Process for preparing ammonium chloride

Abstract

There is provided a process and a chemical production unit for producing crystalline ammonium chloride in the presence of a crystallization additive, wherein the process comprises the steps of: a) reacting NH3 and HCl by feeding NH3 and HCl into an aqueous ammonium chloride solution; b) crystallizing ammonium chloride from the aqueous ammonium solution obtained in step a), and c) separating the crystallized ammonium chloride, the energy required in step b) being generated in step a). The crystalline ammonium chloride obtainable by the process is suitable as a flavoring agent, as an animal feed additive, as an additive for cosmetic compositions or as an additive for pharmaceutical compositions.

Description

[0001] The present invention relates to the use of a crystallization additive composed of HCl and NH 3 A process for preparing crystalline ammonium chloride, a chemical production unit for carrying out said process, surface-modified crystalline ammonium chloride and its use as a flavoring agent or as an additive for animal feed, cosmetic compositions or pharmaceutical compositions. Background Art

[0002] Ammonium chloride can be produced commercially by several methods, of which the Solvay process and direct synthesis are the most important. The modified Solvay process (ammonium chloride-soda ash process) uses the reaction of ammonia with carbon dioxide in aqueous sodium chloride, where ammonium chloride and soda are produced. Alternatively, ammonium chloride can be produced by reacting HCl with NH 3 Direct response production between.

[0003] DE 2318514 A discloses a method for preparing powdered ammonium chloride from gaseous ammonia and HCl gas, wherein the heat of reaction is removed by heat exchange. However, reactions in the gas phase generally have some disadvantages, such as the removal of high energy, undesirable deposits in the reactor, and the crystal shape and particle size distribution may be difficult to control.

[0004] US2024680 discloses a saturator for producing ammonium chloride, which comprises a closed chamber, a container arranged in the chamber and connected to the chamber at its upper end, wherein HCl and NH 3 NH 2 O at 65°C-95°C was fed into the vessel at different levels as a gaseous reactant. 4 The heat of reaction released during the reaction is absorbed as the heat of vaporization of the following substances: NH 3 or any evaporable water supplied as a diluent.

[0005] The process for preparing ammonium chloride may also use aqueous ammonium chloride solutions originating from various sources or production lines.

[0006] CN 103785263 A discloses a method for treating ammonia-containing tail gas produced by calcining ammonium paratungstate, wherein the tail gas is condensed at 30° C. to 80° C. and absorbed by HCl to form a saturated ammonium chloride solution. The crystallized product can be obtained after evaporative crystallization for further use, for example, in fertilizer production.

[0007] CN 103303942 A discloses a method for recovering ammonium chloride from a mother liquor containing glycine, wherein the mother liquor is subjected to a heating / evaporation stage and a flash evaporation stage twice to obtain a liquid with a concentration of about 45%, which is then subjected to continuous crystallization, thickening and centrifugation. The method is described as having low steam consumption.

[0008] CN 109437250 A discloses a combined production method of potassium nitrate and ammonium chloride, wherein the ammonium chloride method comprises a crystallization section, and the crystallization section comprises a flash evaporator and two crystallizers.

[0009] CN 107746066 A discloses a method for absorbing acidic gases generated in an ash plasma melting processing system, wherein HCl gas enters an ammonia spray tower to form NH 4 A Cl solution is concentrated and crystallized by using steam generated in a waste heat recovery unit of a plasma melting processing system.

[0010] AW Bamforth et al., Chem. Process Engng. [Chemical Process and Engineering] 53 (2), 1972, 72-74 disclose a process carried out in aqueous solution, wherein ammonia gas is fed into the cone section of the saturator, and air-diluted HCl is passed into the NH 4 The reaction was carried out at about 80 °C under reduced pressure and in excess NH 3 (pH 8) occurs to produce a supersaturated solution. When there are enough crystals in the suspension, extraction begins at a rate corresponding to the amount of ammonium chloride obtained by the reaction. The suspension is extracted from the bottom of the saturator and thickened in a hydrocyclone, and the ammonium chloride is separated and dried in a centrifuge. The mother liquor is recycled to the saturator, and the waste gas from the separator is washed with water.

[0011] The known processes often provide crystalline ammonium chloride of technical quality with no specific requirements or with low requirements for the crystal form or particle size, which are generally sufficient for use as nitrogen fertilizer, as solid electrolyte in dry cell batteries or as a component of flux in tinning and galvanizing. However, use as a flavoring in food applications or as an additive for animal feed, cosmetic compositions or pharmaceutical compositions requires higher qualities, which can only be achieved with great effort.

[0012] The aqueous ammonium chloride solution is usually subjected to cooling crystallization or preferably evaporative crystallization. The latter usually uses several consecutive evaporation units to utilize the applied energy as best as possible, so-called multiple-effect evaporation units. The first effect is heated by steam, the following stages are heated by steam from the upstream unit. With multiple effects, the steam consumption can be reduced accordingly.

[0013] For example, CN 109381880 A discloses a method for treating wastewater containing ammonium chloride using a triple-effect evaporation crystallization system and a condensation device. The evaporation crystallization system includes a crystallization device for vapor-liquid separation, a circulation pump and a heating device, wherein the vapor is used to heat another heating device and condense.

[0014] The reaction and crystallization stages known in the art for preparing ammonium chloride from aqueous solutions are usually not linked to their energy balance. When about two thirds of the water have to be evaporated from an approximately 35 wt % ammonium chloride solution at a temperature of 50° C., a high energy input is still required. This is usually done from an external source, for example by applying heating steam.

[0015] In addition, when using crystalline ammonium chloride in various applications, the crystal form should be considered. The crystal form obtained from the aqueous solution may be influenced by other substances. In the absence of so-called crystallization additives, ammonium chloride crystals grow anisotropically and dendritic crystals are obtained from pure aqueous solution. However, dendritic crystals are undesirable for unfavorable flow characteristics, increased residual moisture due to the high specific surface area, and for agglomeration due to the possibility that the crystals become intertwined.

[0016] A. Chianese et al., Journal of Crystal Growth, 166, 1996, 1099-1104, describe the influence of inorganic cations such as Mn(II) ions on the crystal habit. Moreover, organic substances such as urea or pectin may influence crystal growth. Ammonium chloride crystals grow in the form of cubes in solutions to which urea is added, as described by YV Naidich, Adgeziya Rasplavov i Paika Materialov [Adhesion of Molten Metals to Materials] (1993), 30, 43-6. Depending on the amount of pectin in the aqueous solution, the octahedral faces of the dendrites can be transformed into cubic faces, as described by I.YA.Melik-Gaikazyan et al., Izvest.Tomsk.Politekh.Inst. [Journal of Tomsk Polytechnic University], 1958, 95, 372-377.

[0017] Therefore, there is still a need for a process for preparing and crystallizing ammonium chloride which meets the requirements of desired product properties and energy consumption, especially on an industrial scale.

[0018] Therefore, the object of the present invention is to provide a process for preparing crystalline ammonium chloride in an economical way, also taking environmental factors into account. The process should require essentially no energy input or require low energy input, allow high yields of crystalline material, especially minimal losses of starting material and product via wastewater or exhaust gas, allow targeted adjustment of product properties and / or be reliable for damage caused, for example, by undesirable deposits.

[0019] Furthermore, the object of the present invention is to provide a high-quality crystalline ammonium chloride suitable for use as a flavoring agent, an animal feed additive, or as an additive for cosmetic or pharmaceutical compositions. The product should have at least one of the following properties, like a defined crystal morphology, a narrow particle size distribution, low residual moisture, good flowability and / or a low tendency to agglomeration, even when stored for a long time. Summary of the invention

[0020] It has now been found that crystalline ammonium chloride can be obtained by a two-stage production process, wherein the reaction stage and the crystallization stage are substantially separated, but energetically linked. This allows a substantially autothermal process, wherein the energy generated in the reaction stage enables evaporation to be achieved during the crystallization stage.

[0021] Therefore, in a first aspect, the present invention relates to a process for producing crystalline ammonium chloride in the presence of a crystallization additive, the process comprising the following steps:

[0022] a) By adding NH 3 and HCl is fed to NH 4 NH Cl in aqueous solution 3 Reaction with HCl;

[0023] b) making ammonium chloride from the NH 4 Cl crystallizes from aqueous solution, and

[0024] c) separating the crystalline ammonium chloride,

[0025] The energy required in step b) is generated in step a).

[0026] In another aspect, the present invention relates to a surface modified crystalline ammonium chloride obtainable or obtained by a process as defined in any aspect herein.

[0027] In another aspect, the present invention relates to the use of crystalline ammonium chloride obtainable or obtained by a process as defined in any aspect herein as a flavoring agent, as an animal feed additive, as an additive for a cosmetic composition or as an additive for a pharmaceutical composition.

[0028] In another aspect, the present invention relates to a method for applying the crystalline ammonium chloride obtainable or obtained by a method as defined in any aspect herein as a flavoring agent to food or as an additive to animal feed, cosmetic compositions or pharmaceutical compositions.

[0029] In another aspect, the present invention relates to a chemical production unit for carrying out the method as defined in any aspect herein, the chemical production unit comprising

[0030] - a reaction zone comprising

[0031] - used to convert NH 3 an inlet device for feeding into the reaction zone,

[0032] - inlet means for feeding HCl into the reaction zone,

[0033] - a mixing device,

[0034] - Used to obtain NH 4 Apparatus for phase separation of aqueous Cl solution and reaction vapor,

[0035] - circulation pump,

[0036] - heat exchangers,

[0037] - used to convert the NH 4 The device for passing Cl aqueous solution into the crystallization zone,

[0038] - means for passing the reaction vapors into the crystallization zone,

[0039] - a crystalline region comprising

[0040] - used to convert the NH 4 The Cl aqueous solution is fed into the inlet device in the crystallization zone,

[0041] - used to obtain NH 4 Evaporator for aqueous suspensions of Cl,

[0042] - circulation pump,

[0043] - heat exchangers,

[0044] - used to 4 The suspension of Cl is passed into the separation zone.

[0045] - a separation zone comprising

[0046] - one or more for obtaining crystalline NH 4 Cl separation device, and

[0047] - Inlet device for feeding crystallization additives. DETAILED DESCRIPTION

[0048] As used herein, the term "substantially autothermal" means that during stable operation at least 80%, preferably at least 90%, more preferably at least 95% of the energy required in step b) is generated in step a).

[0049] As used herein, the term "stable operation" means standard operating conditions for the manufacture of crystalline ammonium chloride, thus excluding any brief periods of start-up or shutdown of the chemical production unit itself. The water added to steps a) to c) should be minimal, e.g., at most 5%, and a HCl concentration of at least 37 wt% is required.

[0050] As used herein, the term "reaction loop" means a loop comprising the apparatus for step a), typically comprising apparatus for phase separation, a circulation pump, a heat exchanger and a mixing apparatus.

[0051] As used herein, the term "crystallization loop" means a loop comprising the equipment used in step b), typically including an evaporator, a circulation pump and a heat exchanger.

[0052] As used herein, the term "reaction stage" means the process of step a) within the reaction loop and the reaction vapors and NH 2 withdrawn from the reaction loop. 4 Transfer of aqueous Cl solution to the crystallization loop.

[0053] As used herein, the term "crystallization stage" refers to the process of step b) within the crystallization loop and the NH 4 Transfer of the aqueous Cl suspension to the separation device.

[0054] As used herein, the term "separation stage" means the process within the separation step c).

[0055] As used herein, the term "reaction zone" means a zone for conducting a reaction stage.

[0056] As used herein, "crystallization zone" means a zone used to carry out the crystallization stage.

[0057] As used herein, "separation zone" means a zone used to perform a separation stage.

[0058] For example, the d in the cumulative frequency distribution of the weight-average size distribution function (median diameter, particle size distribution) obtained by sieving analysis 50 The values ​​indicate that 50 wt% of the particles have a diameter that is the same as or smaller than the respectively indicated value. 50 The value can be determined according to the method described in ISO 2591-1:1988-12.

[0059] As used herein, pressure in bar means absolute pressure in bar.

[0060] As used herein, the term "a combination thereof" or "any combination thereof" means any possible combination of two or more components mentioned in the corresponding list of components of the same kind or different kinds.

[0061] As used herein, the indefinite article "a / kind" includes the singular and also the plural, that is, the indefinite article for a component of a composition means that the component is a single compound or a plurality of compounds. If not otherwise stated, the indefinite article "a / kind" and the expression "at least one / kind" are used synonymously.

[0062] Figure 1 A schematic overview of a preferred embodiment of the method of the present invention is shown.

[0063] Figure 2 Microscopic pictures of products obtainable by the process of the present invention are shown.

[0064] The method of the present invention for producing crystalline ammonium chloride mainly comprises three stages: a reaction stage, a crystallization stage and a separation stage.

[0065] Process step a) involves the reaction phase, i.e., the reaction of NH 3 The step of reacting with HCl, wherein NH 3 and HCl is fed to NH 4 Cl aqueous solution. 4 Aqueous Cl solution preferably travels through the reaction loop. NH 3 Preferably it is fed as a gas. HCl is preferably fed as an aqueous solution.

[0066] Typically, the reaction loop comprises means for phase separation; a pump, preferably a circulation pump; a heat exchanger; and a mixing device. An aqueous ammonium chloride solution circulates within the reaction loop.

[0067] Therefore, in a preferred aspect, the present invention relates to a process for producing crystalline ammonium chloride in the presence of a crystallization additive, the process comprising the steps of:

[0068] a) By adding NH 3 and HCl is fed to NH 4 NH Cl in aqueous solution 3 Reaction with HCl;

[0069] b) making ammonium chloride from the NH 4 Cl crystallizes from aqueous solution, and

[0070] c) separating the crystalline ammonium chloride,

[0071] wherein the energy required in step b) is generated in step a), and

[0072] Make NH 4 The aqueous Cl solution travels through a reaction loop which preferably comprises a circulation pump, a mixing device and a vessel for phase separation.

[0073] The device for phase separation can be any container suitable for phase separation, such as a phase separator. The heat exchanger can be a tube bundle heat exchanger. The mixing device can be any mixer suitable for a pipeline, such as a static mixer, a jet mixer or an in-line mixer.

[0074] The heat exchanger may be supplied with an external source of steam or fuel gas, for example external steam at a pressure of 0.2 to 5 bar, preferably 0.5 to 3 bar, to heat the system of the reaction zone to NH during start-up of the chemical production unit, preferably the reaction zone, of the process. 4 The expected operating temperature of aqueous Cl solution. NH 4 The operating temperature of the aqueous Cl solution is such that the production of NH 4 Steady state operation of the unit of Cl. Any condensate from the heat exchanger can be collected in a separate container.

[0075] Typically, a stream of aqueous ammonium chloride solution is passed (preferably pumped) through the reaction loop. Typically, the concentration of the aqueous ammonium chloride solution is slightly undersaturated, for example in the range of 30 wt% to 45 wt%, depending on the operating temperature and pressure in the reaction loop.

[0076] The concentration is preferably adjusted to a concentration of about 3 wt% to 10 wt% below the saturation limit. Preferably, the concentration is about 35 wt% to about 45 wt%, preferably at an operating temperature of about 50°C to 130°C, preferably 80°C to 120°C and a pressure of 0.1 to 3 bar in the reaction loop. 4 These ranges of Cl concentration, pressure and temperature generally include pressures and temperatures throughout the reaction loop. At operating temperatures of 95° C. to 120° C. and pressures of 0.2 to 2 bar, particularly 0.2 to 1.5 bar, the NH 4 An especially preferred concentration of the aqueous Cl solution is about 35 wt % to 42 wt %.

[0077] The circulation volume of the aqueous ammonium chloride solution in the reaction loop and the dosing rate of the gaseous ammonia are generally such that the ammonia is completely dissolved.

[0078] The circulation volume of the aqueous ammonium chloride solution can vary within wide limits, generally depending on the production capacity.

[0079] The dosing of ammonia can be carried out by a suitable inlet device suitable for the gas. Suitable examples include any nozzle inlet, jet pump or feed pipe, such as an ejector. The inlet device for dosing ammonia is usually located between the heat exchanger and the inlet device for HCl. The dosing rate of ammonia can vary widely, usually depending on the circulation volume and production capacity.

[0080] The aqueous hydrochloric acid solution to be fed preferably has a concentration of 20 wt % to 38 wt %, more preferably 25 wt % to 38 wt %, especially 30 wt % to 38 wt %, and in particular 32 wt % to 38 wt %. The dosing rate of the aqueous HCl solution can vary widely, usually depending on the circulation volume and production capacity.

[0081] Therefore, in a preferred aspect, the present invention relates to a process for producing crystalline ammonium chloride, wherein NH 3 As a gas feed, and HCl as an aqueous solution at a concentration of 20 to 38 wt%, preferably at a concentration of 25 to 38 wt%, more preferably at a concentration of 30 to 38 wt%.

[0082] In another preferred aspect, the present invention relates to a method for producing crystalline ammonium chloride, wherein the NH 4 The concentration of the Cl aqueous solution is 30 wt% to 45 wt%. This concentration range generally includes NH 4 The concentration of Cl.

[0083] Further preferred is a process for producing crystalline ammonium chloride, wherein step a) is carried out at a pressure of 0.1 to 3 bar and a temperature of 50° C. to 130° C. These ranges of pressure and temperature generally include the pressures and temperatures within the entire reaction loop.

[0084] Particularly preferred is a process for producing crystalline ammonium chloride, wherein the NH 4 The concentration of the aqueous Cl solution is 35 wt % to 42 wt %, in particular at a temperature of 90° C. to 120° C. and a pressure of 0.2 to 2 bar.

[0085] The aqueous hydrochloric acid solution can be fed into the reaction loop via a suitable inlet device, for example using a dosing pump. The aqueous HCl solution can be fed before or into the mixing device, preferably into the mixing device, in which the NH 3 Neutralization reaction with HCl. 4 When the aqueous Cl solution leaves the mixing device, the neutralization reaction is usually rapid and complete.

[0086] NH 3 The amounts of HCl and HCl are usually equimolar. 3 The molar ratio of is typically in the range of 0.95:1.05 to 1.05:0.95, preferably 0.96:1.04 to 1.04:0.96, more preferably 0.98:1.02 to 1.02:0.98.

[0087] Therefore, in a preferred aspect, the present invention relates to a process for producing crystalline ammonium chloride, wherein HCl:NH3 The molar ratio is 0.95:1.05 to 1.05:0.95, preferably 0.96:1.04 to 1.04:0.96.

[0088] Preferably, at the operating temperature and pressure, the NH 4 The pH value of the Cl aqueous solution is usually <6, preferably <5.

[0089] During the reaction, a slight overpressure of, for example, >1 to 3 bar, preferably >1 to 2 bar, can be maintained in order to carry out the reaction of ammonia with hydrochloric acid without causing NH 4 The aqueous Cl solution boils and forms vapor in the mixing unit. The complete exothermic energy of the neutralization reaction results in only circulating NH 4 The temperature of the Cl aqueous solution increases. The circulating NH 4 The operating temperature of the Cl aqueous solution (reaction solution) may be raised in the range of 5°C to 30°C, but is preferably not higher than 130°C.

[0090] Therefore, in a preferred aspect, the present invention relates to a process for producing crystalline ammonium chloride, wherein the energy required in step b) is obtained in step a) by converting NH 3 The reaction heat with HCl is generated, which is released in the form of reaction vapors.

[0091] Preferably, reaction step a) comprises reacting NH 3 A step of reacting with HCl and a subsequent step of generating reaction vapors are performed.

[0092] Therefore, in a preferred aspect, the present invention relates to a process for producing crystalline ammonium chloride in the presence of a crystallization additive, wherein step a) comprises

[0093] a-1) Make NH 3 step of reaction with HCl, and

[0094] a-2) a step of generating reaction vapor,

[0095] The steps described therein are performed individually.

[0096] Then, the reaction solution (i.e., the superheated NH 4 Cl aqueous solution) is passed into the apparatus for phase separation of step a-2), wherein the pressure is generally reduced upon entry to a pressure of, for example, <1 bar, preferably ≤0.8 bar, more preferably 0.2 to 0.8 bar. This can be achieved by conventional means, for example via a throttle valve or an orifice plate. The reduced pressure generally leads to boiling of the reaction mixture, wherein water is partially evaporated to produce NH 4 Cl aqueous solution and reaction vapor. 4The Cl aqueous solution is cooled to a certain degree, for example, by 3°C to 10°C, for example, to a temperature of about 70°C to 120°C.

[0097] Preferably, NH 3 Step a-1) of reaction with HCl is carried out in a mixing device and step a-2) of generating reaction vapors is carried out in a phase separation vessel.

[0098] Step a-2) is usually a phase separation, in which reaction vapors and NH 4 A phase of aqueous Cl solution, said solution generally having a concentration as high as that of the aqueous solution obtained after step a-1).

[0099] In a preferred aspect, the present invention relates to a process for producing crystalline ammonium chloride, wherein the reaction vapor is generated by decompression, preferably to a pressure of <1 bar, more preferably to a pressure of 0.2 to 0.8 bar.

[0100] Therefore, further preferred is a process for producing crystalline ammonium chloride in the presence of a crystallization additive, wherein step a) comprises

[0101] a-1) Make NH 3 a step of reacting with HCl at a pressure of >1 to 3 bar, preferably >1 to 2 bar, and

[0102] a-2) a step of generating a reaction vapor at a pressure of <1 bar, preferably from 0.2 to 0.8 bar,

[0103] The steps described therein are performed individually.

[0104] The amount of water to be evaporated is usually calculated so that the NH 4 The concentration of the aqueous Cl solution is in the range corresponding to the concentration present in the reaction loop, thus typically being between 30 wt% and 45 wt%, depending on the operating temperature and pressure in the reaction loop.

[0105] NH 4 Cl does not crystallize in the reaction loop during step a). This allows the material of the reaction zone to be protected from any abrasion.

[0106] The amount of water evaporated in the apparatus for phase separation generally depends on the production capacity.

[0107] The resulting reaction vapors can be purified, in particular from any entrained solvents such as NH 4 Cl solution, ammonia and / or HCl. Any suitable droplet separation device can be applied to the top of the device for phase separation, preferably a demister, like an aerosol separator or a droplet separator. Preferably, a combination of an aerosol separator and a droplet separator is used.

[0108] Therefore, in a preferred aspect, the present invention relates to a process for the production of crystalline ammonium chloride, wherein the reaction vapors are purified.

[0109] The reaction vapors can then be passed to the shell side of the heat exchanger of the subsequent crystallization stage of step b).

[0110] NH 4 The aqueous Cl solution is circulated to the unit in a reaction loop, usually via the suction side of a circulation pump and a heat exchanger, wherein ammonia gas is usually fed into the reaction loop.

[0111] NH 4 A portion of the aqueous Cl solution is usually removed from the reaction loop at a constant rate and fed to the crystallization loop for further evaporation and crystallization. This preferably occurs on the pressure side of the circulation pump. Typically, depending on the production capacity, the amount of circulation volume removed for evaporation and crystallization can be about 2% to 30%, more preferably 5% to 20% of the initial circulation volume.

[0112] Therefore, in a preferred aspect, the present invention relates to a process for producing crystalline ammonium chloride, wherein the NH 4 A portion of the aqueous Cl solution is fed to step b).

[0113] Process step b) is a crystallization stage, preferably comprising evaporative crystallization. The crystallization stage may comprise one or several crystallization stages, preferably one to three crystallization stages, which are connected in parallel or in series, preferably in parallel.

[0114] Therefore, in a preferred aspect, the present invention relates to a process for producing crystalline ammonium chloride, wherein the crystallization in step b) is carried out by one or more evaporation-crystallization loops, which are preferably arranged in parallel.

[0115] The crystallization and evaporation of ammonium chloride solution are usually carried out in a circulating evaporator. The crystallization loop usually includes a circulating pump, a heat exchanger and an evaporator. The principle of evaporative crystallization is generally known in the art.

[0116] Any suitable evaporator may be used, for example a Robert-type evaporator, an Oslo-type evaporator or a forced circulation (FC) evaporator.The heat exchanger may be a tube bundle type heat exchanger.

[0117] Crystallization and evaporation can be carried out with a circulation volume which is preferably higher than the circulation volume of the reaction loop. The temperature and pressure are lower than the temperature and pressure of the reaction loop. This allows the process of step a) and step b) to be operated in a substantially autothermal manner.

[0118] The NH that is usually partially removed from the reaction stage 4The Cl aqueous solution is fed into the crystallization loop at the suction side of the circulation pump, preferably via one or preferably multiple inlet devices. The circulation flow can be passed into a heat exchanger, NH 4 The aqueous Cl solution is heated therein. The heat exchanger is operated with the reaction vapors withdrawn from the reaction stage or part thereof (in the case of multiple crystallization loops). Any condensate is usually collected in a separate container.

[0119] Process steps a) and b) are usually operated in a substantially autothermal manner during steady-state operation. Heating the partially removed NH 4 The energy of the aqueous Cl solution is provided by the reaction vapor produced in step a). Typically, during stable operation, at least 90%, preferably at least 95%, more preferably at least 98% of the energy required in step b) is produced in step a). In particular, the reaction vapor is sufficient for process step b) without external energy. In the case where external energy is required, for example, external vapor at a pressure of 0.1 to 3 bar, preferably 0.2 to 2 bar, can be added to the reaction vapor.

[0120] Water is typically evaporated from the solution in an evaporator in an amount sufficient to result in supersaturation of the solution and crystallization of ammonium chloride and growth of ammonium chloride crystals, which is generally dependent on production capacity. The pressure and temperature in the evaporator are generally lower than the pressure and temperature in the apparatus used for phase separation. The resulting NH 4 The Cl aqueous suspension preferably has a concentration of about 5 wt % to 40 wt %.

[0121] The vacuum required for evaporation can be generated by conventional means, for example by using a vacuum pump, such as a liquid ring compressor or a jet pump.

[0122] The vapor stream resulting from the evaporation may be purified prior to condensation, in particular freed from any entrained solution, for example by any suitable separation device. Optionally the purified crystallization vapor may be condensed using a heat exchanger (e.g. a plate heat exchanger) and collected in a container for the condensate. Alternatively, the crystallization vapor may be used in another process, like preheating of the feedstock or a downstream evaporation device.

[0123] The NH obtained in the evaporator can be continuously removed from the crystallization loop, usually by means of a pump. 4 Cl aqueous suspension and feed it to the third stage for separation of ammonium chloride as solid. This may take place between the evaporator and the circulation pump or between the circulation pump and the heat exchanger of the crystallization loop, preferably between the evaporator and the circulation pump. Preferably, the NH 4 The concentration of the Cl aqueous suspension is about 5 wt % to 40 wt %.

[0124] Process step c) is a separation stage, preferably a solid-liquid separation stage. The separation step can be carried out with conventional separation devices, preferably in multiple steps, with the application of energy known in the art for inorganic crystallized salts.

[0125] Typically, the separation step is performed by centrifugation or filtration, such as continuous filtration using, for example, a drum filter, preferably by centrifugation. A suitable separation device may be a pusher centrifuge. Alternatively, a hydrocyclone may be used in addition before the centrifuge.

[0126] Therefore, in a preferred aspect, the present invention relates to a process for producing crystalline ammonium chloride, wherein the crystalline ammonium chloride is separated in one or more separation stages, preferably by centrifugation.

[0127] The streams from one or more evaporators may be fed to the separation stage as separate streams, or may suitably be fed as a combined stream.

[0128] The stream of one or more evaporators can be passed into a first solid-liquid separation stage using one or more hydrocyclones to separate into a thick lower stream and an upper stream with a lower solid content. The thick lower stream can then be passed into a second separation stage using one or more centrifuges.

[0129] In case of multiple hydrocyclones, they are preferably used in parallel, wherein the streams are divided to the number of hydrocyclones applied. The thick lower streams can be combined before the second separation stage or processed separately. Preferably, the thick lower streams are combined for the second separation stage.

[0130] The upper stream is usually fed to a vessel where the mother liquor is collected, preferably after combining the upper streams in the case of multiple hydrocyclones.

[0131] After centrifugation, the wet ammonium chloride can be separated as a centrate and can be dried in a suitable dryer, such as a flash dryer, a belt dryer or a drying drum, and cooled.

[0132] The saturated ammonium chloride solution separated as the centrate can be discharged into a container for collecting the mother liquor.

[0133] The mother liquor collected from the separation stage can be recycled, preferably pumped, into the reaction loop to close the complete 3 stages. The recycling step allows the NH 4 The Cl aqueous solution can be kept undersaturated.

[0134] Therefore, in a preferred aspect, the present invention relates to a process for the production of crystalline ammonium chloride, wherein the mother liquor obtained in step c) is recycled to step a).

[0135] In order to obtain the desired morphology of crystalline NH4 C1, the process of the present invention is carried out in the presence of a crystallization additive. The crystallization additive can be added in different steps of the process, for example in the crystallization stage and / or the separation stage, preferably in step b) and / or step c), preferably in step b).

[0136] Therefore, in a preferred aspect, the present invention relates to a process for producing crystalline ammonium chloride, wherein a crystallization additive is added in step b) and / or step c), preferably step b).

[0137] The crystallization additive can be added to the crystallization stream before it enters the crystallization loop. The crystallization additive can also be added to the crystallization loop of step b), preferably on the suction side of the circulation pump. The crystallization additive can also be added to the separation stage of step c), preferably before entering the centrifuge or preferably before the second separation stage.

[0138] The crystallization additive may be added via a suitable inlet device, for example using a dosing pump or any nozzle inlet.

[0139] The crystallization additive can be added to the process of the present invention in any suitable form, preferably as an aqueous solution, for example as an aqueous solution, an ammonium chloride solution like the lean mother liquor obtained in the process, or a solution in ammonia. The solvent of the aqueous solution can be appropriately selected according to the type of crystallization additive. Preferably, the crystallization additive is in the form of an aqueous solution, more preferably as a solution in water or in a solution containing NH 4 Add the solution of Cl in the mother liquor.

[0140] The aqueous solution of the crystallization additive preferably has a concentration of 0.01 wt% to 10 wt%, more preferably 0.1 wt% to 5 wt%, based on the total weight of the solution. The concentration may depend on the type of the crystallization additive and its solubility in the corresponding aqueous system.

[0141] The crystallization additive preferably comprises at least one hydrophilic polymer, more preferably a hydrophilic polymer based on a sugar derivative, most preferably a polysaccharide or a derivative thereof.

[0142] The crystallization additive may also be used as any mixture of two or more polysaccharides or their derivatives.

[0143] Therefore, in a preferred aspect, the present invention relates to a process for producing crystalline ammonium chloride, wherein the crystallization additive is a polysaccharide, a derivative thereof, or any combination thereof.

[0144] The polysaccharide or its derivative is advantageously selected so that not only the polysaccharide or its derivative itself but also any thermal decomposition products in the amounts typically present or formed are suitable as additives for food or animal feed and do not adversely affect the taste of any food processed with the immediately produced crystalline ammonium chloride. It is preferred to use polysaccharides of natural origin or polysaccharides formed by modifying natural polysaccharides having a neutral taste and approved by food law.

[0145] The polysaccharide or its derivative may be a heteropolysaccharide, a derivative thereof, a homopolysaccharide or a derivative thereof.

[0146] The heteropolysaccharide may be selected from alginic acid, its salts or derivatives like sodium alginate, potassium alginate, ammonium alginate, calcium alginate, propane-1,2-diol alginate, agar, carrageenan, processed Eucheuma algae, locust bean gum / carob bean gum, guar gum, tragacanth gum, gum arabic, xanthan gum, karaya gum, tara gum, gellan gum, konjac gum, konjac glucomannan, soy-hemicellulose, pectin or its derivatives like amidated pectin, and any combination thereof.

[0147] Heteropolysaccharides are typically obtained by fermentation or by isolation from natural sources.

[0148] Homopolysaccharides are typically homopolysaccharides based on glucose and its derivatives, preferably cellulose or its derivatives.

[0149] Therefore, in a preferred aspect, the present invention relates to a method for producing crystalline ammonium chloride, wherein the crystallization additive is selected from heteropolysaccharides, derivatives thereof, cellulose, derivatives thereof, and any combination thereof.

[0150] Suitable cellulose derivatives are, for example, cellulose ethers, wherein the hydroxyl groups are partially or completely substituted by ether groups. Cellulose ethers can be alkyl ethers or aralkyl ethers, wherein the alkyl or aralkyl groups can be further substituted by hydroxyl, carboxyl or carboxylate groups. The corresponding counterions of the carboxylate groups can be alkali metal ions, such as sodium ions or potassium ions or ammonium ions. Cellulose ethers can carry one type of substituent on the cellulose ether molecular chain, while mixed ethers can carry two or more different substituents, like methyl hydroxyethyl cellulose.

[0151] Preferred cellulose derivatives are methylcellulose, ethylcellulose, propylcellulose, carboxymethylcellulose (CMC), hydroxyethylcellulose, hydroxypropylcellulose, methylhydroxyethylcellulose, methylhydroxypropylcellulose, methylhydroxybutylcellulose, ethylhydroxyethylcellulose, carboxymethylhydroxyethylcellulose, benzylcellulose and any mixed cellulose ethers.

[0152] Among carboxymethylcelluloses, sodium compounds are preferred.

[0153] Cellulose ethers are prepared in a known manner, typically by the action of alkyl halides or aralkyl halides, epoxides or activated olefins on cellulose which has been activated with a base, for example with aqueous sodium hydroxide solution. Cellulose ethers are generally commercially available, for example under the trade name or (For food applications).

[0154] Preferred are polysaccharides or derivatives thereof that have been approved as food additives.

[0155] Examples of heteropolysaccharides include alginic acid (E 400), sodium alginate (E 401), potassium alginate (E 402), ammonium alginate (E 403), calcium alginate (E 404), propane-1,2-diol alginate (E 405), agar (E 406), carrageenan (E 407), processed Eucheuma algae (E 407a), locust bean gum / carob bean gum (E 410), guar gum (E 412), tragacanth gum (E 413), gum arabic (E 414), xanthan gum (E 415), karaya gum (E 416), tara gum (E 417), gellan gum (E 418), ghatti gum (E 419), konjac gum (E 425i), konjac glucomannan (E 426), konjac gum (E 427i), konjac gum (E 428), konjac gum (E 429), konjac gum (E 430), konjac gum (E 431), konjac gum (E 432), konjac gum (E 433), konjac gum (E 434), konjac gum (E 435), konjac gum (E 436), konjac gum (E 437), konjac gum (E 438), konjac gum (E 439), konjac gum (E 440), konjac gum (E 441), konjac gum (E 442), konjac gum (E 443), konjac gum (E 444), konjac gum (E 445), konjac gum (E 446), konjac gum (E 447), 425ii), soybean-hemicellulose (E426), pectin (E 440i), amidated pectin (E 440ii) and any combination thereof.

[0156] Examples of homopolysaccharides or their derivatives include cellulose (E 460), methylcellulose (E 461), ethylcellulose (E 462), hydroxypropylcellulose (E 463), hydroxypropylmethylcellulose (E 464), ethylmethylcellulose (E 465), carboxymethylcellulose (E 466), cross-linked sodium carboxymethylcellulose (E 468), enzymatically hydrolyzed carboxymethylcellulose (E 469), polydextrose (E 1200), pullulan (E 1204), oxidized starch (E 1404), monostarch phosphate (E 1410), distarch phosphate (E 1412), phosphorylated distarch phosphate (E 1413), acetylated distarch phosphate (E 1414), acetylated starch (E 1420), acetylated distarch adipate (E 1422), hydroxypropyl starch (E 1440), hydroxypropyl distarch phosphate (E 1442), sodium starch octenylsuccinate (E 1444). 1450), acetylated oxidized starch (E 1451), and any combination thereof.

[0157] Thus, in a preferred aspect, the present invention relates to a process for producing crystalline ammonium chloride, wherein the crystallization additive is selected from the group consisting of alginic acid (E 400), sodium alginate (E 401), potassium alginate (E 402), ammonium alginate (E 403), calcium alginate (E 404), propylene glycol alginate (E 405), carrageenan (E 407), tragacanth gum (E 413), gum arabic (E 414), xanthan gum (E 415), karaya gum (E 416), gellan gum (E 418), ghatti gum (E 419), pectin (E 440i), amidated pectin (E 440ii), cellulose (E 460), methylcellulose (E 461), ethylcellulose (E 462), hydroxypropyl cellulose (E 463), hydroxypropyl methylcellulose (E 464), 464), ethyl methyl cellulose (E465), carboxymethyl cellulose (E 466), cross-linked sodium carboxymethyl cellulose (E 468), enzymatically hydrolyzed carboxymethyl cellulose (E 469), and any combination thereof.

[0158] Preferred heteropolysaccharides are heteropolysaccharides having COOH groups, derivatives thereof or heteropolysaccharides having OSO 3 Heteropolysaccharides of groups.

[0159] Therefore, in a preferred aspect, the present invention relates to a method for producing crystalline ammonium chloride, wherein the crystallization additive is a heteropolysaccharide having COOH groups, a derivative thereof, a polysaccharide having OSO 3 The present invention relates to a heteropolysaccharide of a polysaccharide group, preferably a heteropolysaccharide based on galacturonic acid, mannuronic acid, guluronic acid, glucuronic acid or a derivative thereof, cellulose, or cellulose ether.

[0160] In particular, the crystallization additive is a heteropolysaccharide based on galacturonic acid, mannuronic acid, guluronic acid, glucuronic acid or any derivatives thereof.

[0161] Particularly preferred crystallization additives are selected from the group consisting of alginic acid (E 400), sodium alginate (E 401), potassium alginate (E 402), ammonium alginate (E 403), calcium alginate (E 404), propylene glycol alginate (E 405), carrageenan (E 407), tragacanth gum (E 413), gum arabic (E 414), xanthan gum (E 415), karaya gum (E 416), gellan gum (E 418), gum ghatti (E 419), pectin (E 440i), amidated pectin (E 440ii) and any combination thereof.

[0162] More preferred is a crystalline additive selected from the group consisting of alginic acid (E 400), sodium alginate (E 401), ammonium alginate (E 403), gellan gum (E 418), pectin (E 440i), amidated pectin (E 440ii) and any combination thereof.

[0163] Most preferred is a crystalline additive selected from the group consisting of pectin (E 440i), amidated pectin (E440ii), and any combination thereof.

[0164] Crystallization additives are usually based on NH 4 The total amount of Cl is 0.1 to 1000 ppm by weight (0.00001 wt% to 0.1 wt%), preferably 1 to 500 ppm by weight, more preferably 5 to 300 ppm by weight. 4 The total amount of Cl is based on the crystallized NH 4 Calculated value for 100% yield of Cl.

[0165] Therefore, in a preferred aspect, the present invention relates to a process for producing crystalline ammonium chloride, wherein the amount of the crystallization additive is 0.1 to 1000 ppm by weight, preferably 1 to 500 ppm by weight, based on the total weight of the crystalline ammonium chloride.

[0166] Increasing the amount of the crystallization additive above a maximum level generally results in an adverse effect on the desired crystal morphology.

[0167] Reducing the amount of crystallization additive below a minimum level also results in an adverse effect on the desired crystal morphology, for example, by obtaining a more dendritic crystal morphology, which may result in more intertwined particles and agglomerates.

[0168] The yield of crystalline ammonium chloride obtained is almost quantitative, in particular ≥98%, in particular ≥99%.

[0169] The median diameter (d) of the crystalline ammonium chloride particles obtainable by this process, after generally removing fines and oversized agglomerates, is 50 ) can be in the range of 50 μm to 1 mm. The median diameter can be adjusted within these limits depending on the desired median diameter.

[0170] Therefore, in a preferred aspect, the present invention relates to a process for producing crystalline ammonium chloride, wherein the crystalline ammonium chloride has a median diameter d of 50 μm to 1 mm. 50 .

[0171] Suitable methods for adjusting the desired particle size may be screening, for example by in-line screening within the crystallization loop, or by adjusting suitable parameters like circulation volume, grinding of large crystals, seeding by adding smaller crystals or by targeted reduction of supersaturation.

[0172] Crystallized ammonium chloride can be treated with an anti-caking agent, stored, filled and packaged. After separation and drying of the crystallized ammonium chloride, an anti-caking agent can be added to prevent the formation of lumps or sizable agglomerates that may form during storage. Examples of anti-caking agents include calcium phosphate, calcium carbonate, magnesium carbonate, silicon (IV) oxide or another conventional anti-caking agent. Preferably, anti-caking agents are approved as food additives and animal feed additives.

[0173] The process of the present invention provides crystalline ammonium chloride, wherein the crystallization additive is attached to the surface of the crystal. Thus, the process of the present invention provides surface-modified crystalline ammonium chloride.

[0174] Therefore, in a preferred aspect, the present invention relates to a process for producing crystalline ammonium chloride, wherein the crystalline ammonium chloride is surface-modified by a crystallization additive.

[0175] In another aspect, the present invention relates to a surface modified crystalline ammonium chloride obtainable by a process as defined in any aspect herein.

[0176] The crystallization additive added to the process of the present invention may be present at least partially or completely in the final product, based on the total weight of the pectin added to the process, and its amount is generally at least 30 wt%, preferably at least 40 wt%, more preferably 40 wt% to 90 wt%. The surface-modified crystalline ammonium chloride may contain the crystallization additive in an amount of 0.03 to 1000 ppm by weight, preferably 1 to 500 ppm by weight, more preferably 5 to 300 ppm by weight, based on the crystalline ammonium chloride.

[0177] The crystalline ammonium chloride obtainable by the process of the present invention can be suitably used for applications in the food industry, the animal feed industry (for example, as a zootechnical additive), the cosmetics industry or the pharmaceutical industry.

[0178] Therefore, in another aspect, the present invention relates to the use of crystalline ammonium chloride obtainable or obtained by a process as defined in any aspect herein as a flavoring agent, as an animal feed additive, as an additive for a cosmetic composition or as an additive for a pharmaceutical composition, preferably as a flavoring agent or as an animal feed additive.

[0179] In another aspect, the present invention relates to the use of crystalline ammonium chloride obtainable by the process as defined in any aspect herein as a flavoring agent in food or as an additive in animal feed, a cosmetic composition or a pharmaceutical composition, preferably as a flavoring agent in food or as an additive in animal feed.

[0180] The process can be carried out with a chemical production unit comprising zones for a reaction stage, a crystallization stage and a separation stage.

[0181] Therefore, in another aspect, the present invention relates to a chemical production unit for carrying out the method as defined in any aspect herein, the chemical production unit comprising

[0182] - a reaction zone comprising

[0183] - used to convert NH 3 (1) an inlet device (3) for feeding into the reaction zone,

[0184] - an inlet device for feeding HCl (2) into the reaction zone,

[0185] - a mixing device (4),

[0186] - Used to obtain NH 4 an apparatus (5) for phase separation of aqueous Cl solution and reaction vapor (11),

[0187] - a circulation pump (7),

[0188] - a heat exchanger (8), preferably supplied with steam (9) during the start-up phase,

[0189] - used to convert NH 4 The Cl aqueous solution (10) is passed into the crystallization zone,

[0190] - means for passing the reaction vapor (11) into the crystallization zone,

[0191] - a crystalline region comprising

[0192] - used to convert NH 4 The Cl aqueous solution is fed into the inlet device in the crystallization zone,

[0193] - used to obtain NH 4 Evaporator (12) for aqueous suspension of Cl,

[0194] - a circulation pump (13),

[0195] - a heat exchanger (14),

[0196] - used to transfer NH 4 The suspension of Cl (17) is passed into the separation zone,

[0197] - a separation zone comprising

[0198] - one or more for obtaining crystalline NH 4 Cl separation device, and

[0199] - one or more inlet devices (23) for feeding the crystallization additive.

[0200] Preferably, the chemical production unit additionally comprises

[0201] - a droplet separation device (6), preferably a demister,

[0202] - Used to extract NH 4 A pump (16) for a portion of the aqueous suspension of Cl,

[0203] - a drying device (21),

[0204] - a container (20) for collecting the mother liquor, and

[0205] - means for passing the mother liquor (24) into the reaction zone.

[0206] The crystallization zone preferably comprises one or more crystallization loops, more preferably one to three or one to two crystallization loops, and these crystallization loops are more preferably arranged in parallel.

[0207] Figure 1 A schematic diagram of a preferred embodiment of the process of the invention is shown, which comprises a reaction stage, a crystallization stage and a separation stage.

[0208] The reaction zone of the reaction stage includes a reaction loop including a reaction system for feeding NH 3 (1), a mixing device (4) into which HCl (2) is fed, a device for phase separation (5), a droplet separation device (6), a circulation pump (7) and a heat exchanger (8) which is operated with steam (9) during the start-up phase and from which any condensate can be collected separately.

[0209] The crystallization zone of the crystallization stage comprises a crystallization loop, which comprises an evaporator (10), a circulation pump (13) and a heat exchanger (14). 4 The reaction vapors (11) obtained in the device for phase separation (5) are fed to the heat exchangers of the crystallization loop and the crystallization zone, respectively. Any condensate leaving the heat exchanger can be collected separately.

[0210] Contains NH 4The aqueous suspension of Cl (17) is partly removed via a pump (16) to feed the separation zone. The crystallization vapor (15) obtained in the evaporator (10) is discharged, for example for further use or for collection as condensate.

[0211] The separation zone of the separation stage comprises a hydrocyclone (18), a centrifuge (19) and a drying device (21), wherein both the hydrocyclone and the centrifuge are connected to a container (20) for collecting the mother liquor, in which the crystalline ammonium chloride (22) is obtained as the final product. The mother liquor (24) is passed into the reaction loop.

[0212] Furthermore, crystallization additives can be added at various locations (see, for example, (23)).

[0213] In the case of two parallel crystallization loops, the vapor stream (9) and NH 4 The aqueous Cl solution stream (10) is each divided into two equal streams.

[0214] Reference Symbols List

[0215] 1 NH 3

[0216] 2 HCl

[0217] 3 For feeding NH 3 Entrance device

[0218] 4 Mixing device

[0219] 5 Apparatus for phase separation

[0220] 6 Droplet separation device

[0221] 7.13 Circulation pump

[0222] 8.14 Heat exchanger

[0223] 9 Steam

[0224] 10 NH 4 Cl aqueous solution

[0225] 11 Reaction vapor

[0226] 12 Evaporator

[0227] 15 Crystallization Vapor

[0228] 16 Pumps

[0229] 17 NH 4 Aqueous suspension of Cl

[0230] 18 Hydrocyclone

[0231] 19 Centrifuge

[0232] 20 Container for mother solution

[0233] 21 Drying device

[0234] 22 Crystalline NH 4 Cl

[0235] 23 Crystallization Additives

[0236] 24 Mother liquor

[0237] The process of the invention offers economic advantages as well as environmental advantages.

[0238] The process of the present invention provides crystalline ammonium chloride in a substantially quantitative yield, for example in a very high yield of ≥ 99% or more based on the amount of HCl.

[0239] The inventive method allows a heat-integrated process. Crystallized ammonium chloride can be obtained by a two-stage production process, wherein the reaction stage and the crystallization stage are separated, but energetically associated. This allows a substantially autothermal process, wherein the energy produced in the reaction stage provides the necessary energy and the energy for evaporation during the crystallization stage, respectively. The input of the energy produced by the reaction enthalpy of the neutralization reaction in step a) is sufficient to fully evaporate the water introduced with aqueous HCl. Therefore, the reaction enthalpy can be used to form reaction vapors and to form crystallization vapors, and it can be used for other processes requiring heat, such as further evaporation.

[0240] Since the neutralization reaction is separated from the energy removal by forming water vapor within the reaction stage, a substantially NH-free 4 Cl, HCl, and NH 3 of reaction vapor.

[0241] The entrainment of small amounts of ammonia, hydrochloric acid and ammonium chloride in the offgases of the reaction and crystallization stages results in minimal losses of starting materials and ammonium chloride via the wastewater. Due to the process of the reaction step and the additional purification of the reaction and crystallization vapors, a condensate of high purity (i.e., generally with low conductivity) is obtained and can be used for further processes. Thus, any NH 3 , HCl and NH 4 Cl emissions are minimized.

[0242] In NH 3 The application of a slight overpressure during the reaction with HCl avoids the coexistence of gaseous ammonia and steam, which reduces the loss of ammonia via the gas phase. Therefore, the loss of ammonia and ammonium chloride via the exhaust gas is also minimal.

[0243] Furthermore, the process according to the invention enables the preparation of crystalline ammonium chloride in a reliable manner with minimal disruption caused by possible salt deposits.

[0244] The process of the present invention provides ammonium chloride in crystalline form with high purity. In particular, the process can be used to control the crystallization of ammonium chloride.

[0245] Compared to ammonium chloride crystals characterized by a dendritic structure in the absence of a crystallization additive and as described in the prior art, the ammonium chloride crystals exhibit a favorable morphology, in particular a more spherical shape, under the action of the crystallization additive.

[0246] The crystallized product has a uniform crystal structure with a low specific surface area, which has the advantage that the crystals can be easily, substantially completely and quickly dried. In addition, the crystallized product shows less agglomeration.

[0247] The crystalline product has a narrow crystal size distribution, wherein the narrow crystal size distribution generally has a favorable effect on product parameters such as free-flowing properties, hygroscopicity, bulk density, and the like.

[0248] The crystalline ammonium chloride obtained is generally a free-flowing powder which remains a free-flowing powder after storage for several months, for example up to a year or even longer.

[0249] All percentages, ppm or similar values ​​refer to weight relative to the total weight of the corresponding basis, unless otherwise indicated.The terms "% by weight" and "wt%" are used synonymously herein.

[0250] The following examples shall further illustrate the present invention without limiting the scope of the present invention.

[0251] Examples

[0252] Phase 1: NH 3 Reaction with HCl

[0253] The reaction of ammonia with hydrochloric acid is carried out in a reaction loop comprising a phase separator, a circulation pump, a tube bundle heat exchanger, an ejector (jet pump) and a static mixer. An aqueous ammonium chloride solution (about 40 wt %) is circulated by a pump at a temperature of 95° C. to 105° C. 3 In the case of a circulation volume of 1000 t / h, the required amount of gaseous ammonia is dissolved into the reaction loop via a jet pump.

[0254] Subsequently, hydrochloric acid (37wt%, 0.99 equivalent relative to the amount of ammonia) was added to the reaction mixture while maintaining a pressure of 2 bar using a static mixer. Upon entering the phase separator, the neutralization reaction was complete. Ammonia and hydrochloric acid were dosed in the reaction loop so that a small amount of excess ammonia (about 1mol%) was always added. The temperature of the solution in the static mixer was increased from about 98°C to 106°C. The reaction solution was dosed to the phase separator via a throttle valve to prevent boiling during the actual reaction. After the valve, the reaction solution was boiled by decompression (about 620 mbar), where phase separation occurred as NH 4 Cl aqueous solution (cooled to about 100 ° C) and steam.

[0255] Water evaporates from the reaction solution in the phase separator, wherein the temperature of the reaction solution decreases accordingly in the phase separator. The amount of water evaporated during the reaction is such that at 100° C. the NH 4 The concentration of the Cl solution is about 40 wt%. Any solution is removed from the vapor via an aerosol separator and a droplet separator. The vapor is then transferred to a heat exchanger for the subsequent crystallization stage.

[0256] The reaction solution is passed from the phase separator to the suction side of the circulation pump and is sent to the ammonia ejector to close the loop. On the suction side of the circulation pump, the ammonium chloride mother liquor from the separation stage is added.

[0257] When starting up the chemical production unit, a heat exchanger installed between the circulation pump and the ammonia ejector is used to heat the reaction mixture to an operating temperature of about 100° C. with 2 bar steam.

[0258] On the pressure side of the pump, part of the reaction solution is continuously removed from the reaction loop and fed to two crystallization stages for further evaporation.

[0259] Process Stage 2: Crystallization

[0260] The crystallization and evaporation of the ammonium chloride solution are carried out in two parallel circulation evaporators. Only one circulation evaporator is described below.

[0261] The crystallization circuit comprises a circulation pump, a tube bundle heat exchanger and an evaporator. Crystallization and evaporation are carried out at a temperature of about 55° C. and a pressure of 110 mbar with a high circulation volume. First, the circulation volume is conveyed from the pump to a heat exchanger, which is operated with a portion of the vapors from the reaction stage. The solution is heated by about 1° C. to 2° C. in the heat exchanger. In the case of formation of condensate, this can be discharged in a separate container.

[0262] Before the heated solution is fed into the evaporator, the reaction solution of stage 1 is dosed into a crystallization loop. Water is evaporated from the solution in the evaporator, resulting in crystallization of ammonium chloride, wherein a suspension of ammonium chloride (about 20 wt %) is moved. After the solution is separated therefrom by a droplet separator, the vapors produced by the evaporation are condensed. The vacuum required for the evaporation is generated with a liquid ring compressor.

[0263] Between the evaporator and the circulation pump, part of the ammonium chloride suspension is continuously removed and fed to the separation stage. Predissolved crystallization aids can be dosed into the crystallization loop.

[0264] Process Stage 3: Separation

[0265] The discharge from the two evaporators is first passed into several hydrocyclones to separate into a thick lower stream and an upper stream with a lower solids content. The combined upper stream is fed into a mother liquor container. The combined thick lower stream is directed to a pusher centrifuge. Crystallization additives can also be dosed before the pusher centrifuge.

[0266] The moist ammonium chloride separated as the centrifuge is dried. The saturated ammonium chloride solution separated as the centrifuge liquid can be discharged into an ammonium chloride mother liquor container. The mother liquor is pumped into the reaction loop.

[0267] The dried ammonium chloride was sieved to remove lumps and stored in bags. The product was obtained as a flowable powder in >99% yield.

[0268] Figure 2 Shown is a micrograph of the product obtained by the example in which 50 ppm by weight of pectin was used, added to an aqueous ammonium chloride solution in the crystallization loop.

[0269] Based on the analysis of the total organic carbon (TOC) of the mother liquor, it was determined that 75% of the added pectin was attached to the final product. TOC was determined according to DIN EN 1484:2019-04.

Claims

1. A method for producing crystalline ammonium chloride in the presence of a crystallization additive, the method comprising the steps of: a) reacting NH3 with HCl by feeding NH3 and HCl into an aqueous NH4Cl solution; b) crystallizing ammonium chloride from the aqueous NH4Cl solution obtained in step a), and c) separating the crystalline ammonium chloride, The energy required in step b) is generated in step a).

2. The method according to claim 1, wherein: The aqueous NH4Cl solution of step a) is passed through a reaction loop which preferably comprises a circulation pump, a mixing device and a vessel for phase separation.

3. The method according to claim 1 or 2, wherein: NH3 was fed as a gas, and HCl was fed as an aqueous solution with a concentration of 20 wt% to 38 wt%.

4. The method according to claim 1, 2 or 3, wherein: In step a), the concentration of the NH4Cl aqueous solution is 30 wt% to 45 wt%.

5. A method according to any one of the preceding claims, wherein: The molar ratio of HCl:NH3 is 0.95:1.05 to 1.05:0.

95.

6. A method according to any one of the preceding claims, wherein: Step a) is carried out at a pressure of 0.1 to 3 bar and a temperature of 50 to 130°C.

7. A method according to any one of the preceding claims, wherein: The energy required in step b) is generated in step a) by the heat of reaction of the reaction of NH 3 with HCl, which is released in the form of reaction vapors.

8. A method according to any one of the preceding claims, wherein: Step a) comprises a-1) a step of reacting NH3 with HCl, and a-2) a step of generating reaction vapor, The steps described therein are performed individually.

9. A method according to any one of the preceding claims, wherein: The reaction vapors are generated by reducing the pressure.

10. A method according to any one of the preceding claims, wherein: The reaction vapors were purified.

11. A method according to any one of the preceding claims, wherein: A portion of the aqueous NH4Cl solution obtained in step a) is fed to step b).

12. A method according to any one of the preceding claims, wherein: The crystallization in step b) is carried out by means of one or more evaporation-crystallization loops, which are preferably arranged in parallel.

13. A method according to any one of the preceding claims, wherein: The crystalline ammonium chloride is separated in one or more separation stages, preferably by centrifugation.

14. A method according to any one of the preceding claims, wherein: The mother liquor obtained in step c) is recycled to step a).

15. A method according to any one of the preceding claims, wherein: The crystallization additive is added in step b) and / or step c).

16. A method according to any one of the preceding claims, wherein: The amount of the crystallization additive is 0.1 to 1000 ppm by weight based on the total weight of the crystallized ammonium chloride.

17. A method according to any one of the preceding claims, wherein: The crystalline additive is a polysaccharide, a derivative thereof or any combination thereof.

18. A method according to any one of the preceding claims, wherein: The crystalline additive is selected from heteropolysaccharides, derivatives thereof, cellulose, derivatives thereof, and any combination thereof.

19. A method according to any one of the preceding claims, wherein: The crystallization additive is a heteropolysaccharide having COOH groups, a derivative thereof, a heteropolysaccharide having OSO3 groups, preferably a heteropolysaccharide based on galacturonic acid, mannuronic acid, guluronic acid, glucuronic acid or a derivative thereof, cellulose, or cellulose ether.

20. A method according to any one of the preceding claims, wherein: The crystalline additive is selected from the group consisting of alginic acid (E 400), sodium alginate (E 401), potassium alginate (E 402), ammonium alginate (E 403), calcium alginate (E404), propylene glycol alginate (E 405), carrageenan (E 407), tragacanth gum (E 413), gum arabic (E 414), xanthan gum (E 415), karaya gum (E 416), gellan gum (E 418), ghatti gum (E419), pectin (E 440i), amidated pectin (E 440ii), cellulose (E 460), methylcellulose (E 461), ethylcellulose (E 462), hydroxypropyl cellulose (E 463), hydroxypropyl methylcellulose (E 464), ethyl methylcellulose (E 465), carboxymethyl cellulose (E 466). 466), cross-linked sodium carboxymethylcellulose (E 468), enzymatically hydrolyzed carboxymethylcellulose (E 469) and any combination thereof.

21. A method according to any one of the preceding claims, wherein: The crystalline ammonium chloride is surface-modified by the crystallization additive.

22. A method according to any one of the preceding claims, wherein: The crystalline ammonium chloride has a median diameter d of 50 μm to 1 mm. 50 .

23. A surface-modified crystalline ammonium chloride obtainable or obtained by a process according to any one of claims 1 to 21.

24. Use of crystalline ammonium chloride obtainable or obtained by the process according to any one of claims 1 to 22 as a flavoring agent, as an animal feed additive, as an additive for a cosmetic composition or as an additive for a pharmaceutical composition.

25. A method of applying crystalline ammonium chloride obtainable or obtained by the method according to any one of claims 1 to 22 as a flavoring agent to food or as an additive to animal feed, cosmetic compositions or pharmaceutical compositions.

26. A chemical production unit for carrying out the method according to any one of claims 1 to 22, the chemical production unit comprising - a reaction zone comprising - inlet means for feeding NH3 into the reaction zone, - inlet means for feeding HCl into the reaction zone, - a mixing device, - a device for phase separation for obtaining an aqueous NH4Cl solution and reaction vapors, - circulation pump, - heat exchangers, - means for passing the aqueous NH4Cl solution into a crystallization zone, - means for passing the reaction vapors into the crystallization zone, - a crystalline region comprising - inlet means for feeding the aqueous NH4Cl solution into the crystallization zone, - an evaporator for obtaining an aqueous suspension containing NH4Cl, - circulation pump, - heat exchangers, - a device for passing the NH4Cl-containing suspension into a separation zone, - a separation zone comprising - one or more separation units for obtaining crystalline NH4Cl, and - Inlet device for feeding crystallization additives.

27. The chemical production unit according to claim 26, additionally comprising - droplet separation device, - a pump for extracting a portion of the aqueous suspension containing NH4Cl, - drying device, - a container for collecting the mother liquor, and - means for passing the mother liquor into the reaction zone.

Images