Tests have shown that when the shower water is about 122°F [50°C] the detergents and microbicides dispersants are most effective. This is true whether the washing system is continuous, intermittent or whether felts are washed during shutdown periods. It’s essential that felts be kept as clean as possible to not only prolong their life, but more importantly, to maintain paper machine production speeds and minimize downtime.
There are no frills in this felt washing water heating system. It was designed to give dependable service, quicker response and assure delivery of heated water at the temperature desired. Felt cleaning schedules never need to be worked around any warm-up periods or shutdown delays. Heating starts instantly and stops instantly. At the same time, it is completely safe because raw steam never contacts the felt. Water must be flowing through the flow switch before the steam supply is turned ‘on.’ The steam supply valve is closed immediately should therebe an interruption in water flow.
An automatic Hydroheater is the heart of the system. It quietly heats the water while it modulates the steam flow. High velocity steam produces the turbulence for instantaneous heating and prevents scaling of internal surfaces. The two-response temperature controller senses the heated water temperature just downstream of the automatic Hydroheater and provides the output pressure for precise control. The other two items in this system, one flow switch and one solenoid operated steam valve, work together to prevent any steam from coming in contact with the felt. As soon as water flows through the flow switch, its circuit is closed, energizing the steam solenoid. Only then does steam flow to the automatic Hydroheater.
Many paper mills are using this low cost controlled felt washing water heater system with automatic Hydroheaters. Some of them have been in operation for 10 or 15 years without any major maintenance or parts replacement. When this system is used, felt washing water heating problems will be solved.
Fluid: Flow Rate: Inlet Temperature: Discharge Temperature: Steam Supply Pressure:
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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.
SOLUTION
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.
GOAL
• Achieve optimal temperature control
• Eliminate fiber degradation and scaling
• Reduce chemical usage
• Minimize boilout routine
ACCOMPLISHMENTS
• Achieved instantanous condensation and homogeneous heating
• Eliminated product degradation and scaling
• Reduced chemical usage and saves thousands per month
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Fluid: Flow Rate: Inlet Temperature: Discharge Temperature: Fluid Supply Pressure: Steam Supply Pressure: Steam Superheat: |
Mead Paper in Kingsport, Tennessee, USA, needed to eliminate severe vibration and hammering caused by an existing black liquor heater on gun loop to the recovery boiler.
The previously installed direct contact steam heater was a one-of-akind, simple in-line sparging device. Because of inadequate condensing capabilities and external control of mass steam flow rate, unstable heating and rough operation caused damage to associated piping and fittings. This is not an uncommon problem when heating heavy black liquor with an improperly designed direct contact steam heater.
SOLUTION
Hydro-Thermal engineers chose the K412AS Hydroheater® installed prior to the gun loop on the recovery boiler. The Hydroheater heats black liquor to the optimum temperature to maintain proper nozzle pattern and droplet size for maximum burn efficiency. The Hydroheater was designed for severe service liquor heating and eliminates the problems of hammering and fouling.
Mead is experiencing smooth, quiet and stable operation. The severe vibration problem was eliminated. The temperature of the black liquor is precisely controlled at 250°F [121°C]. After the Hydroheater had been installed for more than six months, no downtime for maintenance or cleaning had been necessary.
GOAL
• Eliminate severe vibration and hammer
• Regulate condensing capabilities
• Reduce maintenance and equipment damage
ACCOMPLISHMENTS
• Eliminated hammering and fouling
• Optimal temperature control
• Achieved stable operation
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.
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A major pulp and paper company needed to unload rail cars filled with sodium chlorate using tempered water to dissolve the NaClO3 and create the proper solution strength. They use an elemental chlorine-free process for bleaching in their pulp mills. Traditional ECF replaces elemental chlorine with chlorine dioxide in the bleaching process.
10-20% of the product can remain undissolved in railcars and then returned to the chemical manufacturer if the water is not at the proper temperature. This company wanted to improve their railcar unloading process by eliminating loss of product due to inconsistent temperature control. They also had to maintain safety restrictions derived from the highly corrosive and hazardous material.
SOLUTION
The solution was to use a K414AS series Hydroheater® with a 316 body, 2205 duplex head (high nickel alloy) and a titanium stem plug. It now dissolves the NaClO3 with precise and consistent 190°F hot water. The Hydroheater replaced competitive direct steam injection heaters that cost significantly more to maintain due to the entire unit being unnecessarily cast in titanium.
A railcar carries $50,000-$60,000 of NaClO3. This pulp mill goes through 1 railcar/day and they have been saving an estimated 10% of $50,000 ($5,000) a day, or $30,000 a week. With the cost of the K414AS, they averaged a two-week Return on Investment (ROI).
Hydro-Thermal’s direct steam injection products can help you get a larger ROI. Our jet cookers can help achieve precise temp controls & eliminate your sodium chlorate loss. Fill out a request for a jet cooker quote forum to improve your railcar unloading ROI today.
GOAL
• Precise temperature control
• Eliminate product loss
• Improve workplace safety
ACCOMPLISHMENTS
• Precise temperature control
• Reduced maintenance time and costs
• Eliminated product loss
• Improved safety
• Two week ROI
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.
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A former Nekoosa Packaging Corporation in Valdosta, Georgia, USA, needed to eliminate hammering and scaling problems exhibited by existing green liquor heater.
Nekoosa has been using an externally modulated direct contact steam heater, mass steam flow rate was controlled by varying the pressure of the steam with an external control valve. The resulting pressure variations of the steam resulted in a reduced range of stable operation. When the heater was operating outside the limited range of stability, the heater exhibited severe hammering and vibration with consequent damage to internal components.
Hydro-Thermal engineers installed the K414AN Hydroheater prior to the slaker in order to precisely control temperature and maximize the conversion efficiency of slaked lime.
Installed in 1989, the mill reported that all hammering and vibration had been eliminated. The temperature of the green liquor had been precisely maintained at 190°F [87.8°C], and the Hydroheater has operated without scaling or fouling.
Update: Regular maintenance can provide years of service even in a corrosive environment. The mill carries a spare heater for easy swapout and uses a 2-3 year rebuild schedule to replace internal wear components. The current heater is on the fourth rebuild and has been in operation for 12 years.
• Eliminate hammering and scaling
• Achieve stable operation
• Reduce maintenance
• Consistent stable operation
• Eliminated scaling and hammer
• Heater has been in operation for 12 years
To learn more related to this case study, head over to our pulp & paper pages to get more information on everything related. Discover similar processes within those industries and be able to find more solutions for common industry heating issues.
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.
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!
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