To produce 5 MW of electricity how much steam pressure is needed and water in relevancy. What temperature is needed to produce it and what size pipe should be piped into the steam turbine?

Answer 1

That is a question that does not have one single answer. For instance, if the pressure of the steam is raised, less steam is needed. As pressure rises, temperature will also rise due to adiabatic work done on the steam. Also, higher temperatures are needed at higher pressures to make sure the steam does not condense. Raising the temperature of the steam at a given pressure also means that less steam is needed to provide the same amount of energy. Efficiency will also vary, depending on the turbine, and other factors, such ascondenser vacuum.

In general, running a pressure around 40 - 45 PSI, it will take 20,000 - 25,000 pounds of steam per hour to generate one megawatt of electricity during that hour. This is with steam that is just above saturation (around 285°F). So, for 5 MW, you'd need around 100,000 pounds of steam an hour. The pipe size would depend on the turbine. A 55 MW turbine (common for geothermal), might have two pipes bringing steam in (one per side), both of which are around 30" in diameter. For 100,000 pounds of steam an hour, much smaller pipes would suffice. However, expanding and then compressing the steam repeatedly is something you want to avoid.

Note that these figures reflect more of a geothermal application. The pressure and temperature of steam from a boiler will typically be much higher.