Fluid filtration method and apparatus

Claim 2

In a filter unit for purifying liquid, having a filter tank, an inlet for passing liquid to be purified into the filter tank, an outlet for removing purified liquid from the filter tank, and a means for precoating filter elements within the tank with a precoat of particles of a filter medium, at least one improved tubular filter element positioned within the tank so that liquid to be purified enters the outer area of the filter element during a service cycle and passes longitudinally through the filter element to a discharge end of the filter element, comprising: a perforated tubular support member for supporting the precoat of filter medium particles; a tubular distributor core, concentrically located within said support member to define an annular space between said support member and said distributor core, having a plurality of apertures in the wall of said distributor core; and a plurality of dividers positioned axially along said distributor core within said annular space to prevent the unimpeded flow of liquid through said annular space, said dividers defining a plurality of annular chambers within said annular space, said annular chambers decreasing in length in a direction away from the service cycle discharge end of the filter element.

Claim 3

In a filter unit for purifying liquid, having a filter tank, an inlet for passing liquid to be purified into the filter tank, an outlet for removing purified liquid from the filter tank, and a means for precoating filter elements within the tank with a precoat including ion exchange resin particles in the size range of 60 to 400 mesh, at least one improved tubular filter element having a service cycle discharge end and positioned within the tank so that liquid to be purified enters the outer area of the filter element and passes longitudinally through the filter element to the discharge end of the filter element, comprising: a perforated tubular support member for supporting the filter medium precoat; a tubular distributor core, concentrically located within said support member to define an annular space between said support member and said distributor core, having a plurality of apertures in the wall of said distributor core; and a plurality of dividers positioned axially along said distributor core within said annular space to prevent the umimpeded flow of liquid through said annular space, said dividers defining a plurality of annular chambers within said annular space, said annular chambers decreasing in length in a direction away from the service cycle discharge end of the filter element.

Claim 4

In a filter unit for purifying liquid, having a filter tank, an inlet for passing liquid to be purified into the filter tank, an outlet for removing purified liquid from the filter tank, and a means for precoating filter elements within the tank with a precoat including ion exchange resin particles in the size range of 60 to 400 mesh, at least one improved tubular filter element having a service cycle discharge end and positioned within the tank so that liquid to be purified enters the outer area of the filter element and passes longitudinally through the filter element to the discharge end of the filter element, comprising: a perforated tubular support member for supporting the filter medium precoat; a tubular distributor core, concentrically located within said support member to define an annular space between said support member and said distributor core, having a plurality of apertures in the wall of said distributor core; and a plurality of dividers positioned axially along said distributor core within said annular space to prevent the umimpeded flow of liquid through said annular space, said dividers defining a plurality of annular chambers within said annular space, said annular chambers decreasing in length in a direction away from the service cycle discharge end of the filter element.

Claim 6

In a filter unit for purifying liquid, having a filter tank, an inlet for passing liquid to be purified into the filter tank, an outlet for removing purified liquid from the filter tank, and a means for precoating filter elements within the tank with a precoat of particles of a filter medium, at least one tubular filter element positioned within the tank so that liquid to be purified enters the outer area of the filter element during a service cycle and passes longitudinally through the filter element to a discharge end of the filter element, comprising: a perforated tubular support member for supporting the filter medium particles; a tubular distributor core, concentrically located within said support member to define an annular space between said support member and said distributor core, having a plurality of apertures in the wall of said distributor core; and means positioned axially along said distributor core within said annular space for preventing the unimpeded flow of liquid longitudinally through said annular space and for defining a plurality of annular chambers within said annular space, said annular chambers decreasing in length in a direction away from the service cycle discharge end of the filter element, the length of the annular chamber adjacent the discharge end being approximately 1.6 times the length of the annular chamber furthest away from the discharge end.

Claim 7

In a filter unit for purifying liquid, having a filter tank, an inlet for passing liquid to be purified into the filter tank, an outlet for removing purified liquid from the filter tank, and a means for precoating filter elements within the tank with a precoat of particles of a filter medium, at least one tubular filter element positioned within the tank so that liquid to be purified enters the outer area of the filter element during a service cycle and passes longitudinally through the filter element to a discharge end of the filter element, comprising: a perforated tubular support member for supporting the filter medium particles; a tubular distributor core, concentrically located within said support member to define an annular space between said support member and said distributor core, having a plurality of apertures in the wall of said distributor core; and means positioned axially along said distributor core within said annular space for preventing the unimpeded flow of liquid longitudinally through said annular space and for defining a plurality of annular chambers within said annular space, said annular chambers decreasing in length in a direction away from the service cycle discharge end of the filter element, the length of the annular chamber adjacent the discharge end being approximately 1.6 times the length of the annular chamber furthest away from the discharge end.

Claim 10

The apparatus of claim 6 wherein the ratios of the length of each annular chamber to the length of the annular chamber closest to the discharge end are, in a direction away from the discharge end, approximately 1.17, 1.37, and 1.6 respectively.

Claim 13

The method of claim 8 further comprising the step of increasing the diameter of the apertures along the longitudinal axis of the filter element in a direction away from the service cycle discharge end of the element.

Claim 14

The method of claim 8 wherein the length of the annular chamber adjacent the discharge end is approximately 1.6 times the length of the annular chamber adjacent the discharge end.