Furnaces – Process – Treating fuel constituent or combustion product
Reexamination Certificate
1998-11-16
2001-08-14
Ferensic, Denise L. (Department: 3749)
Furnaces
Process
Treating fuel constituent or combustion product
C110S238000, C110S342000, C110S348000, C110S204000, C423S24000R
Reexamination Certificate
active
06273008
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an improved method for treating chlorinated hydrocarbons in valorization of chlorinated residuals (VCR) process unit (see, e.g., U.K. Pat. No. GB 2053452) and the chlorinated hydrocarbon waste incinerator, and more particularly to a method for modifying these systems such that a synthesized blend of carbon dioxide and oxygen replaces the ordinary air used to fuel the reaction in either system, thereby generating a useful hydrogen chloride product and a useful carbon dioxide product in both the VCR process unit and the chlorinated hydrocarbon waste incinerator. The invention further encompasses modifications to the anhydrous hydrogen chloride purification unit attached to these systems that prevent the discharge of any hydrochloric acid streams containing three (3%) percent by weight or greater hydrogen chloride dissolved in water. Furthermore, the invention encompasses the addition of absorbent beds to these systems that remove contaminants from the carbon dioxide product, with these contaminants ultimately being recycled back into the high temperature reactors, where they are converted to hydrogen chloride and carbon dioxide. Also, the invention encompasses the addition of a unit whereby oxygen that is present in the carbon dioxide exiting the absorbent beds is separated from the final carbon dioxide product stream and then recycled back into the high temperature reactor.
BACKGROUND OF THE INVENTION
Chlorinated hydrocarbon by-product materials are generated in a wide variety of chlorinated hydrocarbon manufacturing operations, such as the manufacture of ethylene dichloride, vinyl chloride monomer, methyl chloroform, trichloroethylene, perchloroethylene, allyl chloride or mono and dichlorobenzene. These are all commercial products, some of which may be used as solvents, others as feedstocks for producing materials such as non-ozone depleting refrigerants, plastic film (Saran Wrap®), polyvinyl chloride, Teflon®, or Kynar®. The chlorinated hydrocarbon by-products of these manufacturing operations have been traditionally considered hazardous wastes requiring carefully regulated treatment. One common method for treating these hazardous by-products is to destroy them in a chlorinated hydrocarbon waste incinerator. In such systems, the liquid wastes are injected into a natural-gas fired incinerator, where the chlorinated organic molecules are essentially oxidized, thus yielding hydrogen chloride (HCl), salt water and a vent gas comprised mostly of nitrogen and carbon dioxide. An example of this type of system is depicted in FIG.
1
.
Steam, or perhaps water, that is sometimes used to cool the reaction in these incinerators mixes with the hydrogen chloride, thus yielding a weaker hydrochloric acid by-product solution. This hydrochloric acid by-product, from four to twenty (4% to 20%) percent by weight hydrogen chloride, is too weak for typical commercial uses, which generally require acid strengths in excess of thirty-one (31%) percent by weight hydrogen chloride. Therefore, the useless hydrochloric acid by-product must be neutralized and disposed of as salt-water waste. Under federal guidelines, any unit producing an acid stream greater than three (3%) percent by weight hydrogen chloride must be classed as a halogen acid furnace (HAF) under the General Hazardous Waste Rules. This weak acid stream is therefore considered an undesirable waste product. Furthermore, the pre-dominately nitrogen/carbon dioxide waste gas generated in these incinerators is simply vented into the atmosphere. Some of the components present in the incinerator may also be converted into extremely toxic dioxin and into nitrous oxide, which may then appear in the vent gases. The fact that all by-products of the typical chlorinated hydrocarbon incineration unit are un-useful, undesirable waste materials represents a disadvantage to this system.
The valorization of chlorinated residuals (VCR) process unit, similar to the incinerator described above, was designed specifically to produce at least one useful by-product of the typical chlorinated hydrocarbon oxidation technique that takes place in an incinerator, namely anhydrous hydrogen chloride, although, of course the principles of the invention are applicable to other types of processes as well, including new facilities which are designed from the beginning to use the principles of the present invention. However, for exemplary purposes, the invention will be primarily discussed with respect to the particular BCP VCR facility described more fully below.
The VCR process unit, as employed by Borden Chemicals and Plastics (BCP) at Geismar, L A, converts the chlorinated hydrocarbon by-product left over from the manufacture of vinyl chloride monomer into useful hydrogen chloride. One method for producing vinyl chloride monomer (VCM) entails reacting acetylene and anhydrous hydrogen chloride (HCl) as the raw materials for manufacturing the VCM product (see FIG.
2
). This process, as practiced by BCP, is termed the VCM-A Process. Another method for producing VCM entails reacting chlorine or anhydrous HCl and ethylene to produce ethylene dichloride or 1,2 dichloroethane (EDC). The EDC is then thermally reacted to produce VCM (see FIG.
3
). This process, as practiced by BCP, is termed the VCM-E Process. In both VCM processes, the chlorinated hydrocarbon by-product, also called organic intermediate materials, is generated. These organic intermediate materials consist primarily of the following chemical components:
ethylene dichloride (CH
2
ClCH
2
Cl), trichloroethane (CHCl
2
CH
2
Cl), 1,1,2,2 tetrachloroethane (CHCl
2
CHCl
2
), 1,1,1,2 tetrachloroethane (CHCl
3
CH
2
Cl), and pentachloroethane (CHCl
2
CCl
3
)
Compounds such as chloroprene, 1,1 dichloroethane, 1,1,1 trichloroethane, chloroform, carbon tetrachloride, cis/trans-dichloroethylene, trichloroethylene, perchloroethylene and various other chlorinated organic compounds are also possible intermediate materials. These organic intermediate materials are further used as feedstock in the VCR process unit, whereby anhydrous HCl is manufactured for use as a raw material feedstock for the VCM-A process described above. The VCR process unit therefore serves as an HCl manufacturing unit using as feedstock the organic intermediate materials produced in the VCM-A and VCM-E processes, the intention being to maintain a “closed-loop” manufacturing process whereby all intermediate materials are usefully and beneficially utilized.
Thus, the VCR process unit is designed specifically to use the organic intermediate by-product of both VCM processes as a feedstock for manufacturing HCl, a necessary raw material in the VCM-A and VCM-E processes. The reaction taking place in the VCR process unit is depicted in FIG.
4
. The system itself is depicted in FIG.
5
.
The VCR process unit uses two raw materials for manufacturing HCl, namely the organic feedstock and air. These raw materials are mixed in the VCR reactor, which contains a proprietary mixing device in which HCl is initially manufactured. In this mixing device, vaporized liquid feedstock is introduced into a high velocity, high temperature air stream. The feedstock and the air react to form anhydrous HCl. The type of reactions that occur in the VCR process are represented by the following equation:
CH
2
ClCH
2
Cl+CHCl
2
CH
2
Cl+4.5O
2
+N
2
—5HCl+4CO
2
+H
2
O+N
2
From the VCR reactor, the anhydrous HCl is directed into a purification unit and then used as feedstock in the VCM-A process. Excess water generated in the reactor must be purged from the system via this HCl purification unit. Since this purge water contains greater than three (3%) percent by weight hydrogen chloride, thus constituting a weak acid stream, the VCR process unit is also classed as a halogen acid furnace. This weak acid purge must be neutralized to form salt water, which may then be sewered.
Meanwhile, a gaseous by-product, comprised mainly of CO
2
, N
2
, and minimal amounts of O
2
, HCl and Cl
2
, is directed into an alkaline-fed s
Dominqu{dot over (e)}& Waddell
Ferensic Denise L.
Rinehart K.
LandOfFree
Chlorinated hydrocarbon waste incinerator and valorization... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Chlorinated hydrocarbon waste incinerator and valorization..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Chlorinated hydrocarbon waste incinerator and valorization... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2441264