System, method and process for disinfection of internal surfaces in aseptic tanks and pipelines by flooding with sanitizing fog

Abstract

System, method and process for disinfection of internal surfaces in aseptic tanks and pipelines by flooding with sanitizing fog in facilities designed to store liquids in general, such system comprising an external equipment with means to generate sanitizing fog, controlling means of gases flow rate, in-line detectors and draining means of gases inside the tank, input means of fog carrying means comprising inert gases. Disinfection process comprises introduction of a sanitizing fog with droplets with a maximum size of 10 m, preferably with maximum size of 5 m, simultaneously with removal of gases enclosed inside such tanks and pipelines, maintaining a positive pressure inside such tanks and pipelines, such method providing reduction of oxygen concentration inside the tanks in two steps, the first one comprising reduction to near 10% and the second a reduction to a value below 1%, filling the tank with a sanitizing fog during the second step.

Claims

1. A method for disinfection of internal surfaces of at least one of an aseptic tank and a pipeline configured to store and transport liquids, the method comprising: flooding the at least one of the aseptic tank and the pipeline with an inert gas and a sanitizing fog, the flooding causing oxygen present in the tank to rise to the upper portion of the tank; detecting the concentration of oxygen in the tank; removing the oxygen from the at least one of the aseptic tank and the pipeline through a duct and into the atmosphere; and closing the duct when the detected concentration of oxygen in the tank is less than a predetermined amount.

2. The method of claim 1, wherein the sanitizing fog comprises droplets having a maximum size of 10 m.

3. The method of claim 1, wherein the sanitizing fog comprises droplets having a maximum size of 5 m.

4. The method of claim 1, wherein the sanitizing fog comprises a peracetic acid solution.

5. The method of claim 4, wherein the peracetic acid solution has a concertation ranging from 500 to 3000 ppm.

6. The method of claim 1, wherein the predetermined amount of the concentration of oxygen is less than 1%.

7. The method of claim 1, wherein the sanitizing fog is produced by oscillation of piezoelectric transducers driven by an ultrasonic oscillator circuit.

8. The method of claim 7, wherein the method further comprises: reducing a content of oxygen inside the tank to less than 10% before the flooding.

9. A method for disinfection of internal surfaces of at least one of an aseptic tank and a pipeline configured to store and transport liquids, the method comprising: generating a sanitizing fog; flooding the at least one of an aseptic tank and a pipeline with an inert gas and the generated sanitizing fog, the flooding causing oxygen present in the tank to rise to the upper portion of the tank; and measuring a concentration of oxygen in the at least one of the aseptic tank and the pipeline; removing the oxygen from the at least one of the aseptic tank and the pipeline through a duct and into the atmosphere until a predetermined concentration of the oxygen is reached.

10. The method of claim 9, wherein the flooding is simultaneous with the removal of the oxygen, the oxygen being removed using a centrifugal fan whose output discharges to the atmosphere.

11. The method of claim 9, wherein the sanitizing fog comprises droplets having a maximum size of 10 m.

12. The method of claim 9, wherein the sanitizing fog comprises droplets having a maximum size of 5 m.

13. The method of claim 9, wherein the sanitizing fog comprises a peracetic acid solution.

14. The method of claim 9, wherein the peracetic acid solution has a concertation ranging from 500 to 3000 ppm.

15. The method of claim 9, wherein the inert gas is nitrogen.

16. The method of claim 9, wherein the sanitizing fog is produced by oscillation of piezoelectric transducers driven by an ultrasonic oscillator circuit.

17. The method of claim 9, wherein the predetermined concentration of oxygen is less than 1%.

Description

DESCRIPTION OF DRAWINGS

(1) Other advantages and features of the invention will become more evident from the description of a preferred embodiment, given as a non-limiting example, and from accompanying drawings where:

(2) FIG. 1 shows the equipment that produces the fog of sanitizing solution, according to the invention.

(3) FIG. 2 illustrates the use of the invention when flooding an aseptic storage tank with sanitizing fog and gas.

DETAILED DESCRIPTION OF INVENTION

(4) As already mentioned herein, the flooding procedure is the final step of cleaning and disinfection process of NFC juices aseptic tanks. The system of the present invention eliminate the need to perform said flooding with a liquid sanitizing solution, therefore saving time, chemical products, water, energy and reduction of effluents.

(5) In the known flooding procedure, i.e., using a sanitizing solution in liquid state, an iodoform solution must be transferred to NFC juice aseptic tank with pumps. Said sanitizing solution enters the aseptic tank by means of a bottom valve 52 situated in base of aseptic tank 50 (see FIG. 2). As soon as the sanitizing solution begins to fill the tank, the atmospheric air within is expelled by a relief valve 46 situated on top of the aseptic tank. The cost of providing a iodoform solution for a 6 million liters aseptic tank is about US$ 120,000.00. The time to fill the whole aseptic tank and expel all atmospheric air is from 2 to 4 days and will depend on flow rate of the pump used to transfer the solution.

(6) Once the aseptic tank is completely filled with sanitizing solution and confirmation that there is no longer any atmospheric air inside, the procedure to empty the tank is initiated. To maintain internal pressure of tank, nitrogen is injected by valve 43 situated on top of tank, as shown in FIG. 2.

(7) Due to its high cost, such solution must be transferred to another tank, in order to not waste it, as it can be reused in up to 1 year. Thus, 1 aseptic tank is lost to store NFC juice. The emptying procedure of aseptic tank also lasts from 2 to 4 days. Once the tank is emptied, there is a sterile tank and able to receive NFC juice.

(8) The inventive concept now proposed consists of generating a fog of sanitizing solution with a carrying gas, to insure that substitution of gases inside the aseptic tank (atmospheric air by nitrogen) is performed in a sterilized manner, avoiding, thus, contamination of aseptic tank in this procedure step. In case of NFC juices, an inert gas is used as carrying means, being that, in alternative embodiments, such carrying means can be air itself.

(9) The fog of sanitizing solution has the same features of sanitizing solution in liquid state. In fact, it is the same solution. The difference is that it works with a droplet size of, approximately, 5 microns, which increases the contact surface area of sanitizer solution. Thus, the same three-dimensional space can be occupied, reaching 100% of its internal surfaces, using only a small amount of the solution that would be necessary if a solution in liquid state were used.

(10) Referring now to FIG. 1, the invention comprises an external equipment housed into a cabinet 10, which is provided with casters 35 that make it movable near several equipments (tanks and pipelines). Inside this cabinet there is the nebulization box 11, made of stainless steel 304/316 able to resist internal pressures up to 10 bar. Such nebulization box has a pressure relief valve 16 regulated to open with 6 Bar.

(11) Such box 11 is where the liquid solution becomes a fog. The bottom of this box is provided with piezoelectric elements 12, whose number depends on desired volume of fog production. Such plates must be made of stainless steel or material resistant to corrosive solutions.

(12) The level control of sanitizing solution 32 is essential to a proper operation of the system, since fog production can be impaired in case the column of solution above the plates' surfaces 12 exceeds 50 mm. Such control is made by a group of components that include detector 19, peristaltic pump 21, drainage system 25 of nebulization tank, reservoir of sanitizer solution 22 and a supplying conduit of solution 20. Information from detector 19 indicates if the level of sanitizer solution is below or above ideal value; in first case, peristaltic pump 21 is driven sending solution included in reservoir 22 to the box 11, through conduit 20. In the second case, drainage system 25 is driven in order to remove part of solution included in nebulization box.

(13) The piezoelectric transducers are driven by electronic circuits that generate an ultrasonic signal in the order of hundreds of kHz to some MHz, wherein the size of fog drop produced is related to such frequency.

(14) The nebulization box is provided, further, with deflectors 37 that work to condensate large drops generated in procedure.

(15) The gaseous carrying means, in case nitrogen, is introduced in box 11 through input 28, wherein the function of such means is to draw the fog produced inside the nebulization box out of the equipment.

(16) Depending on use of the system, atmospheric air itself can also be used as carrying means, instead of inert gases, or even compressed air.

(17) In case of application in aseptic tanks it is necessary to insure the quality of carrying means. Thus, before going inside nebulization box, the carrying means, more specifically nitrogen, passes by a filter 15 comprising a stainless steel housing and a microbiological cartridge of known type.

(18) In operations carrying means is provided by an external piping 13, a pressure relief valve 16 must be provided installed on top portion of nebulization box as a safety measure, since a very high pressure can cause excessive pressurization inside the box 11.

(19) The fog produced is carried to the output pipeline 14, which is provided by an in-line detector 41 to monitor gas flow rate. Sanitizing fog is launched inside pipelines and tanks by hoses attached to equipment output; quantity and quality of produced fog can be monitored by glass monitor window 17 allowing visual inspection.

(20) At one side of equipment control a panel 18 is installed, wherein elements for electrical protection are found (switches, relays, etc.), as well as controllers to perform equipment operation manually or automatically. Depending on the application, said control panel can be provided with CLPs, timers, delayers or other controllers, in accordance with application.

(21) The equipment is provided with a centrifugal fan 24, used in several steps of the inventive method, whose operation, described later, is controlled by an electronic inverter module of variable frequency 23 headed by control panel 18.

(22) Several maneuver valves 27, 30 and 31 are part of the equipment that are driven during different steps of sanitization process of tank, as will be described herein below.

(23) The method used in invention, which is detailed below, refers to a process of gaseous flooding of an aseptic tank, designed to store NFC orange juice, with capacity up to 6.000.000 liters. FIG. 2 describes interconnections of such aseptic tank with the equipment that generates such sanitizing fog, shown in FIG. 1. The aseptic tank is placed inside a cold chamber with controlled temperature of 1 C., which is not shown in the drawings.

(24) The gaseous flood process includes two stages, the first one consisting of substitution, even partially, of atmospheric air, which contains oxygen, by nitrogen, inside the tank. The second stage includes application of sanitizing fog.

(25) The main steps of the first stage are as follow: a. after the end of CIP process, wait at least 4 hours in order to complete the liquid runoff from internal walls of tank 50, which is collected in bottom and drained through opening 51 and correspondent valve 52, illustrated in FIG. 2; b. place the equipment 10 near tank 50 and make the following attachments, with all valves closed: connect a hose 42 between bottom valve 36 of tank and the viewer 17 of output 14 from such equipment; connect nitrogen source 13 to flange 39, keeping all valves closed 27, 30 and 31 of equipment 10 as well as valve 13a from nitrogen piping; interconnect by means of a hose 49 the inspection flange 34 on top of tank 50 and an air input 26 associated to centrifugal fan 24 in equipment 10, the output of such fan discharging at atmosphere through output 33, out of cold chamber; connect to exterior of cold chamber the pressure relief valve output 16 by means of a hose; put the sanitizing solution reservoir 22 next to equipment 10 and place the end of suction hose of peristaltic pump 21 inside this reservoir; c. check the proper installation of in-line detectors 40 (oxygen), 41 (gases flow rate) and 47 (hydrogen peroxide); d. install microbiological cartridge in filter 15; e. connect control panel 18; peristaltic pump 21 is driven automatically, transferring a portion of sanitizing solution from reservoir 22 to nebulization box 11, until reaching the correct level indicated by level detector 19; f. after opening the bottom valve 36, slowly open input valve of nitrogen 30, as well as valve 13a, monitoring pressure inside the tank with detector 44; g. using frequency inverter command in control panel 18, drive centrifugal fan 24, setting the frequency (and, therefore, the fan flow rate) in order that volume exhausted through output 33 to exterior is approximately equal to volume of injected nitrogen. By performing this adjustment, data from detector 44 must be controlled, in order to assure a positive pressure value in tank, avoiding that such pressure becomes negative.

(26) At this point, nitrogen is entering into equipment 10 through valve 30, passing by filter 15 and, after going through nebulization box 11, leaves by output duct 14 and viewer 17 to hose 42 which introduces the gas in tank 50 through valve 36. Inside the tank the nitrogen pushes oxygen to the upper portion of tank, from where is suctioned by centrifugal fan 24 through inspection flange 34 and duct 49 and released to atmosphere through discharge opening 33. During such period, oxygen detector 40 is monitored; initially, such detector should show a value near to 20.6%, corresponding to the oxygen concentration in atmospheric air. As time goes by, this concentration must fall, due to introduction of nitrogen in tank. Upon reaching a value of approximately 10%, the second stage of procedure is initiated, described as follows: by setting frequency inverter, reduce in approximate 50% flow rate in centrifugal fan 24; in control panel 18, turn on the nebulization system (fog) to energize piezoelectric transducers 12 to produce sanitizing fog inside nebulization box 11;

(27) The nitrogen flow introduced in input 28 will carry with it such fog, which must be checked in a visible manner by viewer 17. Such fog, forwarded by pipeline 42 and bottom valve 36, enters the tank, occupying gradually its whole interior.

(28) The purpose of this stage consists of filling the complete volume of tank with sanitizing fog and nitrogen. During such operation, the sanitizing solution inside nebulization box 11 will be consumed. The level detector 19 sends an electrical signal to control panel in order to drive the peristaltic pump 21, which will transfer more sanitizing solution from reservoir 22 to interior of nebulization box 11 to maintain the proper level of solution.

(29) After some hours, it will be possible observe part of sanitizing fog exiting to the atmosphere through exhaustion duct 33 of equipment 10. At this point, there will be possible to measure concentration of sanitizer through detector of hydrogen peroxide 47. During such step the concentration of oxygen continues to be monitored by detector 40 and also the internal pressure of tank through pressure detector 44, because there exists a trend to a gradual increase of internal pressure of the tank.

(30) This stage lasts approximately 8 hours, considering that it is stopped when concentration of oxygen falls below 1% and the concentration of peracetic acid is within the limit determined by quality control department of the company.

(31) Once the predetermined values of concentration of oxygen and peracetic acid are reached, the second stage of operation is ended: ultrasonic plates 12 are deactivated; the valve 30 of nitrogen input is closed; inspection flange 34 on top of tank is substituted by a closing flange; valve 31 is closed; the bottom valve 36 is closed and hose 42 is disconnected.

(32) From this point, the tank is totally closed, but not necessarily in desired pressure. Leaving the valve 29 open, the pressure is automatically controlled by the system through opening and closing of valve 43, in order to introduce necessary amount of nitrogen to reach the ideal pressure. The tank, now, is in conditions to be supplied with NFC juice.

(33) Although the flooding method has been described based on the oxygen removal from a fixed tank, designed to store orange juice, it is understood that principles of invention are applicable to disinfection of movable tanks, such as those used in road transportation using trucks, railways using wagons and maritime using ships.

(34) Furthermore, as mentioned before, sanitizing fog can be used at CIP step, more specifically at step of disinfection/sanitization of tanks and pipelines, which is performed after cleaning respective surfaces using caustic soda and acid. In comparison to known methods, in which sanitizing solution is applied by means of pumps, spray ball, rotating spray or scan jet, use of sanitizing fog presents the advantage of reaching all internal surfaces of tank and associated pipelines, besides substantial economy of water and product used as disinfectant.

(35) In general lines, the disinfection/sanitization process includes some of the steps related to the second step of gaseous flood process previously detailed. Notice that, however, as a significant difference, the fact that, in disinfection/sanitization, the carrying means is not necessarily nitrogen, but may be a gas or mixture of gases (such as atmospheric or compressed air).

(36) Considering that carrying means is atmospheric air, such disinfection will comprise, therefore, the following steps: i. after the end of cleaning process (caustic soda-rinse-acid-rinse), wait at least 4 hours in order to complete liquid runoff from tank's internal walls 50, which is collected in bottom and drained through opening 51 and correspondent valve 52, illustrated in FIG. 2; ii. place the equipment 10 near to tank 50 and connect a hose 42 between bottom valve 36 of tank and viewer 17 of output 14 of such equipment; iii. put the sanitizing solution reservoir 22 next to equipment 10 and place the end of suction hose of peristaltic pump 21 inside this reservoir; iv. connect control panel 18; peristaltic pump 21 is driven automatically, transferring a portion of sanitizing solution from reservoir 22 to nebulization box 11, until reaching the correct level indicated by level detector 19; v. in control panel 18, turn on the nebulization system (fog) to energize piezoelectric transducers 12 to produce sanitizing fog inside nebulization box 11; vi. connect centrifugal fan 24 and set the frequency inverter 23 to initiate drag of sanitizer fog.

(37) Regarding the step of disinfection of CIP process there are 2 ways of proceeding: 1Without looping: in this case atmospheric air must go into the equipment 10 through input 26, pass by centrifugal fan 24, pass by filter 15, enter the box 11 and leave by duct 14. In this case air inside of the tank will not be removed (through valve 34 and duct 49), but only an injection of sanitizing fog in tank or pipeline. The valves 30 and 31 remain closed, being opened the valve 27. 2With looping: refers to looping the fog inside the tank or net of pipeline. In this case, output 34 of tank is connected to input 26 by the duct 49. Therewith, by centrifugal fan 24, fog solution loops inside the tank. The valve 27 remains opened and valves 30 and 31 closed.

(38) Once concluded disinfection/sanitization of tank and associated pipelines, the sequence of process will depend on the nature of stored product, as well as carrying means of sanitizing fog. Thus, in case the air was used as carrying means and the product is a NFC vegetable juice, oxygen removal process will be necessary in accordance with flood procedure already mentioned before.

(39) When stored product is not affected by oxygen, it is possible to proceed immediately to tank's filling, it being not necessary, in this case, to proceed with gaseous flood procedure.

(40) Accordingly, the invention is defined and bounded by the set of the following claims.