Thin Stock Screening

SKU: C-722Duration: 24 Minutes Certificate Included

Pay-per-view (PPV) format perfect for individual users.

Get immediate access to this interactive eLearning course online. Must be used within 30 days, expires 48 hours after launch.

Language:  English

Great for in-person classroom training or as an alternative to DVD.

Includes printable documents and Convergence Video Player for Windows systems. Content expires after 1 year.

Language:  English

Ideal for corporate licensing and volume users who also need administrative tracking and reporting on training.

Get this interactive eLearning course into your LMS or learn how you can leverage our LMS to deliver training to your workforce.

Need multiple courses or have lots of users? Just let us know a little more about what you need and we’ll get you some great volume pricing.

 Need help deciding? Compare delivery formats.

Course Details

Specs

Training Time: 24 minutes

Compatibility: Desktop, Tablet, Phone

Based on: Industry Standards and Best Practices

Languages: English

The purpose of thin stock screening is to remove debris from the dilute stock going to the headbox. Screening also deflocculates the stock and protects downstream equipment. Screening systems often use two or three "cascaded" stages in order to reduce fiber losses and improve overall debris removal efficiency. The design and operation of a screening system must take into account the requirements of the paper or board machine, desired sheet quality and properties, and characteristics of the particles to be removed.

Learning Objectives

At the end of this module, you will be able to:

  • Identify the purposes of thin stock screening
  • Identify the types of debris found in mechanical pulps, chemical pulps, and secondary fiber
  • Identify the components and describe the operation of a vibratory flat screen
  • Identify the components and describe the operation of pressure screens
  • Explain why pressure screen holes and slots are tapered or relieved
  • Identify and describe primary process flows
  • Define "reject rate," "debris removal efficiency," and "long fiber removal efficiency"
  • Describe the operations of cascaded screening systems

Key Questions

The following key questions are answered in this module:

What is the purpose of thin stock screening?
Screening removes dirt, small pieces of plastic, wood and other contaminants. It also helps break up fiber clumps.

What are disadvantages of vibratory flat screens?
Vibratory screens have high maintenance and foaming issues.

How are pressure screen basket openings created?
The baskets can have drilled holes, milled slots, or welded wedge wire.

What are typical screen opening sizes?
In thin stock systems, hole sizes range from about 1.2 to 3 mm (0.05-0.12 inch), with an open area of 10 to 25%. Slot widths vary from about 0.2 to 0.5 mm (0.008-0.02 inch), and open area is generally 7 to 15%.

What debris properties affect removal efficiency?
Large, 3D particles are easiest to remove. 2D debris, such as wet strength flakes, can be removed, but some orientations pass through the baskets easily. Small contaminants like shives are most difficult to remove by screens.

Sample Video Transcript

Below is a transcript of the video sample provided for this module:

Pressure screens consist of a vertical or horizontal screen housing that contains one or two perforated cylindrical screen baskets and a shaft driven rotor. Foils or bumps on the rotor travel in close proximity to the screen surface and help force fibers through the openings, and then create a low pressure pulse as they pass by. The momentary back flush action of the pulse prevents materials from building up and plugging or blinding the screen. Between pulses, the pressure from the feed pump keeps fibers and water moving through the openings. The material that passes through becomes the accepts, which exit from the side of the screen housing. The material which cannot pass through the openings is discharged as rejects near the bottom of the housing.

Customer Q&A

Ask a Question

Sorry, we're missing some information

I would like to have several employees take multiple courses. How can I set that up?

We're in the process of making bulk course and multiple user purchases easier. But for now, you can order multiple courses and contact us with details on who you'd like to assign courses to. We can set up each user's training plan and make sure everyone gets the eLearning assignments they need.

Can I get a free full-length preview of a course to see what this course covers?

While we do our best to offer details on course contents, we don't normally offer full-length previews. But please contact us with more details for a better understanding of what your organizaton needs and how we can help.

Do I get a certificate when I complete a course?

Yes. All of our courses allow you to print a completion certficate upon successfully passing the integrated test at the end of each eLearning course.

How do I log in to take a course that I have already paid for?

You'll receive an email with login details moments after you purchase your pay-per-view (PPV) course. Just click the login link and enter the user name and password provided.

Do you have courses in different languages?

Yes. While all of our courses are originally produced in English, we develop many courses in a growing number of languages, including Chinese, Dutch, German, Italian, Japanese, Korean, Polish, Portuguese, Russian, Spanish, Tamil, and Thai. Available languages are normally displayed in the Course Details section on each course page.
Added to Cart! Click here to view your cart.