Production of synthesis gas from methane by high temperature

Transcription

1 Production of synthesis gas from methane by high temperature Popov Viktor E., Surov A.V., Subbotin D.I., Popov S.D., Serba E.O., Obraztsov N.V. Institute for Electrophysics and Electric Power of the Russian Academy of Sciences Saint-Petersburg State Institute of Technology Saint-Petersburg, Russia 9 th International Freiberg Conference on IGCC & XtL Technologies

2 Methods for hydrogen production 2

3 Investigated plasma processes The type of plasma Flow rate Power Conversion of CH 4 Energy consumption* CH 4 /CO 2 g/s W % MJ/kg Corona discharge 1, ,3 62,4 291,19 DC Corona 1, , ,1 282,45 Corona + catalytic ,4 56,3 100,71 DBD 3, ,3 656,10 DBD + catalytic , ,60 Microwave discharge 5, , ,8 59,59 Glow discharge 3, ,02 Cold plasma stream 0,24 0, ,68 428,39 Plasma stream + catalytic 0,24 0, ,06 325,82 Gliding arc 0, ,16 Nitrogen arc discharge 0,87 0, ,82 75,15 Nitrogen arc + catalytic 0,96 0, ,32 65,87 Diode discharge 0,96 0, ,71 65,81 *- specific energy consumption of converted CH 4 3

4 THREE-PHASE HIGH VOLTAGE AC PLASMA TORCH WITH ROD ELECTRODES Plasma forming gases air, H 2 O Voltage AC 3x10 kv Current up to 50 A Power up to 105 kw Efficiency ~95% Electrodes life time up to 200 hours 4

5 The plasma torch scheme 1 electrode 2 arc channel 3 electric arc 4 gas supply 5 gas supply 4 5 Air Air Air Steam CO 2 CO 2 CO 2 Steam 5

6 Kinetic model. Initial data CH H 2 O CO 2 = 2.1 H 2 + CO Q = 168,8 kj Stream 2 Stream 1 6

7 Plasma composition, mole fractions Plasma enthalpy, MJ/kg Kinetic model. Initial data. Stream 1 Thermodynamically equilibrium mixture of 0.55 H 2 O CO 2 7

8 Kinetic model. Initial data Reactor type perfect-mixing reactor Volumetric energy consumption per 1 m 3 of reactor E v = W (H н +E in ) = const = 1 MW where W = 1/ hourly space velocity, h -1 ; hold-up time, s; raw material density at standard conditions, kg/m 3 ; E in energy, introducing with plasma, MJ/kg Kinetic mechanism contains 28 substances and 246 elementary acts

9 Calculations results Reagents conversion and product selectivity The plasma reactor specific volumetric productivity

10 1 st experiment. Cooled chamber 1- plasma torch 2- cooled chamber 3- methane feed Reaction volume l Power kw Flow rates: CO 2 3 g/s H 2 O 3 g/s CH 4 to the electrode 0.5 g/s 10

11 Results The temperature in the reaction chamber decreases if the methane flow rates increases. This is the reason of a maximum of the steam conversion. Carbon dioxide reforming is more likely when the temperature decreases. 11

12 Pilot facility Reaction volume - 70 l The power of the plasma torch is kw 12

13 CO 2 -H 2 O and CO 2 methane reforming 13

14 CO 2 -H 2 O and CO 2 methane reforming CO 2 -H 2 O reforming CO 2 - reforming Parameter Data Experimental Estimated Experimental Estimated CH Syngas H composition, CO % vol CO Specific energy CH consumption, MJ per kg of H Conversion level, % Selectivity on H 2, %

15 Change of plasma torch power at constant expenses of reacting substances Plasma forming components flowrates CH g/s, H 2 O 2.9 g/s, CO g/s CH g/s, CO 2 6 g/s 15

16 Air methane reforming 16

17 Air reforming of methane Parameter Experimental data Estimated data CH Syngas composition, % vol. H CO CO N Ar Specific energy consumption, MJ per kg of CH H

18 Three-phase high voltage AC plasma torch with hollow electrodes Plasma forming gas air up to 100 g/s Voltage AC 3x10 kv Current up to 100 A Power up to 500 kw Efficiency ~ 92% Electrodes life time up to 2000 hours Shutter speed 1/4000 s 18

19 Conclusions In the long-term regime, a high conversion of methane to synthesis gas ( %) was achieved for the first time in almost stoichiometric regimes with low energy inputs (37-42 MJ/kg of methane), which considerably exceeds the parameters for known plasma processes. 19

20 Conclusions Produced syngas contains more than 95% of mixture of CO and H 2 with a molar ratio of H 2 : CO from 1 to

21 Conclusions With a significant change in the composition of the plasma-forming mixture from CH g/s, H 2 O 2.9 g/s, CO g/s to CH g/s, CO 2 6 g/s stable operation of the plasma torch is unchanged. 21

22 Conclusions The main advantage of this plasma process is the ability to control the composition of the products and obtain a syngas that does not contain a large number of impurities. 22

23 Conclusions The comparative simplicity of this plasma method makes it possible to predict its largescale implementation for obtaining a wide range of liquid organic substances. 23

24 Thank you for your attention! 24