KR102014980B1 - A manufacturing method for solid refuse fuel comprising wastewater sludge - Google Patents

Abstract

Since the method for producing a solid fuel of the present invention includes 30 to 50% by weight of sewage sludge on a solid basis, the excess sewage sludge can be recycled in a large amount, and a mixed slurry obtained by mixing biomass and waste oil in advance is used as it is. Alternatively, by heating and mixing with the middle water content of sewage sludge, it is possible to reduce the drying cost of the sewage sludge and to provide high efficiency solid fuel. In particular, as biomass, both herbal and wood based biomass can be used, and biomass can be used to further increase the calorific value of solid fuel.

Description

A manufacturing method for solid refuse fuel comprising wastewater sludge}

The present invention relates to a method for producing solid fuel, and to a method for producing solid fuel with high efficiency while recycling sewage sludge.

Solid fuel products are manufactured in a solid state in accordance with the quality standards set by law through the selection of flammable waste, crushing and dry molding. After combustible solid waste such as household waste, waste synthetic resin, waste synthetic fiber, waste rubber, waste tire, waste paper, agricultural waste, waste wood, vegetable residue, herbal waste, etc. After selection and drying process, it is compressed into non-molded form.

The Enforcement Regulations on the Promotion of Saving and Recycling of Resources, as amended on January 31, 2013, included amendments to the types of solid fuel products, and the existing types of solid fuel products (RDF, RPF, WCF, TDF). Are divided into general solid fuel products (Solid Refuse Fuel (SRF)) and bio solid fuel products (Biomass-Solid Refuse Fuel; BIO-SRF). As a result, the scope of raw materials for solid fuel products has expanded significantly.

Sewage sludge, on the other hand, accounts for over 14% of the operating costs of sewage treatment plants. Incineration, landfill and ocean dumping treatment method is required, the treatment technology of sludge has a problem that the development of technology is much slower than the water treatment technology. In addition, the treatment of organic sludge is becoming a very important problem because the construction of sewage treatment plants is increasing due to the increase of population and the development of industry, and the sludge generated along with this is continuously increasing.

In addition, since the organic dumping of organic sludge has been banned since 2012, the amount of organic sludge to be treated on the land has increased significantly, thus causing difficulties in the treatment method.

Korean Patent No. 0700110, "Method for Manufacturing Sewage / Wastewater Sludge and Solid Fuel Using Sludge," and Korean Patent No. 0847247, "Method for Manufacturing Solid Fuel, with Sewage and Wastewater Sludge as Main Material," 70 to 85% by weight of sewage sludge is dried and pulverized to 10% by weight or less of water, and then mixed with an additional caloric aid such as anthracite coal, wood and waste oil to produce a solid fuel product. In order to dehydrate and dry to less than 10% by weight, there is a problem in that facility cost and operation cost are high. In addition, equipment must be periodically cleaned by fly ash generated during crushing. There was a problem that was not very high.

On the other hand, Korean Patent No. 1592737 proposes a method for producing a solid fuel which does not dry sewage sludge but mixes it with moisture content of 70 to 85% by weight of sewage sludge, wood flour and rice husk flour and then hot-air-dried solid fuel. Wood flour and rice husk flour occupy most of the wastewater, and the weight ratio of sewage sludge contained on the basis of solids is 10 to 20% by weight, which is not suitable as a means for treating excess sewage sludge.

In addition, Korean Patent No. 1433141 has a high energy consumption when producing sewage sludge powder by mixing the sewage sludge having a moisture content of 70 to 85% by weight with an excess heat medium oil through secondary pressure drying after primary drying. Recovery of the residual heat medium oil is necessary for the preparation of the product, and the process is complicated by adding water to knead the dried sludge again, and there is a problem of additionally mixing anthracite and the like to increase the calorific value.

Korean Registered Patent No. 0700110 Korean Patent Registration No. 0847247 Korean Registered Patent No. 1592737 Korean Patent No. 1433141

The problem to be solved by the present invention is a high sewage sludge solid content contained in the solid fuel is suitable for the treatment of excess sewage sludge, reducing the drying cost of sewage sludge, providing a method for producing a solid fuel with high efficiency It is.

In order to achieve the above object, the present invention comprises the steps of mixing biomass and waste oil in a weight ratio of 1: 1 to 4: 1 to prepare a mixture of biomass and waste oil; Mixing 200 to 400 parts by weight of sewage sludge having a water content of 30 to 50% by weight to 100 parts by weight of the mixed slurry; And a step of molding the solid fuel while compressing and drying the mixture of the mixed slurry and the sewage sludge into an extrusion molding machine.

According to an embodiment of the present invention, the biomass may be an herbal biomass selected from Kenyaf, rice hulls, corn cobs, rice straw, and cotton swabs, or wood based biomass obtained from wood or by-products thereof.

According to one embodiment of the invention, the biomass has a water content of 10 to 30% by weight, heating the biomass to a superheated steam temperature of 150 to 400 ° C. for 1 to 60 minutes; And heating the biomass heated with the superheated steam at 200 to 350 ° C. under anoxic or low oxygen conditions.

According to one embodiment of the present invention, the mixing slurry further comprises a heating step of heating the mixed slurry to 120 to 240 ℃ before mixing with the sewage sludge having a water content of 30 to 50% by weight, the mixed slurry and sewage In the step of mixing the sludge, the temperature may be maintained at 110 to 220 ° C. for 20 minutes to 3 hours while heating the mixture of the mixed slurry and sewage sludge.

According to one embodiment of the invention, the forming step may be to be compressed and dried by a screw warmed to 130 to 200 ℃ in the extruder.

Since the method for producing a solid fuel of the present invention includes 30 to 50% by weight of sewage sludge on a solid basis, the excess sewage sludge can be recycled in a large amount, and a mixed slurry obtained by mixing biomass and waste oil in advance is used as it is. Alternatively, by heating and mixing with the middle water content of sewage sludge, it is possible to reduce the drying cost of the sewage sludge and to provide high efficiency solid fuel. In particular, as a biomass, both herbal and wood based biomass can be used, and the calorific value of solid fuel can be further increased by utilizing superheated steam treatment and anoxic or low oxygen heated biomass.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

The present invention comprises the steps of mixing the biomass and waste oil in a weight ratio of 1: 1 to 4: 1 to prepare a biomass and waste oil mixed slurry; Mixing 200 to 400 parts by weight of sewage sludge having a water content of 30 to 55% by weight to 100 parts by weight of the mixed slurry; And a step of molding the solid fuel while compressing and drying the mixture of the mixed slurry and the sewage sludge into an extrusion molding machine.

First, biomass and waste oil are mixed at a weight ratio of 1: 1 to 4: 1 to prepare a biomass and waste oil mixed slurry.

Without directly mixing the sewage sludge and the waste oil, the biomass and the waste oil mixed slurry may be prepared first and then mixed with the sewage sludge to suppress separation of the water and oil layers by the biomass solids included in the mixed slurry.

The biomass and the waste oil may be mixed in a weight ratio of 1: 1 to 4: 1, preferably 1.5: 1 to 3: 1. When the waste oil exceeds the upper limit of the mixing ratio, the effect of inhibiting separation of water and oil layers is reduced by the biomass solids, and the waste oil is not sufficiently mixed with the biomass when the biomass exceeds the upper limit of the mixing ratio. The calorific value supplementation of solid fuel may be insufficient, and it may adversely affect physical properties such as molding and hardness of solid fuel.

The biomass is not particularly limited, but may be, for example, an herbal biomass selected from Kenyaf, rice hulls, corn stalks, rice straws, and cotton swabs, or wood-based biomass obtained from wood or by-products thereof.

The moisture content of the biomass may be 0.1 to 15% by weight, preferably 0.5 to 10% by weight, more preferably 1 to 8% by weight of moisture. The biomass is preferably ground to 5 to 30 mm, preferably 10 to 25 mm.

The biomass may be subjected to a semi-carbonization step of heating at 200 to 350 ° C., preferably in anoxic or low oxygen conditions, before mixing with the waste oil. The semi-carbonization step may be performed for 20 minutes to 2 hours, preferably 30 minutes to 1 hour. The semi-carbonized biomass prepared through the above steps has a water content of 1 to 5 wt%, a low calorific value of 4500 to 6000 kcal / kg, a density of 0.75 to 0.85 kg / L, and an energy density of 15 to 20 GJ / m ³ and the surface shows hydrophobicity. When the semi-carbonized biomass is used, the energy density is increased as well as the hydrophobic surface makes it easy to mix with the waste oil, thereby making it easy to prepare a mixed slurry.

If the moisture content of the biomass is 10 to 30% by weight, the biomass may be heated for 1 to 60 minutes, preferably 10 to 40 minutes, at a superheated steam temperature of 150 to 400 ° C. to lower the moisture content of the biomass. The water content can be lowered to 15% by weight, preferably 10% by weight, more preferably 8% by weight or less, and can further increase the semi-carbonization efficiency while lowering the water content of the biomass.

The waste oil need not be particularly limited, but for example, any one or more waste oils selected from waste cooking oil, waste mineral oil, waste engine oil, waste oil, waste pate, waste organic solvent and waste lacquer may be used. Regeneration fuel oil may be used to undergo a physical process such as filtration, mixing the waste oil, more preferably, refined fuel made by physical and chemical methods such as heating the waste oil or regenerated fuel oil or mixing chemicals You can use oil. The refined fuel oil includes an ionic refinery oil, a reduced pressure refined oil and a high temperature pyrolysis oil, preferably an ionic refinery oil.

Hereinafter, 'waste oil' used in the present invention is used to mean both waste oil, recycled fuel oil and refined fuel oil. The boiling point of the said waste oil is 150 degreeC or more, Preferably it is 200 degreeC or more, More preferably, it is 250 degreeC or more.

Mixing may be mixed with a conventional stirrer for preparing the mixed slurry, and there is no need to specifically limit, but 0.5 to 10 hours or more, preferably 1 to 8 hours, more preferably 2 to 6 hours at 50 to 300 rpm It can be stirred.

Next, a step of mixing 200 to 400 parts by weight of sewage sludge having a water content of 30 to 50% by weight to 100 parts by weight of the mixed slurry.

The conventional sewage sludge has a water content of 70 to 85% by weight, which requires a lot of equipment and energy costs for drying to produce a powder having a water content of 10% by weight or less or 5% by weight for solid fuel production. none.

In the present invention, since the solid fuel can be manufactured using sewage sludge having a water content of 30 to 50% by weight, which is pre-dried so as to lower the water content of the conventional sewage sludge only 1/3 to 1/2, the cost of equipment for drying And the consumption of energy costs is significantly reduced.

The water content of the biomass and waste oil mixed slurry is 0.1 to 10% by weight, preferably 0.5 to 5% by weight, more preferably 1 to 3% by weight, so that the water content is 30 to 50% by weight in sewage sludge. Only 200 to 400 parts by weight of the mixed slurry, preferably 250 to 350 parts by weight, the water content of the mixture of the mixed slurry and sewage sludge may be 20 to 40% by weight.

Between the preparation of the biomass and waste oil mixed slurry and the mixing of the mixed slurry and the sewage sludge, the mixed slurry is heated to 120 to 240 ° C. before mixing with the sewage sludge having a water content of 30 to 50% by weight. Further comprising a mixed slurry heating step, in the step of mixing the mixed slurry and sewage sludge may be maintained at a temperature of 110 to 220 ℃ 30 minutes to 3 hours while heating the mixture of the mixed slurry and sewage sludge.

By heating the mixed slurry before mixing with the sewage sludge, the moisture contained in the sewage sludge is evaporated and dried by the heat of the mixed slurry heated in the step of mixing the mixed slurry and the sewage sludge, and at the same time, organic matter and mixing of the sewage sludge The calorific value of the solid fuel may be increased by increasing the energy density of the biomass of the slurry.

For example, the water content of the sewage sludge of the mixing step is 30 to 45% by weight, preferably 35 to 40% by weight, the mixing slurry heating step is heated to 120 to 200 ℃, preferably 120 to 160 ℃ In the step of mixing the mixed slurry and sewage sludge, the temperature is maintained at 110 to 160 ° C., preferably 110 to 140 ° C. for 1 to 3 hours, preferably 1.5 to 3 hours, while heating the mixture of the mixed slurry and sewage sludge. In this case, the water contained in the sewage sludge may be evaporated to dry the water content of the mixture of the mixed slurry and the sewage sludge to 12 to 25% by weight.

On the other hand, for example, the water content of the sewage sludge of the mixing step is 35 to 50% by weight, preferably 45 to 50% by weight, the mixing slurry heating step is 180 to 240 ℃, preferably 200 to 230 ℃ Heating and mixing the mixture slurry and sewage sludge in the step of heating the mixture of the mixed slurry and sewage sludge at a temperature of 180 to 230 ° C., preferably 180 to 210 ° C. for 30 minutes to 2 hours, preferably 30 When heated for 1 minute to 1 hour, the water contained in the sewage sludge is evaporated to dry the water content of the mixture of the mixed slurry and the sewage sludge to 12 to 25% by weight, and at the same time, the organic matter of the sewage sludge and the biomass energy of the mixed slurry. Increasing the density can increase the calorific value of the solid fuel.

Next, the mixture of the mixed slurry and sewage sludge is introduced into an extrusion molding machine to perform a step of forming a solid fuel while being compressed and dried.

The mixture of the mixed slurry and the sewage sludge has a water content of 12 to 40% by weight, preferably 12 to 25% by weight, more preferably 13 to 18% by weight, and is fed into an extruder to compress and dry the solid fuel. Mold. Compressed and dried by a screw warmed to 130 to 200 ° C., preferably 150 to 180 ° C. in the extruder, and the water content of the molded solid fuel is 10% by weight or less, preferably 1 to 8% by weight. .

Hereinafter, the present invention will be described in more detail with reference to preferred examples. However, these examples are intended to illustrate the present invention in more detail, it will be apparent to those skilled in the art that the scope of the present invention is not limited thereby.

Example 1:

The wood chips having a water content of 25 wt% and an average particle size of 15 mm were treated with wood biomass for 30 minutes with superheated steam at 300 ° C. and dried to 7 wt% of moisture.

The dried wood chips having a moisture content of 7% by weight were placed in a semi-carbonized device, and injected with nitrogen to form anoxic conditions, and then heated to 250 ° C. for 2 hours to produce semi-carbonized wood chips.

The semi-carbonized wood chips were stirred with ion refined oil (boiling point at 260 ° C.) for 2 hours at 100 rpm at a weight ratio of 2 to 1 to prepare a biomass and waste oil mixed slurry.

The biomass and waste oil mixed slurry is heated to 220 ° C., and mixed with 100 parts by weight of the heated mixed slurry while preliminarily drying 300 parts by weight of sewage sludge having a water content of 40% by weight, and mixing the mixed slurry and sewage sludge. The temperature of the mixture was kept at 190 ° C. for 40 minutes while heating. The water content of the mixture of the mixed slurry cooled to room temperature after the heating and the sewage sludge was 15% by weight.

The mixture of the mixed slurry and sewage sludge was put in an extruder and compressed and dried by a screw warmed to 150 ℃ to prepare a solid fuel. The low calorific value of the solid fuel was 4330 kcal / kg, the fixed carbon was 31.9 wt%, and the moisture content was 5 wt%.

Example 2:

The wood chips having a water content of 25 wt% and an average particle size of 15 mm were treated with wood biomass for 30 minutes with superheated steam at 300 ° C. and dried to 7 wt% of moisture.

The dried wood chips having a moisture content of 7% by weight were placed in a semi-carbonized device, and injected with nitrogen to form anoxic conditions, and then heated to 250 ° C. for 2 hours to produce semi-carbonized wood chips.

The semi-carbonized wood chips were stirred with ion refined oil (boiling point at 260 ° C.) for 2 hours at 100 rpm at a weight ratio of 2 to 1 to prepare a biomass and waste oil mixed slurry.

The biomass and waste oil mixed slurry is heated to 140 ° C., and 300 parts by weight of sewage sludge having a water content of 40% by weight is preliminarily mixed with 100 parts by weight of the heated mixed slurry, and the mixed slurry and sewage sludge are gradually added. The temperature of the mixture was kept at 120 ° C. for 2 hours while heating. The water content of the mixture of the mixed slurry cooled to room temperature after the heating and the sewage sludge was 16% by weight.

The mixture of the mixed slurry and sewage sludge was put in an extruder and compressed and dried by a screw warmed to 155 ° C. to prepare a solid fuel. The low calorific value of the solid fuel was 4210 kcal / kg, the fixed carbon was 31.5 wt%, and the moisture content was 5 wt%.

Example 3:

The wood chips having a water content of 25 wt% and an average particle size of 15 mm were treated with wood biomass for 30 minutes with superheated steam at 300 ° C. and dried to 7 wt% of moisture.

The dried wood chips having a moisture content of 7% by weight were placed in a semi-carbonized device, and injected with nitrogen to form anoxic conditions, and then heated to 250 ° C. for 2 hours to produce semi-carbonized wood chips.

The semi-carbonized wood chips were stirred with ion refined oil (boiling point at 260 ° C.) for 2 hours at 100 rpm at a weight ratio of 2 to 1 to prepare a biomass and waste oil mixed slurry.

300 parts by weight of sewage sludge having a moisture content of 40% by weight was preliminarily dried to 100 parts by weight of the biomass and waste oil mixture slurry, and mixed. The water content of the mixture of the mixed slurry and the sewage sludge was 30.6% by weight.

The mixture of the mixed slurry and the sewage sludge was put in an extruder and compressed and dried by a screw warmed to 180 ℃ to prepare a solid fuel. The low calorific value of the solid fuel was 4150 kcal / kg, the fixed carbon was 31 wt%, and the moisture content was 5 wt%.

Example 4:

Wood chips having an average particle size of 15 mm dried with a wood-based biomass with a water content of 10% by weight were used.

The wood chips were stirred with ion refined oil (boiling point at 260 ° C.) for 2 hours at 100 rpm at a weight ratio of 2 to 1 to prepare a biomass and waste oil mixed slurry.

300 parts by weight of sewage sludge having a moisture content of 40% by weight was preliminarily dried to 100 parts by weight of the biomass and waste oil mixture slurry, and mixed. The water content of the mixture of the mixed slurry and the sewage sludge was 30.6% by weight.

The mixture of the mixed slurry and the sewage sludge was put in an extruder and compressed and dried by a screw warmed to 180 ℃ to prepare a solid fuel. The low calorific value of the solid fuel was 4005 kcal / kg, fixed carbon was 28.4 wt%, and moisture content was 5 wt%.

Comparative Example 1:

25 parts by weight of anthracite coal is mixed with 75 parts by weight of sewage sludge powder having a water content of 5% by weight, and then a predetermined amount of water is kneaded to prepare a mixture having a water content of 15% by weight. Compressed and dried to prepare a solid fuel. The low calorific value of the solid fuel was 4020 kcal / kg, the fixed carbon was 25.7% by weight, and the moisture content was 5% by weight.

The solid fuel has a low calorific value must be included more than a certain amount of additional caloric supplements to meet more than 4000 kcal / kg, a problem that requires a lot of equipment costs and operating costs to dehydrate and dry to less than 10% by weight of moisture content In addition, the equipment should be periodically cleaned by the fly ash generated during the pulverization, and the dried and molded solid fuel did not have a high heat generation rate.

Comparative Example 2:

100 parts by weight of sewage sludge having a water content of 80% by weight, 100 parts by weight of wood powder having an average particle size of 0.5 mm dried at 10% by weight of wood-based biomass, and 15% by weight of chaff having a submicrobial biomass. 20 parts by weight of min, 3 parts by weight of ion refined oil were mixed, hot air dried at 300 ° C. for 5 hours, the dried solid was pulverized, and kneaded by adding a certain amount of water to prepare a mixture having a moisture content of 15% by weight, followed by an extrusion molding machine. And compressed and dried by a screw warmed to 180 ℃ to prepare a solid fuel. The low calorific value of the solid fuel was 5410 kcal / kg, the fixed carbon was 13.3 wt%, and the moisture content was 5 wt%.

The proportion of sewage sludge solids in the manufactured solid fuel was 15.4% by weight, which is significantly lower than the proportion of sewage sludge solids in the solid fuel of Example 1, 64% by weight, which is not suitable for the treatment of excess sewage sludge.

Claims (5)

Preparing a semi-carbonized biomass having a water content of 1 to 5 wt%, heating the biomass at 200 to 350 ° C. for 20 minutes to 2 hours under anoxic or low oxygen conditions;
Preparing a mixture of biomass and waste oil by mixing the semi-carbonized biomass and waste oil in a weight ratio of 1: 1 to 4: 1;
A mixed slurry heating step of heating the mixed slurry to 120 to 240 ° C;
To 100 parts by weight of the heated mixed slurry, a mixed slurry and sewage sludge mixture maintained at 110 to 220 ° C. for 20 minutes to 3 hours while mixing 200 to 400 parts by weight of sewage sludge having a water content of 30 to 55% by weight and Mixing; And
And inserting the mixture of the mixed slurry and the sewage sludge into an extrusion molding machine to form a solid fuel while compressing and drying the solid fuel. The sewage sludge of claim 1, wherein the biomass is an herbal biomass selected from Kenyaf, rice hull, corn cob, rice straw, and cotton swab, or wood based biomass obtained from wood or by-products thereof. Solid fuel production method comprising a. The method of claim 2, wherein if the moisture content of the biomass introduced into the semi-carbonized biomass manufacturing step is 10 to 30% by weight, the biomass is heated to a superheated steam temperature of 150 to 400 ℃ for 1 to 60 minutes Solid fuel manufacturing method characterized in that it further comprises. delete The method of claim 1, wherein the molding step is compressed and dried by a screw warmed to 130 to 200 ℃ in an extruder.