WO2000011329A1

WO2000011329A1 - Method and apparatus for purifying water solutions of glycol-based substances

Info

Publication number: WO2000011329A1
Application number: PCT/DK1999/000438
Authority: WO
Inventors: René Emil JENSEN
Original assignee: United Sensitives Marketing In; Jensen Rene Emil
Priority date: 1998-08-20
Filing date: 1999-08-16
Publication date: 2000-03-02
Also published as: AU5153799A

Abstract

The invention relates to a method and an apparatus for purification of water solutions of coolants and similar glycol-based substances such as di- or polyvalent alcohols e.g. from internal combustion engines making it possible to collect and purify the coolant for the purpose of recycling as the apparatus contains a preliminary chemical treatment with sodium diethyldithiocarbamate and a polyquarternary ammonium compound in its hydroxide form, means of filtration comprising an initial filtration apparatus for particle filtration of the preliminary treated coolant by using two or more serially arranged filters with decreasing pore size and a second filtration apparatus for filtration of the filtered coolant for removal of pollutants dissolved in the particle filtrated coolant and pumps for circulation of the substance through the preliminary treatment and the filtration processes. In this manner, it is possible to carry out a simple and efficient recycling process purifying used coolants within a relatively short period of time since the process is carried out by making one single circulation and at great speed since recirculation is superfluous.

Description

METHOD AND APPARATUS FOR PURIFYING WATER SOLUTIONS OF

GLYCOL-BASED SUBSTANCES

The present invention relates to a method and an apparatus for purification of water solutions of coolants and similar glycol-based substances such as di- or polyvalent alcohols in connection with e.g. an internal combustion engine where polluted water solutions are collected and purified with the purpose of recycling.

Water solutions of di- or polyvalent alcohols, also called glycols, are used today for heat transfer in many types of heat exchange systems including both stationary and mobile installations, such as air conditioning installations, cooling systems for vehicles, cooling systems for cold store, power plants etc. Water solutions of glycols consisting of a mix of water and glycol are commonly known as coolants. When the coolant is circulated in the heat exchange system, it eventually becomes polluted and the inhibitors etc. are decomposed and the coolant will thereby loose its heat exchange and corrosion protection abilities which is the reason why it must be replaced at certain intervals.

Today, several processes for purifying used coolants are known and they usually comprise combinations of chemical purifying and filtration techniques. The purpose of these techniques is to remove all heavy metals and other corrosion and decomposition products so that the coolant may be reused. An example of a system for purification of coolants can be found in EP-A1-0 530 630. Other systems for purification of coolants may be found in US-A-5, 651,895, US-A-5,645,730, US-A- 5,474,684 and US-A-4,946,595.

These systems are characterized in that a salient chemical treatment is carried out of the collected used coolant and the liquid is then subsequently filtrated by passing it around in the closed system a number of times.

CONΠRMAΠON COPY In practice, it turns out that these known and relatively complex systems are not as efficient as could be desired and that they are consequently insufficient for commercial use. The attraction, and thus the commercial use of such systems, is that the purification of the coolant must be available in garages in connection with check- ups or repairs of vehicles or as an integrated part of a heat exchange systems which may be found in cold store, air conditioning installations, large and small power plants etc. In addition, the existing purification systems for recycling of coolants are quite time-consuming since an acceptable purification result may only be obtained after extensive recirculation in the processing system which is quite time-consuming and thus quite expensive. Furthermore, the existing systems designed to purify water solutions of glycols, incl. coolants, are characterized by a large consumption of chemicals to adjust the pH value of the liquid during the purification process, among other things. This adds to the fact that the complexity and the costs associated with the recycling process are unacceptably high.

Based on this, the purpose of the invention is to create a simplified and more efficient method of purifying water solutions of coolants and similar glycol-based substances for recycling and an associated recycling apparatus thereto.

The invention comprises a method of the initially mentioned kind during which the water solution undergoes a preliminary chemical treatment of the collected substance in order to develop particles of dissolved metals that may be filtered, an initial filtration of the preliminary treated substance carried out through one or more serially arranged filters with decreasing pore size followed by a second filtration of the filtered substance for removal of pollutants that have decomposed in the particle- filtrated substance.

In this manner, it is possible to create a simple and efficient purification process capable of conducting a simple circulation for cleansing of coolants over a relatively short period of time which makes the process time-saving as recirculation becomes superfluous. The invention also features an apparatus for purification of water solutions of coolants and similar glycol-based substances in connection with e.g. an internal combustion engine that is capable of collecting and purifying a polluted water solution for recycling purposes, according to the invention, as the apparatus features means for a preliminary chemical process of the collected coolant, means of filtering comprising an initial filtering apparatus for filtration of particles of the preliminary purified substance by using one or more serially arranged filters with decreasing pore size and a second filtering apparatus for filtration of the filtered substance while also featuring pumps handling the circulation of the substance through the preliminary and the subsequent filtration processes.

In this manner, the apparatus for performance of the purification process is easy to use and set up "on site", e.g. in or in connection with a garage, according to the invention. The apparatus can be advantageous when installed between a collection tank of used coolants and a storage tank for recycled/new coolants.

The purification apparatus for performance of the purification process may be applied to both mobile and stationary systems, incl. large heat exchange systems for e.g. industrial purposes, according to the invention. Thus, in accordance with the invention, it is realized that the method for purification of coolants and the associated apparatus can be used by internal combustion engines for cars, busses, trucks etc. and may also be used for heat exchange systems such as air conditioning installations, radiator systems for heating of cabins etc., thermal floors in cool houses where the refrigeration is transported away from the base. Apart from this, it has been recognized that the purification system, according to the invention, may also be used for purification of water solutions of glycols that are used as a defrosters for air planes etc. When defrosting an air plane, relatively large amounts of defrosting substances containing glycols are used and in order to spare the environment it could be collected with the purpose of being recycled and purified after having been polluted by dust, dirt etc. during use and the subsequent collection. According to the invention, the purification system may also be used to purify substances containing glycols that have not been used within a closed system and are consequently expected to contain various kinds of polluting particles. In the preferred embodiment of the invention, the chemical preliminary process comprises an initial purification process of the collected substances with a precipitant for the development of insoluble metalliferous particles and subsequent purification with a coagulating basic compound for coagulation of the developed metalliferous particles in the coolant. The precipitant preferably consists of sodium diethyldithiocarbamate or sodium dimethyldithiocarbamate. In that manner, it is possible to create a simple and efficient precipitation and subsequently filter particles of polluting materials such as heavy metals etc. during additional filtration processes. A preferred coagulating basic compound for the development of clusters of metalliferous particles suitable for filtration is a polyquartemium ammonium compound in its hydroxide form.

In the preferred embodiment of the invention, the initial filtration comprises three filters decreasing in pore size. In this manner, it is possible to carry out a good filtration of particles with a minimum of energy used just as the particle filtration is quick since the flow resistance in the individual filters during circulation of the coolant may be reduced through the use of more filters and since filtration may take place over several steps. If large capacity is required of the recycling system, it is naturally possible to use several parallelly arranged series of filters.

In the preferred embodiment of the invention, the initial filter removes particles in excess of 75 μm while the second filter removes particles in excess of 10 μm and the third in excess of lμm. In this way, the initial filtration process is particularly suited for a quick and efficient purification of the used coolant once it has undergone a preliminary chemical treatment.

The second filtration, according to the embodiment of the invention, comprises two spodium filters for removal of oil, dye, acid decomposition products and other compounds. In this manner, it is possible to create a simple and environmentally friendly removal of these liquid pollutants. Once a carbon filter reaches saturation, the filter is easily emptied for carbon and subsequently refilled with new carbon. After having been exposed to a pyrolytic process, the used carbon may be reused and will thus not constitute a burden on the environment as would have been the case if alternatively disposed of.

According to the embodiment of the invention, the process system features a one- way valve between each of the filters so that backwashing of the filters is prevented which means that the purification process may be carried out with only little pressure resulting in reduced consumption of energy.

According to the embodiment of the invention, additives such as corrosion inhibitors, buffers and bases are added to the coolant subsequent to the second filtration so that the purified coolant is ready for reuse. This "package of additives" may either be added prior to the filtration process or at a later point, e.g. in relation to the storage of the recycled coolant in a tank or in a similar situation.

The apparatus, according to a preferred embodiment of the invention, is compact and installed in a mobile installation and transportable frame. This makes it easy to move it around in e.g. a garage among the vehicles on which it is to be used.

The water solutions of coolants that can be subjected to a purification according to the invention with the purpose of recycling the coolant could be glycol based water solutions and/or water solutions with corrosion protective inhibitors.

The invention is described in detail with reference to the drawings in the following where

Fig. 1 shows a process diagram of a recycling process of used coolants according to the invention and Fig. 2 shows a schematic side projection of a apparatus for recycling of coolants according to the invention.

Figure 1 is a schematic illustration of how the recycling process takes place according to the invention. Used coolant is supplied from a collecting tank (not shown) to the system by a bulk feeder 1 that leads the used polluted coolant through a pipeline and into a container 4 by the opening of a valve 2. Additives 3 are then added in the container and the used coolant is exposed to preliminary treatment. The container 4 also features a stirring device. The used coolant is thus treated in the container 4 with sodium diethyldithiocarmabmate in order to make the dissolved metals in the polluted coolant form insoluble particles. The precipitant does not bind the metal ions chemically but attracts the metal ions and captures them in "insoluble" clusters of metal ions in the substance. Next, the coolant is purified with a water solution containing a sufficient amount of coagulating basic compound, such as a polyquartemium ammonium compound in its hydroxide form so that the metalliferous particles form larger particles which are more suitable for filtration.

A mechanical prefilter 4a has been placed next to the discharge pipe from the container 4. The preliminary treated used coolant is pumped from the container 4 through the prefilter 4a and through an open faucet/valve 5 by a pump 6 and onwards to the first filtration apparatus 9-11.

The initial filtration apparatus consists of three serially connected filters 9-11. In connection with each of the filters, a valve 7 and a manometer 8 for monitoring of the filtration process are placed immediately before the filter. The filters 9-11 of the filter apparatus have different pore sizes and have been arranged in such a manner that the pore size is decreasing. According to a preferred embodiment of the invention, the first filter 9 removes particles in excess of e.g. 75 μ, the second filter 10 in excess of 10 μm and the third filter 11 removes particles in excess of 1 μm. The three filters may be Purtex PX75-20", Purtex PX10-20" and Hytrex II GX01-20" respectively and all three filters are of the cartridge filter type. However, when dealing with larger systems it may be advantageous to use other filters with a larger capacity such as filter bags, centrifugal filters etc.

Subsequent to the removal of metalliferous and other particles from the coolant by the first filter, the particle-filtrated coolant is lead through a counter valve 12 to the second filtration means 13,14. The second filtration apparatus features two spodium filters 13 and 14 that are serially connected. In this manner, soluble pollutants such as oil, dye, acid decomposition products and other compounds are removed from the coolant so that a relatively clear and purified substance will emerge.

Oil and other liquid pollutants are deposited in the carbon filters 13 and 14 on the surface of the carbon. Once the carbon is saturated and the effect of the filters 13 or 14 is reduced, the carbon may easily be replaced. The used carbon can be purified by exposing it to a pyrolytic process burning at a temperature preferably just below the combustion temperature of the carbons so that they may be reused several times in the filters 13 and 14.

The purified coolant is then lead through a counter valve 15 to a cartridge filter 16, preferably of the same type as the third filter 11 in the particle filtration, in order to remove particles that have been rinsed out with the spodium filters 13 and 14.

The purified coolant is lead to a container 18 through a valve 17 where an "additive package" 19 consisting of corrosion inhibitors, buffers and bases and potentially also a defroster are added preventing the coolant from freezing after which the purified used coolant is treated and reused as an efficient coolant that can be lead to a storage or transport tank (not shown).

Figure 2 represents a schematic, possible embodiment of the apparatus for performance of a method, according to the invention. The three cartridge filters in the initial filter apparatus 9-11 and the two spodium filters 13 and 14 and the additional cartridge filter 16 have been arranged successively in the upper part of the installation box 22 which is placed in a frame 21 that has been provided with a fixed set of wheels at the at the back and one or more revolvable wheels in the front. On top, the frame 21 features a handle 25 so that the user can easily move the frame as a semitrailer. As has been illustrated in figure 2, the pump 6 is situated at the bottom of the box 22. The above mentioned example of an embodiment has been described for purification of coolants for e.g. vehicles. However, it should be pointed out that the purification system, according to the embodiment of the system, may also be used for purification of other kinds of water solutions of glycols. According to the invention, the system may also be used for purification of glycol-based substances used for many other purposes, incl. substances used as heat exchange substances in heat exchange systems.

Claims

Patent Claims

1. A method for purification of water solutions of coolants and similar glycol-based substances, such as di- or polyvalent alcohols e.g. from an internal combustion engine where the polluted coolant is collected and recycled with the purpose of reuse, characterized in that the water solution is subject to

a preliminary chemical treatment of the collected substance for development of particles of dissolved metals to be filtered and then - an initial filtration of the preliminary treated substance through one or more serially arranged filters with decreasing pore sizes and a second filtration of the filtered substance for removal of pollutants that have dissolved in the particle-filtrated substance.

2. A method in accordance with claim 1 where the preliminary chemical treatment comprise an initial purification process of the collected substance with a precipitant for the development of insoluble metalliferous particles and a subsequent purification with a coagulating basic compound for coagulation of the developed metalliferous particles in the substance.

3. Method in accordance with claim 2 where the precipitant is sodium diethyldithiocarmbamate.

4. Method in accordance with claims 2 or 3 where the coagulating basic compound is a polyquartemium ammonium compound in its hydroxide form.

5. Method according to claims 1 to 5, where the initial filtration comprise three filters with decreasing pore size.

6. Method according to claim 5 where the initial filter removes all particles in excess of 75 ╬╝m, the second filter all particles in excess of 10 ╬╝m and the third filter all particles in excess of 1 ╬╝m.

7. Method in accordance with claims 1 to 6 where the second filtration comprise two carbon filters for removal of oil, dye, acid decomposition products and other compounds.

8. Method in accordance with claims 1 to 7 where additives containing corrosion inhibitors, buffers and bases are added to the purified substance subsequent to the second filtration.

9. An apparatus for purification of water solutions of coolants and similar glycol- based substances such as di- or polyvalent alcohols e.g. from an internal combustion engine for the performance of a method in accordance with any of the previous claims and in which polluted water solutions may be collected and purified with the purpose of reuse, characterized in that the apparatus comprises

- means for a preliminary chemical treatment filtration means comprising an initial filtration apparatus for particle filtration of the preliminary treated substance by the use of two or more serially arranged filters with decreasing pore size and - a second filtration apparatus for filtration of the filtered substance for removal of pollutants that have been dissolved in the substance, and a pumping means for transport of the substance through the preliminary treatment and the filtration processes.

10. An apparatus in accordance with claim 9 where the means for preliminary chemical treatment comprise an initial treatment unit for purification of the collected substance with a precipitant for the development of insoluble metalliferous particles and a second treatment unit for adding a coagulating basic compound for coagulation of the developed metalliferous particles in the substance.

1 1. An apparatus in accordance with claim 10 where the precipitant is sodium diethyldithiocarbamate.

12. An apparatus in accordance with claim 10 or 11 where the coagulating basic compound is a polyquartemium ammonium compound in its hydroxide form.

13. An apparatus in accordance with claims 9 to 12 where the initial filtration apparatus comprises three filters with decreasing pore size.

14. An apparatus in accordance with claims 9 to 13 where the second filtration apparatus comprises one or more preferably spodium filters (carbon filters) for removal of oil, dye, acid decomposition products and other compounds.

15. An apparatus in accordance with claims 9 to 14 where the filtration means also feature a third filtration device.

16. An apparatus in accordance with claims 9 to 15 where a one-way valve has been placed between each filtration apparatus.

17. An apparatus in accordance with claims 9 to 16 where additives, such as corrosion inhibitors, buffers and bases, are added to the purified substance in an additive unit subsequent to the filtration means.

18. An apparatus in accordance with claims 9 to 17 where the apparatus is compactly designed and installed in a mobile mounting and transportation frame.