Classifications

• • A—HUMAN NECESSITIES
  • A62—LIFE-SAVING; FIRE-FIGHTING
  • A62D—CHEMICAL MEANS FOR EXTINGUISHING FIRES OR FOR COMBATING OR PROTECTING AGAINST HARMFUL CHEMICAL AGENTS; CHEMICAL MATERIALS FOR USE IN BREATHING APPARATUS
  • A62D3/00—Processes for making harmful chemical substances harmless or less harmful, by effecting a chemical change in the substances
  • A62D3/30—Processes for making harmful chemical substances harmless or less harmful, by effecting a chemical change in the substances by reacting with chemical agents
  • A62D3/38—Processes for making harmful chemical substances harmless or less harmful, by effecting a chemical change in the substances by reacting with chemical agents by oxidation; by combustion
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B7/00—Halogens; Halogen acids
  • C01B7/01—Chlorine; Hydrogen chloride
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
  • F23G7/00—Incinerators or other apparatus for consuming industrial waste, e.g. chemicals
• • A—HUMAN NECESSITIES
  • A62—LIFE-SAVING; FIRE-FIGHTING
  • A62D—CHEMICAL MEANS FOR EXTINGUISHING FIRES OR FOR COMBATING OR PROTECTING AGAINST HARMFUL CHEMICAL AGENTS; CHEMICAL MATERIALS FOR USE IN BREATHING APPARATUS
  • A62D2101/00—Harmful chemical substances made harmless, or less harmful, by effecting chemical change
  • A62D2101/20—Organic substances
  • A62D2101/22—Organic substances containing halogen
• • A—HUMAN NECESSITIES
  • A62—LIFE-SAVING; FIRE-FIGHTING
  • A62D—CHEMICAL MEANS FOR EXTINGUISHING FIRES OR FOR COMBATING OR PROTECTING AGAINST HARMFUL CHEMICAL AGENTS; CHEMICAL MATERIALS FOR USE IN BREATHING APPARATUS
  • A62D2203/00—Aspects of processes for making harmful chemical substances harmless, or less harmful, by effecting chemical change in the substances
  • A62D2203/10—Apparatus specially adapted for treating harmful chemical agents; Details thereof
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN  A CARRIER GAS OR AIR 
  • F23C2900/00—Special features of, or arrangements for combustion apparatus using fluid fuels or solid fuels suspended in air; Combustion processes therefor
  • F23C2900/9901—Combustion process using hydrogen, hydrogen peroxide water or brown gas as fuel

Definitions

• This invention relates to the elimination of environmentally harmful products of manufacturing processes.
• it relates to processes for the disposal of organic materials such as heavy halogenated wastes.
• HHW heavy halogenated wastes
• Typical aromatic and polyaromatic heavy halogenated wastes include such compounds as hexachlorobenzene (HCB) , poly- chlorinated biphenyls (PCB's) and octachlorostyrene (OCS) .
• HBC hexachlorobenzene
• PCB's poly- chlorinated biphenyls
• OCS octachlorostyrene
• HCE perchloroethylene
• HCBD hexachlorobutadiene
• Incineration has been widely used for the destruction of domestic and industrial waste but these heavy halogenated wastes are not readily handled by this means.
• the combustion of such wastes is incomplete and harmful amounts can escape into the atmosphere or into soil and water. Furthermore some of the reaction products formed in this partial combustion are also harmful.
• the carrier gas comprising hydrogen performs three important functions. First, the carrier gas carries the heavy .halogenated wastes (HHW) to the burning means. Se- condly, the hydrogen ensures a high temperature in the hydrogen/oxygen flame for complete destruction of the HHW. Thirdly, the hydrogen converts the halogen into hydrogen halide.
• HHW heavy .halogenated wastes
• the preferred carrier gas is hydrogen itself, but other compositions comprising at least 80% v/v of hydrogen may be used. Suitable compositions, for example, are some of the hydrogen-rich hydrocarbon streams found in oil refineries.
• Some of the heavy halogenated wastes referred to hereinbefore have a relatively low vapour pressure at ambient temperatures and may in fact be solid. Such materials are heated to a temperature at which a adequate amount of vapour will be continuously removed by the flow of carrier gas. The temperature is controlled so that the amount of HHW vapour is not excessive since this _ - —
• a first stream of carrier gas is passed over the heated chlorinated hydrocarbons, and this is diluted with a second stream of carrier gas before passing the mixture of gases into the flame.
• the second stream of carrier gas is pre-heated, typically by passage through a tube in or above the HHW, before being mixed with the first stream containing HHW vapour.
• the first stream of carrier gas can pass over the surface of the heated HHW, or, preferably, be bubbled through the molten material. In the latter case a high and reproducible level of saturation of the stream with HHW vapour can be achieved.
• a more preferred embodiment of flash vaporization provides control of the rate of feeding the HHW vapour and is particularly useful when the HHW contains compounds of widely differing vapour pressure.
• the molten or liquid HHW is fed at a controlled rate into a heated vaporizer maintained at a temperature at or above 300 C.
• the HHW vapour is then carried to the flame by a stream of pre-heated hydrogen.
• The.-nature of the construction material of the va ⁇ ourizer is fairly critical in that some materials, for example, stainless steel, may lead to decomposition of the HHW to form carbon.
• a preferred construction material is mild steel.
• the purity of the oxygen gas used in our process is not narrowly critical but should contain at least 40% w/w oxygen and preferably at least 90 % w/w oxygen. Air is not suitable since it does not provide a stable flame without soot formation.
• the burning means may comprise, for example, a relatively simple burner such as an arrangement of concentric pipes with the carrier gas/HHW vapour passing through the inner tube and oxygen through the outer tube.
• the hydrogen/HHW mixture will then burn within a sheath of oxygen to give a laminar flame.
• Suitable burners can be readily constructed and are inexpensive.
• the combustion chamber can be fabri ⁇ cated from any suitable metal provided that cooling is adequate and the reactant gases are kept above their dew point.
• Other suitable materials are carbon and quartz.
• Hydrogen/oxygen flames typically have a temperature in the vicinity of 2700 C. However, when the heavy halogenated wastes are burnt in this flame the tempera- tures is lower and may be as low as 2000 C. With small- scale equipment air cooling of the combustion chamber surrounding the flame may be adequate for the tenrpera- tures reached.. For larger-scale equipment cooling means will probably be necessary and suitable equipment, will be obvious to those skilled in the art.
• C PI collection means the hydrogen chloride from heavy chlorinated wastes can be virtually completely recovered • as concentrated or fuming hydrochloric acid.
• the other combustion products from our process are carbon dioxide and water.
• FIGURE 1 shows a schematic view of an embodiment of the apparatus wherein the carrier gas comprising hydrogen is passed over heated HHW and the HHW/hydrogen vapour is burnt in a hydrogen/oxygen flame.
• FIGURE 2 shows a schematic view of an embodiment of the apparatus wherein the HHW is first heated and passed into a flash vaporizer with hydrogen before being burnt in a hydrogen/oxygen flame.
• FIGURE 3 shows a schematic view of a vessel with ribbon type mixer for preheating the HHW prior to vaporization. It should be noted that Figures 1 to 3 are not drawn to scale and the relative dimensions and proportions of some parts of these Figures have been shown enlarged or reduced for the sake of clarity and convenience.
• Figure 1 shows a vaporizer 10 comprising a vessel with entry tubes 11 and 12, and heating furnace 14. The vaporizer 10 is connected by outlet tube 13 to burner 15 bearing an entry tube 16 which is concentrically disposed around the tube 13.
• the vaporizer 10 is connected by outlet tube 13 to burner 15 bearing an entry tube 16 which
• Olv ⁇ FI burner 14 is attached to a combustion chamber 17 within cooling means 18.
• the combustion charier 17 is connected by an outlet tube 19 to a water-cooled condensation column 20 equipped with a receiver 21 and a water or optionally an aqueous sodium hydroxide scrubber 22.
• the heavy halogenated wastes 23 are placed in the vaporizer 10 and heated by the furnace 14.
• a first stream of hydrogen is fed into the vaporizer 10 by means of inlet tube 11 and bubbled through or passed over the molten HHW .23 before leaving the vaporizer 10 by tube 13 to the burner 14.
• a second stream of hydrogen passes through tube 12 so as to enter the vaporizer 10 close to the entrance of the tube 13. Both hydrogen streams are preheated by cooling the tubes 11 and 12 around a heated block (not shown in Figure 1) .
• Oxygen is fed to the burner 14 through the tube 16 to produce the flame in combustion chamber 17.
• the HHW is combusted in the hydrogen/oxygen flame in combustion chamber17 and the hot combustion products pass through tube 19 to the water-cooled condenser 20.
• the condensed products are collected in the receiver 21 and the non- condensed products, mainly carbon dioxide and oxygen, are passed through the scrubber 22.
• FIG 2 shows a heating vessel 24 with heating furnace 25 connected via a metering pump 26 and tube 27 to a lash vaporization chamber 28 fitted with heating means 9 , an inlet tube 30 and outlet tube 31.
• the HHW is heated in the vessel 24 and the molten HHW is delivered to the heated vaporization chamber 28 via the pump 26 which can be operated to accurately control the rate of* addition of HHW.
• a stream of preheated hydrogen is admitted to the vaporizer through inlet tube 30. and the mixture of HHW vapour and hydrogen is passed through outlet tube 31 to a burner.
• Figure 3 shows a heating vessel 32 fitted with a horizontal ribbon type mixer 33.
• the vessel 32 is heated with a furnace 34 and has an inlet port 35, an outlet tube 36, and a discharge port 37.
• the HHW is introduced through the inlet port 35 into the heated vessel 33 .
• the HHW melts and is forced by the ribbon mixer 33 along the unit to the outlet tube 36.
• the ribbon mixer 33 assists in heat transfer and also trans ⁇ fers unmelted residues to the vicinity of the discharge port 37 from time to time, thus avoiding contamination of the rest of the apparatus.
• a further advantage of our process is that the only HHW materials handling required is the transport of the cold waste from the plant or store to the melting unit and vaporizer which were described hereinbefore. It is also possible to construct a unit of such a size that it is sufficiently portable to be moved between the various plants or stores where the HHW are generated or held.
• Some HHW for example, hexachlorobenzene
• HHW hexachlorobenzene
• Some HHW are . solids and are practically insoluble in conventional solvents. Loading such solids into conventional in ⁇ cinerators is technically very difficult and hazardous. Introduction of such material intc the burner of our process in the form of a vapour greatly reduces the materials handling requirement.
• the concentrated acid solutions produced from our process are more readily neutralized and eliminated as liquid effluent than the very dilute acid solutions of the prior art incinerators.
• the use of hydrogen as a carrier gas ensures a minimum volume of non-condensable vent gas and thus reduces the size of the hydrogen halide scrubber required.
• HBC technical hexachlorobenzene
• HCB HCB was placed in the vaporizer. All the connecting tubings were heated to 250°C to prevent condensation of HCB. During the burning, fuming concentrated hydrochloric acid was collected in the receiver. The flame was bright and luminous.
• the amount of uncombusted HCB was 30 ug, corresponding to a destruction efficiency of 99.9999%.
• the flame temperature was calculated to be around 2,500°C and the residence time 0.08 sec.
• the second stream of hydrogen was used to control the saturation of HCB in the hydrogen carrier to the burner. About 80% v/v HCB saturation was achieved and no blockages occurred in the lines under this condition.
• Rate of burning 0.3 g/min
• Amount of condensate 524 ml
• Chlorine content - 53.0 g
• PCBs perchlorobiphenyls

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Organic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Business, Economics & Management (AREA)
• General Health & Medical Sciences (AREA)
• Toxicology (AREA)
• General Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Chemical & Material Sciences (AREA)
• Health & Medical Sciences (AREA)
• Emergency Management (AREA)
• Inorganic Chemistry (AREA)
• Environmental & Geological Engineering (AREA)
• Treating Waste Gases (AREA)
• Incineration Of Waste (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Priority Applications (3)

Applications Claiming Priority (2)

Publications (1)

Family

ID=3768872

Family Applications (1)

Country Status (5)

Cited By (9)

Families Citing this family (5)

Citations (7)

Family Cites Families (3)

• 1981
  • 1981-12-07 JP JP57500040A patent/JPH0215225B2/ja not_active Expired - Lifetime
  • 1981-12-07 GB GB08300453A patent/GB2110198B/en not_active Expired
  • 1981-12-07 WO PCT/AU1981/000186 patent/WO1982002001A1/en active Application Filing
  • 1981-12-07 US US06/394,916 patent/US4464351A/en not_active Expired - Fee Related
  • 1981-12-08 ZA ZA818515A patent/ZA818515B/xx unknown

Patent Citations (7)

Also Published As

Similar Documents

Legal Events