JP2015093231A - Method and device for processing highly wet waste - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and device for processing a highly wet waste at low cost.SOLUTION: The method for processing a highly wet waste includes the successive steps of: supplying carbon dioxide gas to a highly wet waste; dissolving the carbon dioxide gas in the water contained in the highly wet waste with application of pressure; and reacting the water with dissolved carbon dioxide gas and a solid matter in the highly wet waste. Preferably the highly wet waste is decompressed after the reaction so that carbon dioxide gas is separated and recycled for use as carbon dioxide gas to be dissolved in water, and heated so that the reaction is accelerated.

Description

  The present invention relates to a technique for treating waste (hereinafter referred to as high-humidity waste) having a high water content such as sewage sludge, raw garbage, and pulp sludge.

High-humidity waste such as sewage sludge, garbage, and pulp sludge is incinerated by a combustion furnace, for example.
Since sewage sludge, which is a highly humid waste, contains a large amount of moisture, the moisture content has been reduced beforehand using a mechanical dehydrator such as a screw press dewatering device, a filter press dewatering device, or a centrifugal dewatering device. Later, incineration is performed.

However, it is difficult to reduce the moisture content of high-humidity waste to such an extent that it can be self-combusted by mechanical dehydration as described above. Therefore, it is necessary to add a fossil fuel to ensure a sufficient combustion state, and there is a problem that the fuel consumption required for the incineration process increases.
Therefore, various proposals have been made as pretreatment methods for reducing or eliminating the fossil fuel necessary for the combustion treatment of highly humid waste.

In Patent Document 1, a high-humidity waste is put into a processing container, high-pressure steam is injected, and a hydrothermal reaction proceeds by holding it at a predetermined pressure and temperature for a predetermined time. It is described that the water content is reduced by making the waste finer and lower in molecular weight so that moisture that is not released in the mechanical dehydration process can be easily released, and then dewatering in a dehydration apparatus.
However, this method has a problem that the high-pressure steam used in the hydrothermal treatment is exhausted out of the system as waste steam, so that a great amount of heat energy possessed by the waste steam is lost and thermal efficiency is poor.

In Patent Document 2, in the method using hydrothermal reaction described in Patent Document 1, hydrothermal treatment reactors are provided in parallel, and waste steam discharged from one hydrothermal reaction reactor is reacted in the other hydrothermal reaction reactor. It is described that it is supplied as water vapor for preheating the area. In this method, the thermal energy of high-pressure steam used for hydrothermal treatment is recovered and effectively used.

However, both of the methods described in Patent Document 1 and Patent Document 2 utilize a hydrothermal reaction of water, and there is a problem that a large amount of energy is consumed to make water high temperature and high pressure.
Moreover, there is a concern that the moisture content of the high-humidity waste increases by spraying high-pressure steam on the high-humidity waste.

Patent Document 3 discloses a gas dissolving means for dissolving carbon dioxide gas in slurry sludge under pressure, and crushing slurry sludge in which gas is dissolved under a pressure lower than the pressure under pressure. A method of treating sludge using a sludge treatment apparatus equipped with a destruction means is described.
In this sludge treatment method, after gas is dissolved in slurry-like sludge under pressure, the slurry-like sludge is injected from a nozzle under a pressure lower than the pressure under pressure to collide with a collision plate. By making the gas dissolved in the sludge cells into bubbles by a pressure difference (pressure difference between the pressurized condition and a pressure lower than the pressure under the pressurized condition), the sludge cells are inflated. This swells the cell wall in a state where the elastic force is small, thereby releasing moisture.

However, this method uses a means for mechanically destroying the sludge in the form of a slurry and requires a separate processing apparatus for this purpose. Further, when sludge is sprayed from the nozzle, it is thought that the sludge is clogged in the nozzle and stable operation cannot be performed. Furthermore, carbon dioxide gas generated when sludge is jetted from a nozzle and collided with a collision plate contains an odor component, and it is not preferable to discharge this to the environment as it is in environmental measures. This measure is not described.

JP 2007-203213 A JP 2009-120746 A JP 2009-233637 A

  An object of the present invention is to solve the problems of the prior art as described above, and to provide a method and an apparatus capable of treating highly humid waste at low cost.

As a result of intensive studies to solve the above-mentioned problems, the present inventor has dissolved carbon dioxide gas obtained by supplying and pressurizing carbon dioxide gas to the high-humidity waste prior to dehydration treatment of the high-humidity waste. The present invention has been completed by finding that the water content of the waste can be greatly reduced in the dehydration process by treating with water.
The configuration of the present invention is as follows.

(1) After supplying carbon dioxide to highly humid waste,
Pressurize to dissolve carbon dioxide in water in highly humid waste,
A method for treating high-humidity waste, characterized by reacting water in which the carbon dioxide gas is dissolved with solids in high-humidity waste.
(2) The method for treating high-humidity waste according to (1), wherein the high-humidity waste after the reaction is decompressed to separate carbon dioxide, and (3) water in which the carbon dioxide is dissolved The method for treating high-humidity waste according to (1) or (2), wherein the high-humidity waste is heated in order to promote the reaction with the solid matter in the high-humidity waste (4) An apparatus for supplying carbon dioxide to wet waste;
An apparatus for pressurizing a mixture of high-humidity waste and carbon dioxide obtained from the apparatus, and dissolving the carbon dioxide in water in the high-humidity waste;
An apparatus for treating high-humidity waste, comprising a reaction tank for reacting water in which carbon dioxide gas is dissolved in the apparatus with solid matter in high-humidity waste.
(5) The apparatus for treating high-humidity waste according to (4), wherein a device for reducing the high-humidity waste discharged from the reaction tank is provided. (6) The high-humidity waste is reduced in pressure. The high-humidity waste treatment apparatus according to (5), further comprising a carbon dioxide separation device for separating carbon dioxide from a mixture of high-humidity waste and carbon dioxide discharged from the apparatus.
(7) The high-humidity waste according to (6), wherein the carbon dioxide gas separated in the carbon dioxide separation device is used as a carbon dioxide gas used in a device for mixing the high-humidity waste and carbon dioxide. Material processing equipment.
(8) The high-humidity waste according to any one of (5) to (7), wherein pressurization of the mixture of high-humidity waste and carbon dioxide gas and decompression of the high-humidity waste are performed with a pressure exchanger. Material processing equipment.
(9) The high-humidity waste treatment apparatus according to any one of (5) to (7), wherein the apparatus for depressurizing the high-humidity waste discharged from the reaction tank is a pressure reducing valve.
(10) Any one of (4) to (12), wherein a heater for heating the high-humidity waste supplied to the reaction tank or heating the high-humidity waste in the reaction tank is provided. An apparatus for treating highly humid waste according to claim 1.
(11) The heat exchanger for exchanging heat between the highly humid waste discharged from the reaction tank and the highly humid waste supplied to the reaction tank is provided. High-humidity waste treatment equipment.
(12) In any one of (4) to (11), a carbon dioxide gas circulation path for supplying carbon dioxide gas to the reaction tank and supplying carbon dioxide gas discharged from the reaction tank to the reaction tank is provided. The high-humidity waste processing apparatus as described.
(13) Dehydration of high-humidity waste characterized in that a dehydrator for dehydrating high-humidity waste discharged from the high-humidity waste treatment apparatus according to any one of (4) to (12) is provided. Processing equipment.

  According to the present invention, it is possible to further reduce the pressure and temperature for the treatment because the oxidation action by the water in which carbon dioxide gas is dissolved is used without using a high-temperature and high-pressure hydrothermal reaction. There is an effect that can be reduced.

It is a figure which shows an example of the highly humid waste processing apparatus of this invention. It is a figure which shows an example of the highly humid waste processing apparatus of this invention. It is a figure which shows an example of the highly humid waste processing apparatus of this invention. It is a figure which shows the modification of the highly humid waste processing apparatus of FIG. It is a figure which shows an example which added the dehydrator to the highly humid waste processing apparatus of FIG.

Out of the moisture contained in high-humidity waste, external water such as pore water, capillary-bound water, and surface-attached water is easy to mechanically dehydrate, but internal water contained in cells and tissues contained in sludge etc. Mechanical dehydration is difficult.
In the present invention, by first supplying carbon dioxide gas to the high-humidity waste and pressurizing, the solubility of the carbon dioxide gas in the external water of the high-humidity waste increases, and the external water is a carbon dioxide in which a large amount of carbon dioxide is dissolved. It becomes water. And the cell wall of each solid substance which forms the highly humid waste which is contacting with this carbonated water is destroyed by the oxidation action of carbonated water. By performing dehydration treatment on the highly humid waste whose cell wall has been destroyed, the moisture content of the highly humid waste can be greatly reduced, and the fuel consumption required for incineration can be reduced or eliminated.

Further, the highly humid waste material that has been oxidized is in a pressurized state, and it is preferable to recover the energy required for this pressurization. In the present invention, the energy of the high-humidity waste in a pressurized state after the oxidation treatment is recovered by using a pressure exchanger, and is used as energy for pressurizing the untreated high-humidity waste.

Moreover, the highly wet waste after the oxidation treatment contains carbon dioxide gas. In the present invention, the high-humidity waste after oxidation treatment is depressurized to separate and recover carbon dioxide from the high-humidity waste, and this carbon dioxide is supplied again to the untreated high-humidity waste and pressurized to produce carbon dioxide. Is reused by dissolving it in the external water of highly humid waste. Carbon dioxide gas contains an odor component, but as described above, the odor component is not discharged to the environment by reusing the carbon dioxide gas in a closed cycle.
In addition, a part of carbon dioxide gas can be discharged | emitted after taking out from a circulation system suitably and performing a deodorizing process.

The present invention utilizes the oxidizing action of carbonated water. Such an oxidation reaction has a higher reaction efficiency as the temperature is higher. For this reason, it is preferable to perform contact with carbonated water and highly humid waste in the state heated in the reaction tank where temperature was controlled. Specifically, it is preferable that a mixture of carbonated water and highly humid waste is heated in a reaction vessel, or heated with a heater and introduced into the reaction vessel to cause an oxidation reaction at a temperature of room temperature or higher. .
The higher the reaction temperature is, the better the efficiency of the oxidation reaction is, but it costs more to heat, and the higher the temperature, the higher the carbon dioxide gas solubility needs to be, and the higher the cost of pressurization. The temperature and pressure are appropriately set in consideration of the cost according to the processing target.
The temperature condition needs to be appropriately selected according to the type of high-humidity waste to be treated, and is usually room temperature to 80 ° C, preferably room temperature to 50 ° C, more preferably 30 ° C to 50 ° C.

  Below, the form for implementing this invention is demonstrated based on FIGS. In addition, the following description illustrates embodiment in this invention, Comprising: The invention as described in a claim is not limited at all.

(First embodiment)
A first embodiment of the present invention is shown in FIG.
A high-humidity waste treatment apparatus 10 shown in FIG. 1 includes a pressure pump 1, a pressure exchanger 2, a heat exchanger 3, a heater 4, a reaction tank 5, and a separator 6 that separates carbon dioxide gas.
Untreated high-humid waste W1 is supplied with carbon dioxide gas, then pressurized by the pump 1 and sent to the pressure exchanger 2.
The high-humidity waste W1 is pressure-exchanged by the pressure exchanger 2 with the reacted high-humidity waste W2 in a high-pressure state sent from the reaction tank 5 to be in a high-pressure state.
As the pressure exchanger, for example, an energy recovery booster (HPB) manufactured by Fedeco, USA can be used.

Next, the high-humidity waste W <b> 1 having a high pressure is sent to the heat exchanger 3. The high-humidity waste W1 is heated by exchanging heat with the reacted high-humidity waste W2 that has been heated by the heat exchanger 3, and then appropriately heated by the heater 4 as necessary. To be introduced. At the stage of introduction into the reaction vessel 5, carbon dioxide gas is dissolved in the moisture of the highly wet waste W1, and the moisture is carbonated water.

The high-humidity waste W1 is brought into contact with carbonated water for a predetermined time in the reaction tank 5, and the cell wall of the solid content of the high-humidity waste W1 is destroyed by the oxidation action of the carbonated water. Discharged.
The reaction tank 5 is preferably provided with a stirrer to enable uniform and sufficient contact between the carbonated water and the highly wet waste W1.

The reacted high-humidity waste W2 discharged from the reaction vessel 5 is recovered by the heat exchanger 3, and further sent to the pressure exchanger 2 to exchange pressure with the high-humidity waste W1 to reduce the pressure, and the carbonated water. The carbon dioxide dissolved in the water will be separated.
The mixture of the highly humid waste W2 and the carbon dioxide gas is sent to the separator 6, and the carbon dioxide gas and the highly wet waste W2 are separated.
The carbon dioxide gas separated by the separator 6 is recovered and supplied again to the untreated high-humidity waste W1, and the same cycle as described above is repeated.

In this way, by circulating the carbon dioxide gas in a closed cycle, the odor component contained in the carbon dioxide gas is not released out of the system as it is. Further, a part of the carbon dioxide gas containing the concentrated odor component can be continuously or intermittently extracted from the circulation system as appropriate and deodorized, and then released outside the system. In this case, since the odor component is concentrated, the deodorization treatment can be performed efficiently.
The positions of the pump 1 and the pressure exchanger 2 can be exchanged, and the positions of the heat exchanger 3 and the heater 4 can be exchanged. The same applies to the following embodiments.

(Second Embodiment)
A second embodiment of the present invention is shown in FIG.
In this embodiment, the position of the heater 4 in the first embodiment is changed.
In the case shown in FIG. 2, the heater 4 heats the highly humid waste by supplying the heat medium heated by the heat medium heater 10 to the heat transfer tube 11 provided in the reaction tank 5. ing.

(Third embodiment)
A third embodiment of the present invention is shown in FIG.
In the present embodiment, a pressure reducing valve 7 is arranged in a path from the reaction tank 5 to the separator 6 in place of the pressure exchanger 2 in the first embodiment.
The reacted high-humidity waste W2 sent out from the reaction tank 5 is depressurized by passing through the pressure reducing valve 7, and the carbon dioxide gas is separated from the high-humidity waste W2 and the mixed flow of the high-humidity waste W2 and the carbon dioxide gas. And sent to the separator 6. Carbon dioxide gas is separated and recovered by the separator 6, and this carbon dioxide gas is supplied again to the untreated high-humidity waste W1 and reused.

(Fourth embodiment)
A fourth embodiment of the present invention is shown in FIG.
In this embodiment, the compressor 8 for supplying carbon dioxide gas to the reaction tank 5 in the first embodiment is added. The carbon dioxide gas supplied to the lower part of the reaction tank 5 by the compressor 8 is mixed with the highly humid waste W1 and carbonated water in the reaction tank by bubbling to make uniform and sufficient carbonated water and highly humid waste W1. Enable contact.
Further, by supplying carbon dioxide gas to the lower part of the reaction tank 5 by the compressor 8, it is possible to supply a sufficient amount of carbon dioxide gas required by the highly wet waste W1 supplied to the reaction tank. Carbon dioxide gas that has been supplied into the reaction tank by the compressor 8 and has not dissolved in the moisture of the sludge is discharged from the reaction tank 5 and sent to the compressor 8 again.
(Fifth embodiment)
A fifth embodiment of the present invention is shown in FIG.
In the present embodiment, in the first embodiment shown in FIG. 1, the reacted high-humidity waste discharged from the separator 6 is supplied to a dehydrator and dehydrated to obtain a dehydrated high-humid waste W3. It is.
Since the high-humidity waste W2 is oxidized by contact with carbonated water and the water is easily separated, the moisture content of the high-humidity waste W3 is greatly reduced by dehydrating the dehydrator 9.
In addition, also in the first to fourth embodiments, by adding the dehydrator 9 in the same manner, the dehydrated highly wet waste W3 can be obtained.

According to the present invention, in order to use the oxidizing action by water in which carbon dioxide gas obtained by supplying and pressurizing carbon dioxide gas to high-humid waste without using high-pressure steam is used, Compared with the method using high-pressure steam, the pressure and temperature for the treatment can be further reduced, and the energy consumption can be reduced.
Moreover, since this invention does not require the processing equipment for mechanically destroying a cell wall like the method of patent document 3, it has the effect that the cost concerning a processing equipment can be reduced.

According to the present invention, the pressure energy can be recovered by the pressure exchanger, and the heat energy can be recovered and reused by the heat exchanger, so that energy consumption can be reduced.
Since the carbon dioxide used in the present invention is easily separated from the highly humid waste at the stage where the pressure is reduced after the high pressure state, the carbon dioxide is easily recovered and reused.
Further, in the present invention, since carbon dioxide is circulated and used in a closed system, odor components are not released to the environment.

When the method of the present invention is applied to sewage sludge, when composting the sewage sludge, it is possible to reduce the moisture content of the sludge, so that there is an effect that the weight is small and handling becomes easy.
Further, when phosphorus is collected, there is an effect that the collection becomes easy because the concentration of phosphorus is increased.
In addition, by destroying the cell wall of the highly humid waste, it is possible to carry out methane fermentation effectively by bringing it into the methane fermentation process without mechanical dehydration.

DESCRIPTION OF SYMBOLS 1 Pressurization pump 2 Pressure exchanger 3 Heat exchanger 4 Heater 5 Reaction tank 6 Separator 7 Pressure reducing valve 8 Compressor 9 Dehydrator 10 Heat medium heater 11 Heat transfer tube W1 Untreated high-humid waste W2 Reacted Highly humid waste W3 Highly humid waste after dehydration

Claims (13)

After supplying carbon dioxide to highly humid waste,
Pressurize to dissolve carbon dioxide in water in highly humid waste,
A method for treating high-humidity waste, characterized by reacting water in which the carbon dioxide gas is dissolved with solids in high-humidity waste. 2. The method for treating highly humid waste according to claim 1, wherein the highly humid waste after the reaction is decompressed to separate carbon dioxide.   The high-humidity waste according to claim 1 or 2, wherein the high-humidity waste is heated in order to promote a reaction between the water in which the carbon dioxide gas is dissolved and the solid matter in the high-humidity waste. Waste disposal method. A device for supplying carbon dioxide to highly humid waste,
An apparatus for pressurizing a mixture of high-humidity waste and carbon dioxide obtained from the apparatus, and dissolving the carbon dioxide in water in the high-humidity waste;
An apparatus for treating high-humidity waste, comprising a reaction tank for reacting water in which carbon dioxide gas is dissolved in the apparatus with solid matter in high-humidity waste. The apparatus for treating high-humidity waste according to claim 4, further comprising a device for depressurizing high-humidity waste discharged from the reaction tank. 6. The high carbon dioxide gas separation device according to claim 5, further comprising a carbon dioxide gas separation device for separating carbon dioxide gas from a mixture of high wet waste material and carbon dioxide gas discharged from a device for depressurizing the high moisture waste material. Wet waste treatment equipment.   The treatment of high-humidity waste according to claim 6, wherein the carbon dioxide separated in the carbon dioxide separation device is used as carbon dioxide used in an apparatus for mixing the high-humidity waste and carbon dioxide. apparatus.   The high-humidity waste treatment apparatus according to any one of claims 5 to 7, wherein the pressurization of the mixture of the high-humidity waste and carbon dioxide gas and the decompression of the high-humidity waste are performed by a pressure exchanger.   The apparatus for treating high-humidity waste according to any one of claims 5 to 7, wherein the apparatus for depressurizing high-humidity waste discharged from the reaction tank is a pressure reducing valve.   A high heater according to any one of claims 4 to 9, further comprising a heater for heating the high-humidity waste supplied to the reaction tank or heating the high-humidity waste in the reaction tank. Wet waste treatment equipment.   The high-humidity waste according to claim 10, further comprising a heat exchanger for exchanging heat between the high-humidity waste discharged from the reaction tank and the high-humidity waste supplied to the reaction tank. Material processing equipment.   The high-humidity waste according to any one of claims 4 to 11, further comprising a carbon dioxide circulation path for supplying carbon dioxide to the reaction tank and supplying carbon dioxide discharged from the reaction tank to the reaction tank. Material processing equipment.   A dewatering apparatus for high-humidity waste, comprising a dehydrator for dehydrating high-humidity waste discharged from the high-humidity waste processing apparatus according to any one of claims 4 to 12.

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