How does the leak detection device for the descent tube of a space furnace work?

Does the downcomer also have a side leakage device? I’ve heard of it for the first time. I’m not familiar with the technology used in space furnaces, but I am aware of GE’s coal water slurry gasification process. GE’s downcomers do not have any leakage prevention devices; the most obvious sign of leakage in such downcomers is an abnormally high temperature at the process gas outlet. Do space furnaces’ downcomers have such leakage prevention devices? I hope the guy from the space furnace can come and share some knowledge with us. Thanks! Looking forward to the answer!

It’s quite simple: rows of tubes are arranged around the outside of the downcomer. One end of each tube is sealed, while the other end leads outside the furnace and is connected to a small buffer tank known as the vaporizer auxiliary tank. Before starting up the gasification furnace, the pressure in the buffer tank is raised to around 5.0 MPa; then the discharge valve is closed, forcing the gas to remain inside the pipelines and tanks. If the pressure in the tank drops rapidly during operation of the gasification furnace (excluding natural leaks), it indicates that the downcomer and the coil wrapped around its outside may have been burned through. This is the principle behind leak detection.

Thank you very much. Nitrogen is probably used inside the tubes as well; I used to think that water was used for leak testing. The gas rushing inside turns into dead gas over time; can this exhaust pipe withstand the high temperature of the hot syngas? Have there been any false alarms during actual operation?

The leak detection device functions as a \"fuse\". The structure is as described on the third floor: it is a thin tube coiled around the outer wall of the downcomer. Its most prominent feature is that the wall thickness is relatively thin. Under normal operating conditions, the inner wall of the downcomer is protected by a water film formed due to the spraying from the quenching ring; as a result, although the temperatures of the synthesis gases, fly ash, and slag can reach 1500 degrees Celsius, the temperature of the inner wall of the downcomer remains around 210 degrees Celsius thanks to this continuous water film barrier. However, if the cooling ring spray is uneven and as a result the water film does not cover the inner wall of the tube completely, the high-temperature syngas will come into direct contact with the inner wall of the downcomer, causing its temperature to rise rapidly to the point where it burns out or is damaged. Since the downcomer and quench ring are located inside the quench chamber, it is not possible to monitor their operating conditions under normal circumstances; therefore, this safety device has been added to the latest design. Because the wall of the tube is very thin, once hot gas and solids come into direct contact with the wall of the downcomer, the leak detection tube will burn through first, causing the pressure inside the tube to drop and triggering an alarm. Remind the operator to pay attention.

Thank you very much for your answer: handshake. What is the typical operating pressure range for this? The pressure should be slightly higher than that of the vaporization furnace, I guess. Also, is it necessary to keep the pressure within a certain range at all times under normal conditions? It doesn’t seem that there are control valves on the flow diagram for adjusting the pressure; rather, it must be controlled manually using hand valves on site.

There is such a design, but it’s not available in Linquan Phase 1; actually, this design is really unnecessary. GE has the synthesizer outlet temperature, and that’s sufficient.