Makoto Kobayashi. 20 May, 2014

Transcription

1 Inhibition and Elimination of Carbon Deposition in Dry Gas Desulfurizaion Process of Advanced Oxy-fuel IGCC Power Generation with Carbon Capture Capability with Small Penalty on Thermal Efficiency. 6 th IFC on IGCC & XtL Technologies Central Research Institute of Electric Power Industry Makoto Kobayashi 20 May, 2014

2 Is it possible to eliminate the pre-combustion processes for purpose to reduce power consumption for CO 2 capture? Section 1 Key issue to establish the Oxy-fuel IGCC for CO 2 capture and storage.

3 Concept and basic design of Oxy-fuel IGCC O 2 -CO 2 blown gasification + Semi-closed cycle GT" CO 2 is obtained by mist elimination of exhaust." Thermal efficiency is 44% LHV at transmission end." Dry Desulfurization Process

4 Operation of desulfurization reactors

5 Three Reactor Sulfur Removal System

6 Scope and objective of this study Key issue to establish Oxy-fuel IGCC power generation plant; carbon deposition" 2CO CO 2 + C"; Boudouard reaction" Exhaust Gas Recirculation (EGR) to sulfur removal reactor is effective on preventing carbon deposition in the steady state operation." It is important to examine impact of carbon deposition when EGR is not available during plant startup." Possibility to eliminate carbon deposit during the succeeding regeneration step."

7 Section 2 Experimental examination of carbon deposition on Dry gas desulfurization sorbent.

8 Deteriorative effect of carbon deposition Honeycomb desulfurization sorbent was cracked due to expansion of zinc ferrite particle through carbon deposition.

9 Gas condition at gasifier outlet and at dry sulfur removal process

10 Chemistry related to sulfur removal Boudouard reaction, carbon deposition 2CO!! CO!!+ C (1) 2 R B P CO2 P CO (2) water gas shift reaction CO + H 2 O!! CO 2!+ H 2 (3) R W P CO2 P H! P CO P H! O (4) Sulfidation of zinc ferrite ZnFe 2 O 4 + 3H 2 S + H 2 ZnS + 2FeS + H 2 O (5) Regeneration of spent zinc ferrite ZnS + 2FeS + 5O 2 ZnFe 2 O 4 + 3SO 2 (6)

11 Deposition test in the non-equilibrium condition for water gas shift reaction

12 Experiment specific to key issue Key issue is to inhibit carbon deposition and eliminate deposited carbon for actual operation of the dry gas purification process." We already confirmed that EGR can effectively inhibit carbon deposition." To evaluate amount of carbon deposition during reduction procedure at starting-up of the plant, where the EGR is not available." How much amount of the deposited carbon can be eliminated during the oxidative condition of regeneration procedure."

13 Fixed bed reactor test apparatus 1 T = 450 P = 0.98 MPa 1 Each gas is supplied through independent MFC.

14 Sulfur removal with the zinc ferrite sorbent

15 Chemistry related to sulfur removal Boudouard reaction, carbon deposition 2CO!! CO!!+ C (1) 2 R B P CO2 P CO (2) water gas shift reaction CO + H 2 O!! CO 2!+ H 2 (3) R W P CO2 P H! P CO P H! O (4) Sulfidation of zinc ferrite ZnFe 2 O 4 + 3H 2 S + H 2 ZnS + 2FeS + H 2 O (5) Regeneration of spent zinc ferrite ZnS + 2FeS + 5O 2 ZnFe 2 O 4 + 3SO 2 (6)

16 Behavior of carbon deposit during regeneration Difference Reverse to residual amount of consumption Integration l l Carbon deposit can be released by oxidation during regeneration step. Oxidation of carbon is slower than that of zinc ferrite oxidation. 16

17 Amount of carbon deposit in reduction and its elimination in regeneration In the small R B region, amount of carbon deposit during reduction increases." Most part of deposit is eliminated in the succeeding regeneration step. 17

18 Sulfur breakthrough comparison ² Sulfur removal performance is unchanged in spite of carbon deposit incinerated during preceding regeneration step. 18

19 Conclusion Amount of carbon deposit was considered relatively small, i.e. 1wt%, when EGR is not available during plant startup." It was possible to eliminate carbon deposit during the succeeding regeneration step." Impact of carbon deposition to the sulfur removal efficiency is negligibly small at expected condition." Part of this study financially is supported by NEDO.