Drying and gas or vapor contact with solids – Apparatus – With means to treat gas or vapor
Reexamination Certificate
2001-06-01
2003-05-27
Lazarus, Ira S. (Department: 3749)
Drying and gas or vapor contact with solids
Apparatus
With means to treat gas or vapor
C034S081000, C034S109000, C034S128000
Reexamination Certificate
active
06568100
ABSTRACT:
The present invention relates to a gas dryer which includes a drying drum containing an adsorbent material, and, in particular, to such a dryer in which a primary gas is dried using the adsorbent material and in which a secondary gas is used to regenerate the adsorbent material.
A drum dryer which can be used in a compressed gas system comprises a housing and a quantity of an adsorbent material within the housing by which fluid in the gas to be dried (the primary gas flow) can be adsorbed. The fluid can be aqueous (especially water) or non-aqueous. It will generally be entrained in the primary gas flow in gaseous form (for example as a vapour), although it can be entrained in liquid form (for example as droplets). The adsorbent material can be regenerated for reuse by means of a secondary gas flow which is supplied to the drum to flow over the adsorbent material which is loaded with adsorbed fluid. The secondary gas flow is usually in the opposite direction to the primary gas flow. Such dryers are particularly used in compressed air processes as dehumidifiers to remove vapour from a compressed gas stream which has been cooled after compression stages. The secondary gas flow which is used to regenerate the adsorbent material can be compressed air at elevated temperature as a result of the compression stage, which is fed through the adsorbent material so as to regenerate it.
An example of a drum dryer is disclosed in U.S. Pat. No. 5,385,603, in which an adsorbent material is arranged in on the surface of a cylindrical drum which is arranged to rotate around its longitudinal axis. The adsorbent material can be define a plurality of parallel channels for gas to flow over the surface of the drum, in a direction that is parallel to the drum axis. The drum and the housing between them can provide partitions by which the housing can be divided into different regions for gas to flow through the drum. One of the regions can be for the primary gas flow in which the adsorbent material adsorbs entrained fluid, and the other of the regions can be for the countercurrent secondary gas flow, which is used to regenerate the adsorbent material by desorbing adsorbed fluid. The drum is driven rotationally by a motor positioned at one end of the axis of rotation. The axis is only supported transversely at the end from which it is driven. The dryer has a system of seals located around the periphery of the drum, between the drum and the housing, to keep the primary and secondary gas flows separate. Frictional forces between the drum and the housing can place significant load on the motor by which the drum is made to rotate.
The present invention provides a gas dryer in which the primary and secondary regions of a drying drum are defined by flow guides mounted at opposite ends of the drum, which can rotate around the drum axis so that boundaries between regions of the drum for the primary and secondary gas flows rotate around the drum.
Accordingly, in one aspect, the present invention provides a gas dryer which comprises (a) a housing, (b) a drying drum in the housing which is permeable to allow flow of gas through the drum between its opposite first and second ends, (c) a first flow guide at the first end of the drum and (d) a second flow guide at the second end of the drum, the first and second flow guides defining between them a primary region of the drum for a primary gas flow to flow through the drum, and a secondary region of the drum for a secondary gas flow to flow through the drum, and being mounted for rotation around the drum axis so that boundaries between the primary and secondary regions rotate around the drum, the permeable structure of the drying drum and the flow guides allowing the primary and secondary gas flows to flow through their respective regions of the drum without significant mixing.
The dryer of the invention has the advantage that the drum which provides the adsorbent material for the gas can be fixed within the housing. The drum need not therefore be mounted for rotation: this enables the problem of mounting the drum on a shaft that is driven rotationally at one end but which is unsupported transversely at its other end. The dryer of the invention is therefore able to withstand transverse forces such as it might be exposed to during transportation. Furthermore, the need to provide seals between a moving drum and the adjacent side wall of the housing, as in known dryers, is avoided. As a result, the frictional forces which have to be overcome during operation of the dryer of the invention can be kept low, reducing the energy requirements during operation of the dryer.
The absence of moving seals between the drum and the housing of the dryer of the invention can also simplify assembly of the dryer.
Preferably, the first and second flow guides are arranged for rotation about a common axis. The dryer can include a drive shaft which passes through the centre of the drying drum. The first flow guide can be mounted on the drive shaft at the first end of the drying drum and the second flow guide can be mounted on the drive shaft at the second end of the drying drum. Preferably, the dryer includes locating means which urges one or both of the first and second flow guides towards the drying drum. This can help to minimise unwanted loss of gas. Preferably, the first and second flow guides are configured such that the leading edges of the flow guides are maintained at a controlled clearance from the respective ends of the drying drum so as to prevent significant egress of gas from the flow guides, while preventing contact of the guiding edges with the respective ends of the drying drum. The clearance will be kept as small as possible, consistent with avoiding contact between the flow guides and the ends of the drum. The actual clearance will depend on factors such as the accuracy with which the drum is manufactured. If the drum can be manufactured with sufficient control, the clearance between the flow guides and the drum might be as small as 4 mm or less, for example not more than about 2 mm, preferably not more than about 1 mm.
Preferably, the dryer includes a support extending between an internal surface of the housing and a side wall surface of the drying drum, to fix the drum against movement relative to the housing and to support the drum in the housing. The provision of movable flow guides in the dryer of the invention allows the drum to be fixed. This can simplify control over the clearances between the drum and the flow guides, since the location of the more massive drum component can be controlled by virtue of it being fixed to the housing.
Preferably, the support for the drum contacts the side wall surface of the drum at a point between its ends. Preferably, the support bears substantially the entire weight of the drying drum; this facilitates control over the clearances between the drum and the flow guides. Preferably, the support extends around the entire periphery of the drum. A suitable form of support might be for example a substantially right angular flange.
The support for the drum can extend continuously around the drum so as to divide the housing into first and second chambers, such that gas can only pass between the first and second chambers through the drum.
To facilitate manufacture, the housing can comprise first and second housing parts, with the support attached to the housing at the interface between the housing parts. Preferably, the housing parts have substantially the same shape and configuration. This reduces inventory during manufacture. When the port on the second housing part is not required for outflow of gases, a blanking piece can be provided within it to close it against gas flow.
Preferably, the dryer has a space around the drum between the internal wall of the housing and the external surface of the drum, and includes an inlet for the gas to be dried by which gas is directed into the space, to flow in the space to the first end of the drum.
Preferably, the cross-section of at least one, especially both, of the drum and the housing is substanti
Billiet Colin Thomas
Fielding Robert Michael
Sienack Desideratus Julius
Domnick Hunter Limited
Lazarus Ira S.
Maginot Moore & Bowman
Ragonese Andrea M.
LandOfFree
Gas dryer does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Gas dryer, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Gas dryer will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3048318