20–24 t/h Mixed Wood Chip Pellet Line, Henan Province, China

Background and Project Context

Henan Province sits at the center of China’s agricultural and forestry processing corridor, generating substantial volumes of mixed wood residue from timber processing, construction, and furniture manufacturing. Converting this material to biomass fuel through pelletization offers operators a route to monetize residue streams while supplying industrial heat and power customers who require a consistent, dense solid fuel.

The operator profiled here required a production system capable of processing mixed wood chips at 20–24 metric tons per hour under continuous operation. Key constraints included industrial safety compliance — particularly dust and fire risk management — and zero visible fugitive dust emission, consistent with the enclosed-processing requirements applied to biomass handling facilities in China’s manufacturing zones. The operator selected Kingwood to design and supply the complete line.

According to IEA Bioenergy Task 40 (2024 update), global industrial wood pellet demand exceeded 30 million metric tons in 2023, with large-format lines above 10 t/h representing a growing proportion of new investment. Projects at this scale require systematic engineering of each sub-process rather than a simple scale-up of smaller plant configurations.

Equipment Configuration

The line centers on eight JWZL-688 vertical biomass pellet mills running in parallel. Each JWZL-688 is rated at 2–2.3 t/h, so eight units in parallel produce the 20–24 t/h system output with a degree of redundancy built into the configuration. For a full specification of the JWZL-688 and its sister models, see the Kingwood vertical pellet mill product range.

Each mill uses a ring die design with a dual-bearing main shaft. Distributing the radial load across two bearings rather than one reduces localized wear on both the shaft and the die bore, extending the interval between scheduled maintenance stops — a meaningful consideration when eight units are running concurrently and downtime compounds across the bank. The main drive on each mill is a 200-kilowatt, four-pole motor, selected for energy efficiency at sustained output rather than peak intermittent performance.

Upstream, two hammer mills handle primary size reduction of incoming mixed wood chips. Downstream, a counter-flow cooler, vibrating screen, finished-product silo, and automated ton-bag packaging system complete the process train. An integrated dedust circuit operates across the entire line.

Project Scope and Output

Feedstock enters the facility via sealed belt conveyors fitted with permanent magnetic pulleys and self-discharge iron removers. This dual-stage tramp metal protection removes ferrous contamination before material contacts any mill internals — a standard precaution when feedstock provenance is mixed and consistent pre-sorting cannot be guaranteed.

The two hammer mills reduce chip size to the particle distribution required for pelletization. Each mill operates with spark detection, explosion isolation valves, and pressure relief venting active. Pulse discharge and enclosed infeed keep the mill inlet free of fugitive dust, addressing the conditions under which dust ignition risk is highest. Fine particles captured by the hammer mill deduster return to the belt conveyor, recovering usable material.

Crushed material travels by bucket elevator to a sealed surge bin positioned above the pellet mill bank. A hydraulic bottom discharge mechanism controls flow rate from the bin. A distribution auger then meters and splits the material stream evenly across all eight JWZL-688 mills, maintaining consistent feed to each unit.

After pelletization, finished pellets move on a perimeter belt conveyor to the counter-flow cooler. Counter-flow cooling — where ambient air moves opposite to pellet travel direction — produces a more uniform temperature reduction across the pellet cross-section compared with co-flow arrangements, which matters for pellet durability and moisture stability in storage. ISO 17225-2:2021 specifies mechanical durability and moisture limits for industrial wood pellets; cooler design is a direct determinant of whether finished product meets those thresholds.

Cooled pellets pass over a vibrating screen before entering the finished-product silo. The automated ton-bag packaging system handles metering and sealing at the silo discharge, maintaining pellet integrity for storage and bulk transport.

Engineering Highlights

Two design decisions stand out from a procurement engineering perspective.

The first is the line-wide dedust architecture. Rather than treating dust collection as a compliance measure with waste disposal as the endpoint, the system routes all captured fines back to the raw material silo. The transcript indicates this achieves over 99% material utilization. At 20–24 t/h throughput, even a fraction of a percent of material loss adds up to meaningful cost across a production year; the recirculation design eliminates that leakage. It also means the facility operates with zero dust emission to atmosphere, which simplifies environmental permit compliance.

The second is the choice to run eight parallel mills rather than a smaller number of higher-capacity units. Parallel configurations allow individual mills to be isolated for die changes, bearing inspections, or unplanned stoppages without halting total production. The distribution auger ensures that removing one mill from service simply reduces total output proportionally rather than triggering a system-wide shutdown. For an operator running continuous shifts, that operational flexibility has tangible value.

The fully enclosed processing envelope — sealed conveyors, enclosed surge bins, covered discharge points, and the integrated dedust circuit — means the facility handles a combustible organic feedstock at industrial scale without relying on operator discipline to control dust exposure. The enclosure is engineered in, not managed in.

Kingwood’s design and manufacturing capability draws on 27 years of R&D in biomass pellet equipment and a project portfolio spanning more than 30 countries and over 2,000 production line projects planned and designed.

Sources

• YouTube video r7XXObb-iL4 (Kingwood site footage, Henan Province mixed wood chip pellet line)
• IEA Bioenergy Task 40, Renewable Energy from Forests, 2024 update
• ISO 17225-2:2021, Solid Biofuels — Fuel Specifications and Classes, Part 2: Graded Wood Pellets