What is the composition of the lead-antimony alloy in the internal injection Venturi tube?
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Our internal spray Venturi tubes are constructed with carbon steel lined with lead and then covered with graphite. The flue gas coming from the waste heat boiler enters at a temperature of 350–380°C, while the melting point of lead is 327°C; although the addition of some antimony increases hardness, it should lower the melting point. I would like to ask experts: What is the appropriate ratio of lead to antimony in a lead-antimony alloy? Is it necessary to line the lead inside the cast venturi cone with graphite, or else will it not be able to withstand the high temperatures of flue gases and get damaged? Thank you!
The converging section of the Venturi tube must be made of materials such as graphite or KP1, in order to resist high-temperature corrosion. As for the throat section, it is best to line it with graphite plates. There are not many restrictions regarding the material used for the expanding section; it can be polypropylene, fiberglass-reinforced plastic, or lead – the choice depends mainly on the size of the equipment and the operating environment. As for the lead-antimony alloy you mentioned, antimony serves to enhance strength, and its proportion cannot exceed 4%; otherwise, microcracks will appear in the welding of the lead. Please refer to this. Feel free to contact me if needed; my phone number is 13465426288
The converging section of the Venturi tube must be made of materials such as graphite or KP1, in order to resist high-temperature corrosion. As for the throat section, it is best to line it with graphite plates. There are not many restrictions regarding the material used for the expanding section; it can be polypropylene, fiberglass-reinforced plastic, or lead – the choice depends mainly on the size of the equipment and the operating environment. As for the lead-antimony alloy you mentioned, antimony serves to enhance strength, and its proportion cannot exceed 4%; otherwise, microcracks will appear in the welding of the lead.
Since the expanded tube section is already part of the adiabatic evaporation washing section, its temperature is not above 300 degrees, so there is no need to worry about the temperature in this area. Typically, the amount of antimony added to the expanded tube is between 6% and 8%; the higher the amount of antimony, the better the strength, but the lower the corrosion resistance. However, if too little antimony is used, the strength becomes poor. Therefore, while ensuring sufficient strength, the antimony content should be reduced as much as possible.