Chemical apparatus and process disinfecting – deodorizing – preser – Chemical reactor – Including specific material of construction
Reexamination Certificate
1997-11-14
2001-01-23
Knode, Marian C. (Department: 1764)
Chemical apparatus and process disinfecting, deodorizing, preser
Chemical reactor
Including specific material of construction
C422S241000, C422S242000
Reexamination Certificate
active
06177054
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a reactor vessel, to a high pressure reactor comprising such vessel, to a high pressure reactor system comprising two or more of these high pressure reactors, to a process for manufacturing the reactor vessels and to the use of these high pressure reactors and reactor systems in operations requiring high pressures.
High pressure reactors are known in the art. They usually comprise a cylindrically-shaped stainless steel vessel of sufficient thickness to withstand the radial forces caused by the high pressures applied and one or two pistons elements, optionally provided with pressurizing and depressurizing means, for building up the pressure inside the reactor vessel. In case one movable piston element is used, the other plugging element at the opposed side is rigidly connected to the vessel at its opening. Usually a liquid medium, such as for instance water, is used inside the reactor for attaining the high isostatic pressures. The sample to be subjected to the high pressure is placed in the liquid medium, after which the liquid medium is compressed, thereby subjecting the sample to isostatic pressure.
The available high pressure reactors have a limitation in that stainless steel starts to flow at pressures above 5,000 bar. Thus, at pressures above 5,000 bar additional, expensive, measures are normally necessary. Furthermore, the resistance of stainless steel against rapid, large pressure changes is not optimal. The present invention aims to overcome these disadvantages and aims to provide a reactor which requires less material in terms of weight, whilst being at least equally strong as stainless steel reactors at a lower cost. A further object of the present invention is to provide a reactor, which can withstand isostatic pressures of up to 15,000 bar. It has been found that these and other objects can be attained by the use of certain fibers in the wall of a reactor vessel.
SUMMARY OF THE INVENTION
Accordingly, the present invention relates to a reactor vessel comprising:
(a) a cylindrically shaped, hollow core element as the inner wall, which element is open at both ends; and
(b) at least one layer of high performance fibers, preferably having a tensile strength of at least 100 MPa, arranged around the core element in a substantially circumferential orientation,
wherein the fibers are embedded in a rigid polymeric or resinous matrix.
The cylindrically shaped core element to be used may be a liner, but may also be a fine-meshed or a large-meshed metallic netting. The metal to be used preferably is stainless steel. In a particularly preferred embodiment, however, the core element is a stainless steel liner. The thickness of such liner may vary between wide limits, but a thickness of from 5 mm to 10 cm, preferably from 5 mm to 3 cm, has been found particularly advantageous.
The inner diameter of the core element and hence of the reactor vessel will normally range from 10.0 cm up to 100.0 cm depending on the desired reactor volume, but smaller or larger diameters could also be used. An inner diameter of from 15.0 to 50.0 cm is most conveniently used. The inner height of the reactor may vary within wide limits, but suitably ranges from 50.0 cm to 200.0 cm, more suitably from 60.0 cm to 125.0 cm. Reactor volume, accordingly, suitably ranges from about 15.5 to about 6,000 liters, more suitably from about 40 to about 1,000 liters. A reactor volume of from 150 to 500 liters has been found to be particularly useful, mainly in view of ease of handling, process control and cost of construction material.
The high performance fibers, that may be used for the purpose of the present invention, include both organic and inorganic fibers and should have such stress/strain properties (particularly a sufficiently high tensile strength) that it is able to withstand the high radial forces exerted onto the walls of the reactor vessel as a result of the very high pressures applied. It will be appreciated that the exact tensile strength of the fibers to be used is determined by the pressure applied in the reactor and the number of layers and the type of fibers to be used. It has been found that the fibers used should preferably have a tensile strength of at least 500 MPa in order to be suitably applied. However, fibers having a tensile strength of at least 1 GPa are more preferred, whilst fibers having a tensile strength of 2 GPa or more are most preferably used. The fibers to be used should also have a high modulus, suitably of at least 5 GPa and more suitably of at least 25 GPa. A modulus of 60 GPa or more is most preferred. The fibers to be used should also have a relatively low elongation at break, i.e. they should not be too elastic. Suitably, the elongation at break of the fibers used should not exceed 5% and preferably is at most 3%. An elongation at break of 1.5% or less is most preferred.
Several high performance fibers may be used for the purpose of the present invention. In general, four main classes of suitable high performance fibers can be recognised: the (modified) carbon fibers, the rigid-rod polymeric fibers, the gel spun fibers and the vitreous fibers.
Carbon fibers are very suitably applied in at least one layer constituting the wall of the reactor vessel according to the present invention. The term carbon fiber as used herein refers to filamentary products composed of more than 90% carbon and having a filament diameter of 3-15 &mgr;m and more preferably 5-12 &mgr;m. Carbon fibers are normally produced via the pyrolysis of polyacrylonitrile (PAN), pitch or rayon. A specific category of carbon fibers are the graphite fibers having a three-dimensional graphite structure. The preferred carbon fibers are the PAN-based fibers, of which the high modulus PAN-grades having a tensile modulus of 350 to 480 GPa, a tensile strength of 1.7 to 4.7 GPa and an elongation at break of 0.4 to 1.4% and the ultra high modulus PAN-grades having a tensile modulus of 500 to 600 GPa, a tensile strength of 1.7 to 3.9 GPa and an elongation at break of 0.3 to 0.7% are most preferably applied.
The rigid-rod polymeric fibers include the lyotropic liquid crystalline polymers and the thermotropic liquid crystalline polymers. The first class is the most important and comprises the aramid fibers. Suitable and well known aramid fibers are those consisting of p-phenylene heterocyclic rigid-rod polymers like poly(p-phenylene-2,6-benzobisthiazole) and poly(p-phenylene-2,6-benzobisoxazole) and those consisting of benzimidazole polymers like poly(2,2′-(m-phenylene)-5,5′-bisbenzimidazole). Aramid fibers are commercially available, for instance under the trade name KEVLAR and NOMEX.
The gel spun fibers include the high performance polyethylene (HPPE) fibers manufactured by DSM and Allied Signal and sold under the trade names DYNEEMA and SPECTRA. These HPPE fibers are based on ultra high molecular weight polyethylene, i.e. polyethylene molecules having a weight average molecular weight of 1×10
6
or higher.
The vitreous fibers, finally, include the glass fibers and refractory ceramic fibers. These fibers are composed of glass which is in the vitreous state. In general, the vitreous state in glass in somewhat analogous to the amorphous state in polymers, but unlike organic polymers, it is not desirable to achieve the crystalline state in glass. Glass fibers are normally produced from glass-forming compounds like SiO
2
and P
2
O
5
mixed with other intermediate oxides like Al
2
O
3
, TiO
2
or ZnO and modifiers like MgO, Li
2
O, BaO, CaO, Na
2
O and K
2
O. The purpose of these modifiers is to break down the SiO
2
network, so that molten glass has the proper viscosity characteristics to allow it to cool to the desired vitreous state. The refractory ceramic fibers are produced by using high percentages of Al
2
O
3
(normally about 50%) in admixture with SiO
2
as such or modified with other oxides like ZrO
2
or by using Kaolin clay, which contains similarly high amounts of Al
2
O
3
.
The reactor vessel according to the present invention comprises
Instituut Voor Agrotechnologisch Onderzoek (ATO-DLO)
Knode Marian C.
Ohorodnik Susan
Webb Ziesenheim & Logsdon Orkin & Hanson, P.C.
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