Liquid purification or separation – Plural distinct separators – Filters
Patent
1991-10-07
1993-07-13
Dawson, Robert A.
Liquid purification or separation
Plural distinct separators
Filters
210402, 210403, 210404, 210406, 2104161, B01D 3300, B01D 3306
Patent
active
052270645
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a filter for continuous filtering of a suspension The filtering takes place under pressure or under vacuum or under a combination of pressure and vacuum.
BACKGROUND OF THE INVENTION
As previously known, the filter includes a vessel containing the suspension to a certain level and a gas space positioned above the suspension, an essentially horizontal center axle rotatably arranged in the vessel, filter discs spaced from each other along the center axle and substantially perpendicular to the latter, the filter discs consisting of filter sectors with surrounding filter cloth and internal channels for filtrate and gas obtained during the filtering, connection means in the center axle between the filter sectors and an outlet from the vessel, removing means for each filter disc arranged in the gas space for the removal of filter cake obtained on the filter cloth during filtering, and means for receiving the filter cake material removed by the removing means.
It is known to use as the removing means in such filters a so-called doctor, i.e., a scraper or cutter principally in the form of a planer. The scraper is arranged immediately above the suspension level where the filter sectors descend into the suspension, i.e., at the end of the rotation of the filter sectors in the gas space. In these filters, the scrapers are therefore positioned substantially horizontally. Such positioning of the scrapers, however, results in several disadvantages. Scraped-off material tends to shuffle over the scraper with accompanying risk of deposits on the scraper. Moreover, this positioning of the scraper limits the utilization of the filtering surfaces of the filter discs, since the suspension level in the filter vessel can be no higher than the position for the scraper. The positioning of the scrapers furthermore means that the receiving device must be formed relatively wide, at least in its upper part, and then taper downwardly to a circular outlet. This results in a relatively large distance between the filter discs. Furthermore, there is a great risk that scraped-off material is built up in the downwardly directed cone from rectangular cross-section at the scrapers to circular cross-section at the discharge of scraped-off material through the bottom of the vessel.
By the present invention, the above disadvantages have been eliminated. In applicant's filter, the removing means consists of an substantially vertically arranged scrape for removing at least an outer layer of the filter cake along a substantially vertical line for substantially vertically sliding and dropping down of the scraped-off filter cake material along the scraper. As a result of this positioning of the scraper, scraped-off material tends to slide along the scraper without drag and to drop therefrom. The scraper is accordingly not under load. Moreover, the scraped-off material falls in a controlled, substantially hour-glass form. Furthermore, the risk of build-up is eliminated, in contrast to what happens in the case of horizontally positioned scrapers. Another advantage, with the positioning of the scrapers according to the invention, is that the suspension level in the filter can be raised drastically so that the filtering surface can be optimally used, resulting in high and optimal capacity for each filter disk. Another advantage is that positioning of the scrapers according to the invention results in a filter construction having considerably less distance between the filter disks on the center axle; this permits a substantially smaller filter dimension for the same capacity.
Preferably, the scraper is so inclined that the lower end of the scraper is further away from a vertical plane through the center axle than the upper end of the scraper. Such positioning further facilitates dropping of scraped-off filter cake material off the scraper.
In a preferred embodiment, the receiving device consists of a substantially vertically arranged outlet pipe. Due to the form of a vertical scraper, this outlet
REFERENCES:
patent: 3698556 (1972-10-01), Emmett, Jr. et al.
patent: 3744543 (1973-07-01), Emmett, Jr. et al.
patent: 4168234 (1979-09-01), Hutto, Jr.
patent: 4695381 (1987-09-01), Ragnegard
patent: 4769986 (1988-09-01), Kokkonen et al.
patent: 4929355 (1990-05-01), Ragnegard et al.
patent: 5073264 (1991-12-01), Immonen et al.
Dawson Robert A.
Fortuna Ana M.
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