Where does the steam in pipes go?
Answer:
It's mainly used for heating systems, centralizing the heat production to realize the greatest efficiency of scale. Building systems like this is hugely expensive, so it requires a dense urban core (like Manhattan) to become worthwhile.
It's not only done with steam for heating, though. In Toronto, cold water from deep in Lake Ontario is circulated through heat exchangers to provide efficient air conditioning for the downtown core, resulting in huge energy savings.
Con Edison produces 30 billion pounds of steam each year through its seven cogeneration plants (which boil water to 1,000°F (538°C)) before pumping it to 100,000 buildings in Manhattan below 96th Street -- the biggest steam system in the world.
The steam coursing under Manhattan is not to be confused with what is popularly called steam rising from many city manholes. The steam in the pipes is invisible, while the so-called steam wafting up from the streets is often vapor produced when underground water hits hot equipment and escapes from beneath the streets. It can also be condensed steam leaking from the Con Ed system.
Some of the real steam winds up at St. Vincent's Hospital on 12th Street, where the forceps in the operating room are sterilized using steam. Every day nearly 200 cleaning trays of surgical instruments pass through the Central Sterilization unit at St. Vincent's. A cleaning tray can contain anywhere from six to 130 pieces of surgical steel, depending on the size of the instruments. First, the trays are placed in a washer-disinfector, similar to a regular dishwasher. Then the trays go into the sterilizer where steam circulates inside. The intensity of the heat from the steam kills any viral or bacterial pathogens.
Most of the steam, though, is used for heating and cooling. Steam used for heating flows from Con Edison's underground mains into a building's internal heating pipes and then into a radiator where it heats a room. For cooling, steam flows from the main into a building's steam air conditioning unit.
The use of steam eliminates the need for boilers in individual buildings. Because steam from Con Edison's centralized plants is mass-produced, it is generally more economical, efficient and environmentally friendly than individual oil or gas boilers.
Joe Petta of Con Edison compares it to mass transit. "Which is better for the environment, 50 people riding to the city on a bus or 50 people riding 50 different vehicles? The emissions from one bus will be less than the emissions for 50 cars," says Petta. And he adds, the plants that produce steam are subject to "more stringent environmental and emissions controls than individual buildings generating their own heat either by burning gas or oil."
Typically for heating buildings
Steam would be used in the HVAC for buildings. It is not uncommon to cool the air below the desired temperature you want and then reheat it as a way to lower the humidity of the air in the building.
The steam is superheated and at high pressure (hence the explosion of a very old pipeline).
It is piped from a steam generating plant to a number of high-rise buildings in the area as a heating medium.
Some of the steam may be used to drive turbines that, in turn, are driving water pumps to distribute fresh water to the units.
As the steam cools and condenses back to water, its pressure drops to near atmospheric and returns to the plant for re-vaporisation.
The answers post by the user, for information only, FunQA.com does not guarantee the right.
More Questions and Answers: