Organic waste hydrolysis treatment system

Abstract

To provide a further efficient organic waste hydrolysis treatment system that does not affect an environment adversely by achieving significant improvement in processes and by having sterilization and bad smell recovery means.SOLUTION: There is provided an organic waste hydrolysis treatment system for hydrolyzing organic waste while agitating the organic waste under a high temperature and high pressure saturated steam environment, and performing processing by drying the organic waste. The system includes: a pressure-resistant container equipped with an input port for inputting organic waste and an exhaust port for discharging steam or gas during or after processing the organic waste; steam supply means for supplying saturated steam to the inside of the pressure-resistant container; pressure adjusting means for adjusting the pressure in the pressure-resistance container by an on-off valve; steam discharge means for discharging steam in the pressure-resistant container; agitation means for agitating the waste input to the inside of the pressure-resistant container; and hot air supply means for supplying hot air for drying the organic waste.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an organic waste hydrolysis treatment system for decomposing and drying organic waste in a high-temperature and high-pressure steam environment (also called a subcritical environment). [Background technology]

[0002] In waste treatment, especially in the treatment of organic waste, a waste treatment method that uses water vapor to hydrolyze organic waste with high-temperature, high-pressure saturated steam (in a subcritical environment) has been attracting attention in recent years as an alternative to the conventional incineration treatment in incinerators or underground disposal, as a device that does not have a negative impact on the global environment. In addition, waste treatment devices and systems that use this method have actually been developed and manufactured, and some of these devices and systems have already been delivered to and are in operation by waste treatment companies and local governments.

[0003] The above waste treatment method, device and / or system are disclosed, for example, in Japanese Patent No. 4751977 (Patent Document 1). The waste treatment device disclosed in Patent Document 1 is a waste treatment device or system that mainly treats organic waste, places the waste in a sealed pressure-resistant container, supplies high-pressure saturated steam into the container, and pulverizes and hydrolyzes the waste in a high-temperature, high-pressure environment while controlling the pressure and temperature inside the container.

[0004] Here, when the hydrolyzed waste is discharged as it is from the pressure vessel, most of the treated waste has a high water content and is in a sludge state, so it gives off a foul odor and has a significant adverse effect on the surrounding environment. In order to improve this foul odor, a drying process or means is required in the waste treatment method, device and / or system.

[0005] However, there is no description of a drying process or means in Patent Document 1. In addition, the device disclosed in Patent Document 1 can prevent a drop in temperature due to evaporation of water during drying by supplying high-temperature steam into the gap between the outer and inner walls of a pressure-resistant container with a double-wall structure, but since it is an indirect heating method, it takes a long time to dry, and there is room for further improvement in terms of shortening the drying time.

[0006] In order to improve the drying time, for example, Japanese Patent Application Laid-Open No. 2008-246300 (Patent Document 2) discloses a waste treatment device and method in which hydrolyzed waste is moved to a separately installed low-pressure container and dried there, thereby increasing the turnover rate of the pressure container. However, in the waste treatment device and method disclosed in Patent Document 2, if the waste is dry, it can be moved by an agitator blade, which can increase the turnover rate of the pressure container and shorten the drying time, but in the case of waste with a high moisture content and in a sludge state, there is a problem that it is not easy to move the waste.

[0007] Also, Japanese Patent Application Laid-Open No. 2010-284589 (Patent Document 3) proposes a waste treatment system that dries waste materials by directly supplying superheated steam into a pressure-resistant container. The system according to Patent Document 3 alleviates concerns about bad odors, but has the problem that it takes a long time to dry if there is not enough space for the drying fluid to flow inside the pressure-resistant container.

[0008] There has been a strong demand for shortening the drying time of such waste treatment equipment and systems, both in terms of recovering the high costs required to install the equipment and in terms of the costs of operating the equipment. This is because it is related to the turnover rate of the treatment equipment, which is how much large amount of waste can be treated in a day or how many times it can be operated in a day, and if the drying time can be shortened, the turnover rate of the equipment can be increased, significantly increasing the amount of waste that can be treated, which will contribute to saving on operating costs and cost recovery.

[0009] In addition, JP 2017-131841 A (Patent Document 4) discloses a waste treatment system equipped with a hot air supply means and a pressure adjustment means for shortening the drying time. In the invention described in Patent Document 4, high-pressure hot air is sent into the container, so that the hot air penetrates and contacts not only the surface but also the water held inside according to the so-called Pascal's principle, and then the pressure is reduced, so that the solid holding the moisture inside is subjected to drying conditions equivalent to those of the air flow drying of the surface, making it possible to significantly shorten the time corresponding to the movement time of the water held inside to the solid surface, which greatly affects the drying time, and by pulse-fluctuation of the pressure, it is possible to treat in an even shorter time.

[0010] However, the system disclosed in Patent Document 4 has a problem in that it takes time for moisture to move in the capillaries inside the substance, and therefore the pulse period must be lengthened, making it difficult to achieve a sufficient reduction in time. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] Patent No. 4751977 [Patent Document 2] JP 2008-246300 A [Patent Document 3] JP 2010-284589 A [Patent Document 4] JP 2017-131841 A Summary of the Invention [Problem to be solved by the invention]

[0012] In view of the above-mentioned circumstances, the present invention provides a waste treatment system including means for hydrolyzing, pulverizing and drying organic waste with high-temperature, high-pressure saturated steam, which is more efficient and has less impact on the environment by significantly improving the drying means or process and further by having sterilization and odor recovery means. [Means for solving the problem]

[0013] The organic waste hydrolysis treatment system according to the present invention, which aims to solve the above problems, is configured to hydrolyze and dry organic waste under a high-temperature, high-pressure saturated steam environment while stirring the organic waste, and the organic waste hydrolysis treatment system comprises a corrosion-resistant stainless clad pressure vessel having an inlet for introducing the organic waste and an outlet for discharging steam or gas generated during or after the treatment of the organic waste, steam supply means for supplying saturated steam into the pressure vessel, pressure adjustment means for adjusting the pressure in the pressure vessel with an on-off valve, and a valve for discharging the steam in the pressure vessel. The organic waste hydrolysis treatment system is characterized in that it comprises a water vapor exhaust means for exhausting water from the waste material introduced into the pressure-resistant vessel, an agitation means for agitating the waste introduced into the pressure-resistant vessel, and a hot air supply means for supplying hot air for drying the organic waste, the agitation means having an agitation shaft penetrating the heat-resistant vessel, and the organic waste hydrolysis treatment system is characterized in that it sets the temperature inside the heat-resistant vessel at 210 to 240°C and the pressure inside the heat-resistant vessel at 2 to 3 MPa, sterilizes and hydrolyzes the organic waste while agitating it with the agitation means, and, after the sterilization and hydrolysis, drys the organic waste with the hot air supplied by the hot air supply means and then discharges the powder of the organic waste that has been decomposed.

[0014] The configuration of the system according to the present invention is more effectively achieved by the organic waste being any one of used rolling straw, sludge, waste plastics, paper waste, wood chips, solid waste from animals, animal residues, medical waste whether infectious or non-infectious, separated food waste, food waste, discarded fishing nets, or discarded printed circuit boards, or by further comprising condensing means for cooling and condensing the steam and gas discharged from the exhaust port, neutralizing means for neutralizing the effluent condensed in the condensing means, and water washing means and alkaline washing means for washing the gas not condensed in the condensing means, the effluent being connected to the neutralizing means via a pump, and the non-condensed gas being connected to the water washing means and the alkaline washing means via a blower, and further the neutralizing means, the water washing means and the alkaline washing means being connected to a reduced pressure drying means. Effect of the Invention

[0015] According to the organic waste hydrolysis treatment system of the present invention, in a waste treatment device including a hydrolysis means using high-temperature, high-pressure saturated steam, the drying time can be significantly shortened, the daily turnover rate of the device can be increased, and costs can be significantly reduced.

[0016] According to the waste treatment device of the present invention, it is possible to completely sterilize organic waste by sterilizing to a higher standard than the sterilization standard set by the World Health Organization (WHO) (121°C in an autoclave for 30 minutes or more), and the treated and dried waste can be disposed of or landfilled as general waste. In addition, by adding a deodorizing means, it is possible to completely deodorize organic waste. [Brief description of the drawings]

[0017] [Figure 1] 1 is a schematic diagram showing an example of an industrial waste treatment device used in a waste treatment system according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] An example of an apparatus for hydrolysis and treatment of organic waste according to the present invention will be described with reference to a schematic diagram.

[0019] In FIG. 1, 1 indicates a pressure vessel for containing and treating waste, 1a indicates an inlet for the waste, and 1b indicates an outlet for the treated waste. The pressure vessel 1 has a sealed structure, and the inlet 1a and outlet 1b are structured to be openable and closable by valves (not shown). Although not shown, the pressure vessel 1 for treating waste may have a double structure, and may be structured to supply high-temperature steam to the gap between the outer and inner walls to assist the drying operation. Furthermore, the pressure vessel 1 may have a triple structure or even a multiple structure, as long as it is a sealed structure. The size, material, shape, etc. of the pressure vessel 1 are not particularly limited, and may be appropriately selected or designed according to the installation location and the surrounding environment. As for the installation locations of the inlet 1a and outlet 1b, there is no need to be particular about the locations shown in FIG. 1, as long as the transport of the waste is taken into consideration.

[0020] Reference numeral 2 denotes an impeller for stirring the waste material fed from the feed port 1a while transferring it to the discharge port 1b. Reference numeral 2a denotes the stirring shaft of the impeller 2, which penetrates through the pressure vessel 1. There is no particular restriction on the shape of the impeller 2, but when considering the stirring of the waste material and the transfer of the waste material from the feed port 1a to the discharge port 1b, a helical screw blade may be provided.

[0021] Reference numeral 3 denotes a motor for rotating the agitator shaft 2a. The motor 3 is controlled to rotate in both forward and reverse directions, so that waste material fed from the feed port 1a is transported back and forth within the pressure vessel 1 to the discharge port 1b. There are no particular limitations on the performance of the motor 3, so long as it can rotate in both forward and reverse directions.

[0022] Reference numeral 4 denotes a boiler that supplies high-temperature, high-pressure steam for hydrolyzing waste into the pressure vessel 1, and 4a denotes a steam supply pipe for supplying high-temperature, high-pressure steam from the boiler 4 into the pressure vessel 1 during hydrolysis of the waste.

[0023] The temperature, pressure and / or supply time of the water vapor supplied into the pressure vessel 1 are adjusted depending on the condition of the waste being treated (e.g., the ratio of water adhering to the surface of the object (waste) and the water contained inside the object, etc.).

[0024] Reference numeral 5 denotes a high-pressure hot air generator. Reference numeral 5a denotes an on-off valve that pulse-controls the pressure in the pressure-resistant container 1 during drying. In other words, the on-off valve 5a also serves as an on-off valve for controlling the volume of air (hot air) generated from the hot air generator 5. Publicly known products may be used for the hot air generator 5 and the on-off valve 5a. The on-off valve 5a may be either automatic or manual, with the automatic type being preferable.

[0025] Reference numeral 9 denotes a control device that controls the temperature, pressure, and time in the pressure vessel 1. The control device 9 is connected to the inlet 1a, the outlet 1b, the motor 3, the boiler 4, the on-off valve 5a, the temperature measurement line 6, the pressure measurement line 7, and the steam outlet 8. Although details are not shown, the control device 9 is a device in which the controllers of the connected components such as the inlet 1a are integrated, and the control device 9 can be manufactured by any means or method. In addition, although the connection means between each component such as the inlet 1a and the control device 9 is shown in FIG. 1 as being connected by wires (lines), a wireless signal connection means may be adopted by providing sensors or the like to each component such as the inlet 1a and the control device 9. In addition, the role of the control device 9 is to control the supply amount of steam from the boiler 4 during hydrolysis, to open and close the on-off valve 5a during drying, and / or to open and close the steam outlet 8 based on the temperature and pressure in the pressure vessel 1 measured by the temperature measurement line 6 and the pressure measurement line 7. Furthermore, the control device 9 controls the opening and closing of the inlet 1a and / or the outlet 1b of the pressure vessel 1, and controls the forward / reverse rotation and / or rotation speed of the stirring blade 2 (motor 3).

[0026] Furthermore, a sequencer, a timer, and the like may be installed in the control device 9 and each of the components connected to the device.

[0027] Although not shown, a deodorizing device (deodorizing means) may be additionally installed in the organic waste hydrolysis treatment system according to the present invention. As the deodorizing device, an ozone deodorizing device, a photocatalyst deodorizing device, a plasma deodorizing device, a discharge oxygen generating device, etc. can be used.

[0028] Reference numeral 10 denotes a condenser connected to the steam exhaust port 8. Reference numeral 11 denotes a transfer blower for transferring gas that is not condensed in the condenser 10. Reference numeral 12 denotes a pump for transferring the waste liquid condensed in the condenser 10 to a neutralization tank 17. The condenser 10, blower 11, pump 12, and neutralization tank 17 may be of known types.

[0029] Gas that is not condensed in the condenser 10 passes through a blower 11 and is washed in the water washing absorption tower 13 and the alkali washing absorption tower 14, where it is deodorized and then exhausted to the outside. An alkaline aqueous solution of caustic soda (sodium hydroxide) or the like is placed in the alkali washing absorption tower 14. Note that hypochlorous acid may be added to the alkaline aqueous solution for oxidative decomposition and removal. A line may be set up to transfer the excess moisture stored in the water washing absorption tower 13 and / or the alkali washing absorption tower 14 to a moisture evaporation container (reduced pressure dryer) described later (see FIG. 1). 16 is a final storage tank for wastewater, and depending on the environmental standards for wastewater in the surrounding area, the water is either discharged directly or discharged into a public waterway via a wastewater treatment plant.

[0030] The waste treatment system according to the present invention is established by combining the above-mentioned components as shown in FIG.

[0031] Next, the operation of the waste treatment system according to the present invention (outline of the waste treatment method) will be described. The waste treatment system according to the present invention is characterized by drying waste after hydrolysis using high-temperature and high-pressure steam in a short time compared to conventional hydrolysis waste treatment technology using high-pressure saturated steam, and the waste to be treated is not particularly limited as long as it is an organic material that can be hydrolyzed. In addition, the waste treatment system according to the present invention dries waste after hydrolysis in a short time, but does not perform pyrolysis or carbonization, so that it can be reused as fuel, fertilizer, etc.

[0032] The conditions for hydrolyzing waste are not particularly limited, but most (organic) waste can be hydrolyzed by controlling the temperature in a pressure vessel (see, for example, heat-resistant vessel 1 in FIG. 1) to preferably 210-240° C., more preferably 212-234° C., and the pressure to 2-3 MPa, and treating the waste with high-temperature, high-pressure saturated steam. If the temperature in the pressure vessel is 210° C. and the pressure is 2 MPa or less, plastics mixed in the waste are not sufficiently hydrolyzed, and even if the temperature in the pressure vessel is 240° C. and the pressure is 3 MPa or more, the general hydrolysis performance is not necessarily improved, and furthermore, the pressure vessel must be thickened, which increases the cost of the device and reduces its economic efficiency.

[0033] Moreover, the steam used for hydrolyzing the waste desirably has a temperature of 210-240°C and a pressure of 2-3 MPa. If the temperature is below 210°C and the pressure is below 2 MPa, the plastics mixed in the waste will not be hydrolyzed, and even if the temperature is above 240°C and the pressure is above 3 MPa, the effect of hydrolysis will not increase significantly.

[0034] The reaction time for hydrolysis depends on the temperature and / or pressure in the pressure vessel and the pressure of the steam, but is preferably about 5 to 250 minutes. If the reaction time is less than 5 minutes, the waste will not be sufficiently hydrolyzed. Furthermore, hydrolysis of general waste is completed within 250 minutes, and the effect of hydrolysis will not increase even if the reaction time is longer than that.

[0035] Target organic wastes include used straw rolls, sludge, waste plastics, paper waste, wood chips, solid waste from animals, animal residues, infectious or non-infectious medical waste, separated food waste, food residues, waste fishing nets, waste printed circuit boards, etc. Any amount of waste can be treated according to the scale of the waste treatment system according to the present invention and the size of each component device.

[0036] Next, waste hydrolyzed using high-temperature, high-pressure steam has a high moisture content and is in a so-called sludge state, so it cannot be easily removed from the pressure-resistant container as it is. Therefore, in the waste treatment system according to the present invention, after hydrolysis, high-temperature, high-pressure hot air is introduced, and the pressure is pulse-varyed as described in Patent Document 4 to dry and discharge the waste in a short time, thereby making it possible to achieve highly efficient drying of the waste hydrolyzed with steam and shorten the drying time. However, the present invention can be achieved even if the pressure is not pulse-varyed.

[0037] The temperature of the hot air (hot air) is about 500°C and the pressure is about 0.5 to 1 MPa. Before the drying, the pressure inside the pressure vessel is lowered (almost to normal pressure). The pressure here refers to the pressure maintained inside the pressure vessel. If the pressure is below 0.5 MPa, the moisture content of the waste does not decrease. Even if the pressure is above 1 MPa, the amount of capital investment increases, but there is little effect in shortening the drying time. Although the moisture content of the waste decreases inside the pressure vessel, the hydrolysis performance of general waste is not necessarily improved, and when considering the reuse of hydrolysis-treated waste (for example, as fertilizer or fuel), deterioration at high temperatures is a concern, so it is not appropriate.

[0038] Next, hot air is continuously inserted for about an hour depending on the dryness of the powder (the goal is to make the moisture content of the powder about 30%).

[0039] Although the embodiment of the organic waste hydrolysis treatment system according to the present invention has been described above, it goes without saying that the present invention is not limited to the above embodiment and can adopt various embodiments without departing from the matters described in this specification, the drawings, and / or the claims. EXAMPLES

[0040] The above-mentioned embodiment will be described in detail with reference to examples. For waste treatment, an organic waste hydrolysis treatment system (apparatus) according to the present invention shown in FIG.

[0041] [Test Example 1] Hydrolysis treatment using the organic waste hydrolysis treatment system according to the present invention In this test, infectious disease medical waste (referred to as "Sample 1") and food waste (referred to as "Sample 2") were treated under the hydrolysis treatment conditions shown in Table 1 below.

[0042] [Table 1]

[0043] First, the hydrolysis treatment in Table 1 refers to the hydrolysis treatment carried out in the pressure-resistant container of the treatment system shown in Figure 1. And the product in Table 1 refers to each sample that was hydrolyzed, dried, and then powdered.

[0044] A sterilization test was conducted on the infectious disease medical waste of sample 1, and it passed, meaning that no growth of bacteria (spore-forming bacteria) was observed. This sterilization test will be described later as "Test Example 2." On the other hand, a sterilization test was not conducted on the food waste of sample 2, but hydrolysis was performed to the extent that it could be composted.

[0045] [Test Example 2] Sterilization test of infectious disease medical waste after hydrolysis and drying In Test Example 2, a sterilization test was carried out on Sample 1 (medical waste for infectious diseases) after the hydrolysis treatment and drying in Test Example 1.

[0046] First, for sample 1 after hydrolysis and drying (referred to as "specimen 1" in Test Example 2) and non-sterilized infectious disease medical waste as a comparative test example (referred to as "specimen 2" in Test Example 2), the spore-forming bacteria, i.e. Geobacillus stearothermophilus (ATCC#7953) was used as a biological indicator to confirm the presence or absence of growth after culturing the spore-forming bacteria for 7 days at 55°C. However, for sample 1, the presence or absence of growth of the spore-forming bacteria could not be determined after the culturing, so 100μL of the culture liquid was inoculated into soybean casein digest medium (manufactured by Eiken Chemical Co., Ltd.), and the presence or absence of growth was confirmed after culturing at 55°C for 7 days. The results are shown in Table 2 below.

[0047] [Table 2]

[0048] As shown in Table 2, no growth of spore-forming bacteria was observed in sample 1, whereas growth of spore-forming bacteria was observed in sample 2.

[0049] Although the embodiment described above is merely an example, the results suggest that bacteria that cannot be killed by normal heating, such as spore-forming bacteria (e.g., Bacillus) that parasitize organic waste, can also be sterilized by using high-temperature, high-pressure steam in the organic waste hydrolysis treatment system according to the present invention. [Industrial Applicability]

[0050] The organic waste treated by the waste treatment system according to the present invention is not pyrolyzed or carbonized, and can therefore be reused as fuel, fertilizer (compost), and the like. [Explanation of symbols]

[0051] 1. Pressure vessel 2 stirring blades 3 Motor 4. Boiler 5. Hot air generator 6 Temperature detection line 7 Pressure detection line 8 Steam exhaust port 9. Control Device 10 Condenser 11 Blower 12 Pump 13. Water washing absorption tower 14 Alkaline cleaning absorption tower 16 Wastewater storage tank 17 Neutralization tank

Claims

1. An organic waste hydrolysis treatment system in which organic waste is hydrolyzed while being stirred in a high-temperature and high-pressure saturated steam environment, and is then dried and treated, The organic waste hydrolysis treatment system comprises a corrosion-resistant stainless clad pressure vessel having an inlet for introducing the organic waste and an outlet for discharging steam or gas generated during or after the treatment of the organic waste, steam supply means for supplying saturated steam into the pressure vessel, pressure regulating means for regulating the pressure in the pressure vessel with an on-off valve, steam exhaust means for exhausting the steam in the pressure vessel, stirring means for stirring the waste introduced into the pressure vessel, and hot air supply means for supplying hot air for drying the organic waste. The stirring means has a shaft for stirring penetrating the heat-resistant container; and The organic waste hydrolysis treatment system is characterized in that the temperature inside the heat-resistant container is set to 210 to 240°C and the pressure inside the heat-resistant container is set to 2 to 3 MPa, the organic waste is sterilized and hydrolyzed while being stirred by the stirring means, and after the sterilization and hydrolysis, the organic waste is dried with hot air supplied by the hot air supply means and then a powder of the decomposed organic waste is discharged.

2. 2. The organic waste hydrolysis treatment system according to claim 1, wherein the organic waste is any one of used straw rolls, sludge, waste plastics, paper waste, wood chips, solid waste from animals, animal residues, infectious or non-infectious medical waste, separated food waste, food residues, waste fishing nets, and waste printed circuit boards.

3. 3. The organic waste hydrolysis treatment system according to claim 1 or 2, further comprising condensing means for cooling and condensing the steam and gas discharged from the discharge port, neutralizing means for neutralizing the waste liquid condensed in the condensing means, and water washing means and alkali washing means for washing the gas not condensed in the condensing means, wherein the waste liquid is connected to the neutralizing means via a pump, and the non-condensed gas is communicated with the water washing means and the alkali washing means via a blower, and further wherein the neutralizing means, the water washing means and the alkali washing means are connected to a reduced pressure drying means.

Images