how many kcal needed to get 10000 kg sat. steam 1

[AHMEDDODO]

hi all,

if i have a boiler that works under pressure of 10 bar to produce 10000 kg of saturated steam per hour and it works by natural gas
1 m^3 natural gas = 9750 kcal
and the heating value of it isa 980 to 1100 btu/ft^3
what is the amount of gas i need per hour?
and what is the amount of water i need to produce that amount of steam?
waht is the formulas used or how i could calculate something like this?

thanks

 

[MintJulep]

What is the starting temp of the water?

Just look this up in the steam tables.

 

[Montemayor]

If you are a graduate mechanical engineer, you should know you have to have the lower heating value identified before you can start any heat and material balance around any boiler. And it is precisely a heat and material balance what will get you what you are asking. But you haven't even identified which heat value you've given us.

You need to back to the basics of Thermodynamics and make the heat & material balance.

 

[AHMEDDODO]

the starting temp. of water is 23 deg.c
what can do a heat and material balance to get the amount of gas??

 

[mauner]

Given 10 bar = 145 psi

P = 145 psia
v = 3.115461111 ft^3/lbm
T = 355.8126831 deg F
s = 1.572958589 BTU/lbm-R
h = 1194.156738 BTU/lbm
X = 1 nd
STATE = Saturated vapor

P = 145 psia
v = 0.018058134 ft^3/lbm
T = 355.8126831 deg F
s = 0.510563552 BTU/lbm-R
h = 327.7919617 BTU/lbm
X = 0 nd
STATE = Saturated liquid

Delta h = 866.4 BTU/lbm

Given: 10000 kg/hr = 2205 lbm/hr

866.4* 2205 = 1910334 Btu/hr

Given: 9750 kcal/m3 = 38692 Btu/m3

1910334/38692 = 49.4 m3/hr

Assuming Thermal efficiency = 0.8

49.4/0.8 = 61.7 m3/hr

Water consumption = 2205 lbm/hr / 8.3 lb/gal = 267 gal/hr
or 16.8 liters/minute

 

[StoneCold]

Mauner
Good Job! You are hired.
AHMEDDODO I am sorry we have to let you go.

 

[quark]

mauner,

Recheck your calculation with OP's last post.

Stonecold,

It is highly biassed and unethical to declare the results without revealing a scheduled interview(perhaps a walk-in?), previously.

Please explain me why I can't sue you as you deliberately prevented me from earning a livelihood.

Any moral police out there

 

[mauner]

Boy,

I can't believe I lost the job just because of an incomplete 5 minute calculation and a dropped zero!


Corrected should be 22045 lbm/hr * 866.4 BTU/lbm = 19099788

Plus sensible heat from 55F to 355F or 282.4*22045 = 6225508

For a total of 25325296 Btu/hr

25325296/38692 = 654.5 m3/hr / 0.8 = 818.2 m3/hr

Water flow = 22045 * 8.3 /60 = 3050 gpm or 11544 Liter/min

 

[Mattysdad]

what do you need to do with the steam, there may be a better way ?