Detection of through-wall leakage - Coke Oven Managers Association

ECOCARBReduction of Emissions and Energy Utilisation of Coke OvenHeating Systems through Advanced Diagnostics and ControlMansour SaiepourTata Steel Group Environment,Swinden Technology Centre, UKE-mail: mansour.saiepour@tatasteel.comCOMA Conference, Scunthorpe, 4-5 th April 2013

ECOCARB project• Partly funded by the EC, Research fund for Coal and Steel (RFCS)• 1 July 2008 – 31 December 2011• Total budget: € 2.5MConsortium:• Tata Steel – UK• AMMR/CPM – Forbach, France• BFI – Dusseldorf, Germany• Uhde – Dortmund, Germany• Newcastle University – UKECOCARBUhdePartner companies with required expertise were selected.COMA Conf, Scunthorpe, ECOCARB 4-5 April 2013 2

Challenges with coke oven heating• Environment – NOx, SO 2 , CO and particulate;• Energy efficiency – Fuel cost, CO 2 emissions;• Coke quality – heating quality (also affectspushing emissions;• Battery life – maintenance (new plant > £ 300M)• Oven walls can develop Through Wall Leakagewhich may considerably affect the above.A Potential Solution• Prompt repair and maintenance - needs earlydetection of faults;• Hence, need for suitable condition monitoringsystem.Underfiring emissionsPushing emissionsCOMA Conf, Scunthorpe, ECOCARB 4-5 April 2013 3

Small cracksEmpty OvenThrough-wall leakage• Wall crack between chamber and flue – caused byexp/cont & pushing the coke especially when sticking;• Raw gas leaks from chamber to flues during coalcharging and coking;• Interferes with combustion, lowers excess O 2 , leads toincomplete combustion, hence higher CO and soot(carbon particles);• A larger amount of combustibles such as methane(CH 4 ) from both leaked raw gas and fuel gas remain unburnt;• Hence, measurement of CO, O 2 , CH 4 and particulatematter may be used as indicators for through-wallleakage;• Assess coke oven through-wall leakage by undertakingwaste gas analysis at individual walls.COMA Conf, Scunthorpe, ECOCARB 4-5 April 2013 4

Project AimDetection of heating wall faults at early stage of occurrence to:• Prevent major repair costs;• Reduce environmental emissions;• Increase energy efficiency;• Improve heating hence coke quality and pushing emissions;• Extend battery life.COMA Conf, Scunthorpe, ECOCARB 4-5 April 2013 5

Work PackagesTata SteelAMMR-CPMBFIUNEWUhdeWork PackageWaste gas analysisof heating wallsInspection ofregenerators andfluesExperimental heatingflue and CFDmodellingSystem for automaticdetection of faultsIndividual heatingwall controlAimEssential data and process knowledge fordetection of faultsCondition monitoring for improvement ofheating efficiencyData and information for detection offaultsDetection of heating faults at early stageMake improvements by injectingsecondary air and controlling heat input toindividual wallsCOMA Conf, Scunthorpe, ECOCARB 4-5 April 2013 6

Detection of through-wall leakage (Tata Steel)• Coke oven heating system - Tata Steel Scunthorpe;• Woodall-Duckham-Koppers twin flue underjet oven design;• 3 Batteries, 25 ovens each, 5.4 m high ovens, coking time 18h,690 kt/a;• Fuel: coke oven gas,• 20 minute reversals;• Each heating wall has 30 flues;• 15 combustion (burning) flues;• 15 exhaust (non-burning) flues.COMA Conf, Scunthorpe, ECOCARB 4-5 April 2013 7

Detection of through-wall leakage (Tata Steel)• Measurement of exhaust gases from heating walls at waste gas boxes;• Health and safety: potential exposure to carbon monoxide gas, electricalsupply, and high temperatures of waste gas boxes, floor and ambient;• Waste gas temperature (> 300°C), moisture (> 20% hence potentialcondensation and loss of soluble gases such as NO 2 and SO 2 )• Dust loading: Equipment must be protected against high dust emissions.Before measurementAfter measurementFilter element in theparticle heated filterCOMA Conf, Scunthorpe, ECOCARB 4-5 April 2013 8

Detection of through-wall leakage (Tata Steel)• Results of measurements at waste gasboxes before, during & after charging;• Low leakage (top) and high leakage(bottom);• Main indicators for through-wall leakageare O 2 , CO, CH 4 ;• Examples (during charging of ovens)• Low leakage,─ CO: ~ 3,000 ppm─ CH 4 : ~ 340 ppm─ O 2 : ~ 1%• High leakage,─ CO: ~ 18,000 ppm─ CH 4 : ~ 1,200 ppm─ O 2 : 0%COMA Conf, Scunthorpe, ECOCARB 4-5 April 2013 9

Detection of through-wall leakage (Tata Steel)• Coke oven wall emissions tester (COWET) -developed by Tata Steel UK;• Simultaneously measures both walls;• Waste gas O 2 , CO, CO 2 , NO x , CH 4 and dust;• Quickly identifies which of 2 walls is faulty;• Self-contained - equipment protected in atemperature regulated closable housing;• Easily, quickly and safely moved from oneoven to another;• EU Patent application no. 10015884COMA Conf, Scunthorpe, ECOCARB 4-5 April 2013 10

Causes of inefficient heating operation (AMMR - CPM)• New robot forinspection ofregenerator soleflues;• 2 cameras (Lateralview & axial view);• Operatingtemperature ~ 300°C;• Width: 80 – 240 mm;2 cameras• Successfully testedin real operatingconditions.Axial view by robot cameraCOMA Conf, Scunthorpe, ECOCARB 4-5 April 2013 11

Heating flue height (m)Heating flue height (m)Causes of inefficient heating operation (AMMR - CPM)• Results of combustionefficiency tests;• Complete assessment ofheating flue and regenerator;• Air/gas ports─ Videofil to inspect ports• Temp distribution─ Pyrofil (refractories)─ Suction pyrometer (gas)• Flame length─ CO content inside87654321airGood combustiongasRefractory fluewall temperatureGas temperature0700 800 900 1000 1100 1200 1300 1400 1500Temperature (°C)87654321airgasBad combustionRefractory fluewall temperatureGas temperature0700 800 900 1000 1100 1200 1300 1400 1500Temperature (°C)Flame: 4.5m, low CO Flame: 3m, CO > 1%O 2 ~ 6%O 2 ~ zero• Excess air─ O 2 content at top• Regenerator─ Inspection robotCOMA Conf, Scunthorpe, ECOCARB 4-5 April 2013 12

Fuel gasAirLaboratory combustion tests (BFI)• Experimental heating flue designed andconstructed;• To investigate influence of differentconditions on emission formation andtemperature profile inside coke ovenheating flues;• Scale down (1:2) of a heating flue at TataSteel UK;Flue gasAnalyzerAnalyzerRaw gasAnalyzer• Can investigate effect of:• through-wall leakage (naphthalenesaturator);• nozzle blockage (different size nozzles);• Measure CO, NO x , CO 2 , O 2 , dust, fluetemperatue;• CFD modelling also undertaken.Automatic firingdeviceCoke oven gasBF gasNatural gasRaw gasAnalyzerAnalyzerFlue gasrecirculationCOMA Conf, Scunthorpe, ECOCARB 4-5 April 2013 13

Laboratory combustion tests (BFI)• Effects of standard coke ovenconditions (no faults), determined;• At standard conditions flue gas emissionswere low (e.g. CO, dust);• Provided baseline for results of faultyconditions tests;• Increasing flue gas recirculationdecreased temp, hence decreased NOx;• Increasing recirculation by 20% reducedNOx by factor of ~2 for experiment andCFD.NOx flue gas in mg/m 3 . Reference O 2content 5%2000150010005000% flue gas recirculation20% flue gas recirculation40% flue gas recirculation60% flue gas recirculation00 1 2 3 4 5 6 7 8O 2content flue gas in %COMA Conf, Scunthorpe, ECOCARB 4-5 April 2013 14

Laboratory combustion tests (BFI)• Influence of through-wallleakage (TWL) on emissionformation investigated;• Amount of TWL is related to DPacross coke chamber & heatingflue, and crack geometry;• TWL increased the dust contentin flue gas:TWL (% of fuel rate) 1% 10%Measured dustcontent5 mg/m 3 55 mg/m 3and lowered the O 2 content.No TWLTWL: 10%TWL: 75%O 2 = 6.6%O 2 = 5.5%O 2 = 0.4%COMA Conf, Scunthorpe, ECOCARB 4-5 April 2013 15

Online automatic fault detection (UNEW)• Diagnostics model based on dataand process knowledge provided byTata Steel;• Matlab-based GUI for modelgeneration, validation, and updating;• New univariate and multivariate datavisualisation tool to identify andremove process outliers;Multivariate outlier identify / remove• Performance of the developed PCAmodel was assessed by examiningthe scores, SPE and T 2 monitoringplots;Process monitoring with PCA modelCOMA Conf, Scunthorpe, ECOCARB 4-5 April 2013 16

Online automatic fault detection (UNEW)• Overall system based on Gensym G2KBS;• Designed by Tata Steel and UNEW;• Automatically and quickly detectsheating faults;• Determines the type of fault (TWL, fuelrelatedor nozzle blockage);• Locates the oven with the fault;• Indicates the severity of the fault;• Potential for early remedial actions(e.g. fuel flow rate or repairs);Prototype G2-based monitoring of cokeoven heating faultsCOMA Conf, Scunthorpe, ECOCARB 4-5 April 2013 17

Online automatic fault detection (UNEW)• System installed on-line and evaluated;• Detected and identified coke oventhrough-wall leakage and other coke ovenheating faults;• Provides potential for:• reducing emissions;• increasing energy efficiency;• improving coke quality;• extending battery life;• Used to provide information for controllingindividual walls;• Good feedback from plant engineers.COMA Conf, Scunthorpe, ECOCARB 4-5 April 2013 18

Individual heating wall control (Uhde)• There are two elements to thedesign:• injection of secondary air into thenon-burning flue during alternatereversals to burn the additional unburntgas components (tar, benzoleand other material) in the raw gasthat has leaked from the cokingchamber into the flue and hencereduce emissions, decarbonise thenozzles and increase efficiency.• control of the fuel flow rate intoindividual wall headers to control thethermal input;COMA Conf, Scunthorpe, ECOCARB 4-5 April 2013 19

Individual heating wall control (Uhde)• Sealing of Becker recirculation portto avoid buildup of explosive gasmixture;• Spring steel elements in combinationwith viton gasket;• Nozzle carrier with seal and newnozzle at the tip;• Avoid manipulation of riser pipes;• Application of 3-way valves in thegas line;• Several preparatory tests wereneeded before final installation;• Two heating walls were completelyequipped with this modification.COMA Conf, Scunthorpe, ECOCARB 4-5 April 2013 20

Individual heating wall control (Uhde)• Good results from extensive trial tests;• No worsening of NOx emissions and cross-wall temp profiles;• Injection of secondary air into the ‘off-gas’ leg reduced waste gas CO(related to dust/soot emissions);COMA Conf, Scunthorpe, ECOCARB 4-5 April 2013 21

Main Achievements• Waste gas measurements at boxes─ Measurement expertise gained;─ Knowledge of emission values for assessment;─ Developed COWET (patent application filed);• Robot for inspection of regenerator sole flues;• Experimental heating flue and results;• Automatic on-line system for fault detection and location;• Individual heating wall control.COMA Conf, Scunthorpe, ECOCARB 4-5 April 2013 22

THANK YOUAcknowledgementThe research leading to these results has received funding from the European Union ResearchProgramme of the Research Fund for Coal and Steel (Contract number: RFCR-CT-2008-00007)