US 5,980,755 A · Methods and apparatus for monitoring a filter bed by differential pressure

Abstract

A differential pressure monitor measures the pressure at a plurality of heights in a filter bed. A preferred embodiment of the monitor comprises an elongated body, a plurality of pressure sensors located on the elongated body for obtaining the pressure readings, a control means for determining differential pressures from the pressure readings, each differential pressure being the difference in pressure between pressures measured at two different heights in the filter bed, and transmission means to transmit the pressure readings from the pressure sensors to the control means. Methods of monitoring and controlling the performance of a filter bed during filtration and during backwashing also are provided. Two such methods include measuring turbidity levels in a filter bed and obtaining water samples from a filter bed.

Claims33

Dependent claims

A filter bed for a liquid filtration system comprising:

(a) an underdrain;
(b) at least one layer of filter media situated on top of said underdrain;
(c) control means located outside the filter bed for determining pressure differentials from a plurality of pressure readings;
and
(d) a differential pressure monitor located within the filter bed for measuring pressure at a plurality of heights in the filter bed, the monitor comprising:
an elongated body having an upper end, a lower end, and a sidewall defining an inner cavity, the elongated body having a generally uniform cross section;
a plurality of pressure sensors located on the elongated body for obtaining pressure readings at a plurality of corresponding heights across said at least one layer of filter media wherein the monitor is at least partially submerged in the filter media;
and
transmission means to transmit the pressure readings from said pressure sensors to said control means.

6 more elements

A method of measuring at least one pressure reading at at least one location in a filter bed in a liquid filtration system, the filter bed having at least one layer of filter media and an upper surface at the top of the layer of filter media, the method comprising the steps of:

(a) providing a differential pressure monitor comprising:
an elongated body having an upper end, a lower end, and a sidewall defining an inner cavity;
at least one pressure sensor located on the elongated body for obtaining at least one pressure reading at at least one location in the filter bed;
(b) placing the differential pressure monitor in the filter bed by positioning the monitor down through the upper surface of the filter bed and into the filter media;
and
(c) measuring at least one pressure reading at at least one location within the filter media in the filter bed with the differential pressure monitor.

3 more elements

A method of monitoring and controlling performance of a filter bed in a liquid filtration system during filtration to achieve more efficient backwashing and filtration operation, the filter bed having two layers of filter media and an upper surface at the top of an upper layer of the two layers of filter media, the method comprising the steps of:

(a) providing a control means for determining a pressure differential from a plurality of pressure readings;
(b) providing a differential pressure monitor comprising:
an elongated body having an upper end, a lower end, and a sidewall defining an inner cavity;
three pressure sensors for obtaining pressure readings at three corresponding locations during filtration, the three locations being:
(1) at a distance adjacent to and vertically above the upper layer of filter media in the liquid filtration system so as to measure the pressure at the upper surface of the upper layer of filter media, the pressure at this location being p1;
(2) at an interface of the upper layer of filter media and a lower layer of the two layers of filter media, the pressure at this location being p2;
and
(3) at a point proximate a bottom surface of the lower layer of filter media, the pressure at this location being p3;
and
transmission means to transmit the pressure readings from the pressure sensors to the control means, wherein the differential pressure is the difference in pressure between pressures measured at two different heights;
(c) starting filtration by introducing influent to the liquid filtration system at a location vertically above the upper surface of the upper layer of filter media;
(d) monitoring pressure readings p1, p2, and p3 at periodic intervals and recording such measurements on the control means to obtain a characteristic profile of the filter bed during filtration, wherein no part of the control means or the monitor passes through walls of the liquid filtration system.

9 more elements

A method of monitoring and controlling performance of a filter bed in a liquid filtration system during backwashing to achieve more efficient backwashing and filtration operation, the filter bed having two layers of filter media, an upper surface at an upper layer of filter media, a lower surface at a lower layer of filter media, and a bottom surface, the method comprising the steps of:

(a) providing a control means for determining a pressure differential from a plurality of pressure readings;
(b) providing a differential pressure monitor comprising:
an elongated body having an upper end, a lower end, and a sidewall defining an inner cavity;
three pressure sensors for obtaining pressure readings at three corresponding locations during backwashing, the three locations being:
(1) at a distance adjacent to and vertically above the upper layer of filter media so as to measure the pressure at the upper surface of the upper layer of filter media, the pressure at this location being p1;
(2) at an interface of the upper layer of filter media and the lower layer of filter media, the pressure at this location being p2;
and
(3) at a point proximate the lower surface of the lower layer of filter media, the pressure at this location being p3;
and
transmission means to transmit the pressure readings from the pressure sensors to the control means, wherein the differential pressure is the difference in pressure between pressures measured at two different heights;
(c) pumping water in an upward direction in through the bottom surface of the filter bed and through the filter bed at a relatively slow rate of flow;
(d) gradually increasing the rate of flow of water being pumped into the liquid filtration system;
(e) periodically measuring pressure readings p1, p2, and p3;
(f) recording the pressure readings on the control means to obtain a characteristic profile of the filter bed during backwashing;
and
(g) monitoring differential pressure p3-p1 to determine a backwash differential pressure and when it approaches a constant value, starting backwashing at the rate of water flow being pumped into the liquid filtration system to achieve the backwash differential pressure.

13 more elements

Dependencies are inferred from the claim text.

Methods and apparatus for monitoring a filter bed by differential pressure

Life of this patent

Methods and apparatus for monitoring a filter bed by differential pressure

Life of this patent

Abstract

Claims33