# US 4,394,261 A · System for controlling clarification of boiler feed water and the like

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- Number: US 4,394,261 A
- Document ID: US4394261A
- Status: Granted
- Kind: A
- Application number: 06/355,007
- Filed: 1982-03-05
- Granted: 1983-07-19
- Earliest claimed: 1982-03-05
- Assignees: Texaco Inc.
- Inventors: Henry D. Moser
- Web page: https://patentgrep.com/patent/US4394261A

## CPC

- C02F 5/02: Softening water by precipitation of the hardness
- C02F: TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE (separation in general B01D; special arrangements on waterborne vessels of installations for treating water, waste water or sewage, e.g. for producing fresh water, B63J; adding materials to water to prevent corrosion C23F; treating radioactively-contaminated liquids G21F9/04; regeneration of reactants for recirculation into processes, see the relevant places for the processes)

## Abstract

A water clarification system for boiler feed water and similar applications. It employs a settling tank and adds a chemical to the inlet stream for causing precipitation of suspended matter. Clarified water is drawn off at an outlet near the surface. The system includes a sludge draw-off line with a valve for regulating the amount drawn. And, there is a small sized connection out from the tank at a desired level above the bottom, which is for drawing a continuous sample. Also, there is a back flush connection from the inlet stream into the sludge draw-off. Timing controls are applied to the sludge draw-off for periodically opening the valve if the sample indicates turbidity. Otherwise, the draw-off cycles are omitted. And, there is an override back flush cycle which is timed for keeping the sludge draw-off line clear.

## Claims

### Claim 1

In combination with a system for controlling clarification of boiler feed water and the like by precipitation, said system comprising
a settling tank having an inlet and an outlet for said water,
means for adding a chemical to said inlet water to cause said precipitation,
a drain line and first valve means for drawing off precipitate from the bottom of said tank,
a small sampling line connected into said tank at a predetermined level above the bottom of said tank for continuously sampling water from said tank,
means for continuously measuring turbidity of said sampled water, comprising
a switch having a closed position if said turbidity exceeds a predetermined minimum and an open position if not, and
means for backwashing said precipitate draw-off, comprising
a second valve means for controlling flow through a connecting line between said inlet water and said drain line while said first valve means is closed,
timing and control means for checking said turbidity at first predetermined intervals and for activating said first valve means for second predetermined intervals if said turbidity exceeds a predetermined minimum and for activating said second valve means with disabling of said first valve means at third predetermined regular intervals,
said timing and control means comprising
first timing means for opening said first valve means for said second predetermined intervals,
first circuit means for connecting said turbidity switch to said first timing means for activating said first timing means only when said turbidity exceeds said predetermined minimum
second timing means for checking said turbidity at said first predetermined intervals,
second circuit means for connecting said second timing means to said first timing means for activating said second timing means whenever said turbidity switch is closed, and
third timing means for opening said second valve means at said third predetermined regular intervals.

### Claim 2 (depends on 1)

The invention according to claim 1, wherein
said means for backwashing also comprises third circuit means for disabling said first valve means during said third predetermined regular intervals.