Method and system for synergistically preparing mineral wool in waste incineration power plant

Abstract

The invention discloses a method and system for synergistically preparing mineral wool in a waste incineration power plant. The method comprises the steps of fly ash washing, fly ash pretreatment, a batching system, high-temperature melting, fiber forming and cotton making and molten flue gas treatment. Fly ash (hazardous waste) does not leave a factory, deep fusion of the two processes is carried out through in-plant multi-level cooperation on the premise that the main waste incineration process is not affected, manpower resources of the whole plant are optimized, the advantage of spontaneous green electricity is fully utilized, green building materials are produced through solid waste, the comprehensive cost of recycling of fly ash high-temperature melting cotton making is reduced, and the method is suitable for industrial production. The environmental and social benefits are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of waste treatment, and in particular relates to a method and system for collaboratively preparing mineral wool in a waste incineration power plant. Background Art

[0002] Waste incineration fly ash is enriched with toxic components from all links of waste incineration. The fly ash composition is complex, toxic, and difficult to recycle. Currently, chelation landfill is still the main method, which has become a problem restricting the development of the waste incineration industry. A breakthrough in the resource utilization of fly ash is urgently needed.

[0003] Fly ash resource utilization technologies mainly include cement kiln synergy, low-temperature thermal decomposition and high-temperature melting. Among them, high-temperature melting is the fly ash disposal technology with the most thorough harmlessness and the lowest environmental risk. The production of high-value products such as inorganic thermal insulation cotton through fly ash melting can greatly offset the fly ash melting cost.

[0004] However, according to current application practice experience, although the comprehensive cost of high-temperature melting cotton resource utilization is lower than that of simple high-temperature melting harmless treatment, it is still much higher than the cost of the current mainstream chelation landfill, and it also faces the problem of high market pressure for resource products at the same price. Therefore, how to further reduce the comprehensive cost of fly ash melting cotton resource utilization is a key link. At the same time, reducing environmental pollution in the process of fly ash resource utilization, achieving near-zero emissions, reducing energy consumption, and improving the green attributes of products are the current basic requirements. Therefore, the present invention proposes a method and system for the coordinated preparation of mineral wool in a waste incineration power plant. Summary of the invention

[0005] Technical problems to be solved: In response to the above technical problems, the present invention provides a method and system for the coordinated preparation of mineral wool in a waste incineration power plant, which fully utilizes various resources of existing waste incineration power plants, solves the current problems of serious secondary pollution and high cost in the resource utilization process of fly ash during high-temperature melting, and enhances the market competitiveness of waste incineration fly ash resource utilization; at the same time, fly ash cotton is made by electric melting, using the green energy of the incineration power plant to produce green building materials and reduce carbon dioxide emissions from the plant.

[0006] Technical solution: In the first aspect, the present invention provides a method for collaboratively preparing mineral wool in a waste incineration power plant, comprising the following steps:

[0007] S1. Fly ash washing: The fly ash generated by the waste incineration power plant is washed with water to make the dry basis chlorine content in the fly ash ≤ 3%; the electricity generated by the waste incineration power plant is used to power the plant area and equipment;

[0008] S2. Fly ash pretreatment: including drying and granulation. The moisture content of the dried fly ash is less than 3%, and the particle size after granulation is 10-50mm;

[0009] S3, material proportion: the pre-treated fly ash is mixed with bottom ash, basalt, magnesite and dolomite in proportion to obtain a mixed material. The specific proportion of the ingredients is set according to the mineral wool produced at the back end;

[0010] S4, high temperature melting: melting the mixed material at high temperature to obtain slag and flue gas;

[0011] S5, fiber-forming and cotton-making: transporting the slag to the fiber-forming and cotton-making system to complete the preparation of mineral wool;

[0012] S6. Flue gas treatment: The flue gas generated by high-temperature melting is purified synchronously with the waste gas generated by waste incineration after pretreatment and discharged after meeting the standards.

[0013] Preferably, the waste gas generated during the water washing process in step S1 is transported to the garbage bin of the waste incineration power plant through the exhaust pipe, and then transported to the waste incinerator through the deodorization fan of the waste incineration power plant; the recycled water generated in the water washing evaporation process can be used in the fly ash water washing step, and can also supplement the circulating cooling water of the waste incineration system.

[0014] Preferably, the fly ash in step S2 can be dried by drum or rotary flash evaporation, and steam is used as a heat source for drying, and the steam comes from the secondary steam extracted from the steam turbine of the waste incineration power plant. After drying, granulation is performed by dry rolling.

[0015] Preferably, the dust generated during the batching process in step S3 is collected by a negative pressure system, incorporated into the exhaust duct after dust removal, and sent to the garbage bin of the waste incineration power plant, and then sent to the waste incinerator through the deodorizing fan of the waste incineration power plant.

[0016] Preferably, the high temperature melting in step S4 is performed using a three-phase AC arc furnace or a DC arc furnace.

[0017] Preferably, the waste gas generated in the fiber-forming and cotton-making process in step S5 is sent to a waste incinerator as combustion air to completely decompose organic matter in the waste gas, and the particulate matter is treated in a flue gas purification device of the waste incineration system.

[0018] Preferably, the specific process of flue gas treatment in step S6 is: the flue gas is pretreated through a secondary combustion chamber, a waste heat utilization device, a denitrification device, a quenching tower, an activated carbon injection, a bag filter and a primary wet tower; the pretreated flue gas enters the flue gas treatment device of the waste incineration system for coordinated disposal and discharge, and the deacidified and salt-containing wastewater generated in the wet tower part of the system is treated and reused in the fly ash washing step.

[0019] In a second aspect, the present invention provides a system used in the method described in the first aspect, comprising a waste incineration system and a fly ash resource system.

[0020] The waste incineration system comprises a waste bin, a waste incinerator and a waste heat boiler which are connected in sequence. The steam outlet of the waste heat boiler is connected to the steam inlet of the steam turbine. The electricity generated by the steam turbine enters the power system. The flue gas outlet of the waste heat boiler is connected to the flue gas purification system. The flue gas treated by the flue gas purification system is discharged after meeting the standards. The purified fly ash obtained by the flue gas purification system enters the fly ash resource system.

[0021] The purified fly ash is washed with water by a water washing device in the fly ash resource system and then enters a fly ash pretreatment system, wherein the fly ash pretreatment system comprises a drying system, a granulation system and a batching system connected in sequence. The dust generated by the drying system, the granulation system and the batching system is recovered to the garbage bin after passing through a bag dust collector, and the mixed material obtained after passing through the batching system is sent to a high-temperature melting furnace, and the generated slag enters the fiber-making system through a centrifugal blowing device to be made into mineral wool, and the exhaust gas generated by the fiber-making system is sent to the garbage bin through a dust collector.

[0022] Preferably, the wastewater generated by the water washing device passes through a wastewater purification device and a wastewater evaporation device in sequence, and the generated condensed water is used as circulating cooling water for the waste incineration system, and the sediment outlet of the wastewater purification system is connected to the inlet of the high-temperature melting furnace.

[0023] Preferably, the flue gas outlet of the high-temperature melting furnace is connected in sequence with a flue gas pretreatment system and a flue gas purification system, the flue gas pretreatment system includes a secondary combustion chamber, a waste heat boiler, a quenching tower, a bag filter and a wet tower connected in sequence, the salt-containing wastewater outlet of the wet tower is connected to a membrane concentration device, the wastewater outlet of the membrane concentration device is connected to the inlet of a wastewater purification device, and the flue gas outlet of the wet tower is connected to the flue gas inlet of the waste heat boiler of the waste incineration system.

[0024] Beneficial effects: 1) The fly ash generated by the incineration system in the waste incineration plant can be directly transported to the fly ash cotton resource system as its main raw material through a warehouse pump without being transported by hazardous waste vehicles. On the one hand, it reduces the risk of secondary pollution caused by fly ash leakage, and on the other hand, it ensures that hazardous waste is not produced, reducing the cost of raw materials;

[0025] 2) The fly ash cotton resource system uses green electricity generated by the waste incineration system, eliminating the problem of selling electricity through partition walls. The electricity price is lower than that of regional industrial electricity, which reduces the energy cost of fly ash resource utilization. At the same time, it uses green electricity and conforms to the production concept of new green building materials;

[0026] 3) There are many scattered sewage discharge points in each process unit of fly ash resource washing, pretreatment, batching, fiber forming, etc. After being collected and simply treated, these sewage discharge points can be sent to the garbage bin and passed through the negative pressure fan to the garbage incinerator for system treatment, which reduces the investment in a large number of environmental protection equipment and reduces the energy consumption of the system;

[0027] 4) In the fly ash resource system, the low-grade steam from the waste incineration system can be used for material pre-drying and product film lamination, etc., to improve the energy utilization efficiency of the entire plant;

[0028] 5) The flue gas purification process generated by the high-temperature melting of the fly ash cotton resource system and the waste incineration process are deeply coordinated to increase the redundancy of the flue gas treatment system and ensure that the system flue gas is stable and meets the standards. At the same time, through the respective characteristics of the two systems, the solid waste and waste gas in the factory are solved, and the near-zero emission of the waste incineration power generation project is achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic flow diagram of a method for collaboratively preparing mineral wool in a waste incineration power plant according to the present invention. DETAILED DESCRIPTION

[0030] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments:

[0031] Example 1

[0032] A 600t / d waste incineration power plant, with a 30t / d waste incineration fly ash melting cotton production line built in the plant, to dispose of the fly ash in the plant, and the target resource product is rock wool, with an output of about 40t / d. The waste incineration production line is two 300t / d lines, and the flue gas treatment process adopts waste heat utilization + semi-dry deacidification tower + dry activated carbon + bag + wet deacidification, and the flue gas emissions meet GB18484 and local standards. The two lines share a 15MW generator set. The raw fly ash from the incineration plant was sampled and tested, and the main components of the fly ash are shown in Table 1 below:

[0033] Table 1 Main components of fly ash

[0034] Components <![CDATA[H2O]]> C <![CDATA[SO3]]> <![CDATA[CaCl2]]> NaCl KCl CaO <![CDATA[SiO2]]> <![CDATA[Al2O3]]> MgO <![CDATA[Fe2O3]]> ％ 6.23 2 11.4 21.25 7.16 4.69 31.76 7.6 2.06 2.2 1.47

[0035] like Figure 1 As shown: fly ash is transported to the fly ash melting cotton making system through pneumatic conveying pipeline. According to the fly ash composition, a three-stage countercurrent washing process is adopted, and the water-ash ratio is about 3:1. After washing, the dry chlorine content of the fly ash is less than 2%, the moisture content is less than 35%, and the total amount is about 1.05t / h. During the washing and stirring process, part of the ammonia in the fly ash will volatilize and be sent to the garbage bin through the exhaust pipe of the washing tank. The gas volume is about 1800Nm 3 / h.

[0036] After softening, weight removal, concentration and other purification processes, the wash water is evaporated for salt separation. The evaporation water volume is about 4.66t / h, and the products are industrial sodium chloride and potassium chloride. The precipitate produced in the softening process is washed with fly ash and enters the subsequent drying system. The condensed water produced by evaporation is about 4t / h, and the total hardness is below 200mg / L. The water quality meets the requirements of the system's circulating cooling water and can be used as circulating cooling water for the entire plant.

[0037] After washing, the fly ash enters the fly ash pretreatment system. The main pollutants in the waste gas during the pretreatment process are particulate matter. After passing through the bag filter, it is sent to the garbage bin of the waste incineration system. The gas volume is about 5000Nm 3 / h. The heat source for material drying comes from the 1.6MPa / 204℃ steam generated by the waste incineration waste heat system, and the steam consumption is about 1t / h.

[0038] The electricity consumed by the fly ash melting system is entirely derived from the power generation of the waste incineration system. Since the actual amount of waste entering the plant is less than the design value, the total power generation of the plant is approximately 10.5MW, of which the in-plant electricity consumption of the waste incineration system is approximately 1.4MW, the electricity consumption of the fly ash melting cotton line is approximately 7MW, and the remaining electricity is supplied to the grid.

[0039] The main pollutants of the waste gas generated by cotton collection, solidification and cooling in the melting cotton making system are organic matter and particulate matter. After passing through the cotton board dust removal room, it is sent to the garbage bin of the garbage incineration system. Since most of the dust is collected by the dust collecting hood, the gas volume of this part is the largest, about 13000Nm 3 / h.

[0040] The total volume of gas sent to the garbage bin is about 19800Nm 3 / h, the primary air required for the combustion of the 300t / d waste incineration system is taken from the waste bin, which is generally 35000Nm 3 / h or more, the two incineration lines take a total of 70000Nm 3 / h or more, which is much higher than the total amount of gas sent into the garbage bin by the three parts. The amount of flue gas sent into the garbage bin by the three parts of melting cotton making will not have a negative impact on the system.

[0041] The flue gas volume at the outlet of the melting furnace of the 30t / d fly ash melting project is about 400Nm 3 / h. Due to the small amount of flue gas, the fly ash melting cotton flue gas treatment line of this project does not have a waste heat recovery system. It adopts a treatment solution of secondary combustion chamber + quenching tower (including denitrification) + activated carbon + bag + wet method. The flue gas volume at the outlet of the wet method tower is about 1000Nm 3 / h. If it directly enters the waste incineration flue gas without preliminary treatment, the high concentration of flue gas pollutants can easily cause the incineration flue gas emissions to exceed the standard. The fly ash resource utilization and waste incineration system are coordinated for disposal. The access point is in front of the waste heat boiler of the waste incineration power generation project. Through certain pretreatment, it meets the process requirements of hazardous waste incineration flue gas, reduces the pollutant concentration in the fly ash melting resource flue gas, and ensures that it does not affect the incineration system. Through coordinated treatment, the redundancy of the flue gas treatment system is increased to ensure that the system flue gas is stable and meets the standards. The secondary fly ash generated by the secondary combustion chamber, quenching tower and bag filter is sent back to the fly ash washing device for treatment. The flue gas pollutant emission values ​​after preliminary flue gas purification are shown in Table 2 below:

[0042] Table 2 Flue gas pollutant emission values ​​after preliminary flue gas purification

[0043] project Fly ash melting wet tower outlet HCl <![CDATA[1.03mg / Nm 3 ]]> <![CDATA[SO2]]> <![CDATA[38.94mg / Nm 3 ]]> NOx <![CDATA[189.21mg / Nm 3 ]]> dust <![CDATA[9.80mg / Nm 3 ]]> <![CDATA[O2]]> 5.48％

[0044] The flue gas from the melting cotton making system is processed in coordination with a 300t / d incineration flue gas treatment line. After preliminary treatment, it is introduced into the flue before the waste heat boiler of the waste incineration system. The flue gas volume of a waste incineration system line is about 60,000Nm 3 / h. After coordinated treatment, the emission values ​​of flue gas pollutants from the chimney outlet of the whole plant are shown in Table 3 below, which meet the local ultra-low emission standards:

[0045] Table 3 Emission values ​​of flue gas pollutants from chimney outlets of the whole plant after coordinated treatment

[0046] project unit Chimney emissions <![CDATA[Stack emissions (converted value at 11% O2)]]> HCl <![CDATA[mg / Nm 3 ]]> 3.53 3.73 <![CDATA[SO2]]> <![CDATA[mg / Nm 3 ]]> 22.14 23.40 NOx <![CDATA[mg / Nm 3 ]]> 72.98 77.15 dust <![CDATA[mg / Nm 3 ]]> 4.04 4.27 <![CDATA[O2]]> ％ 11.52

[0047] The wastewater generated by the two wet deacidification systems of the garbage incineration system and the fly ash melting cotton making system is treated together. After cooling, the wastewater enters the membrane system for concentration, and the salt concentration is concentrated from about 6% to more than 15%. Then it is sent to the softening unit of the washing wastewater treatment for hardness removal. The wastewater is completely consumed in the plant, achieving zero discharge.

[0048] Through the above-mentioned collaborative process, financial, comprehensive management, and operation personnel work together to save more than 50% of personnel costs. Through process water, electricity, gas, and environmental protection equipment, a high degree of collaboration is achieved, saving more than 10% of equipment investment and more than 30% of operating costs, ultimately achieving low-cost resource disposal of waste incineration fly ash, opening up a new market promotion route for the resource utilization of waste incineration fly ash.

[0049] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for collaboratively preparing mineral wool in a waste incineration power plant, characterized in that: The following steps are involved: S1. Fly ash washing: The fly ash generated by the waste incineration power plant is washed with water to make the dry basis chlorine content in the fly ash ≤3%; the electricity generated by the waste incineration power plant is used to power the plant area and equipment; S2. Fly ash pretreatment: including drying and granulation. The moisture content of the dried fly ash is less than 3%, and the particle size after granulation is 10-50mm; S3, material proportion: the pre-treated fly ash is mixed with bottom ash, basalt, magnesite and dolomite in proportion to obtain a mixed material. The specific proportion of the ingredients is set according to the mineral wool produced at the back end; S4, high temperature melting: melting the mixed material at high temperature to obtain slag and flue gas; S5, fiber-forming and cotton-making: transporting the slag to the fiber-forming and cotton-making system to complete the preparation of mineral wool; S6. Flue gas treatment: The flue gas generated by high-temperature melting is purified synchronously with the waste gas generated by waste incineration after pretreatment and discharged after meeting the standards.

2. The method according to claim 1, characterized in that: The waste gas generated during the water washing process in step S1 is transported to the garbage bin of the waste incineration power plant through the exhaust pipe, and then sent to the waste incinerator through the deodorization fan of the waste incineration power plant; the recycled water generated in the water washing evaporation process can be used in the fly ash water washing step, and can also supplement the circulating cooling water of the waste incineration system.

3. The method according to claim 1, characterized in that: In step S2, the fly ash can be dried by drum or rotary flash evaporation. Steam is used as a heat source for drying. The steam comes from the secondary steam extracted from the steam turbine of the waste incineration power plant. After drying, granulation is performed by dry rolling.

4. The method according to claim 1, characterized in that: The dust generated during the batching process in step S3 is collected by a negative pressure system, and after dust removal, it is incorporated into the exhaust pipe and sent to the garbage bin of the waste incineration power plant, and then sent to the waste incinerator through the deodorizing fan of the waste incineration power plant.

5. The method according to claim 1, characterized in that: In step S4, high temperature melting is performed using a three-phase AC arc furnace or a DC arc furnace.

6. The method according to claim 1, characterized in that: The waste gas generated in the fiber-forming and cotton-making process in step S5 is sent to the waste incinerator as combustion air to completely decompose the organic matter in the waste gas, and the particulate matter is treated in the flue gas purification device of the waste incineration system.

7. The method according to claim 1, characterized in that: The specific process of flue gas treatment in step S6 is as follows: the flue gas is pre-treated through the secondary combustion chamber, waste heat utilization device, denitrification device, quenching tower, activated carbon injection, bag filter and primary wet tower; the pre-treated flue gas enters the flue gas treatment device of the waste incineration system for coordinated disposal and discharge, and the deacidified and salt-containing wastewater generated in the wet tower part of the system is treated and reused in the fly ash washing step.

8. A system used in the method according to any one of claims 1 to 7, characterized in that: Including waste incineration system and fly ash resource system, The waste incineration system comprises a waste bin, a waste incinerator and a waste heat boiler which are connected in sequence. The steam outlet of the waste heat boiler is connected to the steam inlet of the steam turbine. The electricity generated by the steam turbine enters the power system. The flue gas outlet of the waste heat boiler is connected to the flue gas purification system. The flue gas treated by the flue gas purification system is discharged after meeting the standards. The purified fly ash obtained by the flue gas purification system enters the fly ash resource system. The purified fly ash is washed with water by a water washing device in the fly ash resource system and then enters a fly ash pretreatment system, wherein the fly ash pretreatment system comprises a drying system, a granulation system and a batching system connected in sequence. The dust generated by the drying system, the granulation system and the batching system is recovered to the garbage bin after passing through a bag dust collector, and the mixed material obtained after passing through the batching system is sent to a high-temperature melting furnace, and the generated slag enters the fiber-making system through a centrifugal blowing device to be made into mineral wool, and the exhaust gas generated by the fiber-making system is sent to the garbage bin through a dust collector.

9. The system according to claim 8, characterized in that: The wastewater generated by the water washing device passes through the wastewater purification device and the wastewater evaporation device in sequence, and the generated condensed water is used as circulating cooling water for the waste incineration system. The sediment outlet of the wastewater purification system is connected to the inlet of the high-temperature melting furnace.

10. The system according to claim 8, characterized in that: The flue gas outlet of the high-temperature melting furnace is connected in sequence with a flue gas pretreatment system and a flue gas purification system. The flue gas pretreatment system includes a secondary combustion chamber, a waste heat boiler, a quenching tower, a bag filter and a wet tower connected in sequence. The salt-containing wastewater outlet of the wet tower is connected to a membrane concentration device, the wastewater outlet of the membrane concentration device is connected to the inlet of a wastewater purification device, and the flue gas outlet of the wet tower is connected to the flue gas inlet of the waste heat boiler of the waste incineration system.

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