Pressure after the first stage exhaust of the turbine

The pressure after the first stage of exhaust refers to the exhaust pressure after the first stage of expansion in the turbine is complete, and the steam has done work through the first-stage impeller. In a fully condensed steam turbine, this pressure is usually close to or equal to the pressure inside the condenser ； In a extraction steam turbine, the pressure after the first stage of exhaust may be higher than the condenser pressure, as the steam may be extracted for use in other processes before being discharged. The magnitude of this pressure can be used to monitor and adjust the operating condition of the turbine. .

This post was last edited by shijiazhuang on 2024-2-1 at 11:37. The primary pressure you mentioned should be the pressure between stage 7, which is the impulse stage, and stage 8; this pressure is generally referred to as the wheel chamber pressure. What is the wheel chamber pressure in a turbine? There are pressure gauges on site that display this pressure – what does its level indicate? 1. The backpressure value is determined based on the design of the unit; it can be found by looking at the model. The wheel chamber pressure is the pressure behind the first-stage impeller of the turbine. 2. The first-stage impeller of a turbine is usually of the impulse type, and the wheel chamber pressure corresponds to the pressure after this first stage. High wheel chamber pressure is usually caused by factors such as fouling at the rear. 3. The level of pressure in the wheel chamber indicates the amount of thermal energy and kinetic energy of the steam within the turbine that is converted into mechanical energy of the rotor. High wheel chamber pressure indicates turbine fouling, and the steam does not do work. The pressure level in the wheel chamber has its designated value, which is determined by the steam pressures at its inlet and outlet. 4. The wheel chamber pressure of a turbine refers to the pressure after the control stage; a high pressure indicates scaling in the turbine, which reduces its efficiency and prevents the steam’s energy from being effectively converted into mechanical energy. At the beginning of operation, the pressure in our turbine was 1.8 MPa, and it increased to 2.5 MPa as operations progressed. Slight fluctuations in steam pressure can cause the rotation speeds to become out of sync. During maintenance, after disassembly, it was found that the turbine blades were severely scaled. 5. The so-called wheel chamber pressure is simply a measure of the pressure of the steam that has done work in the regulating stage; it can indicate whether there is blockage in the flow channels of the blades, as well as whether there is significant leakage in the inter-stage seals. During maintenance, these blades as well as the clearances between moving and stationary parts are definitely the key areas to focus on. 6. Turbine chamber pressure is used to monitor the operating conditions of the turbine and those of the flow passage components. After scaling occurs in the flow passage, the wheel chamber pressure will increase under the same steam inlet conditions and steam flow rate. After the turbine is put into normal operation, and provided that the flow path is clean, the relationship between the wheel chamber pressure P1 and the new steam flow rate as well as other parameters is measured ； During subsequent operations, the wheel chamber pressure P2 under the same steam flow rate and parameters is measured, and the obtained data is compared with it. The relative increase in chamber pressure is calculated using the formula P=(P2-P1)/P1*100%; P should not exceed 10%, and if it does, cleaning is necessary. By monitoring the drum pressure, the maximum steam flow can be limited to prevent overload. 7. The gradual increase in drum pressure indicates that the steam passages (nozzles and impellers) are narrowing due to the accumulation of impurities from the boiler. The accumulation of scale leads to a decrease in efficiency and capacity; in extreme cases, the impeller, partitions, cylinders, and thrust bearings can be damaged due to excessive stress. Typically, manufacturers will specify a maximum wheel chamber pressure.

Typically, manufacturers will specify a maximum wheel chamber pressure. But this figure isn’t mentioned in the information we provided