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For every application, there's an evaporator or dryer that can boost performance
n today's economy, chemical processors must deliver high product quality and uniformity while maintaining high yield and low production costs in order to be successful. For this reason, they depend upon efficient continuous evaporation and drying processes for the production of high-quality products with specific product parameters. There's a plethora of evaporation and drying equipment engineered to meet the needs of the chemical process industries (CPI), in the most cost-effective, process-efficient and energy-saving way possible.
Advances in evaporation
The ideal choice of evaporation technology depends upon factors such as viscosity and the thermal characteristics of the product, the required output rate and the available energy supply, according to Niels Knudsen, sales manager, Flow Food and Beverage, SPX Flow Technology (Soborg, Denmark; www.spx. com). Evaporation techniques include single pass or circulation, single or multiple effect and thermal or mechanical vapor recompression, he says. The proper evaporator must be selected for the product being processed, as well as for the specific challenges associated with that product or process.
"For example, for concentration of low- to medium-viscosity organic and inorganic products, falling film evaporation is widely applied," he says. "SPX's Anhydro brand falling film evaporators deliver low energy consumption, high heat-transfer coefficients and a single-pass evaporation that yields a short residence time for minimum impact on product quality."
In addition to direct steam heating, Anhydro falling film evaporators apply two vapor-recompression techniques to minimize the energy consumption: mechanical vapor recompression (MVR) and thermal vapor recompression (TVR). MVR requires little or no steam and delivers substantial operational cost savings in areas with an ample supply of lowcost electricity. For TVR, multi-effect evaporation uses vapor from one effect as the heating medium in a subsequent effect, thereby operating at a lower pressure and temperature.
For difficult and demanding tasks in the fields of distillation, concentration and degassing, thin-film evaporators can be applied, says Rainer Fabricius, sales manager with Buss-SMS-Canzler (Düren, Germany; www. sms-vt.com). Gentle handling of the product using short residence time and high evaporation ratios in a single pass, as well as minimal loss during product change due to low holdup, make them ideal for these applications. In addition, the availability of different rotor types, vertical...