Method for reducing and solidifying chlorine escape in household garbage derived fuel

Abstract

The invention discloses a method for reducing and solidifying chlorine escape in household garbage derived fuel, which comprises the following steps: S1, screening to remove inorganic matters in household garbage, drying, and controlling the water content of the household garbage to be 2-25%; and S2, the dried household garbage is smashed, and the smashed particle size of the household garbage is controlled to range from 0.1 mm to 0.8 mm. And S3, adding a chlorine fixing agent into the crushed household garbage, and uniformly stirring and mixing. And S4, the household garbage and the chlorine fixing agent which are stirred and mixed uniformly are pressed, and the garbage derived fuel is obtained. The chlorine-containing harmful waste generated during combustion of the household garbage derived fuel is controlled by controlling the water content and adding the chlorine fixing agent. A gas-phase reaction path for generating polychlorinated dibenzo-p-dioxin and similar substances and precursors thereof from chlorine sources and organic components in the garbage in a high-temperature environment is inhibited, the chlorine sources in low-temperature flue gas are reduced, and the fixation of chlorine in the garbage derived fuel is realized.

Description

Technical Field

[0001] The invention relates to the field of garbage disposal, in particular to a method for reducing and solidifying chlorine escape in domestic garbage derived fuel. Background Art

[0002] With economic development and improvement of residents' living standards, the per capita amount of garbage generated in urban areas will also increase accordingly.

[0003] For a long time, the treatment of urban domestic waste has mainly been to find suitable places for landfill (accounting for about 80%), followed by high-temperature composting (accounting for about 15%), and incineration is less common (accounting for about 5%). In recent years, with people's increasing attention to resources and ecological environment, garbage production energy and recycling technologies derived from changes in the composition of domestic waste have developed rapidly. At present, a kind of waste-derived fuel (RDF) production technology has emerged at home and abroad. The so-called waste-derived fuel refers to the removal of non-combustible materials such as metals, glass, sand and soil from the garbage, and the crushing and drying of the combustible materials in the garbage (such as plastics, fibers, rubber, wood, food waste, etc.), adding additives, and compressing into a solid fuel of the desired shape (such as columnar, granular, etc.). Waste-derived fuel can be used as fuel for heating boilers, power generation boilers, and cement kilns. The ash after combustion can be used as an effective component for making cement without landfilling, which provides a better way for the resource utilization and reduction of waste.

[0004] Studies have shown that domestic waste contains a certain amount of chlorine, and the total chlorine content of each component (dry basis) is 1.52-19.44 mg / g. Among them, the chlorine content of kitchen waste components is the highest, at 8.38-19.44 mg / g. The inorganic chlorine content in the chlorine of kitchen waste components accounts for more than 90%, and the organic chlorine content in the chlorine of rubber and plastic components accounts for 46%-55%. At present, the fuelization of domestic waste, that is, the resource utilization and reduction of domestic waste through combustion production of energy, has become the main development path for domestic waste treatment. However, studies have shown that the chlorine contained in the garbage during incineration is basically released in the form of HCl, which will directly corrode human skin, respiratory tract, building decoration materials and industrial equipment, seriously affecting human health, construction and industrial equipment and other equipment life. At the same time, the overflowed HCl is also one of the important prerequisites for the formation of dioxin, known as the "poison of the century", during the combustion process. The toxicity of the dioxin formed is equivalent to 1,000 times that of potassium cyanide (KCN). The International Agency for Research on Cancer has listed it as a Class I carcinogen to humans.

[0005] Therefore, there is a need for a method for controlling and fixing the escape of chlorine produced during the incineration of refuse-derived fuels to reduce chlorine emissions and promote the fuelization of domestic waste. Summary of the invention

[0006] The object of the present invention is to provide a method for reducing and solidifying chlorine escape from domestic waste-derived fuels, so as to fix the chlorine escaped from the combustion of the domestic waste-derived fuels and reduce chlorine emissions.

[0007] In order to solve the above technical problems, the present invention provides a method for reducing and solidifying chlorine escape in domestic waste-derived fuel, comprising:

[0008] S1: Screen and remove inorganic matter from domestic waste, and dry it to control the moisture content of domestic waste between 2% and 25%.

[0009] S2: Crush the dried domestic waste and control the particle size of the crushed domestic waste to be 0.1mm-0.8mm.

[0010] S3: Add chlorine fixative to the crushed domestic waste and stir to mix well.

[0011] S4: Compressing the mixed domestic waste and chlorine fixative to obtain waste-derived fuel.

[0012] Furthermore, the chlorine fixing agent comprises, by mass percentage:

[0013] Steel slag 30%-45%;

[0014] Fly ash 15%-25%;

[0015] Phosphogypsum 25%-35%;

[0016] Red mud 10%-15%.

[0017] Furthermore, the preparation method of the chlorine fixing agent comprises:

[0018] Take steel slag, fly ash, phosphogypsum and red mud of the same mesh size, and weigh and mix them according to the mass percentage.

[0019] The weighed steel slag, fly ash, phosphogypsum and red mud are stirred and mixed to obtain a chlorine fixing agent.

[0020] Furthermore, the mesh size of the steel slag, fly ash, phosphogypsum and red mud is 200-400 mesh.

[0021] Furthermore, the mixing mass ratio of the crushed domestic waste to the chlorine fixing agent is (9-99):1.

[0022] Furthermore, the inorganic matter includes at least metal, glass and sand and gravel, and the inorganic matter is removed by magnetic separation and screening.

[0023] Furthermore, the waste-derived fuel is compacted by a powder tabletting machine.

[0024] Furthermore, the pressing pressure of the powder tablet press is 4MPa-6MPa.

[0025] Furthermore, the water content of the refuse derived fuel is 2%-25%.

[0026] Furthermore, the waste derived fuel is a cylindrical particle structure.

[0027] Compared with the prior art, the present invention has at least the following beneficial effects:

[0028] The present invention controls the generation of chlorine-containing hazardous wastes during the combustion of domestic waste-derived fuels by controlling the water content and adding a chlorine fixing agent. The gas phase reaction pathway of the chlorine source and organic components in the waste to generate polychlorinated dibenzo-p-dioxins and their analogs and their precursors under high temperature environment is suppressed. The chlorine source in low-temperature flue gas is reduced, and the generation mechanism of low-temperature solid-phase fly ash reaction of polychlorinated dibenzo-p-dioxins and their analogs is suppressed.

[0029] Furthermore, the present invention only needs to mix a chlorine fixing agent into the domestic waste-derived fuel, and can achieve effective control of chloride without changing the main structure of the existing incineration system, thereby simplifying the tail gas treatment process after waste incineration. Compared with flue gas dechlorination technology, it avoids huge equipment investment and operating costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 A flow chart of a method for reducing and solidifying chlorine escape in domestic waste-derived fuels according to the present invention;

[0031] Figure 2 It is a schematic diagram of the structure of the garbage derived fuel combustion and gas collection device of the present invention. DETAILED DESCRIPTION

[0032] The following is a more detailed description of the method for reducing and solidifying chlorine release in a domestic waste-derived fuel of the present invention in conjunction with a schematic diagram, wherein a preferred embodiment of the present invention is shown, and it should be understood that those skilled in the art can modify the present invention described herein while still achieving the beneficial effects of the present invention. Therefore, the following description should be understood as being widely known to those skilled in the art and not as a limitation of the present invention.

[0033] The present invention is described in more detail in the following paragraphs by way of example with reference to the accompanying drawings. The advantages and features of the present invention will become more apparent from the following description. It should be noted that the accompanying drawings are in very simplified form and are not in exact proportions, and are only used to facilitate and clearly assist in illustrating the purpose of the embodiments of the present invention.

[0034] Embodiment 1:

[0035] like Figure 1 As shown, an embodiment of the present invention provides a method for reducing and solidifying chlorine escape in domestic waste-derived fuel, comprising:

[0036] S1: Screen and remove inorganic matter from domestic waste, and dry it to control the moisture content of domestic waste between 2% and 25%.

[0037] S2: Crush the dried domestic waste and control the particle size of the crushed domestic waste to be 0.1mm-0.8mm.

[0038] S3: Add chlorine fixative to the crushed domestic waste and stir to mix well.

[0039] S4: Compressing the mixed domestic waste and chlorine fixative to obtain waste-derived fuel.

[0040] In this embodiment, it is first necessary to sort and remove the non-combustible components in the domestic waste, which mainly include metals, glass, stones and other inorganic substances. Then the water content of the domestic waste should be controlled at 5%. Controlling the water content of the domestic waste is conducive to reducing the subsequent processing difficulty and product effect. The next step is to crush the domestic waste and control its particle size at 0.5mm. Controlling the particle size of the crushed domestic waste is conducive to fully mixing the chlorine fixative and the domestic waste. Then add a certain mass percentage of chlorine fixative to the crushed domestic waste, and finally stir the mixture evenly and press it into waste-derived fuel by extrusion. In order to ensure the sorting quality, the main sorting methods for domestic waste are:

[0041] Furthermore, the inorganic matter includes at least metal, glass and sand and gravel, and the inorganic matter is removed by magnetic separation and screening.

[0042] The garbage is initially screened and magnetically separated to remove the inorganic components, and then a chlorine fixative needs to be prepared.

[0043] Furthermore, the chlorine fixing agent comprises, by mass percentage:

[0044] Steel slag 30%-45%.

[0045] Fly ash 15%-25%.

[0046] Phosphogypsum 25%-35%.

[0047] Red mud 10%-15%.

[0048] In this embodiment, the chlorine fixing agent ratio used is: steel slag accounting for 45% of the total mass after mixing, fly ash accounting for 15% of the total mass after mixing, phosphogypsum accounting for 25% of the total mass after mixing, and red mud accounting for 15% of the total mass after mixing. The chlorine fixing agent is prepared after crushing and mixing.

[0049] Furthermore, the preparation method of the chlorine fixing agent comprises:

[0050] Take steel slag, fly ash, phosphogypsum and red mud of the same mesh size, and weigh and mix them according to the mass percentage.

[0051] The weighed steel slag, fly ash, phosphogypsum and red mud are stirred and mixed to obtain a chlorine fixing agent.

[0052] Furthermore, the mesh size of the steel slag, fly ash, phosphogypsum and red mud is 200-400 mesh.

[0053] In this embodiment, the steel slag, fly ash, phosphogypsum and red mud are all ground into 400-mesh powder by ball milling, and then stirred and evenly mixed by a mixer.

[0054] Specifically, in this case, since the water content of domestic waste is controlled at 5%, in order to ensure the stability of the water content of the mixed RDF, the water content of the chlorine fixative should also be controlled at 5% before mixing with the domestic waste.

[0055] Furthermore, the mixing mass ratio of the crushed domestic waste to the chlorine fixing agent is (9-99):1.

[0056] In this case, the mass ratio of domestic waste to added chlorine fixative is 19:1. The chlorine fixative is added to the mixer first, and then the crushed domestic waste is added to the mixer for mixing. This order is conducive to completely mixing the chlorine fixative and domestic waste, ensuring the quality of the mixed waste-derived fuel.

[0057] Furthermore, the waste-derived fuel is compacted by a powder tabletting machine.

[0058] Furthermore, the pressing pressure of the powder tablet press is 4MPa-6MPa.

[0059] Furthermore, the water content of the refuse derived fuel is 2%-25%.

[0060] Furthermore, the waste derived fuel is a cylindrical particle structure.

[0061] In order to ensure the combustion effect of RDF and facilitate the measurement of post-combustion gas, RDF needs to be pressed into granules so that it can be completely burned during combustion and reduce the error caused by incomplete combustion. Therefore, in this case, the YP-8T infrared powder tablet press of Tianjin Jinfulun Technology Co., Ltd. is used to press RDF. The pressure range of this machine is 0-40MPa. The pressure used during pressing is 5Mpa, and the RDF is pressed into cylindrical particles with a diameter of 15mm, a height of 1cm, a mass control of 1g to 2g, and a water content of 5%.

[0062] The above-mentioned granular waste-derived fuel is burned, and the gas after burning is collected by a combustion and gas collection device to determine the concentration of Cl- ions therein. Then, waste-derived fuel that is directly pressed without adding a chlorine fixative is prepared according to the above method, and the gas after burning is collected to determine the concentration of Cl- ions therein. Finally, the Cl- ion concentrations in the two gases are compared to obtain the reduction ratio of Cl- ions. The method for collecting and determining Cl- ions in the combustion and escaped gas of waste-derived fuel is as follows:

[0063] like Figure 2 As shown, the garbage-derived fuel combustion and gas collection device consists of a garbage-derived fuel burner 1, a condenser 2, a gas collection bottle 3, an air pump 4 and other parts. The garbage-derived fuel burner is a glass hollow cylinder of φ10cm×20cm. There is a circular opening (garbage-derived fuel inlet) 5 in the middle of the container, and the protruding part of the opening can be plugged into a rubber plug 6 for sealing. The lower opening of the container is an air inlet 7. The top opening of the container is connected to the condenser 2, and the condenser 2 is connected to the gas collection bottle 3 through a rubber tube. The gas collection bottle 3 is filled with 0.01mol / L NaOH absorption liquid 8, and the gas collection bottle 3 is connected to the air pump 4. The operation process of the device is: first, the air pump 4 is turned on, and then the rubber plug 6 of the garbage-derived fuel inlet 5 is removed, and the garbage-derived fuel is ignited and sent into the garbage-derived fuel burner 1, and the rubber plug 6 is plugged; the air is continuously pumped for 20 minutes until the garbage-derived fuel stops burning completely, and the absorption liquid 8 obtained is treated and the Cl- ion concentration therein is analyzed by ion chromatography.

[0064] By comparing the chlorine content in the gas collected after the combustion of the refuse-derived fuel prepared in this case with the one without the addition of chlorine fixative, it can be concluded that:

[0065] Under the premise of 5% water content, 95% of 0.5mm size RDF molding raw materials and 5% of 400 mesh chlorine fixative are used, and after uniform mixing, they are pressed under 5-10MPa pressure to form granular RDF with a diameter of 15mm, a height of about 1cm, and a mass of 1-2g. After combustion, the chlorine released is reduced by more than 95% compared with no fixative.

[0066] Example 2

[0067] The mesh size of the chlorine fixative was adjusted to 400 mesh, 300 mesh, and 200 mesh, respectively, and three types of garbage-derived fuels with chlorine fixatives of different mesh sizes were prepared for experiments. The contents of chlorine released in the gas collected after the three types of garbage-derived fuels were burned were compared with the contents of chlorine released in the gas collected after the garbage-derived fuel without the chlorine fixative was burned. The results are shown in the following table:

[0068] Comparison table of chlorine fixative particle size and chlorine reduction percentage after combustion:

[0069] Comparison table of chlorine fixative particle size and chlorine reduction percentage after combustion

[0070]

[0071] As shown in the comparison table of the mesh size of the chlorine fixer and the percentage reduction of chlorine released after combustion, it can be seen from the table that when the mesh size of the chlorine fixer is 400 mesh, the percentage reduction of chlorine released after combustion of the prepared waste-derived fuel (i.e., RDF) is 99.5%, when the mesh size of the chlorine fixer is 300 mesh, the percentage reduction of chlorine released after combustion of the prepared waste-derived fuel is 98.7%, and when the mesh size of the chlorine fixer is 200 mesh, the percentage reduction of chlorine released after combustion of the prepared waste-derived fuel is 97.6%. Therefore, it can be concluded that when the mesh size of the chlorine fixer is 200 mesh, 300 mesh, and 400 mesh, the chlorine fixer of 400 mesh has a higher percentage reduction of chlorine released and a better fixation effect on chlorine. In the mesh size range of 200 mesh to 400 mesh, the effect of the chlorine fixer increases with the increase of the mesh size.

[0072] Embodiment 3:

[0073] The water content of the RDF was adjusted to 2%, 5%, 7%, 10%, 15% and 25%, respectively. The above process was repeated to prepare RDF of different specifications for experiments. The chlorine content in the gas collected after the RDF of different specifications was burned was compared with the chlorine content in the gas collected after the RDF of the same water content but without adding chlorine fixative. The comparison table of the water content of RDF and the reduction percentage of chlorine after combustion is shown below:

[0074] Comparison table of moisture content of refuse-derived fuel and reduction percentage of chlorine released after combustion Comparison table of moisture content of refuse-derived fuel and reduction percentage of chlorine released after combustion

[0075]

[0076] According to the data in the comparison table of the moisture content of RDF and the percentage reduction of chlorine emission after combustion, it can be concluded that when the moisture content of RDF is ≤10%, when the RDF with chlorine fixative added is burned, the chlorine emission is reduced by more than 95.0% compared with the RDF without chlorine fixative added. At this time, it can be considered that the Cl- ions after the combustion of RDF are basically fixed in the ash, and it can be seen that the optimal moisture content of RDF with the addition of chlorine fixative should be controlled within 10%. As the moisture content of RDF increases from 2% to 25%, the percentage reduction of chlorine emission after the combustion of RDF with chlorine fixative added also decreases, indicating that the fixing effect on chlorine emission decreases with the increase of moisture content in RDF.

[0077] Embodiment 4:

[0078] The particle sizes of crushed domestic waste were adjusted to 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm and 0.8mm respectively, and the above process was repeated to prepare different specifications of RDF for experiments. The chlorine content in the gas collected after the combustion of RDF of different specifications was compared with the chlorine content in the gas collected after the combustion of RDF without adding chlorine fixative. The comparison table of domestic waste particle size and chlorine reduction percentage after combustion is as follows:

[0079] Comparison table of particle size of domestic waste and reduction percentage of chlorine released after combustion

[0080]

[0081] From the comparison table of the particle size of domestic waste and the percentage reduction of chlorine released after combustion, it can be seen that when the particle size of domestic waste is controlled between 0.2 mm and 0.5 mm during the preparation of RDF, the chlorine released after combustion of the prepared RDF is reduced by more than 95.0% compared with the RDF without chlorine fixative added. However, the chlorine released after combustion of the RDF prepared when the particle size of domestic waste is 0.1 mm, 0.6 mm, and 0.8 mm is reduced by less than 95.0% compared with the RDF without chlorine fixative added. Therefore, it is shown that when preparing RDF materials, controlling the particle size of domestic waste to be between 0.2 mm and 0.5 mm can improve the fixation effect of chlorine.

[0082] Embodiment 5:

[0083] The mass ratio of the chlorine fixative added during the preparation of the RDF was adjusted to be controlled at 1%, 2%, 3%, 4%, 5%, 6%, 7% and 10% of the total mass after mixing, respectively. The above process was repeated to prepare RDFs of different specifications for experiments. The chlorine content in the gas collected after the combustion of RDFs of different specifications was compared with the chlorine content in the gas collected after the combustion of RDFs without the chlorine fixative added. The comparison table of the chlorine fixative addition ratio and the chlorine reduction percentage after combustion is shown below:

[0084] Comparison table of chlorine fixative addition ratio and chlorine reduction percentage after combustion

[0085]

[0086] As shown in the above table, it can be known from the data in the table that: when the content of the chlorine fixative added during preparation accounts for 2% to 6% of the total mass of the RDF, after the RDF is burned, the chlorine released is reduced by more than 95.0% compared with the RDF without the addition of the chlorine fixative, and the fixation effect of chlorine is better. When the content of the chlorine fixative accounts for 1%, 7%, and 10% of the total mass of the RDF, the chlorine released is reduced by less than 95.0% compared with the RDF without the addition of the chlorine fixative, and is 87.3%, 91.2%, and 83.6% respectively, and the fixation effect of chlorine is poor at this time. In the range of 2% to 6% of the total mass of the RDF, the best addition amount for the fixation effect of chlorine is 5% and 6%. Therefore, the RDF prepared by controlling the addition amount of the chlorine fixative to about 5% of the total mass of the RDF has a better fixation effect on chlorine after combustion.

[0087] Compared with the prior art, the present invention has at least the following beneficial effects:

[0088] The present invention controls the chlorine-containing hazardous waste generated by the combustion of domestic waste-derived fuel by controlling the water content and adding a chlorine fixing agent. The gas phase reaction pathway of the chlorine source and organic components in the waste to generate polychlorinated dibenzo-p-dioxins and their analogs and their precursors under high temperature environment is suppressed. The chlorine source in the low-temperature flue gas is reduced, and the generation mechanism of the low-temperature solid-phase fly ash reaction of polychlorinated dibenzo-p-dioxins and their analogs is suppressed.

[0089] At the same time, because only the chlorine fixative needs to be mixed into the domestic waste-derived fuel, effective control of chloride can be achieved without changing the main structure of the existing incineration system, simplifying the tail gas treatment process after waste incineration. Compared with flue gas dechlorination technology, it avoids huge equipment investment and operating costs.

[0090] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for reducing and solidifying chlorine release from domestic waste-derived fuels, characterized in that: include: S1: Screen and remove inorganic matter from domestic waste, and dry it to control the moisture content of domestic waste between 2% and 25%; S2: crushing the dried domestic waste and controlling the particle size of the domestic waste to be 0.1mm-0.8mm; S3: adding chlorine fixative to the crushed domestic waste and stirring to mix well; S4: Compressing the mixed domestic waste and chlorine fixative to obtain waste-derived fuel.

2. The method for reducing and solidifying chlorine release in domestic waste-derived fuel as claimed in claim 1, characterized in that: The chlorine fixing agent comprises, by mass percentage: Steel slag 30%-45%; Fly ash 15%-25%; Phosphogypsum 25%-35%; Red mud 10%-15%.

3. The method for reducing and solidifying chlorine release in domestic waste-derived fuel as claimed in claim 2, characterized in that: The preparation method of the chlorine fixing agent comprises: Take steel slag, fly ash, phosphogypsum and red mud of the same mesh size, and weigh and mix them according to the mass percentage; The weighed steel slag, fly ash, phosphogypsum and red mud are stirred and mixed to obtain a chlorine fixing agent.

4. The method for reducing and solidifying chlorine release in domestic waste-derived fuel as claimed in claim 3, characterized in that: The mesh size of the steel slag, fly ash, phosphogypsum and red mud is 200-400 mesh.

5. The domestic waste derived fuel as claimed in claim 1, characterized in that: The mixing mass ratio of the crushed domestic waste to the chlorine fixing agent is (9-99):

1.

6. The method for reducing and solidifying chlorine release in domestic waste-derived fuel as claimed in claim 1, characterized in that: The inorganic matter at least includes metal, glass and sand and gravel, and the inorganic matter is removed by magnetic separation and screening.

7. The method for reducing and solidifying chlorine release in domestic waste-derived fuel as claimed in claim 1, characterized in that: The waste-derived fuel is pressed and formed by a powder tabletting machine.

8. The method for reducing and solidifying chlorine release in domestic waste-derived fuel as claimed in claim 7, characterized in that: The pressing pressure of the powder tablet press is 4MPa-6MPa.

9. The method for reducing and solidifying chlorine spillage of domestic waste-derived fuel as claimed in claim 7, characterized in that: The water content of the refuse derived fuel is 2%-25%.

10. The method for reducing and solidifying chlorine release in domestic waste-derived fuel as claimed in claim 1, characterized in that: The refuse derived fuel is in a cylindrical particle structure.

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