JP3486702B2 - Detoxification method of CFC - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detoxifying CFCs.
It is about the law. [0002] 2. Description of the Related Art Freon 11 (CCl)_ThreeF) and Freon 12
(CCl_TwoF_TwoFluorocarbon containing chlorine atom in the molecule
Is regulated worldwide because it decomposes the ozone layer.
By the end of 995, the production of such chlorofluorocarbons worldwide
It is internationally promised to stop birth. And I
The country has been producing the above-mentioned pollutant CFCs since July 1989.
And consumption is regulated. Also, pollutant CFCs in stock
Is required to make this harmless. Freon's
A method of decomposing CFCs in a flame as a detoxification method
It has been known. In this method, Freon stays in the flame
A mixture of chlorofluorocarbons, fuel and air
It is a method of burning [Kondo, Tokuhashi; Disaster research23
  156 (1992)]. In the above-mentioned method of decomposing chlorofluorocarbon in a flame, chlorofluorocarbon is not used.
Hydrogen fluoride is generated by decomposition, and this hydrogen fluoride
Is extremely flammable and metal corrosive,
Strong corrosion resistance is required for furnace and piping materials. Only
However, materials that have corrosion resistance to hydrogen fluoride are very
Is limited, and this is the
It is a factor that makes industrialization difficult. Also like this
Combustion furnace made of various corrosion-resistant materials to decompose CFCs
If you try to do so, the cost of treating CFCs will increase significantly
There is also a problem. [0004] DISCLOSURE OF THE INVENTION The present invention reduces the use of CFCs.
It is an object to provide a method for detoxifying the value. [0005] Means for Solving the Problems The present inventors have solved the above problems.
As a result of intensive research to solve the problem, the present invention is completed
Reached. That is, according to the present invention, combustible waste is
Combustion of combustible waste including the process of burning in a combustion furnace
In the treatment method, CFCs are introduced into the furnace and burned.
Treatment and hydrogen fluoride concentration of 2000mg / N
m^ThreeThe following combustion furnace exhaust gas is generated, and this exhaust gas is
Remove hydrogen fluoride from exhaust gas by contact with potash water
A method for detoxifying CFCs is provided. The detoxification treatment of CFCs of the present invention is based on existing waste.
It is carried out using a waste combustion treatment device. Conventionally, city Go
While continuously supplying combustible waste such as
Baking is widely practiced. The present inventors have
Chlorofluorocarbons or hydrocarbons
Supplied continuously or intermittently at a low flow rate in the form of a mixture with
When decomposing or burning, hydrogen fluoride in the combustion furnace
Since the gas concentration is maintained at a low level, the furnace wall and exhaust
The pipe wall through which the gas flows is hardly damaged,
Walls and pipe walls do not need to be made of special corrosion resistant materials.
And found. Next, the present invention will be described with reference to the drawings. FIG.
Is an example of a system diagram for use in carrying out the method of the present invention.
Is shown. In FIG. 1, 1 is a mixer and 2 is a rotary key.
Run-type primary combustion furnace, 3 is a rigid secondary combustion furnace, 4 is waste heat
Reference numeral 5 denotes a cooling tower, and reference numeral 6 denotes a dust removal tower. [0008] Fluorocarbon gas and hydrocarbon are each in line
11 and into the mixer 1 through line 12, where
After mixing in the rotary kiln type primary combustion furnace 2
be introduced. In addition, the flammable
Solid waste is introduced through line 14 and
The same waste oil is introduced through line 15 and
(Air) is introduced through line 16. The primary fuel
Solid in furnace 2 and secondary combustion furnace 3 connected to it
Combustion of waste and waste oil is performed. Combustion temperature in this case
Is 800 to 1000 ° C. In addition, primary combustion furnace 2
And the secondary combustion furnace 3, the combustion of the waste
In addition, the decomposition or combustion of CFCs is also performed. For example, charcoal
Hydrogen is CH_FourAnd CFC is CCl_TwoF_TwoFuel when
The firing reaction is represented by the following reaction formula.         2CCl_TwoF_Two+ 3CH_Four+ 6O_Two → 5CO_Two+ 4HF + 4HCl + 2H_TwoO (1) The combustion furnace exhaust gas passes through a line 17 and is
It is extracted from the combustion furnace 3 and introduced into the waste heat boiler 4,
Here, indirect heat exchange with water introduced from line 19 is performed.
Is replaced. This heat exchange turns the water into steam,
Is pulled out through the housing 20. On the other hand, combustion furnace exhaust gas
The cooled exhaust gas is cooled by the heat exchange of
5 is introduced. From the bottom of the secondary combustion furnace 3, incineration ash
It is withdrawn through line 31. In the cooling tower 5, the cooling
Water is sprayed from spray device 22 into fine droplets
The exhaust gas contacts fine droplet particles of this cooling water.
Touch to cool further. Cooling wastewater is supplied to line 32 and
The waste liquid is introduced into the waste liquid pit 35 through the waste liquid pit 35. Line 21
As the cooling water from pH 7 to 9, preferably 7 to 8
Water or alkaline water is used. Alkali in this case
Water is based on sodium hydroxide or calcium hydroxide
Can be obtained by adding an alkaline substance such as
it can. The exhaust gas after contact with the cooling water is supplied to line 2
3 and is introduced into the dust removal tower 6. Dust tower 6
, The dust removing liquid L passes through the pump 29 and the line 27.
From the dust removal tower 6, passing through the line 24 and spraying
Sprayed into fine droplets of dust from the device 25
The dust in the exhaust gas is trapped by the fine droplets of this dust removal liquid.
Caught and removed from exhaust gas. Is dust removal liquid on line 28?
And a part of the dust removal liquid is supplied to the line 33 and the line 3
4 and is introduced into the waste liquid pit 35. Dust removal liquid L
PH 8 to 10, preferably 8 to 9 alkaline water
Used. This alkaline water contains sodium hydroxide or water
Adding alkaline substances such as calcium oxide to water
Can be obtained by In the dust removal tower 6,
HF and HCl contained in gas are alkaline dust
Reacts with liquid and is removed from exhaust gas. Reaction in this case
Is represented, for example, by the following equation.         HF + NaOH → NaF + 1 / 2H_TwoO (2)         HCl + NaOH → NaCl + 1 / 2H_TwoO (3) Exhaust gas from which dust has been removed in the dust removal tower 6
If necessary, further through a dust collector such as an electric dust collector
And released into the atmosphere. In the present invention, the flow supplied to the combustion furnace is
The amount of HF contained in the flue gas of the combustion furnace was 20%.
00mg / Nm^ThreeOr less, preferably 1000 mg / Nm^Three
Set as follows. The supply amount of CFC is within the above range
If it exceeds, the problem of furnace material corrosion and exhaust gas flow
The problem of corrosion of the inner wall material of piping and equipment passing through
Is not preferred. Conversely, the supply amount within the above range
Is supplied to the combustion furnace when the combustion furnace, piping, etc.
Detoxification of CFCs without causing corrosion problems
I can. The flow used as the raw material to be treated in the present invention
CFC 11, CFC 12, CFC 13 (C
ClF_Three), Freon 113 (CCl_TwoF-CCIF_Two),
Freon 114 (CCIF_Two-CCIF_Two), Freon 115
(CCIF_Two-CF_Three) Etc., and at least
Are also halogenated hydrocarbons containing one fluorine atom
If so, detoxification treatment can be performed according to the present invention. Departure
CFCs may be used as is or mixed with hydrocarbons
The fuel is supplied to the combustion furnace in the form of a substance,
Can be used arbitrarily, regardless of whether it is gaseous or liquid at room temperature.
For example, methane, ethane, propa
Gas oil, kerosene, etc., in addition to lower hydrocarbons such as
Can be The proportion of hydrocarbon used is 1 mole equivalent of chlorofluorocarbon.
L, at least 1 mol, preferably about 1.5 to 3 mol
It is. [0015] Next, the present invention will be described in more detail with reference to examples.
I do. Embodiment According to the apparatus system diagram shown in FIG._TwoF_Two)
Detoxified. The main operating conditions in this case are shown in relation to FIG.
It is shown below in the series. (1) Line 11 Freon supply: 20 kg / hr (2) Line 12 Hydrocarbon (methane) supply: 7.5 Nm^Three/ Hr (3) Line 14 Combustible waste supply: 900 kg / hr (4) Line 15 Waste oil supply: 226 kg / hr As waste oil, thinner or organic solvent waste oil is used.
Was. (5) Primary combustion furnace 2 Combustion temperature: about 850 ° C (6) Secondary combustion furnace 3 Combustion temperature: about 900 ° C (7) Line 17 (I) Combustion furnace exhaust gas composition CO_Two: 3.7 vol% O_Two: 10.2vol% N_Two: 59.0 vol% H_TwoO: 27.0 vol% HF: 730 mg / Nm^Three HCl: 1240 mg / Nm^Three (Ii) Temperature: about 900 ° C (8) Line 18 Exhaust gas temperature: about 250 ° C (9) Line 21 (I) Cooling water: 1 wt% or less of sodium hydroxide
Liquid, pH: 7, temperature: 70 ° C (Ii) Supply amount of cooling water: 70000 kg / hr (10) Line 23 (I) HF concentration in exhaust gas: 15 mg / Nm^Three (Ii) HCl concentration in exhaust gas: 35 mg / Nm^Three (11) Line 28 (I) Dust remover: 24 wt% aqueous solution of sodium hydroxide,
pH: 9-10, temperature: 60 ° C (Ii) Supply amount of dust removing liquid: 55 kg / hr (12) Line 26 (I) HF concentration in exhaust gas: 0.1 mg / Nm^ThreeLess than (Ii) HCl concentration in exhaust gas: 4.6 mg / Nm^Three (Iii) Exhaust gas temperature: about 60 ° C [0017] According to the present invention, existing waste combustion treatment is performed.
By using the equipment, CFCs can be replaced by special equipment corrosion etc.
Detoxification process can be easily performed without causing problems.
Wear.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an example of a system diagram for use in carrying out the method of the present invention. [Description of Signs] 1 Mixer 2 Primary combustion furnace 3 Secondary combustion furnace 4 Waste heat boiler 5 Cooling tower 6 Dust tower 35 Waste pit

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-7-88457 (JP, A) JP-A 8-959 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B01D 53/34 A62D 3/00

Claims (1)

(57) [Claim 1] In a method for combustible combustible waste including a step of combusting combustible waste in a combustion furnace, fluorocarbon is introduced into the combustion furnace to perform combustion treatment. A method for detoxifying CFCs, further comprising generating combustion furnace exhaust gas having a hydrogen fluoride concentration of 2000 mg / Nm ³ or less, and contacting the exhaust gas with alkaline water to remove hydrogen fluoride from the exhaust gas.