JP4441364B2 - Resin-based waste recycling method - Google Patents

Description

The present invention relates to a waste recycling method for recovering gas and / or oil by thermally decomposing waste mainly composed of resin, and relates to an improvement in increasing a material recycling ratio and effective use of resources, in particular, heat. The present invention relates to a processing method for controlling the composition and recovery rate of gas and oil obtained after decomposition.

Examples of a single system for carbonizing waste such as waste tires and plastics to obtain carbonization gas, recovered oil, and carbides are disclosed in JP-A-49-111986, JP-A-51-135983, and the like. There are many.
For example, in Japanese Patent Laid-Open No. 2000-296378, in the gasification of waste, the reduction in the calorific value of the high gasification gas is prevented without forming oil, and in the incineration of waste, Disclosed is a waste treatment method that can reduce the amount of harmful substances. When gasifying organic waste, it is used as a gasification accelerator in the gasification furnace, when incinerating organic waste, as a combustion accelerator in the combustion field, as a hazardous substance decomposition agent in incineration ash, and as an exhaust gas. In this method, high-temperature steam at 600 ° C. or higher is introduced as a harmful substance decomposing agent.
However, there are problems in that it is expensive to industrially obtain superheated steam at 600 ° C. or higher, and the amount of heat generated from the recovered gas also decreases.

On the other hand, Japanese Patent Application Laid-Open No. 2002-336673 discloses a method for decomposing organic waste with a superheated steam at 550 ° C. or less as a high-speed decomposition method for organic waste.
However, this prior art is a method of oxidizing and decomposing organic waste by all or any combination of oxidation reaction with oxygen in the air and drying, hydrolysis reaction and thermal decomposition reaction with superheated steam. In order to make it a heat source, nothing is shown regarding the control of the composition and recovery rate of the gas and oil recovered by the thermal decomposition which is the subject of the present invention.
Japanese Patent Application Laid-Open No. 2002-322481 discloses a method of carbonizing organic waste in an atmosphere of superheated steam.
However, this prior art replaces the air in the furnace with superheated steam, thereby forming a good carbonized atmosphere of organic matter with a very low oxygen concentration in the furnace. Nothing is shown regarding the control of the composition and recovery rate of gas and oil recovered by thermal decomposition.
JP-A-49-111986 Japanese Patent Laid-Open No. 51-135983 JP 2000-296378 A JP 2002-336673 A Japanese Patent Laid-Open No. 2002-322481

As mentioned above, various proposals for the recycling of waste mainly consisting of resin have been made for the establishment of a recycling-oriented society. There were also many unresolved issues such as the need to maintain high quality and recovery rate of recovered gas and oil.
Therefore, the present invention can recycle wastes mainly made of resin, which can recycle high-value-added gas and oil without variation in cheaper equipment. It is an object to provide a resource recycling method.

The present invention solves the problems of the prior art as described above, supplies steam during thermal decomposition, and controls the composition and / or recovery rate of the recovered gas and / or oil, thereby reducing the cost. It provides a method for recycling waste mainly consisting of resin, which can stably recover and recycle high value-added gas and oil in a simple facility. It is the following contents as described in the claims.
(1) In a waste recycling method in which waste mainly composed of resin is thermally decomposed to recover gas and oil , the thermal decomposition temperature is set to 600 to 700 ° C., and 300 ° C. during the thermal decomposition. A method for recycling waste mainly composed of resin, characterized by supplying less than water vapor and controlling the composition and / or recovery rate of the recovered oil .
(2) The steam supplied during the pyrolysis is steam generated by exchanging heat between the high-temperature gas generated by the pyrolysis and water. Recycling method.
(3) The waste recycling material according to (1) or (2), wherein the waste mainly composed of the resin includes one or more of waste tire, waste plastic, and shredder dust. Method.
(4) The waste recycling method according to any one of (1) to (3) , wherein the amount of water vapor introduced is controlled in accordance with a change in the pyrolysis gas composition.

  According to the present invention, high value-added gas and oil can be produced with less expensive equipment by supplying steam during thermal decomposition and controlling the composition and / or recovery rate of the recovered gas and / or oil. There are significant industrially useful effects, such as a method for stably recovering and recycling resources, and a method for recycling waste mainly composed of resin.

An embodiment of the present invention will be described in detail with reference to FIGS.
FIG. 1 is a process flow diagram illustrating an embodiment of a waste recycling method mainly composed of resin in the present invention.
In the present invention, when resin-containing waste mainly composed of resin such as waste tire, waste plastic, and shredder dust is thermally decomposed to recover gas and / or oil, water vapor is supplied during the thermal decomposition. Supplying water vapor increases the apparent gas volume in the furnace and shortens the residence time of the pyrolyzed gas in the furnace, thereby controlling the recovery rate and composition of gas and oil because the reaction time changes. It is possible to provide gas and oil with higher added value.
In particular, by exchanging heat between the gas recovered by pyrolysis and water, water vapor is produced by an aquatic gasification reaction and supplied at the time of pyrolysis. Steam can be supplied.

In addition, the composition of the oil and the oil, which is a pyrolysis product, changes according to the compositional variation of the target waste. Therefore, it is preferable to supply water vapor to be introduced into the pyrolysis furnace while observing this situation using means for grasping product properties such as gas composition analysis methods such as gas chromatography and FT-IR. In addition, by setting the temperature of water vapor to less than 300 ° C., the composition of gas and oil can be controlled to a constant value without significantly changing the recovery ratio of gas and oil. By controlling the composition of the gas or oil to a constant value, it is not necessary to make production adjustments such as a reduction in the operation rate of the next process due to gas shortage with the next process using the gas or oil.
In the present invention, the thermal decomposition method is not limited, but in order to recover the gas or oil, an indirect heating method such as an external heating type rotary kiln is preferable, and the thermal energy of the high temperature gas or oil is further increased. By using it as a heat source for the thermal decomposition treatment, the energy cost can be reduced.

FIG. 2 is a diagram showing the influence of water vapor used in the present invention on the quality of oil.
In FIG. 2, the horizontal axis represents the residence time index (min) in the pyrolysis gas furnace in consideration of the increase in the apparent gas volume when water vapor is supplied, and the vertical axis represents the weight loss rate at a thermobalance of 100 ° C. %) Indicates an oil quality index, and the lower this value, the smaller the ratio of light components such as light oil and the greater the yield of heavy oil. In FIG. 2, a circle indicates a case where no steam is supplied at a thermal decomposition temperature of 600 ° C. and a waste treatment rate of 170 kg / hr, and a triangle indicates a case where water vapor is not supplied at a thermal decomposition temperature of 650 ° C. and a waste treatment rate of 240 kg / hr. The symbol ● indicates the case where water vapor is supplied at a thermal decomposition temperature of 600 ° C. and a waste treatment rate of 170 kg / hr. In either case, the water vapor temperature is less than 300 ° C.
As shown by the dotted line on the right side of FIG. 2, by supplying water vapor, the apparent gas volume increases, so the residence time index (min) in the pyrolysis gas furnace decreases, and the oil quality index also decreases accordingly. Because the ratio of light components such as light oil in the oil is small and the ratio of heavy oil is high, it is possible to supply oil that is difficult to ignite and that can simplify the safety measures of the equipment.

Similarly, □ in FIG. 2 indicates that steam is not supplied at a pyrolysis temperature of 700 ° C. and a waste treatment rate of 420 kg / hr, and ■ indicates that steam is supplied at a pyrolysis temperature of 700 ° C. and a waste treatment rate of 420 kg / hr. In this case, an asterisk (*) indicates a case where excessive thermal decomposition is performed at a thermal decomposition temperature of 720 ° C. and a waste treatment rate of 170 kg / hr.
As shown by the dotted line on the left side of FIG. 2, by supplying water vapor, the apparent gas volume increases and the residence time index (min) in the pyrolysis gas furnace decreases, and the oil quality index also decreases accordingly. Because the ratio of light components such as light oil in the oil is small and the ratio of heavy oil is high, it is possible to supply oil that is difficult to ignite and that can simplify the safety measures of the equipment.
In addition, conventionally, in order to increase the ratio of heavy oil, the recovered oil may be distilled again, but according to the present invention, the ratio of heavy oil can be increased at the time of recovery. A re-distillation process is also unnecessary.

Using an externally heated rotary kiln having an inner diameter of 800 mm and a length of 6000 mm, a thermal decomposition experiment of waste mainly composed of resin was performed under the conditions shown in Table 1.
<Example-1 and Comparative Example-1>
An example of the present invention in which water vapor was supplied at a rate of 420 kg / h at the time of thermal decomposition at 80 kg / hr is Example-1, and a case in which water vapor was not supplied under the same conditions is Comparative Example-1. Since the apparent gas volume was increased by supplying water vapor, the residence time of the pyrolysis gas in the furnace was short, the calorific value of the gas was as high as 11000 kcal / Nm3, and the oil-light fraction was 20%. On the other hand, in Comparative Example-1, a decrease in the calorific value of gas and an increase in light oil were observed as compared to Example-1.
<Example-2 and Comparative Example-2>
Example 2 shows a case where the thermal decomposition temperature is 700 ° C., the tire supply amount is lower than that in Example 1, and water vapor is supplied at 120 kg / hr at the time of thermal decomposition at 260 kg / h. The case where there was no is Comparative Example-2. Compared with Example-1, in Comparative Example-2, the gas recovery rate and the oil / light fraction increase and the gas calorific value decreases. On the other hand, in Example-2, the gas recovery rate, the oil / light fraction, and the gas heating value were the same as in Example-1.

<Example-3 and Comparative Example-3>
Example in which the pyrolysis temperature is 700 ° C., the raw material conditions in Example-1 are changed, and mixed waste of 80% tire and 20% waste plastic is supplied at 300 kg / h and steam is supplied at 100 kg / hr during pyrolysis. -3, and the case where water vapor was not supplied under the same conditions is Comparative Example-3. In Comparative Example-3, the gas recovery rate and the oil / light fraction increase and the gas heating value decreases. On the other hand, in Example-3, the gas recovery rate, the oil / light fraction, and the gas heating value were the same as in Example-1.
<Experimental result>
As a result of this experiment, gas and oil can be recovered without changing the gas heating value and oil / light fraction by supplying water vapor during pyrolysis even when the pyrolysis raw material and feed rate change. It was confirmed that high-value gas and oil can be provided with inexpensive equipment.

It is a process flow figure which illustrates an embodiment of a recycling method of the waste which mainly has resin in the present invention. It is a figure which shows the influence which the water vapor | steam used for this invention has on the quality of oil.

Claims (4)

In a waste recycling method for thermally decomposing waste mainly composed of resin to recover gas and oil , the thermal decomposition temperature is set to 600 to 700 ° C., and water vapor of less than 300 ° C. is used during the thermal decomposition. And recycling the recovered oil to control the composition and / or recovery rate of the recovered oil .   2. The waste recycling method according to claim 1, wherein the steam supplied during the pyrolysis uses steam generated by heat exchange between high-temperature gas generated by the pyrolysis and water. .   The waste recycling method according to claim 1 or 2, wherein the resin-based waste includes one or more of waste tire, waste plastic, and shredder dust. The waste recycling method according to any one of claims 1 to 3 , wherein the amount of the steam introduced is controlled in accordance with a change in the pyrolysis gas composition.

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