Is the amount of steam produced by the boiler at 3.5 Mpa the same as that at 1.0 Mpa?
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I would like to ask: a preheated boiler generates steam at 3.5 Mpa. If, with the same amount of heat and all other conditions remaining unchanged, it is adjusted to produce steam at 1.0 Mpa, will the amount of steam generated be the same? Is it true that more steam needs to be produced at 1.0 Mpa than at 3.5 Mpa? Thanks, those who know please share
With the same heat input and other conditions remaining unchanged, the amount of steam produced at 1.0 Mpa will be greater than that produced at 3.5 Mpa. This is because the generation of steam requires energy, that is, heat. When the pressure decreases, less energy is required to generate steam; therefore, more steam can be produced with the same amount of heat. But this is only a theoretical analysis; in reality, the steam production is also affected by various factors such as the efficiency of the boiler and heat losses. Therefore, the actual situation needs to be assessed based on practical operations. .
“\"The same amount of heat\" means that when the same amount of heat is supplied, the amount of heat generated is also roughly equal. More heat per unit volume is carried by 3.5 Mpa compared to 1.0 Mpa; as a result, more steam is produced after the adjustment. This can be calculated using the enthalpy value of the steam. Accordingly, the boiler needs to have more water added to it
The smoke exhaust temperature is reduced, so more is produced, of course
““A decrease in flue gas temperature” is a local factor; relying on local conditions can lead to significant errors in assessing the overall situation. It is necessary to consider the issue from a comprehensive perspective, taking into account the overall heat balance. Assuming that the total amount of coal burned per unit time remains constant, the input heat will also remain consistent. Input heat = amount of steam produced * calorific value + heat carried away by flue gas + heat carried away by slag + heat lost due to heat dissipation to the environment. When the temperature decreases, the heat carried away by flue gas and slag as well as heat loss due to dissipation all decrease, while the heat contained in the steam increases. A decrease in the calorific value may lead to an increase in the amount of steam produced. If, on the other hand, the heat carried away by flue gas and slag as well as heat loss due to dissipation increase, a decrease in the calorific value could still result in an increase in the amount of steam produced
Everything is based on assumptions; you wait for those assumptions to come true
There should be a change in this amount of steam, but it won’t be very noticeable. Looking at the amount of desalinated water produced through temperature and pressure reduction gives a roughly similar figure.
The original poster’s question is incomplete. Steam at 3.5 Mpa is likely superheated steam, and the temperature needs to be known. Steam at 1.0 Mpa is most likely saturated steam. With the boiler’s thermal efficiency remaining constant, the difference in the production volumes of the two types of steam can be calculated by looking up their enthalpy values in a table. The steam output at 1.0 Mpa will definitely be higher.