nox processing experiences for removal in the co2 plant ... presentations/s5b … · nox processing...

NOx processing experiences for removal in the CO2 plant for the Oxyfuel combustion processRoland Ritter, Torsten Stoffregen, Linde Engineering Dresden GmbHNicole Schödel, Florian Winkler, Linde Engineering HQ Pullach3. OCC, Ponferrada, 12th September 2013

Linde Engineering Dresden GmbH 3. Oxyfuel Combustion Conference Ponferrada / 12. September 20132

Overview of the Oxyfuel-pilot plant at Schwarze Pumpe

Boiler

Dust filter

FGD

ASU

CO2 plantFGC Control room

operator:Vattenfall Europe

location:Schwarze Pumpe

capacity: 30 MWth

fuel:5,2 t/h (lignite)

O2 consumption:10 t/h (99,5%)

CO2 (liquid): 9 t/h

capex:approx. 70 Mio. €

Start-up: Sept 2008


Oxyfuel technologyCO2 purification and liquefaction plant (pilot plant)

Processpre-compression, drying, liquefaction, rectification with CO2 recycling and liquid storage

Capacity7 000 Nm³/h flue gas

max. 240 t/d CO2 liquid

Purity> 99.7 vol % CO2

Scope of workTurnkey plant

Start-up2008


The challenge of SOx and NOx removal at oxyfuel fired power plants

typical content of SO2 in air fired mode after boiler: 1500… 5000 mg/Nm³

content of SO2 in flue gas in oxyfuel fired mode after boiler

(w/o FGD in recycle flow ): 8000… 35000 mg/ Nm³

typical content of NOx in flue gas in oxyfuel fired mode after boiler:

(w/o DeNOx unit in recycle flow): 500… 1400 mg/ Nm³

ca. 1.5 times increase of

NOx-concentration at boiler

recycled NOx will be reduced

3 to 5 times increase of

SO2-concentration

acid dew point change, serious corrosion

at boiler

source:„CO2 Quality and other relevant Issues“

A. Kather; 2nd Working Group Meeting; 7th September 2009; Cottbus


New process development NOx and SOx removal - background

The flue gas of oxyfuel power plants with CSS has to be purified before transportation and storage.

There are several common technologies for flue gas purification for:

— DeNOx (Selective Catalytic Reduction-unit)

— DeSOx (FGD – lime stone suspension)

— Simultaneous removal

There is a high operation pressure available in the CO2-stream.

new process ideas


Development of the Linde-concept (laboratory)

researched technologies in LINDE-laboratory:1) catalytic reduction technology with reduction media hydrogen and ammonia2) alkali based wash unit with ammonia, sodium hydroxide and ammonia derivate (urea)3) reduction/ regeneration of spent salt solution


Principle units for Oxyfuel technology


Development of the Linde-concept for Oxyfuel technology


LINDE-concept alkaline wash unit LICONOX™ (“Linde cold DeNOx”)

NO and SO2 Oxidation:

NO+½ O2 NO2

SO2 + NO2 SO3 + NO

Alkali based wash unit:

SO2+ 2 NH3 + H2O (NH4)2 SO3

SO3+ 2 NH3 + H2O (NH4)2 SO4

NO + NO2 + 2 NH3 + H2O 2NH4NO2

2 NO2 + 2NH3 + H2O NH4NO2 + NH4NO3

2 NO +O2 + 2 NaOH NaNO2 + NaNO3 +H2O

2 NO2 + 2 NaOH NaNO2 + NaNO3 +H2O

Regeneration/ reduction: NH4NO2 N2 + 2 H20 (Nitrite-decomposition > 60°C)

Ammonia water …

— reaction of NO and NO2

— reaction of SO2 and SO3

results are nitrite and nitrate …

— reaction to a mix of nitrogen and sulfur fertilizer

— reduction to N2 and H2O possible (De-nitrification)

• pre-purified, compressed gas

• moderate temperature

• small gas stream (low volume flow rate)

• smaller equipment

• high conversation rate

• no acid mixture (corrosion problem)

advantages:


Cost comparison of different NOx-removal units

key results of alkaline wash unit tested in laboratory in Linde:

• better opportunity to remove NOx than standard solution

• NOx-conversion of 97 % approved

• simultaneous removal of SOx and NOx

• NOx-removal directed to selective synthesis of Ammonium-nitrite

• option of Nitrite reduction and/ or conversion into fertilizers (nitrate)

Cost estimate Standard SCR solution Fast SCR at elevated pressure with H2 or NH3

Alkaline wash unit at elevated pressure

Conversion rate in % 90 90 85-95

Capital in % 100 140-170 65-70

Operating cost in % 100 80-140 20

Total capex and opex in % 100 120-140 40-50


Alkaline wash unit with real flue gas from oxy-boiler – installation in the CO2-pilot plant Schwarze Pumpe

Atm

.capacity:

200… 700 Nm³/h

30… 40 (80) °C

5… 20 bar

NO/ NO2-

concentration

adjustable

with additional

dosing (cylinder)

using of

15 wt%

ammonia water or 33 wt%

sodium hydroxide


Installation of test facility at oxyfuel pilot plant

process flow diagram of alkaline wash process

installation of column skid

first test campaign:

27.07. – 07.09.2010 using ammonia water

second test campaign:

26.04. – 27.05.2011 using sodium hydroxide


Measuring values / performance

NOx conversation versus operation pressure p1<< p2 and residence time

pressure p1pressure p2

• Converstion rate of NO/ NO2 depending of pressure, temperature, ph-value • Kinetic Model based determination of NO/NO2 profileTarget for future plants:• Selection of DeNOx position (depended from pressure)• Performance simulation based on kinetics for demonstration/ commercial power plant • Column height and diameter determination for NOx removal• Calculation of utility consumption (NH3, NaOH) and also spent salt solution flow rate


LICONOX™ - results of pilot plant laboratory results confirmed

Simulat ion and Comparison with measured Data10bar; 24°C; 6,5vol% O2; pH6,5

0

20

40

60

80

100

120

140

160

180

0 5 10 15 20 25 30

time sec.

NOx

[vpp

m]

0,5

0,6

0,7

0,8

0,9

1

nitr

ite se

lect

ivity

[mol

/mol

]

nit rogen monoxide

nitrogen dioxide

nitrite select ivity

50%55%60%65%70%75%80%85%90%95%

100%

0 5 10 15 20pressure in bar

NOx c

onve

rsio

n pi

lot p

lant

Extended kinetic Model• Consideration of NO2 yield and influence

onto NO conversion• Determination of kinetic rate constants• Nitrite selectivity forecast

NOx conversation rate versus pressure

nitrite selectivity versus NO-NO2 rate on column entry


Development of the kinetic model

NO-conversation versus pH-value

4 NO + 3 02 + 2 H2O → 4 HNO3

4 NO + O2 + 2 H2O + 4 NH3 → 4 NH4NO2

determination of kinetic rate constants

[NO2]/([NO]x[O2]) in dm³/mol

0%

25%

50%

75%

100%

0% 25% 50% 75% 100%NOx conversion simulated

NOx c

onve

rsio

n pi

lot p

lant

Kinetic model confirmed Good correlation between measured data and kinetic model


Reduction of spent salt solution(test phase in Schwarze Pumpe)

possible reduction of spent salt solution:

• NO-NO2 removal with 15wt%- ammonia water 100% (Basis)

• NO-NO2 removal with 33wt%- sodium hydroxide ca. 46%

• NO-NO2 removal with ammonia water and reduction ca. 23%

0

100

200

300

400

500

600

700

800

0 50 100 150 200

Temperture °C

HNO 2

mm

ol/l

pH 7.2pH 7.6pH 7.8

Nitrite-content after reduction versus temperature

Regeneration/ reduction: NH4NO2 N2 + 2 H20 (Nitrite-decomposition)

Cooling Water

Make up Water

spent saltsolution(nitrates)

Ammonia Water

compressedCO2-Gas

purifiedCO2-Gas

nitrite reduction


Advantages of the LICONOX™ - processConclusion

• reduced gas flow in the CO2 plant (three times lower, SCR is arranged after the boiler, were the gas contains the recycle gas)

• the process conditions are “mild” and “moderate”

• raw gas is pre-purified and compressed; smaller equipment are required

• an alkaline solvent has a significantly better capability for removal of NOx compared to water and no complete oxidation of NO is needed

• simultaneous SOx and NOx removal is possible; SO2 adsorption is independent of the NO kinetics and can directly be removed along with SO3 (an oxidation of SO2 to SO3 is not required)

• high conversation rate

• no acid mixture (corrosion problem)

• there is a potential for regeneration of the washing media or the oxidized washing media can be used e.g. as a fertilizer

The pilot phase is complete, the Scale-up is on going and the LICONOX is ready for commercialisation.

The new process has a couple of advantages compared to normal existing hot SCR technology (state of the art) and the washing process with water:

Thank you for your attention

Roland RitterLinde Engineering Dresden GmbHphone +49-351-250 [email protected]

nox processing experiences for removal in the co2 plant ... presentations/s5b … · nox processing...

Documents