Advanced Coal Gasification Technology based on Exergy Recuperation

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1 Advanced Coal Gasification Technology based on Exergy Recuperation The University of Tokyo Institute of Industrial and Science Collaborative Research Center for Energy Engineering Atsushi Tsutsumi

2 Japan s New Coal Policy C3 Initiative towards the establishment of the Clean Coal Cycle Demonstration of diversified CCT models, with coal gasification as the core technology Hybrid Gasification of coal, biomass, waste plastics, biomass coal waste gasification Reduced ore oil Co-production of chemicals Co-production of Steel iron Iron and steel Diesel, naphthalene, etc. Methanol, acetic acid, etc. Chemicals Syn gas H 2 CO Electric power commercial, transportation Production CO 2 sequestration IGCC IGFC FC GT ST boiler Power plants, Automobiles, etc. Hydrogen Station FCV gasifier Stationary FC slug Effective use Blast furnace Steel Storage METI C3 Initiative

3 High-efficiency power generation technology development

4 Sustainable Clean Coal Technology More Efficient Utilization of Coal exergy recuperative gasification partial oxidation gasification at high temperature -> steam gasification at low temperature Hybrid Gasification Diversification of energy resources biomass, waste, plastics, heavy oil, etc. low rank coal Zero-Emission SOx, NOx, PM, heavy metals CO 2 sequestration ready hydrogen co-production

5 Integration Technology: Energy Cascading & Exergy Recuperation Combustion Exergy Recuperation 2000 K Chemical Energy Thermal Energy Chemical Energy Thermal Energy Hydrogen Energy Thermal Energy H 2 O Fuel combustion reforming reaction H K Thermochemical cycle for hydrogen production as a thermochemical heat pump The recuperation of low-level heat can minimize the energy loss in the energy conversion process Cascade utilization (IGCC/IGFC) Exergy recuperation (A-IGCC/IGFC) combustion coal gasifier GT ST coal gasifier GT ST waste heat combustion coal gasifier fuel cell GT ST coal gasifier fuel cell GT ST waste heat Partial oxidation Low cold gas efficiency Recycle of waste heat from GT/FC Large cold gas efficiency Reduction of exergy loss

6 Energy flow in the cascade utilization IGCC system IGCC A-IGCC η = = 53% (48%) η = 100 Cold gas efficiency 80% = 59% (57%) IGFC A-IGFC exergy rate gasifier FC ST power GT power exhaust 12 6 loss power η = = 60% (55%) 0 η = = 76% (70%) 12 0 condenser loss

7 Comparison between conventional and advanced IGCC/IGFC Conventional IGCC/IGFC A-IGCC/IGFC integration cascade utilization exergy recuperation gasification partial oxidation high temperature ( C) steam reforming low temperature ( C) gasifier Entrained flow bed high density CFB efficiency 46 48% (IGCC) 55% (IGFC) 53 57% (A-IGCC) 65% (A-IGFC) Projection of improvement of generation efficiency

8 A novel high-density triple-bed CFB (TBCFB) gasifier Heat carried particles CO, CO 2 Pyrolyzer Downer reactor Combustor Pyrolyzer Coal Tar/gases CO,H 2 Coal Gases (CO, H 2, CH 4 etc.)+tar Char Gasifier Bubble fluidized bed Char +Steam CO H 2 Unreacted Char Heat Particles Char +particles Gasifier Char Combustor Riser reactor Unreacted Char +O 2 CO, CO 2 Heat O 2 Steam Heat carried particles Illustrated by Dr Mastuoka, AIST, Japan In order to use the heat effectively, circulating a large amount of particles in this system is required!!!

9 A novel large-scale TBCFB system Riser: 0.1mX16.6m Downer: 0.1mX6m BFB: 0.75m X 0.27m X 3.4m

10 Heat Utilization Energy Cascading Self-heat Recuperation Chemical Energy Thermal energy (high Temp.) Thermal energy (low Temp.) Thermal Energy Heat Circulation by self-heat recuperation can reduce the energy requirement in the process drastically Self heat Exchange Self-Heat Recuperation T T1 Q heat exchange T Q heat exchange Tb T0 Effluent Feed T1 Tb Tb Effluent Feed Energy Saving Q T0 Energy Saving Q Y. Kansha, N. Tsuru, K. Sato, C. Fushimi, A. Tsutsumi, Industrial and Engineering Chemistry Research 48(16), , 2009

11 CD F F The heat of condensation is recuperated by compressors and exchanged with the heat of vaporization. RB Temperature Q RB Energy consumption Q CD Heat supplied by reboiler is wasted in the condencer Enthalpy Energy consumption Energy saving 80 90% reduction Self heat is recuperated by adiabatic compression $6&'()*+563,8-/056**9*:;*< #"!! #!!! "!!! 7561&6/06.4* 203/044./056!"#$%&'()*$+,-.&) $%&'()*'&+,-&'./01&* 203/044./056 85% reduction in energy consumption by self-heat recuperation

12 Exhaust gas Condencer CO 2 50 C 120 C Flue gas Absorption Reboiler Stripping In the chemical absorption process (MEA), the process energy is needed 4.1GJ/t-CO 2. 68% energy saving can be achieved by self-heat recuperation

13 High energy demand for drying because of large latent heat of water evaporation Heat amount [ MJ/kg] LHV(EHV) Combustion gas (900 C) HHV Self combustion Water evap. heat Moisture content [ wt% wb] No heat recovery No heat recovery Heat recovery Heat recovery Conduction drying Hot air drying MVR SHR Conduction drying Hot air drying MVR SHR Comparison of required energy input Comparison of exhausted CO 2

14 Sustainable Clean Coal Technology Exergy Recuperative Gasification The hydrogen and power co-production by using the exergy recuperation gasification technology could considerably increase the energy utilization efficiency Exergy Recuperative Drying The self-heat recuperative drying which recovers not only latent heat, but also sensible heat can save drying energy. This is a key technology for the improvement of power generation efficiency in the utilization of brown coal and/or biomass with high moisture content. Exergy Recuperative CCS Exergy Recuperative Gas Cleaning The energy for the CO2 separation and gas cleaning can be reduced by over 70%.