Natural Gas Consumption - CAT Generator

What is 75% load in KW?

What is the heating value of your fuel (natural gas)?

Hi Steve,

Thanks for responding. The calorific value of CNG in Nigeria is 37.23MJ/SCM.

The Generator rating in kVA is 1205 & in KW is 965.

I hope this will help you in advising.

Best Regards

Baiju

Hi Kaisan,

Thank you very much for this lucid explanation. I missed to mention that we are in Nigeria and according to the GAS company the Calorific Value (which I presume is the heating value that you referred) is 37.23MJ/Scm.

Please advise if the formula can now be redone as 1205*.75*10.8/37.23=262SCM/Hr.

I wish the above redone formula is true as your explanation can then be used by me as THE RULE.

Best Regards

Baiju

Yes, you can use that formula, but what you have to take into account is the question that StevS asked, namely "What is 75% load in kW". You give it in kVA and for simplicity I just used it in the formula to illustrate the concept. ie the 1025 as the rated power is assumed to be in kW in the formula you now have. You must ensure that this number is given in kW so that your units are consistent.

I had the pleasure of working in Nigeria for a number of years - how are things?

Hi Kaisan,

Thanks for this quick response. I have replied to Steve just now....that Kw figure is 965 for the CAT generator....so I presume I substitute 1205 with 965.

Nigeria is looking very good for business now.....opportunities are tremendous and this is THE EMERGING MARKET in its true sense, in fact the whole of West African coast. I live in Lagos....where were you in Nigeria?

Best Regards

Baiju

Hi Baiju,

Given data is for required specific heat in MJ/bkWh, if you consider 96.25 % Alternator Efficency and convert the same for kcal than Sp. heat for generating one ekWh is 11220 kJ/ekwh which is 2675 kcal/ekwh. Now at NCV of 8500 kcal of 1 SCM of gas your Sp. fuel consumption is 0.314 SCM/ekwh. Your 1205 kVa generator to at 75% load and at 0.8 PF will generate 723 ekwh if myltiplied by Sp. fule consumption will give you result of 227 SCM/hr. Which very near to what CAT has provided and I assume only difference is due to NCV of NG..

Hope I have clarified.

Hi DRK,

Thank you very much for the calculations the end result of which is very close to what CAT advised.

Please note that we are in Nigeria and therefore I do not have much expertise around to fall back on except the generator provider CAT. I am the Finance Controller of the project and hence am DUMB when it comes to interpreting so much technical stuff , though I am trying.

I would be grateful if you can advise me the calculation "step by step" with convesrions of these different energy values like MJ/kWh, ekWh,kcal etc. I did not understand what Sp. heat & Sp. Fuel consumption (pardon my ignorance).

Best Regards

Baiju

Thanks Baijju for appriciating the effort. it is very little technicle that even Ii know also. but it is always good to share.

Kindly find the the image of working, I do not know how to attach here if you can provide me your mail ID than i can forward you the file.

And don't be soory for being a finincial guy at last you only will rule on us on any day.

Difference in my earlier working and here is due to your actual NCV of NG, I have considered the same as 35.57 MJ/kcal.

Bye for now. (preview suggest some alignment problem in paste)

Hi DRK,

Thank you very much for getting this so well illustrated. I really am grateful. My mail id is byju_2@yahoo.com As you said sharing is a wonderful experience just as Albert Einstein said ......"You have an apple, I have an apple & if we exchange it , we still have one apple each , while you have an idea , I have an idea & if we exchange ideas we are both left with two ideas each"

I really dont like being in Finance these days because we are a breed not loved anymore.....everything we do is looked at with a microscope.

Thanks once again.

Baiju

Ok Baiju,

First the generator rating is 965, so 75% load is 0.75 (965) = 724 KW..

At power generation of 724 KW, the fuel consumption is 10.8 mJ/KW-hour.

So the fuel consumption per hour is 724 KW* 10.8 MJ/KW-hr= 7819 MJ/hr

Your heating value is 37.23 MJ/SCM

So we take 7819 MJ/hr and divide by 37.23 MJ/SCM, and you get 210 SCM/hr

CAT's estimate was higher as they probably used a heating value consistent with gas in the USA rather than Nigeria. Oh and I did not bother with trying to factor in efficiencies.

Does this make sense?

Thank you Steve for this quick response.

I think CAT might have used a different heating value or may be they are just being conservative with the Fuel Consumption promises.

Regards

Baiju

Dear Baiju,

I have followed your communications with interest.

Please call Engr. Charles Osagie in Lagos on no 07058833466, he is a specialist and can help you with all your questions.

Hope this helps

Frank

Baiju,

I have followed this exchange with interest.

there is a specialist in Lagos who can help you.

Please call Eng. Charls Osagie on 07058833466

I am sure he can assist you with all these aspects

Guas

Hi Guas,

Thanks very much for this contact. Shall certainly call on Engr.Charles.

I hope you are the one who posted the same feedback just a while earlier as "guest" cos its the same in content.

Thanks once again.

Regards

Baiju

Baiju,

Yes that was me, I was not completely logged in, but I am now

Hope he can can be of assistance

Guas

Steve,

your explanation is really simple and YES it makes sense.

Please I will aprreciate if u can just allow me to bother you with a little of my own mechanical problem. I am a new employee in one of the companies that patronize CAT, it is assumed that I should know the solution to this problem but I don't.

I have this specification from a CAT gas turbine generator, TITAN 130 :

(ISO, no loss)

Electrical Power = 15MW

Heat rate = 10'230 KJ/kWE-hr

Fuel Input = 42.63 MJ/s

Efficiency = 35.19%

if this generator is to run on natural gas, pls how do I determine the amount of natural gas needed per hour.

I figured that the NO LOSS means that it is running @ 100% load, but in my calculation,trying to use the model you provided on your earlier post I got the value to be 3091.26 SCM/hr.

Please I am counting on your response. PLS "FACTOR IN EFFICIENCY" in this case.

You can reduce the fuel consumes by add water injection to your system.A small amount of water will increase engine wear and be more efficient. We inject water in our engines in the Dakota all the time.By adding water you will produce the same amount of horse power.

Baiju,

Please call Eng. Charles Osagu on 07058833466, he can most probably help you with all your enquiries.

Trust this is helpful

Guas