Project to build 100kw Organic Rankine Cycle Power Generator

[mellotango]

Hi, our firm has been awarded a project to build a prototype of a 100kw organic rankine cycle power generating system. I am currently chief researcher and I would like to gather some help through this forum. There are 2 key elements in this project A) we don't plan to construct shell n tube evaporators/condensers but rather obtain refurbished ones from local heat exchanger manufacturers B) we intend to modify 'dry' rotary screw compressors to function as expanders (since turbines are too costly, and this experiment has been shown to be possible by users from another thread in this forum) Our main heat source will be through biomass combustion and thermal oil will be our choice of heating fluid.

To start off, I would like some advice and specs for building such a system with a net electricity gain of 100kw:

i) U-tube or straight tube heat exchangers?
ii) Size of shell n tube evaporator?
iii) Size of shell n tube condensor?
iv) Choice of working fluid?
iv) Total volume (in ltr) of working fluid required for circulation?
v) Flow rate of working fluid pump?
vi) Size of 'dry' screw compressor?
vii) Size of regenerator?
viii) Size of air condenser? (to cool temp of working fluid from 130C to 65C)
ix) Size of alternator generator?
x) What is the expected electrical efficiency?

Will appreciate any help on this. During the course of this project, I would be glad to come back and post details of our progress. Thx!

[Brian_UK]

Seems more like you would like the forum to design the system for you.

Do you have any design input into the system that we could comment on?

[chillerman2006]

Seems more like you would like the forum to design the system for you.

Do you have any design input into the system that we could comment on?

Blimey, I thought the same thing Mate, starting reading & thought this looks interesting & then questions unravelled, pow !

time to give WebRam a buzz to quote for this thread annit, Mate

[NoNickName]

Funny how incompetent firms are awarded grants.

[mellotango]

Nonickname, in contrary to what your assumptions are, no, we have not been awarded a grant. But rather a project with possible future prospects, if we are able to show that it works with enough efficiency, that's all I can say. And we have to build this prototype funded by ourselves with very limited funds. And I admit, our expertise is not really into ORC systems and that I'm not really an engineer by training, but instead have dealt with some local successful gasification projects, which I can be more comfortable discussing technical issues with. Which is also why I'm seeking some help in this forum since ORC technicians or engineers with knowledge in this field is relatively scarce here in this part of the world. Nor can we afford any at the moment.

Back to the topic, as mentioned we are interested in building a test model of a 100kw ORC system. Brian_uk, sorry about the lack of input as I still trying to get a grasp of technicals here. Basically, I have now the parameters needed for a 280kw systems from proven orc systems, i.e. evaporator/condensor flow rate, input/output temperatures, max pressure, viscocity, heat transfer coefficient. e.g. So tailoring to a 100 kw system would mean reducing the parameters in proportionate amounts, logically speaking. But sizing the correct evaporator/condenser shell/tube heat exchanger needed is still beyond my ability, as some regard this as a specialized skill.

Instead, I'm seeking advice as to whether it is possible to modify commercially available refrigeration systems, i.e. industrial air cooled or water cooled chillers into green power generators by reversing the cycle flow. We will provide the heat source through biomass combustion and the screw compressors will be modified to act as expanders. If this concept is viable, and if anyone has done this before, I'd appreciate any help on this. On our side, during the oncoming months, we would be happy to share our progress via photos blog updates etc (with contributors only) from this forum.

Here are some specs for a refurbished air-cooled industrial chiller for sale that I am currently looking at.

Nominal cooling capacity: 249400 kcal/h or 290 kw
Input power: 103.4 kw
Max running current: 216A
Refrigerant: R22
Refrigerant type of control: thermostatic expansion valve
Compressor type: semi hermetic screw
Compressor power: 96.2 kw
Compressor Start mode: Y-
Compressor capacity control: 25-50-75-100
Evaporator type: shell and tube
Evaporator chilled fluid flow: 49.7 m3/h
Evaporator inlet and outlet pipe diameter: 4 inch
Condenser type: shell and tube
Condenser cooling air flow: 95000 m3/h
Condenser power: 7.2kw
Safety protection: compressor over temperature, unit overload, high and low pressure, flow switch, phase sequence, phase-missing, antifreezing
Dimension: 4000×1950×2200 mm
Net weight: 2860kg

Our choice of working fluid would be R245fa and thermal oil the heating carrier if the system were to be converted to orc for better efficiency. My broad question is, is there any reasons why this cannot be done with the above refurbished chiller?

[chillerman2006]

R245fa is standard R245 cleaned up to aviation grade used for cooling infastructure of fighter plane defence system electronics (black boxes) I have used it but did not know its available for general purchase.

Well thats going to put the cost up for starters as it eats copper & O'rings .... dont use ptfe tape anywhere it desolves it ! Every part of the system must be stainless and either welded joints (hundreds) or leak tested with helium + maspectrometer to 8x5 to the -7 (see my pics for test benchs, ground cooling units, environmental test jigs) as for cleanliness your be working to nasa guidelines 'NAS1638' ... I know this minefield !

I am concluding here that your research & developement is for a military customer & if it is I can tell you from experience that they will have you & others jumping through hoops all day long ... and just when you think you have what they want ... they will say " oh sorry we have gone for another design from another company" there will be several companies trying to provide the equipment they desire & they will also have all the universities testing for them, I know we had competitors that they laughed about dropping when we crossed the finish line ! .... big big contract if you can make what they want ... but you will not see a penny return untill .. signed sealed delivered & tested/proven by them for minimum 6 months ... pumps for R245fa are another issue ... hydraulic lock ... vapour lock .... and thats just a few issues off the top of my head

If not military are you sure R245fa is available R245 is ?

R's chillerman

[mad fridgie]

The first question you need to ask yourself is, do you want 100Kw electircal output, or do you want 100Kw net electrical output. Big difference.

[mellotango]

Honeywell sells Genetron R245fa. You can check out their website for more info.

Also, yes, about 100 kw net electrical output after minusing all other electrical losses would be ideal. Will this above configuration do it?

[mellotango]

I forgot to add that R245fa is widely used by well known orc systems such as pratt whitney UTC Purecycle, electratherm, etc I can email you the specific link to honeywell website about this product if you need it.

[mad fridgie]

Honeywell sells Genetron R245fa. You can check out their website for more info.

Also, yes, about 100 kw net electrical output after minusing all other electrical losses would be ideal. Will this above configuration do it?

....................No

[chillerman2006]

Nonickname, in contrary to what your assumptions are, no, we have not been awarded a grant.


Here are some specs for a refurbished air-cooled industrial chiller for sale that I am currently looking at.

Nominal cooling capacity: 249400 kcal/h or 290 kw
Input power: 103.4 kw
Max running current: 216A
Refrigerant: R22
Refrigerant type of control: thermostatic expansion valve
Compressor type: semi hermetic screw
Compressor power: 96.2 kw
Compressor Start mode: Y-
Compressor capacity control: 25-50-75-100
Evaporator type: shell and tube
Evaporator chilled fluid flow: 49.7 m3/h
Evaporator inlet and outlet pipe diameter: 4 inch
Condenser type: shell and tube
Condenser cooling air flow: 95000 m3/h
Condenser power: 7.2kw
Safety protection: compressor over temperature, unit overload, high and low pressure, flow switch, phase sequence, phase-missing, antifreezing
Dimension: 4000×1950×2200 mm
Net weight: 2860kg

Our choice of working fluid would be R245fa and thermal oil the heating carrier if the system were to be converted to orc for better efficiency. My broad question is, is there any reasons why this cannot be done with the above refurbished chiller?

Nonickname probaly meant contract/project & was lost in translation

R245/R245fa/R245fa ECR is used in oiless systems

Honeywell sells Genetron R245fa. You can check out their website for more info.

Also, yes, about 100 kw net electrical output after minusing all other electrical losses would be ideal. Will this above configuration do it?

100kw output, you answered your own question above 103.4kw input

I forgot to add that R245fa is widely used by well known orc systems such as pratt whitney UTC Purecycle, electratherm, etc I can email you the specific link to honeywell website about this product if you need it.

R245/R245fa are one & the same....I should have added ECR (see my picture) to the end which is the only clean 245 available & having spoken to honeywell this morning it is not available to purchase

It would appear your choice of equipment, working fuid & expectations, conclude to just one thing - this is not a project you are able to carry out without employing a design engineer....would you like me to provide contact details ???

http://www.refrigeration-engineer.co...=grouppictures

[rcarlitos99]

Hello Metallongo

Nice to hear from someone working in a ORC cycle. I've been working as Project Manager more than two years in a 25 KWe unit, also with a compressor working as expander. Right now, the performance tests are done and we are working in the serial machine to release at the end of the year.
We started at the same point that you are at this moment. You can send me a private message and we can start collaboration.

[mellotango]

Hi again. Chillerman, the choice of refrigerants in not conclusive yet, as there are other suitable options like isopentane, isobutane, toluene, silicon oil, etc but are highly flammable. R245 has been getting recognition as environmentally friendly refrigerant and good for low temperature cycles. However, we are interested in using high temperature loops since our heat source will come from biomass combustion waste heat (which we are currently utilizing ourselves for drying purposes). Hence, in terms of refrigerant selection, we are still doing more research on that.

Rcarlitos, I've had the pleasure of reading up similar work you have done before on your orc systems, also based in screw compressor conversion. I would be very interested to work in collaboration with you and hopefully we can share some ideas based on the success of your project. I'll send u a private msg right after this posting.

p.s. Chillerman, if your design engineer is also interested in collaboration work, we can get in contact too.

[mellotango]

Rcarlitos, I can't seem to send you a private message through my account. Perhaps you can drop me an email at mellotangoatgmaildotcom Thx

[Gary]

Many portable generators are equipped with 4 stroke combustion engines. Just as a thought experiment, I've been considering converting the 4 stroke engine into an expander. I think this could be done. Interesting stuff.

BTW, you will not be able to send PM's until you are up to 15 posts.

[chillerman2006]

Hi again. Chillerman, the choice of refrigerants in not conclusive yet, as there are other suitable options like isopentane, isobutane, toluene, silicon oil, etc but are highly flammable. R245 has been getting recognition as environmentally friendly refrigerant

Chillerman, if your design engineer is also interested in collaboration work, we can get in contact too.

Hi mellotango

Yes 245 is very environmetally friendly & as long as its used as a working fuid only (here in uk) can be vented, but can not if actually used as a refrigerant, as it them comes under refrigerant laws .... strange but true (more useless info I have stored)

I will drop a line to the design team, but sorry its unlikely as the two main lead engineers/designers hold salaries of £150k plus per annum .... ouch and as a result, do not take on additional work

There is how ever a 'Mad' design company here above who has the ability you require

Just need to increase your posts & you can drop him a private message or if you like I can email you some contact details ???

R's chillerman

[solarjoules]

Hello,
Your chiller has a cooling capacity or evaporator of 290kW. In a ORC, the evaporator becomes the heater. With higher temps, the evaporator rating goes up. Let's say it is 300kW. Typical efficiency of ORC is 10%. Your compressor, which is now the expander would only produce 30kW at best. Maybe 45kW with recuperator.

You would not get the 100KW output. carrier did something similar with their chiller. See PureCycle.

[graeme ellis]

Hi there all,
i would suggest using R134a for low temp applications ,its easy to get and works well in ORC.As for the guy who is wanting to get a unit up and running gee you need to hit the books my friend.As for using an ORC unit on a biomass setup you can use storage tanks and tertiary loops so you can control water /glycol loop temps better.I would suggest using a twin screw compressor and modify it to work as an expander.Otherwise for a cheap option also scroll expanders are greatand you can get these from "AIRSQUARED" look them up on the net.I am currently building my own ORC out of a twin screw compressor designed for refrigeration and hoping to achieve approx 5 to 6 kw gross at shaft.If you need advice please ask ,but the hard yards are done by you in the end ,bugger all information out there and lots of sleepless nights wondering how to get arounfd problems. cheers Graeme ellis