A method for using a blocker to inhibit the formation of dioxin-like substances in waste incineration

Abstract

The invention discloses a method for using a blocker to inhibit the formation of dioxin-like substances in waste incineration, belonging to the field of flue gas purification for solid waste incineration. In the invention, an organic nitrogen-sulfur-based functional monomer is inserted into the interlayer of hydrotalcite to prepare a novel nitrogen-sulfur-doped hydrotalcite blocker, and the blocker is directly sprayed into the flue duct area of the incinerator, so as to achieve the purpose of effectively controlling the formation of dioxin-like substances in flue gas from the source. Compared with the existing inhibitors, the novel nitrogen-sulfur-doped hydrotalcite blocker prepared in the invention simultaneously has the inhibition functions of sulfur-based, nitrogen-based and hydroxyl group-based blockers. On the one hand, it can destroy the activity of the key catalyst for dioxin de novo synthesis, and on the other hand, it can adsorb the chlorine source (Cl2 / HCl) for the formation of dioxin-like substances, making the catalyst for the formation of dioxin-like pollutants lose its activity. The novel sulfur-nitrogen-doped hydrotalcite blocker developed in the invention is simple to prepare and low in cost, and has important application value for solving the problem of dioxin-like substance emissions in solid waste incineration flue gas.

Description

Technical Field

[0001] The invention relates to the field of flue gas purification for solid waste incineration, and particularly to a preparation method of a novel blocker for inhibiting the formation of dioxin-like substances in solid waste incineration flue gas. Background Art

[0002] Incineration, as an important way for domestic waste treatment in China, has significant advantages such as volume reduction, weight reduction, and energy recovery. However, the secondary pollution problems and the resulting "Not In My Backyard (NIMBY) effect" have attracted much attention to the emission control of dioxin-like substances. To meet the emission requirements, while improving the flue gas treatment equipment and facilities, domestic waste incineration plants in China adopt more advanced flue gas treatment processes, which have reduced the emissions of dioxin-like substances in domestic waste incineration tail gas to a certain extent. However, end-of-pipe control has not fundamentally solved the problem of dioxin-like substance emissions. Therefore, process retardation - that is, retarding the formation of dioxin-like substances - has become a research hotspot for solving the problem of dioxin-like substance emissions, replacing end-of-pipe control.

[0003] Research shows that the main formation pathway of dioxin-like substances during solid waste incineration is de novo synthesis in the post-furnace flue gas cooling section. Therefore, the main measure for incineration plants to control dioxin-like substances is to use rapid cooling treatment to reduce the flue gas temperature below 200 °C within 1.0 s, thereby reducing the residence time of the flue gas in the temperature range of 200 °C to 500 °C. However, in actual production, it is difficult for rapid cooling treatment to achieve the required cooling rate. In recent years, adding blockers during the flue gas cooling process to destroy the activity of the key catalysts for dioxin de novo synthesis has become an effective way to retard the formation of dioxins. The most widely studied inhibitors include nitrogen-containing blockers, sulfur-containing blockers, and hydroxyl group-containing blockers. Chinese invention patent CN103423749A uses a novel S-N blocker (combining the functions of sulfur and nitrogen blockers) to achieve a high dioxin-like inhibition efficiency; Chinese patent CN105080325 discloses a method for inhibiting the formation of dioxin-like substances in solid waste incineration flue gas, and adding ammonium dihydrogen phosphate can effectively inhibit the formation of dioxin-like substances. However, the existing blockers have the problem of weak contact ability with flue gas particles, resulting in poor inhibition effects. It can be seen that developing efficient novel blockers has become an urgent problem to be solved in the research field of retarding the formation of dioxin-like substances. Summary of the Invention

[0004] The technical problem to be solved by the invention is to overcome the above technical defects and provide a novel, low-cost, and efficient method for controlling the formation of dioxin-like substances in waste incineration flue gas.

[0005] To solve the above problems, the technical solution of the invention is: a method for using a blocker to inhibit the formation of dioxin-like substances in waste incineration, the method comprising the following steps:

[0006] 1. Uniformly mix a divalent metal salt, an aluminum salt, and an organic nitrogen-sulfur functional monomer in an aqueous solution. Under the conditions of heating and stirring, a sodium hydroxide solution is gradually added dropwise to the mixture;

[0007] 2. Age the above mixture, then filter, wash, and dry it to obtain a retarder.

[0008] Further, in step (1), the divalent metal salt includes calcium chloride, magnesium chloride, calcium nitrate, and magnesium nitrate.

[0009] Further, in step (1), the organic nitrogen-sulfur functional monomer includes sulfonamide, sulfamic acid, and dimethyldithiocarbamic acid.

[0010] Further, in step (1), the molar ratio of the divalent metal ion, aluminum ion, and organic nitrogen-sulfur functional monomer is (1 - 3):1:(1 - 4).

[0011] Further, in step (1), the sodium hydroxide solution (1 mol / L) is gradually added dropwise to the solution to make the pH of the solution 8.0 - 11.0.

[0012] Further, in step (1), the mixture is stirred at 50 - 80 °C and aged for 24 h.

[0013] Further, in step (2), the mixture is filtered, washed with deionized water, and centrifuged until the washing liquid is neutral, and then dried at 60 °C for 12 h to obtain a sulfur-nitrogen doped hydrotalcite retarder.

[0014] The advantages of the invention compared with the existing technology are as follows:

[0015] 1. The retarder developed in the present invention combines the inhibitory functions of sulfur-based retarders, nitrogen-based retarders, and hydroxyl group-based retarders, and can more efficiently inhibit the formation of dioxin-like substances;

[0016] 2. While the present invention can efficiently inhibit dioxin-like substances during the waste incineration process, it will not have a negative impact on the incineration system and the emissions of other conventional pollutants in the flue gas at the tail;

[0017] 3. The sulfur-nitrogen doped hydrotalcite retarder developed in the present invention is simple to prepare, low in cost, significantly reduces the operating cost of waste incineration plants, and has important application value for solving the problem of dioxin-like substance emissions during the incineration of solid waste. Brief Description of the Drawings

[0018] Figure 1 It is the SEM image of the sulfur-nitrogen doped hydrotalcite retarder prepared in Example 1. Detailed Description of the Invention

[0019] The following will clearly and completely describe the technical solutions in the embodiments of the invention with reference to the accompanying drawings in the embodiments of the invention. Obviously, the described embodiments are only a part of the embodiments of the invention, rather than all the embodiments; based on the embodiments of the invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the invention.

[0020] As Figure 1 shown, a method for using a retarder to inhibit the formation of dioxin-like substances in waste incineration is to uniformly mix a divalent metal salt, an aluminum salt, and an organic nitrogen-sulfur functional monomer in an aqueous solution. Under the conditions of heating and stirring, a sodium hydroxide solution is gradually added dropwise to the mixed solution. After aging, it is filtered, washed, and dried to obtain the retarder.

[0021] The divalent metal salt includes calcium chloride, magnesium chloride, calcium nitrate, and magnesium nitrate.

[0022] The organic nitrogen-sulfur functional monomer includes thioamide, sulfamic acid, and dimethyldithiocarbamic acid.

[0023] The molar ratio of the divalent metal ion, aluminum ion, and organic nitrogen-sulfur functional monomer is (1-3):1:(1-4).

[0024] The sodium hydroxide solution is gradually added dropwise to the solution until the pH = 8.0-11.0.

[0025] The mixture is stirred at 50-80 °C and aged for 24 h. Then, the mixture is filtered, washed with deionized water, and centrifuged until the washing liquid is neutral. Then, it is dried at 60 °C for 12 h to obtain the sulfur-nitrogen doped hydrotalcite retarder.

[0026] The retarder is directly sprayed into the flue gas region of the incinerator to control the de novo synthesis of dioxin-like substances in the waste incineration flue gas.

[0027] An application of a retarder for inhibiting the formation of dioxin-like substances in waste incineration is to first put the waste into the incinerator for combustion, and then directly spray the inhibitor into the flue gas region of the incinerator to inhibit the de novo synthesis of dioxin-like substances in the combustion flue gas.

[0028] The mass ratio of the retarder to the chlorine element in the flue is between 50 and 300.

[0029] The flue gas region is the flue gas region with a temperature range of 200-500 °C.

[0030] The specific embodiments are as follows.

[0031] Example 1:

[0032] 1. Preparation of sulfur-nitrogen doped hydrotalcite retarder

[0033] Calcium chloride, aluminum nitrate and thioamide are uniformly mixed in an aqueous solution, and the molar ratio is 2:1:4. Under stirring conditions, sodium hydroxide solution (1 mol / L) is gradually added dropwise to the solution to make the solution pH = 9.0. Then the mixture is stirred and aged at 60 °C for 24 h, filtered, washed with deionized water, and centrifuged until the washing solution is neutral. Finally, it is dried at 60 °C for 12 h to obtain a sulfur and nitrogen doped hydrotalcite retarder. The SEM image of the sulfur and nitrogen doped hydrotalcite retarder is as Figure 1 shown.

[0034] 2. Method for inhibiting the formation of dioxin-like substances in waste incineration flue gas

[0035] First, the waste is put into an incinerator for combustion, and then the sulfur and nitrogen doped hydrotalcite retarder is directly sprayed into the flue gas area of the incinerator with a temperature range of 400 - 500 °C. When inhibiting the formation of dioxin-like substances in the burning waste, the mass ratio of the addition amount of the retarder to the chlorine element in the flue gas is 250. Through experimental determination, the inhibition rate of the dioxin-like substances de novo synthesis intermediates (chlorobenzene, chlorophenol) in the flue gas after combustion reaches more than 90%.

[0036] Example 2:

[0037] Calcium chloride, magnesium chloride, aluminum nitrate and thioamide are uniformly mixed in an aqueous solution, and the molar ratio is 1:1:1:4. Under stirring conditions, sodium hydroxide solution (1 mol / L) is gradually added dropwise to the solution to make the solution pH = 10.0. Then the mixture is stirred and aged at 60 °C for 24 h, filtered, washed with deionized water, and centrifuged until the washing solution is neutral. Finally, it is dried at 60 °C for 12 h to obtain a sulfur and nitrogen doped hydrotalcite retarder.

[0038] 2. Method for inhibiting the formation of dioxin-like substances in waste incineration flue gas

[0039] First, the waste is put into an incinerator for combustion, and then the sulfur and nitrogen doped hydrotalcite retarder is directly sprayed into the flue gas area of the incinerator with a temperature range of 300 - 400 °C. When inhibiting the formation of dioxin-like substances in the burning waste, the mass ratio of the addition amount of the retarder to the chlorine element in the flue gas is 200. Through experimental determination, the inhibition rate of the dioxin-like substances de novo synthesis intermediates (chlorobenzene, chlorophenol) in the flue gas after combustion reaches more than 80%.

[0040] Example 3:

[0041] Calcium chloride, aluminum nitrate and thioamide are uniformly mixed in an aqueous solution with a molar ratio of 1:1:4. Under stirring conditions, a sodium hydroxide solution (1 mol / L) is added dropwise to the solution to adjust the pH of the solution to 8.0. Then, the mixture is stirred and aged at 60 °C for 24 h, followed by filtration, washing with deionized water, and centrifugation until the washing liquid is neutral. Finally, it is dried at 60 °C for 12 h to obtain a sulfur and nitrogen-doped hydrotalcite retarder.

[0042] 2. Method for inhibiting the formation of dioxin-like substances in waste incineration flue gas

[0043] First, the waste is put into an incinerator for combustion, and then the sulfur and nitrogen-doped hydrotalcite retarder is directly sprayed into the flue gas duct area of the incinerator with a temperature range of 400 - 500 °C. When inhibiting the formation of dioxin-like substances in the burning waste, the mass ratio of the retarder addition amount to the chlorine element in the flue gas is 300. Through experimental determination, the inhibition rate of the dioxin-like substances (chlorobenzene, chlorophenol) as the de novo synthesis intermediates in the flue gas after combustion reaches more than 85%.

[0044] Example 4:

[0045] Calcium nitrate, aluminum nitrate and thioamide are uniformly mixed in an aqueous solution with a molar ratio of 1:1:3. Under stirring conditions, a sodium hydroxide solution (1 mol / L) is added dropwise to the solution to adjust the pH of the solution to 9.0. Then, the mixture is stirred and aged at 60 °C for 24 h, followed by filtration, washing with deionized water, and centrifugation until the washing liquid is neutral. Finally, it is dried at 60 °C for 12 h to obtain a sulfur and nitrogen-doped hydrotalcite retarder.

[0046] 2. Method for inhibiting the formation of dioxin-like substances in waste incineration flue gas

[0047] First, the waste is put into an incinerator for combustion, and then the sulfur and nitrogen-doped hydrotalcite retarder is directly sprayed into the flue gas duct area of the incinerator with a temperature range of 400 - 500 °C. When inhibiting the formation of dioxin-like substances in the burning waste, the mass ratio of the retarder addition amount to the chlorine element in the flue gas is 250. Through experimental determination, the inhibition rate of the dioxin-like substances (chlorobenzene, chlorophenol) as the de novo synthesis intermediates in the flue gas after combustion reaches more than 80%.

[0048] Example 5:

[0049] Calcium chloride, aluminum nitrate and thioamide are uniformly mixed in an aqueous solution with a molar ratio of 21:1:3. Under stirring conditions, a sodium hydroxide solution (1 mol / L) is added dropwise to the solution to adjust the pH of the solution to 11.0. Then, the mixture is stirred and aged at 60 °C for 24 h, followed by filtration, washing with deionized water, and centrifugation until the washing liquid is neutral. Finally, it is dried at 60 °C for 12 h to obtain a sulfur and nitrogen-doped hydrotalcite retarder.

[0050] 2. Method for inhibiting formation of dioxin-like substances in waste incineration flue gas

[0051] First, put the waste into the incinerator for combustion, and then directly inject the sulfur and nitrogen doped hydrotalcite retarder into the flue gas region of the incinerator where the temperature ranges from 300 to 500 °C. When inhibiting the formation of dioxin-like substances in the burning waste, the mass ratio of the addition amount of the retarder to the chlorine element in the flue gas is 300. Through experimental determination, the inhibition rate of the dioxin-like substances de novo synthesis intermediates (chlorobenzene, chlorophenol) in the flue gas after combustion reaches more than 80%.

[0052] The invention and its implementation manners have been described above. Such description is not restrictive. What is shown in the drawings is only one of the implementation manners of the invention, and the actual structure is not limited thereto. All in all, if those of ordinary skill in the art are inspired by it and design, without creative work, structural manners and embodiments similar to the technical solution without departing from the purpose of the invention-creation, they shall fall within the protection scope of the invention.

Claims

1. A method for using a blocker to inhibit the formation of dioxin-like substances in waste incineration, characterized in that: A divalent metal salt, an aluminum salt and an organic nitrogen-sulfur functional monomer are uniformly mixed in an aqueous solution. Under the conditions of heating and stirring, a sodium hydroxide solution is added dropwise to the mixed solution. After aging, it is filtered, washed and dried to obtain a retarder; The divalent metal salt includes calcium chloride, magnesium chloride, calcium nitrate and magnesium nitrate; The organic nitrogen-sulfur functional monomer includes thioamide, sulfamic acid and dimethyldithiocarbamic acid; The molar ratio of the divalent metal ion, aluminum ion and organic nitrogen-sulfur functional monomer is (1~3):1:(1~4).

2. The method for using a blocker to inhibit the formation of dioxin-like substances in waste incineration according to claim 1, wherein: The sodium hydroxide solution is added dropwise to the solution to make the solution pH = 8.0~11.

0.

3. The method for using a blocker to inhibit the formation of dioxin-like substances in waste incineration according to claim 1, characterized in that: The mixture is stirred at 50~80 °C and aged for 24 h. Then the mixture is filtered, washed with deionized water and centrifuged until the washing liquid is neutral, and then dried at 60 °C for 12 h to obtain a sulfur-nitrogen doped hydrotalcite retarder.

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