Method for treating water from gasification processes, logic unit configured to carry out such a method, device for treating water from gasification processes and use of a stripper in such a method

Abstract

Method for treating water from gasification processes, during or after which gasification processes raw gas (G1) is treated in the process steps or plant components of raw gas scrubbing (1), further gas cooling (3) and / or acid gas removal (4) and is then provided as synthesis gas (G4), wherein a water stream (W1) from the raw gas scrubbing and a process fluid stream (W3, W4) from the gas cooling and / or acid gas removal are treated, characterized in that - the water stream (W1; W14) is treated separately from the process fluid stream by subjecting the process fluid to a stripping (12; 112; 212) separate from the water stream (W14), - salt-free or at least substantially salt-free wash water (W12b) obtained during process fluid stripping is returned to the raw gas scrubber (1), and - the separate water stream (W14) from the raw gas scrubbing (1) is subjected directly after the raw gas scrubbing (1) to a stripping (14) designed to provide waste water (W6) that can be discharged to the environment.

Description

[0001] The invention relates to a method and a device for treating water from or in connection with gasification processes, by means of which gasification processes, for example, synthesis gas is provided. In particular, the invention relates to a method and a device by which a raw gas stream and a water stream from gasification are treated after the process steps or plant components of raw gas scrubbing, optionally gas conditioning, further gas cooling and / or acid gas removal, wherein a water stream from the raw gas scrubbing and a process fluid stream from the gas cooling or gas conditioning and / or acid gas removal are treated for fluid treatment. In particular, the invention relates to a method according to the preamble of claim 1 and a device according to the preamble of the independent device claim. The fluid treatment can optionally relate only to (waste) water or additionally to gaseous process media.A fluid can be understood as a fluid that is at least partially gaseous or at least partially liquid. Fluid treatment is therefore understood as the treatment of process media, including at least the comprehensive treatment of (waste) water that is to be discharged.

[0002] Wastewater treatment is particularly interesting for plants with upstream gasification. Hot raw gas from a gasification process, especially from coal gasification processes using the high-temperature Winkler process (HTW) or from entrained-flow gasification processes, is typically scrubbed in a scrubber to remove chloride and dust. The scrubber is fed with fresh water.

[0003] After the raw gas scrubbing, the gas stream is fed to a gas cooling or gas conditioning system. This process generates a large amount of wastewater due to the consumption of fresh water. In particular, the chloride content of the gasified coal determines the amount of water required in the process (especially raw gas scrubbing). If the chloride content is particularly high, this also leads to high water consumption, particularly in order to comply with material-related maximum values and / or discharge limits of the downstream plants regarding the chloride concentration, especially the chloride concentration in the medium discharged to the environment. In other words: If the chloride content is high, it must be diluted with a large amount of fresh water. The absolute proportion of discharged chloride is not lower in this case, but a maximum concentration must not be exceeded.

[0004] However, in many countries or regions, available water resources are very limited, or water is very precious. Minimizing water consumption would provide enormous benefits. Yet, simply providing a high water flow rate can pose challenges. Wastewater disposal is also becoming increasingly regulated in many countries. Therefore, keeping the amount of wastewater discharged and disposed of as low as possible is desirable, simply to keep process costs low. Last but not least, in some countries, plants are only permitted if they meet certain environmental protection criteria.

[0005] A system or process that requires only a comparatively small amount of water or that generates little wastewater would be desirable, particularly while observing legal guidelines regarding water quality.

[0006] Patent DE 43 18 549 C1 describes a distillation process with special cooling, in particular with a water-charged quench cooler, of overhead gas or vapors in connection with the avoidance of high water consumption or large amounts of wastewater. In a wastewater pretreatment process, the wastewater is acidified using stripping gas. Furthermore, the wastewater can be treated with steam to produce ammonia-containing, essentially salt-forming water.

[0007] German Patent Application DE 40 18 309 A1 describes a process for treating wastewater generated during raw gas scrubbing. The treatment takes place in several consecutive steps, including two steam stripping steps, after flue dust has been removed by pressure filtration. The resulting wastewater stream is discharged into the environment or biological treatment system after solids and gases, including ammonia-containing vapors, have been separated.

[0008] The object of the invention is to provide a method and a device with the features described above, allowing water to be used effectively and in a resource-saving manner. The object can also be seen in providing a plant or process configuration or a method in connection with gasification processes that allows only a small amount of water to be released into the environment or wastewater treatment and can be elegantly integrated into a gasification process or a synthesis gas plant.

[0009] This object is achieved according to the invention by a method according to claim 1 for treating water from gasification processes, during or after which gasification processes raw gas from gasification is treated in the process steps or plant components of raw gas scrubbing, optionally gas conditioning, further gas cooling and / or acid gas removal and is then made available as synthesis gas, wherein a water stream from the raw gas scrubbing and a process fluid stream from the gas conditioning or gas cooling and / or acid gas removal are treated, wherein the water stream is treated separately from the process fluid stream by subjecting the process fluid to process fluid stripping separate from the water stream. By separating the (waste) water stream from the process fluid stream, in particular downstream of the raw gas scrubbing, the required amount of fresh water and possibly also the amount of wastewater can be reduced by a considerable factor.Chemical-physical wastewater pretreatment can be carried out in a particularly resource-saving manner.

[0010] The process fluid can be at least partially gaseous or at least partially liquid. Process fluid or process condensate from raw gas scrubbing, gas cooling, and / or acid gas removal cannot usually be reused untreated. Until now, wastewater and process condensates were typically treated in a (single) wastewater pretreatment unit. The entire wastewater was then discharged into the environment (or to wastewater post-treatment) or for evaporation. Evaporation can reduce the amount of wastewater in energy terms, but this can be particularly beneficial. However, the wastewater was not typically reused. Typically, only a single wastewater stream was generated, which was discharged without any further use.

[0011] In contrast, the process described here allows for separate treatment of saline water and at least essentially salt-free process fluid / condensate. The entire amount of water from the process fluid stripping can be recycled within the overall plant. In particular, only the amount of water from the wastewater stripping needs to be released into the environment. This reduction in the amount of water to be released brings with it various advantages, particularly a reduction in freshwater consumption. The plant itself can also be operated with less heavily contaminated water, particularly water with a low salt content.

[0012] By treating the water stream separately from the process fluid stream, the amount of wastewater discharged to the environment or the composition of this wastewater can also be controlled in a very simple or flexible way.

[0013] The gasification processes take place, for example, at temperatures in the range of 800°C to 1200°C, and / or pressures in the range of 10 bar to 30 bar.

[0014] In contrast to the aspects described in DE 43 18 549 C1, a device or a method according to the present invention can relate to an entire, comprehensive wastewater management system or at least be incorporated therein. The apparatus technology used in patent DE 43 18 549 C1 can be used at least in part, at least with regard to individual components of the devices described here. The wastewater purification or pretreatment can be carried out, for example, using stripping gas and steam, in particular in such a way that NH3 vapor is produced. During process fluid stripping, stripping gas, e.g. a gas mixture with preferably at least 90% CO2, can be fed to a column, whereby a CO2-rich gas stream can be used for this purpose during acid gas removal. Steam can be fed to the column, in particular in such a way that NH3 water and acid gas are produced.

[0015] By separating the water stream from the process fluid stream, a particularly large amount of physically purified process media can be reused.

[0016] According to one embodiment, the process fluid stripping is carried out in such a way that two separate fluid streams are produced, namely a first fluid stream comprising wash water and a second fluid stream comprising process water. This enables more flexible use of the resulting water, in particular by reusing process water internally and recycling wash water, in particular for raw gas scrubbing. The fluid fed to the process fluid stripping can contain salt or have a significantly higher salt content than the wash or process water, which is essentially salt-free after stripping. Recirculated streams can be essentially salt-free. The process fluid stripping can generate at least four outgoing streams, in particular NH3 water, sour gas, salt-free purified process water, and salt-free purified wash water.

[0017] It has been shown that recirculation can lead to a significant reduction in the amount of fresh water previously required for raw gas scrubbing, or even to the elimination of fresh water altogether. The process or the corresponding device is configured, e.g., a flow rate of 10m 3 / h of wash water. The flow rate varies depending on the system and may also depend on the type of gas conditioning.

[0018] According to one variant, for example, a volume flow of 15m 3 / h washing water and a volume flow of 11m 3 / h wastewater, with particular emphasis on approx. 28m 3 / h of condensate can be treated.

[0019] According to an alternative plant or process control, for example, a volume flow of approx. 55m 3 / h washing water and a volume flow of approx. 13m 3 / h wastewater. The interdependence of these volume flows must be defined for each specific plant and optimized specifically for the respective process.

[0020] During process fluid stripping, the purified water obtained, i.e. salt-free or at least essentially salt-free scrubbing water (upstream), is returned to the gas cooling system, i.e. to the raw gas scrubbing system. It has been shown that this allows the amount of wastewater discharged into the environment to be made up by a huge factor / proportion using water from the process, i.e. not fresh water, but water that has already been used. The required amount of fresh water can be reduced to approximately 25% of the wastewater volume for processes without separation of the wastewater stream or without recirculation. Purified water produced during process fluid stripping, in particular process water, can simultaneously be made available for further use in the overall plant. This results in very resource-efficient water management.

[0021] According to one embodiment, the process fluid obtained during process fluid stripping is salt-free or at least substantially salt-free, in particular in the form of purified scrubbing water, which is used separately from internally reused process water, in particular provided for recirculation to the raw gas scrubbing, and / or in the form of purified internally reusable / reused process water, which is provided for reuse in the overall plant. At least substantially salt-free, recirculated process water / scrubbing water also provides advantages with regard to corrosion of plant components.

[0022] Process water is generally alkaline. Alternatively, the process water can be made alkaline by adding caustic. This allows for effective scrubbing of chloride from the raw gas. A caustic addition system or a device for adjusting the pH value of the process water can be located, for example, within or downstream of the process fluid stripping system.

[0023] According to one embodiment, the process fluid stripping comprises both a process condensate stripper and an NH3 stripper, with NH3 stripping taking place behind or downstream of the process condensate stripper. The two strippers can be connected via a stripper coupling or at least one line between the stripper columns. In this case, the NH3 stripping can take place together with the process condensate stripping, for example, in an NH3 stripper downstream of a process condensate stripper.

[0024] The process described here can be carried out by means of a plant or device comprising at least three stripping columns, of which one column is provided for the (waste) water stream downstream of the raw gas scrubbing, and two stripping columns, in particular connected in series, are provided for process fluid downstream of the gas cooling or acid gas removal.

[0025] According to one embodiment, CO2-containing gas is extracted for stripping a desulfurization stage. This results in process-related advantages for the overall process. According to one embodiment, a gas containing more than 50 vol.% CO2, in particular more than 70 vol.% CO2 or more than 90 vol.% CO2, is used as the stripping gas. This also provides process-related advantages for the overall process. According to one embodiment, during process fluid stripping, NH3 water and sour gas, in particular sour gas for post-combustion, are provided in separate streams or lines. As already mentioned, process fluid stripping can generate four outgoing streams: in particular NH3 (strong) water, sour gas, purified (salt-free) process water, and purified (salt-free) wash water.

[0026] The separate water stream from the raw gas scrubbing is subjected to a stripping process to produce wastewater that can be discharged to the environment, i.e., directly after or downstream of the raw gas scrubbing process. The stripped wastewater stream can be discharged directly after stripping into the environment or wastewater treatment downstream of a stripper column. This also allows for a simple, cost-effective plant configuration.

[0027] According to one embodiment, the separate water stream from the raw gas scrubbing corresponds to a proportion of less than 35%, preferably less than 30%, more preferably less than 25% of the process fluid stream fed to the process fluid stripping. This allows a comparatively large proportion of the water to be used for the process without having to consume fresh water. At such proportions, the aforementioned advantages become particularly noticeable, especially with regard to the amount of wastewater discharged into the environment.

[0028] The proportion also depends on the chloride content of the coal used. The type of gas conditioning can also influence the chloride content and thus the proportion defined above. However, it has been shown that the proportion can be surprisingly low with the present process. In particular, proportions below 15% can be achieved with certain plant configurations.

[0029] According to one embodiment, the separate water stream from the raw gas scrubber is discharged as wastewater into the environment or to a wastewater post-treatment facility after a stripping step. This results in a process that is easy to handle and control, with comparatively low plant engineering expenditure. At the same time, overhead gas or vapors can also be discharged for post-combustion, particularly downstream of the wastewater stripper.

[0030] According to one embodiment, the separate water stream downstream of the raw gas scrubber and separately from the process fluid stream is treated in a pretreatment or purification stage, in particular stripping, such that the water stream can be discharged into the environment after the purification stage, separately from the process fluid stream. This allows for a particularly simple plant or process configuration. In particular, advantages also arise with regard to the material selection for individual plant components.

[0031] According to one embodiment, process fluid stripping closes an internal water circuit between the raw gas scrubber on the one hand and the gas cooling or gas conditioning and / or acid gas removal on the other hand, in particular such that a water volume flow of the water circuit returned to the raw gas scrubber at least partially forms the wastewater stream to be discharged to the environment and, in particular, also reduces the freshwater consumption of the raw gas scrubber. In conjunction with the process fluid treatment, this makes it possible to control the manner and the proportion of freshwater consumed and the wastewater treated and discharged.

[0032] The aforementioned object is also achieved by a logic unit configured to control or regulate a previously described method, wherein the logic unit is configured to control at least one distributor on an internal water circuit for recirculating at least one process fluid stream, in particular a salt-free wash water stream. This allows for a significant reduction in the amount of recirculation and thus also in the required amount of fresh water.

[0033] The aforementioned object is also achieved by a water treatment device for treating water from gasification processes, in particular by a device configured to carry out a previously described method, with a wastewater stripping downstream of a raw gas scrubber, wherein the water treatment device also comprises a stripping for a process fluid stream separate from the water stream, which is separate from the wastewater stripping. This results in the aforementioned advantages. The water treatment device is configured to separate salt-containing fluid from at least substantially salt-free fluid, and to provide at least substantially salt-free (washing or process) water that can be reused internally in the process.

[0034] Advantages also arise with regard to the material selection for individual plant components. Stripping saline, corrosive wastewater previously required high-quality materials. By reducing the wastewater volume, the equipment components made of corrosion-resistant materials can be designed smaller and thus more cost-effectively. The comparatively large, salt-free volume flows can be handled with less expensive equipment made of less expensive (less corrosion-resistant) materials.

[0035] The process fluid stripping is part of an internal circuit, whereby the process fluid stripping is connected to the raw gas scrubbing in such a way that the process fluid stream is at least partially recyclable to the raw gas scrubbing, i.e., as an at least substantially salt-free scrubbing water stream. This allows the amount of fluid required, especially fresh water, to be reduced considerably.

[0036] The device can have a return line set up for volume flows (especially washing water) greater than or equal to 10m 3 / h. This allows a large amount of the required fresh water to be replaced with wash water, or even completely.

[0037] According to one embodiment, the process fluid stripping system comprises at least two strippers, in particular an NH3 stripper connected in series downstream of a process condensate stripper. This results in further advantages with regard to the possibilities for further use of the fluids within the process.

[0038] According to one embodiment, the process fluid stripping system has at least four outlets, each comprising an outlet for vapor or sour gas, an outlet for scrubbing water, an outlet for process water, and an outlet for NH3-rich water, wherein at least one of the outlets is a component of / of the internal circuit of the water treatment device. This allows a process fluid stream to be split in such a way that individual substreams can be reused in a particularly expedient manner.

[0039] According to one embodiment, the process fluid stripping system comprises a distributor configured or arranged to split the process fluid stream, in particular a water stream, into reusable process water and recyclable wash water. This allows the individual streams to be easily controlled, in particular downstream of the process condensate stripper. The process water can be discharged, in particular, downstream of an NH3 stripper, which is arranged downstream of the process condensate stripper.

[0040] The aforementioned object is also achieved by using at least one stripper for a process fluid stream separate from a water stream from gasification processes, in particular in a previously described device, in conjunction with a recirculation of at least a portion of the process fluid stream in an internal water circuit. This saves process fluid, and the plant components can be operated with a comparatively uncontaminated fluid or medium. The main advantage is a reduced amount of wastewater discharged into the environment.

[0041] Further features and advantages of the invention will become apparent from the description of at least one embodiment with reference to drawings, as well as from the drawings themselves. Fig. 1 shows a schematic representation of the process flow for pretreating wastewater according to the state of the art; Fig. 2 shows a schematic representation of a plant structure and a process flow for treating water according to an embodiment; Fig. 3 shows a schematic representation of a plant structure and a process sequence for treating water according to a further embodiment; and Fig. 4 shows a detailed, schematic representation of a plant structure and a process sequence for treating water according to a further embodiment.

[0042] For reference symbols that are not explicitly described in relation to a single figure, reference is made to the other figures.

[0043] The Fig. Figure 1 shows a previously known wastewater treatment system in conjunction with a gasification process. Raw gas, or a raw gas stream G1, is fed to a raw gas scrubber 1, followed downstream by a gas conditioning 2 or gas cooling 3 and an acid gas removal 4, and can then be provided as syngas or synthesis gas stream G4. A water stream W1 from the raw gas scrubber 1, a process fluid stream W3 from the gas cooling 3, and also a process fluid stream W4 from the acid gas removal 4 are fed to a wastewater pretreatment 5, from which a wastewater stream W6 is discharged to the environment or to the biological treatment 6. The wastewater pretreatment 5 includes stripping. A stripping gas stream Gs is fed together with steam Gd to a stripper column, and NH3 vapor or NH3 water G5.1 and an acid gas stream G5.2 are discharged. However, with this configuration, the water consumption is quite high. The amount of wastewater discharged is also disadvantageously large.

[0044] The Fig. Figure 2 shows the previously described setup downstream of a gasification process. However, water W14 is now fed directly to a separate stripping unit 14.

[0045] The raw gas G1, particularly hot raw gas from gasification, is scrubbed in a scrubber (raw gas scrubber 1), primarily to remove chloride and dust. The gas can then be fed to a gas conditioning unit 2 in a dedicated process plant, for example, via an HCN / COS hydrolysis unit, and then cooled for delivery to a gas scrubber. The gas can also be fully converted and then cooled to produce hydrogen, or partially converted with a hydrolysis stage and then cooled to produce synthesis gas.

[0046] The water stream W14 from the at least one scrubber 1 contains chloride. The discharged water volume depends on the chloride concentration. It has now been shown that a considerable amount of water can be saved if this water stream is separately stripped of dissolved and chemically bound gas components in a stripper. Due to the chloride content, the treated wastewater W6 is then no longer used internally but is preferably discharged directly to the environment 6.

[0047] Likewise, the process condensates W3 and W4 generated during gas cooling can be treated separately, particularly together with other (waste) water streams from downstream plant components. After removal of the dissolved and chemically bound gas components by stripping 12, the water can be reused in the process, particularly by providing both a salt-free process water stream W12a and a salt-free wash water stream W12b.

[0048] In the following, the wastewater stripping 14 at a treatment plant 10; 100 according to Fig. 2 or Fig. 3. The water W14, which is discharged from the raw gas scrubber 1, contains, in addition to dissolved gases, all of the chloride from the raw gas G1. In order to remove the dissolved and partly chemically bound gases, the water is conveyed, in particular pumped, to a stripper column 14 or 14.1. In the stripper column, the dissolved gases are removed at elevated temperature until the bottom product of the column falls below the maximum permissible concentration of dissolved gases. The energy required for this can be provided, for example, via a steam-heated column reboiler ( Fig. 4) are supplied.

[0049] The column vapor G14 with the stripped gases is preferably fed to an afterburner ( Fig. 3). For this purpose, the vapor is advantageously cooled to reduce the amount of water vapor in the gas stream. This is done, for example, in a quench cooling system, especially if the condensed water is highly corrosive due to the gases dissolved in it and concentrated by the stripping process, making a conventional heat exchanger (air- or water-cooled) unsuitable.

[0050] The hot vapor is directed from the side into the quench cooling vessel from below. Cool water at a temperature of approximately 80 °C is added from above, distributed through a built-in packing. The direct contact of the hot vapor with the cool water cools the gas stream and condenses the water. In particular, individual components or process steps described in patent DE 43 18 549 C1 can be used for cooling.

[0051] The water condensed in the quench cooler, for example, is pumped from the bottom of the vessel, cooled in a plate heat exchanger, specifically to 80 °C, and then returned to the quench cooler packing. Excess water can be returned to the top packing of the stripper at a controlled level. A lower temperature should not be selected, especially if there is a risk that the chemically bound gases could form salts that crystallize and clog system components.

[0052] The cooled vapor G14 can be piped to an afterburner under pressure control. The corresponding pipeline can be equipped with trace heating to prevent condensation in the line.

[0053] The bottom product W6 from the stripping column can be withdrawn at a controlled level and pumped to the plant boundary. Before being discharged to the environment 6, the water can be cooled to 30 to 40°C in a plate heat exchanger. The exact required temperature must usually be coordinated with the wastewater collection point.

[0054] In the following, the process fluid stripping 12; 112 in a treatment plant 10; 100 according to Fig. 2 or Fig. 3. Large quantities of condensates typically occur during conditioning 2 and cooling 3 of the raw gas G1 downstream of scrubber 1. These process condensates from conditioning or cooling, as well as wastewater from optional downstream plant components, typically do not contain chloride. It has now been shown that these streams can be elegantly recirculated into the process after appropriate treatment.

[0055] The dissolved and partially chemically bound gas components are removed downstream of the raw gas scrubber in a stripper column 12, 12.1 ( Fig. 3) removed at elevated temperature. Typically, large amounts of ammonia NH3 are also dissolved in the process condensates, which can be used to produce ammonia-rich water W12.2 and thus should not be removed. Therefore, in addition to steam Gd, carbon dioxide CO2 is also advantageously used as a stripping gas Gs. Examples include the following proportions: 1000 kg process condensate, 250 kg CO2, 150 kg steam.

[0056] It has been shown that it is particularly advantageous to carry out the process fluid stripping in two separate strippers 12.1, 12.2 ( Fig. 3), namely a process condensate stripper 12.1 and a separate ammonia stripper 12.2. Such an advantageous process control is described below.

[0057] CO2 (Gs12; Gs12.1) injected into the lower third of a column of the process condensate stripper 12.1 binds the ammonia in the water to form ammonium bicarbonate, which collects in the column bottom. Steam Gd12; Gd12.1 injected into the column from below causes the ammonium bicarbonate in the bottom to be thermally decomposed, and the released CO2 and the gas components dissolved in the process condensate are stripped off overhead. Thus, a large portion of the free ammonia W12.2 can be discharged at or with the column bottom 12d.

[0058] The column vapor G12.1 from the process condensate stripper 12.1 can also be cooled in a quench cooler and fed to the afterburner, particularly similar to wastewater stripping. Excess condensate in the sump of the quench tank can be recirculated to the top packing of the stripper at a controlled level.

[0059] A portion of the stripped process condensate in the sump 12b of the process condensate stripper column 12.1 can now be pumped (back) to scrubber 1 and reused, particularly as wash water W12b via a line that is part of an internal water circuit WC. It has been shown that this alkaline water promotes the quantitative leaching of chloride from the raw gas G1 or synthesis gas G4. A further advantage is that this measure can reduce or completely replace the amount of fresh water required to be fed to scrubber 1. The remaining bottom product can, for example, be fed to another stripper column 14 for further processing.

[0060] A second stripper column 12.2 of the process fluid stripping 12 serves to separate ammonia. The bottom product of the process condensate stripper can be pumped via a coupling or connecting line 112.1 to the feed tray of this ammonia stripper 12.2. The supply of the necessary reboiling energy for the stripper 12.2 can be achieved, for example, by means of a steam-heated column reboiler 12.3 ( Fig. 4). The ammonia-enriched column vapor can be cooled in a quench cooler (process or plant component).

[0061] To produce ammonia liquor W12.2, the vapor from the quench cooling system can be condensed in a vertical condenser with the addition of water. The amount of water added is adjusted to produce a storable ammonia liquor. This ammonia liquor can be advantageously reused in other plant components, for example, in exhaust gas purification for NOx reduction.

[0062] Salt-free water W12a collected in the sump of the ammonia stripper with a residual ammonia content of less than 5 ppm can also be used in other parts of the plant as make-up water, for example in a deionized water plant.

[0063] Fig. 3 shows the at least four outlets 12a, 12b, 12c, 12d of the process fluid stripper 12. A manifold 16 is arranged on or downstream of the process condensate stripper 12.1 and in communication with a logic unit 18.

[0064] The internal water circuit WC can be formed, for example, by three or four line sections or lines, in particular a first and optionally also a second line section WC1, WC2 between raw gas scrubbing 1 and / or gas conditioning 2 or gas cooling 3, and a further line section WC3 towards the process fluid stripping 12, as well as the return line WC4 back to the raw gas scrubbing 1.

[0065] Fig.Figure 4 describes in detail a water treatment plant 200, in which additional plant components or lines / process streams can be provided. In particular, the NH3 stripper 12.2 has an outlet 12d.1 leading to the column reboiler 12.3, which has an outlet 12d.2 from which the discharge line W12.2 for NH3 heavy water branches off. Process water F4 can be supplied to the column reboiler 12.3. Sodium hydroxide solution F2 can be supplied to the NH3 stripper. Sodium hydroxide solution F2 can also be supplied to the stripper 14.1 via line F1. Furthermore, an optional coupling of the supply of process water F4 to the stream of purified process water W12a can be achieved via line F5 (dash-dotted line, optional). An optional addition of caustic to the recirculated stream of purified process water W12b can also be carried out via line F3 (dotted line, optional). List of reference symbols 1 Raw gas scrubbing (process or plant component) 2 Gas conditioning (process or plant component) 3 Gas cooling (process or plant component) 4 Acid gas removal (process or plant component) 5 Wastewater pretreatment according to the state of the art 6 Environment or biology G1 Raw gas or raw gas stream, in particular from gasification Gs stripping gas or stripping gas stream Gd steam G4 Syngas or synthesis gas stream G5.1 NH3 vapors or NH3 water G5.2 Sour gas (stream) W1 Water or water stream from raw gas scrubbing for pretreatment W3 Process fluid flow from gas cooling to pretreatment W4 Process fluid stream from acid gas removal to pretreatment W6 Wastewater or wastewater stream discharged into the environment or for biology 10; 100; 200 water treatment plant 12;112 Process fluid stripping (process or plant component) 12.1 Process condensate stripper 12.2 NH3 stripper or ammonia stripper 12.3 Column reboiler 112.1 Stripper coupling 12a, 12b, 12c, 12d; 12d.1, 12d.2 outlet 14 Stripping to provide wastewater 14.1 Stripper or stripping column 16 distributors 18 Logic unit F1, F2 sodium hydroxide or NaOH stream F3 optional addition of lye or NaOH stream F4 Process water F5 optional coupling of process water supply to W12a G12.1 Vapours or sour gas or sour gas stream, especially for post-combustion Gs12; Gs12.1 Stripping gas or stripping gas stream Gd12; Gd12.1 steam G14 Vapours or sour gas or sour gas stream, especially for afterburning W12a (first) stream of purified process water, especially for internal reuse W12b additional stream of purified process water, especially for recirculation W12.2 NH3 heavy water or ammonia water stream W14 Water or water flow from the raw gas scrubber to the wastewater stripping WC internal water circuit WC1 first pipe section of the water circuit WC2 Water pipe or further pipe section of the water circuit WC3 Water pipe or further pipe section of the water circuit WC4 Return line or further section of the water circuit

Claims

[1] Process for the treatment of water from gasification processes, during or after which gasification processes raw gas (G1) is treated in the process steps or plant components of raw gas scrubbing (1), further gas cooling (3) and / or acid gas removal (4) and is then provided as synthesis gas (G4), wherein a water stream (W1) from the raw gas scrubbing and a process fluid stream (W3, W4) from the gas cooling and / or acid gas removal are treated, characterized by , that - the water stream (W1; W14) is treated separately from the process fluid stream by subjecting the process fluid to a stripping (12; 112; 212) separate from the water stream (W14), - salt-free or at least substantially salt-free wash water (W12b) obtained during process fluid stripping is returned to the raw gas scrubber (1), and - the separate water stream (W14) from the raw gas scrubbing (1) is subjected directly after the raw gas scrubbing (1) to a stripping (14) designed to provide waste water (W6) that can be discharged to the environment. [2] Method according to claim 1, wherein the process fluid stripping (12; 112; 212) is carried out in such a way that two separate fluid streams are produced, namely a first fluid stream comprising process water (W12a) and a second fluid stream comprising wash water (W12b). [3] Method according to one of the preceding method claims, wherein the process fluid stripping (12; 112; 212) comprises both a process condensate stripper (12.1) and an NH3 stripper (12.2), wherein NH3 stripping takes place downstream of the process condensate stripper. [4] Process according to one of the preceding process claims, wherein CO2-containing gas is taken for the stripping of a desulfurization stage, and / or wherein a gas of more than 50 vol.% CO2, in particular more than 70 vol.% CO2 or more than 90 vol.% CO2 is used as stripping gas. [5] Method according to one of the preceding method claims, wherein the separate water stream (W14) from the raw gas scrubber (1) corresponds to a quantity proportion of less than 35%, in particular less than 25%, of the process fluid stream (W3, W4) supplied to the process fluid stripping (12). [6] Method according to one of the preceding method claims, wherein the separate water stream (W14) from the raw gas scrubber (1) is discharged into the environment (6) as waste water (W6) after stripping (14). [7] Method according to one of the preceding method claims, wherein by means of the process fluid stripping (12; 112; 212) an internal water circuit (WC) is closed between the raw gas scrubbing (1) on the one hand and the gas cooling (3) and / or acid gas removal (4) on the other hand, in particular in such a way that a water flow (W12b) of the water circuit (WC) returned to the raw gas scrubbing (1) at least partially forms the waste water flow (W6) to be discharged to the environment. [8] Logic unit (18) configured to control or regulate a method according to one of the preceding method claims, wherein the logic unit is configured to control at least one distributor (16) on an internal water circuit (WC) for recirculating at least one process fluid stream (W3, W4). [9] Water treatment device (10; 100; 200) for treating water (W1; W14) from gasification processes, in particular a device designed to carry out a method according to one of the preceding method claims, with a wastewater stripping (5; 14) downstream of a raw gas scrubber (1); characterized by , that - the water treatment device also comprises a stripping (12; 112; 212) for a process fluid stream (W3, W4) separate from the water stream (W6, W14), which is separate from the wastewater stripping (14); and - the process fluid stripping (12; 112; 212) is part of an internal circuit (WC), wherein the process fluid stripping is connected to the raw gas scrubber (1) in such a way that the process fluid stream (W3, W4) is at least partially recyclable to the raw gas scrubber (1), and - the separate water stream (W14) from the raw gas scrubbing (1) is subjected directly after the raw gas scrubbing (1) to a stripping (14) designed to provide waste water (W6) that can be discharged to the environment. [10] Water treatment device according to the preceding claim, wherein the process fluid stripping (12; 112; 212) comprises at least two strippers (12.1, 12.2), in particular an NH3 stripper (12.2) connected in series behind a process condensate stripper (12.1). [11] Water treatment device according to one of the preceding device claims, wherein the process fluid stripping (12; 112; 212) has at least four outlets, each comprising an outlet (12c) for vapors or sour gas, an outlet (12b) for wash water, an outlet (12a) for process water and an outlet (12d) for NH3 strong water, wherein at least one of the outlets is a component of / of the internal circuit (WC) of the water treatment device (10; 100; 200); and / or wherein the process fluid stripping (12; 112; 212) has a distributor (16) configured or arranged to split the process fluid stream (W3, W4) into reusable process water (W12a) and recyclable wash water (W12b). [12] Use of at least one stripper (12, 12.1, 12.2) for a process fluid stream (W3, W4) separated from a water stream (W1; W14) from gasification processes, in a device (10; 100; 200) according to one of the preceding device claims, in conjunction with a recirculation of at least a part (W12b) of the process fluid stream in an internal water circuit (WC).

Images