94- Tape-type feather leaf separator used as a demisting separator in the waste gas scrubber tower for the acetic anhydride project

In recent years, the standards for exhaust gas emissions from chemical plants have become increasingly strict. Chemical companies are required to make significant efforts in exhaust gas treatment, by seeking reliable environmental protection companies that offer effective exhaust gas treatment technologies and equipment for use in such processes. The treatment of waste gas generated by acetic acid and acetic anhydride plants is no exception.

However, in the waste gas treatment industry, environmental protection companies equipped with genuine waste gas treatment technology and equipment are not easy to find. For example, a acetic acid manufacturing plant in East China used a scrubber provided by an environmental protection company in Shanghai, along with its own exhaust gas demister, to treat the factory’s waste gases. As a result, the exhaust gas emitted from the scrubber contained many acid-containing droplets and mist, causing significant pollution in the surrounding area. The local environmental protection authorities ordered the factory to make corrections.

This post was last edited by luoli519 on 2019-3-5 at 16:10. The washing tower demister initially provided by this Shanghai-based environmental protection company for its clients was a traditional, simple mesh-type demister. Since the exhaust pressure from the scrubber tower is almost at atmospheric pressure, and the initial operating pressure drop of the wire mesh demister was too high, the exhaust gas got trapped inside the tower, preventing proper discharge. This supplier switched to another type of custom-made mesh with a significantly lower bulk density; although the pressure drop was reduced, the exhaust gases emitted contained visible acid droplets that fell in the surrounding area. Furthermore, as the operating time increases, the wire mesh demister continues to corrode and its wires break, resulting in an increasingly severe issue of acid droplets in the exhaust gases.

Thus, this environmental protection company in Shanghai obtained a set of baffle demisters from a demister manufacturer in East China to replace the wire mesh demisters. However, the property owners reported that tests conducted by the local environmental protection agency showed no improvement in the amount of acidic droplets in the exhaust emissions.

Indeed, many property owners have reported that in the gas-liquid demisting components installed in their systems, whether it was wire mesh types at first, which became damaged due to corrosion, or Chevron baffle types later on, there was little change in the amount of liquid droplets and foam in the outlet gas phase; it seems that no matter what type of gas-liquid demisting component is used, its effectiveness in removing such droplets and foam remains limited.

This post was last edited by luoli519 on 2019-3-5 at 16:13. In fact, what these property owners see is only the surface appearance. The effectiveness of gas-liquid demisting separation depends not only on the type of internal components used, but also on whether accurate and reliable design configurations can be obtained through a systematic platform based on precise dynamic separation design. Domestic demister suppliers and universities will find it difficult to develop accurate platform systems for dynamic separation calculation and design within a short to medium term of 5–10 years; as a result, they often rely on rough estimates and intuitive judgments to come up with so-called technical solutions and cost estimates. Without obtaining accurate and reliable design configuration results through a design system platform based on precise dynamics separation, it is not possible to ensure the accuracy and reliability of the actual performance of gas-liquid demisting separation. The gas-liquid demisting separation internals used in owners’ installations were likely chosen based on rough estimates and guesswork: initially wire meshes were used, but when they became damaged they were no longer suitable; later, Chevron baffle plates were adopted, all of which were decisions made through estimation rather than systematic analysis. Although a demisting internal component was installed there, it did not exhibit any significant demisting and separation effect from start to finish. Forwarding creates an illusion; it doesn’t matter whether it’s there or not, *it’s taken for granted*. In fact, efficient gas-liquid demisting separation internals are essential; otherwise, process packages both domestically and internationally would not specify clear technical requirements at the aforementioned stages.

This post was last edited by luoli519 on 2022-11-30 at 18:29. Gas-liquid separation and degassing technology belongs to the category of precise kinetic separation technologies; accurate and reliable design configurations can only be obtained through a system platform based on precise kinetic separation principles, and these configurations serve as the basis for manufacturing the internal components. Simply by installing a certain type of demisting and separation internal component, significant demisting and separation effects cannot be achieved. In fact, even when using the most advanced vane separation internals, it is essential to have accurate and reliable technical solutions as well as precise configuration patterns, which are achieved through a precisely designed dynamic separation system platform as a fundamental prerequisite. Otherwise, without a sound technical solution and an accurate configuration structure obtained through the design of a precision dynamics separation system platform as fundamental prerequisites, even components made of gold would be utterly useless! This is why many owners have tried various types of demisting and separation internals, only to find that the demisting and separation effects differ little.

This environmental protection company went to great lengths to approach us for help. The exhaust gas emission conditions at the top of the waste gas scrubber tower of this acetic acid plant are as follows: 1. Operating temperature: 65℃ ； 2. Operating pressure: 1.08 BarA ； 3. Exhaust emission volume: 136,500 kg/h; 4. Vapor density: 1.05 kg/m^3; 5. Vapor viscosity under operating conditions: 0.019 cp ； 6. Estimated liquid volume in the gas phase: 1200 kg/h; 7. Density under droplet conditions: 980 kg/m^3.

This post was last edited by luoli519 on 2022-11-30 at 18:30. Given that the exhaust pressure from the scrubber is very low, the volume of gas to be treated is large, and the liquid droplets contained in it contain acetic acid which needs to be removed promptly, we recommend to our clients the use of vane separators.

The last edit to this post was made by luoli519 on 2022-11-30 at 18:30. The accurate and reliable performance parameters of the G50 type vane separator, obtained using NOVEL Company’s precise dynamics gas-liquid separation process calculation and design system platform, are as follows: 1. Type of exhaust gas demister: G50 type vane separator； 2. Internal component configuration type: tape-type ； 3. Operating pressure drop: not exceeding 0.009Bar ； 4. Separation efficiency: 4N level separation to remove liquid droplets and bubbles of 5.82 microns and larger in size ； 5. Operational flexibility: 15%-130% ； 6. Equipment material: SS316L.