Title of Invention	'A METHOD FOR THE SYNTHESIS OF METHANOL AND A SYSTEM THEREOF".
Abstract	Method for the synthesis of methanol from hydrogen, carbon monoxide and carbon dioxicte under pressure wherein desulphurated natural gas is sent forward to a reformer and subsequently the synthesis gas is sent forward to methanol gyntiiesis,eharaeterized in that after passing through the reformer, out of the synthesis gas How, a side stream is supplied to a methauol preliminary reactor, the methanol created in the preliminary reactor is supplied to the methanol flow leaving the mefhanol synthesis of the main flow, and a synthesis gas flow that is not converted in the methanol preliminary reactor is supplied oace more to fee main flow before the methanol synthesis, wherein in the area, of this supply, at the same time an additional synthesis gas is given up which compensates the loss that has arisen.

Title of Invention

'A METHOD FOR THE SYNTHESIS OF METHANOL AND A SYSTEM THEREOF".

Abstract

Method for the synthesis of methanol from hydrogen, carbon monoxide and carbon dioxicte under pressure wherein desulphurated natural gas is sent forward to a reformer and subsequently the synthesis gas is sent forward to methanol gyntiiesis,eharaeterized in that after passing through the reformer, out of the synthesis gas How, a side stream is supplied to a methauol preliminary reactor, the methanol created in the preliminary reactor is supplied to the methanol flow leaving the mefhanol synthesis of the main flow, and a synthesis gas flow that is not converted in the methanol preliminary reactor is supplied oace more to fee main flow before the methanol synthesis, wherein in the area, of this supply, at the same time an additional synthesis gas is given up which compensates the loss that has arisen.

Full Text	The invention is directed at a method for the synthesis of methanol from hydrogen, carbon monoxide- and carbon dioxide under pressure, in particular to increase the yield of methods thai have already been uaed, wherein deaulphurated natural gas is sent forward to a reformer and subsequently the synthesis gas is sent forward to methanol synthesis. A range of plants or methods for catalytic methanol synthesis are known, wherein the specifications DE-21 17 060, DE-25 29 591, DE-32 20 995, DE-35 18 362, US-29 04 575 and DE 41 00 632 can be named here BE examples of wealth of solutions. Normally, a methanol production plant is operated in conjunction with a paint for the productionon of Synthesi gas, with both plants being ditiiruaiufied in such a way that the synthesis gas that is produced precisely covers the requirements of the methanof-producing catalyst of the synthesis gas circulation, and in particular is composed gtothiometrically in relation to the following reactions, wherein only two of them are linearly dependent on one other. CO + 2H2 CH3OH -90.84kJ/mol (1) CO2 + H2 CO +H2O+ 41.20kJ/mol (2) CO2 +3H2 CH3OH +H2O- 49.64kJ/mol (3) According to these reaction equations, the following applies for a stochiometric synthesis gas; \ see original for equation] -2- where ei represents the gas concentrations of the respective starting materials on a molar basis. Such a synthesis gas is usually produced in a primary reformer alone or together with a secondary reformer, or in a similar gas production plants, in a single-lane manner. A plant of this type ean be retrofitted only with difficulty when existing production capacities need to be expanded. In general, in such cases a further plant has to be constructed according to the pattern of the old plant, and syaergistic effects of the two plants are not to be expected. Also problematic is the incorporation of foreign synthetsis gas, which is often available cheaply after the shutdown of other plants in larger works, but which due to other compositions, usually due to too large a. proportion of compounds containing carbon ('C-proportion") cannot be used for methanol production without expensive further reprocessing. The task of the invention is therefore to extend the known method such that the disadvantages that have become known are overcome, economical retrofitting of existing plants is achieved, and foreign synthesis gas can be used. With a method of the type designated at the outset this task is solved in accordance with the invention in that after passing through the reformer, out of the synthesis gas flow, a side stream is supplied to a methaol preliminary reactor, the methanol created in the preliminary reactor is supplied to the methanol flow leaving the methanol synthesis of the main flow, and a synthesis gas flow that is not converted in the methanol preliminary reactor is supplied once more to the main flow before the methanol synthesis, wherein in the area of this supply, at the same time an additional synthesis gas is given up which compensates the loss that has arisen The methanol preliminary reactor that is used, as well as the usual appliances for the conditioning of the synthesis gas and the condensation and separation of the methanol produced, can be retrofitted, wherein it is thus possible to achieve an increase in me production capacity of up to 57% in relation to the capacity of the- old plant Naturally -3- this concept is not restricted to the retrofitting of old plants, but can also be taken into account to advantage in new designs. Further embodiments of the invention result from the dependent claims. Here, it can be envisaged that as an additional synthesis gas, a foreign synthesis gas flow from a separate synthesis gas source is used, or a synthesis gas that has been extracted from the natural gas charge flow as a bypass, has been led via an antotherm reformer, or that has originated from another synthesis gas production. Here, the foreign gas synthesis can originate from a combined autotherm reformer (also called a "CAR") or a reactor for partial oxidation, which can be retrofitted and is considerably more economical in construction that the apparatuses that are usually used for the production of the synthesis gas with precisely matching gas composition. In this case, it is also possible to use a part of the waste gas of the methanol production plant, which otherwise would be usable only as a furnace gas, as a further charge gas in an autothermal reformer or a combined autothermal reformer. It can be advantageous here if the additional synthesis gas, which compensates the loss and is supplied to the main synthesis gag flow before the methanot synthesis, is taken from a combined autotherm reformer and/or a reactor for partial oxidation, or from another synthesis gas production, as is likewise envisaged by this invention. In a further embodiment of the invention, the waste heat that is to be led off during the cooling of the methanol synthesis gas mixture from the methanol preliminary reactor can be used to operate an absorption-type refrigerating machine. The cold that is produced is used to cool the synthesis gas emerging from the reformers before its compression, thus saving on compression energy. According to the invention, the compression energy that is saved can be used to compress the foreign synthesis gas or the additional synthesis gas that is created in retrofitted reformers. Furthermore, the cold mat is produced can be used to condense out more methanol after the methanol reactors. Where the primary aim is to save on -4- investment costs, and energy costs are low, it can be economical to do without the utilization of waste heat and to use a- conventional refrigeration machine, e,g, one operated with ammonia as a refrigerant, instead of an absorption-type refrigerating machine. When mixing the foreign synthesis gas with the synthesis gas that is obtained from the methanol preliminary reactor of the methanol that has been produced has been separated off, care must be taken that the mixture mat is obtained approximately corresponds to the composition of the synthesis gas that was originally diverted, fully covers the conditions for the existing methanol circulation, and that the original synthesis can be operated within the framework of the catalyst conditions. In order to ensure this, at least the following must apply for the molar concentrations of th e foreign synthesis gas: 0.8 number 2. A former embodiment of the invention consists in the fact that a mixture of H2 and CO2 is uaed as additional synthesis gas, wherein the CO2 that is present in the mixture originates from the flue gas of a firing place or from me waste gas of a CO2 scrubbing plant in an ammonia plant (fig.2). Utilisation of the CO2 originating from combustion in the additional synthesis gas has the great advantage that is CO2 need not be discharged into the atmosphere, but is used for synthesis, in accordance with the regulations. In [Ms] embodiment, it is envisaged that the CO2 originates from a flue gas cleansing plant of a firing place, for example the firing place- of the primary reformer. 'Hue procedure has the additional advantagae that the climate-changing CO2 is brought into the substance circulation, so that for example a "greenhouse gas emission tax-" would no longer have to be paid for this, which makes the procedure considerably more economical. .5- Besides the utilization of the CO2 from combustion, the CO2 can also originate from the CO2 scrubbing plant of an NH3 plant; an ammonia plant of this type is not described in further detail in the following description. To solve the aforementioned task, the invention also envisage a plant for methanol synthesis, in particular for carrying out the method in accordance with one of the preceding claims, with a natural gas supply conduit to a reformer and a downstream methanol synthesis, wherein according to the invention such a plant is characterized by - a branch conduit for a side stream of the syntiiesis gas leaving the secondary reformer, - amethanol preliminary reactor in the side stream, - a methanol supply conduit to the methanol main flow leaving the methanol synthesis - a return conduit which guides non-converted synthesis gas from the methanol preliminary reactor into the synthesis gas main flow before the methanol synthesis, as well as a supply conduit before fee methanol synthesis, for the supply of sy nthesis gas that compensates losses. In a further embodiment, the plant in accordance with this invention is characterized by the feet that an autotherm reformer is switched parallel to the reformer, wherein the synthesis gas that is leaving is used at least in part as synthesis gas that compensate losses. -6- According to the invention, a flue gas scrubbing plant can also be provided for the the gas leaving the primary reforms, as well as a CO2 supply conduit for making available the foreign or additional synthesis gas, as well as supply conduit for supplying foreign H2 (fig.2), wherein it can be expedient to deploy a supply conduit for supplying foreign CO2 from a CO2 scrubbing plant in NH3 plant, as well as a supply conduit for supplying foreign H2, as is likewise envisaged in an embodiment in accordance with the invention. Further details, advantages and features of the invention result from the following description, as well as on the basis of the drawing. In a heavily simplified for the drawing snows me following; Fig. 1 shows a modular diagram of a plant in accordance with the invention, and Figs. 2 and 3 show modified examples of the modular diagram, in a comparable representation: The description of the retrofitting capability of a plant I serves as an example here, with me functioning of the method also being described simultaneously: A method production plant ! which is already in operation and which comprises a primary reformer 2? a secondary reformer 3 and a methanel synthesis 4, is retrofitted with a. methatiol preliminary reactor 5 and an autothermai reformer 6 . Desulphurated nahiral gas 7 is used as a charge substance; this is guided into both the primary reformer 2 and the autothermal reformer 6, with charge input substances that are not shown here, e.g. water vapor and oxygen, being added. In me primary reformer 2 raw synthetic gas is produced from this, which essentially comprises hydrogen, carbon monoxide, carbon dioxide and unconverted water vapour and natural gas. In the secondary reformer 3, with oxygen the remaining natural gas is converted to hydrogen and carbon monoxide. Here the conditions in me primary reformer 2 and in the iBPcoudary reformer 3 are set such that a stochiometric eynmeisis gap 8 is produced in accordance with the equations (1) to (4). From this, the side stream 9 is diverted off -7- and guided to the methanol preliminary reactor 5. In the methanol preliminary reactor 5, a part of this synthesis gas is converted, is condensed out, separated off, and led off as additional methanol 10. The remaining sub-Btochiometric synthesis gas 11 is added to the original synthesis gas main flow 12 once more. In order to avoid the occurrence of a gub-stochiometric mixture, the super-stoehiomstric synthetic gas 13 is likewise added to the synthesis gas main flow 12, This super-stochiomeiric synthesis gas 13, for its part comprises foreign synthesis gas 14 and/or additional synthesis gas 15 mat has been specially produced for this purpose in the retrofitted autotheraial reformer 6, wherein the autothermal reformer 6 is to be understood as an example only. With the two additions to (he synthesis gas main flow 12, the stocfaiometric synmesis gas 16 is formed, which has a composition equivalent to the Btoctuometric synthesis gas 8. With this, mafhsaiol 17 fa created in the conventional manner in the old methane! synthesis 4; together with the additional methanol 10, this forms the new product metuanof 18. In a modification of the plant according to fig. 1, fig. 2 shows a plant in which the conduit 14, which supplies the foreign synthesis gas, is supplied with CO2 via a conduit 19 and with foreign Ha via a conduit 20. llie COa of the conduit 19 originates .from a. flue gas scnibhing plant. 21, which receives the flue gas via the conduit 11 from tit© primary reformer 2, llie flue gas (scrubbing plant 21 cleanses fee flue gas, leads die CO2 to the conduit 19 and the waste gas to a chimney 23, indicated oriJy symbolically, It ems be seen thdt thip waste gas is free of COa. Fig. 3 shows the alternative in whidi,, via. the conduit l°a> foreign CO2 is supplied to the conduit 14 for the fbreigo synthesis gas, wherein this foreign CO] originates from an ammonia plant - not shown in greater detail - from me CO?, scrubbing plant there. Here too, forvigp lh is supplied to the system via. a conduit 20a Clearly, in particular iii the case of the variant according to ilg. 2, wholly closed CDs circulations ore possible, i.e. tiiess pimts work in such a way thai no COj has to .8- bo discharged into Ihe environment The following example figures in Table 1 provide greater clarification. Here, it is assumed that there exists en old plant for the- production of 3000 tonaes of methanol per day, the capacity of which is to be expanded by around 35%. The figures relate to the reference numbers in fig. 1. -9. -10- WE CLAIM 1. Method for the synthesis of methanol from hydrogen, carbon monoxide and carbon dioxide under pressure, wherein desulphurated natural gas is sent forward to a reformer and subsequently the synthesis gas is sent forward to memanoi synthesis,characterized in that after passing through the reformer, out of the synthesis gas flow, a side stream is supplied to a methanol preliminary reactor, the memanoi created in the preliminary reactor is supplied to the methanol flow leaving me methanol synthesis of the main flow, and a synthesis gas flow that is not converted in the methanol preliminary reactor is supplied once more to the main flow before me methanol synthesis, wherein in the area of this supply, at the same time an additional synthesis gas is given up which compensates the loss that has arisen. 2. Method as claimed in claim 1, wherein an additional synthesis gas, a foreign synthesis gas flow from a separate synthesis gas source is used, or a synthesis gas that has been extracted from the natural gas charge flow as a bypass, has been led via an autotherm reformer, or that has originated from another synthesis gas production. 3. Method as claimed in one of the preceding claims, wherein the additional synthesis gas, which compensates the loss and is supplied to the main synthesis gas flow before the niethanol systems, is taken from a combined autotfaerm reformer and/or a reactor for partial oxidation, or from another synthesis gas production. 4. Method as claimed in one of th e preceding claims, wherein the waste heat of the additional inethanol preliminary reactor is used to operate an absorption-type refrigerating machine, wherein the cold that is produced is used to cool a synthesis gas compression and/or unused compression energy is used for the compression of foreign synthesis gas. 5. Method as claimed in one of the preceding claims, wherein a mixture of H2 and CO2 is used as additioaal synthesis gas, wherein the CO2 that is present in the mixture originates from the flue gas of a firing place or from the waste gas of a CQz scrubbing plant in an ammonia plant -11- 6. Method as claimed in one of the preceding claims wherein the CO2 originates from a Sue gas cleansing plant of a firing place, for example the firing place of the primary reformer. 7. Plant for methanol synthesis with a natural gas supply conduit to a reformer and a downstream methanol synthesis wherein; - a branch conduit 9 for a side stream of the synthesis gas (8) leaving the ¦ secondary reformer (3), a mothanol preliminary reactor (5) in the side stream, a methanol supply conduit (10) to the methanol main flow (17) leaving the methanol synthesis (4). - A return conduit (11) which guides non-converted synthesis gas from the methanol preliminary reactor (5) into the synthesis gas main flow (12) before the- methanol synthesis (4), as well as - a supply conduit (13) before the methanol synthesis (4)., for the supply of synthesis gas that compensates losses. 8. Plant as claimed in claim 7, wherein an outotherm reformer (6) is switched parallel to the reformer (2,3), wherein the synthesis gas (15) that is leaving is used at least in part as synthesis gas that compensates losses. 9, Plant as claimed in claim 7 or 8, wherein a flue gas scrubbing plant (21) for thee flue gas leaving the primary reformer (2), as well as a CO3 supply conduit (19) for making available the foreign or additional synthesis gas (14}, as well as Bupply conduit (20) for supplying foreign H2 (fig.2) 10. Plant as claimed in claim 7 or one of the following ones wherein a supply conduit (19a) for supplying foreign CO2 from a CO2 scrubbing plant in the NH3 plant, as well as a supply conduit (20c) for supplying foreign H2 (fig. 3). Method for the synthesis of methanol from hydrogen, carbon monoxide and carbon dioxicte under pressure wherein desulphurated natural gas is sent forward to a reformer and subsequently the synthesis gas is sent forward to methanol gyntiiesis,eharaeterized in that after passing through the reformer, out of the synthesis gas How, a side stream is supplied to a methauol preliminary reactor, the methanol created in the preliminary reactor is supplied to the methanol flow leaving the mefhanol synthesis of the main flow, and a synthesis gas flow that is not converted in the methanol preliminary reactor is supplied oace more to fee main flow before the methanol synthesis, wherein in the area, of this supply, at the same time an additional synthesis gas is given up which compensates the loss that has arisen.

Full Text

The invention is directed at a method for the synthesis of methanol from hydrogen, carbon monoxide- and carbon dioxide under pressure, in particular to increase the yield of methods thai have already been uaed, wherein deaulphurated natural gas is sent forward to a reformer and subsequently the synthesis gas is sent forward to methanol synthesis.
A range of plants or methods for catalytic methanol synthesis are known, wherein the specifications DE-21 17 060, DE-25 29 591, DE-32 20 995, DE-35 18 362, US-29 04 575 and DE 41 00 632 can be named here BE examples of wealth of solutions.
Normally, a methanol production plant is operated in conjunction with a paint for the productionon of Synthesi gas, with both plants being ditiiruaiufied in such a way that the synthesis gas that is produced precisely covers the requirements of the methanof-producing catalyst of the synthesis gas circulation, and in particular is composed gtothiometrically in relation to the following reactions, wherein only two of them are linearly dependent on one other.
CO + 2H2 CH3OH -90.84kJ/mol (1)
CO2 + H2 CO +H2O+ 41.20kJ/mol (2)
CO2 +3H2
CH3OH +H2O- 49.64kJ/mol (3)
According to these reaction equations, the following applies for a stochiometric synthesis gas;
\ see original for equation]
-2-

where ei represents the gas concentrations of the respective starting materials on a molar basis.
Such a synthesis gas is usually produced in a primary reformer alone or together with a secondary reformer, or in a similar gas production plants, in a single-lane manner.
A plant of this type ean be retrofitted only with difficulty when existing production capacities need to be expanded. In general, in such cases a further plant has to be constructed according to the pattern of the old plant, and syaergistic effects of the two plants are not to be expected. Also problematic is the incorporation of foreign synthetsis gas, which is often available cheaply after the shutdown of other plants in larger works, but which due to other compositions, usually due to too large a. proportion of compounds containing carbon ('C-proportion") cannot be used for methanol production without expensive further reprocessing.
The task of the invention is therefore to extend the known method such that the disadvantages that have become known are overcome, economical retrofitting of existing plants is achieved, and foreign synthesis gas can be used.
With a method of the type designated at the outset this task is solved in accordance with the invention in that after passing through the reformer, out of the synthesis gas flow, a side stream is supplied to a methaol preliminary reactor, the methanol created in the preliminary reactor is supplied to the methanol flow leaving the methanol synthesis of the main flow, and a synthesis gas flow that is not converted in the methanol preliminary reactor is supplied once more to the main flow before the methanol synthesis, wherein in the area of this supply, at the same time an additional synthesis gas is given up which compensates the loss that has arisen
The methanol preliminary reactor that is used, as well as the usual appliances for the conditioning of the synthesis gas and the condensation and separation of the methanol produced, can be retrofitted, wherein it is thus possible to achieve an increase in me production capacity of up to 57% in relation to the capacity of the- old plant Naturally
-3-

this concept is not restricted to the retrofitting of old plants, but can also be taken into account to advantage in new designs.
Further embodiments of the invention result from the dependent claims. Here, it can be envisaged that as an additional synthesis gas, a foreign synthesis gas flow from a separate synthesis gas source is used, or a synthesis gas that has been extracted from the natural gas charge flow as a bypass, has been led via an antotherm reformer, or that has originated from another synthesis gas production.
Here, the foreign gas synthesis can originate from a combined autotherm reformer (also called a "CAR") or a reactor for partial oxidation, which can be retrofitted and is considerably more economical in construction that the apparatuses that are usually used for the production of the synthesis gas with precisely matching gas composition. In this case, it is also possible to use a part of the waste gas of the methanol production plant, which otherwise would be usable only as a furnace gas, as a further charge gas in an autothermal reformer or a combined autothermal reformer.
It can be advantageous here if the additional synthesis gas, which compensates the loss and is supplied to the main synthesis gag flow before the methanot synthesis, is taken from a combined autotherm reformer and/or a reactor for partial oxidation, or from another synthesis gas production, as is likewise envisaged by this invention.
In a further embodiment of the invention, the waste heat that is to be led off during the cooling of the methanol synthesis gas mixture from the methanol preliminary reactor can be used to operate an absorption-type refrigerating machine. The cold that is produced is used to cool the synthesis gas emerging from the reformers before its compression, thus saving on compression energy.
According to the invention, the compression energy that is saved can be used to compress the foreign synthesis gas or the additional synthesis gas that is created in retrofitted reformers. Furthermore, the cold mat is produced can be used to condense out more methanol after the methanol reactors. Where the primary aim is to save on
-4-

investment costs, and energy costs are low, it can be economical to do without the utilization of waste heat and to use a- conventional refrigeration machine, e,g, one operated with ammonia as a refrigerant, instead of an absorption-type refrigerating machine.
When mixing the foreign synthesis gas with the synthesis gas that is obtained from the methanol preliminary reactor of the methanol that has been produced has been separated off, care must be taken that the mixture mat is obtained approximately corresponds to the composition of the synthesis gas that was originally diverted, fully covers the conditions for the existing methanol circulation, and that the original synthesis can be operated within the framework of the catalyst conditions. In order to ensure this, at least the following must apply for the molar concentrations of th e foreign synthesis gas: 0.8 number 2.
A former embodiment of the invention consists in the fact that a mixture of H2 and CO2 is uaed as additional synthesis gas, wherein the CO2 that is present in the mixture originates from the flue gas of a firing place or from me waste gas of a CO2 scrubbing plant in an ammonia plant (fig.2).
Utilisation of the CO2 originating from combustion in the additional synthesis gas has the great advantage that is CO2 need not be discharged into the atmosphere, but is used for synthesis, in accordance with the regulations.
In [Ms] embodiment, it is envisaged that the CO2 originates from a flue gas cleansing plant of a firing place, for example the firing place- of the primary reformer.
'Hue procedure has the additional advantagae that the climate-changing CO2 is brought into the substance circulation, so that for example a "greenhouse gas emission tax-" would no longer have to be paid for this, which makes the procedure considerably more economical.
.5-

Besides the utilization of the CO2 from combustion, the CO2 can also originate from the CO2 scrubbing plant of an NH3 plant; an ammonia plant of this type is not described in further detail in the following description.
To solve the aforementioned task, the invention also envisage a plant for methanol synthesis, in particular for carrying out the method in accordance with one of the preceding claims, with a natural gas supply conduit to a reformer and a downstream methanol synthesis, wherein according to the invention such a plant is characterized by
- a branch conduit for a side stream of the syntiiesis gas leaving the
secondary reformer,
- amethanol preliminary reactor in the side stream,

- a methanol supply conduit to the methanol main flow leaving the methanol
synthesis
- a return conduit which guides non-converted synthesis gas from the methanol
preliminary reactor into the synthesis gas main flow before the methanol
synthesis, as well as
a supply conduit before fee methanol synthesis, for the supply of sy nthesis gas that compensates losses.
In a further embodiment, the plant in accordance with this invention is characterized by the feet that an autotherm reformer is switched parallel to the reformer, wherein the synthesis gas that is leaving is used at least in part as synthesis gas that compensate losses.
-6-

According to the invention, a flue gas scrubbing plant can also be provided for the the gas leaving the primary reforms, as well as a CO2 supply conduit for making available the foreign or additional synthesis gas, as well as supply conduit for supplying foreign H2 (fig.2), wherein it can be expedient to deploy a supply conduit for supplying foreign CO2 from a CO2 scrubbing plant in NH3 plant, as well as a supply conduit for supplying foreign H2, as is likewise envisaged in an embodiment in accordance with the invention.
Further details, advantages and features of the invention result from the following description, as well as on the basis of the drawing. In a heavily simplified for the drawing snows me following;
Fig. 1 shows a modular diagram of a plant in accordance with the invention, and
Figs. 2 and 3 show modified examples of the modular diagram, in a comparable representation:
The description of the retrofitting capability of a plant I serves as an example here, with me functioning of the method also being described simultaneously:
A method production plant ! which is already in operation and which comprises a primary reformer 2? a secondary reformer 3 and a methanel synthesis 4, is retrofitted
with a. methatiol preliminary reactor 5 and an autothermai reformer 6 . Desulphurated nahiral gas 7 is used as a charge substance; this is guided into both the primary reformer 2 and the autothermal reformer 6, with charge input substances that are not shown here, e.g. water vapor and oxygen, being added. In me primary reformer 2 raw synthetic gas is produced from this, which essentially comprises hydrogen, carbon monoxide, carbon dioxide and unconverted water vapour and natural gas. In the secondary reformer 3, with oxygen the remaining natural gas is converted to hydrogen and carbon monoxide. Here the conditions in me primary reformer 2 and in the iBPcoudary reformer 3 are set such that a stochiometric eynmeisis gap 8 is produced in accordance with the equations (1) to (4). From this, the side stream 9 is diverted off
-7-

and guided to the methanol preliminary reactor 5. In the methanol preliminary reactor 5, a part of this synthesis gas is converted, is condensed out, separated off, and led off as additional methanol 10. The remaining sub-Btochiometric synthesis gas 11 is added to the original synthesis gas main flow 12 once more.
In order to avoid the occurrence of a gub-stochiometric mixture, the super-stoehiomstric synthetic gas 13 is likewise added to the synthesis gas main flow 12, This super-stochiomeiric synthesis gas 13, for its part comprises foreign synthesis gas 14 and/or additional synthesis gas 15 mat has been specially produced for this purpose in the retrofitted autotheraial reformer 6, wherein the autothermal reformer 6 is to be understood as an example only.
With the two additions to (he synthesis gas main flow 12, the stocfaiometric synmesis gas 16 is formed, which has a composition equivalent to the Btoctuometric synthesis gas 8. With this, mafhsaiol 17 fa created in the conventional manner in the old methane! synthesis 4; together with the additional methanol 10, this forms the new product metuanof 18.
In a modification of the plant according to fig. 1, fig. 2 shows a plant in which the conduit 14, which supplies the foreign synthesis gas, is supplied with CO2 via a conduit 19 and with foreign Ha via a conduit 20. llie COa of the conduit 19 originates .from a. flue gas scnibhing plant. 21, which receives the flue gas via the conduit 11 from tit© primary reformer 2, llie flue gas (scrubbing plant 21 cleanses fee flue gas, leads die CO2 to the conduit 19 and the waste gas to a chimney 23, indicated oriJy symbolically, It ems be seen thdt thip waste gas is free of COa.
Fig. 3 shows the alternative in whidi,, via. the conduit l°a> foreign CO2 is supplied to the conduit 14 for the fbreigo synthesis gas, wherein this foreign CO] originates from an ammonia plant - not shown in greater detail - from me CO?, scrubbing plant there. Here too, forvigp lh is supplied to the system via. a conduit 20a
Clearly, in particular iii the case of the variant according to ilg. 2, wholly closed CDs circulations ore possible, i.e. tiiess pimts work in such a way thai no COj has to
.8-

bo discharged into Ihe environment
The following example figures in Table 1 provide greater clarification. Here, it is assumed that there exists en old plant for the- production of 3000 tonaes of methanol per day, the capacity of which is to be expanded by around 35%. The figures relate to the reference numbers in fig. 1.
-9.

-10-

WE CLAIM
1. Method for the synthesis of methanol from hydrogen, carbon monoxide and carbon dioxide under pressure, wherein desulphurated natural gas is sent forward to a reformer and subsequently the synthesis gas is sent forward to memanoi synthesis,characterized in that after passing through the reformer, out of the synthesis gas flow, a side stream is supplied to a methanol preliminary reactor, the memanoi created in the preliminary reactor is supplied to the methanol flow leaving me methanol synthesis of the main flow, and a synthesis gas flow that is not converted in the methanol preliminary reactor is supplied once more to the main flow before me methanol synthesis, wherein in the area of this supply, at the same time an additional synthesis gas is given up which compensates the loss that has arisen.
2. Method as claimed in claim 1, wherein an additional synthesis gas, a foreign
synthesis gas flow from a separate synthesis gas source is used, or a synthesis gas that
has been extracted from the natural gas charge flow as a bypass, has been led via an
autotherm reformer, or that has originated from another synthesis gas production.
3. Method as claimed in one of the preceding claims, wherein the additional
synthesis gas, which compensates the loss and is supplied to the main synthesis gas
flow before the niethanol systems, is taken from a combined autotfaerm reformer
and/or a reactor for partial oxidation, or from another synthesis gas production.
4. Method as claimed in one of th e preceding claims, wherein the waste
heat of the additional inethanol preliminary reactor is used to operate an absorption-type refrigerating machine, wherein the cold that is produced is used to cool a synthesis gas compression and/or unused compression energy is used for the compression of foreign synthesis gas.
5. Method as claimed in one of the preceding claims, wherein a mixture of H2
and CO2 is used as additioaal synthesis gas, wherein the CO2 that is present in the
mixture originates from the flue gas of a firing place or from the waste gas of a CQz
scrubbing plant in an ammonia plant
-11-

6. Method as claimed in one of the preceding claims wherein the CO2
originates from a Sue gas cleansing plant of a firing place, for example the firing
place of the primary reformer.
7. Plant for methanol synthesis with a natural gas supply conduit to a reformer
and a downstream methanol synthesis wherein;
- a branch conduit 9 for a side stream of the synthesis gas (8) leaving the
¦ secondary reformer (3),
a mothanol preliminary reactor (5) in the side stream,
a methanol supply conduit (10) to the methanol main flow (17) leaving the methanol synthesis (4).
- A return conduit (11) which guides non-converted synthesis gas from
the methanol preliminary reactor (5) into the synthesis gas main flow
(12) before the- methanol synthesis (4), as well as
- a supply conduit (13) before the methanol synthesis (4)., for the supply
of synthesis gas that compensates losses.
8. Plant as claimed in claim 7, wherein an outotherm reformer (6) is switched parallel to the reformer (2,3), wherein the synthesis gas (15) that is leaving is used at least in part as synthesis gas that compensates losses.
9, Plant as claimed in claim 7 or 8, wherein a flue gas scrubbing plant (21) for thee flue gas leaving the primary reformer (2), as well as a CO3 supply conduit (19) for making available the foreign or additional synthesis gas (14}, as well as Bupply conduit (20) for supplying foreign H2 (fig.2)

10. Plant as claimed in claim 7 or one of the following ones wherein a supply conduit (19a) for supplying foreign CO2 from a CO2 scrubbing plant in the NH3 plant, as well as a supply conduit (20c) for supplying foreign H2 (fig. 3).
Method for the synthesis of methanol from hydrogen, carbon monoxide and carbon dioxicte under pressure wherein desulphurated natural gas is sent forward to a reformer and subsequently the synthesis gas is sent forward to methanol gyntiiesis,eharaeterized in that after passing through the reformer, out of the synthesis gas How, a side stream is supplied to a methauol preliminary reactor, the methanol created in the preliminary reactor is supplied to the methanol flow leaving the mefhanol synthesis of the main flow, and a synthesis gas flow that is not converted in the methanol preliminary reactor is supplied oace more to fee main flow before the methanol synthesis, wherein in the area, of this supply, at the same time an additional synthesis gas is given up which compensates the loss that has arisen.

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Patent Number

206704

Indian Patent Application Number

IN/PCT/2001/00449/KOL

PG Journal Number

19/2007

Publication Date

11-May-2007

Grant Date

10-May-2007

Date of Filing

23-Apr-2001

Name of Patentee

UHDE GMBH

Applicant Address

FREIDRICH-UHDE-STRASSE 15, 44141 DORTMUND,

Inventors:

#	Inventor's Name	Inventor's Address
1	BAEHNISCH HANS-JOACHIM	BOMELBURGSTRASSE 10, 44227 DORTMUND,

PCT International Classification Number

C07C 29/151, B01J 8/04

PCT International Application Number

PCT/EP00/06488

PCT International Filing date

2000-07-08

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	19942559.0	1999-09-07	Germany
2	100 00 280.3	2000-01-07	Germany
3	19951137.3	1999-10-23	Germany