A batch pneumatic conveying system transfers defined quantities according to a repeated operating cycle. It can support batch mixers, weigh vessels, reactors and production lines that require material traceability between stages. “Batch” describes the timing of transfer; it does not determine whether solids move in dilute phase, dense phase or as a plug.
For roots blower selection, the decisive values are the peak airflow and pressure during the active conveying interval—not the hourly averages for the complete cycle.
Break the Cycle into Real Operating Steps
A batch sequence can include:
- Filling or weighing the feed vessel.
- Isolating it from the upstream process.
- Starting and proving the air system.
- Introducing material into the conveying line.
- Clearing the pipe and receiver connection.
- Stopping or reducing the air supply.
- Resetting valves and preparing the next batch.
Some pressure-vessel systems also include pressurization and controlled depressurization. Those steps can create a higher pressure or short-term air demand than steady material transport.
Average Throughput Can Hide the Peak Duty
If material is conveyed during only part of each hour, the instantaneous solids rate in that interval must be higher than the required hourly average. The feeder, pipe, receiver and filter all see this active rate.
The duty definition should state batch mass, number of batches per hour, filling time, conveying time, clearing time and expected delay between cycles. It should also identify whether batches can overlap elsewhere in the process. Sizing only from average tonnes per hour can produce a line that cannot empty the vessel within the required schedule.
Air demand may also vary through the cycle. The blower and any receiver should be evaluated from a transient air balance, including feeder leakage, fluidizing air and purge demand. A receiver does not create pressure capability that the blower does not have.
Low-Pressure Batch Feeding Options
A batch process does not always require a blow tank. Material can be accumulated in a weigh hopper and then metered through a suitable rotary airlock or other pressure-capable feeder into a low-pressure conveying line. The conveying portion may behave like a conventional continuous line for a limited time.
This arrangement can be considered for a Pasifik roots blower when normal and peak pressure remain within the selected model’s verified curve. The feeder must handle the instantaneous solids rate and restrict leakage throughout the batch discharge.
The Blow-Tank Pressure Boundary
A blow tank is a pressure vessel that uses gas pressure to discharge material. Many dense-phase, long-distance and single-plug designs operate at several bar. Those duties are outside the published Pasifik positive-pressure portfolio and should use an air source and vessel system engineered for the required pressure.
A lower-pressure blow tank is not automatically excluded, but its full cycle must be checked. Peak vessel pressurization, line pressure, purge flow, valve sequence and receiving-vessel pressure must all remain within the blower package and system ratings. The source diagram that combines “roots blower / Compressor” has been removed because these equipment categories are not interchangeable.
Single-Plug Systems Need Separate Validation
Transporting an entire batch as one compact plug can reduce material velocity, but pressure rises with plug friction, length, compaction and route complexity. When the plug exits, compressed gas behind it can expand quickly and impose a transient load on the receiver and filter.
Material testing should confirm repeatable plug formation, restart behavior, wall friction, product quality and residual deposits over multiple cycles. A successful first batch is not proof of a stable conditioned line. Many single-plug applications exceed low-pressure blower capability.
Controls, Standby and Thermal Operation
The control sequence should prove receiver availability, route position, filter condition and blower status before material feeding begins. A feeder trip should stop solids without trapping an unsafe pressure condition. High pressure, high discharge temperature and receiver high level require defined actions. If batches are widely separated, stopping the blower may save energy, subject to the permitted starting frequency and process sequence. For shorter intervals, variable speed or unloaded operation may be evaluated within the manufacturer’s minimum-speed and cooling limits. Continuous relief-valve discharge is not an acceptable control strategy.
Glossary
Batch mass: Defined quantity of bulk material transferred during one operating cycle.
Clearing time: Interval during which gas removes residual conveyed material from the pipeline after feeding stops.
Cycle time: Total elapsed time for all operating steps required to complete one batch transfer.
Instantaneous conveying rate: Solids flow during the active transfer interval rather than its average over the full cycle.
Peak air demand: Greatest short-duration gas-flow requirement across the operating cycle.
Pressurization time: Interval required to raise a vessel or system from its initial pressure to a defined operating condition.
Single-plug conveying: Batch method in which a defined material quantity moves through the line as one concentrated body.