There are two main industrial retort technologies for oil shale processing – using retort gas as a gaseous
heat carrier or semicoke as a solid heat carrier. The first one is represented in Estonia by the Kiviter Process and also is used China, Russia and Brazil; the second is represented by the Galoter Process. The ATP process, used for example in Canada and Queensland, belongs to the solid heat carrier category.
The Kiviter process is suitable for retorting of high-calorific oil shale (over 15% of Fischer assay oil). Besides Estonia, substantial experience in developing and operating vertical retorts for processing oil shale has been also gained in Russia, China, Brazil. The equipment of the Kiviter process is notable by compactness, but the process is connected with the formation of harmful residue-semicoke. The Galoter process is suitable for more fine-grained shales, and uses a horizontal rather than a vertical retort.
The Galoter process has substantial advantages in comparison with the Kiviter process.
· the use of fine-grained (size up to 25mm) and lower quality (calorific value 9.0 MJ/kg) oil shale which
simplifies the mining and fuel preparation processes;
· It has a higher production efficiency (85-90%) and generates gas of higher calorific value;
· the solid residual (ash) is less environmentally hazardous.
At the same time, the Galoter process is associated with more complicated multistage technological scheme and apparatuses. The ATP process, used successfully for processing of oil sands in Canada, is of interest also for the retorting of Estonian oil shale and should be studied more thoroughly. The connection of oil shale retorting by the Galoter process with the Narva power plant in Estonia has the important advantage that it enables the gas generated to be used for both heat and power production,
and the oil generated to be used for starting the boilers.