JP3321598B2 - Carbon-containing solid held on carbonaceous carrier, method for producing the same, and method for producing methane - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a carbon-containing solid held on a carbonaceous carrier, a method for producing the same, and a method for producing methane.

[0002]

2. Description of the Related Art When an organic substance is thermally decomposed, a pyrolysis product gas and a pyrolysis residue are generated. The pyrolysis gas contains a large amount of condensable organic gas useful as fuel oil or the like, and is used as a fuel oil raw material or the like. on the other hand,
The pyrolysis residue is used as a raw material for char, coke, carbon material and the like. Therefore, when the organic waste is recycled, the pyrolysis method can be important. In particular, the pyrolysis method is particularly useful in that plastics and flame-retardant raw materials that cause various problems in ordinary incineration can be converted into adsorbents and building materials. Generally, in the pyrolysis process, condensable organic products collectively called tar are produced as by-products. In a conventionally proposed thermal decomposition process, a method of recovering this condensable organic product to be used as a chemical raw material or as a power for a plant or a fuel for thermal decomposition is being studied. Except for the high-temperature carbonization technology intended for metallurgical coke, the pyrolysis process is operated at 400 to 600 ° C. for reasons such as maintaining the thermal efficiency of the process. The condensable products generated in this temperature range are collectively called low-temperature tars, and are rich in unsaturated hydrocarbons, oxygen, and nitrogen-containing functional groups, and are chemically unstable substances that easily undergo polycondensation and oxidation reactions. It is. Further purification and stabilization are required to convert such materials into chemical raw materials, and burning requires special techniques and equipment capable of coping with the ever-changing viscosity and the like. If the condensable pyrolysis products are supplied in a large amount and stably, the above-mentioned utilization method may be economically feasible, but the scale of the apparatus is small and the operation rate is often not increased. Regional supply is limited and often fluctuates with season and economic conditions.
R> If the fixed cost burden on the product cost increases and the variable cost cannot be reduced, it will not be profitable. In addition to the economic downside of such a process system, there are also many technical issues. Some of the condensable products generated during the thermal decomposition process are liquefied on the inner wall of the device and flow down on the wall during the cooling process, but most of them are condensed into fine droplets to form mist, producing gas. Floating inside. Since the mist cannot be effectively captured even when cooled from the outside, the mist adheres and accumulates on the inner walls of all devices downstream of the thermal decomposition reactor, and eventually solidifies. As a result, various blockages and operational obstacles called tar troubles occur.

For the separation and removal of condensable products, a scrubber system using water is generally used. However, it is difficult to completely remove mist-like condensable products with a scrubber, and in many cases, a filter must be used in the subsequent stage. In this case, since the components condensed in the filter medium of the filter solidify with time and become clogged, frequent replacement of the filter medium is required, and maintenance requires labor and cost. Further, in the scrubber system, wastewater treatment of used water imposes a heavy burden. Aromatic compounds such as phenol dissolved in wastewater have high carcinogenic properties, act as environmental hormones, have high environmental pollution, are hardly susceptible to microbial degradation, and impose a heavy burden on the treatment. It is also disassembled,
A large amount of water is mixed and dissolved in oil called tar, which often makes chemical use and combustion disposal difficult. In other words, the wet processing method has many disadvantages, and some dry processing technology is desired.

[0004]

SUMMARY OF THE INVENTION The present invention relates to a carbon-containing solid formed by solidifying a condensable organic substance contained in a pyrolysis product gas obtained when an organic substance is thermally decomposed by an adsorbent and solidifying the same. It is an object of the present invention to provide a production method and a method for producing methane using the carbon-containing solid as a raw material.

[0005]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have completed the present invention. That is, according to the present invention, a process for preparing solid carbonaceous held in coal quality carrier, (i) thermal decomposition step of organic materials by pyrolysis to produce a pyrolysis product gas and the pyrolysis residue, (ii A) a capturing step in which the pyrolysis product gas is brought into contact with a carbonaceous carrier to trap mist-like condensable organic substances contained in the gas on the carbonaceous carrier; A polymerization step of forming a carbon-containing solid by polymerizing a polymerizable component contained therein in an organic substance,
And a method for producing a carbon-containing solid held on a carbonaceous carrier. Further, according to the present invention, in a method for producing methane by reacting a carbon-containing raw material with hydrogen, the method comprises using a carbon-containing solid held on the carbonaceous carrier as the carbon-containing raw material. A manufacturing method is provided.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION As the organic substance used as a raw material for thermal decomposition in the present invention, various kinds of conventionally known organic substances can be used as long as they can be thermally decomposed. Such organic substances include coal tar, petroleum distillation residues, coal-based and petroleum-based pitch, in addition to various plastic wastes. As the carbonaceous carrier used in the present invention, various carbon-containing substances which are solid at a temperature at which the organic substance is thermally decomposed can be used. The carbonaceous carrier includes various types of coal and carbon (charcoal, carbon black, etc.). This carbonaceous carrier is usually used in a powder form, and has an average particle size of 0.1 to 50 μm, preferably 1 to 10 μm.
It is.

Next, the present invention will be described with reference to the drawings.
FIG. 1 shows an example of a flow sheet for producing a carbon-containing solid held on a carbonaceous carrier according to the present invention. In FIG. 1, 1 indicates a thermal decomposition step, 2 indicates a solid-gas separation step, 3 indicates a polymerization step, and 4 indicates a gas purification step.

In order to carry out the present invention in accordance with the flow sheet shown in FIG. 1, raw material organic matter is introduced into a pyrolysis step 1 through a line 11, where it is pyrolyzed. The thermal decomposition temperature is usually from 350 to 600C, preferably from 400 to 550C. The pyrolysis of the organic matter produces a pyrolysis product gas and a pyrolysis residue. The pyrolysis product gas is extracted through line 13, while the pyrolysis residue is exhausted through line 12. The pyrolysis gas consists of condensable organic substances that condense and liquefy when cooled to room temperature, and non-condensable gases that do not condense and liquefy. The condensable organic matter generally depends on the type of the raw material organic matter, but is generally an aliphatic saturated hydrocarbon, an aliphatic unsaturated hydrocarbon, an aromatic hydrocarbon, and a non-hydrocarbon compound ( Oxygen-containing compounds and nitrogen-containing compounds). Non-condensable gases include hydrogen, methane,
Lower hydrocarbons such as ethane, ethylene and propane are included. The pyrolysis residue is composed of a high-boiling tar substance having a boiling point of 500 ° C. or higher, a carbon substance, or the like. This can be used as a raw material for producing a solid fuel.

In the pyrolysis gas line 13, a carbonaceous carrier is added from a line 14 in order to capture condensable components contained in the generated gas and to separate the condensable components from the gas, and the gas is brought into contact with the pyrolysis gas. . When the pyrolysis product gas is brought into contact with the carbonaceous carrier, the condensable organic matter in the gas has a high carbon ratio and a high affinity with the carbonaceous carrier, so that the carbonaceous carrier can be efficiently treated. Be captured. The amount of the carbonaceous carrier added to the produced gas is 0.5 to 20 parts by weight, preferably 1 to 5 parts by weight, per 1 part by weight of the condensable organic substance contained in the gas. When the carbonaceous carrier is added to the pyrolysis gas line as described above, the carbonaceous carrier is preferably in the form of fine particles, and usually has an average particle size of 0.1 to 5 μm, more preferably. Is 1-5μ
m.

As described above, the condensable organic matter captured on the carbonaceous carrier is introduced into the solid-gas separation step 2, where it is separated from the gas and sent to the polymerization step 3 through the line 15. On the other hand, the gas from which the condensable organic matter captured by the carbonaceous carrier has been separated is sent to the gas purification step 4 through the line 16.

The solid-gas separation step 2 is carried out using a solid-gas separation device. In this case, any device having a structure capable of separating solid particles contained in a gas can be used. May be. Examples of such a device include a bag filter, an electric dust collector, and a cyclone. The solid-gas separation step can be performed under the same high temperature condition as the thermal decomposition temperature, but is preferably performed at a reduced temperature, for example, 200 to 400 ° C. For this purpose, the gas introduced into the solid-gas separation step may be cooled using a heat exchanger.

When the solid-gas separation is performed by a bag filter, the carbonaceous carrier capturing the condensable organic matter is deposited on the filter surface over time.
Shows excellent filter action. The amount of sediment increases,
When the pressure loss becomes large, the deposit is peeled off from the filter surface by, for example, backwashing the filter.

In the gas refining step 4, impurity gases such as SO ₄ contained in the gas are removed. The gas from which such compounds have been removed is a combustible gas containing hydrogen, as well as lower hydrocarbons such as methane and ethane, and is used as a fuel for power generation or industrial fuel.

In the polymerization step 3, the condensable organic substance adsorbed and held on the carbonaceous carrier is polymerized to a high molecular weight and solidified. The condensable organic substance obtained by decomposition of the organic substance contains a polymerizable component such as an unsaturated compound or an oxygen-containing compound, is unstable, is very easily polymerized, and easily has a high molecular weight. In the present invention, utilizing such properties of the condensable organic matter contained in the pyrolysis product gas, the condensable organic matter is polymerized to a high molecular weight and solidified.
Polymerization of the condensable organic substance by polymerization is carried out by bringing it into contact with oxygen or an oxygen-containing gas, for example, air.
Irradiation with ultraviolet rays or heating can be performed within a range in which a large amount of volatile components does not evaporate.

The product obtained in the polymerization step 3 has a structure in which a carbon-containing solid (polymerized solidified condensable organic substance) is relatively strongly bonded and held on a carbonaceous carrier.
Handling, such as transportation, crushing, and supply, is possible.

The carbon-containing solid retained on the carbonaceous carrier obtained as described above can be advantageously used as it is as a raw material for producing methane. To produce methane from a carbon-containing solid held on a carbonaceous support, the raw material is
It is reacted with hydrogen at a temperature of 00 to 1100 ° C and a pressure of 3 to 7 MPa. By this reaction, the carbon-containing solid on the carbonaceous carrier reacts with hydrogen and is converted into methane,
The carbonaceous carrier itself reacts with hydrogen and is converted to methane. In the present invention, the carbon-containing solid held on the carbonaceous carrier can be supplied to an existing hydrogasification furnace using coal as a raw material to be gasified (methaned).

As a method of trapping condensable organic substances contained in the pyrolysis gas from organic substances in the carbonaceous carrier, other than the method of adding the particulate carbonaceous carrier to the pyrolysis gas as described above. There are various methods. Examples of such a method include a method in which a pyrolysis gas is passed through a packed bed of a fixed bed or moving bed system packed with a carbonaceous carrier, and a fluidized bed filled with a powdered carbonaceous carrier, for fluidization. Examples of the method include a method of supplying a pyrolysis gas as a gas and a method of flowing the pyrolysis gas through a filter made of a carbonaceous carrier.

[0018]

Next, the present invention will be described in more detail with reference to examples.

EXAMPLE In this example, as a raw material to be treated, a plastic mixture (50% by weight of polyethylene and polypropylene 5%) was used.
0% by weight). In addition, coal powder (average particle size: 10 μm) was used as the carbonaceous carrier. A reaction tube was filled with 100 parts by weight of the plastic mixture and heated to a temperature of 400 ° C. while flowing nitrogen gas, and the pyrolysis product gas obtained at that time was discharged through a cooled glass tube filled with coal powder. The mixture was circulated at a temperature of 50 ° C., and the condensable components in the gas were captured by the coal powder. Next, after the thermal decomposition reaction of the plastic mixture, air was passed through the glass tube filled with the coal powder at an outlet temperature of 50 ° C. to polymerize and solidify the condensable organic matter trapped in the coal powder. This polymerized solid had no tackiness, had fluidity, and had good handling properties. Next, a gas composed of 10 vol% of hydrogen gas and 90 vol% of nitrogen gas was placed in the glass tube filled with the coal powder.
The mixture was allowed to flow at an outlet temperature of 850 ° C. and a pressure of 40 atm, and the flowing gas discharged from the glass tube was analyzed. As a result, it was confirmed that a gas containing methane as a main component was obtained.

[0020]

According to the present invention, the condensable organic substances contained in the gas generated by the thermal decomposition of various organic substances such as plastic wastes are captured by the carbonaceous carrier and separated from the gas. The condensed organic matter is effectively prevented from condensing on the pipe inner wall surface or the apparatus inner wall surface downstream of the thermal decomposition step. Further, the carbon-containing solid held on the carbonaceous carrier of the present invention is a material having good handleability, and together with the carbonaceous carrier, can be used as a raw material for methane production, and can be used as a solid fuel or the like. it can. Since the present invention is used as a method for effectively utilizing the organic waste at the same time as the treatment of the organic waste, its industrial significance is great.

[Brief description of the drawings]

FIG. 1 shows an example of a flow sheet for producing a carbon-containing solid held on a carbonaceous carrier according to the present invention.

[Explanation of symbols]

 1 Thermal decomposition process 2 Solid-gas separation process 3 Polymerization process 4 Gas purification process

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-60-32894 (JP, A) JP-A-4-25594 (JP, A) JP-A-61-73795 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) C10B 53/00 C01B 31/00 C07C 1/00 C07C 9/04

Claims (2)

(57) [Claims] 1. A method for producing a carbon-containing solid held on a carbonaceous carrier, comprising: (i) a pyrolysis step of pyrolyzing an organic substance to generate a pyrolysis product gas and a pyrolysis residue;
A capturing step in which the pyrolysis product gas is brought into contact with a carbonaceous carrier to capture mist-like condensable organic matter contained in the gas on the carbonaceous carrier; (iii) the organic matter captured by the carbonaceous carrier A polymerization step of polymerizing a polymerizable component contained therein to obtain a carbon-containing solid, comprising the steps of: (a) producing a carbon-containing solid held on a carbonaceous carrier; 2. A method for producing methane by reacting a carbon-containing raw material with hydrogen, wherein the carbon-containing raw material is used as the carbon-containing raw material.
A method for producing methane, comprising using a carbon-containing solid held on a carbonaceous carrier as described above.