OLGA process philosophy
Product gas contains solids, tars and inorganic impurities. It is very important to consider the logical order for cleaning the product gas. In principle mixing of dust, tar and water must be avoided. In any case it must be avoided to mix tar & water!
The philosophy of OLGA is based on dew point control. In the figure below the tar and water dew points are shown, together with the logical process steps.
Logical equipment with typical temperatures:
- Product gas cooler; gasifier exit 700-900 ºC– OLGA inlet 380 ºC
- Separation of solids; 380 ºC , solid removal choice
- removal of coarse solids by a cyclone (and OLGA for fine solid aerosols)
- removal of all solids by a hot gas filter - OLGA tar separation; inlet 380 ºC outlet 70-90 ºC (safe above water dew point)
- Water condenser; 70-90 ºC to 30 ºC
- Water scrubber; 30 ºC
Key philosophy
OLGA operates above the water dew point, but reduces the tar dew point to a level under the lowest process temperature. Tar & water are not mixed!
Principle of OLGA
The tar removal principle of OLGA is based on a multiple stage scrubber in which, the gas is cleaned by special scrubbing oil. In the first section of OLGA (the collector) the gas is gently cooled down by the scrubbing oil. Heavy tar particles condense and are collected, after which they are separated from the scrubbing oil and can be recycled to the gasifier, together with a small bleed.
In the second stage (the absorber / stripper) lighter gaseous tars are absorbed by the scrubbing oil. Both stages are presented as separate columns in underneath process sketch. In the absorber column the scrubbing oil is saturated by these light tars. This saturated oil is regenerated in a stripper. In case of an air or steam blown gasifier hot air is used to strip the tars of the scrubbing oil. This air loaded with light tars can be used as gasifying medium in the gasifier. Hence, the stripper column design is not only based on the tar removal capacity but also on the amount of air that can be used by the gasifier. All heavy and light tars can be recycled to the gasifier where they are destructed and contribute to the energy efficiency. Tar waste streams are efficiently recycled this way.
Summarised advantages of OLGA
The OLGA system is a reliable and solid solution for the tar problem. The advantages can be summarised as follows:
- No more tar related problems
- Increased system stability and availability
- Minimisation of waste water treatment costs
- No tar waste streams - Better gas quality compared to a thermal tar cracker
- More reliable and less vulnerable than a catalytic tar cracker
- No poisoned waste water; the problem of tar removal by a water scrubber systems
Contact person: Jan-Willem Könemann, +31-10-5991114
