CZ326692A3 - Process and apparatus for destruction of chlorinated hydrocarbons in solid waste - Google Patents

Abstract

Process for destruction of chlorinated hydrocarbons in solid waste in the presence of oxides or carbonates of metals of alkaline soils. The solid waste with chlorinated hydrocarbons is added at up to 35 % by weight to a mixture containing fuel and 3 to 20 % by weight calcium oxide or calcium carbonate, all related to the fuel content, and it is left to react at 800 to 1000 degrees C under the conditions of fluidised combustion. The apparatus includes a fluidised reactor (1) connected by the outlet neck (2) with the combustion chamber (4), where, in the upper part of the fluidised reactor (1), there is a chute (9) for feeding solid waste with opening plumb to the bottom of the fluidised reactor (1) under the level of the output neck (2).<IMAGE>

Description

METHOD AND EQUIPMENT FOR THE DESTRUCTION OF CHLORINE HYDROCARBONS IN SOLID WASTE

Technical field

1,

The present invention relates to a process for the destruction of chlorinated hydrocarbons in wastes in the presence of oxides or carbonates of alkaline metal apparatuses for carrying out the process comprising a fluidized bed reactor with a combustion chamber outlet.

solid earth and bonded

BACKGROUND OF THE INVENTION

Contamination of soils, sediments, sands and other non-combustible inorganic materials with toxic chlorinated substances such as pesticides and their partial decomposition products, polychlorinated biphenyls, dioxins, chlorinated phenols and the like presents a serious environmental problem. A number of methods have been proposed to destroy these substances in said materials, including;

incinerator combustion (Mindler A.B .: Innovation Hazard. Waste Treat ..

Technol. Ser. 1990,1 Therm. Processes, 147) and high-temperature flow-wall reactors (called HTFW reactors, Rockwell Int. Report 1984, EPA600 / D-84-072), low-temperature oxidation (Piersal P .: Report 1989, CPSvc.

EPS3 / HA / 5) is biodegraded (Tassinato G., De Philippis R.: D.A., Dif.

AmbientaLe 14,44 (1990)). The destruction of polychlorinated biphenyls in soils can be accomplished by treatment with certain chemical agents such as mixtures of potassium hydroxide and polyethylene glycol (the KPEG process, Kornel A. et al., EPA Report 1989, EPA 600-9). (89/072) with a mixture of this hydroxide and non-dimethylsulfoxide (U.S. Pat. No. 4,447,541 1984) at ambient temperature / at slightly elevated temperatures. In addition to these processes, which result in the conversion of chlorinated hydrocarbons to non-toxic products, some physical methods have been proposed for the decontamination of solid wastes of this type, based on the thermal separation of volatile chlorinated hydrocarbons from waste in special separators (Fox RD et al. (Environ. Progr. 10 (1), 40 (1991)) or their extraction, secondary and tertiary amines are known to be effective as extraction agents (BEST process, EPA Report 1989,

EPA / 9200.5-253), a mixture of water and an immiscible organic solvent, e.g.

Wzbtf kerosine, gasoline (US Pat. Appl. 672,230 (1986)), surfactant-added water (e.g., Ellis W. D. et al., Hazard. Metr. Spills).

Conf. Why., Prev. Beh., Control Cleanup Waste Sites 1984, 1116).

Recently, the method of destruction of polychlorinated biphenyls in soils by means of calcium oxide has been considered as very promising. This, according to some data (New Scientist 129, 27 (19.91)), proceeds easily at normal temperatures when the conclusions were not fully confirmed by Technol. 25 (11), 1936, however.

known to their disintegration of both materials; further investigations of these (Sedlák O.L. et al: Environ. S.ci (1991)). The action of calcium oxide by the pyrolysis of chlorinated hydrocarbons contributes to and, at the same time, high efficiency, captures the formation of hydrogen chloride produced by pyrolysis. calcium chloride formation (Nukem GmbH: OE 3 517019, DE 3 028 193, DE 3 9 187 16, E.P 0401810; Asea Brown Boveri AG: DE 3 828633, DE 3 728870 et al: DE 3 443722). This procedure

Λ destruction of PCB fluids and recently protected even for the removal of PCBs from waste gases. (Plasma Product l ... td: PCT Int.Appl. WO 9108041 (1991)).

A common feature is to perform decomposition in the absence of air in an inert atmosphere, i.e., under pyro

DE 3,739171; Ma.ngo.1 K, has so far been utilized for the fixed bed of CaO.

However, only PCBs contained in combustible liquids or gases which can be pyrolytically decomposed can be treated in this way. Maintaining pyrolytic conditions is necessary to avoid direct oxidation of PCBs that cause the formation of toxic chlorinated products. Since the bed of calcium oxide in the mixture with the resulting calcium chloride as a reaction product tends to crust, it is necessary.

to take further measures, i. addition of inert substances such as _Ύ ck. . ,, _.

železxty,. respx slag, etc. Reaction for sand, rubber oxide at around

500 [0C] and, of course, requires special equipment - a special reactor p. rril n e e. n ý m ρ 1 tě tě n rn.

The above methods and apparatuses are relatively proportional

PCBs are costly and are virtually unusable for in solid waste such as soils and the like. obÚC.

The present invention.

These drawbacks are overcome by a process for destroying chlorinated hydrocarbons contained in solid wastes / according to the presence of metal oxides or carbonates. wherein the essence of the process is that the mixture containing fuel and the calcium to calcium carbonate and / or calcium carbonate are mixed. bring ¹ . Y solid waste, with chlorinated hydrocarbons in an amount of up to 35 µm wt / wt, based on the fuel content, and allowed to react at a temperature of 800 to 80 ° C. ie 100 ° C under fluidized bed combustion conditions.

The mixture of fuel and calcium oxide alone contains 3 to 10% calcium oxide and the mixture of fuel and carbonate alone in the calcium Dt & The calcium carbonate, based on the weight of the fuel, may furthermore preferably contain from 0.1 to 10% by weight of calcium carbonate. 15%

And w / w of glass based on the weight of the mixture.

The conditions of fluidized bed combustion and the temperature at which the reaction proceeds allow. immediate contact of the reactants and an immediate increase in the temperature of the solid waste feed. This avoids the formation of undesirable volatile chlorinated toxic products. The essence of the apparatus comprising a fluidized bed reactor connected to the combustion chamber by an outlet orifice is that a solid waste outlet is provided at the top of the fluidized bed with a discharge perpendicular to the bottom of the fluidized bed. output throat level. Over. The feeder can advantageously be loaded with a dispenser with a container. An advantage of the device according to the invention is that a conventional fluidized bed reactor with a combustion chamber is used which is adapted to carry out the process according to the invention under the conditions mentioned above. An important condition for immediate contact, reactants and an immediate increase in the temperature of the solid waste being fed is accomplished by treating the downcomer, which opens into the interior of the fluidized bed. Thus, unlike the reactor described in the prior art, waste is not fed to the surface of a bed of calcium oxide surrounded by an inert atmosphere, but dispersed into fluidized bed sites with a relatively constant, high, temperature where in the presence. In the case of destruction of PCB, the reaction of chlorine and / or hydrogen chloride is preferred.

-HX

with calcium oxide prior to the undesired reaction of bromide and calcium chloride, and calcium chloride. K are. To ensure high process efficiency, destruction is carried out with an above-stoichiometric amount of base

- calcium oxide, calcium carbonate or mixtures thereof

- based on the organically bound chlorine content of solid waste. That this surplus is a good choice in the fiS ’range

10 times the stoichiometric amount, preferably 3X7

1.5 times. At the same time, it must be ensured that the total amount of base is sufficient to remove the oxide formed by the fluidized-bed combustion of the spent fuel; especially sulfur dioxide.

f 1 u, i d η í m s a a a v v v v v v v v v v v

In f, Shot #. 100OPC- said weight ratio of removal of organically bound chlorine

W o rk ing with e n e. temperatures up to 800 to guarantee efficiency from contaminated material. 99,999J &. In the case of destruction of polychlorinated biphenyls, it has been shown that no PC8 metabolites such as polychlorinated dibenzodioxins or furans are formed in the process. Further, it has been found that, unlike known pyrolysis processes, the off-gas does not contain methane or methane. lower unsaturated hydrocarbons.

Process efficiency can be enabled. In addition, it is possible to further increase the release of vases and t released by the addition of the substances c h 1 o r o o o o.

Particularly suitable is the addition of a rigid waterglass to the weight of the oxide, i.e. in the amount of 0.1 to 15% by weight of calcium carbonate, preferably

The process according to the invention can advantageously be used for the destruction of organic chlorinated substances in solid, partially combustible and non-combustible wastes. In the case of partially combustible waste it shall:. The process has the advantage that decontamination occurs while utilizing the thermal potential of the waste so that ecologically harmful waste can become a secondary fuel energy source. In addition, the process enables simple disposal of chlorinated substances from solid waste, which becomes part of the effluent, solid residues, incineration. high process efficiency, even flue gases do not require special treatment (such as washing) before. their release into the atmosphere.

-S 'χ

Overview of the drawings

One possible arrangement of the apparatus for carrying out the method according to the invention

The invention is explained in more detail by means of a drawing showing schematically a cross-section through the device.

DETAILED DESCRIPTION OF THE INVENTION

The fluidized bed reactor 7 is connected by a feeder 5 to a solid fuel reservoir 6 with the addition of an additive, i. In its lower part there is an air chamber 7 with a concave grate, an outlet 8 and a closure 12. The fluidized bed reactor χ is further connected to the combustion chamber 4 via the outlet neck 2 into which the nozzles 3 of the secondary air exit. In the upper part of the fluidized bed reactor 9, a downcomer 9 is provided with a feeder 10 and a reservoir XX. The output of the dispenser is adjustable in the range of 0 to 100%. rated power. The header 9 extends below the lower edge of the outlet orifice 2 vertically perpendicular to the bottom of the air chamber 7 of the fluidized bed reactor and perpendicular to the surface of the fluidized bed 15 formed in the fluidized bed reactor χ. The upper part of the combustion chamber 4 leads to the exhaust of gaseous flue gases 14. At the lower part of the combustion chamber 4 there is a hopper 13 for gravitational separation of particles from the fluidized bed reactor χ.

The destruction of chlorinated hydrocarbons in solid wastes takes place only after stabilization of the fuel combustion in the entire combustion chamber. The solid waste is started to be fed to the fluidized bed 15 in the fluidized bed reactor 11 via a lead 9 and a dispenser 10 from the reservoir 11. The calcium oxide or calcium carbonate is fed to the fluidized bed reactor X together with the fuel. Solid combustion residues are discharged from the fluidized bed 15 as needed by the closure 12 and from the combustion chamber 4 through a hopper 13.

The method according to the invention is demonstrated in the following examples using reference to the above-described apparatus used for its application.

Example 1

7; · V

The fluidized bed reactor was commissioned in a known manner. Brown fuel was used as a fuel and 10 was added as a / bititive

3% by weight of the weight of the limestone Ladc.e (CaO content in the dry matter 49.04).

, MgO 0,6lj%,

CO ₂ 36.8 µm of a grain size of 67.2CJZ. below 0.06 mm and 32.3 ° C from 0.06 mm to 0.2 mm.

After stabilization of combustion in the whole combustion chamber and 1S /

850) c900rc in the fluidized bed / was fed contaminated material to the surface of the fluidized bed, which was blasting sand containing 839 mg of organically rare chlorine per kg waste, of which 40% Cl was in the form of polychlorinated biphenyls (Delor 106). The content of inorganically bound chlorine (Cl ions) in the starting material was 24 mg / kg.

Additive fuel was fed at a rate of 248 kg / hr and contaminated waste at a rate of 65 kg / hr.

The product of this process was solid waste in which the presence of organic substances containing chlorine in its molecule was not detected (the sensitivity limit of the method to PCB was 0.1 ppm). Flue gas (a = 1.82) at 0 = contained (a = 1.4) 37 mg CO / m ³ , 329 mg NO (expressed as

NO) / m, 232 mg SO / m, 8 mg HCl / m ³ , 18 mg / m ³ particulate matter and ^{2 n} 3 ^{2 n} less than 10 mg / m of organo-compounds (expressed in total carbon). The presence of n

polychlorinated biphenyls and their metabolites (dioxins and dibenzofurans) were not detected in the flue gas (detection limit of analysis was 0.1 ppm PCB and 0.2 ppb for PCDD).

Example 2.

Example 1 was repeated with the difference that instead of calcium carbonate has been used as an additive calcium oxide in slaked lime ^.for: t € ementárnynčía in an amount of 3 lim. 4 / ha fuel weight. The feed rate of the fuel-additive mixture was 198 kg / hr and PCB - contaminated blasting sand 22.5 kg / h @ -1. The analysis showed that the destruction efficiency of chlorinated organic compounds was 99.999. The flue gas contained mg CO / m ³ , 210 mg NO / m ³ , 215 mg SO / m ³ , 2 mg HCl / m ³ , 10 mg / m ³ solid nx 2 η η n pollutants. The presence of PCBs and PCDDs has not been established.

Example 3

Example 1 was repeated except that a 9: 1 mixture of calcium carbonate and a rigid water glass was used in place of calcium carbonate as an additive. This mixture was added to the fuel to be 7 wt%. percent by weight of fuel, magnifying glass as in-example

PCB 99, -9-999% Solid or gaseous flue gas did not contain PCB | f-tf PCDDs within the sensitivity limits of analytical methods (0.1 ppm PCB and 0.1 ppb PCDD). The levels of carbon monoxide (28 mg / m), nitrogen oxide (146 mg / m), sulfur dioxide (220 mg / m), hydrogen chloride (3 mg / m) and particulate matter (15 mg / m) were lower than the emission limits for incineration of special waste given by the relevant decree (Provisions of the FVŽP to Act 309/1991).

Industrial applicability

The process and apparatus for destroying the chlorinated hydrocarbons according to the invention can advantageously be used for the disposal of solid-polluted and non-combustible bulk materials contaminated by these substances. This method is particularly useful in the disposal of sands used for shot blasting of chlorinated rubber coatings or paints containing polychlorinated biphenyls. Similarly, it can be used to remove chlorinated substances from sediments and soils, after drying and possibly adjusting the particle size. The process effectively removes a wide variety of chlorinated hydrocarbons, including polychlorinated biphenyls, dioxins, chlorinated phenols, and chlorinated polymers such as chloroprene, PVC. These substances can form both a mechanical admixture of said bulk materials and can be adsorbed on their surface.

Claims (2)

1 - Method of destruction. chlorinated 15 t in solid wastes in the presence of oxides or carbonates, metals l. And μ $ Jt ,, the S c is -RT tpjm ý, / Ot "^'JL 2d% w / carbonate, calcium hydroxide is fed with solid waste chlorinated hydrocarbons characterized efjf y in an amount up to 39x w ^ r * / Se weight to the fuel content, and allowed to react at 800 to 100 ° C under fluidized bed combustion conditions. alkaline earth containing fuel and from 3 to 10 2e into calcium oxide and / or o - * 7 LX 1 <C I HER 5. The method of claim 1, wherein the method is as follows. y of fuel and calcium oxide alone contains 3 to 5%. 1012 grind, oxide, calcium and a mixture of fuel and calcium carbonate alone contains 5 to S < L, said mixture of fuel and carbonate itself &lt; t &gt; Y 2 wt% calcium carbonate ,; based on fuel weight. The method of claims 1 and 2 of fuel and oxide 1 ζ <L Ή ^ m, ^sm ^ ^s I C. it further comprises the weight of the mixture. 0.1 It is characterized by calcium and / or calcium carbonate n r in wt. O Device for carrying out the method according to claim 1. 1 and 3 comprising a fluidized bed reactor connected by an outlet orifice to a combustion μ. ^{In the} upper part of the fluidized bed in the reactor. (1) there is a downcomer (9) for the supply of solid waste, with a discharge perpendicular to the level of the outlet throat (2). bottom of fluidized bed reactor (1) under Equipment. k, carried out by means of n-e-n-e wherein the dispenser (10) with the method reservoir (11) of the above claim (9) is inserted