Electric heating – Metal heating – By arc
Reexamination Certificate
1999-10-04
2002-08-27
Berman, Jack (Department: 2881)
Electric heating
Metal heating
By arc
Reexamination Certificate
active
06441336
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention concerns improvements in and relating to collecting and/or separating of materials, and in particular, but not exclusively, to the collecting and/or separating of ionised and/or vaporised species.
2. Present State of the Art
A number of separation techniques, such as ion cyclotron resonance, generate different energy levels in the ionised materials fed to them and make a separation based on this. In the case of ICR the energy level of one or more selected elements or isotopes can be significantly higher than for other elements or isotopes.
Prior art collection of such materials is based on the simultaneous discharge and solidification of the higher energy species, followed by a separate similar procedure applied to the lower energy species.
One such system employs an open lattice of plates presented to the process stream flow. The plates are earthed or held at a fixed electrical potential to effect discharge of the components striking them. The grid is also cold relative to the process stream and as a consequence species contacting it are solidified on the grid at the time of discharge. The grid can periodically be removed from the process stream and the solidified material removed.
The lower energy level material, due to a number of factors, largely avoids the grid. Separate discharge and condensing is effected for this part of the process stream on a subsequent collector.
Other techniques, such as various selective ionisation processes, also call for the collection of a process stream presented in an ionised, vaporised form. Similar techniques have been used to effect their collection.
The collector/separation systems of the prior art are not ideal for a number of reasons. These include the need to provide a high level of cooling into the structure and the need to remove the collecting structure from the stream periodically. Periodic collection systems render the collection of the product an essentially batchwise process restricting active processing. Furthermore, during the time between introducing a clean grid and its removal, when loaded, the operation of the collection system is also undesirably variable as the build-up of collected material effects the efficiency of the collection. Such collection grids are also not applicable for processing streams which generally result in liquid or gaseous products as such product would not be retained by the grid. The processing of water to give heavy water, for instance, does not readily provide a product suitable for collection on the grid.
Objects and Brief Summary of the Invention
The present invention aims to provide alternative collection/separation system and method of operation which addresses at least some of the problems with prior art collectors/separators.
According to a first aspect of the invention we provide a method of collecting at least part of an at least partially ionised sample contained within a retaining portion of a magnetic field, comprising the steps of:
a) discharging a part of the sample to be collected by contact with an electrical conductor;
b) the discharged part of the sample leaving the confines of the retaining portion of the magnetic field; and
c) separately collecting the discharged part of the sample or converting the discharged part of the sample to a liquid or solid form.
In this way the part of the sample to be collected need not be deposited on the same element as it used to discharge it, but is instead recovered or converted to a non-vaporised state elsewhere.
The sample may be completely or substantially completely in ionised form.
The discharged part of the sample may be removed from the confines of the retaining portion of the magnetic field prior to collection or prior to conversion to liquid or solid form. This is particularly preferred where only a portion of the sample is to be collected or only some in the sample are to be collected, for instance in a separation technique.
Alternatively the discharged part of the sample may be collected or may be converted to a non-vaporised state within the confines of the retaining portion of the magnetic field, or a reduced strength magnetic field portion, and removed subsequently. This sequence may be applicable where the whole of that stream is to be so converted, following a prior separation stage for instance.
The sample may still be within a magnetic field following its leaving the retaining portion of the magnetic field. The charged species, however, are restricted to this retaining portion of the magnetic field. The retaining portion of the magnetic field may be provided at between 0.5 and 10 and preferably between 1 and 6 Tesla.
Preferably the collection method provides a separation of one part of the sample from another part of the sample. The one part may be, or include, a different element and/or different isotope and/or different compound to the other part. The one part and/or other part may consist of all of a selected element and/or isotope and/or compound in the sample. Alternatively a portion of the selected species may still be present in the other part after separation.
The separation may be of U from Pu and/or either or both from fission reaction products; of
235
U from
238
U; of D
2
O and/or HDO from H
2
O; of D
2
and/or DH from H
2
; or other such separations. The separations may be performed in discrete atomic and/or elemental and/or molecular forms, as ions.
Preferably the separation of one part of the sample from another part of the sample is based on the one part of the sample having a higher energy level than the other part. The differential energy levels are preferably provided selectively. Ion cyclotron resonance may be used to provide the differential energy levels.
Preferably the higher energy level part is discharged on contacting the electrical conductor. Preferably all, or substantially all of the one, high energy, part contacts the electrical conductor. Preferably the lower energy other part, or the substantial part thereof, avoids the electrical conductor.
The discharged portion of the sample may leave the confines of the retaining portion due to a lower pressure outside the confines of the retaining portion of the magnetic field. The pressure difference may arise due to an elevated pressure within the retaining portion of the magnetic field and/or, more preferably, a depressed pressure outside the retaining portion of the magnetic field. The depressed pressure may be generated by a vacuum pump. The pressure differential may also be used to remove the discharged part of the sample from the unit to a remote location, for instance entirely out of the magnetic field.
A conversion from uncharged vapour to liquefied or solidified form may be provided and may be effected by contacting the discharged portion of the material with a reduced temperature component. The component temperature being such as to reduce the material below its liquification or solidification point for the conditions at that location. A contact surface may be employed. A liquefied product and/or solidified product may be generated.
Removal means may be provided to remove the liquefied or solidified material from the unit to a product stream.
The discharged portion of the sample may be retained as a vapour or gas form as the separated part of the sample.
Solidified products may include uranium dioxides. Liquid product forms may include D
2
O. Gaseous product forms may include D
2
.
The undischarged part of the sample may be discharged and/or converted to a non-vaporised state at a further location. Single stage discharge and conversion to product form, such as a non-vaporisation state is preferred. The discharge may be affected by contacting the undischarged part of the sample with a conductor. The conductor may be provided at an applied potential or earthed potential. Contacted with a cooled surface may be employed. A gaseous and/or liquid and/or solid product may be produced.
According to a second aspect of the invention we provide collecting apparatus comprising a magnetic f
Berman Jack
British Nuclear Fuels PLC
Smith II Johnnie L
Workman & Nydegger & Seeley
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