Hello, I would like to get feedback on the best way to approach a new unit start up with regard to a test run for Operations sign off. Would I simply be looking for design target rates at product specification? Anything else that should be examined, such as under sized control valves? I would...
Hello, I would like to inquire on the best (cheapest) way to reduce ~2,500 ppm H2S to 50-100 ppm. The gas is flare header, and so is low pressure (1.5 psig). I have only seen amine applications in higher pressure systems. Can amine be used in low pressure also? How would you regenerate the rich...
Hello, I am not familiar with mechanical seals, so I apologize for my simple question.
What is the purpose of the vent lines in dual seals and gas seals? Must these seals vent continuously to flare? How much flow would be expected for a typical vent design?
Thank you,
Hello,
I have a PSV set at vessel MAWP of 20 psig. API recommends the inlet pipe to the PSV not have a pressure loss greater than 3% of set pressure at valve capacity. However, this is only 0.6 psi. ASME allows an overpressure of 10% for vessels with MAWP greater than or equal to 30 psig and 3...
Hello,
Does any one know of any theoretical equation for calculating the max possible discharge pressure or compression ratio of a liquid ring compressor?
Since LRs are positive displacement machines, when does the pressure increase stop?
Any references would be great!
Thanks,
Hello,
I am new to the subject of flame arrestors, and am in need of some fundamental help.
If a gaseous mixture to a flare is not classified as flammable, then is a flame arrestor required? Is flashback only a concern for flammable mixtures? My stream is composed primarily of Nitric Oxide...
Hello,
I am evaluating the adequacy of an existing flame arrestor and need to understand how to calculate the flashback velocity. How does pipe length and fittings impact the velocity?
I suppose it is the flashback velocity that I should check the pressure drop against on my FA capacity...
Hello,
I need to determine whether a 275 psig steam drum will require a vortex breaker at its bottom nozzle that goes to the suction of a pump. I have a 12" outlet nozzle and suction line to the pump. The flow rate is 1,600 gpm. Liquid level in the drum is about 5 ft above the bottome nozzle...
Hello,
I am looking into potential energy savings on retrofitting an A/C motor with a VFD. The machine is a positive displacement, SIHI, liquid ring compressor. The performance curve I have is a bit confusing to me. Typically, I see centrifugal type machines as having the required power...
Hello,
I have a 265 psig steam/condensate line return from a heat exchanger back to a flash steam drum. It is about 5 wt% vapor/95 wt% liquid, and 80 vol% vapor/20 vol% liquid. Liquid velocity is 3.5 ft/sec; steam velocity is 15 ft/sec.
We are experiencing slug flow as evidenced by regular...
Hello,
I have gone out for bids on 2 different exchangers, one is condensing on the shell side and the other vaporizing on the shell side. One exchanger manufacturer has recommended to use a 60 degree tube layout. They say that this reduces the possibility of vibration in the exchanger. This is...
Hello,
I am pondering the consequence of oversizing a steam trap. I can understand why an undersized steam trap would be problematic, i.e. backing condensate into your steam header. But what would an oversized trap do? Release steam?
Any light shed on this subject would be appreciated.
Hello,
I am curious about determining how much vacuum a vessel can see during draining.
My case would be a vessel 90% full of liquid being drained with nothing else open. Is it as simple as P1*V1=P2*V2, where I would solve for P2 when I have 100% empty vessel?
Does the rate of draining...
Hello, I was recently in a PSM audit and a question came up of zones in a flame arrestor/flare system. No one in the room seemed to know what these zones are. Can anyone provide some general comments on flame arrestor zones i.e. what are they, purpose, design, etc.
Thank you
Hello, I am a cheme and have what seems to be a dumb mechanical question.
In general, is the design of manways such that they are the same thing as nozzles? If I have a 24"-300# RFWN std wt manway, what is the difference between that and a 24"-300# RFWN std wt nozzle? Can a manway support the...
Hello All,
I have a liquid seal that is used as overpressure protection on a vent system off of a reactor set at 16.5 psig. I am wondering, in general, what promts the use of a liquid seal vs a PSV or rupture disk for this application? We have a pressure control valve on the vent piping so it...
Hello,
I am in the process of sizing a RO in a 1" warm up line around the discharge check valve of a pair of hot (415 deg F) condensate pumps. I have a somewhat simple question: is backflow through these pumps in this type of application an issue? The flow I calculated for this warm up line is...
Hello, I do not have much practical experience with pumps and have a question as to what physically happens when a system curve is at a point beyond the rated pumps curve. In other words, what happens when a pump runs out on its curve. Do you simply extrapolate the curve to the lower TDH and...
Hello All,
A colleague and I are having a discussion on the overpressure scenario(s) that must be considered for process piping/pipelines. Would the cases differ from any of those we consider for pressure vessels, i.e. blocked outlet, fire, thermal expansion, etc? The reason I ask is that we...
