Prime mover selection for pump 3

[ro_kru]

I am building an power pack for the company for one of the project. From pump performance curve I can see that pump is absorbing 80HP @ 1200RPM. I need a prime mover to run the vacuum pump. I am planning to go with Tier 4 diesel engine as prime mover. Do we have to do any calculation for selection of prime mover or we just select prime mover which can provide somewhat higher HP @ 1200 RPM?
1) What other information I need to know for from pump before selection of diesel engine and what calculation I need to do?
2) What calculation I do for the selection of prime mover that it can meet requirement of pump and prime mover won't stall?

Thanks

 

[TugboatEng]

Consider the duty cycle of the pump. If the pump is to operate continuously you will want to oversize the diesel engine. An engine operating at 50% rating will last longer than an engine operating at 100%. You may see this in a prime vs. standby rating. With tier 4, however, it's important that you load the engine heavily enough to keep the SCR functioning. I also strongly suggest sizing your pump to operate at 1800 rpm as that is the speed most diesel engines are optimized to run at. This will allow you to select a smaller engine.

 

[LittleInch]

You may also want to think about using an electric motor as 1200 rpm is a 6 pole motor at 60 htz.

In order to get it moving you may need a soft starter to avoid oversizing the diesel engine.

I would think you want to aim for normal power being 70-80#% of max power to give you enough to start it but then run efficiently.

Anything at 50% or below won't be in the efficient range, especially if the engine is turbocharged.

don't know what a tier 4 engine is.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[TugboatEng]

Tier 4 is an EPA emissions threshold that in nearly all cases requires selective catalytic reduction where urea is dosed in to the exhaust stream prior to passing over a catalyst. The catalyst requires operation above a certain temperature to prevent clogging.

 

[ro_kru]

@LittleInch.
Interestingly there is a motor driving the pump company wants diesel engine.

 

[ro_kru]

@TugboatEng , do we consider any hand calculation?

 

[TugboatEng]

Part of the purchase price of the engine should include some level of access to an application engineer through the sales team. I would start by finding an engine dealer with strong presence in your region and contact their sales team. The advertised power ratings will all be at 1800 rpm and you will have to go through applications to get the rating at 1200 rpm. You may have to run a reduction gear.

 

[MintJulep]

From pump performance curve I can see that pump is absorbing 80HP @ 1200RPM.

That is an important piece of information. Is that the "rated" power of the pump?

More important will be what the pump is actually doing in its installed application.

Does it run continuously at 80 HP, 1200 rpm?

What is the rating of the existing electric motor? Was it provided at part of a pump-motor unit from the OEM, or pieced together by someone?

You might guess that the original combination was selected with a little margin. If that guess is true then increasing the power of the diesel relative to the original is at best not necessary, and possibly the wrong thing to do.

Electric motors (I'm assuming the existing motor is a 3-phase synchronous type) and diesel engines react rather differently to changes in load.

You can't just unbolt an electric motor and bolt up a diesel and call it a day.

 

[MechinNC]

The Deere 4045 is worth a look. Available in a variety hp ratings that will do your job, but will probably need a reduction gear of about 1.5:1 to get engine to sweet spot of 1800 with pump at 1200.

It may be possible to get the 4045 or the bigger six cyl engine to make 80hp at 1200, but that puts it pretty far out of its design envelope, might have emission system trouble there. Would want to ask Deere about that.

What kind of duty cycle will this pump run?

 

[TugboatEng]

John Deere is in a league of their own for engines in that power range. If you can tolerate the initial price and have local support, they are the finest engines money can buy. Either the 4045 or 6068 will cover your application. The 4045 is rated for 150hp at 1800 rpm but I would contact an application engineer to verify 80hp at 1200.

 

[EdStainless]

If you have to run a reduction gear make sure that someone runs vibration analysis. Often they use non-integral gear rations such as 1.87777 in order to prevent vibration issues.

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