Seated neatly in a factory in Sundsvall, Sweden, is a pilot reactor for the production of steam explosion materials. A seemingly inconspicuous toolkit, which belongs to the Valmet Fiber Technology R&D Center, is the Finnish leader. A division of Valmet Oyj, a global forest industry and energy technology company. With its innovative technology, the company may have broken the stalemate in the 'chicken and eggs' market.
As a landmark, Sundsvall has a long tradition in wood fiber, pulp and paper processing technologies – Sunds, SCA and Defibrator became Sunds Defibrator, a mechanical fiber separation process, METSO points in 2013 After the demolition became a virtue.
Steam explosions or steam treatments can produce 'black' particles, which proponents regard as safer and more cost-effective renewable biomass fuels than traditional 'white' biomass particles. Like the black particles they bake, steam The black particles produced by the explosion can contain more energy per kilogram, have a strong hydrophobicity, do not generate heat or generate exhaust gas, lead to a smaller amount of dust, and can be grinded and burned like coal.
According to Valmet, its black particles can replace 100% of coal in small equipment, and the proportion of coal that can be substituted in large plants can reach as high as 70% without the need to define dimensional details. As a multi-fuel boiler system for industrial scale The main supplier, the company undoubtedly understands the performance of different fuels in its boiler.
However, unlike Andritz AG, one of the most widely known and respected Austrian counterparts, the company accidentally chose a drying route - because its current technology portfolio does not include granulation equipment, it is made in wood pulp. The grain industry may be more like a dark horse.
In other words, the company does have other equipment required for industrial-scale pellet plants, such as material handling, debarkers, downsizing, belt dryers and conveyors, and technology for producing steam exploded materials.
Use the difference
Other technology developers, such as Arbaflame of Norway and Zilkha Biomass of the United States, have developed steam treatment technology and have been busy providing solutions for investors while providing products to the electric utility market. Here are already two notable Differences: Company size and lack of demonstration facilities.
As a publicly listed company, Valmet is financially strong enough to operate as a complete turnkey, procurement and construction (EPC) contractor. In fact, the company has successfully built millions of euros across the world. Industrial process projects, such as pulp and paper mills or biomass power plants.
Second, both Arbaflame and Zilkha use black granule production equipment, and at least one commercial off-take agreement is in place, and Valmet does not even have a demonstration plant, just a pilot unit of Sundsvall.
Although the company stated that it can provide retrofit services for existing white pellet factories, the lack of its own demonstration plant may become a thorny issue, at least in terms of the wood pellet industry.
In February 2014, when Valmet and Zilkha developed a 'global joint product' based on Zilkha's solution, Valmet and Zilkha signed a five-year cooperation agreement to bring 'steam explosion black particles into the market'. According to Valmet This partnership has triggered some potential black particle plant projects.
However, the company also pointed out that different regions face different challenges, and the technology may not be suitable for everyone. In addition, the company’s presentation at various conferences in recent years shows that it may not be the first thing the particle industry itself sees. Batch Valmet equipment.
The established philosophy
Valmet may appear to be only a latecomer, but it is worth pointing out where the company came from. In short, the steam explosion process itself can be traced back to William Mason and the masonry process — a kind of fiberboard product that was commercialized in the 1930s. .
In a studio at the Valmet fiber technology R&D center in Sundsvall, Sweden, all black magic is hidden Pilot test reactor. So the concept that wood fiber is treated with steam under pressure and then rapidly decompressed is not new. This process variant is used in the wood-based panel industry and the company also serves this industry. It is this process technology that is isolated and applied by the company. In the production of black particles of steam explosion material.
Continuous process
The wood chips or micro-form material is fed into a pressurized reactor using a drying screw before being sent to a pressurized reactor with a buffer silo. The screw plug is then used - a common technique used in the pulp industry. Material is fed into a pressurized container.
When using a screw plug, the material itself forms a seal against pressure loss when it enters the reactor. Once in, just add steam, explains Peter Björklund, Valmet's Senior Process Engineer.
The material moves inside the reactor. The residence time depends on the type and size of the biomass and is then discharged from the reactor through the blow valve into the so-called blowpipe.
It is here that a de facto steam explosion occurs - as the vapor-saturated material moves from high pressure to normal atmospheric pressure through the blow valve, the sudden drop in friction and pressure causes the material to instantaneously decompose or 'explode' into small particles, almost becoming powder.
This also means that no extra treatment is required between the steam explosion and the granulation step.
Bark and integrated cogeneration unit
The single most important factor in the biomass fuel value chain is the cost of raw materials – access to a large amount of low-cost raw materials will greatly increase the economic benefits of any particle project. The steam explosion process is low-grade, and upgrading of low-cost materials creates opportunities for high-quality products.
One of the raw materials is bark from the wood processing industry, such as sawmills and pulp mills, and as these industries become more energy efficient, not all barks need to be used internally. In addition, bark pre-drying Low grade residual heat and process steam are also easily available in these industries.
Valmet's Senior Process Engineer Peter Björklund discussed the advantages of its steam treatment technology at the WSED in Austria. Our test unit in Sundsvall produced black particles from the bark to verify product quality parameters. The test run confirmed the suitability of cork bark for the production of black particles and could soon provide a promising alternative for the heating and power industries, Peter Björklund Say.
Another possibility highlighted by Björklund is the integration of black particles with a packaged combined heat and power (CHP) production system to provide energy for production and provide excess power to the grid.
This depends on the specific situation of the local area and the project, especially in the overall feasibility, especially in terms of on-grid tariffs, Björklund quickly said that the use of high-quality fuel on site does not make much sense.
Instead, the CHP plant will use low-grade wet fuels such as waste or bark, and the wood chips will be upgraded to black pellets, which will be sold out with excess electricity.
For some reason, the Japanese outback will use those 'unused wood' (which may be very suitable for this type of combined heat and power), and time will tell whether Valmet's approach helps to break the deadlock.
