One Question per Day 20181210

During hot start, the temperatures of the rotor and cylinder metals are high. If vacuum is created first, cold air will enter the cylinder through the shaft seal; since cold air flows downward to the lower cylinder, its temperature drops sharply, resulting in an increased temperature difference between the upper and lower cylinders. This causes the cylinders to deform, leading to friction between the moving and stationary parts. In severe cases, this can prevent the turning gear from functioning properly and cause the main shaft to bend. Therefore, during hot start, steam should be supplied to the shaft seal first, followed by the creation of vacuum

Because the turbine is in a hot state, the temperature of both the rotor and the shaft seal components at the shaft seal area is very high. If vacuum is created without first activating the shaft seal, a large amount of cold air will inevitably be drawn into the cylinder through the shaft seal, causing the rotor in that section to contract rapidly. This leads to significant thermal stress and thermal shock on the rotor, as well as a reduction in the clearances between the axial moving and stationary parts of the blade assemblies in the earlier stages; in severe cases, this can result in friction between these moving and stationary parts. Therefore, when starting a turbine in a hot condition, the shaft seal must be applied first before evacuating the vacuum.

During hot start-up, the temperatures of the rotor and cylinder metals are high; if vacuum is drawn first, cold air will enter the cylinder along the shaft seal. Since cold air flows downward to the lower cylinder, its temperature drops sharply, increasing the temperature difference between the upper and lower cylinders. This causes the cylinders to deform, resulting in friction between the moving and stationary parts. In severe cases, it prevents the turning gear from functioning properly, leading to bending of the main shaft. At the same time, when the turbine is in a hot state, the temperature of the rotor at the shaft seal as well as that of the shaft seal itself is very high. If vacuum is created without first applying the shaft seal, a large amount of cold air will inevitably be drawn into the cylinder through the shaft seal, causing rapid contraction of the rotor in the shaft seal area. One causes significant thermal stress and thermal shock on the rotor; it also leads to a reduction in the clearances between the axial stationary and rotating parts of the earlier stages of blades, and in severe cases, results in friction between these stationary and rotating parts. Therefore, when starting a turbine in a hot condition, the shaft seal must be applied first before evacuating the vacuum.

During hot start, the temperatures of the rotor and cylinder metals are high. If vacuum is drawn first, cold air will enter the cylinder through the shaft seal; since cold air flows downward to the lower cylinder, its temperature drops sharply, increasing the temperature difference between the upper and lower cylinders. This causes the cylinders to deform, resulting in friction between the moving and stationary parts. In severe cases, this can prevent the turning gear from functioning properly and lead to bending of the main shaft. Therefore, during hot start, shaft seal steam should be supplied first, followed by the creation of vacuum.

Because the turbine is in a hot state, the temperature of both the rotor and the shaft seal components at the shaft seal area is very high. If vacuum is created without first activating the shaft seal, a large amount of cold air will inevitably be drawn into the cylinder through the shaft seal, causing the rotor in that section to contract rapidly. This leads to significant thermal stress and thermal shock on the rotor, as well as a reduction in the clearances between the axial moving and stationary parts of the blade assemblies in the earlier stages; in severe cases, this can result in friction between these moving and stationary parts. Therefore, when starting a turbine in a hot condition, the shaft seal must be applied first before evacuating the vacuum.

During hot start, the temperatures of the rotor and cylinder metals are high. If vacuum is drawn first, cold air will enter the cylinder through the shaft seal; since cold air flows downward to the lower cylinder, its temperature drops sharply, increasing the temperature difference between the upper and lower cylinders. This causes the cylinders to deform, resulting in friction between the moving and stationary parts. In severe cases, this can prevent the turning gear from functioning properly and lead to bending of the main shaft. Therefore, during hot start, shaft seal steam should be supplied first, followed by the creation of vacuum.

During hot start, the temperatures of the rotor and cylinder metals are high. If vacuum is drawn first, cold air will enter the cylinder through the shaft seals; since cold air flows downward to the lower cylinder, its temperature drops sharply, increasing the temperature difference between the upper and lower cylinders. This causes the cylinders to deform, leading to friction between the moving and stationary parts. In severe cases, it prevents the barring gear from functioning properly, resulting in bending of the main shaft.

Because the turbine is in a hot state, the temperature of both the rotor and the shaft seal components at the shaft seal area is very high. If vacuum is created without first activating the shaft seal, a large amount of cold air will inevitably be drawn into the cylinder through the shaft seal, causing the rotor in that section to contract rapidly. This leads to significant thermal stress and thermal shock on the rotor, as well as a reduction in the clearances between the axial moving and stationary parts of the blade assemblies in the earlier stages; in severe cases, this can result in friction between these moving and stationary parts. Therefore, when starting a turbine in a hot condition, the shaft seal must be applied first before evacuating the vacuum.

During hot start, the temperatures of the rotor and cylinder metals are high. If vacuum is drawn first, cold air will enter the cylinder through the shaft seal; since cold air flows downward to the lower cylinder, its temperature drops sharply, increasing the temperature difference between the upper and lower cylinders. This causes the cylinders to deform, resulting in friction between the moving and stationary parts. In severe cases, this can prevent the turning gear from functioning properly and lead to bending of the main shaft. Therefore, during hot start, steam should be supplied to the shaft seal first, followed by the creation of vacuum.

During hot start, the temperatures of the rotor and cylinder metals are high. If vacuum is drawn first, cold air will enter the cylinder through the shaft seals, and since cold air flows downward to the lower cylinder, its temperature drops sharply. This increases the temperature difference between the upper and lower cylinders, causing the cylinders to deform and resulting in friction between the moving and stationary parts. In severe cases, this can prevent the turning gear from functioning properly and lead to bending of the main shaft. Therefore, during hot start, steam should be supplied to the shaft seals first, followed by the creation of vacuum.