16- Exchange of experience in the selection and design, installation and operation, as well as maintenance management of demister systems in power plant desulfurization scrubbers

This post was last edited by luoli519 on 2023-10-3 at 17:14. Currently, in flue gas desulfurization scrubbers used in thermal power plants both domestically and internationally, regardless of whether the blades are of the “sine wave type” or “baffle type,” and regardless of whether the blade arrangement uses the conventional “FLAT type” or “ROOF type,” the liquid droplets captured by the blade modules still fall back into the rising flue gas like a “downpour.” Some of these droplets are then carried back up by the rising flue gas to the demister for further separation and capture, in a continuous cycle. The droplets in the flue gas are separated by the blade assembly to form individual droplets; this is a stage in the entire separation process ； The droplets separated from the leaf cluster falling back into the newly rising air currents and separating due to gravity represent another stage in the entire separation process. If the droplets separated by the blade assembly in the first stage cannot be separated from the flue gas by gravity during the second gravity sedimentation stage, the efficiency of the entire separation process is reduced. Are there any new advancements in technology that overcome the gravity settlement control issue present in the aforementioned technologies? The G50 type vane separator has achieved this breakthrough, offering substantial improvements in separation efficiency, operational flexibility, and maximum gas velocity. It has been adopted in industries such as petrochemicals, natural gas processing and transportation, coal chemistry, large-scale chemical manufacturing, offshore platforms, and onshore terminals. For more technical details on the G50 type vane separator, please visit the HaiChuan Chemicals Forum using the direct link https://bbs.hcbbs.com/thread-1354814-1-1.html.

Regarding the installation of the washing nozzles, it should be noted that thorough cleaning is necessary in all corners and dead zones behind the installation of the blade demisters. In particular, each blade has a front and a back surface; due to full contact with the gypsum slurry droplets carried by the flue gas, both surfaces of the blade are prone to scaling. Therefore, the washing nozzles need to spray cleaning liquid in opposite directions to rinse both sides of the blade, ensuring thorough cleaning on both surfaces. Therefore, it becomes necessary to use an angular spray setting sometimes. I once designed a washing scheme for blade demisters for an enterprise, aiming to address the differences in spraying density between the central and peripheral areas of each solid nozzle; to install corner nozzles to prevent liquid shortage in edges and corners; to use nozzles that spray in opposite directions in order to clean both the front and back surfaces of each blade; and to take into account avoiding the cancellation of the momentum of the cleaning fluid resulting from simultaneous cleaning in opposite directions, which could lead to insufficient liquid coverage in certain areas. Through this experience and opportunity, we can remind and share with fellow sailors.

Regarding the setup of leaf washing systems at various levels, some special cases also need to be discussed. For example, recently some thermoelectric companies have significantly expanded the capacity of their steam boilers, resulting in a substantial increase in the amount of flue gas generated. Yet, the flue gas desulfurization scrubbers still use old equipment, with only the density of lime slurry used for absorption and spraying increased accordingly. The super-speed flue gas passing through the demister carries more fine gypsum slurry, which settles on the leeward side of the secondary demisting blade assembly and causes scaling. I also observed slight scaling and crystallization on the leeward side of the secondary defoaming blades of the evaporator crystallizer’s defoamer during major overhauls at some factories. No wonder that some foreign companies specializing in separation technologies, when designing two-stage vane demister washing systems, also install a washing spray system on the leeward side of the second-stage vane demister (that is, at the air outlet end of the second-stage vane demister). However, these spray washing systems located on the leeward side of the secondary blade demister serve only as a backup; they are not activated during the normal operation of the evaporation crystallizer ； Only during the factory’s annual major maintenance, when inspections are carried out, if crystalline deposits are found on the windward side of the secondary vane demister, is it temporarily activated for cleaning; thereafter, it is turned off and remains closed at regular times. This is to provide further clarification.

This post was last edited by luoli519 on 2023-10-3 at 17:15. Additionally, the following professional discussion posts that I posted on the Haichuan Chemical Industry Forum are listed here for everyone to use as links to join the discussions: 13. Discussion on improvements to the inlet devices of cyclone separators in gas-solid separation applications; please visit http://bbs.hcbbs.com/thread-1614524-1-1.html to participate in the discussion. 14. Regarding the issues arising from the use of swirl tube/swirl plate demisters in the wet flue gas desulfurization process for boilers, please visit http://bbs.hcbbs.com/thread-1599605-1-1.html to participate in the discussion.

This post was last edited by luoli519 on 2023-10-3 at 17:16. 35. Discussion on the removal of liquid sulfur foam in the SO2 production unit of the sulfolane plant: http://bbs.hcbbs.com/thread-1616252-1-1.html.

This post was last edited by luoli519 on 2023-10-3 17:16: Discussion on the setting of the vane separator in the exhaust system of the vacuum pump in the distillation unit of the sulfolane plant, http://bbs.hcbbs.com/forum.php?mod=viewthread&tid=1616268.

37. Regarding the application of the C4 hydrocarbons/water coalescing separator in the MMA methyl methacrylate project, please visit http://bbs.hcbbs.com/thread-1617142-1-1.html to participate in the discussion. To be continued......

This post was last edited by luoli519 on 2023-10-3 at 17:16. For discussions on measures related to the removal of liquid droplets from the flue gas resulting from the mixed combustion of waste gas from chlor-alkali plants and coke oven gas, as well as heat recovery and cooling processes, please visit http://bbs.hcbbs.com/thread-1617257-1-1.html.

40. Regarding the unstable operation of the alcohol synthesis unit in the **device and the waste alkali liquid separator, which leads to problems in the operation of the subsequent coagulation separator, please visit http://bbs.hcbbs.com/thread-1620515-1-1.html to participate in the discussion. To be continued......

At present, for the demisters in flue gas desulfurization towers of the vast majority of power plants at home and abroad, the cheaper FLAT arrangement and the more expensive ROOF arrangement are primarily used. Both the FLAT and ROOF types of demister internals find solutions within the axial cross-section of the desulfurization tower.