×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Are you an
Engineering professional?
Join Eng-Tips Forums!
• Talk With Other Members
• Be Notified Of Responses
• Keyword Search
Favorite Forums
• Automated Signatures
• Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

#### Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

# Natural gas consumption to produce 10m3 steam from room temperature water

## Natural gas consumption to produce 10m3 steam from room temperature water

(OP)
Hi guys:
I confess that I'm not at ease with thermodynamic calculations regarding steam production and I need some help checking my calculations

I am trying to calculate how much natural gas a boiler would consume to produce 10m3 of 8 bar steam from room temperature water and I am reaching values that seem odd to me but still couldn't nail where is my mistake.

Assumptions:
Water quantity: 10m3
Room Water temperature: 20C
Final Steam temperature: 170C
Water Sensible Heat: 1.2 kJ/Kg.C
Enthalpy liquid :720.9kJ/Kg
Enthalpy evaporation:2047 kJ/kg
Natural Gas Calorific value: 41,868.00 kJ/m3
Boiler efficiency: 85%

Total energy needed: 10,000*((150*1.2)+2047)=22,270,000.00kJ
Natural gas consumption:22,270,000.00/41,868*0.85=625.78 m3

I think that this is an absurd amount of natural gas and my gut feeling was expecting a much lower natural gas volume.
What am I doing wrong?

Thanks for the help

### RE: Natural gas consumption to produce 10m3 steam from room temperature water

10m3 of saturated steam at 8barg has a specific volume of 0.235m3/kg, so this converts to 10/0.235 = 42.5kg of steam, so you'd start off with 42.5kg of liquid water, which translates to 42.5e-3m3, not 10m3. Else calc looks good.
The sensible heat to raise liq water from 20degC to 170degC should be based on a Cp value of 4.2kJ/kg/degC, not 1.2kJ/kg/degC - think you've quoted the Cp value of sat steam.
Nat gas calorific value seems high at 42MJ/sm3, usually it is approx 35MJ/sm3 (LHV), but maybe this is some rich nat gas ?

#### Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

#### Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

#### Resources

White Paper - Effects of AIA Quick Guide to UL 489 or UL 1077
The function of a circuit breaker is to provide overload (thermal) and short-circuit (magnetic) protection to a circuit and its downstream components. A circuit breaker functions like an airbag in a car, protecting circuit components and people by tripping the circuit to interrupt the current flow if it detects a fault condition in the control system. Download Now
White Paper - Guide to Integrate Large-Format Additive
As with any new technology, getting into large-format 3D printing begins with investigation. The first question may be a simple one: what does “large-format” mean? For 3D printers, “large” is a relative term. Many extrusion-based (FFF) 3D printers are referred to as desktop machines, because they fit on table space. Some of these have very respectable build volumes – but when it comes to “large-format,” the machines will need their own dedicated floor space. Large-format 3D printers have significant build volumes and are most often found in professional settings, like manufacturing facilities and R&D centers. Download Now

Close Box

# Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

• Talk To Other Members
• Notification Of Responses To Questions
• Favorite Forums One Click Access
• Keyword Search Of All Posts, And More...

Register now while it's still free!