Inline Moisture (MC) Softsensing and Control

The Delta T Moisture (MC) sensing & control model, derived from first principles,

relates the MC of a product exiting a dryer to the temperature drop (∆T) of hot after contacting the wet product and the production rate, evaporative load or dryer speed (S). The model produced the following exclusive technology:

• An inline MC SoftSensor consisting of two ordinary temperature sensors and software that is rugged, reliable, does not drift, can be installed “inside-a-dryer”, uses 100% of production as sample size, and does not require re-calibration.
• A new control algorithm that maintains the target MC with at least 30% less variation that that achieved by traditional sensing & control technology.
• An Evaporative Load Softsensor.

The above-described technology filled a niche that is proving quite profitable to those industries that have taken advantage of its ability to allow the sale of 0.5% to 1.0 % more water with the product without exceeding the upper specification limit (USL); significantly increase production by controlling to a higher mean MC without exceeding the USL; reduce unit energy consumption by 5 % to 10%,; and improve product quality by eliminating over and under-drying.

Applications

The Delta T MC Softsensor has been applied to various products such as food, pet food, textiles, non-wovens, minerals, building products, forest products, chemicals, corn gluten, dried distilled grains with solubles (DDGS), etc., using such dryer-types as flash, spray, belt, rotary, fluidized-bed, and batch dryers. Usually, the product MC standard deviation is reduced by at least 30% below that achieved by traditional MC sensing and control technology. In most cases, simple payback of investment is 3 – 6 months.

Extension of Delta T Technology

In addition to development of the MC SoftSensor from the Delta T model, it will be shown that four additional product properties can be sensed and controlled in terms of the same process variable, (∆T). These are water activity, relative humidity, product surface temperature, drying rate, and evaporative load. Descriptions of these SoftSensors may be reviewed by selecting SoftSensors on the Home Page selection bar.