You can put your dirty thoughts back into their box. This post is not about that.
I'm not content with just working in an industrial facility and not knowing the processes involved. That's why I've been paying attention to the boilers, equipment and steam use where I'm working.
They use a lot of steam, where I'm working. Rail cars, ships and barges come from great distances, are full of sulfur and the sulfur can be solid. That's where the steam comes into place.
The boilers fascinate me. Inside the combustion chambers are steel tubes, which is where the steam is produced. Natural gas, which is only one of many fuels, is used for the heat and the heat of the flames is increased by forced air blowers.
The basic process is the high temperature in the combustion chamber heats the water, the water flashes to steam and the steam is channeled through insulated piping. That's the simple process.
Steam has different temperatures at different pressures. The higher the pressure; the hotter the steam. At high pressures, the heat of the steam can reach the point it changes products into different substances, which is how petroleum is distilled and many products derived from crude oil. The downside is that the high temperatures are above the flash point of many of the products. At those temperatures, something seemingly insignificant, like a tiny leaking flange on a pipe, can result in an instant fire, since the only requirement left for combustion is the introduction of oxygen, which is abundant in air. That's why refineries limit employees during the process of bringing a unit back on line after maintenance. Things can get out of hand quickly, and disasters are not unknown.
Steam pressure is determined by regulators, so the heat is controlled and kept at the optimum temperature for the process. Where I'm working, the boilers are kept at about 110 pounds of pressure and the steam for the different processes varies. The steam travels through insulated pipes, into steam jackets on rail cars, which heats the sulfur above the melting point. The liquid sulfur is dumped into concrete trenches, that have steam loops in the bottom to insure the sulfur doesn't "freeze" during transfer. The sulfur flows into a pit and pumped to large storage tanks kept hot with steam.
Steam doesn't stay steam forever. As it's used, the temperature drops and the hot water is eventually collected back into the "hot well". From there, it's pumped to a deaeration tank, which supplies the boilers with water for steam. There, the process begins again.
Attrition through leaks requires makeup water for the system, which is controlled by a float in the hot well. When the well drops below a certain level, water is added.
Makeup water isn't just tap water. Chemicals are added to prevent scaling and corrosion in the boiler tubes, which can fail if the water is contaminated. If that should happen, the combustion chamber is "kicked" with super heated water, which raises the pressure tremendously. If the relief valves don't allow the gasses to escape, the boiler explodes. That's why boilers have sight port, so inspections can be made while the boiler is running. If the tubes appear to be distorted, or leaking, the boiler can be shut down for repair before a catastrophic failure.
In a perfect world, little to no water is added to the closed steam loop. But leaks happen and the amount of additional water is dictated by the amount of leaks. Since heating water requires expensive energy, steam leaks are frowned upon.
So, now you know as much about boilers as I do. They're fascinating, loud, hot critters that make noises that make your hair stand on end. While those that operate them are used to the noises, I'm not and they sometimes make me nervous.