KWS Manufacturing

Polished Food-Grade Stainless Steel Screw Feeder for Metering Thickening Agent for Specialty Chemical Company

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Screw Feeders for Metering Thickening Agent: The Ashland Chemical CompanyPlant Name and Location

The Ashland Chemical Company
Hopewell, VA

General Description

The Ashland Chemical Company provides specialty chemicals for the pharmaceutical, healthcare, food, building, manufacturing, and automotive industries. Ashland Chemical has operations in more than 100 countries and provides innovative products and services that add value to products that people use every day. For this project, Ashland required several new screw feeders to meter Aqualon™ cellulose gum from dryer storage bins to rotary valves so it could be conveyed downstream pneumatically. Aqualon™ cellulose gum, or sodium carboxymethylcellulose (CMC), is widely used as an economical thickener and stabilizer in foods and beverages. Cellulose gum is useful in suspending solids and modifying the flow and texture of liquids. In beverage concentrates and powdered drink mixes, cellulose gum adds a pleasant, clean positive sensation in the mouth. KWS worked directly with Ashland Chemical and a third-party engineering firm to create a screw feeder design to meet all aspects of the application.

Design Parameters

  1. Product Type: Cellulose Gum or CMC (carboxymethyl cellulose)
  2. Material Density: 58 Lbs. per Cubic Foot
  3. Conveyor Capacity: 217 Cubic feet per Hour
  4. Duty: 24 Hours per Day, 7 Days per Week

KWS Advantages

Ashland had existing live bottom screw feeders in the Hopewell, VA plant as part of their process since the mid-1960s but wanted to improve efficiency and increase capacity. Ashland engaged a third-party engineering firm, Progressive Design, to provide engineering input to upgrade and refresh the process. Progressive Design needed an experienced screw conveyor manufacturer to design and build polished stainless steel screw feeders to meet the demands of the application. They were also seeking a partner with engineering knowledge to suggest improvements and help them with the design. KWS analyzed the existing problems and provided improvements in the screw feeder design. Since the cellulose gum is a food product, KWS recommended that all internal product-contact surfaces be polished to 180-grit finish with no pits or crevices. The shaft seals were also upgraded to a food-grade design and purged with nitrogen. KWS also recommended increasing the drive horsepower and torque to handle even the worst-case upset condition. KWS is the industry leader when providing solutions to difficult applications and excels in manufacturing food-grade stainless steel equipment. KWS engineers analyzed the original application and recommended a superior design.

Special Features

Ashland was concerned about unloading the storage bins properly and the food-grade requirements of the application. Each screw feeder was designed with increasing flight pitch along the length of the screw to allow the bin to unload evenly and prevent bridging and ratholing. The center pipe of the screw was oversized to support the head load of the material in the bin. All internal product contact areas were polished to 180-grit finish and food-grade lubricants were used in the bearings and gear reducers. Sanitary air-purged shaft seals kept the product contained within the screw feeder housings. The finish provided by KWS ensured completely crevice-free and cleanable product contact surfaces.


"Thanks for all the help addressing every detail of the project for us."

Jeff Marshall, Senior Process Engineer – Progressive Design


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