Advanced Oxy- Fuel Boilers for Cost-Effective CO2 Capture-Bm

7/29/2019 Advanced Oxy- Fuel Boilers for Cost-Effective CO2 Capture-Bm

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BY PATHFINDERGROUP- 2 & 3

Advanced Oxy- Fuel Boilers

&CO2Sequestration


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Presentation Outline

Program goal and background

Conceptual design of the Advanced Boiler for

Economic advantages

Present laboratory-scale tests Summary


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Program Goal

Develop and commercialize a

novel high efficiency boiler orprocess heater that can provide aCO2-rich product stream that can

be inexpensively purified andcompressed for Sequestration


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A novel process for CO2 sequestration is proposedutilizing a supercritical oxygen-fired PC boiler, which,as part of a Rankine steam cycle, forms a high

efficiency, zero emission, stack less power station. Coalis combusted in the furnace where the oxidizer consistsof a mixture of O2 and recycled flue gas, whichcontains primarily CO2 gas.


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The effluent of the plant is virtually pureCO2, which is condensed, pressurized, andpiped from the plant to the sequestration

site.


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Since the onset of the industrial age, CO2 concentrations inthe Earths atmosphere have increased by about 1-2 ppmper year. This represents a 35% increase in the atmospheric

CO2 concentration in less than 200 years. This increasemay have a profound effect in causing global climatechange. Increased atmospheric CO2 concentrations maynot only cause solar energy to be trapped in the atmospherebut may also increase the acidity of the ocean due to

increased CO2 dissolution .


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CO2 capture technologies

CO2 capture technologies are based upon three generalconcepts: post-combustion capture, pre-combustion capture, and oxy fuel combustion.

Post-combustion refers to capturing CO2 from a flue gas after a fuel hasbeen combusted in air.

Pre-combustion refers to a process where a hydrocarbon fuel is gasifiedand water-gas shifted to form a mixture of hydrogen and CO2 and CO2is captured from the synthesis gas before it is combusted.

Oxy fuel (or O2-fired) combustion is an approach where a hydrocarbon

fuel is combusted in a mixture of oxygen and carbon dioxide rather thanair to produce an exhaust of a mixture of CO2 and water vapor.

Post-combustion capture is conceptually the simplestmethod of CO2 removal.


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Advantages.

Oxy-fuel fired boiler Improve thermal efficiency

Increase fuel savings

Simplify and reduce the cost of CO2 capture

Ultra-low NOx emission

Thermal integration of O2 separation for the boilercauses reduced operating and capital costs for oxy-fuelsystem


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Oxygen source

Traditionally by external air separation unit high cost

Oxygen Transport Membranes (OTM)


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Conventional OTM Process


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OTM-Dilute Oxygen Combustion Concept


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OTM-Reactive Purge Combustion Concept


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Conceptual OTM Boiler Process


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Ash removal is accomplished in a dust removal device (suchas an electrostatic precipitator), which is located between therecuperator and the wet-end economizer. The cold flue gasexits this wet-end economizer and contains primarily CO2

(over 90% by mass) and small amounts of O2 and H2O. Thecold flue gas is split into two streams: 1) recycled to thefurnace through the recuperator (55 70% flue gas flow) and2) compressed and condensed to produce a liquid effluent (30 45% flue gas flow). The preheated recycled flue gas is split

into primary and secondary streams. The primary stream,without O2 addition, is sent to the coal pulverizers, where it isused for drying and transport of the pulverized coal, and exitsthe mill at a temperature 250 350F.


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Economics Case Study

Conventional Advanced

Boiler OTM boiler

Capital Cost (INR)

Boiler 276000000 414000000

Annualized capital cost 47196000 70794000Operating Costs(INR)

Annual Fuel @Rs230/MMBTU 1347800000 1209800000

Annual Power @ Rs2.07/kWh 2438000 69000000

Annual Cost of Oxygen(INR)

Total Operating Costs 1350238000 1278800000

Combined annual Cost 1397434000 1349594000

Oxy-fuel fired boiler

Improve thermal efficiency2 year payback


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Economics Case Study

Conventional Advanced

Boiler OTM boiler

Capital Cost (INR)

CO2 Capture System 1,403,000,000 276,000,000

Annualized capital cost 239,890,000 47,196,000Operating Costs (INR)

Annual Steam @230/MMBTU 269,422,000

Annual Power @ 2.07/kWh 96,600,000 35,650,000

Annual Chemicals 69,000,000

Total Operating Costs 435,022,000 35,650,000

Combined annual Cost 674,912,000 82,846,000

Net Supercritical CO2 Cost 1886/ton 230/ton


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Laboratory-scale Tests

OTM material development

thermal and mechanical stability

long-term operation reliability

high oxygen transport flux

cost effective OTM tube manufacturing

Thermal integration of OTMs with fuel combustion

Multi-tube OTM reactor

temperature control and heat transfer

complete and efficient combustion

very low NOx

more detailed capital cost estimate to meet requirements for cost effective CO2capture


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OTM Material Development

Ceramic membrane is key to program success

Membrane performance tests occur at severe operatingconditions

Membrane material optimization in progress Robustporous support

no tube failures when exposing to fuel

no tube failures during thermal cycles

no tube failures despite events with rapid cool down


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Multi-tube OTM Reactor


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Flow Diagram of Multi-tube OTM Reactor


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Technology Roadmap


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Overall power plant system and componentdesigns are presented for a 475 MW (gross)supercritical coal-fired plant. The power plant

system cycle was optimized to minimize theoverall power plant heat rate and facilitateCO2 sequestration.


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Models of Air-Fired and O2-Fired Furnaces(with right side wall removed)


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Gas Temperature


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Wall Heat Flux


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Oxygen fired Burner


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Summary

Advantages of thermally integrated OTM boiler

Utilize OTMs to supply oxygen for combustion, eliminating the needof an external air separation unit.

Produce high purity CO2 exhaust, significantly reducing the cost of

CO2 capture. Improved efficiency provides economic incentive for

commercialization.

Current laboratory-scale tests

OTM material development to demonstrate material stability andsufficient oxygen flux

Multi-tube OTM reactor experiments to understand the thermalintegration of OTMs with fuel combustion


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PRESENTED BY

COORDINATOR: MR. P.K.SAHA

SPEAKER

SANDEEP SAHUBANAMANLI MOHANTA

PRANAY NAYAN

Thanks


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Oxy-fuel refers to technology thatburnsoxygen withgaseous fuel. As compared to air, which contains 20.95%oxygen, higher temperatures can be reached using pureoxygen. Approximately the same total energy is produced

when burning a fuel with oxygen as compared to with air;

the difference is the lack of temperature diluting inertgases. The most common fuel burned in a torch withoxygen is acetylene; even though it presents specialhandling problems, it has the greatest heat output.

The process has also been proposed as a method of

capturing carbon dioxide from coal-fired electric powerplants because the output flue gases from combustion inoxygen as opposed to air have a higher carbon dioxidecontent fraction.

1 i i l t
http://en.wikipedia.org/wiki/Combustionhttp://en.wikipedia.org/wiki/Oxygenhttp://en.wikipedia.org/wiki/Fuelhttp://en.wikipedia.org/wiki/Airhttp://en.wikipedia.org/wiki/Acetylenehttp://en.wikipedia.org/wiki/Flue_gaseshttp://en.wikipedia.org/wiki/Flue_gaseshttp://en.wikipedia.org/wiki/Acetylenehttp://en.wikipedia.org/wiki/Airhttp://en.wikipedia.org/wiki/Fuelhttp://en.wikipedia.org/wiki/Oxygenhttp://en.wikipedia.org/wiki/Combustion


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1= air inlet2= mechanical energy issupplied3= nitrogen outlet4= oxygen outlet

5= recycled exhaust gas inlet6= fuel inlet (ie coal, ...)7= cold water pipe8= steam inlet pipe9= steam turbine10= steam outlet pipe

11= steam condensor12= cooling pipe of steamcondensor13= bottom ash14= fly-ash removal15= sulpher + gypsum removal

16= cooler17= water condensor (waterremoval)18= mechanical energy issupplied (CO-compressor)19= CO outlet


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oxy-fuel welding, a welding torch is used to weldmetals. Welding metal results when two pieces areheated to a temperature that produces a shared poolof molten metal

oxy-fuel cutting, a cutting torch is used to heatmetal to kindling temperature.


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http://news.bbc.co.uk/2/hi/science/nature/7586569.stm


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AIR SEPARATION

In this first stage, the Air Separator removesnitrogen, which makes up 78% of air. Once thenitrogen has been removed, the remaining product isan almost pure stream of oxygen.

However, there is a downside; the air separationprocess demands a lot of energy and reduces theoverall efficiency of the power plant.


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FUEL INJECTION

At this point, a mixture of coal and oxygen is blastedinto the boiler and ignited.

Many power stations "wash" and pulverise the coal

before it is fed into the boiler. "Washing" actually refers to a process that involves

passing coal through a series of liquids with varyingdensities. This removes many of the impurities found

in coal (the impurities sink in the liquid, allowingthem to be removed easily).


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BOILER

The combustion of the coal and oxygen generates theheat that generates the steam to power thegenerator.

Because the coal/oxygen mix burns at a highertemperature than a coal/air mix, it is necessary torecycle some of the flue gas, primarily consisting ofCO2 and water vapour, back into the boiler to reduce

the overall temperature.


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STEAM TURBINE

The steam generated as a result of heating waterpassed through the boiler in pipes is then used topower steam turbines that generate electricity.

However, the pilot plant at Schwarze Pumpe will notuse the steam to power electricity generators.Instead, the steam will be piped to a nearbyindustrial plant.


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PARTICLE REMOVAL

This is the first of several "cleaning" processes thatthe flue gas will pass through.

At this point, small particles called "fly ash" are

removed from the gas.


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SULPHUR REMOVAL

This stage, which usually involves a process calledflue gas desulphurisation (FGD), removes sulphurdioxide (SO2), which causes acid rain if it is releasedinto the atmosphere.

A mixture of limestone and water is sprayed over theflue gas, which reacts with the SO2 to form gypsum(a calcium sulphate), a material that can be used in

the construction industry.


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COOLER AND CONDENSER

At this final filtering stage, the flue gas is cooled tocondense the water vapour.

Because nitrogen was removed during the air

separation process, nitrogen oxides were preventedfrom forming during the combustion process.

As a result, the remaining gas is an almost purestream of CO2 (formed when oxygen and carbon

atoms bonded together during combustion).


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Combustion in an O2/CO2 mixture (oxyfuel combustion)has been recognized as a prom-ising technology for CO2capture as it produces a high CO2 concentration flue gas.

The Zero Emission Technology (ZET) term is mainlyused to describe CO2 emission abatement; greenhousegas emissions in general can be decreased throughincreased power plant energy efficiency, use of lower

carbon-intensive fuels and greater use of re-newableenergy, and through CO2 capture technologies.


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Oxy-fuel combustion systems

The oxy-fuel combustion process eliminates nitrogen from the fluegas by combusting a hydrocarbon fuel in either pure oxygen or amixture of pure oxygen and a CO2 - rich re-cycled flue gas(carbonaceous fuels include biomass). Combustion of fuels withpure oxygen reaches adiabatic combustion temperatures around

3500C which is far too high for typical power plant materials. Thecombustion temperature is controlled by the pro-portion of flue gasand gaseous or liquid-water recycled back to the combustion cham-

ber. The combustion products consist mainly of carbon dioxide andwater vapour to-gether with excess oxygen required to ensurecomplete combustion of the fuel.

The CO2 capture efficiency is very close to 100% in oxy-fuelcombustion cap-ture systems.

characteristics of oxy-fuel combustion with recycled flue gas


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y y gdiffer with air combus-tion in several aspects including the

following

To attain a similar adiabatic flame temperature the O2 proportion of the gases flowing through the burner is typically 30%, whilein air combustion it is ~ 21%, and about 60% of the flue gas is recycled.

The volume of gas flowing through the furnace is reduced somewhat, and the volume of flue gas (after recycling) is reduced byabout 80%.

The density of the flue gas is increased, as the molecular weight of CO2 is 44, com-pared to 28 for N2.

Without gas cleaning in the recycle stream, emissions including corrosive sulphur gases show higher concentrations than in airfiring.

As oxy-fuel combustion combined with sequestration must provide power to several significant unit operations, such as flue gascompression, that are not required in a conventional plant without sequestration, oxy-fuel combustion / sequestration is lessefficient per unit of energy produced. However, it is more efficient than a conventional plant with sequestration due to thesignificant energy required scrubbing a dilute gas stream prior to compression.

NOx emissions (mass per unit of energy released from the coal) decreases compared to that in air combustion. The reduction wasshown to depend on the oxygen concen-tration due to the change in the flame temperature. However, the difference de-creasessignificantly even if as little as 3% N2 presented.

SO2 emission (mass per unit of energy released from the coal) was not affected sig-nificantly by the variations of O2 or CO2concentration. The decrease in SO2 during oxy-fuel combustion is due to SO3 formation and subsequent sulphur retention.

CO concentration is not a considerable problem. Increasing the oxygen concentration decreased the CO emission. The decreaseof CO concentration along the flame is slower compared to air combustion because of high CO2 gas concentration in oxyfuelcombustion.


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Pre-combustioncapture: Alsotermedfueldecarbonisation.TheprocessistypicallysuggestedtobeusedinconnectionwithInte- gratedGasification

CombinedCycle(IGCC)powerplantswhereitistermedIGCCeCCS. Coalgasificationisappliedtoobtainagas (syngas) containingCO,CO2,andH2. TheCOistransformedintoCO2 by thewater-gasshiftreactionandcanthenbeseparatedfromtheremaininghydrogencontaininggasbeforethisiscombustedinagas turbine.

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Advanced Oxy- Fuel Boilers for Cost-Effective CO2 Capture-Bm