294 BUSINESS ANALYTICS MODULE B LI N EA R PR O G R A M M I N G
hour of the day are assumed to be deterministic. In a real situation,
wide fluctuations will be experienced in a stochastic manner.
The optimal solution results in a considerable amount of idle
1. To develop the model:
Let: x1 = tons of phosphoric acid produced per day
x2 = tons of urea produced per day
x3 = tons of ammonium phosphate produced per day
x4 = tons of ammonium nitrate produced per day
The appropriate model equations then become:
Maximize 60x1 + 80x2 + 90x3 + 100x4 + 50x5 + 50x6 + 65x7 + 70x8
1
6
7
8
320
600
300
320
x
x
x
x
Supply constraint (with no curtailment):
5.5x1 + 7x2 + 8x3 + 10x4 + 15x5 + 16x6 + 12x7 + 11x8 36,000
(a) Supply constraint (20 percent gas curtailment):
5.5x1 + 7x2 + 8x3 + 10x4 + 15x5 + 16x6 + 12x7 + 11x8 28,800
(Note: 36,000 cu. ft. 103 0.80 = 28,800 cu. ft. 103)
(b) Supply constraints (40 percent gas curtailment):
5.5x1 + 7x2 + 8x3 + 10x4 + 15x5 + 16x6 + 12x7 + 11x8 21,600
(Note: 36,000 cu. ft. 103 0.60 = 21,600 cu. ft. 103)
With a 20 percent natural gas curtailment, the optimal pro-
1
2
3
4
5
6
7
8
320
200
270
300 Profit: $174,650
480
385
300
320
x
x
x
x
x
x
x
x
=
=
=
=
=
=
=
=
With a 40 percent natural gas curtailment, the optimal pro-
duction schedule, in tons/day, is:
1
8
320
320
x
x
=
=
2. Obviously, those products that have high energy consumption
factors must undergo extensive scrutiny to conserve energy. These
products include chlorine (15.0) and caustic soda (16.0). Energy
consumption is high for these chemicals because they are pro-
3. These products are all produced by large-volume, capital–
intensive plants. Emergency shutdowns often result in loss of raw
materials, pollution, potential personnel hazards, and equipment
damage. These plants are staffed for normal operations, and
4. Normal profit: $185,400/day
Profit with a 20 percent curtailment: $174,650/day
Profit with a 40 percent curtailment: $151,933/day