JP2012031283A - Method of manufacturing fuel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of efficiently manufacturing solid fuel which is easily pulverized and used by hardly causing thermal degradation of waste plastics containing vinyl chloride and separating only chlorine at low temperature for facilitating waste heat.SOLUTION: In the method, waste plastics containing vinyl chloride are processed at 220-300°C in an external treatment apparatus with agitation which is filled with water vapor. The external treatment apparatus is selected from a kiln, a two axes paddle mixer and a multistage dryer.

Description

  The present invention relates to a method for producing fuel from PVC-containing waste plastic.

Waste plastics are used as alternative fuels in furnaces such as boilers and cement kilns, but the amount of waste plastics containing PVC has been limited due to corrosion of boilers and adverse effects on cement quality. For this reason, a large amount of waste plastic such as automobile shredder dust (ASR) and construction waste plastic is buried or incinerated.
However, securing landfills has become more difficult every year. In order to limit greenhouse gas emissions, it is desirable that waste plastic be used as fuel without being incinerated to reduce the amount of fossil fuel used.

  Conventionally, in order to promote the thermal recycling of waste plastics having a high chlorine content, application of superheated desalination and gasification processes has been studied. However, although these technologies have been commercialized, none of them are widely used. Further, in the overheated desalination and gasification process, since it operates at a high temperature of 350 ° C. or higher, it is common to use fossil fuel or the like as a heat source.

For example, Patent Document 1 describes a method of heating and carbonizing a polymer material such as vinyl chloride-containing waste plastic in a supersaturated steam atmosphere at a temperature range of 150 to 350 ° C., and recovering dry distillation gas without burning it. It is described that it can be removed.
However, carbonization of the polymer material takes too much time in this temperature range, so it is necessary to directly heat the polymer material with far infrared rays, and the effect of the far infrared rays is crushed to 5 cm or less as a pretreatment, It was necessary to heat and reduce the volume of the foam beforehand.
In general, when a polymer material is carbonized, the dry distillation gas often condenses or polymerizes in the exhaust gas duct of the carbonization apparatus and adheres in a tar-like shape, often causing trouble.
Furthermore, carbonization generates many types of products such as carbonized gas, carbides, pyrolysis oil, tar-like products, waste liquids, etc., and a large amount of equipment and costs are required to use them effectively. There is a problem.

Patent Document 2 describes a solid fuel in which a finely pulverized fuel is dispersed and integrated inside a carbonized fuel obtained by desalting waste plastic containing vinyl chloride. The solid fuel is waste plastic containing vinyl chloride. It is described that it is manufactured by heating to 300 to 380 ° C. while mixing by scraping and dropping the pulverized fuel.
In this method, generally, at 300 ° C. or higher at which a desalting reaction occurs by heat desalting, molten waste plastic and powder are mixed, and a solid that is easily pulverized is recovered and converted into fuel. The pulverized fuel to be mixed is required to have a small amount of gasified by pyrolysis. This is because gasification occurs at a temperature of 300 to 380 ° C., and depending on the material and temperature, there is a problem that the recovery rate of the solid fuel decreases and the equipment for processing the generated gas becomes large. .

In Patent Document 3, as an anti-fusing agent, dust or pulverized coal accompanying the combustion gas after burning an organic substance is supplied to a heating furnace together with waste plastic, and at a pressure lower than atmospheric pressure and / or containing oxygen. A method for producing a solid raw fuel that is heated and pyrolyzed while supplying a gas is described.
However, this method has a problem that it requires equipment such as pressure adjustment and supply of oxygen gas, and heat treatment at a high temperature.

JP 2005-15555 A JP 2009-235215 A JP 2009-269965 A

  Accordingly, an object of the present invention is to efficiently produce a solid fuel that is easy to use and separate waste fuel, at a low temperature that makes it easy to use waste heat, without pyrolyzing the waste plastic containing vinyl chloride, separating only chlorine, and easily crushing. It is to provide a method.

  As a result of various investigations in view of such circumstances, the present inventors have efficiently removed chlorine by treating an object to be treated at 220 to 300 ° C. in a heat treatment apparatus filled with water vapor, The present invention was completed by finding that it can be produced.

  That is, this invention provides the manufacturing method of the fuel characterized by processing vinyl chloride containing waste plastic at 220-300 degreeC in the heat processing apparatus filled with water vapor | steam, stirring.

  According to the present invention, vinyl chloride-containing waste plastic can be decomposed with less energy, chlorine can be efficiently removed, and fuel can be efficiently produced by continuous treatment at normal pressure. Further, the obtained fuel has a high total calorific value and good grindability.

  Examples of the vinyl chloride-containing waste plastic used in the present invention include ASR, construction waste plastic, pulper residue, container packaging waste plastic sorting residue, and the like.

In the present invention, the vinyl chloride-containing waste plastic as described above is continuously charged into a heat treatment apparatus at 220 to 300 ° C. and almost atmospheric pressure filled with water vapor, and the treatment is performed while stirring.
As the heat treatment apparatus, for example, an external heat processing apparatus such as a kiln, a twin-screw paddle mixer, a multistage dryer, or the like can be used.

In addition, as a method of introducing water vapor into these apparatuses, (a) introducing water vapor into the processing apparatus as raw material moisture, (b) introducing saturated water vapor directly into the processing apparatus, (c) sliding part seal of the processing apparatus Examples thereof include (d) a method of introducing superheated steam that is introduced as a gas.
Furthermore, in order to obtain a superheated steam atmosphere at 220 to 300 ° C., in the case of (a) to (c), a method of superheating steam and raw materials by using an external heating type processing apparatus can be adopted. In the case of (d), the raw material can be heat-treated only with superheated steam, but the raw material can also be heat-treated in combination with external heating.
The amount of water vapor to be introduced varies depending on the shape of the heat treatment apparatus, the filling rate, the chlorine content of the waste plastic to be treated, the moisture content, the properties, etc., and is not particularly limited. For example, if the amount of water vapor to be circulated is small, the water vapor may condense in an unheated portion of the heat treatment apparatus and become concentrated hydrochloric acid, which must be mixed with the processed material. On the other hand, if the amount of water vapor is large, the energy for producing water vapor becomes enormous and energy efficiency is lowered, which is not preferable.

The treatment temperature is 220 to 300 ° C, but 250 to 280 ° C is particularly preferable, and the treatment is preferably performed for about 30 to 60 minutes.
As a heat source for heat treatment equipment, low-temperature waste heat such as cement kilns, waste incinerators, etc. can be used efficiently and can be processed at low cost, and can be processed safely without worrying about explosions. .

In this invention, when processing a vinyl chloride containing waste plastic, an organic substance containing granular material can be mixed and processed.
Through the treatment as described above, chlorine is separated from the vinyl chloride in the waste plastic and is exhausted together with water vapor as HCl. However, depending on the type of waste plastic, etc., it may melt during processing and adhere to the processing equipment and cause troubles. It may be difficult to be done.
In such a case, when the organic substance-containing powder is mixed and processed, the powder exhibits the effect of preventing the waste plastic from fusing, enabling stable processing and processing with good pulverizability. Can be obtained.

Examples of the organic substance-containing granular material include dry sewage sludge, sewage sludge carbide, coke dust, wood waste and the like.
It is preferable that the organic substance-containing granular material is mixed so that the total amount of the ash derived from the waste plastic and the organic substance-containing powder is 20 to 60% by mass, particularly 30 to 50% by mass in the entire processed product.
In Patent Document 2, a pulverized fuel with a small volatile content is used as a powder to be mixed with molten plastic. This is stipulated in order to reduce the recovery rate of solid fuel, to reduce the amount of gas generated, and to reduce the cost of gas / waste water treatment equipment, because the plastic is frequently decomposed and gasified at 300 to 380 ° C. It is what.
In the present invention, since the treatment is performed at a low temperature at which thermal decomposition hardly occurs, it is not necessary to limit the volatile content of the powder mixed with the molten plastic.

Chlorine decomposed and vaporized in the heat treatment apparatus is led out of the apparatus together with water vapor.
Steam discharged from chlorine containing chlorine can be removed with a scrubber using water containing alkali components, or after a hydrochloric acid recovery facility recovers hydrochloric acid, a small amount of residual gas can be used as cement kiln combustion air. It is possible to use by deodorizing by combustion in the heat source of the desalination facility.

On the other hand, the solid content obtained after the treatment is used as a regenerated solid fuel.
This solid content has a chlorine concentration reduced to about 0.5% by mass and can be used as a fuel as it is.
In addition, the chlorine contained in the waste plastic is sufficiently removed, but other chemical components that can be used as fuel (carbon, hydrogen, etc.) are hardly removed, so the total calorific value when used as a solid fuel is also low. It is expensive.

In addition, the fuel obtained by the present invention also has good pulverizability.
For example, it is preferable that the ratio of the particle size of 1.5 mm or less is 90% or more as a condition that the solid fuel can be suitably used in the cement kiln, but the fuel of the present invention can be pulverized to such a particle size. It is.

Example 1
An external heating kiln (an external heating rotary kiln (inner diameter 500 mm × length 4950 mm (heating part length 3000 mm)) using propane gas as a heat source) is heated so that the temperature of the raw material becomes a predetermined processing temperature. Steam was fed from the hood, and the residence time was adjusted by the number of revolutions of the kiln Table 1 shows the treatment temperature, residence time, and residual chlorine amount when automobile shredder dust and construction mixed waste plastic were treated.

  In addition, the chlorine concentration used the value measured by the Eshka method, and the desalination rate was computed by following Formula.

  The yield was calculated from the following equation.

When the treatment temperature is 220 to 300 ° C., a sufficient desalting effect is obtained and the yield is also good.
On the other hand, at 200 ° C., a sufficient desalting effect cannot be obtained, and at 350 ° C., the yield decreases.
Yield decreases due to evaporation of moisture inherent in the raw material, dust dissipation, and volatilization / pyrolysis gasification of organic substances. At 300 ° C., volatilization / pyrolysis gasification of organic substances is considered to start, which leads to loss of heat and places a load on the treatment of exhaust gas, so heating above 300 ° C. is not preferable.

Example 2
An external heating kiln (an external heating rotary kiln (inner diameter 500 mm × length 4950 mm (heating part length 3000 mm)) using propane gas as a heat source) is heated so that the temperature of the raw material becomes a predetermined processing temperature. Steam was fed from the hood, and the residence time was adjusted by the number of rotations of the kiln. The remaining amount of chlorine and the desalting rate were determined in the same manner as in Example 1. The results are shown in Table 2.

(1) Processing conditions:
Processing temperature: 250 ° C
Residence time: 60 minutes (2) Materials:
Volume residue: Specific gravity separation residue (heavy residue) Chlorine = 3.2%, moisture 8%
Powder: Dry sewage sludge 0.06% chlorine, 1.2% moisture

Residue residue is mainly composed of vinyl chloride or olefinic resin with aluminum attached, and when only the residue is treated, the molten resin tends to adhere to the kiln, resulting in poor discharge. .
On the other hand, when dry sewage sludge was blended at a ratio of 20 to 60 parts by mass with 80 parts by mass of the residue, adhesion to the kiln was eliminated.

Claims (5)

  A method for producing a fuel, characterized in that a vinyl chloride-containing waste plastic is treated at 220 to 300 ° C in a heat treatment apparatus filled with water vapor while stirring.   The manufacturing method according to claim 1, wherein the vinyl chloride-containing waste plastic and the organic matter-containing granular material are mixed and processed.   The manufacturing method of Claim 2 whose mass ratio of the organic substance containing granular material in all the processed materials is 20-60 mass%.   The manufacturing method according to any one of claims 1 to 3, wherein the heat treatment apparatus is an external heat treatment apparatus selected from a kiln, a twin-screw paddle mixer, and a multistage dryer.   Water vapor is introduced into the processing equipment as (a) raw material moisture, (b) saturated steam is introduced directly into the processing equipment, (c) is introduced as a sliding part seal gas of the processing equipment, or (d) superheated steam is introduced. The manufacturing method of any one of Claims 1-4 introduce | transduced into a processing apparatus by this.