External heat exchanger storage capacity
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Why, at low load levels, does the external heat exchanger have a high storage capacity at low temperatures and a low storage capacity at high temperatures? Is this related to the heat extraction process in the cycle? Does this phenomenon occur at high load levels as well? Last edited by chengkang on 2009-4-11 14:06.]
What do you mean? Could you explain it more clearly? I can’t understand it
At low load, heat is generally not extracted; the catalyst in the external heat exchanger remains almost unfloated and has a high bulk density, resulting in a high apparent reserve and a low temperature. As the heat extraction load increases, the temperature rises, and the storage amount first increases and then decreases. Because the reserve is related to the pressure difference.
This is quite simple: the temperature of the regenerator is definitely higher than the temperature of the external heat source. With a low circulation rate and fewer heat sources, the temperature is low; conversely, with a high circulation rate and more heat sources, the temperature is high. Last edited by chengkang on 2009-4-11 14:34.]
At low load, the external extraction slide valve is closed, resulting in a lower catalyst circulation rate in the external heat exchanger; consequently, the catalyst spends more time in the external heat exchanger, and thus the temperature is lower. I disagree with the opinion from the third floor!~ What do you mean by no fluidization? That’s not correct – the fluidization state in the external section is related to the fluidization air used there, and not so much to the load.
Because at low load, the circulation volume is small, the bulk density of the catalyst is low, and the residence time of the catalyst is long, resulting in a lower temperature. At high load, the circulation volume of the catalyst is large, it is in a fluidized state, the bulk density is low, the residence time is short, and the heat transfer time is short, leading to a higher temperature; however, due to the large circulation volume of the catalyst, the total amount of heat absorbed is high. The greater the load, the higher the circulation rate, the higher the external heat extraction temperature, the greater the heat intensity, and the greater the steam production.
It might be that the fluidization of your external heat exchanger isn’t optimal
When the external heat storage capacity is high, but the circulation volume of heat extraction is low, the amount of heat extracted is small and the temperature is low. When the external heat storage capacity is low, but the circulation volume is high, the amount of heat extracted is greater and the temperature is high.
The external heat absorption load is low, so the air flow rate for ventilation is reduced; the flow rate of the catalyst used for external heat absorption is also low. The density of the catalyst inside is high, which results in a high storage capacity. At the same time, due to the low catalyst flow rate, there is a longer contact time with the external heat absorption tubes, leading to a lower temperature inside those tubes. And vice versa