KR101049048B1 - Manufacturing method for briqeutte using sewage sludge - Google Patents

Abstract

PURPOSE: A method for manufacturing briquette using sewage sludge is provided to cost-effectively generate regenerated fuel based on organic wastes such as the sewage sludge. CONSTITUTION: Sewage sludge is dehydrated and dried. The dried sewage sludge is carbonated to obtain sludge carbide. A combustible gas is generated from a sludge carbide generating process. The combustible gas cooling process and a toxic material eliminating process are further implemented. Mixed fuel coal is generated by mixing sludge carbide, anthracite coal, and charcoal. The briquette is obtained using the mixed fuel coal. In the mixed fuel coal, 70-90 weight% of anthracite coal and 5-15 weight% of charcoal.

Description

MANUFACTURING METHOD FOR BRIQEUTTE USING SEWAGE SLUDGE}

The present invention relates to a method for producing hole coal using sewage sludge.

Domestic sewage treatment rates and water quality have been gradually improved, aiming at the level of developed countries, and investments in the expansion and construction of various sewage treatment plants have been steadily achieved to achieve this. However, sludge produced as a by-product in sewage treatment process has increased as well as the addition and establishment of sewage treatment plants.However, due to the lack of treatment facilities, the lack of proper treatment methods, the strengthening of related laws such as the prohibition of direct landfilling and strengthening of marine dumping regulations, etc. It is urgent to prepare alternatives for the treatment of sludge.

According to data from the Ministry of Environment in 2008, there are about 403 public sewage treatment facilities in Korea, and the treatment capacity reaches 24,430 thousand㎥ / day. In addition, sewage sludge from public sewage treatment facilities is 2,817 thousand tons / year, of which land landfill is 103 thousand tons / year (4%), incineration is 458 thousand tons / year (16%), and recycling 533 thousand tons / year (19%) ). It is reported that offshore dumping is being handled at 1721 million tons / year (61%). Due to the government's policy, direct landfilling of sludge is prohibited (Revised Rules of the Waste Management Act-1997), and landfilling of treated sludge is not possible due to groundwater contamination and odor generation. In addition, existing landfills are expected to run out of landfill capacity after 10 years. In preparation for the London Convention and the 96 Protocols on dumping at sea, the Ministry of Maritime Affairs and Fisheries has revised the Act on the Prevention of Marine Pollution Prevention Act (2004. 2. 21), which has been amending related laws since 2004. In addition, the ban on ocean dumping following the entry into force of the London Convention entered into force in 2008. Since 2012, all sewage sludge is banned from dumping at sea, and as a part of the government's countermeasures against global warming, as a countermeasure against the global warming, the reduction of GHG emissions has been achieved. Is needed.

Accordingly, it is urgent to prepare a treatment plan for organic sludge offshore dumping waste, which accounts for 19% of sewage sludge, which is treated by offshore dumping and landfill incineration. For this reason, researches on waste treatment are being actively conducted, and alternatives are proposed for fueling, composting, solidifying, and anaerobic digestion using sludge reduction technology and recycling technology.

Therefore, the present invention was derived to solve the above-described problems, by using the sewage sludge which is an organic waste to produce renewable fuel not only to prevent environmental pollution due to sewage sludge, but also using sewage sludge that can be produced at economical cost It is intended to provide a method for manufacturing a hole coal.

Other objects of the present invention will become more apparent through the embodiments described below.

Mixed fuel coal manufacturing method according to an aspect of the present invention, the step of dewatering and drying the sewage sludge, the step of carbonizing the dried sewage sludge to produce sludge carbide, and mixed sludge carbide, anthracite coal and charcoal It includes the step of producing, the mixed fuel coal contains at least 70% by weight, more specifically 70 to 90% by weight of anthracite coal.

Mixed fuel coal manufacturing method according to the present invention may include one or more of the following embodiments. For example, the mixed fuel coal may include 5 to 15% by weight of charcoal. The method may further include a combustion gas cooling process of cooling a high temperature combustion gas generated while generating sludge carbide, and a combustion gas treatment process of removing harmful substances included in the cooled combustion gas.

Dehydrated sludge can be dried at 250 ~ 350 ℃ and carbonized below 700 ℃.

Mixed fuel coal according to an aspect of the present invention is characterized in that it is produced by the method as described above.

Hole coal according to an aspect of the present invention is characterized in that it is produced using a mixed fuel coal produced by the method as described above.

Mixed fuel coal production method according to another aspect of the present invention, the step of dewatering and drying the sewage sludge, the step of carbonizing the dried sewage sludge to produce sludge carbide, and mixing the sludge carbide and anthracite coal to produce a mixed fuel coal Including the step, the mixed fuel coal contains at least 80% by weight, more specifically 80 to 90% by weight of anthracite coal.

Mixed fuel coal production method according to another aspect of the present invention, the combustion gas cooling step of cooling the high-temperature combustion gas generated while generating the sludge carbide, and the combustion gas processing step of removing harmful substances contained in the cooled combustion gas It may further include.

Mixed fuel coal manufacturing method according to the present invention may include one or more of the following embodiments. For example, the sludge may be dried at 250 to 350 ° C. and carbonized at 700 ° C. or less.

Mixed fuel coal according to another aspect of the present invention is characterized in that the mixed fuel coal produced by the above method.

Hole coal according to another aspect of the present invention is characterized in that it is formed using a mixed fuel coal produced by the method as described above.

By producing recycled fuel using sewage sludge which is an organic waste, it is possible to provide a method of manufacturing hole coal using sewage sludge which can be produced at an economical cost as well as preventing environmental pollution due to sewage sludge.

1 is a flow chart illustrating a method of manufacturing a mixed fuel coal according to an embodiment of the present invention.
2 is a flowchart illustrating a method of manufacturing a mixed fuel coal according to another embodiment of the present invention.
3 is a view showing the water distribution inside the sewage sludge.
4 is a graph showing a drying experiment curve of sewage sludge.
5 is a graph showing the principle of the carbonization process of sewage sludge.
6 is a view illustrating a drying and carbonization process of sewage sludge in the method of manufacturing a mixed fuel coal according to an embodiment of the present invention.

As the inventive concept allows for various changes and numerous embodiments, particular embodiments will be illustrated in the drawings and described in detail in the written description. However, this is not intended to limit the present invention to specific embodiments, it should be understood to include all transformations, equivalents, and substitutes included in the spirit and scope of the present invention. In the following description of the present invention, if it is determined that the detailed description of the related known technology may obscure the gist of the present invention, the detailed description thereof will be omitted.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "have" are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, components, or a combination thereof.

1 and 2 are flowcharts illustrating a method of manufacturing a mixed fuel coal according to embodiments of the present invention.

Referring to Figure 1, the mixed fuel coal production method according to an embodiment of the present invention, the step of drying the sewage sludge, the step of carbonizing the dried sewage sludge to produce a sludge carbide, sludge carbide, anthracite and charcoal ( Charcoal) to produce a mixed fuel coal.

Referring to FIG. 2, the method for manufacturing mixed fuel coal according to another embodiment of the present invention includes drying the sewage sludge, carbonizing the dried sewage sludge to generate sludge carbide, and mixing the sludge carbide and anthracite coal. Generating a mixed fuel coal.

Hereinafter, in the method of manufacturing mixed fuel coal according to the embodiments of the present invention, a step of drying sewage sludge, generating sludge carbide, and a method of mixing sludge carbide and anthracite or anthracite and charcoal will be described sequentially. .

sewer Sludge  dry

3 is a view showing the water distribution inside the sewage sludge.

Referring to FIG. 3, the water distribution in the sewage sludge before dewatering may be classified into free or bulk water, interstitial water, surface water, and bound water.

Free water is water that is not affected by suspended solids particles.Possible water is water trapped inside a floc or microorganism. Adjacent water is water where water molecules are firmly attached to a solid surface by hydrogen bonding. Moisture that is chemically bound to particles is known as moisture, which can only be removed by thermal energy.

Interstitial water is water present in the gap between the large solid particles, and is not directly bonded to the solid material, so that the interstitial water can be easily separated by a concentration method. The capillary water also belongs to the pore water region.

Capillary water is water existing between particles of fine sludge solids, which is capillary pressure, and is water that is bound by capillary pressure. The same force acting inversely with the force of the capillary surface tension can be removed (separated by mechanical compression such as centrifugal force or vacuum pressure).

Surface water is water adhering to the bound water of the colloidal particles or to the microsludge produced by biological treatment. This water is difficult to remove, and the bound water of the colloidal particles can be separated by flocculation with a flocculant.

In bound water, the water in the sludge is surrounded by the microbial cell membrane, while the pore water, the capillary binding water, and the adjacent water are external water, whereas the cell fluid is internal water. To remove this, the cell membrane must be destroyed, so it is difficult to remove. When aerobic or anaerobic digestion, high temperature heating or freezing are performed, the internal water is drawn out to the external water.

It is an operation to vaporize, evaporate, and remove the water in the sludge by applying heat from industrial wastewater sludge containing water. When the weight of the wet sample is Ww (kg) and the weight of the dry sample is Wd (kg), the water (x) And water content w are defined by equations (1) and (2), respectively.

(1)

(One)

(2)

(2)

The moisture content in equilibrium between the sludge and the wet gas is called equilibrium moisture content (We), and the difference between the total moisture content and equilibrium moisture content of the solid is called free moisture content (F). The moisture content removed when drying with air at temperature and humidity.

The equilibrium moisture content at the point where the equilibrium curve meets the relative humidity of 100% is called bound water, and more water is called unbound water.

When drying the sludge containing water is subjected to a three-step drying process, this process is shown in the drying experiment curve of FIG. 4 is a graph showing a drying experiment curve of sewage sludge.

Referring to FIG. 4, section A is a preheating period during which the sample is preheated and the moisture content is gradually decreased, and section B is a constant-rate drying period in which the moisture content of the sample is linearly decreased and the moisture content of the sample is constant. Period C, which is the period until the decrease in moisture content gradually decreases and reaches equilibrium, is called a falling-rate drying period, and the drying rate is obtained from a slope of the moisture content decreasing curve.

The drying rate is expressed as the amount of water evaporated from the unit surface area per unit time (kg-H ₂ O / ㎡h) for the fixed sample, and the amount of water evaporated from the dry sample at 1 kg per hour for the irregular sample [kg-H ₂ O / h-dry solid h].

If the mass of the anhydrous material is W (kg), the dry area of the material is A (m2), the water content is w (kg-H ₂ O / kg-dry solid), and the time is θ (h), R (kg / m <2> h) can be represented by Formula (3).

(3)

(3)

-W dw is the amount of water evaporated and is equal to the change in weight of the solid sample -dw due to drying. That is, it is as following Formula (4).

(4)

(4)

Substituting Eq. (4) into Eq. (3) and expressing it as a differential equation is the same as Eq. (5).

(5)

(5)

When such a drying rate is floated with respect to the water content, it is displayed as shown in FIG. 4 and the periods A, B and C correspond to the three periods in FIG.

The period A is relatively short, and in the period B, evaporation of water from the sludge can be considered as evaporation from the free liquid level. The rate-of-drying period of C is the simplest indication that the drying characteristics of the material are different depending on the material even though the air-side conditions such as temperature, humidity and wind speed are constant.

Industrially used dryers are used in various forms depending on the type of dry matter. Dryers can be classified into convection heat transfer type, conduction heat transfer type, and radiant heat transfer type dryers according to heat transfer methods. Convection heat dryers include box type (batch) dryers, tunnel type dryers, nozzle jet dryers, and band type aeration dryers. Conductive heating dryers include box type vacuum dryers, freeze dryers, cylindrical dryers, multi-disk dryers, and airflows. Or a conical stirring dryer, an indirect heating rotary dryer, and the radiant heat type dryer includes a far infrared ray dryer, a freeze vacuum dryer, and the like.

Sludge  Carbide generation

Pyrolysis processes are being developed as one of techniques for recovering energy from flammable wastes by low pollution treatment. Pyrolysis is the operation of heating waste to high temperature (500 ~ 1,000 ℃) in an oxygen-free or low-oxygen atmosphere. Combustion is by exothermic reaction, but pyrolysis is by endothermic reaction. In addition, when the organic material is burned, CO ₂ and H ₂ O are produced, whereas pyrolysis produces a material as shown in FIG. 5 by reducing the molecular weight of organic waste and organic compounds by heat.

5 is a graph showing the principle of the carbonization process of sewage sludge.

In the gas phase, liquids such as tar, oil and aqueous solution containing hydrocarbons such as hydrogen, methane and ethane and organic chemicals such as acetic acid, acetone and ethanol, solid net carbon, glass, metal and earth and sand The composition of the decomposition products such as Char (Char) is greatly changed depending on the temperature, there are low temperature method and high temperature method.

At low temperatures (around 450-550 ° C), more tar, char and liquid fuels are produced. At high temperatures (around 750 ° C), a lot of gaseous fuels are produced. Therefore, the low temperature method is called pyrolysis, and the high temperature method is also called gasification, but both low temperature and high temperature are collectively called pyrolysis method.

When heated at low and low temperatures, the molecules are decomposed at the weakest point and have sufficient reaction time, so that recombination of the decomposed molecules occurs, making it difficult to decompose and producing a thermally stable solid. However, heating at high speeds and temperatures causes the molecules to explode within a short reaction time, producing a wide range of organic low molecular weight materials.

The pyrolysis process varies in composition and amount of product depending on heat supply rate, pyrolysis temperature, residence time, waste composition, contact method of waste and gas in the reactor, and presence of oxygen. The effects of these are summarized as follows.

As the heat supply rate increases in the pyrolysis reaction, the amount of pyrolysis gas produced increases, and the amount of organic liquid, water, and char decreases.

The production rate of CO, H ₂ , CH _4, etc. in the pyrolysis gas increases as the heat supply rate increases, and the amount of CO ₂ generated decreases.

In a pure sense, pyrolysis is an anoxic reaction, but there is a problem of supplying energy for pyrolysis from the outside, so pyrolysis products are actually burned in the presence of oxygen to supply heat for pyrolysis and recover excess heat. It is often used as a gasification system.

When pyrolysis proceeds in the presence of oxygen, the amount of CO produced is maximum. On the other hand, in pure pyrolysis, the amount of H ₂ generated is maximum. In the case of using air as the oxygen source, since most of the pyrolysis generated gas is occupied by nitrogen, combustion efficiency is reduced.

When the heating temperature is low, the oil component (liquid phase) in the fuel component ratio is large, and the gas component (gas phase) increases as the heating temperature is gradually increased.

At low and high heating rates, gas production is high, but at high heating rates, water content and organic matter in solution are decreasing.

Another factor influencing the pyrolysis process is moisture. The more moisture, the longer it takes to raise the temperature to the operating temperature, and the more expensive it is to dry the waste through preheating. .

The heating time is approximately proportional to the square of the waste size and the burning time depends on the solid form and mass transfer and the relative speed of the chemical reaction, but is usually proportional to the power of one to two powers.

Pyrolysis reactors include fixed bed gasification plants, external kiln plants, fluidized bed plants, shaft furnace plants and indirectly heated multistage screw plants.

In the stationary gasifier, the waste is injected into the upper part of the reactor and moved downward, followed by drying, pyrolysis, gasification, and combustion heat formed at the bottom in the form of drying, pyrolysis, gasification, and combustion sequentially. Slag or ash is discharged to the bottom of the stationary gasifier and pyrolysis gas is discharged to the top.

The external kiln-type equipment uses a rotary kiln type furnace to pyrolyze the input while indirectly heating the input, and circulates the heat recovered from the exhaust gas process as a heat source for the indirect heating. The external kiln type plant has a disadvantage of occupying a lot of installation area compared to the fluidized bed, but has the advantage that it can be used for components with a slow pyrolysis reaction rate or a large variation in the calorie amount of waste.

Fluidized bed installations pyrolyze a portion of the waste in the furnace by self-burning, and most companies develop this technology. Compared with the rotary kiln method, the pyrolysis reaction rate is faster and the installation area is smaller, but it is difficult to adapt to the fluctuation of waste calorific value.

Shaft furnace equipment is an application of shaft furnace technology in the form of a blast furnace, and is being developed in Nippon Steel and Nippon Steel Pipe (NHK). The gas can be gasified and melted in one furnace at the same time, making the installation compact. In addition, although the shaft furnace equipment can use coke as a reducing agent and maintain the inside of the reactor at a high temperature, it has a disadvantage of high operating cost caused by using coke.

In the indirect heating multi-stage screw type equipment, the carbonization device is decomposed into dry gas (volatile matter) and carbonaceous residues by dry and carbonization phenomena generated inside the preheating pipe and the drying pipe where air is cut off by heating the fuel combustion chamber. Dry gas is burned by evaporating to upper layer through gas outlet at upper part of preheating pipe and drying pipe, and carbonaceous gas is connected from top to bottom through three carbonization pipes and one cooling pipe. It is a dry carbonization system that continuously recycles and carbonizes carbides within 4% of moisture content within 30 minutes. Indirect heating multi-stage screw type equipment dissipates environmental pollutants generated in carbonization process at high temperature (850 ℃ ~ 1,000 ℃) generated in upper combustion chamber, and supplies heat source directly to dryer to provide energy rate during drying free of charge. There is no fuel cost, and there is no generation of wastewater, which is a secondary pollution, so there is no need for a secondary facility such as a wastewater treatment plant.

mix Fuel coal  Produce

Sewage sludge carbide and anthracite or sewage sludge carbide, anthracite and charcoal are mixed to produce mixed fuel coal.

Anthracite is a type of coal produced over a long period of time in the carbonization stage of coal and is the highest in coal level. The geological ages of other coals occur in older geology. It consists mainly of carbon and contains hydrogen and oxygen. In addition, it contains nitrogen, sulfur and inorganic substances. High levels of sulfur can cause an unpleasant odor of sulfur dioxide when burned. High-quality coal is low in moisture, contains a lot of fixed carbon and volatile matter, and calorific value is 6,000 ~ 8,000kcal / kg. In the case of lignite, the amount of volatile matter and fixed carbon is almost the same, while there is almost no volatile matter of anthracite coal. Anthracite has a combustion ratio of 12 or more, fixed carbon of 92.3% or more, and an ignition temperature of 400 to 500 ° C.

Charcoal is a solid product that occurs when wood is heated with the air cut off and heated with very little air. As a material of charcoal, solid wood is generally used.

Hereinafter, specific embodiments of the mixed fuel coal according to the present invention and a manufacturing method thereof will be described.

6 is a view illustrating a drying and carbonization process of sewage sludge in the method of manufacturing a mixed fuel coal according to an embodiment of the present invention.

Referring to FIG. 6, sewage sludge is carbonized through an import process, a drying process, a carbonization process, and a combustion gas treatment process. The loading facility of a 100 ton sludge carbonization facility consists of a 50 ton weighbridge, a storage tank of 130m3 and a sludge feed pump of 5.8 tons / hour x 8kg / cm2. Drying equipment is equipped with a 100 ton / day kiln dryer, 8,800 Nm3 / hour cyclone dust collector and 1.7 ton / hour dry sludge forming machine, and the carbonization facility is 1.7 ton / hour direct heating rotary furnace type. A carbonization furnace and a reburn furnace of 142,300 kcal / m 3 are installed.

Combustion cooling system consists of 12,690Nm3 / hour gas cooling tower, 2,060,400kcal / hour combustion air preheater, and 621,600kcal / hour white smoke reduction air preheater. A reduction device (SNCR), a 13,850 Nm 3 / hour filtration dust collector, and a 13,850 Nm 3 / hour spray contact cleaning dust collector are installed.

Dewatered sewage sludge was dried at 250 ~ 350 ℃ in a 1.7 ton / hour dry sludge molding machine using a 100 ton / day kiln type dryer, and formed into a diameter of about 2 to 3 mm, followed by direct heating of 1.7 ton / hour. Carbonization at about 700 ° C. in a rotary hearth type carbonization furnace produced slurry carbides.

The flue gas treatment process includes a flue gas cooling facility and a flue gas treatment facility.

Combustion gas cooling system is composed of gas cooling tower, combustion air preheater and smoke reduction air preheater. The hot combustion gas discharged from the combustion furnace is cooled in the gas cooling tower and sent to the combustion air preheater. After the heat exchange with the combustion gas through the dry exhaust gas blower, the combustion gas is cooled to a certain temperature and sent to the white smoke reduction air preheater.

Combustion gas treatment system is composed of dust removal device, harmful acid gas removal device, smoke reduction device and so on. The role of the flue gas treatment facility is to supply a large amount of fly ash and harmful gases such as sulfur oxides (SOx), nitrogen oxides (NOx) and hydrogen chloride (HCl), and very small amounts of dioxins and heavy metals contained in the combustion gas discharged from recombustion. It is treated and discharged below the standard value of conservation method.

The anthracite coal was sieved using a sieve having a width x length x height of 700x60x40 mm and using a thickness of 1 mm in diameter and 3 mm in sieve spacing.

Charcoal is a mixture of domestic and foreign products with various types of charcoal on the market. Charcoal was crushed with a wooden hammer and hung with a 3 mm gap.

Using the sludge carbide, anthracite and charcoal prepared as described above to prepare a mixed fuel coal having a content as shown in Table 1 below.

Content and Content of Mixed Fuel Coal division Mixed fuel coal sample content (%) Sample content (5Kg standard) sample hard coal Carbide Charcoal hard coal Carbide Charcoal S1 100 - - 5 - - S2 - 100 - - 5 - S3 - - 100 - - 5 S4 70 30 - 3.5 1.5 - S5 80 20 - 4.0 1.0 - S6 90 10 - 4.5 0.5 - S7 30 70 - 1.5 3.5 - S8 20 80 - 1.0 4.0 - S9 10 90 - 0.5 4.5 - S10 90 5 5 4.5 0.25 0.25 S11 80 10 10 4.0 0.5 0.5 S12 70 15 15 3.5 0.75 0.75 S13 30 60 10 1.5 3.0 0.5 S14 30 50 20 1.5 2.5 1.0 S15 20 70 10 1.0 3.5 0.5 S16 10 70 20 0.5 3.5 1.0 S17 10 80 10 0.5 4.0 0.5 S18 5 90 5 0.25 4.5 0.25

The water content of sewage sludge dewatered before carbonization was 80% and that of sludge carbide was less than 1%. The organic matter of dewatered sludge was 70 ~ 75% and the calorific value was 3,650kcal / kg. Carbide organic matter content decreased from 70-75% before carbonization to 30-42%, and calorific value decreased by 13% to 3,086 kcal / kg. Elemental analysis showed that carbon contained 45.8% in dewatered sludge and 34.6% in sludge carbide, while hydrogen contained 6.4% in dehydrated sludge and 0.5% in carbide.

As a result of analysis of heavy metals contained in dewatered sludge and sludge carbide, arsenic (As) decreased from 0.116 to 0.01 mg / l, and lead (Pb) decreased from 0.027 to 0.01 mg / l. Mercury (Hg) and zinc (Zn) were detected in dehydrated sludge, 0.169 and 0.044 mg / l, respectively, but not in sludge carbide. No other heavy metals were detected in the sludge carbides.

Among the exhaust gases generated during the drying and carbonization of sewage sludge, dust was detected at 1.0 mg / Sm 3, which is lower than the emission limit of 80 mg / Sm 3, and carbon monoxide (CO) was 15 ppm, which is 200 ppm or less. NOx, SOx, and HCl were detected at 33, 1.0, and 1.0 ppm, which are 150, 70, and 40 ppm or less, respectively.

Odor measurement methods include a direct sensory method, an air dilution sensory method, and a chemical analysis method. In this embodiment, the direct sensory method was used. Odors generated during incineration at 900 ° C. were measured for 20 people in a room of 5m, 7m, and 4m in width, length, and height, respectively. If the odor is 2, it corresponds to the detection of moderate odor, and if the odor is 1, it corresponds to the degree of detecting a slight odor.

Odor was satisfied with criteria 2 or below by direct sensory method, and dioxin was detected as low as 0.05 ng-TEC / Nm3 below 0.1ng-TEC / Nm3.

The high calorific value, fixed carbon ratio, volatile content, ash, and moisture ratio of the mixed fuel coal samples S1 to S18 are shown in Table 2 below.

       Industrial Analysis of Mixed Fuel Coal sample High calorific value
(kcal / kg) Fixed carbon
(%) Volatile
(%) Ash
(%) moisture
(%) S1 4,539 51.76 5.74 33.69 8.81 S2 1,666 15.36 7.43 76.33 0.88 S3 7,477 76.38 7.57 3.70 12.35 S4 3,769 45.79 6.21 42.22 5.78 S5 4.087 47.51 6.20 39.59 6.70 S6 4,179 49.64 6.33 36.74 7.29 S7 2,895 26.61 7.31 63.37 2.71 S8 2,195 22.64 8.07 67.32 1.97 S9 2,139 20.35 7.98 70.35 1.32 S10 4,831 50.88 5.64 35.16 8.32 S11 4,611 50.55 6.57 34.50 8.38 S12 4,346 47.54 7.26 37.18 8.02 S13 3,143 36.63 7.29 51.69 4.39 S14 3,620 40.20 7.40 46.14 6.26 S15 3,035 30.40 7.31 58.78 3.51 S16 3,063 31.93 8.06 55.69 4.32 S17 2,671 26.26 7.80 63.27 2.67 S18 2,179 20.64 7.55 69.92 1.89

The calorific value was measured using a model name PARR6300, a calorific value analyzer. The measuring principle is to measure calorific value by temperature difference by heat energy transfer. The high calorific value was measured twice for each sample using the calorific value device, and then the average value was taken.

Industrial analysis used the American Society for Testing and Materials (ASTM) D3172-89 standard test method. The water content of the sewage sludge was determined by drying at 105 ° C. for at least one hour in an inert atmosphere in an oven and then measuring the reduced weight. Volatile content is obtained after heating in an inert atmosphere for 7 minutes while maintaining the temperature of the electric furnace at 930 ~ 970 ℃, and subtracting water content from the reduced weight. Ash remains after burning for 4 hours under an oxidizing atmosphere while maintaining at 750 ℃. The amount was obtained. Fixed carbon was obtained after limiting moisture, volatile matter and ash content in the total weight. The content of each item was measured and averaged after two analyzes for each sample.

The calorific value and the analytical value of the mixed fuel coal sample of S1 to 18 are shown in Table 3 below. Referring to the table below, the calorific value, fixed carbon, volatile content, ash and moisture content of the raw materials S1 and S2 and the mixed fuel coals S5, S6, S10, S11 and S12 among the 18 samples were determined as fuel coal quality and hole coal quality. It was determined that it could be used as an auxiliary fuel due to the specification.

Calorific Value and Analytical Value of Mixed Fuel Coals sample High calorific value
(kcal / kg) Fixed carbon
(%) Volatile
(%) Ash
(%) moisture
(%) standard More than 4,000 20 or more 50 or less 35 or less below 10 S1 Ο Ο Ο Ο Ο S2 X X Ο X Ο S3 Ο Ο Ο Ο X S4 X Ο Ο X Ο S5 Ο Ο Ο Ο Ο S6 Ο Ο Ο Ο Ο S7 X Ο Ο X Ο S8 X Ο Ο X Ο S9 X Ο Ο X Ο S10 Ο Ο Ο Ο Ο S11 Ο Ο Ο Ο Ο S12 Ο Ο Ο Ο Ο S13 X Ο Ο X Ο S14 X Ο Ο X Ο S15 X Ο Ο X Ο S16 X Ο Ο X Ο S17 X Ο Ο X Ο S18 X Ο Ο X Ο

The heavy metal analysis results of the mixed fuel coal samples of S1 to 18 are shown in Table 4 below.

As a heavy metal analyzer, the model name Optima 5300DV of Perkin Elmer, USA, which is an inductively coupled plasma analyzer, was used. Pretreatment was performed using microwave (Milestone, Italy) for heavy metal analysis of the mixed fuel coal. Acid was added to a sealed container and pretreated in a microwave, and heavy metals were analyzed using the inductively coupled plasma analyzer.

Referring to Table 4 below, seven heavy metals of arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), lead (Pd), zinc (Zn) and mercury (Hg) were all detected below the reference level. Therefore, it was judged that all the mixed fuel coal samples of said S1-18 satisfy | filled the quality standard of sewage sludge fuel coal. In addition, small amounts of arsenic, copper, and zinc were detected among the heavy metals detected below the reference value. In view of these results, it is judged that the problem of heavy metals does not occur when the raw material is manufactured and used as a mixed fuel coal.

Determination of Heavy Metals in Mixed Fuel Coals (ND: Not Detected) sample As CD Cr Cu Pd Zn Hg standard 1.5 or less 0.3 or less - 3.0 or less 3.0 or less - Less than 0.005 S1 ND ND ND 0.0110 ND ND ND S2 0.0125 ND ND 0.0180 ND 0.0010 0.0001 S3 ND ND ND 0.0070 ND ND ND S4 ND ND ND 0.0125 ND ND 0.0001 S5 ND ND ND 0.0080 ND ND 0.0001 S6 ND ND ND 0.0080 ND ND 0.0001 S7 0.0020 ND ND 0.0135 ND ND 0.0001 S8 ND ND ND 0.0050 ND ND 0.0001 S9 0.0140 ND ND 0.0155 ND ND 0.0001 S10 ND ND ND 0.0085 ND ND 0.0001 S11 0.0020 ND ND 0.0150 ND ND ND S12 ND ND ND 0.0125 ND ND 0.0001 S13 ND ND ND 0.0095 ND ND ND S14 0.0020 ND ND 0.0180 ND ND ND S15 0.0090 ND ND 0.0175 ND ND 0.0001 S16 0.0100 ND ND 0.0180 ND ND 0.0001 S17 0.0110 ND ND 0.0135 ND ND 0.0001 S18 0.0115 ND ND 0.0135 ND ND 0.0002

A flue gas analyzer is used to analyze the gases generated during the combustion of mixed fuel coal. As the exhaust gas analyzer, model name GreenLine MK2 was used. Combustion characteristics experiments were carried out with the mixed fuel coal samples S1 to S3 and the mixed fuel coal S6 and S10 samples as the standard samples. Experimental conditions were 1 hour at 10 g of analytical sample, 8 L / min of air, temperature rising method 0-150 ° C. → 10 ° C./min, 150-550 ° C. → 6 ° C./min, 550-850 ° C. → 10 ° C./min, 850 ° C. And the exhaust gas was analyzed.

When the oxygen supply is insufficient during combustion or low combustion temperature, carbon monoxide (CO), which is an incomplete combustion product, is generated. Among the mixed fuel coal samples, carbon monoxide at the combustion of S1, S6, and S10 was the highest at 5,000, 3,500, and 4,500 ppm at 400 ~ 800 ° C. It seems to be.

Nitrogen oxides are produced by the oxidation of nitrogen species bound to carbon or other atoms contained in the fuel. Fuel NO _x accounts for 75-95% of the total nitrogen oxides, about 50-70% nitrogen oxides by volatile-N, and about 20-30% nitrogen oxides by char-N. Anthracite coal produced up to 10ppm at about 200 ~ 850 ℃ and carbide (S2) generated 12ppm at about 500 ~ 600 ℃. The other mixed fuels, S3, S6 and S10, exhibited concentrations of up to about 10, 8 and 16 ppm with the increase of combustion temperature and the generation of NOx.

Sulfur dioxide (SO ₂ ) is a colorless, irritating toxic gas that corresponds to the air pollutants formed by the combination of sulfur contained in the fuel with oxygen in the air. Exposure to high concentrations of sulfur dioxide gas from the combustion of sulfur-containing fuels causes respiratory illness and problems such as acid rain, building corrosion, and reduced visibility. In samples S1 to S18 of the mixed fuel coal, SOx did not occur in almost all samples.

As described above, it can be seen that the exhaust gas concentrations for the CO, NOx, and SO ₂ of the mixed fuel coal samples S6 and S10 are detected to be low or a trace amount compared to the anthracite sample.

Among the 15 mixed fuel coals (S4 to S18) prepared by mixing a sludge carbide, anthracite coal and charcoal at a predetermined ratio, a sample suitable as a mixed fuel coal was analyzed as S5, S6, S10, S11, and S12. It turns out to be strange.

The making of a bullet

The five bullets (S5, S6, S10, S11, S12) which can be used as a mixed fuel coal were used as a raw material, and the coal pellet was manufactured. Hole production equipment was manufactured on the basis of hole No. 1 (150 mm in diameter, 170 mm in height, 25 holes). A sample of the mixed fuel coal was put into the hole making machine, and then hit by a wooden hammer several times, thereby producing a hole coal.

 The analysis results of the hole coal produced using the reference sample S1 (anthracite coal 100%) and each sample are shown in Table 5 below.

Analysis result of hole bullet sample Hole bullet Combustion
Remnants Calorific value
(kcal / kg) Compressive strength
(kg / ㎠) Height standard
(mm) weight
(kg) Tumble strength Combustion
Maintenance costs Combustion rate
(%) Compressive strength
(kg / ㎠) S1 4,539 4.90 142 3.61 pass 0.34 49.47 1.1 S5 4,087 4.60 152 3.46 pass - - 1.0 S6 4,179 4.93 150 3.57 pass 0.35 50.83 1.3 S10 4,831 4.83 150 3.37 pass 0.35 52.74 1.3 S11 4,611 4.43 148 3.36 pass - - 1.0 S12 4,346 4.10 150 3.60 fail - - 0.9

The height standard of the hole coal was measured after 20 days of drying at the room temperature and the production time of the hole coal. The measured dimensions were compared with the dimensions of the bullets produced from the anthracite base sample S1 and the mixed fuel coals (S5, S6, S10, S11, S12). There were no changes in diameter and height in the standard measurements of the bullets.

Compressive strength was analyzed by using the universal compressive strength test equipment (HS-1471) by measuring the strength of the standard sample S1 and the mixture of the coal and hole coal combustion residue made of mixed fuel coal. The test equipment is digitally electric. The body can be set in height according to the measurement sample using screws. The one-touch value is attached to the measurement unit so that the user can easily operate it and has a conversion function of an indicator.

The compressive strength was the average of three experimental tests of the compressive strength. The compressive strength formed by the mixed fuel coals S11 and S12 was lower than the standard value, but the values of S5, S6, and S10 represented about 90% or more of the reference sample, which caused problems in using the bullet. I do not think it will be.

Tumble strength is the strength that does not break when transporting and storing a bullet, and it is measured by the bullet test method KSE3732. As can be seen in Table 5, the slitting carbide produced by the S12 with more than 10% of the coal fell below the reference value, but the remaining four are not broken, it is determined that the fall strength is sufficient.

When the sample was dried for 20 days, the weight ratio (%) after drying to the weight before drying was calculated and compared with the reference sample (S1). The reference sample had a weight ratio of 91%, and the samples closest to the reference sample were S5, S6 and S10, showing 87%, 89% and 89%, respectively, and the remaining S11 and S12 samples were 86% and 80%, respectively. And a lot of difference.

The combustion duration ratio represents the weight / burning duration of a hole coal sample multiplied by 1,000. The combustion duration ratio was 0.34 for the reference sample S1, and 0.35 for the mixed fuel coals S6 and S10, respectively, indicating similar values to the reference sample.

The combustion rate was obtained by the formula 1- (burned residue weight / hollow weight) × 100. The reference sample (S1) was 49.8%, and the mixed fuel coals S6 and S10 were 50.8% and 52.7%, respectively.

As a result of measuring the compressive strength of the combustion residue, the compressive residue compressive strength of the reference sample (S1) was 1.1 kg / cm 2, and the compressive strengths of S6 and S10 were all 1.3 kg / cm 2, which was higher than that of the reference sample. S5 and S11 were close to the reference sample at 1.0 kg / cm 2, but S12 was significantly below the standard at 0.9 kg / cm 2.

As a result of comprehensive determination of the calorific value, compressive strength, specification, weight, tumble strength, combustion duration ratio, and combustion rate, the mixed fuel coal bore coal having the physical properties most similar to the reference sample S1 was produced by S6 and S10. Although the holes produced by S5 and S11 did not meet the specifications of the hole coal, it was confirmed that there is a possibility in the calorific value and the compressive strength, which are physical properties as the fuel pellets.

Although the above has been described with reference to an embodiment of the present invention, those skilled in the art may vary the present invention without departing from the spirit and scope of the present invention as set forth in the claims below. It will be appreciated that modifications and variations can be made.

Claims (13)

Dewatering and drying the sewage sludge;
Carbonizing the dried sewage sludge to produce sludge carbide;
Mixing the sludge carbide, anthracite coal and charcoal to produce a mixed fuel coal; And
Manufacturing a hole coal of a predetermined size using the mixed fuel coal;
The mixed fuel coal is a coal production method using sewage sludge containing 70 to 90% by weight of the anthracite coal.
delete The method of claim 1,
The mixed fuel coal production method, characterized in that the charcoal contains 5 to 15% by weight.
The method of claim 1,
A combustion gas cooling step of cooling the high temperature combustion gas generated while generating the sludge carbide,
Combustion gas treatment process for removing the harmful substances contained in the cooled combustion gas further comprising a mixed fuel coal production method.
The method of claim 1,
Method for producing a mixed fuel coal, characterized in that the dehydrated sludge is dried at 250 ~ 350 ℃ and carbonized at 700 ℃ or less.
delete delete Dewatering and drying the sewage sludge;
Carbonizing the dried sewage sludge to produce sludge carbide;
Mixing the sludge carbide and anthracite to produce a mixed fuel coal; And
Manufacturing a hole coal of a predetermined size using the mixed fuel coal;
The mixed fuel coal is a coal production method using sewage sludge containing 80 to 90% by weight of the anthracite coal.
delete The method of claim 8,
A combustion gas cooling step of cooling the high temperature combustion gas generated while generating the sludge carbide,
Combustion gas treatment process for removing the harmful substances contained in the cooled combustion gas further comprising a mixed fuel coal production method.
The method of claim 8,
Method for producing a mixed fuel coal, characterized in that the dehydrated sludge is dried at 250 ~ 350 ℃ and carbonized at 700 ℃ or less.
delete delete

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