Pressure Relief System in a Production module-Bulk Drug(API) Manufactu

[bsg]

We are designing a small Bulk Drug(API) Manufacturing Facilty where solvents will be used.The Design basically centres around One main Reactor, one Supporting Vessel for Work Up,Filtration,Drying and Milling Facilities.There is a Corridor all around this facility and our Client has asked us about the provisions envisaged for Pressure relief as the Production facility is an internal one surrounded by the corridor.

The arrangement we have in mind is the conventional Pressure Relief Arrangement for the Reactors and Closed Vessels with Safety Valves and rupture Discs and the exhaust pipe will have Flame arrestors.

an anybody suggest a better system ?

bsg

 

[chrisflower]

Pressure relief systems are a system of last resort. It is best practise to design the system so that pressure relief device systems are not required. For example specify the vessels with a design pressure higher than any pump can deliver. I noted that you have solvents present so fire may be an issue, but it may be possible to limit the inventory to prevent the vessels from over pressurising. Another approach, which is gaining acceptance in the UK primarily with very vigorous run-away reactions, is to say that I will design the equipment to deform in a relief event but not explode. This will mean that the equipment will need replacing after the over pressure event, but will not cause any other damage.

I note from your question that you are intending to use flame arrestors on the relief lines. This should be done with caution as flame arrestors can become easily blocked, thus rendering the relief stream useless. If you are going to install them then ensure that they are inspected regularly.

One question, where do the proposed relief lines vent to if the production unit is internal and surrounded by corridors?
Hopefully they will be routed to a safe location outside of the building, but I imagine that this will be a tortuous route, affecting pressure drops etc.

If possible design out the need for a relief system.

 

[bsg]

Thanks.
1)The Closed vessels handling solvents are ,of course, designed properly.

2)The safety/Relief line will be routed to roof ( corridor only on sides)

3)The Flame Arrestors are also properly designed.

4)Rupture Discs will take care of any vigorous unpredicted run way reaction type situation

Any further precaution necessary for the area in general ?

Regards,

bsg

 

[greg87]

I would also recommend against a flame arrestor on the relief discharge line. With proper location and position of the discharge point, it should not be required.

I'm not sure why they would be questioning pressure relief for the tanks, "since the area is surrounded by a corridor" Sounds more like they are refering to the need for pressure relief for an exposion in the room (relief panels).

 

[bsg]

Dear greg87,

Thanks.

Could you please tell me more about these Relief panels ?

Regards,

bsg

 

[dangnm]

bsg,
Just a thought, since it was not brought up earlier. You presumably have a pump on the discharge and valves on inlets, which also creates potential vacuum scenarios. If your reactor is not rated for full vacuum, you should probably look at a vacuum breaker.

It has also been my experience that most minor pressure and vacuum scenarios seem to occur during a startup. This usually results from human error (a tech forgot a valve was still locked out when the pump was started, or vice-versa). Properly designed systems keep vessels from exploding or imploding, but they will not prevent a relief scenario from happening. Interlocks on pump and valve control with appropriate open/close sensors, and thorough procedures are easy preventative measures.
Regards,

alevy27

 

[TSeener]

BSG,

I too have worked on and design several API facilities in the US and in PR. There are only a few items that I did not not see in your original message.

One, we would typically avoid the exterior cooridor arrangement, but if required we would create some special blast rated walls to protect the exterior coordidor. This however brings up a question, how many floors and where is your suite to be located. The Architectural design is truly driven by the Codes and I would direct you back to BOCA for the specifics.

Second, We would not run a relief header to a flame arrester. We would install a knockout tank, which would be inerted with nitrogen along with the relief header. This prevents any solvents from making it out of the system on to the roof and the inerting helps prevent deflagration in an over pressurization. Install an O2 sensor on the knockout tank and on the relief header to confirm that the system has been completely purged prior to startup and during operation.

If you have any other questions, please feel free to ask.

Best Regards,

Tom Seener