Calculating Steam Production in Fire Tube Boiler | 180ºC Dry Saturated Steam

In summary, the flue gas enters the boiler at 1500ºC and leaves at 100ºC. The feed water is externally preheated to 180ºC before entering the boiler. The mean specific heat capacity of the flue gases is 1.15 kJ/kgK. The latent heat of vaporisation of the water at 180ºC is 2015 kJ/kg. The amount of steam produced per hour is determined by the total heat loss and the difference between the feed water temperature and the temperature of the flue gas.
  • #1
Big Jock
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Homework Statement


Dry saturated steam at a temperature of 180ºC is to be produced in a fire tube boiler from cooling of 50000 kg/h of flue gases from a pressurised combustion process. The gases enter the tubes of the boiler at 1500ºC and leave at 100ºC. The feed water is externally preheated to 180ºC before entering the boiler.
The mean specific heat capacity of the flue gases is 1.15 kJ/kgK. The latent heat of vaporisation of the water at 180ºC is 2015 kJ/kg. Feed water temperature = 180ºC.
Determine the amount of steam produced per hour, if the total heat loss is 10% of the heat available for steam raising.

Don't even know where to begin with this so any advise to get me started would be extremely grateful as I am completely lost at the moment.

Many thanks in advance...
 
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  • #2
Try rearranging the problem statement...

It describes a source of heat...

"50000 kg/h of flue gases"
"enter the tubes of the boiler at 1500ºC and leave at 100ºC"
"The mean specific heat capacity of the flue gases is 1.15 kJ/kgK."

That's enough information (using a suitably relevant equation) to calculate the amount of heat (per hour) "available for steam raising".

It describes where that heat is going...

"The feed water is externally preheated to 180ºC"
"Dry saturated steam at a temperature of 180ºC is to be produced."
"The latent heat of vaporisation of the water at 180ºC is 2015 kJ/kg"

You can apply that data to [strike]the same[/strike] a similar relevant equation to find the mass (per hour) of steam produced.
 
Last edited:
  • #3
The flue gasses cannot leave at a lower temperature than the feed water, is that 100 Deg C a typo?
 
  • #4
Yes Jobrag it was a typo should have been 200 deg C
 
  • #5
I assume you are familiar with the concept of enthalpy. What is the change in enthalpy of 1 kg of flue gas if you cool it from 1500 C to 200 C? What is the change in enthalpy of 50000 kg of flue gas if you cool it from 1500 C to 200 C? What is the rate of heat transferred (per hour) from the flue gas?

Chet
 
  • #6
afraid not Chet this is how I'am finding this question extremely difficult. I would imagine once you have a handle on what you stated the question is relatively simple?
 
  • #7
Have you learned about heat Q and heat capacity Cp? What kind of course is this? Physics 101 or Thermo?

Chet
 
  • #8
yeah Chet I know about those. Its actually from a heat transfer and combustion task I have been set...
 
  • #9
Big Jock said:
yeah Chet I know about those. Its actually from a heat transfer and combustion task I have been set...
OK. In that case, how much heat do you have to remove to cool 1 kg of flue gas from 1500 C to 200 C?

Chet
 
  • #10
Have you an equation for that so I can look through the course work...
 
  • #11
Big Jock said:
Have you an equation for that so I can look through the course work...
The idea is for you to look through the course work and find the equation you need. What text are you using? Look up heat capacity in the appendix. Do you realize that you are spending more of your valuable time asking questions than it would take to just look it up in your notes and textbook?

Chet
 
  • #12
Chet trust me this was a last resort. I have spent 3 days 12 hour days reading my course work and this isn't covered at all hence why I need the help.

The tutor is asking if I have ever used the energy balance equation but I have no idea what this even looks like
 
  • #13
Big Jock said:
Chet trust me this was a last resort. I have spent 3 days 12 hour days reading my course work and this isn't covered at all hence why I need the help.

The tutor is asking if I have ever used the energy balance equation but I have no idea what this even looks like
What's the title of your textbook? Have you tried Googling "heat capacity?"
 
  • #14
Don't have a textbook Chet only course notes they have provided. If you could recommend a good book or relevant PDF files I can find online feel free...
 
  • #15
Big Jock said:
Don't have a textbook Chet only course notes they have provided. If you could recommend a good book or relevant PDF files I can find online feel free...
I already suggested that you Google heat capacity. Also, check Amazon for any book on freshman physics.

Chet
 
  • #16
Wikipedia has a lot of info. Make sure you understand the difference between "Heat Capacity" and "Specific Heat Capacity". You will also need to look up and understand "latent heat of vaporisation" for the second part.
 

1. How is steam produced per hour measured?

Steam produced per hour is typically measured in units of mass, such as kilograms or pounds, or in units of energy, such as joules or British thermal units (BTUs). The amount of steam produced per hour can also be measured in units of volume, such as cubic meters or cubic feet.

2. What factors affect the amount of steam produced per hour?

The amount of steam produced per hour can be affected by several factors, including the type and efficiency of the steam production equipment, the temperature and pressure of the steam, and the quality and quantity of the fuel used to produce the steam. Other factors that can affect steam production include ambient temperature and humidity, as well as any heat losses in the steam production process.

3. How does steam production per hour impact the efficiency of a system?

The efficiency of a system can be greatly impacted by the amount of steam produced per hour. This is because steam is often used to power machines or equipment, and the more steam that is produced, the more work can be done. However, if too much steam is produced, it can lead to energy waste and decreased efficiency. On the other hand, if not enough steam is produced, it can result in a decrease in the amount of work that can be done by the system.

4. What is the average amount of steam produced per hour in a typical industrial setting?

The amount of steam produced per hour in a typical industrial setting can vary greatly depending on the industry and the specific equipment being used. However, on average, steam production can range from a few thousand pounds per hour to over a million pounds per hour in large power plants or industrial facilities.

5. How can steam production per hour be optimized?

To optimize steam production per hour, it is important to regularly maintain and tune steam production equipment to ensure it is running at peak efficiency. Choosing the right type and quality of fuel can also greatly impact steam production. In addition, implementing energy-saving measures, such as insulation and heat recovery systems, can help to reduce heat losses and increase steam production. Regular monitoring and adjustments can also help to optimize steam production per hour in industrial settings.

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