The breathing valve of the normal pressure storage tank is easily clogged, causing tank holding. How to solve this problem?
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The breathing valve of the normal pressure storage tank is easily clogged, causing tank holding. How to solve this problem?
As for the safety valve, there is no problem if you do this, and this is actually how it is done.
What is the blockage? Is it freezing? Or does the material crystallize? It is very dangerous to hold the tank under excessive pressure.
Manholes can be designed as safe drainage manholes.
The breathing valve is easy to get clogged. There is no good way to do this except to check it frequently. Once the breathing valve is clogged, there will be serious safety hazards, such as bursting the container or deflating the storage tank.
Safety valve + post inspection and recording. If the storage tank is particularly important, remote transmission, alarm and other measures can be installed.
If the breathing valve is easily clogged, the use of the safety valve will be limited, and several aspects must be combined.: 1. In addition to adding a safety valve, a manual vent valve is also required. ； 2. At least two sets of remote pressure display and alarm systems. Because the breathing valve will be blocked, the pressure guide pipe of the pressure transmitter may also be blocked. Using more than two sets of pressure alarms can timely detect and clear the blocked pressure guide pipe by comparing the two pressure values. ； 3. When the pressure values are consistent and rise significantly, you can first manually vent the pressure and then clean the breathing valve immediately. ； 4. Don’t put too much trust in the safety valve, because the throat of the safety valve may also be blocked.
If it is a normal-pressure open storage tank, the vent must be vented to the atmosphere, and if the caliber of the vent is too large, a bird screen may be needed, and attention should be paid to heat tracing to prevent freezing and blockage. Moreover, there must be a manhole on the top of the tank, and the weight of the manhole cover has certain requirements, and it can also play a role in pressure relief. If it is a closed storage tank, it should generally be equipped with a pressure reducing safety valve (PVRV). The design principles of the safety valve should follow API 2000 and heat tracing is also required.
Storage tanks generally have pressure alarms, and if there are abnormal pressure fluctuations, workers are quickly called for inspection.
The pressure of the normal pressure storage tank is already very low. Even if a pressure alarm is added, how to respond correctly to small pressure fluctuations? The general design pressure of fixed-roof atmospheric storage tanks is only a few kPag, and the maximum is only 17kPag.
Isn't it enough to add an overflow pipe, which can be directly vented to the atmosphere? In addition, if it is in a tank farm, connect all the tanks with connecting pipes, so that even if the breathing valve of one tank is blocked, the others will not be blocked at the same time. In this way, you only need to check and clean it regularly. In fact, as long as there is an overflow pipe, the problem can be solved.
You can set an alarm. The pressure of the normal pressure storage tank will not rise during normal operation. If the alarm occurs, there may be a problem. The normal value and the set value can be measured around 100mmH2O.
It is necessary to analyze what is causing it, and whether the design of the gland inside the breathing valve is unreasonable and too heavy?
What might be the cause of the blockage? We also have one, and it’s equipped with a safety valve, which I don’t understand a bit.
If the problem is severe, it can be replaced with a vent. :)
The breathing valve problem is either blocked or sticky, or the designed flux may be too small. You can increase the diameter of the through hole and take anti-blocking and sticking measures (contact surface treatment). The above statement is also acceptable, but some media have restrictions.
Safety measures for normal pressure large tanks: 1. Breathing valve for normal operation: Constant pressure is generally -5~150mmH2O; 2. Hydraulic safety valve for safety protection: Constant pressure is generally -20~180mmH2O; 3. Pressure alarm interlock device: Detect the pressure of the large tank and cut off the pressure source when it reaches the limit, such as the transfer pump, to prevent liquid level fluctuations, -30~200mmH2O; Breathing valves and safety valves are generally equipped with more than one according to the breathing volume of the large tank, which means that they can play a relatively backup role.
To put it simply, it is: Safety valve + regular manual inspection + regular valve cleaning
I encountered a blockage in the breathing valve, which caused a vacuum in the tank and caused the tank to be deformed due to suction. Because it is frozen and blocked, adding heat will solve it. You can also try water sealing + nitrogen sealing. Heat is also needed when the weather is cold.
Our company has experienced tank deflation and tank lifting due to excessive positive pressure due to breathing valve problems. Currently, a new breathing valve is added to the top of each tank, a remote pressure transmitter is added to the nitrogen pipeline, and the breathing valves are regularly calibrated. No accidents have occurred in the past year.