Are the water wall and drum of the boiler connected? Is the pressure equal inside the water wall and the drum?

There are textbooks on industrial boilers available online; take a look at them. If you have any questions, ask then

Firstly, the water wall and the drum are connected to each other; it is generally assumed that the pressure inside the water wall and the drum is equal. As for why it is called a water wall rather than a tubular heat exchanger, I’m not sure. Under normal circumstances, the drum is not exposed to direct heat – the main source of heating comes from the water wall, which absorbs the radiant heat from the fuel inside the boiler. Additionally, because the water wall covers a large area, the heating is more uniform. If the drum were to be exposed to direct heat, with a smaller heating surface, uneven heating could occur, leading to deformation of the drum, which poses certain risks and results in greater heat loss. I have been working in the boiler industry for only a short time, so the above are merely my personal insights

The term ‘vapor drum’ is a colloquial name; it should generally be referred to as a boiler drum, where heating, vaporization, and superheating take place. The water wall is named so because it is arranged on the inner side of the furnace/chamber in a screen-like configuration; fins/ridges are present between these walls to enhance heat absorption, similar to the structure of a wall. Water cooling is used because it absorbs the heat from the fuel, protecting the walls; the water/heat transfer oil/or other fluids inside the pipes flow due to differences in density and pressure caused by heating. The water wall and the drum are connected. But the pressures are not necessarily equal. For example, double drum, triple drum, etc.; it needs to be determined based on the structure. A heat exchanger is a device that transfers part of the heat from a hot fluid to a cold fluid, on the condition that the heat exchanger itself does not absorb external heat; instead, heat exchange occurs between the fluids inside it. In simple terms, the operating requirements for water wall systems are more stringent and complex compared to those of ordinary heat exchangers. The calculations related to water walls are based on boiler parameters rather than those of containers; factors such as soot coefficient, flue gas darkness, and fly ash wear are taken into account in these calculations, whereas such factors are not considered in container-related calculations. Don’t study mechanically; there are many types of boiler structures, as well as various designs for steam drums. It cannot be assumed that the drum is not directly heated; this must be determined based on the type and design of the boiler. For example, DZL models have directly heated sections to increase the heating surface area. As for furnaces such as boiling furnaces and fluidized bed furnaces, it’s a different situation – specific analysis is required for each case. The last question – I didn’t understand it. If pressure and temperature control are to be achieved solely through water wall cooling, a large amount of steel will be required, and it should be understood that steam always contains water. The drum serves to separate steam from water; it also has functions such as waste discharge, drying, and overall safety pressure relief.