165-Leaf Separated Demister for the Technical Upgrading of the Demister in Desulfurization Towers

What are the current structural types of mist eliminators?

From a structural perspective, the demisters and mist eliminators used in various desulfurization towers and absorption towers in industries such as petroleum refining, natural gas, chemicals, metallurgy, pharmaceuticals, and environmental protection often feature structures such as wire mesh fiber block structures, filter element structures, baffle plate structures, swirl tube structures, packing structures, and vaned separation structures. This technical article analyzes and discusses a case study of upgrading traditional desulfurization tower designs by replacing the packing and wire mesh demister systems with feather-leaf separated demisters.

The case presented in this post actually relates to the technical upgrade of the demister in the flue gas desulfurization tower used to handle the smoke with high dust levels and high sulfur content generated during the roasting of pyrite in the rotary kilns at Tongling Nonferrous Metals. However, the client clearly did not have a good understanding of the gas-liquid separation technologies used in such towers, and was deceived by a company based in Changsha, Hunan. Of course, this is also the consequence for property owners of low-bid wins in recent years.

For the sake of discussion, I will first post here the layout diagrams of the flue gas desulfurization tower and its demister provided by this Hunan-based company to the owners:

The roasting flue gas, rich in dust and SOx, enters the desulfurization absorption tower at the flue gas inlet e and moves upward into Zone A. Zone A is a packed layer of corrugated packing made of calendered perforated plates, where flue gas and the organic amine absorption solution flowing from top to bottom undergo desulfurization absorption. The smoke rises from Area A into Area B. Zone B is the organic amine liquid spray washing zone, where the organic amine liquid injected from the h-nozzle carries out further desulfurization absorption. The smoke rises from Area B into Area C. Zone C is the area in the desulfurization tower where gas-liquid separation, as well as foam and mist removal, take place. The purified flue gas undergoes gas-liquid separation at the upper part of the desulfurization absorption tower, and then is discharged from the tower through the flue gas outlet k at the top of the tower.

Unlike conventional desulfurization absorption towers, the demister installed in zone C of this desulfurization tower consists of PP random packing with a height of 450–500 mm and a wire mesh demister with a thickness of 150 mm. However, under fluctuating operating conditions, the flue gas discharged from the top of the desulfurization tower often contains a significant amount of organic amine liquid, which enters the downstream gas transmission pipelines and causes severe liquid accumulation. This leads to poor flue gas discharge, high operating pressure drops, as well as substantial losses of organic amine liquid; consequently, the operational and maintenance costs for such systems remain high. This is also the main reason why Tongling Nonferrous Metals intends to carry out further technical upgrades after suffering losses at hands of this company in Hunan. It should be noted that any gas-liquid separation technology, including defoaming and demisting technologies, belongs to the category of kinetic separation techniques. It is not possible to rely on experience alone – through guesswork, arbitrary decisions, or simply imitating existing methods – as many companies at home and abroad do; such an approach often leads to serious consequences for the equipment in use.

This post was last edited by luoli519 on 2020-10-20 at 11:40. Let’s take a look at the actual operating conditions of the foam remover and mesh foam remover used in this desulfurization absorption tower: Gas phase: Flue gas after desulfurization (1) Gas flow rate: 30,000–60,000 Nm3/h (2) Pressure: 500 Pa(g) (3) Temperature: 40°C (4) Density: 1.2 kg/Nm3 Liquid phase: Organic amine absorption liquid (1) Liquid flow rate: 20–30 m3/h (2) Pressure: 500 Pa(g) (3) Temperature: 42°C (4) Density: 1.07 kg/L (5) Surface tension: 70 mN/m (6) Viscosity: 0.74 cp

Additional information on the existing desulfurization tower and demister: The diameter of the desulfurization tower is 3500 mm, with a steel lining made of PO material. Currently, 450-500 mm of bulk foam removal packing is installed, and 150 mm for one layer of the mesh foam remover. The tower diagram is attached. NuoWei Energy Technology Company is required to use vane-type demister to achieve 99% mist removal, with the pressure loss in the demisting section being less than 600 Pa.

The main technical details of the anti-clogging vane-type demister for the desulfurization tower, which were developed by our side using the owner-provided operating condition data through NOVEL’s precise dynamics separation technology and configuration design system platform, are as follows: 1. Type of demister: Vane-type demister； 2. Separator model: NOVEL P4-3900-0.4; 3. Pre-distribution coalescing internals set model: NOVEL G50D ； 4. Model of the precision vane-separated internal component set: NOVEL P4-D BANK-192/4-30-EDP; 5. Model of the anti-siphon short-circuit liquid dropping internal component set: NOVEL G50LD ； 6. Separation efficiency: 99.9%@8.31micron plus ； 7. Operating pressure drop: 0.568 kPa.

This post was last edited by luoli519 on 2024-4-7 at 11:08. The ‘Data Tables’ showing the anti-clogging vane-type demister for the desulfurization tower, as output by our system platform based on NOVEL’s precise dynamics separation technology for calculation and configuration design, are as follows: