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 manufacturing 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 H2Sonic velocity measurement4 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 monomer caprolactam is purified and concentrated by extraction and crystallization. After polymerization, the polymer is finally separated from the residual monomers and purified.
LiquiSonic® Sonic velocity measurement in caprolactam
Application
The robust inline measuring system LiquiSonic® convinces in the context of quality monitoring and optimal process control with several measuring tasks:
- Incoming goods inspection
- Beckmann process (synthesis): H2Sonic velocity measurement4 / 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 monitoring signals exceedances and underruns and sends real-time information to the process control system.
Installation
The LiquiSonic® immersion sensors can be easily installed in the supply and transport lines. When installing the LiquiSonic® sensors no bypass is necessary and dead spaces are avoided.
The LiquiSonic® Controller 30 can be connected with up to 4 sensors. This makes it possible to monitor several measuring points simultaneously.
Typical measuring ranges:
Concentration range caprolactam: 70 to 100 m% Temperature range: 80 to 130 °C
Concentration range caprolactam: 0 to 10 m% Temperature range: 20 to 70 °C
In incoming goods:
Concentration range oleum: 0 to 30 m% Temperature range: 10 to 60 °C
Customer benefit
The robust sensor construction and the choice of special materials, such as HC2000 or PFA, ensure long process uptime of the system. In addition, SensoTech offers sensors with appropriate ATEX, IECEx, and FM certification. LiquiSonic®reduces time-consuming laboratory measurements:
- Time required: 1 hour per day
Through LiquiSonic® the concentration of residual caprolactam (residual monomer) is minimized and thus plant productivity is optimized.
LiquiSonic® ensures a highly precise analysis of the caprolactam concentration with permanent data recording. The measuring 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, so that immediate action can be taken in case of disturbances and deviations.
