Seek advice on methods to prevent clogging in dust-heavy gas sampling probes
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High-dust gas sampling probes generally have filtering devices installed at the probe tip, but these devices tend to get clogged. Although there are many related patents, practical use shows that the situation is not very good – the backwashing effect is inadequate, clogging occurs easily, and maintenance requirements are high. As the title suggests, is there any better solution? Please advise.
Why doesn’t the original poster consider using a direct-measurement dust concentration detector with a probe that is inserted into the sample, thereby avoiding the need for extensive maintenance?
Many methods do not involve direct measurement of dust; for example, the ultraviolet spectroscopy analyzers used in CEMS are used to analyze sulfides/nitrides, etc. On-site measurements present the following problems: large pressure fluctuations and inaccurate readings； High dust content affects spectral transmittance ； The dust content is high, resulting in high maintenance costs.
What the original poster is referring to is probably the sampling method, and indeed there is a problem with sampling. I’ve heard before that some people use a constant-speed sampling method to measure dust levels; they also need sampling probes, and again, due to high dust levels, it often happens that a sampling probe gets clogged before it can complete its sampling task. Later, I heard that they modified their dust sampling instruments. Originally, there was only one probe, but they added several more probes, so that when one probe gets clogged, they can immediately switch to another one. However, I’m not exactly sure about the specifics of how it’s done, haha. This can be considered their own modification technique – they didn’t share it with me. But you can use this as a reference for the approach
1. The sampling device should be installed at the top of the pipe, with the sampling tube extending to 1/2 of the pipe’s diameter. 2. Cut a 45° bevel at the front end of the sampling tube, with the bevel facing away from the direction of the airflow. 3. Use a larger diameter sampling tube; select a ball valve for the valve at the root, and then use a tube with a smaller diameter to run after that valve. 4. Install a filter after the root valve; it is best to use two stages of filtration.
It’s still the issue of high maintenance requirements; as long as a filter is in use, there’s a possibility of it getting clogged. If the dust has strong adhesion, maintenance requirements are high, and backblowing fails to achieve the desired results. For example, the analysis of exhaust gases from cement kilns is prone to clogging, and cleaning the filter elements is quite troublesome ； The analysis of high-temperature and coke oven gas in steel plants faces the same problems. It seems that many related products in the domestic market are just good enough to use.
You’re right; many devices in China are used in a substandard manner, and this is mainly because most people don’t pay much attention to the issue of dust. They don’t realize that addressing this dust problem can bring benefits to businesses, and they only think about how much it will cost to invest in dust detection equipment today. In reality, over the long term, resolving the dust problem can help companies save costs.
Many domestic patents in this area basically have little practical value~~~ It is said that the blast furnace gas sampling probe developed by model worker Liu from Wuhan Iron and Steel Group works well; I wonder if anyone has any information on this topic
I’m not sure what the design of your probe backflush system is. Generally, we first install a gas storage tank and use a PLC to control pulse-based flushing; if there is tar present, it’s possible to heat the area with steam before carrying out the backflush.