Process for in situ oil shale retorting with off gas recycling

Patent · Tue Nov 30 04:00:00 EST 1976

OSTI ID:7315839

Cha, C Y; Ridley, R D

This process is suitable for in situ retorting of oil shale particles, with retorting proceeding downwardly through a bed of broken pieces of shale. When a single bed is being retorted, air is passed downwardly after ignition until a hot zone trailing the combustion zone has built up to some predetermined thickness, for example, 20 feet having a temperature over 1000/sup 0/ F. Thereafter off gas from the bed is recycled downwardly without air. Reaction of the recycle gas with the heated spent shale increases the heating value of the resultant off gas. The transfer of heat without combustion increases the yield of oil. When the maximum temperature in the bed drops to a predetermined temperature above the self-ignition temperature of the shale, air is again introduced to reestablish a combustion zone and build up a hot zone. Retorting continues with alternating combustion and recycling periods through the entire bed. When multiple beds of oil shale particles are retorted air is passed downwardly through one of the beds to maintain a combustion zone until a sufficient hot zone trailing the combustion zone has been produced. Air is then passed through a second bed of oil shale particles and at least a portion of the off gas from the second bed is recycled through the first bed for cooling the hot zone, increasing the heating value of the off gas, and retorting additional oil. Additional beds of oil shale particles can be included in series with combustion zones being intermittently established in each of the beds, alternating with cooling by recycled off gas. 38 claims, 4 figures.

• Assignee: Occidental Petroleum Corp.
• Patent Number(s): US 3994343
• OSTI ID: 7315839
• Country of Publication: United States
• Language: English

Related Subjects

04 OIL SHALES AND TAR SANDS
040401* -- Oil Shales & Tar Sands-- In Situ Methods
True & Modified
BITUMINOUS MATERIALS
CARBONACEOUS MATERIALS
CHEMICAL REACTIONS
COMBUSTION
ENERGY SOURCES
FOSSIL FUELS
FUELS
IGNITION
IN-SITU COMBUSTION
IN-SITU PROCESSING
IN-SITU RETORTING
OFF-GAS SYSTEMS
OIL SHALES
OIL YIELDS
OXIDATION
PROCESSING
RETORTING
THERMOCHEMICAL PROCESSES
YIELDS