EP3571157A1 - Verfahren zur flexiblen steuerung der verwendung von salzsäure aus chemischer produktion - Google Patents
Verfahren zur flexiblen steuerung der verwendung von salzsäure aus chemischer produktionInfo
- Publication number
- EP3571157A1 EP3571157A1 EP18700374.4A EP18700374A EP3571157A1 EP 3571157 A1 EP3571157 A1 EP 3571157A1 EP 18700374 A EP18700374 A EP 18700374A EP 3571157 A1 EP3571157 A1 EP 3571157A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- hydrochloric acid
- stage
- neutralization
- reaction mixture
- station
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B7/00—Halogens; Halogen acids
- C01B7/01—Chlorine; Hydrogen chloride
- C01B7/03—Preparation from chlorides
- C01B7/04—Preparation of chlorine from hydrogen chloride
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B7/00—Halogens; Halogen acids
- C01B7/01—Chlorine; Hydrogen chloride
- C01B7/07—Purification ; Separation
- C01B7/0706—Purification ; Separation of hydrogen chloride
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
- C02F1/461—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/66—Treatment of water, waste water, or sewage by neutralisation; pH adjustment
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
- C02F2101/10—Inorganic compounds
- C02F2101/12—Halogens or halogen-containing compounds
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W90/00—Enabling technologies or technologies with a potential or indirect contribution to greenhouse gas [GHG] emissions mitigation
Definitions
- the invention relates to a method for flexible control of the use of hydrochloric acid from chemical production on an industrial scale and a system for this purpose.
- the invention is based on known per se industrial processes for the neutralization of hydrochloric acid, for example, as a reaction by-product in the production of plastic or
- the purification of hydrogen chloride can be carried out, for example, according to US 6719957 by liquefaction and distillation.
- the condensed organic impurities can be removed.
- EP 1743882 B1 also describes the hydrogen chloride purification on A coal, although other adsorbents are also possible.
- the absorption of the hydrogen chloride to form hydrochloric acid can be carried out by various methods, e.g. described in the Handbook of Chlor-Alkali Technology (2005), page 1364.
- hydrochloric acid can be carried out by different methods.
- One method is purification in which the hydrochloric acid is stripped by means of steam (Ulimann Encyclopedia of Industrial Chemistry, Vol. 18, 2002, Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim, Hydrochloric Acid, p 191 et seq., EP 1743882 Bl, in particular claim 1)
- EP 1743882 Bl also describes that inorganic impurities are removed by means of chelating ion exchangers.
- the purified hydrochloric acid may then be recycled, i. the formation of chlorine, which is returned to the chemical process, be used in a hydrochloric acid electrolysis with diaphragm or with gas diffusion electrodes.
- the hydrogen chloride is already separated from the chemical production process, it can be subjected to gas phase oxidation according to the Deacon process and reacted with oxygen to form chlorine and water.
- This hydrogen chloride take-off point can only be used if a Deacon process is available at or near the site and hydrogen chloride from the chemical process is generated.
- the Deacon process is not complete, so that the unreacted hydrogen chloride must be separated from the reaction product chlorine together with the water formed.
- the resulting hydrochloric acid must also be fed to a suitable workup or use.
- the Deacon process is a very economical, alternative recycling process.
- hydrochloric acid daily production from an isocyanate plant eg a Toluoldiisocynant production (TDI) with an exemplary capacity of 100,000 t / a storage capacity of 750 m 3 hydrochloric acid (30 wt.%) Is necessary.
- TDI Toluoldiisocynant production
- the reason for this is the highly corrosive properties of hydrochloric acid, which require high-quality materials for the storage containers and a high level of maintenance.
- part of the hydrochloric acid is made available from the warehouse to other chemical processes and usually transported by rail tank cars, ships or lorries to other points of consumption.
- the hydrochloric acid is from the ongoing chemical production, in which the hydrochloric acid is formed and shipped to the warehouse via a shipping station.
- Critical situations can arise when higher volumes of hydrochloric acid need to be stored or recycled than can be delivered via the shipping station. This may be the case, e.g. on public holidays, where driving restrictions apply to trucks, as well as in high-deep water for ship transport or lack of availability of rail tank cars or trucks.
- the failure in the field of recycling processes can lead to a dramatic excess of hydrochloric acid, which ultimately means that the ongoing chemical production must be turned off.
- the object of the invention is to establish a flexible hydrochloric acid management, which avoids stopping or throttling the chemical production process, the hydrogen chloride or hydrochloric acid as a byproduct.
- the hydrogen chloride or the resulting hydrochloric acid is supplied to the sale after purification.
- Hydrochloric acid is of great importance in the chemical industry as an inorganic acid. Hydrochloric acid is used, for example, in the workup of ores and crude phosphate. It is used in the acid treatment of petroleum and natural gas sources as well as in metalworking during pickling, etching and brazing. As a food additive, hydrochloric acid is called E 507. If it can no longer be sold or sold at the site where the hydrochloric acid is produced, the storage capacity is quickly exhausted. If the sale does not recommence, alternative recycling processes must be used early on. These include the HC1 diaphragm, the HCl SVK electrolysis or the gas phase oxidation according to the Deacon method.
- hydrochloric acid electrolysis such as HCl diaphragm or HCl -SVK electrolysis or not available and the hydrochloric acid is no longer in the chlorine - Alkali electrolysis are recorded, remains only the way to neutralize the hydrochloric acid. Since it is about gr volumes of hydrochloric acid, the neutralization is a technical challenge and can be carried out in particular as follows. The chemical principles of neutralization are extensively described in the literature. According to the Arrhenius Concept (1887) and its extension by Bronsted-Lowry (1923), neutralization is the reaction between an acid and a base.
- An acid is defined as a substance that can dissociate to form hydronium ions or oxonium ions (H 3 O + ) in aqueous solution and release protons.
- a base describes a substance which, upon dissociation in aqueous solution, forms hydroxide ions (OH) and can take up protons (see MORTIMER, Charles E. MÜLLER, Ulrich: Chemie - Dasmaschinen gleich der Chemie, 8th Edition , 2001, pp. 234 and 282).
- the discontinuous method of titration for determining a graph for displaying the pH is known for laboratory operation. It will be too A small amount of the base is gradually added to a defined amount of an acid, and the pH is determined by an indicator (compare MORTIMER, Charles E. MÜLLER, Ulrich: Chemie
- WO2008083997A1 discloses a continuous process for the neutralization of a hydrochloric acid-containing reaction mixture following the production of diphenylmethanediamine (MDA), in which the acid is neutralized with ammonia, followed by separation of the reaction mixture into the aqueous and organic phases.
- MDA diphenylmethanediamine
- the separation of the ammonia from the aqueous phase by means of an oxide or hydroxide of an alkaline earth metal is possible via a further process.
- the weak base ammonia (pH 9.4) is added as a neutralizing agent to an acidic reaction mixture after the MDA reaction and after the neutralization reaction, a separation of the organic from the aqueous phase is carried out separately to work up both phases or to recover a portion of the amount of ammonia used by reaction with milk of lime and subsequent distillation.
- a further industrial application of neutralization on an industrial scale is found, for example, in the treatment of municipal or process-technical wastewaters, which preferably occur as acidic mixed wastewaters.
- a pH-neutral state (pH 7) is sought, which is achieved by adding strong acids and bases (usually sulfuric acid and caustic soda or alternatively lime) between the computer and the primary treatment.
- strong acids and bases usually sulfuric acid and caustic soda or alternatively lime
- the addition of these substances serves to precipitate metal ions through the formation of metal hydroxides.
- This process is referred to as neutralization precipitation and usually takes place in continuous treatment plants. In this case, average residence times of 15 minutes are sought at a mean throughput of 10 m 3 / h and mixing takes place by means of slowly running mixing elements.
- the focus here is on the separation of metal hydroxides by sinking processes, so that downstream deposition processes are required (see HARTINGER, Ludwig: Handbook of wastewater and recycling technology, 2nd edition, 1991, p 294 ff).
- the invention relates to a process for the flexible control of the use of hydrochloric acid with an HCl concentration of at least 10 wt .-%, in particular with a volume flow of at least 1 m / 'h, obtained from a continuous chemical production process, which is characterized that purified hydrochloric acid from a hydrochloric acid storage either a shipping station, an HCl electrolysis station or a chlor-alkali electrolysis station, which are sites for the hydrochloric acid, or a neutralization station is supplied by the failure of one or more of the above-mentioned points or bottlenecks of the
- the hydrochloric acid is supplied to the neutralization station and neutralized with concentrated caustic, in particular with concentrated caustic soda, and the resulting salt solution is optionally supplied to the chloralkali electrolysis station or to a disposal station.
- the method principle is described below by way of example with reference to the overview in FIG. 5.
- hydrogen chloride gas is generated, which is optionally first supplied to a HCl purification B or reacted directly in a HO absorption C with water to hydrochloric acid 44.
- the hydrogen chloride 42, 43 from purification B may be supplied to HO absorption C or HCl gas phase oxidation K.
- the HCl gas purification B can preferably be carried out by condensation of the hydrogen chloride at low temperature and / or high pressure followed by a distillative purification or the purification is carried out by freezing the impurities.
- the resulting purified HCl fraction can be subsequently purified further on carbon.
- HCl absorption of the hydrogen chloride in water in an absorption unit C so the released energy can be used to generate steam within the absorption unit C and remove impurities from the hydrochloric acid with this vapor.
- steam may be added to the unit for stripping out impurities.
- the absorption C is preferably carried out in only one apparatus. Alternatively, other absorption methods according to the prior art can be used. For this purpose, steam is fed by way of example in a column in the bottom.
- the hydrogen chloride to be absorbed is placed in the middle part of the column and the absorption solution, a hydrochloric acid 48 having a concentration of I - 25 wt.%, Preferably 15- 25 wt.% Hydrochloric acid, abandoned in the top of the column.
- the charged hydrochloric acid 48 may be wholly or partly derived from a low-concentration hydrochloric acid, the HCl electrolysis (F) z. B. was removed by the diaphragm method or the HC1-SVK method.
- the absorption process is conducted especially adiabatically.
- Impurities such as solvents or organic impurities or, if the chemical process is an isocyanate production, also residues of phosgene can be taken off at the upper column part of the absorption column of absorption C.
- the column is a 26-36 wt .-% hydrochloric acid 44 taken, preferably a 30 wt.% Hydrochloric acid and optionally the hydrochloric acid cleaning D supplied.
- the resulting hydrochloric acid 44 can be purified in the hydrochloric acid purification D, for example with A coal.
- Alternative purification methods such as distillation, stripping with steam, extraction or treatment with other adsorbents are also possible.
- the content of organic impurities for further use, for example in electrolysis, both the hydrochloric acid and the NaCl electrolysis, should, measured at the TOC content (total organic carbon) of less than 100 mg / kg, preferably less than 10 mg / kg. For other applications of hydrochloric acid, this must usually be present in a purified form.
- the resulting hydrochloric acid from the purification D can be fed to a storage E.
- the hydrochloric acid storage E can act as a distribution point, which need not be so exclusively. It is also conceivable that the receiving sites hydrochloric acid electrolysis F, NaCl electrolysis 1, or other hydrochloric acid consumers at the site (not shown), the hydrochloric acid directly. Preferably, however, a buffer in the form of a bearing E is interposed.
- hydrochloric acid electrolysis F One of the points of sale for hydrochloric acid is exemplified by the hydrochloric acid electrolysis F.
- the hydrochloric acid electrolysis F can be carried out by the diaphragm or hydrochloric acid SVK method according to the prior art.
- the installed electrolysis capacity determines the intake of hydrochloric acid.
- Hydrochloric acid which can not be recycled by means of electrolysis to chlorine 58 and possibly hydrogen 59, must be stored in storage E.
- the resulting from the hydrochloric acid electrolysis chlorine 58 and possibly the hydrogen 59 are completely or partially recycled to the production process A.
- the depleted hydrochloric acid 48 from the hydrochloric acid electrolysis F is fed back to the HCl absorption unit C and reacted, as described above.
- a chemical production process that can be used in the new method, in particular a production process for the chlorination of organic compounds (eg production of vinyl chloride), a process for the production of phosgene and phosgenation, for example for the preparation of isocyanates, particularly preferably of methylene diisocyanate (MDI), toluene diisocyanate (TDI) or a process for the production of polycarbonate (PC), or a process for the combustion of chlorine-containing waste understood.
- MDI methylene diisocyanate
- TDI toluene diisocyanate
- PC polycarbonate
- the new process is applicable in all cases of chemical production in which hydrogen chloride or hydrochloric acid is obtained as a by-product in large industrial quantities.
- a preferred method is therefore characterized in that in the HC! Electrolysis station hydrochloric acid is converted to chlorine, wherein the chlorine is recycled in the chemical production process and chemically reacted there.
- a further take-off point for the hydrochloric acid from the storage E may be the NaCl electrolytes I. (stream 54c) or also the neutralization G (stream 54) or the shipping station H (stream 54b).
- the capacity of large scale chemical production e.g. of an isocyanate more than 50,000 t / a per plant, with plant capacities of up to 400,000 t / 'a at a location are quite common.
- This hydrogen chloride streams are generated, which amount to over 4 t / h. If a chlorine-alkali electrolysis L is present at the site, then a partial stream of the purified hydrochloric acid can be used for acidification of the brine or for sodium hypochlorite decomposition.
- a chlor-alkali electrolysis with a capacity of 400,000 t / a chlorine has a hydrochloric acid requirement of about 0.9 t / h to 1, 4 t / h HCl 100%.
- TDI toluene diisocyanate
- a toluene diisocyanate (TDI) plant with a capacity of 100,000 t / a TI about 231 t / h HCl 100%, so that only about 0.5% of the HCl amount in the chlor-alkali electrolysis for acidification of the electrolyte can be used.
- TDI toluene diisocyanate
- the hydrochloric acid is used in the NaCl electrolysis, it is also recycled there to chlorine and can thus be recycled to the production process A. As a result, the recycling cycles are increasingly closed, which means that the production process A can produce lower emissions.
- alkali chloride in particular sodium chloride, which optionally originates from the neutralization G, and non-neutralized hydrochloric acid for acidification of the alkali chloride solution is converted to chlorine , wherein the chlorine is recycled to the chemical production process A and chemically reacted there.
- the purified hydrochloric acid is supplied for sale via the shipping station H or the NaCl electrolysis 1, or possibly other hydrochloric acid users (not shown) at the site. Further recycling processes are the hydrochloric acid electrolysis F and the Deacon process K. Hydrochloric acid can be taken from the bearing E in order to use it in various applications.
- the hydrochloric acid in a hydrochloric acid electrolysis F z. B .: after the diaphragm process or after the HCl -SV. Process to chlorine and hydrogen or chlorine and water are reacted. If the capacity of the electrolysis F is limited, a part of the purified hydrochloric acid must be supplied from a hydrochloric acid storage to a shipping station H.
- a neutralization station G is supplied in which the hydrochloric acid is reacted with sodium hydroxide solution to form a-preferably saturated-saline solution.
- This saline solution 56 is preferably used again in a chlor-alkali electrolysis I, or must be disposed of as a stream 56a via a disposal station.
- a partial stream or else the total stream of the hydrogen chloride 43 purified in the purification station B can be fed to the catalytic oxidation with oxygen, the HCl gas phase oxidation according to the Deacon process K.
- the chlorine 58a from the HCl gas phase enoxidation K is partially or completely recycled to the chemical production A.
- the hydrochloric acid 49 can be supplied to the hydrochloric acid purification D or directly to the hydrochloric acid storage E and, if required, to the neutralization G and / or the NaCl electrolysis I, and / or HCl electrolysis F and / or to a shipping station H.
- the linkage of the HCl gas phase oxidation K with the further use of different hydrochloric acid utilizations, in particular the hydrochloric acid electrolysis F represents a very efficient variant of the HCl gas phase oxidation K.
- This linkage is particularly efficient, since from the HCl gas phase oxidation resulting hydrochloric acid only with extreme high expenditure HG gas can be won, so that the meaningful utilization of this hydrochloric acid is commanded.
- a multi-stage, in particular a three-stage neutralization process in the neutralization station G is used in the new process.
- a preferred mode of multi-stage neutralization for the new process is described in the following sections. It is a specific object of the invention to provide for the flexible control of the use of large scale chemical acid hydrochloric acid in a continuous neutralization process, on an industrial scale, of variable operating requirements for hydrochloric acid inlet concentration and quantity in a continuous and fully automated sodium hydroxide neutralization process adhering to the target process parameters pH and temperature.
- There is a special task in the regulation of the pH which develops in a logarithmic dependence on the concentration of hydronium ions in the aqueous solution.
- the further special technical task consists in automatically compensating for process-related pressure fluctuations in the process upstream of the neutralization, and for compensating associated mass flow fluctuations within a specific tolerance window.
- the particular object is achieved in that the neutralization of hydrochloric acid is carried out with a volume flow of at least 1 m 3 / h with alkali in at least 3 reaction stages, which include a coarse adjustment, fine adjustment and end setting of the pH and cooled from stage to stage each, include recycled partial streams of the reaction mixture, which absorb the respective reaction heat in these stages.
- a concept consisting of three reaction stages is used, which allows the dosage of the neutralization quantities required taking into account the maximum pH jump of a reaction stage and takes into account the maximum usable concentrations of the reactants.
- the dosing capacity decreases with increasing number of reaction stages.
- the decreasing dosing capacity is reflected in the choice of dosing valves.
- Preferred is a process in which the neutralization G in the form of a multi-stage, in particular a three-stage continuous neutralization of hydrochloric acid with a HC1 concentration of at least 10 wt .-% and with a volume flow of at least 1 m 3 / h, preferably at least 5 m 3 / h, to a target pH in the range of 3 to 9, is carried out with the following steps:
- this secondary circuit 7' resulting from the removal of a portion of current from the main stream to be cooled 7 of the second reaction stage 2, wherein the ratio of the volume flow 7 of the neutralized hydrochloric acid to the flow of the partial flow 7 'is at least 10 to 1 and, after Cooling 8 of the main stream of the second stage, recycling a further larger partial stream 9 of the secondary
- Neutralization stage 3 to a pH in the range of pH 3 to pH 9 by means of addition of alkali 5 'or hydrochloric acid 4' in particular at the metering 11 "and 11 '" in a further secondary circuit 11' which is connected to the neutralization zone 17c, wherein this secondary circuit 11 'consists of a smaller partial stream of the main stream 1 1 leaving the third stage of the reaction mixture 17 c, which is a cooling system
- Reaction mixture 18c in the third stage 3 is to be initiated as a recycle stream 16 for further pH adjustment.
- sodium hydroxide solution is used in the neutralization G as neutralizing agent (alkali lye).
- Sodium hydroxide with a content of NaOCl of less than 100 ppm is preferably used as the neutralizing agent.
- the novel process is preferably carried out in such a way that in the neutralization G the average residence time of the reaction mixture 18a in the first neutralization stage 1 is from 20 s to 3 min.
- the average residence time of the secondary reaction mixture 18b in the second neutralization stage 2 in the neutralization G is in a further preferred embodiment of the process from 15 to 100 min.
- the average residence time of the tertiaryEffsmi research 18 c in the third neutralization stage 3 in the neutralization G is in another preferred embodiment of the new method from 45 to 250 min.
- a particularly preferred variant of the new neutralization process G is characterized in that, independently of one another, the temperature of the primary reaction mixture 18a at the outlet of the first stage 1 is adjusted to a value in the range from 45 ° C to 80 ° C, preferably from 65 ° C to 70 ° C is set, the temperature of the secondary reaction mixture 18b, which is measured directly in the second reaction stage 2, to a value in the range of 40 ° C to 75 ° C, preferably from 60 ° C to 65 ° C and the temperature of the tertiary reaction mixture 18c is set at the outlet of the cooling of the third stage 12 to a value in the range of 15 ° C to 55 ° C, preferably from 25 ° C to 50 ° C.
- the target temperature of the tertiary reaction mixture 18c in the product stream 15 when leaving the plant is particularly preferably a maximum of 30 ° C.
- neutralization G uses a specific arrangement of static mixers and mixing nozzles. In the first reaction stage, both input streams are combined in a static mixer in order to subsequently obtain a homogeneous reaction mixture in a comparatively short time.
- a further particularly preferred embodiment of the neutralization G is therefore characterized in that the mixing of the streams 4, 5, 9 takes place in the first neutralization stage 1 in a static mixer, wherein the static mixer has a mixing quality of at least 98%, preferably 99%.
- the quality characteristic mixing quality is understood to mean the ratio of the volume with homogeneous distribution of sodium hydroxide solution, hydrochloric acid and their reaction product to the total volume.
- the goal of homogeneity is that each sample reflects a composition that corresponds to the population.
- the mixing quality is dependent on the volume flow and the resulting pressure loss at the mixing elements, which produce a cross-mixing due to the turbulence in the mixing tube, and is determined at a distance of 4 x pipe diameter after that mixing element. The distance behind the point of contact of the fluids to be mixed until reaching the mixing grade is called a mixing section.
- the static mixer is followed by a downstream container which, owing to its volume, effects a residence time 17a for reacting the reaction mixture of the first stage 18a. This further enhances the effect of homogenizing the reaction mixture. This is also conducive to be able to perform a reliable pH measurement for the reaction mixture 18a.
- mixing nozzles are provided in particular in order to mix the inflowing mass flows on the one hand and to bring about homogenization within the reaction vessels on the other hand.
- a preferred variant of the neutralization G is characterized in that in the neutralization zone 17b and / or in the neutralization zone 17c in each case a buffer volume in the range of about 25% of the usable holding volume is provided to compensate for variations in the input volume flow.
- the neutralization G is designed so that the mixing of the secondary reaction mixture 18b with the partial flow 4 ', 5', 7 'and the mixing of the tertiary reaction mixture 18c with the partial flow 4', 5 ', 11' independently using Stirring tools 19 in the neutralization zone 17b or 17c or via mixing nozzles 20, the currents in the input region of the supply lines of the part 7 'and 1 1' to the neutralization zone 17b and 17c are provided.
- the metering valves for the metering of caustic soda are especially designed in duplicate in order to be able to carry out the most precise possible metering. Accordingly, there is one coarse metering element per neutralization stage and a small valve for fine adjustment. For the addition of hydrochloric acid, this two-fold version of the dosing is not absolutely necessary, especially if in the first stage, a setpoint is specified and counteracted in the other stages, only an overshoot of the pH and no specific control task is present.
- the neutralization G it is helpful in a preferred embodiment of the neutralization G to ensure a certain residence time for the reaction of sodium hydroxide solution and hydrochloric acid.
- appropriate residence times are provided in the reaction stages. Since the static mixer preferably used in the first stage hardly generates residence times, a dwell time is followed in the static mixer. This allows the reaction mixture to react and increase the validity of the pH measurement after the first stage.
- the same technical need speaks in favor of allowing corresponding residence times in the second and third stages, which, however, in contrast to the first stage, have been realized in particular via integrated reaction vessel volumes. This also has the advantage of a buffer capability of the system in case of disturbances of the process variables of the input currents and thus prevents the direct shutdown of the system when leaving this process window.
- the volumes of the second and third reaction vessels were selected in a preferred embodiment so that a build-up of the pH controls is avoided (resonance catastrophe).
- the entire system for carrying out the neutralization G is designed in particular as a continuous system and is designed for continuous operation without the need for flow interruption due to reaction or set-up times.
- a continuous processing of hydrochloric acid can be guaranteed and load limitations or fluctuations of upstream processes are not to be feared.
- the heat produced in the neutralization reaction is gradually removed in particular by means of cooling water cooler via separate circuits in the second and third reaction stage.
- a partial flow for cooling purposes is also returned before the first stage.
- Umicalzpump s are used which lead in addition to a mixing effect on the one hand within the unit (by rotation of the impeller) and on the other hand by the return to the container.
- these measures ensure that limits in terms of materials are met and that the produced neutralized wastewater is within the specified requirements and can thus be used for further processes.
- the neutralization G alkali lye in particular sodium hydroxide with a content of NaOCl of less than 100 ppm is used so that no formation of free chlorine during the reaction occurs, which in turn would require the use of a reducing agent.
- the concentration of the sodium hydroxide solution is preferably at least 15% by weight, particularly preferably at least 25% by weight, very particularly preferably at least 30% by weight.
- the alkali solution used in the neutralization G preferably sodium hydroxide
- a reducing agent preferably sodium bisulfite added to the aforementioned maximum content of NaOCl set.
- the reducing agent may also be added in the second neutralization stage of the neutralization G to the stream of the alkali metal hydroxide, in particular of the sodium hydroxide solution.
- Fig. 1 is a schematic view of a three-stage neutralization G of hydrochloric acid
- Fig. 2 is a schematic view of details of the first neutralization stage
- Fig. 3 is a schematic view of details of the second neutralization stage
- Fig. 4 is schematic view of details of the third neutralization stage
- Fig. 5 is a schematic view of the overall process for hydrochloric acid management
- Fig. 6 is a schematic view of a particular embodiment for hydrochloric acid management
- Example 1 Description of Multistage Neutralization The composite for hydrochloric acid management at a production site is shown schematically in FIG.
- a HCl falls to gas, which is a station B for gas purification, in particular by distillation, freezing of impurities and cleaning over activated carbon, fed (gas stream 40).
- the purified chloriganho ffo ffgas 42 is a station C for hydrogen chloride absorption, which works by steam stripping fed.
- a portion of the purified hydrogen chloride gas 43 is fed to a catalytic gas-phase oxidation catalytic converter K in which hydrogen chloride is reacted with oxygen in the presence of catalysts containing ruthenium compounds at elevated temperature to form chlorine 58a and water or hydrochloric acid 49, respectively.
- the chlorine gas 58a is recycled to production A for conversion.
- an HCl gas stream 41 may also be fed directly to the hydrogen chloride absorption station C.
- Hydrochloric acid 44 from the HCl -Ab sorption C and optionally excess hydrochloric acid 49 from the HCl gas phase oxidation K are fed to a station D for the purification of hydrochloric acid, which removes further impurities, for example by means of activated carbon.
- the purified hydrochloric acid is forwarded to a hydrochloric acid tank E as a hydrochloric acid storage.
- hydrochloric acid 4 is either supplied from the hydrochloric acid tank E or directly from the station D to the neutralization station G for the purification of hydrochloric acid (not shown) and neutralized there by means of concentrated sodium hydroxide solution 55.
- the resulting saline solution 56 can preferably be supplied to a plant 1, for the electrolysis of sodium chloride or in a stream 56a of a disposal station M.
- a plant 1 for the electrolysis of sodium chloride or in a stream 56a of a disposal station M.
- part of the hydrochloric acid 54c from the storage E can be used to acidify the sodium chloride solution.
- the chlorine 57 formed in the electrolysis L is supplied for reuse in the chemical production A.
- Another delivery station for the hydrochloric acid 54b is the shipping station H, in which the loading of the hydrochloric acid optionally on trucks (stream 43), rail tank cars (stream 44) or on ships (stream 45) takes place.
- a hydrochloric acid electrolysis station F is provided here, in which a portion of the purified hydrochloric acid 54a from the hydrochloric acid storage E to chlorine gas 58, optionally hydrogen 59 and depleted hydrochloric acid 48 is reacted.
- the chlorine gas 58 is, if necessary, recycled to the chemical production A, which utilizes hydrogen 59 thermally or otherwise, and the depleted hydrochloric acid 48 is supplied to the HCl absorption C.
- the neutralization station G is then put into operation when the capacity of the hydrochloric acid storage E exhausted, the other recycling options hydrochloric acid electrolysis F, sodium chloride electrolysis L and the sale or shipping H for various reasons are not possible.
- the neutralization system is ready for operation (Fig. 1). There are for the used 32% sodium hydroxide solution at the measuring point P2 an operating pressure of 6.3 bar / 0.63 MPa and for neutralizing 31% hydrochloric acid at the measuring point P 1 an operating pressure of 5.4 baru / 0.54 MPa on.
- a nominal value for the hydrochloric acid stream to be neutralized in the process control system is specified by the operator.
- a hydrochloric acid inlet stream 4 having a volume flow of 30.0 m 3 / h is introduced into the recycle stream of cooled second stage reaction mixture 9.
- a ratio control Fl and F2 and via the pH control of the first stage PH! is added via the control valve pair of sodium hydroxide inlet of the first neutralization stage K4 a quantity of 28.5 m 3 / h of the stream of 9 and 4.
- the total volume flow of 179 m 3 / h was then achieved in a static mixer 20, which is the mixing element of the first neutralization stage 1. After passing through an intensive homogenization takes place after the static mixer, the measurement of the temperature Tl for controlling the cooling water flow rate for the cooling of the first and second stage 8.
- the primary reaction mixture 18a passes into a residence time and neutralization zone 17a, which was realized by means of a flow-through container and was provided for further reaction of that reaction mixture to subsequently guarantee a reliable pH measurement PH 1 for controlling the amount of sodium hydroxide solution 5 supplied.
- a pH of 1, 6 sets.
- the still acidic brine passes into the operated at ambient pressure, second stage of the neutralization 2.
- Their residence time is ensured by a pressureless, high set reaction vessel (not shown) by a free overflow in normal operation, a level of 58, 3%, which corresponds to about 30 m 3 .
- the mixing nozzles 21 By installing the mixing nozzles 21, the resulting turbulence in the reaction stage 2 is used for mixing. In addition, the mixing nozzles 21 suck an approximately four times the current from the surrounding tank volume those reaction mixture 18b with. Two small mixing nozzles are aligned tangential to the ground and a large jet mixer acts obliquely upwards centrally and thus ensures thorough mixing in the volume. This mixing principle is used analogously in the third neutralization stage 3. From this stage, a main stream 7 of the reaction mixture 18 b is removed and the cooling 8 is supplied. Here, a large part of the heat of neutralization of the first and second stages is transferred to the cooling water. The cooling water of the cooling 8 heats up from 14.7 ° C to 24.5 ° C.
- the main part of the thus pre-cooled brine outlet is run before the first stage of neutralization 1 in the form of the recycle stream 9 in the amount of 120 mVh.
- a smaller partial flow 7 'of this brine operates in a secondary circuit, the mixing nozzles 21.
- In this stream are after specification of the pH control PH 2 120.0 1 / h of lye at the metering 7 "and 0.7 1 / h of acid the metering 7 "'dosed.
- the feedback of the metering K5 is again through a flow meter F5.
- the reaction mixture 18b passes in the form of the stream 10 from the second stage 2 via an overflow into the third stage of the neutralization 3, which realizes a significantly higher residence time due to the 3-fold capacity.
- This volume ratio of the volume of the second to the volume of the third stage was carried out in order to avoid a build-up of regulations and an associated resonance catastrophe.
- a main stream 1 1 of the reaction mixture 18c is also removed and the cooling 12 is supplied.
- the heat of neutralization of the third stage is transferred to the cooling water.
- the cooling water of the cooling 12 heats up from 14.7 ° C to 29 ° C.
- the reaction mixture 18c cools from 36.5 ° C to 29 ° C.
- this pH measurement was carried out in triplicate (redundant).
- the reaction mixture 18c is discharged via a level control LI adhering to the release criteria pH value (measurement PH3 and PH4) and temperature (measurement T3) in the process step 14.
- the delivery is interrupted and the flow rate 13 in the form of the current 16 back to the third neutralization stage 3 promoted. It can thus temporarily buffered brine in the second and third reaction stage (2 and 3) in the first step.
- the liquor for the first stage 1 is metered from the network via two parallel valves K4, which have a staggered valve size (kvs value).
- the fine valve is directly controlled and has a 10 times lower maximum flow rate than the coarser valve.
- the latter is controlled more slowly by the manipulated variable of the small valve, so that there is no resonance between the valves.
- the coarser valve is slightly opened. As a result, the smaller can close something again. This abutment of the larger valve occurs so often until the required target pH is reached. Similarly, the coarser valve closes gradually when the fine valve threatens to close.
- a fast and accurate control of the liquor stream can be achieved.
- This basic principle described here using the example of the first stage is analogously also implemented in the second stage 2 at the sodium hydroxide metering K5 and third stage 3 at the sodium hydroxide metering K6.
- the second and third stages primarily try to regulate the prescribed pH values. While the bandwidth for the third stage is dictated by the output limits, the first and second stages may be dictated according to the performance of the controls. Since the expected metered streams of sodium hydroxide in the third stage are very small, the metering takes place via a valve and in parallel via a positive displacement pump. Due to the high accuracy requirements by the desired pH levels of the stages to the dosage, overshoot is possible.
- the comprehensive process concept described here is based on a control concept, which is characterized by the measurement of many process variables such as input flow rates, inlet pressures and temperature, level and pH per reaction stage and further monitoring thedewas sertemp eratur allows on the one hand fully automated operation of the system via an intelligent process control and, on the other hand, a certain variance of the process parameters of the input media (concentration, pressure and quantity) to which the overall system automatically adjusts itself. In normal operation, a direct intervention of the operator after starting the system is not required. Thus, for each stage, a control circuit is used for the pH value which determines the quantities of neutralizing agent required and adjusts them to the metering valves. Accordingly, a constant pH value is targeted per stage, which approaches the target pH value as the number of reaction stages increases.
- the integrated concept for load control allows neutralization systems to be operated under efficient load and significantly simplifies operation of the system.
- the load control automatically reduces the load to keep the critical process size below its limits.
- the neutralization system is automatically operated under maximum load while maintaining the specified limit values for the process parameters of the product solution and optimum utilization of the system capacity with maximum turnover.
- the fact that the critical process variables are in the uncritical range indicates to the plant operator that the nominal value of the load can be increased by intervention of the plant operator.
- an automatic load change is made by the process control system to keep the differing process size below its threshold.
- the automatic load change takes place via control loops intended for the respective process variable (eg PID, MPC).
- superimposed master control loops are provided for the load specification and the process variables, which have the objective of the respective process variable with the load as manipulated variable to its setpoint.
- the manipulated variables of the higher-level master control loops are respectively setpoints for the subordinate control loop (slave), which intervenes in the process via an actuator (eg valve Kl), so that the prevailing pressure conditions and the given valve characteristics require the current required by the slave controller established.
- Another control technology optimization of the process control is the automatic cooling water control.
- the process temperatures of the first and second and third neutralization stage are measured and when exceeding the target values, the cooling water flow is automatically increased by means of actuators in the form of control valves.
- the temperature measurement of the third neutralization stage (T2) by means of direct control acts on a control valve of the cooling device of the third stage (12).
- the system reacts to load changes or tempera ture fluctuations and avoids direct intervention of the automatic load reduction when a process variable is exceeded (see previous paragraph).
- the pH regulations of the individual stages have been implemented in the form of a feed-forward rule (see LIPTAK, Heia G .: Instrument Engineers Handbook, 4th edition, 2005, pp. 2044 ff.) Not only does it use the local volume and local pH, but it also takes into account each precursor solution flowing in.
- the supplied volume flows are included and the supply pressures, which were identified as major disturbances, are taken into account
- this calculation is done from the previously metered volume flows and the pH at the outlet of the second stage, so that yes the
- the neutralization unit is designed in accordance with the safety requirements of the chemicals in use. In the process, compatible materials were used and appropriate safety concepts for large deviations from process variables were provided. In addition, it is a closed system in which emerging sour exhaust air streams are given purposefully in an existing exhaust air treatment plant.
- the concentration of the resulting NaCl-containing solutions is 20-25 wt .-%
- the resulting NaCl-containing stream 15 from the neutralization G can be fed to a chlorine-alkali electrolysis L or a disposal station M.
- the following example describes the hydrochloric acid management in a production process (A) for the production of isocyanates with a capacity of 100,000 t / h of toluene diisocyanate (TDI), which is operated with a load of 11.5 T / h TDI and thereby 9.353 t / HCl gas is generated as a by-product.
- A hydrochloric acid management in a production process for the production of isocyanates with a capacity of 100,000 t / h of toluene diisocyanate (TDI), which is operated with a load of 11.5 T / h TDI and thereby 9.353 t / HCl gas is generated as a by-product.
- TDI toluene diisocyanate
- hydrochloric acid electrolysis F in the form of a hydrochloric acid diaphragm electrolysis plant F with a capacity of 3 t / h HCl (100%), a shipping station H for filling railway tank cars and trucks 43.
- a sodium chloride Electrolysis L connected, which has a capacity of 300,000 t / h of chlorine and can thus 0.829 t / h of hydrochloric acid calculated as 1 00% HCl record.
- a neutralization unit G which can process a hydrochloric acid amount of 10 t / h calculated as 100%> HCl.
- Hydrogen chloride 41 which is obtained in the isocyanate production A is fed to a HCl gas absorption C in normal operation.
- the depleted hydrochloric acid 48 from the hydrochloric acid electrolysis F with an amount of 20.36 t / h and a concentration of 20 wt.% I and 15.04 t / h of water 61 is supplied as the absorption medium.
- Impurities are removed from the absorption unit C with water and chlorine.
- 0.4 t / h of a loaded with organ ik 30% hydrochloric acid 60 are removed and disposed of.
- an amount of 44.353 t / h of a 30% hydrochloric acid 44 is removed from the HCl absorption unit C.
- the hydrochloric acid 44 is fed to a cleaning station D. In the cleaning station D, the hydrochloric acid 44 is again treated with activated carbon to remove residues of impurities.
- the purified hydrochloric acid is fed to a hydrochloric acid storage E. 23.27 t / h of the 30% hydrochloric acid 54a are removed from the storage E and fed to an HCl diaphragm electrolysis F.
- 2.91 t / H of chlorine 58 is produced from the hydrochloric acid supplied and the depleted hydrochloric acid 48, 20.36 t / h, with a concentration of 20 wt.%>
- the HCl absorption C is supplied.
- hydrochloric acid storage E From hydrochloric acid storage E, the chlor-alkali electrolysis I located at the site is supplied with 2.769 t / h hydrochloric acid 54c to acidify the brine. Furthermore, 18.314 t / h of 30% hydrochloric acid 54b are put up for sale. For this purpose tankers 43 are filled.
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Environmental & Geological Engineering (AREA)
- Water Supply & Treatment (AREA)
- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Hydrology & Water Resources (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)
Abstract
Description
Claims
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
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EP17152417.6A EP3351505A1 (de) | 2017-01-20 | 2017-01-20 | Verfahren zur flexiblen steuerung der verwendung von salzsäure aus chemischer produktion |
PCT/EP2018/051088 WO2018134239A1 (de) | 2017-01-20 | 2018-01-17 | Verfahren zur flexiblen steuerung der verwendung von salzsäure aus chemischer produktion |
Publications (1)
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EP3571157A1 true EP3571157A1 (de) | 2019-11-27 |
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EP17152417.6A Withdrawn EP3351505A1 (de) | 2017-01-20 | 2017-01-20 | Verfahren zur flexiblen steuerung der verwendung von salzsäure aus chemischer produktion |
EP18700374.4A Pending EP3571157A1 (de) | 2017-01-20 | 2018-01-17 | Verfahren zur flexiblen steuerung der verwendung von salzsäure aus chemischer produktion |
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EP17152417.6A Withdrawn EP3351505A1 (de) | 2017-01-20 | 2017-01-20 | Verfahren zur flexiblen steuerung der verwendung von salzsäure aus chemischer produktion |
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Country | Link |
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US (1) | US11040878B2 (de) |
EP (2) | EP3351505A1 (de) |
JP (1) | JP2020506859A (de) |
KR (1) | KR20190105590A (de) |
CN (1) | CN110198914A (de) |
WO (1) | WO2018134239A1 (de) |
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CN109399567B (zh) * | 2018-12-28 | 2021-08-13 | 甘肃金川恒信高分子科技有限公司 | 一种自动补偿氯化氢发生器 |
Family Cites Families (28)
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AT234639B (de) * | 1961-10-14 | 1964-07-10 | Siegener Ag Eisenkonstruktion | Verfahren zur Gewinnung von gasförmigem Chlor und gasförmigem Wasserstoff |
JPS5311238B2 (de) * | 1972-09-14 | 1978-04-20 | ||
US4247532A (en) * | 1979-08-13 | 1981-01-27 | Shell Oil Company | Purification of electrolytically-produced chlorine |
DE3714439A1 (de) * | 1987-04-30 | 1988-11-10 | Bayer Ag | Verfahren zur herstellung von (cyclo)aliphatischen diisocyanaten |
EP0371201A1 (de) * | 1988-12-01 | 1990-06-06 | Ruhrkohle Aktiengesellschaft | Verfahren zur Hydrierung von Organochlorverbindungen und Neutralisation des anfallenden Chlorwasserstoffs sowie Neutralisationsmittel für aus Organochlorverbindungen anfallenden Clorwasserstoff |
FI85007C (fi) * | 1990-10-24 | 1992-02-25 | Nokia Ab Chemicals Oy | Foerfarande foer framstaellning av saltsyra. |
US5616234A (en) * | 1995-10-31 | 1997-04-01 | Pepcon Systems, Inc. | Method for producing chlorine or hypochlorite product |
IT1282367B1 (it) * | 1996-01-19 | 1998-03-20 | De Nora Spa | Migliorato metodo per l'elettrolisi di soluzioni acquose di acido cloridrico |
JPH1081986A (ja) * | 1996-09-03 | 1998-03-31 | Permelec Electrode Ltd | 水平型複極式電解槽 |
US6719957B2 (en) | 2002-04-17 | 2004-04-13 | Bayer Corporation | Process for purification of anhydrous hydrogen chloride gas |
US20040152929A1 (en) * | 2002-05-08 | 2004-08-05 | Clarke William D | Process for vinyl chloride manufacture from ethane and ethylene with air feed and alternative hcl processing methods |
DE102005032663A1 (de) | 2005-07-13 | 2007-01-18 | Bayer Materialscience Ag | Verfahren zur Herstellung von Isocyanaten |
DE102006023581A1 (de) * | 2006-05-19 | 2007-11-22 | Bayer Materialscience Ag | Verfahren zur Abtrennung von Chlor aus dem Produktgas eines HCI-Oxidationsprozesses |
DE102006024516A1 (de) * | 2006-05-23 | 2007-11-29 | Bayer Materialscience Ag | Verfahren zur Herstellung von Chlor aus Chlorwasserstoff und Sauerstoff |
ES2427593T3 (es) | 2007-01-08 | 2013-10-31 | Basf Se | Procedimiento para la obtención de difenilmetanodiamina |
CA2682402C (en) * | 2007-04-12 | 2015-07-14 | Cefco, Llc | Process and apparatus for carbon capture and elimination of multi-pollutants in flue gas from hydrocarbon fuel sources and recovery of multiple by-products |
TWI478875B (zh) * | 2008-01-31 | 2015-04-01 | Solvay | 使水性組成物中之有機物質降解之方法 |
US20090232861A1 (en) * | 2008-02-19 | 2009-09-17 | Wright Allen B | Extraction and sequestration of carbon dioxide |
DE102008012037A1 (de) * | 2008-03-01 | 2009-09-03 | Bayer Materialscience Ag | Verfahren zur Herstellung von Methylen-diphenyl-diisocyanaten |
DE102008015901A1 (de) * | 2008-03-27 | 2009-10-01 | Bayer Technology Services Gmbh | Elektrolysezelle zur Chlorwasserstoffelektrolyse |
JP5484689B2 (ja) * | 2008-04-25 | 2014-05-07 | 三菱重工業株式会社 | 排ガス処理システム及び排ガス中の水銀除去方法 |
JP5391577B2 (ja) * | 2008-05-14 | 2014-01-15 | Jfeスチール株式会社 | 廃塩酸液から塩酸を回収する塩酸回収装置および塩酸回収方法 |
US20110091366A1 (en) * | 2008-12-24 | 2011-04-21 | Treavor Kendall | Neutralization of acid and production of carbonate-containing compositions |
SG174714A1 (en) | 2010-03-30 | 2011-10-28 | Bayer Materialscience Ag | Process for preparing diaryl carbonates and polycarbonates |
CN102602892B (zh) * | 2012-04-11 | 2015-04-01 | 万华化学集团股份有限公司 | 通过氯化氢的催化氧化制备氯气的方法 |
WO2014039929A1 (en) * | 2012-09-07 | 2014-03-13 | Clean Chemistry, Llc | Systems and methods for generation of reactive oxygen species and applications thereof |
CN104512865B (zh) * | 2013-09-26 | 2016-08-17 | 宝山钢铁股份有限公司 | 除硅中和反应的中和药剂氨水添加量的控制方法 |
US10934627B2 (en) * | 2016-05-06 | 2021-03-02 | Malvi Technologies, Llc | Methods and systems for making hypochlorite solution from reverse osmosis brine |
-
2017
- 2017-01-20 EP EP17152417.6A patent/EP3351505A1/de not_active Withdrawn
-
2018
- 2018-01-17 CN CN201880007462.2A patent/CN110198914A/zh active Pending
- 2018-01-17 JP JP2019538621A patent/JP2020506859A/ja active Pending
- 2018-01-17 WO PCT/EP2018/051088 patent/WO2018134239A1/de unknown
- 2018-01-17 US US16/479,083 patent/US11040878B2/en active Active
- 2018-01-17 KR KR1020197020805A patent/KR20190105590A/ko not_active Application Discontinuation
- 2018-01-17 EP EP18700374.4A patent/EP3571157A1/de active Pending
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KR20190105590A (ko) | 2019-09-17 |
WO2018134239A1 (de) | 2018-07-26 |
EP3351505A1 (de) | 2018-07-25 |
US20190375635A1 (en) | 2019-12-12 |
CN110198914A (zh) | 2019-09-03 |
JP2020506859A (ja) | 2020-03-05 |
US11040878B2 (en) | 2021-06-22 |
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