adjusting the amount of oxidant injected, the ideal oxidation effect can be achieved. The control method is flexible, the operation is simple, and it can be continuously scaled up for production.

[0046] The description of this invention is given for illustrative and descriptive purposes only and is not intended to be exhaustive or to limit the invention to the forms disclosed. Many modifications and variations will be apparent to those skilled in the art. The embodiments were chosen and described in order to better illustrate the principles and practical application of the invention and to enable those skilled in the art to understand the invention and to design various embodiments with various modifications suitable for a particular purpose.

Claims

1. A dry low-temperature oxidation device for desulfurized ash, characterized in that, The device includes a main body, which is divided into a crushing and heating section, an oxidation section and a discharge section from top to bottom. A partition is provided between adjacent sections, and a material outlet is provided on the partition. The crushing and heating section, oxidation section, and discharge section are all equipped with independent motor-driven stirring shafts; The crushing and heating section is equipped with a heat tracing device, and the crushing and heating section has a feed inlet and an exhaust outlet; An oxidant injection device is provided above the stirring shaft of the oxidation section; The discharge section is equipped with a discharge port.

2. The dry low-temperature oxidation device for desulfurized ash according to claim 1, characterized in that, The partition has a U-shaped structure.

3. The dry low-temperature oxidation device for desulfurized ash according to claim 2, characterized in that, Both ends of the partition are connected to inclined plates, which are fixedly installed on the inner wall of the device body.

4. The dry low-temperature oxidation device for desulfurized ash according to claim 2, characterized in that, The partition between the crushing heating section and the oxidation section has a double-layer structure, and the heat tracing device is installed inside it.

5. The dry low-temperature oxidation device for desulfurized ash according to claim 1, characterized in that, The motor is a frequency converter motor, and the stirring shaft is equipped with several sets of stirring blades.

6. The dry low-temperature oxidation device for desulfurized ash according to claim 1, characterized in that, The material inlet is located at the end of the partition and on the side of the direction of desulfurization ash flow.

7. The dry low-temperature oxidation device for desulfurized ash according to claim 1, characterized in that, The oxidant injection device is externally connected to an oxidant supply system, and the oxidant solution in the oxidant supply system is one or more of hydrogen peroxide, potassium permanganate, and hypochlorite.

8. The dry low-temperature oxidation device for desulfurized ash according to claim 1, characterized in that, The heating device is used to control the heating temperature in the crushing heating section to be between 100℃ and 150℃. And / or, the heat tracing device is a steam heat tracing device or an electric heating type heat tracing device.

9. The dry low-temperature oxidation device for desulfurized ash according to claim 1, characterized in that, The oxidant injection device includes several sets of distribution branches arranged along the stirring shaft, and each set of distribution branches is equipped with several sets of nozzles.

10. A method for dry low-temperature oxidation of desulfurized ash using the dry low-temperature oxidation device according to any one of claims 1-9, characterized in that, include: Desulfurization ash is fed into the crushing and heating section through the feed inlet. Under the action of the stirring shaft and heating device in the crushing and heating section, it is stirred, crushed, and heated to form dry powder desulfurization ash. The dry powder desulfurization ash then enters the oxidation section through the material inlet on the partition plate under the action of the stirring shaft. In the oxidation section, under the action of the stirring shaft, it undergoes an oxidation reaction with the oxidant injected by the oxidant injection device. The oxidation reaction temperature is below 200℃. Under the action of the stirring shaft, it then enters the discharge section through the material inlet on the partition plate and is discharged through the discharge port under the action of the stirring shaft in the discharge section. The gas generated by the heating in the crushing and heating section and the gas and water vapor generated after the oxidation reaction in the oxidation section are discharged through the exhaust port of the crushing and heating section.

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