1. General information
- In efforts to effectively tackle the climate crisis and reach net-zero emissions by 2050, operators across multiple industries have adopted highly deliberate strategies to decarbonize their processes.
- Yet, as many have discovered, these endeavors have frequently encountered formidable barriers such as high capital costs, regulatory approvals and long implementation timelines. In the meantime, operators need access to low-cost, high-ROI, carbon-reducing solutions now.
- The wood pellet industry is no exception. Raw material sourcing, transportation and waste management all heavily contribute to a carbon footprint that is no longer sustainable. The industry’s conventional approach to wood pellet production has also been very energy-intensive and required extensive equipment to clean emissions before being released into the atmosphere.
- While many efforts are already underway within the wood pellet industry to increase efficiencies at the manufacturing stage, meeting net-zero objectives will require operators to increasingly leverage modern technologies and adopt innovative processes.
2. Wood Pellet Process Traditional Technology
- Before delving into decarbonization solutions, it is important to understand the wood pellet manufacturing process and technologies that are currently in use. Wood pellets are created by first removing moisture from incoming wood fiber. That fiber is then ground into dust and compressed into small pellets measuring between 6 and 8 millimeters in diameter and up to 40 millimeters in length.
- During the process, the wood pellets are heated up so the lignin in the wood acts as an adhesive to keep the compressed particles together. Once discharged, the wood pellets range in temperature from 70 degrees Celsius (158 degrees Fahrenheit) to 100 C, making them too hot for storage and transport. The preferred option is to cool the wood pellets to approximately 3 C to 5 C above ambient temperatures.
- Conventional counterflow air wood pellet coolers use chilled or ambient air to cool the wood pellets. The wood pellets enter a cooling bin, typically through a rotary valve, and are leveled off by a distributor. Cold air is then injected into an isolated bin under the bed of pellets, thereby indirectly cooling the product from the bottom up. A level sensor inside the bin determines when the wood pellets are discharged.
- This traditional cooling method has the disadvantage of requiring large energy inputs (e.g., high horsepower fans) to get the job done—a challenge for wood pellet producers who are already facing high energy costs.
3. Moving Bed Heat Exchangers
- Alternatives such as plate-based moving bed heat exchangers (MBHE) at the cooling step of production offer wood pellet producers the opportunity to improve the energy efficiency of their existing processes, with the added benefit of significantly improved heat transfer efficiency.
- Plate-based MBHEs blend the thermal efficiency of plate heat exchange design with the science of uniform mass flow to cool pelletized bulk solids such as wood pellets. In an MBHE, the solids flow by gravity between a series of vertically oriented, hollow stainless-steel plates—typically made of SS304L for the wood pellet industry. The plates are cooled by a working fluid that flows through the plates’ internal channels countercurrent to the product flow.
- The cooling medium is often a cooling water source or chiller water. In some cases, brine, river water or seawater can be used by incorporating a closed-loop fluid temperature control module. The system can also operate as a stand-alone system via a dedicated closed-loop circuit using a dry cooler and chiller.
- The MBHE has a discharge device at the bottom that controls the flow of product, usually by a variable frequency drive or pneumatic actuator, before it exits to the downstream conveyance system.
4. Summary of the main content:
- The problem: The wood pellet industry is looking for ways to reduce its carbon footprint to meet climate goals.
- The traditional solution: Cooling wood pellets with cold air is energy-intensive.
- The new solution: Using moving bed heat exchanger (MBHE) technology to cool wood pellets more efficiently.
- How it works: MBHE uses stainless steel plates to transfer heat from wood pellets to a cooling liquid, reducing pellet temperature quickly and saving energy.
- The advantages: MBHE increases energy efficiency, reduces operating costs, and reduces carbon emissions.
5. Conclusions :
- Moving bed heat exchanger technology is a promising solution to reduce carbon emissions in the wood pellet industry. By using this technology, wood pellet producers can reduce energy costs, increase production efficiency, and contribute to environmental protection.
Note: The information in this article is for reference only and may change depending on the manufacturer and source of raw materials. For the most accurate information, you should consult experts, wood pellet suppliers or contact Overc.vn to answer your questions and problems related to wood pellets and wood chips.
Source:
- Biomass Magazine
- Overc Team synthesise, analyse and write articles.
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OVERC was established in Vietnam, which has 17 FTA (Free Trade Agreement).
Vietnam is one of the countries with the most FTAs in the world.
Our main activities are manufacturing and distributing Wood Pellets and Wood Waste. Our wood pellet products, which are made from Acacia veneer residual 100% or wood waste (logs, sawdust, wood chips, wood shavings,…), have been exported to many countries around the world such as Japan, Korea, EU, etc.
OVERC Co.,Ltd would like to wish you all the best at this time.
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