KR101041171B1 - Method for preparing sewage sludge fuel for the blended combustion at coal fired plant using microwave - Google Patents

Abstract

In order to use the domestic sewage sludge as a mixed fuel of a coal-fired power plant, the present invention applies a sludge having a moisture content of 80% or more to a microwave heat source and a mixture of hydrophobic bituminous coal and anthracite to 150 ° C or lower, which is 250 ° C or lower than the conventional 400 ° C. It is to provide a method for producing sewage sludge coal for coal-fired power plant mixed combustion by drying at a temperature and a manufacturing apparatus for performing the method.

Sewage Sludge, Microwave, Drying Reactor, Hydrophobic, Bituminous Coal, Anthracite

Description

Method for preparing sewage sludge fuel for the blended combustion at coal fired plant using microwave}

The present invention relates to a method for producing sewage sludge coal for coal-fired power plant mixed combustion by applying a microwave heat source. More specifically, in order to use domestic sewage sludge as a mixed fuel of a coal-fired power plant, the present invention uses a microwave heat source and a hydrophobic bituminous coal or anthracite blending technology to make the sludge having a moisture content of 80% or more than conventional 400 ° C. The present invention relates to a method for producing sewage sludge coal for coal-fired power plant mixed combustion by drying at a temperature not lower than 250 ° C and lower than 150 ° C.

Globally, about 80% of total energy demand depends on fossil fuels, and about 50% of fossil fuels depend on coal. In Korea, about 30% of the total electricity production is expected to remain coal. Environmental problems are with injuries as a major theme of the 21st century, emissions of harmful air pollutants caused by burning of fossil fuels is a problem which the regulation is gradually strengthening, in recent years, and is subject to enhanced regulation on SO ₂ and NO _x, CO ₂ regulations have also been implemented since 2013.

Biomass is the third most abundant energy source in the world after coal and oil. It accounts for about 1,250 million TOE, or about 14% of the world's energy.In developing countries, about 35% of the total energy is supplied as biomass, and in developed countries, it is an important energy source. Biomass supplies about 70 to 40 million TOEs and about 20 to 40 million TOEs in Europe. Biomass includes traditional agricultural by-products and energy crops, including sludge and waste, except fossil fuels.

In particular, in the US, Sewage Sludge Combustion Research conducted by DOE and EPRI in the US and EU in Europe regarding sewage sludge, which is a domestic waste, is not only effective for power plants but also environmentally effective when applied to large-scale pulverized coal plants. Was concluded.

In Korea, since July 2001, sludge from discharged facilities of a certain size has been prohibited from landfilling. Recently, due to the strengthening of the sludge treatment regulations, the wastes to be disposed of are being recycled as resources using sludge properties that contain a large amount of flammable organic substances, and are also called biosolids instead of sludge. Accordingly, the government aims to supply renewable energy, including sewage sludge fuel, in 2011, with 5% of primary energy and 7% of electricity production. According to the agreement ('05 .7.25), the company is investing in renewable energy with a goal of 1.1 trillion won by 2008.

In particular, power generation companies are planning to build RDF and sewage sludge fuel power plants by 2011, and are conducting joint research with the Korea Electric Power Research Institute to apply coal-fired power plant sites for sewage sludge coal fueling. However, most of organic sludge, mainly sewage and wastewater sludge, generated about 6.5 million tons annually in Korea, has a water content of 70 to 80% and cannot be used as a fuel immediately. It is about 4,000kcal / kg, so it is inferior in self-firing property and its combustion characteristics are completely different from the existing solid fossil fuels. Therefore, in order to use it as a fuel in a combustion furnace that uses an independent fuel and uses existing fossil fuels, it is necessary to reinforce the calorific value and maintain it at 4,500 kcal / kg or more, and correct the combustion characteristics similar to that of bituminous coal or anthracite coal. I need to give.

Table 1: Various sewage sludge moisture content by drying and applicable aftertreatment process

Water content Post-processing example 60 to 65% Applicable fluidized bed incinerator 45 to 35% Can be incinerated with general waste 25-15% Incineration molten fuel, cement waste incineration and molten fuel in cement kilns, composting below 10 Coal-fired Power Plant Combustion Fuel

In particular, in order to fuel the sewage sludge coal-fired power plant, the water content should be lowered to 10% or less as shown in Table 1 above. However, the water in the sludge is divided into free water, internal water (gap water), surface water, and bonded water as shown in FIG. 1, and a large part of the water of sludge is free water and surface water attached to the sludge surface. The water present between the molecule and the molecule is the internal water, and the bound water is chemically bound to the sludge molecule. Sewage sludge free water and surface water are dried at 100 ± 5 ℃, but internal and combined water are destroyed and dried at about 400 ℃, so it is difficult to maintain this high temperature up to the inside of sludge by conventional drying methods.

The present invention devised to improve these problems is applied to the heat source application technology during extraction by applying a microwave heat source rather than a direct or indirect heating method such as heating furnace and electric furnace, the moisture content of more than 80% hydrophobic bituminous coal and silver anthracite coal The purpose of the present invention is to provide a method for manufacturing sewage sludge coal for coal-fired power plant by mixing at 150 ° C or lower, which is 250 ° C or more lower than 400 ° C.

The method for producing sewage sludge coal for coal-fired power plant mixed combustion according to the present invention is a microwave drying reactor having a low dielectric constant of Teflon that transmits microwaves by mixing sewage sludge having a water content of 80% or more with hydrophobic bituminous coal and anthracite coal. Supplying to;

Supplying microwaves while stirring the mixture of sewage sludge, bituminous coal and anthracite coal at a speed of 200 to 500 rpm in the microwave drying reactor;

The water content is made of sewage sludge of 10% or less by drying the water at a temperature of 150 ° C. or less by drying the insoluble water of the pore water, the capillary coupling water, and the internally held water of the sewage sludge which is decomposed and dried at 400 ° C. or more by the microwave heat source. Making; And

Discharging the dried sewage sludge is characterized in that consisting of a step of crushing with a grinder.

According to the method of the present invention, the mixing ratio of the bituminous coal and anthracite coal is preferably mixed at 5 to 15% by weight based on the total mixture, and the drying step of the sewage sludge is 0.15 to 1 hour in a temperature range of 105 to 150 ° C. It is characterized by drying during.

In addition, the apparatus for producing sewage sludge coal for coal-fired power plant mixed combustion using a microwave heat source according to the present invention is a rotary sewage sludge conveying belt conveyor, bituminous coal and anthracite storage hopper for supplying sewage sludge containing 80% or more moisture. Diaphragm for supplying appropriate amount by valve, wet sewage sludge conveying belt conveyor and wet sewage sludge supplied from diaphragm, inlet for injecting bituminous coal and anthracite, moist sewage sludge introduced through the inlet, bituminous coal and anthracite mixture Raw material supply unit consisting of a screw feeder for transferring the feed to the microwave reactor,

A dry reaction part including a wet sewage sludge supplied from the raw material supply part and a microwave drying reaction device for drying by applying a microwave heat source to the bituminous coal and anthracite mixture;

Sludge moisture consisting of a condenser 39 for condensing the vapor evaporated in the microwave reactor with the cooling water supplied by the steam cooling water storage tank for storing the condensed vapor evaporated and dried in the drying reaction unit, the cooling water supply pump Recovery section,

It consists of a dry sludge coal crusher for pulverizing the sewage sludge is dried and manufactured in the microwave reactor to 200mesh powder of the thermal power plant fuel standard and a pulverized dry sewage sludge coal transport device for transferring the crushed sludge coal to the storage hopper. It is characterized by consisting of sewage sludge coal processing unit.

According to the apparatus of the present invention, the microwave drying reactor is composed of a microwave supply cavity and a microwave drying reactor in which a microwave supplier is installed.

The microwave supply pupil is a supply for supplying a microwave heat source, a microwave supply for supplying microwaves into the microwave drying reactor, a microwave reflection stirrer for reflecting the microwaves reflected and transmitted from the upper lower plate back to the reactor, the reactor Dry steam outlet made of aluminum oxide to help discharge dry steam generated from inside, sludge feeder for supplying bituminous coal and anthracite and sludge feedstock, the feeder for feed, agitator shaft insert, dry steam outlet The microwave leakage choke is attached to the

The microwave drying reactor is a microwave reaction unit, made of a low dielectric constant Teflon material for the purpose of permeation of microwaves, a raw material supply pipe supplied with wet sewage sludge and additives such as bituminous and anthracite, and the raw material mixture is stirred. Stainless steel stirrer connected to the stirrer shaft for microwave reflection role, stainless steel shielded thermocouple thermometer for controlling microwave output by measuring temperature inside microwave drying reactor, dry steam discharge pipe for evaporation of dry moisture, water content 10 Dry sludge discharge valve for discharging sewage sludge coal dried to less than%, characterized in that it consists of a screw feeder for transporting the sludge discharged from the dry sludge discharge valve to the grinder.

In addition, the microwave supply pupil plate of the microwave supply pupil is made of aluminum material having a high microwave transmission resistance, and the dry water vapor outlet is made of aluminum oxide material that does not transmit microwave to prevent leakage to the outside of the microwave supply pupil. have.

The manufacturing technology of sewage sludge coal for coal-fired power plant mixed combustion using a microwave heat source according to the present invention uses friction force by molecular rotation or rearrangement at a speed corresponding to the frequency of electromagnetic waves of microwaves, compared to conventional thermally conductive heating. It is possible to rapidly increase the temperature, and to dry sewage sludge at a low temperature of 150 ° C. or less for a short time of 1 hour or less, which can reduce unnecessary calorie consumption, while having a very low moisture content of 10% or less and a superior combustion fuel. There is an effect that can produce sewage sludge coal suitable as a fuel for the combined combustion power plant of thermal power plant.

The method for producing sewage sludge coal for coal-fired power plant mixed combustion of the present invention is characterized in that the application of a heat source during extraction is applied to a microwave heat source, not a direct or indirect heating method such as a heating furnace and an electric furnace. That is, microwaves are a kind of electromagnetic waves (300 MHz to 300 GHz) located between far infrared rays and radio waves (high frequencies) in the spectrum. The biggest feature of microwave is that the heating method uses friction force by molecular rotation or rearrangement as much as speed corresponding to the frequency of electromagnetic wave, so that it can raise the temperature faster than conventional thermal conductive heating.

In addition, microwave energy has low energy that does not damage chemical bonds, and thus does not alter or destroy molecular structure. Because of the rapid temperature rise and chemical stability, microwave technology has already been applied in various chemical fields. In addition, the principle of the microwave is a material having a low dielectric constant (permeability) transmits microwaves, but in the case of the combined moisture such as water, a polar solvent having high transmittance, it is used as a heating source.

On the other hand, materials such as sludge organic materials have the property of transmitting microwaves. Therefore, in the case of microwave drying equipment, the material properties and the physicochemical properties of the sludge to be dried should be considered.

In addition, the present invention is characterized by applying a technique utilizing the difference in the wettability (Wettability) of the carbon component of the hydrous and anthracite coal having hydrophobicity and hydrophilicity. The reaction mechanism is shown in FIG. In order to increase repulsion and repulsion between hydrophilic bonded water and hydrophobic carbon components, a certain amount of bituminous or anthracite is used as a catalyst, which increases hydrophobicity with bound moisture and increases surface tension to prevent decomposition with sludge. Promote At this time, the irradiated microwaves increase the molecular rotational power of the bonded water such as the pore water and the capillary bond water to dry the bound water and the capillary water at a temperature of 150 ° C. or lower to be ejected as steam.

Method for producing sewage sludge coal for coal-fired power plant mixed combustion using a microwave heat source according to the present invention by mixing sewage sludge having a water content of more than 80%, hydrophobic bituminous coal and anthracite coal 5 to 15% by weight relative to the total weight fraction The microwave is fed to a microwave drying reactor made of a low dielectric constant teflon that transmits microwaves, and then the microwave is supplied while stirring the mixture of sewage sludge, bituminous coal and anthracite coal at a speed of 200 to 500 rpm.

The sewage sludge used in the present invention is composed of a high polar solvent absorbing microwaves, pore water, combined moisture, and internally held water. Therefore, when microwave irradiation, moisture absorbs microwaves and increases molecular rotational power, thus exothermic reaction in moisture itself. It is possible to decompose and dry the bound water and the capillary bound water even at the following low temperatures. At this time, the carbon component of the bituminous coal and anthracite coal having hydrophobicity to be added serves as a catalyst that acts to push the decomposed water to the outside of the sludge solid by generating a repulsive force / repulsive force with the combined water having hydrophilicity.

Difficult water of pore water, capillary coupling water, and internal holding water of sewage sludge which is decomposed and dried at 400 ° C. or higher by the microwave heat source is 150 ° C. or lower, preferably at a temperature of 105 to 150 ° C. for 0.15 to 1 hour. By drying, the water content is made of sewage sludge coal of 10% or less, and the dried sewage sludge coal is discharged and pulverized by a pulverizer.

The apparatus for producing sewage sludge coal for coal-fired power plant mixed combustion using the microwave heat source of the present invention will be described in detail with reference to the accompanying drawings.

3 is a view schematically showing an apparatus for producing sewage sludge coal for combined combustion of a thermal power plant using sewage sludge as a raw material. 3 is a device for carrying out a process for manufacturing and drying sewage sludge having a water content of 80% or more with sewage sludge coal for thermal combustion-fired mixed combustion having a water content of 10% or less, and mixing a microwave heat source and hydrophobic bituminous coal or anthracite coal. Through the decomposable and dried at 400 ℃ or more, the hardly decomposable moisture such as pore water, capillary coupling water, internal holding water and the like to be dried below 150 ℃.

The sewage sludge drying process by applying microwave heat source and mixing petroleum / anthracite coal according to the present invention is combined with free water and surface attachment water outside the sludge solid which is dried in the range of 105 ± 5 ° C, and drying is performed at 400 ° C or higher. It is characterized in that the gap water, the capillary coupling water, the internal holding water is made in a short time at 150 ℃ or less.

Apparatus for manufacturing sewage sludge coal for thermal power plant mixed combustion using sewage sludge as a raw material by applying the developed microwave heat source according to the present invention is illustrated in FIG.

Microwave reaction of wet sewage sludge conveying belt conveyor (31) for supplying sewage sludge containing more than 80% moisture, inlet (32) for injecting the conveyed wet sewage sludge and petroleum / anthracite coal, and injected sludge and petroleum anthracite mixture In order to inject a predetermined amount of bituminous coal into the screw feed device 33 and the inlet 32, the bituminous coal storage hopper 34, a rotary valve 35 for discharging coal ash and the rotary valve 35 are provided. A raw material supply part including a petroleum / anthracite additive supply part comprising a diaphragm 36 for supplying bituminous coal at an appropriate amount by a;

A drying reaction part including a wet and dry sewage sludge supplied from the raw material supply part and a microwave drying reaction device 30 for drying by applying a microwave heat source to the oil / anthracite mixture;

Steam cooling water storage tank 37 for condensing and storing the vapor evaporated and dried in the drying reaction unit, a cooling water supply pump 38 for transferring the cooling water of the steam cooling water storage tank 37 to the condenser, the cooling water supply pump 38 A sludge water recovery unit comprising a condenser 39 which serves to make the vapor evaporated from the microwave reactor 30 into condensed water with the cooling water supplied by the condensed water;

The sewage sludge coal dried and manufactured by the microwave reactor 30 is transferred, and the dry sludge coal crusher 40 and the crushed sludge coal are crushed into a 200-mesh powder passing through a thermal power plant as a storage hopper 41. Characterized in that it consists of a sludge coal processing unit composed of a pulverized dry sludge coal conveying device 42 for conveying.

4 is a detailed view of the microwave reactor 30, which is the core of the components of the present invention. The microwave supply cavity 301 is a microwave feeder 303 for feeding microwaves into the drying reactor 302 and some microwaves reflected from the upper and lower plates and transmitted through the reactor 302 back to the reactor. Dry steam outlet 305 made of aluminum oxide material through which microwaves are not transmitted to prevent leakage to the outside of the microwave supply cavity 301 through the microwave reflection stirrer 304 and the upper contact portion of the microwave drying reactor 302. ), A sludge raw material supply port 306 for supplying an additive bituminous coal and a sludge raw material, and an aluminum microwave on the surface of the raw material supply port 306, the stirrer shaft inserting hole 307, and the dry steam discharge port 305. A microwave supply section to which the leakage choke 308 is attached;

A raw material supply pipe 309 made of Teflon material having a low permittivity for permeation of the supplied microwave and supplied with wet sewage sludge to be dried and an oil / anthracite as an additive, and the microwave drying reactor 302. The temperature inside the microwave stirrer 311 and the stainless steel stirrer connected to the stirrer shaft 310 for the infiltration of the sludge and the bituminous coal and the penetration of the combined moisture and the microwave reflection role are measured. Stainless steel shielded thermocouple thermometer 312 to control microwave output, dry steam discharge pipe 313 to reduce moisture content due to evaporation of dry water, and dry sludge to discharge sewage sludge coal dried below 10% moisture content Discharge valve 314, dry sludge discharged from the discharge valve 314 to the screw feeder 315 for transferring the sludge coal discharged to the grinder Characterized in that part it becomes has done microwave reaction that is sex.

The main part of the present invention, the microwave supplying pupil plate 316 is made of aluminum material having high microwave transmission resistance to block external leakage of microwaves, and the microwave drying reactor 302 uses microwaves having a high microwave transmittance in the microwave. Is configured to penetrate smoothly and prevent erosion of the reactor.

Such a method for producing sewage sludge coal from wet sewage sludge to which the microwave according to the present invention and an apparatus for performing the same will be described in more detail based on the following examples.

Experimental Example

In the configuration of the microwave reactor 30 as shown in FIG. 4, the microwave feeder 303 is 2.45 GHz, 2 kW, 220 V, single phase, and the volume of the microwave drying reactor 302 is 2 L, 20 cm in diameter, microwave reflection stirrer. The rotation speed of the 304 is 100 ~ 500rpm variable, the thermometer used a stainless steel shielded thermocouple thermometer 312, the diameter of the dry steam outlet 305 and the sludge raw material supply port 306 is 2 inches, shielded thermocouple The diameter of the installation unit of the thermometer 312 is composed of 1cm, the experimental conditions and the results are as follows.

Experimental conditions

Wet sewage sludge used in the experiment is shown in Table 2 below. In the case of sewage sludge, the moisture content is about 79.99 (about 80)%, and the heat content is 3,660Kcal / kg, which is similar to anthracite coal. . In the case of imported bituminous coal used as an additive, moisture was less than 0.5% and the calorific value was 6,990 Kcal / kg. On the other hand, the test conditions were 1.5 kg of Daejeon sewage sludge with a moisture content of about 80% and 150 g of bituminous coal as a raw material, followed by drying reaction at 150 ° C. for 30 minutes.

Table 2. Characteristics of sewage sludge to be dried and added coal briquettes

Kinds Calorie
(Kcal / Kg) V.M. (%) F.C (%) Ash (%) Water (%) compare Daejeon Sewage Sludge 3,660 10.85 2.02 7.14 79.99 91.1 wt.% Bituminous coal 6,990 36.00 54.30 9.20 0.50 8.9 wt.%

☞ Calorific Value: Dry base

Experiment result

Table 3. Characteristics of Sewage Sludge

Kinds Calorie
(Kcal / Kg) V.M. (%) F.C (%) Ash (%) Water (%) compare Dry sewage sludge 4,650 42.25 22.07 25.88 9.80

As a result of drying the sewage sludge through the application of microwave heat source and mixing bituminous coal, the moisture content was very low as 9.8% as shown in Table 3, and the calorific value was 4,650 Kcal / kg, which was much higher than the raw sewage sludge.

On the other hand, in the case of sewage sludge coal, as shown in Figs. 5 and 6, the fixed carbon of the amorphous phase (Amorphous Phase) appeared to be the main component, the crystalline form showed the form of agglomerated fine particles. On the other hand, in the case of metal materials, as shown in FIG. 7, coal ash components of various minerals (Si, Al, Mg, Na, Fe, etc.) in addition to crystalline fixed carbon are identified as the composition of bituminous coal and anthracite coal. It was confirmed that it was suitable as.

In addition, as a result of analysis of the heat loss curve of sewage sludge coal as shown in FIG. 8, the dehydration of free water is made within 10% of the range near 90 ° C., similarly to bituminous coal. The combustion reaction occurs and the complete combustion reaction of fixed carbon occurs in the range of 420 ~ 500 ℃, and the combustion tendency is the same as that of bituminous coal or anthracite coal.

1 is a schematic diagram of the water-bonded form of sewage sludge coal.

Figure 2 is a schematic diagram showing the effect of the coal briquettes mixed on the combined water during drying.

Figure 3 is a schematic diagram of the overall manufacturing apparatus of sewage sludge coal according to the present invention according to the present invention.

4 is an enlarged detailed view of the microwave reactor of FIG. 3.

5 is a SEM photograph for showing the crystalline form of sewage sludge coal according to the present invention.

6 is a graph showing the XRD analysis result of FIG.

7 is a graph showing the results of EDS analysis of sewage sludge coal according to the present invention.

8 is a graph showing the heat loss curve test results of sewage sludge coal according to the present invention.

<Description of the symbols for the main parts of the drawings>

30 ---- microwave reactor

31 ---- Wet Sludge Transfer Belt Conveyor

32 ---- Slot

33 ---- Screw Feeder

34 ---- Bituminous Coal Storage Hopper

35 --- rotary valve

36 --- diaphragm

37 ---- Steam coolant reservoir

38 ---- Chilled water supply pump

39 ---- condenser

40 ---- dry sludge coal crusher

41 ---- storage hopper

42 ---- Dry Sludge Feed System

301 ---- microwave supply pupil

302 ---- microwave drying reactor

303 ---- microwave feeder

304 ---- microwave reflective stirrer

305 ---- Dry steam outlet

306 ---- Feeding port

307 ---- Stirrer Shaft Insert

308 ---- Microwave Leakage Choke

309 ---- raw material supply pipe

310 ---- Stirrer Shaft

311 ---- Stirrer

312 ---- shielded thermocouple thermometer

313 ---- dry steam discharge pipe

314 ---- dry sludge discharge valve

315 ---- Screw Feeder

316 ---- microwave supply pupil plate

Claims (7)

In the method for producing sewage sludge coal for coal-fired power plant by applying microwave heat source by pulverizing sewage sludge produced by supplying microwaves to the sewage sludge mixture with water content of 80% or more and drying at a temperature of 150 ° C. or lower. The sewage sludge is mixed with hydrophobic bituminous coal and anthracite coal at 5 to 15% by weight based on the total mixture, and the mixture is supplied with microwaves while stirring at 200 to 500 rpm, and the microwave heat source is used at 105 to 150 ° C. Method of producing sewage sludge for coal-fired power plant mixed combustion by applying a microwave heat source, characterized in that the drying under temperature to produce a water content of less than 10% sewage sludge coal and pulverized. delete delete delete delete delete delete

Images