Organic compounds -- part of the class 532-570 series – Organic compounds – Amino nitrogen containing
Reexamination Certificate
1997-01-16
2001-07-03
Hruskoci, Peter A. (Department: 1724)
Organic compounds -- part of the class 532-570 series
Organic compounds
Amino nitrogen containing
C210S761000, C210S205000, C422S198000, C422S208000, C521S045000, C562S483000, C562S485000, C564S497000, C568S868000, C568S871000
Reexamination Certificate
active
06255529
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention concerns a method of and an apparatus for decomposing wastes in a chemical plant of decomposing wastes containing by-products formed in a chemical plant by using super-critical or high pressure/high temperature water and capable of recovering and reutilizing raw material compounds or derivatives thereof as an aimed product in a plant from the wastes. More in particular, it relates to a method of and an apparatus for decomposing wastes such as PET bottles and urethane foams by using super-critical water and high pressure/high temperature water and recovering the raw material compounds or the derivatives thereof from the wastes.
2. Description of the Prior Art
In the case of industrially synthesizing various chemical products in chemical plants, it is well-known that by-products other than aimed products are formed or unreaction products remain. For example, in a polymerizing reaction plant, a device for separating a resultant polymer and unreacted monomers in a reaction vessel is essentially provided and the recovered unreacted monomers are generally reutilized as the raw material for the polymerizing reaction. It is also known that oligomers are by-produced in the polymerizing reaction and separation/elimination steps of the oligomers are often conducted since aimed properties can not be obtained or the properties are worsened with lapse of time if the oligomers are left in the polymers. While the unreacted monomers can be reutilized by merely incorporating them again into a raw material feed line, the oligomers are subjected to incineration or discarding since they can not be handled in the same manner as the monomers.
Side reaction products or oligomer such as dimers or trimers of aimed compounds are formed not only in polymerizing reaction plants but also in chemical plants for synthesizing low molecular compounds, and such by-products or oligomers have to be separated from the aimed compounds by, for example, distillation. While by-products can be separated from low molecular materials relatively easily, since separation of the aimed compound from the oligomers is often difficult, a great amount of the oligomers and the aimed compounds are often contained after all in the wastes such as distillation residues. There are scarcely no methods of effectively utilizing such wastes and they are merely subjected to incineration or discarding treatment, which brings about a problem with a view point of resource saving.
In recent years, it has been attempted to detoxicating wastes or obtain utilizable products therefrom by using hydrolyzing or oxidizing reactions in super-critical water or high pressure/high temperature water. For example, Japanese Patent Laid-Open Hei 3-500264 discloses a method of detoxicating wastes in a discharge liquid system by utilizing oxidizing reaction under a super (or sub)-critical state, Japanese Patent Laid-Open Hei 5-31000 discloses a method of hydrolyzing various high molecular compounds by using water at a super-critical or subcritical state and, further, Japanese Patent Publication Hei 3-16328 or Japanese Patent Laid-Open Hei 5-271328 discloses a method of obtaining pure terephthalic acid and glycol from polyethylene terephthalate wastes.
However, although the technique of Japanese Patent Laid-Open Hei 3-500264 is important as a detoxicating method, it involves a problem for the usefulness of the resultant materials since the method accompanies oxidizing reaction and other publications mention nothing about methods and apparatus of efficiently decomposing wastes in chemical plants containing oligomers such as dimers.
OBJECT OF THE INVENTION
In view of the above, in the present invention, wastes in a chemical plant which can not be utilized but are merely incinerated or discarded have been noted and it is an object of the invention to establish a continuous treating method capable of decomposing target compounds such as by-products or oligomers contained in the wastes and decomposing them into raw material compounds or derivatives thereof for aimed compounds in the plant.
SUMMARY OF THE INVENTION
The present invention provides a method of decomposing wastes containing target compounds having one or more of hydrolyzable bonds of ether bond, ester bond, amide bond and isocyanate bond wherein the method comprises continuously supplying wastes in a molten state or a liquid state to a reactor, continuously supplying super-critical water or high pressure/high temperature water to the reactor and bringing the water into contact with the wastes thereby decomposing the target compounds, and recovering them as raw material compounds or derivatives thereof for the target compound.
The present invention further provides an apparatus for decomposing wastes comprising:
a reactor,
means for continuously supplying wastes containing target compounds having one or more hydrolyzable bonds of ether bond, ester bond, amide bond and isocyanate bond as they are in a molten state or liquid state to the reactor continuously,
means for supplying super-critical water or high pressure/high temperature water to the reactor, and
means for introducing a discharged liquid containing decomposition products of the target compounds discharged from the reactor into a separation device.
The decomposing method of the present invention can be applied with no particular restriction to wastes in a chemical plant so long as they contain hydrolyzable target compounds and, among all, the method is applicable effectively when the target compound is “dimer or higher oligomer of raw material compound” as the by-product in a case where the aimed compound in the chemical plant is a high molecular material, or “dimer or higher oligomer of the aimed compound” as by-products in a case where the aimed compound is a low molecular material. By using the decomposing method of the present invention, both “dimer or higher oligomer of raw material compound” and “dimer or higher oligomer of aimed compound” can be decomposed into “raw material compound or derivatives thereof”, so that resultant decomposition products can be utilized effectively. “oligomer” in the present invention means dimer or higher compound with no restriction for the numerical value of the polymerization degree since it varies depending on the kind of the polymer or the polymerizing method.
In the method of the present invention, it is preferred that the super-critical water or high pressure/high temperature water to be supplied to the reactor is set to higher than 100° C. and higher than 5 MPa, and to supply the supercritical water or high pressure/high temperature water in an equal or more amount based on the weight of the wastes in the chemical plant.
The feature of the decomposing method according to the present invention resides in that the target material is wastes in a chemical plant in a molten state or liquid state and that useful compounds can be recovered continuously from the wastes. Since the wastes in the chemical plant are discharged continuously, a storage vessel for the wastes is necessary in the batchwise treating method. Further, the batchwise process involves a problem that loss of energy is large for cooling or temperature elevation of the reactor upon batch replacement. Further, since a great amount of water is necessary for slurrifying solid-state wastes upon charging them, an energy for putting them to a high temperature is required. In the method according to the present invention, however, since the wastes in the chemical plant can be treated continuously as they are in a molten state or liquid state under constant pressure and temperature conditions, it is free from the foregoing drawbacks and extremely useful in actual operation.
The target to be decomposed in the present invention is wastes in chemical plants containing target compounds having one or more of hydrolyzable bonds of ether bond, ester bond, amide bond and isocyanate bond. When the target compound in the wastes is “dimer or higher oligomer in the raw material compound” as
Fukuzato Ryuichi
Nagase Yoshiyuki
Hruskoci Peter A.
Kabushiki Kaisha Kobe Seiko Sho
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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