What is the cycle rate?
Thread Content
What is the cycle rate? What does it mean,? What’s the use? Should it be bigger, better, or smaller? Image below: (Injuries sustained at work, sharing for reference)
The ratio of the circulating water volume entering the rising tube to the steam volume at its outlet. Due to the salt deposition on the water wall of high and medium pressure boilers, the circulation ratio must be sufficiently high. At subcritical pressure, the minimum cycle rate should be limited to avoid film boiling. The circulation ratio is related to the structure of the circulation system and the heating intensity of the riser. Under fixed conditions of the cross-sectional ratio between the downcomer and the upcomer and the structure, as the heat load increases, the circulation flow rate rises initially, and the circulation ratio also increases, demonstrating a self-compensating capability ； But at a certain point, if the heat load increases further, the circulation flow rate increases slowly or even stops increasing, and the circulation ratio also ceases to rise, losing its self-compensation capability; if the heat load increases further, the circulation ratio actually decreases. This constant circulation ratio is known as the critical circulation ratio, and supercritical units illustrate this phenomenon.
The ratio of the circulating water volume entering the rising tube to the steam volume at its outlet. Due to the salt deposition on the water wall of high and medium pressure boilers, the circulation ratio must be sufficiently high. At subcritical pressure, the minimum cycle rate should be limited to avoid film boiling. The circulation ratio is related to the structure of the circulation system and the heating intensity of the riser. Under fixed conditions of the cross-sectional ratio between the downcomer and the upcomer and the structure, as the heat load increases, the circulation flow rate rises initially, and the circulation ratio also increases, demonstrating a self-compensating capability ； But at a certain point, if the heat load increases further, the circulation flow rate increases slowly or even stops increasing, and the circulation ratio also ceases to rise, losing its self-compensation capability; if the heat load increases further, the circulation ratio actually decreases. This constant circulation ratio is known as the critical circulation ratio, and supercritical units illustrate this phenomenon.
The so-called cycle ratio refers to the ratio of the amount of water involved in the cycle, G, to the amount of steam generated by the evaporation heating surface; in fact, it is the reciprocal of the steam dryness X at the outlet of the evaporation heating surface.
Steam dryness? Is it the amount of moisture in the steam?
Steam dryness: The mass percentage of dry saturated steam contained in each kilogram of wet saturated steam.
What was mentioned above refers only to the working fluid side; for circulating fluidized bed boilers, there is also the combustion gas side, which is the ratio between the amount of material returned to the furnace through the cyclone separator and the amount of fuel added.
It can be understood as how many revolutions per unit mass of fuel is required in the cyclone separator for it to turn gray What’s the use of this? What can it express? Thank you
A circulating bed boiler generally refers to the ratio of the amount of ash carried by the rising flue gas in the furnace per unit time to the amount of fuel fed into the furnace. It reflects the level of ash in the furnace; too high a level increases boiler wear ； Too low a value affects heat transfer and can result in insufficient boiler output. Generally between 10 and 20