Advanced NOx control by combining in-furnace fuel additive combustion technology and SNCR

Transcription

1 Advanced NOx control by combining in-furnace fuel additive combustion technology and SNCR Marc Ottolini CEO 6 September 2016 William Nimmo & Syed Sheraz Daood, Energy Engineering Group, University of Sheffield, UK 11 th ECCRIA Sheffield, United Kingdom

2 Silanite TM Fuel Enrichment additive Patented fuel additive system for coal-fired power stations Multiple benefits: 3.4% volume equivalent additive yields: 1.1% increase in boiler efficiency 8-10% NO x reduction About 20% reduction in dust and particulate emissions Significantly better quality fly ash > 40% corrosion reduction 2016 IIT Ltd 2

3 Fundamental science 2016 IIT Ltd 3

4 First evidence of cracking of hydrocarbons Nitrogen Thermocouple Coal First Furnace Fuel improver Second Furnace Gaseous compositions RC ACFI WCFI d(0.9) < 75 µm d(0.9)<35 µm d(0.9)<35 µm CO Thermocouple H Condenser System Gas Sample Bag CO CH C 2 H C 2 H IIT Ltd 4

5 Fundamental science The effects of Silanite TM are based on 2 key mechanisms: Additive particles interact with coal particles causing heavier hydrocarbons to crack into lighter hydrocarbons increased gas yield more complete combustion Iron oxide in fuel additive acts as catalyst causing additional NO x reduction reactions 2016 IIT Ltd 5

6 IIT Combustion Test Facility 100 kw th test rig to simulate Power Station operating conditions 2016 IIT Ltd 6

7 Silanite TM additive: full-scale 233 MW th boiler SembCorp Utilities Ltd: Test coal boiler ton/h max. steam operating flow 170 ton/hr minimum steam flow Furnace dimensions = 29m x 7.5 m x 7.6 m Throat diameter for burners: 650mm, 12 burners placed in 3 landings Forced-induced draft fans = 2 each; Electrostatic precipitator; Doosan ball/ ring type coal mills; Main steam output splits into HP and IP steams. Plant related data recorded by Delta V control system 2016 IIT Ltd 7

8 Silanite TM additive: Test plan Test Regimes- Description of activities Time Regimes Description 7:30 to 10:20 Coal baseline 10:20 Silanite additive injection started 10:20 to 11:00 Transition from coal to additive plus coal 10:40 to 15:00 Additive + coal steady state 14:44 to 19:00 Coal mill loads on both B and C mill started to increase 15:00 Additive injection stopped 15:00 to 15:30 Transition from additive plus coal back to coal only 15:30 to 16:30 Coal ending baseline; not steady state as the coal mill load kept on increasing due to customer demand IIT Ltd 8

9 Silanite TM additive: NO reduction 8.4% reduction in NOx for 3.4 vol. % Silanite Injection NO Ox (mg/nm m 3 ) Coal baseline Average = Max based on standard deviation = Min based on standard deviation = NOx Coal plus additive baseline Average = 517 Max based on standard deviation = 543 Min based on standard deviation = 491 coal mill load increased 05:52:48 07:33:36 09:14:24 10:55:12 12:36:00 14:16:48 15:57:36 17:38:24 Time (h:min) Air calibration purged 2016 IIT Ltd 9

10 Silanite TM additive: Flame zone temperature Temp ( C) coal baseline coal + 6.8% additive coal ending baseline 2016 IIT Ltd 10

11 Silanite TM additive: Loss on Ignition > 40% reduction in LOI 2016 IIT Ltd 11

12 Silanite TM additive: Boiler efficiency Net improvement boiler efficiency > 1% The main influential l factor for the higher net boiler efficiency is the unburned combustion content in the fly ash with and without the additive. Net boiler efficiency according to BS EN : IIT Ltd 12

13 Silanite TM additive: improved dust collection in ESP 2016 IIT Ltd 13

14 Silanite TM additive: Risk assessment Risk assessment conducted in 2014 with inputs from Sembcorp, Parsons Brinckerhoff and University of Leeds Erosion Risk areas: Pulverizer mill PF tubes Boiler tubes Silanite coal Actual Specific Data: PSD d 90 d d 90 d Density φ p (approx) Base line fly ash 508 µ 21 µ Ex-mill coal 180µm 54µm 2g/cm 3 Fly ash with 6.8% 335 µ 11 µ Silanite TM 47µm 17µm 4 g/cm 3 additive Silaniteit TM particles and Silaniteit TM fly ash too small to have material effect 2016 IIT Ltd 14

15 Silanite additive: Risk assessment (2) Slagging & Fouling With additive: Slagging index Rs moved from to 0.19 Rs < 0.6 low slagging propensity Fouling index Fu moved from 0.43 to 0.87 Fu < 0.6 low fouling propensity K 2 O concentration lower Higher fly ash softening temperature Conclusion: Effect of Silanite TM additive insignificant Corrosion Electro-chemical corrosion happens in presence of liquid phase Silanite TM fly ash has higher fly ash softening temperature, thus reducing corrosion effect Test results indicate Silanite TM reduces corrosion Conclusion: Silanite TM additive has no detrimental effect on boiler installation 2016 IIT Ltd 15

16 Silanite TM additive: Ash fusibility temperatures 2016 IIT Ltd 16

17 Silanite additive: Corrosion test facility 6 silicon carbide electrically heated elements A gas mixture skid supplying simulated combustion gas products (O 2 :3 3-4%, CO 2 : %, 16% HCl: %, SO 2 : %, N 2 : 75-78%, H 2 O: 6-8%) T22 ferritic steel alloy (Cr: 2.25%, Mo: 1%) coupons coated with the coal fly ash and Silanite mixed fly ash Exposure time: 1000 hrs 2016 IIT Ltd 17

18 Silanite TM : Corrosion test results: 40 50% reduction 2016 IIT Ltd 18

19 Silanite TM additive: SEM / EDS images Coating Corrosion (scale) T22 metal 2016 IIT Ltd 19

20 Silanite Additive: finer PSD, higher iron Silanite TM additive creates higher quality fly ash: > 40% reduction of PSD Coal fly ash d 90 d 50 Base line fly ash 508 µ 21 µ Fly ash with 6.8% additive 335 µ 11 µ Enhanced suitability for use in concrete 2016 IIT Ltd Coal + 6.8% Silanite fly ash % % Na 2 O MgO Al 2 O SiO P 2 O SO Cl K 2 O CaO TiO V 2 O Cr 2 O MnO Fe 2 O CoO NiO CuO ZnO ZrO SrO Mo SnO Sb PbO

21 Silanite TM + SNCR: enabling 70-90% AFR reduction 2016 IIT Ltd 21

22 Silanite TM + SNCR: supplementary effect 2016 IIT Ltd 22

23 Silanite TM Fuel Enrichment additive: summary Multiple benefits: 3.4% volume equivalent additive yields: 1.1% increase in boiler efficiency 8-10% NO x reduction + advantageous interaction with SNCR About 20% reduction in dust and particulate emissions Significantly better quality fly ash > 40% corrosion reduction Easy to retrofit without need for outage 2016 IIT Ltd 23