Run cold water over the pipes
This is a very good idea. The gas is passed over pipes that have cold water running through them, and the heat goes from the gas into the water. The gas gets cooler, the water gets hotter - this is called a heat exchanger.
Visit the Industry Animated site to see how a heat exchanger works (this link will open a new window so you don't lose your place!)
OK, it's your turn to run the control room...