7 replies to this topic

[curious_cat]

I was researching into Codes and Guidelines for Blast Protection of Reactors (Hydrogenation). I don't mean reactor interlocks, automation etc. but specifically layout, siting and structural protection. e.g. Blast Walls, Blast Panels, Venting, siting etc. i.e. When stuff goes wrong (and it shouldn't!) how does one minimize secondary damage. 

 

A non-US facility I was reviewing has a number of hydrogenators (approx 10,000 to 15,000 L) and there are no locally applicable codes that cover this use case. The end-use is specialty chemicals so the plant itself is built to local codes and "good engineering practice". And in any case the facility is older (approx. 50 years) and grandfathered in. Automation and interlocks etc. were upgraded over the years but the basic structure and layout  remains the same.  The originally facility is relatively open and on structural steel but now there is some discussion whether blast walls etc. should be added. 

 

Hence I was wondering from a safety point of view whether there would be other codes e.g. API, US / EU etc. that would serve as guidance or best practices.

 

 

Fundamentally, I am trying to reconcile two different points of view: (1) Safely venting the blast wave pressure e.g. by friable panels or having a reactor which is somewhat "open" i.e. no surrounding concrete walls etc. versus ( 2)  Blast shielding that would remain structurally sound in case of a blast.

 

This is a preliminary review so just want to familiarize myself with applicable standards and recommendations before a PE comes in for the detailed calculations and recommendations.

Edited by curious_cat, 09 August 2021 - 01:19 AM.

[breizh]

Hi,

You mention non US facility , if it's China you need to refer to GB code .

Other possibilities  should be to consult OSHA recommendations  and CCPS center for chemical process safety guidelines .

note : 

I do remember a concrete wall erected  between a toluene tank and a control room in China  to mitigate the risk of blast .

 

Good luck

Breizh 

[curious_cat]

Hi,

You mention non US facility , if it's China you need to refer to GB code .

Other possibilities  should be to consult OSHA recommendations  and CCPS center for chemical process safety guidelines .

note : 

I do remember a concrete wall erected  between a toluene tank and a control room in China  to mitigate the risk of blast .

 

Good luck

Breizh 

 

Thanks Breizh! 

 

I will look up the CCPS guidelines. Do you recall which of the CCPS publications this is in. I was browsing my bookshelf and currently looking at "Guidelines for Facility Siting and Layout; CCPS 2003". But CCPS has so much of good stuff out there that it is sometimes easy to miss the best stuff. 

 

No, this is not in China. It is a plant in India. 

 

Yes, I have seen those blast shields for control room protection as well. I guess it makes sense to deflect the blast from vulnerable targets such as control rooms. But does it make sense to surround the reactor with blast proof walls. How common are blast walls and where are designers using them. 

 

Also, what wall strength do the codes recommend and is there a guideline to estimate the blast overpressure in a specific case to make sure the wall is appropriately designed. 

 

I can imagine concrete projectiles from an under designed wall doing more damage than if the blast wave was allowed to propagate away safely and dissipate.  

[breizh]

Hi, 

Check for Guidelines for evaluating process plant buildings for external explosion and fires .

 

There is a section dedicated to blast !! 

Breizh

[Pilesar]

From your description, the plant already meets the applicable codes because of grandfathering. Most hydrogenation reactors do not have blast walls and their owners emphasize instead reducing the probability of an incident. Good practice is to quantify plant risks by using Layers Of Protection Analysis (LOPA) or equivalent method. My suspicion is that in an old plant, there are more effective ways to improve safety than building blast walls around existing processes. Erecting blast walls in an existing plant seems completely impractical to me, but an internet search will find companies that specialize in designing and supplying such walls.

[curious_cat]

Hi, 

Check for Guidelines for evaluating process plant buildings for external explosion and fires .

 

There is a section dedicated to blast !! 

Breizh

 

Excellent! Found the section. Exactly what I needed! 

[breizh]

Hi,

For your information , what I'm aware in China regarding process involving H2 and pyrophoric catalyst is the following : 

In several plants before the maintenance operation , Operation people did not purge  the H2 content to a suitable threshold (Below LEL) and opened the manhole , Unfortunately some catalyst was trapped between the gasket and the manhole leading to ignition , explosion and fatality.

 

Make sure during your Hazop or Safety review you take account this type of risk , really important to sweep the sky of the reactor(s) with sufficient enough inert gas , calibrated instrument to measure the H2 level at the vent or discharge point . 

Operation and maintenance are key for this kind of operation . 

Find a way to mitigate the risk of ignition and get all the work permits in place.

 

Good luck 

 

Breizh

[curious_cat]

Hi,

For your information , what I'm aware in China regarding process involving H2 and pyrophoric catalyst is the following : 

In several plants before the maintenance operation , Operation people did not purge  the H2 content to a suitable threshold (Below LEL) and opened the manhole , Unfortunately some catalyst was trapped between the gasket and the manhole leading to ignition , explosion and fatality.

 

 

Indeed. I have heard of some similar reports here too. Another common specialty chemical incident is related to shutdowns of distillation columns using structured packings. Very often once opened these high surface area packings tend to catch fire.