Issues with starting and stopping turbines

Static testing of the turbine unit! Most systems have a simulated driving program! Debug it following this procedure, and then drive the car for real!

Of course, we can’t keep manually switching the control valves

You can first conduct speed-over-limit tests, and then carry out some interlock tests; this way there will be no need to worry

Who has animated diagrams of the working principles of compressors and turbines? Please share them, thanks

May I ask the seniors what the purpose of the dry gas seal in compressors is? How is it sealed?

Back to upstairs: The principle of dry gas seals. I. A dry gas seal is a non-contact end-face seal that seals off all process pressures. The seal consists of an axially floating carbide ring – the stationary ring, and a rotating ring – the moving ring. The outer diameter of the sealing surface of the rotating ring is provided with grooves, and beneath these grooves lies a smooth area known as the seal dam. When the shaft is at rest and the unit is not under voltage, the spring behind the stationary ring causes it to make contact with the rotating ring. As the unit increases pressure, the static pressure generated by the gas causes the two rings to separate, forming a very thin gas film (about 3 μm). This gap allows a small amount of sealing gas to leak out. When the unit begins to rotate, the grooves on the rotating ring pump gas toward the seal barrier, causing the pressure within the grooves to increase from the outer diameter toward the inner diameter. A high-pressure area is formed near the root of the grooves, which widens the gap between the two rings; at the same time, the leakage amount also increases. When the spring force and the static pressure of the gas are equal to the hydrodynamic forces of the groove and the sealing dam, a stable gas film gap is formed between the sealing surfaces. As the gap decreases, hydrodynamic effects cause the separation force between the end faces to increase rapidly, causing the gap to widen. An increase in the gap will lead to a decrease in the opening force, and the gap will decrease. The automatic balancing principle of dry gas seals ensures a stable gap and leakage rate between the sealing surfaces. When the shaft rotates, the sealing surfaces do not come into contact, so there is no wear. II. As the name implies, a dry gas seal refers to a seal that uses dry and clean gas. During operation, there is a very small gap between the sealing surfaces of the dry gas seal, and the sealing gas flows through this gap. The small gaps between the sealing surfaces require that the sealing gas contain no particles with a diameter larger than those gaps, nor any liquids. The dry gas seal control unit is characterized by having filtering devices and dehumidification units (when process media is used as the sealing gas), thereby providing gas of high purity to extend the lifespan of the sealing surfaces and prevent the accumulation of contaminants on the back side of the stationary ring. Sealing gas is divided into main sealing gas and isolation gas (buffer gas). The design pressure of the dry gas seal is the inlet pressure of the unit. The pressure in the main seal intake chamber is slightly higher than the intake pressure, ensuring a clean environment within the seal chamber. Due to the pressure difference between the sealed chamber and the process gas chamber, in a series configuration, most of the sealed air flow that has been dehumidified and filtered enters the compressor through the process gas path; only a small portion of this sealed air flow passes between the sealing surfaces and becomes leakage gas ； In the case of a parallel double-end face seal, the sealing air flow passes between the two sealing surfaces, becoming leakage gas. The main sealing gas in a series-connected structure is further divided into primary main sealing gas (on the inner end face) and secondary main sealing gas (on the outer end face). The inner end face provides the primary sealing function, while the outer end face serves as a safety seal; in the event that the primary seal on the inside fails suddenly, hazardous materials will not leak out in large quantities, thereby preventing safety accidents. The primary seal gas for level 1 can be either the process medium or nitrogen, while the primary seal gas for level 2 can only be an inert gas (nitrogen).

Is the primary seal used to seal process gas or oil? What is the secondary seal used to seal?

A trial run must be conducted before operation, critical speed

The primary seal is used to prevent process gas from leaking into the compressor’s primary seal chamber, thereby avoiding contamination of the seal surfaces; it is typically filled with high-pressure nitrogen or process gas. The secondary seal prevents leakage from the primary seal into the secondary seal chamber, where it mixes with the gas from the primary seal and is sent to the flare; low-pressure nitrogen is generally used for this purpose. A balanced gas seal is used to prevent oil from entering the sealing chamber; low-pressure nitrogen passed through a pressure valve is generally employed for this purpose.

I really learned something here; thank you. Keep learning every day* and making progress day by day! :):):):):):):):):)