System and method for resource recycling of sulfur dioxide

Patent metadata

Field	Value
Publication number	US-11731874-B2
Application number	US-202017784264-A
Country	US
Kind code	B2
Filing date	May 10, 2020
Priority date	Dec 13, 2019
Publication date	Aug 22, 2023
Grant date	Aug 22, 2023

Abstract

A system for resource recycling of sulfur dioxide includes a charcoal reduction furnace, a high temperature dust remover, a cooling separator A, a liquid sulfur tank, a cooling separator, a tail gas absorption tower, a gas stripping tower, a hypo reactor, a centrifuge, a mother liquor tank and a thickener. And a method for resource recycling of sulfur dioxide includes the following steps: (1) preparing elemental sulfur, (2) removing dust from a process gas containing gaseous sulfur, (3) separating elemental sulfur, (4) reabsorbing residual SO2 gas, (5) purifying sulfur powder, (6) preparing a slurry of cured hypo, (7) performing liquid-solid separation, and (8) preparing an absorption slurry. According to the method, SO2 gas is reduced into liquid sulfur and sulfur powder, and sodium thiosulfate is coproduced.

First claim

What is claimed is:

1. A system for resource recycling of sulfur dioxide, wherein the system comprises a charcoal reduction furnace with a gas output end connected with a dust remover, a gas-phase output end of the dust remover is connected with a cooling separator A, and another gas-phase output end is connected with a cooling separator B;
a liquid-phase output end of the cooling separator A is connected with a liquid sulfur tank, a gas-phase output end of the cooling separator A is connected with a thickener through a tail gas absorption tower, an output end of the thickener is respectively connected with a hypo reactor, a centrifuge and a mother liquor tank, the hypo reactor, is connected with the mother liquor tank through the centrifuge, and an output end of the mother liquor tank is respectively connected with the thickener and the tail gas absorption tower; and
a gas-phase output end of the cooling separator B is connected with the tail gas absorption tower, a solid-phase output end of the cooling separator B is connected with a gas stripping tower, the gas stripping tower is connected with the centrifuge through the hypo reactor, a solid-phase output end of the centrifuge is a product, and a liquid-phase output end of the centrifuge is connected with the mother liquor tank.

2. The system for resource recycling of sulfur dioxide according to claim 1 , wherein a solid-phase output end of the dust remover and a gas output end of the gas stripping tower are both connected with the charcoal reduction furnace.

3. The system for resource recycling of sulfur dioxide according to claim 1 , wherein the gas stripping tower is also provided with an input pipeline for stripping gas and an output pipeline for sulfur powder.

4. The system for resource recycling of sulfur dioxide according to claim 1 , wherein the hypo reactor is provided with an input pipeline for sodium-alkali, and the mother liquor tank is provided with input pipelines for sodium-alkali and process water.

5. A method for realizing resource recycling of sulfur dioxide by using the system according to claim 1 , wherein the method comprises the following steps:
(1) preparation of elemental sulfur: in the charcoal reduction furnace, using a charcoal reducing agent to perform a redox reaction with original flue gas containing SO 2 to generate a process gas containing gaseous sulfur, and controlling the volume content of oxygen in the process gas to be 1.5% or less;
(2) removal of dust from process gas containing gaseous sulfur: removing the dust from the process gas containing gaseous sulfur in step (1) and sulfur vapor in the dust remover by using filter elements;
(3) separation of elemental sulfur: transporting the process gas containing gaseous sulfur after dust removal in step (2) into a condensation separator A and/or a condensation separator B for separation, so as to separate liquid sulfur through the condensation separator A and separate sulfur powder through the condensation separator B;
(4) reabsorption of residual SO 2 gas: absorbing and purifying the non-condensable gas leaving the condensation separator A and/or leaving the condensation separator B in step (3) by the tail gas absorption tower, wherein controlling a pH value of an absorption liquid in the absorption tower to be 6.5 or above;
(5) purification of sulfur powder: transporting the sulfur powder obtained in step (3) into the gas stripping tower which uses nitrogen and/or the purified tail gas at the outlet of the tail gas absorption tower as a gas stripping medium, and after gas stripping, transporting part of the sulfur powder into the hypo reactor, and outputting the other part of the sulfur powder as a product;
(6) preparation of slurry of cured hypo: transporting the absorption liquid absorbed by the absorption tower into the thickener, placing the thickened slurry in the hypo reactor, adjusting the pH value to 10 with sodium-alkali, controlling a molar ratio of Na 2 SO 3 to H 2 O in the hypo reactor at 1:(6.3-7.5), at the same time, adding the sulfur powder according to a molar ratio of 1:(1.1-1.2) of S:Na 2 SO 3 , and then, sealing the hypo reactor for heating and curing to obtain a suspension;
or directly producing a sodium sulfite slurry without adding the sulfur powder to the hypo reactor, which is specifically as follows:

preparation of sodium sulfite slurry: transporting the absorption liquid absorbed by the absorption tower into the thickener, placing the slurry in the hypo reactor, and adjusting the pH value to 10 with sodium-alkali to obtain the sodium sulfite slurry;
(7) liquid-solid separation: transporting the suspension obtained by heating and curing in step (6) into the centrifuge for separation to obtain a sodium thiosulfate wet product and a sodium thiosulfate mother liquor, or transporting the sodium sulfite slurry into the centrifuge for separation to obtain a sodium sulfite wet product and a sodium sulfite mother liquor; and
(8) preparation of absorption slurry: preparing an absorption liquid with a pH value of 10-12 and a relative density of 1.28-1.40 from the mother liquor, the process water and the sodium-alkali, and transporting the absorption liquid into the tail gas absorption tower and the thickener.

6. The method according to claim 5 , wherein the charcoal reduction furnace in step (1) can be divided into an ash cooling section, an SO 2 reducing section and a reducing agent preheating section from top to bottom according to the temperature during operation.

7. The method according to claim 6 , wherein the temperature of a lower part of the ash cooling section is controlled at 250-380° C., the temperature of the SO 2 reducing section is controlled at 860-1100° C., and the temperature of an upper part of the reducing agent preheating section is controlled at 380-650° C.

8. The method according to claim 5 , wherein a mass metering ratio of the charcoal reducing agent to SO 2 in sulfur-containing flue gas in step (1) is M 1 :M 2 =1:(2-8), wherein M 1 represents a mass flow rate of fixed carbon in the charcoal reducing agent, and M 2 represents a mass flow rate of SO 2 in the sulfur-containing flue gas.

9. The method according to claim 8 , wherein a molar ratio of zero valent sulfur to positive tetravalent sulfur in the process gas containing gaseous sulfur leaving the charcoal reduction furnace is S(0):S(IV)=(1.3-95):1; and further preferably, when the sulfur powder is produced, the ratio of S(0):S(IV) is not less than 1.05, and when sodium thiosulfate is produced, the ratio of S(0):S(IV) is controlled at 1.05-1.08.

10. The method according to claim 5 , wherein the temperature of the process gas containing gaseous sulfur entering the dust remover in step (2) is 380-650° C., and a temperature drop before and after the gas enters and leaves the dust remover is not greater than 30° C.

11. The method according to claim 5 , wherein the condensation separator A in step (3) uses the process hot water at 103-108° C. or the process gas at 70-105° C. as a cooling medium, and the process gas containing gaseous sulfur can be cooled to 105-113° C., and
the condensation separator B uses the process water at 15-100° C. or the process gas at 80° C. or below as a cooling medium, and the process gas containing gaseous sulfur can be cooled to 105° C. or below.

12. The method according to claim 5 , wherein stirring is performed in the heating and curing process in step (5), a stirring rate is adjusted to 26-35 r/min, a reaction temperature is controlled at 100-105° C., and a reaction time is controlled at 30-45 min.

Assignees

• Nanjing Gekof Institute Of Environmental Protection Tech & Equipment Co Ltd
• Nanjing University Of Technology
• Jiangsu Deyitong Environmental Protection Tech Co Ltd
• Nanjing Liuyan Environmental Protection Tech Co Ltd
• Nanjing Liyuan Environmental Protection Tech Co Ltd

Inventors

• Xu Haitao
• Xu Yanzhong
• Li Mingbo
• Chen Renyuan
• Liu Dahua
• Wu Zhenshan
• Song Jing
• Xu Meng

Classifications

• C01B17/0482 Primary

  with carbon or solid carbonaceous materials · CPC title

• B01D5/0072

  with filtration · CPC title

• B01D5/0093

  Removing and treatment of non condensable gases · CPC title

• B01D46/0036

  by adsorption or absorption · CPC title

• B01D53/502

  characterised by a specific solution or suspension · CPC title