JPH10216506A - Superheated steam decomposition device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cooling device which is adequately corrosion-resistive and is less costly by liquefying by cooing a gas produced by superheated steam decomposition in two stages. SOLUTION: This superheated steam decomposition device is equipped with a reaction device 8 for decomposing a hardly decomposable substance by superheated steam and a cooling device 9 provided on the downstream of the reaction device 8. In this case, the cooling device 9 comprises a first cooling means 9A which primarily cools a produced gas to be supplied from the reaction device 8 down to a specified temperature at which the gaseous state is maintained and a second cooling means 9B which cools and liquefies the produced gas cooled primarily by the first cooling means 9A. Thus, it is possible to cool and liquefy the produced gas with the help of the second cooling means 9B after cooling the produced gas down to a specified temperature while it is kept in a gaseous state showing no high corrosive properties through the process of the first cooling means 9A.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling device used for cracking superheated steam.

[0002]

2. Description of the Related Art Refractory substances such as environmental pollutants (for example,
As a method for decomposing and detoxifying fluorocarbons, trichloroethane, chlorobenzene, etc., a mixture of a hardly decomposable substance and a solvent (for example, water) is heated to a temperature (for example, 650 ° C.) higher than a predetermined temperature (normal evaporation temperature). A superheated steam decomposition method of decomposing a hardly decomposable substance by forming a vapor and maintaining the state for a predetermined time has been adopted.

[0003] When CFCs are decomposed by the above superheated steam decomposition method, the following hydrolysis is carried out.

CCl ₂ F ₂ + 2H ₂ O → CO ₂ + 2HF + 2HCl The product gas (carbon dioxide CO ₂ , hydrogen fluoride HF, hydrogen chloride HCl) decomposed by the above superheated steam decomposition method is in an overheated state (that is, 650 ° C.). Because of the high temperature gas of
After this is cooled and liquefied, it is necessary to perform a detoxification treatment (that is, a neutralization treatment with an alkali).

[0005]

However, when the product gas in a superheated vapor state (that is, 650 ° C.) is cooled and liquefied as it is, the hydrogen fluoride HF in the product gas is generated in the process.
When hydrogen chloride and HCl become an aqueous solution, it becomes a strongly acidic solution. Since this highly acidic solution has extremely high corrosiveness, even a cooling device using a special metal with excellent corrosion resistance, such as Hastelloy, Inconel, etc., can be corroded in a short time, making it unusable. It falls into. On the other hand, there is a synthetic resin such as Teflon as a material showing high corrosion resistance,
These have a problem in heat resistance and are in a superheated steam state (ie,
(650 ° C.) cannot be used for cooling the produced gas.

The present invention has been made in view of the above points, and provides a low-cost cooling apparatus which can sufficiently withstand corrosiveness by liquefying a gas generated by superheated steam decomposition in two stages. It is intended to provide.

[0007]

According to the basic structure of the present invention, as a means for solving the above-mentioned problems, there are provided a reactor for decomposing a hardly decomposable substance by superheated steam, and a cooling device provided downstream of the reactor. A first cooling means for primary cooling the cooling device to a predetermined temperature that maintains a gas state of the produced gas supplied from the reaction device, and the first cooling means. And second cooling means for liquefying the primary-cooled product gas.

[0008] With the above configuration, the produced gas is cooled down to a predetermined temperature by the first cooling means in a gas state which does not show high corrosivity, and then the produced gas is cooled and liquefied by the second cooling means. As the first cooling means, it is possible to use a cooling means having a structure in which only heat resistance is considered without considering corrosiveness, and a second cooling means can be used.
As a cooling means, a cooling means having excellent corrosion resistance can be used without giving much consideration to heat resistance.

In the basic structure of the present invention, the first cooling means includes: a heat transfer tube made of a material having excellent heat resistance, through which a product gas supplied from the reactor flows.
In the case where the heat transfer tube is constituted by a body on the outer peripheral side of the heat transfer tube and through which a refrigerant flows, it is possible to cool a high-temperature generated gas to a predetermined temperature by using a heat transfer tube mainly considering heat resistance without much considering corrosion resistance. This contributes to a reduction in the cost of the device.

[0010] The second cooling means may include a heat transfer tube made of a synthetic resin material having excellent corrosion resistance and a flow of product gas supplied from the first cooling means, and an outer peripheral side of the heat transfer tube. In the case where the apparatus is constituted by a container through which a refrigerant flows, it is possible to perform cooling and liquefaction of the generated gas using a heat transfer tube made of a low-cost synthetic resin material mainly considering corrosion resistance without considering heat resistance much. Contributes to cost reduction.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Some preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

First Embodiment FIGS. 1 and 2 show a superheated steam cracking apparatus according to a first embodiment of the present invention.

As shown in FIG. 1, the superheated steam decomposition apparatus supplies a substance to be decomposed (for example, a substance to be decomposed (eg, Freon X) supplied from a tank 1 through a flow control valve 2 and a flow meter 3). For example, a mixed steam generator 6 that mixes a fluorocarbon X) and a solvent (for example, water W) supplied from a solvent tank 4 by a pump 5 and heats the mixture to a predetermined temperature (for example, 400 ° C.) to vaporize the mixture. The mixed steam obtained by the mixed steam generator 6 is further heated to a higher temperature (for example, 650 ° C.).
A superheated steam generator 7 that heats the superheated steam into superheated steam, and the superheated steam obtained by the superheated steam generator 7 is kept in that state for a predetermined period of time to decompose the substance (for example,
A reactor 8 for hydrolyzing CFCs X);
Cooling device 9 for cooling and liquefying product gas G (for example, a mixture of superheated steam, carbon dioxide gas CO ₂ , hydrogen fluoride HF, and hydrogen chloride HCl) obtained by the above, and a solution obtained by cooling by cooling device 9 Separating gas and liquid from L (ie,
Gas-liquid separation device 10 for separating carbon dioxide gas CO ₂ , hydrogen fluoride HF and hydrogen chloride HCl from a solution of hydrofluoric acid and hydrochloric acid)
And a removing device 11 for neutralizing and removing gases (that is, carbon dioxide gas CO ₂ , hydrogen fluoride HF, and hydrogen chloride HCl) from the gas-liquid separation device 10 by showering with an alkaline aqueous solution. Reference numerals 12, 13, and 14 denote heaters for heating.

Thus, the cooling device 9 comprises a first cooling means 9A for primary cooling the produced gas G supplied from the reaction device 8 to a predetermined temperature (for example, 180 ° C.) for maintaining the gaseous state; And a second cooling means 9B for cooling and liquefying the product gas G which has been primarily cooled by the first cooling means 9A.

The first cooling means 9A includes a cylindrical body 15 and a plurality of heat transfer tubes 1 arranged in parallel in the body 15.
, And an inlet chamber 17 for distributing the generated gas G supplied from the reactor 8 to the heat transfer tubes 16, 16, at both ends in the body 15. An outlet chamber 18 for collecting the cooled product gas G from the heat transfer tubes 16 is formed (see FIG. 2).

A fan 19 is provided in the body 15.
And heated by the heating means 20 to a predetermined temperature (for example, 150 ° C.), and air (in other words, hot air) A acting as a refrigerant is supplied. By exchanging heat with the generated gas G (for example, a high temperature of 650 ° C.) flowing through the heat transfer tubes 16, 16,..., The generated gas G reaches a predetermined temperature (for example, 180 ° C.) at which the generated gas G maintains a gas state. It is to be cooled down.

The heating means 20 comprises an electric heater or the like, and is supplied with hot air A supplied by a control means (not shown).
Is detected by the temperature sensor 21, and the amount of electricity is controlled so that the temperature of the hot air A becomes 150 ° C. In this way, as shown in the time chart of FIG. 3, the temperature of the generated gas G is 650 ° C. in the inlet chamber 17 (that is, time T ₁ ) of the first cooling means 9A, but the first gas is changed to the first temperature. In the outlet chamber 18 (that is, time T ₂ ) of the cooling means 9A, the gas is cooled to 180 ° C. while maintaining the gas state. That is, by controlling the temperature of the warm air A, which is the refrigerant, the generated gas G is not cooled until it is liquefied. The hot air A supplied into the body 15 is heated by heat exchange with the generated gas G to become high temperature, and is discharged from the discharge pipe 22 into the air.

As described above, in the first cooling means 9A, the generated gas G flowing through the heat transfer tubes 16, 16,...
Is kept in a gaseous state, so that the corrosiveness is extremely low. Therefore, the heat transfer tubes 16, 16,.
In the selection of the material, if the material can withstand high temperature (for example, 650 ° C.), it is not necessary to consider much about the corrosiveness. That is, a relatively low-cost material such as stainless steel can be selected as the material of the heat transfer tubes 16. It is desirable to use a ceramic heat transfer tube in consideration of corrosion resistance.

On the other hand, the second cooling means 9B is provided with a synthetic resin material (for example, Teflon or the like) having a high corrosion resistance while allowing the generated gas G supplied from the outlet chamber 18 of the body 15 of the first cooling means 9A to flow therethrough. ), And a refrigerant (for example,
(See FIG. 2), and heat is exchanged between the water and a generated gas G (for example, 180 ° C.) flowing through the heat transfer tube 23 to generate a gas. The gas G is cooled to room temperature (for example, 20 ° C.) and liquefied. In this cooling process, hydrogen fluoride HF and hydrogen chloride H
Although the Cl is dissolved in the liquefied water to form a strongly acidic aqueous solution L, it flows through the heat transfer tube 23 made of a synthetic resin having excellent corrosion resistance, so there is no possibility of corrosion. Moreover, the temperatures of the generated gas G and the strongly acidic aqueous solution L flowing through the second cooling means 9B are not so high (that is, 20 ° C to 1 ° C).
80 ° C.), so that the heat transfer tube 23 made of synthetic resin can withstand sufficiently.

As described above, in the present embodiment, the product gas G is cooled to a predetermined temperature (for example, 180 ° C.) by the first cooling means 9A in a gas state that does not show high corrosiveness, and then the second gas is cooled to the second temperature. The produced gas G can be cooled and liquefied by the cooling means 9B of the first cooling means 9B.
A having a configuration in which only heat resistance is considered without consideration of corrosiveness (for example, one having heat transfer tubes 16, 16,... Made of stainless steel, ceramic, or the like) can be used, and the second cooling means 9B A material having excellent corrosion resistance (for example, having a heat transfer tube 23 made of a synthetic resin such as Teflon) can be used without considering heat resistance. Therefore, it greatly contributes to the cost reduction of the heating steam decomposition apparatus.

Second Embodiment FIG. 4 shows a cooling device in a superheated steam cracking device according to a second embodiment of the present invention.

In this case, oil O is employed as a refrigerant in the first cooling means 9A. Accordingly, an oil tank 25 for storing the oil O, a pump 26 in place of the fan 19, and a return oil pipe 2 in place of the discharge pipe 22
7. A cooler 28 for cooling the return oil O and a pump 29 for returning the oil are provided. in this case,
Since the oil O whose temperature can be easily controlled is used as the refrigerant, the cooling efficiency of the first cooling unit 9A is improved. The other configuration and operation and effect are the same as those in the first embodiment, and the description is omitted.

In the above embodiment, the case of decomposing CFCs has been described. However, the superheated steam decomposition apparatus of the present invention is applicable to the case of decomposing other hardly decomposable substances (for example, trichloroethane, chlorobenzene, etc.). is there.

[0024]

According to the present invention, there is provided a superheated steam decomposer comprising a reactor for decomposing a hardly decomposable substance by superheated steam, and a cooling device provided downstream of the reactor. First cooling means for primary cooling the product gas supplied from the reactor to a predetermined temperature for maintaining a gas state, and second cooling for cooling and liquefying the product gas primary cooled by the first cooling means By means of
After the produced gas is cooled to a predetermined temperature in a gas state that does not show high corrosiveness by the first cooling means, the produced gas can be cooled and liquefied by the second cooling means. As a means, a structure having only the heat resistance without considering the corrosiveness can be used, and as the second cooling means, a structure with excellent corrosion resistance can be used without much consideration of the heat resistance. An excellent effect that superheated steam decomposition of a hardly decomposable substance can be easily performed with a low-cost device can be obtained.

[Brief description of the drawings]

FIG. 1 is a system diagram showing a schematic configuration of a superheated steam cracking apparatus according to a first embodiment of the present invention.

FIG. 2 is a system diagram showing a configuration of a cooling device in the superheated steam cracking device according to the first embodiment of the present invention.

FIG. 3 is a time chart showing a temperature change of a product gas passing through a cooling device in the superheated steam cracking device according to the first embodiment of the present invention.

FIG. 4 is a system diagram showing a configuration of a cooling device in a superheated steam cracking device according to a second embodiment of the present invention.

[Explanation of symbols]

8 is a reaction device, 9 is a cooling device, 9A is a first cooling means,
9B is a second cooling means, 16 is a heat transfer tube, 15 is a body, 2
3 is a heat transfer tube, 24 is a container, X is a hardly decomposable substance (fluorocarbon),
W is a solvent (water).

Claims (3)

[Claims] 1. A superheated steam decomposer comprising a reactor for decomposing a hardly decomposable substance by superheated steam and a cooling device provided downstream of the reactor, wherein the cooling device is supplied from the reactor. A first cooling means for primary cooling the produced gas to a predetermined temperature which maintains a gas state, and a second cooling means for cooling and liquefying the produced gas primarily cooled by the first cooling means. A superheated steam cracker characterized by the following. 2. The first cooling means is provided with a heat transfer tube made of a material having excellent heat resistance as well as a flow of a product gas supplied from the reactor, and a refrigerant flowing on the outer peripheral side of the heat transfer tube. The superheated steam cracking apparatus according to claim 1, wherein the superheated steam cracking apparatus is constituted by: 3. The heat transfer pipe made of a synthetic resin material having excellent corrosion resistance while allowing the generated gas supplied from the first cooling means to flow, and a second cooling means provided on an outer peripheral side of the heat transfer pipe. The superheated steam cracking device according to any one of claims 1 and 2, further comprising a container through which the refrigerant flows.