1. Technical Data And Process Description
1.1 Design conditions of the plant supplied by Buyer
1.1.1 Atmospheric air condition: (design condition)
Atmospheric pressure: 95kPa
Atmospheric temperature: 0˚C-35˚C
Relative humidity: 80%
Sea elevation: 1000m
1.1.2 Natural conditions in the plant site: (to be furnished by final user)
1.1.2.1 Atmospheric temperature:
Extreme Lowest temperature: 9˚C
1.1.2.2 Humidity:
Monthly highest relative humidity: 80%
Monthly Lowest relative humidity: 49%
1.1.2.3 Wind direction, velocity and pressure, and sunshine:
Wind velocity: 10 meters above the ground:
Largest wind velocity:4
1.1.2.4 Impurities of feed air:
CO2: ≤350ppm
C2H2: ≤2ppm
CnHn: ≤30ppm
Dust content: ≤30 mg/m³
1.1.2.5 Public engineering utilities
A. Cooling water:
Temp. of circulating cooling water: ≤30 ˚C
Pressure of circulating cooling water: 0.3MPa
Temp. rise: 8˚C
Return water pressure: 0.15MPa
Suspends: 50-60ppm
PH value: 7-8
Total hardness: 110---150ppm ascaco 3
Total alkali: 110---150ppm ascaco 3
CL in cooling water: 25---30ppm
Total solution: 300ppm (Max)
Electric conduction: 400---425micromho/cm 3
B. Steam conditions:
C. Electric Power:
Low tension: 380V±5%, frequency: 50Hz±5%
D. Instrument air: ≥0.5MPa(G), 25˚C, free of oil, dry.
1.2 Main Technical Data
1.2.1 Working condition O2: 100N m³/h±5% (480cylinders/24hrs)
Purity ≥99.6%
1.2.2 Processing air capacity: 1000N m /h
1.2.3 Discharge pressure of air compressor: 0.75MPa(G)
1.2.4 Product delivery pressure:
Oxygen: 15MPa
1.3 Process description
Air which was sucked in from air intake tower enters the suction air filter and after being removed of dust and other mechanical contaminants in it, it is compressed to the pressure of 0.7MPa by piston air compressor. Air from the air compressor is cooled to ~8˚C in the refrigeration unit, taken into the molecular sieve absorber for removing H2O, C2H2 and CO2. There are two molecular sieve absorbers which operate on a staggered cycle, i.e. one vessel is adsorbing the contained impurities while the other is being reactivated by waste nitrogen from the rectifying column.
Then the cleaned air is divided into two streams, one of them is taken into the rectifying column and cooled by the return waste nitrogen, oxygen and nitrogen through the main heat exchanger. The steam-liquid air mixture is taken into the lower column for rectifying, and herein the pure nitrogen of 99.99% from the top of the column enters into the evaporator-condenser and condensed by liquid oxygen from the upper column. A part of the liquid nitrogen is fed to the lower column as reflux. The other part after subcooling enters into the top of the upper column after throttled.
Another cleaned stream enters the main heat exchanger and get out from the middle of the main heat exchanger and enter into the turbine expansion to generate most refrigeration for need of the plant's operation. After the expander, air enters to the main heat exchanger, and get out from the cool box.
The product oxygen with the purity of 99.6% O 2 gained at the bottom of the upper column is warmed up through the heat exchanger and then delivered to the compressed oxygen system.
The product nitrogen of 99.99% N 2 gained at the top of the upper column is warmed up through the main heat exchanger and then taken to the compressed nitrogen system.
The waste nitrogen from the top of the upper column is warmed up, it goes to the regeneration molecular sieve adsorption.
1.4 Characteristics
1.4.1 Purifying air by molecular sieve adsorption makes the process simple, start-up and operation easy and safe, switch-over loss small and rectifying condition stable.
1.4.2 By using the pre-cooling system to cool the air with normal temp. Thus it makes the molecular sieve adsorbent in good condition.
1.4.3 For the use of the automatically controlled filter, the air bearings turbo-expander and the aluminum plate-fin heat exchanger, the stability, safety and reliability of the whole plant are improved greatly.
1.4.4 By using a new construction of the evaporator-condenser to avoid the accumulation of C-H chemical compounds.
| No. |
Components |
Power(Kw) |
Cooling water
(ton/hr) |
| Motor power |
Shaft power |
| 1 |
Air compressor |
90 |
85 |
8 |
| 2 |
Pre-cooling |
5.5 |
4.5 |
4 |
| 3 |
Fractionation heater |
27 |
9 |
0 |
| 4 |
Heater |
15 |
0 |
0 |
| 5 |
Oxygen compressor |
30 |
28 |
4 |
| 6 |
Total |
167 |
126.5 |
16 |
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