CN111922026A - Incineration fly ash triboelectric separation treatment equipment and method - Google Patents

Abstract

The invention discloses an incineration fly ash triboelectric separation treatment equipment and method. The household garbage is incinerated and flue gas purified by equipment such as a fluidized bed incinerator, a semi-dry absorption tower, an activated carbon injector, a bag filter, etc. The incineration fly ash is subjected to triboelectric separation by vibrating friction device and drum electric separator. After the separation by electric separation, two products of fine ash and tail ash are obtained. The tail ash is treated by electrodialysis to remove and recover heavy metals. After electrodialysis The residual ash is directly sent to the landfill for landfill disposal, and the refined ash product is sent to the incinerator as a combustion-supporting material, and the dioxin is decomposed while the activated carbon is used as a fuel. Innocent treatment and high value-added utilization of fly ash, while reducing the operating cost of the incineration plant.

Description

Incineration fly ash triboelectric separation treatment equipment and method

technical field

The invention belongs to the technical field of waste incineration fly ash treatment, and specifically relates to an incineration fly ash triboelectric separation treatment device and method.

Background technique

The incineration method for domestic waste treatment has become the mainstream method of domestic waste treatment in my country because of its short treatment time, small footprint, volume reduction, harmlessness and heat recovery. There were about 400 domestic waste incineration power plants at the end of 2018, with a total waste incineration of over 380,000 tons per day. Most of the dioxins (70%-90%) produced by waste incineration are transferred to the incineration fly ash. The incineration fly ash has been included in the "National List of Hazardous Wastes" in my country due to its enrichment of highly toxic dioxins and toxic heavy metals. Calculated according to the amount of fly ash produced by 3% to 5% of the waste incineration volume, about 16,000 tons of fly ash will be produced every day in the country, and these fly ash have become a huge hidden danger to urban environmental safety. In order to strictly control the emission of toxic substances in the incineration process, in 2014, China raised the emission standard of dioxins in waste incineration flue gas from 1.0ng I-TEQ/m ³ to 0.1ng I-TEQ/m ³ . According to the standard, the incineration plant needs to inject a large amount of activated carbon into the flue to adsorb dioxins in the flue gas. The injection amount of activated carbon is 150-200 mg/ ^Nm3 of flue gas. Most of the activated carbon that adsorbs dioxins is transferred to the bag fly ash. Therefore, the fly ash contains a considerable amount of carbon components (activated carbon and virgin carbon). In addition, a small amount of unburned carbon residue from the incinerator also enters the bag fly ash. The above two aspects lead to a high content of carbon components (activated carbon and unburned carbon residue) in the incineration fly ash, which is an organic pollutant such as dioxin. source of enrichment. The forms of heavy metals such as Cd, Zn, and Pb in fly ash are mainly in exchangeable (F1) and carbonate (F2) states, with strong mobility. At present, domestic waste incineration fly ash is mainly cement solidified and then sent to domestic waste landfill for landfill disposal. This method is aimed at solidifying heavy metals, which cannot eliminate the potential danger of dioxins, and causes cement consumption due to high carbon components. Therefore, it is urgent to develop suitable treatment methods for high carbon characteristics.

Since the carbon components in the incineration fly ash are mainly in the form of monomer particles, the high carbon components in the fly ash can be removed using physical separation methods. The feasible physical separation methods include wet method represented by flotation and dry method represented by electroselection. The former is based on the difference in the surface properties (wettability) of carbon element and ash element in fly ash, that is, carbon element has better hydrophobicity than ash element, and it is easy to adhere to flotation under the action of oil collectors. The air bubbles in the machine and then float up. Patents 201410034832.5 and 201510705257.1 disclose the treatment methods of medical waste incineration fly ash decarburization and flotation combined with sulfide precipitation or ion flotation to recover heavy metals, which solves the problems of fly ash decarburization and heavy metal recovery. In addition, the direct return of fly ash to the incinerator for reburning has been proved to be a method for decomposing dioxins at high temperature, and the decomposition rate of dioxins can reach more than 99%. The flotation method has better carbon removal effect, but flotation is a wet process. After flotation, the carbon-rich fine ash needs to undergo expensive dehydration and drying steps before being sent to the incinerator to support combustion, and its investment and operating costs are very high. high, which limits the popularization and application of flotation technology to a certain extent.

In incineration fly ash, the carbon component has good electrical conductivity relative to non-conductive inorganic materials, and this electrical difference provides a prerequisite for the electrification of incineration fly ash. The difference in the electrical properties of carbon components and inorganic substances can be enhanced by triboelectric charging, and then the simultaneous separation of carbon components and dioxins in fly ash can be achieved within an electrostatic field. Compared with the flotation method, the electric separation method has dry operation, simple process, and does not require a huge waste water treatment and product dehydration system. As a dry separation method, the triboelectric separation technology not only saves the high cost of dehydration and product drying system. It also effectively avoids environmental pollution and waste of water resources caused by the sorting process.

Electrodialysis is a physical and chemical process in which ions migrate from one part of the solution to another part of the solution by using the selective permeability of the ion exchange membrane under the action of an external DC electric field. The electrodialysis device is made based on the principle that the ion membrane can selectively permeate the anions and cations of the electrolyte in the solution under the action of the DC electric field, that is, the cations can pass through the cation membrane, and the anions can pass through the anion membrane. The anion and cation exchange membranes move directionally and enter the anion and cation concentration chamber. Electrodialysis technology has been widely used in wastewater treatment and removal of heavy metals from contaminated soil. Patent 201310681066.7 discloses a method for removing heavy metals from waste incineration fly ash by electrodialysis. Taking into account the hydrophobic properties of dioxins, it is almost insoluble during electrodialysis, and activated carbon in fly ash has a strong effect on dioxins. After electrodialysis, the dioxin content in the residual ash will exceed that of the original ash, and the remaining residual ash still cannot directly enter the landfill. It can be seen that electrodialysis is more suitable for treating fly ash after removing dioxins.

SUMMARY OF THE INVENTION

The object of the present invention is to overcome the deficiencies of the prior art, in order to eliminate the dioxin hazard in the waste incineration fly ash, to solve the impact of high-content activated carbon on the follow-up treatment of the fly ash, and to provide a kind of incineration fly ash triboelectric separation treatment equipment and method, It can make the carbon components in the fly ash carry electric charges through friction, and then separate the carbon components and dioxins in the fly ash synchronously through electro-selection and dry method to obtain two products of fine ash and tail ash. Incineration and reburning solves the problem of dioxin decomposition and fuel reuse. The tail ash is recovered and removed by electrodialysis, and dechlorinated at the same time. It can safely and effectively realize the harmless treatment of fly ash and use it with high added value.

The present invention is achieved through the following technical solutions:

An incineration fly ash triboelectric separation treatment equipment, characterized in that it comprises a fluidized bed incinerator, a semi-dry absorption tower, an activated carbon ejector, a bag filter, a vibration friction device, and a drum electric separator,

The air outlet of the fluidized bed incinerator is connected to the inlet of the semi-dry absorption tower, the outlet of the semi-dry absorption tower is connected to the air inlet of the bag filter through the activated carbon injector, and the air outlet of the bag filter is connected to the chimney through the induced draft fan. The discharge port at the bottom of the dust collector is connected with the discharge port of the vibration friction device to the feed port of the drum electric separator, and the carbon-rich fine ash discharge port of the drum electric separator is connected to the waste feed port of the incinerator.

The operating method of the incineration fly ash triboelectric separation treatment equipment is as follows:

The domestic waste first enters the fluidized bed furnace for incineration, and the bottom ash after incineration is discharged from the discharge port at the bottom of the grate furnace. The flue gas generated by the incineration is deacidified by the semi-dry absorption tower, and the activated carbon injector sprays activated carbon powder to absorb the flue gas. The dioxins in the dioxin, the activated carbon powder that adsorbs dioxins and the fly ash are mixed together, enter the bag filter to become the bag fly ash, and the flue gas passing through the bag filter is discharged from the chimney through the induced draft fan;

The incineration fly ash collected by the bag filter is sent to the mixer, where it is fully mixed with the modifier and the modifier, and then sent to the vibrating friction device, and the charged fly ash after frictional charging enters the drum electric separator. Electro-separation is carried out to obtain carbon-rich fine ash, intermediate products and tail ash after separation.

The intermediate product is sent back to the electric separator for electrical separation again, and finally carbon-rich fine ash and tail ash are obtained;

The enriched fine ash is directly sent to the incinerator as a combustion-supporting material for fuel utilization, and the dioxin is decomposed while the activated carbon is used as a fuel;

The tail ash product is then mixed with additives and water to form mortar and electrodialysis treatment in the electrodialysis tank. After treatment, three products including heavy metal concentrate, residual ash and waste liquid are obtained. The heavy metal concentrate can be recovered by hydrometallurgy. Pb, Zn and other heavy metals, the residual ash is directly sent to the landfill for landfill treatment, and the waste liquid is directly sent to the sewage system for safe discharge.

In the above technical scheme, the modifier is one of kerosene, diesel oil, acetic acid, ethanol, etc., and the added mass is 5-15 g/kg fly ash.

In the above technical scheme, the adjusting agent is one or more of surfactants such as Tween80, SDS, and n-hexane, acetone, toluene, etc., and the added mass is 5-20 g/kg fly ash.

The advantages and beneficial effects of the present invention are:

In the present invention, a modifier is firstly added to the fly ash to enhance the charge difference between the carbon component and the inorganic matter in the fly ash, and at the same time, a modifier is added to promote the adsorption of dioxin on the carbon component in the process of the fly ash frictional charging. In this method, the incineration fly ash is triboelectrically charged to make the inorganic substances in it and activated carbon oppositely charged, and then the synchronous separation of carbon components and dioxins is realized in a high-voltage electrostatic field, and fine ash and tail ash are obtained by electrical separation. There are two kinds of products. Among them, the fine ash product is dry and the carbon content is about 4 times that of the original fly ash, and the calorific value exceeds 3000 kcal. The pyrolysis of oxin and the utilization of carbon components as fuel can effectively reduce the amount of coal added in the incineration plant; the tail ash product is then treated by electrodialysis, and the content of chloride salts and heavy metals in the remaining residual ash is very low, and the volume is greatly reduced , it can be directly sent to the domestic waste landfill to realize its final safe disposal. The heavy metal concentrate can be used as the raw material of the smelter to recover heavy metals such as Pb and Zn, and the remaining waste water can be treated and discharged. This method can perform on-line electrical separation at the bottom of the bag filter of the incinerator, reduce the toxicity of dioxins in the fly ash and the amount of landfill disposal, and greatly solve the problem of the high content of carbon components in the fly ash in the current domestic cement solidification method. The disadvantages of large consumption and effectively reduce the environmental risk of dioxins in landfills. The invention can realize the harmless treatment and high value-added utilization of the waste incineration fly ash under the condition of low cost. The invention solves multiple problems with one process, and has the advantages of simple operation, low cost, good treatment effect and non-existent secondary pollution and other advantages.

Description of drawings

Fig. 1 is the structural schematic diagram of the incineration fly ash triboelectric separation treatment equipment in the embodiment.

In the embodiment of Fig. 2, incineration fly ash triboelectric separation and tail ash electrodialysis treatment process flow chart

Detailed ways

The technical solutions of the present invention are further described below in conjunction with specific embodiments.

Referring to accompanying drawing 1, incineration fly ash triboelectric separation treatment equipment, including fluidized bed incinerator, semi-dry absorption tower, activated carbon ejector, bag filter, mixer, vibration friction device, drum electric separator,

The domestic waste first enters the fluidized bed furnace for incineration, and the bottom ash after incineration is discharged from the discharge port at the bottom of the fluidized bed furnace. The flue gas generated by the incineration is discharged through the tail of the incinerator, and the flue gas outlet at the tail of the incinerator is connected to the semi-dry absorption tower. , so that the flue gas discharged from the incinerator is deacidified through the semi-dry absorption tower, and the outlet of the semi-dry absorption tower is connected to the air inlet of the bag filter through the activated carbon injector, and the activated carbon injector sprays activated carbon powder to absorb the Dioxins, activated carbon powder adsorbing dioxins and fly ash are mixed together. These activated carbon powder adsorbing dioxins are filtered and transferred to the bag fly ash through the bag filter, and the gas passing through the bag filter is passed through the induced draft fan. Chimney exhaust.

The air outlet of the fluidized bed incinerator is connected to the inlet of the semi-dry absorption tower, the outlet of the semi-dry absorption tower is connected to the air inlet of the bag filter through the activated carbon injector, and the air outlet of the bag filter is connected to the chimney through the induced draft fan. The discharge port at the bottom of the dust collector is connected with the feed port of the vibrating friction device. The fly ash, modifier and adjusting agent are fully mixed and charged in the friction device. The discharge port of the vibrating friction device is connected with the inlet of the drum electric separator. The charged fly ash from the filter bag enters the drum electrical separator for electrical separation, and after separation, carbon-rich fine ash, intermediate products and tail ash are obtained;

The intermediate products are sent back to the electrical separator for further electrical separation, and finally carbon-rich fine ash and tail ash products are obtained; the enriched fine ash is sent to the waste raw material of the incinerator as a combustion-supporting material for fuel utilization. Referring to accompanying drawing 2, the tail ash product is mixed with auxiliary agent and water into mortar, and electrodialysis treatment is carried out in the electrodialysis tank. After the treatment, 3 kinds of products such as heavy metal concentrate, residual ash and waste liquid are obtained. The heavy metal concentrate can pass wet Heavy metals such as Pb and Zn are recovered by metallurgical method, the residual ash is directly sent to the landfill for landfill treatment, and the waste liquid is directly sent to the sewage system for safe discharge.

The specific method for electrifying fly ash is described below in conjunction with specific embodiments.

Example 1:

The chemical composition, ignition loss rate and dioxin content of a certain waste incineration fly ash (ie, cloth bag fly ash) are shown in Table 1. Add 0.5% (mass ratio) of kerosene as modifier and 2% of n-hexane as modifier to the waste incineration fly ash, mix evenly and send it to the vibration friction device for frictional charging, and the charged fly ash is sent to the drum The electric separator is electrically selected. The voltage of the drum electric separator is 45kV, the drum speed is 200r/min, and the intermediate product is electrically separated twice. The carbon content in the product is 39.46% and 4.27% respectively, the dioxin content is 8.35 and 2.65ng I-TEQ/g respectively, the calorific value of the carbon-rich fine ash reaches 2985 kcal, and the carbon-rich fine ash is used as the waste incinerator. Combustion-supporting materials are mixed into the garbage for incineration to realize the fuel utilization of carbon components and the decomposition of dioxins. The dioxin content in tail ash meets the dioxin limit required by GB16889-2008 (<3ng TEQ/g)

Referring to accompanying drawing 2, the above-mentioned tail ash product is subjected to electrodialysis treatment. First, sodium citrate and water are prepared into a solution according to 1:10. The electrodialysis treatment was carried out in the electrodialysis tank with a current density of 15A/m2. After 12 days of electrodialysis treatment, it was found that the recovery rates of heavy metals such as Pb, Zn, and Cd after electrodialysis treatment reached 17.5% and 24.3%, respectively. , 50.5%; 63.4% of chlorine in the tail ash is removed, and the waste liquid is directly sent to the sewage system for safe discharge; the heavy metal concentrate can further recover heavy metals such as Pb and Zn through hydrometallurgy; Cu, Pb, Zn, The leaching concentrations of heavy metals such as Cd are 0.09mg/L, 1.14mg/L, 2.32mg/L, and 0.05mg/L, which are lower than the "Standards for Pollution Control of Domestic Waste Landfills" (GB16889-2008), and meet the requirements of direct entry Standard for domestic waste landfills.

Table 1: Main chemical composition, ignition loss rate and dioxin content (%) of incineration fly ash in Example 1

Table 2: Loss on ignition, heavy metal and dioxin content (%) of incineration fly ash in Example 1

Example 2:

Using the same incineration fly ash in Example 1, add 1.5% (mass ratio) acetic acid as modifier, 1.0% acetone and 0.4% surfactant (Tween80) as modifiers and join in waste incineration fly ash, After mixing evenly, it is sent to the vibrating friction device for frictional charging, and the charged fly ash is sent to the drum electric separator for electric separation. The voltage of the drum electric separator is 38kV, and the drum speed is 220r/min. The carbon-rich fine ash and tail ash were finally obtained after electro-separation. The carbon content of the two products was 38.77% and 4.97%, respectively, and the dioxin content was 8.16 and 2.78ng I-TEQ/g, respectively. Ash can be added with a small amount of cement to solidify heavy metals and then sent to landfill for domestic waste disposal. Fuel utilization and decomposition of dioxins. The dioxin content in tail ash meets the dioxin limit required by GB16889-2008 (<3ng TEQ/g)

Referring to accompanying drawing 2, the above-mentioned tail ash product is subjected to electrodialysis treatment. First, sodium citrate and water are prepared into a solution according to 1:9. The electrodialysis treatment was carried out in the electrodialysis tank with a current density of 16.5A/m2. After 14 days of electrodialysis treatment, it was found that the recovery rates of heavy metals such as Pb, Zn, and Cd after electrodialysis treatment reached 18.2% and 23.8%, respectively. %, 51.2%; 61.4% of chlorine in the tail ash is removed, and the waste liquid is directly sent to the sewage system for safe discharge; the heavy metal concentrate can further recover heavy metals such as Pb and Zn through hydrometallurgy; Cu, Pb, Zn, The leaching concentrations of heavy metals such as Cd were 0.09mg/L, 1.02mg/L, 2.31mg/L, and 0.03mg/L, which were lower than the "Standards for Pollution Control of Domestic Waste Landfills" (GB16889-2008), which were in line with the direct entry Standard for domestic waste landfills.

Example 3:

Using the same incineration fly ash in Example 1, adding 0.7% (mass ratio) of acetic acid as modifier, 0.9% of toluene and 0.8% of surfactant (SDS) as modifiers and added to the waste incineration fly ash, After mixing evenly, it is sent to the vibrating friction device for frictional charging, and the charged fly ash is sent to the drum electric separator for electric separation. The voltage of the drum electric separator is 25kV, and the drum speed is 160r/min. The carbon-rich fine ash and tail ash are finally obtained after separation by electro-separation. Ash can be added with a small amount of cement to solidify heavy metals and then sent to landfill for domestic waste disposal. Fuel utilization and decomposition of dioxins. The dioxin content in tail ash meets the dioxin limit required by GB16889-2008 (<3ng TEQ/g)

Referring to accompanying drawing 2, the above-mentioned tail ash product is subjected to electrodialysis treatment. First, sodium citrate and water are prepared into a solution according to 1:12. The electrodialysis treatment was carried out in the electrodialysis tank with a current density of 14A/m2. After 13 days of electrodialysis treatment, it was found that the recovery rates of heavy metals such as Pb, Zn, and Cd after electrodialysis treatment reached 17.5% and 24.2%, respectively. , 52.2%; 62.6% of chlorine in the tail ash is removed, and the waste liquid is directly sent to the sewage system for safe discharge; the heavy metal concentrate can further recover heavy metals such as Pb and Zn through hydrometallurgy; Cu, Pb, Zn, The leaching concentrations of heavy metals such as Cd are 0.08mg/L, 1.11mg/L, 2.25mg/L, and 0.05mg/L, which are lower than the "Standards for Pollution Control of Domestic Waste Landfills" (GB16889-2008), which are in line with the direct entry Standard for domestic waste landfills.

The above embodiment describes a new process for the innocuous treatment and resource utilization of waste incineration fly ash, and the present invention is suitable for domestic waste incineration fly ash and medical waste incineration fly ash. The friction device is not limited to the vibration friction device, and the electric separator is not limited to the drum electric separator, but can also be other triboelectric separation equipment for coal and fly ash.

Although the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, the present invention is not limited to the above-mentioned specific embodiments. Under the inspiration of the present invention, without departing from the spirit of the present invention and the protection scope of the claims, personnel can also make many forms, which all fall within the protection scope of the present invention.

Claims (2)

1. a kind of incineration fly ash triboelectric selection treatment equipment, it is characterized in that: comprise fluidized bed incinerator, semi-dry absorption tower, activated carbon ejector, bag filter, vibration friction device, drum electric separator, wherein: The air outlet of the fluidized bed incinerator is connected to the inlet of the semi-dry absorption tower, the outlet of the semi-dry absorption tower is connected to the air inlet of the bag filter through the activated carbon injector, and the air outlet of the bag filter is connected to the chimney through the induced draft fan. The discharge port at the bottom of the dust collector is connected with the inlet of the vibration friction device through the mixer, and the discharge port of the vibration friction device is connected with the feed port of the drum electric separator. 2. the operating method of the incineration fly ash triboelectric separation treatment equipment according to claim 1, is characterized as follows: The domestic waste first enters the fluidized bed furnace for incineration, and the bottom ash after incineration is discharged from the discharge port at the bottom of the grate furnace. The flue gas generated by the incineration is deacidified by the semi-dry absorption tower, and the activated carbon injector sprays activated carbon powder to absorb the flue gas. The dioxins in the dioxin, the activated carbon powder that adsorbs dioxins and the fly ash are mixed together, enter the bag filter to become the bag fly ash, and the flue gas passing through the bag filter is discharged from the chimney through the induced draft fan; The incineration fly ash collected by the bag filter is sent to the mixer, where it is fully mixed with the modifier and the modifier, and then sent to the vibrating friction device, and the charged fly ash after frictional charging enters the drum electric separator. Electro-separation is carried out to obtain carbon-rich fine ash, intermediate products and tail ash after separation. The intermediate product is sent back to the electric separator for electrical separation again, and finally carbon-rich fine ash and tail ash are obtained; The enriched fine ash is sent to the waste raw material of the incinerator as a fuel for combustion; The tail ash is treated by electrodialysis to obtain residual ash, waste liquid and heavy metal concentrate. The residual ash is sent to the domestic waste landfill for direct landfill disposal. The heavy metal concentrate can be subsequently used to recover heavy metals such as Pb and Zn through hydrometallurgy.

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