Fermentation never stabilises
Temperature does not hold above 55 °C, odour persists, or the cured material is still active when it reaches the granulator. Usually a turning, aeration or moisture problem rather than an equipment shortage.
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01
When a retrofit is the right answer
Market wants granules, plant makes powder
Adding granulation and drying to an existing powder line, reusing intake, fermentation, grinding and bagging, is often 40–60% of the cost of a new plant.
Read more →Output is below nameplate
The line runs at 60–70% of design rate because one step — usually screening, drying or bagging — was sized at nominal rate rather than with duty margin.
Read more →Odour or dust complaints
Extraction, enclosure and biofiltration retrofits, plus operational changes to turning times and pile moisture.
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Baseline measurement before design
- Feedstock tonnage and moisture actually received over a two-week period, including peaks.
- Fermentation temperature profile at three depths in the pile over a full cycle, with the turning record.
- Moisture of cured material entering the processing line, measured daily.
- Actual throughput at each process step, so the real bottleneck is identified rather than assumed.
- Granule size distribution, granule strength and final product moisture.
- Connected load and actual maximum demand, plus transformer and cable capacity headroom.
- Downtime log: what stopped the plant, for how long, and why.
03
Retrofit options ranked by cost and disruption
| Upgrade | Typical lead time | Disruption | Effect |
|---|---|---|---|
| Operational fix — turning regime, moisture, aeration rate | Days | None | Often the largest single improvement in fermentation stability |
| Add screening or bagging capacity | 3–6 weeks | Low, can be installed during normal stops | Removes the most common bottleneck at modest cost |
| Add a second shaft or turner for the fermentation bay | 4–8 weeks | Low | Shortens cycle or absorbs more feedstock |
| Convert open windrow to covered, aerated or in-vessel | 3–6 months | Medium, phased | Odour control, weather independence, smaller footprint |
| Add granulation, drying and cooling | 4–7 months | Medium to high | Changes the product and the revenue per tonne |
| New parallel line | 6–10 months | Low on the existing plant | Doubles capacity without stopping production |
04
The three constraints that decide what is possible
Building height. A dryer and cooler in series need vertical space and lifting access. If the existing building is 4.5 m to the hook and the new dryer needs 7 m of headroom, the retrofit becomes a building project as well.
Foundation capacity. Existing slabs were cast for the machines that were installed, not for heavier ones. We check dynamic loads and either spread them or cast new plinths — a decision that is far cheaper before equipment is specified.
Power headroom. A granulation and drying line adds 60–120 kW per tonne per hour of capacity. If the transformer has no margin, the retrofit needs an electrical upgrade first, and that is usually a utility lead time rather than a workshop task.
Retrofit an existing line
Send photographs of the existing plant, the equipment list and the last month of production data. We reply with the bottleneck analysis and the practical upgrade options.
FAQ
Plant engineering questions
Can a plant keep running during a retrofit?
Often yes, if the new equipment is installed in parallel and connected during a planned stop. Building work above an operating line is the exception and is scheduled with the customer's production calendar.
Our compost smells and never heats up. Is that a machine problem?
Usually not. The most frequent causes are low moisture, insufficient turning or aeration, a carbon-to-nitrogen ratio that suppresses microbial activity, or piles that are too small to retain heat. We measure the profile before recommending any equipment.
Is it worth adding a dryer, or can granules be sold at higher moisture?
That depends on your market and climate. Dryer-free granulation is possible with the right binder and a stable feedstock, but product moisture then depends on the fermentation and curing discipline. The design basis records which route is being designed for.
Can equipment from another manufacturer be integrated?
Yes. Retrofits commonly insert our equipment into an existing line. We measure the interface conditions — moisture, particle size, throughput, power and control signals — and design the connection rather than assuming the catalogue figures apply.
Send us your design basis
Tell us the feedstock, the daily tonnage and the product you want to sell. The engineering team replies with the plant configuration, the equipment scope and the information we still need before layout drawings start.
- Feedstock profile — type, moisture, contamination, seasonal peaks
- Capacity — t/day fresh material or t/h finished fertilizer
- Product — powder, granules, bagged retail, bulk compost
- Site — available area, power supply, water, access road
Prefer to talk first? WhatsApp +86 182 0399 3035 or email [email protected].