A pilot glass reactor is not simply a larger laboratory reactor.
When a process moves from 2–5L laboratory trials to 20L, 50L, 100L or larger pilot batches, mixing, heat transfer, feeding, vacuum, discharge and operation all change.
The purpose of a pilot reactor is to verify whether the process can still be controlled before moving toward production scale.
At HJCHEM, we normally start with the customer’s actual process sequence, rather than selecting a reactor only by volume.
Start with the Real Working Volume
For example:
- initial charge: 20L
- later liquid addition: 8L
- final process volume: approximately 28L
In this case, selecting a reactor based only on the initial 20L charge may leave insufficient headspace.
Pilot processes may also need extra space for:
- foaming
- reflux
- gas generation
- vacuum boiling
- powder addition
- later dosing
This is why glass reactor working volume should be confirmed before choosing the nominal reactor capacity.
Do Not Copy Laboratory RPM Directly
If a 5L reactor performs well at 300 rpm, it does not mean a 50L reactor should also operate at 300 rpm.
For pilot-scale equipment, the agitator should be selected according to:
- viscosity
- solids content
- mixing purpose
- working volume
- viscosity changes during processing
In HJCHEM projects, we may use propeller, paddle, anchor or other customized impeller configurations depending on the material.
For processes with vortexing or insufficient axial circulation, PTFE baffles can also be added.
See our guide to glass reactor agitators for more detail.
Heat Transfer Becomes More Important During Scale-Up
A larger batch normally takes longer to heat and cool.
The jacket may reach the target temperature quickly while the material in the center of the reactor responds more slowly.
This becomes particularly important for:
- exothermic reactions
- low-temperature reactions
- crystallization
- temperature-sensitive synthesis
- polymerization
- vacuum concentration
For pilot development, it is useful to record:
- starting temperature
- target temperature
- required heating time
- required cooling time
- actual material temperature
- jacket or circulator temperature
Do not evaluate the system only by the minimum or maximum temperature of the circulator.
Cooling capacity at the actual operating temperature is more important.
Laboratory Feeding Often Needs to Change at Pilot Scale
At laboratory scale, a chemist may add material manually using a dropping funnel.
At pilot scale, the same method may become too slow or difficult to control.
Depending on the process, HJCHEM can configure:
- peristaltic pumps
- metering pumps
- dosing pumps
- multiple independent feed lines
- pH-controlled dosing
- sealed feeding under vacuum
An example is a customized HJCHEM coprecipitation glass reactor.
Depending on the customer’s process, the system can use three or four feeding pumps. Two or three pumps operate at preset flow rates, while another dosing pump is automatically controlled according to the pH signal.
The reactor can also include:
- pH probe
- temperature sensor
- four internal PTFE baffles
- overflow outlet
This type of configuration is much closer to actual pilot process development than simply adding several ports to a standard reactor.
See our coprecipitation glass reactor configuration for an example.
Consider Vacuum as a Complete System
If vacuum is part of the pilot process, do not select only a reactor and vacuum pump.
The complete system may include:
Reactor → Condenser → Receiver → Cold Trap → Vacuum Pump
Depending on the process, not every component is required.
The important questions are:
- Why is vacuum required?
- What operating pressure is needed?
- Is solvent evaporating continuously?
- Is solvent recovery required?
- Does material need to be fed while under vacuum?
A pilot reactor used only for vacuum-assisted reaction requires a different configuration from one used for vacuum distillation or solvent concentration.
For this type of process, see our guide to choosing a glass reactor for vacuum reactions.
Discharge Becomes a Real Operation Issue
At 2L or 5L scale, material can often be poured out manually.
At 50L or 100L scale, this is no longer practical.
Before selecting a pilot reactor, consider:
- material viscosity
- solids content
- crystal formation
- bottom valve size
- whether gravity discharge is sufficient
- whether residue remains in the vessel
- how the reactor will be cleaned
For processes containing solids or sticky residues, vessel access can become as important as the reaction itself.
HJCHEM can customize liftable glass reactor systems where the vessel can be lowered and tilted up to 120° for easier access, cleaning and residue handling.
This type of configuration can be useful during pilot development when frequent cleaning and process changes are required.
See our liftable glass reactor article for more detail.
Do You Need a Complete Pilot Reactor System?
Depending on the process, a pilot system may include:
- jacketed glass reactor
- heating and cooling circulator
- vacuum pump
- condenser
- receiver
- dosing pumps
- pH control
- gas inlet
- scrubber
- PLC/HMI control
The correct configuration depends on what the customer wants to verify during pilot trials.
Our guide to a complete glass reactor system explains the common supporting equipment.
What Should You Provide for a Pilot Reactor RFQ?
Provide the following information:
- initial batch volume
- maximum working volume
- process materials
- viscosity
- solids content
- operating temperature
- required heating/cooling time
- vacuum requirement
- mixing purpose
- number of feed streams
- feed rates
- reflux or distillation requirement
- solvent recovery requirement
- discharge method
- required sensors
- preferred automation level
If some information is not yet known, describe the laboratory process step by step.
That is often enough for HJCHEM to identify which parts of the laboratory setup need to change at pilot scale.
What Should a Good Pilot Reactor Help You Learn?
A pilot reactor should help answer questions such as:
- Can the batch still be mixed effectively?
- How long does heating and cooling take?
- Can dosing remain stable?
- Does the reaction behave differently at larger volume?
- Can vacuum be maintained?
- Is condensation capacity sufficient?
- Can solids be discharged easily?
- Which parameters must be controlled before further scale-up?
This information is often more valuable than simply proving that a larger batch can be produced.
FAQ
1. What size is considered a pilot-scale glass reactor?
There is no universal definition. In many process-development projects, capacities such as 20L, 50L, 100L and 200L are commonly used for kilo-lab or pilot work, depending on the application.
2. Can I use the same RPM when scaling from 5L to 50L?
Not necessarily. Reactor geometry, impeller diameter, torque and flow pattern change with scale.
3. Can one pilot glass reactor perform reaction and distillation?
Yes, if the vessel, condenser, receiver, vacuum system and port layout are configured for both operations.
4. Should I buy a larger reactor for future scale-up?
Not automatically. A reactor that is too large for the current batch may create poor mixing or sensor-immersion problems. Choose the reactor according to the actual working volume first.
Conclusion
A pilot-scale glass reactor should not simply reproduce the laboratory reactor at a larger volume.
The important questions are:
Working Volume → Mixing → Heat Transfer → Feeding → Vacuum → Monitoring → Discharge → Control
For process development, the best pilot system is one that allows you to understand how these conditions change with scale.
HJCHEM can configure pilot glass reactors from the actual process sequence, including vessel design, agitation, temperature control, feeding, vacuum, condensation and automation.
Planning to Scale Your Process from Lab to Pilot Scale?
Send HJCHEM your target pilot volume, material properties, temperature, vacuum, mixing and feeding requirements.
We can help identify which reactor functions should remain the same and which need to change during scale-up.