A system and method for efficient semi-dry deacidification

Abstract

The present invention discloses a system and method for efficient semi-dry deacidification, which includes an additive device, a lime adding device, a slurry preparation tank, a colloid mill, a finished product tank and an SDA deacidification tower; wherein the additive device and the lime adding device are both connected to the top inlet of the slurry preparation tank through a pipeline, and the slurry preparation tank is sequentially connected to the colloid mill, the finished product tank and the SDA deacidification tower through a pipeline. The present invention adds additives to the lime slurry and performs grinding treatment, which significantly reduces the size of the lime particles, increases the specific surface area of ​​the lime slurry, and increases its contact area and reaction activity with the acidic gas in the flue gas, thereby significantly enhancing the deacidification efficiency. At the same time, after the lime slurry undergoes a semi-dry reaction in the deacidification tower, it is dehydrated and dried to form highly active lime particles, and the deacidification reaction continues to be carried out, thereby improving the overall deacidification efficiency and lime utilization rate. Compared with traditional processes, the deacidification efficiency of the present invention is higher and can better adapt to increasingly stringent pollutant emission standards.

Description

Technical Field

[0001] The invention belongs to the technical field of environmentally friendly flue gas purification, and in particular relates to a system and method for efficient semi-dry deacidification. Background Art

[0002] With the acceleration of urbanization and the continuous growth of population, the problem of domestic waste treatment has become increasingly prominent. Domestic waste incineration, as an effective treatment method, can not only effectively reduce the volume of waste, but also achieve resource reuse through heat recovery. However, the flue gas generated during the incineration of domestic waste contains a large amount of acidic gases, such as sulfur dioxide (SO2) and hydrogen chloride (HCl). If these acidic gases are directly discharged without treatment, they will cause serious pollution to the environment.

[0003] In order to control the emission of flue gas from domestic waste incinerators, the deacidification process has become a key link in flue gas treatment. At present, the mainstream deacidification process for domestic waste incinerators is the lime slurry rotary spray desulfurization process (SDA). This process uses slaked lime as a desulfurizer, and uses a high-speed rotating atomizer to atomize the slaked lime slurry into droplets with a diameter of less than 100μm, which react with the acidic gas in the flue gas to achieve the purpose of deacidification. However, with the continuous improvement of environmental protection requirements and the increasingly stringent pollutant emission standards, the traditional SDA process has been difficult to meet the current environmental governance needs. First, the traditional SDA process can achieve a certain deacidification effect when treating flue gas containing only domestic waste incineration. However, with the addition of industrial waste, the acidic gas composition in the flue gas becomes more complex, and the concentration of acidic gas also increases significantly, which makes the traditional SDA process in terms of deacidification efficiency. In addition, although the slaked lime used in the traditional SDA process has a certain desulfurization efficiency, its specific surface area is relatively small and its reaction activity is limited, resulting in a slow deacidification reaction rate and an unsatisfactory deacidification effect. Especially when treating flue gas containing high concentration of acidic gas, its deacidification efficiency is difficult to meet environmental protection requirements.

[0004] In order to solve the above problems, high-activity slaked lime has been rapidly developed in recent years. High-activity slaked lime has a very high specific surface area and reactivity, and can quickly react with the acidic gas in the flue gas to achieve efficient deacidification. At the same time, the deacidification temperature of high-activity slaked lime is low, and it can achieve efficient deacidification at a lower temperature, which is of great significance for reducing energy consumption and improving economic benefits.

[0005] Therefore, developing a new SDA process based on highly active slaked lime to improve deacidification efficiency and meet increasingly stringent pollutant emission standards has become a research hotspot and urgent need in the field of flue gas treatment in municipal solid waste incinerators. Summary of the invention

[0006] In view of the deficiencies in the prior art, the present invention provides a system and method for highly efficient semi-dry deacidification, which has the advantages of high deacidification efficiency, can significantly reduce the acid gas content in flue gas, and reduce pollution to the environment.

[0007] The present invention is achieved through the following technical solutions:

[0008] A highly efficient semi-dry deacidification system comprises an additive device, a lime adding device, a slurry preparation tank, a colloid mill, a finished product tank and an SDA deacidification tower; wherein the additive device and the lime adding device are both connected to the top inlet of the slurry preparation tank through a pipeline, a pipeline is provided at the bottom outlet of the slurry preparation tank to be connected to the inlet of the colloid mill, a pipeline is provided at the outlet of the colloid mill to be connected to the top inlet of the finished product tank, and the bottom outlet of the finished product tank is connected to the rotary atomizer of the SDA deacidification tower through a pipeline.

[0009] Preferably, a delivery pump is provided on the pipeline between the finished product tank and the SDA deacidification tower.

[0010] Preferably, a pipeline is provided at the outlet of the delivery pump to be connected back to the top inlet of the slurry preparation tank.

[0011] Preferably, a circulation pump is further included, and a pipeline is provided at the bottom outlet of the finished product tank to connect to the inlet of the circulation pump, and a pipeline is provided at the outlet of the circulation pump to connect back to the top inlet of the slurry mixing tank.

[0012] Preferably, there are more than one slurry preparation tanks, and all of them are connected to the additive device, the lime adding device, and the colloid mill through pipelines.

[0013] An efficient semi-dry deacidification method based on the above system comprises the following steps:

[0014] Step 1) respectively adding additives and lime into a slurry preparation tank in proportion through an additive device and a lime adding device, and adding water into the slurry preparation tank to prepare 8-12% lime slurry;

[0015] Step 2) The bottom outlet of the slurry preparation tank is opened, and the prepared lime slurry is first passed through a colloid mill to grind the lime particles in the lime slurry to less than 1 μm. The lime slurry ground by the colloid mill is sent to the finished product tank, and then pumped into the rotary atomizer of the SDA deacidification tower through a delivery pump. Under the action of the rotary atomizer, the lime slurry is atomized into droplets and sprayed into the SDA deacidification tower; the lime slurry droplets are dried by the flue gas while being deacidified in the SDA deacidification tower, forming ultrafine lime particles with a high specific surface area to continue to absorb acidic gases, thereby completing the operation.

[0016] Preferably, the lime in step 1) is slaked lime or quicklime with a mesh size ≥ 200 mesh; the content of Ca(OH)2 in the slaked lime is > 90%; the content of CaO in the quicklime is > 85%.

[0017] Preferably, the additive in step 1) is one or more of alcohols, sucrose, and anionic surfactants; and the amount of the additive is 3% of the weight of the lime.

[0018] Preferably, in step 2), the lime particles in the lime slurry are ground to less than 0.5 μm.

[0019] Preferably, the method further includes step 3): a portion of the lime slurry pumped into the SDA deacidification tower is returned to the slurry preparation tank through a delivery pump, or the lime slurry is directly pumped back to the slurry preparation tank through an additional pipeline and a circulation pump, and the returned lime slurry is ground by a colloid mill and returned to the finished product tank. The lime slurry is ground multiple times to form finer lime particles, which has a better deacidification effect.

[0020] The beneficial effects of the present invention are as follows:

[0021] (1) The present invention adds additives to the lime slurry and performs grinding treatment, which effectively inhibits the crystallization process of slaked lime, thereby significantly reducing the size of lime particles. This pretreatment step greatly increases the specific surface area of ​​the lime particles in the lime slurry, increases the contact area and reaction activity with the acidic gas in the flue gas, and thus significantly enhances the deacidification efficiency. Compared with the traditional process, the deacidification efficiency of the present invention is higher and can better meet the increasingly stringent pollutant emission standards.

[0022] (2) The pretreated lime slurry is sprayed into the deacidification tower through a rotary atomizer, fully mixed with the flue gas and dried to form highly active lime particles. These highly active lime particles are small in size and have a porous surface. They not only have stronger deacidification capabilities, but can also continue the deacidification reaction at a lower temperature, thereby reducing energy consumption and operating costs. In addition, due to the small size of the lime particles, they stay in the deacidification tower for a longer time and can react more fully with the acid gases in the flue gas, further improving the deacidification efficiency.

[0023] (3) The present invention realizes the combined application of semi-dry deacidification and high-activity lime deacidification. This combination not only gives full play to the advantages of the two deacidification technologies, but also makes the entire deacidification system more efficient and stable through mutual complementation and reinforcement. In practical applications, the present invention can significantly reduce the acid gas content in flue gas, reduce environmental pollution, and reduce the environmental pressure and economic burden of enterprises. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the structure of a system for efficient semi-dry deacidification;

[0025] In the figure: 1. Additive device; 2. Lime adding device; 3. Slurry preparation tank; 4. Colloid mill; 5. Finished product tank; 6. SDA deacidification tower; 7. Delivery pump; 8. Valve. DETAILED DESCRIPTION

[0026] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] Example 1

[0028] A highly efficient semi-dry deacidification system, such as Figure 1 As shown, it includes an additive device 1, a lime adding device 2, a slurry preparation tank 3, a colloid mill 4, a finished product tank 5 and an SDA deacidification tower 6; wherein the additive device 1 and the lime adding device 2 are both connected to the top inlet of the slurry preparation tank 3 through a pipeline, a pipeline is provided at the bottom outlet of the slurry preparation tank 3 to be connected to the inlet of the colloid mill 4, a pipeline is provided at the outlet of the colloid mill 4 to be connected to the top inlet of the finished product tank 5, and the bottom outlet of the finished product tank 5 is connected to the rotary atomizer of the SDA deacidification tower 6 through a pipeline.

[0029] like Figure 1 As shown, a delivery pump 7 is provided on the pipeline between the finished product tank 5 and the SDA deacidification tower 6, which is used to pump the lime slurry ground by the colloid mill 4 into the SDA deacidification tower 6. At the same time, a pipeline (a valve 8 is provided on the pipeline) is provided at the outlet of the delivery pump 7 to be connected back to the top inlet of the slurry preparation tank 3, so that a part of the pumped lime slurry can be returned to the slurry preparation tank 3, and the returned lime slurry is returned to the finished product tank 5 after being ground by the colloid mill 4.

[0030] A preferred solution is to set up a separate circulation pump to circulate the ground lime slurry, that is, set up a pipeline at the bottom outlet of the finished product tank 5 to connect back to the top inlet of the slurry mixing tank 3, and set a circulation pump and valve 8 on the pipeline.

[0031] like Figure 1 As shown, in this embodiment, the number of the slurry preparation tanks 3 is more than one, and all are connected to the additive device 1, the lime adding device 2, and the colloid mill 4 through pipelines.

[0032] An efficient semi-dry deacidification method based on the above system, the specific steps are as follows:

[0033] (1) Additives and lime are added into a slurry preparation tank 3 according to a certain proportion through an additive device 1 and a lime adding device 2, and water is added into the slurry preparation tank 3 to prepare a lime slurry with a concentration of 8 to 12%.

[0034] The lime can be slaked lime or quicklime. Slaked lime requires a Ca(OH)2 content of >90% and a size of 200 mesh or more; quicklime requires a CaO content of >85% and a size of 200 mesh or more.

[0035] The additive can be a mixture of one or more of alcohols, sucrose, and anionic surfactants; the amount of the additive is 3% of the weight of the lime.

[0036] (2) The bottom outlet of the slurry preparation tank 3 is opened, and the prepared lime slurry is first passed through the colloid mill 4 to grind the lime particles in the lime slurry to less than 1 μm (preferably less than 0.5 μm). The lime slurry ground by the colloid mill 4 is sent to the finished product tank 5, and then pumped into the rotary atomizer of the SDA deacidification tower 6 through the delivery pump 7. Under the action of the rotary atomizer, the lime slurry is atomized into droplets and sprayed into the SDA deacidification tower 6; the lime slurry droplets are dried by the flue gas while being deacidified in the SDA deacidification tower 6, forming a high specific surface area (BET>30m 2 / g), and the ultra-fine lime particles continue to absorb the acid gas to complete the operation.

[0037] (3) The lime slurry can also be repeatedly ground by the colloid mill 4 in a circulating manner. A portion of the lime slurry pumped into the SDA deacidification tower 6 is returned to the slurry preparation tank 3 by the delivery pump 7, or the lime slurry is directly pumped back from the finished product tank 5 to the slurry preparation tank 3 by another pipeline and a circulation pump. The reflux amount can be controlled according to the opening of the valve 8. The returned lime slurry is ground by the colloid mill 4 and then returned to the finished product tank 5. The lime slurry is ground multiple times to form finer lime particles, which has a better deacidification effect.

[0038] The embodiments described above are only some embodiments of the present invention, rather than all embodiments. The detailed description of the embodiments of the present invention is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. The scope of protection of the present invention shall be subject to the scope required by the claims. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work shall fall within the scope of protection of the present invention.

Claims

1. A highly efficient semi-dry deacidification system, characterized in that: It comprises an additive device, a lime adding device, a slurry preparation tank, a colloid mill, a finished product tank and an SDA deacidification tower; wherein the additive device and the lime adding device are both connected to the top inlet of the slurry preparation tank through a pipeline, a pipeline is provided at the bottom outlet of the slurry preparation tank to connect to the inlet of the colloid mill, a pipeline is provided at the outlet of the colloid mill to connect to the top inlet of the finished product tank, and the bottom outlet of the finished product tank is connected to the rotary atomizer of the SDA deacidification tower through a pipeline; A delivery pump is provided on the pipeline between the finished product tank and the SDA deacidification tower; A pipeline is provided at the outlet of the delivery pump to be connected back to the top inlet of the slurry mixing tank; It also includes a circulation pump. A pipeline is arranged at the bottom outlet of the finished product tank to be connected to the inlet of the circulation pump. A pipeline is arranged at the outlet of the circulation pump to be connected back to the top inlet of the slurry mixing tank.

2. The system for efficient semi-dry deacidification according to claim 1, characterized in that: The number of the slurry preparation tanks is more than one, and all of them are connected with the additive device, the lime adding device and the colloid mill through pipelines.

3. A highly efficient semi-dry deacidification method based on the system of claim 1 or 2, characterized in that: The following steps are involved: Step 1) respectively adding additives and lime into a slurry preparation tank in proportion through an additive device and a lime adding device, and adding water into the slurry preparation tank to prepare 8-12% lime slurry; Step 2) Open the bottom outlet of the slurry preparation tank, and the prepared lime slurry is first passed through a colloid mill to grind the lime particles in the lime slurry to less than 1 μm. The lime slurry ground by the colloid mill is sent to the finished product tank, and then pumped into the rotary atomizer of the SDA deacidification tower through a delivery pump. Under the action of the rotary atomizer, the lime slurry is atomized into droplets and sprayed into the SDA deacidification tower; the lime slurry droplets are dried by the flue gas while being deacidified in the SDA deacidification tower, forming ultra-fine lime particles with a high specific surface area to continue to absorb acidic gases, completing the operation.

4. The method for efficient semi-dry deacidification according to claim 3, characterized in that: Step 1) The lime is slaked lime or quicklime with a mesh size of ≥200 mesh; the content of Ca(OH)2 in the slaked lime is >90%; the content of CaO in the quicklime is >85%.

5. The method for efficient semi-dry deacidification according to claim 3, characterized in that: Step 1) The additive is one or more of alcohols, sucrose, and anionic surfactants; the amount of the additive is 3% of the weight of the lime.

6. The method for efficient semi-dry deacidification according to claim 3, characterized in that: In the step 2), the lime particles in the lime slurry are ground to less than 0.5 μm.

7. The method for efficient semi-dry deacidification according to claim 3, characterized in that: The method also includes step 3): a portion of the lime slurry pumped into the SDA deacidification tower is returned to the slurry preparation tank through a delivery pump, or the lime slurry is directly pumped back to the slurry preparation tank through an additional pipeline and a circulation pump, and the returned lime slurry is ground by a colloid mill and returned to the finished product tank. The lime slurry is ground multiple times to form finer lime particles, which has a better deacidification effect.

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