Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D29/00—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor
  • B01D29/01—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor with flat filtering elements
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D29/00—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor
  • B01D29/62—Regenerating the filter material in the filter
  • B01D29/66—Regenerating the filter material in the filter by flushing, e.g. counter-current air-bumps
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D29/00—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor
  • B01D29/62—Regenerating the filter material in the filter
  • B01D29/70—Regenerating the filter material in the filter by forces created by movement of the filter element
  • B01D29/72—Regenerating the filter material in the filter by forces created by movement of the filter element involving vibrations
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D29/00—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor
  • B01D29/88—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor having feed or discharge devices
  • B01D29/94—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor having feed or discharge devices for discharging the filter cake, e.g. chutes
  • B01D29/945—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor having feed or discharge devices for discharging the filter cake, e.g. chutes for continuously discharging concentrated liquid

Definitions

• the present invention relates to a method of filter- cleaning, and a liquid-filtering apparatus where in a relatively flat and broad chamber a liquid circulating in a primary circulation flows in a so-called cross flow over a substantially plane filter element, and a fraction of the liquid amount is pressed through the filter element, whereby an ultrasonic transducer arranged with its vibration surface situated parallel to and opposite one of the surfaces of the filter element is active at least during a periodic filter-cleaning reflushing of liquid through the filter element.
• the method and apparatus according to the invention are further developments of methods and filters used for filtration of fuel oil for motors, where the filter is cleaned periodically by establishing a pressure drop in the primary oil circulation and hence a reflux of the oil through the filter element which at the same time is exposed to ultrasound, thereby causing impurities deposited in the filter to loosen and be washed away by the oil in the primary circulation.
• this is obtained in that the distance between the vibration surface of the ultrasound transducer and the surface of the filter element is reduced or eliminated during the reflushing when the transducer is active.
• Figure 1 shows a simplified diagram of a part of a fuel system of a motor, wherein the liquid-filtration apparatus according to the invention can be used,
• Figure 2 a section through an embodiment of the filter according to the invention, shown in normal position
• FIG 3 the filter of Figure 2 shown during reflushing for cleaning of the filter element
• Figure 4 a diagram illustrating the dependence of the cleaning effect on the distance between filter cloth and ultrasound-transducer during reflushing.
• a pump P which draws oil from a storage tank (not shown) through a suction pipe 10 and sends it on through a heat exchanger H to a filtration apparatus F.
• a primary circulation the greater part of the oil flows in cross flow over a filter element 7 - i.e. in a flat flow parallel to the filter cloth - and out through a primary outlet 5 and back to the pump P.
• a small part of the oil flows through the filter element 7 to a secondary outlet 6 and further through a buffer tank B to the motor (not shown).
• the filter element of the apparatus F is cleaned periodically by reflushing, a valve 1 at regular time intervals - or controlled by the pressure drop over the filter element - opening a pump by-pass 11 so that the pressure in the primary circulation drops, and impurities deposited in the filter loosen and are washed away by the oil in the primary circulation when the valve 1 is closed again.
• An ultrasound-transducer (not shown in Figure 1), the vibration surface of which forms a limitation surface for the flat cross flow of oil along the filter element 7, cooperates in preventing formation of a filter pulp at the surface of the filter element 7.
• a draining valve 2 in the primary circulation is opened, and oil is either carried back to the buffer tank or is drained out to be cleaned. Oil may also be drained out during reflushing, the valves 1 and 2 in that case being open at the same time. If the pump P draws oil (e.g. diesel oil) which is so clean that no filtration is necessary, a valve 3 in a filter by-pass pipe 8 is kept open. The filter may then be examined or replaced, it being possible to cut it off from the rest of the fuel system by means of closing valves not shown. Frequently, several filters connected in parallel are used.
• oil e.g. diesel oil
• a difficulty of the described method consists in that the filter element used is spoiled rather quickly which is especially presumed to be owing to cavitation formations at that side of the filter element which faces the ultrasound-transducer, and to protracted actions to loosen the impurities in the filter.
• the filter element 7 in the housing 8 is mounted by means of guidings 9 in a way so as to be displaceable between the positions shown in Figures 2 and 3.
• the filter is in its normal working position where - as indicated by arrows - oil in the primary circulation flows in a cross flow over the filter element 7 from the inlet 4 to the outlet 5. Also as indicated by arrows, a fraction of the oil flows through the filter element 7 to the secondary outlet 6.
• FIG. 3 shows the filtration apparatus during cleaning of the filter element 7 by reflushing provoked by a pressure drop in the primary circulation or a pressure rise at the secondary side of the filter element 7.
• oil now flows back through the filter element 7 from the secondary side to the primary side thereof and in a direction towards the inlets 4 and the outlets 5.
• the filter element 7 is moved closed up to the vibration surface of the ultrasound-transducer T so that the flow velocity away from the primary side of the filter element 7 is high and, at the same time, the vibrations from the transducer T to the filter element 7 are very effective.
• the filter element 7 stands up excellently to the strong vibration influence thereby produced, which in connection with the increased flow velocity at the primary side of the filter has the effect that it is possible to obtain an effective cleaning in a very short time.
• the dependence of the cleaning effect on the distance between the filter element and the ultrasound-transducer is illustrated in the diagram of Figure 4 which is based on a series of experiments employing varying distance and ultrasound-effect.
• the embodiments of the filtration apparatus according to the invention schematically shown in Figures 2 and 3 comprise a stationary ultrasound transducer T at the primary side of the filter element, it will be understood that the transducer may also be arranged at the secondary side (discharge side) of the filter.
• the relative displacement between the filter element 7 and the transducer T may also be established by the transducer T being moved up to and away from the filter element 7 or by the transducer T as well as the filter element 7 being movable.
• the displacement may be produced by control signals from the control circuit for the pump P or the transducer T or possibly just mechanically as a result of the pressure drop in the primary circulation.

Landscapes

• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Cleaning By Liquid Or Steam (AREA)
• Filtration Of Liquid (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=6351571

Family Applications (1)

Country Status (4)

Cited By (8)

Families Citing this family (11)

Citations (2)

Family Cites Families (4)

• 1988
  • 1988-04-08 DE DE3811706A patent/DE3811706A1/de active Granted
• 1989
  • 1989-04-07 WO PCT/DK1989/000081 patent/WO1989009646A1/en not_active Ceased
  • 1989-04-07 AU AU34447/89A patent/AU3444789A/en not_active Abandoned
  • 1989-04-08 ES ES8901232A patent/ES2012710A6/es not_active Expired - Lifetime

Patent Citations (2)

Also Published As

Similar Documents

Legal Events