Method for fixing CO2 through cooperation of waste incineration fly ash and landfill leachate

Abstract

The invention relates to the technical field of household garbage treatment and carbon sequestration, in particular to a method for fixing CO2 through cooperation of garbage incineration fly ash and garbage leachate. According to the method, the carbon dioxide is fixed through cooperation of the waste incineration fly ash and the landfill leachate, ammonium chloride is added in the process, the carbon dioxide fixing effect is better, meanwhile, generated tail gas is partially circulated in the carbon dioxide fixing process, on one hand, the concentration of ammonium chloride in the mixed liquid can be effectively guaranteed, and on the other hand, the carbon dioxide fixing effect is improved; and on the other hand, the ammonia content in the discharged tail gas can be reduced, the dosage of a treatment agent can be reduced, and the tail gas is convenient to purify. According to the method, on one hand, fixation of carbon dioxide is achieved through cooperation of the waste incineration fly ash and the landfill leachate, on the other hand, the carbon fixation effect is further improved through addition of ammonium chloride and ammonia backflow, waste is treated with waste, and the method has important significance on waste treatment and environment protection.

Description

Technical Field

[0001] The present invention relates to the technical field of domestic waste treatment and carbon sequestration, and in particular to a method for fixing CO2 by using fly ash from waste incineration in conjunction with waste leachate. Background Art

[0002] The management of hazardous waste is an integral part of global environmental issues and a prominent issue in my country's environmental protection. Municipal waste incineration is an important means of disposing of urban domestic waste. The incineration process produces a large amount of fly ash. Waste incineration fly ash contains many harmful heavy metals such as lead, cadmium, and zinc. More importantly, incineration fly ash is also enriched with toxic components such as dioxins and furans that are carcinogenic to humans. Existing environmental regulations at home and abroad have classified it as hazardous waste, and it must be emphasized that it should be handled safely.

[0003] Carbon dioxide storage refers to capturing and compressing carbon dioxide produced by large emission sources and transporting it to a selected location for long-term storage, rather than releasing it into the atmosphere. Carbon dioxide storage technology actually means storing carbon dioxide in a specific natural or artificial "container" and using physical, chemical, biochemical and other methods to store carbon dioxide for a hundred years or even longer, rather than releasing it into the atmosphere. Forests, oceans, strata, chemical reactors, etc. can all be used as "containers" for storing carbon dioxide. Storing carbon dioxide can reduce the greenhouse effect, slow global warming, protect ecosystems, and provide solutions to climate change.

[0004] The impact of waste incineration fly ash and carbon dioxide on people's lives and the environment cannot be ignored. Therefore, after people's exploration, waste incineration fly ash can be used to seal carbon dioxide, thereby realizing the dual waste treatment of fly ash and carbon dioxide; but in actual application, the storage capacity of carbon dioxide by waste incineration fly ash is limited, and the application effect is difficult to meet people's expectations. Therefore, a method of using waste incineration fly ash to achieve efficient fixation of carbon dioxide is a problem that existing laboratories need to solve. Summary of the invention

[0005] The purpose of the present invention is to provide a method for fixing CO2 by using fly ash from garbage incineration in conjunction with garbage leachate, so as to solve the problem of poor carbon fixation effect of the existing method.

[0006] To achieve the above object, the present invention adopts the following technical solution: a method for fixing CO2 by using fly ash from garbage incineration and leachate, comprising the following steps:

[0007] S1, concentrating the landfill leachate to obtain an alkaline first concentrated solution;

[0008] S2, adding ammonium chloride to the first concentrated solution of S1 to obtain a second concentrated solution, and mixing the waste incineration fly ash and the second concentrated solution to obtain a mixed solution;

[0009] S3. The captured carbon dioxide gas is introduced into the S2 mixed liquid to achieve the fixation of CO2.

[0010] Furthermore, in the above-mentioned S1, the landfill leachate is subjected to nanofiltration treatment, and then the landfill leachate after the nanofiltration treatment is concentrated by reverse osmosis.

[0011] Furthermore, the volume ratio of the first concentrated liquid to the original landfill leachate after nanofiltration treatment is 1:5-10.

[0012] Furthermore, in S2, after adding ammonium chloride, the content of ammonium chloride in the second concentrated solution is 50-100 g / L.

[0013] Furthermore, the solid-liquid mass ratio of the waste incineration fly ash to the second concentrated liquid is 1:3-8.

[0014] Furthermore, in S3, the fixation of CO2 comprises the following steps:

[0015] S31, under stirring, introducing captured carbon dioxide gas into the mixed liquid, and obtaining tail gas after the carbon dioxide gas is absorbed by the mixed liquid;

[0016] S32, passing a part of the tail gas obtained in S31 into the mixed liquid for circulation, and the exhaust tail gas is purified and then discharged.

[0017] Furthermore, in the S31, the stirring intensity is 60 to 120 r / min.

[0018] Furthermore, the flow rate of the air is 1 to 5 mL / (g·min) relative to the mass of the mixed liquid.

[0019] Furthermore, in the S32, the ratio of the flow rate of the circulating exhaust gas to the flow rate of the introduced carbon dioxide gas is 1 to 5:1, the flow rate of the discharged exhaust gas is substantially consistent with the flow rate of the introduced carbon dioxide gas, and the time for introducing the carbon dioxide gas is 1 to 3 hours.

[0020] Furthermore, in the above-mentioned S32, the exhaust gas can be discharged after being absorbed and purified by water.

[0021] Beneficial effects of the present invention:

[0022] 1. The method of the present invention uses fly ash from garbage incineration to fix carbon dioxide in cooperation with garbage leachate. Since the garbage leachate contains calcium and magnesium ions, it achieves waste treatment with waste and also improves the carbon fixation effect;

[0023] 2. The leachate is alkaline. Under alkaline conditions, the addition of ammonium chloride can improve the precipitation effect of calcium and magnesium ions in the mixed solution, thereby increasing the amount of carbon fixation. At the same time, the leachate is low in cost, which reduces costs;

[0024] 3. The method of the present invention can effectively intercept ammonia in the tail gas by partially circulating the tail gas after carbon fixation, thereby ensuring the concentration of ammonium chloride in the mixed liquid, which on the one hand helps the precipitation of calcium and magnesium ions and improves the carbon fixation effect, and on the other hand also reduces the ammonia content in the tail gas, facilitates the purification of the tail gas and can reduce the use of tail gas treatment agents. DETAILED DESCRIPTION

[0025] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention.

[0026] Example 1

[0027] In this embodiment, the domestic waste leachate, the domestic waste incineration fly ash and the captured carbon dioxide gas all come from a waste incineration plant, wherein the captured carbon dioxide gas is the incineration flue gas, and the carbon dioxide content in the flue gas is 13%.

[0028] The components of the waste incineration fly ash were tested, and the results are as follows:

[0029] Table 1 Metal content of fly ash from domestic waste incineration in a waste incineration plant

[0030]

[0031] As can be seen from Table 1, the metal ions in the waste incineration fly ash mainly exist in the form of calcium ions, and specifically the calcium ions exist in the waste incineration fly ash in the form of calcium oxide.

[0032] The domestic waste leachate treated by nanofiltration was concentrated by reverse osmosis to obtain a first concentrated solution. The volume ratio of the domestic waste leachate before and after concentration was 8:1. The domestic waste leachate concentrate was taken and the calcium and magnesium ion contents therein were tested. The results are as follows:

[0033] Table 2 Calcium and magnesium ion content of concentrated liquid leachate from domestic waste incineration plant

[0034]

[0035] During the testing process, it was found that the pH of the concentrated leachate of domestic waste was alkaline, and the content of calcium ions was significantly greater than that of magnesium ions.

[0036] Take 5L of the above-mentioned concentrated domestic waste leachate, add 400g of ammonium chloride thereto, and obtain a second concentrated solution with an ammonium chloride content of 80g / L. The second concentrated solution is sealed and stored for later use.

[0037] Take 500g of the above-mentioned second concentrated liquid into a multi-mouth flask, slowly add 100g of waste incineration fly ash thereto, stir and mix at a stirring intensity of 80r / min, and then introduce flue gas into the flask through an air intake pump. The flue gas introduction rate is 2L / min. The air intake is connected to the aeration head through a hose, and the aeration head extends below the liquid level in the multi-mouth flask.

[0038] Connect any two ports of the multi-port flask through a hose, and install a circulating air pump on the hose. Control the flow rate of the circulating air pump to 6L / min. The outlet gas of the circulating air pump also extends to below the liquid level through the aeration head.

[0039] The reaction was carried out at room temperature for 2 hours. After the reaction was completed, the reaction liquid was collected and weighed. A total of 629.4 g of reaction liquid was obtained, and about 29.4 g of carbon dioxide was fixed, which was about 95.3% of the theoretical fixed amount.

[0040] The collected reaction solution was filtered to obtain a filtrate and a filter residue. The calcium and magnesium ion contents in the filtrate were tested. The results are shown in the following table:

[0041] Table 3 Content of calcium and magnesium ions in the filtrate after reaction

[0042]

[0043] It can be seen that the method of the present invention promotes the storage effect of waste incineration fly ash on carbon dioxide, and also precipitates calcium and magnesium ions in the concentrated solution of landfill leachate, thereby further achieving the fixation of carbon dioxide.

[0044] Example 2

[0045] Take the fly ash, flue gas and the second concentrated liquid from the incineration of domestic waste in Example 1.

[0046] The stirring speed is 100 r / min, and the rest is the same as in Example 1.

[0047] After the reaction was completed, the reaction liquid was collected and weighed, and a total of 629.9 g of reaction liquid was obtained, and about 29.9 g of carbon dioxide was fixed, which was about 96.9% of the theoretical fixed amount.

[0048] Example 3

[0049] Take the fly ash, flue gas and the second concentrated liquid from the incineration of domestic waste in Example 1.

[0050] The reaction time at room temperature was 3 h, and the other conditions were the same as in Example 1.

[0051] After the reaction was completed, the reaction liquid was collected and weighed, and a total of 629.5 g of reaction liquid was obtained, and about 29.5 g of carbon dioxide was fixed, which was about 95.6% of the theoretical fixed amount.

[0052] Comparative Example 1

[0053] Take the fly ash and flue gas from the incineration of domestic waste in Example 1.

[0054] 500 g of water was added to a multi-necked flask, and then 100 g of fly ash from the incineration of domestic waste was added thereto. Flue gas was passed directly under stirring, with a ventilation volume of 8 L / min. The stirring intensity and reaction time were the same as those in Example 1.

[0055] After the reaction was completed, the reaction liquid was collected and weighed, and a total of 618.3 g of reaction liquid was obtained, and about 18.3 g of carbon dioxide was fixed, which was about 59.7% of the theoretical fixed amount.

[0056] Comparative Example 2

[0057] Take the fly ash and flue gas from the incineration of domestic waste in Example 1.

[0058] Add 500g of water to a multi-necked flask, add 40g of ammonium chloride thereto, stir to dissolve, then slowly add 100g of fly ash from the incineration of domestic waste thereto, and introduce flue gas under stirring at a ventilation rate of 8L / min. The stirring intensity and reaction time are the same as those in Example 1.

[0059] After the reaction was completed, the reaction liquid was collected and weighed, and a total of 626.2 g of reaction liquid was obtained, and about 26.2 g of carbon dioxide was fixed, which was about 85.5% of the theoretical fixed amount.

[0060] Comparative Example 3

[0061] The introduced flue gas was refluxed, wherein the ventilation volume of the flue gas was 2 L / min, the reflux gas volume was 6 L / min, and the other conditions were the same as those in Comparative Example 2.

[0062] After the reaction was completed, the reaction liquid was collected and weighed, and a total of 627.8 g of reaction liquid was obtained, and about 27.8 g of carbon dioxide was fixed, which was about 90.7% of the theoretical fixed amount.

[0063] Comparative Example 4

[0064] Take the fly ash, flue gas and second concentrated liquid from the incineration of domestic waste in Example 1.

[0065] The ventilation rate of flue gas was 8 L / min, and no tail gas reflux was performed. Other aspects were the same as those in Example 1.

[0066] After the reaction was completed, the reaction liquid was collected and weighed, and a total of 625.7 g of reaction liquid was obtained, and about 25.7 g of carbon dioxide was fixed, which was about 83.3% of the theoretical fixed amount.

[0067] The present invention is not limited to the above-mentioned optimal implementation mode. Anyone can derive other various forms of products under the inspiration of the present invention. However, no matter what changes are made in the shape or structure, all technical solutions that are the same or similar to those of the present application fall within the protection scope of the present invention.

Claims

1. A method for fixing CO2 by using fly ash from garbage incineration and leachate, characterized in that: The following steps are involved: S1, concentrating the landfill leachate to obtain an alkaline first concentrated solution; S2, adding ammonium chloride to the first concentrated solution of S1 to obtain a second concentrated solution, and mixing the waste incineration fly ash and the second concentrated solution to obtain a mixed solution; S3. The captured carbon dioxide gas is introduced into the S2 mixed liquid to achieve the fixation of CO2.

2. The method for fixing CO2 by using fly ash from garbage incineration and leachate according to claim 1, characterized in that: In the above-mentioned S1, the landfill leachate is subjected to nanofiltration treatment, and then the landfill leachate after the nanofiltration treatment is concentrated by reverse osmosis.

3. The method for fixing CO2 by using fly ash from garbage incineration and leachate according to claim 2, characterized in that: The volume ratio of the first concentrated liquid to the landfill leachate after nanofiltration treatment is 1:5-10.

4. The method for fixing CO2 by using fly ash from garbage incineration and leachate according to claim 1, characterized in that: In the S2, after adding ammonium chloride, the content of ammonium chloride in the second concentrated solution is 50-100 g / L.

5. The method for fixing CO2 by using fly ash from garbage incineration and leachate according to claim 4, characterized in that: The solid-liquid mass ratio of the waste incineration fly ash to the second concentrated liquid is 1:3-8.

6. The method for fixing CO2 by using fly ash from garbage incineration and leachate according to claim 1, characterized in that: In the S3, the fixation of CO2 comprises the following steps: S31, under stirring, introducing captured carbon dioxide gas into the mixed liquid, and obtaining tail gas after the carbon dioxide gas is absorbed by the mixed liquid; S32, passing a part of the tail gas obtained in S31 into the mixed liquid for circulation, and the exhaust tail gas is purified and then discharged.

7. The method for fixing CO2 by using fly ash from garbage incineration and leachate according to claim 6, characterized in that: In the S31, the stirring intensity is 60 to 120 r / min.

8. The method for fixing CO2 by using fly ash from garbage incineration and leachate according to claim 6, characterized in that: The flow rate of the carbon dioxide gas is 1 to 5 mL / (g·min) relative to the mass of the mixed liquid.

9. The method for fixing CO2 by using fly ash from garbage incineration and leachate according to claim 6, characterized in that: In the S32, the ratio of the flow rate of the circulating tail gas to the flow rate of the introduced carbon dioxide gas is 1 to 5:1, the flow rate of the discharged tail gas is substantially consistent with the flow rate of the introduced carbon dioxide gas, and the time for introducing the carbon dioxide gas is 1 to 3 hours.

10. The method for fixing CO2 by using fly ash from garbage incineration and leachate according to claim 6, characterized in that: In the above-mentioned S32, the exhaust gas can be discharged after being absorbed and purified by water.

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