NOx processing experiences for removal in the CO 2 plant for the Oxyfuel combustion process

Transcription

1 NOx processing experiences for removal in the CO 2 plant for the Oxyfuel combustion process Roland Ritter, Torsten Stoffregen, Linde Engineering Dresden GmbH Nicole Schödel, Florian Winkler, Linde Engineering HQ Pullach 3. OCC, Ponferrada, 12 th September 2013

2 Overview of the Oxyfuel-pilot plant at Schwarze Pumpe operator: Vattenfall Europe Boiler location: Schwarze Pumpe Dust filter ASU capacity: 30 MW th FGD fuel: 5,2 t/h (lignite) O 2 consumption: 10 t/h (99,5%) CO 2 (liquid): 9 t/h capex: approx. 70 Mio. Start-up: Sept 2008 FGC CO 2 plant Control room Linde Engineering Dresden GmbH 2

3 Oxyfuel technology CO 2 purification and liquefaction plant (pilot plant) Process pre-compression, drying, liquefaction, rectification with CO 2 recycling and liquid storage Capacity Nm³/h flue gas max. 240 t/d CO 2 liquid Purity > 99.7 vol % CO 2 Scope of work Turnkey plant Start-up 2008 Linde Engineering Dresden GmbH 3

4 The challenge of SOx and NOx removal at oxyfuel fired power plants typical content of SO 2 in air fired mode after boiler: mg/nm³ content of SO 2 in flue gas in oxyfuel fired mode after boiler (w/o FGD in recycle flow ): mg/ Nm³ typical content of NOx in flue gas in oxyfuel fired mode after boiler: (w/o DeNOx unit in recycle flow): mg/ Nm³ ca. 1.5 times increase of NOx-concentration at boiler recycled NOx will be reduced 3 to 5 times increase of SO 2 -concentration acid dew point change, serious corrosion at boiler source: CO 2 Quality and other relevant Issues A. Kather; 2 nd Working Group Meeting; 7 th September 2009; Cottbus Linde Engineering Dresden GmbH 4

5 New process development NO x and SO x 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 CO 2 -stream. new process ideas Linde Engineering Dresden GmbH 5

6 Development of the Linde-concept (laboratory) researched technologies in LINDE-laboratory: 1) catalytic reduction technology with reduction media hydrogen and ammonia 2) alkali based wash unit with ammonia, sodium hydroxide and ammonia derivate (urea) 3) reduction/ regeneration of spent salt solution Linde Engineering Dresden GmbH 6

7 Principle units for Oxyfuel technology Linde Engineering Dresden GmbH 7

8 Development of the Linde-concept for Oxyfuel technology Linde Engineering Dresden GmbH 8

9 LINDE-concept alkaline wash unit LICONOX ( Linde cold DeNOx ) NO and SO 2 Oxidation: NO+½ O 2 NO 2 SO 2 + NO 2 SO 3 + NO advantages: pre-purified, compressed gas moderate temperature small gas stream (low volume flow rate) Alkali based wash unit: SO NH 3 + H 2 O (NH 4 ) 2 SO 3 SO NH 3 + H 2 O (NH 4 ) 2 SO 4 NO + NO NH 3 + H 2 O 2NH 4 NO 2 2 NO 2 + 2NH 3 + H 2 O NH 4 NO 2 + NH 4 NO 3 2 NO +O NaOH NaNO 2 + NaNO 3 +H 2 O 2 NO NaOH NaNO 2 + NaNO 3 +H 2 O Regeneration/ reduction: NH 4 NO 2 N H 2 0 (Nitrite-decomposition > 60 C) smaller equipment high conversation rate no acid mixture (corrosion problem) Ammonia water reaction of NO and NO 2 reaction of SO 2 and SO 3 results are nitrite and nitrate reaction to a mix of nitrogen and sulfur fertilizer reduction to N 2 and H 2 O possible (De-nitrification) Linde Engineering Dresden GmbH 9

10 Cost comparison of different NOx-removal units Cost estimate Standard SCR solution Fast SCR at elevated pressure with H 2 or NH 3 Alkaline wash unit at elevated pressure Conversion rate in % Capital in % Operating cost in % Total capex and opex in % 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) Linde Engineering Dresden GmbH 10

11 Alkaline wash unit with real flue gas from oxy-boiler installation in the CO 2 -pilot plant Schwarze Pumpe capacity: Nm³/h (80) C 5 20 bar Atm. NO/ NO 2 - concentration adjustable with additional dosing (cylinder) using of 15 wt% ammonia water or 33 wt% sodium hydroxide Linde Engineering Dresden GmbH 11

12 Installation of test facility at oxyfuel pilot plant process flow diagram of alkaline wash process installation of column skid first test campaign: using ammonia water second test campaign: using sodium hydroxide Linde Engineering Dresden GmbH 12

13 Measuring values / performance NOx conversation versus operation pressure p 1 << p 2 and residence time pressure p 1 pressure p 2 Converstion rate of NO/ NO 2 depending of pressure, temperature, ph-value Kinetic Model based determination of NO/NO 2 profile Target 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 (NH 3, NaOH) and also spent salt solution flow rate Linde Engineering Dresden GmbH 13

14 LICONOX - results of pilot plant laboratory results confirmed NOx [vppm] Simulation and Comparison with measured Data 10bar; 24 C; 6,5vol% O2; ph6,5 nitrogen monoxide nitrogen dioxide nitrite selectivity time sec. 1 0,9 0,8 0,7 0,6 0,5 nitrite selectivity [mol/ mol] NOx conversation rate versus pressure NOx conversion pilot plant 100% 95% 90% 85% 80% 75% 70% 65% 60% 55% 50% pressure in bar nitrite selectivity versus NO-NO 2 rate on column entry Extended kinetic Model Consideration of NO 2 yield and influence onto NO conversion Determination of kinetic rate constants Nitrite selectivity forecast Linde Engineering Dresden GmbH 14

15 Development of the kinetic model determination of kinetic rate constants NO-conversation versus ph-value 4 NO + O H 2 O + 4 NH 3 4 NH 4 NO 2 [NO 2 ]/([NO]x[O 2 ]) in dm³/mol 100% 4 NO H 2 O 4 HNO 3 NOx conversion pilot plant 75% 50% 25% 0% 0% 25% 50% 75% 100% NO x conversion simulated Kinetic model confirmed Good correlation between measured data and kinetic model Linde Engineering Dresden GmbH 15

16 Reduction of spent salt solution (test phase in Schwarze Pumpe) purified CO 2 -Gas Make up Water Regeneration/ reduction: NH 4 NO 2 N H 2 0 (Nitrite-decomposition) Nitrite-content after reduction versus temperature Ammonia Water compressed CO 2 -Gas Cooling Water nitrite reduction spent salt solution (nitrates) HNO 2 mmol/ l ph 7.2 ph 7.6 ph possible reduction of spent salt solution: Tempert ure C NO-NO 2 removal with 15wt%- ammonia water 100% (Basis) NO-NO 2 removal with 33wt%- sodium hydroxide ca. 46% NO-NO 2 removal with ammonia water and reduction ca. 23% Linde Engineering Dresden GmbH 16

17 Advantages of the LICONOX - process Conclusion 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: reduced gas flow in the CO 2 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; SO 2 adsorption is independent of the NO kinetics and can directly be removed along with SO 3 (an oxidation of SO 2 to SO 3 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. Linde Engineering Dresden GmbH 17

18 Thank you for your attention Roland Ritter Linde Engineering Dresden GmbH phone