How to maintain operation without surge as much as possible when the steam pressure difference of the turbine is low
Thread Content
The steam pressure of the unit fluctuates, and the pressure difference is always too low, resulting in turbine surge. How to prevent surging without lowering the steam backpressure by turning down the exhaust valve? When the medium-pressure is low, the press increases the electro-hydraulic opening in order to continue operating; this causes the low-pressure steam pressure to rise, resulting in an even smaller pressure difference, which in turn prompts an further increase in the electro-hydraulic opening. In this vicious cycle, the pressure difference becomes increasingly small, leading to compressor surge. Sometimes, in order to reduce the electro-hydraulic opening, the turbine speed is lowered, and reverse swing is avoided as much as possible. I wonder if this will work? Is there any other better way? :dizzy: Headache
Reducing the speed means lowering the power output of the turbine; with a lower compressor flow rate, surge naturally occurs. The process conditions do not meet the objective requirements of the equipment, so only the process conditions can be changed.
It must be addressed at the source, that is, by solving the problem of insufficient total steam supply. This can be achieved by increasing the amount of steam available, which means boosting the boiler’s production capacity and maintaining stable pressure； Alternatively, reduce the steam consumption in other areas, minimize unreasonable emissions at the installation site, improve pipeline insulation, and reduce heat losses.
Reducing the speed lowers the inlet flow rate, which is naturally one of the causes of surge. However, as mentioned earlier, when the pressure of the medium-pressure steam is low, the pressure difference becomes too small, which causes the electro-hydraulic opening of the valve to increase. As this opening increases, more medium-pressure steam enters the turbine and turns into low-pressure steam. Therefore, the medium pressure will continue to decrease, while the low pressure will continue to increase. This creates a vicious cycle. To break this cycle, two approaches can be taken: one is to increase the steam pressure difference, that is, to raise the medium pressure or lower the low pressure. Increasing the work that steam can do reduces the electro-hydraulic opening, turning a vicious cycle into a virtuous one. That is, the electro-hydraulic opening decreases, and less medium pressure turns into low pressure. The medium voltage naturally increases. The low pressure naturally decreases. The press does not stall. Secondly, before the compressor experiences surge, reduce the amount of steam required by the compressor; this will in turn lead to a decrease in the electro-hydraulic opening. That is, reduce the compressor speed to prevent the vicious cycle from worsening further. In my personal view, I hope for critical education. The problem now is that the elasticity adjustment using the second method is particularly low. It might even worsen the situation, causing the press to surge more rapidly; I wonder if there are any other solutions. Or the second method is wrong in itself. Hope for guidance. Thank you!
The best solution in such a situation is of course to address the problem at its source, but this requires time as well as the cooperation of other workshops. Of course, it is hoped to adjust the press using one’s own methods. It can’t be that every time this happens, the entire factory has to be mobilized. The press still requires its own operating methods. Hope for guidance
How large are the fluctuations in steam pressure, and why do they occur? All of these require finding the reasons and addressing them urgently. Steam serves as the power source for steam turbines, and stable pressure is an essential process condition! Unless the root cause is addressed, trying to find solutions unilaterally from the compressor side often leads to the situation described by the original poster: the more busy things get, the more chaotic it becomes, and the more chaotic it is, the busier things get; at a certain point, an accidental action might trigger other problems. To identify the cause of steam pressure fluctuations, one can examine the following aspects: the trend in pressure and flow rates in the medium-pressure steam main during compressor surge, the trend in pressure and flow rates of the steam at the compressor inlet, the trend in pressure and flow rates of the steam backpressure, and the trend in pressure and flow rates of steam in other major steam-consuming units. By viewing these trend charts on a single operation panel, it is possible to determine the root cause of the steam pressure fluctuations. Possible reasons include 1. Unstable steam production by the boiler ； 2. There is a problem with the PID settings of the control valve for a certain medium-pressure steam user, resulting in excessive periodic variations in the valve’s opening and closing range ； 3. Fluctuations in the operations of low-pressure steam users cause periodic changes in the compressor back pressure......
Are you referring to surge in steam turbines or compressors? It’s all confusing me?