Is the slurry pipeline depressurized after the gasifier is shut down?
Thread Content
This post was last edited by lflsedin on 2015-6-10 22:03. How to relieve pressure from the coal slurry pipeline and the gasifier after shutting down the gasifier? ?
After the gasifier is shut down, the slurry pipeline should be kept under pressure to prevent any leakage; the pressure in this pipeline should only be released after the pressure in the gasifier has dropped. It is recommended to use a dedicated pressure-release line for this purpose, allowing for manual control of the rate of pressure release. If the pressure in the coal slurry pipeline is released while the gasifier is under pressure, the burner valve and check valve will be subjected to pressure on one side only; in the event that the seal is not adequate, high-temperature gases can damage the coal slurry pipeline, which is not worth the consequences.
This is the most basic requirement – it should be included in both the operation tickets and the operating procedures for your coal slurry pipeline flushing system.
After the gasifier is shut down, blind flanges must be installed on the coal slurry pipeline, and the pipeline should be flushed after that.
With three valves for isolation, pressure relief should be possible. Otherwise, how can four nozzles be used for pressurized continuous feeding?
After the gasification furnace is shut down, there are generally two methods for releasing pressure from the slurry pipeline. The method we commonly use is to release pressure by backwashing at the outlet of the high-pressure slurry pump. If backwashing at the outlet becomes blocked, it is also possible to open the slurry circulation valve to release pressure; however, since a flow control orifice plate is installed after the slurry circulation valve, blockages can occur there as well. It is best to release pressure at the outlet of the slurry pump. To prevent blockages in the slurry pipeline, it is recommended to release pressure and flush it within 30 minutes.
The gasifier controls the pressure release rate through the flare vent valve to carry out pressure relief； After the pressure relief of the gasifier and the oxygen pipeline is completed, open the slurry pressure relief line at the burner; the control room then opens the slurry cut-off valve to relieve pressure in the slurry pipeline.
As I recall, with the SIS safety system in place, opening the slurry circulation valve requires the oxygen pipeline to be depressurized first
Generally, both the coal slurry pipelines and oxygen pipelines are equipped with nitrogen plugs; when the gasifier is shut down, these nitrogen plugs activate to cut off the coal slurry pipelines and the gasifier. The pressure in the nitrogen seal must be higher than the normal operating pressure of the vaporizer.