DD133090B1 - METHOD FOR THE DISTILLATIVE REPRODUCTION OF SYNTHETIC RAW METHANOL - Google Patents

Description

"OB Leuna-T / discover Leuna,

"T / old Ulbricht"

LP 7739

Title of the invention

Process for the distillative workup of synthetic Rohniethanoi

Field of application of the invention

The invention relates to a process for the continuous, distillative workup of synthetic crude methanol to obtain pure dimethyl ether and pure methanol.

Characteristic of the known technical solutions

It is known to work up synthetic crude methanol by distillation in such a way that dimethyl ether is obtained from it in a first column and the bottom product is fed to a second column, in which most of the impurities boiling below ethanol are removed overhead and the resultant bottom product a third column, wherein it contains in a top product containing low-boiling impurities, a pure methanol side stream, two further side streams, the high-boiling

Contaminants contain and wastewater is decomposed as bottom product -wird.

(Μ · Μ · Karavaev et al., Promyslennyj sintez metanola, lzd · Chimioa, Moskva 1974, pp. 54-67).

Hachteil of such a process is once a relatively high expenditure on equipment and energy in the pre-distillation, since the first two columns of practically the entire amount of raw methanol are passed through and for the separation of the dimethyl ether as a Heinprodukt of a very large excess of! .. Ethanol a relatively high Return ratio is required. On the other hand, the quality of the pure methanol obtained is not sufficient for various applications. 3ine separation of certain impurities, e.g. A'thanol, requires an unreasonable amount of energy and high equipment costs.

Object of the invention

The invention is based on the aim to obtain pure dimethyl ether and pure methanol, to carry out the separation of the impurities contained in the hide ethanol with low apparatus and energy expenditure and a favorable material economy, and to achieve a low waste water load.

Presentation of 7 / esens the invention

It was the task to find a suitable procedure. According to the invention the object is achieved by a process for the continuous distillative workup of synthetic crude methanol containing water, dimethyl ether and lower and higher than methanol boiling impurities by 3ntätherungs-, flow and two-stage pure methanol distillation, wherein in the first pure methanol column containing a lower boiling impurities Separated overhead product and the bottom product of the second pure

methanol column, in which a top product, a pure methanol side stream, 'Yasser and higher-boiling impurities separated • are, achieved by distilling the crude methanol under a pressure of 12.5 - 20 at, while pure dimethyl ether stripping, a side product and a Sump product (I) separates, distilling the side product under about the same pressure, wherein a top product is recycled and withdrawn a bottom product, or that nan the crude methanol under a pressure of 1-5 at distilled while a gaseous overhead product (I) and a bottom product ( I), the gaseous overhead product (I) is distilled under a pressure of 12.5 to 15 minutes, removing pure dimethyl ether and a bottom product (II) and returning part of the bottom product (II) and the bottom product (I) distilled under a pressure of 1.5 to 5 at and with a reflux ratio of 0.8 to 2.0, taking off a pure methanol side stream and the bottom stream (I II) then distilled under a pressure of 3.0 to 10 at nit a reflux ratio of 1.5 to 5.

The first pure ethanol column is operated at pressures of 1, p to 5 at and a reflux ratio of O ₃ S to 2.0 and the second pure methanol column at higher pressures of 3.0 Ьіз 10 at and a reflux ratio of 1.5 to 5 operated. The reflux ratio represents the ratio of the amount of liquid flowing downwards in the top column of the respective column below the purity of the methanol withdrawal to the sum of the quantity withdrawn from the overhead product and the quantity of pure methanol.

Exemplary embodiments Example 1

Sin stream of 27> 9 t / h of synthetic crude methanol containing 1.2 t / h of dimethyl ether and inert gases, 1.2 t / h

Water, 250 ppm ethanol and 0.15 Gevjichts- ^ i-butanol as essential components arrives at the 45. Floor in the flow column, which has a total of 75 soils and is operated under a pressure of 20 at V over the top of this column 12.8 t / h of a substantially consisting of dimethyl ether gaseous stream nit at a temperature of 73 ⁰ C and withdrawn in a condenser down to a small residue of inert gases and dimethyl ether, which in a Henge of 0.05 t / h from the process be condensed. The S4ü3sig3trom leaving the condenser is divided in the ratio of etvja 11: 1, wherein one part serves as reflux for the forerunner and the other part as a pure dimethyl ether with less than 0.01 weight ?? ethanol is taken from the process as a final product in an amount of 1.15 t / h. At the bottom of the feed column, a liquid side stream consisting essentially of ethanol, dimethyl ether and most of the impurities boiling lower than methanol is withdrawn at a rate of 1.0 t / h and at the top in the side stream column containing 10 trays introduced. The gaseous overhead product enriched in this diethyl ethyl ether passes back to the feed column at the bottom of the column 57. The pressure in the two columns is equal. The bottom product obtained in the sidestream column is removed from the process at a rate of 0.2 t / h Most of the low-boiling impurities contained in the hay ethanol and 0.1 part by weight of dimethyl ether, the forerunner column, are operated with 3.5 t / h of high-pressure steam The resulting dibutcondensate is used to heat the sidestream column 25.5 t / h of a stream withdrawn and moved to the G. G. soil in the first pure methanol column This column has 75 trays and is operated at a pressure of 5 A. The gaseous overhead product of this column with a Hasse of 39.1 t / h enters the top condenser in which complete condensation takes place, the liquid formed

is divided into two sub-streams, one of which has an Ilasse of 38.0 t / h and serves as reflux for the first Reinmet hano! column, while the other sub-stream with an Ilasse of 1.0 t / h is removed from the process. 12.0 t / h of a stream are withdrawn from the first pure methanol column at the bottom and are removed from the process as pure methanol with an ethanol content of about 15 ppm. The reflux ratio is 2.0 × The bottom product of the first pure methanol column has a hate of 13. 4 t / h and arrives on the 12th floor in the second pure methanol column, which is operated at a pressure of 10 at and is equipped with 75 trays · The gaseous overhead product of this column is withdrawn in an Ilenge of 42.3 t / h and in Circulating evaporator condenses the first Reinmethonolkolonne. The resulting liquid stream is divided into a 2eilstrom with a Hasse of 41.9 t / h, which serves as reflux for the second pure methanol and a Teilstroni with a Hasse of 0.4 t / h, which is removed from the process becomes. At the bottom 65 of the second pure methanol column, a liquid side stream before. 11.7 t / h pure methanol with 250 ppm lit ha no Ige ha It withdrawn and removed as a final product from the process. In this column, the reflux ratio is 2.5 »" Furthermore, a liquid side stream is withdrawn at a close of 0.05 t / h at the 25 * bottom and also removed from the process at the bottom б is another Seitenstron in an Ilenge The water-leaner upper layer is removed from the process in a Hengo of 0.05 t / h, while the water-rich lower layer is removed from the second pure ethanol ethanol column Layer at the bottom 5 into the second pure-ethanol column The wastewater obtained during the work-up of the crude methanol is discharged into the sewer at a level of about 1.2 t / h The second pure methanol column is heated by means of a circulation evaporator, 17.5 The total steam consumption of the process is 21.0 t / h - corresponding to a specific

see steam consumption of 0.8 t per t Не Ѣ ha no 1 and dimethyl ether.

Example 2

Sin stream of 28.2 t / h synthetic crude methanol containing 1.2 t / h of dimethyl ether and inert gases, 1.2 t / h 7 / asser, 250 ppm ethanol and 0.15 wt iai-butanol as essential components arrives at the 45-tray in the feed column, which has a total of 75 trays and is operated under a pressure of 12.5 at. 10.8 t / h of a substantially consisting of dimethyl ether gaseous stream having a temperature of 53 ⁰ G are withdrawn overhead this column and in a condenser down to a small residue of inert gases and dimethyl ether, which in a!.! Close of 0, 05 t / h are removed from the process, condensed. The liquid stream leaving the condenser is divided in a ratio of about 8: 1, one part serving as reflux for the forerunner and the other part as pure dinethyl ether with 0.01% by weight ethanol as a final product in a length of 1 15 t / h of the product is taken off at the bottom of the forerunner column, a liquid side stream consisting essentially of ethanol, dinethyl ether and most of the impurities boiling lower than 1.0 t / h and introduced at the top of the bottom in the Seitenstronkolonne containing 10 trays. The enriched in Dinethyläther gaseous overhead product of this column returns to the bottom 56 in the flow column. There is pressure equalization between the two columns. The waste in the Seitenstrocikolonne bottom product is removed from the circulation in a Lenge ^ on 0.2 t / h from the process, 3s contains most of the low-boiling impurities contained in the crude methanol and 0.1 weight ^ dimethyl ether. The feed column is operated at 3.3 t / h of high-pressure steam. The resulting steam condensate is used sum heating the Seitenstroo column. From the Sumtif the pre-run column will be

Withdrawn 26.8 t / h of a stream and arrive at 8, soil in the first Reinmethano! Column. This column has 75 plates and is operated at a pressure of 1.5 at. The gaseous top product of this column with a mass of 31.0 t / h reaches the top condenser, in which complete condensation takes place divided into two sub-streams, one of which has a Hasse of 29.6 t / h and serves a return for the first pure methanol column, while the other partial flow with a pale of 1.4 t / h is removed from the Proseß. 11.0 t / h of a stream are withdrawn from the bottom of the first pure methanol column and removed from the process as pure methanol with an ethanol content of 1 ppm by weight. The return ratio is 1.5. The bottom product of the first pure methanol column has an Ilasse of 14.4 t / h and passes on 12 · bottom in the second pure methanol column, which is operated at a pressure of 3 at and equipped with 75 trays. The gaseous overhead product of this column is withdrawn in an amount of 32.5 t / h and condensed in the circulation evaporator of the first pure methanol column. The resulting liquid stream is divided into a Teilstroci with a Hasse of 31.5 t / h, which serves as reflux for dia second pure methanol column, and in a Teilstrorri with a hatch of 1.0 t / h, which is removed from the process becomes. At the bottom 65 of the second pure methanol column, a liquid side stream of 12.0 t / h of pure methanol with 400 ppm ethanol content is withdrawn and removed from the process as a final product.

Furthermore, a liquid side stream is withdrawn in a range of 0.1 t / h on the 25th floor and also removed from the process. At the bottom 6 another side stream is taken in an amount of 0.15 t / h from the second pure methanol, cooled by a cooler and separated in a separation vessel in two phases. The formed, less water-resistant top layer is removed from the process at a rate of 0.05 t / h, while the water-rich bottom layer

is returned to the bottom 5 in the column. The resulting in the processing of crude methanol water is discharged in an amount of about 1.2 t / h in the sewer,

The second reactor is operated at a reflux ratio of 1.5 and heated by means of a circulation evaporator, consuming 12.7 t / h of high pressure steam. The total steam consumption of the process is 16.0 t / h corresponding to a specific steam consumption of 0.6 t per t !! ethanol and dimethyl ether.

Example 3

33.8 t / h of a stream of synthetic crude methanol with 0.9 t / h of dimethyl ether including inert gases, 2.1 t / h of T / asser, 0.03 t / h of i-butanol, or an ethanol content of 300 ppm at the 60 'bottom injected into the run under a pressure of 1.0 at and provided with 70 practical trays feed column. The gaseous top product of this column consists essentially of dimethyl ether, ethanol, and impurities boiling lower than ethanol, including inert gases, and reaches the dephlegmator, but at a temperature of 35 ^° C., about 65% by weight. * condensed. Dio thereby resulting liquid phase leaves the top condenser and serves as reflux for the column, while the gas phase is withdrawn, compressed in a compressor and injected into the operated under a pressure of 12.5 at and containing 20 bottom dimethyl ether at the 10th floor. The gaseous overhead of this column passes into the reflux condenser, where it is condensed to the inert gases and small residues of dimethyl ether, which leave this condenser with an output of 0.05 t / h and discharged into the exhaust system, and a liquid stream with a Hasse of 2.65 t / h forms, t / h are withdrawn from the process of the 0.85 as a pure dimethyl ether with less than 0.01 wt -js _e !! ethanol, while the remaining part of the dimethyl

The bottom product of this column, which has a temperature of about 130 ⁰ C, is withdrawn in an amount of 0.2 t / h and removed from the process. The remaining part of the product obtained in the bottoms passes as partially vaporized stream at the bottom 65 in the upper part of the feed column · The dimethyl ether is heated with ca · 0.5 t / h low-pressure steam, which is fed to a circulation evaporator · From the feed column is a bottom stream in taken from a bed of 35.3 t / h and injected into the first pure methanol column G operated at a pressure of 1.5 atm and equipped with 75 trays in the sump. The head of this column leaves a gaseous stream in an amount of 44 »2 t / h, which is partially condensed in a dephlegmator, with the remaining gaseous phase injected at a rate of 2.5 t / h at the 65 x 3 anode into the Yorlauf column and the resulting liquid phase with a Hasse of 41.7 t / h as reflux At the bottom 63 of the first pure methanol column is a liquid side stream with a Hasse of 22.0 t / h of pure ethanol containing about 250 ppm of ethanol , withdrawn and removed as the final product aua the process. The reflux ratio in the first Heinmethanolkolonne is 0.3, from the bottom of this column, a stream with an Ilasse of 11.3 t / h and taken on the 12th floor in which operated under a pressure of 3.0 at and with 75 trays equipped second pure methanol column injected. From the top of this column 54.0 t / h of a gaseous stream are withdrawn and partially condensed in the circulation evaporator of the first pure methanol. The non-condensed part leaves as gaseous stream in a length of 5.6 t / h this circulation evaporator and enters the circulation evaporator of the Yorlaufkolonne in which it is partially condensed. The remaining gas phase escapes in an amount of 0.6 t / h from the circulation evaporator of the Yorlaufkolonne and passes with its own pressure on 65 · Soil in the Yorlaufkolonne · The resulting in the circulation evaporators of Yorlauf- and first pure methanol column liquid phases are combined and with a Mass of 53.4 t / h as reflux for the second pure methanol

used column. From the bottom 70 of the second pure methanol column, a liquid side stream with a LIasse of 8.4 t / h is withdrawn as pure methanol-Sndprodukt with an ethanol content of about 5 ppm »

The reflux ratio is 5.0 in this column. At the bottom of the second Heinmethanolkolonne 0.15 t / h of Äthanabaltigen side stream and at the 5 · bottom 0.10 t / h of another Seitenatromes be removed. The latter side stream is cooled by means of a cooler to a temperature of 40 ⁰ C and passes into a separating vessel, where a separation into two phases takes place. The resulting upper, poorer water phase is withdrawn in an Ilenge of about 0.05 t / h and removed from the process. The water-rich lower phase is added to the Sinspritzprodukt the afar Reinmethanolkolonne. 2.1 t / h of a wastewater stream are finally withdrawn from the bottom of this column. The second pure methanol column is heated with 21.5 t / h Ilochdruckdanpf. The specific steam consumption for the example given is 0.70 t of steam per t of pure ethanol and dimethyl ether.

Example 4

31.9 t / h of a stream of synthetic crude methanol with o, 9 t / h of dimethyl ether including inert gases, 2.1 t / h '.Yasser, 0.03 t / h of i-butanol and an iithanolgehalt of 3CO ppm are on 45 "Bottom injected into the operated under a pressure of 6.0 at and provided with 70 practical trays Torlaufkolonne. The gaseous overhead product of this column consists essentially of dimethyl ether, hetaryl and impurities boiling lower than ethanol, including inert gases, and enters the dephlegmator, where it partially condenses. The resulting liquid flush leaves the dephlegmator and serves as reflux for the column, while the gas phase is sucked off, compressed into a compressor and into the operated under a pressure of 15 at and 20 plates containing Disiethvlätherkolonne

The gaseous top product of this column passes into the reflux condenser, except for the inert gases and small residues of dimethyl ether, which leave this condenser with a cash flow of 0.05 t / h and are discharged into the waste gas network is condensed and forms a liquid stream with a Hasse of 3.1 t / h, are sucked from the 0.85 t / h as pure dimethyl ether with less than 0.01 wt .- ^ methanol from the process, while ' the remainder of the dimethyl ether column is fed to the reflux. The sump product of this column, which has a temperature of about 150 ⁰ C, is removed from circulation in a LIenge of 0.2 t / h from the process, Ss contains !! ethanol by far the largest £ ecause the low-boiling impurities contained in the crude methanol (except dimethyl ether). The remaining part of the resulting bottoms product passes as reflux into the feed column. The Dimeiftiylätherkolonne is heated with about 0.6 t / h of high pressure steam while the Torlaufkolonne consumes about 2.0 t / h of high pressure steam. From the '/ orlaufkolonne a bottoms stream is taken in a narrow! Of 30.8 t / h and injected into the operated under a pressure of 1.5 at and equipped with 75 plates first pure methanol column on the 15th floor. The head of this column leaves a gaseous stream in a LIengo of 49.2 t / h, which is condensed in a top condenser and divided into two streams, one of which has a Hasse of 1.0 t / h and is withdrawn from the process and the other of a length of 48.2 t / h serves as reflux for the first pure methanol column.

On the second column 68 of the first Reinnethanol column, a liquid side stream with a І.Іazze of 16.7 t / h of crude methanol containing 5 ppm of ethanol is drawn off and removed from the process as end product. The reflux ratio in the first pure methanol column is 1.8. From the bottom of this column, a stream with a Hasse of 12.6 t / h is removed and on the 12th floor in the operated under a pressure of 3.0 at and equipped with 75 plates second Reinmethanolkolonne

injected. 51.6 t / h of a gaseous stream are withdrawn from the top of this column and condensed in the circulation evaporator of the first pure methanol column. The obtained in the circulation evaporator of the first pure methanol column is liquid methanol is divided into two streams, one of which has a Hasse of 0.6 t / h and removed from the process and the other stream with a liasse of 51.0 t / h as reflux for the second pure-metal colony is used. From the bottom 70 of the second Reinmethaiiolkolonne a liquid side stream is withdrawn with a lieiiQQ of 9 »7 t / h as a pure ethanol ündprodukt with a ethanol content of 20 ppn.

The reflux ratio is 4.0 in this column. At the bottom of the second pure methanol column, 0.15 t / h of an ethanol-containing side stream and at 5.times.0.10 t / h of another side stream are taken off. The latter side stream is cooled by means of a cooler to a temperature of 40 ⁰ G and enters a separation vessel, where a separation into two phases takes place. The resulting upper, lower-water phase is sucked off in a length of about 0.50 t / h and removed from the sample. The water-rich lower phase is the 3in3pritzprodukt the second Reinaethanolkolonne added. Finally, 2.1 t / h of a wastewater stream are withdrawn from the bottom of this column. The second pure methanol column is heated with 20.5 t / h Hochdruckdamp. The specific steam consumption for the stated Веізрізі is 0.60 t Danpf per t pure ethanol and dimethyl ether.

Claims (1)

invention claim A process for the continuous distillative workup of synthetic crude methanol containing water, dimethyl ether and lower and higher than methanol boiling impurities by Entätherungs-, flow and two-stage pure methanol distillation, wherein in the first pure methanol column, a lower boiling impurities containing top product and separates the bottom product of second pure methanol column, in which a top product, a pure methanol side stream, "Vasser and higher-boiling impurities are separated, characterized in that distilling the crude methanol under a pressure of 12.5 - 20 at, thereby pure dimethylätier withdraws, a side product and a Bottom product (I) separates, distilling the side product under about the same pressure, with nanopan overhead product and withdrawing a bottom product, or by distilling the crude ethanol under a pressure of 1-6 at a gas overhead product (I) and a Sunpfprodukt (I) separates, сіaz gaseous head product (I) under a pressure of 12.5 - 15 at distilled, with пап гзіпеп Dinethyläther and a sump product (II) and a part de3 Sumpfproduktea (II) returns, and the 3unpfprodukt (I) under a pressure of 1.5 Ьіз 5 at and with a reflux ratio of 0.8 to 2.0 distilled, vbeiei disregarding a pure methanol side strora and the bottom stream (III) then under a pressure of 3.0 to 10 at a reflux ratio of 1.5 to 5 distilled.