Turbidimeter system reduces fuel and water costs, eliminates need for pollution control capital equipment

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Model AP-VIE Controller for Heat Exchange Use

Problem

To comply with clean-water regulations, a wood products company needed to reduce or eliminate the condensate contained in its discharged effluent streams.

To preclude the possibility of creosote, oil or other wood preservatives getting into its boilers when the heating coils developed leaks, a manufacturer of pressure-treated wood poles, pilings, cross-ties, timbers and lumber products formerly would discharge all of its condensate with other effluent into the rivers and streams around the company 5 eight plants in the southeastern United States.

Newly enacted water quality standards now prohibited this practice. In an effort to avoid costly treatment and disposal of the condensate, the company determined the most cost-effective solution would be to recycle the condensate and not discharge it.

Solution

A turbidity monitoring system was installed to monitor the condensate for impurities before returning it to the boilers.

To facilitate condensate recycling, the company considered several methods of monitoring the condensate for oil. Company management determined the turbidity alarm method, which was inexpensive and easy to install, adjust and maintain, was the best solution.

The turbidity alarm system includes a light source and a photo-electric scanner mounted on opposite sides of a flow cell placed in the condensate return line to the deaerator. The scanner detects increases in turbidity caused by impurities in the condensate by measuring the differences in light it receives from the light source.

Electronic signals from the scanner are transmitted to a metal control cabinet housing indicator lamps and relay.

A92-36_equipment.JPG (37914 bytes)The amount of transmitted light reaching the scanner lessens as the turbidity of the condensate increases. When the turbidity has increased to the point where the condensate can no longer be considered safe for use in the boiler feedwater system, the relay within the cabinet signals an alarm, turns on a red light and opens a three-way valve to divert the condensate to the waste water treatment system. When turbidity levels are sufficiently lowered, the relay closes the valve and the system returns to normal operating conditions.

The installation of the turbidimeter provided many benefits to the company. Boiler fuel and water consumption was lessened and make-up water costs were reduced. Further, the recycling of the condensate precluded the need for capital-intensive pollution control systems, as the previously discarded condensate formerly was a major part of the company's discharged wastewater.

Model AP-VIE

The Model AP-VIE does not require an additional box, but has alarm controls and isolated 4-20mA outputs.  Request A89-50 flyer for additional information.

Questions? Contact McNab

A92-36C
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