Calcium hydroxide-based flue gas desulfurizer

Abstract

The present application relates to the technical field of flue gas desulfurizer, particularly relates to a calcium hydroxide-based flue gas desulfurizer, which comprises the following components in parts by weight: modified calcium hydroxide 100 parts, coal ash slag 30-50 parts, ceramic granule crushing product 20-40 parts, iron oxide 5-10 parts, magnesium oxide 2-8 parts, hydroxyapatite 5-8 parts, and sodium-based bentonite 5-10 parts. Compared with the current desulfurizer, the desulfurizer improves the void, improves the surface characteristics of calcium hydroxide, and avoids the influence of the produced calcium sulfate on the desulfurization effect in the later period. Overall, the desulfurizer not only has sufficient strength, but also has good desulfurization efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of flue gas desulfurizer, in particular to a calcium hydroxide-based flue gas desulfurizer. BACKGROUND

[0002] Sulfur dioxide is a harmful byproduct in many industrial processes. Coal and oil combustion are the main sources of sulfur dioxide emissions in industrial processes, so power plants, steel mills, petrochemical plants, and other industrial processes that use coal or oil as energy will produce a large amount of sulfur dioxide. In addition, the metallurgical industry, such as copper smelting, zinc smelting, steel smelting, etc., is also an important source of sulfur dioxide; other aspects, such as some chemical reactions in the chemical industry, including high-temperature furnaces and kilns, will also produce sulfur dioxide.

[0003] Because sulfur dioxide is harmful to the environment and human health, if sulfur dioxide is directly discharged into the atmosphere in industrial production, the pollution of sulfur dioxide to the air is quite serious. Therefore, it is necessary to remove sulfur dioxide from flue gas, and reducing and controlling sulfur dioxide emissions is an important task to protect the environment and improve air quality.

[0004] Flue gas desulfurizer is a chemical substance used to reduce the content of sulfur dioxide (SO2) in industrial flue gas. Flue gas desulfurizer can react with SO2 in flue gas to convert it into relatively harmless compounds or precipitates, thereby achieving the purpose of reducing air pollution. The use of flue gas desulfurizer can effectively reduce the emission of sulfur dioxide in industrial flue gas, reduce air pollution and the formation of acid rain. However, the use of flue gas desulfurizer will also produce some by-products and waste, which need to be properly treated and disposed of to avoid other pollution problems to the environment.

[0005] Common flue gas desulfurizers include limestone, gypsum, and ammonia water, etc. Among them, limestone is one of the most commonly used flue gas desulfurizers. Limestone reacts with SO2 to form calcium sulfate (CaSO4), which can be treated as solid waste or used to produce building materials, etc. Gypsum is also a commonly used desulfurizer, which reacts with SO2 to form calcium sulfate, which can also be used for waste treatment or other purposes. Therefore, calcium hydroxide-based flue gas desulfurizer is one of the most important desulfurizers.

[0006] Calcium hydroxide desulfurizer has high desulfurization efficiency and low cost, and is widely used in flue gas desulfurization processes in coal-fired power plants, steel mills, chemical plants, and other industrial fields.

[0007] Based on the reaction between SO2 and alkaline substances or in alkaline solution or on the wet surface of solid alkaline substances, flue gas desulfurization can be divided into wet desulfurization and dry desulfurization. Wet flue gas desulfurization has the advantages of fast desulfurization reaction speed, simple equipment, high desulfurization efficiency, but generally has the problems of serious corrosion, high operation and maintenance cost and easy secondary pollution. The desulfurization absorption and product treatment of dry desulfurization technology are carried out in dry state, which has the advantages of no waste water and waste acid discharge, light equipment corrosion, no obvious temperature drop of flue gas in the purification process, high temperature of purified flue gas, easy diffusion of chimney exhaust, less secondary pollution, but has the problems of low desulfurization efficiency, slow reaction speed and large equipment.

[0008] In dry flue gas desulfurization, the existing calcium hydroxide desulfurizer is mainly composed of calcium hydroxide and a binder. Due to the single component, when the calcium hydroxide is high, the strength is very low, causing pulverization, and when the calcium hydroxide is low, the strength increases, but the sulfur capacity becomes very low, affecting the desulfurization effect. Therefore, the current desulfurizer has the problem that the strength and desulfurization effect cannot be considered. SUMMARY

[0009] The purpose of the present application is to solve the above problems, and a calcium hydroxide-based flue gas desulfurizer is provided, and a specific preparation method thereof is also provided.

[0010] Specifically, the present application adopts the following technical solutions:

[0011] A calcium hydroxide-based flue gas desulfurizer, comprising the following components by weight:

[0012] 100 parts of modified calcium hydroxide,

[0013] 30-50 parts of coal ash slag,

[0014] 20-40 parts of ceramic granule powder,

[0015] 5-10 parts of iron oxide,

[0016] 2-8 parts of magnesium oxide,

[0017] 5-8 parts of hydroxyapatite,

[0018] 5-10 parts of sodium-based bentonite.

[0019] As a preferred, the preparation steps of the modified calcium hydroxide are as follows: sodium hydroxide and sodium chloride are prepared into an aqueous solution, and a silane coupling agent is added into the aqueous solution at the same time, and finally the mass concentration of sodium hydroxide and sodium chloride in the prepared aqueous solution is 2-5%, and the concentration of the silane coupling agent is 3-8%;

[0020] Then the prepared aqueous solution is reacted with calcium oxide for 3-5 hours to generate calcium hydroxide paste, and then the paste is dried at a temperature not higher than 120 DEG C, and finally the dried product is crushed and ground to obtain modified calcium hydroxide.

[0021] Preferably, the ceramic particle fragments are large ceramic particles with a particle size greater than 3 cm, and then the fragments with a particle size greater than 0.5 cm are obtained by crushing.

[0022] Preferably, the coal ash slag has a particle size in the range of 2-8 mm.

[0023] Preferably, the preparation method of the flue gas desulfurizer comprises the following steps:

[0024] (1) Modified calcium hydroxide preparation, sodium hydroxide and sodium chloride are prepared into an aqueous solution, and a silane coupling agent is added into the aqueous solution, and finally the mass concentration of sodium hydroxide and sodium chloride in the prepared aqueous solution is 2-5%, and the concentration of the silane coupling agent is 3-8%; then the prepared aqueous solution is reacted with calcium oxide to generate calcium hydroxide paste, and then the paste is dried at a temperature not higher than 120 DEG C, and finally the dried product is crushed and ground to obtain modified calcium hydroxide;

[0025] (2) The coal ash slag, ceramic particle fragments, iron oxide, magnesium oxide and hydroxyapatite are stirred uniformly according to the predetermined proportion with the modified calcium hydroxide to obtain a mixture;

[0026] (3) Then, sodium bentonite is added into the mixture and stirred uniformly, and then 2-3% of carboxymethyl cellulose sodium aqueous solution is sprayed;

[0027] (4) Finally, the mixture is extruded to form a shaped product, and the shaped product is dried at a temperature of 100-120 DEG C.

[0028] Preferably, the hydroxyapatite, iron oxide, magnesium oxide and calcium oxide are passed through a 100-mesh sieve.

[0029] The present application has the following advantages:

[0030] The present application uses coal ash slag and ceramic particle fragments as a large skeleton for carrying particle powder, so as to form an extruded product with good structural strength, and uses the porous structure of the coal ash slag and the ceramic particle fragments to improve the gas passing rate.

[0031] The calcium hydroxide is modified, and the calcium hydroxide is improved by a silane coupling agent and sodium chloride and sodium hydroxide, so that the silane coupling agent forms a group on the surface of the calcium hydroxide crystal particles under alkaline conditions, which is beneficial to supplement sulfur dioxide gas, and meanwhile, the sodium ion changes the crystal structure of the original calcium hydroxide, so that defects are generated, thereby forming a pore distribution and pore size conducive to sulfur fixation, and finally improving the desulfurization effect.

[0032] The scheme has a large porous structure, and the modified calcium hydroxide has a microstructure, so that after the calcium hydroxide reacts with sulfur dioxide, the pores are not easily blocked by the produced calcium sulfate, and the desulfurization effect in the later stage is not affected. DETAILED DESCRIPTION

[0033] The embodiments will now be further detailed. It should be understood that the following description is not intended to limit the embodiments to one preferred embodiment. On the contrary, it is intended to cover alternatives, modifications, and equivalents, which can be included within the spirit and scope of the described embodiments as defined by the appended claims.

[0034] The general scheme of the present application is:

[0035] A calcium hydroxide-based flue gas desulfurizer, comprising the following components in parts by weight:

[0036] 100 parts of modified calcium hydroxide,

[0037] 30-50 parts of coal ash slag,

[0038] 20-40 parts of ceramic particle crushing,

[0039] 5-10 parts of iron oxide,

[0040] 2-8 parts of magnesium oxide,

[0041] 5-8 parts of hydroxyapatite,

[0042] 5-10 parts of sodium-based bentonite.

[0043] The ceramic particle crushing is large particle ceramic particles with a particle size greater than 3 cm, and then a crushing method is used to obtain crushed particles with a particle size greater than 0.5 cm. The particle size of the coal ash slag is in the range of 2-8 mm.

[0044] The preparation method of the flue gas desulfurizer comprises the following steps:

[0045] (1) Preparation of modified calcium hydroxide: Sodium hydroxide and sodium chloride are prepared into an aqueous solution, and a silane coupling agent is added to the aqueous solution. The mass concentration of sodium hydroxide and sodium chloride in the final aqueous solution is 2-5%, and the concentration of silane coupling agent is 3-8%. Then, the prepared aqueous solution is reacted with calcium oxide to generate calcium hydroxide paste. Then, it is dried at a temperature not higher than 120°C. Finally, the dried product is crushed and ground to obtain modified calcium hydroxide.

[0046] (2) Coal ash slag, ceramsite powder, iron oxide, magnesium oxide, hydroxyapatite and modified calcium hydroxide are mixed evenly according to a predetermined ratio to obtain a mixture; the hydroxyapatite, iron oxide, magnesium oxide and calcium oxide are passed through a 100-mesh sieve;

[0047] (3) Then, add sodium bentonite to the mixture, mix evenly, and then spray 2-3% sodium carboxymethyl cellulose aqueous solution;

[0048] (4) Finally, the mixture is extruded to obtain a molded product, and the molded product is dried at 100-120℃.

[0049] Example 1:

[0050] A calcium hydroxide-based flue gas desulfurizer comprises the following components in parts by weight:

[0051] 100 parts of modified calcium hydroxide,

[0052] 30 portions of coal ash and slag.

[0053] 40 parts of crushed ceramsite,

[0054] 5 parts iron oxide

[0055] 8 parts magnesium oxide

[0056] 5 parts hydroxyapatite

[0057] 10 parts of sodium bentonite.

[0058] The ceramsite powder is made from large ceramsite particles with a diameter greater than 3 cm, which are then crushed to obtain fragments with a diameter greater than 0.5 cm. The particle size of the coal ash slag is in the range of 2-8 mm.

[0059] The preparation method of flue gas desulfurizing agent includes the following steps:

[0060] (1) Preparation of modified calcium hydroxide: Sodium hydroxide and sodium chloride are prepared into an aqueous solution, and a silane coupling agent is added to the aqueous solution. The mass concentration of sodium hydroxide and sodium chloride in the final aqueous solution is 2-5%, and the concentration of silane coupling agent is 3-8%. Then, the prepared aqueous solution is reacted with calcium oxide to generate calcium hydroxide paste. Then, it is dried at a temperature not higher than 120°C. Finally, the dried product is crushed and ground to obtain modified calcium hydroxide.

[0061] (2) Coal ash slag, ceramsite powder, iron oxide, magnesium oxide, hydroxyapatite and modified calcium hydroxide are mixed evenly according to a predetermined ratio to obtain a mixture; the hydroxyapatite, iron oxide, magnesium oxide and calcium oxide are passed through a 100-mesh sieve;

[0062] (3) Then, add sodium bentonite to the mixture, mix evenly, and then spray 2-3% sodium carboxymethyl cellulose aqueous solution;

[0063] (4) Finally, the mixture is extruded to obtain a molded product, and the molded product is dried at 100-120℃.

[0064] Example 2:

[0065] A calcium hydroxide-based flue gas desulfurizer comprises the following components in parts by weight:

[0066] 100 parts of modified calcium hydroxide,

[0067] 50 portions of coal ash and slag.

[0068] 40 parts of crushed ceramsite,

[0069] 10 parts of iron oxide

[0070] 8 parts magnesium oxide

[0071] 8 parts of hydroxyapatite

[0072] 10 parts of sodium bentonite.

[0073] The ceramsite powder is made from large ceramsite particles with a diameter greater than 3 cm, which are then crushed to obtain fragments with a diameter greater than 0.5 cm. The particle size of the coal ash slag is in the range of 2-8 mm.

[0074] The preparation method of flue gas desulfurizing agent includes the following steps:

[0075] (1) Preparation of modified calcium hydroxide: Sodium hydroxide and sodium chloride are prepared into an aqueous solution, and a silane coupling agent is added to the aqueous solution. The mass concentration of sodium hydroxide and sodium chloride in the final aqueous solution is 2-5%, and the concentration of silane coupling agent is 3-8%. Then, the prepared aqueous solution is reacted with calcium oxide to generate calcium hydroxide paste. Then, it is dried at a temperature not higher than 120°C. Finally, the dried product is crushed and ground to obtain modified calcium hydroxide.

[0076] (2) Coal ash slag, ceramsite powder, iron oxide, magnesium oxide, hydroxyapatite and modified calcium hydroxide are mixed evenly according to a predetermined ratio to obtain a mixture; the hydroxyapatite, iron oxide, magnesium oxide and calcium oxide are passed through a 100-mesh sieve;

[0077] (3) Then, add sodium bentonite to the mixture, mix evenly, and then spray 2-3% sodium carboxymethyl cellulose aqueous solution;

[0078] (4) Finally, the mixture is extruded to obtain a molded product, and the molded product is dried at 100-120℃.

[0079] Example 3:

[0080] A calcium hydroxide-based flue gas desulfurizer comprises the following components in parts by weight:

[0081] 100 parts of modified calcium hydroxide,

[0082] 30 portions of coal ash and slag.

[0083] 20 parts of crushed ceramsite.

[0084] 5 parts iron oxide

[0085] Two parts magnesium oxide,

[0086] 5 parts hydroxyapatite

[0087] Five parts of sodium-based bentonite.

[0088] The ceramsite powder is made from large ceramsite particles with a diameter greater than 3 cm, which are then crushed to obtain fragments with a diameter greater than 0.5 cm. The particle size of the coal ash slag is in the range of 2-8 mm.

[0089] The preparation method of flue gas desulfurizing agent includes the following steps:

[0090] (1) Preparation of modified calcium hydroxide: Sodium hydroxide and sodium chloride are prepared into an aqueous solution, and a silane coupling agent is added to the aqueous solution. The mass concentration of sodium hydroxide and sodium chloride in the final aqueous solution is 2-5%, and the concentration of silane coupling agent is 3-8%. Then, the prepared aqueous solution is reacted with calcium oxide to generate calcium hydroxide paste. Then, it is dried at a temperature not higher than 120°C. Finally, the dried product is crushed and ground to obtain modified calcium hydroxide.

[0091] (2) Coal ash slag, ceramsite powder, iron oxide, magnesium oxide, hydroxyapatite and modified calcium hydroxide are mixed evenly according to a predetermined ratio to obtain a mixture; the hydroxyapatite, iron oxide, magnesium oxide and calcium oxide are passed through a 100-mesh sieve;

[0092] (3) Then, add sodium bentonite to the mixture, mix evenly, and then spray 2-3% sodium carboxymethyl cellulose aqueous solution;

[0093] (4) Finally, the mixture is extruded to obtain a molded product, and the molded product is dried at 100-120℃.

[0094] The products prepared above were subjected to corresponding performance tests.

[0095] The tests include: sulfur capacity test and crushing resistance test.

[0096] The test method for the average radial crushing force of particles shall be in accordance with the determination of the average crushing force in Q / 0305CJY020-2022. The sulfur capacity test method shall adopt the method of HG / T 2513; the bulk density test method shall be detailed in the enterprise standard Q / 0305CJY020-2022.

[0097] The test results are as follows:

[0098] Example 1 Example 2 Example 3 Crushing strength (N / cm) 89 95 103 Sulfur content 35 38 34 Bulk density (g / cm3) 0.65 0.68 0.66 Porosity % 130 136 142

[0099] In embodiments of this invention, coal ash slag and ceramsite powder are used as a large framework to support the granular powder. This results in an extruded product with good structural strength, and the porous structure of the coal ash slag and ceramsite powder improves gas permeability. Specifically, this invention modifies calcium hydroxide. The calcium hydroxide is modified using a silane coupling agent, sodium chloride, and sodium hydroxide. This allows the silane coupling agent to form groups on the surface of the calcium hydroxide crystal particles under alkaline conditions, facilitating the replenishment of sulfur dioxide gas. Simultaneously, sodium ions alter the original crystal structure of the calcium hydroxide, creating defects that form a pore distribution and pore size conducive to sulfur fixation, ultimately improving desulfurization efficiency. Furthermore, the porous structure of this solution, combined with the microstructure of the modified calcium hydroxide, prevents the pores from being blocked by the produced calcium sulfate after the reaction of calcium hydroxide and sulfur dioxide, thus minimizing the impact on subsequent desulfurization. Once the generated calcium sulfate blocks the formed desulfurizing agent, the flue gas throughput in the desulfurizing agent will inevitably decrease. Therefore, only by avoiding reducing the flue gas throughput can we ensure efficient desulfurization in both the early and late stages of treatment.

[0100] For ease of explanation, specific naming has been used in the above description to provide a thorough understanding of the described embodiments. However, it will be apparent to those skilled in the art that these specific details are not required to implement the above embodiments. Therefore, the above description of the specific embodiments described herein is presented for illustrative and descriptive purposes. Its purpose is not to exhaustively list or limit the embodiments to the specific, precise forms disclosed. It will be apparent to those skilled in the art that certain modifications, combinations, and variations can be made based on the above teachings.

Claims

1. A calcium hydroxide-based flue gas desulfurizer, characterized in that: Includes the following components by weight: 100 parts of modified calcium hydroxide, 30-50 parts of coal ash and slag. 20-40 parts of crushed ceramsite. 5-10 parts of iron oxide 2-8 parts magnesium oxide 5-8 parts of hydroxyapatite 5-10 parts of sodium bentonite; The preparation steps of the modified calcium hydroxide are as follows: sodium hydroxide and sodium chloride are prepared into an aqueous solution, and a silane coupling agent is added to the aqueous solution. In the final aqueous solution, the mass concentration of sodium hydroxide and sodium chloride is 2-5%, and the concentration of silane coupling agent is 3-8%. Then, the prepared aqueous solution is reacted with calcium oxide for 3-5 hours to produce calcium hydroxide paste. Then, it is dried at no higher than 120°C. Finally, the dried product is pulverized and ground to obtain modified calcium hydroxide. The ceramsite pulverized material is made from large ceramsite particles with a particle size greater than 3 cm, which are then pulverized to obtain fragments with a particle size greater than 0.5 cm. The particle size of the coal ash slag is in the range of 2-8mm.

2. The calcium hydroxide-based flue gas desulfurizer according to claim 1, characterized in that: The preparation method of the flue gas desulfurizing agent includes the following steps: (1) Preparation of modified calcium hydroxide: Sodium hydroxide and sodium chloride are prepared into an aqueous solution, and a silane coupling agent is added to the aqueous solution. The mass concentration of sodium hydroxide and sodium chloride in the final aqueous solution is 2-5%, and the concentration of silane coupling agent is 3-8%. Then, the prepared aqueous solution is reacted with calcium oxide to generate calcium hydroxide paste. Then, it is dried at a temperature not higher than 120°C. Finally, the dried product is crushed and ground to obtain modified calcium hydroxide. (2) The coal ash slag, ceramsite powder, iron oxide, magnesium oxide, hydroxyapatite and modified calcium hydroxide are mixed evenly according to the predetermined ratio to obtain a mixture. (3) Then, add sodium bentonite to the mixture, mix evenly, and then spray 2-3% sodium carboxymethyl cellulose aqueous solution; (4) Finally, the mixture is extruded to obtain a molded product, and the molded product is dried at 100-120℃.

3. The calcium hydroxide-based flue gas desulfurizer according to claim 1, characterized in that: The hydroxyapatite, iron oxide, magnesium oxide, and calcium oxide passed through a 100-mesh sieve.