阅读说明：本技术 一种电弧炉处理废弃物污染物减排方法和系统 (Emission reduction method and system for treating waste pollutants by electric arc furnace ) 是由 周涛 董茂林 于 2020-05-28 设计创作，主要内容包括：本发明属于废物处理技术领域,具体公开了一种电弧炉处理废弃物污染物减排方法和系统。本方法包括如下步骤：根据烟气预热温度,将废钢预热通道划分为高温区、中温区和低温区；废钢冶炼开始后,达到指定温度时,将生石灰粉和废旧橡胶混合后加入到高温区,将生石灰粉和废弃塑料混合后加入到中温区和/或低温区,进行燃烧；从废钢预热通道出来的烟气进入烟气混合装置与电弧炉出来的高温烟气进行混合,并加入空气或氧气形成混合烟气,使废弃物燃烧分解的气态产物充分燃烧；最后清除灰渣。本发明能有效利用烟气中的余热,显著减少污染物的排放量,节约烟气治理成本,并在不增设烟气脱硫脱硝装置的条件下,达到国家排放标准。(The invention belongs to the technical field of waste treatment, and particularly discloses an emission reduction method and system for treating waste pollutants by an electric arc furnace. The method comprises the following steps: dividing a scrap preheating channel into a high-temperature area, a medium-temperature area and a low-temperature area according to the flue gas preheating temperature; after the smelting of the scrap steel is started and the specified temperature is reached, mixing quicklime powder and waste rubber, adding the mixture into a high-temperature area, mixing the quicklime powder and waste plastic, adding the mixture into a medium-temperature area and/or a low-temperature area, and burning; the flue gas from the scrap steel preheating channel enters a flue gas mixing device to be mixed with the high-temperature flue gas from the electric arc furnace, and air or oxygen is added to form mixed flue gas, so that gaseous products generated by burning and decomposing the waste are fully combusted; and finally, removing ash. The invention can effectively utilize the waste heat in the flue gas, remarkably reduce the discharge amount of pollutants, save the flue gas treatment cost, and reach the national discharge standard under the condition of not additionally arranging a flue gas desulfurization and denitrification device.)

1. An electric arc furnace waste pollutant treatment emission reduction method is characterized by comprising the following steps: according to the flue gas preheating temperature, dividing a scrap steel preheating channel into a high-temperature area, a medium-temperature area and a low-temperature area in sequence; after smelting of the scrap steel is started, when the temperature of each area of a scrap steel preheating channel reaches a specified temperature, mixing quicklime powder and waste rubber, adding the mixture into a high-temperature area, mixing the quicklime powder and waste plastic, adding the mixture into a medium-temperature area and/or a low-temperature area, and burning; the flue gas from the scrap steel preheating channel enters a flue gas mixing device to be mixed with the high-temperature flue gas from the electric arc furnace, and air or oxygen is added to form mixed flue gas, so that gaseous products generated by burning and decomposing the waste are fully combusted; and finally, removing the residual ash after the waste is burnt out.

2. The method of claim 1, wherein: the high-temperature area refers to an area with the smoke temperature of more than 1000 ℃ in the waste steel preheating channel, the medium-temperature area refers to an area with the smoke temperature of 700-1000 ℃ in the waste steel preheating channel, and the low-temperature area refers to an area with the smoke temperature of less than 700 ℃ in the waste steel preheating channel.

3. The method of claim 1, wherein: the total amount of waste added into the scrap steel preheating channel is 10-15 kg per ton of steel.

4. The method of claim 1, wherein: the mixing ratio of the quicklime powder to the waste rubber is 1: 3-5, and the ratio of the quicklime powder to the waste plastic is 1: 5-8.

5. The method of claim 1, wherein: the waste rubber and the waste plastic are used after being crushed, the mass of the crushed fragments of the waste rubber is not more than 10g, and the mass of the crushed fragments of the waste plastic is not more than 40 g.

6. The method of claim 1, wherein: the oxygen content in the mixed flue gas is kept at 10% or above; and/or the temperature of the mixed flue gas is not lower than 850 ℃.

7. The method of claim 1, wherein: the method further comprises the steps of: and quicklime powder is sprayed into a flue gas outlet of the scrap steel preheating channel and/or an outlet of the flue gas mixing device.

8. An electric arc furnace system for waste pollutant abatement treatment according to the method of any one of claims 1 to 7, wherein: the system comprises an electric arc furnace, a scrap steel preheating device, a waste feeding and batching device, a flue gas mixing device and a heat supplementing device; the scrap steel preheating device comprises a scrap steel preheating channel, one end of the scrap steel preheating channel is communicated with the electric arc furnace, the scrap steel preheating channel is sequentially divided into a high-temperature area, a medium-temperature area and a low-temperature area from one end close to the furnace mouth of the electric arc furnace according to the flue gas preheating temperature, and the high-temperature area, the medium-temperature area and the low-temperature area are respectively provided with a charging hole; the waste feeding and batching device comprises a weighing mechanism, a batching mechanism and a feeding mechanism, wherein the feeding mechanism is connected with a feeding port; the scrap steel preheating channel is provided with a flue gas outlet which is communicated with a flue gas mixing device, the electric arc furnace is provided with a bypass channel for discharging high-temperature flue gas, and the bypass channel is communicated with the flue gas mixing device; the scrap steel preheating channel is connected with a heat supplementing device, and the heat supplementing device is used for heating the interior of the scrap steel preheating channel.

9. The method of claim 8, wherein: and the bypass channel is provided with an air mixing valve used for adding air or oxygen into the flue gas mixing device.

10. The method of claim 8, wherein: the system also comprises an ash discharging device, the scrap steel preheating channel is provided with an ash outlet, and the ash outlet is communicated with the ash discharging device;

and/or the system further comprises a waste storage device, wherein the waste storage device is communicated with the waste feeding and batching device and is used for providing the stored waste and quicklime powder to the waste feeding and batching device.

Technical Field

The invention relates to the technical field of metallurgy and waste recovery treatment, in particular to an electric arc furnace waste pollutant treatment emission reduction method and system.

Background

At present, the waste tires and the waste plastic products are recycled in a small proportion, and most of the waste tires and the waste plastic products are buried or incinerated. As a result of investigations, only 60% of the tires are stored in a stack and more than 10% of the tires are illegally dumped in the disposal of used tires. Due to the special component characteristics of the tire, substances harmful to the environment can be decomposed after long-term storage, and the environment is seriously polluted; moreover, fire accidents are easily caused by randomly piling up tires.

In the steel-making process of the electric arc furnace, the chemical energy accounts for 35-40% of total energy consumption, and the chemical energy is mainly the result of carbon-oxygen reaction generated by oxygen blowing. Electric furnaces are expected to continue to grow by reducing the consumption of fossil energy sources such as coal and natural gas, wherein one of the methods for reducing the consumption of coal is to use potential alternative fuels, i.e., waste materials generated by a recycling process, rubber tires and waste plastic products are alternatives to coal.

The electric steel accounts for 30% of the total amount of iron and steel in the world, and the proportion of the electric steel is continuously increased in the past 20 years. In the steelmaking process of the electric arc furnace, the electric energy input accounts for 60-65% of the total energy, and the chemical energy accounts for 35-40%. The chemical energy is mainly the result of the reaction of blowing oxygen to produce carbon and oxygen. One of the methods for realizing sustainable development of electric arc furnaces and reducing the consumption of fossil energy such as coal and natural gas is to use potential alternative fuels, namely, waste materials generated in a recycling process are used, rubber tires and waste plastic products are substitutes of coal, and the waste materials are not only excellent substitutes for electric arc furnace steelmaking, but also can solve the problem of environmental protection. However, when carbon powder is replaced by high molecular polymer such as waste tires, SO in flue gas can be generated₂、NO_xAnd pollutants such as dioxin and the like exceed standards. Therefore, how to control the emission of the smoke pollutants and effectively utilize the waste heat in the smoke becomes a main problem of the electric furnace smoke treatment technology based on the waste tires.

Disclosure of Invention

In view of the defects of the prior art, the invention aims to provide the method and the system for reducing the emission of the pollutants in the waste treated by the electric arc furnace, and the method and the system for reducing the emission of the pollutants in the waste treated by the electric arc furnace are characterized in that the emission of the organisms is reduced from the source by selecting a proper additive through a high-temperature treatment technology of the waste, so that the problem of emission of the pollutants generated by the waste treated by the electric arc furnace is fundamentally improved and solved, the waste.

To achieve the above and other related objects, a first aspect of the present invention provides an emission reduction method for treating waste pollutants by an electric arc furnace, comprising the steps of: according to the flue gas preheating temperature, dividing a scrap steel preheating channel into a high-temperature area, a medium-temperature area and a low-temperature area in sequence; after smelting of the scrap steel is started, when the temperature of each area of a scrap steel preheating channel reaches a specified temperature, mixing quicklime powder and waste rubber, adding the mixture into a high-temperature area, mixing the quicklime powder and waste plastic, adding the mixture into a medium-temperature area and/or a low-temperature area, and burning; the flue gas from the scrap steel preheating channel enters a flue gas mixing device to be mixed with the high-temperature flue gas from the electric arc furnace, and air or oxygen is added to form mixed flue gas, so that gaseous products generated by burning and decomposing the waste are fully combusted; and finally, removing the residual ash after the waste is burnt out. Further, the high-temperature region refers to a region with the flue gas temperature of more than 1000 ℃ in the scrap steel preheating channel, the medium-temperature region refers to a region with the flue gas temperature of 700-1000 ℃ in the scrap steel preheating channel, and the low-temperature region refers to a region with the flue gas temperature of less than 700 ℃ in the scrap steel preheating channel.

Furthermore, the total amount of the waste added into the scrap steel preheating channel is 10-15 kg/ton steel. That is to say, the total amount of the processed waste is 10-15 kg per ton of steel smelted by the electric arc furnace, so that the flue gas waste heat generated by the steel smelting of the electric arc furnace can be fully and reasonably utilized while the waste is ensured to be fully combusted.

Further, the mixing ratio of the quicklime powder to the waste rubber is 1: 3-5, and the ratio of the quicklime powder to the waste plastic is 1: 5-8. Further, the waste rubber and the waste plastic are used after being crushed, the mass of the crushed fragments of the waste rubber is not more than 10g, and the mass of the crushed fragments of the waste plastic is not more than 40 g.

Further, the oxygen content in the mixed flue gas is kept at 10% or above.

Further, the temperature of the mixed flue gas is not lower than 850 ℃.

Further, the method comprises the following steps: quicklime powder is sprayed into a flue gas outlet of the scrap steel preheating channel and/or an outlet of the flue gas mixing device so as to further reduce the content of pollutants in the flue gas.

Further, when the whole temperature of the scrap steel preheating channel is insufficient, a heat supplementing device is adopted for heating so as to ensure that the working condition of treating the waste is within a reasonable temperature range.

Further, waste rubber, waste plastic and quicklime powder are added to one side of the high-temperature area, the middle-temperature area and the low-temperature area of the waste steel preheating channel, which is close to the waste steel feeding side.

The invention provides an electric arc furnace system for performing waste pollutant emission reduction treatment by adopting the method, which comprises an electric arc furnace, a scrap steel preheating device, a waste feeding and batching device, a flue gas mixing device and a heat supplementing device; the scrap steel preheating device comprises a scrap steel preheating channel, one end of the scrap steel preheating channel is communicated with the electric arc furnace, the scrap steel preheating channel is sequentially divided into a high-temperature area, a medium-temperature area and a low-temperature area from one end close to the furnace mouth of the electric arc furnace according to the flue gas preheating temperature, and the high-temperature area, the medium-temperature area and the low-temperature area are respectively provided with a charging hole; the waste feeding and batching device comprises a weighing mechanism, a batching mechanism and a feeding mechanism, wherein the feeding mechanism is connected with a feeding port; the scrap steel preheating channel is provided with a flue gas outlet which is communicated with a flue gas mixing device, the electric arc furnace is provided with a bypass channel for discharging high-temperature flue gas, and the bypass channel is communicated with the flue gas mixing device; the scrap steel preheating channel is connected with a heat supplementing device, and the heat supplementing device is used for heating the interior of the scrap steel preheating channel.

Further, the bypass channel is provided with an air mixing valve used for adding air or oxygen into the flue gas mixing device.

Further, the system also comprises an ash discharging device, the scrap steel preheating channel is provided with an ash outlet, and the ash outlet is communicated with the ash discharging device.

Further, the system also comprises a waste storage device, wherein the waste storage device is communicated with the waste feeding and batching device and is used for providing the stored waste and quicklime powder for the waste feeding and batching device.

As mentioned above, the method and the system for reducing emission of waste pollutants by electric arc furnace treatment have the following beneficial effects:

the invention can be applied to the engineering field of treating urban waste by an electric arc furnace, the waste is classified, an optimal feeding mode is adopted, the pollutant generation amount is less, meanwhile, quicklime is added into the waste, the flue gas coming out of a scrap preheating channel enters a flue gas mixing device to be mixed with the high-temperature flue gas coming out of the electric arc furnace, the flue gas temperature in the scrap preheating channel can be improved, the oxygen content is improved by adding air or oxygen, sufficient reaction conditions are provided, and the gaseous products of incomplete combustion generated by waste combustion are completely decomposed, so that the pollutant discharge amount is reduced; meanwhile, the method ensures that the waste is fully combusted by controlling the amount of the waste treated by the electric furnace to be 10-15 kg/ton steel, and simultaneously, the flue gas waste heat generated by the steel making of the electric arc furnace can be fully and reasonably utilized. Therefore, the invention can reach the current national emission standard of smoke pollutants without adding a smoke desulfurization and denitrification device.

The method provided by the invention can be used for treating the waste pollutants by using the electric arc furnace, so that the treatment effect of the urban waste in the waste steel preheating channel can be strongest, the waste heat in the flue gas can be effectively utilized, the discharge amount of the pollutants generated by the urban waste treatment by the waste steel preheating device can be greatly reduced, and the flue gas treatment cost can be saved.

Drawings

FIG. 1 shows a flow chart of an electric arc furnace waste abatement method of the present invention.

Detailed Description

The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention.

As shown in fig. 1, the invention provides an electric arc furnace waste treatment emission reduction method and an electric arc furnace system for performing waste pollutant emission reduction treatment by using the method, wherein the system comprises an electric arc furnace, a scrap steel preheating device, a waste storage device, a waste feeding and batching device, a flue gas mixing device, a heat supplementing device and an ash discharging device; the scrap steel preheating device comprises a scrap steel preheating channel, one end of the scrap steel preheating channel is communicated with the electric arc furnace, the scrap steel preheating channel is sequentially divided into a high-temperature area, a medium-temperature area and a low-temperature area from one end close to the furnace mouth of the electric arc furnace according to the flue gas preheating temperature, and the high-temperature area, the medium-temperature area and the low-temperature area are respectively provided with a charging opening; the waste feeding and batching device comprises a weighing mechanism, a batching mechanism and a feeding mechanism, wherein the feeding mechanism is connected with a feeding port; the waste storage device is communicated with the waste feeding and batching device and is used for providing the stored waste and quicklime powder to the waste feeding and batching device; the scrap steel preheating channel is provided with a flue gas outlet which is communicated with the flue gas mixing device, the electric arc furnace is provided with a bypass channel for discharging high-temperature flue gas, the bypass channel is communicated with the flue gas mixing device, the bypass channel is also provided with an air mixing valve for adding air or oxygen into the flue gas mixing device, and the flue gas mixing device is provided with an outlet for discharging the flue gas; the scrap steel preheating channel is connected with a heat supplementing device, and the heat supplementing device is used for heating the interior of the scrap steel preheating channel; the scrap steel preheating channel is provided with an ash outlet which is communicated with an ash discharging device.

The method comprises the following specific steps:

(1) dividing the scrap steel preheating channel into a high-temperature area, a medium-temperature area and a low-temperature area according to the flue gas preheating temperature, wherein the high-temperature area is an area with the flue gas temperature of more than 1000 ℃ in the scrap steel preheating channel, the medium-temperature area is an area with the flue gas temperature of 700-plus-1000 ℃ in the scrap steel preheating channel, and the low-temperature area is an area with the flue gas temperature of less than 700 ℃ in the scrap steel preheating channel;

(2) the method comprises the following steps of respectively placing quicklime powder, waste rubber and waste plastic into a waste material storage device, then sending the materials into a waste material feeding and batching device, weighing a certain amount of quicklime powder, waste rubber and waste plastic by a weighing mechanism, uniformly mixing the materials by a batching mechanism, and finally adding the materials into a waste steel preheating channel by a feeding mechanism;

(3) after smelting of the scrap steel is started, when the temperature of each area of a scrap steel preheating channel reaches a specified temperature, mixing quicklime powder and waste rubber, adding the mixture into a high-temperature area, mixing the quicklime powder and waste plastic, adding the mixture into a medium-temperature area and/or a low-temperature area, and burning; wherein the mixing ratio of the quicklime powder to the waste rubber is 1: 3-5, and the ratio of the quicklime powder to the waste plastic is 1: 5-8; the total amount of the waste added into the scrap steel preheating channel is 10-15 kg per ton of steel, namely the total amount of the waste treated by the electric arc furnace is 10-15 kg per ton of steel, so that the flue gas waste heat generated by the electric arc furnace steel making can be fully and reasonably utilized while the waste is ensured to be fully combusted. The method classifies the wastes, enables the wastes of different types to burn in a region with proper temperature by optimizing the adding mode, reduces gaseous products generated by incomplete combustion of the wastes and controls the emission of the pollutants; because the waste plastics in the waste belong to flammable materials, the waste plastics can be added into a low-temperature area or a medium-temperature area, and the waste tires are more resistant to high temperature and are added into a high-temperature area. (4) The flue gas from the scrap steel preheating channel enters a flue gas mixing device to be mixed with the high-temperature flue gas from the fourth hole bypass channel of the electric arc furnace, so that the flue gas temperature of the scrap steel preheating channel is increased, a certain amount of air or oxygen is added to form mixed flue gas, the oxygen content in the mixed flue gas is kept to be more than 10%, and gaseous products generated by combustion and decomposition of wastes are fully combusted in the flue gas mixing device; the highest flue gas temperature of the mixed flue gas is controlled to be not lower than 850 ℃.

(5) In the process, quicklime powder can be sprayed into the flue gas outlet of the scrap steel preheating channel and/or the outlet of the flue gas mixing device, so that the content of pollutants in the flue gas is further reduced.

(6) And finally, removing the residual ash after the waste is burnt out through an ash discharging device arranged at an ash outlet of the steel preheating channel.

When the whole temperature of the scrap steel preheating channel is insufficient, the temperature is raised by adopting the heat supplementing device so as to ensure that the working condition of treating the waste is within a reasonable temperature range.

Combustible and volatile materials in the waste, such as waste plastics and the like, can be fed through the low-temperature area.

The waste rubber can be automobile waste plastics, such as waste tires, automobile seats, bumpers and the like, and rubber products such as waste belts and the like, but is not limited to the above.

The scrap preheating apparatus is similar in construction to the electric arc furnace scrap preheating apparatus mentioned in application No. CN 110173976 a.

The following is a detailed description of specific examples, but the specific application examples of the present invention are not limited thereto.

In a 120t electric arc furnace, the length of a scrap preheating channel is 20 meters, and in the smelting process, the length of each temperature interval on the scrap preheating channel is measured by a thermocouple and is divided into a high-temperature area, a medium-temperature area and a low-temperature area. From the furnace mouth to the scrap feeding direction, 0 to 8 meters is a high-temperature area, 9 to 14 meters is a medium-temperature area, and 15 to 20 meters is a low-temperature area. When the whole temperature of the scrap steel preheating channel is not enough, a heat supplementing device can be adopted for heating, and the working condition of treating wastes is ensured to be within a reasonable temperature range.

The waste rubber and the quicklime powder are fully mixed by the batching mechanism according to the mass ratio of about 3:1, the waste plastic and the quicklime powder are fully mixed by the mass ratio of about 8:1, and the waste plastic and the quicklime powder are respectively added to one side, close to waste steel feeding, of a high-temperature area, a middle-temperature area and a low-temperature area of a waste steel preheating channel by the feeding mechanism to be combusted. The total amount of waste added to the scrap preheating channel was 12 kg/ton steel.

The flue gas that comes out from scrap preheating channel gets into flue gas mixing arrangement and mixes with the high temperature flue gas that the electric arc furnace fourth hole bypass channel came out, is provided with the air mixing valve on the bypass channel, through mixing partial air, forms mixed flue gas, guarantees that the oxygen content of mixed flue gas is not less than 14% to guarantee that mixed flue gas temperature is not less than 850 ℃, in order to guarantee that the scrap preheats incomplete combustion material that exists in the channel, such as carbon black, hydrogen chloride, aromatic hydrocarbon class material and VOC class material, can the complete combustion decomposition.

In the process, quicklime powder can be sprayed into the flue gas outlet of the scrap steel preheating channel and/or the outlet of the flue gas mixing device, so that the content of pollutants in the flue gas is further reduced.

And finally, removing the residual ash after the waste is burnt out through an ash discharging device arranged at an ash outlet of the steel preheating channel.

According to the regulation of DB 132169-2018' ultralow emission standard of atmospheric pollutants for iron and steel industry in Hebei province, SO is generated in the steel-making process₂Emission limit is 50mg/m³，NO_xEmission limit 150mg/m³。

The determination of the waste sulfur dioxide and nitrogen oxides of the fixed pollution source can be continuously monitored by a non-dispersive infrared absorption method. The emission concentration of the electric furnace flue gas pollutants was measured on a 50t electric furnace before and after the implementation of the waste pollutant emission reduction method proposed by the present invention, and the results are shown in table 1.

TABLE 1

Therefore, by adopting the method provided by the invention and utilizing the electric arc furnace to treat the waste pollutants, the treatment effect of the urban waste in the waste steel preheating channel can be strongest, the waste heat in the flue gas can be effectively utilized, the discharge amount of the pollutants generated by the urban waste treatment by the waste steel preheating device can be greatly reduced, and the flue gas treatment cost can be saved.

In conclusion, the invention can be applied to the engineering field of treating urban waste by an electric arc furnace, the waste is classified, an optimal feeding mode is adopted, the pollutant generation amount is less, meanwhile, the quicklime is added into the waste, the flue gas from the waste steel preheating channel enters the flue gas mixing device to be mixed with the high-temperature flue gas from the electric arc furnace, the flue gas temperature in the waste steel preheating channel can be increased, the oxygen content is increased by adding air or oxygen, sufficient reaction conditions are provided, and the gaseous products of incomplete combustion generated by waste combustion are completely decomposed, so that the pollutant discharge amount is reduced; meanwhile, the method ensures that the waste is fully combusted by controlling the amount of the waste treated by the electric furnace to be 10-15 kg/ton steel, and simultaneously, the flue gas waste heat generated by the steel making of the electric arc furnace can be fully and reasonably utilized. Therefore, the invention can reach the current national emission standard of smoke pollutants without adding a smoke desulfurization and denitrification device.

The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.