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

Results and discussion

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 H2 . 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 ,ChinaChemical 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