1. Ventilation Air Methane – Converting a Greenhouse Gas 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, October 2012, Athens, Greece

2. 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)

3. 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)

4. ANTHROPOGENIC SOURCES OF METHANE EMISSIONS

5. SOURCES OF COAL–RELATED METHANE EMISSIONS

6. VENTILATION AIR METHANE

8. membrane
separation
PSA
TSA
m3N/h
m3N/h
1 764 m3N/h

9. 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 from the temperature of NOx formation is also wider than for TFRR
Cheaper materials of construction

10. CFRR
Drawbacks
Operating temperature (up to 800 oC) is, however, too high for less expensive catalysts
Cost of the expensive catalyst can make the total cost 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 CFRR has so far been realized only on a small scale

11. TFRR Advantages TFRRs are widely used in industry for VOCs combustion
Non-catalytic oxidation in TFRRs (thermal flow-reversal reactors) is often frequently regarded as an attractive alternative
Advantages
No investment and operating costs associated with a catalyst
TFRRs are widely used in industry for VOCs combustion
The concept has already been proven in ventilation air installations (processing up to m3(STP)/h)
Expected better behaviour with wet and dusty gas
Higher temperatures at the inlet to heat recovery units make the recovery more efficient

12. TFRR
Drawbacks
High operating temperatures (up to about 1 200oC)
More expensive materials of construction
Safety margin for the temperature of NOx formation is smaller than for CFRR. Thus, the outlet concentrations of NOx can be higher than those for catalytic reactors

13. System of central cooling System with hot gas withdrawal
CFRR
Principal heat recovery schemes
INERT
CATALYST
HEAT EXCHANGER
System of central cooling
INERT
CATALYST
Hot gas
withdrawal to
heat exchanger
System with hot gas withdrawal

14. System of central cooling System with hot gas withdrawal
TFRR
Principal heat recovery schemes
INERT
HEAT EXCHANGER
System of central cooling
System with hot gas withdrawal
Hot gas
withdrawal to
heat exchanger

15. ESTIMATION OF KINETIC PARAMETERS
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)

16. 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

17. 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

18. 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

21. PRELIMINARY RESULTS FOR THE PILOT TFRR AT CYCLIC STEADY STATE
Feed flow rate
Half-cycle time
Methane concentration
Conversion
Proportion of gas withdrawn
m3/h s
Inlet, vol. %
Outlet, vol.% %
412
240
1.03
0.04
96.1
17.1
398
180
0.77
0.03
9.8
400 90
0.53
0.02
96.2
3.6
402 50
0.43
90.7
2.3
435 60
0.31
93.5 20
0.35
0.05
85.7
406
0.22
86.4

22. EXPERIMENTAL AND PREDICTED TEMPERATURE PROFILES IN THE PILOT TFRR
Experiment vs. model (consecutive scheme)

23. 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) 23

24. THANK YOU
FOR YOUR
ATTENTION