A steam condenser is a piece of machinery that turns steam into water. Many steam-based systems use a circuit of water to maximize their efficiency. Water is heated into steam, the steam provides motivation for a process, a steam condenser turns it back into water and the cycle begins again. Steam condensers come in two varieties, contact condensers and surface condensers. Each of these systems uses a cooler liquid, generally liquid water, to cool the steam back into water.
Many power generation systems use steam to actually create energy. Oil, coal, and even nuclear power plants use the energy they generate to heat water into steam. That steam turns a turbine, which generates power. In order for any power generation system to function at top efficiency, the water needs to become steam and then go back to water with as little temperature change as possible. The best way to achieve this is to reuse water over and over again.
One important thing about water is the effects pressure has on it. As pressure increases on water, it stays liquid longer. At very high pressure, liquid water exists far past its normal boiling point, the point at which it turns to steam. At very low pressure, the water turns into steam at a much lower temperature. This property is often used as an assistant for moving water back and forth between a liquid and a gas.
A contact steam condenser almost always uses water vapor and liquid water as its gas and liquid. The steam or water may have a secondary substance within it, but it is much smaller in volume than the water. This system uses a large tank, which may be under greater-than-normal pressure, to trap and hold steam. Liquid water is sprayed into the tank, which rapidly cools the steam and turns it back into water. The combined water is then pumped back into the system.
A surface steam condenser uses water vapor, but may not use water as the coolant. In this system, steam moves into a collection chamber containing pipes filled with coolant. The steam condenses on these pipes and drips to the bottom of the tank. The liquid water at the bottom of the tank is pumped back into the system. At no time during the process will the water and the coolant come in contact with one another.
Surface condensers have one main advantage over contact condensers—they don’t require additional cool water. A surface steam condenser can use nearly any liquid or gas that is cooler than the steam to condense the water into liquid. This is useful in arid areas, as the water requirements are much lower. In addition, the coolant pipes and the condensing chamber may be under different pressures, exacerbating the temperature difference.