Introduction

Pneumatic transport systems are based on the principle of conveying fibrous and bulk materials through pipelines using air flow. A fan is an essential component of any pneumatic transport system.

History of Pneumatic Transport

The first pneumatic transport systems were developed in England in the 1890s for unloading grain from ships. In 1906, pneumatic transport was also introduced in the woodworking industry. Today, pneumatic transport is widely used in various industries, including woodworking, construction, agriculture, food processing, tobacco, tea, flour, various powders, cellulose, grains, hay, straw, cement, sand, lime, and chips.

Types of Fans

Various air supply machines are used to provide the necessary air volume and pressure for material transport: turbo blowers, compressors of various types, two-rotor rotary blowers, vacuum pumps, and fans.

Fans in Woodworking

Medium or high-pressure centrifugal fans are typically used in woodworking. Fans used in pneumatic transport systems can be classified into three types: dust, transport, and clean air fans.

Dust Fans

VP-type dust fans are the most widely used in woodworking. The design of these fans allows for the transport of bulk, non-sticky materials, including chips. The fan rotor typically consists of 6-8 blades. The efficiency coefficient does not exceed 67%.

Transport Fans

Transport fans typically have backward-curved blades and a V-belt drive. The fan housing appears narrow visually. Fans with a V-belt drive are recommended for use in systems with uneven material feed. This is to avoid excessive load on the electric motor bearings. This fan can provide high pressure and transport a large amount of material with a smaller amount of air. The permissible material concentration in the air is up to 0.5 kg/m³. Transport fans are typically used for extracting chips from filters, feeding chip storage bins, granulators, briquetting machines, and transporting chips over long distances.

Clean Air Fans

Clean air fans are typically used in pneumatic transport in vacuum suction systems. In this case, the material is not transported through the fan. These fans have rotors of various configurations; this depends on the application of the fan and the required power. These fans typically have a higher efficiency coefficient than dust fans, which in some cases can save up to 25% of electricity with a properly designed pneumatic transport system.

Selecting the Right Fan

To select the appropriate fan, it is important to know the volume of air to be extracted and the pressure that the fan must develop. Once these parameters have been determined, it is necessary to refer to the fan performance chart. The chart will allow you to select the most suitable fan for your parameters and the most energy-efficient fan. Each chart shows the fan’s performance efficiency percentage, or efficiency coefficient. If you look at the curve of the chart, the efficiency at the edges of the curve is lower than in the middle of the curve. The difference between the edge of the chart and the middle can be up to 20%, so the conclusion is that the more precisely you select the fan, the more you will save.

Choosing a Chip Extraction System

Chip filters, though simple-looking, are vital for woodworking. Picking the wrong system leads to problems. Cleaning clogged filters takes a full day, and frequent clogs cost manufacturers significantly. An experienced specialist can help you navigate filter options. Māris Puzurs, project manager for “Baltijas Koks,” offers advice.

Experience Matters

The company has manufactured and installed chip extraction systems for eight years. “We saw foreign manufacturers offering simple things we could make ourselves,” says Māris Puzurs. “We started with small air ducts and now produce fans and filters.”

High-Quality Solutions

In the past, the company gained experience working with various leading filter manufacturers. This knowledge allows them to offer high-quality solutions today.

Project Examples

The company’s longest project was a 170-meter chip feed system. Their largest project by volume is a chip feed system for a granulator in Liepāja. It has a capacity of 100 m3/h and uses only 22 kW. They’ve also installed many positive and negative pressure filter systems.

Filter Selection

Choosing a filter requires special care if you use high-speed planers, process light wood, or filter dust. Very light particles can easily clog the filter with even slight airflow.

Rotary Filters Explained

Rotary filters have filter bags, a conical chamber for chips, and a rotor sluice to remove them. These filters have a longer cone than others to prevent clogging. While this makes them slightly more expensive, it guarantees no blockages above the sluice. This makes them ideal for facilities with high-speed planers that create light dust particles.

Filter Size and Airflow

Each filter has a specific size based on its filtering area. This area can filter a certain volume of air. In woodworking aspiration systems, one square meter of filter area typically handles 100 m3/h. If the filter handles more air, the bags will clog faster and reduce their lifespan. This can also lead to more dust in the air, as the filtered air is usually returned to the workshop.

Website for Filter Information

To help you choose a filter, we created a website (mpp.lv) with information about our products. “Choosing the right solution is important,” says Māris Puzurs. “Some entrepreneurs buy used filters that cost more than new ones, simply because they lack information about pricing.

Recommended loads per square meter of filtering area: