Hey everybody, hope you are enjoying my blog and finding the information useful in your field of work. Today we are talking about a topic which is rather less explored and understood in many industries as of now i.e. "Partial Inerting".
Let's start first with understanding Inerting. Inerting is defined as the replacement of "oxidant" in a system by a non-reactive, non-flammable gas, to make the atmosphere within the system unable to propagate flame. Inerting may be achieved by using a non-flammable gas, which will neither react with the fuel nor with the oxidant. There are many gases used for inerting such as Nitrogen, Carbon Dioxide, Flue Gases, Noble Gases (Argon, Helium), etc.
We have to understand that the material will still be flammable, but the ignition sensitivity and explosion severity will reduce. This may mean that explosion protection might not be necessary as MIE might increase to such an extent that "Removal of Ignition Source" can be utilised as Basis of safety in place of Explosion Protection (such as venting, containment or suppression). Since it is also capable of reducing Explosion severity (i.e. Pmax and Kst), hence the required vent area or the design of explosion protection measures can be much easier and cheaper. Keep in mind cost for St 3 vent > St 1 vent > no vent requirement.
A random test on an organic powder done for publishing the research paper shows that MIE has increased from < 1mJ at 21% Oxygen concentration to 30-100 mJ at 12% and > 1000 mJ at 10% as shown in the table below.
Reviewing the results of more common Sulphur dust, which has a very low MIE at 21% oxygen increases much more rapidly i.e. 1000 mJ at 10% concentration of oxygen. The same has been shown in the graph below:
Ref: www.icheme.org/~/media/Documents/Subject%20Groups/Safety_Loss_Prevention/Hazards%20Archive/XXI/XXI-Paper-027.pdf
However, one has to understand that in order to establish required oxygen content to reach a much safer condition which is easier to handle and easier to design, testing for different parameters at different oxygen level is required. This will help in reaching appropriate results.
I hope that this concept can be brought to industries and it will make safe operations possible at a much lower cost which usually takes an excessive amount of Nitrogen (or other inert gas) and hence inerting remain underutilised in industries.
Keep writing to me for further topic suggestions and will upload on the page. Do like, share and comment on the blog. I appreciate that people are actively commenting on LinkedIn, but it will be great for the blog if we get the comments here on the page.
Let's start first with understanding Inerting. Inerting is defined as the replacement of "oxidant" in a system by a non-reactive, non-flammable gas, to make the atmosphere within the system unable to propagate flame. Inerting may be achieved by using a non-flammable gas, which will neither react with the fuel nor with the oxidant. There are many gases used for inerting such as Nitrogen, Carbon Dioxide, Flue Gases, Noble Gases (Argon, Helium), etc.
P.S: Some material may react with these inert gases under some conditions. Hence, correct selection of gases is critical.
Now let's discuss the concept of PARTIAL INERTING to prevent dust fire and explosion. Partial Inerting means dilution of oxidising atmosphere with an inert gas but not up to the extent of LOC i.e. oxidant concentration lies between LOC and atmospheric concentrations. In other words, for partial inerting, the oxidising atmosphere (most often air) in which the explosible dust is dispersed is mixed with a fraction of inert gas (e.g. nitrogen) considerably smaller than that required for complete inerting (i.e. below LOC).
We have to understand that the material will still be flammable, but the ignition sensitivity and explosion severity will reduce. This may mean that explosion protection might not be necessary as MIE might increase to such an extent that "Removal of Ignition Source" can be utilised as Basis of safety in place of Explosion Protection (such as venting, containment or suppression). Since it is also capable of reducing Explosion severity (i.e. Pmax and Kst), hence the required vent area or the design of explosion protection measures can be much easier and cheaper. Keep in mind cost for St 3 vent > St 1 vent > no vent requirement.
A random test on an organic powder done for publishing the research paper shows that MIE has increased from < 1mJ at 21% Oxygen concentration to 30-100 mJ at 12% and > 1000 mJ at 10% as shown in the table below.
Reviewing the results of more common Sulphur dust, which has a very low MIE at 21% oxygen increases much more rapidly i.e. 1000 mJ at 10% concentration of oxygen. The same has been shown in the graph below:
However, one has to understand that in order to establish required oxygen content to reach a much safer condition which is easier to handle and easier to design, testing for different parameters at different oxygen level is required. This will help in reaching appropriate results.
I hope that this concept can be brought to industries and it will make safe operations possible at a much lower cost which usually takes an excessive amount of Nitrogen (or other inert gas) and hence inerting remain underutilised in industries.
Keep writing to me for further topic suggestions and will upload on the page. Do like, share and comment on the blog. I appreciate that people are actively commenting on LinkedIn, but it will be great for the blog if we get the comments here on the page.
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