Pump seal cooling tank----thermosiphon
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In the new projects undertaken by our company, double-end internal seal pumps are used for sealing purposes. For cooling, a small tank containing 3/4 water is suspended at a height of one meter; it contains a cooling coil. At its lower end, there are two small pipes that serve as inlet and outlet lines for the coolant used to cool the seal, connecting to the seal jacket. A gas pipe is installed at the top to maintain a slight positive pressure inside the tank. According to those experts, this mechanism utilizes the principle of thermal siphonage to enable self-circulation of the coolant. However, during testing, some of the coolant failed to circulate, or there was insufficient cooling, which has already caused 4 sets of mechanical seals to burn out. Could everyone please help explain the reasons why the coolant doesn’t circulate and the solutions to fix it? Thank you! ! ! ! ! ! ! !
I have seen similar systems; it’s for the external circulating cooling water of the rectifier, with a soft water tank on top to cool the rectifier, as well – it’s a water circulation system. It works very well. Next time, let’s check the site to see if it can provide you with some insights.
This post was last edited by wo*aohe on 2010-5-27 17:31. 1 What medium does the pump handle? What is a thermosiphon medium? Is there ventilation on the thermosiphon pot? Is steam also added to the thermosiphon tank? You haven’t made it clear at all. 2 First of all, this type of mechanical seal must be used in pumps that do not crystallize and in which leakage of the medium is not allowed. If the medium tends to crystallize, the thermosiphon tube will become blocked, losing its thermosiphonic effect. 3 The principle of the thermosiphon circulation is that the mechanical seal is equipped with a screw pump which provides the power for circulation; additionally, the pressurization through ventilation supplies some driving force for circulation, and the thermosiphon effect is generated as a result of heat exchange with the medium. Therefore, the medium used for thermal siphonning must not have too high a viscosity. Secondly, mechanical-sealed threaded pumps have a directionality – they must not be installed in the wrong way. Additionally, gas (usually nitrogen) should be applied to the pipes, and the pressure level should not be too low. 4 Be careful not to get the inlet and outlet pipes on the mechanical seal mixed up.
I have something to attend to first, but I’ll briefly share my opinion. If the circulation is poor, it is possible to install a pump impeller on the shaft; in simple terms, it functions like a small pump blade. Modern pump manufacturers all use designs of this kind, and API Plan 52 also requires such a solution for forced circulation.
Once, in a reply from a fellow marine enthusiast, it was mentioned that installing pipeline pumps for forced circulation is a reliable method with noticeable results.
Quoting the original poster: “It contains a cooling coil inside, and at its lower end there are two small pipes that serve as the inlet and outlet lines for the seal cooling fluid, connecting to the seal jacket.” You’re not connecting them in reverse, are you? Cooling water should flow through the cooling coil, while about three-quarters of it should be soft water or engine oil. If connected reversely, it is very likely to burn out the seal. ·········Personal opinion
Based on your information about the double-end face seal, as well as the use of water and pressurized nitrogen for supply, I think it’s the connection method for the Plan53A seal flushing scheme. The coil inside the tank is connected to the circulating cooling water, not to the machine seal chamber. Industrial white oil needs to be poured into the tank; pay attention to the liquid level indicated by the glass sight gauge. The mechanical seal itself should be equipped with a pumping ring that can circulate white oil on its own, in order to ensure heat dissipation and the lubrication of the mechanical seal.
First of all, it is necessary to ensure that the diameter of the inlet and outlet pipes is slightly larger; the pipes should be as short as possible with as few bends as possible. When bends are unavoidable, avoid using right-angle elbows to reduce pipeline resistance.
Just connect a cooling water pipeline directly to the system’s water pressure pipeline – that’s it!
Reply to 1# kouling1986: I think it’s a problem with the nitrogen pressure at the top – too low or too high leads to poor cooling effects. I’m not sure if the issue has been resolved yet.
A small gear pump should be added as a coolant circulation pump; it won’t increase costs much, but it will yield excellent results