12 replies to this topic

[curious_cat]

Are there vendors selling smaller sized steam driven pumps or rather the turbine that will drive them. We have a lot of 10-20 hP CFG pumps currently driven by motors. OTOH, plenty of spare steam (~350 psig) is available and we were wondering if we could reduce our operational expenses by switching to steam driven pumps.

 

Problem is, most literature I find is for much larger pumps. 

 

Any comments? Is this project worthwhile? 

[pavanayi]

curious_cat,

 

The feasibility of any such project will depend on three primary things:

1. Marginal price of your steam

2. Price of electric power.

3. The current steam balance

 

The problem with small turbines is the very low efficiency they come with (20-25%). Hence it might only be reasonable if your marginal steam prices are very cheap in comparison to the power prices.

 

Another approach would be to have one turbogenerator (condensing type or backpressure type, depending on your steam balance), that will take all the available steam (350 psig) through it and generate power to be used internally. This is a neater option than buying and installing several small turbines and associated pipework, as efficiencies will be higher for one large turbine than the single small turbines for each pump. It might prove more economically viable.

 

But the neatest option would be to investigate why you have plenty of spare steam in the first place, and is there a far more economical way to reduce the excess steam and instead use the available heat within your process itself, thereby reducing fuel firing somewhere.

[curious_cat]

Thanks for all those tips. 

 

If I may pick your brain a bit more:

 

(1) What's the smallest steam driven turbine you recall seeing in a process plant. Any vendor sites you know I could look at. I've had no success on google finding small hP turbines.

 

(2) At about what smallest capacity does a turbogenerator become viable. Or alternatively, what's the smallest one you've seen in use. My impression was our loads were too small for generating our own power. 

[pavanayi]

I have seen small 15-20 HP pumps driven by backpressure turbines (compressor lube oil, steam condensate return etc) that are run between 250 psig and 50 psig.

Unfortunately I dont remember the manufacturers of those turbines, but someone else on this forum might know a few.

 

Your second questions is a very subjective one. It will depend on the parameters I have mentioned earlier in post 2, and you can easily work out the economics. Assume a 25% overall thermal to electric for a condensing turbogenerator. With your steam availability, you can find out how much electricity you can potentially generate.

What benefit do you get in reduced electricity import is dependent on your costs involved. Get a capital cost estimate and you should have your answer!! I guess it should not be difficult to do a preliminary back of the envelope calc to see if there is any benefit in investigating in detail.

[shan]

You are better off to buy a large steam turbine with better efficiency to generate electric power and use the power to drive the pump motors.

[curious_cat]

Thanks! I will calculate!

[Bobby Strain]

Look for Coppus turbines for small drives.

 

Bobby

[Art Montemayor]

I think Dresser-Rand has a "C" Series of steam turbines that are single-stage, and have an overhung wheel design.

 

I know they bought out Terry Turbines, once an excellent small horsepower steam turbine manufacturer, but ceased selling them.  Now, I think they have developed their own line of turbines.

 

If Coppus is still alive, they should also be a good prospective supplier.  They once were very good suppliers.

[ramsingh_mech]

Dresser-Rand do single stage capabilities from  1 HP to 4695 HP ...there are some other vendors also..but the selecion of this type of Low HP Systems need case to case study.  as you said , the enthalpy of steam avilable with you is very lower side for this application the steam rate goes at higher side. once again evalute /compare the Steam Turbine / Motor Power.

 

Thanks

RAM.

[curious_cat]

I think Dresser-Rand has a "C" Series of steam turbines that are single-stage, and have an overhung wheel design.

 

I know they bought out Terry Turbines, once an excellent small horsepower steam turbine manufacturer, but ceased selling them.  Now, I think they have developed their own line of turbines.

 

If Coppus is still alive, they should also be a good prospective supplier.  They once were very good suppliers.

Thanks. C series still looks way too large for the 10-20 hP applications I was looking at:

 

http://www.dresser-r...nglestage/C.php

 

Still checking out the rest! Thanks for the tips. 

[curious_cat]

Dresser-Rand do single stage capabilities from  1 HP to 4695 HP ...there are some other vendors also..but the selecion of this type of Low HP Systems need case to case study.  as you said , the enthalpy of steam avilable with you is very lower side for this application the steam rate goes at higher side. once again evalute /compare the Steam Turbine / Motor Power. 

 

Thanks

RAM.

 

 

Can you point me to the lower range models? Ones I found on their site are definitely not in the 10 hP range. 

[ramsingh_mech]

It depends on your requirement , but there are lower range manufacturing facilities are there with Dresser Rand. I suggest you to directly contact the Dresser Rand Party , they will be very much happy to assist you.

 

RAM.

[pavanayi]

Try Elliott Turbo. They mention 20hp turbines on their website. You might have to contact a representative for their product range

 

http://www.elliott-t...om/turbines.asp