demister

For reference: Mist eliminator model, alternative names for mist eliminators, main features. Mesh Pad – a wire mesh mist eliminator with high efficiency in capturing acid mist particles ranging from 3 to 20 µm. The Co-knit Mesh Pad hybrid mesh demister has a high efficiency in capturing acid mist particles with sizes of 2–20 µm, and its performance is superior to that of the pure mesh demisters mentioned above. The CK type (CK-IP) economy version has a high capture efficiency for acid mist in the 1–3 µm range; it features a specially designed mixed-wire mesh capture layer, giving it better anti-clogging performance than the CS type. Its service life and demisting efficiency are both superior to those of wire mesh demisters. It is also easy to install, and convenient for removal, cleaning, and replacement. It has an anti-cavitation control layer. The CS type (CS-IIP) economy version has a high efficiency in capturing acid mist in the 1–3 µm range; its performance is better than that of mesh mist eliminators and CK mist eliminators. However, it clogs more easily than the CK type and is generally not suitable for use in dryers. It has an anti-cavitation control layer. The ES type, which is energy-efficient, has a high efficiency in capturing acid mist with particle sizes of < 1 µm; it can meet the requirements for mist removal at levels below 20 mg/Nm3. Typically, the acid mist level downstream of one absorption tower is around 5 mg/Nm3. The fiber collection layer is controlled by a computer, with the machine performing the winding ； It has an anti-cavitation control layer. HE and HE+ types are high-efficiency types; they have a high capture efficiency for acid mist with particle sizes of < 1 µm, and can meet requirements for mist removal at levels of 20 mg/Nm3 or lower, as well as even more stringent requirements. The HE+ type has an anti-entrainment control layer. The FP type, which is installed on-site, has a high efficiency in capturing acid mist with particle sizes of < 1 µm; it is mainly used in factories where clogging occurs frequently, requiring regular cleaning and replacement of the fiber bed. Customers can replace the fiber bed themselves on site. XP (AP) type – super-efficient: it exhibits a high capture efficiency for acid mist with particle sizes of < 1 µm. Compared to ES units of the same size, it features a more uniform fiber bed, lower pressure drop, and better performance. It has an anti-cavitation control layer.

Our drying tower uses a stainless steel 316 wire mesh demister, while the first and second absorption towers employ fiber demisters

This post was last edited by luoli519 on 2016-5-27 08:13. Drawing on my many years of experience in the design and promotion of high-efficiency gas-liquid, gas-solid, gas-liquid-solid, liquid-liquid, and gas-liquid-solid separators both domestically and internationally, I would like to share my insights regarding the similarities and differences between mesh demisters and fiber demisters for everyone’s discussion and reference: Similarities between mesh demisters and fiber demisters: 1. Both mesh demisters and fiber demisters use fine fibers as their basic material; these materials can be metal fibers, glass fibers, synthetic fibers, plant fibers, or combinations thereof, and they are manufactured through processes such as dispersion, weaving, winding, melt spraying, or sintering. 2. The principle of foam removal is to create a cellular structure through the interweaving and bridging of fiber filaments, thereby preventing the particles carried in the airflow from passing through; these particles are then aggregated into larger droplets. Under the effect of gravity, these droplets break free from the surface tension holding them to the fibers and fall back into the airflow, completing the first stage of foam separation. The droplets that enter the airflow have some of the larger ones manage to break free from the airflow due to their own gravity, reaching the liquid collection area at the bottom of the separator where they are completely separated from the airflow – this constitutes the second stage of the separation process. Small liquid droplets of a certain size that fall into the airflow remain suspended in it and are carried away from the demister, making it impossible to achieve demisting and separation. 3. The fiber filaments interweave with one another to form a cellular structure; the sizes of these cells follow a Gaussian distribution and exhibit unevenness. While small-sized carriers are blocked and intercepted when passing through smaller pores, larger-sized carriers may penetrate larger gaps and escape. Therefore, with a lattice-type blocking demister, it is difficult to achieve a specified high separation efficiency for aerosols of a given size; in other words, blocking demisting cannot be considered a truly quantitative and efficient separation method. For example, screen-type demisters find it difficult to meet the requirement for 100% quantitative separation of liquid droplets larger than 5.7 microns. 4. The droplets that are trapped and accumulated within the pores formed by fiber bridging, on the one hand, flow downward due to their own gravity; on the other hand, they remain attached to the fibers because of surface tension. Additionally, they are pulled forward by the flowing air currents, allowing them to pass through the fiber layers. As a result, these droplets become elongated and smaller, enabling them to pass through pores of the same size or even smaller ones. The droplet that has penetrated the fiber layer, as the airflow cross-section expands suddenly and the flow velocity decreases abruptly, its own surface tension causes the previously elongated and reduced droplet to return to its original spherical shape. Therefore, the size of the pores formed by fiber bridging differs significantly from the size of the liquid droplets that are removed. The pore size distribution data resulting from fiber interweaving and bridging cannot be used to represent the foam removal size, as there is a significant difference between them. 5. Due to the large specific surface area of the fibers, the continuously increasing droplets and foam tend to accumulate within the fibrous components, forming thick liquid films. This facilitates the occurrence of \"liquid flooding\" and \"liquid surge\", which leads to the flow channels being covered by these liquid films and thus becoming blocked, creating a vicious cycle in foam removal and separation. Therefore, the barrier-type fibrous demister is not suitable for applications with high liquid load in the gas stream and high gas flow rates. To handle gas-liquid demisting separation with a high liquid content, a pre-separator must be installed to remove the excess liquid in advance, thereby meeting the required conditions at the inlet of the barrier-type fibrous demister and ensuring its efficient operation. 6. The pores formed by fiber interweaving and bridging exhibit excellent blocking efficiency for carrying solid particulate matter whose equivalent diameter remains relatively constant during the separation process; they are thus very suitable for gas-solid and liquid-solid separation applications. However, after these solid particles of different sizes carry impurities into the fiber separation element, the larger particles remain on the surface of the fiber element and accumulate over time; this surface accumulation can be largely regenerated through backflow of air or liquid flow. On the other hand, tiny solid particles penetrate deep into the middle and deeper layers of the fibrous structure, where they are trapped by the surrounding fiber filaments, making it difficult to achieve ideal regeneration through fluid backflow. The smaller the pore size, the worse the effect of fluid backflow on regenerating the particles in the middle and deeper layers of the fiber media, to the point where regeneration may not be possible at all. 7. The barrier-type fibrous demister is not suitable for use in scenarios where gas streams containing solid particles, gels, and a large amount of foam need to be dehumidified. Consider using baffle demisters or swirl plate demisters, which have a strong ability to resist particle clogging but a lower demisting efficiency. Alternatively, a feather-leaf type high-efficiency gas-liquid demisting and defogging separator can be used. It not only boasts highly efficient demisting performance that is superior to that of screen-type demisters, but also has the same resistance to clogging by solid particles as baffle or swirl plate demisters. Its internal components can operate for an extremely long period without the need for regular replacement, eliminating the requirement for spare parts. As a result, its operation and maintenance costs are very low. It has been adopted in new process packages and projects both domestically and internationally, as well as in the technical upgrades of existing screen-type demister systems.

This post was last edited by luoli519 on 2016-5-27 08:21. Differences between wire mesh demisters and fiber demisters: 1. Their names are different, as they are translated directly from foreign languages. Mesh Pad Type Demister: wire mesh mist eliminator; Fibre Type Demister: fiber-based mist eliminator. 2. Wire mesh demisters generally refer to demisters made from fibers with a relatively large diameter; the drawing properties of these fiber materials are not very good, and they are mainly made of metallic materials and polymers that are difficult to draw into fibers ； For example, wire mesh demisters, PVC wire mesh demisters, PVDF wire mesh demisters, PTFE wire mesh demisters, and so on. Fiber demisters refer to demisters made from fibers with very fine diameters; these fibers have good drawing properties, and are primarily made from plant fibers, glass fibers, and polymers with excellent drawing properties ； For example, PP fiber type demisters, glass fiber type demisters, PP composite glass fiber type demisters, etc. 3. Wire mesh demisters are generally made from a single material in the form of nets, felts, pads, blocks, cones, cartridges, etc. Fiber defoamers can be made from a single material, or they can be constructed using two or more materials or even through coating composites; their shapes are typically in the form of mats, pads, blocks, cones, cartridges, etc. 4. Screen-type demisters have large pore sizes resulting from the interweaving and bridging of fibers; their size distribution is wide, their porosity is high, their ability to block and separate particles is poor, and their pressure drop is relatively low. Fiber demisters feature fine pore sizes resulting from the interweaving and bridging of fibers; they have a narrow size distribution, low porosity, excellent separation capabilities through blocking and interception, and relatively high pressure drops. 5. Screen-type demisters are generally used for primary demisting and separation, with no strict requirements regarding the direction of airflow ； In accordance with national and industry standard requirements, it is capable of removing liquid droplets larger than 600 microns under dynamic airflow conditions, with a macroscopic separation efficiency of over 97%. Fiber demisters are generally used for precise demisting and separation, requiring the airflow to flow in a direction from low flux toward high flux along the normal direction ； In the two-stage combined coalescing separator consisting of deep coalescing in a fiber demister and a subsequent vane-type liquid mist capture chamber, 99.99% removal of liquid mist particles with sizes of 1–3 microns and significant Brownian characteristics can be achieved under dynamic airflow conditions. The second-stage vane-type foam capture chamber is used to capture the small and medium-sized foam droplets that remain suspended in the exhaust airflow after coalescence and sedimentation in the first-stage fiber demister. It is particularly important to note that, as an ultra-precise coalescing separation demister, it usually consists of multiple layers such as an inner metal support layer, a solid particle interception and filtration layer, a micro-foam and mist coalescing layer, a droplet release layer, and an outer protective layer. But it must be emphasized once again that the more sophisticated the demister, the less it can handle \"coarse\" liquids; the amount of liquid in the incoming air should

It depends on the price you can afford; generally, wire mesh demisters are used in drying towers, while fiber mist eliminators are a better choice for the first and second stages of absorption

This post was last edited by luoli519 on 2016-5-27 10:21. It’s not appropriate to use a fiber demister alone. This is the result of domestic companies attempting to adopt fiber demisters from abroad without fully understanding how to use and configure them. The fiber demister can indeed block, intercept, and coalesce even smaller liquid droplets, but does the amount of liquid carried by the airflow meet the inlet requirements of the fiber demister? The fiber demister prevents some of the larger-sized liquid droplets formed by interception and coalescence from falling into the liquid collection area and being separated; whereas those liquid droplets that have grown in size but remain suspended in the airflow at the outlet of the fiber demister – droplets whose size after coalescence is greater than that of the liquid droplets entering the fiber demister – are carried away from the tower system by the airflow. It can be confirmed through detection methods such as infrared. Generally speaking, when a fiber demister is used, it is necessary to install a fan-type high-efficiency gas-liquid demisting and separation device at its downstream end to capture those liquid droplets that are larger in size but still suspended in the airflow exiting the fiber demister. For example, coalescing separators and natural gas coalescing filter separators are very common equipment used for advanced gas-liquid separation; hundreds of such two-stage coalescing filter separators are in operation on the West-East Gas Pipeline. Otherwise, the liquid droplets and mist in the exhaust gas become larger in size due to coalescence in the fiber demister, compared to their size in the inlet gas before passing through the fiber demister; this makes it easier for these droplets to cause corrosion and damage to the equipment in the downstream pipelines. “The “triple acid” equipment belongs to the traditional industry; due to the fact that domestic understanding of gas-liquid separation was still at a preliminary stage at that time, there were many knowledge gaps, which led to mismatches between the equipment and its requirements – in other words, good horses being paired with poor harnesses, or inferior horses given fine saddles. There are also fewer opportunities for technical exchanges and improvement between those in traditional industries and those in emerging industries. Only when the operation of the device encounters problem bottlenecks is there an opportunity to continuously consult with professional technology companies and specialists in separation technologies. Listen to multiple perspectives, make comparisons, and then draw your own conclusions.

This post was last edited by springflower on 2016-5-28 at 20:32. All my colleagues in the field of sulfuric acid mist eliminators are admirable for the depth of their expertise, their market share, and the quality of their services. However, I’m not sure about your company’s market performance in the field of demisters for the sulfuric acid industry What about the experience that other companies have accumulated over more than a decade or even several decades in the sulfuric acid industry? We are very pleased to have new colleagues joining us in contributing to environmental protection efforts. However, does your company have any knowledge regarding mist eliminators in the sulfuric acid industry? Has any research been done on the workflow under normal operating conditions? Are the purification criteria known? What kind of damage will occur once a certain indicator is exceeded? How significant of an impact can poor defogging performance have on the device?

“The \"tri-acid\" industry is considered a low-end, traditional sector both domestically and internationally; it lags behind emerging industries such as petrochemicals, coal chemicals, fine chemicals, and environmental protection technologies, both in terms of its manufacturing processes and in terms of local technological upgrades. It is precisely because the \"three acids\" industry has relied on empirical design and equipment over the past few decades, resulting in a failure to improve the level of tooling technology, that the problems associated with these \"three acids\" facilities continue to arise. In recent years, there has been a push for industrial structure adjustment and technological upgrading, with very strict regulations on pollutant emissions from traditional industries, especially those that generate significant pollution. Business owners are seeking various ways to upgrade their technologies in order to meet strict environmental emission standards ； At the same time, it reduces the operational and maintenance costs for enterprises. Many owners of \"tri-acid\" plants have turned to us for help in carrying out technical upgrades and modifications to their existing separation systems. Furthermore, hydrogen fluoride production facilities face more severe equipment corrosion compared to sulfuric acid production facilities, along with stricter environmental, safety, and emission requirements. The owners of hydrofluoric acid plants have also turned to us for help in carrying out technical upgrades and modifications to their existing separation systems. I think this indicates an unstoppable trend. We welcome industry professionals facing similar device-related issues to contact us for consultation and technical upgrade solutions.