Release Characterization

Case Study

Major Emission Sources• Venting from the feed and product storage tanks• Off-gases from the scrubbers• Liquid wastes from the scrubbers• Emissions from the decanting and purification

columns• Emissions from the boilers• Fugitive emissions• Feed and product loading and off-loading emissions

Emission from Reactors, Stripper, Decanting and Purification Columns• Table 8.3-2: 1.5kg/1000 kg throughput (reactor vent),

0.2 kg/1000 kg throughput (stripper), 0.02 kg/ 1000 kg throughput (decanter), 0.7 kg/ 1000 kg throughput (distillation column vents).

• Assume (1) half of the emissions from reactor are cyclohexane (reactant) and half are ketone and alcohol (products) and (2) all of the emissions of the other units are products.

• Emission estimates: 0.8 kg cyclohexane/ 1000 kg throughput and 1.6 kg ketone and alcohol/100 throughput.

Emissions from Boilers• Rudd et al. (1981) suggested 1 value of 0.5 metric tons of fuel oil used per

metric ton of product.• Assume #6 fuel oil with 1% sulfur is used.

3 3

32

3 3

33

3

19 kg/10 L fuel oil 0.8 L/kg 500 kg fuel oil/ 10 kg product

= 7.6 kg SO /10 kg product

0.69 kg/10 L fuel oil 0.8 L/kg 500 kg fuel oil/ 10 kg product

= 0.3 kg SO /10 kg product

8 kg/10 L fuel oil 0.8 L/k

3

3x

3 3

3

g 500 kg fuel oil/ 10 kg product

= 3.2 kg NO /10 kg product

1.5 kg/10 L fuel oil 0.8 L/kg 500 kg fuel oil/ 10 kg product

= 0.6 kg PM/10 kg product

Fugitive Emissions

• Rough estimates are made on the basis of experience. Typical values: 0.5 – 1.5 kg per 1000 kg product.

• Use 0.5 kg/ 1000 kg throughput.• Emissions are evenly split between products

and reactants.

Emission Loss from Liquid Loading

L L 12.46

0.6 (4.1 14.7/760) 98 = 12.46530

= 0.1 lb/1000 gal = 0.15 kg/1000 kg throughput

S P MT

Losses from Tanks• Assume an annual production rate of 100 million pounds

per year.• A typical tank should hold 2-3 days of production capacit

y.• A tank 35 ft in diameter and 20 ft high with a fixed roof is

reasonable.• The tank is 80% full.• If the facility is located in Houston, TX, the data and proc

edure described in appendix C lead to an estimate of 0.5 kg emitted/1000 kg product for standing and working losses.

• We will assume that these are emissions of the feed material (cyclohexane) also.

Hedley et al. (1975)

Environmental Performance

Performance Indicators• Energy consumed from all sources within the

manufacturing or delivery process per unit of manufactured output.

• Total mass of material used directly in the product, minus the mass of the product, per unit of manufactured output.

• Water consumption per unit of manufactured product.• Emissions of targeted pollutants (those listed in TRI)

per unit of manufactured output.• Total pollutants per unit of manufactured output.

Material UseBased on data of Rudd et al. (1981) and Hedley et al. (1975). Rudd reports th

at the manufacture of 1 ton of cyclohexanol requires 1.64 tons of cyclohexane and 0.13 ton of NaOH. Cyclohexanone is produced at a rate of 0.38 tons per tons of cyclohexanol.

1.64 0.13 1.38Material Intensity 0.28

1 0.38

Water Use

• According to Hedley et al. (1975), 5000 gpm of cooling water and 10 gpm of process water are used for a 85000000 pounds per year facility.

• This leads to an estimate of 30 gallons of water per pound of product.

Energy Intensity and Pollutant Generation

• From literature, 0.4 fuel oil per kg product. On the basis of 150000 BTU per gallon fuel oil, the energy intensity is 7 kBTU per pound of product.

• From Table 8.3-12, pollutant generation is 0.3 lb/ lb product.

The performance indicators of the example process are at the high ends of the rangereported here. Improvements are needed!!!