The Effects of Operation Parameters on the Performance of Entrained-bed Pulverized Coal Gasifier with High Fusion Temperature Coal

Transcription

1 The Effects of Operation Parameters on the Performance of Entrained-bed Pulverized Coal Gasifier with High Fusion Temperature Coal Zhenghua Dai*, Zhonghua Sun, Xin Gong, Zhijie Zhou, Fuchen Wang Institute of Clean Coal Technology Key Laboratory of Coal Gasification and Energy Chemical Engineering of Ministry of Education East China University of Science and Technology

2 Content The novel syngas cooling process for IGCC system Coal analysis data Simulation results analysis and discussion Conclusions P2

3 1 The novel syngas cooling process for IGCC system Typical entrained-bed coal gasification technologies Technology GE coal feeding refractory lining coal water slurry refractory brick Shell pulverized coal membrane wall OMB (Opposed - Multi -Burner) (I) coal water slurry (II) pulverized coal (I) refractory brick (II) membrane wall high temperature syngas cooling (I) water quenching (II) radiation boiler + convection boiler recycle syngas quenching + convection boiler (I) water quenching (II) radiation boiler + recycle syngas quenching + convection boiler P3

4 Schematic structure of the OMB gasifier The OMB gasifier is featured with four horizontal impinging burners, which can intensify mixing and improve residence time distribution. P4

5 The OMB pulverized coal gasification technology with novel syngas cooling process Coal Fuel 1 2 Pulverized coal Pulverized coal preparation Pulverized coal +N2 Steam 5 Steam OMB Gasification Crude syngas Steam radiation boiler convection boiler Quenching gas ~280 Crude syngas Syngas water scrubbing Crude syngas 6 Condensate 3 High pressure N2 Pulverized coal transportation 4 Oxygen Boiler water Slag Boiler water Black water Slag water treatment Grey water Soft water Filter cake and waste water This sysngas cooling process can reduce the radiation boiler length and investment. The gas temperature at inlet of the convection boiler can be adjusted online and avoid the ash agglomeration. P5

6 2 Coal analysis data Proximate analysis, wt%(dry) Ash 32.0 Volatile matter 9.0 Fixed carbon 59.0 Ultimate analysis, wt%(dry) C 61.3 H 2.0 N 0.7 S 2.7 O 1.3 Ash 32.0 Ash analysis, wt%(dry) SiO Al 2 O Fe 2 O P 2 O CaO 5.9 MgO 0.4 Na 2 O 0.5 K 2 O 1.0 SO P6

7 Ash fusion temperature with Flux(CaCO3) Flux (CaCO 3 ) addition % Deforming temperature( ) Softening temperature( ) Fusion temperature( ) >1550 > P7

8 Viscosity-Temperature characteristics of coal ash with Flux(CaCO3) 100 Viscosity(Pa.s) %CaCO3 3%CaCO3 5%CaCO Temperature( ) P8

9 3 Simulation results analysis and discussion Simulation diagram of the OMB pulverized coal gasifier DRY-COAL QTRANSFE DECOMP INBURNER RYIELD OXYGEN N2 STEAM FUEL BURN RGIBBS QLOST PORDUCT Q Heat loss % gasification temperature C Dai, ZH, etc. Pilot-trial and modeling of a new type of pressurized entrained-flow pulverized coal gasification technology. Fuel 2008; 87: P9

10 The basic operation conditions and gasification performance with no flux Operation conditions Operation pressure,mpa(g) 4.0 Coal flow rate, t/h 80.5 Oxygen flow rate, Nm 3 /h Oxygen purity, % 99.6 Nitrogen flow rate, Nm 3 /h 9200 Middle pressure steam flow rate, t/h 15.1 boiler water flow rate, t/h ~18 Gasification performance Gasifier temperature, 1600 Gasifier heat loss(2.5%), GJ/h 45 Steam by membrane wall, t/h 13 H 2, mol% (dry basis) 23.9 CO, mol% (dry basis) 64.9 CO 2, mol% (dry basis) 2.8 CH 4, mol% (dry basis) Carbon Conversion, % 99 Specific coal consumption, kg(dry basis)/knm 3 (CO+H 2 ) Specific oxygen consumption, Nm 3 /knm 3 (CO+H 2 ) P10

11 Effects of oxygen coal ratio and steam coal ratio on the gasification performance P11

12 The oxygen coal ratio and steam coal ratio are required to adjust at the same time. When The fluctuation range of coal flow rate is +/-5%, the fluctuation range of gasification temperature is 280. As increasing the heat loss of the gasifier from 0.9% (1300 ) to 3.6% (1700 ), the oxygen and coal consumption increases 18% and 7% respectively. P12

13 Base coal Effects of ash content on the gasification performance Coal 1 Coal 2 Proximate analysis (wt%,dry basis) Ash V FC Ultimate analysis (wt%,daf) Operation conditions Gasifier perssure, MPa(G) 4 Base coal Gasification temp 1600 Coal 1 Coal 2 Oxygen-coal ratio,nm 3 /t coal Steam coal ratio, kg/tcoal Gasification performance Carbon conversion,% Specific coal consumption, kg coal/knm 3 (CO+H 2 ) Specific oxygen consumption, Nm 3 oxygen/knm 3 (CO+H ) The coal quality has great effect on the operation conditions and gasification performance. When The fluctuation range of coal ash content % is +/-2, the fluctuation range of gasification temperature is 140. P13

14 Effects of adding flux on the gasification performance Specific coal consumption Specific oxygen consumption % 1 3% 2 5% 3 Flux(CaCO3) 250 0% 1 3% 2 5% 3 Flux(CaCO3) 0 3% 5% Temp Heat loss 2.50% 1.80% 1.40% The proper addition of flux (CaCO 3 ) can observably reduce the coal and oxygen consumption. P14

15 4 Conclusions OMB pulverized coal gasification technology with novel syngas cooling process is proper for IGCC. For pulverized coal gasification, the steady of coal flow rate, the steady of coal quality and measurement of coal flow rate are very important. The operation parameters are related to the ash content, ash fusion temperature, ash viscosity-temperature characteristics, heat loss of gasifier, etc. These parameters are combined to determine optimal gasification performance and operation stability. P15

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