One of the world's most important polyamides is PA6, known as Perlon, which is produced by the polymerization of the monomer caprolactam (CPL). Due to the complexity of the production process, it is divided into 4 areas:
- Synthesis of Crude Caprolactam
- Separation and Crystallization of Ammonium Sulfate
- Purification and Processing of Crude Caprolactam
- Polymerization to PA6
In caprolactam production, cyclohexanone, hydroxylamine, and H2SO4 the base material cyclohexanone oxime is produced. By adding oleum and ammonia, crude caprolactam is generated, which is separated from the ammonium sulfate phase. Subsequently, the purification and concentration of the monomer caprolactam is carried out by extraction and crystallization. After polymerization, the polymer is finally separated from the residual monomers and purified.
LiquiSonic® Sound Velocity Measurement in Caprolactam
Application
The robust inline measurement system LiquiSonic® convinces in the context of quality monitoring and optimal process control in several measurement tasks:
- Incoming Goods Inspection
- Beckmann Process (Synthesis): H2SO4 / oleum
- Phase Separation of CPL and Ammonium Sulfate
- Crystallization Monitoring of Ammonium Sulfate
- Extraction: Concentration of CPL in Solvent
- Distillation: Concentration of Caprolactam in Water
- Reactor Water: Water in Caprolactam
The LiquiSonic® system can therefore be used both in high-precision concentration determination and in phase detection and process monitoring (crystallization). An internal limit value monitoring signals exceedances and shortfalls and sends the real-time information to the process control system.
Installation
The LiquiSonic® Immersion Sensors can be easily installed in the supply and transport lines. During the installation of the LiquiSonic® Sensors no bypass is necessary and dead spaces are avoided.
The LiquiSonic® Controller 30 can be connected to up to 4 sensors. This makes it possible to monitor multiple measuring points simultaneously.
Typical measurement ranges:
Concentration range Caprolactam: 70 to 100 wt% Temperature range: 80 to 130 °C
Concentration range Caprolactam: 0 to 10 wt% Temperature range: 20 to 70 °C
In goods receipt:
Concentration range Oleum: 0 to 30 wt% Temperature range: 10 to 60 °C
Customer benefits
The robust sensor construction and the choice of special materials, such as HC2000 or PFA, ensure long system uptime. Additionally, SensoTech offers sensors with appropriate ATEX, IECEx, and FM certification. LiquiSonic®reduces time-consuming laboratory measurements:
- Time required: 1 h per day
Through LiquiSonic® the concentration of residual caprolactam (residual monomer) is minimized, optimizing plant productivity.
LiquiSonic® ensures a high-precision analysis of the caprolactam concentration with continuous data recording. The measurement system is also successfully used for the rapid phase separation between caprolactam and ammonium sulfate. AdBlue® is essential for quality control. LiquiSonic® determines the urea concentration inline, allowing immediate response to disturbances and deviations.
