Hi I would like to ask the community if we can set up a post for a new energy system I have been working on ,I think it works out more efficient and ecologically better , and its large scale thinking for energy systems , and now I need to check through my figures and need the views of IET thinkers for instance on combustion , post combustion chemistry , it unfolds into quite a complex system which I have been working on for 8 years , but enables us to get more energy from wastes and perhaps helps to move to biomaterials. I have an interest as environmental thinker and have designed the system to go through to government funding phases and pretty confident it works well in a number of questions around energy and environmental thinking .
Ok am trying to think how to do this , some technology I cant really discuss until end of June when published , but I guess getting agreement on the toolbox I have made should help to express the interactions that enable the efficiency so at least you get an idea of the combustion efficiencies .I don't know if a good starting point is to look at one of the most impressive coal fired plants where supercritical steam parameters are used , the J W Turk plant in Arkansa USA won an award in 2012 and it is quite a bit of engineering for coal technology ,Using PRB coal at around 21000 KJ/KG at a rate 350,000kg /Hr , producing 600MW and putting out 444,756 kg of CO2 every hour plus NO2 , estimate as air drafted atl air/ fuel ratio of 8:1 , air at 1.225 kg/m3 around 2,800,000 kg hr or 3,430,000 m3 , being as air is composed of 78% N2 and 21% O2 so around 2,709,700m3 of N2 and 720,000m3 O2 .The O2 is of course the component that reacts . This shows an obvious efficiency problem , even with re heat of incoming air ,the N2 component in air drafting plays little part in the actual heat aspects, add in if you have variations of external air temperatures and in air drafted systems you have ,thermal efficiencies to think about ,In the case of the J.W.Turk plant this is around 40MW from a day say at external air temp of 20oC to a night say of 2oC , inherent also is the fact that the N2 component of air is heated only to carry heat to the exhaust . The J.w.Turk plant given the planning time involved , it took nearly 2 years just to build the water curtain boiler ,really is a great engineering achievement , steam pressures to turbine of 26200 KPA supercritical steam at 607oC and 557kg/s .It is claimed that supercritical steam enables less fuel to be burnt and so is better for emissions , however fossil fuels and particularly coal are not really choices for countries to make anymore.
Carbon capture is interesting until you start thinking about the maths in fuel use terms where you start having figures of 15% plus extra coal burning and emissions just to sequester the CO2 into spent gas fields , so even to a lay person kinda burning 15% more fuel sequester CO2 means your stores run out of space faster and when your store is full what do you do then .
The other interesting fact for most air drafted electricity generating plants is how KJ of fuel is converted into KW of electrical output and most plants around the world have the rather terrible figure of 32-36% fuel energy to electrical output , the very best are at 45% and if you use CHP systems then maybe 60% , so these sorts of plants are incredibly poor at thermal efficiency. Because the J W Turk plant is burning the plentiful supply of low grade coal it produces fly ash and this is collected from the exhaust , it is thought that around 16% of the heat energy created is lost in so called stack losses, although where you use this to pre heat incoming air , as many plants do you get some improvements .
I make the total heat for this plant at 350,000kg x 21000 kj/kg = 7,350,000,000 KJ/hr with around 1,470,000,000 kj hr being in the exhaust assuming a standard 80% heat conversion boiler (don't know the heat recovery back to incoming pre heating) , but around 80% of the heat energy used is converted in heat of the steam . so around 1mw uses 12,250,000 kj of fuel .
the MW and MWH understanding at point of generation , I could do with some better framing , is 600MW the continuous output ? so is my 12,250,000 kj per Mw , fuel figure correct ?
Also been trying to work out post combustion gas flows , and I get 1m3 of CO2 at NPT being 8m3 in volume at 500oC but unable to work out heat content in KJ per m3 at 8m3 expansion ?? I have had a go at ideal gas calcs but doesn't really help me with KJ per m3 . Have some other toolbox builder for combustion calcs later and a whole host of other technical thinking if required.
Ok am trying to think how to do this , some technology I cant really discuss until end of June when published , but I guess getting agreement on the toolbox I have made should help to express the interactions that enable the efficiency so at least you get an idea of the combustion efficiencies .I don't know if a good starting point is to look at one of the most impressive coal fired plants where supercritical steam parameters are used , the J W Turk plant in Arkansa USA won an award in 2012 and it is quite a bit of engineering for coal technology ,Using PRB coal at around 21000 KJ/KG at a rate 350,000kg /Hr , producing 600MW and putting out 444,756 kg of CO2 every hour plus NO2 , estimate as air drafted atl air/ fuel ratio of 8:1 , air at 1.225 kg/m3 around 2,800,000 kg hr or 3,430,000 m3 , being as air is composed of 78% N2 and 21% O2 so around 2,709,700m3 of N2 and 720,000m3 O2 .The O2 is of course the component that reacts . This shows an obvious efficiency problem , even with re heat of incoming air ,the N2 component in air drafting plays little part in the actual heat aspects, add in if you have variations of external air temperatures and in air drafted systems you have ,thermal efficiencies to think about ,In the case of the J.W.Turk plant this is around 40MW from a day say at external air temp of 20oC to a night say of 2oC , inherent also is the fact that the N2 component of air is heated only to carry heat to the exhaust . The J.w.Turk plant given the planning time involved , it took nearly 2 years just to build the water curtain boiler ,really is a great engineering achievement , steam pressures to turbine of 26200 KPA supercritical steam at 607oC and 557kg/s .It is claimed that supercritical steam enables less fuel to be burnt and so is better for emissions , however fossil fuels and particularly coal are not really choices for countries to make anymore.
Carbon capture is interesting until you start thinking about the maths in fuel use terms where you start having figures of 15% plus extra coal burning and emissions just to sequester the CO2 into spent gas fields , so even to a lay person kinda burning 15% more fuel sequester CO2 means your stores run out of space faster and when your store is full what do you do then .
The other interesting fact for most air drafted electricity generating plants is how KJ of fuel is converted into KW of electrical output and most plants around the world have the rather terrible figure of 32-36% fuel energy to electrical output , the very best are at 45% and if you use CHP systems then maybe 60% , so these sorts of plants are incredibly poor at thermal efficiency. Because the J W Turk plant is burning the plentiful supply of low grade coal it produces fly ash and this is collected from the exhaust , it is thought that around 16% of the heat energy created is lost in so called stack losses, although where you use this to pre heat incoming air , as many plants do you get some improvements .
I make the total heat for this plant at 350,000kg x 21000 kj/kg = 7,350,000,000 KJ/hr with around 1,470,000,000 kj hr being in the exhaust assuming a standard 80% heat conversion boiler (don't know the heat recovery back to incoming pre heating) , but around 80% of the heat energy used is converted in heat of the steam . so around 1mw uses 12,250,000 kj of fuel .
the MW and MWH understanding at point of generation , I could do with some better framing , is 600MW the continuous output ? so is my 12,250,000 kj per Mw , fuel figure correct ?
Also been trying to work out post combustion gas flows , and I get 1m3 of CO2 at NPT being 8m3 in volume at 500oC but unable to work out heat content in KJ per m3 at 8m3 expansion ?? I have had a go at ideal gas calcs but doesn't really help me with KJ per m3 . Have some other toolbox builder for combustion calcs later and a whole host of other technical thinking if required.
