PILOT PLANT HANDLING AND RHEOLOGICAL BEHAVIOR OF …projet.ifpen.fr/Projet/upload/docs/application/pdf/2013-11/briceno_m… · Viscoplastic Fluids: From Theory to Application IFPEN,

Viscoplastic Fluids: From Theory to Application IFPEN, Rueil-Malmaison 18 – 21 November 2013

PILOT PLANT HANDLING AND RHEOLOGICAL BEHAVIOR OF COLLOIDAL

PETROLEUM COKE-IN-WATER FUEL SUSPENSIONS

Gustavo NUÑEZ†, Hidekel OLMEDO, Nelson ROJAS, Suyin TORRES, María BRICEÑO Nano Dispersions Technology Inc.


Nano Dispersions Technology, Inc.

•  Small high-tech company that develops products based on colloidal and nanodispersions using a top-down approach

•  Located in the City of Knowledge since 2007, a

Science Park in Panama sponsored by the UN and the EU

We have developed a mainly colloidal suspension of petroleum coke in water We are designing a manufacturing plant to provide 40 MW in a commercial boiler


There are increasing piles of petcoke around the world.

Fuel oil price is heavily affecting the economy of many power plants

There are increasing piles of petcoke around the world. Fuel oil price: 16 US$/MMBTU

Petcoke price: 2 US$/MMBTU


Proof of concept has been successful

Colloidal Petcoke in Water (CPW): Low volatile content petcoke ignites easily and produces a stable flame, without a support fuel


Commercial grind to specifications – 200 mesh

Wet-comminution grind

•  Most particles are colloidal •  Virtually no sedimentation

for weeks


Is it possible to handle and atomize this material? Is it going to drain from a tank?

Fuel composition: Petcoke: 61 % w/w Additives: 0.3 % w/w Water: 38.7 % w/w


Evaluation of rheological behavior: •  Rotational rheometer (parallel plates) – steady state,

and dynamic oscillatory tests (sample volume < 2 mL) •  Pipe viscometer (1/2” to 1”, sample volume 200 L,

laminar flow, 28 ºC – 32 ºC) •  Tank drainage

The truth about this (and many!) VPF: Repeatability is acceptable (max. error < 10 %) but reproducibility is pretty bad, specially for larger volumes


Rotational rheometry – parallel plates Viscosity as a function of temperature

This material is homogeneous and stable to sedimentation


Rotational rheometry – parallel plates Material functions

Steady state and dynamic tests: •  Yield stress, σy: 0.5 Pa •  Phase angle, δ: 20º – 25º •  Relaxation time, λ: 0.016 s


Pipe viscometry

γ = 32QπD3

143+ d lnQ

d ln p!

"#

$

%&

τ =D −Δp( )4L

ReMR: 1 - 200

Slip or lubricated flow


Pipe viscometer Material functions

•  Yield stress, σy ≈ 23 Pa •  Slope of shear thinning region, n: 0.3086


Data fitting

Carreau model

Bingham model η =

σ y

γ+µ∞

η =ηo −η∞

1+ λ γ( )2( )1−n2

+η∞

Fitted parameter:

ηo and η∞

No fitted parameters

(µ∞= η∞)


Combination of methods and models (shear rate: 2 to 800 s-1)

Lack of reproducibility: Shear history and microbubbles


Viscosity for engineering design

Viscosity for pumping (< 100 s-1): ηo ( ≈ 500 mPa.s) Viscosity for atomization (100 s-1): 200 mPa.s – 400 mPa.s


Ongoing investigation – tank drainage

Uneven surface observed in tanks of 1 L – 2000 L, gravity drainage or pumped

Undrained volume depends on tank shape and outlet diameter


Preliminary results - rectangular and cubical tanks

1 2

θ θ

W 2W

d d

Tank 1: •  θ is constant after

uneven surface onset •  Drainage is gradual,

faster for larger d

Tank 2: •  θ increases after uneven surface

onset •  Drainage is fast the first few

seconds, then stops completely

Ho Ho

The free surface relaxes slowly (> 1 h)


Preliminary results

Tank 1

Tank 2

More work is necessary in order to establish operational criteria

D

d

Rectangular tank

Cubic tank


CONCLUSIONS •  The observed pipe behavior may be interpreted as a

lubricated flow in which the continuous phase migrates to the wall, thereby reducing friction.

•  Acknowledging this phenomenon has a positive impact in equipment costs and handling operations.


Documents

PILOT PLANT HANDLING AND RHEOLOGICAL BEHAVIOR OF …projet.ifpen.fr/Projet/upload/docs/application/pdf/2013-11/briceno_m… · Viscoplastic Fluids: From Theory to Application IFPEN,