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High-pressure catalytic systems
High-pressure catalytic systems frequently used for Air Pollution Control in the production of purified terephthalic acid (PTA). They are based on the catalytic process.High-pressure catalytic systems can be used for all exhaust gases produced under high pressure.
High-pressure catalytic system benefits
- Energy recovery from the expansion of the purified process gas (for example in a turbine)
- Autothermal operation
- Anti-corrosive design available
- Low maintenance levels and long maintenance intervals. The maintenance cycle of the high-pressure catalytic system is generally the same as that of the production system.
- Dürr has extensive experience in the field of PTA.
- Customers can choose the most suitable catalyst material (no requirement to use a specific manufacturer).
- A comprehensive service portfolio with local engineers.
- The system has a small footprint. The exhaust gas can be taken directly from the production line at high pressure. As a result, the individual components and the overall system can be significantly reduced in size.
Operating principle High-pressure catalytic systems
The high-pressure exhaust gas which contains methyl acetate, methyl bromide, and carbon monoxide, can be purified directly without prior expansion and fed into the high-pressure catalytic system.
The exhaust gas is first heated using a heat exchanger that is powered by steam or preheated air. To improve the energy efficiency of the system, the temperature of the exhaust gas is increased using an air-to-air heat exchanger, which is heated with clean air, until the gas reaches the operating temperature of the catalyst.
After the organic pollutants have been converted in the catalyst, the purified exhaust gas is cooled, and the heat is recovered in the air-to-air heat exchanger. The cooled and purified exhaust gas, which is still under pressure, is then returned to the production system. The energy from the gas can be recovered in a downstream expander.
Application areas High-pressure catalytic systems
Dürr's standard solution for the production of purified terephthalic acid (PTA) and for other applications that generate exhaust gas at high pressure is the high-pressure catalytic system. PTA is manufactured in the petrochemical industry and this is where the high-pressure catalytic systems are primarily used.
Technical specifications High-pressure catalytic systems
High-pressure catalytic systems are designed for use where exhaust gases containing the following pollutants are produced at high pressure:
- Methyl acetate
- Methyl bromide
- Carbon monoxide
In the typical PTA production process, the pollutant burden for the high-pressure catalytic system fluctuates within a very narrow range.
An important feature of the design of the system is the choice of the correct catalyst for the pollutant burden to allow for long production cycles.
Construction High-pressure catalytic systems
The catalyst, which removes the organic pollutants from the exhaust gas, lies at the heart of the high-pressure catalytic system. To enable the catalyst to operate within its ideal temperature window, upstream heat exchangers are used that heat the exhaust gas to the necessary temperature before it reaches the catalyst. The arrangement of the components in a high-pressure catalytic system makes it possible to transfer the exhaust gas from the production process and purify it without needing to modify it in any way. After being purified, the exhaust gas is returned to the manufacturing process at its existing overpressure.
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