Metering Hot Lime from Silo at International Paper Ticonderoga, NY

General Description

International Paper (IP) is a world leader in production of fiber-based packaging, pulp and paper. With more than 25,000 customers in 150 countries, IP supplies packaging products, pulp for diapers and tissues as well as paper products for print documents. The IP mill in Ticonderoga, NY produces high quality paper products for documents and everyday use.

Lime is used in the pulp making process to neutralize acids that dissolve glue (lignin) holding pulp fibers (cellulose) together. The lime and chemical solution is processed at high temperatures in kilns and reused in the process. Screw feeders and conveyors are used for handling lime products at temperatures up to 900-degrees F.

After an existing screw feeder and slide gate under a hot lime silo failed multiple times a year, IP contacted KWS for a long-term solution. The new slide gate and screw feeder had to withstand the extreme conditions of the pulp mill and designed to operate at all times. Ease of shutting off product flow from the silo and clean out was a necessity to reduce downtime.

Design Parameters

1. Product Type: Hot Lime
2. Material Density: 55 Lbs. per Cubic Foot
3. Design Temperature: 900-Degrees F
4. Capacity: 309 Cubic Feet per Hour
5. Duty: 24 hours per Day, 7 Days per Week

KWS Advantages

IP and KWS have an extensive successful history of working together to solve difficult bulk material handling problems. Downtime is not an option when dealing with hot lime, and KWS worked with IP engineers to integrate special features to ensure the equipment was designed to handle unexpected loads and upset conditions. KWS engineers also worked closely with engineers from Kaman to design the hydraulic power unit for the slide gates and fully test the system prior to installation.

Special Features

The new KWS slide gate and screw feeder were constructed using heavy-duty 304 stainless steel to withstand high temperatures of the hot lime stored in the hopper and occasional foreign objects that inevitably travel through the system. The screw feeder trough was equipped with a clean out port to allow maintenance operators to pull out foreign objects with ease. The drive unit produces extreme high torque to power through upset conditions. A KWS torque arm trough end allows the gear reducer to “float” while producing torque. The screw was mass-flow design to promote even withdrawal of material from the hopper and to meter hot lime at a controlled rate. KWS provided a slider base trough end on the tail end of the screw feeder to account for thermal expansion due to high heat.

The maintenance slide gate located between the hopper and screw feeder was hydraulicly actuated and produced over 10,000 lbs. of force for opening and closing. The gate frame was made of 3/8 and ¾-inch thick 304 stainless steel plate to handle the high hydraulic forces. A custom internal diverter was added to prevent crushing of hot lime by the gate blade during closing. High temperature seals prevent leakage when the slide gate is in the closed position.