What is the difference between a vacuum breakdown shutdown of a gas turbine and a shutdown triggered by a crisis safety device?

Vacuum breakage occurs when the vacuum reaches a certain threshold value, causing the system to stop; whereas a crisis safety device brings about a stop by shutting off the power supply, which in turn closes the valves driven by steam. Most emergency stops are caused by situations such as overspeed, failure of the threshold value mechanism, or malfunctions in electrical instruments. These stop mechanisms operate on different principles and are mandatory in nature; they are also known as mechanical stops.

Isn’t there also a manual vacuum-breaking shutdown?

If the machine is shut down just because of a vacuum break, that is an error in operation; check your operation manual.

The book explains it as follows: First, it states the situations in which an emergency shutdown is required: 1. The speed of the turbine exceeds the operating range of the critical safety device, thereby putting at risk the failure of that safety device to function； 2. The axial displacement or expansion difference of the turbine rotor exceeds the specified values·············12. When the pressure in pressure vessels such as heaters and deaerators exceeds the limit values and cannot be reduced, or when the pressure vessel ruptures or leaks. Next is the procedure to follow in case of an emergency shutdown: 1. Manually activate the safety device to cause the automatic main steam valve, control valves, and exhaust check valves to close quickly, thereby blocking all steam pathways to the turbine, and verify that these valves are properly closed··············6. Report the incident to the relevant departments. Finally, there are situations in which it is necessary to break the vacuum for an emergency shutdown: 1. The unit suddenly experiences severe vibration and cannot eliminate it ； 2. The turbine speed has exceeded the limit value, yet the emergency protector does not activate ； 3. Metal noises occurring inside the unit ； 4. In the event of water impact ； 5. If oil supply is cut off to any bearing of the unit, smoke is emitted from it, or the oil temperature at the bearing outlet rises sharply above 70°C········11. When the lubricating oil pressure drops below the critical value and fails to return to normal levels even after the auxiliary oil pump is started

This post was last edited by Li Yi on 2018-2-2 at 16:17. What I understand is that stopping the machine by breaking the vacuum and stopping it by applying the brake are used in different situations, but what are the reasons for choosing one method over the other? What’s the difference? I hope you will kindly offer your guidance

This post was last edited by Li Yi on 2018-2-2 at 16:16. What I understand is that stopping the machine by breaking the vacuum and stopping it by applying the brake are used in different situations; but what are the reasons for choosing one method over the other? What’s the difference? I hope you will kindly offer your guidance

Vacuum breakdown shutdown is an emergency shutdown under normal conditions; it only affects the liquid level in the vacuum cooler, as well as causing vibrations and displacement. It’s possible that your compressor doesn’t have any other interlock protection devices. As for the shutdown triggered by a safety device, it occurs when the situation gets out of control – in this case, the oil supply is cut off, meaning the compressor no longer receives oil for lubrication. What effects might occur if a vacuum breakdown shutdown fails to actually break the vacuum? Negative pressure will result, and what are the consequences of that? Think about it by yourself. There is still a difference between the two.

It seems you’re not very familiar with compressors yet – have you only just started working in this role?

Turbine! I wasn’t at the scene and don’t understand turbines

The last edit to this post was made by Li Yi on 2018-2-2 at 19:41. In simple terms, the condition that triggers an emergency shutdown to break the vacuum means that our turbine can no longer rotate, and it must be stopped immediately. Therefore, we employ a vacuum-breaking emergency shutdown to reduce the coasting time, allowing the turbine to stop as quickly as possible in order to minimize the impact of the fault. A vacuum loss shutdown that does not cause damage refers to a failure in the turbine and its associated systems that prevents the unit from operating properly, but it does not pose a significant threat to the safety of the main machine; in other words, the turbine can still rotate, so it is possible to reduce the load rapidly and then shut down the machine following the normal shutdown procedures for vacuum loss