How to prevent fires in vent pipelines, taking hydrogen venting as an example.
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The last edit to this post was made by *nyang3390 on 2011-7-21 at 12:39, modifying the description in the article \"A Brief Analysis of the Causes of Hydrogen Combustion and Explosion\" (North China Electric Power Technology, Issue 7, 1991): \"The results of Experiment 3 show that, at a discharge gap of 8 millimeters, the higher the iron oxide content, the easier it is for ignition to occur.\" Ignition occurs when the H2O content is 4.2 cubic centimeters and the discharge gap is 4–6 millimeters. The presence of iron oxide and water in hydrogen is an important condition for a fire to occur. ” \"Explanations to the Provisions of the Design Code for Hydrogen Stations\" (GB50177-2005) 12.0.9 A flame arrester is installed on the hydrogen vent pipe to prevent the spread of fires or explosions in the event that a lightning strike causes such an incident during hydrogen venting. In the past, the location of flame arresters was sometimes placed indoors to facilitate maintenance ； Some are also installed outdoors, which helps to protect them from lightning strikes. This provision states that it shall be installed at the pipe outlet. The hydrogen vent pipe is placed 1 meter above the roof ridge to prevent hydrogen from flowing back into the interior when it is vented. For hydrogen vent pipes under a pressure of more than 0.1 MPa, in order to prevent excessive flow rates when hydrogen is vented, and considering that the vent pipes being installed outdoors may be corroded by rainwater and humid air, resulting in rust that could lead to combustion or explosion incidents during venting, this regulation stipulates that the piping material used for the vent pipes behind the flame arrester should be stainless steel.
My suggestion is to add a flame arrester to the vent pipe
My suggestion is to allow N2 to flow through the vent pipe, and a flow-limiting orifice plate can be installed
Install a flame arrester, and add a nitrogen gas outlet at the vent
I agree with what was said on the 4th floor: it’s best to blow with N2 first before releasing H2, and then blow with N2 again after the release – that way there should be no problems. It’s also important to maintain good static electricity grounding
Someone upstairs reminded me that I need to check how our hydrogen vent line is designed.
Hydrogen at 0.1 MPa is vented directly, and static electricity can easily be generated due to high flow rates, leading to combustion. So, by adding a Gavin vent before discharge, the volume of the pipeline increases and the flow rate of the hydrogen gas slows down; at the same time, it is important to ensure proper grounding to prevent static electricity, which should help to some extent. Passing nitrogen gas is also a good method
After the vent pipe, a nitrogen pipe or steam pipe is added for dilution to suppress combustion.
Install a flame arrester, and supply nitrogen at the vent
The year before last, our company experienced an incident in which the hydrogen vent pipe caught fire due to a lightning strike; at that time, only a flame arrester was installed on the hydrogen vent pipe, and no nitrogen pipeline was connected (we were using bottled nitrogen at that time). Based on this incident of the hydrogen vent pipe catching fire due to a lightning strike, we connected nitrogen to the hydrogen vent pipe and installed lightning protection devices there, thereby preventing fires in the hydrogen vent pipe caused by lightning strikes.
Could you be more specific? We use natural gas here, and there have been cases where it was ignited by lightning. The vent is vertical and equipped with a flame arrester.