RU2627899C1 - Method for liquids disinfection and heating, and device for its implementation - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: method of water disinfection and heating includes the effect of microwave energy on the processed water flow of a given size, passing through a rectangular waveguide at an angle to its wide wall. An aqueous solution of ionic silver is added to the flow based on its concentration in the treated water of 0.01-0.02 mg/l. Water is passed through a device including a microwave generator, a rectangular waveguide with flanges, a radiating transparent tube passing through it, the axis of which is at an angle to the wide wall of the waveguide, and an end matched absorbing load. The tube through which the flow is passed has an expanding shape. The width W has a maximum value of 0.66 of the waveguide wide wall size, the height h at the waveguide entrance is 0.06-0.15 of the wavelength, and the height H at the waveguide output is 0.18-0.47 of the wavelength and is set wide side to the direction of electromagnetic wave propagation.

EFFECT: decreased liquid disinfection temperature, increased efficiency of microwave energy absorption and productivity, reduced energy costs, accelerated process of microwave disinfection and water heating, a possibility of using of a lower dose of ionic silver.

2 cl, 3 dwg, 1 tbl

Description

The invention relates to a technology for disinfection and heating of water with microwave energy and can be used in food, medical, microbiological, pharmaceutical, as well as in the chemical industry.

Most effectively, the present invention can be used in the food industry for disinfection and heating of water, used, for example, in the preparation of juices and other food liquids.

The invention can also be used in the medical, microbiological and pharmaceutical industries for the disinfection of water used in the preparation of culture media, vaccines, serums and liquid drugs.

In addition, the invention may find application in the chemical and gold mining industries for heating water in technological processes.

Currently, the problem of the production of environmentally friendly food products, including drinking water, without the addition of preservatives and chemicals is one of the leading places in the world.

The relevance of disinfecting and heating water consumed by a person in everyday life is determined both by an increase in the number of adverse territories and factors, and by the use of various preservatives along with traditional methods of disinfecting water.

Of particular importance is disinfection and heating during the treatment of water intended for long-term storage.

Currently, there is a known method of exposure to heavy metals and, in particular, silver on microorganisms in order to destroy them (L.A. Kulsky. Silver water. Kiev: Naukova Dumka. 1977, 164 p.).

The death rate, for example, Escherichea coli with an initial concentration of 10 ⁴ CFU / ml at a dose of ionic silver of 1.0 mg / l, is 3 min; at a dose of 0.5 mg / l - 20 min; at a dose of 0.2 mg / l - 50 min, and for a dose of 0.05 mg / l it takes about 2 hours of contact for a complete bactericidal effect (L.A. Kulsky. Silver water. Kiev: Naukova Dumka. 1977. P. 20 -34).

The disadvantages of this method and its use include significant doses of ionic silver to reduce the time of exposure to microorganisms in water at rest.

Also known are methods and devices for disinfecting and heating water using microwave energy (VV Ignatov et al. Influence of electromagnetic fields of the microwave range on a bacterial cell. Publishing house of SSU. 1978, 80 pp.).

A known method and device in which the microwave field is applied to a bacterial suspension in a test tube placed in a rectangular waveguide (V.V. Ignatov et al. Influence of electromagnetic fields of a microwave range on a bacterial cell. Publishing house of SSU. 1978, p. 34-35). This type of device is referred to as a passage, waveguide, connected on one side to a microwave generator, and on the other, to an end-matched absorbing load. The tube in the device is placed at an angle of 45 ° to the wide wall of the waveguide.

In the proposed embodiment, the device is not used for disinfection and heating of water in the stream.

For example, a microwave apparatus for evaporating liquid mixtures is known, which includes a waveguide and a microwave generator. In this apparatus, the heated liquid is fed through a tube transparent to microwaves, the axis of which is located at an angle to the wide wall of the waveguide, so that the heated effluent is then fed into the chamber where the liquid is sprayed and evaporated. The resulting vapor is separated and condensed, and the non-evaporated liquid is mixed with the main stream and recycled (Roger M. Amadon. MICROWAVE APPARATUS FOR EVAPORATING LIQUID MIXTURES. U.S. Patent 3,495,648. Feb. 17.1970. U.S. Cl. 159-3).

The presence of the final water load in this device is confirmed by the fact that not all microwave energy is absorbed by the heated fluid, and therefore excluded from the heating process.

This microwave apparatus also offers two more options for arranging tubes that are transparent for microwaves in the waveguide, through which liquid is supplied to the chamber.

The first option is a series of tubes located at an angle to the wide wall of the waveguide, connected in series. In the second embodiment, the tubes are connected in parallel and have a common liquid inlet and outlet.

The disadvantage of both versions of the microwave device for heating and evaporating liquid mixtures is the complexity and cumbersomeness of the entire structure, which with a final water load represents considerable size and weight.

The complexity of the design is also expressed in the additional shielding of the tubes extending beyond the waveguide, from the penetration of radiation into the surrounding space.

This device for heating with microwave energy is used in the circulating technological scheme of the apparatus for evaporating and concentrating fruit juices and other heat-sensitive liquids by means of electromagnetic wave energy. The device is used for continuous heating in a stream of a portion of the liquid located in the evaporator, and act on it until complete evaporation. The result of repeated recycling at an elevated evaporation temperature is a significant loss of vitamins and the nutritional properties of liquids.

A known system for cleaning liquids, which use a device for heating and disinfecting the liquid to be cleaned with microwave energy (N. Colman Rosenberg. SYSTEM FOR PURIFYING LIQUIDS. U.S. Patent 4,013,558. Mar. 22. 1977. U.S. C1. 210-149). This device is an expanding waveguide (horn), at the end of which a corrugated tube is placed, laid round to round. Such a tube fills the open end of the waveguide and almost completely blocks its cross section. The fluid flow rate is kept constant, and the fluid temperature is monitored by temperature sensors at the inlet and outlet of the tube. The main disadvantage of the device for microwave heating is the incomplete disinfecting effect and the possibility of precipitation and its accumulation in the corrugations, as well as microorganisms. This entails an additional operation to periodically clean the tube.

In addition, the use of a waveguide with an open end (horn) requires protection of the entire device as a whole from radiation of microwave energy into the surrounding space. This increases the dimensions of the device and its weight.

The device is used in a flow-through technological scheme to improve the method of processing liquids during disinfection and clarification, which consists in mixing and maintaining the consistency of the flow at the proper level before and during microwave energy treatment. The result (99.9%) of sterilization is achieved at 65 ° C for vegetative forms of microorganisms.

Closest to the proposed technical solution is a device for disinfection and heating of aqueous media, including a microwave generator, a rectangular waveguide with flanges, a tube of radiolucent material located at an angle of 30-45 ° to the wide wall of the waveguide, an end coordinated absorbing load of a quasi-resonant type, this tube in cross section has a flat shape and is set wide side to the direction of propagation of the electromagnetic wave, has a height equal to 0.12-0.14 wavelengths, and a width equal to 0.26-0.45 times EPA broad wall of the waveguide (LL Zablocki, SI CLIMAR, AG Lobanov. Device for disinfection and heating aqueous medium. Copyright certificate the USSR №1139439. 15.02.1985, the IPC A61L 2/12). This flat-shaped tube has constant dimensions at the indicated boundary values.

The imperfection of the known device lies in the insufficiently high efficiency of absorption of microwave energy in this tube, which decreases with increasing temperature of the treated water, which leads to an increase in energy costs and lower productivity. Such a device is used in a circulation-flow technological scheme for disinfection and heating of aqueous media in a stream. The result (100%) of exposure to a set of vegetative forms of microorganisms is achieved at a temperature of 70 ° C.

The disadvantages of this device and its use are the increased temperature of water disinfection, reduced efficiency of absorption of microwave energy and performance, excessive energy consumption.

The technical result consists in accelerating the process, reducing energy consumption, the temperature of the microwave disinfection and heating of water, as well as the dose of ionic silver, increasing the efficiency of absorption of microwave energy.

The task in part, the method is solved by exposing microwave energy to a stream of treated water of a given size passing through a rectangular waveguide at an angle to its wide wall, and an aqueous solution of ionic silver is added to the stream of treated water based on its concentration in the treated water 0.01- 0.02 mg / l, the water flow has an expanding shape from the entrance to the waveguide to the exit from it, while the width of the stream W has a maximum value of 0.66 the size of the wide wall of the waveguide, and the height h at the entrance to the waveguide is 0.06-0 15 length waves and its height H at the exit from the waveguide is 0.18-0.47 wavelengths.

The task in part, the device is also solved by the fact that in the device for disinfection and heating of water, including a microwave generator, a rectangular waveguide with flanges, a tube of radiolucent material, the axis of which is located at an angle to a wide wall of the waveguide, an end coordinated absorbing load, according to the invention install a tube whose width W is constant and has a maximum value of 0.66 of the size of the wide wall of the waveguide, the tube has an expanding shape and its height h at the entrance to the waveguide is 0.06-0.15 dl us waves, and the height H at the outlet of the waveguide is 0,18-0,47 wavelength and wide side is set to the direction of propagation of electromagnetic wave.

Brief Description of Drawings and Tables

FIG. 1. A device for implementing the method, where 1 is a tube of expanding shape; 2 - transcendental device; 3 - a rectangular waveguide; 4 - flanges; water inlet and outlet fittings are not conventionally shown.

FIG. 2. The circulation-flowing technological scheme

The scheme includes: 1 - a tube of expanding shape; 2 - transcendental device; 3-rectangular waveguide; 4 - flanges; 5 - microwave generator; 6 - end matched absorbing load; 7 - three-position valve (valve); 8 - capacity with treated water; 9 - a centrifugal pump; 10 - adjustable valve (flow regulator).

FIG. 3. Graphical display of parameters from Tab. one.

1 and 2 - the dependence of efficiency and temperature on the flow of water on the device of the prototype.

1 'and 2' - the dependence of efficiency and temperature on water flow according to the proposed technical solution.

Tab. 1. Technological parameters of disinfection and heating of water according to the prototype and the proposed technical solution.

The sign “-” means the absence of microbes in the water.

The sign "±" means the presence of microbes in water at a concentration of up to 100 CFU / ml.

The “+” sign indicates the presence of microbes in water at a concentration above 100 CFU / ml.

CFU - colony forming unit.

The technological scheme (Fig. 2) includes a pipeline connected to a tank 8 with water to be treated, to which, after a centrifugal pump 9, an adjustable valve 10, a temperature sensor t ₁ , an expanding shape tube 1, a temperature sensor t ₂ , a three-position valve ( valve) 7. The pipeline with respect to the tube 1 located in the device for disinfecting and heating water (Fig. 1) is divided into the inlet and outlet lines (the inlet line is located in front of the inlet of the tube 1 after the adjustable valve 10, the outlet - after the tube expanding form 1). In this case, the output line is connected to the tank 8 with treated water through an adjustable valve 10 with the formation of a closed loop (recycle loop).

A solution of ionic silver is injected (Fig. 2) into a container 8 with infected treated water based on the final dose in the water of 0.01-0.02 mg / L. After that, water from the tank 8 by the pump 9 through the adjustable valve 10 is fed to the inlet of the tube 1 of an expanding shape for heating; in the period of establishing the set temperature, water from the tube 1 through a three-position valve 7 is returned to the tank 8 with the treated water; upon reaching the set water temperature, the three-position valve 7 is switched and the treated water is used for its intended purpose, as well as samples are taken for microbiological analysis. Monitoring the water temperature before and after microwave heating is carried out using temperature sensors t ₁ and t ₂ .

A set of Escherichia coli and Pseudomonas aeruginosae at a concentration of 10 ⁶ CFU / ml is used as test microbes. Registration of the main technological parameters (flow rate and water temperature), as well as sampling for biocontrol, is carried out at discrete values of temperature, namely 95, 90, 80, 70, 65, 60, 55, 50, 45, and 40 ° С. Processed water - dechlorinated tap drinking water with an initial temperature of 20 ± 0.5 ° C. To illustrate the operation of the device, a microwave generator is used, generating a frequency of 2450 ± 50 MHz, power 1.0 kW; the main type of wave is H ₁₀ ; section of the waveguide (a × b) - 90 × 45 mm; the expanding tube has a constant width W of 59.4 mm; input height h - 10 mm; the height H at the exit is 32 mm and is made of fluoroplastic.

The intervals of the size of the tube of expanding shape are determined experimentally.

So, the width of the tube W is limited to 0.66 of the size of the wide wall of the waveguide (a). An increase in the tube width above this value does not lead to an increase in the absorption of microwave power, since closer to the corners inside the waveguide, microwave energy is practically absent.

The height of the tube at the inlet h is set 0.06-0.15 wavelength or 7-18 mm, which ensures optimal heating of water with an initial temperature corresponding to the environment from ~ 0 ° C to 35 ° C.

A decrease in the height of the tube h at the inlet below 0.06 wavelength leads to the passage of part of the microwave energy into the end matched absorbing load, i.e. energy loss and reduced device efficiency. An increase in the height of the tube h at the inlet above 0.15 wavelength does not increase the efficiency of the device and productivity and does not ultimately reduce the disinfection temperature.

The height of the tube N at the outlet is set to 0.18-0.47 wavelengths or 22-58 mm, which ensures the temperature of heating and disinfection of water in the range of ~ 45 ° C-95 ° C and up to boiling.

Reducing the height of the tube H at the output below 0.18 wavelength leads to a decrease in the efficiency of the device and performance, as well as the passage of part of the microwave energy into the end matched absorbing load. The increase in the height of the tube H at the output above 0.47 wavelength does not reduce the temperature of disinfection and energy consumption and does not increase productivity.

For example (see table), the proposed device uses a tube of constant width W - 59.4 mm, height h at the inlet - 10 mm, corresponding to an initial water temperature of ~ 18 ° С-20 ° С, and height H at the exit - 32 mm, corresponding to the final disinfection and heating temperature of ~ 65 ° C.

The results of the experiments show that the disinfection temperature in the proposed device is 55 ° C, which is 10 ° C lower than in the prototype device. At this temperature, the efficiency of absorption of microwave energy is 94% compared with 87% in the prototype. Productivity increased from 0.285 l / min to 0.385 l / min; energy consumption decreased from 51 to 40 Wh / h.

In addition, in the proposed device, the tube is used interchangeable and selected for a specific temperature regime of disinfection and heating of water, which ensures high adaptability when using the proposed device in a specific process (technological scheme).

In the established range of heating temperatures (95 ° С-40 ° С), the microwave energy does not reach the end matched absorbing load, i.e. it is completely absorbed by a passage device with an expanding tube. In this particular case, the end coordinated absorbing load is assigned the role of a kind of fuse that assimilates microwave energy in the case when the processed water is accidentally absent for some reason in the expanding tube. This protects the microwave generator from failure.

Due to the inevitable adsorption of ionic silver by the surface of the vessel and microorganisms, as well as the transition of part of it to an inactive, bound state, the final dose of ionic silver in the vessel with treated water does not remain constant. From experience to experience, this dose ranges from 0.01-0.02 mg / L.

This accepted minimum dose of ionic silver provides an effective combined effect on microorganisms in combination with microwave energy in a stream of water.

By itself, such a dose of ionic silver does not have any noticeable effect on microorganisms, even within 60 minutes.

So, the analysis of the given examples (Table 1) shows that the addition of a solution of ionic silver to the process water stream during microwave disinfection and water heating and the use of an expanding-form device with a tube provides:

- lowering the temperature of disinfection and heating of water by 10 ° C from 65 ° C to 55 ° C;

- increase in the efficiency of absorption of microwave energy by 7%;

- increase in productivity by 35.1%;

- reduction of energy consumption by 21.6%.

Claims (2)

1. A method of disinfecting and heating water by applying microwave energy to a stream of treated water of a given size passing through a rectangular waveguide at an angle to its wide wall, characterized in that an aqueous solution of ionic silver is added to the stream of treated water based on its concentration in the treated water 0.01-0.02 mg / l, the water flow has an expanding shape from the entrance to the waveguide to the exit from it, while the width of the stream W has a maximum value of 0.66 the size of the wide wall of the waveguide, the height h at the entrance to the waveguide is 0.06-0.15 wish to set up the wavelength and height H at the outlet from the waveguide 0,18-0,47 wavelength. 2. A device for disinfecting and heating water, including a microwave generator, a rectangular waveguide with flanges, a tube made of radiolucent material passing through it, whose axis is at an angle to the wide wall of the waveguide, and also an end coordinated absorbing load, characterized in that the tube width W has a maximum value of 0.66 the size of the wide wall of the waveguide, the tube has an expanding shape and its height h at the entrance to the waveguide is 0.06-0.15 wavelengths, and the height H at the exit of the waveguide is 0.18-0.47 lengths us and set the wide side to the direction of propagation of electromagnetic waves.

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