Question

A new coal-fired power plant has been built using a sulfur emission control system that is 70.% efficient. If all of the sulfur oxidizes to SO2 and the emissions of SO2 are limited to 0.60 lb SO2 per million BTU of heat into the power plant, what maximum percent sulfur content can the fuel have if (a) 15,000. BTU/lb coal is burned; or if (b) 9000. BTU/lb coal is burned.

Answer 1

To determine the maximum percent sulfur content the fuel can have, the sulfur emissions limit and the efficiency of the sulfur emission control system must be considered. For (a) burning 15,000 BTU/lb of coal, the maximum sulfur content is 0.004%. For (b) burning 9,000 BTU/lb of coal, the maximum sulfur content is 0.0067%.

Step-by-step explanation:

To find the maximum percent sulfur content that the fuel can have, we need to consider the sulfur emissions limit and the efficiency of the sulfur emission control system.

(a) If 15,000 BTU/lb of coal is burned, we can use the sulfur emissions limit of 0.60 lb SO2 per million BTU to calculate the maximum sulfur content:

Maximum sulfur content = (Sulfur emissions limit / Heat input) * 100
Maximum sulfur content = (0.60 lb SO2 / 15,000,000 BTU) * 100

Simplifying the calculation gives:
Maximum sulfur content = 0.004% or 0.04 lb sulfur per 1,000 lb of coal.

(b) If 9,000 BTU/lb of coal is burned, we can use the same formula to calculate the maximum sulfur content:

Maximum sulfur content = (0.60 lb SO2 / 9,000,000 BTU) * 100
Maximum sulfur content = 0.0067% or 0.067 lb sulfur per 1,000 lb of coal.

Answer 2

The maximum sulfur content for coal that a power plant can have depends on the BTU content of the coal and the efficiency of the emission control system. For coal with 15,000 BTU/lb, the sulfur content can be up to 6.65%, and for coal with 9,000 BTU/lb, up to 11.12%.

Step-by-step explanation:

To determine the maximum percent sulfur content the fuel can have for a new coal-fired power plant equipped with a sulfur emission control system, we need to use the given emissions limit of 0.60 lb SO₂ per million BTU of heat and the efficiency of the sulfur control system, which is 70%. The efficiency tells us that only 30% of the sulfur will get converted into SO₂ . We also have two scenarios based on different BTU/lb coal values: (a) 15,000 BTU/lb coal and (b) 9,000 BTU/lb coal.

Calculations for Scenario (a):

Calculations for Scenario (a):

We're given:

Sulfur control efficiency: 70%

SO₂ emission limit: 0.60 lb SO₂ /million BTU

Coal energy content: 15,000 BTU/lb

To find the maximum percent sulfur that the coal can contain, we must consider the amount of sulfur resulting in 0.60 lbs of SO₂ per million BTUs. First, we calculate the amount of SO₂ that can be produced per pound of coal:

SO₂ emission limit × Coal energy content per pound:

0.60 lb SO₂ /million BTU × 1 million BTU / 15,000 BTU/lb = 0.040 lb SO₂ /lb coal

Remembering that only 70% of the SO₂ is controlled, we find the total SO₂ that could have been produced from the sulfur content in the coal:

0.040 lb SO₂ /lb coal / (1 - 0.70 control efficiency) = 0.133 lb SO₂ /lb coal before control.

Since each pound of sulfur produces 2 pounds of SO₂ :

0.133 lb SO₂ /lb coal × 1 lb sulfur / 2 lb SO₂ = 0.0665 lb sulfur/lb coal

Convert this into a percentage:

0.0665 lb sulfur/lb coal × 100 = 6.65%

Calculations for Scenario (b):

Following a similar process but with 9,000 BTU/lb coal, we get:

0.60 lb SO₂/million BTU × 1 million BTU / 9,000 BTU/lb = 0.0667 lb SO₂/lb coal after control.

Accounting for the control efficiency:

0.0667 lb SO₂/lb coal / (1 - 0.70 control efficiency) = 0.2223 lb SO₂/lb coal before control.

And converting to sulfur content:

0.2223 lb SO₂/lb coal × 1 lb sulfur / 2 lb SO₂ = 0.1112 lb sulfur/lb coal = 11.12%