JP6562846B2 - How to make organic sludge into fuel - Google Patents

Description

  The present invention relates to a method for converting organic sludge such as sewage sludge into fuel.

  Conventionally, in order to effectively use organic sludge such as sewage sludge as a fuel, Patent Document 1 and the like describe that water-containing sludge such as sewage sludge remains in the form of a water-containing slurry in the kiln bottom of a kiln or calcined Techniques have been proposed in which fuel is directly input to the furnace.

  However, in the method described in Patent Document 1, since the organic sludge is put into the kiln bottom of the cement kiln in the form of a water-containing slurry, the amount of heat is lost due to the moisture in the organic sludge, resulting in a decrease in cement production efficiency. Cause inconvenience.

  Therefore, Patent Document 2 discloses a method for treating organic sludge in which air is aerated from below the organic sludge and the organic sludge is subjected to aerobic fermentation, and the moisture of the organic sludge is reduced by drying with air and heat of fermentation by aerobic fermentation. Is described.

  Further, Patent Document 3 discloses that a fermented organic sludge is fermented using a hyperthermophilic bacterium in an idle horizontal mill for cement raw material, and a calorific value adjusting agent such as flammable waste or solid fuel is added to the fermented organic sludge. A method for converting organic sludge into a fuel is proposed in which the amount of heat is adjusted by adding odor to deodorize the odor gas generated by fermentation with an oxidation catalyst.

  On the other hand, odorous gas generated by aerobic fermentation of organic sludge can be processed at low cost by biological deodorization. In Patent Document 4, organic waste is supplied to a fermentation cracking tank whose internal temperature is adjusted to about 60 ° C. by a heater, and the organic waste is stirred in the fermentation cracking tank and aerated. An organic waste treatment method is described in which organic waste is subjected to aerobic fermentation using thermophilic bacteria, and odorous gas containing ammonia generated by fermentation is introduced into a nitrification tank to perform biological deodorization treatment. Further, this document describes that even if the ammonia concentration in the odor gas is about 1000 ppm, it can be dealt with by continuously sprinkling water in the nitrification tank.

Japanese Patent No. 3933194 Japanese Patent Laying-Open No. 2015-213879 JP 2013-072051 A JP 2003-80206 A

  As described above, in order to effectively use organic sludge such as sewage sludge as fuel, it is necessary to reduce the water content of organic sludge.

  Further, in the method described in Patent Document 3, sludge is composted using a cement raw material mill and is put into the kiln as fuel. However, since the cement raw material mill generally has a small equipment capacity, the amount of fermentation treatment is low. Low. Moreover, since it takes one to two months for composting of sludge, it takes the equipment and labor for storage, and the equipment cost and the operating cost increase.

   Furthermore, in the method described in Patent Document 4, when the ammonia concentration in the odor gas is large, a large amount of water is required for watering. In addition, the ammonia concentration of the odor gas introduced into the biological deodorization treatment tank such as a nitrification tank is preferably 200 ppm or less in consideration of the deodorization function of the biological deodorization treatment tank. Therefore, when the ammonia concentration of the odor gas exceeds 200 ppm, it is necessary to dilute the odor gas in advance, and the equipment / operating cost is increased accordingly.

  Then, this invention is made | formed in view of the problem in the said prior art, Comprising: It aims at making organic sludge into fuel at low cost.

In order to achieve the above object, the present invention is a method for fuelizing organic sludge, wherein the organic sludge is deposited in an indoor yard, and the organic sludge is generated in a cement firing device or a power generation device. A high temperature gas of not less than 140 ° C. and not more than 140 ° C. is ventilated at a rate of more than 0.4 m ³ / min and less than 1.0 m ³ / min per 1 m ^{3 of the} organic sludge, and the heat of fermentation by aerobic fermentation is used. It is characterized by reducing the moisture of organic sludge and using it as fuel.

  According to the present invention, the water content of the organic sludge is merely reduced by using the heat of fermentation by drying with a high-temperature gas or aerobic fermentation, so that a long treatment period such as when composting is unnecessary. A treatment period of 1 day to 4 days is sufficient, heat loss can be suppressed, and organic sludge can be made into fuel at low cost. Moreover, a large amount of processing is possible by using an indoor yard.

Regarding the amount of gas, from the viewpoint of deodorizing equipment and operating costs, it is basically preferable to vent the necessary minimum amount as described in Patent Document 2, but high-temperature gas is reduced to 0.000 per m ³ of organic sludge. Ammonia concentration in odor gas while effectively using high-temperature gas to reduce moisture in organic sludge without diluting odor gas in advance by aeration at a rate exceeding 4 m ³ / min and 1.0 m ³ / min or less Can be reduced to about 200 ppm or less, and organic sludge can be treated efficiently and at low cost.

  Furthermore, a relatively low-temperature gas that is difficult to use can be used to recover heat of 50 ° C. or more and 140 ° C. or less generated in a cement baking apparatus or power generation apparatus as the high-temperature gas, for example, aerobic fermentation or the like is performed. Equipment adjacent to the indoor yard can be used.

  In the method for converting the organic sludge into fuel, the organic sludge can be deposited in the indoor yard after adding moisture adjusting material as necessary to improve the air permeability and handling of the organic sludge.

Further, the amount of aeration of the high-temperature gas to the organic sludge can be adjusted by the ammonia concentration, the CO ₂ concentration or the decomposition degree of the organic sludge after the high-temperature gas is passed through the organic sludge. .

  Furthermore, moisture in the atmospheric gas of the indoor yard can be condensed and recovered, and by actively recovering moisture evaporated from the organic sludge, the moisture reduction rate of the organic sludge can be increased, This leads to an increase in throughput. The recovered water is effectively used as at least one of diluting water for denitration agent used in cement production, lubricating water used for transporting the organic sludge, cooling water for heat exchange pipes, and water for water spraying in biological deodorization tanks. be able to.

  The odor gas generated by the aerobic fermentation can be deodorized, and environmentally friendly organic sludge can be made into fuel.

  The aerobic fermentation can be performed by a hyperthermophilic bacterium. By using a hyperthermophilic bacterium, fermentation is efficiently promoted in a high temperature range (above 85 ° C) that cannot be expected by normal fermenting bacteria. It becomes possible to reduce between.

  As described above, according to the present invention, organic sludge can be made into fuel at low cost.

It is a whole block diagram which shows the installation which applied the fuel conversion method of the organic sludge concerning this invention.

  Next, an embodiment for carrying out the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows an example of equipment to which the method of fueling organic sludge according to the present invention is applied. This fueling equipment 1 is provided in a cement manufacturing factory or adjacent to a cement manufacturing factory, and uses an abandoned house or the like. The indoor yard 2 includes a high-temperature gas supply unit 8 for ventilating the high-temperature gas G1 to the organic sludge S such as sewage sludge, a cooling pipe 3 and a scraper 4 above the indoor yard 2, A condensate tank 5 and a biological deodorization treatment tank 6 are provided outside the building 7 surrounding 2. Here, the organic sludge refers to those that can be fermented with sewage sludge, papermaking sludge, billpit sludge, food sludge, digested sludge, municipal waste (household waste), and the like.

  The high-temperature gas supply unit 8 vents the high-temperature gas G1 generated in the cement baking apparatus or the power generation apparatus at 50 ° C. or more and 140 ° C. or less into the organic sludge S accumulated in the indoor yard 2. A plurality are provided. The high temperature gas G1 is introduced from a high temperature gas source (not shown) below the high temperature gas supply unit 8.

  The cooling pipe 3 is provided in order to condense and collect the moisture in the gas in the building 7 such as the water that has flowed through the pipe and the water evaporated from the organic sludge S, and a plurality of cooling pipes 3 are provided in the building 7. It is juxtaposed horizontally below the ceiling. Note that the cooling pipe 3 may also be provided in the vertical direction to have a mesh shape.

  The scraper 4 is provided for collecting the water adhering to the surface of the cooling pipe 3 and transporting it to the condensed water tank 5, and moves along the surface of the cooling pipe 3 in the direction of arrow M in FIG.

  The condensed water tank 5 is provided for storing the recovered water W by the cooling pipe 3 and the scraper 4, and the recovered water W is used in the fueling facility 1, cement manufacturing factory, and the like as will be described later.

  The biological deodorization treatment tank 6 is provided to remove ammonia in the odor gas G2 generated during the fermentation treatment of the organic sludge S in the building 7. The biological deodorization treatment tank 3 contains microorganisms such as nitrifying bacteria and denitrifying bacteria, and these microorganisms decompose odor components such as ammonia. In addition, the biological deodorization treatment tank 3 includes a water sprinkling unit (not shown) that sprinkles water to maintain these microorganisms. In addition, without installing the biological deodorization treatment tank 6, the odor gas G2 can be treated by an adjacent cement burning apparatus in operation.

  Next, a method for fuelizing organic sludge using the fueling facility 1 having the above configuration will be described with reference to FIG.

  The wood sludge, waste tatami, etc. are added to the received organic sludge as moisture adjusting material, if necessary, and then deposited in the indoor yard 2. The hot sludge S is passed through the sludge S through the high temperature gas supply unit 8 and dried. In addition, the organic sludge S is aerobically fermented using a hyperthermophilic bacterium, and the moisture of the organic sludge S is reduced using the heat of fermentation. The fermentation of the organic sludge S here is not for the purpose of fermentation itself, but for the purpose of reducing the water content of the organic sludge S using the heat of fermentation. The hyperthermophilic bacterium has a feature that enables aerobic activity and fermentation even in a high temperature range (85 ° C. or higher) that cannot be expected to be raised by ordinary fermenting bacteria.

  Here, it is preferable to use a high-temperature gas G1 having a temperature of 50 ° C. to 140 ° C., having a low moisture content, and an oxygen content that is substantially the same as that of atmospheric components. By using the thing of this temperature range, while reducing the water | moisture content of organic sludge S efficiently compared with normal temperature gas, the heat loss of the apparatus which discharge | emits high temperature gas G1 can be suppressed low. . In addition, the high temperature gas G1 having a low moisture content is more effective in reducing the moisture content of the organic sludge S. By using a gas having an oxygen content of about 20%, which is substantially the same as that of atmospheric components, The fermentation efficiency of the sludge S can be improved.

  Examples of the exhaust gas of the cement firing device used as the high-temperature exhaust gas G1 include clinker cooler exhaust gas, cement kiln exhaust gas, boiler exhaust gas attached to the cement firing device, and chlorine bypass exhaust gas. Considering the amount and oxygen content, the exhaust gas from the clinker cooler and the chlorine bypass indirect cooler is optimal.

  Furthermore, by using a hyperthermophilic bacterium for fermentation of the organic sludge S, the water content of the organic sludge S can be reduced more efficiently than normal aerobic fermentation. In the indoor yard 2, it is not necessary to compost the organic sludge S, and it is only necessary to reduce the moisture by using fermentation heat.

The amount of hot gas G1 to vent to the organic sludge S adjusts the airflow rate per organic sludge S1m ³ to 0.4~1.0m ³ / min. The aeration rate per organic sludge S1m ³ 0.2~0.4m ³ / min by adjusting suppressing the ventilation gas amount, although it is possible to optimize the balance of the water reduction effect drying by fermentation, generating In some cases, the ammonia concentration of the odor gas G2 is as high as about 400 ppm. In that case, if the odor gas G2 is diluted in advance before being introduced into the biological deodorization treatment tank 6 as in the prior art, the equipment and operation costs are increased accordingly.

Therefore, in the present invention, such a case in consideration of increasing the airflow rate per organic sludge S1m ³ to 0.4~1.0m ³ / min, without diluting the pre-odorous gas G2, the hot gas Organic sludge can be treated efficiently and at low cost by making the ammonia concentration in the odor gas G2 about 200 ppm or less while effectively using G1 to reduce the water content of the organic sludge S.

For example, if the aeration amount of the hot gas G1 per organic sludge S1m ³ is 200ppm ammonia concentration in 0.3 m ³ / min is no problem even if it is introduced into the odorous gas G2 to the biological deodorization treatment tank 6 When the ammonia concentration rises to 400 ppm with the above air flow, in order to dilute the odor gas G2 in advance before being introduced into the biological deodorization treatment tank 6, a high-temperature gas G1 of 0.3 m ³ / min (ammonia concentration 0 ppm) Must be introduced into the odor gas G2 as a gas for dilution, and the equipment and operating costs increase accordingly.

Therefore, instead of using the high-temperature gas G1 of 0.3 m ³ / min as the dilution gas, the organic sludge S is added to the organic sludge S together with the original high-temperature gas G1 of 0.3 m ³ / min that was originally vented to the organic sludge S. By reducing the ammonia concentration in the odor gas G2 to about 200 ppm or less while effectively ventilating and reducing the water content of the organic sludge S, the organic sludge can be treated efficiently and at low cost. The amount of aeration of the high temperature gas G1 to the organic sludge S is adjusted by monitoring the CO ₂ concentration or the decomposition degree of the organic sludge S in addition to the ammonia concentration after the high temperature gas G1 is passed through the organic sludge S. You can also

  Along with the fermentation of the organic sludge S, cooling water is allowed to flow through the cooling pipe 3, and the atmospheric gas in the indoor yard 2 is cooled at the surface of the cooling pipe 3, so that moisture in the gas is condensed on the surface of the cooling pipe 3. Adhere to. Therefore, the scraper 4 is moved along the cooling pipe 3 in a direction close to the condensed water tank 5 to collect the water adhering to the surface of the cooling pipe 3 and transported to the condensed water tank 5 for storage.

  The recovered water W once stored in the condensed water tank 5 is diluted water of a denitration agent used at the time of cement production, lubricating water for improving handling when sludge is transported to a cement manufacturing factory, and cooling water for heat exchange pipes. In addition, it can be effectively used for watering in a biological deodorization tank.

  The odor gas G2 discharged from the building 7 is decomposed in the biological deodorization treatment tank 6 and then released to the atmosphere, and the organic sludge discharged from the indoor yard 2 is granulated together with a calorific value adjusting material with a pressure molding device or the like. Granulated fuel can be used as fuel in cement firing equipment and the like. Although organic sludge can be used directly as a fuel for cement kilns and calciners, the amount of heat generated by itself is not so high, so if it is used for other purposes, it generates heat before pressure molding. The amount of heat is adjusted by adding a quantity adjusting material. As the calorific value adjusting material, combustible waste such as waste plastics, paint residue, and waste oil, solid fuel, and the like can be used.

  From the above, according to the present invention, the organic sludge S is ventilated with the high-temperature gas G1 to dry the organic sludge S, and further, the moisture is reduced using the heat of fermentation by aerobic fermentation to obtain fuel. A long treatment period as in the case of composting is not required, and a reduction in cement production efficiency can be reduced and the organic sludge S can be fueled at a low cost in a short treatment period.

  Further, even when the ammonia concentration in the odor gas G2 exceeds about 200 ppm, the ammonia concentration in the odor gas G2 can be reduced to about 200 ppm or less while effectively using the high temperature gas G1 for reducing the water content of the organic sludge S. And can treat organic sludge efficiently and at low cost.

  Furthermore, by condensing and recovering the water evaporated from the organic sludge in the atmospheric gas in the indoor yard 2 using the cooling pipe 3 or the like, the moisture reduction rate of the organic sludge S is increased and the throughput is increased. In addition, the recovered water W can be effectively utilized in the organic sludge fuelization facility 1 or a cement manufacturing factory.

1 Organic Sludge Fueling Facility 2 Indoor Yard 3 Cooling Pipe 4 Scraper 5 Condensate Water Tank 6 Biological Deodorization Treatment Tank 7 Building 8 Hot Gas Supply Unit G1 Hot Gas G2 Odor Gas S Organic Sludge W Collected Water

Claims (7)

With organic sludge accumulated in an indoor yard, a high-temperature gas of 50 ° C. or higher and 140 ° C. or lower generated in a cement baking apparatus or power generator is applied to the organic sludge at 0.4 m ³ / m ^{3 of the} organic sludge. Organic sludge fuel characterized by using a heat of fermentation by aerobic fermentation and reducing the moisture of the organic sludge as a fuel while aerating at a rate exceeding min and exceeding 1.0 m ³ / min Method.   2. The method for fuelizing organic sludge according to claim 1, wherein a moisture adjusting material is added to the organic sludge as needed, and then deposited in the indoor yard. The amount of aeration of the high temperature gas to the organic sludge is adjusted by adjusting the ammonia concentration, the CO ₂ concentration or the decomposition degree of the organic sludge after the high temperature gas is passed through the organic sludge. The method for fuelizing organic sludge according to claim 1 or 2.   4. The method for fuelizing organic sludge according to claim 1, 2, or 3, wherein moisture in the atmospheric gas in the indoor yard is condensed and recovered.   The recovered water is used as at least one of diluting water for denitration agent used during cement production, lubricating water used for transporting the organic sludge, cooling water for heat exchange pipes, and water for water spraying in a biological deodorization tank. The method of converting the organic sludge into fuel according to claim 4.   6. The method for producing organic sludge as a fuel according to any one of claims 1 to 5, wherein the odor gas generated by the aerobic fermentation is deodorized.   7. The method for producing organic sludge as a fuel according to claim 1, wherein the aerobic fermentation is performed by a hyperthermophilic bacterium.

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