(185a) Mechanistic Study of Water/Solids Settling in a Diluted Bitumen System: Statistical and Image Analysis

Mechanistic
study of Water/Solids Settling in a Diluted Bitumen System: Statistical and
Image analysis

Nitin
Arora¹(nitin@ualberta.ca)

Suzanne
M. Kresta¹ (kresta@ualberta.ca)

Samson
Ng² (ng.samson@syncrude.com)

Sujit
Bhattacharya² (bhattacharya.sujit@syncrude.com)

1.     
Department
of Chemical and Materials Engineering, University of Alberta, Edmonton, AB T6G
2V4, Canada

2.      Syncrude Canada Ltd., Edmonton, AB T6N 1H4, Canada

Keywords:
nearest neighbor analysis, froth, sweep flocculation, clays, floc size

Abstract

The
removal of water and solids (clays and heavy minerals) from bitumen froth is a
key step in bitumen extraction from Athabasca oil sands ¹.
Bitumen froth
contains approximately 60% bitumen, 30% water and 10% solids by mass ¹. Bitumen froth is diluted with
naphthenic solvent followed by demulsifier addition to remove water and solids.
To achieve the desired level of dewatering, process specifications for both the
 bulk concentration of demulsifier and the mixing  conditions (injection
concentration, energy dissipation  and mixing time) must be determined². The presence of
asphaltenes, naphthenic acids and bi-wettable solids on bitumen-water interface¹
makes water/solids separation from bitumen, a slow and difficult process. The
goal of this work is to determine the settling mechanism (sweep flocculation,
coalescence) and interactions between particles and drops (water-water,
water-solid and solid-solid) using spatial statistics and image analysis.

An image analysis protocol for
drop size distribution of spherical water drops was previously developed for
diluted bitumen system ³. However, the protocol could not
be applied to bitumen froth because of non-spherical water drops and higher
solids content (Figure 1).
There is a need for development of image analysis algorithm for froth. 

Figure
1: Microscope image with 40X objective containing
spherical and non-spherical drops and solids.

Figure
2: Cluster identification after
pre-processing of Figure 1.

We
have developed a protocol which isolates objects (solids and water) from a
microscope image and determines their location. A
series of test images containing two objects (A and B corresponding to water
and solids) with varying amounts of clustering have been developed to test the point-nearest-neighbor
(PNN) method for cluster detection. PNN method provides an overall clustering
tendency in an image; however, the method cannot quantify the number, size and
location of clusters in an image space. A separate protocol is being developed
to obtain this information (Figure 2). Once
developed, the image analysis protocol will be integrated with a real time
imaging system to monitor clustering and hence detecting operational problems.

Highlights

·        
Demulsifier
performance can be monitored by cluster detection of bitumen froth images.

·        
The
composition of the clusters: clay-water, water-water, clay-clay, can also be
detected.

·        
The
water/solid settling mechanism affects demulsifier performance and settling
time.

References

1.        Masliyah, J.; Xu Z.; Dabros M ;Czarneck. J. Chapter 7. Froth Treatment, Tipman R.
In: Handbook on Theory and Practice of Bitumen Recovery from Athabasca Oil
Sands Volume II: Industrial Practice. Kingsley Knowledge Publishing;
2013:211-250.

2.        Chong JY. Mixing
Effects on Chemical Demulsifier Performance in Diluted Bitumen and Froth. 2013.

3.        Leo SS. Measurement
and Analysis of Changes in Drop Size Distribution during Bitumen Clarification
using Image Analysis. 2013.