- #1

- 7

- 0

1) Feed water enters a boiler at 172.52 degrees Celsius. The boiler produces super heated steam at 5600kpa and 472 degrees Celsius. The boiler efficiency is 82%. Find the Heat required by fuel.

2)

I interpolated the value given for feed water and super heated steam.

h@5600kpa 472 degrees Celsius = 3359.0128 kj/kg

hf@ 172.52 degrees Celsius = 730.30 kj/kg

So...

delta h = 3359.0128 kj/kg - 730.30kj/kg

delta h = 2628.7128 kj/kg (this is the energy that the boiler would produce running at 100% to make the given steam right?)

So...

Qfuel = (2628.7128 kj/kg)(1.18) (I'm multiplying by 1.18 to make up for the 18% efficiency difference)

Qfuel = 3101.88 kj/kg

efficiency = Qsteam/Qfuel

.82 = 2628.7128/Qfuel

Qfuel = 3205.07 kj/kg

3) I get two different answers for quantity of heat required by fuel. Can someone please explain why? Thank you.

2)

I interpolated the value given for feed water and super heated steam.

h@5600kpa 472 degrees Celsius = 3359.0128 kj/kg

hf@ 172.52 degrees Celsius = 730.30 kj/kg

So...

delta h = 3359.0128 kj/kg - 730.30kj/kg

delta h = 2628.7128 kj/kg (this is the energy that the boiler would produce running at 100% to make the given steam right?)

So...

Qfuel = (2628.7128 kj/kg)(1.18) (I'm multiplying by 1.18 to make up for the 18% efficiency difference)

Qfuel = 3101.88 kj/kg

efficiency = Qsteam/Qfuel

.82 = 2628.7128/Qfuel

Qfuel = 3205.07 kj/kg

3) I get two different answers for quantity of heat required by fuel. Can someone please explain why? Thank you.

Last edited: