Find the steam required. The heater discharges 450000 lbs per hour of water, the entering temperature is 276 degrees Farenheit and steam enters a contact type of heater at 139 psia and 1254.0 Btu per lb.I've got 0 ideas on how to start this problem, i wrote it down exactly as it was asked by the book. Please! in dire need of help!
It doesn't look like you have all of the information needed. It appears that you are using steam at 139 psia and 1254 btus per pound to heat water at about 40 plus psig and 276 degs to some other temperature. Without the information on the water exiting the heater you only have part of the heat load defined. This problem looks like a typographical error. NOTE: What goes in and what comes out in terms of the steam or water will of course always be equal but the pressure, temperature and physical states won't be. That is the problem. You must have these conditions defined for either the water or the steam both going in and coming out. Let’s take another example similar to your problem: When you have two fluids, one heating up the other, you need to determine the amount of heat required to heat the colder fluid and from that you can determine how much of the hot fluid you need to and how much heat it must give up. Let us assume you have an open tank containing 150 pounds of water at 100 degs F. Let us also assume you are going to heat it to 200 degs F with saturated steam at atmospheric pressure which means the steam will start at 212 degs F. Since you know the starting and ending conditions of the water in the tank you can determine how much heat is needed to get to this point. You now need to determine how much steam you need to heat up the water. When you introduce the steam to the water, it will first condense giving up its latent heat. It will then be saturated water at 212 degs F. It will then further cool down until it is at 200 degs F. By knowing these conditions, you can determine on a per pound basis how much heat each pound of steam will give up in the process. Since the heat transferred must balance between the water and the steam you can then determine how many pounds of steam are needed and the total amount of water now in the tank.
