Glass-Lined Reactors: Complete Guide with Design, Parts, and Parameters
Glass-Lined Reactor Technical Specifications: Hi, today we are going to learn about glass-lined reactors—a critical type of equipment in industries handling corrosive, high-purity, or sensitive chemical reactions. These reactors are popular in pharmaceutical, chemical, and polymer manufacturing processes due to their unique construction and corrosion resistance.
In this guide, we’ll cover everything you need to know about glass-lined reactors, including their key parts and component names, so you can understand how each section functions within the overall system. We’ll also walk through the technical specifications, including the typical pH range, which is critical for chemical compatibility, and the temperature range that defines operational safety. The guide will explain the MOC (Material of Construction) used in these reactors, focusing on why glass-lined steel is chosen over other materials. We’ll dive into design parameters from both the process and utility side—such as pressure, temperature, and utility requirements—as well as provide best practices for OMC (Operation, Maintenance, and Cleaning) to ensure long service life and safe usage. Finally, we’ll include a section with frequently asked interview questions related to glass-lined reactors, which will be especially helpful for students, job seekers, and professionals preparing for technical roles in the chemical and pharmaceutical industries.
Table of Contents
Glass-Lined Reactor Parts
Glass-lined reactors are complex vessels that consist of several integrated parts to handle both mechanical and chemical functions.
Major Components:
- Reactor Vessel (Shell)
- Agitator (Anchor, Turbine, or Propeller type)
- Jacket / Limpet Coil (for heating and cooling)
- Drive System (Motor and Gearbox)
- Nozzles (for charging, venting, instrumentation)
- Manhole or Handhole
- Baffles and Dip Pipe
- Thermowell
- Bottom Outlet Valve
- Internal Glass Lining
Glass-Lined Reactor Parts Name
| Part Name | Function |
|---|---|
| Shell | Main body containing the reaction mass |
| Jacket / Limpet Coil | For heating or cooling using utility fluids |
| Agitator | Provides uniform mixing of contents |
| Nozzles | Entry/exit points for materials and instruments |
| Thermowell | Holds temperature sensor securely |
| Baffles | Enhances agitation efficiency |
| Bottom Valve | Outlet for draining material |
| Manhole | For inspection and manual cleaning |
| Drive System | Powers agitator via motor-gearbox assembly |
Glass-Lined Reactor Technical Specifications
| Parameter | Typical Value or Range |
|---|---|
| Capacity | 100 to 60,000 Liters |
| Design Pressure | –1 to +6 bar |
| Design Temperature | –20°C to 200°C |
| Agitation Speed | 10–100 RPM |
| Glass Lining Thickness | 1.5 to 2.5 mm |
| Lining Color | Blue or White (manufacturer-specific) |
| Compliance | ASME / DIN / GMP |
Glass-Lined Reactor pH Range
- Standard pH Range: 1 to 9 (safe and long-term use)
- Extended Range: up to pH 12 (short-term, mild temperature)
- Not Recommended: Strong alkali at high temperature
Glass-Lined Reactor Temperature Range
| Medium | Temperature Limit |
|---|---|
| Reaction Mass | –20°C to 200°C |
| Jacket Steam | Max 6 bar pressure (~165°C) |
| Hot Oil | Up to 180–200°C |
| Chilled Water / Brine | –10°C to 10°C |
Avoid sudden heating/cooling to prevent glass cracking.
MOC (Material of Construction) of Glass-Lined Reactor
| Component | Material |
|---|---|
| Shell (Outer Body) | Mild Steel (MS) or Stainless Steel (SS) |
| Internal Surface | Glass Enamel (fused under high temperature) |
| Agitator Shaft | Glass-lined or PTFE-coated |
| Nozzles and Valves | Glass-lined steel or PTFE-lined |
| Gaskets and Seals | PTFE, EPDM, or chemical-resistant elastomers |
Design Parameters: Process Side & Utility Side
Process Side Parameters
| Parameter | Typical Design Values |
|---|---|
| Working Pressure | –1 to +6 barg |
| Reaction Temperature | –10°C to 180°C |
| Reaction Type | Batch, Semi-batch |
| pH Compatibility | 1 to 9 (safely), up to 12 (controlled) |
| Agitation | Low to high viscosity, depending on design |
Utility Side Parameters
| Utility | Operating Range |
|---|---|
| Steam (Jacket) | Up to 6 bar (≈165°C) |
| Hot Oil | Up to 200°C |
| Chilled Water / Brine | –10°C to 10°C |
| Jacket Pressure | Typically up to 6 barg |
OMC – Operation, Maintenance & Cleaning
Operation
- Preheat reactor to avoid thermal stress
- Control ramp rates for heating/cooling
- Avoid excess pressure and vacuum
Maintenance
- Perform spark tests to detect glass damage
- Monitor motor, gear, and seal performance
- Replace gaskets regularly
Cleaning
- Use chemical (non-abrasive) methods
- Avoid brushes or hard scrubbing tools
- Prefer CIP systems for consistent cleaning
Pro Tips for Glass-Lined Reactor Use
- Avoid High Pressure & Temperature
- Glass-lined reactors are not suitable for very high pressures (>6 bar) or temperatures above 200°C. Use special alloy reactors or lined SS reactors for such conditions.
- Never Use for pH Above 14
- Extremely alkaline media (pH > 12–14) can attack the glass lining, especially at high temperatures. Avoid prolonged exposure or switch to PTFE-lined or Hastelloy reactors.
- Follow DIN Standards
- Always select GLRs manufactured as per DIN 28136 / 28160 standards for quality assurance in design, fabrication, and inspection.
- Preheat Reactor Gradually
- Prevent thermal shock to glass by slowly ramping temperature during startup. Sudden heating/cooling may crack the lining.
- Conduct Regular Spark Testing
- Periodically test for micro-cracks or pinholes using an AC or DC spark tester. It helps detect invisible damage early.
- Avoid Abrasive Cleaning Tools
- Never use metal brushes or scrapers. Use only soft brushes, non-abrasive cloths, or approved chemical cleaning agents.
- Check Compatibility First
- Before running any new chemical batch, verify chemical compatibility with glass lining, even if pH is within the range.
- Limit Vacuum Usage
- GLRs are not ideal for full vacuum operations unless specially designed. Confirm vacuum rating with the supplier.
- Use Clean Utilities
- Make sure that steam, hot oil, and chilled water are free from suspended particles to avoid localized damage inside jacket or limpet coil.
- Protect Against Mechanical Impact
- Avoid hitting the internal surface with tools or sampling rods during maintenance, which may cause chipping.
- Maintain Proper Agitator Clearance
- Ensure that the agitation system is aligned and impeller does not touch internal surfaces. Misalignment can crack the lining.
- Document pH Profile of Process
- Keep a detailed pH log of your process (start to end) to avoid unintended pH excursions damaging the lining.
- Don’t Use Compressed Air for Mixing
- Avoid sparging compressed air directly unless verified; impingement can lead to erosion of lining over time.
- Use Thermal Shock Protectors (if possible)
- Some modern GLRs have expansion joints or thermal buffers. Use them when available to reduce thermal stress.
- Train Operators Regularly
- GLRs require special handling knowledge. Make sure operating and cleaning personnel are trained and aware of limitations.
Glass-lined Reactor Interview Questions
What is a glass-lined reactor?
Answer
A glass-lined reactor is a type of pressure or batch reactor made by coating the interior surface of a steel vessel (typically mild steel or stainless steel) with a layer of glass enamel. This lining provides excellent resistance to corrosion, chemical attack, and contamination. These reactors are commonly used in pharmaceutical, chemical, and fine chemical industries for handling aggressive and high-purity reaction mixtures.
What is the difference between a glass reactor and a stainless steel reactor?
Answer
The main difference lies in the internal material and its compatibility. A glass reactor usually refers to a fully transparent borosilicate glass vessel, mainly used in labs or pilot plants, offering visibility but low pressure resistance. A stainless steel reactor is durable and good for neutral to mildly basic reactions. In contrast, a glass-lined reactor has a steel body with an internal glass coating, making it ideal for industrial-scale reactions involving corrosive, especially acidic, substances where stainless steel would corrode.
What damages the glass-lined reactor?
Answer
Glass-lined reactors can be damaged by thermal shock (sudden temperature changes), mechanical impact (tools or agitator contact), chemical attack (especially from strong alkalis at high temperature), and improper cleaning methods using abrasive materials. Over time, normal wear, erosion, or misaligned agitators may also cause micro-cracks, chips, or peeling in the glass lining.
What is the pH range of a glass-lined reactor?
Answer
Glass-lined reactors are best suited for acidic to neutral media. The recommended pH range is 1 to 9 for continuous use. They can tolerate pH levels up to 12 temporarily under controlled conditions, but sustained exposure to strong alkalis or pH above 12–14, especially at high temperatures, can degrade or destroy the glass lining.
What is the purpose of glass lining in reactors?
Answer
Glass lining protects the steel reactor from aggressive chemicals, particularly acids, and prevents contamination of the product. It also offers a non-stick surface that is easy to clean, making it ideal for applications in industries requiring high purity and corrosion resistance.
Can glass-lined reactors handle both acidic and basic media?
Answer
Yes, but primarily for acidic and neutral media. They are highly resistant to acids but limited in handling strong bases. Alkaline substances with a pH above 9 should be used cautiously, and strong bases above pH 12–14 should be avoided due to the risk of damaging the glass lining, especially at elevated temperatures.
How is glass lining integrity checked over time?
Answer
The most common method is the spark test, where a spark tester (AC or DC) is used to detect cracks, pinholes, or exposed metal beneath the lining. When the electrode contacts a damaged area, a visible spark appears, indicating that the glass has failed at that location and needs repair.
Conclusion
Glass-lined reactors are ideal for applications requiring chemical resistance, product purity, and durability. With proper selection, process design, and regular maintenance, they ensure long life, safe operation, and contamination-free processing. They are the first choice for handling acidic and reactive chemicals, thanks to their unique construction and performance.
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