FI119731B - A method for regenerating aqueous liquids containing trimethylglycine and glycol - Google Patents

Description

A method for regenerating aqueous liquids containing trimethylglycine and glycol Förfarande för regenerering av vattcnhaltiga, trimethylglycine and glycol innehällande vätskor 5

Engineering

The present invention relates to a process for the regeneration of aqueous heat transfer, cooling, de-icing and de-icing fluids containing trimethylglycine for re-use of trimethylglycine. The process removes impurities from the aqueous heat transfer, cooling, de-icing, and de-icing fluids used, particles removed from the equipment, and glycol typically derived from conventional glycol-based heat transfer and cooling fluids.

15

State of the art

Trimethylglycine or betaine-based heat transfer, cooling, de-icing and de-icing fluids contain trimethylglycine as anhydrate or monohydrate 20 or trimethylglycine salts such as hydrochloride or trimethylglycine derivatives such as dimethylglycine. Trimethylglycine monohydrate is the most commonly used compound. Trimethylglycine can be prepared, for example, synthetically or by extraction from natural sources such as sugar).

25

The concentration of trimethylglycine in heat transfer, cooling, de-icing and de-icing liquids typically ranges from 1 to 60% by weight and the water content from 40 to 99% by weight. In addition, the fluids may contain auxiliaries, depending on the application, for example corrosion inhibitors.

Used trimethylglycine-based functional fluids such as ice rink coolants, building technology applications heat transfer fluids, aircraft and runway de-icing and de-icing fluids, and automotive coolants are generally discarded. The trimethylglycine-based fluids used typically contain various impurities, metal particles removed from the equipment such as iron, manganese, magnesium, aluminum, chromium and nickel particles and other solid particles, as well as glycol from propylene glycol and propylene glycols from liquids previously used in the equipment, . When the fluids contain environmentally harmful additives and / or residues such as ethylene glycol, used fluids must be disposed of as hazardous waste.

10 The goal of environmentally sustainable development is to minimize the burden on the environment. Thus, the disposal of heat transfer and cooling fluids to introduce them into, for example, wastewater is undesirable.

EP 1177208 discloses a method for crystallizing trimethylglycine from supernatant aqueous solutions.

In view of the foregoing, there is an obvious need for a method for regenerating coolants for functional fluids containing Irimethyl-lysine, such as various coolants, heat transfer fluids for building applications, aircraft de-icing and de-icing fluids and engines such as car engines.

Objective of the Invention 25

The object of the invention is a process for the regeneration of aqueous solutions containing trimethylglycine for reuse of trimethylglycine.

3

It is also an object of the invention to recover dry trimethylglycine from used aqueous solutions containing trimethylglycine for re-use of trimethylglycine.

Another object of the invention is a trimethylglycine recycling system.

5

Characteristic features of the method and recycling system of the invention are set forth in the claims.

Summary of the Invention 10

The present invention relates to a process for the regeneration of aqueous liquids containing trimethylglycine and glycol, which comprises filtration to remove solids and color contained in the liquid, and a) spray drying and optional fluidized drying, or b) nanofiltration and optional evaporation.

Patterning

The invention is illustrated in the accompanying Figures 1 and 2, however, which are not intended to limit the embodiments shown.

Fig. 1 illustrates a process according to the invention wherein the aqueous aqueous liquid containing trimethylglycine is introduced in stream 1 to a filtration step 10, which separates particles having a particle size in the range of 0.1 to 50 µm. This removes debris, metal particles, iron-bound compounds, and pigments that cause color. After filtration, the filtrate is fed in a stream 2 to a spray dryer 20, which is also supplied with a warm drying gas in stream 3. The dry kiln gas, preferably air, is recycled in stream 4 through cyclone 30 to separate solid trimethylglycine particles to heater 40 and back to spray dryer 20. on the basis, a powdered trimethylglycine is recovered, which is combined with the trimethylglycine particles 4 separated from the cyclone 30 in a stream 7. The recovered trinethylglycine is optionally fed in a stream 5 to a fluidized bed dryer 50 where the remaining water is evaporated and the remaining glycol residues are removed. The product provides powdered trimethylglycine in stream 6, which can be reused as such for the preparation of heat transfer fluids and cooling fluids.

Figure 2 illustrates another embodiment of the invention, wherein the aqueous aqueous liquid containing trimethylglycine is introduced in stream 1 to a filtration step 10, which separates particles having a particle size in the range of 0.1 to 50 µm. This removes debris, metal particles, iron-bound compounds and pigments that cause color. After filtration 10, the filtrate is conducted as stream 2 and water as stream 4 and optionally recycled water as stream 3 to membrane filter 20 to provide trimethylglycine-containing concentrate in stream 6 and glycol and water-containing filtrate 7. Trimethylglycine-containing concentrate in stream 6 and water as stream 5 stream 11 to another membrane filter 30 to obtain a trimethylglycine-containing concentrate stream 8 and a glycol-water filtrate 9. The resulting trimethylglycine-containing concentrate stream 8 may be used as such in heat transfer or coolant solution, to achieve the desired working solution concentration.

DETAILED DESCRIPTION OF THE INVENTION It has surprisingly been found that used and intended for disposal trimethylglycine-based functional fluids, such as ice rink coolants, heat transfer fluids for building technology applications, airborne and runway de-icing and thawing liquids, recover for reuse using the method of the invention.

As used herein, trimethylglycine refers to trimethylglycine anhydrate and monohydrate, trimethylglycine salts such as hydrochloride and trimethylglycine derivatives such as dimethylglycine and mixtures thereof. Trimethylglycine monohydrate is the most commonly used compound.

5

The trimethylglycine-based and aqueous functional fluid used in the process of the invention, such as ice rink coolant, heat transfer fluid for building technology applications, de-icing and thawing of airplanes and runways, optionally fluidizing; or b) subjecting the filtrate to nanofiltration and optional evaporation.

The aqueous solution of tri-15 methylglycine used in the first embodiment of the process of the invention, for example a heat transfer solution, is first filtered with one or more filters having a pore size in the range of 0.1 to 50 µm, preferably 0.5 to 20 µm. Then, according to step a) of the process, the filtrate is fed into a spray dryer where it is sprayed into the hot gas chamber by spray drying technology into small droplets of less than 100 µm, whereupon the impurity components are obtained from the solution by efficient transfer.

The drying gas may be air or nitrogen, preferably air. If the system has a closed circuit, nitrogen is used. The temperature of the drying gas is 160-280 ° C, preferably 25,190-240 ° C. Spray dryers known in the art can be used as spray dryers. During spray drying, the filtrate evaporates water and some glycols, and the product is crystallized dry trimethylglycine powder.

The drying gas can either be recycled from the spray dryer through a cyclone and heater back to the dryer, or it can be recycled directly to the gas-30 scrubber unit, which operates by conventional spray technology. The temperature of the air leaving the spray drier 6 is typically 95-160 ° C and the temperature of the dry trimethylglycine powder obtained is 50-80 ° C.

The solution is sprayed with a rotating disk nozzle or pneumatic largest to obtain an effective droplet and transfer surface 5. With a pneumatic nozzle, the feed is preferably dripped by hot air, whereby the evaporation of the glycol from the spray is enhanced. Preferably, the rotary disk nozzle dissolves the solution at 25,000 rpm around the circumference of the rotating disk into small droplets whose volatile components can be further enhanced by the transfer of hot gas to the disk. It is also known to use pressure nozzles as nozzles.

After spray drying, the trimethylglycine powder is optionally fed to a fluidized bed dryer at a temperature of 60-120 ° C, preferably 70-100 ° C, where the glycol remaining in the trimethyl-15 glycine is separated by fluidization in air. The Glyc content of trimethylglycine after fluidized-bed drying is not more than 0.2% by weight, and the trimethylglycine thus obtained is suitable as such for use in the manufacture of heat transfer, cooling and anti-icing fluids.

In an alternative embodiment of the method, the trimethylglycine-based and aqueous liquid used is first filtered as one or more filters having a pore size in the range 0.1 to 50 µm, preferably 0.5 to 20 µm. Then, according to step b) of the process, the filtrate is directed to a membrane separation step in which water, preferably deionized water or demineralized water produced by membrane separation or distillation processes and / or recycled water added to the process is added so that the concentration of trimethylglycine , preferably 3-5% by weight, and then the diluted solution is directed to a membrane separator where water and water-impurities and glycols are removed from the solution so that the concentration of trimethylglycine in the effluent concentrate is in the range of 10-20% by weight, preferably 10- 15% by weight.

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An embodiment of the membrane separation regeneration process is based on the use of semipermeable and selective membrane material for the separation of trimethylglycine from water and glycols. Reverse osmosis or; nanofiltration membranes with a differential pressure of 5 membranes acting as the driving force for the separation. In nanofiltration, trimethylglycine is concentrated to 10-15% by weight to a concentration of 2000-4000 kPa (abs.) And a temperature of 20-50 ° C. Nanofiltration membranes have a larger pore size than inverse osmosis membranes, typically 10-100 nm, whereby the membranes retard components of more than 200-1000 daltons. (Dalton is a unit of measure used for the film industry in proportion to its molecular weight for film 10). Due to the larger pore size, nanofiltration can use a lower pressure difference across the membrane, saving energy. Trimethylglycine has a molecular weight of 117 g / inol, but nevertheless nanofiltration can be utilized if the membrane charged with trimethylglycine charged in aqueous solution is selected as the separation film. Preferably, negatively charged nanofiltration membranes are used, whereby separation can be performed at a pressure level lower than reverse osmosis. Reverse osmosis membranes typically have a pore size of 1-10 nm, whereby components of more than 10-100 Daltons are retained, respectively.

The film separation process of the invention utilizes one or more successive nanofiltration steps, preferably two nanofiltration steps, whereby 80 to 90% of the glycol is removed and the glycol content of the purified trimethylglycine solution is between 0.1 and 0.3% by weight and the trimethylglycine is 90 95%. In the nanofiltration step, the temperature is in the range of 15-50 ° C, preferably 20-40 ° C, and the operating pressure is 1500-8000 kPa (abs.), Preferably 2000-4000 kPa (abs.).

At each membrane separation step, the solution to be regenerated is first diluted with water, preferably deionized water, or demineralized water produced by membrane separation methods or distillation to a desired concentration to reduce the osmotic pressure of trimethylglycine and to dissolve the impurities in water. After this t δ, the solution thus obtained is directed to a film unit in which water and water are dissolved; glycol is permeable to the membrane and trimethylglycine is retained by the membrane. Theoretically, the solution can be concentrated with respect to trimethylglycine to a level where the osmotic pressure difference of the solution is equal to the operating pressure. In practice, however, the economic concentration 5 is significantly lower than this. After the membrane separation steps, the reconstituted trimethylglycine solution may optionally be concentrated to the desired working solution concentration either by evaporating excess water or by adding pure trimethylglycine to the solution.

The process of the invention has several advantages. The method allows the separation of pure trimethylglycine in powder form or reconstituted trimethylglycine solution from spent heat transfer and coolant liquids for reuse. In addition, impurities and glycol residues in trimethylglycine crystals can be effectively removed. The thus obtained recycled aqueous solution containing trimethylglycine or tri-15-methylglycine can be reused, for example, for the production of heat transfer fluids and coolants.

In the spray drying embodiment of the process according to the invention, the product is obtained directly in solid form which can be made into the aqueous solutions required for various applications. When a gas scrubber is combined with spray drying, glycols and other environmentally harmful compounds can be separated.

In the embodiment of the process of the invention utilizing membrane separation, advantages in terms of process safety are achieved, since the process is free of flame or explosive gases and no risk of dust explosion.

The method of the invention enables controlled and economical recovery of removable components and efficient recovery of purified product from a closed spray system system as a dry powder.

30 9

The trimethylglycine obtained by the process is suitable as such for reuse in functional fluids such as ice rink coolants, heat transfer fluids for building technology applications, de-icing and thawing fluids for airplanes and runways, and coolants for engines such as car engines 5 and the like. In this way, valuable trimethylglycine can be recycled and utilized as a raw material and the environmental load reduced; while supporting sustainable development. In addition, significant raw material savings in fluid production are achieved.

The invention is illustrated by the following examples, which, however, are not to be construed as limiting.

Examples 15 Example 1 Filtration of spent trimethylglycine-containing cooling solution to remove solids and color

The heat transfer fluid used in the ice rink for 5 years containing 49.5 wt% water, 46 wt% trimethylglycine, 4 wt% ethylene glycol and solid impurities was used as a test solution. The solution was fed to a 0.5 µm filter, whereupon the iron-brown solid was efficiently filtered from the dark brown feed so that the filtrate was clear and light brown in color with trimethylglycine.

25 30 10

Example 2

Regeneration of trimethylglycine aqueous solution by spray drying 49.5% by weight of water, 46% by weight of trimethylglycine, 4% by weight of ethylene glycol and solid-5 impurities, used in an ice rink for 5 years, was fed to a spray dryer. The solution was fed to a spray dryer and air at 230 ° C was used as the dry gas. The product gave a trimethylglycine powder having a water content of 0.5 wt% and a glycol content of 1.5 wt%. The powder was then passed to a lithium-bed dryer having a drying air temperature of 70 ° C. The product obtained was trimethylglycine powder having a glycol content less than 0.5 wt%.

Example 3

Film separation of trimethylglycine and ethylene glycol from aqueous solution The difference between trimethylglycine and ethylene glycol was investigated on DSS Labstak M20 equipment using four commercially available reverse osmosis and nanofiltration membranes.

The apparatus was subjected to a concentration run with a stock solution containing 5% by weight of trimethylglycine and 0.3% by weight of ethylene glycol in water. The test solution was made with a conductivity of <2 pS / cm in water. The concentration run was accomplished by returning the equipment concentrate back to the feed tank and draining the equipment permeate from the test system. During the test, the temperature was 25 ° C and the operating pressure was raised from a starting weight of 20 barg to a final pressure of 36 barg. The pressure of the penneate was normal atmospheric pressure. During the experiment, the concentration of the feed tank was monitored by measuring the dry matter content on a refractometer. The amount of permeate flux was monitored during the experimental run and permeate and feed were sampled at different pressure levels. Table 1 shows the retention calculated on samples of concentrate 23 barg and 36 barg on the membranes used with an ROI of 99.5% salt retention (NaCl), R02 99.5% salt retention (NaCl), R03 99% salt retention (NaCl) and NFl 96% salt retention (MgSO4).

30 The retention R is calculated by the formula: i s i 11 (c) R = 1 - p- 100%

V cf J

where cp is the permeate concentration and c / feed concentration.

5 Table 1 Concentration experiments for centimethylglycine and ethylene glycol retention on three reverse osmosis membranes (RO) and one nanofiltration membrane (NF),

Film Trimethylglycine Retention,% Ethylene Glycol Retention,% 23 barg 36 barg 23 barg 36 barg ROI 99.1 983 6R5 "343 ~ R02" 953 "9/7" 5Ϊ3 343 R03 ~ 993 98.5 "56Ä 183" NF1 983 953 night ^ 22/7

As seen in Table 1, reverse osmosis membranes (RO1, R02, R03) retained trimethylglycine well but also significantly retained ethylene glycol. With a Na-10 filtration membrane, NFl, ethylene glycol is permeable to water and, at a higher pressure level, ethylene glycol can even be concentrated in the permeate.

Claims (9)

A process for the regeneration of aqueous liquids containing trimethylglycine and glycol, characterized in that the aqueous solution containing the trimethylglycine and glycol is filtered and the filtrate is a) spray-dried and optionally floated in a whale, or b) the filtrate is that the regenerated trimethylglycine contains less than 0.5 wt% glycol. 10 A method according to claim 1, characterized in that the aqueous solution containing trimethylglycine and glycol is a functional fluid such as ice rink coolant, heat transfer fluid for building technology applications, aircraft and runway de-icing and de-icing fluid, or engine coolant or mixture thereof. Method according to claim 1 or 2, characterized in that the aqueous solution is filtered in one or more filters having a pore size in the range of 0.1 to 50 µm, preferably 0.5 to 20 µm, and the filtrate is fed to a spray dryer, in which it is sprayed into a drying gas having a temperature of 160 to 280 ° C, preferably 190 to 240 ° C, the trimethylglycine powder obtained after spray drying is optionally fed to a fluid bed dryer at a temperature of 60 to 120 ° C, preferably 70 to 100 ° C. 25 Method according to one of Claims 1 to 3, characterized in that the drying gas in the spray dryer is air or nitrogen, preferably air. Process according to claim 1 or 2, characterized in that the aqueous solution is filtered as one or more filters having a pore size in the range of 0.1 to 50 µm, preferably 0.5 to 20 µm, and the filtrate is passed to a nanofiltration step in which the filtrate adding water and optionally the recycled water recovered in the process so that the solution is diluted to a 1-7% by weight concentration of trimethylglycine, preferably i 3-5% by weight, and the solution is passed to a nanofiltrate, whereby 5 the trimethylglycine content in the effluent solution is in the range of 10-20% by weight, preferably 10-15% by weight, and optionally the solution thus obtained is evaporated. A process according to any one of claims 1,2 or 5, characterized in that the process comprises one or more nanofiltration steps having a temperature in the range of 15-50 ° C, preferably 20-40 ° C and an operating pressure of 1500-8000 kPa (abs). .), preferably 2000 to 4000 kPa (abs.). Process according to one of Claims 1, 2, 5 or 6, characterized in that the water is deionized water or demineralized water produced by membrane separation processes or distillation. A process according to any one of claims 1, 2, 5, 6 or 7, characterized in that water is evaporated from the regenerated trimethylglycine solution or pure trimethylglycine is added to the trimethylglycine solution to achieve the desired working solution concentration. 9. A process for recycling used aqueous trimethylglycine and glycol containing aqueous liquids, characterized in that the aqueous trimethylglycine and glycol containing aqueous liquids are treated according to any one of claims 1-8 and the resulting trimethylglycine solution or trimethylglycine liquid is prepared from coolants, heat transfer fluids for building technology applications, anti-icing and de-icing fluids for aircraft and runways, or engine coolants. Piilentkrav