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Recycled fiber stock using direct steam injection

11% Recycled Fiber Stock

Flow Rate:
140-225 GPM [38-61 m³/hr]

Inlet Temperature:
Approx. 105°F [41°C]

Discharge Temperature:
125°F [52°C]

Steam Supply Pressure:
Varies; 92-110 PSIG [6.3-7.6 barg]





Recycled Fiber Stock

A major paper products manufacturer needed to heat recycled fiber stock to optimal bleaching temperature. Sparging steam into their fiber line through a small number of injection points, this recycled mill struggled with uneven heating of its recycled fiber stock. Inconsistent heating resulted in inefficient bleaching. “Hot spots” contributed to fiber degradation and excessive scaling, compromising stock yield and quality and necessitating quarterly acid boilouts. Process engineers sought to more precisely add heat to the bleaching process, reducing the amount of bleaching chemicals required and minimizing the boilout routine.


Designed specifically to heat medium consistency pulp stock, a Solaris® Hydroheater was installed and delivered immediate process improvements. The device features patented Mach™ diffuser technology, in which a rotary choked flow steam diffuser discharges steam into stock through hundreds of injection points at very high, often sonic, velocity. The high degree of surface contact between steam and stock and the turbulent nature of the steam discharge ensures instantaneous condensation and homogeneous heating.

Solaris’ ability to heat stock uniformly has solved the fiber degradation problem. Process engineers report that increasing the temperature of the bleaching process is saving the mill thousands of dollars in chemical costs each month. The drop in chemical usage has also resulted in a significant reduction in volatile emissions. Scaling has been minimized and the mill plans to cut back to a yearly, rather than quarterly, boilout. Plant personnel are now investigating other applications for the Solaris within the mill.


• Achieve optimal temperature control
• Eliminate fiber degradation and scaling
• Reduce chemical usage
• Minimize boilout routine


• Achieved instantanous condensation and homogeneous heating
• Eliminated product degradation and scaling
• Reduced chemical usage and saves thousands per month


Are you curious about our patented direct steam injection technology? Click here to learn more.

Are you wondering what applications are ideal for direct steam injection? See the Where It Works section for the a list of industries.

Do you want to learn more about our products? Click here for more information.

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Hydro-Thermal is the global leader in the development and manufacturing of Hydroheaters. Through our vast global channel partners, we support hydro heating in six continents and all industrialized areas. We create heating systems for a variety of industries including: pulp, paper, chemical, ethanol, food & beverage, metal, & more!

Hydro-Thermal Corporation 

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