In the PTA process, it is necessary to monitor the oxygen concentration of the exhaust gas of the oxidation reactor, the exhaust gas of the crystallizer, the loose gas of the filter cake of the filter dryer, and the outlet gas of the exhaust compressor, and more oxygen content analyzers are required.
In this process, the medium gas is a mixture of oxygen, nitrogen, carbon monoxide, carbon dioxide, acetic acid vapor, etc., which is characterized by strong corrosiveness and high humidity. If a zirconia principle analyzer is used, the acetic acid vapor and carbon monoxide gas will undergo an oxidative combustion reaction in the detection head, causing the instrument to be unable to function normally. In addition, the humid gas can easily cause the zirconium tube to burst, so the zirconia analyzer should not be used in this environment. The thermomagnetic oxygen analyzer has high requirements for the sample, which needs to be kept clean and dry, and there can be no corrosive gases, and it is obvious that these gases in the PTA device cannot meet the conditions. Previously, a magnetomechanical oxygen analyzer was installed at the outlet of the exhaust gas compressor, and during use, the detector was contaminated with acid vapor and even caused the detector to be scrapped, so the thermomagnetic and magnetomechanical oxygen analyzers were not suitable for use in such environments.
In the process of PTA, the electrochemical oxygen content analyzer system should be selected, which is composed of three parts: pretreatment, sampling and analysis, and the pretreatment part uses neutralization, dilution or adsorption to remove or dilute the medium in the sample gas that has an impact on the sensor measurement to the allowable concentration, so as to ensure the life of the analytical part and the measurement accuracy. All components of the oxygen content analysis system are made of excellent corrosion-resistant materials and imported polymer membrane filtration technology, which can effectively filter strong corrosive gases, avoid damage to the sensor, and have a long service life to ensure that the equipment can operate stably for a long time. The PTA unit of a company in Luoyang Petrochemical is equipped with 8 sets of electrochemical oxygen content analyzer systems, and the operation is in good condition.