Water is dripping at the outlet of the desulfurization tower; could someone expert please take a look and tell me what’s wrong with this design?
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Project background: Flue gas desulfurization tower of a certain enterprise, with two fans delivering a maximum total air volume of 260,000 m³/h; the tower diameter is designed to be 6 m (see the system diagram for detailed structure), and the flue gas flow velocity is 2.55 meters/second. Single-alkali desulfurization is planned to be used, equipped with 4 37KW water pumps with a flow rate of 290 m³ and a head of 24 m. Problem description: The owner’s furnace has not been started yet. The two fans were turned up to full speed at room temperature for a test run, and severe water leakage was observed, as if it were raining. Observations showed that a large amount of water was carried by the flue gas to the tray surface, which at one point caused the tray recovery tank to overflow; as a result, the recovery pipeline had to be connected to the desulfurization solution tank. Details: By adjusting the fan’s frequency to 39 Hz, the water splashing issue no longer occurs. Above 40 Hz, water will splash even if only one layer of nozzles is activated. Question: The two-layer double-hook C-type mist eliminators at the back end (placed one on top of the other without any gap in between) are not capable of handling such a large amount of liquid droplets, which is why water splashing occurs. The mist eliminator located in the air duct at the top serves only as a supplementary measure; its mist-removal efficiency is not taken into account when the flow rate exceeds a certain level. At this flow rate, an excessive amount of water is carried onto the tray, which is abnormal. Could it be that the design of the spray nozzles and pumps is inadequate, resulting in a high proportion of ultra-fine mist particles, which then coalesce into larger droplets as the flue gas passes upward through the tray? Furthermore, according to the data provided by the nozzle manufacturer, at the pump’s head and flow rate, the droplet size is 1800–2400 μm. Try again after preparing to ignite it; the flue gas temperature is around 40-60°C. Will this lead to a significant improvement in the issue of water droplets drifting? Above, I’m not sure if it has been explained clearly enough; I hope the experts can give me some advice
I’m not sure why, but I can only upload one image; the spray diagram cannot be uploaded. There are 36 1-inch silicon carbide vortex nozzles per layer, the water pump has a head of 24 meters and a flow rate of 290 m3.
Should it be uploaded using a computer or a mobile phone?
Uploaded from a computer; the first image was uploaded successfully, but the second one kept showing as pending upload. I tried several times with the same result
It must be due to the gas velocity exceeding the design value, right? Or the design height is not sufficient.
The flow velocity in the demister section is estimated to be too high, failing to achieve the effect of mechanical demisting
Problem analysis: 1. In typical designs, the empty tower flow rate is too high; such a high flow rate results in excessive pressure drop across the tower and increased mist entrainment. This has been confirmed by adjusting the fan’s frequency to change the exhaust volume； 2. The Type C demister is another form of swirl plate demisting; its demisting efficiency is generally moderate under conditions of high gas flow rates and large amounts of mist entrained. Its advantages are low pressure drop and low cost ； 3. The smaller the particle size of the spray water, the better the desulfurization effect; it has little to do with the mist droplets carried in the flue gas ； 4. Foam entrainment has nothing to do with temperature, but it is somewhat related to the water flow rate from the water pump ； Measures: 1. Reduce the volume of flue gas to be treated, or increase the tower diameter ； 2. Replace the demister with a wire mesh demister or a layer of high-density packing with a smaller diameter ； 3. It is possible to consider reducing the amount of water used for spray cleaning, provided that the desulfurization effect meets the required standards, and give it another try!
Simply put, the gas flow rate is too high, carrying the liquid away; it can also be said that the gravity pulling the liquid downward is less than the force of the gas pushing it upward. Being upstairs was the right choice indeed :)