High pressure saves resin and energy

15 March 2017


Imal-Pal, the major Italian machinery producer, has been the co-ordinating partner in an EU-funded co-operation working on systems to reduce the amount of resin used in board manufacture. The pilot project has been successful; the 30-month project has now reached the stage of industrial useage and application.

The High-Pressure Resination System (HPRS) is a partnership project involving partners from Spain and Italy. Imal, in conjunction with J.M. Colomer, made the investment in engineering, manufacturing and logistics to successfully commercialise this technology. Xilopantec has been producing panels for many years and has the know-how and expertise necessary for the application of the HPRS technology and to improve the industrial process. Imal and Xilopantec together focussed on establishing new collaborations with academic and industrial players to further develop the project solutions. The pilot line was set up at XILOPANTEC’s facility in Pavia.

The role of CEPRA, whose main mission is to promote Italian industry abroad, was to disseminate the project’s achievement in Italy and throughout the EU by using its extensive network of contacts and by organizing events.

The project was co-funded by LIFE+, which is the European Union’s financial instrument supporting environmental and nature conservation projects.

The aim of the project was to design and produce a pilot line that is able to reduce resin and power consumption in the wood fibre panel production process. Whilst UF resins have desirable thixotropic properties and provide the wood panel with good structural properties, it is paramount to optimize their use in relation to the desired properties and minimize the amount of formaldehyde, known for its effects on human health.

Imal-Pal, the co-ordinator of the project, describes the process as follows:- “Before addressing the technical aspects, we shall briefly summarise the project for a clearer understanding of the activities involved,” says the company.

“The woodworking industry is a very important sector in Europe, accounting for nearly €230bn of manufacturing added value in Europe [EPF, European wood factsheets]. “Engineered wood (EW) represents a highly relevant segment where a wide range of products are processed and employed in a wide range of applications, from building components to furniture parts. EWs include different varieties of panels such as particleboard, medium density fibreboard (MDF), plywood and oriented strand board (OSB).

“The blending process is a critical manufacturing phase in which resins are used to bind the different types of wood fibres together for the production of EWs.”

In traditional blending processes the wood fibres are crushed and driven at high speed inside drums, where the resin is injected through nozzles at a given pressure and mixed. The volume of resin added is calculated according to the weight of wood. The pressure is fixed and there is no other control of the resin/wood ratio.

The process has disadvantages and an inherent inefficiency. The purpose of the resin is to act as a glue. It sticks to the surface of the wood particles. The amount of resin should therefore depend not on the weight of the wood particles but on their surface area. This area of course will vary according to the size of the particles. Small, finely-divided wood fibres will have greater surface area than the same weight of larger, more coarsely-cut fibres.

Applying the resin at a fixed rate regardless of wood particle size is therefore wasteful of resin – and hence carries unnecessary costs, both financial and environmental.

Nevertheless, this known fibre resination process has been applied in various industrial facilities for over 50 years now and, throughout those years, has undergone numerous improvements. These, though, have primarily involved process automation and rarely the analysis of the blending process. It has yet to take advantage of the new era of digital sensors, high data flows and continual monitoring and feed-back controls; the process remains relatively crude.

Imal-Pal explains that the aim of the life-HPRS project is to remedy precisely this inefficiency: to reduce resin usage in the panel production industry by distributing the amount of resin required in relation to the surface area of the wood and not in relation to its weight.

The innovative solution that the partners have developed applies the resin at high pressure through specially-designed nozzles – injectors – which have variable diameter orifices. Monitoring of resin pressure is continuous and the nozzles open and close during operation to precisely adjust the dosage. Thanks to the high pressure they apply the resin at high speed.

The method achieves a quick and even distribution of glue onto the chip or strand layer. It also minimises waste and ensures optimization of the mixing process. Significant improvement can be achieved. HPRS reduces resin consumption by 10 to 20%, depending on panel type and previous process, with significant savings in terms of costs and harmful emissions due to formaldehyde contained in the glue. Summing up, by dosing and spreading resin more efficiently, the “over-spreading” method can become a thing of the past. More consistent boards consequently result.

Energy efficiencies also flow from HPRS. The electric motor used within the blending process needs 15% less power. The reduction in resin means a corresponding reduction in the drying process and the energy costs associated with it.

The technical targets which the partners reached, says Imal-Pal, are:

  • Environmental, economic and technical benefits achieved by introducing new mechanical technology for the nozzles and blender motor which is able to distribute the resin particles in a much more efficient manner than blending technologies currently available on the market.
  • A new effectiveness and efficiency of the entire production process and quality of the end-product with respect to current state-of-the art technology.

The environmental targets which were reached are:

  • A drastic reduction in resin usage in the panel production industry by demonstrating an engineered panel production line that is capable of saving up to 10kg (ie 10%) of resin for each cubic metre of panel produced. The reduction in the amount of resin consumed will also lead to a significant, 5%, energy saving in the MDF drying process.
  • To demonstrate a relevant reduction in energy consumption in the blending and drying process through the utilisation of an injection system that carries out a preliminary mixing of the wood and resin particles before the traditional blender comes into operation.

The main activities were performed at the XILOPANTEC premises in Cigognola, in Pavia, Italy. IMAL technicians and engineers assisted with the fine tuning of the pilot plant.

The definition of the operational logic and its adaption to the reality of plants located worldwide has been taken into consideration in the design of the pilot line, which was designed to understand the various technical solutions which need to be adopted to achieve the expected benefits from the HPRS project. These were examined first for the particleboard process and then for OSB and MDF. Installation and start-up at the pilot site have given more than satisfactory results.

The logic and the components are similar and are often modifiable with respect to the number of process variables regarding the type of raw material introduced into the process, the resins involved and the level of technology present in the panel production plant.

The new technology and equipment can be incorporated into the existing line. A special sticker supplied within the scope of the EU project can mark and identify those pieces of equipment involved in the project.

The HPRS system developed by the Italian and Spanish partners
Variable-orifice nozzles are the heart of the system
The system is now industry-ready