Turbine Steam Usage problem

[Patassa]

I'm trying to spec out some new turbine steam trip valves for a client. The valve manufacturer is requesting the steam flow rates through the turbine. I've asked the client for the information and the Process engineer has given me a couple of numbers based off of the pump data sheets that have some basic turbine numbers on them as well. I'm having an issue understanding the Process engineer's response.

The data sheet states the steam flow rate as
85.5 lb/BHP/hr
The process engineer said in the email that this is "85.5 MPPH".
Is MPPH = mass pounds per hour? If so, is this correct? I'm not that familiar with these units but it seems like I'd need to multiply 85.5 lb/BHP/hr x 150 hp (from the data sheet) to get the lb/hr?

Also, he only had the data sheets for 2 out of the 5 turbines I've requested. I am using a Turbine Steam-Consumption calculator to estimate the steam flow rate for my other turbines as well as to compare with the numbers given on the 2 data sheets that I do have. Using the following inputs, the calculator is giving me numbers that are no where close to 85.5 x 150 hp lb/hr.
P in = 600 psig
T in = 700 F
P out = 250
T out = 520
Power = 150 hp
calculated steam usage = 5036 lb/hr

What am I missing?

 

[racookpe1978]

His info. 8<) Call him back so you get a quick feedback, without the emails or trail of tears needed in writing to a client.

 

[Patassa]

Well he sent me the data sheet, so I see where he got the number, I'm just not sure that he interpreted it correctly. He's a very green engineer.

is MPPH equivalent to Lbs/hp/hr like he's saying? That doesn't seem right.

 

[stgrme]

I believe that 85.5 MPPH stands for 85,500 lb/hr. In other words, "M" equals 1,000. Using the inlet and outlet steam conditions, I calculate about 2,576 hp (1,922 kW). How does this calculated power compare to the power required by the pump? Please note that the rated power for the turbine may include margin to ensure the turbine capability will exceed the power required by the pump.

Best of luck!

 

[MintJulep]

What am I missing?

You are missing the information that you need to do your job correctly.

If you suspect that the process engineer you have already corresponded with is not the right person in your client's organization to provide that information then find the right person.

If there is no right person then make arrangements to get the information yourself.

Somewhere in the facility there is certainly a file that contains the original design parameters. Of course maybe no one knows where it is.

If you can't find it then you'll need to directly measure.

You are unlikely to get the information you need from random strangers on the internet.

 

[Patassa]

Can anyone answer whether MPPH = lbs/bhp/hr ? For example the data sheet says the "Steam Rate FL 85.5 Lb/Bhp/hr" Their process engineer is telling me this is equal to 85.5 MPPH. It seems to me that I need to multiply 85.5 lb/Bhp/hr x 150 hp = 12,835 lb/hr which would be 12.825 MPPH.

Am I incorrectly thinking about this?

 

[EnergyMix]

Just to be clear, what does the initialization "MPPH" mean to you? What are its units? Why does the process engineer think you don't have to get rid of the horsepower term? Why are you equating the Bhp term in the 85 lb/Bhp/hr number as equal to hp? Also was it intended that 85 lb/Bhp/hr mean 85 lb*hr/Bhp -- that's what you get by the second division.

I strongly recommend picking up the phone and talking to the process engineer (yes, I'm an introverted engineer and don't like phones either, but sometimes you have to.) Clear up your units. Random strangers on the internet cannot interpret this for you (well we could, but just because someone confirms your math doesn't mean you've met what the process engineer wants. He might really want 85 MPPH.) Being right sometimes is not the important thing -- sometimes what's important is getting the process to do what the customer wants.

Want to know the do's and don'ts of Eng-Tips? Read FAQ731-376.
English not your native language? Looking for some help in getting your question across to others or understanding their answers? Go to forum1529.

 

[MintJulep]

What does MPPH stand for?


** MPPH Machu Picchu Pueblo Hotel
** MPPH 2-Methyl-1-Phenyl-2-Propyl-Hydroperoxide (biochemistry)
* MPPH Magnesium Potassium Phosphate Hexahydrate

 

[MisterDonut]

MPPH is thousands of pounds per hour, like stgrme said. MMPH is not equivalent to lbs/bhp/hr.

 

[FredRosse]

We very often have confusion on the mass flow issues. In our USA utility industry, PPH = Pounds(mass) Per Hour

The current Metric standard uses a prefix for thousands (k, or kilo), so if we want to express 15,000 PPH, it can be written 15 kPPH

The trouble then starts with the standard Metric designation for millions (M, or Mega)

the USA industry for several decades uses "M" for thousands (based on Roman number designations), which in current industry is sometimes mistaken for "Millions" by Metric oriented people.

As a result, the USA standard is currently to express "Millions" as MM, such as 5,000,000 PPH = 5 MMPPH In this case the older (Roman "M") designation becomes 1000 x 1000 = Millions, and there is no conflicting Metric prefix to be confused with. Similarly, we use kPPH for thousands, and there is again no conflicting interpretation.

The confusion for the issue here is clearly that someone is mixed up on the numbers, 85.5 LBm/BHP-hr gives 12,825 PPH steam flow for a 150 Horsepower machine, a fairly high, but not unreasonable steam consumption for a small turbine. But the same data supplied has 5036 PPH steam consumption stated, and evidently the engineer stated "85.5 MPPH", which in any interpretation would be either 85,500 PPH, or 85,500,000 PPH, which are values far too high for anything close to reasonable. So in conclusion, the data needs to be sorted by someone who actually knows what is what.

 

[Patassa]

Thanks FredRosse,

We got it sorted out, my inclination was correct and the process engineer apologized for being quite confused on the issue.

 

[GenB]

So the designer already agreed that it was a mistake bhph for mpph. What's the question?

 

[poetix99]

I see that you got your question "sorted out", but only FredRosse gave you information that implicitly answered one of your original questions: BHP (in this context) stands for Brake HorsePower. The "brake" here refers to shaft power delivered at the driven equipment.
The quantity such as 85 lb/BHP/hr is a "steam rate" for the turbine in question -- the amount of steam flow required (lb/hr) per unit of power (hp). It is represented as lb/hp-hr, or (somewhat sloppily & confusingly) lb/hp/hr.