Process and plant for producing a plurality of gaseous products from shifted and unshifted raw synthesis gas
阅读说明：本技术 用于从经变换和未变换的粗合成气生产多种气体产物的方法和设施 (Process and plant for producing a plurality of gaseous products from shifted and unshifted raw synthesis gas ) 是由 阿尔弗雷德·古布林斯基 莎伦·科尔贝特 多利特·拉波尔德 潘卡·普里 于 2019-06-14 设计创作，主要内容包括：本发明涉及一种用于从粗合成气中除去酸性气体成分的气体洗涤方法和相应设施,其通过在气体洗涤方法中处理经变换的和未变换的粗合成气并且通过将由此获得的部分产物流组合而生产具有不同组成的多种气体产物成为可能。此外,本发明确保了以有利的方式在材料上和/或在能量上利用在负载的洗涤介质的减压期间中获得的闪蒸气体。(The present invention relates to a gas scrubbing process and corresponding installation for removing acid gas components from a raw synthesis gas, which is made possible by treating a shifted and an unshifted raw synthesis gas in a gas scrubbing process and by combining partial product streams obtained therefrom to produce a plurality of gas products having different compositions. Furthermore, the invention ensures that the flash gas obtained during the depressurization of the loaded scrubbing medium is utilized in an advantageous manner on the material and/or on the energy.)
1. Method for purifying shifted and unshifted raw synthesis gas by gas scrubbing with a scrubbing medium and for producing a gas having a different H2A process for multiple synthesis gas product streams at/CO ratios comprising the steps of:
(a) the shifted and unshifted raw syngas are provided and supplied to respective separate pre-scrubbers to remove trace components, such as NH3HCN, mercaptans, BTX aromatics,
(b) supplying the gaseous overhead products from these pre-scrubbers to respective separate H2S scrubber to remove H2S，
(c) From these H2The gaseous overhead of the S scrubber is supplied to separate CO2Scrubber to remove CO2，
(d1) CO from the unshifted raw syngas2The gaseous top product stream of the scrubber is divided into a first synthesis gas part product stream and a second synthesis gas part product stream which is passed for pressure reduction through a preferably multistage expander to recover mechanical work and cold and obtain an expanded second synthesis gas part product stream,
(d2) converting CO from the shifted raw syngas2Gaseous overhead product stream of the scrubber is split into a third streamA gas-forming partial product stream and a fourth synthesis gas partial product stream,
(e) supplying the liquid bottom product from the separate pre-scrubbers to an intermediate pressure pre-scrubber flash vessel, supplying the gaseous top product from the intermediate pressure pre-scrubber flash vessel to a recompressor, supplying the liquid bottom product from the intermediate pressure pre-scrubber flash vessel to a low pressure pre-scrubber flash vessel, supplying the gaseous top product from the low pressure pre-scrubber flash vessel to the recompressor, supplying the liquid bottom product from the low pressure pre-scrubber flash vessel to at least one apparatus for flash regeneration and/or heat regeneration of the scrubbing medium,
(f) from these individual H2The liquid bottom product of the S scrubber is supplied to medium pressure H2S flash vessel from the medium pressure H2The gaseous overhead of the S flash vessel is supplied to the recompressor, from which the medium pressure H is taken2The liquid bottoms of the S flash vessel are supplied to a low pressure H2S flash vessel from which the low pressure H is to be derived2The gaseous overhead of the S flash vessel is supplied to the recompressor, from which the low pressure H is taken2The liquid bottom product of the S-flash vessel is supplied to at least one device for flash regeneration and/or thermal regeneration of the washing medium,
(g) from these individual COs2The liquid bottom product of the scrubber is supplied to medium pressure CO2A flash vessel to receive CO from the medium pressure2The gaseous overhead of the flash vessel is supplied to the recompressor to supply the gaseous overhead from the medium pressure CO2Liquid bottoms from the flash vessel are supplied to low pressure CO2A flash vessel to receive CO from the low pressure2The gaseous overhead product of the flash vessel is supplied to the low pressure H2S flash vessel and/or the recompressor to convert CO from the low pressure2The liquid bottom product of the flash vessel is supplied to at least one device for flash regeneration and/or thermal regeneration of the washing medium,
(h) recycling the gas stream compressed by the recompressor to a pre-scrubber for the unshifted raw synthesis gas and/or the shifted raw synthesis gas.
2. Method for purifying shifted and unshifted raw synthesis gas by gas scrubbing with a scrubbing medium and for producing a gas having a different H2A process for multiple synthesis gas product streams at/CO ratios comprising the steps of:
(a) the shifted and unshifted raw syngas are provided and supplied to respective separate pre-scrubbers to remove trace components, such as NH3HCN, mercaptans, BTX aromatics,
(b) supplying the gaseous overhead products from these pre-scrubbers to respective separate H2S scrubber to remove H2S，
(c) From these H2The gaseous overhead of the S scrubber is supplied to separate CO2Scrubber to remove CO2，
(d1) CO from the unshifted raw syngas2The gaseous top product stream of the scrubber is divided into a first synthesis gas part product stream and a second synthesis gas part product stream which is passed for pressure reduction through a preferably multistage expander to recover mechanical work and cold and obtain an expanded second synthesis gas part product stream,
(d2) converting CO from the shifted raw syngas2The gaseous top product stream of the scrubber is separated into a third synthesis gas part product stream and a fourth synthesis gas part product stream,
(e) supplying the liquid bottom product from the separate pre-scrubbers to an intermediate pressure pre-scrubber flash vessel, supplying the gaseous top product from the intermediate pressure pre-scrubber flash vessel to a recompressor, supplying the liquid bottom product from the intermediate pressure pre-scrubber flash vessel to a low pressure pre-scrubber flash vessel, supplying the gaseous top product from the low pressure pre-scrubber flash vessel to the recompressor, supplying the liquid bottom product from the low pressure pre-scrubber flash vessel to at least one apparatus for flash regeneration and/or heat regeneration of the scrubbing medium,
(f) from these individual H2The liquid bottom product of the S scrubber is supplied to medium pressure H2S flash vessel from the medium pressure H2The gaseous overhead of the S flash vessel is fed into the first or subsequent stage of the multi-stage expander or into a conduit downstream of the expander, from the intermediate pressure H2The liquid bottoms of the S flash vessel are supplied to a low pressure H2S flash vessel from which the low pressure H is to be derived2The gaseous overhead of the S flash vessel is supplied to the recompressor, from which the low pressure H is taken2The liquid bottom product of the S-flash vessel is supplied to at least one device for flash regeneration and/or thermal regeneration of the washing medium,
(g) from these individual COs2The liquid bottom product of the scrubber is supplied to medium pressure CO2A flash vessel to receive CO from the medium pressure2The gaseous overhead of the flash vessel is fed to the first or subsequent stage of the multi-stage expander or into a conduit downstream of the expander, from which medium pressure CO is supplied2Liquid bottoms from the flash vessel are supplied to low pressure CO2A flash vessel to receive CO from the low pressure2The gaseous overhead product of the flash vessel is supplied to the low pressure H2S flash vessel and/or the recompressor to convert CO from the low pressure2The liquid bottom product of the flash vessel is supplied to at least one device for flash regeneration and/or thermal regeneration of the washing medium,
(h) recycling the gas stream compressed by the recompressor to a pre-scrubber for the unshifted raw synthesis gas and/or the shifted raw synthesis gas.
3. The method according to claim 1 or 2, characterized in that the washing medium comprises one or more components selected from the group of: methanol, N-methylpyrrolidone (NMP), secondary amines, preferably diethanolamine, tertiary amines, preferably methyldiethanolamine, polyethylene glycol dialkyl ethers, preferably polyethylene glycol dimethyl ether.
4. A process according to any one of the preceding claims, characterized in that the first and/or third synthesis gas portion product stream is at least partially added to or forms a methanol synthesis gas product stream.
5. Process according to claim 4, characterized in that the first and third synthesis gas partial product streams are at least partially added to the methanol synthesis gas product stream, wherein the specific ratios are selected such that the H required for methanol synthesis is determined2The ratio of/CO.
6. A process according to any one of the preceding claims, wherein the second expanded synthesis gas partial product stream is added to or forms a fuel gas product stream.
7. The process according to any of the preceding claims, characterized in that the fourth synthesis gas partial product stream is added to or forms a hydrogen product stream.
8. Process according to any one of the preceding claims, characterized in that the recompressor is a multistage recompressor, wherein the gaseous overhead from the low-pressure flash vessels is supplied to a first stage of the multistage recompressor and the gaseous overhead from the intermediate-pressure flash vessels is supplied to a subsequent stage of the multistage recompressor.
9. Method for purifying shifted and unshifted raw synthesis gas by gas scrubbing with a scrubbing medium and for producing a gas having a different H2A facility for multiple syngas product streams of/CO ratios comprising the following components and assemblies in fluid connection with each other:
(a) means for providing and supplying the shifted and unshifted raw synthesis gas to respective separate pre-scrubbers, wherein these pre-scrubbers are suitable for removing trace components, such as NH3HCN, mercaptans, BTX aromatics,
(b) for supplying the gaseous overhead products from these pre-scrubbers to respective separate H2S scrubber to remove H2S clothesThe device is placed in a water tank,
(c) for converting from these H2The gaseous overhead of the S scrubber is supplied to separate CO2Scrubber to remove CO2The apparatus of (1) is provided with a plurality of the devices,
(d1) for converting CO from the unshifted raw syngas2Means for separating the gaseous top product stream of the scrubber into a first part product stream and a second part product stream, means for introducing the second part product stream into a multi-stage expander, means for discharging the expanded second part product stream from the expander,
(d2) for converting CO from the shifted raw syngas2Means for separating the gaseous top product stream from the scrubber into a third partial product stream and a fourth partial product stream,
(e) means for supplying liquid bottom product from the separate pre-scrubbers to the intermediate pressure pre-scrubber flash vessel, means for supplying gaseous top product from the intermediate pressure pre-scrubber flash vessel to the recompressor, means for supplying liquid bottom product from the intermediate pressure pre-scrubber flash vessel to the low pressure pre-scrubber flash vessel, means for supplying gaseous top product from the low pressure pre-scrubber flash vessel to the recompressor, means for supplying liquid bottom product from the low pressure pre-scrubber flash vessel to at least one apparatus for flash regeneration and/or heat regeneration of the scrubbing medium,
(f) for converting H from these individual groups2The liquid bottom product of the S scrubber is supplied to medium pressure H2Means for flashing S the vessel from the medium pressure H2Means for supplying the gaseous overhead product of the S flash vessel to the recompressor for supplying the gaseous overhead product from the intermediate pressure H2The liquid bottoms of the S flash vessel are supplied to a low pressure H2Means for S flash vessel to supply low pressure H2Means for supplying gaseous overhead from the S flash vessel to the recompressor for supplying low pressure H from the low pressure2The liquid bottom product of the S-flash vessel is supplied to at least one device in the apparatus for flash regeneration and/or thermal regeneration of the washing medium,
(g) for separating CO from these separate gases2The liquid bottom product of the scrubber is supplied to medium pressure CO2Means of flash vessel for feeding CO from the medium pressure2Means for supplying the gaseous overhead product of the flash vessel to the recompressor for supplying the gaseous overhead product from the intermediate pressure CO2Liquid bottoms from the flash vessel are supplied to low pressure CO2Means of flash vessel for passing CO from the low pressure2The gaseous overhead product of the flash vessel is supplied to the low pressure H2Means of S flash vessel and/or the recompressor for passing CO from the low pressure2The liquid bottom product of the flash vessel is supplied to at least one device in the apparatus for flash regeneration and/or thermal regeneration of the washing medium,
(h) means for recycling the gas stream compressed by the recompressor to a pre-scrubber for the unshifted raw synthesis gas and/or the shifted raw synthesis gas.
10. Method for purifying shifted and unshifted raw synthesis gas by gas scrubbing with a scrubbing medium and for producing a gas having a different H2A facility for multiple syngas product streams of/CO ratio comprising the following components and assemblies:
(a) means for providing and supplying the shifted and unshifted raw synthesis gas to respective separate pre-scrubbers, wherein these pre-scrubbers are suitable for removing trace components, such as NH3HCN, mercaptans, BTX aromatics,
(b) for supplying the gaseous overhead products from these pre-scrubbers to respective separate H2S scrubber to remove H2The device of the S is characterized in that,
(c) for converting from these H2The gaseous overhead of the S scrubber is supplied to separate CO2Scrubber to remove CO2The apparatus of (1) is provided with a plurality of the devices,
(d1) for converting CO from the unshifted raw syngas2Means for separating the gaseous top product stream of the scrubber into a first part product stream and a second part product stream, for separating the second partMeans for introducing the partial product stream into a multistage expander, means for withdrawing an expanded second partial product stream from the expander,
(d2) for converting CO from the shifted raw syngas2Means for separating the gaseous top product stream from the scrubber into a third partial product stream and a fourth partial product stream,
(e) means for supplying liquid bottom product from the separate pre-scrubbers to the intermediate pressure pre-scrubber flash vessel, means for supplying gaseous top product from the intermediate pressure pre-scrubber flash vessel to the recompressor, means for supplying liquid bottom product from the intermediate pressure pre-scrubber flash vessel to the low pressure pre-scrubber flash vessel, means for supplying gaseous top product from the low pressure pre-scrubber flash vessel to the recompressor, means for supplying liquid bottom product from the low pressure pre-scrubber flash vessel to at least one apparatus for flash regeneration and/or heat regeneration of the scrubbing medium,
(f) for converting H from these individual groups2The liquid bottom product of the S scrubber is supplied to medium pressure H2Means for flashing S the vessel from the medium pressure H2Means for supplying the gaseous overhead of the S-flash vessel to the second or subsequent stage of the multi-stage expander for converting the gaseous overhead from the intermediate pressure H2The liquid bottoms of the S flash vessel are supplied to a low pressure H2Means for S flash vessel to supply low pressure H2Means for supplying gaseous overhead from the S flash vessel to the recompressor for supplying low pressure H from the low pressure2The liquid bottom product of the S-flash vessel is supplied to at least one device in the apparatus for flash regeneration and/or thermal regeneration of the washing medium,
(g) for separating CO from these separate gases2The liquid bottom product of the scrubber is supplied to medium pressure CO2Means of flash vessel for feeding CO from the medium pressure2Means for supplying the gaseous overhead of the flash vessel to the second or subsequent stage of the multi-stage expander for the intermediate pressure CO2Liquid bottoms from the flash vessel are supplied to low pressure CO2Of flash vesselsMeans for introducing CO from the low pressure2The gaseous overhead product of the flash vessel is supplied to the low pressure H2Means of S flash vessel and/or the recompressor for passing CO from the low pressure2The liquid bottom product of the flash vessel is supplied to at least one device in the apparatus for flash regeneration and/or thermal regeneration of the washing medium,
(h) means for recycling the gas stream compressed by the recompressor to a pre-scrubber for the unshifted raw synthesis gas and/or the shifted raw synthesis gas.
Technical Field
The present invention relates to a process for producing multiple gas products with different compositions and subsequent combinations of the individual gas streams obtained therefrom from a raw synthesis gas by gas scrubbing with a scrubbing medium. The invention also relates to a plant for carrying out such a method.
Background
Methods for separating undesired satellites from industrial raw gas by physical or chemical absorption or gas scrubbing are well known from the prior art. Thus, such processes may be used to safely remove unwanted acidic components (e.g., carbon dioxide (CO) from a raw syngas produced by gasification or reforming of a carbonaceous feed stock2) And hydrogen sulfide (H)2S)), and also hydrogen (H) from the desired synthesis gas component2) And carbon monoxide (CO) to remove additional components such as Carbonyl Sulfide (COs) and Hydrogen Cyanide (HCN) to trace amounts. A known and frequently used method is that in Ullmann's Encyclopedia of Industrial Chemistry, Ullmann's Encyclopedia of Industrial Chemistry]The low temperature methanol wash process, described generally in the sixth edition, volume 15, page 399 and below. In the low-temperature methanol wash process, the above-mentioned unwanted disruptive components are absorbed by cold methanol as absorbent or wash medium (i.e. methanol cooled to significantly below ambient temperature), wherein a strong mass transfer between the crude gas and the absorption medium/wash medium takes place in an absorption column (also referred to as a wash column). As methanol temperature decreases and pressure increases, the solubility of the unwanted gas components increases dramatically, while remaining nearly constant for hydrogen and carbon monoxide. Furthermore, methanol has the advantage of maintaining a low viscosity even at temperatures as low as-75 ℃ and thus good mass and heat transfer properties.
Methanol loaded with destructive components and used as a scrubbing medium is circulated through the regeneration equipment in a low temperature methanol scrubbing process. In these regeneration plants, the loaded methanol is freed from absorbed gases by physical means. Thus in the first regeneration step CO is removed from the loaded methanol scrubbing medium by depressurization (so-called flash regeneration) and/or stripping with a gas such as nitrogen2. In an additional or alternative regeneration step, by heating(so-called thermal regeneration) to drive off the sulfur-containing gases (COS and H)2S). Often seek to produce virtually no CO2COS/H of2S gas, since it is economically subjected to further processing with CO2Impairment of mixing.
In the low temperature methanol wash process, a distinction is made between the standard process and the selective low temperature methanol wash process. Associated gas COS/H in a standard low temperature methanol wash process2S and CO2Are removed together from the raw synthesis gas in one absorption step. In contrast, the associated gas containing sulphur, COS/H, is produced in a so-called selective low-temperature methanol wash process2S and CO2Are removed separately from the raw synthesis gas in separate consecutive absorption steps. Such selective absorption is achieved by suitably adjusting the process parameters, in particular the ratio of the amounts of scrubbing medium to gas to be absorbed. The selective absorption has the advantage of COS/H2S and CO2The gases have been kept largely separated in the absorption and only a minor portion needs to be separated in the regeneration of methanol. This also allows the recovery of the sulphur present using downstream processes, such as the Claus (Claus) process.
The flash regeneration of the scrubbing medium loaded with acid gas components can be carried out in a multistage procedure, wherein mechanical work and cold can be recovered in the depressurization. Thus, acidic components such as CO are removed from gas streams2、H2In the process of S and COS, US patent US 5067972 proposes treating the stream with a physical scrubbing medium. The scrubbing medium loaded with acid gas components is supplied to a cascade of flash vessels of decreasing pressure, and the flash gas thus released is supplied in each case between two stages of a multistage pressure reduction turbine. This recovers mechanical work and process cold.
However, the flash gas obtained at the end of the pressure reduction cascade is used only as a coolant for the raw gas introduced into the process and is then discharged from the process. One disadvantage of this is that there is no teaching of further utilization of the flash gas obtained, for example as a material.
Another disadvantage is that the described gas purification method recovers pure synthesis gas with a fixed composition. As described in Ullmann's Encyclopedia of Industrial Chemistry, 6 th edition, volume 15, chapter 5.1, "Carbon monoxide shift conversion", page 382 and below, CO conversion (also referred to as CO shift) can be used to change the composition in the direction of a relatively hydrogen-rich mixture after addition of steam and contact with a suitable catalyst. However, since pure syngas is typically obtained at temperatures close to ambient temperature after undergoing a scrubbing process, the CO conversion is typically carried out by reheating the pure syngas. This requires additional devices, such as heaters/heat exchangers, and the corresponding heating energy which is taken from the raw synthesis gas during cooling before introduction into the scrubbing apparatus must be resupplied.
Disclosure of Invention
The problem addressed by the present invention is therefore to specify a process which avoids the said disadvantages of the processes known from the prior art and in particular allows recovery from a raw synthesis gas of different compositions (for example with respect to the H present in the different partial products)2In terms of/CO ratio) of a plurality of pure gas products.
This problem is substantially solved by a method having the features of claim 1. Further embodiments, in particular preferred embodiments, of the method according to the invention can be found in the dependent claims. The invention also relates to a plant for carrying out such a method.
The method according to the invention:
method for purifying shifted and unshifted raw synthesis gas by gas scrubbing with a scrubbing medium and for producing a gas having a different H2A process for multiple synthesis gas product streams at/CO ratios comprising the steps of:
(a) the shifted and unshifted raw syngas are provided and supplied to respective separate pre-scrubbers to remove trace components, such as NH3HCN, mercaptans, BTX aromatics,
(b) supplying the gaseous overhead products from these pre-scrubbers to respective separate H2S scrubber to remove H2S，
(c) From these H2The gaseous overhead of the S scrubber is supplied to separate CO2Scrubber to remove CO2，
(d1) CO from the unshifted raw syngas2The gaseous top product stream of the scrubber is divided into a first synthesis gas part product stream and a second synthesis gas part product stream which is passed for pressure reduction through a preferably multistage expander to recover mechanical work and cold and obtain an expanded second synthesis gas part product stream,
(d2) converting CO from the shifted raw syngas2The gaseous top product stream of the scrubber is separated into a third synthesis gas part product stream and a fourth synthesis gas part product stream,
(e) supplying the liquid bottom product from the separate pre-scrubbers to an intermediate pressure pre-scrubber flash vessel, supplying the gaseous top product from the intermediate pressure pre-scrubber flash vessel to a recompressor, supplying the liquid bottom product from the intermediate pressure pre-scrubber flash vessel to a low pressure pre-scrubber flash vessel, supplying the gaseous top product from the low pressure pre-scrubber flash vessel to the recompressor, supplying the liquid bottom product from the low pressure pre-scrubber flash vessel to at least one apparatus for flash regeneration and/or heat regeneration of the scrubbing medium,
(f) from these individual H2The liquid bottom product of the S scrubber is supplied to medium pressure H2S flash vessel from the medium pressure H2The gaseous overhead of the S flash vessel is supplied to the recompressor, from which the medium pressure H is taken2The liquid bottoms of the S flash vessel are supplied to a low pressure H2S flash vessel from which the low pressure H is to be derived2The gaseous overhead of the S flash vessel is supplied to the recompressor, from which the low pressure H is taken2The liquid bottom product of the S-flash vessel is supplied to at least one device for flash regeneration and/or thermal regeneration of the washing medium,
(g) from these individual COs2The liquid bottom product of the scrubber is supplied to medium pressure CO2A flash vessel to receive CO from the medium pressure2Flash volumeThe gaseous overhead product of the vessel is supplied to the recompressor, from which medium pressure CO is taken2Liquid bottoms from the flash vessel are supplied to low pressure CO2A flash vessel to receive CO from the low pressure2The gaseous overhead product of the flash vessel is supplied to the low pressure H2S flash vessel and/or the recompressor to convert CO from the low pressure2The liquid bottom product of the flash vessel is supplied to at least one device for flash regeneration and/or thermal regeneration of the washing medium,
(h) recycling the gas stream compressed by the recompressor to a pre-scrubber for the unshifted raw synthesis gas and/or the shifted raw synthesis gas.
The installation according to the invention:
method for purifying shifted and unshifted raw synthesis gas by gas scrubbing with a scrubbing medium and for producing a gas having a different H2A facility for multiple syngas product streams of/CO ratios comprising the following components and assemblies in fluid connection with each other:
(a) means for providing and supplying the shifted and unshifted raw synthesis gas to respective separate pre-scrubbers, wherein these pre-scrubbers are suitable for removing trace components, such as NH3HCN, mercaptans, BTX aromatics,
(b) for supplying the gaseous overhead products from these pre-scrubbers to respective separate H2S scrubber to remove H2The device of the S is characterized in that,
(c) for converting from these H2The gaseous overhead of the S scrubber is supplied to separate CO2Scrubber to remove CO2The apparatus of (1) is provided with a plurality of the devices,
(d1) for converting CO from the unshifted raw syngas2Means for separating the gaseous top product stream of the scrubber into a first part product stream and a second part product stream, means for introducing the second part product stream into a multi-stage expander, means for discharging the expanded second part product stream from the expander,
(d2) for converting CO from the shifted raw syngas2Means for separating the gaseous top product stream from the scrubber into a third partial product stream and a fourth partial product stream,
(e) means for supplying liquid bottom product from the separate pre-scrubbers to the intermediate pressure pre-scrubber flash vessel, means for supplying gaseous top product from the intermediate pressure pre-scrubber flash vessel to the recompressor, means for supplying liquid bottom product from the intermediate pressure pre-scrubber flash vessel to the low pressure pre-scrubber flash vessel, means for supplying gaseous top product from the low pressure pre-scrubber flash vessel to the recompressor, means for supplying liquid bottom product from the low pressure pre-scrubber flash vessel to at least one apparatus for flash regeneration and/or heat regeneration of the scrubbing medium,
(f) for converting H from these individual groups2The liquid bottom product of the S scrubber is supplied to medium pressure H2Means for flashing S the vessel from the medium pressure H2Means for supplying the gaseous overhead product of the S flash vessel to the recompressor for supplying the gaseous overhead product from the intermediate pressure H2The liquid bottoms of the S flash vessel are supplied to a low pressure H2Means for S flash vessel to supply low pressure H2Means for supplying gaseous overhead from the S flash vessel to the recompressor for supplying low pressure H from the low pressure2The liquid bottom product of the S-flash vessel is supplied to at least one device in the apparatus for flash regeneration and/or thermal regeneration of the washing medium,
(g) for separating CO from these separate gases2The liquid bottom product of the scrubber is supplied to medium pressure CO2Means of flash vessel for feeding CO from the medium pressure2Means for supplying the gaseous overhead product of the flash vessel to the recompressor for supplying the gaseous overhead product from the intermediate pressure CO2Liquid bottoms from the flash vessel are supplied to low pressure CO2Means of flash vessel for passing CO from the low pressure2The gaseous overhead product of the flash vessel is supplied to the low pressure H2Means of S flash vessel and/or the recompressor for passing CO from the low pressure2The liquid bottom product of the flash vessel is supplied to at least one of the reactors for the flashA device in a plant for flash regeneration and/or thermal regeneration of a scrubbing medium,
(h) means for recycling the gas stream compressed by the recompressor to a pre-scrubber for the unshifted raw synthesis gas and/or the shifted raw synthesis gas.
The terms shifted syngas and unshifted syngas are understood to mean syngas that has undergone CO conversion and syngas that has not undergone CO conversion, respectively. The reaction conditions required for carrying out the CO conversion are known to the person skilled in the art and are described in the technical literature.
The term scrubbing medium, synonymous with absorption medium or solvent, is understood in the context of the present invention to mean a substance or mixture of substances in liquid form under the process conditions, having an absorption capacity for the component to be separated from the gas and which can be regenerated by physical means, for example by flashing or thermal regeneration.
Flash is understood to mean a rapid, preferably sudden, pressure reduction of the liquid, which is preferably achieved upon entry into the vessel via a flow restrictor (e.g. a valve). The gas thus released is referred to as flash gas.
The term recompressor refers to a single-stage or multi-stage compressor whose task is to increase the pressure of the gas stream from a low value to a higher value, for example the entry pressure of the raw synthesis gas.
Supplying the material stream to the expander also includes at least a partial supply thereof, while passing the remaining portion of the material stream, for example, to a recompression machine.
Pre-scrubber, H2S scrubber and CO2The scrubber need not necessarily be in the form of a separate device connected via a conduit, but may in the context of the present invention also be a section of one or more integrated absorption columns.
In recycling the gas stream compressed by the recompressor to the pre-scrubber for the raw synthesis gas, the gas stream can enter the pre-scrubber directly via a separate conduit. The recycle conduit may alternatively pass into the raw syngas feed conduit to premix the recycled gas with the raw syngas prior to entering the scrubbing apparatus.
A fluid connection between two zones is understood to mean any type of connection which in any case makes it possible for a fluid (for example a liquid washing medium) to flow from one of the two zones to the other, ignoring any interposed zones, components, valves or devices.
Means for supplying, supplying or discharging a material flow to a process stage or a plant component are understood to mean all apparatuses, component parts and devices, in particular storage vessels, conduits, separating and metering apparatuses such as, for example, valves, conveying apparatuses such as, for example, pumps, blowers, compressors, which a person skilled in the art would consider to utilize in a particular case.
Any pressure figures in bar (a) are based on absolute pressure in bar unless otherwise stated in individual cases.
The inventors have realized that it is advantageous to subject a portion of the raw synthesis gas to a CO conversion in the form of a raw gas CO shift. The shifted raw syngas and the unshifted raw syngas are then treated in two separate gas scrubbing apparatuses. Advantageously, the same plant components and equipment can be used in respect of the regeneration of the loaded scrubbing medium, since these components and equipment must be present even in the case of the treatment of only one raw synthesis gas. Thus, a corresponding synergy is obtained in the treatment of two different raw synthesis gases having different compositions.
The appropriate combination of the shifted and the unshifted pure synthesis gas makes it possible to obtain different final product streams, for example with H required for methanol synthesis2A methanol synthesis gas product stream, a hydrogen product stream and a fuel gas product stream in a/CO ratio. This provides an advantage in terms of the width of the product palette compared to a method in which only a single raw synthesis gas of fixed composition is processed.
The present invention is further based on the discovery that: the flash gas obtained can also be utilized on materials by recycling to the raw synthesis gas entering the gas scrubbing process. The flash gas still contains a certain proportion of the valuable components CO and H2And due to the invention of the recycle to the shifted/unshifted raw synthesis gasIf desired, it can also be at least partially passed into the synthesis gas partial product stream. This improves the overall process balance of these valuable components.
In a particular embodiment of the method according to the invention according to claim 2 and of the plant according to the invention according to claim 10, only a part of the flash gas is utilized on the material by recycling into the raw synthesis gas entering the gas scrubbing process, while another part is passed to an expander, for example a multistage pressure reduction turbine. This achieves an advantageous compromise between the material and energy utilization of the flash gas.
Further preferred embodiments of the invention
A preferred embodiment of the method according to the invention is characterized in that the washing medium comprises one or more components selected from the group of: methanol, N-methylpyrrolidone (NMP), secondary amines, preferably diethanolamine, tertiary amines, preferably methyldiethanolamine, polyethylene glycol dialkyl ethers, preferably polyethylene glycol dimethyl ether. All these absorption media are used for the absorption of carbon dioxide and sulphur compounds, are chemically stable and chemically inert to the substances to be separated, and can be regenerated by pressure reduction/thermal regeneration.
A further preferred embodiment of the method according to the invention is characterized in that the first and/or third synthesis gas part product stream is at least partially added to or forms a methanol synthesis gas product stream.
It is particularly preferred that the first and third synthesis gas part-product streams are at least partially added to the methanol synthesis gas product stream, wherein the specific ratio is selected such that the H required for methanol synthesis is determined2The ratio of/CO. Since the first part of the product stream originates from the unconverted raw synthesis gas, the third part of the product stream originates from the converted raw synthesis gas, and the latter is therefore rich in hydrogen, a suitable combination of the two streams can be employed to determine precisely the H required for methanol synthesis2The ratio of/CO.
A further preferred embodiment of the process according to the invention is characterized in that the second expanded synthesis gas partial product stream is added to or forms a fuel gas product stream.
It is preferred that the fourth synthesis gas portion product stream is added to or forms a hydrogen product stream. The first portion of the product stream is derived from shifted raw syngas and is therefore richer in hydrogen compared to unshifted syngas.
It has proven to be particularly advantageous when the recompressor is a multistage recompressor, wherein the gaseous overhead from the low-pressure flash vessels is supplied to a first stage of the multistage recompressor and the gaseous overhead from the intermediate-pressure flash vessels is supplied to a subsequent stage of the multistage recompressor. In this way, the flash gases are compressed in an energy-optimized manner, since they are supplied to the respective stages of a multistage recompressor with similar pressure levels.
Working examples
Further features, advantages and possible applications of the invention will also be apparent from the following description of working examples and the accompanying drawings. All features described and/or depicted form the subject matter of the present invention by themselves or in any combination, irrespective of their combination in the claims or their dependency references.
Figure 1 shows a schematic view of a method according to the invention/a plant according to the invention in a first embodiment,
fig. 2 shows a schematic view of a method/installation according to the invention in a second embodiment.
In the schematic diagram shown in fig. 1 of the method according to the invention/of the plant according to the invention according to the first embodiment, the unshifted raw synthesis gas is supplied via conduit 1 and the shifted raw synthesis gas is supplied via conduit 71 to two separate scrubbing apparatuses comprising scrubbers 2, 4 and 6 and scrubbers 72, 74 and 76, respectively. Each scrubber may be a separate device or a zone of an integrated scrubbing/absorption tower. The scrubbing medium used in this working example was cold methanol, which was delivered to these scrubbing apparatuses via conduit 98/99. Typically, a plurality of methanol streams of different purity/degree of regeneration are supplied to the scrubbing apparatus at different points in a manner known to those skilled in the art (not shown).
Via a conduit 1, withoutThe shifted raw synthesis gas enters a pre-scrubber 2 for removing trace components such as NH3And HCN, typically at a pressure of 20 to 70 bar (a), and is scrubbed therein with a portion of the acid gas component-laden methanol supplied via conduit 48. The top product from the pre-scrubber 2 is supplied via conduit 3 to H2S scrubber 4 and is likewise scrubbed therein with partially loaded methanol. Will come from H2The top product of S scrubber 4 is supplied via conduit 5 to CO2Scrubber 6 and therein is scrubbed with high purity methanol supplied via conduit 98 and formed from thermally regenerated methanol, fresh pure methanol or mixtures thereof. Via conduit 7a, from CO2A portion of the top product of scrubber 6 is fed to an expander in the form of a two-stage pressure reducing turbine comprising coolers 8, 12, 16, turbine stages 10, 14 and internal conduits 9, 11, 13, 15. In which the purified synthesis gas is depressurized, typically to a pressure of 5 bar (a), to recover cold and mechanical work. A condensate separator is typically present after each pressure reduction stage but is not shown. The condensate collected here is recycled to a part of the plant where the liquid is treated at a similar pressure; these are, for example, flash vessels. Via conduit 17, the depressurized pure synthesis gas is discharged from the process and sent to further treatment or processing. The pure synthesis gas thus obtained can be used, for example, as fuel gas. CO from the unshifted raw syngas via conduit 7, and after combining with the gas supplied via conduit 77, via conduit 792The remainder of the top product of scrubber 6 is discharged from the process as methanol synthesis gas.
Via conduit 71, the unshifted raw syngas enters a pre-scrubber 72 to remove trace components such as NH3And HCN, typically at a pressure of 20 to 70 bar (a), and is scrubbed therein with a portion of the acid gas component-laden methanol supplied via conduit 84. The top product from the pre-scrubber 72 is supplied to H via conduit 732S scrubber 74 and is likewise scrubbed therein with partially loaded methanol. Will come from H2The top product of S scrubber 74 is supplied to CO via conduit 752Scrubber 76 and in which is used a heightA pure methanol wash, which methanol is supplied via conduit 99 and is formed from thermally regenerated methanol, fresh pure methanol or mixtures thereof. Will be derived from CO2The top product of scrubber 76 is discharged via conduit 77 and is split into two portions. A first portion is withdrawn from the process as a crude hydrogen product via conduit 78 and sent to further processing/treatment (not shown). The second portion is discharged via conduit 77 and is mixed with the CO2The remaining portion of the top product of scrubber 6 is combined and discharged from the process via conduit 79.
The prewashers 2, 72 are loaded with trace components such as NH3And HCN, via conduits 19, 81, and depressurized therein to typically 15 to 40 bar (a). The gaseous overhead product thus obtained is passed via conduit 21 to the second stage of the recompressor, which comprises coolers 32, 35, compressor stages 31, 34 and separators 30, 33. The conduits inside the recompressor are not marked with a special reference numeral. The liquid bottoms from the medium pressure pre-wash flash vessel 20 is passed via conduit 22 to a low pressure pre-wash flash vessel 24 and therein depressurized, typically to 1.5 to 15 bar (a). The gaseous overhead product thus obtained is passed via conduit 25 to the first stage of the recompressor and is introduced therein into separator 30. The liquid bottoms from the low pressure pre-wash flash vessel 24 is transferred to a thermal regeneration device 94 via conduit 26.
At H2The methanol scrubbing medium loaded with hydrogen sulphide in the S scrubber 4, 74 is supplied to the medium pressure H via conduit 39, 822S flash vessel 40 and therein depressurised to typically 15 to 40 bar (a). The gaseous overhead product thus obtained is transferred via conduits 41, 51, 60 and 21 to the second stage of the recompressor. From medium pressure H2The liquid bottoms of S-flash vessel 40 is passed to low pressure H via conduit 422S flash vessel 45 and therein depressurised to typically 1.5 to 15 bar (a). The gaseous overhead product thus obtained is passed via conduit 47 to the first stage of the recompressor and is introduced therein into separator 30. From low pressure H2The liquid bottoms of S flash vessel 45 is passed via conduit 46 to a flash regeneration plantAnd (5) preparing 90.
In CO2The methanol scrubbing medium loaded with carbon dioxide in the scrubber 6, 76 is supplied via conduit 49, 83 to the medium pressure CO2Flash vessel 50 and therein depressurised to typically 15 to 40 bar (a). The gaseous overhead product thus obtained is passed via conduits 51, 60 and 21 to the second stage of the recompressor. From medium pressure CO2The liquid bottoms of flash vessel 50 is transferred to low pressure CO via conduit 522Flash vessel 55 and therein depressurised to typically 1.5 to 15 bar (a). The gaseous top product thus obtained is transferred to low pressure H via conduit 572S flash vessel 45 and combined therein with the overhead product therefrom. From low pressure CO2The liquid bottoms of flash vessel 55 is passed via conduit 56 to flash regeneration apparatus 90.
The gas stream entering the two-stage recompressor is in two pressure stages compressed to the raw synthesis gas pressure level and recycled to the pre-scrubber 2 via conduits 36 and 1. The conduit 36 may also enter the prewasher 2 directly.
The loaded methanol scrubbing medium introduced into flash regeneration device 90 is depressurized therein. The depressurization is carried out in a plurality of stages (not shown) and finally a high CO is obtained2CO of purity2Product stream and lower CO2CO of purity2The exhaust stream and exits the process via conduits 91 and 92. The procedures required here and the pressure levels employed are known per se to those skilled in the art. A methanol scrubbing medium substantially loaded with hydrogen sulfide is also obtained, which is transferred via conduit 93 to a thermal regeneration device 94. This is also a multistage plant (only schematically shown) and the individual process steps and process conditions of the thermal regeneration are known to the person skilled in the art. Obtained as product of the thermal regeneration is a stream of a high-purity methanol washing medium (so-called fine washing methanol), which is recycled to the CO via conduits 98, 99, optionally after further processing steps and addition of fresh methanol2A scrubber 6, 76. Also obtained as a further product of the thermal regeneration is an acid gas stream which contains hydrogen sulphide and further sulphur components and which is discharged from the process via conduit 95 and sent to further treatment or processing. Acid gasThe stream is typically supplied to a sulphur recovery facility (not shown) operating according to, for example, the claus process.
The schematic representation of the method according to the invention/the installation according to the invention in the second embodiment shown in fig. 2 corresponds substantially to the embodiment of fig. 1. From medium pressure H in contrast to the latter2S flash vessel 40 and CO from medium pressure2The overhead of the flash vessel 50 is passed via conduits 41 and 51 to the second stage of the two-stage expander. Thus, in this particular embodiment, from medium pressure H2S flash vessel and medium pressure CO2Only a part of the flash gas of the flash vessel is utilized on the material by recompression and recycling into the raw synthesis gas entering the gas scrubbing process, while the remaining part of the flash gas is used for recovering cold and mechanical work and is thus utilized on the energy. This achieves an advantageous compromise between the material and energy utilization of the flash gas.
Industrial applicability
The present invention provides a gas scrubbing process and corresponding plant for removing acid gas components from a raw synthesis gas, which makes it possible to produce a plurality of gas products with different compositions by treating shifted and unshifted raw synthesis gas in the gas scrubbing process and by combining part of the product streams thus obtained. Furthermore, the invention ensures that the flash gas obtained during the depressurization of the loaded scrubbing medium is utilized in an advantageous manner on the material and/or on the energy.
List of reference numerals
1 guide tube
2 Pre-scrubber
3 catheter
4 H2S washer
5 catheter
6 CO2Washing device
7 guide tube
8 cooler
9 guide tube
10 turbine stage
11 catheter
12 cooler
13 catheter
14 turbine stage
15 guide tube
16 cooler
17 catheter
19 guide tube
20 medium pressure prewashing flash evaporation container
21 catheter
22 catheter
24 low pressure prewashing flash vessel
25 guide tube
26 guide tube
30 separator
31 compressor stage
32 cooler
33 separator
34 compressor stage
35 cooler
36 guide tube
39 catheter
40 medium pressure H2S flash evaporation container
41 catheter
42 catheter
45 low pressure H2S flash evaporation container
46 catheter
47 guide tube
49 catheter
50 medium pressure CO2Flash evaporation container
51 catheter
52 catheter
55 low pressure CO2Flash evaporation container
56 catheter
57 conduit
60 catheter
71 catheter
72 prewasher
73 catheter
74 H2S washer
75 guide tube
76 CO2Washing device
77 catheter
78 catheter
79 catheter
81 conduit
82 guide tube
83 conduit
84 catheter
90 flash evaporation regeneration equipment
91 guide tube
92 guide tube
93 catheter
94 Heat regeneration device
95 catheter
96 catheter
98 guide tube
99 guide tube