Understanding the Intermittent Working Mode of Small Pyrolysis Machines

Small pyrolysis machines are gaining popularity among small-scale recyclers and startup investors because they are low-cost, easy to operate, and require less land compared to large continuous pyrolysis plants. One of the most distinctive features of these small units is their intermittent working mode, also known as batch operation. For many new users, this working method can be confusing, especially when estimating daily output or planning manpower. This article explains how intermittent operation works and why it is commonly used in small pyrolysis systems.

What Does “Intermittent Working Mode” Mean?

In a batch pyrolysis system, raw materials are processed in separate cycles. Once a batch of waste—such as tires, plastic, biomass, or oil sludge—is loaded into the reactor and the lid is sealed, the machine begins heating and will not receive new material until the entire cycle is finished. The system must cool down before the door can be opened and the next batch can be loaded.

This is different from continuous pyrolysis systems, where materials are fed and discharged without stopping. Small pyrolysis machine typically avoids continuous processing because keeping material flowing evenly requires complex mechanical feeding, sealing, and high-temperature slag discharge systems.

A Typical Batch Operation Cycle

Although the duration varies depending on fuel type, heating method, capacity, and material shape, a standard operation cycle generally includes five stages.

First is feeding. Raw materials are manually or semi-automatically loaded into the reactor. This process usually takes one to three hours, especially if tires need to be cut or if plastic must be dried first.

Next is heating and pyrolysis. The reactor is heated to around 350–500°C. During this period, the material decomposes into oil vapor and syngas. This stage is the core of the process and may last six to ten hours. The gas produced can be recycled as fuel, reducing external fuel consumption.

After pyrolysis finishes, the system enters the cooling stage. Because the reactor cannot be opened under high temperatures for safety reasons, it must cool down naturally or through forced cooling systems. Cooling often takes six to twelve hours and is the most time-consuming part of the entire cycle.

Once the temperature is safe, solid residues such as carbon black, steel wires, or biomass char are discharged manually or using mechanical tools. This stage normally takes two to three hours. The reactor then becomes ready for the next loading.

Overall, a complete cycle generally requires 16 to 24 hours, meaning most small batch pyrolysis machines can only process one batch per day.

Why Small Pyrolysis Machines Use Batch Mode

Small pyrolysis systems favor intermittent operation for several reasons. The equipment cost is lower because there is no need for high-temperature continuous feeding seals or automatic discharge structures. The machine design is simpler, which reduces mechanical failure and maintenance costs.

Batch systems are also more flexible. Operators can easily change from plastic to tires in the next cycle without adjusting continuous feeding parameters. The operation skill requirement is lower as well, making it suitable for regions without industrial automation experience. Since batch systems remain sealed during heating, they also offer a high level of operational safety.

Drawbacks of Intermittent Operation

Despite its advantages, batch pyrolysis has limitations. Daily output is lower because production must stop for cooling and unloading. Labor demand is higher since loading and residue discharge often require manual work. Heat loss is greater because the reactor repeatedly cools down, reducing thermal efficiency. For large-scale industrial projects or continuous waste streams, batch pyrolysis may not meet production demands.

How to Improve Efficiency

Although batch systems cannot match fully continuous plants, several methods can boost efficiency. Pre-drying or shredding materials can shorten heating time. Waste heat recovery systems can pre-heat incoming feedstock. Using syngas as fuel reduces energy cost, and scheduling workers to begin feeding immediately after cooling minimizes downtime.

Conclusion

The intermittent working mode is an essential characteristic of small pyrolysis machines. It offers low investment, simple operation, and flexible material handling, making it ideal for small recycling businesses and decentralized waste-to-energy projects. While it cannot provide continuous large-scale output, understanding the batch cycle helps operators manage production efficiently and decide when upgrading to a continuous plant becomes worthwhile.