Slide 1

Development of mixed amine solvents

Prof. Mengxiang FangZhejiang University

Email:mxfang@zju.edu.cn

Slide 2

What is Chemical Absorption ?

Absorption with chemical reaction has long been considered one of the most feasible routes to post combustion CO2 capture.

--- Technology roadmap carbon capture and storage, IEA,2010

Slide 3

Chemical absorption technology

Advantages

Disadvantages

Extensive use in the chemical lines

Mature technology and process

Lower demand for flue gas purity

High regeneration energy consumption

High water consumption

Some operating problems including degradation, corrosion, foaming, flooding, channeling and entrainment

Main puzzle?

Advanced solvents

New process

Larger unit size and space occupation

Challenge of Chemical Absorption

Slide 4

Demonstration Plant in China

Huaneng Beijing3,000t/y CO2 Capture demonstration project

Huaneng Shanghai120,000t/y CO2 Capture demonstration projectChina power Investment

Hechui 10,000t/y CO2 Capture demonstration project

Amine based solvents，Packing Column，Heat regeneration process

Energy consumption 3.6-4Mj/kg，Energy penalty 8-11% Investment increase 50-90% Electricity price increase 70-90%

Slide 55

How to decrease cost and energy consumption?

CO2>99%

Absorptionprocess

Regenerationprocess

Flue gas

Gas absorbent

Advanced solventsKs series mixed amineAmmonia basedIon-liquidPhase change

New RegenerationProcessMulti-stage Vacuum regeneration

New ReactorPacking materialRotating bedMembrane Co

Heat IntegrationInnersystem

---Technology roadmap carbon capture and storage, IEA,2010 More cost and energy effective solutions by chemical absorption, which

is environmental friendly and less water consumption, is still needed!

Slide 6

Principe of Mixed amine

• Principle In combination with high reactivity with CO2 and low regeneration energy consumption.

Research of mixed amine

Primary amine/ tertiary amine

Tertiary amine/ active ingredient

Secondary amine/ hindered amine

Based on high CO2reactivity, reduce the energy consumption

Based on the low energy consumption , increase the CO2reactivity

Use the sterically hindered amines

Mixed amine Ⅰ

Mixed amine Ⅱ

Mixed amine Ⅲ

Slide 7

Absorbent Concentration Research objective

MEA 30%，20%，10% Set a study basis and tested the concentration effect on absorption performance

MDEA 30% Set a study basis

MEA+MDEA Total concentration 30%（activator concentration 5%

，10%，15%）

Adding tertiary amine into primary amine, to decrease regeneration energy consumption while keeping

high absorption rateMEA+AMP Total concentration 30%

（activator concentration 5%，10%）

Adding sterically hindered amine into primary amine, to decrease regeneration energy consumption

while keeping high absorption rateMEA+TETA,A

EEA,DETA,PZTotal concentration 30%

（activator concentration 5%，10%）

Adding polyamine and cyclic amine into primary amine, to keep the regeneration energy consumption constant or less increase while further improving the absorption

performanceMDEA+TETA,

AEEA,DETA,PZTotal concentration 30%

（activator concentration 5%，10%，15%）

Adding polyamine and cyclic amine into primary amine, to keep the regeneration energy consumption constant or less increase while further improving the

absorption performanceMEA (Sigma-Aldrich, purity≥99.9mass%);MDEA (Sigma-Aldrich, purity≥99.9mass%);AMP (Fluka, purity> 97mass %);PZ (anhydrous 99%); AEEA (Adama-beta, purity 99mass%);TETA (Adamas-beta, purity 99mass%) ;DETA(Shanghai Lingfeng Chemical, purity 99mass%)

Test amine

Slide 8

Experimental study

1.Experiments schematic

Figure 1 Experimental apparatus for absorption study1、MFC 2、Mixing tank 3、Valve 4、Thermostatic

water bath 5、Acid wash 6、Desiccators 7、Gas analyzer 8、Computer 9、Vent

Figure 2 Experimental apparatus for regeneration study1.Oil bath 2.Glass reactor 3.Stirring Cell 4.Condenser

5.Flow meter 6.Gas flow meter by drainage 7.Sampling port 8.Condensation water inlet 9.Condensation water outlet

10.Plug-in heat resistance 11.Thermocouple

Slide 9

2. Experimental conditions

ParametersSerial number of the reactor

1 2 3 4Shape column column column column

Average inner diameter/mm 48.5 41 36.5 27

Volume of absorbent/mL 120 120 120 120

Liquid surface height / Average inner diameter

1.5 2.5 3.5 8.0

Table 2 Design parameters of the semi-batch reactor

Figure 2 Design forms of the gas inlet for the reactor

Absorption•Absorption temperature：40℃；•Absorption pressure: 1 atm;•Initial solution volume: 120mL•Gas flow：N2, 0.8 L/min；CO2, 109 ml/min，CO2 concentration of the simulated gas，12%。

Regeneration•Volume of glass reactor :800ml • Volume of rich-CO2 solution:500ml;•Temperature rising period:5 min;•Regeneration temperature: 100℃;•Regeneration pressure: 1 atm;

Slide 10

=2 2

2

, ,

,

CO in CO out

CO in

v vv−

2 ,CO Aη 2 2

2 2

, ,

, ,(1 )CO in CO out

CO in CO out

C CC C

−

−

v

3. Analysis method

CO2 removal efficiency

V is the gas flow rate，mL/min；C is the gas concentration in the simulated gas

=

Solution CO2 loading

——The volume of tested sample ，L；

——The initial volume of the gauges tube before titration

—— The ending volume of the gauges tube after titration，——The mole concentration of ammonia，mol/L;

——The gas volume correction factor when the experimental operating conditions are converted into standard operating conditions. It is a dimensionless coefficient and its calculation formula is as follows：

Slide 11

CO2 regeneration extent

2 ,CO Rη = int 100%eve

eve

A AA−

∗

Aint is the instantaneous CO2 loading in the solvents during regeneration ，molCO2/mol absorbent；Aenv is eventual CO2 loading in the solvents during regeneration ，molCO2/mol absorbent

CO2 regeneration rate

Veve——Released CO2 volume of the initial solution，L；

t——The regeneration time，min;

intv veveBt−

=

Vint——Released CO2 volume of the inatantaneous solution，L；

Slide 12

Experimental results

• MEA-based |Absorption performance

Addition EffectPZ +DETA +AEEA +TETA +AMP -MDEA -Initial Max RECaused by PZAver RECaused by DETA

Slide 13

• MEA-based |Absorption performance

Addition EffectDETA +TETA +AEEA +PZ +AMP -MDEA -Weight concenHas a stronger effectEven Max CO2 LoadingCaused by DETAAver CLCaused by TETA

Slide 14

• MDEA-based |Absorption performance

Addition Effect

DETA +TETA +AEEA +PZ +

Initial Max RECaused by DETAAver RECaused by DETA

Slide 15

• MDEA-based |Absorption performance

Addition Effect

TETA +DETA +AEEA +PZ +

Initial Max RECaused by TETAAver RECaused by TETA

Slide 16

• MEA-based |Regeneration performance

Addition EffectMDEA +AMP +PZ -DETA -AEEA -TETA -

Initial Max RECaused by 15%MDEAAver RECaused by 15% MDEA

Slight difference

Slide 17

• MEA-based |Regeneration performance

Addition EffectComparable to 30%MEA

Initial Max RRCaused by 5%AMPAver RRCaused by 15% MDEA

Slight difference

Slide 18

• MDEA-based |Regeneration performance

Addition Effect

PZ -AEEA -TETA -DETA -

5% seems to be acceptable

Slide 19

• MDEA-based |Regeneration performance

Addition Effect

All positive

Initial Max RRCaused by 15%AEEAAver RRCaused by 15% DETA

Slide 20

Analysis and evaluation

• AbsorptionAbsorption capacity--- How much CO2 can be absorbed?

During industry operation, absorbent mass has the direct relation with the operation cost of the pumps. Due to the molecular weight difference, the absorption capacity is more suitable to be given in form of mass rather than mole. The absorption capacity almost equals to the ultimate CO2 loading.

Absorption rate--- How fast CO2 can be absorbed? Mean absorption rate during CO2 loading linearly increasing

phase(R2>0.95) Average absorption rate during whole absorption process

Other factors also should be considered, such as degradation rate, precipitation, foaming and so on.

Slide 21

Absorbents of good absorption performance

Absorbent Initial absorption rate A1(by RE) Score 1

Effective absorption

capacity A2(kg/kg)

Score 2 Total score A（High to low）

30%MEA 88.596 1.00 0.3638 1.00 1.00

20%MEA+10%DETA 91.18 1.04 0.55617 1.53 1.58

25%MEA+5%PZ 94.157 1.06 0.48722 1.34 1.42

20%MEA+10%AEEA 89.21 1.01 0.49674 1.37 1.38

20%MEA+10%PZ 97.85 1.10 0.42794 1.18 1.298

25%MEA+5%DETA 89.016 1.00 0.46185 1.27 1.27

20%MEA+10%TETA 88.307 1.00 0.45143 1.24 1.24

25%MEA+5%AEEA 88.435 1.00 0.40828 1.12 1.12

15%MDEA+15%DETA 84.191 0.95 0.36256 1 0.95

15%MDEA+15%TETA 79.032 0.89 0.33756 0.93 0.84

20%MDEA+10%DETA 74.251 0.84 0.29083 0.8 0.672

20%MDEA+10%PZ 81.767 0.92 0.23411 0.64 0.59

Slide 22

Regeneration Evaluation

• Mean regeneration rate (D1) D1 refers to the average regeneration rate before the regeneration extent of CO2-rich solution reaches 50%.

• Regeneration extent (D2 ) D2 is defined as the CO2 regeneration extent at the 50min in the solvents

Slide 23

Absorbent

Mean regeneration

rate scoreD1 by CL

Regeneration extent score

D2

Total scoreD=D1*D2

High to low

25%MDEA+5%TETA 1.99 1.44 2.87

15%MDEA+15%AEEA 2.11 1.24 2.61

20%MDEA+10%PZ 1.73 1.51 2.61

20%MDEA+10%TETA 1.75 1.42 2.49

25%MDEA+5%DETA 1.67 1.43 2.39

15%MDEA+15%PZ 1.69 1.31 2.21

15%MDEA+15%DETA 1.95 1.04 2.03

15%MDEA+15%TETA 1.73 1.17 2.02

20%MEA+10%MDEA 1.40 1.19 1.67

15%MEA+15%MDEA 1.29 1.29 1.66

25%MEA+5%AMP 1.31 0.97 1.27

30%MEA 1.00 1.00 1.00

Absorbents of good regeneration performance

Slide 24

Overall performance evaluation of absorbents

Absorbent Absorption Score A

Regeneration ScoreD Total Score(A×D)

30%MEA 1 1 120%MEA 0.9384 0.9516 0.8929814

30%MDEA 0.0345 1.63 0.056235MEA-Based

15%MEA+15%MDEA 0.5751 1.6641 0.957023920%MEA+10%MDEA 0.747 1.666 1.24450225%MEA+5%MDEA 0.8736 0.9996 0.873250620%MEA+10%AMP 0.7719 0.927 0.715551325%MEA+5%AMP 0.893 1.2707 1.1347351

20%MEA+10%AEEA 1.3837 0.609 0.842673325%MEA+5%AEEA 1.12 0.684 0.7660820%MEA+10%TETA 1.24 0.6675 0.827725%MEA+5%TETA 1.224 0.7905 0.967572

20%MEA+10%DETA 1.5759 0.5751 0.906300125%MEA+5%DETA 1.27 0.7654 0.972058

20%MEA+10%PZ 1.298 0.666 0.86446825%MEA+5%PZ 1.4204 0.7912 1.1238205

MDEA-Based15%MDEA+15%AEEA 0.6142 2.6164 1.606992920%MDEA+10%AEEA 0.4725 1.792 0.84672

25%MDEA+5%AEEA 0.2744 1.8876 0.517957425%MDEA+5%PZ 0.3848 2.3868 0.9184406

20%MDEA+10%PZ 0.5888 2.6123 1.538122215%MDEA+15%DETA 0.95 2.028 1.926620%MDEA+10%DETA 0.672 2.0124 1.352332825%MDEA+5%DETA 0.33 2.3881 0.788073

15%MDEA+15%TETA 0.8277 2.0241 1.675347620%MDEA+10%TETA 0.6075 2.485 1.509637525%MDEA+5%TETA 0.3286 2.8656 0.9416362

Slide 25

Energy consumption analysis

Total regeneration heat demand QCO2 EstimationQCO2=Qsens+ Qrea+Qvap

Qsens=Cp*m*△tCp refers to the specific heat of the solutions;m is the mass flow rate of the absorbents;△t stands for the temperature difference between CO2-lean solution and

CO2-rich solution.

Qrea= --△H*MM refers to the CO2 recovery during the regeneration process, mol/h△H is 72 kJ/molCO2 for MEA

Qvap=rH2O*R*A kj/hrH2O is the evaporation heat of H2O，kJ/molH2O. The value is 40 kJ/ molH2O when the operating pressure is 2bar. R is the reflux ratio at the top of regenerator

2

2

H O*

CO

PR P=

2H OP

2

*COP

.

is the saturated steam pressure of the CO2-rich solution，kPa；

is the CO2 partial pressure at the top of regenerator，kPa

Note:For different absorbents, the actual optimal CO2-rich solution CO2 loading and CO2-lean solution CO2loading are inconsistent. In order to facilitate the Rec comparison for absorbents, Rec-50%, which refers to the regeneration energy consumption when the regeneration extent reaches 50%, is chosen as the base.

Slide 26

Relative energy consumption Rec-50%

AbsorbentCO2 loading in the CO2-rich

solution

CO2 loading in the CO2-lean

solution

Relative regeneration

Energy consumption

Energy saving compared to MEA

kg/kg kg/kg KJ/kg CO2 %30%MEA 0.422 0.211 54.74 0.0020%MEA 0.491 0.245 60.3 -10.16

MDEA-BasedMDEA25%+AEEA5% 0.250 0.125 54.54 0.37

MDEA20%+AEEA10% 0.345 0.172 46.57 14.93

MDEA15%+AEEA15% 0.387 0.193 41.59 24.03MDEA25%+PZ5% 0.351 0.175 38.37 29.90

MDEA20%+PZ10% 0.366 0.183 38.52 29.63MDEA15%+PZ15% 0.411 0.205 40.29 26.40

MDEA25%+TETA5% 0.310 0.155 44.53 18.65MDEA20%+TETA10% 0.372 0.186 40.65 25.74

MDEA15%+TETA15% 0.440 0.220 39.12 28.54MDEA25%+DETA5% 0.379 0.189 36.01 34.22

MDEA20%+DETA10% 0.403 0.202 38.50 29.67

MDEA15%+DETA15% 0.463 0.232 41.18 24.78MEA-Based

MEA25%+AEEA5% 0.462 0.231 60.85 -11.16MEA20%+AEEA10% 0.479 0.240 61.34 -12.06MEA25%+AMP5% 0.449 0.225 51.04 6.76

MEA20%+AMP10% 0.404 0.202 51.15 6.55MEA25%+DETA5% 0.500 0.250 59.88 -9.38

MEA20%+DETA10% 0.517 0.258 67.12 -22.62MEA25%+MDEA5% 0.373 0.186 53.54 2.20

MEA20%+MDEA10% 0.352 0.176 45.21 17.42MEA15%+MDEA15% 0.307 0.154 47.21 13.76

MEA25%+PZ5% 0.468 0.234 64.29 -17.44MEA20%+PZ10% 0.488 0.244 56.50 -3.22

MEA25%+TETA5% 0.479 0.240 66.17 -20.89MEA20%+TETA10% 0.508 0.254 58.98 -7.75

Slide 27

Conclusion

29 kinds of absorbents have been tested,7 of them have been expected to have better overall performance relative to 30 wt% MEA by two methods. The energy consumption reduction for novel solvents is nearly 30%.

The evaluation method still needs to be improved. Although a tendency can be predicted, the method is too rough to give a precise answer due to too much assumption and approximation.

Mixing amines is a promising way of solvent selection for CO2 capture.

Slide 28

Outlook

• To improve the evaluation method for solvent selection.

• To testify the true energy consumption in pilot study.

• To complete the systematic study of mixed amines, such as degradation, corrosion and environmental impact.

Slide 29

Thanks for your attention!