Dryer FAQ

A few points need to be clear about capacity figures:

1. Capacity is not a fixed value. The same machine will produce different figures for a different material, a different initial moisture content or a different target final moisture.

2. Figures must state whether they are on a dry basis or a wet basis. Dry basis means the mass of bone-dry material; wet basis includes the moisture. The two differ substantially and the ambiguity causes problems if it is not stated.

3. Official data comes from a trial run. Until the operating parameters are fixed, any capacity figure is only an order of magnitude.

4. Air volume can be stated precisely. It is fixed by the machine size, does not change with the material and can be given at the selection stage.

Providing the material name, the initial moisture content and the target final moisture is what makes a recommendation usable.

The two have different structures and suit different duties:

Flash airflow dryer

It dewaters through brief contact between high-temperature air and the material. Drying is fast, which suits inorganic salts and chemical powders that need rapid dewatering. Sizes are Φ220, Φ280, Φ325, Φ400, Φ500 and Φ600.

Rotary dryer

The rotating drum tumbles the material for more even heating. It suits sawdust, plastic pellets and flake materials that do not break up while tumbling.

How to decide

Look at the material form and whether it is sticky. Powders and fast-dewatering duties point to flash airflow; granular or flake materials needing even heating point to rotary. The moisture content and target final moisture still have to be considered.

The choice mainly follows the site energy supply:

Steam heating

Suits plants that already have a boiler or steam piping. Running cost is relatively lower and it fits long continuous production.

Electric / electromagnetic heating

Suits sites with no steam supply, requiring no piping, with flexible deployment and fast start-up. The electromagnetic series handles roughly 200–5000 kg/h, provided the electrical capacity matches.

How to decide

Check whether a boiler exists, whether electrical capacity is sufficient, and which running cost is lower over time. With adequate power and no steam, electric heating is the simpler choice.

Equipment is built to suit the operating conditions. Lead time depends mainly on the machine size and how complex the configuration is, and scheduling is arranged once the requirement is clear.

The parameters to provide in advance are: material name and properties, initial moisture content, target final moisture, daily throughput, and the available space and energy supply (electrical capacity or steam parameters).

The clearer the parameters, the more accurate the selection and quotation, and the easier the schedule. If they are not yet clear, a small trial run is the usual way to establish them.

Powders such as battery-grade lithium powder and aluminium powder have strict batch consistency requirements. Two approaches are common:

Batch dryer

Charges, dries, cools and discharges in cycles, with controlled time and temperature per batch and small variation between batches. Suits small volumes and frequent product changes.

Flash airflow dryer

Continuous operation with fast dewatering, suiting high-volume continuous production.

Note

Powders are generally hygroscopic and easily airborne, and aluminium powder also needs explosion protection and temperature control. These conditions should be raised with the manufacturer at the selection stage.

The price depends on the configuration, and the configuration depends on the operating conditions, so the same type of machine can differ substantially in price between applications. The main factors are:

Machine size

Drying tube diameter or drum size, material of construction (carbon steel or stainless steel) and wall thickness form the main part of the price.

Heat source

Steam, electric heating, electromagnetic heating and natural gas require noticeably different ancillary equipment and therefore carry different prices.

Ancillary equipment

Fans, dust collectors, feed and discharge conveyors, control cabinets and any explosion protection requirement all enter the total price.

How to obtain an accurate quotation

Provide the material name and form, initial moisture content, target final moisture, daily throughput and the site heat source conditions, and a corresponding configuration and quotation can be given. If the parameters are incomplete, a directional range is possible first.

Common heat sources are steam, electric heating (including electromagnetic), natural gas and biomass. The choice follows the site conditions and environmental requirements:

Steam

More economical for plants that already have a boiler, with a lower unit cost of heat; suits long continuous production.

Electric / electromagnetic heating

No boiler or steam piping needed, flexible deployment and fast start-up, provided the electrical capacity matches. The electromagnetic series handles roughly 200–5000 kg/h.

Natural gas / biomass

Usable where a gas supply or biomass fuel is available, and high hot air temperatures are easy to reach. Local emission requirements need to be checked.

Order of decision

First what is available on site, then the long-term running cost, and finally whether environmental rules allow it. Where all three are satisfied, choose the option with the lower running cost.

Machines are assembled and trial-run before dispatch, and the sequence afterwards is:

Arrival and installation

Staff are generally arranged to guide installation and commissioning on site, while the customer prepares the foundation and the power or steam connection.

Power-on trial run

After installation the machine is trial-run on site to confirm air volume, temperature and operation of each stage, and the operating parameters are adjusted to the actual material.

Operator training

Operation and routine maintenance are explained during the trial run, focusing on temperature control, cleaning intervals and wear-part replacement.

Ongoing support

Contact us at any time if a problem appears in operation. Specific schedules follow the plan agreed by both parties.

Site conditions that need preparing in advance are best confirmed at the contract stage so that the machine is not left waiting on arrival.

It depends on the material properties and the drying method, and should be considered at the selection stage:

Mechanical breakage

In a rotary dryer the material tumbles and falls continuously, and brittle granules tend to produce fines. Where the particle size distribution matters, the lifter pattern needs adjusting or a flash airflow dryer should be considered instead.

Heat damage

Temperature-sensitive materials (some pharmaceuticals and food products) require a ceiling on the hot air temperature and a limit on dwell time. A shorter dwell time means less heat damage, which is why flash airflow is used for heat-sensitive materials.

Moisture regain

Strongly hygroscopic materials take up moisture again if the cooling and transfer stages expose them to air for too long, so the discharge and packing stages have to be considered as part of the solution.

How to confirm

State the heat sensitivity and particle size requirements in advance and check particle size and moisture during the trial run. That is the most direct way to confirm the result.