How to address the high failure rate of Venturi tubes made of sulfuric acid
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We have a 20,000-ton sulfuric acid production plant that uses venturi tubes, foam towers, and electrostatic mist removal systems; during operation, the venturi tubes suffer from a high rate of damage. Our venturi tubes are lined with carbon steel, followed by lead and then graphite; however, the graphite layers get damaged very easily. Is this caused by nozzle erosion, or is there some other reason? Can other materials be used as a substitute? Such as titanium materials, etc.
It can be cast using lead, or a small amount of antimony can be added to enhance strength. Our company uses lead for casting, which results in very durable products; (it’s not difficult to create the molds and carry out the casting process by oneself).
The venturi nozzles in use now are made of lead-antimony alloy, K-type alloy, as well as pure tetrafluoroethylene. Pure titanium is not suitable for use in dilute acids. For the throat tube, carbon steel lined with lead is sufficient; if erosion is severe, the flow rate of the acid should be recalculated to determine whether the acid pump chosen is too large, resulting in high flow rates that shorten the lifespan of the nozzles and the overall structure. When using most materials, it is not enough to consider only the material itself – other process parameters also need to be taken into account.
The vast majority of venturi tubes are made of lead, and their tendency to fail is due to substandard circulating dilute acid. Or it may be due to improper operation; sometimes the dilute acid pump trips, causing high-temperature gas to enter the venturi and damaging it.
Thank you for the enthusiastic guidance from above. As a supplementary point, ours is an internal-spray shoot type Venturi; the nozzle is fine, but the conical tee of the Venturi is not up to standard. The Venturi tee is made of carbon steel lined with lead and then covered with graphite. The temperature of the flue gas entering it is 350–380°C, while the melting point of lead is 327°C. Even if some antimony is added, it increases hardness but should lower the melting point. The current damage is that the graphite blocks have become loose, with small pieces falling off. Is this due to poor manufacturing quality or excessive erosion? The excessive heat caused the lead to almost disappear, and in the end it corroded through the carbon steel casing. Is there any good solution?
Let me make one set for you to try! The throat is made of graphite plates. Also, what is the structure of your nozzle? What is the head of the pump?
Ceramic tubes can be customized; they are strong and resistant to corrosion
It seems that tantalum is the more suitable material, as it is currently the best choice for resisting sulfuric acid – it is corrosion-resistant and durable. The production of tantalum tubes and sheets in China is now quite advanced~~:lol Give us the drawings and specifications, and we’ll show you. wmmtlc@gmail.com
Titanium won’t work; use lead-lined graphite, with the graphite being impregnated with resin
Is your venturi of the internal injection type or external injection type? It’s better to use the internal injection type, as it saves a lot of trouble.
One set of equipment that we have removed had lead in it for over 30 years; it seemed to fetch a good price at auction later on!
I would like to ask: if an external acid cleaning cycle is used, what problems might arise with the process equipment? ?
The venturi is made of lead-antimony alloy, with a graphite-lined steel throat; it is a very mature type of equipment.