System for preventing scaling, removing hydrogen peroxide residues and recycling water in a septic filling systems of laminated carton containers

Abstract

Disclosed is a system for preventing scaling and deposit formation in a sterile air heat exchanger of a system for aseptic packaging within laminated carton packages, and a process for eliminating hydrogen peroxide residues in aseptic laminated carton packaging systems, characterized in that it comprises providing a supply of water for scrubbing sterile air that has the following properties: (a) maximum conductivity at 20 C. of 2.0 micromhos; and (b) a maximum silica content of 0.1 ppm.

Claims

1. An aseptic packaging system for laminated carton-containing containers adapted to remove residual hydrogen peroxide and to recycle sterile air washing water, comprising: a supply line to supply sterile air washing water having the following properties, a maximum conductivity at 20 C. of 2.0 micromhos, and a maximum silica content of 0.1 ppm; a scrubber for washing the sterile air, the scrubber configured to be fed with the sterile air washing water; an air-water separator to separate washing water coming from the scrubber, the separated water having a content of hydrogen peroxide; a collection tank for collecting the washing water having said content of hydrogen peroxide, at the outlet from the air-water separator; a chiller or heat exchanger, to maintain the water temperature at a suitable value for the operation of the packaging system, the chiller or heat exchanger being configured to receive water from the collection tank; a filter comprising as a filer medium activated carbon, green sand or mixtures thereof in any ratio for the removal of hydrogen peroxide, wherein the filter is configured to receive water from the chiller or heat exchanger; a tank for obtaining and collecting the fresh sterile air washing water; and a hydrogen peroxide water discharge line connected to the air-water separator and to the collection tank; wherein the supply line is from the tank to the scrubber for providing the sterile air washing water.

2. The system of claim 1 wherein the activated carbon is selected from activated vegetable or mineral carbon.

3. The system of claim 1 further comprising an ultraviolet light lamp connected downstream the filter for the removal of traces of hydrogen peroxide by an advanced oxidation process and sterilization of the sterile air washing water.

4. A process of removal of residual hydrogen peroxide and recycling sterile air washing water used in an aseptic packaging system for laminated carton-containing containers, wherein the process is a closed loop system comprising: a. providing a fresh sterile air washing water supply that exhibits the following properties: a maximum conductivity at 20 C. of 2.0 micromhos, and a maximum content of silica of 0.1 ppm; b. feeding the sterile air washing water to a scrubber, for washing the sterile air; c. collecting washing water having a content of hydrogen peroxide in a collection tank, at the outlet from an air-water separator coming from the scrubber of the air washing system; d. transferring said water to a chiller or heat exchanger, to maintain the water temperature at a suitable value for the operation of the packaging machine; e. contacting the water coming from the chiller or heat exchanger with a filter medium comprising activated carbon, green sand or mixtures thereof in any ratio for the removal of hydrogen peroxide; and f. obtaining and collecting the fresh sterile air washing water in tank.

5. The process of removal of residual hydrogen peroxide and recycling of sterile air washing water used in the aseptic packaging system for laminated carton-containing containers according to claim 4, wherein the water used in the closed loop system is selected from demineralized water, deionized water, osmosed water, water obtained by distillation processes including distilled water, bi-distilled water, tri-distilled water.

6. The removal of residual elimination of hydrogen peroxide and recycling of sterile air washing water used in the aseptic packaging system for laminated carton-containing containers according to claim 4, wherein the water has the following properties: a content of suspended solids of 0 ppm; and a pH at 20 C. from 5.0 to 7.0.

7. The process of removal of residual hydrogen peroxide and recycling of sterile air washing water used in the aseptic packaging system for laminated carton-containing containers according to claim 4, wherein the heat exchanger is a plates heat exchanger, tube and shell heat exchanger or air heat exchanger.

8. The process of removal of residual hydrogen peroxide and recycling of sterile air washing water used in the aseptic packaging system for laminated carton-containing containers according to claim 4, further comprising passing the washing water through an ultraviolet light lamp, for the removal of traces of hydrogen peroxide through an advanced oxidation process and sterilization of the sterile air washing water.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) To complement the description that is being made and in order to help a better understanding of the features of the invention, the present drawings are attached as an integral part of the description. In which, with an illustrative and non-limiting nature are representing the following:

(2) FIG. 1 shows a general diagram of the air washing system in packaging machines.

(3) FIG. 2 shows a series of views (a, b and c) of the exchanger, with scale formation in the sterile air heat exchanger.

(4) FIG. 3 shows two graphs of precipitation (a and b) of Calcium Carbonate compounds (Calcite and Aragonite) using mineral solubility simulation considering 50 ppm of total hardness in the water, present in the scrubber, as a function of pH and temperature.

(5) FIG. 4 shows two Graphs of precipitation (a and b) of compounds of Calcium Carbonate (Calcite and Argonite) using mineral solubility simulation considering 100 ppm of Total Hardness in the Scrubber water as a function of pH and temperature.

(6) FIG. 5 shows the Hydrogen Peroxide concentration graph in the closed loop system, at the laboratory level.

(7) FIG. 6 shows the Hydrogen Peroxide removal graph downstream a carbon and green sand filter, at the laboratory level.

(8) FIG. 7 shows a general diagram of the closed loop system reusing the spent water to wash again the sterile air.

(9) FIG. 8 shows the Image of the Hydrogen Peroxide removal mechanism in the filtration system.

DETAILED DESCRIPTION OF THE INVENTION

(10) Follows a detailed description of the present invention is given with reference to the figures.

(11) During the aseptic packaging process of the prior art, it is frequent to stop production in order to clean/remove the incrustations and scale/deposits that are formed inside the sterile air exchanger, this due to the decrease in pressure and temperature in the aseptic chamber, which in turn puts in risk the aseptic conditions for packaging.

(12) Referring to FIG. 1, it shows the washing of the air used in aseptic packaging machines of laminated carton containing containers the prior art, in said figure it is shown that the air is sent to a scrubber 17 whose purpose is to absolve the residual hydrogen peroxide present in the air, subsequently the water with hydrogen peroxide passes to an air-water separator 18.

(13) According to the prior art, the water is withdrawn from the separator and sent to a drain 15, and the air is sent to the air heater 16. In accordance with the present invention, it is provided a new loop for a Residual Hydrogen Peroxide Removal System and Recirculation of Water Used in Aseptic Laminated carton Packaging Systems, shown in FIG. 7. In one aspect of the invention, the water is no longer discharged to the drain, but the water is treated to remove hydrogen peroxide and is then recycled to the aseptic packaging system of the prior art.

(14) Said System for the Elimination of Residual Hydrogen Peroxide and Recirculation of Water Used in Aseptic Packaging Systems for containers containing Laminated carton, of the present invention, refers to the installation of a closed loop system consisting of: 1) A supply of demineralized, deionized, osmosed water, or obtained by distillation process with the following characteristics:

(15) TABLE-US-00001 Conductivity at 20 C. 2.0 micromhos maximum Suspended Solids 0 ppm maximum pH 20 C. 5.0 to 7.0 Silica 0.1 ppm maximum Appearance colorless transparent liquid Odor Odorless Said water supply is stored in a water tank 40. From said tank 40, the water is pumped to a scrubber 17 where water absorbs hydrogen peroxide. 2) Water collection tank(s) 31, with a content of hydrogen peroxide, at the outlet of the separator 18, in case there is not enough pressure to feed the chiller 34 and filtration system 37. 3) Water chiller or heat exchanger 34, at the outlet of said collection tank(s) 31. 4) Hydrogen peroxide filtration/removal system, whose tank can be made of stainless steel or polyethylene covered with fiberglass 37 using activated carbon of vegetable or mineral origin, green sand or a mixture of both, as a filter medium, in any proportion. Where the ratio of activated carbon and green sand depends on the content of hydrogen peroxide, water flow and speed of the packaging machine. 5) Ultraviolet lamp 38 for degradation of traces of residual hydrogen peroxide. 6) Pumps 32 and 41 and accessories for connection.

(16) According to the prior art, the salts that cause scale and deposits present in the sterile air exchanger 20 in an aseptic packaging system, come from entrainments from the water incorporated to the air stream in the air-water separator equipment 18, such entrainments pass in turn to an air heater 16 and later to a heat exchanger 20 which is required for conditioning the sterile air (at a temperature of 280 C. in start-up conditions and 70 C. in normal operating conditions) to be feed to the aseptic chamber 13 and thus ensuring the aseptic conditions required in the packaging process and avoid contamination of the product by microorganisms. Under this temperature conditions all the salts dissolved in the water will precipitate and will cause incrustations of retrograde solubility salts which highly insulate the transfer of heat, as well as the precipitation of the other salts in the form of deposits (chlorides, sulphates, sodium, Silica, etc.) due to dry conditions.

(17) According to the prior art, the water used for air washing has the following general specifications; Total Hardness from 50 to 100 ppm as CaCO.sub.3, Chlorides maximum 49 ppm as NaCl, Sulphates maximum 100 ppm as SO.sub.4, Maximum Copper 0.05 ppm as Cu, pH 7.0 to 8.5 and maximum conductivity of 625 micromhos.

(18) The water used for the washing of sterile air, (numeral 14, FIG. 1), according to the prior art usually comes from different aquifers such as well water, surface water, or treated water, maintaining a drinkable water quality for this use, using softeners to remove hardness.

(19) For example, the analysis of sampled well water from the Ecatepec area is shown in Table 1 below:

(20) TABLE-US-00002 TABLE 1 Chemical analysis of raw water and general specifications of the water at the scrubber inlet Water plant Reference Property Units (raw) values Total hardness ppm as CaCO.sub.3 300 50 to 100 Calcium hardness ppm as CaCO.sub.3 110 20 to 40 Magnesium hardness ppm as CaCO.sub.3 190 30 to 60 P Alkalinity ppm as CaCO.sub.3 0 M Alkalinity ppm as CaCO.sub.3 345 Chlorides ppm as NaCl 332 49 max Silica ppm as SiO.sub.2 86 pH 7.3 7 to 8.5 Conductivity Microohm 866 625 max Iron ppm as Fe 0.06 Sulphates ppm as SO.sub.4 42 100 max Cuper ppm as Cu 0.1 0.05 max

(21) The first salts to form incrustations are those with retrograde solubility and low heat transfer, causing problems in heat exchange equipment, the most common incrustations found in heat exchange equipment are:

(22) Calcium Carbonate, Calcium Sulfate, Calcium Phosphate, Silica and Magnesium Silicate.

(23) In general, water sources have temporary hardness (in the form of Carbonates), so by eliminating the Hardness content only Silica incrustations can be formed. However, at the temperature conditions of 280 C. will take place the precipitation of others salts, mainly Sodium Chloride, Sodium Carbonate, Sodium Sulphate, coprecipitating Silica, at the temperature conditions will precipitate and will get dirty the heat exchange equipment.

(24) Considering the reference values for Total Hardness from 50 to 100 ppm as CaCO.sub.3 and simulating the compounds that precipitate using the WaterCycleRx software from FRENCH CREEK SOFTWARE, INC., the following has been found:

(25) There will be precipitation of Calcium Carbonate in the form of Calcite and Aragonite, these compounds precipitate from a pH of 7.5 and 86 C. considering a Total Hardness of 50 ppm, and from a pH of 7.5 and 64 C. considering a Total Hardness of 100 ppm.

(26) This can be seen in graph a and b of FIG. 3, regarding a simulation of mineral solubility at 50 ppm of total hardness in water entering to the Scrubber, where the color code identifies the severity of the problem, showing the following indications according to the color plotted;

(27) Color code identifying the severity of the problem.

(28) Blue color means a safe range.

(29) Green means a slight potential problem if the condition changes slightly.

(30) Yellow color warns check measurement; a problem is near.

(31) Magenta color indicates a probable problem, take corrective action.

(32) Red color indicates a problem. Treatment or corrective action is required.

(33) In graph 4a and 4b mineral solubility simulation 100 ppm of total hardness in the water entering the Scrubber, where the color code identifies the severity of the problem, showing the following indications according to the color plotted;

(34) Color code identifying the severity of the problem.

(35) Blue color means a safe range.

(36) Green means a slight potential problem if the condition changes slightly.

(37) Yellow color warns check measurement; a problem is near.

(38) Magenta color indicates a probable problem, take corrective action.

(39) Red color indicates a problem. Treatment or corrective action is required.

(40) From the above, it can be deduced that any trace of hardness in the water used for the sterile air washing and this is dragged into the sterile air separator, will form calcium carbonate incrustations and the other salts will precipitate due to the effect of temperature.

(41) In accordance with the present invention, to prevent the formation of encrustations, demineralized, deionized, osmosed water is used, or else obtained by the distillation process (distilled water, bidistilled water, tri-distilled water) for washing sterile air with the following characteristics:

(42) TABLE-US-00003 Conductivity at 20 C. 2.0 micromhos maximum Silica 0.1 ppm maximum In addition, the water may have 0 ppm maximum Suspended Solids pH 20 C. 5.0 to 7.0

(43) The content of dissolved salts is minimal since the conductivity is an indirect form of the dissolved salts in the water, therefore, although these are entrained in the sterile air separator, the amount of deposit/scale that will be formed in the Sterile air heat exchanger will be minimal. Which results in minimizing stoppages for cleaning, thereby increasing the production of the aseptic packaging machine.

(44) According to the prior art, the consumption of water for sterile air washing varies depending on the container, as well as the characteristics and speed of each packaging machine, the average flow being from 5.0 to 22 liter/min, this water is discarded (numeral 15, FIG. 1) due to the residues of Hydrogen Peroxide resulting from the sterile air washing, being a high water consumption and cost if the number of packaging machines in operation are considered.

(45) If the drain water 15 from the prior art were to be reused without any treatment, the residual Hydrogen Peroxide would increase from 0 ppm to 11,500 ppm (equivalent to 11.5%) of residual Hydrogen Peroxide in 8 hours with At a flow of 8.5 liters/min, the reference value is a maximum of 1% residual Hydrogen Peroxide in the water at the outlet of the sterile air separator, such high concentrations of hydrogen peroxide would cause contamination of the aseptic chamber as well as contamination of the containers produced and food contained.

(46) According to the present invention, to recycle this water, the present invention removes the residual Hydrogen Peroxide. For this purpose, the following stages are carried out: (1) a stage of contact with activated carbon, green sand or a mixture of both in any proportion, and (2) a stage of contact with ultraviolet light.

(47) For the stage of contact with activated carbon, green sand or mixtures of both in any proportion, it is required a filtration equipment whose tank can be made of stainless steel or polyethylene covered with fiberglass 37 where the Hydrogen Peroxide molecule is broken into Oxygen and Water without adding an additional contaminant to the aseptic system.

(48) Filtration equipment 37 contains vegetable or mineral type activated carbon, green sand (commercially available) or a combination of both in any proportion.

(49) The mechanism for the removal of peroxide in the filtration system 37 with activated carbon and green sand is as follows:

(50) ##STR00001##

(51) Activated carbon (AC) has reducing characteristics so hydrogen peroxide will not be absorbed on it.

(52) The radicals OOH and OH combine to form H.sub.2O and O.sub.2.

(53) In the Green Arena, the reactions that take place are:

(54) ##STR00002##

(55) The contact time for the elimination of the residual Hydrogen Peroxide varies from 5 minutes to 30 minutes and will depend on the concentration of Peroxide to be removed, as well as the flow that passes through the filter 37 adjusting the filter media bed.

(56) Example 1: Water with a hydrogen peroxide content of 500 ppm was passed through a column containing activated carbon and green sand during a 95 minute run at the laboratory level. As a result, it was obtained the reduction of the residual Hydrogen Peroxide from 500 ppm to 4 ppm.

(57) Example 2: In an operational run in a packaging machine, the hydrogen peroxide content was decreased from 250 ppm to 0.02 ppm.

(58) Since an increase in the temperature of the water in the closed loop system takes place due to contact with the hot air and other areas of the packaging machine, according to the present invention it is installed a water cooling system, for example: a chiller, a heat exchanger 34 such as a plate heat exchanger, tube and shell heat exchanger or air heat exchanger to maintain the temperature at a suitable value for the operation of the machine, for example, between 15 and 25 C. The system of the present invention includes a bypass when cooling is not required, since the temperature of the water without cooling reaches values of 61 C. at the outlet of the scrubber 17.

(59) According to the present invention, for the elimination of traces of Hydrogen Peroxide, as well as ensuring sterile water, at least one ultraviolet light lamp 38 is optionally placed to carry out a process of decomposing the traces of hydrogen peroxide through an advanced oxidation process.

(60) The advanced oxidation process using Hydrogen Peroxide and ultraviolet light gives rise to the formation of hydroxyl radicals which are highly reactive, they attack and decompose organic matter and disinfect the water.

(61) The advanced oxidation mechanism for the decomposition of Hydrogen Peroxide is the following:

(62) ##STR00003##
In accordance with the present invention, the system for preventing scale and deposits in the sterile air heat exchanger 20 as well as for the elimination of residual hydrogen peroxide and recirculation of water used for air washing, in systems of Aseptic packaging 10 using laminated carton-containing containers constitutes a practical, economical and efficient alternative, increasing production by keeping the sterile air exchanger clean, avoiding unscheduled stoppages for cleaning and saving water for the first use.

(63) In another aspect of the invention there is provided a method for modernizing an existing food packaging plant. The method comprises the steps of: a. install a sterile air wash water supply tank that exhibits the following properties:

(64) TABLE-US-00004 Conductivity at 20 C. 2.0 micromhos maximum Silica 0.1 ppm maximum; b. installing a sterile air wash water supply line to a scrubber 17, to wash sterile air; c. installing a collection tank 31, to collect washing water with the presence of hydrogen peroxide at the outlet of an air-water separator 18 coming from the scrubber 17, of an air washing system 10; d. installing a line and means to transfer the water from tank 31 to a chiller or heat exchanger 34; e. installing a chiller or heat exchanger 34, at the outlet of the collection tank 31, to maintain the water temperature at a suitable value for the operation of the packaging machine; f. install a filter medium activated carbon, green sand or mixtures thereof, in any proportion, at the outlet of the chiller or heat exchanger 34, for the elimination of hydrogen peroxide; and g. Install a sterile air wash water supply tank 40.

(65) The sterile water cooler 34 is of the chiller type, plate heat exchanger, tube and shell heat exchanger or air heat exchanger.

(66) In addition, the activated carbon in the filter medium is selected from activated vegetable or mineral carbon.

(67) Optionally, between the filter media and the supply tank 40, an ultraviolet lamp 38 is installed, for the removal of traces of hydrogen peroxide by an advanced oxidation process and sterilization of the sterile air wash water.