Is a continuous exothermic reaction possible?

[charlie10]

Is it possible to combine compounds to be constantly reacting with each other to produce heat? If so what is the most heat a reaction could produce and how long will it last? What compounds would be best to get this effect?

[CaptainPanic]

If you have a gas stove, you could light the fire. Then you continuously mix methane and air, and you produce about 55 MJ/kg methane.

 

The hottest is perhaps hydrogen and oxygen?

 

Continuous reactions can last as long as you like. It is a choice that the designer (engineer) can make. In fact, most chemical factories are running continuous.

[charlie10]

the reason i'm asking is would it be possible to heat up a house boiler by having a tube inside the boiler with this reaction continuously occurring within it to heat up the water?

[mississippichem]

Yes, but eventually reactants must be added. If not, all the reactants will be consumed and the reaction will grind to a halt. However, some radical reactions can go a very long way before stopping; and can, at least theoretically, be initiated with as little as one photon.

[Horza2002]

There is no reaction in which u can mix a set amount of reagents together and they will continuously produce heat. You can have several reactions going on one after the other that release heat, but you will eventually reach a point where the products are too stable to go any further. The maximum amount of energy a reaction can possible liberate is achieved by breaking all the bonds and making the strongest ones possible. Once thats done, the products will be the most stable possible and will therefore be no further reaction.

 

Like Mississippichem said, there are some living polymerisation radical reactions that can go on in practise for eternity if you provide enough reagents for them. But then, you have to keep putting reagents in and it requires energy to yields them in the first place.

[CaptainPanic]

the reason i'm asking is would it be possible to heat up a house boiler by having a tube inside the boiler with this reaction continuously occurring within it to heat up the water?

 

Difficult.

Apart from some engineering issues that you need to solve later (length of the tube, amount of fuel needed, volume of water, and temperature control to name a few), my first question is:

 

What's wrong with a regular gas powered boiler? It does pretty much exactly what you say you need, with the only exception that the reaction doesn't take place in the tube. Instead, the water goes through the tube, and the fire is outside.

 

After all, for heating, gas is pretty cheap.

 

I strongly believe that, from a chemical engineering point of view, you're trying something much too difficult. I therefore would suggest that you take a little more time to describe what you want:

- You want a boiler with a tube in the liquid to heat it.

- Why you want to have a different fuel (costs? eco-friendliness? something else?)

- Is there any specific reason why the reaction must be in a tube (why can't the water be in a tube, and the reaction outside?)

[charlie10]

yes it would be a more eco friendly way of heating water. I've just recently got into the idea of renewable energy and i'm just trying to explore what opportunities there are.