Numerical simulation of GSP gasifier with various swirler angles

Transcription

1 19-22 May 2014 Dresden/Radebeul, Germany Numerical simulation of GSP gasifier with various swirler angles Dapeng Bi, Qingliang Guan, Weiwei Xuan, Jiansheng Zhang* Department of thermal engineering, Tsinghua university, China IFC 2014

2 Outline Background Method of calculation Results and discussion Conclusions

3 Background(1/3) Shenhua Group Corp. adopted Siemens GSP pulverized coal gasification technology to produce polypropylene in NingXia province of China. As this was the first commercial 2000 tons/d GSP gasifier, some problems occurred during its first trail operation on Low carbon conversion Thermal wear of membrane wall Failure to slag on the inner wall

4 Background(2/3) Tsinghua gasifier(ii) GSP gasifier CWS Feed Straight Jet nozzle L/D=3 Burner Membrane wall Quench chamber Granulated slag Dry coal Feed Swirling jet nozzle L/D=2 20% fly ash 80% slag 80% fly ash 20% slag

5 Background(3/3) First level Nozzle Operating parameter Chamber Second level Particle diffusion Flow field Third level Mixing of gas-solid flow 2/CO 2 O 2 /Fuel gas CWS Fourth level Fifth level Gas composition Carbon conversion Develop numerical model for GSP gasifier Particle distribution Chemical reaction Residence time Industrial result The impact of its structure on gasification Temperature distribution Membrane lifetime Slag property

6 Method of calculation(1/3) Numerical simulation of GSP gasifier three dimensional/steady-state/turbulence/multiphase flow/reactions Gas flow(euler) Mass/momentum/ energy/species PDF Turbulence k-e/k-w/ RSM DRW CTM Particle(Lagrange) Position/velocity /temperature Source Drag force Homogeneous reactions EBU Arrhenius equilibrium Radiation/ Heat transfer Coal analysis Pressure Devolatilization One-step/twostep/CPD Heterogeneous reations

7 Method of calculation(2/3) Gas flow: ( u ) x i i 0 ( uu i j) P u i u u S x j xi x j x j i j i Turbulence: Realiziable k Particle: m du / dt F F F p p d g o Devolatilization: dm dt Heterogeneous reactions v A v Ev exp( ) m RT R it, p R R v R i, d i, k R i, d i, k Radiation:P 1

8 Method of calculation(3/3) Tuebulence-chemistry:PDF model t ( Y ) uy J R S i i i i i i i( f, H) i 1 0 p( f ) ( f, H) df i Turbulence-particle:Discrete random walk u 0.5 p (2 k/ 3) t min( ts, tt)

9 Results and discussion(1/7) Chamber Nozzle structure Grid meshing (22w) Comparison between simulation with design and other s T/K CO/% CO 2 /% N 2 /% H 2 /% Carbon Conversion/% t/s Simulation Design / Xu et al. [4] /

10 U (m/s) Results and discussion(2/7) z (m) y/ymax (-) Vector of velocity Countours of velocity Radial distribution of axial velocity

11 Results and discussion(3/7) Particle concentration Particle track

12 Results and discussion(4/7) Temperature CO H 2

13 Mole Fraction (-) T(K) Mole Fraction(-) T(K) Results and discussion(5/7) T co co2 h2 h2o o co co2 h2 h2o o2 T z (m) Species/Temperature distribution along axis z (m) 1200 Species/Temperature distribution along cross-section

14 Results and discussion(6/7) S R R 2 1 i / o 2(1 ) tan nb / 2 R o cos S=0 S=0.46 S=0.61 S=1.54

15 Results and discussion(7/7) Ratio of short-circult particles and carbon conversion as increasing swirl number

16 Conclusions 1.The flow field of GSP gasifier can be divided into four regions: swirling jet region, internal recirculation region, external recirculation region and plug flow region. Oxidation reactions are mainly conducted in swirling jet region and upper part of internal recirculation region. Gasification reactions dominated the other regions of the gasifier. 2.The " V " shaped high temperature flame directly impinged on the 1/3 height of the wall which may cause the high temperature corrosion of the gasifier, so carefully attention should be paid to the protection of this part. 3.Because of the effect of external recirculation, coal particle mainly concentrated on the dome part of the gasifier which is beneficial to prolong the resident time and promote carbon conversion. 4.As the angles of swirler increasing, the flow field changed from straight jet to swirling jet and the carbon conversion increased from 66.8% to 98.8% which indicated the structure of nozzle is critical to the performance of the gasifier.

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