Screw Press | Vincent Corp

March 10, 2013

Liquids are separated from solids in two common manners: settling or squeezing. The primary device used for the settling mechanism is the centrifuge, and the primary device used for the squeezing mechanism is the screw press.

Settling results from the action of gravity. Solids can be separated from liquids by letting the mixture sit in a settling pond, tank, Imhoff cone, etc. The effect of gravity can be accelerated and multiplied by spinning the fluid in a centrifuge. Centrifuges are used in a very wide range of industrial applications. In fact, they are far more common than screw presses.

Materials can be squeezed by forcing them against a screen or another filter media. An example of this is old-fashioned wine presses, dating back to Roman times: grapes are placed over a screen fastened at the bottom of a vertical cylinder, and a piston forces down on the grapes to expel the juice through the holes in the screen.

This method has its drawbacks, primarily because pressing is done in batches rather than continuously. Additionally, a thick cake can form at the bottom against the screen, making it difficult for fluid at the top, next to the piston, to flow through this cake and the screen.

Modern screw presses address these disadvantages by surrounding the screw with a screened surface, transforming the cylinder walls into a screened surface. Rather than using a piston, material is conveyed toward the discharge by a helicoid screw.

The helicoid screw, credited to Archimedes for its invention, functions much like a corkscrew. It consists of a shaft around which a spiral steel plate is wound. This design is utilized in various screw presses. In some cases, the barrels surrounding the screw have no openings, thus the mechanism does not separate liquids from solids. For instance, plastic injection molding machines and cooker-extruders for snack foods operate on this principle.

On the other hand, some screw presses are tasked with removing free water from fibrous material, while others, known as Expellers®, exert extremely high pressures to extract oil from seeds like soybeans, peanuts, and canola. The internal pressure is intense enough to convert fat into liquid oil, which flows through the screen cage openings surrounding the screw.

The contemporary screw presses, especially the broken flight design patented by Valerius Anderson in 1900, feature flights with interruptions that minimize co-rotation. Compression is achieved through graduated pitch compression stages and tapering the screw’s shaft diameter to force material against the screen. Discharge moisture control is facilitated by a discharge cone actuated by an air cylinder, allowing easy dewatering adjustments. Additional features can include perforated or wedgewire screens and supplementary screen surfaces in specific parts of the machine.

In larger machines, foot-mounted gearboxes are commonly used, while smaller presses may use hollow-shaft gearboxes. Most modern presses are driven by electric motors, with hydraulic motor drives being less favored due to the advent of reliable, cost-effective variable frequency drives (inverter VFDs).

Dilute materials can be pumped directly into the screw press, although pre-thickening with devices like static screens or gravity tables often improves performance. Vapor-tight presses cater to specialized needs, such as the production of soybean protein concentrate and bioresin, while twin-screw presses, featuring synchronized compression screws and internal shredding action, are ideal for slippery and fibrous materials.

All modern screw presses feature horizontal screws, with vertical designs from the 1800s to the 1950s now obsolete. Laboratory and pilot plant models remain popular for various testing purposes.

For more information, please visit oil seeds crushing machine.

SMALL PRESS, NO SCREEN COVER

PRESS LIQUOR FROM SCREEN

ALFALFA PRESS, SCREEN REMOVED

PRESS WITH SCREENS REMOVED

FOOT MOUNTED GEARBOX DESIGN

PRESS CAKE DISCHARGE

Photos and drawings provided by Vincent Corporation.

Issue 254

In today’s rapidly evolving industrial landscape, businesses are continually seeking innovative solutions to optimize their processes, reduce waste, and enhance sustainability. At French Oil, we take pride in our commitment to delivering cutting-edge technologies that meet our clients’ diverse needs. One such area where our expertise shines, specifically, is in custom screw press dewatering systems.

The Design

At French, our engineers have developed screw press and fiber press designs renowned for their long-lasting durability and decades of exceptional performance. Featuring advanced technology that ensures accurate regulation of discharge moisture, our range includes custom-designed dewatering presses for both virgin and recycled wood pulp. Moreover, you can select from a variety of drive and control systems to find the perfect fit for your specific needs, and our team of skilled French engineers is readily available to guide you in making the optimal choice.

Pulp Dewatering Systems

The French series of LP (low-pressure) pulp dewatering presses are also meticulously designed to deliver unparalleled control over discharge moisture to excel in efficiently separating liquids and solids from moisture-laden fibrous materials. Furthermore, by operating with a feed consistency ranging from 2% to 4% and discharging at 25% to 35%, these presses are available in four primary models: LP-1890, LP-18120, LP-28150, and LP-28200, offering a daily capacity range from 50 to 300 bone-dry metric tons. Select the perfect model that aligns with your application requirements and experience the remarkable engineering prowess of French technology in action.

Screw Press Applications:

Here is a compilation of the most prevalent applications where our premium, tailor-made screw press dewatering systems excel:

Pulp Washing and Bleaching:

The paper industry relies heavily on efficient pulp washing and bleaching processes to produce high-quality paper products. That’s why our custom screw press designs are adept at extracting water and chemicals from pulp, resulting in a cleaner and more refined material. This not only improves the quality of the final paper but also helps in reducing chemical usage and water consumption, making your paper production process more sustainable.

Paper Recycling and De-Inking Operations:

As the world embraces sustainability and environmental consciousness, the demand for recycled paper is on the rise. Our screw presses, for instance, play a crucial role in paper recycling and de-inking operations, as they effectively remove ink, contaminants, and excess water from the recycled paper pulp. By partnering with French Oil for these processes, your paper recycling plant can significantly reduce water usage and energy consumption, contributing to a greener future.

High Consistency Refining of Primary Pulp and Rejects:

Optimizing paper production relies heavily on efficiently refining primary pulp and rejects. That’s why our team of experts engineers our custom screw press designs to handle high-consistency refining effortlessly. By precisely extracting water and fiber from the material, our presses improve the refining process’s efficiency, leading to higher-quality paper products and reduced waste.

Liquid Removal before Pulp Storage and Transport:

To ensure smooth storage and transportation of pulp, it is essential to remove excess liquids effectively. So, our screw press applications excel at precisely this task, reducing the moisture content in pulp to the desired level before storage or transport. This not only improves the handling of pulp but also minimizes the environmental impact of the entire process.

Concentration of Waste Treatment Sludges:

Waste treatment sludges can pose significant challenges to industries, both economically and environmentally. Fortunately, our screw press designs offer an effective solution for concentrating waste treatment sludges. By reducing the moisture content, the volume of waste is minimized, which leads to easier disposal and potential resource recovery.

Excess Water Removal from Various Materials:

Apart from paper-related applications, our screw press designs are versatile enough to handle excess water removal from various materials like corn fiber, corn germ, alfalfa, and more. Furthermore, the ability to efficiently extract moisture from these materials opens up opportunities for multiple industries, including agriculture and biofuel production.

Request A Quote Today

At French Oil, we understand that every industry has unique processing requirements. Our commitment to customization ensures that our screw press dewatering systems can seamlessly integrate into your existing operations, enhancing efficiency, reducing waste, and promoting sustainability. Whether it’s paper manufacturing, recycling, or diverse applications like agricultural materials, we are your trusted partner in processing. Contact our team of experienced engineers to discover how our custom screw press designs can elevate your business to new heights of success!

If you want to learn more, please visit our website automatic screw press machine product.