Process for regeneration of tar reformer catalyst
The invention relates to a catalyst regeneration process for a tar reforming catalyst within a catalyst bed in a tar reformer. The process comprises the steps of:—Admitting a main gas stream with controlled temperature and oxygen content to an inlet into the tar reformer;—Passing the main gas stream through the catalyst bed to form an oxygen depleted gas stream;—Exiting the oxygen depleted gas stream from the tar reformer; and—Recycling at least a part of the oxygen depleted gas stream exiting from the tar reformer back into said main gas stream upstream said tar reformer. The temperature of said main gas stream at the inlet is controlled to be within the range from about 500° C. to about 1000° C.
1. A catalyst regeneration process for a tar reforming catalyst within a catalyst bed in a tar reformer, said process comprising the steps of:
admitting a main gas stream with controlled oxygen content to an inlet into said tar reformer;
passing said main gas stream through said catalyst bed to form an oxygen depleted gas stream;
exiting said oxygen depleted gas stream from said tar reformer; and
recycling at least a part of the oxygen depleted gas stream exiting from said tar reformer back into said main gas stream upstream said tar reformer;
wherein the temperature of said main gas stream at said inlet is controlled to be within the range from about 500° C. to about 1000° C.
2. A catalyst regeneration process according to claim 1 , wherein the temperature of said main gas stream at said inlet is controlled to be in the range between about 500° C. and about 950° C., preferably in the range between about 650° C. and about 950° C., more preferably in the range between about 700° C. and about 900° C.
3. A catalyst regeneration process according to claim 1 , wherein an additional oxidant gas stream with controlled oxygen content is added to the main gas stream and/or is admitted into one or more further inlets into the tar reformer.
4. A catalyst regeneration process according to claim 3 , wherein the tar reformer comprises a plurality of catalyst beds, wherein said additional oxidant gas stream is inlet into the tar reformer downstream at least one catalyst bed.
5. A catalyst regeneration process according to claim 3 , wherein the tar reformer comprises a plurality of catalyst beds, wherein said additional oxidant gas stream is inlet into the tar reformer upstream at least one catalyst bed.
6. A catalyst regeneration process according to claim 1 , wherein the main gas stream to the tar reformer comprises a flue gas resulting from combusting a fuel in a burner, and where said flue gas passes through a biomass gasification unit upstream of the reformer.
7. A catalyst regeneration process according to claim 1 , wherein the main gas stream to the tar reformer comprises a flue gas resulting from combusting a fuel in a burner, and where said flue gas has by-passed a biomass gasification unit.
8. A catalyst regeneration process according to claim 1 , wherein the main gas stream to the tar reformer comprises a flue gas resulting from combusting a fuel in an additional burner.
9. A catalyst regeneration process according to claim 6 , wherein said main gas stream admitted to the tar reformer comprises a flue gas resulting from combusting a fuel containing sulfur in a burner.
10. A catalyst regeneration process according to claim 1 , wherein the tar reformer is a clean tar reformer, the catalyst is a pellet or monolith catalyst and a regeneration gas stream, comprising the main gas stream and the optional additional gas stream, has an oxygen content of maximum 3 vol %.
11. A catalyst regeneration process according to claim 1 , wherein the tar reformer is a dusty tar reformer, the catalyst is a monolith catalyst and a regeneration gas stream, comprising the main gas stream and the optional additional gas stream, has an oxygen content of maximum 3 vol %.
12. A catalyst regeneration process according to claim 1 , wherein said main gas stream has a sulfur content of up to 200 ppmv.
13. A catalyst regeneration process according to claim 1 , wherein the tar reformer is a dusty tar reformer, the catalyst is a monolith catalyst having only a small amount of carbonaceous material deposition, wherein a regeneration gas stream comprising the main gas stream and the optional additional gas stream has an oxygen content in the range from about 9 vol % to about 17 vol %, preferably in the range from about 12 vol % to about 14 vol %.
14. A catalyst regeneration process according to claim 1 , wherein the tar reformer is a dusty tar reformer, the catalyst is a monolith catalyst having only a small amount of carbonaceous material deposition, wherein biomass is combusted in the gasifier during start-up and wherein the flue gas from the combusted biomass is directed through the tar reformer in order to regenerate the catalyst at least partly during start-up of the biomass gasification system.