Thermal Processing

 

Horizontal  retorting for oil production, the current market benchmark, utilising the  Galoter methodology, has been proven and refined over the last 50 years of continuous operation in Estonia.

 

Feedstock benefitiation (KEROCON) will significantly improve the efficiency of classical retorting technology. As the GOS aim to develop large scale projects globally, shale oil upgrade and refining will be economicaly viable.

 

Oil shale feedstock beneficiation (KEROCON) will significantly improve the efficiency of horizontal retorting technology by a factor of 2-3 times. This will allow oil shale projects to realise appropriate scalability, allowing GOS  to develop large scale projects globally producing shale oil products, LPG gas, electricity and value added by-products.

 

The  Galoter technology based horizontal retort plant is, by our analysis, one of the most efficient and cost-effective off the shelf technology available for oil shale processing. The oil shale heated in horizontal retort to 500°C, in the absence of oxygen, and the oil vapours condensed.

 

At present,  three Galoter based plants are in operation in Estonia. Two of them were built in 1980 and have operated continuously at a  high level of reliability and efficiency during operating period. In 2009 the new Galoter technology based plant (Petroter) was constructed and commissioned for operation in the town of Kohtla-Jarve (Estonia) with high levels of efficiency and low harmful emmissions.

 

GOS with partners develops further improvements to the Galoter process to make it more efficient and environmentally friendly.

 

 

 

Circulating Fluidised Bed (CFB) combustion for power production. A technology review reveals that Circulating Fluidised Bed has been developed to a state of the art technology.

Keravan Biovoimalaitos Power plants based on CFB are considered as matured technology for small to medium size units. Several investigations and tests for direct oil shale combustion in CFB plants have been executed in the past and some large scale applications are in successful operation. CFB boilers are the most suitable concept for direct combustion of oil shale.

 

Core of the process is a fluidised bed combustor, the CFB-Reactor, in which the crushed fuel is suspended in an upward flow of combustion air and fine particles. Within the reactor a high turbulence is achieved by a very high slip velocity and internal recirculation of solids. This results in high heat and mass transfer rates culminating in very good combustion conditions.

 

In contracts to a conventional burner flame the temperature in the whole CFB system is kept at a very even level, which is the combustion temperature of about 850 °C. This is achieved by immediate transfer of heat and by external circulation of fine grained fluid bed material, which is discharged at the top of the furnace and recycled via the recycling cyclone/-s and a pressure seal back into the furnace. Fuel particles being entrained together with the circulating bed material are fed back to the combustion zone, consequently extending the retention time until the fuel is almost completely burnt. Split level primary and secondary combustion air injection and the high retention time of the fuel in the furnace support the very high incineration efficiency.

 

Primary combustion under reducing conditions with following secondary combustion under oxidising conditions with an even temperature in the furnace minimise NOX formation.

 

Carbon-monoxide formation is also suppressed by adjustment of above mentioned process parameters. Surplus sulphur dioxide (SO2) in the flue gas is captured by fine grained limestone which typically is directly injected into the furnace and in the case of Tarfaya Oil Shale in included in situ in the raw material. The limestone is burnt to lime under prevailing conditions. The produced lime is very reactive thus catching SO2 as gypsum and in turn cleaning the flue gas of it (in-situ desulphurisation).

 

The flue gas passes through a normal bag house or electrostatic precipitator for removal of fine particulates before being led to the atmosphere. Add-on flue gas desulphurisation and/or De-NOx systems are generally not required.