Hongna Wang Nov. 20, 2012 Journal Report About Coal and sludge

Eulerian–Lagrangian method for three- dimensional thermal reacting flow with application to coal gasifiers Dale M.Snider, SamuelM.Clark CPFD Software LLC, USA Chemical Engineering Science 66 (2011) 1285–1295

 Energy transport and chemistry are modeled in an extension of the Eulerian–Lagrangian computational particle fluid dynamics (CPFD) methodology. The CPFD methodology is based on the MP-PIC method.  In our extension of CPFD, an enthalpy equation describes energy transport for fluid, and provides for transfer of sensible and chemical energy between phases and within the fluid mixture. Homogenous and heterogeneous chemistry are described by reduced-chemistry.  A three-dimensional example of a hot fluidized bed coal gasifier is presented to demostrate the model. Introduction

 The CPFD cell chemistry uses properties mapped from discrete particles to the grid, and the cell particle properties used in chemistry vary from cell to cell depending on the particle distribution in the system. Modelling

Reactor

Results and discussion

 The bed surprisingly has a uniform temperature except at the feed-sparger arms.  There were variations in gas species radially and axially in the bed such as pockets of H 2. In this coal gasifier would not be modeled well by a simple plug-flow reactor model.  The sparger design used in this study appears to be responsible for much of the bed non-uniformity in gas–solids distribution and chemical reactions. The sparger design would be a candidate to improve performance. Conclusion

Rheology and thixotropic properties of slurry fuel prepared using municipal wastewater sludge and coal Jian-zhong Liu, Rui-kunWang Zhejiang University,China Chemical Engineering Science 76 (2012) 1–8

 Municipal wastewater sludge MWS can be directly combined with coal, water, and additives to produce coal–sludge slurry (CSS). Compared with coal–water slurry, CSSs behaved as more obvious pseudo- plastic fluids and the sludge enhances the pseudoplasticity and thixotropy of the slurry. Introduction

 Rheological and thixotropic behaviors are the major character- istics that influence the stability of the storage procedure, fluidity of the transportation procedure (Meng et al., 2000), and spray- ability (Basel et al., 2005) and flammability of the spray and combustion procedures of slurry fuel.  Our research group has carried out studies on the slurryability, rheology, and stability of CSSs. Introduction

 1.Slurryability properties of CSS  After the addition of sludge, the viscosity of the slurry increased and the FVC decreased which can be attributed to sludge particles are abundant in cellular tissues and flocs. Results and discussion

 2.Rheological characteristics of CSSs—C↑ n↓  Rheological index n was close to 1 and was reduced slightly with increasing concentration, indicating that the non- Newtonian pseudoplastic behavior of CWSs was enhanced. Results and discussion

 2.Rheological characteristics of CSSs—α↑ n↓  These parameters showed that the rheological properties well fitted the Herschel–Bulkley flow model. Results and discussion

 3. Thixotropic characteristics of CSS---α ↑ thixotropic loop area ↑ Results and discussion

 4.Effect of sludge particle size The sludge disposal volume and CSS concentration can be improved by properly grinding the sludge to reduce its particle size. Results and discussion

 With increasing CSS concentration, t and K increased, and the pseudoplastic behavior and thixotropyof the CSSs strengthened.  The flow behaviors of the CSSs well fitted the Herschel– Bulkley model  The costs of CSS transportation can be reduced by appropriately reducing sludge particle size. Conclusions