Steam condensation is not flowing properly
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As the title suggests, there is a jacketed evaporator; tetrachlorosilane is contained within the tank, and 2 bar of saturated steam is supplied to the shell side. The liquid flow rate into the storage tank is approximately 3500 kg/h, with a pressure of around 1.8 bar. The trap is functioning properly. What could be the reason for poor drainage of the condensate? There is also difficulty in draining the water accumulated inside the sight glass
It’s still probably a problem with the steam trap. Open the bypass of the strainer and take a look.
The main phenomenon is that the drain sight glass below the trap remains full for a while before being emptied again, on an intermittent basis. Our solution is to introduce nitrogen upstream or downstream of the steam trap.
You can swap the positions of the view mirrors and check whether there is water accumulation in front of the steam trap. If there is water accumulation there, it means that the discharge capacity of the steam trap is too low or that a bimetallic type of steam trap has been used. What you are seeing now is the situation behind the steam trap; water is present there probably due to back pressure behind the steam trap. Since you didn’t mention the specific details, the analysis above is for reference only. Please tell me what type of drain valve you have – mechanical, thermostatic (bimetallic), or thermal dynamic. What is the approximate steam flow rate in your evaporator? Is there any back pressure after the drain valve?
The type of drain is a mechanical float type. Below the trap, there is a condensate collection tank for recycling; this tank is at atmospheric pressure and is connected to the atmosphere. It’s not clear how to determine the steam volume; the heat exchange area of the evaporation tank is approximately 70㎡, saturated steam at 2 bar is supplied, and the pressure of the material inside is kept at 1.8 bar. It’s not very convenient to assemble and disassemble for auditions as it involves parking.
There is a situation in which the phenomenon you described occurs: 1) The actual amount of condensate produced is low, causing the float in the drain valve to rise and fall as it drains water. 2) The collection tank of the condensate recovery tank is located at a higher level than the steam trap. When these two are satisfied simultaneously, the situation you mentioned occurs. But according to what you said, the water rejection capacity should be fairly high. At this point, check again to see if there is a gas lock formed in front of the steam trap. You can search for information on steam gas locks; there are articles dedicated to this topic. Carefully compare the installation method on site with the examples given in those articles to determine whether the gas lock is caused by improper installation. If the cause still cannot be found, it’s best to contact the supplier of the steam trap as soon as possible; they have qualified personnel and specialized equipment that can resolve your issue.
Is it because the selection of the steam trap and steam drainage pipes is too small?