Recent content by zamakaze

For heat exchangers in simulations, I have often seen that sometimes the UA value is often held constant. Like its taken from a max/design case and kept constant for other cases like turndown. However, is this truly the correct approach? Given that the overall heat transfer coefficient (U) is...

In a typical propane refrigeration loop (e.g. in photo), there is always an accumulator or surge vessel. There is no level control on this vessel...so how does the level in the vessel get maintained. The expansion valve usually a level control valve maintains level in chiller. Does that valve...

In a typical fractionation column with a total condenser, does the liquid going to the reflux drum remain fully in the saturated liquid phase? Is any vapor formed in the reflux drum? Is the reflux drum usually just an accumulator or does it also act as a separator? If the reflux drum has a boot...

I am trying to understand if I can send a hydrocarbon product to an API 650 tank which has max internal design of 2.5 psig. Product is from Inlet Separator at 50 psig. Now when I model it I see that the vapor pressure of liquid from Separator is 50 psig. When I take it across LCV to the tank...

@little inch - thanks, however, I am still a bit confused over selecting a high selector From your earlier comment "But if you really want to do that then take both position signals and stick them into a high selector block and the valve will open more based on either lower flow than your set...

Thanks little inch. What you said makes sense. I guess my only concern is that since we have a fail open and air to close valve, should we actually have a low selector instead of high selector? Since in case of blocked flow for e.g, downstream of pump, the head/pressure increases and flow...

@LittleInch - yes both PC and FC are for min flow protection. In case of low flow and high prssure..the control valve should open. Valve is fail open and air to close. So when flow decrease, controller should send low signal to valve maybe ..to cause it to open? ..for pressure increase the valve...

Hi, I am trying to understand use of high and low selector in process control For e.g. in the attach photo, can we use high selector for pressure and flow controller to control min. flow recycle control valve? Should we use high or low selector? Should PC and FC be direct acting or reverse...

How does VFD speed control actually work in Reciprocating/Positive Displacement Compressor? In case of reciprocating compressor, how does capacity control work with speed control. Since we don’t really measure capacity / flow, is the speed control done based on pressure? For example lets...

Thank you for your answers @little inch @snickster

Snickster - yes this pressure vessel is to remove any entrained oil. level control in this vessel is just to maintain an interface b/w oil and water. This pressure vessel will be full of liquid. Noted on ur point to design this vessel for the max op pressure of the upstream separator. But I am...

thanks snickster, but incase i put a level control on water pressure vessel with continuous flow coming in and going out...will that help keep pressure at 15 psig...in this case there will be constant flow into and out of vessel. the water pressure vessel will be fully filled with level control...

@little inch - thanks very much for your response. much appreciated.

@little inch - thanks for your answer

thanks, horacio. Since the fluid is essentially water, what will be there in vapor space in this case? Would the pressure ever rise to 15 psig, even if a pressure control valve is there on the venting line??