Process for heating coal-oil slurries

Patent · Tue Jan 03 00:00:00 EST 1984

OSTI ID:864824

Braunlin, Walter A ^[1]; Gorski, Alan ^[2]; Jaehnig, Leo J ^[3]; Moskal, Clifford J ^[4]; Naylor, Joseph D ^[5]; Parimi, Krishnia ^[6]; Ward, John V ^[7]

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1. Spring, TX
2. Lovington, NM
3. New Orleans, LA
4. Oklahoma City, OK
5. Houston, TX
6. Allison Park, PA
7. Arvada, CO

Controlling gas to slurry volume ratio to achieve a gas holdup of about 0.4 when heating a flowing coal-oil slurry and a hydrogen containing gas stream allows operation with virtually any coal to solvent ratio and permits operation with efficient heat transfer and satisfactory pressure drops. The critical minimum gas flow rate for any given coal-oil slurry will depend on numerous factors such as coal concentration, coal particle size distribution, composition of the solvent (including recycle slurries), and type of coal. Further system efficiency can be achieved by operating with multiple heating zones to provide a high heat flux when the apparent viscosity of the gas saturated slurry is highest. Operation with gas flow rates below the critical minimum results in system instability indicated by temperature excursions in the fluid and at the tube wall, by a rapid increase and then decrease in overall pressure drop with decreasing gas flow rate, and by increased temperature differences between the temperature of the bulk fluid and the tube wall. At the temperatures and pressures used in coal liquefaction preheaters the coal-oil slurry and hydrogen containing gas stream behaves essentially as a Newtonian fluid at shear rates in excess of 150 sec.sup. -1. The gas to slurry volume ratio should also be controlled to assure that the flow regime does not shift from homogeneous flow to non-homogeneous flow. Stable operations have been observed with a maximum gas holdup as high as 0.72.

• Research Organization: Pittsburgh and Midway Coal; SRC International Inc.
• Sponsoring Organization: USDOE
• DOE Contract Number: AC01-76ET10104; AC05-78OR03055
• Assignee: Pittsburg & Midway Coal Mining Co. (Englewood, CO)
• Patent Number(s): US 4424108
• Application Number: 06/337,301
• OSTI ID: 864824
• Country of Publication: United States
• Language: English

Related Subjects

process
heating
coal-oil
slurries
controlling
gas
slurry
volume
ratio
achieve
holdup
flowing
hydrogen
containing
stream
allows
operation
virtually
coal
solvent
permits
efficient
heat
transfer
satisfactory
pressure
drops
critical
minimum
flow
rate
depend
numerous
factors
concentration
particle
size
distribution
composition
including
recycle
type
efficiency
achieved
operating
multiple
zones
provide
flux
apparent
viscosity
saturated
rates
below
results
instability
indicated
temperature
excursions
fluid
tube
wall
rapid
increase
decrease
overall
drop
decreasing
increased
differences
bulk
temperatures
pressures
liquefaction
preheaters
behaves
essentially
newtonian
shear
excess
150
-1
controlled
assure
regime
shift
homogeneous
non-homogeneous
stable
operations
observed
maximum
72
coal particle
coal-oil slurry
flow regime
temperature difference
tube wall
volume ratio
heat flux
size distribution
flow rates
pressure drop
gas flow
gas stream
heat transfer
flow rate
coal liquefaction
particle size
containing gas
temperature differences
efficient heat
temperature excursion
permits operation
multiple heating
controlling gas
hydrogen containing
rapid increase
shear rate
stable operation
increased temperature
newtonian fluid
allows operation
/208/