Help needed regarding issues with acetylene mist eliminators
Thread Content
Dear experts, my company uses a wet acetylene process with sodium hypochlorite for cleaning; there is an acetylene cooler after the neutralization tower. As part of subsequent technical upgrades, an acetylene demister was added after that cooler. However, the water removal effect is not very good at present. The demister uses CECO filter elements. Are there any colleagues who also use demisters? How effective are they?
This post was last edited by luoli519 on 2016-6-22 at 12:11. In wet acetylene systems, the gas stream contains a significant amount of liquid droplets, electroslag, and crystalline deposits formed from salts and alkalis. For demisting, dynamic gas-liquid demister separators with good anti-clogging properties and low operating pressure are typically used, such as high-efficiency vane-type gas-liquid demisting and defogging separators. If a cartridge-type filter is used for the acetylene demister and its water removal efficiency is not good at present, it is necessary to check the following aspects: 1. Is the filter cartridge a gas-liquid coalescing defoaming filter or a filtering filter? Only the coalescing demisting filter element uses a coalescing layer material, resulting in an excellent effect on gas-liquid demisting and separation ； Due to the material’s lack of efficient defoaming and coalescing properties, as well as the large price difference, the defoaming effect of these filter elements is naturally poor. 2. Filter element precision issue. If a filter element is used in the demister, it tends to get clogged easily, resulting in high operating pressure drop and making continuous smooth operation difficult ； It is necessary to choose filter elements with a large pore size and low precision, sacrificing foam removal efficiency in order to extend the lifespan of the filter elements and reduce operating costs. Many owners find it difficult to distinguish between coalescing filters and regular filtering elements, and they are also unable to determine the precision of these filters; moreover, the price difference is significant, which makes it easy for them to be deceived. Owners must obtain more technical information on demister separators by communicating thoroughly with specialized separation technology companies, and enhance their ability to make technical judgments through comparative analysis and question-and-answer sessions. It is recommended to replace it with a feather-leaf type high-efficiency gas-liquid demisting and defoaming separator.
The CECO filter element mentioned by the poster likely refers to the fiber bed demister components, which are characterized by poor resistance to clogging. May I ask the original poster to what extent is the liquid separation effect not satisfactory? Is there any pre-treatment before the mist eliminator is used, as mist eliminators are not very effective at dealing with large amounts of mist carried in the fluid.
Does the owner’s defogger have differential pressure gauges at the front and back, and what is the pressure difference? How is the drainage? Is there a demister bypass? If so, turn on the bypass first to maintain production, and then disassemble the demister to take a look. Acetylene gas inherently contains water mist, and carbon steel equipment inevitably develops rust and other contaminants. The filter element of the demister should be removed and inspected every six months or so; it’s best to clean it if possible and then continue using it, otherwise it needs to be replaced.
I am from CECO. Could you please be more specific about your question? You can call me at 13585961992; it’s Engineer Wang
What is the pressure of acetylene gas? At 80-90 KPa: the temperature must not be lower than 3 degrees Celsius, and it should be kept between 3.5 and 5 degrees Celsius. When the pressure is between 90-100 KPa, the temperature must not be lower than 2 degrees Celsius; it should be maintained between 3-5 degrees Celsius. If a high pressure difference across the filter element is detected at the beginning, the temperature should be increased to 5-8 degrees Celsius, and then the temperature should be reduced gradually once the pressure difference decreases. Especially when driving for the first time, if you can’t drive well, traffic jams will occur immediately; if you don’t handle the situation correctly, the jams will get worse.
Hello, friend. We also work in relatively quiet positions. I think we talk too much; let’s focus on other things for now.
Original poster, we didn’t use this setup, but I’m really interested in knowing why you chose to use a demister – our manufacturing process is the same as yours.
Our two demisters are connected in parallel; one is equipped with a filter element while the other is empty. Last year, during operation, the pressure difference reached around 10 KPa, which affected the loading capacity and caused the demisting function to stop working, leading to freezing and dehydration instead.