The units are designed for oil well gas treating for subsequent transportation and use as a fuel for industrial and do-mestic heating systems.
Gas capacity: 50 000 – 500 000 m3/day. Gas treatment units are applied as single complex consisting of one or more processing trains and general-purpose equipment.
The following typical methods are used for gas dehydration:
- absorption dehydration (absorber);
- adsorption dehydration (adsorber);
- low-temperature separation (low-temperature separator).
Design
Design of gas dehydration unit is developed for single specific situation, considering initial water content of raw mate-rial, requirements for finished product and system structure. It includes the following:
- required dew point measurement;
- selection of process flow chart of gas treatment;
- calculation of concentration of initial and waste dehydrator solutions;
- selection of equipment for dehydration and regeneration sections.
Please fill the questionnaire for the equipment design.
ABSORPTION GAS TREATING UNIT
Structure and operation
Unstripped gas from collector comes to primary separator 1, where its liquid phase is separated, and comes to absorber 2, where it is dehydrated due to contact with concentrated glycol solution. Dehydrated gas passed through the filter 10 for fine glycol, comes to gas main or is distributed to users. The system includes regeneration tower 3, heat exchangers 5, 6 and 7, pumps 11 and 12, tanks 8 and 9.
Schematic diagram of absorber unit
The unit is mainly consists of:
| 1 | Gas separator Ððìàõ=6,3 MPa, Dñ=800 mm |
2 |
| 2 | Absorber Dà=1000 mm, Hàìàõ=10000 mm |
2 |
| 3 | Stripper Dä=400 mm, Häìàõ=7700 mm |
1 |
| 4 | Phase segregator Dð=1200 mm, Lð=2600 mm |
1 |
ADSORPTION GAS TREATING UNIT
Structure and operation
Unstripped gas from collector comes to primary separator 4, where its liquid phase is separated, and comes to adsorber 1, where it passes bottom-up through solid adsorbent layer that takes water vapors.
Dehydrated gas passed through the filter 7 comes to gas main or is distributed to users.
Dehydration lasts for 12 to 16 hours. After that, humid gas is forwarded through adsorber 2, and adsorber 1 is stopped and regenerated. For this purpose, dry gas is taken from the net and forwarded to preheater 3 to be heated to 180 - 200°Ñ.
The gas is forwarded to adsorber 1 and then to cooler 8.
Condensed water is collected in tank 5, whereas gas is repeatedly dried. Adsorbent regeneration lasts for 6 – 7 hours. After that adsorber is cooled for about 8 hours.
Schematic diagram of adsorber unit.
The unit is mainly consists of:
| 1,2 | Absorber Dà=1000 mm, Hàìàõ=10000 mm |
4 |
| 3 | Gas heating furnace Qï=0, 4 Gcal/hour |
2 |
| 4 | Gas separator Ððìàõ=6,3 MPa, Dñ=800 mm |
2 |
LOW-TEMPERATURE GAS SEPARATION UNIT
Structure and operation
Unstripped gas from collector comes to intake separator 1, where its liquid phase and unstable hydrocarbon con-densate are separated. Then the gas comes to heat exchanger 2 of ‘gas-gas’ type for cold recovery of throttled gas, where it is chilled on 10-15 °Ñ or more.
Then the gas is forwarded to throttle 3, and due to the Joule –Thomson’ effect the temperature falls on 10 - 30 °Ñ . Further, the processed gas along the liquid phase comes to low-temperature separator 4, where its liquid phase (water and hydrocarbons), is separated, and cold gas free of water and heavy hydrocarbons (Ñ5+â) passes through recuperative heat exchanger 2 in counterflow with ‘unstripped’ gas and comes to gas line as a product gas.
Efficiency of gas cooling by the way of isoenthalpic process can reach 10-12 °Ñ per 1 MPa of free pressure differ-ence. Inhibitor (glycol, methanol) is injected both prior to heat exchanger 2, and prior to throttle in the amount re-quired for hydrate-free operation.
Water phase (i.e. aqueous solution of inhibitor) and hydrocarbon condensate from separator 4 come to segregator 6, where hydrocarbon condensate is partially degassed. Then condensate is forwarded to stabilization unit and pumped into oil pipeline. Wasted aqueous solution of inhibitor is forwarded to regeneration section.
Schematic diagram of low-temperature separation
The unit is mainly consists of:
| 1 | Gas separator Ððìàõ=6,3 MPa, Dñ=800 mm |
1 |
| 2 | Gas-gas heat-exchanger (annular tube) | 1 |
| 3 | Throttling device | 1 |
| 4 | Gas separator Ððìàõ=4,0 MPa, Dñ=1200 mm |
1 |
