Installation of pipelines on both sides of the sulfur jacket valve
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In the installation section of the sulfur recovery unit, the designers wrote the following: In areas where insulated jacket valves are used, the pipes before and after the valves must have a jacket structure. The length of such pipe jackets is to comply with the following specifications: For pipes with a diameter of ≤DN350 mm, the minimum length of the jacket is ≮200 mm； > For pipes with a diameter of DN350mm, the minimum length of the jacket should be ≮0.5DN. I don’t quite understand this sentence: ① If a jacketed valve is used, then the pipelines before and after the valve should also have a jacketed structure; otherwise, condensation will occur! ②If the entire pipeline does not require a jacket, then there is no need to use a jacketed valve either! ③The process conditions of the pipelines before and after the jacket valve are different; is a jacket required on one side while not needed on the other? I don’t quite understand; please help! Thank you!
I am very familiar with this situation; many of the concepts were indeed introduced by me in 1998: 1. What is commonly referred to as a jacketed disc valve features jacketing around the valve before and after it, which serves to prevent liquid sulfur from condensing and sticking to the valve disc； 2. For those that do not require a jacket earlier on, it is also necessary to consider the possibility of internal leakage and backflow from the valves ； 3. For auxiliary lines that may not be in use regularly, a full jacket is required, unless it is possible to isolate them or employ continuous positive pressure purging.
Found it on Haichuan; let’s see if it can be of some help. There are 3 types of heat tracing for valves: 1. Jacketed valves (providing uniform heating) ； 2. Heating with insulated pipes – Use insulated pipes of DN15 or other specifications; wrap them around the valve several times as it passes through the valve (just like with electric heating) ； 3. Electric heating (slightly more expensive). Whether to use jacket heating or external tube heating depends on the properties of the medium. 1. If the freezing point of the medium is below 50°C, external heating tubes can be used. 2. If the freezing point of the medium is above 50°C, jacket heating can be employed
Regarding the third scenario mentioned by the original poster, design firms now propose measures to prevent corrosion and internal leakage that can occur over time as a result of long-term use of valves; therefore, a nitrogen seal is installed to keep the pipeline under slightly positive pressure.
The prerequisite is a jacket valve, which determines that an environment with a jacket is required. The length specified later is the minimum requirement; in other words, the jacket must be this long. The purpose of this has been clearly explained by everyone, and today they helped me sort it out again
If it is to remain open continuously, there is no need for a jacket; however, this is not feasible in practice. The main consideration is that it may need to be closed at times, or certain auxiliary valves are often kept closed. Without a jacket, sulfur could cause the butterfly valve disc to get stuck. What the pressure gauge teacher said is excellent