Vapor drum and synthesis tower

I met two beautiful girls recently. I’ve always believed that the pressure in the drum has nothing to do with the pressure in the tubes inside the tower; if the pressure in the drum is 2.1, then the pressure in the tubes should be 3.6. I’ll give an example: imagine a tank with a pressure of 3.6 – can water at a pressure of 2.1 be added to that tank? The tubes and the drum form a connected system, and the pressure in this system should be approximately equal; otherwise, the pressure in the drum combined with the head difference of the boiler water will not be able to reach the tubes. Vaporization inside the tubes causes expansion, and this expansion is ultimately directed to the steam drum, from where it is then discharged into the steam pipeline via a pressure control valve. There’s also the fact that each steam pressure corresponds to a specific saturation temperature; if the pressure inside the pipe is really that high, how can the temperature of the synthesis tower be controlled? The difference between the pressure inside the tubes and that in the drum should be only due to pipe resistance. As for how to control the temperature of the synthesis tower, 1) one saturated vapor pressure corresponds to one saturated vapor temperature; 2) when unit amount of saturated water turns into saturated vapor, the temperature does not change, but more than 2,000 kilojoules of heat are required for this process. The temperature control of the synthesis tower is handled based on this theory. The temperature remains stable due to the heat absorbed during the vaporization of water in the boiler; by controlling the pressure in the drum, more steam can be produced when there is more heat release, and less steam is produced when there is less heat release. The steam in the drum and the tubes is in a saturated state. To lower the temperature and reduce the pressure in the drum, the boiler water becomes unsaturated and vaporizes in large quantities; eventually, a balance is reached at the saturated state. At this point, the temperature of the boiler water drops, while the synthesis temperature rises. To prevent further increases, vaporization occurs, and in this way a balance is achieved between the temperature of the synthesis tower and the temperature of the boiler water – that is, a balance between the temperature of the synthesis tower and the pressure in the drum – thereby achieving control over the temperature of the synthesis tower.

Generally, no one controls the drum temperature, unless at the beginning of the heating process when there is no pressure; once pressure is present, the drum temperature serves only as a reference. By controlling the drum pressure properly, one pressure level corresponds to one specific temperature. The drum downcomer and the tubes inside the tower form a U-shaped tube arrangement, with both ends connected to the drum; as a result, the pressure is the same in both areas. Therefore, the pressure throughout the entire system is the same; if there is any difference, it is only due to pipe resistance and the gravitational force of the material itself.

Controlling the drum pressure is intended to control the temperature of the synthesis tower, as for saturated steam, a fixed pressure corresponds to a basically fixed temperature; no one controls it deliberately just to regulate the drum pressure. The pressure in the drum is essentially the same as the water pressure inside the tubes; they are connected to each other.

The pressure inside the drum increases in a steady manner, that is, it rises within the shell. When adjusting the synthesis system, the pressure in the drum is usually controlled based on the exit temperature of the synthesis tower; our main parameter is the exit temperature, while the exact value of the drum pressure isn’t that important. Additionally, the pressure applied to add water to the drum is much higher than that in the drum itself. Liquids are incompressible, and this pressure can be considered as the driving force exerted by the boiler feed pump on the water supplied to the boiler

The pressure in the drum is the same as the pressure on the water side of the synthesis tower; the drum uses the saturated steam pressure to control the temperature of the bed in the synthesis tower, and the temperature of that bed is roughly the same as the temperature in the drum.

By controlling the drum pressure, we regulate the temperature of the synthesis tower to 240 degrees; generally, for every 0.1 MPa increase in drum pressure, the temperature of the synthesis tower rises by 1.5 degrees

Based on the principle of liquid saturated vapor pressure, temperature is controlled by pressure. The pressure in the water circuit of the steam drum and the synthesis tower is the same; only the vapor-water mixture with a relatively low density moves upward under this common pressure, while the water with a relatively high density, after separation, flows back down through the downcomer into the water circuit.

Who says the steam temperature in the drum isn’t important? Unless there’s something wrong with your instruments, go check the steam temperature in the drum, the pressure, as well as the outlet temperature of the synthesis tower before considering this issue

Temperature is only for reference; what’s important is to control the drum pressure. A certain pressure corresponds to a certain temperature, and there is a formula that can be used to calculate it, but unfortunately I don’t have the relevant information with me.