A method suitable for double alkali desulfurization

Abstract

The present invention discloses a method for double alkali desulfurization, which relates to the field of double alkali desulfurization. The method comprises the following steps: step 1: cooling the flue gas, wherein a ventilation pipe is provided on the outer wall of the flue gas duct; step 2: desulfurization reaction, wherein the flue gas after cooling enters the desulfurization tower and is sprayed with alkali solution; step 3: high temperature decomposition, wherein the bottom of the calcium sulfite collecting tank is heated at high temperature; step 4: oxidation and reduction, wherein the calcium sulfite collecting tank is in contact with the air; step 5: desulfurization and reduction, wherein the calcium sulfite is pushed into the regeneration tank by a pushing mechanism to react with the desulfurization liquid. The calcium sulfite of the present invention is decomposed into calcium oxide and sulfur dioxide by heat, and the sulfur dioxide is directly discharged after being detected inside the desulfurization tower. The internal calcium oxide absorbs moisture in the air to generate calcium hydroxide, which can then be discharged into the regeneration tank to facilitate the reduction of the desulfurization liquid into an absorbent. This process prevents the calcium sulfite from being blocked while reducing the workload of the staff in subsequent processing.

Description

Technical Field

[0001] The invention relates to the field of double alkali desulfurization, in particular to a processing method suitable for double alkali desulfurization. Background Art

[0002] The double alkali desulfurization technology uses sodium hydroxide solution as a starting desulfurization agent. The prepared sodium hydroxide solution is directly injected into the desulfurization tower to wash and remove sulfur dioxide in the flue gas to achieve the purpose of flue gas desulfurization.

[0003] Desulfurizer regeneration generally involves reacting the desulfurization product sodium sulfite with calcium hydroxide to generate calcium sulfite precipitate and sodium hydroxide solution. Some calcium hydroxide may remain in the recycled sodium hydroxide solution, and the calcium hydroxide will react with sulfur dioxide in the desulfurization tower to generate calcium sulfite precipitate.

[0004] Chinese patent publication number CN101502754 A provides an energy-saving dual-alkali desulfurization process. This process involves sending flue gas drawn from the tunnel kiln head into an air heat exchange system to exchange heat with cold air entering the system from the outside, and then sending the heated cold air into the gasifier for use as a combustion aid and oxidant. This not only saves the gasifier energy by approximately 8%, but also makes the cooled flue gas more conducive to the absorption of alkali solution.

[0005] Since it is difficult to discharge the calcium sulfite precipitate generated in the desulfurization tower during the desulfurization process of the above-mentioned mechanism, it will cause siltation and precipitation in the desulfurization tower, which will not only affect the desulfurization reaction, but also cause scaling and blockage in the desulfurization tower. Summary of the Invention

[0006] Based on this, the purpose of the present invention is to provide a double alkali desulfurization processing method to solve the technical problem that it is difficult to discharge the calcium sulfite precipitate generated in the desulfurization tower during the desulfurization process of the above-mentioned mechanism, which will cause siltation and precipitation in the desulfurization tower, not only affecting the desulfurization reaction, but also causing scaling and blockage in the desulfurization tower.

[0007] To achieve the above object, the present invention provides the following technical solution: a double alkali desulfurization processing method, comprising the following steps:

[0008] Step 1: Cooling the flue gas. A ventilation pipe is provided on the outer wall of the flue gas duct. One end of the ventilation pipe is connected to its fan. The fan is started to absorb the cold air from the outside and flow through the ventilation pipe on the outer wall of the flue gas duct.

[0009] Step 2: Desulfurization reaction: The cooled flue gas enters the desulfurization tower. Alkali solution is sprayed on the top of the desulfurization tower. The flue gas moves upward and reacts with the alkali solution sprayed downward in a countercurrent manner. It is then discharged into the atmosphere through the online detection system in the desulfurization tower.

[0010] Step 3: Pyrolysis: A calcium sulfite collection tank is provided at the bottom of the desulfurization tower. The calcium sulfite generated after the reaction is collected inside the collection tank. At the same time, an array of U-shaped tubes are evenly installed at the bottom of the calcium sulfite collection tank. The other end of the ventilation pipe is connected to one end of the U-shaped tube, and the calcium sulfite collection tank is heated at high temperature.

[0011] Step 4: Oxidation-reduction: The calcium sulfite collection tank is exposed to the air, and the internal sediment absorbs and oxidizes the moisture in the air;

[0012] Step 5: Desulfurization reduction: push it into the regeneration pool through the pushing mechanism to react with its desulfurization liquid.

[0013] By adopting the above technical solution, calcium sulfite is decomposed into calcium oxide and sulfur dioxide by heat. The sulfur dioxide can be discharged directly after being detected inside the desulfurization tower. The internal calcium oxide absorbs moisture in the air to generate calcium hydroxide, which can then be discharged into the regeneration pool to facilitate the reduction of the desulfurization liquid into an absorbent for reuse. This process prevents calcium sulfite from clogging and reduces the workload of the staff in subsequent handling.

[0014] The present invention is further configured such that the ventilation pipe in step one is arranged in a ring shape as a whole and surrounds the outer wall of the ventilation pipe.

[0015] By adopting the above technical solution, the annular surrounding arrangement makes it easy to increase the heat exchange area with the ventilation pipe, thereby achieving rapid cooling of the internal flue gas.

[0016] The present invention is further configured such that a plurality of swirl plates are provided on the top of the desulfurization tower in the step 2, and nozzles are provided on the swirl plates.

[0017] By adopting the above technical solution, the coordination between the swirl plate and the nozzle facilitates increasing the spraying area of ​​the alkali solution inside, improving the contact area between the alkali solution and the flue gas, and accelerating the reaction itself.

[0018] The present invention is further configured such that an array of heating wires is also provided at the bottom of the three calcium sulfite collecting tanks in the steps.

[0019] By adopting the above technical solution, the calcium sulfite collection tank can be quickly heated by the electric heating wire in coordination with the temperature of the flue gas, thereby improving its overall reaction efficiency.

[0020] The present invention is further configured such that the heating temperature of the heating wire is 600-700°C.

[0021] By adopting the above technical solution, the calcium sulfite itself can be thermally decomposed after the temperature is increased. When the flue gas temperature is not high enough, the electric heating wire itself can also be used for heating.

[0022] The present invention is further configured such that the pushing mechanism in step five includes a pushing cylinder, and the pushing cylinder is located outside the desulfurization tower.

[0023] By adopting the above technical solution, the calcium hydroxide that has absorbed water in the calcium sulfite collection tank can be pushed into the regeneration tank by pushing the cylinder to reduce its desulfurization liquid into an absorbent.

[0024] The present invention is further configured such that a stirring mechanism is provided in the regeneration tank in step five.

[0025] By adopting the above technical solution, calcium hydroxide and its desulfurization liquid can be quickly reacted and reduced, thereby improving the overall processing efficiency.

[0026] In summary, the present invention mainly has the following beneficial effects:

[0027] The present invention provides a calcium sulfite collecting tank at the bottom of the desulfurization tower. During operation, the high temperature of the flue gas is used to preheat the cold air through an external fan, so that the flue gas temperature drops, which is convenient for rapid reaction with the sodium hydroxide in the subsequent desulfurization tower. A U-shaped tube and an electric heating wire are provided at the bottom of the calcium sulfite collecting tank. The air heated by the flue gas cooperates with the electric heating wire to increase its overall temperature, so that the calcium sulfite is decomposed into calcium oxide and sulfur dioxide by heat. The sulfur dioxide can be directly discharged after being detected inside the desulfurization tower. The internal calcium oxide absorbs moisture in the air to generate calcium hydroxide. The calcium hydroxide can then be discharged into a regeneration pool to facilitate the reduction of the desulfurization liquid into an absorbent for repeated use. This process prevents the calcium sulfite from being blocked and reduces the workload of the staff in subsequent processing. DETAILED DESCRIPTION

[0028] The following is a clear and complete description of the technical solutions in the embodiments of the present invention, which is only used to explain the present invention and is not to be construed as limiting the present invention.

[0029] The following describes an embodiment of the present invention based on its overall structure.

[0030] A double alkali desulfurization process comprising the following steps:

[0031] Step 1: Cooling the flue gas. A ventilation pipe is provided on the outer wall of the flue gas duct, one end of which is connected to its fan. The fan is started to absorb cold air from the outside and flow in the ventilation pipe on the outer wall of the flue gas duct. During operation, the high temperature of the flue gas is preheated by the external fan to cool the cold air, thereby lowering the flue gas temperature and facilitating a rapid reaction with the sodium hydroxide in the subsequent desulfurization tower. The ventilation pipe is arranged in an annular shape as a whole and surrounds the outer wall of the ventilation pipe. The annular surrounding arrangement is convenient for increasing the heat exchange area between the ventilation pipe and the ventilation pipe, thereby achieving rapid cooling of the internal flue gas.

[0032] Step 2: Desulfurization reaction. The cooled flue gas enters the desulfurization tower. Alkali solution is sprayed on the top of the desulfurization tower. The flue gas moves upward and reacts with the alkali solution sprayed downward in a countercurrent manner. Then, it is discharged into the atmosphere through the online detection system in the desulfurization tower. Multiple groups of swirl plates are installed on the top of the desulfurization tower, and nozzles are installed on the swirl plates to fully absorb acidic gases such as sulfur dioxide and sulfur trioxide in the flue gas, generating sodium sulfate and sodium bisulfate. The cooperation between the swirl plates and the nozzles increases the spraying area of ​​the alkali solution inside, improves the contact area between the alkali solution and the flue gas, and accelerates its own reaction.

[0033] Step 3: high-temperature decomposition. A calcium sulfite collecting tank is provided at the bottom of the desulfurization tower. The calcium sulfite precipitated after the reaction is collected inside the collecting tank. At the same time, an array of U-shaped tubes are evenly installed at the bottom of the calcium sulfite collecting tank. The other end of the ventilation pipe is connected to one end of the U-shaped tube to heat the calcium sulfite collecting tank at high temperature. An array of heating wires is also provided at the bottom of the calcium sulfite collecting tank. The heating wires can be used to quickly heat the calcium sulfite collecting tank in accordance with the temperature of the flue gas, thereby improving the overall reaction efficiency. The heating temperature of the heating wires is 650°C, which is convenient for thermal decomposition of the calcium sulfite itself after heating. If the flue gas temperature is not high enough, the heating wires themselves can also be used for heating, so that the calcium sulfite is thermally decomposed into calcium oxide and sulfur dioxide. The sulfur dioxide can be directly discharged after being detected inside the desulfurization tower.

[0034] Step 4: Oxidation-reduction: The calcium sulfite collection tank is exposed to the air as a whole, and the internal precipitate absorbs and oxidizes the moisture in the air. The calcium oxide decomposed by heat inside absorbs the moisture in the air to form calcium hydroxide;

[0035] Step 5: Desulfurization and reduction. The calcium hydroxide is pushed into the regeneration tank by a pushing mechanism to react with its desulfurization liquid. The pushing mechanism includes a pushing cylinder, and the pushing cylinder is located outside the desulfurization tower. The calcium hydroxide that absorbs water in the calcium sulfite collection tank can be pushed into the regeneration tank by the pushing cylinder to reduce its desulfurization liquid into an absorbent for reuse. A stirring mechanism is provided in the regeneration tank to facilitate the rapid reaction and reduction of calcium hydroxide with its desulfurization liquid, thereby improving its overall processing efficiency.

[0036] Although an embodiment of the present invention has been shown and described, this specific embodiment is merely an explanation of the present invention and is not a limitation of the invention. The specific features, structures, materials or characteristics described may be combined in an appropriate manner in any one or more embodiments or examples. After reading this specification, those skilled in the art may make modifications, substitutions and variations to the embodiment without creative contribution as needed without departing from the principles and purpose of the present invention. However, as long as they are within the scope of the claims of the present invention, they are protected by patent law.

Claims

1. A double alkali desulfurization process, characterized by: The following steps are involved: Step 1: Cooling the flue gas. A ventilation pipe is provided on the outer wall of the flue gas duct. One end of the ventilation pipe is connected to its fan. The fan is started to absorb the cold air from the outside and flow through the ventilation pipe on the outer wall of the flue gas duct. Step 2: Desulfurization reaction: The cooled flue gas enters the desulfurization tower. Alkali solution is sprayed on the top of the desulfurization tower. The flue gas moves upward and reacts with the alkali solution sprayed downward in a countercurrent manner. It is then discharged into the atmosphere through the online detection system in the desulfurization tower. Step 3: Pyrolysis: A calcium sulfite collection tank is provided at the bottom of the desulfurization tower. The calcium sulfite generated after the reaction is collected inside the collection tank. At the same time, an array of U-shaped tubes are evenly installed at the bottom of the calcium sulfite collection tank. The other end of the ventilation pipe is connected to one end of the U-shaped tube, and the calcium sulfite collection tank is heated at high temperature. Step 4: Oxidation-reduction: The calcium sulfite collection tank is exposed to the air, and the internal sediment absorbs and oxidizes the moisture in the air; Step 5: Desulfurization reduction: push it into the regeneration pool through the pushing mechanism to react with its desulfurization liquid.

2. The method according to claim 1, wherein: The ventilation pipe in step 1 is arranged in a ring shape as a whole and surrounds the outer wall of the ventilation pipe.

3. The method according to claim 1, wherein: In the step 2, a plurality of swirl plates are provided on the top of the desulfurization tower, and nozzles are provided on the swirl plates.

4. The method according to claim 1, wherein: In the three steps, the bottom of the calcium sulfite collecting tank is also provided with an array of heating wires.

5. The method according to claim 4, wherein: The heating temperature of the heating wire is 600-700°C.

6. The method according to claim 1, wherein: The pushing mechanism in step five includes a pushing cylinder, and the pushing cylinder is located outside the desulfurization tower.

7. The method according to claim 1, wherein: A stirring mechanism is provided in the regeneration tank in step five.