flash steam

[soufiane]

I wish to produce some steam by using the energie of smokes resulting from an furnace of combustion which produces 40000 kg / hour of smokes. The flow of smokes which will be used for the production of the vapor is 7000 kg / hour to produce 150 kg / hour of vapor. Given that the quantity of vapor is far too small of a boiler to build using a traditional steam
drum, I thought of making circulate more water than steam needed and at a pressure where it
doesn't evaporate in the coil, then direct the flow to a separation
tank(small drum) to vaporize at pressure required. I wish to have suggéstions concerning the design of the valve allowing this depression and the feasibility of this solution. The vapor generated in 5 bar will be used to warm the fuel oil by the intermidiaire of a heat exchanger.

thanks

 

[benriemens]

soufiane,
why not heat the fuel oil directly by means of the pressurised water?

grtz
Ben

 

[soufiane]

The heater of the fuel oil is made by a heat exchanger the heating fluid of which was some steam, in more it is necessary to know that the latent heat of evaporation of the water is big compared with the sensitive heat that the water pressurized can supply what risks to modify the heat exchanger which is already installed.

 

[quark]

Soufiane!

This is what I understood from your post and I am running the risk of answering in a totally wrong way, if my understanding is wrong.

Afterall they say, curiosity killed the cat

Your total flow of smoke is 40000kg/hr and you are utilising only 7000kg/hr out of that to produce 150kg/hr of vapor(is it steam? and you want to utilise rest of 33000 kg/hr of steam to heat the water at higher pressure than required. And then you will reduce the pressure to flash into steam and use it.

If this is so, I have few comments. 1) First thing is what is your smoke temperature before heating water and after heating water.
2) What is the minimum temperature to which you can reduce the smoke temperature? (consider sulfur condensation for this)
3)The sensible heat of water is 1kCal/kg deg.C and latent heat of evaporation is 550 kCal/kg deg. C. This means if you want to produce flash steam, you require to use approximately 55 kgs of water for 1 kg of flash steam. (if you reduce pressure by 1 kg/sq.cm)

Your second post is still confusing me because, heat water at higher pressure, then depressurise it, convert it to steam and use it for heat. Or else directly use hot water in one single step is one and same with better efficiency in later case.

Regards, Truth: Even the hardest of the problems will have atleast one simple solution. Mine may not be one.

 

[boilerguy]

How about using the flue gas (smoke) to directy heat the fuel oil?