Coal-fired power plant gas-liquid-solid waste collaborative treatment and resource utilization method

Abstract

The invention discloses a gas-liquid-solid waste collaborative treatment and resource utilization method for a coal-fired power plant. Relates to the technical field of gas, liquid and solid waste treatment, in particular to the technical field of collaborative treatment and recycling of gas-liquid-solid waste of a coal-fired power plant. Cooperative treatment of the carbon dioxide, the desulfurization wastewater and the desulfurization gypsum is realized, the treatment efficiency is improved, and the influence on the environment is reduced. The method comprises the following steps: S1, pretreating desulfurization wastewater to obtain alkaline desulfurization wastewater; s2, pretreating the desulfurized gypsum to obtain desulfurized gypsum powder; s3, mixing the alkaline desulfurization wastewater and the desulfurization gypsum powder according to a certain proportion; s4, capturing carbon dioxide gas to complete mineralization reaction; and S5, extracting a product after the mineralization reaction and performing water treatment. A new thought is provided for zero discharge of the desulfurization wastewater, a new direction is provided for the problem of treatment of chloride ions in the desulfurization wastewater, a perfect closed loop of cooperative treatment and resource utilization of wastes is realized, and the effect of treating wastes with wastes is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of gas, liquid and solid waste treatment, and in particular to the technical field of coordinated treatment and resource utilization of gas, liquid and solid wastes in coal-fired power plants. Background Art

[0002] During the slurry circulation process of the flue gas desulfurization device in a coal-fired power plant, heavy metal elements, suspended solids and Cl in the flue gas - Impurities such as chlorine and chlorine will gradually accumulate in the desulfurization wastewater. In order to maintain the balance of substances in the slurry circulation system of the desulfurization device (generally, the slurry Cl - Content is less than 20g / L), to prevent corrosion of desulfurization equipment and ensure the quality of gypsum, a certain amount of desulfurization wastewater must be discharged from the system, so it is very necessary to treat desulfurization wastewater. At present, most of the treatment methods for desulfurization wastewater are traditional "three-tank" processes, but this process has many difficult problems to solve: 1. The water quality of desulfurization wastewater is complex and changeable, requiring multiple reagents to be coordinated and controlled at the same time, the operation control conditions are complex, and the on-site operation is difficult; 2. Due to the frequent fluctuations in the water quality of desulfurization wastewater, the effluent quality is difficult to meet the standards; 3. Acid and alkali are added during the process, the equipment and pipelines are severely corroded, the equipment is frequently repaired and replaced, the operation and maintenance tasks are heavy and the cost is high; 4. There are many types of reagents, large reserves, and certain safety hazards; 5. There is no Cl in the process - treatment measures.

[0003] As a solid industrial waste, desulfurized gypsum is difficult to be used directly in thermal power plants. In the face of desulfurized gypsum produced by thermal power generation units, the existing technology uses a direct wet mineralization method to treat desulfurized gypsum. Direct wet mineralization refers to the mineralization reaction of carbon dioxide and desulfurized gypsum in a reactor with alkaline substances (such as NH4OH or NaOH) as the medium to achieve the treatment of desulfurized gypsum. However, existing alkaline substances, such as sodium hydroxide and ammonia water, are highly corrosive and have pungent odors, which pose a threat to equipment and personal safety, and there are major safety hazards. The cost of governance is also relatively high. Summary of the invention

[0006] In response to the above problems, the present invention discloses a method for coordinated treatment and resource utilization of gas, liquid and solid wastes in coal-fired power plants, which relates to the technical field of gas, liquid and solid waste treatment, realizes the coordinated treatment and resource utilization of carbon dioxide, desulfurization wastewater and desulfurization gypsum, improves treatment efficiency and reduces environmental impact.

[0007] The method comprises the following steps:

[0008] S1. Pre-treating desulfurization wastewater to obtain alkaline desulfurization wastewater;

[0009] S2, pre-treating the desulfurized gypsum to obtain desulfurized gypsum powder;

[0010] S3, mixing alkaline desulfurization wastewater and desulfurization gypsum powder in a certain proportion;

[0011] S4, capturing carbon dioxide gas and completing the mineralization reaction;

[0012] S5. Extracting the product after the mineralization reaction and water treatment.

[0013] 2. Furthermore, the desulfurization wastewater pretreatment is specifically as follows: the desulfurization wastewater is sequentially sent to a sedimentation tank and a clarifier to obtain alkaline desulfurization wastewater and sludge; the alkaline desulfurization wastewater has a pH value of 9 to 10 and contains chloride ions; lime milk and an integrated high-efficiency flocculant are respectively added to the sedimentation tank, and the lime milk and the integrated high-efficiency flocculant are used to remove suspended matter, heavy metals, hardness substances and large particle impurities in the desulfurization wastewater; the sludge is sent to a desludging machine.

[0014] Furthermore, the pretreatment of the desulfurized gypsum is specifically as follows: the desulfurized gypsum is sequentially fed into a crusher and a sieving machine to obtain desulfurized gypsum powder.

[0015] Furthermore, the mixing in a certain proportion is specifically: mixing alkaline desulfurization wastewater and desulfurization gypsum powder in a slurry tank in a certain solid-liquid ratio to obtain desulfurization waste to be treated, and the solid-liquid ratio is: 5-25%; the desulfurization waste to be treated includes: calcium sulfate dihydrate, hydroxide and chloride ions.

[0016] Furthermore, the capturing of carbon dioxide gas specifically includes: capturing carbon dioxide gas emitted from industry and sending it to a mineralization reactor through a pipeline; the flow rate of the carbon dioxide gas is 0.5 to 4 L / min.

[0017] Furthermore, the mineralization reaction is specifically as follows: the desulfurization waste to be treated is sent to a mineralization reactor and carbon dioxide gas is introduced; the temperature of the mineralization reaction is 40 to 80°C, and the time of the mineralization reaction is 10 to 90 minutes; the product of the mineralization reaction is: a mixture and water vapor; the mixture includes: calcium carbonate solid, calcium chloride and sulfate solution.

[0018] Furthermore, the products after the extraction mineralization reaction are specifically as follows: the mixture is sent to a solid-liquid separator to separate calcium carbonate solid, calcium chloride and sulfate solution and liquid water; the calcium carbonate solid is sent to a dryer to obtain dry calcium carbonate solid; the calcium chloride and sulfate solution are sent to a crystallizer to obtain calcium chloride and sulfate solid products and water vapor to be recovered.

[0019] 3. Furthermore, the water treatment is specifically as follows: the water vapor, liquid water and water vapor to be recovered are sent to a hydrophobic reuse tank, and condensed to obtain treated liquid water, and the hydrophobic reuse tank is used for condensation.

[0020] The beneficial effects of the present invention are:

[0021] The invention adopts desulfurization wastewater which is alkaline after pretreatment as an alkaline medium to participate in the mineralization reaction of desulfurization gypsum and carbon dioxide, and no additional alkaline substances need to be added. At the same time, the chloride ions in the desulfurization wastewater can be treated, thereby reducing the treatment cost. The mechanism is simple and easy to operate, and the potential safety hazards are reduced. The generated calcium carbonate can continue to be used for limestone wet flue gas desulfurization in thermal power, electrolytic aluminum, cement and other industries, which can reduce the excessive exploitation of natural limestone ore, promote the carbon cycle in the desulfurization process, and reduce the carbon emission in the desulfurization process. The generated calcium chloride and sulfate products can be used in the chemical, metallurgical and pharmaceutical industries, providing a new idea for zero discharge of desulfurization wastewater, providing a new direction for the difficult problem of chloride ion treatment of desulfurization wastewater, reducing the discharge of waste, reducing the impact on the environment, realizing a perfect closed loop of coordinated waste treatment and resource utilization, achieving the effect of treating waste with waste, and promoting the benign development of the social and economic environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a flow chart of the method described in an embodiment of the present invention. DETAILED DESCRIPTION

[0023] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] This embodiment provides a method for the coordinated management and resource utilization of gas, liquid and solid wastes in coal-fired power plants. The flowchart of the method is as follows: Figure 1 , the method comprises the following steps:

[0025] S1. Pre-treating desulfurization wastewater to obtain alkaline desulfurization wastewater.

[0026] The relevant operations of step S1 are introduced with a specific example:

[0027] The desulfurization wastewater pretreatment is specifically as follows: the desulfurization wastewater is sequentially sent to a sedimentation tank 1 and a clarifier 2 to obtain alkaline desulfurization wastewater and sludge; the alkaline desulfurization wastewater has a pH value of 9 to 10 and contains a large amount of chloride ions; lime milk and an integrated high-efficiency flocculant are respectively added to the sedimentation tank 1, and the lime milk and the integrated high-efficiency flocculant are used to remove pollutants such as suspended matter, heavy metals, hardness substances and large particle impurities in the desulfurization wastewater; the clarifier 2 is used to clarify the alkaline desulfurization wastewater; the sludge is sent to a desludging machine 3.

[0028] S2. Pre-treating the desulfurized gypsum to obtain desulfurized gypsum powder.

[0029] The relevant operations of step S2 are introduced with a specific example:

[0030] 4. The pretreatment of the desulfurized gypsum is specifically as follows: the desulfurized gypsum is a byproduct product of wet flue gas desulfurization used in thermal power, electrolytic aluminum, cement and other industries, wherein the content of calcium sulfate dihydrate is ≥93%; the desulfurized gypsum is sequentially fed into a crusher 4 and a screening machine 5 to obtain desulfurized gypsum powder; the crusher 4 is used to crush the desulfurized gypsum; the screening machine 5 is used to screen the desulfurized gypsum powder.

[0031] S3. Mix the alkaline desulfurization wastewater and desulfurization gypsum powder in a certain proportion.

[0032] The relevant operations of step S3 are introduced with a specific example:

[0033] The mixing in a certain proportion specifically comprises: mixing alkaline desulfurization wastewater and desulfurization gypsum powder in a certain solid-liquid ratio in a slurry tank 6 to obtain desulfurization waste to be treated, wherein the solid-liquid ratio is 5-25%; the desulfurization waste to be treated comprises: calcium sulfate dihydrate, hydroxide and chloride ions.

[0034] S4, capture carbon dioxide gas and complete the mineralization reaction.

[0035] The relevant operations of step S4 are introduced with a specific example:

[0036] The capturing of carbon dioxide gas specifically includes: capturing carbon dioxide gas emitted from industry and sending it to the mineralization reactor 7 through a pipeline; the flow rate of the carbon dioxide gas is 0.5-4 L / min.

[0037] The mineralization reaction is specifically as follows: the desulfurization waste to be treated is sent to the mineralization reactor 7, and carbon dioxide gas is introduced; the temperature of the mineralization reaction is 40-80°C, and the time of the mineralization reaction is 10-90 minutes; the product of the mineralization reaction is: a mixture and water vapor; the mixture includes: solid calcium carbonate and calcium chloride and sulfate solution. The equation of the mineralization reaction is as follows:

[0038]

[0039] This method can remove chloride ions in desulfurization wastewater.

[0040] S5. Extracting the product after the mineralization reaction and water treatment.

[0041] The relevant operations of step S5 are introduced with a specific example:

[0042] The products after the extraction mineralization reaction are specifically as follows: the mixture is sent to a solid-liquid separator 8 to separate calcium carbonate solid, calcium chloride and sulfate solution and liquid water; the calcium carbonate solid is sent to a dryer 9 to obtain dry calcium carbonate solid; the calcium chloride and sulfate solution are sent to a crystallizer 10 to obtain calcium chloride and sulfate solid products and water vapor to be recovered.

[0043] The water treatment is specifically as follows: the water vapor, liquid water and water vapor to be recovered are sent to the hydrophobic reuse tank 11, and condensed to obtain treated liquid water. The hydrophobic reuse tank 11 is used for condensation.

Claims

1. A method for coordinated treatment and resource utilization of gas, liquid and solid wastes from coal-fired power plants, characterized in that: The method comprises the following steps: S1. Pre-treating desulfurization wastewater to obtain alkaline desulfurization wastewater; S2, pre-treating the desulfurized gypsum to obtain desulfurized gypsum powder; S3, mixing alkaline desulfurization wastewater and desulfurization gypsum powder in a certain proportion; S4, capturing carbon dioxide gas and completing the mineralization reaction; S5. Extracting the product after the mineralization reaction and water treatment.

2. The method for coordinated treatment and resource utilization of gas, liquid and solid wastes in coal-fired power plants according to claim 1 is characterized in that: The desulfurization wastewater pretreatment is specifically as follows: the desulfurization wastewater is sequentially sent to a sedimentation tank (1) and a clarifier (2) to obtain alkaline desulfurization wastewater and sludge; the alkaline desulfurization wastewater has a pH value of 9 to 10 and contains chloride ions; lime milk and an integrated high-efficiency flocculant are respectively added to the sedimentation tank (1), and the lime milk and the integrated high-efficiency flocculant are used to remove suspended matter, heavy metals, hardness substances and large particle impurities in the desulfurization wastewater; the sludge is sent to a desludging machine (3).

3. The method for coordinated treatment and resource utilization of gas, liquid and solid wastes in coal-fired power plants according to claim 1 is characterized in that: The pretreatment of the desulfurized gypsum is specifically as follows: the desulfurized gypsum is sequentially fed into a crusher (4) and a sieving machine (5) to obtain desulfurized gypsum powder.

4. The method for coordinated treatment and resource utilization of gas, liquid and solid wastes in coal-fired power plants according to claim 3 is characterized in that: The mixing in a certain proportion specifically comprises: mixing alkaline desulfurization wastewater and desulfurization gypsum powder in a slurry tank (6) in a certain solid-liquid ratio to obtain desulfurization waste to be treated, wherein the solid-liquid ratio is 5-25%; the desulfurization waste to be treated comprises: calcium sulfate dihydrate, hydroxide and chloride ions.

5. The method for coordinated treatment and resource utilization of gas, liquid and solid wastes in coal-fired power plants according to claim 4 is characterized in that: The capturing of carbon dioxide gas specifically includes: capturing carbon dioxide gas emitted from industry and sending it to a mineralization reactor (7) through a pipeline; the flow rate of the carbon dioxide gas is 0.5 to 4 L / min.

6. A method for coordinated treatment and resource utilization of gas, liquid and solid wastes from coal-fired power plants according to claim 5, characterized in that: The mineralization reaction is specifically as follows: the desulfurization waste to be treated is sent to a mineralization reactor (7) and carbon dioxide gas is introduced; the temperature of the mineralization reaction is 40 to 80° C., and the time of the mineralization reaction is 10 to 90 minutes; the products of the mineralization reaction are: a mixture and water vapor; the mixture includes: calcium carbonate solid, calcium chloride and sulfate solution.

7. A method for coordinated treatment and resource utilization of gas, liquid and solid wastes from coal-fired power plants according to claim 6, characterized in that: The products after the extraction and mineralization reaction are specifically: the mixture is sent to a solid-liquid separator (8) to separate calcium carbonate solid, calcium chloride and sulfate solution and liquid water; the calcium carbonate solid is sent to a dryer (9) to obtain dry calcium carbonate solid; the calcium chloride and sulfate solution is sent to a crystallizer (10) to obtain calcium chloride and sulfate solid products and water vapor to be recovered.

8. The method for coordinated treatment and resource utilization of gas, liquid and solid wastes in coal-fired power plants according to claim 7 is characterized in that: The water treatment specifically comprises: sending the water vapor, liquid water and water vapor to be recovered into a hydrophobic recycling tank (11), condensing them to obtain treated liquid water, and the hydrophobic recycling tank (11) is used for condensation.

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