Ethylene glycols
| 원료 | EO |
| 생산물 | ethylene glycols |
| 적용 | To procuce ethylene glycols (EG, DEG, TEG) from ethylene oxide (EO). |
| 설명 | Description:
The flowsheet shown is only one of several possible schemes. The raw materials to a free-standing glycol plant are refined ethylene oxide and pure water. These are mixed with recycle waters and pumped from a feed tank (1) to the hydration reactor after being preheated with hot recycle water and steam. When the glycol unit is part of a combined oxide/glycol plant, it is economically desirable to feed it bleed streams from the ethylene oxide unit. Since this stream can affect product qulity, additional proprietary treatment is necessary. The SD process is also able to simplify the combined oxide/glycol plants by feeding crude oxide solution (aqueous) from the ethylene oxide reaction unit directly to the glycol reaction and omitting the usual oxide refining step. In the glycol reactor (2), sufficient residence time is provided to react (noncatalytically) all of the ethylene oxide. The operating pressure of the reaction is controlled at a level that limits or avoids vaporization of ethylene oxide from the aqueous solution. The water-glycol mixture from the reactor is fed to the first stage (3) of a multiple stage evaporator, which is reboiled using high pressure steam. The remaining stages (4,5) of the evaportor operate at successively lower pressures, with the final stage (5) normally under vacuum. The evaporater water is recovered as condensate and recycled back to the glycol reaction feed mixing tank (1)- or to the oxide reaction section in combined oxide/glycol plants. The concentrated crude glycol solution from the final evaporation stage is then stripped of remaining water and light ends in the light ends column (6). The water-free glycol mixture is then fractionated in a series of vacuum distillation towers (7,8) to produce purified monoethylene glycol (EG) and byproduct diethylene glycol (DEG) and triethylene glycol (TEG). Product qulity: The glycol quality produced in these plants has set a new standard in the industry. Yields: Conversions and selectivities are essentially complete and quantitative. |
