Continuous processing system for used paper diapers

Abstract

To provide a practicable system capable of efficiently converting a used paper diaper into a solid fuel for recycling SOLUTION: The apparatus includes a crushing section 3 for crushing a used paper diaper into crushed pieces, a decomposition liquid adding section 5 for adding a chlorine-based SAP decomposition liquid to the crushed pieces, a dehydrating section 15 for dehydrating the crushed pieces from which water is separated by decomposition of a polymer water-absorbing material to form fluff, a neutralizing agent adding section 19 for adding a chlorine neutralizing agent to the fluff, and a granulating section 21 for wet granulation after addition of the neutralizing agent. The sludge is dehydrated in the dehydration part 15 to be fluff-like and granulated in the granulation part 21 after a chlorine neutralizing agent is added thereto and the dehydration process and the chlorine removing process are well cooperated to dispense with a large amt. of water or a large-scaled drying process.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a technology for recycling used disposable diapers as refuse-derived fuel (RDF or RPF), and more particularly to a system capable of continuously converting them into solid fuel. [Background technology]

[0002] Disposable diapers have traditionally been incinerated as general waste, but in recent years, usage has increased so rapidly that incineration cannot keep up, making disposal a major problem.As a solution, it has been proposed to reuse them as refuse-derived fuel (RDF or RPF). By the way, the main material of disposable diapers is nonwoven fabric, but inside the diaper there is a "super absorbent polymer (SAP)" wrapped in cotton-like pulp.This super absorbent polymer is initially in powder form, but when it comes into contact with urine, or moisture, it turns into a gel, absorbing the moisture and preventing it from leaking out. As such, used disposable diapers contain a large amount of moisture, and in order to make them into a practical solid fuel, this moisture content must be reduced to 10% or less. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2023-171029 Summary of the Invention [Problem to be solved by the invention]

[0004] Patent Document 1 proposes soaking used disposable diapers in a treatment solution to remove water from the polymeric water absorbent material and then dehydrating them. However, dehydration by high-speed rotation alone is not sufficient to produce solid fuel, so a drying process is required. Moreover, because it is a batch process, it is difficult to increase the processing volume. In addition, because a large amount of water is required, it is necessary to deal with drainage. To address this issue, it has been proposed to use microorganisms to decompose polymeric absorbents and release moisture, but this takes too much time and is also a batch process, making it difficult to increase the processing volume.

[0005] The present invention has been made to solve the above-mentioned problems, and its object is to provide a practical system for recycling used disposable diapers into solid fuel (RDF or RPF) that can be continuously and efficiently converted into solid fuel without using large amounts of water or requiring a drying process separate from the dehydration process. [Means for solving the problem]

[0006] The present invention is a continuous processing system for used disposable diapers, which comprises a crushing section that crushes used disposable diapers into crushed fragments, a decomposition liquid addition section that adds a chlorine-based SAP decomposition liquid to the crushed fragments, a dehydration section that dehydrates the crushed fragments into fluff, a neutralizing agent addition section that adds a chlorine neutralizing agent to the fluff, and a granulation section that wet-granulates the fluff after adding the neutralizing agent, and which is characterized in that when used disposable diapers are fed into the crushing section, they are then processed sequentially in each processing section and discharged from the granulation section as solid fuel.

[0007] Preferably, the dehydration section and the granulation section use a dehydration wet granulator to achieve fluffing and granulation in a wet state. Preferably, a waiting section is provided between the decomposition liquid adding section and the dehydration section, and the crushed pieces are kept waiting until a syneresis reaction occurs. Preferably, the crushed pieces are agitated in the decomposition liquid adding section.

[0008] Preferably, an inflow system for introducing wash water containing a chlorine neutralizing agent is connected to the treatment section extending from the decomposition liquid addition section to the neutralizing agent addition section, and both the drainage system for this wash water and the drainage system for the dehydration section are connected to the reaction pool. Preferably, the granulating section is capable of adding an additive to adjust the calorific value of the solid fuel. Preferably, a cooling blower is provided to remove the heat of vaporization from the granulated material discharged from the granulating section. [Effects of the Invention]

[0009] The continuous disposal system for used disposable diapers of the present invention is a continuous system, so it can efficiently process a large amount of used disposable diapers into solid fuel. Furthermore, it does not require the use of a large amount of water or the provision of a drying process separate from the dehydration process, which is advantageous in terms of equipment costs and wastewater treatment. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is an overall configuration diagram of a continuous processing system for used disposable diapers according to an embodiment of the present invention. [Figure 2] FIG. 2 is an image diagram of the processing progress of the continuous processing system for used disposable diapers shown in FIG. 1. [Figure 3] Photographs of the processed material at each stage of the continuous processing system for used disposable diapers shown in Figure 1. [Figure 4] Photographs of the processed material at each stage of the continuous processing system for used disposable diapers shown in Figure 1. [Figure 5] Photographs of the processed material at each stage of the continuous processing system for used disposable diapers shown in Figure 1. DETAILED DESCRIPTION OF THE INVENTION

[0011] A continuous processing system 1 for used disposable diapers according to an embodiment of the present invention will be described with reference to the drawings. As shown in Figures 1 and 2, the materials to be treated are used disposable diapers. Used disposable diapers are rolled up and placed in a plastic bag together, and collected in a sealed state to prevent odors from escaping. In the present invention, the diapers are treated while still in the bag. Although used disposable diapers are labeled "paper diapers," they are primarily made of nonwoven fabric (plastic). Inside the diaper is a super absorbent polymer (SAP) wrapped in cotton-like pulp, which absorbs urine, or moisture, and turns into a jelly-like substance. At normal changing intervals, the moisture content can reach 1000% or more.

[0012] The crushing unit 3 is composed of, for example, a hopper-shaped uniaxial crusher, and when used disposable diapers are put in, it tears open the bag, crushes the disposable diapers, and discharges them as a mixture of crushed pieces. The recommended size of the crushed pieces is about -80 mm. This state is shown in FIG. 3, and the gelatinized water-absorbing polymer (SAP) is exposed.

[0013] The crushed pieces discharged from the bottom opening of the hopper fall to the rear side in the conveying direction of the conveyor that constitutes the decomposition liquid addition section 5. This conveyor is composed of, for example, a screw conveyor, and the falling crushed pieces are pushed out to the front side in the conveying direction and conveyed as a result of the rotation of a screw shaft fitted with spiral blades that is inserted into a pipe. A plurality of spray nozzles 5a are provided in the space on the ceiling side of this conveyor, and SAP decomposition liquid is sprayed onto the broken pieces inside the pipe through these spray nozzles 5a.

[0014] The crushed pieces are stirred as they are transported, and the side facing the ceiling is constantly changed, so that the SAP decomposition liquid is evenly added to the large number of crushed pieces that are fed in. Chlorine-based solutions, such as hypochlorous acid water, are used as SAP decomposition solutions. Hypochlorous acid water also has deodorizing and sterilizing effects, making it suitable for treating used disposable diapers. The recommended amount to add is 3% or more of the moisture absorbed by the used disposable diaper. Since about 300cc of moisture is absorbed during normal use, more than 9cc would need to be added.

[0015] The crushed pieces then fall to the rear side in the conveying direction of the conveyor 7. This conveyor 7 is configured in the same manner as the conveyor constituting the decomposition liquid adding section 5. However, while the latter is horizontal and has a spraying space for the spray nozzle 5a on the ceiling side, the former does not have such a space and is also inclined so that the forward side in the conveying direction is higher. The transported crushed pieces fall from the forward end of the transport direction of the transporter 7 into the reaction tank 9 that constitutes the waiting section. This reaction tank 9 is equipped with a heater that heats the crushed pieces inside the reaction tank 9. While the crushed pieces are waiting inside the reaction tank 9, the SAP decomposing liquid decomposes the polymer water absorbent material (SAP), and water release begins. The heated state promotes the water release reaction.

[0016] A constant quantity discharge screw 11 is disposed on the bottom side of the reaction tank 9, and this constant quantity discharge screw 11 sequentially removes a constant quantity of crushed fragments from the bottom side after waiting in the reaction tank 9 for a certain period of time, for example, several minutes, or at most 30 minutes, and after the water-repelling reaction has progressed sufficiently, and drops them to the rear side in the conveying direction of the downstream conveyor 13. The conveyor 13 is configured in the same way as the conveyor 7. At the time of removal, the water has been sufficiently released and some of the water has seeped out, and the seeped water flows out directly from the drainage outlet 13a provided in the conveyor 13, while the remainder is conveyed.

[0017] The conveyor 13 is also heated in the same manner as the reaction vessel 9, and this heating promotes the syneresis action. The transported crushed pieces fall into the dewatering section 15 from the end of the conveying direction of the conveyor 13. This dewatering section 15 is composed of a dewatering wet granulator (DPF series, manufactured by KUN SHENG MACHINE CO., LTD., sold by Plant Systems Co., Ltd. (the present applicant)), which is the actual machine described in Utility Model Registration No. 3168801. Although the publication describes it as being for complete dewatering, due to its structural characteristics, in this embodiment, the hopper side functions as the dewatering section, and its lower side is open to form a drainage basin 15a. In addition, the adjacent section on the end of the transport direction functions as a drying section equipped with a heater.

[0018] In the dewatering section of the device, a screw rotates inside the screen drum, squeezing the crushed pieces that have been put inside, causing moisture to seep out. The water collected in the wastewater sump 15a is then sent to the reaction pool 17, where a pH adjuster is added to neutralize the chlorine, i.e., remove the chlorine, and the water is further treated as sewage. In addition, sediments are removed as foreign matter.

[0019] In the drying section of the equipment, the dehydrated crushed pieces are lightly dried and turned into fluff before being discharged. This fluff, shown in Figure 4, is broken up and solidified to the extent that it can be transported to the subsequent stage. Once it becomes fluff-like, the moisture content has been reduced to about 20-50%. By adjusting the operating conditions of the dehydration wet granulator, it is possible to limit the process to fluffing without granulating. Note that heating produces steam containing chlorine gas, but this steam is deodorized appropriately via a gas pipe before being discharged outside the system.

[0020] The fluff falls to the rear side of the conveyor constituting the neutralizing agent adding section 19 in the conveying direction. This conveyor is constructed in the same manner as the conveyor constituting the decomposing liquid adding section 5, and the chlorine neutralizing agent is sprayed onto the fluff in the pipe through multiple spray nozzles 19a on the ceiling side of this conveyor. The fluff is stirred as it is transported, and the side facing the ceiling is constantly changed, so that chlorine neutralizer is evenly added to the fluff. The SAP decomposition solution, hypochlorous acid water, is alkaline, and the chlorine neutralizer is neutralized, but the neutralization here is a process to neutralize, or remove, the available chlorine, and there is no requirement to strictly neutralize the pH.

[0021] The conveyed fluff then falls from the leading end of the conveying direction into the granulation section 21. Like the dehydration section 15, this granulation section 21 is composed of a dehydration wet granulation machine (DPF series, manufactured by KUN SHENG MACHINE CO., LTD., sold by Plant Systems Co., Ltd. (the applicant of the present application)), which is an actual machine described in Utility Model Registration No. 3168801. However, in this embodiment, the part of the dehydration section 15 that functions as a drying section with a heater functions as a granulation section.

[0022] The fluff with the chlorine neutralizer absorbed is forced between the fixed blade and the rotating blade to form granules. The device is equipped with a powerful heater, which causes the water to evaporate and turn into steam, and the plastic that made up the nonwoven fabric melts partially, coating the granules. This keeps the granules in a solid state and prevents them from breaking apart during subsequent transport. The chlorine neutralizer also permeates the granules and is sealed in. This granulation product is shown in FIG. The steam generated by heating is deodorized appropriately through a gas pipe and then discharged outside the system.

[0023] The calorific value (calories) required for solid fuel varies depending on the application, so additives can be added at this stage to increase or decrease the calorific value. For example, plastics can be added to increase the calorific value, and paper can be added to decrease the calorific value. Used disposable diapers are general waste, so if no contaminants are added, the solid fuel becomes RDF. If plastics or paper contained in general waste are mixed in, the solid fuel will be RDF. On the other hand, if plastics contained in industrial waste are mixed in, the solid fuel will be RPF.

[0024] The system is closed from the crushing section 3 to the granulation section 21, but is open thereafter, and the granulated material falls to the rear of the conveyor 23 installed in this open area in the conveying direction. This conveyor 23 is made up of a belt conveyor and is inclined so that the leading end in the conveying direction is higher. A cooling blower 25 is installed above the conveyor 23, and mist is sprayed from the cooling blower 25 onto the still hot granulated material, which cools it by absorbing heat as the heat of vaporization of the mist.

[0025] The granulated material is then stored as solid fuel (RDF or RPF), and after the chlorine neutralizer is added, the available chlorine is neutralized by the chlorine neutralizer, including during the storage period. Therefore, when it is actually used as solid fuel (RDF or RPF), chlorine gas is not generated. In addition, the moisture content is reduced to 10% or less. Since the water still retains heat even after passing through the cooling blower 25, an automatic flame detection water sprinkler system is provided to prevent fires.

[0026] The treatment section extending from the decomposition liquid addition section 5 to the neutralizing agent addition section 19 is connected to an inflow system for introducing wash water containing a chlorine neutralizing agent, as shown by the arrows, and both the drainage system for this wash water and the drainage system from the dehydration section 15 are connected to the reaction pool 17. Therefore, the inside of the closed system can also be cleaned appropriately.

[0027] The continuous processing system 1 for used disposable diapers is configured as described above, and when used disposable diapers are fed into the shredding section 3, they are then processed sequentially in each processing section and extracted as solid fuel (RDF or RPF) from the granulation section 21. Moreover, by using an existing dehydration wet granulator, a practical system can be easily constructed without the need for a separate drying process. Furthermore, no water is required to process used disposable diapers, and only the water (including hypochlorous acid water) released from the used disposable diapers and the washing wastewater are discharged outside the system, so the amount of wastewater is small. It is a continuous system, and as used disposable diapers are fed in, they are gradually converted into solid fuel, so the processing volume is large. Even with the current test equipment, it is possible to process 400 to 500 kg / h. In other words, in this continuous processing system 1 for used paper diapers, the material is dehydrated in the dehydration section 15 to form a fluff, and after a chlorine neutralizer is added, it is granulated in the granulation section 21.The dehydration process and the chlorine removal process work together well, eliminating the need for large amounts of water or a large-scale drying process.

[0028] Although the embodiments of the present invention have been described in detail above, the specific configuration is not limited to these embodiments, and the invention also includes design changes within the scope of the present invention without departing from the gist of the present invention. For example, the specific structure of the device that constitutes each processing section is not limited as long as it achieves the respective processing purpose. [Industrial Applicability]

[0029] It can be used to recycle used disposable diapers. [Explanation of symbols]

[0030] 1. Continuous disposal system for used disposable diapers 3... Crushing section 5... Decomposition liquid addition section 9... Reaction tank 15... Dehydration section 19... Neutralizing agent addition section 21... Granulation section 25...Cooling blower

Claims

1. The apparatus comprises a crushing section for crushing used disposable diapers into crushed pieces, a decomposition liquid adding section for adding a chlorine-based SAP decomposition liquid to the crushed pieces, a dehydration section for dehydrating the crushed pieces into fluff, a neutralizing agent adding section for adding a chlorine neutralizing agent to the fluff, and a granulating section for wet granulating the fluff after adding the neutralizing agent, This is a continuous processing system for used disposable diapers, characterized in that after used disposable diapers are fed into the crushing section, they are then processed sequentially in each processing section and discharged as solid fuel from the granulation section.

2. 2. The continuous processing system for used disposable diapers according to claim 1, A continuous processing system characterized by a dehydration section and a granulation section that realizes fluffing and granulation in a wet state using a dehydration wet granulator.

3. 3. The continuous processing system for used disposable diapers according to claim 1 or 2, A continuous processing system characterized by providing a waiting section between the decomposition liquid addition section and the dehydration section, in which the crushed pieces are kept waiting until a syneresis reaction occurs.

4. 4. The continuous processing system for used disposable diapers according to claim 3, A continuous processing system characterized in that the crushed pieces are agitated in the decomposition liquid addition section.

5. 5. The continuous processing system for used disposable diapers according to claim 4, A continuous treatment system characterized in that an inflow system for introducing wash water containing a chlorine neutralizing agent is connected to a treatment section extending from the decomposition liquid addition section to the neutralizing agent addition section, and the drainage system for this wash water and the drainage system for the dehydration section both communicate with a reaction pool.

6. 6. The continuous processing system for used disposable diapers according to claim 5, This continuous processing system is characterized in that the granulation section can add additives to adjust the calorific value of the solid fuel.

7. 7. The continuous processing system for used disposable diapers according to claim 6, A continuous processing system characterized by being provided with a cooling blower that removes the heat of vaporization from the granulated material discharged from the granulation section.

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