CATALYST THERMAL REGENERATION BY EXHAUST GAS

Abstract

Method and system for thermal regeneration of a catalyst by inlet turbine exhaust gas from a diesel engine, where a gas split stream (08) is led from the engine exhaust (02) through an eductor (04) and further to regeneration of a catalyst, wherein a cold air stream (09) is used to keep the regeneration gas stream at a desired constant temperature range.

Claims

1. System for thermal regeneration of a catalyzed soot filter in an engine exhaust gas cleaning unit comprising one or more exhaust gas pipes connected to turbine of a turbocharger; an eductor comprising a motive inlet, a suction inlet and an outlet; one or more exhaust gas split stream pipes connecting the one or more exhaust gas pipes upstream the turbine of the turbocharger with the motive inlet of the eductor; an air pipe connected to the suction inlet of the eductor; a flow regulation valve mounted in the air pipe; and an eductor outlet pipe connecting the eductor outlet with the catalysed soot filter.

2. System for thermal regeneration of a catalyzed soot filter in an engine exhaust gas cleaning unit according to claim 1, wherein the flow regulation valve is adapted to regulate the amount of air sucked into the eductor to achieve a constant temperature range of the gas exiting the eductor.

3. System for thermal regeneration of a catalyzed soot filter in an engine exhaust gas cleaning unit according to claim 2, wherein the temperature range is 380° C.-500° C.

4. System for thermal regeneration of a catalyzed soot filter in an engine exhaust gas cleaning unit according to any of the preceding claims, wherein the catalyzed soot filter is a compact combined DPF filter.

5. System for thermal regeneration of a catalyzed soot filter in an engine exhaust gas cleaning unit according to claim 1, wherein the engine is marine diesel engine.

6. System for thermal regeneration of a catalyzed soot filter in an engine exhaust gas cleaning unit according to claim 1, further comprising regulating valve arranged in the one or more exhaust gas split stream pipes adapted to open, shut or regulate the exhaust gas flow to the motive inlet of the eductor.

7. System for thermal regeneration of a catalyzed soot filter in an engine exhaust gas cleaning unit according to claim 1, wherein the exhaust gas from the engine has a temperature of 400° C.-520° C.

8. System for thermal regeneration of a catalyzed soot filter in an engine exhaust gas cleaning unit according to claim 1, wherein the exhaust gas from the engine has a pressure of 1-2.5 barg.

9. Method for controlled thermal regeneration of a catalysed soot filter in an engine exhaust gas cleaning unit with a mixture of exhaust gas and ambient air at a predetermined set point temperature, comprising the steps of providing a pressurized exhaust gas split stream from an upstream turbocharger; passing the pressurized split stream at exhaust gas temperature to into a motive inlet of an eductor and drawing lower pressure, ambient air at a temperature lower than the exhaust gas temperature through suction inlet of the eductor; controlling the amount of ambient air drawn through the suction inlet of the eductor to obtain the predetermined set point temperature; and contacting the thus obtained exhaust gas air mixture with the catalysed soot filter for a time sufficient for soot regeneration of the filter.

10. Method for controlled thermal regeneration of a catalysed soot filter in an engine exhaust gas cleaning unit with a mixture of exhaust gas and ambient air at a predetermined set point temperature according to claim 9, wherein the set point temperature is in the range of 380° C.-500° C.

11. Method for controlled thermal regeneration of a catalysed soot filter in an engine exhaust gas cleaning unit with a mixture of exhaust gas and ambient air at a predetermined set point temperature according to claim 9, wherein the catalyzed soot filter is a compact combined DPF filter.

12. Method for controlled thermal regeneration of a catalysed soot filter in an engine exhaust gas cleaning unit with a mixture of exhaust gas and ambient air at a predetermined set point temperature according to claim 9, wherein the engine is marine diesel engine.

13. Method for controlled thermal regeneration of a catalysed soot filter in an engine exhaust gas cleaning unit with a mixture of exhaust gas and ambient air at a predetermined set point temperature according to claim 9, further comprising regulating valve arranged in the one or more exhaust gas split stream pipes adapted to open, shut or regulate the exhaust gas flow to the motive inlet of the eductor.

14. Method for controlled thermal regeneration of a catalysed soot filter in an engine exhaust gas cleaning unit with a mixture of exhaust gas and ambient air at a predetermined set point temperature according to claim 9, wherein the exhaust gas from the engine has a temperature of 400° C.-520° C.

15. Method for controlled thermal regeneration of a catalysed soot filter in an engine exhaust gas cleaning unit with a mixture of exhaust gas and ambient air at a predetermined set point temperature according to claim 9, wherein the exhaust gas from the engine has a pressure of 1-2.5 barg.

Description

DESCRIPTION OF THE DRAWING

[0035] A more detailed description of the method and system will be apparent from the following description of a specific embodiment with reference to the drawing in which

[0036] FIG. 1 shows the catalyst thermal regeneration system 01 according to an embodiment of the invention. Two exhaust gas pipes 02 connect the diesel engine exhaust gas header with the two turbo charger turbines 03. A part of the exhaust gas is spilled from the exhaust gas pipes to the eductor 04 through the exhaust gas split stream pipes 08. This exhaust gas split stream is connected to the eductor motive inlet 05 through an exhaust gas regulation valve 12, which is adapted to adjust the flow of the gas split stream according to the need of regeneration of the catalyst (not shown). The gas split stream may be a pulse stream, which is only connected to the catalyst during regeneration periods divided by operation periods without regeneration. When passing through the eductor, the exhaust gas split stream is capable of sucking in a stream of ambient (colder) air from the air pipe 09 through the eductor suction inlet 06 because of the gas expansion in the eductor.

[0037] The combined stream comprising the exhaust gas split stream and an amount of cold air exits the eductor through the eductor outlet 07 and is led to the catalyst to be regenerated by the eductor outlet pipe 11. The temperature of the combined stream is able to be kept in a desired constant range despite the variation of the exhaust gas temperature due to the presence of the flow regulation valve 10 located in the air pipe. The flow regulation valve is adapted to adjust the amount of colder ambient air relative to the exhaust gas split stream, thereby keeping the combined gas stream at a constant temperature range.

EXAMPLE

[0038] In a catalyst thermal regeneration system, the exhaust gas from a diesel engine has a pressure of 1-2.5 barg and a temperature of 400-520° C. according to the engine load.

[0039] The flow regulation valve modulates and adjusts the flow (suction) of colder ambient air in order to keep the temperature of the combined gas stream after the eductor in the range of 380-500° C. suited for regeneration of a catalyst.