Process for working up an alkanolamine, ammonia or amine and water containing stream

Abstract

The invention relates to a process for working up an alkanolamine, water, and ammonia or amine containing stream (5), comprising distilling off ammonia or amine from the alkanolamine, water, and ammonia or amine containing stream (5) in a first distillation stage (7), distilling off residual ammonia or amine from the stream (9) depleted in ammonia or amine in a second distillation stage (13), optionally distilling off water from the crude alkanolamine containing product stream (15) in a third distillation stage (19), and working up the crude alkanolamine containing product stream (15; 23) in a fourth distillation stage (25), wherein at least one of the gas streams obtained in the distillation stages (7, 13, 19, 25) is used as a heat source in a heat pump (31, 41, 61, 71) for generating steam.

Description

Process for working up an alkanolamine, ammonia or amine and water containing streamDescriptionThe invention relates to a process for working up an alkanolamine, water, and ammonia or amine containing stream, comprising:(a) distilling off ammonia or amine from the alkanolamine, water, and ammonia or amine containing stream in a first distillation stage, thereby obtaining a stream depleted in ammonia or amine and a stream containing ammonia or amine;(b) distilling off residual ammonia or amine from the stream depleted in ammonia or amine in a second distillation stage, thereby obtaining a crude alkanolamine containing product stream and a water and ammonia or amine containing stream;(c) optionally distilling off water from the crude alkanolamine containing product stream in a third distillation stage;(d) working up the crude alkanolamine containing product stream in a fourth distillation stage, thereby obtaining a purified alkanolamine containing product stream.Alkanolamines are a group of compounds being used across a wide range of applications, for example in carbon dioxide capture, as catalyst in the production of polyurethanes, in paints and coatings, as fabric softeners, in water treatment and paper manufacturing. The large-scale production of alkanolamines generally is carried out in an alkoxylation by reaction of an amine or ammonia with an alkylene oxide.Such alkoxylation reactions for producing alkanolamines are well known to the skilled person. WO-A 2012 / 080409 describes for example a process for producing N,N-dialkyl-ethanolamine.Batchwise production of alkanolamines is described for example in M. Ernst et aL, “Ethanolamines and Propanolamines”, in Ullmann’s Encyclopedia of Industrial Chemistry, 2022, DOI: 10.1002 / 14356007. a10_001.pub2. In the batchwise production, a reaction kettle is filled with amine and water, which is used as catalyst. The mixture of water and amine is heated to reaction temperature and subsequently ethylene oxide is added. The reaction temperature is maintained for a specific time until the ethylene oxide has been completely converted. Subsequently, the reaction mixture obtained is separated by a fractional distillation. Unconverted amine and water are recycled into the subsequent batch and pure alkanolamines are obtained by distillation under reduced pressure.A process for producing methylethanolamine is described in CN-U 214553403. For this purpose, monomethylamine and ethylene oxide are fed into a reactor in which a mixture of N-methylmonoehtanolamine and N-methyldiethanolamine is obtained. In a distillation tower, unreacted monomethylamine is separated from the reaction mixture and returned into the reactor. The remaining mixture is fed into a second distillation column in which N-methyl-monoethanol- amine is withdrawn at the top. The bottom product of the second distillation column is fed into a third distillation column in which N-methyldiethanolamine is separated off.In distillation processes, the head streams of the distillation columns are cooled and condensed and at least partly recycled into the distillation column to set the temperature at the head of the distillation column. Presently, the heat released from the head stream is transferred to a cooling medium and is wasted.Therefore, it was an object of the present invention to provide a process for working up an alkanolamine, water, and ammonia or amine containing stream with an improved energy balance.This object is achieved by a process for working up an alkanolamine, water, and ammonia or amine containing stream, comprising:(a) distilling off ammonia or amine from the alkanolamine, water, and ammonia or amine containing stream in a first distillation stage, thereby obtaining a stream depleted in ammonia or amine and a stream containing ammonia or amine;(b) distilling off residual ammonia or amine from the stream depleted in ammonia or amine in a second distillation stage, thereby obtaining a crude alkanolamine containing product stream and a water and ammonia or amine containing stream;(c) optionally distilling off water from the crude alkanolamine containing product stream in a third distillation stage;(d) working up the crude alkanolamine containing product stream in a fourth distillation stage, thereby obtaining a purified alkanolamine containing product stream, comprising at least one of; the water and ammonia or amine containing stream is used as a heat source in a first heat pump for generating steam; the stream containing ammonia or amine obtained in step (a) is used as a heat source in a second heat pump for generating steam; the purified alkanolamine containing product stream is used as a heat source in a third heat pump; andthe water distilled off in the third distillation stage is used as a heat source in a fourth heat pump.By using at least one of the streams as a heat source in a heat pump for generating steam, the energy of the respective stream can be used and is not wasted. The steam can be used for example as a heating medium in any process known to a skilled person, for example for heating a reactor or for providing heat in a distillation process. The steam produced in any of the heat pumps may be used directly for example in any process step of the process for working up the alkanolamine, water and ammonia or amine containing stream, in a process for producing the alkanolamine, water and ammonia or amine containing stream or in any other process known to a skilled person that needs steam. Alternatively or additionally, the steam or at least a part of the steam may be fed into a steam grid and supplied to a process that needs steam.The steam generated in any of the heat pumps may have any pressure. Depending on the pressure of the steam produced in the heat pump, it is possible to further compress the steam to obtain low pressure steam, medium pressure steam or high pressure steam. Further, it is possible to divide the steam produced in the heat pump into separate streams which can be compressed to different pressures. This allows for example to produce medium pressure steam and high pressure steam, low pressure steam and medium pressure steam, low pressure steam and high pressure steam or even low pressure steam, medium pressure steam and high pressure steam.Besides producing low pressure steam, medium pressure steam or high pressure steam, it is also possible to use the steam produced in the heat pump without any further compression. This is for example suitable, if the steam directly is used in a specific process, for example for heating a stream or an apparatus.In the context of the present invention, the term “low pressure steam” means steam having a pressure in a range from 0.9 to 4 bar(abs), more preferred in a range from 1 to 2 bar(abs) and particularly in a range from 1 .2 to 1 .5 bar(abs) and a temperature in a range from 96 to 160 °C, more preferred in a range from 99 to 140 °C and particularly in a range from 104 to 120 °C.The term “medium pressure steam” means steam having a pressure in a range from 4 to8 bar(abs), more preferred in a range from 4.5 to 7 bar(abs) and particularly in a range from 5 to 6 bar(abs) and a temperature in a range from 143 to 220 °C, more preferred in a range from 147 to 210 °C and particularly in a range from 151 to 200 °C.The term “high pressure steam” means steam having a pressure in a range from 8 to40 bar(abs), more preferred in a range from 10 to 30 bar(abs) and particularly in a range from 16 to 20 bar(abs) and a temperature in a range from 170 to 280 °C, more preferred in a range from 180 to 260 °C and particularly in a range from 201 to 240 °C.The heat pumps used for producing steam may be any type of heat pump, for example open loop heat pumps or closed loop heat pumps. A heat pump is any apparatus in which a processstream is evaporated and optionally heated. Subsequently the process stream compressed in a pump or compressor to a higher pressure and temperature level.In a closed loop heat pump, a working medium is used that is evaporated by heat transfer from the cooling medium, which simultaneously is cooled. After being evaporated, the working medium is compressed. By compression, the temperature of the working medium increases. Subsequently, the working medium passes a second heat exchanger, in which heat is transferred to water, which is at least partly evaporated. After being cooled by heat transfer to heat and at least partly evaporate the water, the working medium is expanded and thereby further cooled.In an open loop heat pump, water is at least partly evaporated by heat transfer from the cooling medium in a heat exchanger and the at least partly evaporated water is compressed and heated further in at least one compressor to obtain the process steam. Particularly if the cooling medium has a temperature above 70 °C, it is preferred to use an open loop heat pump for producing process steam.The alkanolamine, water, and ammonia or amine containing stream may be obtained for example as a crude reaction stream in a reactor for producing alkanolamine by reaction of an alkylene oxide with ammonia or amine.A reaction for producing an alkanolamine may comprise for example mixing a first feed stream comprising water and an amine or ammonia and a second feed stream comprising an alkylene oxide to obtain a reaction mixture, feeding the reaction mixture into a reactor in which the alkanolamine is formed by reaction of the alkylene oxide and the amine or ammonia, thereby obtaining a crude reaction product and working up the crude reaction product.According to the present invention, the term “alkanolamine” means a compound of formula (I):whereinR1 is selected from substituted or unsubstituted Ci- to Cs-alkylene,R2 and R3 are independently selected from H, Ci- to Cs-alkyl and Ci- to Cs-hydroxyalkylFor producing alkanolamines, water and an amine or ammonia are mixed to form a first feed stream. The first feed stream is preheated to a temperature in a range from 50 to 140 °C, preferably in a range from 90 to 120 °C and mixed with a second feed stream comprising an alkylene oxide to obtain a reaction mixture. The reaction mixture preferably has a temperature in a range from 140°C to 200°C, more preferred in a range from 150 to 180°C and a pressure in a range from 70 to 100 bar(abs), more preferred in a range from 80 to 95 bar (abs).For preheating the first feed stream, any suitable heat exchanger may be used. Preferably, the first feed stream is preheated in a shell-and-tube heat exchanger. The heating medium used for preheating the first feed stream may be any heating medium having a temperature above the temperature to which the first feed stream is heated. Preferably, the heating medium is steam, particularly low pressure steam.The amounts of the first feed stream and the second feed stream are selected such that the amine or ammonia is in excess, preferably in a 1 .1 to 20-fold molar excess, more preferred in a 1 .5 to 10-fold molar excess, and particularly in a 3 to 8-fold molar excess, based on the alkylene oxide. The excess of amine or ammonia ensures a complete conversion of the alkylene oxide and minimizes formation of by-products by, e.g., multiple alkylene oxide addition.If an amine is used, the amine may be a compound of formula (II)HNR1R2(II) whereinR1is selected from H, Ci- to Cs-alkyl, and Ci- to Cs-hydroalkyl, and R2is selected from Ci- to Cs-alkyl, and Ci- to Cs-hydroalkyl.Preferably,R1is selected from H, Ci- to C4-alkyl, and Ci- to C4-hydroalkyl, and R2is selected from Ci- to C4-alkyl, and Ci- to C4-hydroalkyl.For example, the amine may be selected from methylamine and dimethylamine.Particularly preferably, ammonia is used.The alkylene oxide may be selected from ethylene oxide and propylene oxide, particularly ethylene oxide.Preferably, the alkanolamine obtained in the reaction may be for example at least one of monoethanolamine (obtained by reaction of ammonia and ethylene oxide), diethanolamine (obtained by reaction of ammonia and ethylene oxide), triethanolamine (obtained by reaction of ammonia and ethylene oxide), monomethylethanolamine (obtained by reaction of methylamine and ethylene oxide), dimethylethanolamine (obtained by reaction of dimethylamine and ethylene oxide), methyldiethanolamine (obtained by reaction of monomethylethanolamine and ethylene oxide), diethylethanolamine (obtained by reaction of diethylamine and ethylene oxide), monoisopropanolamine (obtained by reaction of ammonia and propylene oxide), diisopropanolamine (obtained by reaction of ammonia and propylene oxide), and triisopropanolamine (obtained by reaction of ammonia and propylene oxide).This reaction mixture is fed into a reactor, in which the alkanolamine is formed by reaction of the alkylene oxide and the amine or ammonia, thereby obtaining a crude reaction product. The reaction preferably is carried out continuously in a tube reactor. For providing sufficient reaction time, it is preferred that the tube reactor has a length in a range from 300 m to 2.2 km depending on the alkanolamine to be produced. If the alkanolamine is ethanolamine, the reactor length preferably is in a rangel .6 to 2.2 km, particularly in a range from 1 .7 to 2.0 km and if the alkanolamine is alkylethanolamine, the reactor length preferably is in a range from 300 to 600 m, particularly in a range from 400 to 500 m. Due to the length of the tube reactor, the reactor generally comprises a plurality of passes, the passes generally have a length in a range from 30 to 100 m, wherein the length may depend on the space provided at the location of the reactor. For a compact design of the reactor, the passes may be arranged one above the other. In each pass the tube further may run meandering. The reaction pressure preferably is in a range from 10 to 40 bar(abs), particularly in a range from 15 to 30 bar(abs) and the reaction temperature in a range from 110 to 170 °C, more preferred in a range from 125 to 160 °C.As the crude reaction product still contains ammonia or amine and further may contain undesired by-products, the crude reaction product is further worked-up for separating the alkanolamine from the non-reacted reactants, particularly the ammonia and amine, the water and the undesired by-products.According to the invention, working-up the crude reaction product is carried out in in at least three distillation stages.In a first distillation stage, excess amine or excess ammonia and some of the water are separated off, thereby obtaining a stream depleted in ammonia or amine and a stream containing ammonia or amine. The first distillation stage preferably is carried out in a first distillation column at a pressure below the reaction pressure, preferably in a range from 3 to 25 bar(abs). The bottom temperature in the first distillation column preferably is in a range from 120 to 220 °C and the head temperature of the first distillation column preferably is in a range from 90 to 150 °C.The specific operation conditions of the first distillation column depend on the alkanolamine produced in the process.If the alkanolamine is ethanolamine, particularly monoethanolamine, the pressure in the first distillation column preferably is in a range 5 to 25 bar(abs), particularly in a range from 17 to 22 bar(abs), the bottom temperature preferably is in a range from 150 to 220 °C, particularly in a range from 170 to 220 °C and the head temperature preferably is in a range from 90 to 130 °C, particularly in a range from 100 to 120 °C.If the alkanolamine is methyldiethanolamine, the pressure in the first distillation column preferably is in a range 3 to 6 bar(abs), particularly in a range from 4 to 5 bar(abs), the bottom temperature preferably is in a range from 140 to 180 °C, particularly in a range from 150 to 170 °C andthe head temperature preferably is in a range from 110 to 150 °C, particularly in a range from 120 to 140 °C.If the alkanolamine is diemethylethanolamine, the pressure in the first distillation column preferably is in a range 3 to 6 bar(abs), particularly in a range from 4 to 5 bar(abs), the bottom temperature preferably is in a range from 120 to 160 °C, particularly in a range from 130 to 150 °C and the head temperature preferably is in a range from 100 to 130 °C, particularly in a range from 110 to 120 °C.The first distillation column may be any distillation column known to the skilled person. Usually, the first distillation column has 10 to 40 theoretical plates, preferably 15 to 30 theoretical plates and contains internals, for example packings or trays.The ammonia or amine and the water separated off in the first distillation preferably may be recycled into the reaction and mixed with fresh ammonia or amine and water to form the first feed stream.The stream depleted in ammonia or amine generally still contains ammonia or amine. For this purpose, residual ammonia or amine is distilled off from the stream depleted in ammonia or amine in a second distillation stage, thereby obtaining a crude alkanolamine containing product stream and a water and ammonia or amine containing stream.The second distillation stage preferably is carried out in a second distillation column at a pressure below the pressure in the first distillation column, preferably in a range from 50 mbar(abs) to 8 bar(abs). The bottom temperature in the second distillation column preferably is in a range from 150 to 200 °C and the head temperature of the second distillation column preferably is in a range from 70 to 170°C.The specific operation conditions of the second distillation column depend on the alkanolamine produced in the process.If the alkanolamine is ethanolamine, particularly monoethanolamine, the pressure in the second distillation column preferably is in a range 3 to 8 bar(abs), particularly in a range from 4 to 6 bar(abs), the bottom temperature preferably is in a range from 150 to 200 °C, particularly in a range from 160 to 190 °C and the head temperature preferably is in a range from 130 to 170 °C, particularly in a range from 140 to 160 °C.If the alkanolamine is methyldiethanolamine, the pressure in the second distillation column preferably is in a range 50 to 700 mbar(abs), particularly in a range from 100 to 600 mbar(abs), the bottom temperature preferably is in a range from 150 to 200 °C, particularly in a range from 160 to 190 °C and the head temperature preferably is in a range from 70 to 120 °C, particularly in a range from 80 to 100 °C.If the alkanolamine is dimethylethanolamine, the pressure in the second distillation column preferably is in a 50 to 700 mbar(abs), particularly in a range from 100 to 600 mbar(abs), the bottom temperature preferably is in a range from 150 to 200 °C, particularly in a range from 160 to 190 °C and the head temperature preferably is in a range from 70 to 120 °C, particularly in a range from 80 to 100 °C.The second distillation column may be any distillation column known to the skilled person. Usually, the second distillation column has 10 to 50 theoretical plates and contains internals, for example packings or trays.The remaining water may be distilled off in a third distillation stage. If the water is essentially completely distilled off in the second distillation stage, the third distillation stage can be omitted. Independent of the alkanolamine, the third distillation stage preferably is carried out in a third distillation column at a pressure in a range from 700 mbar(abs) to 1500 mbar(abs), particularly 800 to 1200 mbar(abs). The bottom temperature in the third distillation column preferably is in a range from 150 to 200 °C, particularly in a range from 160 to 190 °C and the head temperature of the third distillation column preferably is in a range from 90 to 120 °C, particularly in a range from 95 to 110 °C.The third distillation column may be any distillation column known to the skilled person. Usually, the third distillation column has 10 to 40 theoretical plates and contains internals, for example packings or trays.To obtain a pure alkanolamine, the crude alkanolamine containing product stream is worked up in a fourth distillation stage, thereby obtaining a purified alkanolamine containing product stream.The fourth distillation stage preferably is carried out in a fourth distillation column at a pressure below the pressure in the third distillation column, preferably in a range from 50 to 300 mbar(abs). The bottom temperature in the fourth distillation column preferably is in a range from 70 to 200 °C and the head temperature of the fourth distillation column preferably is in a range from 40 to 170 °C.The specific operation conditions of the fourth distillation column depend on the alkanolamine produced in the process.If the alkanolamine is ethanolamine, particularly monoethanolamine, the pressure in the fourth distillation column preferably is in a range 50 to 300 mbar(abs), particularly in a range from 80 to 150 mbar(abs), the bottom temperature preferably is in a range from 150 to 200 °C, particularly in a range from 170 to 190 °C and the head temperature preferably is in a range from 120 to 170 °C, particularly in a range from 140 to 160 °C.If the alkanolamine is methyldiethanolamine, the pressure in the fourth distillation column preferably is in a range 50 to 200 mbar(abs), particularly in a range from 80 to 120 mbar(abs), the bottom temperature preferably is in a range from 150 to 190 °C, particularly in a range from 160 to 180 °C and the head temperature preferably is in a range from 60 to 120 °C, particularly in a range from 80 to 100 °C.If the alkanolamine is diemethylethanolamine, the pressure in the fourth distillation column preferably is in a range 150 to 250 mbar(abs), particularly in a range from 180 to 220 mbar(abs), the bottom temperature preferably is in a range from 70 to 130 °C, particularly in a range from 85 to 110 °C and the head temperature preferably is in a range from 40 to 100 °C, particularly in a range from 50 to70 °C.The fourth distillation column may be any distillation column known to the skilled person. Usually, the fourth distillation column has 10 to 50 theoretical plates and contains internals, for example packings or trays.The distillation columns may be heated by steam, depending on the bottom temperature for example by using low pressure steam, medium pressure steam or high pressure steam. Preferably, the distillation columns are heated by using medium pressure steam.Before being fed into the first distillation stage, a part of the ammonia or amine contained in the crude reaction product may be removed. For this purpose, for example, a flash evaporator may be arranged upstream the first distillation stage and an ammonia or amine containing vapor stream and an alkanolamine containing liquid stream are obtained in the flash evaporator by partial evaporation of at least a part of a crude reaction product obtained in the reactor for producing alkanolamine.For evaporating at least a part of the ammonia or amine by flash evaporation, any flash evaporator, known to the skilled person may be used. Generally the flash evaporator is a tank having a pressure below the pressure of the crude reaction product. To avoid entrainment of droplets into the gas stream, a suitable liquid separator, for example a packing may be provided in the flash evaporator. The pressure in the flash evaporator is selected such that the boiling point of the ammonia or amine at the pressure in the flash evaporator is below the temperature of the crude reaction stream. Preferably, the pressure in the flash evaporator is in a range from 12 to 20 bar(abs) and depends on the alkanolamine produced in the reactor.If the alkanolamine, for example, is ethanolamine, preferably monoethanolamine, the pressure in the flash evaporator preferably is in a range from 5 to 25 bar(abs), particularly in a range from 15 to 20 bar(abs).If the crude reaction product is partly evaporated in the flash evaporator to remove a part of the ammonia or amine, it is preferred that at least a part of the alkanolamine containing liquid stream is the alkanolamine, water, and ammonia or amine containing stream, which is fed intothe first distillation stage. Particularly, the complete alkanolamine containing liquid stream obtained in the flash evaporator is the alkanolamine, water, and ammonia or amine containing stream, which is fed into the first distillation stage.As an alternative, it is further possible to carry out the first distillation stage for removing ammonia or amine by flash evaporation. In this case, the first distillation column described above, is replaced by the flash evaporator.To reduce the waste energy, according to the invention, the heat of at least one gas stream ob- tainined in one of the distillation stages is used as a heat source in a heat pump for producing steam.Each of the heat pumps used in the process may be a closed loop heat pump or an open loop heat pump.In a closed loop heat pump, a heat transfer medium is heated and evaporated by heat exchange from a heat source in a first heat exchanger, the evaporated heat transfer medium then is compressed in a compressor, by which the temperature of the heat transfer medium further increases. In a second heat exchanger, a water stream is heated and particularly evaporated by heat transfer from the heat transfer medium. Due to the heat transfer in the second heat exchanger, the heat transfer medium is cooled and may partly condense. In an expansion device, for example a throttle device, the heat transfer medium is expanded and thereby further cooled and condensed. The heat transfer medium then is recycled into the first heat exchanger. The steam obtained in the second heat exchanger is compressed to a specified pressure.In an open loop heat pump, a water stream is evaporated in a heat exchanger by heat transfer from a heat source. Subsequently the thus obtained steam is compressed to a specified pressure. Besides evaporating the water in the heat exchanger, it is alternatively possible to heat the water in the heat exchanger or to only partly evaporate the water. If the water is heated and remains liquid, it is fed into a flash apparatus. On entry in the flash apparatus, a part of the water evaporates due to a pressure reduction. The obtained steam is withdrawn from the flash apparatus and compressed and the liquid part of the water is mixed with fresh water and recycled into the heat exchanger. If only a part of the water stream is evaporated in the heat exchanger, the partly evaporated stream may either be fed into the flash apparatus to further evaporate some of the water or the partly evaporated stream is fed into a phase separator in which the liquid phase is separated from the gas phase. The steam containing gas phase is compressed in at least one compressor and the liquid phase is recycled into the heat exchanger after being mixed with fresh water.In a first and preferred embodiment of the invention, the water and ammonia or amine containing stream obtained in the second distillation stage (b) is used as a heat source in a first heat pump for generating steam.Preferably, the first heat pump is an open loop heat pump and comprises a heat exchanger in which water is evaporated by heat transfer from the water and ammonia or amine containing stream to generate steam and the steam subsequentlny is compressed in at least one compressor.For producing steam, the water fed into the first heat pump preferably has a temperature in a range from 10 to 110 °C and a pressure in a range from 1 to 8 bar(abs), more preferred a temperature in a range from 30 to 90 °C and a pressure in a range from 1 ,2 to 6 bar(abs), and particularly a temperature in a range from 40 to 60 °C and a pressure in a range from 1 ,5 to 4 bar(abs).In the heat exchanger of the first heat pump, the water is at least partly evaporated, thereby obtaining saturated steam. If the water is evaporated completely, it may be possible that the steam is superheated in the heat exchanger. However, generally, the water does not completely evaporate so that the water leaving the heat exchanger comprises a liquid phase and saturated steam. The at least partly evaporated water then is fed into at least one compressor to generate superheated stream.In a second embodiment, the stream containing ammonia or amine obtained in step (a) is used as a heat source in a second heat pump for generating steam. Due to the low pressure of the stream containing ammonia or amine, it is preferred that the second heat pump is a closed loop heat pump.Therefore, the second heat pump preferably comprises a closed loop and generating steam comprises:(i) heating and evaporating a heat transfer medium by heat transfer from the stream depleted in ammonia or amine in a first heat exchanger,(ii) compressing the heat transfer medium,(iii) generating steam by evaporating water by heat transfer from the heat transfer medium in a second heat exchanger, thereby condensing the heat transfer medium,(iv) expanding the heat transfer medium,(v) returning the heat transfer medium into step (i), and(vi) compressing the steam obtained in step (iii) in at least one compressor.The heat transfer medium used in the closed loop may be any suitable heat transfer medium for a heat pump with a closed loop. Suitable heat transfer media for example are water, glycol-wa- ter mixtures or heat transmission liquids like ethyleneoxide, cyclobutene, 1 -butyne, cis-butene, trans-butene, 1 ,3-butadiene, 1 -butene, propyne, butane, isobutene, dimethylether, cyclopropane, ammonia, propandiene, neopentane, isobutane, R441A, R1233ZDE, R1234ZEZ, R1224YDZ, R40, R436B, R510A, R435A, R429A, R436A, RE235CB2, R152A and R440A. Preferably, the cooling medium is ammonia, water or a glycol-water mixture, particularly ammonia or water.In the closed loop, the heat transfer medium absorbs heat from the stream depleted in ammonia or amine in the first heat exchanger. By the heat absorption, the heat transfer medium evaporates. The evaporated heat transfer medium then is compressed in at least one compressor. By compression, the pressure and the temperature of the heat transfer medium increases. In the second heat exchanger, heat is transferred from the heat transfer medium to water. Thereby, the heat transfer medium is cooled and the water preferably at least partly evaporates. After passing the second heat exchanger, the heat transfer medium is expanded and returned into the first heat exchanger.The at least partly evaporated water leaving the second heat exchanger is compressed in at least one compressor to generate process steam.The water fed into the second heat exchanger preferably has a temperature in a range from 10 to 110 °C and a pressure in a range from 1 to 8 bar(abs), more preferred a temperature in a range from 30 to 90 °C and a pressure in a range from 1 ,2 to 6 bar(abs), and particularly a temperature in a range from 40 to 60 °C and a pressure in a range from 1 ,5 to 4 bar(abs).If the crude reaction stream is partly evaporated in the flash evaporator to remove a part of the ammonia or amine, it is preferred that the ammonia or amine containing vapor stream and the stream containing ammonia or amine obtained in step (a) are mixed and then fed into the second heat pump. Alternatively, it is also possible that only the ammonia or amine containing vapor stream or, alternatively, only the stream containing ammonia or amine obtained in step (a) is fed into the second heat pump.In a third embodiment, the purified alkanolamine containing product stream is used as a heat source in a third heat pump. The third heat pump preferably is an open loop heat pump and comprises a heat exchanger in which water is evaporated by heat transfer from the purified alkanolamine containing product stream to generate steam and the steam subsequently is compressed in at least one compressor.For producing steam, the water fed into the third heat pump preferably has a temperature in a range from 10 to 110 °C and a pressure in a range from 1 to 8 bar(abs), more preferred a temperature in a range from 30 to 90 °C and a pressure in a range from 1 ,2 to 6 bar(abs), and particularly a temperature in a range from 40 to 60 °C and a pressure in a range from 1 ,5 to 4 bar(abs).In the heat exchanger of the third heat pump, the water is at least partly evaporated, thereby obtaining saturated steam. If the water is evaporated completely, it may be possible that the steam is superheated in the heat exchanger. However, generally, the water does not completely evaporate so that the water leaving the heat exchanger comprises a liquid phase and saturated steam. The at least partly evaporated water then is fed into at least one compressor to generate superheated stream.In a fourth embodiment, the water distilled off in the third distillation stage is used as a heat source in a fourth heat pump. Preferably, the fourth heat pump is an open loop heat pump.Besides providing only one of the heat pumps as described above, it is further possible to provide two heat pumps, three heat pumps or all four heat pumps. Particularly preferably, the process comprises all four heat pumps. If not all four heat pumps are comprised, it is preferred to provide the heat pumps that are connected to the streams having the highest temperatures or to the streams by which the largest amounts of steam can be generated in the heat pump. For this reason, it is preferred to provide at least the first heat pump or the first and the second and / or third heat pump, if less heat pumps than all four are to be provided.The following applies to each of the heat pumps, i.e. the first heat pump, the second heat pump, the third heat pump and the fourth heat pump, if provided in the process.Depending on the pressure of the water supplied to the heat pump for generating steam and on the required pressure of the steam, it may be necessary to compress the steam after evaporation of the water.If the at least partly evaporated water obtained in the heat pump has a pressure below the pressure of medium pressure steam, the at least partly evaporated water may be mixed with high pressure steam to obtain medium pressure steam. As an alternative, it is also possible to compress the at least partly evaporated water for obtaining medium pressure steam. Further, depending on the amount of high pressure steam that can be used for being mixed with the at least partly evaporated water or the capacity of compressors used for compressing the partly evaporated water, it is also possible to mix a part of the at least partly evaporated water with high pressure steam and to compress the other part of the at least partly evaporated water. The medium pressure steam obtained in both processes can be mixed to obtain only one steam stream.Compression of the at least partly evaporated water may be carried out in only one compressor or a compressor cascade, comprising at least two compressors. Independently of using only one compressor or a compressor cascade, it is possible that each compressor comprises only one compressor stage or more than one compressor stage. Particularly if only one compressor is used, it is preferred to use a compressor having at least two compressor stages.If the at least partly evaporated water is compressed to obtain the medium pressure steam, it is further possible to inject water after at least one compressor stage or after at least one compressor. If water is injected, it is preferred to inject water after each compressor stage or at least each compressor, respectively. By injecting water, the required specifications of the medium pressure steam can be set.If the pressure of the at least partly evaporated water is below the pressure of low pressure steam, it is preferred to compress the at least partly evaporated water to obtain low pressure steam.If it is possible to evaporate the water in the heat exchanger completely, it is possible to use the steam obtained by evaporation as process steam. In this case, the water fed into the heat exchanger of the heat pump preferably has a pressure that corresponds to the pressure of low pressure steam.The steam produced in any of the heat pumps and the optional subsequent compression can be used in any process, which uses steam having the pressure of the steam generated in the heat pump. The steam may be used for example in the process for working up the alkanolamine, water, and ammonia or amine containing stream, a process for producing alkanolamine or in any other process which preferably is carried out on the industrial site, the process for producing alkanolamine and the subsequent process for working up the alkanolamine, water, and ammonia or amine containing stream is carried out. Besides using the steam directly in a process, preferably a process on the same industrial site, the steam may be fed into a steam grid.The present invention further relates to a target product that can be obtained or achieved by a method according to the present invention.The publication Prior Art Disclosure; Issue 684; paragraphs

[1000] to

[8005] ; ISSN: 2198-4786; published: February 12, 2024 will be regarded as Reference RF1 , which is incorporated herein by reference in its entirety. Preferably, the target product is a product as described in Reference RF1 ; paragraphs

[1000] to

[8005] ,Preferably, the process described herein is further a process for the production of a product, preferably a target product. The converting step to obtain the target product preferably comprises one or more step(s) as described below and can be performed by conventional methods well known to a person skilled in the art. The converting step preferably comprises one or more step(s) selected from: recycling, preferably depolymerizing, gasifying, pyrolyzing, and / or steam cracking; and / or purifying, preferably crystallizing, (solvent) extracting, distilling, evaporating, hydrotreating, absorbing, adsorbing and / or subjecting to ion exchanger; and / or assembling, preferably foaming, synthesizing, chemical conversion, chemically transforming, polymerizing and / or compounding; and / or forming, preferably foaming, extruding and / or molding; and / or finishing, preferably coating and / or smoothing. In addition, the one or more step(s) are described in detail in Reference RF1 ; paragraphs

[1000] to

[8005] ,The term “building block”, as used herein, comprises compounds, which are in a gaseous or liquid state under standard conditions of 0°C and 0.1 MPa. Building blocks are typically used in chemical industry to form secondary products, which provide a higher structural complexity and / or higher molecular weight than the building block on which the secondary product is based. The building block is preferably selected from the group consisting of hydrogen, carbonmonoxide, carbon dioxide, ethylene oxide, ethylene glycols, syngas comprising a mixture of hydrogen and carbon monoxide, alkanes, alkenes, alkynes and aromatic compounds. The alkanes, alkenes, alkynes and aromatic compounds comprise in particular 1 to 12 carbon atoms, respectively.The term “monomer”, as used herein, comprises molecules, which can react with each other to form polymer chains by polymerization. The monomer is preferably selected from the group consisting of (meth)acrylic acid, salts of (meth)acrylic acid; in particular sodium, potassium and zinc salts; (meth)acrolein and (meth)acrylates. (Meth)acrylates comprising 1 to 22 carbon atoms are preferred, in particular comprising 1 to 8 carbon atoms.The terms (meth)acrylic acid, (meth)acrolein or (meth)acrylate relate to acrylic acid, acrolein or acrylate and also to methacrylic acid, methacrolein or methacrylate, where applicable. Further, the monomer can be selected from hexamethylenediamine (HMD) and adipic acid. The building block can further be an intermediate compound.The term “intermediate compound”, as used herein, comprises organic reagents, which are applied for formation of compounds with higher molecular complexity. The intermediate compound can be selected for example from the group consisting of phosgene, polyisocyanates and propylene oxide. The polyisocyanates are in particular aromatic di- and polyisocyanates, preferably toluene diisocyanate (TDI) and / or diphenylmethane diisocyanate (MDI). The building block and the monomer and typical converting step(s) to obtain the building block or monomer are described in more detail in paragraphs

[1000] to

[1012] of Reference RF1 .The term “polymer A”, as used herein, comprises thermoplastic, e.g., polyamide or thermoplastic polyurethane, thermoset, e.g., polyurethane, elastomer, e.g., polybutadiene, or a copolymer or a mixture thereof and is defined in more detail in paragraphs

[2001] to

[2007] of Reference RF1.The term “polymer composition A”, as used herein, comprises all compositions comprising a polymer as described above and one or more additive(s), e.g. reinforcement, colorant, modifier and / or flame retardant, and is defined in more detail in paragraph

[2008] of Reference RF1.The term “polymer product A”, as used herein, comprises any product comprising the polymer A and / or polymer composition A as described above and is defined in more detail in paragraphs

[2009] and

[2010] of Reference RF1 . The step(s) to obtain the polymer, preferably polymer A, polymer composition, preferably polymer composition A or polymer product, preferably polymer product A is / are described in more detail in paragraph

[2011] of Reference RF1.The term “industrial use polymer”, as used herein, comprises rheological polymers, polycarboxylate, alkoxylated polyalkylenamine, alkoxylated polyalkylenimine, polyether-based, dye inhibition polymers and soil release cleaning polymers defined in more detail in paragraphs

[3035] to

[3044] of Reference RF1 .The term “industrial use surfactant”, as used herein, comprises non-ionic, anionic and amphoteric industrial use surfactants defined in more detail in paragraphs

[3008] to

[3034] of Reference RF1.The term “industrial use descaling compound”, as used herein, comprises nonphosphate based builders (NPB) and phosphonates (CoP) described in more detail in paragraphs

[3001] to

[3005] of Reference RF1.The term “industrial use biocide”, as used herein, refers to a chemical compound that kills microorganisms or inhibits their growth or reproduction defined in more detail in paragraphs

[3006] to

[3007] of Reference RF1 .The term “industrial use solvent”, as used herein, comprises alkyl amides, alkyllactamides, alkyl esters, lactate esters, alkyl diester, cyclic alkyl diester, cyclic carbonates, aromatic aldehydes and aromatic esters defined in more detail in paragraphs

[3045] to

[3055] of Reference RF1.The term “industrial use dispersant”, as used herein, comprises anionic and non-ionic industrial use dispersants defined in more detail in paragraphs

[3056] to

[3058] of Reference RF1.The term “composition and / or formulation thereof’ with reference to the industrial use polymers, industrial use surfactants, descaling compounds and / or industrial use biocides refers to industrial use compositions and / or institutional use products and / or fabric and home care products and / or personal care products defined in more detail in paragraph

[3059] of Reference RF1. The converting step(s) to obtain the industrial use polymer, industrial use surfactant, descaling compound and / or industrial use biocide are defined in more detail in paragraph

[3060] of Reference RF1. The converting steps to obtain the industrial use composition or formulation of the industrial use polymer, industrial use surfactant, descaling compound and / or industrial use biocide are defined in more detail in paragraph

[3061] of Reference RF1.The term “agrochemical composition”, as used herein, typically relates to a composition comprising an agrochemically active ingredient and at least one agrochemical formulation auxiliary. Examples of agrochemical compositions, active ingredients and auxiliaries are described in more detail in Reference RF1 , paragraph

[4001] , The agrochemical composition may take the form of any customary formulation. The agrochemical compositions are prepared in a known manner, e.g. described by Mollet and Grubemann, Formulation technology, Wiley VCH, Weinheim, 2001 ; or Knowles, New developments in crop protection product formulation, Agrow Reports DS243, T&F Informa, London, 2005. The converting step(s) to obtain the agrochemically active ingredients and auxiliaries may be conducted in analogy to the production step(s) of their analogues that are based on petrochemicals or other precursors that are not gained by recycling processes. In addition, conversion to compounds mentioned in sections “Polymer” and “Cosmetic surfactant, emollient, wax, cosmetic polymer, UV filter, further cosmetic ingredient orcompositions or formulations thereof’ may be performed as described in these sections as well as the respective paragraphs in Reference RF1.The term active pharmaceutical ingredients and / or intermediates thereof, as used herein, comprises substances that provide pharmacological activity or other direct effect in the diagnosis, cure, mitigation, treatment, or prevention of disease, or to affect the structure or any function of the body. Intermediates thereof are isolated products that are generated during a multi-step route of synthesis of an active pharmaceutical ingredient.The term pharmaceutical excipients, as used herein, comprises compounds or compound mixtures used in compositions for various pharmaceutical applications, which are not substantially pharmaceutically active on itself. Active pharmaceutical ingredients and / or intermediates thereof and pharmaceutical excipients are defined in more detail in paragraph

[5001] of Reference RF1. The converting step(s) to obtain the active pharmaceutical ingredients and / or intermediates thereof and pharmaceutical excipients may comprise one or more synthesis steps and can be performed by conventional synthesis and techniques well known to a person skilled in the art.The terms animal feed additives, human food additives, dietary supplements, as used herein, comprises Vitamins, Pro-Vitamins and active metabolites thereof including intermediates and precursors, especially Vitamin A, B, E, D, K and esters thereof, like acetate, propionate, palmitate esters or alcohols thereof like retinol or salts thereof and any combinations thereof; Tetraterpenes, especially isoprenoids like carotenoids and xanthophylls including their intermediates and precursors as well as mixtures and derivates thereof, especially beta carotene, Canthaxan- thin, Citranaxanthin, Astaxanthin, Zeaxanthin, Lutein, Lycopene, Apo-carotenoids, and any combinations thereof; organic acids, especially formic acid, propionic acid and salts thereof, such as sodium, calcium or ammonium salts, and any combinations thereof, such as but not limited to mixtures of formic acid and sodium formiate, propionic acid and ammonium propionate, formic acid and propionic acid, formic acid and sodium formiate and propionic acid, propionic acid and sodium propionate and formic acid and sodium formiate; glycerides of carboxylic acids and short and medium chain fatty acids, conjugated linoleic acids, such as omega-6 fatty acid (C18:2) methyl ester and 1 ,2-propandiol and beverage stabilizers, such as polyvinylpyrroli- done-polymer or polyvinylimidazole / polyvinylpyrrolidone-copolymer. Animal feed additives, human food additives and dietary supplements are defined in more detail in paragraph

[5002] of Reference RF1 . The converting step(s) to obtain the animal feed additives, human food additives, dietary supplements may comprise one or more synthesis steps and can be performed by conventional synthesis and techniques well known to a person skilled in the art.The terms aroma chemical and aroma composition as used herein, comprise a volatile organic substance with a molecular weight between 70-250 g / mol comprising a functional group with a carbon skeleton of C5-C16 carbon atoms comprising linear, branched, cyclic, for example with a ring size of C5-C18, bicyclic or tricyclic aliphatic chains and but not necessarily one or more unsaturated structural elements like double bonds, triple bonds, aromatics or heteroaromatics and preferably the one or more additional functional groups are selected from alcohol, ether, ester,ketone, aldehyde, acetal, carboxylic acid, nitrile, thiol, amine. In one aspect, the aroma chemical is a terpene-based aroma chemical, for example selected from monoterpenes and monoterpenoids, sesquiterpenes and sesquiterpenoids, diterpenes, triterpenes or tetraterpenes. Aroma chemicals can be combined with further aroma chemicals to give an aroma composition. Aroma chemicals and aroma compositions are defined in more detail in paragraph

[5003] of Reference RF1 . The converting step(s) to obtain the aroma chemical and aroma composition may comprise one or more synthesis steps and can be performed by conventional synthesis and techniques well known to a person skilled in the art.The term “aqueous polymer dispersion”, as used herein, comprises aqueous composition(s) comprising dispersed polymer(s) and is defined in more detail in the section

[6001] entitled “aqueous polymer dispersion” of Reference RF1 . The dispersed polymer(s) may be selected from acrylic emulsion polymer(s), styrene acrylic emulsion polymer(s), styrene butadiene dispersions), aqueous dispersion(s) comprising composite particles, acrylate alkyd hybrid dispersions), polyurethane(s) (including UV-curable polyurethanes) and polyurethane - poly(meth)acrylate hybrid polymer(s).The term “emulsion polymer”, as used herein, comprises polymer(s) made by free-radical emulsion polymerization. Aqueous polyurethane dispersion(s) are defined in more detail in the section

[6002] entitled “Polyurethane dispersions” of Reference RF1. UV-curable polyurethane(s) is / are defined in more detail in the section

[6017] of Reference RF1. Polyurethane - poly(meth)acrylate hybrid polymer(s) is / are defined in more detail in the section

[6016] of Reference RF1.The term “polymeric dispersant”, as used herein, comprises preferably polymer(s) comprising polyether side chain, in particular polycarboxylate ether polymer(s) and polycondensation produces) defined in more detail in paragraph

[6020] entitled “Polymeric dispersant” of Reference RF1 . The converting (polymerization) step(s) to obtain the aqueous polymer dispersion(s) comprising emulsion polymer(s) is / are defined in more detail in the section

[6003] entitled “Emulsion polymerization” of Reference RF1. The converting (polymerization) step(s) to obtain the aqueous polyurethane dispersion(s) is / are defined in more detail in the section

[6014] entitled “Process for the preparation of aqueous polyurethane dispersions” and section

[6017] entitled “Aqueous UV-curable polyurethane dispersions, their preparation and use and compositions containing them” of Reference RF1 . Composition(s) and uses of aqueous polymer dispersion(s) and of polymeric dispersant(s) are defined in more detail in the following sections of Reference RF1 : section

[6004] entitled “Uses of aqueous polymer dispersions”, section

[6005] entitled “Binders for architectural and construction coatings” section

[6006] entitled “Binders for paper coating” section

[6007] entitled “Binders for fiber bonding” section

[6008] entitled “Adhesive polymers and adhesive compositions” section

[6015] entitled “Aqueous polyurethane dispersions suitable for use in coating compositions” section

[6016] entitled “Aqueous polyurethane - poly(meth)acrylate hybrid polymer dispersions suitable for use in coating compositions” section

[6017] entitled “Aqueous UV-curable polyurethane dispersions, their preparation and use and compositions containing them section

[6018] entitled “Inorganic binder compositions comprisingpolymeric dispersants and their use”

[6019] 100% curable coating compositions UV-crosslinka- ble poly(meth)acrylate(s) and its / their uses are defined in more detail in section

[6009] entitled “UV-crosslinkable poly(meth)acrylates for use in UV-curable solvent-free hotmelt adhesives and their use for making pressure-sensitive self-adhesive articles” of Reference RF1 . Polyisocya- nate(s), composition(s) comprising them and their uses are defined in more detail in section

[6010] entitled “Polyisocyanates” of Reference RF1. Hyperbranched polyester polyol(s) and its / their uses are defined in more detail in section

[6011] entitled “Organic solvent based hyperbranched polyester polyols suitable for use in coating compositions” of Reference RF1. The converting step(s) to obtain the hyperbranched polyester polyols is / are defined in more detail in the section

[6012] entitled “Preparation of organic solvent based hyperbranched polyester polyols” of Reference RF1. Coating composition(s) comprising hyperbranched polyester polyol(s), polyisocyanate(s) and additive(s) and substrate(s) coated therewith are defined in more detail in section

[6013] entitled “Organic solvent based two component coating compositions comprising hyperbranched polyester polyols and polyisocyanates” of Reference RF1. Unsaturated polyester polyol(s), solvent-based coating composition(s) comprising said unsaturated polyester polyols) and substrate(s) for coating with said coating composition(s) are defined in more detail in section

[6018] entitled “Organic solvent based coating composition comprising unsaturated polyester polyols” of Reference RF1. 100% curable coating composition(s) is / are defined in more detail in section

[6019] of Reference RF1 . Polymeric dispersant(s) for inorganic binder compositions is / are defined in more detail in section

[6020] of Reference RF1 . The inorganic binder composition(s) comprising the polymeric dispersants and their use are defined in more detail in section

[6021] of Reference RF1 . The converting step(s) to obtain the polymeric dispersant(s) are defined in more detail in section

[6020] of Reference RF1.The term “inorganic binder composition” comprising the polymeric dispersant(s), as used herein, comprises preferably in particular hydraulically setting compositions and compositions comprising calcium sulfate and is defined in more detail in section

[6021] of Reference RF1 entitled “Inorganic binder compositions comprising the polymeric dispersant and their use”. Specific building material formulation(s) comprising polymeric dispersant(s) or building product(s) produced by a building material formulation comprising a polymeric dispersant are disclosed in more detail in section

[6021] of Reference RF1.The term “cosmetic surfactant”, as used herein, comprises non-ionic, anionic, cationic, and amphoteric surfactants and is defined in more detail in paragraph

[7002] of Reference RF1.The term “emollient”, as used herein, refers to a chemical compound used for protecting, moisturizing, and / or lubricating the skin and is defined in more detail in paragraph

[7003] of Reference RF1.The term “wax”, as used herein, comprises pearlizers and opacifiers and is defined in more detail in paragraph

[7004] of Reference RF1.The term “cosmetic polymer”, as used herein, comprises any polymer that can be used as an ingredient in a cosmetic formulation and is defined in more detail in paragraph

[7005] of Reference RF1.The term “UV filter”, as used herein, refers to a chemical compound that blocks or absorbs ultraviolet light and is defined in more detail in paragraph

[7006] of Reference RF1.The term “further cosmetic ingredient”, as used herein, comprises any ingredient suitable for making a cosmetic formulation. Several sources disclose cosmetically acceptable ingredients. E. g. the database Cosing on the internet pages of the European Commission discloses cosmetic ingredients and the International Cosmetic Ingredient Dictionary and Handbook, edited by the Personal Care Products Council (PCPC), discloses cosmetic ingredients.The term “composition and / or formulation thereof’ with reference to the cosmetic surfactant, emollient, wax, cosmetic polymer, UV filter and / or further cosmetic ingredient refers to personal care and / or cosmetic compositions or formulations defined in more detail in paragraph

[7007] of Reference RF1. The converting step(s) to obtain the cosmetic surfactant, emollient, wax, cosmetic polymer, UV filter or further cosmetic ingredient is / are defined in more detail in paragraph

[7008] of Reference RF1 .The terms “polymer B”, “polymer composition B”, “coating composition”, “other functional composition”, “foil”, “molded body”, “coating” and “coated substrate” are well known to the person skilled in the art and are defined in more detail from paragraph

[8000] to

[8005] of Reference RF1.In a preferred embodiment, the target product is selected from: i) building block or monomer; or ii) polymer, preferably polymer A, polymer composition, preferably polymer composition A, or polymer product, preferably polymer product A; or iii) cleaning polymer, cleaning surfactant, descaling compound, cleaning biocide or composition or formulation thereof; or iv) agrochemical composition, agrochemical formulation auxiliary or agrochemically active ingredient; or v) active pharmaceutical ingredient or intermediate thereof, pharmaceutical excipient, animal feed additive, human food additive, dietary supplements, aroma chemical or aroma composition; or vi) aqueous polymer dispersion, preferably polyurethane or polyurethane - poly(meth)acrylate hybrid polymer dispersion, emulsion, binder for paper and fiber coatings, UV-curable acrylic polymer for hot melts and coatings polyisocyanates, hyper branched polyester polyol, polymeric dispersant for inorganic binder compositions, unsaturated polyester polyol or 100% curable composition; or vii) cosmetic surfactant, emollient, wax, cosmetic polymer, UV filter, further cosmetic ingredient or composition or formulation thereof; orviii) polymer B, polymer composition B, coating composition, other functional composition, foil, molded body, coating or coated substrate.In a preferred embodiment, the content of the alkanolamine in the target product is 1 weight-% or more, preferably 2 weight-% or more, more preferably 5 weight-% or more, more preferably 15 weight-% or more, more preferably 30 weight-% or more, more preferably 40 weight-% or more, more preferably 60 weight-% or more, more preferably 80 weight-% or more, more preferably 90 weight-% or more, more preferably 95 weight-% or more; and / or the content of the alkanolamine in target product is 100 weight-% or less, preferably 95 weight- % or less, more preferably 90 weight-% or less, more preferably 50 weight-% or less, more preferably 25 weight-% or less, more preferably 10 weight-% or less; and preferably the content is determined based on identity preservation and / or segregation and / or mass balance and / or book and claim chain of custody models, preferably based on mass balance, preferably the International Sustainability and Carbon Certification (ISCC) standard.In a preferred embodiment, preferably according to the above-mentioned embodiments of the process, the method comprises the step of converting the product of the process, namely alkanolamine, which can be achieved or obtained by one of the above-mentioned embodiments, to obtain the target product.An embodiment of the invention is shown in the figure and explained in more detail in the following description.The only figure shows a flow chart of a process for producing an alkanolamine.For producing an alkanolamine, a water and amine or ammonia containing first feed stream is preheated to a temperature in a range from 50 to 140 °C and is mixed with a second feed stream comprising an alkylene oxide to obtain a reaction mixture 1 . The reaction mixture 1 is preheated to a temperature in a range from 90 to 180 °C and preferably has a pressure in a range from 20 to 100 bar(abs), depending on the alkanolamine to be produced. After preheating, the reaction mixture 1 is fed into a reactor 3. In the reactor, an alkanolamine is formed by reaction of the amine or the ammonia and the alkylene oxide. For a complete conversion of the alkylene oxide, the amine or ammonia usually are fed into the reactor in a 1 .1 to 20-fold molar excess, based on the alkylene oxide. By the excess of amine ore ammonia, a complete conversion of the alkylene oxide is ensured and the formation of by-products is minimized.The reactor preferably is a tube reactor having a length in a range from 300 m to 2.2 km depending on the alkanolamine to be produced.By reaction an alkanolamine, water and ammonia or amine containing stream 5 is obtained. The alkanolamine, water, and ammonia or amine containing stream 5 is fed into a first distillation stage 7, which preferably is carried out in a first distillation column. The first distillation column preferably is operated at a pressure in a range from 3 to 25 bar(abs), a bottom temperature in arange from 120 to 220 °C and a head temperature in a range from 90 to 150 °C. In the first distillation stage 7, ammonia or amine is distilled off from the alkanolamine, water, and ammonia or amine containing stream 5, thereby obtaining a stream 9 depleted in ammonia or amine and a stream 11 containing ammonia or amine. Generally the stream 11 containing ammonia or amine also contains water.The stream 11 containing ammonia or amine is cooled and then preferably recycled into the reactor 3. For recycling the stream 11 containing ammonia or amine, it is possible to directly feed the stream 11 into the reactor 3, or, preferably, to feed the stream 11 containing ammonia or amine into the reaction mixture 1 before entering the reactor 3.The stream 9 depleted in ammonia or amine is fed into a second distillation stage 13, which preferably is carried out in a second distillation column. In the second distillation stage, residual ammonia or amine separated from the stream 9 depleted in ammonia or amine, thereby obtaining a crude alkanolamine containing product stream 15 and a water and ammonia or amine containing stream 17. The second distillation column preferably is operated at a pressure in a range from 3 to 8 bar(abs), a bottom temperature in a range from 150 to 200 °C and a head temperature in a range from 130 to 170 °C.After cooling the water and ammonia or amine containing stream 17 preferably is recycled into the reactor 3. For this purpose, the water ammonia or amine containing stream 17 may be fed directly into the reactor 3 or may be mixed with the stream 11 containing ammonia or amine before being fed into the reactor 3.To remove remaining water, the crude alkanolamine containing product stream 15 may be fed optionally into a third distillation stage 19. In the third distillation stage, water 21 is removed from the crude alkanolamine containing product stream 15 and a further purified crude alkanolamine containing product stream 23 is obtained. Generally, the third distillation stage 19 is carried out in a third distillation column which is operated at a pressure in a range from 50 mbar(abs) to 1500 mbar(abs), a bottom temperature in a range from 150 to 190 °C and a head temperature in a range from 70 to 120 °C.The water preferably is mixed into the water and ammonia or amine containing stream 17 and then recycled into the reactor 3 together with the water and ammonia or amine containing stream 17.The further purified crude alkanolamine containing product stream 23 is fed into a fourth distillation stage 25, in which high boilers 27 are removed. By removing the high boilers 27, a purified alkanolamine containing product stream 29 is obtained.To use the heat of at least one of the streams withdrawn at the top of the distillation stages 7, 13, 19, 25, the respective stream is used as a heat source in a heat pump.As the water and ammonia or amine containing stream 17 has the highest temperature, at least this stream is used as a heat source in a first heat pump 31.The first heat pump 31 may be an open loop heat pump or a closed loop heat pump. Preferably, the first heat pump 31 is an open loop heat pump as shown here. The first heat pump 31 comprises a heat exchanger 33, in which heat is transferred from the water and ammonia or amine containing stream 17 to a water stream 35. By heat transfer, the water stream 25 is evaporated in the first heat exchanger. The thus obtained steam 37 is compressed in at least one compressor 39 to obtain low pressure steam, medium pressure steam or high pressure steam, depending on the steam demand.For using the heat of the stream 11 containing ammonia or amine, this stream is used as a heat source in a second heat pump 41 . The second heat pump 41 may be an open loop heat pump or a closed loop heat pump, however, due to the temperature of the stream 11 containing ammonia or amine, it is preferred that the second heat pump 41 is a closed loop heat pump as shown here.For generating steam, the second heat pump 41 comprises a first heat exchanger 43, in which a heat transfer medium 45 is heated and evaporated by heat transfer from the stream 11 depleted in ammonia or amine. After evaporation, the heat transfer medium is compressed in a compressor 47. Due to compression, the temperature of the heat transfer medium 45 increases. Subsequently, the compressed heat transfer medium 45 flows through a second heat exchanger 49, in which steam 51 is generated by evaporating water 53 by heat transfer from the heat transfer medium 45. Due to the heat transfer, the heat transfer medium at least partly condenses. The cooled and condensed heat transfer medium is expanded in an expansion device 55, for example a throttle. By expansion, the heat transfer medium is further cooled. The cooled and condensed heat transfer medium then is recycled into the first heat exchanger 43. Depending on the intended use, the steam 57 is compressed in at least one compressor 59, thereby obtaining low pressure steam, medium pressure steam or high pressure steam.A third heat pump 61 can be provided for using the heat of the purified alkanolamine containing product stream 29. As the first heat pump 31 , the third heat pump may be a closed loop heat pump or an open loop heat pump and preferably is an open loop heat pump. For using the heat of the purified alkanolamine containing product stream 29, the third heat pump 61 comprises a heat exchanger 63, in which heat is transferred from the purified alkanolamine containing product stream 29 to a water stream 65. By the heat transfer, the water stream 65 is evaporated, thereby obtaining steam 67. As in the first heat pump 31 or the second heat pump 51 , the steam 67 may be compressed in at least one compressor 69 to obtain low pressure steam, medium pressure steam or high pressure steam, depending on the steam demand.If the process comprises the third distillation stage 19, a fourth heat pump 71 may be comprised to use the heat of the water separated from the crude alkanolamine containing product stream 15. The fourth heat pump 71 also may be a closed loop heat pump or an open loop heat pumpand, preferably, is an open loop heat pump. In the third heat pump 71 , a water stream 73 is evaporated in a heat exchanger 75 by heat transfer from the water 21 that is removed from the crude alkanolamine containing product stream 15. Depending on the steam demand, the steam may be compressed in at least one compressor 79 to obtain low pressure steam, medium pressure steam or high pressure steam.If more than one heat pump is used and in at least two heat pumps steam is generated having essentially the same pressure, it is possible to join the steam streams obtained in the at least two heat pumps forming one steam stream. The steam produced in the heat pumps may be used either directly in a process, for example for heating a distillation column or a reaction, or may be fed into a steam grid and distributed to processes that need steam of the respective pressure.For setting the amount of steam to be produced, it may be preferred to provide by-pass lines by which the heat exchangers 33, 43, 63, 73 can be bypassed by at least a part of the respective gas stream withdrawn at the top the respective distillation column. By bypassing a part of the gas stream, the amount of steam to be produced is reduced and by bypassing the whole gas stream, in the respective heat pump no steam is generated. This may be for example necessary it the amount of steam that is needed is reduced or for maintenance purposes of the heat pump without a shut-down of the whole process.

Claims

Claims1 . A process for working up an alkanolamine, water, and ammonia or amine containing stream (5), comprising:(a) distilling off ammonia or amine from the alkanolamine, water, and ammonia or amine containing stream (5) in a first distillation stage (7), thereby obtaining a stream (9) depleted in ammonia or amine and a stream (11) containing ammonia or amine;(b) distilling off residual ammonia or amine from the stream (9) depleted in ammonia or amine in a second distillation stage (13), thereby obtaining a crude alkanolamine containing product stream (15) and a water and ammonia or amine containing stream (17);(c) optionally distilling off water from the crude alkanolamine containing product stream (15) in a third distillation stage (19);(d) working up the crude alkanolamine containing product stream (15; 23) in a fourth distillation stage (25), thereby obtaining a purified alkanolamine containing product stream (29), characterized in at least one of; the water and ammonia or amine containing stream (17) is used as a heat source in a first heat pump (31) for generating steam; the stream (11) containing ammonia or amine obtained in step (a) is used as a heat source in a second heat pump (41) for generating steam; the purified alkanolamine containing product stream (29) is used as a heat source in a third heat pump (61); and the water (21 ) distilled off in the third distillation stage (19) is used as a heat source in a fourth heat pump (71).

2. The process according to claim 1 , wherein the first heat pump (31) is an open loop heat pump and comprises a heat exchanger (33) in which water (35) is evaporated by heat transfer from the water and ammonia or amine containing stream (17) to generate steam and the steam subsequently is compressed in at least one compressor.

3. The process according to claim 1 or 2, wherein the alkanolamine, water, and ammonia or amine containing stream (5) is obtained in a reactor (3) for producing alkanolamine by reaction of alkylene oxide with ammonia or amine.

4. The process according to any of claims 1 to 3, wherein the second heat pump (41) comprises a closed loop and generating steam comprises:(i) heating and evaporating a heat transfer medium (45) by heat transfer from the stream (11) depleted in ammonia or amine in a first heat exchanger (43),(ii) compressing the heat transfer medium,(iii) generating steam (57) by evaporating water (53) by heat transfer from the heat transfer medium (45) in a second heat exchanger (49), thereby condensing the heat transfer medium,(iv) expanding the heat transfer medium,(v) returning the heat transfer medium into step (i), and(vi) compressing the steam (57) obtained in step (iii) in at least one compressor (59).

5. The process according to claim 4, wherein the heat transfer medium (45) is selected from the group consisting of water, glycol-water mixtures or heat transmission liquids like ethyleneoxide, cyclobutene, 1 -butyne, cis-butene, trans-butene, 1 ,3-butadiene, 1 -butene, propyne, butane, isobutene, dimethylether, cyclopropane, ammonia, propadiene, neopentane, isobutane, R441A, R1233ZDE, R1234ZEZ, R1224YDZ, R40, R436B, R510A, R435A, R429A, R436A, RE235CB2, R152A and R440A.

6. The process according to any of claims 3 to 5, wherein a flash evaporator is arranged upstream the first distillation stage (7) and an ammonia or amine containing vapor stream and an alkanolamine containing liquid stream are obtained in the flash evaporator by partial evaporation of at least a part of a crude reaction product obtained in the reactor (3) for producing alkanolamine.

7. The process according to claim 6, wherein the ammonia or amine containing vapor stream and the stream (11) containing ammonia or amine obtained in step (a) are mixed and then fed into the second heat pump.

8. The process according to claim 6 or 7, wherein at least a part of the alkanolamine containing liquid stream is the alkanolamine, water, and ammonia or amine containing stream (5), which is fed into the first distillation stage (7).

9. The process according to any of clams 1 to 8, wherein the third heat pump (61) is an open loop heat pump and comprises a heat exchanger (63) in which water (65) is evaporated by heat transfer from the purified alkanolamine containing product stream (29) to generate steam (67) and the steam (67) subsequently is compressed in at least one compressor (69).

10. The process according to any of claims 1 to 9, wherein the first distillation stage (7) is operated in a first distillation column at a pressure in a range from 3 to 25 bar(abs), a bottom temperature in a range from 120 to 220 °C and a head temperature in a range from 90 to 150 °C.11 . The process according to any of claims 1 to 10, wherein the second distillation stage (13) is operated in a second distillation column at a pressure in a range from 50 mbar(abs) to 8 bar(abs), a bottom temperature in a range from 150 to 200 °C and a head temperature in a range from 70 to 170 °C.

12. The process according to any of claims 1 to 11 , wherein the third distillation stage (19) is operated in a third distillation column at a pressure in a range from 700 mbar(abs) to 1500 mbar(abs), a bottom temperature in a range from 150 to 200 °C and a head temperature in a range from 90 to 120 °C.

13. The process according to any of claims 1 to 12, wherein the fourth distillation stage (25) is operated in a fourth distillation column at a pressure in a range from 50 to 300 mbar(abs), a bottom temperature in a range from 70 to 200 °C and a head temperature in a range from 40 to 170 °C.

14. The process according to any of claims 1 to 13, wherein the alkanolamine is converted into a target product.

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