On-line analyzer design, installation and commissioning should pay attention to the problem gas analysis system is not a simple combination of analysis instruments, it includes sampling system, pretreatment system, analytical instrumentation. The sampling system and the pretreatment system are the key to the whole analysis system, so it is necessary to consider the single analyzer at the same time:
1 sampling system considering good instrument
An efficient and reliable instrument sampling system is the key to the use of good instruments. In general, the Oxygen Analyzer to detect the gas through the instrument sampling system filtration, drying, cooling, decompression, steady flow and other links to deal with the conditions, to enter the instrument to detect. Therefore, it is important to make or purchase a suitable instrument sampling system according to different situations or by yourself. To explain is: the desiccant used in oxygen is not suitable for oxygen absorption of silica gel, molecular plug, etc., can use concentrated sulfuric acid, calcium chloride, phosphorus pentoxide. When the micro-test, the sample gas can not be washed by water, so as to avoid the water dissolved oxygen interference measurement results.
2 Consideration of the interference of the background gas
It has been known that there is a problem of background gas interference in the thermal magnetic oxygen separation instrument and the magnetic mechanical oxygen distributor. If the background gas contains a large number of no gas and NO2 gas, such as high magnetization gas, not suitable for the use of these two instruments. In the application of Zirconium oxide analyzer, if the measured gas contains H2, CO and other reducing gases, the reduction reaction will be used to consume oxygen, affecting the measurement value of the instrument is lower than the actual. These disturbances are sometimes not obvious in constant oxygen detection, but these problems must be noted when detecting the trace oxygen content. If the oxygen content in the high purity nitrogen products of nitrogen-making device should not exceed 1x10-5, it must be considered to remove the H2, CO and other reducing gases in the nitrogen by using the Zirconia Oxygen Analyzer. If an air separation unit had a zirconia-type oxygen distributor, to detect the oxygen content in nitrogen, the oxygen content in the process is generally about 4x10-6, the test results are always negative after the instrument is checked, and then a reduction gas filter is added before the sample gas enters the table, the problem can be solved. Again, for example, the oxygen content of the top of a catalytic reactor is tested, and the oxygen distributor is used as a thermo-magnetic oxygen distributor, at first, the catalyst is regenerated using the oxygen enrichment process, the oxygen content is about 3%~5%, and the instrument runs normally. Later, the catalyst regeneration was replaced by the poor oxygen regeneration process, the oxygen content was controlled below 1, then the influence of the background gas containing the anti magnetic gas appeared, the oxygen quantity was too small, and the instrument measurement result was sometimes negative.
3 Consider the electrical connection section:
On-line analysis instrument is more valuable instrument, in the air separation system electrical design stage should consider complete set Analyzer Analysis Cabinet power supply through UPS or voltage regulator, otherwise the instrument's power supply module is easy to damage, if the selection of imported analytical instruments should pay attention to foreign industrial power supply voltage and frequency and China's differences, The industrial power of some countries in Europe and America is ac110v60hz, and our country is ac220v50hz. Complete sets of analytical instrument system should be reliable grounding, grounding line and neutral line can not be common line, grounding resistance is less than 4 ohms.