Eng-Tips is the largest engineering community on the Internet
Intelligent Work Forums for Engineering Professionals
-
Congratulations waross on being selected by the Tek-Tips community for having the most helpful posts in the forums last week. Way to Go!
calculating amount of 60# steam 1
- Thread starter JGP08
- Start date
-
1
- #2
racookpe1978
Nuclear
What was your nominal inlet conditions for the water that would have been heated?
(Energy out - energy in)/lbm water x amount of water/sec x nbr of seconds = energy gained in the HX
Now: From YOUR steam tables at 60 psig, what energy out do you think you were getting? Saturated, right?
(Energy out - energy in)/lbm water x amount of water/sec x nbr of seconds = energy gained in the HX
Now: From YOUR steam tables at 60 psig, what energy out do you think you were getting? Saturated, right?
- Thread starter
- #5
Racookpe1978,
the inlet conditions are
T = 80 F
P = 70 psig.
It is def saturated steam. but I guess i worded my question poorly, the steam is not being produced by the heat exchanger, it is created somewhere else in the process. however the purpose of the heat exchanger is raising the remperature to about 140 F. since the heat exchanger was down for cleaning this water wasnt heated up but it would've normally gained 30MMBTU/hr. now based on that how much 60# steam would I have created.
Thanks
the inlet conditions are
T = 80 F
P = 70 psig.
It is def saturated steam. but I guess i worded my question poorly, the steam is not being produced by the heat exchanger, it is created somewhere else in the process. however the purpose of the heat exchanger is raising the remperature to about 140 F. since the heat exchanger was down for cleaning this water wasnt heated up but it would've normally gained 30MMBTU/hr. now based on that how much 60# steam would I have created.
Thanks
- Thread starter
- #6
racookpe1978
Nuclear
If your steam is being produced elsewhere (in a different heat exchanger) then in this heat exchanger, you need to use (Temp_water_out - Temp_water_in)x Cp_water = heat exchanged across the heat exchanger if no change of phase. At those low pressures and temperatures, it should be pretty simple.
When you know the energy of the hot water going into the second heat exchanger, and some estimate of its efficiency, then you get the steam energy out. Which will always be less than the orignal energy.
To get "value" of that steam, you need t know the contract cost you are getting paid for the steam.
When you know the energy of the hot water going into the second heat exchanger, and some estimate of its efficiency, then you get the steam energy out. Which will always be less than the orignal energy.
To get "value" of that steam, you need t know the contract cost you are getting paid for the steam.
- Thread starter
- #8
as I see the system
total heat load (30MMBTU/hr) Q = sensible heat Qs + latent heat Ql
latent heat corresponds to the production of steam by vaporization; massflow balance is :
m1 (water kg/h at inlet) =m2 (kg/h steam) + m3 (water kg/h at outlet)
So heat balance should be: Q = m3 x Cp x (T_v - T_inlet) + m2 x h_v x Delta_W
Delta_W = change of vapour content ; I think this should be put to 1 but not sure
T_v = Temperature of vaporization at 60psig (steam tables).
Then basically knowing 'h_v, T_v, T_inlet' you are looking for m2 and m3 ; knowing the hours you can calculate back the amount of steam generated _ do you agree ?
This how I see the problem; I may have misunderstood the question; anyhow if someone can point out any flaw in this, thanks.
Sorry for using S.I units.
Therefore I think the question cant be answered without knowing the total flow of water at inlet ; the rated capacity of the heat exchanger that is down could be used
"If you want to acquire a knowledge or skill, read a book and practice the skill".
total heat load (30MMBTU/hr) Q = sensible heat Qs + latent heat Ql
latent heat corresponds to the production of steam by vaporization; massflow balance is :
m1 (water kg/h at inlet) =m2 (kg/h steam) + m3 (water kg/h at outlet)
So heat balance should be: Q = m3 x Cp x (T_v - T_inlet) + m2 x h_v x Delta_W
Delta_W = change of vapour content ; I think this should be put to 1 but not sure
T_v = Temperature of vaporization at 60psig (steam tables).
Then basically knowing 'h_v, T_v, T_inlet' you are looking for m2 and m3 ; knowing the hours you can calculate back the amount of steam generated _ do you agree ?
This how I see the problem; I may have misunderstood the question; anyhow if someone can point out any flaw in this, thanks.
Sorry for using S.I units.
Therefore I think the question cant be answered without knowing the total flow of water at inlet ; the rated capacity of the heat exchanger that is down could be used
"If you want to acquire a knowledge or skill, read a book and practice the skill".
waqasmanzoor
Chemical
JGP08
Dear, have you tried simulating the process in Aspen PLUS or Aspen HYSYS. Besides doing manual calculations (which you should do for better grasping of process engineering concepts), you can very easily (and swiftly) calculate the "LOST STEAM" by using the process simulators.
First simulate the process in normal operation and try to calculate the total steam produced in normal mode.
Then specify the duty of the HX in question as 0 MMBTU/H in the simulator, and again look at the total steam produced.
The difference between the two steam production rates would give you the "LOST STEAM PER HOUR".
MULTIPLY this "LOST STEAM PER HOUR" by 7 to get the steam lost in 7 hours.
If you share the process data then I can calculate this for you
Regards.
Dear, have you tried simulating the process in Aspen PLUS or Aspen HYSYS. Besides doing manual calculations (which you should do for better grasping of process engineering concepts), you can very easily (and swiftly) calculate the "LOST STEAM" by using the process simulators.
First simulate the process in normal operation and try to calculate the total steam produced in normal mode.
Then specify the duty of the HX in question as 0 MMBTU/H in the simulator, and again look at the total steam produced.
The difference between the two steam production rates would give you the "LOST STEAM PER HOUR".
MULTIPLY this "LOST STEAM PER HOUR" by 7 to get the steam lost in 7 hours.
If you share the process data then I can calculate this for you
Regards.
waqasmanzoor
Chemical
By the way, 30 MMBTU/H seems to be a very big heat exchanger
How much is the water flow rate?
How much is the water flow rate?
- Status
Similar threads
- Locked
- Question
- Locked
- Question