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Ventilation A ir M ethane – C onverting a G reen house G as into E nergy. Prof. Krzysztof Warmuzinski Dr hab. Krzysztof Gosiewski, Dr Marek Tanczyk Dr Manfred Jaschik, Aleksandra Janusz-Cygan. Polish Academy of Sciences, Institute of Chemical Engineering Gliwice, Poland.
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Ventilation Air Methane – Converting a GreenhouseGas into Energy Prof. Krzysztof Warmuzinski Dr hab. Krzysztof Gosiewski, Dr Marek Tanczyk Dr Manfred Jaschik, Aleksandra Janusz-Cygan Polish Academy of Sciences, Institute of Chemical Engineering Gliwice, Poland 5th ISCECC, 11-12 October 2012, Athens, Greece
Methane Increase in concentration (250 years): CO2 – 37%, CH4 – 149% GWP (100 years) – 21 5 Gt of CH4 in the atmosphere (105 Gt CO2 eq.) Annual emissions: 24 Gt of CO2, 0.45 Gt of CH4 = 9.45 Gt/y of CO2 (= 40% CO2 emissions)
Methane sources • Livestock, rice growing • landfill and sewage • Fossil fuel production (gas, oil, coal) • Leakage from the gas distribution systems (~100 Mt/y; 1/3 in Russia) • Thermokarst • Yedoma • Methane clathrates 100 Mt CH4 = 2.1 Gt CO2 eq. (EU produces around 2 Gt/y of CO2)
PSA 60 000 m3N/h 40 000 m3N/h TSA membrane separation 1 764 m3N/h
CFRR So far, most of the studies have focused on catalytic combustion in CFRRs (catalytic flow-reversal reactors) Advantages • Relatively low operating temperatures (below 800 oC ) • Safety margin measured by the distance fromthetemperature of NOx formation is also wider thanfor TFRR • Cheaper materials of construction
CFRR Drawbacks • Operating temperature (up to 800 oC)is, however, too high for lessexpensive catalysts • Cost of the expensive catalyst can make the totalcost of the plant very high • Catalyst will operate with wet and dusty gas, and thus its lifetime will probably be very short • Lower temperatures at the inlet to heat recovery units make the recovery less efficient • Despite abundant literature and studies, the CFRRhas so far been realized onlyon a small scale
TFRR Non-catalytic oxidation in TFRRs (thermal flow-reversal reactors) is often frequently regarded as an attractive alternative Advantages • No investment and operating costs associated witha catalyst • TFRRs are widely used in industry for VOCscombustion • The concept has already been proven in ventilation air installations (processing up to136 000 m3(STP)/h) • Expected better behaviour with wet and dusty gas • Higher temperatures at the inlet to heat recovery unitsmake the recovery more efficient
TFRR Drawbacks • High operating temperatures (up toabout 1 200oC) • More expensive materials of construction • Safety margin for the temperature of NOxformation is smaller than for CFRR. Thus, theoutlet concentrations of NOxcan be higher than those forcatalytic reactors
CFRR INERT INERT CATALYST CATALYST Hot gas withdrawal to heat exchanger HEAT EXCHANGER CATALYST CATALYST INERT INERT System of central cooling System with hot gas withdrawal Principal heat recovery schemes
TFRR INERT INERT Hot gas withdrawal to heat exchanger HEAT EXCHANGER INERT INERT System of central cooling System with hot gas withdrawal Principal heat recovery schemes
LABORATORY EXPERIMENTS IN TUBULAR REACTORS (FREE-SPACE COMBUSTION, MONOLITH A, MONOLITH B) TENTATIVE SELECTION OF REACTION SCHEMES (SINGLE STAGE, CONSECUTIVE, PARALLEL, CONSECUTIVE-PARALLEL) ESTIMATION OF KINETIC PARAMETERS • FINAL SELECTION OF A REACTION SCHEME AND KINETIC EQUATION BASED ON • FORMATION OF CO • MAGNITUDE OF THE KINETIC PARAMETERS VALIDATION OF THE MODEL IN A PILOT TFRR (FEED FLOWRATE UP TO 1,000 m3/h)
KINETIC EXPERIMENTS (free space) • Conditions of the process • Constant gas flowrate of 0.12 m3/h • Temperatures from 500°C to 890°C • Initial methane concentrations: 0.5 to 1.4 vol.% • Quantities measured • Temperature in the cell • Concentrations: CH4 (inlet, outlet) • CO (outlet) • CO2(outlet) • Gas flowrate
KINETIC EXPERIMENTS (Monolith A) • Conditions of the process • Constant gas flowrate of 0.5 m3/h • Temperatures from 470°C to 660°C • Initial methane concentrations: 0.2 to 1.7 vol.% • Quantities measured • Temperature along the monolith • Concentrations: CH4 (inlet, outlet) • CO (outlet) • Gas flowrate
KINETIC EXPERIMENTS (Monolith B) • Conditions of the process • Constant gas flowrate of 0.8 m3/h • Temperatures from 660°C to 820°C • Initial methane concentrations: 0.38 to 1.2 vol.% • Quantities measured • Temperature along the monolith • Concentrations: CH4 (inlet, outlet) • CO (outlet) • CO2 (outlet) • Gas flowrate
PRELIMINARY RESULTS FOR THE PILOT TFRR AT CYCLIC STEADY STATE
EXPERIMENTAL AND PREDICTED TEMPERATURE PROFILES IN THE PILOT TFRR Experiment vs. model (consecutive scheme)
CONCLUSIONS • Ventilation-air methane can be efficiently oxidized in a non-catalytic reverse-flow reactor • A portion of the heat generated in the reactor can be extracted without affecting the sustained cyclic operation • The consecutive reaction scheme, with the kinetic parameters estimated based on laboratory experiments, can be used to simulate the behaviour of the pilot reactor (both qualitatively and quantitatively)
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