Application modification of the Teledyne 6020 UV analyzer for H2S detection in natural gas: 0–5000 ppm

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This post was last edited by haoren46 on 2019-3-9 at 16:27. In overseas natural gas processing plants, the raw natural gas coming from gas wells contains large amounts of H2S gas (0-5000 ppm). Due to the severe corrosive effect of this H2S gas on equipment, it can also cause certain catalysts to become poisoned instantly during downstream processing, thereby severely disrupting the safety of production processes. Therefore, the accuracy and stability of H2S measurement in the feed gas are particularly important. Below is the data sheet for the H2S analyzer; it can be seen that the normal concentration of H2S can reach 0.37%, which is equivalent to 3700 ppm. This represents a significant challenge for ordinary online analyzers. H2S analyzer data sheet: Here, the user has chosen the Teledyne 6020 online ultraviolet analyzer, which features automatic zero-point calibration (with automatic zero-point calibration taking place every 3 hours by default). The measurement range is 0–5000 ppm. Since there are 2 measurement points on site, 2 such analyzers were also selected. Here, we use one of them as a case study for analysis and discussion. According to customer feedback, there is significant data drift at the site, and the standards gases are not very stable either. Although data is available, it cannot be used effectively at all; the system is essentially in a semi-abandoned state. Moreover, not many of the site owners know how to use this analyzer. The relationship among the site owners, the general contractor, and the suppliers is also very tense, with each party having its own difficulties. For some reason, the manager suddenly asked me to take charge of this project. I was also very surprised at the time; maybe it was just forcing things to happen? Anyway, death is inevitable in any case; so I took on this project as if it were a heroic act of sacrifice. After all, I had been working in the field of online analysis for 8 years at that time, and I wanted to try new challenges as well. It was only when I actually got my hands on this renovation project and inspected the site that I was stunned – the actual problems there far exceeded my imagination; the situation was even worse and more serious than what the client had described 1. The on-site air conditioning is not running. The site is in a desert area, where temperatures can exceed 40°C in summer; even with the doors closed inside the hut, the temperature stays above 50°C. It’s highly unlikely that the analyzers, including those used for pre-treatment, can function properly at such temperatures ； The outdoor temperature at the site at that time was 46°C. Upon inspection, it was found that the air conditioner might be lacking Freon; unfortunately, since we were abroad, this component couldn’t even be produced locally. We had to find someone locally who could repair the air conditioner; after purchasing Freon from India and filling it into the air conditioner, it finally started working properly. Working in the cabin is much cooler! ! ! To fill it with Freon, I found a local to do the job; it’s made in India. Actually, the people in India are quite skilled, O(∩_∩)O haha~ 2. After powering it up on site, some of the electrical modules of the Teledyne6020 would not heat up nor function. There were at least 6 modular components on site, and each one had to be taken apart individually for inspection; eventually, it was found that a circuit board had come loose and fallen off. It might be a long journey from within China to overseas; there is limited road transportation, and the road conditions are poor, causing bumps along the way. After inspection, after the power was cut off and that circuit board was reinserted, the system was restarted and powered on; after a 1-hour warm-up period, all components appeared to be functioning normally, the data was available, and the areas that were supposed to generate heat were indeed hot. The circuit board has fallen out of its slot. 3. The preliminary on-site processing is very simple and fails to meet the requirements; this issue is more complex, and I will explain it in more detail later ； 4. The measurement chamber of the field analyzer contains a small amount of condensate oil, which prevents it from functioning properly and requires frequent cleaning ； There is a small amount of condensate oil in the measurement room. 5. The on-site maintenance staff are mostly locals, and they are completely confused ； I can’t speak Chinese or English; I only know a little Russian. Alright! I’ll also pick up some Russian on the spot ； After all, the customer is king, right? That’s about it for the on-site issues; I’ve outlined them roughly. The main problem lies in the third point; for various reasons, it was not possible to obtain the original drawings, so I drew a rough sketch based on the actual conditions on site. As for the original system diagram before the modification, I took a quick look at the site – the feed gas contained a large amount of condensate oil. The samples were taken on-site, then sent through preprocessing before being fed into the analyzer. The entire pretreatment system does not have any condensation devices or oil removal devices. During that period, I developed several proposals, and in the end the third option, which offered the best cost-performance ratio, was chosen (I had prepared five proposals for this renovation project). The details are as follows: The dedicated natural gas probe for Genni A+ takes samples from the outlet of the manifold; the pressure of the sample gas is reduced directly from 7.2 MPa to 0.2–0.6 MPa. After passing through the electric heating pipeline, it enters the analysis chamber, where it first reaches a safety valve (set at 0.6–0.8 MPa) to prevent overpressure from causing issues ； One stream is processed through an oil-gas separator; after being depressurized to 5–15 PSI, it passes through a Genni A+ membrane filter. Another stream is directly vented via a bypass flow meter, while the third stream passes through a filter and then through a sampling flow meter before entering a Teledyne 6020 analyzer; the exhaust gas after analysis is then vented ； The materials that need to be added are listed in the table below: List of materials for modification, System flowchart – revised version, Physical diagram after modification – the areas marked in red are the key areas that require modification. After these modifications are completed, the automatic zero-point calibration of the Teledyne 6020 analyzer, which originally took place every 3 hours, can now be extended to every 12 hours, thereby ensuring the stability and accuracy of the analyzer’s data. This approach saves a large amount of standard zero-point gas and reduces the amount of maintenance work required. The liquid discharge from the gas-liquid separator is carried out based on the actual oil and water content in the process pipeline ； The customer is also very satisfied with the on-site renovation, and virtually all their previous complaints regarding our company have been resolved. Later on, a group of three to five people worked with me to take care of these two devices; after three months of training, they were able to carry out maintenance tasks independently. If any experts are interested in knowing more detailed information, or have any other insights or suggestions, we can discuss them together.