A comparative study on syngas production from crude glycerol by - - PowerPoint PPT Presentation

A comparative study on syngas production from crude glycerol by utilizing DC arc plasma

• Dr. Andrius Tamošiūnas

Plasma Processing Laboratory, Lithuanian Energy Institute 6th International Conference on Sustainable Solid Waste Management, Naxos Island, Greece, 13–16 June 2018

Content

• Glycerol as a source for energy production
• Aim of the work
• Use of plasma and its classification
• Experimental setup & process parameters
• Results & Discussion
• Conclusions

Glycerol (C3H8O3) – a source for energy production

Source: http://www.ebb‐eu.org/stats.php#

Glycerol accounts to 10 wt.% of the total biodiesel production, but in some cases it can amount to 30 wt.%.

Aim of the work

• Experimental investigation of crude glycerol

conversion to syngas using DC arc plasma.

• Process performance quantification in terms of:

– Producer gas composition; – H2 and CO yield; – H2/CO ratio; – Lower heating value (LHV); – Carbon conversion efficiency (CCE); – Energy conversion efficiency (ECE); – Specific energy requirements (SER).

What is Plasma?

Use of plasma because of:

• High temperatures (enthalpy) (103 – 104 K);
• High chemical reactivity and kinetics;
• Neutralization efficiency up to 99.99%;
• Ecological cleanness;
• The amounts of unwanted contaminants are

reduced, (NOx, COx, HC and etc);

• No need of catalyst;
• Fast start‐up – sut‐down of the process;
• Easy adoption for various materials treatment;

Limitations of conventional utilization methods (DR, SR, pyrolysis, PO, AR, SWG, etc.):

• Catalyst sensitivity to contaminants;
• Its deactivation, expensive materials such as Pt used for

catalysts preparation;

• High investment and exploitation costs;
• Requirement of external high‐temperature heat sources

inducing thermal absorption reaction;

• Requirement of high pressures;

Why Plasma?

Classification of plasma Plasma

Low temperature

(Non‐equilibrium plasma) T < 5 x 104 K

High temperature

(Equilibrium plasma) T > 5 x 104… 108 Examples:

Sun, Stars Universe, etc.

Thermal plasma

(quasi‐equilibrium)

Non‐thermal plasma

(Non‐equilibrium) Te ≈ Ti ≈ Tg ≤ 2 x 104 K Te >> Ti ≈ Tg ≈ 300 ~ 103 K

Examples:

Arc discharge RF discharge MW discharge, etc. Examples: Direct barrier discharge Corona discharge, etc.

Experimental setup & process parameters

Parameter/Case Water vapor + glycerol Air + glycerol Arc current, A 160 160 Arc voltage, V 350–390 350 Power, kW 56–62.4 45.6–56 Glycerol flow rate, g/s 5.6 5.6 Gasifying agent flow rate, g/s 2.9–5.15 2.7–4.9 Tplasma, K 2800 4400 Plasma torch thermal efficiency (η) 0.69–0.76 0.6–0.74

Table 1. Experimental conditions for crude glycerol conversion.

• Fig. 1 Experimental setup of

glycerol conversion system:

plasma torch (1), chemical reactor (2), plasma‐forming gas feeding line (3), electrical circuit (4), glycerol feeding line (5), and product gas analysis (6).

Results & Discussion

Producer gas composition, H2/CO ratio and LHV

• Effect of gasifying agent‐to‐glycerol ratio was the only one

parameter for both cases enabling to compare the obtained experimental results between.

Fig 2. Elemental composition of the producer gas and the H2/CO ratio.

H2/CO ratio: Water vapour case – 2.07 Air case – 1.07 LHVsyngas (MJ/Nm3): Water vapour case – 9.82 Air case – 7.32

Carbon conversion & Energy conversion efficiencies

Fig 4. Effect of gasifying agent‐to‐glycerol ratio on the carbon conversion. Fig 5. Effect of gasifying agent‐to‐glycerol ratio on the energy conversion efficiency.

Carbon conversion efficiency (CCE%): Water vapour plasma – 100 Air plasma – 75.7 Energy conversion efficiency (ECE%): Water vapour plasma – 70.8 Air plasma – 48.46

%, 100      

fuel fuel plasma syngas syngas

LHV m P LHV m ECE 

     

%, 100 4 . 22 2 12 %

6 2 4 2 2 2 4 2

                 C H C H C H C CH CO CO Y CCE

gas dry

Specific energy requirements (SER)

Fig 6. Effect of gasifying agent‐to‐glycerol ratio on the specific energy requirements.

SER (kJ/mol): Water vapour plasma – 191.6 (or 1.78 kWh/kg) Air plasma – 266.45 (or 2.5 kWh/kg)

,

syngas

m P SER 

Comparison between results

Parameter/Reference This study (water vapor + glycerol) This study (air + glycerol) Yoon et al. [1] Zhang et al. [2] Discharge type DC arc DC arc MW Rotating DC arc Power, kW 62.4 56 2 24.1 Thermal efficiency (η), (%) 76.1 74.1 n.d. 40 Gasifying agent Water vapor (83%)/Air (17%) Air Air/steam Ar/water in glycerol H2, (vol.%) 51.16 29.00 57 56 CO, (vol.%) 24.74 27.00 35 38 H2/CO ratio 2.07 1.07 1.63 1.47 LHVsyngas, MJ/Nm3 9.82 7.32 12 11 CCE, (%) 100 75.7 ~100 100 ECE, (%) 70.8 48.46 62* 66 SER, (kJ/mol) 191.6 266.45 n.d. n.d.

*This value was named as the cold gas efficiency. The power of the plasma was not added to the formula presented. If the power were added, the ECE would be lower.

Table 1. Summary of the crude glycerol conversion to syngas with various plasma methods.

1. Yoon, S.J., Yun, Y.M., Seo, M.W., Kim, Y.K., Ra, H.W., Lee, J.G.: Hydrogen and syngas production from glycerol through microwave plasma gasification. Int. J. Hydrogen Energ. (2013). https://doi.org/10.1016/j.ijhydene.2013.09.001 2. Zhang, M., Xue, W., Su, B., Bao, Z., Wen, G., Xing, H., Ren, Q.: Conversion of glycerol into syngas by rotating DC arc plasma. Energy (2017). https://doi.org/10.1016/j.energy.2017.01.128

Conclusions

• Crude glycerol conversion to syngas was investigated

using thermal DC arc plasma at atmospheric pressure;

• Two separate gasifying mediums were used: water vapor

and air;

• Crude glycerol gasification in water vapor plasma gave a

better process performance and syngas quality over the air plasma gasification in terms of the H2/CO ratio, H2 and CO yield, CCE, ECE, and SER.

• Dr. Andrius Tamošiūnas

E‐mail: Andrius.Tamosiunas@lei.lt