New hybrid system design could cut coal-plant emissions in half

Combining gasification with fuel-cell technology could boost efficiency of coal-powered plants

This illustration depicts a possible configuration for the combined system proposed by MIT researchers. At the bottom, steam (pink arrows) passes through pulverized coal, releasing gaseous fuel (red arrows) made up of hydrogen and carbon monoxide. This fuel goes into a solid oxide fuel cell (disks near top), where it reacts with oxygen from the air (blue arrows) to produce electricity (loop at right). CREDIT Jeffrey Hanna

This illustration depicts a possible configuration for the combined system proposed by MIT researchers. At the bottom, steam (pink arrows) passes through pulverized coal, releasing gaseous fuel (red arrows) made up of hydrogen and carbon monoxide. This fuel goes into a solid oxide fuel cell (disks near top), where it reacts with oxygen from the air (blue arrows) to produce electricity (loop at right). CREDIT Jeffrey Hanna

From MIT:

CAMBRIDGE, MA — Most of the world’s nations have agreed to make substantial reductions in their greenhouse gas emissions, but achieving these goals is still a considerable technological, economic, and political challenge. The International Energy Agency has projected that, even with the new agreements in place, global coal-fired power generation will increase over the next few decades. Finding a cleaner way of using that coal could be a significant step toward achieving carbon-emissions reductions while meeting the needs of a growing and increasingly industrialized world population.

Now, researchers at MIT have come up with a plan that could contribute to that effort by making it possible to generate electricity from coal with much greater efficiency — possibly reaching as much as twice the fuel-to-electricity efficiency of today’s conventional coal plants. This would mean, all things being equal, a 50 percent reduction in carbon dioxide emissions for a given amount of power produced.

The concept, proposed by MIT doctoral student Katherine Ong and Ronald C. Crane (1972) Professor Ahmed Ghoniem, is described in their paper in the Journal of Power Sources. The key is combining into a single system two well-known technologies: coal gasification and fuel cells.

Coal gasification is a way of extracting burnable gaseous fuel from pulverized coal, rather than burning the coal itself. The technique is widely used in chemical processing plants as a way of producing hydrogen gas. Fuel cells produce electricity from a gaseous fuel by passing it through a battery-like system where the fuel reacts electrochemically with oxygen from the air.

The attraction of combining these two systems, Ong explains, is that both processes operate at similarly high temperatures of 800 degrees Celsius or more. Combining them in a single plant would thus allow the two components to exchange heat with minimal energy losses. In fact, the fuel cell would generate enough heat to sustain the gasification part of the process, she says, eliminating the need for a separate heating system, which is usually provided by burning a portion of the coal.

Coal gasification, by itself, works at a lower temperature than combustion and “is more efficient than burning,” Ong says. First, the coal is pulverized to a powder, which is then heated in a flow of hot steam, somewhat like popcorn kernels heated in an air-popper. The heat leads to chemical reactions that release gases from the coal particles — mainly carbon monoxide and hydrogen, both of which can produce electricity in a solid oxide fuel cell.

In the combined system, these gases would then be piped from the gasifier to a separate fuel cell stack, or ultimately, the fuel cell system could be installed in the same chamber as the gasifier so that the hot gas flows straight into the cell. In the fuel cell, a membrane separates the carbon monoxide and hydrogen from the oxygen, promoting an electrochemical reaction that generates electricity without burning the fuel.

Because there is no burning involved, the system produces less ash and other air pollutants than would be generated by combustion. It does produce carbon dioxide, but this is in a pure, uncontaminated stream and not mixed with air as in a conventional coal-burning plant. That would make it much easier to carry out carbon capture and sequestration (CCS) — that is, capturing the output gas and burying it underground or disposing of it some other way — to eliminate or drastically reduce the greenhouse gas emissions. In conventional plants, nitrogen from the air must be removed from the stream of gas in order to carry out CCS.

One of the big questions answered by this new research, which used simulations rather than lab experiments, was whether the process would work more efficiently using steam or carbon dioxide to react with the particles of coal. Both methods have been widely used, but most previous attempts to study gasification in combination with fuel cells chose the carbon dioxide option. This new study demonstrates that the system produces two to three times as much power output when steam is used instead.

Conventional coal-burning power plants typically have very low efficiency; only 30 percent of the energy contained in the fuel is actually converted to electricity. In comparison, the proposed combined gasification and fuel cell system could achieve efficiencies as high as 55 to 60 percent, Ong says, according to the simulations.

The next step would be to build a small, pilot-scale plant to measure the performance of the hybrid system in real-world conditions, Ong says. Because the individual component technologies are all well developed, a full-scale operational system could plausibly be built within a few years, she says. “This system requires no new technologies” that need more time to develop, she says. “It’s just a matter of coupling these existing technologies together well.”

The system would be more expensive than existing plants, she says, but the initial capital investment could be paid off within several years due to the system’s state-of-the-art efficiency. And given the importance of reducing emissions, that initial capital expense may be easy to justify, especially if new fees are attached to the carbon dioxide emitted by fossil fuels.

“If we’re going to cut down on carbon dioxide emissions in the near term, the only way to realistically do that is to increase the efficiency of our fossil fuel plants,” she says.

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mrpeteraustin

Great idea; well worth trying. But things like this take a long time to get from concept to widespread adoption, even if they are successful. I’d suggest 20 years minimum. So this cannot make any real difference “in the near term”.

vboring

It isn’t.
Coal gasification is hard. The Kemper County Integrated Gasification Combined Cycle plant is basically the same idea, but with a proven combined cycle plant using the gasified coal instead of a fuel cell. It is ridiculously over budget.
https://en.wikipedia.org/wiki/Kemper_Project
The idea in this article is to take the one part of the Kemper plant that works and replace it with a fuel cell – which is entirely unproven in this application and very likely to fail because of sulfur poisoning and ash contamination.
If you want low CO2 reliable energy at a reasonable cost, you need rational nuclear regulations (overseas nuclear plants cost 25% of what they do in the US because of our regulatory environment) or maybe the Net Power Allam Cycle.
https://netpower.com/technology/

Incorrect about new nukes being 4 times more expensive. New commercial reactors being built around the world are essential the same. Several have design certification from the US NRC. Cost overruns associated with regulation are now occurring in France and Finland. The problem is not the regulators, they are asking the right questions.
Power plant workers in the US are paid a fair wages. In other words, if nukes are more expensive the money stays in the community.

MarkW

I’d be worried about gasses other than CO and CH4 that will be coming out of the gasification process poisoning the fuel cells. Past cells have been quite vulnerable to that.

Catcracking

Understand the Kemper plant is delayed until later this year due in part to refractory problems per the link below.
Are you aware of specifics on mechanical problems? Are they design issues?
http://watchdog.org/253506/kemper-project-10/
Are the problems with the gasification section, which should be the easy part and has been widely demonstrated in other designs?
Mississippi Power’s lignite-fired Kemper County integrated gasification combined cycle (IGCC) power plant is seeing yet another delay and $110 million in new costs, a filing with state regulators shows.
The company’s December 2015 monthly status report for the nation’s first commercial power plant that will capture and store carbon dioxide anticipates that it will now come online during the third quarter 2016, likely by August 31.
In October 2014, the in-service date of the plant whose construction was begun in 2010 was postponed to the first half of 2016. The latest delay means the project is now more than two years behind schedule.”
http://www.powermag.com/kemper-igcc-in-service-date-pushed-to-q3-costs-surge-again/
More waste of tax payer dollars.

catweazle666

“Coal gasification is hard.”
Once upon a time, all town gas was made by gasification by heating the coal in retorts heated by producer gas created by burning coke – a by-product of the process – with a reduced air supply.
The calorific value was often boosted by the addition of water gas created by blowing steam over white hot coke.
http://wondersofworldengineering.com/gasproduction.html
This process was rendered obsolete in the early 1960s by the conversion of the entire country to burn North Sea gas.

pete j

The use of steam promotes reform reactions, not true gasification. You’ll get more hydrogen and less methane but, also more acid gases and hopefully less tar formed. The problem is inorganic metal (ash) fumes adsorbing and condensing (especially in the presence of sulfur) on the solid oxide fuel cell.

richardscourtney

catweazle666:
You say:

Once upon a time, all town gas was made by gasification by heating the coal in retorts heated by producer gas created by burning coke – a by-product of the process – with a reduced air supply.
The calorific value was often boosted by the addition of water gas created by blowing steam over white hot coke.

Sorry, but the making of ‘towns gas’ is NOT coal gasification.
Towns gas was formed by heating coal in sealed containers and the volatiles driven off were seperated to obtain tars and the gas. Most of the coal remained as coke which was mostly used as solid smokeless fuel.
Coal gasification consists of partial combustion so all the coal except for ash minerals is converted to a mixture of combustible carbon monoxide (CO) diluted with incombustible carbon dioxide (CO2). If the combustion is with air and not pure oxygen (O2) then the product gas also includes a substantial amount of incombustible ntrogen (N2). A water gas shift can obtain a contribution of hydrogen (H2) in the product gas to modify its combustion rate.
Richard

catweazle666

richardscourtney: “Sorry, but the making of ‘towns gas’ is NOT coal gasification.
Sorry, but I worked in a retort house for a while in the mid-1960s, and that’s not what my textbooks on coal gas production – some of which predated the turn of the century – said.

johnmarshall

Overseas nuclear plants cost 25% of those in the US? If only.
The new Hinkley Point plant in the UK will cost only £18B plus overruns. The design is rubbish and the two being built in France and Finland are massively over time and cost.
Thorium LFTR’s are cheap.

eyesonu

catweazle666
April 6, 2016 at 11:23 am
Thank you for the link. I have spent considerable time reading and rereading the link. It is absolutely fascinating.

catweazle666

eyesonu, Back in the late 1960s as a young chemical engineer I worked for a short while in one of the last functioning gas works in the country before getting involved in the national conversion to North Sea Gas.
It was all proper 1870s Victorian technology, no concessions to Health and Safety or all that boring rubbish, steam engines and lots of very hot, smelly, dangerous conditions. Controlling the retorts by constantly monitoring the temperatures with optical pyrometers, then adjusting them by moving firebrick slabs over the orifices in the flues with bent steel rods to control the flow of air and producer gas, and keeping track of the calorific value of the gas with the trusty Fairweather recording calorimeter. Not a single piece of automation in the whole plant.
It was the most challenging, arduous, physically demanding ,dangerous place I ever worked in by a big margin, but it was never boring.
Funnily enough, it was also the about the most enjoyable job I ever had!

richardscourtney

catweazle666 :
You say

richardscourtney: “Sorry, but the making of ‘towns gas’ is NOT coal gasification.
Sorry, but I worked in a retort house for a while in the mid-1960s, and that’s not what my textbooks on coal gas production – some of which predated the turn of the century – said.

Either those books or your memory of their content is wrong.
Richard

richardscourtney

MarkW:
You say:

I’d be worried about gasses other than CO and CH4 that will be coming out of the gasification process poisoning the fuel cells. Past cells have been quite vulnerable to that.

Your “worry” is correct because the poisoning is a certainty.
In a past life I operated a study that attempted to use membranes to seperate gases from coal gasifiers. They were all destroyed by combustion products of trace elements in the coal.
Richard

James Loux

Richard at 1:51pm,
Absolutely correct. I have gasified organic materials far less onerous than coal in large and small scale gasifiers, and no fuel cells would operate for long in the gases that were produced, especially after one adds water to the reaction. Steam reforms the gas to increase hydrogen content but also produces other less desirable compounds with the trace elements in the fuel. The cleanest way to increase the hydrogen content is to gasify the fuel with oxygen alone and therefore eliminate the nitrogen in the producer gas. But the trace elements in coal will rapidly poison the fuel cells. Installing the fuel cell stack in the same chamber with the gasification could only work in their computer simulation.

Dave Kelly

” I operated a study that attempted to use membranes to separate gases from coal gasifiers. They were all destroyed by combustion products of trace elements in the coal”.
Concur. Fuel cell are sensitive to deactivation via a variety of contaminates.
For example, In the mid 80’s I had an advisory role in a fuel cell project designed to operate with natural gas. Over my objection, the system was installed using waste methane recovered from a garbage disposal system. Trace contaminates from the waste gas destroyed the fuel cell in a matter of months.
I also worked on early coal gasification projects (TVA’s Ammonia from Coal Project in the early 1980’s) looking at trace contaminates – in anticipation of developing technologies for methanol projection. This early work indicated the presence of trace metals (usually metals) likely to deactivate both methanol and fuel cell catalyst. These contaminates can be removed using known technologies; but, this proposal, which uses of a fuel cell integrated directly with the gasifier appears to gloss over these impediments.
I’d be skeptical of this proposal, unless the authors can point to a specific fuel cell catalyst that can withstand the presence of known contaminates

TA

I bet if ole Trump wanted it done quickly, it would be done quickly.

Greg

“Ong says. First, the coal is pulverized to a powder,…” errm , that’s what pulverized means.

Stephen Richards

Energy for pulverising?

beng135

Stephen, the mechanical energy to pulverize the coal is only a tiny percentage of the plant output — a fraction of a percent.

The coal pulverizers, 6 to 8 of them, use a significant amount of house power. It’s a lot more than a fraction of a percent. Auxiliary power for a coal plant can run 10% to 15% esp w/ AQCS. A NG Rankine or CCPP might use 5% +/-.
An efficiency of 50%? Ain’t gonna happen. Show me the heat balance. 50% of the incoming energy in a Rankine cycle goes out the cooling system, those steamy cooling tower clouds.
BTW, my credentials – BSME, PE and 35+ years in power generation of all types.

higley7

And energy for making steam as well. Fuel cells at the industrial level are going to very difficult, as they are so easily contaminated and would also age at those temperatures.
And the CCS of CO2 is just plain asinine. CO2 is Plant Food. We need more not less. Too many people have been fooled into thinking that CO2 control the climate. Fools are stating this as a given fact on nature shows. No trace gas or any gas at any concentrations can control Earth’s climate. Even if there was a small effect, the natural convection of the water cycle would quickly wipe out any detectable effects. Convection of warm, moist air to altitude is responsible for moving about 85% of Earth’s energy budget away from the surface; this is the missing heat that Trenberth is always moaning about not being able to locate. His world does not have convection.

D. J. Hawkins

@Nicholas
The claim appears to be that the gasification and fuel cell cycles operate at the same elevated temperature to generate electricity directly without expanding steam through a turbine and having to cool the working fluid via towers. It would be good to see a mass and energy balance, however.

beng135

Nicholas — worked as an engineer at a power plant. The horsepower needed for pulverizing and its fractional part of total auxiliary power (which includes ALOT of different processes) is easily determined. I stand by my statement.

Robert of Ottawa

Their concept or burning is rather limited.All oxidation is burning. But, never mind the nonsense about carbon sequestration, if it is more efficient and economical it will be built.

Greg

So iron going rusty is “burning”? OMG my car is on fire.
Maybe you meant all burning is oxidation.

Indeed, your rusting car is technically burning, Greg,
OMG! Maybe you meant to say “I’ll check a dictionary before I attempt to ridicule someone next time,” or something like that.
==========
burn
10. Chemistry.
to undergo combustion, either fast or slow; oxidize
(dictionary.com)
==========

seaice1

“to undergo combustion, either fast or slow; oxidize”
I read that as the combustion may be fast or slow. However “combustion” is “a chemical process in which a substance reacts rapidly with oxygen and gives off heat.” and “In chemistry terms, combustion is any process in which a substance combines with oxygen to produce heat and light.”
This could mean that rusting is not burning, since it is not combustion. It is oxidation. The same amount of heat is released whether the oxidation is slow or fast, so that does not help, but the light I think must refer to visible light, which is not emitted by rusting in any meaningful way.
I have seen all oxidation refered to as burning, I have also seen a clear distinction made- as in the emission of light. It is possible that all oxidation is burning, but I think there is still room for doubt. Can you provide an authoritive definition to settle this interesting point?

Matt Bergin

seaice1 Yes the car’s steel is oxidizing and yes it can be called burning as the reaction does release heat but slowly due to the slow rate of oxidization. Raise the temperature 1200 degrees or so, to speed up the reaction, and watch your car disappear. I remember doing an experiment in high school grade 9 science class, back in the 70’s, that proved that rusting was burning using steel wool and a Bunsen burner and some O2.

Gary Pearse

Oxidation of finely powdered iron may give you the heat and light you need and maybe even an explosion!
http://www.chymist.com/Oxidation%20-%20does%20iron%20burn.pdf
“Note: avoid iron dust-type powders they may be too flammable for this
demonstration.” (!!!)

Heat the iron hot to cherry red, blow a little 100% oxygen on it and you’ll get plenty of flames.

catweazle666

Hey Paul, ever messed with oxygen lances?
They burn very well indeed.
Great fun they are!

beng135

Throw a piece of steel wool in a fire and watch it burn brightly.

Rod

Simplest carbon sequestration would be to pipe all CO2 to greenhouses to boost plant growth. Just need to keep other, potentially hazardous gases out.
As an Engineer I’m critical of the 50% efficiency claim. Energy costs of maintaining power cell efficiency, steam generation and more will all add a cumulatively significant waste.

ClimateOtter

IF, and I do mean IF they made this work, that would make wind power even less useful and more expensive.

Janus100

Don’t worry they will not make it work.
Check Ballard Power, they tried to commercialized utility size fuel cells
And these guys will not even try to make it work. They’ll be just playing In their sand box untill the grant money runs out…

michael hart

Yup. Others above have already pointed out some of the technical failings. If these people had actually overcome some of the technical hurdles then it would be publishable on merit. As it is, it is just speculation and wishful thinking.

Greg

Conventional coal-burning power plants typically have very low efficiency; only 30 percent of the energy contained in the fuel is actually converted to electricity. In comparison, the proposed combined gasification and fuel cell system could achieve efficiencies as high as 55 to 60 percent, Ong says, according to the simulations.

Sounds unlikely on the face of it, though even half of that improvement would be good.
Cut the “carbon” crap, anything that can significantly improve conversion of our resources into usable power is something all side can enthusiastically support.

Greg

Sounds unlikely on the face of it, though even half of that improvement would be good.

No, it is quite plausible: Today’s modern gas turbine combined cycle plants can get up to 60-62% efficiency of fuel use compared to power generated. Older gas turbine combined cycles exceeded 50% routinely. But a claim of 30% (or less) is incorrect: Thermal efficiencies have been higher than 30% since the 1930’s and 40’s – 37-42% for superheated coal plants is expected, depending on the degree of superheat, final steam pressure and cooling water temperature. Nuclear plants are less: 32% to 36% because they cannot superheat the steam from their steam generators. (Note: Most enviro limits NEGATIVELY affect efficiency (which is why Chinese and Soviet power and production were so dirty. Thermal limits on cooling water outlet temperatures, on river water changes, on limits for cooling tower make up water, on bag houses and filters and precipitators and collection and pre-screening washings and coal particle size and stack emissions ALL take additional power, add resistance and maintenance costs and can cost billions to back-install. )

So, can you combine a nuclear plant (to boil the water) with a coal or NG super-heater to boost the efficiency?

Combined cycle power plants can achieve about 60% fuel to MW efficiency. The burning and expanding NG produces electricity (about 30%) per the Brayton cycle, the waste heat from the combustion turbines, about 60%, produces steam w/ a HRSG to power a Rankine cycle, about 30% from the steam turbine generator, about 30% to the cooling system, about 10% up the HRSG stack. 30% + 30% + 30% + 10% = 100%.
An ordinary Rankine steam plant, coal or NG, puts about 15% up the stack, 35% to the steam cycle, 50% to the cooling loop. Condensing exhaust steam back to condensate is where that 50% goes. Thermodynamic fact of life.

Greg

Because there is no burning involved, the system produces less ash and other air pollutants than would be generated by combustion.

So what kind of solid residue ( pollution ) is left? Aside from all the crap about CO2 “pollution” what is left behind. I find it unlikely that crushing coal and wamring it up with produce less residue mass that burning it blast furnace conditions.

MCourtney

By the sound of it, the waste (metals and rock, I guess) would be separated at the gasification stage and thus would be more easily disposed of as a solid or a slurry rather than up the chimney.
There may even be something of value in the extracted waste.
This is a very good idea if it works.

erny72

Hi Greg,
During gasification, the impurities that would form ash during combustion will still remain as residue to be disposed of.
I don’t pretend to be any sort of expert on combustion processes in fixed water tube boilers typical in power stations, but I am a certifiable steam train nut and gasification as described in this article is a similar process to that employed in a gas producer combustion system (GPCS) on some locomotives. If you can read all the way through David Wardale’s book “The Red devil and Other Tales From The Steam Age” you’ll get a good description of how it was developed and tuned up on two locomotives (‘Spooky’ and ‘The Red Devil’) in South Africa in the early 1980s, even then, the concept was not new, even to railway use.
You can also find information on GPCS at Hugh Odom’s ‘Ultimate Steam Page’ or on the Coalition for Sustainable Rail page (the group intending to modify a 1930’s steam locomotive to burn torrefied biomass in a GPCS firebox as a technology demonstrator).
In a locomotive, the two main advantages to GPCS are that the introduction of steam to the primary combustion lowers the temperature to below the ash fusion point, so molten clinker is not formed on the grate (which in turn impedes primary air flow and combustion efficiency). Secondly, since most of the heat is liberated by burning CO, H2 and any flammable volatiles naturally present in the coal in secondary air introduced above the coal ‘fire’ there is less carry-over and ejection out the chimney of unburnt fuel particles.
In all cases where GPCS is employed, the locomotives retain their ash-pan beneath the grate and this still needs regular ash disposal.
Pulverized coal combustion is rare but not unheard of in railway locomotives. The ash liberated has a bad habit of crystallizing around the entrances to the tubes that pass from the end of the firebox or combustion chamber through the boiler. The reason for this is that the ash is liberated during combustion at high enough temperature as to be molten, upon contacting the steel of the tubeplate (which is kept relatively cool by the water boiling on the other side) the molten fly ash sticks and freezes. The ‘bird’s nests’ that form then restrict gas flow through the boiler and also inhibit the transfer of heat through the plates of the inner firebox to the water outside. Both reducing efficiency.
I really don’t know how much of a problem molten fly ash crystallizing on the water-tubes of power station boilers is or how it’s overcome.
In the proposal made here, the impurities which would normally result in fly ash if the coal was burned will still result in ash when the coal is gasified, but the ash will be produced in a relatively cool environment (whether the ash is molten or not depends of the ash fusion temperature of the coal used) and since the oxidizing air appears to be introduced into the top of the fuel cell in couterflow to the produced gas entering from below, the ash particles shouldn’t be carried along by an especially powerful draught (I don’t see immediately where the resulting exhaust is to be vented though).
So from the schematic, I would assume the ash should precipitate out from underneath the ‘grate’ in the gas producer. The ash can then be fairly easily collected and transported to the nearest cement works for incorporation into their eevil hot-air affect causing product.
If on the other hand fly ash is being drawn into contact with the fuel cell or its membranes, then over time the accumulated ash will inhibit the flow of produced gas into the fuel cell and reduce efficiency and/or require some form of mechanical removal either continuously or periodically.
It’s an interesting conundrum and one that would be better understood if the research was conducted practically with a scaled down demonstrator rather than as a simulation (which, being mentioned so early in the press release threatened to trigger my allergic reaction to ‘research’ based on making stuff up, a.k.a. ‘computer modelling’)

One significant difference is the use (direct application) of the pulverized coal – where it is burned and what is burning.
In a conventional pulverized coal furnace-boiler, the tiny coal particles are blown into a cylindrical burner and whorled inside with the combustion air to ignite and burn. The result – very high temperature hot gasses- passes up past the superheater tubes, the boiler tubes themselves, the economizer tuubes, etc and then out the stack. A conventional old steam engine or grate-fired boiler burns large coal particles and actual lumps that get thrown as solids onto a grate, the low-pressure combustion air flows up through the grate and the flames rise above that either into the fireside tubes of the boiler (locomotive) and up the stack or past the water-filled tubes of a land-based boiler then the economizer, superheater and air preheater and stack of a land-based boiler. The burnt ashes (as solid chunks) then fall through the grate onto the track (locomotive) or ash pit (land-based).
But a gas turbine sees the fuel combust at very high pressures (500 to 600 psig) with very high temperature combustion gasses (often above 400 – 500 degrees F). The now 2300 degree burnt gasses at 600 psig get thrown immediately onto the first row turbine blades and turbine vanes. If ANY coal powder or ash particles or contaminates (ash slag) are present at all after burning, those very expensive, ceramic-lined turbine blades and vanes get eroded in weeks.
So most coal-burning gas turbine plans require gasifying the coal first (before burning) to prevent all particles from being burned and hitting the turbine blades and to clean those gasses (to meet poluttion spec’s and prevent slag deposits.) There are several proposals including ceramic-lined high-pressure fluidized reactors, re-circulating burners and condensors of the coal-air-dust mix, etc.)
In every case, it the purified gasified coal that goes into the gas turbine as fuel, and the output exhaust hot gasses from the gas turbine that drive the secondary steam cycle. Much more expensive than conventional single-cycle pulverized coal plants, but much more efficient as well.

I would expect that just not wasting energy by heating the fly ash would boost efficiency a mite.

beng135

erny72 says:
I really don’t know how much of a problem molten fly ash crystallizing on the water-tubes of power station boilers is or how it’s overcome.
Steam-powered slagblowers. Slag can be an issue if fusion temps of the coal-ash are too low for the furnace design — molten ash can “stick” to tubes while solidified ash blows past (the molten ash directly against the tube then quickly solidifies due to the tube’s relatively cool temp). IIRC, calcium in the ash was a problem.

oeman50

I noted that, as well, Greg. How does gasification reduce the amount of ash? If all of the fuel is consumed, the same amount of ash remains, no matter if it is oxidized at lower temperatures or is burned. You would get less NOx but you would have the same amount of SOx that has to be scrubbed out, it kills the catalysts in the fuel cell and is an emission that would have to be controlled.
Fuel cells are normally considered “clean” from an emissions standpoint because they run on natural gas, which has no ash, little sulfur and produces no NOx. That fact this was attributed to a coal fuel source means they don’t understand coal.

MarkW

Would lower combustion temperatures reduce NOx emissions?

Dave Kelly

“Would lower combustion temperatures reduce NOx emissions?”
Generally, yes. But NOx does not matter in a gasification system itself because the gasifier operates in a reducing atmosphere. Hence ammonia is produced – not NOx.
That said, in a traditional combined cycle gasification system, you do produced NOx because the synthesis gas is burned in a turbine down-stream of the gasifier.

Catcracking

Greg,
Correct the bad actors don’t just disappear into thin air. A lot of slag typically needs to be withdrawn from the gasifier somewhere (which can clog the system) and the gases need to be cleaned up removing all the nasties that depart with the gas including the sulfur gases. Based on my extensive experience with gasification the downstream equipment to clean up the gas could cost as much as the gasifier section itself.
Why is the article absent of reality? Is this the JV team with no engineering experience?

Dave Kelly

The solids residues are mostly non-leaching slag. Normally, particulate emissions are exceptionally low. Mainly because what little ash is present is removed when the synthesis gas is cooled prior to entering an acid gas removal system (AGR). The cooling condenses steam in the gas concurrently removing most of the ash. The majority of any other ash is removed in the AGR system or a downstream sulfur recovery system.

Harry Passfield

This’ll never fly. Even if you could – provably – use coal totally emmision-free and cost-free, the Greens would still demonise it and demand it’s banned.

beng135

Exactly. Osama Obama has decreed coal to be banned — period. It’s “dirty”, you know….

skeohane

And carbon is pollution, and we’re carbon-based lifeforms, so we know what he thinks of us…

Analitik

One of the big questions answered by this new research, which used simulations rather than lab experiments

So no real answers were produced – it was a modelled study.
Is this supposed to be science? Why don’t they at produce prototype systems before publishing, these days?

Gamecock

Exactly.
‘This new study demonstrates’
No it doesn’t. Simulations don’t demonstrate.

Greg Woods

Ditto that…

Chris Z.

@ Analitik “Why don’t they at produce prototype systems before publishing, these days?”
Because this is “science”, not “engineering” which it’s become fashionable to look down upon (viz. all the stuff on the web glorifying Tesla and smearing Edison!) – You are perfectly right that this kind of daydreaming theoretical research leads nowhere and helps nobody. Only a machine that’s actually built and works as described has any practical value.
This is what you get from valuing imaginary “intellectual property” higher than hands-on work!

Christopher Paino

“(viz. all the stuff on the web glorifying Tesla and smearing Edison!) ”
I get what you’re saying, but, if for naught but Topsy, Edison should be smeared.

Katherine

Exactly. And they claim their study “demonstrates” that the system produces two to three times as much power output when steam is used instead. Nope, until they build a prototype to test the proposed system, they haven’t demonstrated anything.

The reason you do not see gasification prototypes anymore is that they are all epic failures. It has been around forever but destroys whatever you use to convert the gas to electricity.
It used to be called ‘producer gas’ or ‘city gas’. AKA, superfund site to clean up legacy waste.

Why don’t they at produce prototype systems before publishing, these days?

Because it’s actually hard to build stuff that works. Computer models on the other hand a pretty easy. Simple.
Computer modeling is an abused method now. In the early days it was a way to filter out obviously bad ideas before you had to spend real time and effort building something incompatible with basic math. Now it’s become an end in itself for folks who never will build anything that actually works. Their entire purpose is to stay on the grant list gravy train. It’s a failure of the academic infrastructure and it’s particularly damning when it shows up at MIT.

Analitik

Why don’t they at produce prototype systems before publishing, these days?

Thanks everyone for ignoring me leaving out the word “least” in the above sentence. I’ve been cringing every time I see it quoted.

dccowboy

“Most of the world’s nations have agreed to make substantial reductions in their greenhouse gas emissions”
I wonder what they are basing that broad generalization on? Surely not the COP21 ‘agreement’ as the world’s nation’s made no commitment to reduce CO2 emissions at all, especially the Chinese, who appear to have agreed to continue increasing their emissions at their current breakneck pace until at least 2030.

ferdberple

agreed to make substantial reductions in their greenhouse gas emissions
=====================
exactly. the agreements were to reduce the rate of growth from one imaginary number to another imaginary number, with the first world to pay the tab using money borrowed from the countries not paying the tab.

emsnews

Note how the end goal of all this is to bury the CO2 in the ground. They are very serious about reducing CO2 to Ice Age levels.

Paul

Not sure if it applies to coal, but I’ve read that sulfur poisoning of fuel cells is a big problem?

Fuel cells are very sensitive to contaminants. Most coals contain sulfur. Removing it before the fuel cell adds complications = costs.

Gamecock

I’m not going to try go research it, but I believe a commercial power plant sized fuel cell has never been built. Simulating is easy.

Fuel Cell have been used in small biogas plants especially California. Have not seen anyone bragging about long term viability. Less efficient but much cheaper is an internal combustion engine. Many of those still around.

Janus100

There have been could of the built
I remember 4MW station in Japan built back in 1980.

oeman50

A 15 MW fuel cell facility went into service in 2013 in Bridgeport Connecticut that was manufactured and is operated by FCE, Inc. It is owned by a utility. The sulfur compounds in the natural gas fuel supply that are added as odorants are removed by an absorber vessel.

Dave Kelly

“I believe a commercial power plant sized fuel cell has never been built”
You’ve hit the nail on the head. I like the fuel cell concept and I like to the idea of combining gasifier with fuel cell… but the current impediment to both are current limitations on size. The bottom line is that fuel cells undergo a considerable thermal strains during start-up and shut-down. This has limited the size of the units that can be built.
I’d be ecstatic to have operating commercial fuel cell in the 250 mega watt size range. But, we are not there yet.

dudleyhorscroft

The bottom end of the system is basically the 200 year old (nearly) standard method of making “Water Gas”. This was the standard gas, plus “Coal Gas”, used domestically in the UK for heat and light for over a century. Only superseded when North Sea Gas came on line. A favourite method of committing suicide, known as “putting one’s head in the oven” – figuratively and literally.
Trouble is production of Water Gas needs heat to sustain the reaction. So air has to be added now and again to keep it going, which produces carbon dioxide. A mixture of H2 and CO (Water Gas) may be usable in a fuel cell, but surely the addition of CO2 would have a deleterious effect. and if you are going to try to get rid of the CO2 you are putting more complication and cost into the process. If you add air, you also add nitrogen – another contaminant, but more costly you could use pure oxygen!
According to the Australian Institute of Energy:
“Increasing efficiencies are being achieved with conventional single cycle plants. The use of supercritical conditions and a cold final cooling water source allows a power station in Denmark to attain over 45% efficiency, the world’s highest for an operational, single cycle, large coal-fired plant.”
In cogeneration or combined heat and power (CHP) plants waste heat is utilised, typically for district heating or for an industrial process. Total efficiencies of 80% are typical.”
So their improvement of 55% over a quoted 30% for coal fired plant is a little disingenuous – should be 55% over 45%. But again, if you can use the low grade heat from the water used to condense the working fluid, you can get 80%. This can be, and in towns sometimes is, used for district heating, but it could also be used for desalination plants, and I suppose it could be used in heat pumps to increase the grade (temperature and pressure) of a portion of the exhaust gases to run low pressure/temperature turbines, delivering additional power. There is a lot of energy wasted in those cooling towers which adorn most news items about “carbon dioxide pollution”.
District heating systems are used in a number of countries, with the New York system the largest in the world (naturally!). Plausibly the waste steam could be used for heating water and rooms and gardens. Australia requires hot water tanks to maintain a temperature of at least 60C (anti-legionnaires disease), but plumbing fixtures should not pass water hotter than 50C. Room heating in winter would be to around 22 to 25 C. Garden beds could be heated to any suitable temperature depending on the plants to be grown – not really feasible for the home garden, but plausible for garden centres and horticulturalists in cold areas of Australia and even more so in places like the UK. Locally grown “sun-ripened warm tomatoes” in January! As a schoolboy in Croydon, we visited the Croydon Gas works and power stations, and I fantasized about the use of the waste heat in the cooling towers instead being piped under the soil of the acres of waste land around the power station site, which could have turned the area into a “Palm Garden and Spa Resort” for Croydon and South London. A good tourist destination, similar to the hot pools and springs of New Zealand.

erny72

Hi Dudley,
With that in Mind, you’d wonder why the academics feel the need to postulate capturing CO from the exhaust, compressing it and transporting it off for disposal; why not direct both the heat and the plant food (CO2) to a co-located industrial nursery/green house and make actual use of both waste streams (and serve up a visible monument to help tree-huggers sleep soundly at night) instead of sweeping it under the rug for how ever long the chosen aquifer and it’s injection wells last before inevitably leaking?
interesting you mention Nitrogen, in combustion it’s just along for the ride, scavenging some of the heat produced while it gets in the way. If the combustion temperature is high enough, N2 will also waste some of free oxygen and react with it to form real pollutants like NO and NO2; I wonder what efficiency impact there is in a fuel cell that is 70% full of spectator gas on the inlet side and full of NOx on the exhaust side?
While on the subject of spectator gases, any sulphur liberated from the coal during gasification will form SO2 in the presence of oxygen, in steam locomotives, this is one reason for not attempting to lower the temperature of smokebox gases too far (by making the ‘cool’ end of the boiler too efficient) as in the presence of steam or water vapour, sulphuric acid can be produced which hastens corrosion.
How do fuel cell internals react to SO2, or H2SO4? I don’t see any remarks in the press release relating to the use of limestone sand in the gasifier as a sulphur scavenger (as could/would be present in the case of a fluidized bed furnace for example).
Come to think of it, the press release on this study doesn’t mention any consideration of SO2/NOx or fly ash abatement at all, surely all more fundamental forms of pollution than the one gas they seem to obsess over.

dudleyhorscroft

erny72 April 6, 2016 at 6:13 am said:
“With that in Mind, you’d wonder why the academics feel the need to postulate capturing CO [should read CO2] from the exhaust, compressing it and transporting it off for disposal; why not direct both the heat and the plant food (CO2) to a co-located industrial nursery/green house and make actual use of both waste streams (and serve up a visible monument to help tree-huggers sleep soundly at night) instead of sweeping it under the rug for how ever long the chosen aquifer and it’s injection wells last before inevitably leaking?”
They feel that need because they are (a) daft, and (b) are not yet ready to recognize that Carbon Dioxide is a valuable raw material/fertilizer.
Re your earlier comment: “I really don’t know how much of a problem molten fly ash crystallizing on the water-tubes of power station boilers is or how it’s overcome.” I think you will find that the fly ash although it settles on the outside of the water tubes does not restrict air flow, and therefore can be left for some time, while much continues past and settles on the soot in the exhaust pipes and funnel. On the water pipes it can probably be left till the boilers have a chance to cool, when a rap with a hammer is sufficient to break it off, rather like the scale at the bottom of an electric kettle in a hard water area. Up the tubes, the soot does not form a hard coating, and on passenger steam ships it was normal at some time during the middle watch (0000 – 0400) for the duty engineer to ring up the bridge and ask if it was OK to blow the tubes. If necessary, course would be altered (other shipping permitting) and the bridge would give the OK. Blasts of steam would then be directed up the funnel, blowing all the soot out of the funnel, and hopefully overside. Woe betide the engineer who forgot to ask, if the wind direction was such that red hot soot and sooty water was directed over the Chief Officer’s beautifully scrubbed decks and canvas awnings!!!!! Especially if passengers (female) were basking in the cool night air on deck!
On at least one ship – diesel with an exhaust boiler – in Calcutta the internals of the boiler were cleaned by shore staff who used a ladder to enter the boiler from above, using a wooden ladder down from the top of the funnel. Unfortunately they forgot to remove the ladder! After we sailed, eventually the ladder got so hot and dry that it burst into flames and pieces of burning ladder blew out the top of the funnel, some landing in a lifeboat and setting a sea anchor on fire, plus damaging the fibreglass hull of the lifeboat. People were not happy!

richardscourtney

Dudley Horscroft:
You wrongly assert

The bottom end of the system is basically the 200 year old (nearly) standard method of making “Water Gas”. This was the standard gas, plus “Coal Gas”, used domestically in the UK for heat and light for over a century.

No! Coal gasification product and towns gas are very, very different.
Please see my above post in reply to catweazle666 who made the same incorrect assertion as you have.
Richard

dudleyhorscroft

Greg April 6, 2016 at 3:33 am asks: “So what kind of solid residue ( pollution ) is left?”
Exactly the same sort of ash that is left when you burn coal in an ordinary open fire or a power station. This is known as “fly ash” from the fact (I suppose) that in early days the draft was sufficient to lift it up the chimneys from which it would ‘fly’ over the surrounding countryside. Way back in the 1940s this was caught by electrostatic precipitators before going up the chimneys and then disposed of. In the UK it is used to fill up disused quarries. I believe BR runs special fly ash trains from power stations to quarries (but may be wrong).

Catcracking

Dudley
Normally it is slag because of the temperatures of the gasifier are circa 1800 F.. Hot slag is not easy to handle either.

chris y

GE worked on coal gasification for decades, high temperature fuel cells, designs steam generators and designs gas turbines.
It is implausible that GE never looked at this idea in great detail in the 1970’s.
The diagram reminds me of how undergraduates sometimes do a homework problem when the answer is given. Start from the beginning, then work backward from the answer, and then muddle the middle bit.
This study is missing all the middle bits that turn it into a working hardware prototype.

Dave Kelly

I’ve worked with GE on gasification designs. At nearly every step they attempted to sabotage real progress.. to the point we quite collaborating with them. The bottom line is GE wants to sell squeeze every dollar out of standard natural gas turbines designs and does not want to invest gasification optimized designs. And it’s well know to be hostile to fuel cell designs,.

seaice1

There are theoretical advantages to this sort of system – from wiki “Practical fossil-fuel stations operating as heat engines cannot exceed the Carnot cycle limit for conversion of heat energy into useful work. Fuel cells do not have the same thermodynamic limits as they are not heat engines.” So we can get a thermodynamic improvement in theory. This is a long way from practical yet.
This sort of system could also be the answer to energy storage from renewables. If fuel cells can work on this scale we can use the electricity to generate hydrogen and then use th efuel cell to generate power when needed.

http://www.engr.uconn.edu/~jmfent/CHEG320_thermodynamics_extended%20notes.pdf
Been a long time since my college thermo class. First pass this is over my head, would take some study. Fuel cells are different, but the fundamentals of thermo apply to more than just Carnot heat engines. The author explains it well, just ignore the calculus.

Dave Kelly

Thermodynamics describes the limits associated with the production of work by heat transfer. Fuel cells are about the direct conversation of the gases internal chemical energy to electrical energy.
As no conversion from heat to work is occurring in a fuel cell, the fuel cell does not experience the thermodynamic limitations of a “heat engine”. Consequently the energy transfer occurs at a higher efficiency than theoretically achievable by the traditional “heat engine”. In theory the efficiently can approach 100%, in practice 50-60% conversion is actually achievable.
Normally the “efficiency” limitations of fuel cells experience are related to the percent conversion of the related chemical reactions. So, typically, you have a cost trade off between recycling unconverted “fuel” or simply burning off the unconverted fuel and recovering the remaining fuel energy using a heat engine.
In addition, fuel cells operate with better chemical “efficiency” at high temperatures. So, typically, industrial scale fuel cell designs utilize down-stream steam-base heat/steam turbines systems to recover both the thermal energy associated high temperature operation and the chemical energy associate with the unconverted fuel.

lowercasefred

The Southern Co, through Mississippi Power has a combined cycle plant under construction at Kemper, MS. They tout it a lot, but whispers are that costs are running way over budget and all is not roses.
https://en.wikipedia.org/wiki/Kemper_Project

NG fired combined cycle plants are common, efficient and successful. Integrated coal gasification w/ CCPP are not.

Dave Kelly

True, but Kemper is a 1st of a kind design. It’s not an Nth generation design. Duke’s Indiana plant also experience cost over-run and initial operating issues… but again this was not an Nth generation construction for the utility industry.
I’ve been to both plants and am familiar with the people involved. My take is both companies made a mistake in trying to cut he construction cost of the initial designs by compressing the size of the down-stream equipment footprints. In both cases this resulted in the construction crews not having enough physical space to efficiently construct the facilities. Hence, the cost overruns. In addition, In Kemper’s case, I’d have gone with an oxygen blown system to decrease the equipment sizes from the gasifier down-stream.
The Tennessee Valley Authority (TVA) learned these lessons BEFOR it built the United States first commercial scale coal gasification system in Muscle Shoals, AL, in the 1980’s. (I.e. TVA’s Ammonia from Coal Project). I know because I was part of that team. In fairness to Southern and Duke, these particular lesson’s were not part of their experience in part because the TVA team broke-up and went on to other things.
Also, in fairness to Southern and Duke, the art of building gasification systems is quite different from that for constructing pulverized coals systems. Simply put, well established techniques used in traditional utility construction are going to get you into trouble when constructing gasifier-based systems. So, you have to overcome a good deal of institutional inertia/prejudice all the way to the executive level.
Finally, I’m going to be frank, the people at Southern and Duke did a outstanding job given the challenges they faced. They were professional and though at every step… and I cannot and will not say they didn’t do a superb job. Indeed they took considerable pain to address known technical issues and showed considerable imagination and skill in overcoming those issues… particularly with regard to potentially improving the units capacity factors.
Its just that people and companies have to learn some real-world lessons the hard way. No paper design, cost estimate, or A&E assurance a technology is “off the shelf” is meaningful. The only way to learn these real world lessons is to built a facility. The real measure of success it wither the lesson’s learned will be adopted and construction costs reduced.
[Telling summary. Thank you. .mod]

MarkW

If the efficiency improvements are enough to justify the capital costs, then I’m sure that energy companies can be convinced to try this out on their own without any incentives from government or anyone else.

richardscourtney

MarkW:
You say

If the efficiency improvements are enough to justify the capital costs, then I’m sure that energy companies can be convinced to try this out on their own without any incentives from government or anyone else.

Not so. Air blown gasification combined cycle (ABGC) has similar efficiency to that claimed for the above hypotetical power generation system. But the the developed ABGC system is not adopted because of the cost of novelty risk. Instead, small improvements to proven superctical PF are adopted because they have low novlty risk although they provide small efficiency gains. Simply, economics rules and not technology.
Richard

Kaiser Derden

probably works great in the lab and generates 100 watts of power …

Remarkable Claim
So where is the remarkable evidence ?
..Are we to believe that big energy corps are so dumb that they have been burning coal at half the efficiency that was possible ..when there was this easy solution ?
This magic solution stuff is typical of the green energy brigade.
..If anything works as well as these people claim then it can be built subsidies or special favors.

Great discussion of an indifferent original post.

This would be similar to the Quest Carbon Capture and Storage project in the Canadian oil sands, which cost $1.35 billion and received very little support from environmentalists. Some were hesitant and skeptical but some were outright against it, I would say there was more OPPOSITION than support. I guess it makes sense that capitalists thought the environmentalists would be appeased by simply removing the carbon they were complaining about, but it just didn’t happen. This topic is a classic because it exposes the hypocritical nature of the environmental movement. Removing carbon from the atmosphere is not the goal. Big government, and industries dependent on subsidies, is the goal.

Peta in Cumbria

Assuming that the reddish cylindrical bit is resistor or electrical load of some sort and not a battery, I can only conclude that we are being led to our doom by legions of stupid stoopid dumb-ass people.
How can the supposed boffins at MIT get the electrons going the wrong way….

Waste is bad, right?
So stop calling it waste. It is the heat of rejection. Something is a waste only if there is not a use for it.
More often than not, the energy to pump hot water is greater than the energy recovered. It is a case of diminishing returns. I have been asked many times about decay heat from the fission products. We are pretty busy producing 1200 MWe to worry about a 0.5% efficiency improvement.
There is less tactical way of saying it. You have a serious mental disease of you obsess about waste.

“(b) are not yet ready to recognize that Carbon Dioxide is a valuable raw material/fertilizer.”
How much will you pay me if it is so valuable. CO2 is a byproduct of producing nitrogen fertilizer by Haber Bach. The supply is huge demad is tiny.

tadchem

To produce power comparable to a moderate-sized US power plant (500 MW) from hydrogen-oxygen fuel cells with individual voltage outputs of 1.23 volts will require enough cells to generate 400,000,000 no-load amps. Under load, the output of such a fuel cell drops to between 0.5 and 0.8 volts, so the actual capacity of the plant would have to be 1 billion amps. That’s the equivalent of several THOUSAND lightning bolts of current – continuously.
That’s also a LOT of metal-oxide catalyst for the operation of the fuel cells, the mining of which has its own negative environmental impacts. http://www.news.com.au/travel/world-travel/asia/baotou-is-the-worlds-biggest-supplier-of-rare-earth-minerals-and-its-hell-on-earth/news-story/371376b9893492cfc77d23744ca12bc5
Furthermore, the direct current (DC) would have to be converted to alternating current (AC) for transmission. This ‘inversion’ of DC to AC loses about 10% of the power.

ghl

And don’t forget the cost and energy to produce pure oxygen for the input.

Logoswrench

Maybe the could pump that deadly dangerous CO2 into something like, oh I don’t know a greenhouse for plant food because CO2 IS NOT A HAZARDOUS MATERIAL.
And don’t fuel cells generate DC? So all we then need is place for the CO2, a place to put the ash, a ginormous inverter, and we are back to coyote and road runner status. Is this Powerplant going to made by ACME?

Gary Pearse

If the process can be demonstrated, it will work scaled up. It may require more experimentation and problem solving, but it will work. I’ve always been a believer in R&D. In a talk about 30 years ago, I supported this by noting that IBM had a bigger research budget at the time than the entire country of Canada’s combined R&D. My thought was companies like that didn’t do stuff that didn’t have a reasonable probability of becoming profitable. Detractors on gasification/fuel cell experience notwithstanding, if it can be shown to work on the bench, it will work eventually at full scale. They’ve already demonstrated gasification long ago – it will be done.
I was a chokerman in B.C. logging camps in 1957-58 and listened to arguments about going to the moon and the like – all but me believing it could not be done. I remarked that the hard part was counteracting gravity to get into orbit but it had been done for Sputnik which was only the beginning. I was branded a bit of a nut, but I recall being deadly certain it would be done.

jorgekafkazar

I have no experience in logging camps, but I worked on the design of two coal gasification plants. It is absolutely false that every process can be scaled up from lab size to industrial size. And all this is to reduce CO2 “emissions.” Fuel cell input with coal gasifier output? It’s ridiculous and will only happen if the price of petroleum is forced up by carbon taxes and similar Fascist nonsense. Remember, this kludge comes from MIT, home of the Climate Roulette Wheel:
http://news.mit.edu/sites/mit.edu.newsoffice/files/styles/news_article_image_top_slideshow/public/images/2009/200908311113506360_0.jpg?itok=OiSXfou7

Brian R

A simple question. How is the steam produced?

Gary Pearse

From the waste heat of the fuel cell (800C)

Brian R

Effective coal gasification requires temperatures of about 800C. Since there could never be 100% conduction of heat between the fuel cell to the gasifer, the losses would mean there isn’t enough heat from the fuel cell reaching the coal to effectively gasify it. This leads to less gas to react in the fuel cell which in turn means a lower temperature in the fuel cell. Repeat cycle a few times and the entire process grinds to a halt. That is unless you have an external source for the high temperature steam. But then if you had that, you wouldn’t need to gasify coal.

Tom in Texas

RACookPE1978 says:
April 6, 2016 at 9:37 am
So most coal-burning gas turbine plans require gasifying the coal first (before burning) to prevent all particles from being burned and hitting the turbine blades and to clean those gasses (to meet poluttion spec’s and prevent slag deposits.) There are several proposals including ceramic-lined high-pressure fluidized reactors, re-circulating burners and condensors of the coal-air-dust mix, etc.)
I am just an ol’ texas boy, but how do the particles from the fired system transfer through the tubes to the steam portion to hit the blades? Please clarify. thank you

richardscourtney

Tom in Texas:
You ask

how do the particles from the fired system transfer through the tubes to the steam portion to hit the blades?

The particulates need to be removed from the gas or they will damage the gas turbine. This can be achieved by use of Foseco candle filters which I invented for cleaning combustion product gas prior to its use in the gas tubines of PFBC power statioins.
Richard

Dave Kelly

The problem with candles, correct me if I’m wrong, is that they tend to break.
If I’m wrong, please point me to some data… as I’d be interested.

richardscourtney

Dave Kelly:
You say

The problem with candles, correct me if I’m wrong, is that they tend to break.
If I’m wrong, please point me to some data… as I’d be interested.

Yes, solid but porous ceramic candles are brittle and if a single candle in a bank breaks then most (yes, most) of the gas flows through the broken candle so bypasses the filtration. The brittleness results in candle failures because a flaw in the material propagates as a crack through the structure of a candle when reverse pulsing is applied to remove filter cake.
It was to overcome this problem that I developed the Foseco candle filters which we at the UK’s Coal Research Establishment (CRE) repeatedly tested at full scale in attempts to induce damage to them. The developed Foseco candle filters sacrifice strength to provide toughness.
They consist of ceramic fibers with an addition of high temperature cement as a binder. Extra cement is concentrated at the outer surface by filtering cement particles from suspension in a fluid. The structure is then fired to become a candle filter. Flaws don’t propagate as cracks through this structure: a flaw results in a joint between two fibers failing.
The main problem in developing these candle filters was that there is no clear demarcation of a candle’s filtration surface and, therefore, reverse pulsing blasted zones of the candle material away with filter cake. This was overcome by increasing the concentration of the binder cement in the surface zone.
The performance of these filters is known to Foseco and to UK government. I don’t know if this information was ever published in the public domain but I suppose Foseco would provide it to potential purchasers. As an ex-employee of CRE I am not at liberty to provide it (I need to keep my pension), but I know we didn’t manage to fail the developed Foseco candle filters exposed to real conditions and we demonstrated that flaws would not propagate as cracks through their structure.
Richard

Alcheson

Interesting they note that assessing additional fees on the CO2 produced would be necessary to make it cost competitive with other means for producing energy.

I like the idea of combining gasification with fuel-cell technology which could could boost the efficiency of coal-powered plants. It is always worthwhile working on increased efficiency and reduced costs. The only downside could be that the reduction in emission of CO2 could adversely impact on future plant growth and crop yields.

Why do you like the idea again? Inexperienced grad students have an idea. Experienced engineers explain that it is not worth while.
I have some land in Florida that you may think is a good idea. How about some solar panels for your roof..

Fred of Greenslopes

For those interested in coal gasification for electricity generation I would recommend a visit to the Powerhouse Museum in the Queensland outback town of Longreach. For 65 years from 1922 it provided power. Coal was burned to heat larger quantities of coal, thus driving off gas to power modified marine diesel engines which turned the generators. Why not use boilers? The local bore water is so hard that scaling is not controllable. The museum is staffed by volunteers.

eyesonu

A lot of engineers have commented on this thread. The intellectual focus on WUWT is astounding.
Me? I’m just absorbing it all.

“Thorium LFTR’s are cheap.”
The verb ‘are’ infers that such plants have been built as commercial reactors. Sorry your paper reactor is a figment of your imagination.
Of course all steam plants are expensive to build. Going on the cheap is a good way to have a pile of scrap metal in a few years.
“The design is rubbish…”
Really! So JohnMarshall is an expert on reactor design and has worked on the EPR.
Oh wait I am an expert on the EPR as well as other designs of PWRs and BWRs. I have yet to find a bad design. I think of several examples of where the one group of people took the same design and executed the construction well and another group had an epic failure. From personal experience, the former is a source of great job satisfaction and the latter is a source of great frustration.

Louis

“If we’re going to cut down on carbon dioxide emissions in the near term, the only way to realistically do that is to increase the efficiency of our fossil fuel plants.” –MIT doctoral student Katherine Ong
Right on the money! And it comes from a student at MIT, of all places. I just wish more college students could think well enough to draw similar conclusions instead of just accepting and regurgitating the propaganda they have been taught.

That assumes existing plants are not already efficient.