Method for the hydroprocessing of renewable feeds
In a method for the hydroprocessing of renewable feeds in a hydroprocessing unit (unit A), comprising the use of sour waste water from the same or another unit (unit B), which is processing feeds containing sulfur and nitrogen, as wash water in unit A, thereby changing the pH of the waste water from unit A to lower the risk of carbonic acid corrosion of corrodible steel parts in unit A, the renewable material in unit A is directed to contact a material that is catalytically active in hydrogenating the renewable material in the presence of hydrogen, and the effluent is combined with the wash water stream which contains hydrogen sulfide and/or ammonia.
1. A method for the hydroprocessing of renewable feeds in a hydroprocessing unit (unit A), said method comprising:
using sour waste water from another unit (unit B), which is processing feeds containing sulfur and nitrogen, as wash water in the unit A, thereby changing a pH of waste water from the unit A to lower the risk of carbonic acid corrosion of corrodible steel parts in the unit A,
wherein the renewable feeds in the unit A is directed to contact a material that is catalytically active in hydrogenating the renewable feeds in the presence of hydrogen and the wash water, and an effluent from the unit A is combined with the wash water, which contains hydrogen sulfide and ammonia, and wherein the unit B, which is processing feeds containing sulfur and nitrogen and produces the sour waste water, is a hydroprocessing unit treating petroleum-based feeds.
2. The method according to claim 1 , wherein chemicals containing nitrogen and/or sulfur are injected into the wash water to control the pH thereof.
3. The method according to claim 2 , wherein ammonia is injected into the wash water.
4. The method according to claim 1 , wherein the pH of the waste water from the unit A is raised to a value of 7.0 or above.
5. The method according to claim 4 , wherein the pH of the waste water from the unit A is raised to a value of 8.0 or above.
6. The method according to claim 1 , wherein the sour waste water contains more than 100 ppm hydrogen sulfide.
7. The method according to claim 1 , wherein the sour waste water contains more than 100 ppm ammonia.
8. The method according to claim 1 , wherein the wash water which contains hydrogen sulfide and ammonia creates an iron sulfide film capable of protecting the surface of carbon steel in at least one of the hydroprocessing units.