RU2565000C2 - Device for air cleaning of aerosols - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to protection of ambient air against aggressive and fine aerosols. Claimed cleaner comprises mixer with water, centrifuge and motor with fan. Note here that it incorporates extra battery of cyclones, electrical refrigerator running on the Peltier cooling effect and condenser running on the principle of backflow condenser. Note also that said main components are arranged as follows in airflow direction. Battery of cyclones for primary purification of sucked air, motor with fan, jet-type mixer of air with water containing batched amount of surfactant, moisture condenser with moisture backflow into said mixer. Electrical refrigerator hot side contact with mixer liquid phase while its cold side performs further cooling of airflow after bubbling step of purification. Then, condensate collector and centrifuge for separation of moisture drops from airflow.

EFFECT: better removal of dust from air.

1 dwg

Description

The proposed device for air purification relates to the field of protection of environmental air from aggressive and highly dispersed aerosols, where thorough air purification is required. The device can also be attributed to dust collecting equipment and used in domestic and industrial premises for periodic dry cleaning and dust removal of air.

In technology, an aerosol with particles of a size of mainly 0.1-100 microns is called dust, and an aerosol with a smaller particle size (less than 0.1 microns) is usually called simply an aerosol.

As a rule, the aggressiveness of the atmosphere of an environment that is dangerous for humans requires prompt action and mobility of the means used (therefore, the compactness of the device, independence from expensive and scarce consumables, and a minimum of energy consumption). The means used must be universal in the sense of both air purification and dust cleaning. On the other hand, the aggressiveness of the atmosphere of the external environment requires the need for an increased level of cleaning and the safety of the cleaning process itself.

It is known according to the patents RU 2038125, B01D 47/05, B01D 47/00, 1995; RU 2365402, B01D 47/05, 2006; RU 2323033, B01D 47/05, 2008 and others, the use for cleaning a gas stream from aerosols of its preliminary heating, humidification, subsequent cooling with coarsening and trapping of dust particles by condensation of liquid vapor on them with inertial deposition of them on the walls of the refrigerator. The main advantage of the described method is the possibility of deep cleaning, however, the implementation of this method requires large-sized devices (structures).

It is known, for example, the device according to patent RU 2091135, B01D 47/05, B01D 47/06, 1997, which is used to purify a gas containing ultrafine dust particles (approximately 1 μm in size).

The essence of the method of purification of hot gas, which is implemented in the device, is that the hot gas before being fed into the nozzle scrubber is subjected to saturation washing at a temperature of 60-70 ° C, during which the dust particles are wetted, and then the gas saturated with steam is cooled to conducting steam condensation and then passed through a separator to separate the droplets. Due to the formation of a large amount of steam, ultrafine dust particles are wetted to a large extent, which facilitates their subsequent separation, thereby contributing to the achievement of a very high degree of gas purity (dust content did not exceed 5 mg / nm ³ ). Moreover, the achieved cleaning efficiency is realized without a significant increase in energy consumption for the implementation of the method.

The advantage of this method is the possibility of deep gas purification without the use of consumables (with the exception of water) by utilizing the initial heat of the gas and vaporization.

The disadvantage of this method is the need for large quantities of water and a large-sized device that implements the method.

Devices for removing household (home) dust and aerosol from the air are called vacuum cleaners. In vacuum cleaners, the optimal methods for air purification that exist at the moment are implemented. The advantages of vacuum cleaners are primarily in the compactness and mobility of the product and, therefore, in the ability to quickly respond to the aggression that has occurred in the atmosphere, but they work for a relatively short time (1-2 hours). The deepest level of air purification is provided in liquid-type vacuum cleaners.

It is known, for example, the device according to patent RU 2018258, A47L 9/18, 1994, operating as a liquid filter of a vacuum cleaner. The device contains two chambers with liquid. One chamber serves for rough air purification, and the second serves for a thin, final stage of air purification. The main advantage of such filters is their practicality and ease of use. The disadvantage is in their insufficiently high degree of purification.

It is known, for example, the device according to patent RU 2228134, A47L 9/18, 2003, which includes almost all currently known advantages of liquid vacuum cleaners.

A feature of the vacuum cleaner is that it can operate as an air purifier in a continuous mode when connected to a water main and sewage system or to a sump.

This vacuum cleaner contains a housing in which two liquid coarse and fine air filters are integrated. In the lower part of the body of the vacuum cleaner there is a special vessel, which is a dust collector. To work, water or liquid is poured into the vessel, possibly pre-filtered, deodorized, with aromatic oils.

The sucked-in dirty air is evenly distributed over the liquid along the annular surface under the bend roof and with a small vacuum inside the vacuum cleaner, the air sparges (bubble effect), leaving large and medium particles of dirt at the bottom of the vessel. The bubbling intensity is proportional to the useful power of the fan. Next, the air goes to a centrifugal filter. The centrifugal fine filter is rigidly fixed to the output shaft of the electric motor. Rotation with a high frequency (up to 20,000 rpm) creates an air-water mixture above the water surface in which the smallest drops of water moisten and capture dust particles. At the same time, a centrifugal filter in its upper part ensures the separation of water and air. The air leaving the centrifugal liquid filter ensures the removal of thermal energy released during the operation of the electric motor. Then, after the HEPA filter, the air returns already cleaned and moistened to the room. In general, the essence of the cleaning mechanism is to maximize the contact surface of air with the aqueous medium.

However, this method of creating an air-water mixture and a device based on them has at least two disadvantages.

Firstly, this process is quite energy-intensive, since it involves a relatively large mass of water with high kinetic energy.

Secondly, this process still does not solve the problem of cleaning air from aerosols deeply (a separator filter retains approximately 99.95% of the available dust). To solve many special cleaning tasks (protection against military agents, dioxins, viruses, radioactive aerosols), a deeper degree of air purification is required. Therefore, at the final stage in vacuum cleaners, an HEPA filter (High Efficiency Participate Air) has to be additionally installed, in addition, holding aerosols of substances inert to water (hydrophobic particles). Vacuum cleaners with a HEPA filter hold up to 99.99% of the available dust. Another advantage of the HEPA filter, in addition to efficient cleaning, is its compactness.

The disadvantages of the HEPA filter include the following.

The HEPA filter is an expensive and scarce consumable. It is almost impossible to quickly monitor the degree of contamination. In the process of work, the accumulation of harmful substances occurs in its volume and the possibility of subsequent uncontrolled reverse discharge of some of these harmful substances into the atmosphere remains. In an aggressive environment, such a filter becomes an element of one-time use.

When using a vacuum cleaner as an air purifier, the method of air purification itself does not change, therefore it is not suitable for protection against aggressive dust.

The objective of the invention is to provide a device for cleaning air from aggressive aerosols, eliminating the need for expensive and scarce consumables.

The solution to this problem is achieved by using the proposed device for cleaning air from aerosols, including in the direction of air flow a bubbler type mixer with a liquid, a centrifuge and an electric motor with a fan, characterized in that it additionally contains a small-diameter cyclone battery, an electric refrigerator based on the Peltier cooling effect , and a condenser operating on the principle of a reflux condenser, with the main elements of the device located in the following air flow direction: a small-diameter cyclone battery for preliminary rough cleaning of intake air, an electric motor with a fan, a bubbler air-water mixer containing a dosed amount of surfactant, a moisture condenser with its return drain to the mixer, an electric refrigerator, the hot side of which is in contact with the liquid phase of the mixer, and its cold side serves for further cooling of the air flow after the bubbling cleaning step, condensate collector and as a centrifuge separator for separating the water droplets from the air stream.

The essence of this invention as a technical solution is expressed in the aggregate of the following essential features.

The first significant feature that characterizes the proposed device is the inclusion of a battery of small diameter cyclones with a sump for temporary collection and storage of coarse dust in the device circuit. The cyclone battery provides a “dry stage” of cleaning at the beginning of the process. At this stage, up to 90% by weight of all available dust is removed. Most importantly, the coarsest dust is removed, which can interfere with the progress of the further process. This fact greatly simplifies further air purification in the proposed device. It avoids the possibility of water getting into the electric motor (the electric motor is located up to the liquid filter).

The second essential feature characterizing the proposed device is the use of a liquid phase in a bubbler type mixer with a dosed input of detergents, i.e. surface active substances (surfactants). In the case of the use of surfactants, air purification is sent according to a fundamentally different cleaning mechanism, the “air wash” mechanism.

Air dust (especially household dust) contains about 10-20% of dust with hydrophobic properties. Most of these particles have a greasy film on their surface. Particles of such dust are not wetted by water (and part of the dust, which has natural hydrophobicity, is not wetted by steam) and, therefore, remain in the air stream. For this reason, the majority of vacuum cleaners manufactured include an HEPA filter. To its lower limit (approximately 0.3 μm), the HEPA filter delays them.

The essence of the mechanism is the initial wetting of all dust particles, in particular the elimination of the grease film. Dust with natural hydrophobicity, with the help of surfactants passes the stage of hydrophilization. A hydrophilic (wetted) dust particle either immediately and irreversibly passes into the solution, or, if the particle is in the gas phase, it is surrounded by an aqueous shell and, thus, coarsens. Moisture condensation on a hydrophobic (non-wetted) particle does not occur. Each droplet of mist contains a wetted particle of dust as a nucleus.

The third significant feature that characterizes the proposed filtering device is the presence of a moisture condenser after the mixer. The moisture condenser works like a return cooler for the primary discharge of heat into the environment.

Due to condensation of water vapor on them, dust particles are significantly (by orders of magnitude) enlarged. A corresponding increase in the mass and size of particles greatly simplifies their further extraction from the air (makes it possible to use an inertial separation method).

The fourth significant feature that characterizes the proposed device is the presence of an electro-cooling Peltier device. The hot (heat-releasing) side of the refrigerator is used to heat water in a bubbler type mixer, and the cold side of the refrigerator is used to cool air at the final stage of its purification.

The fifth essential feature characterizing the proposed device is the relative position of the elements in the direction of air flow. In particular, it links the operation of the cyclone battery with the operation of the electric motor, which is located immediately after the cyclone battery. This allows the engine cooling heat to be used to heat the air stream, followed by the transfer of this heat to the liquid medium (energy saving). The second point is the spatial separation of the spheres of moisture condensation and phase separation. This dramatically reduces the energy costs of the centrifuge.

The direct arrangement of the separation device above the water surface (Pat. RU 2228134) involves a large mass in rotation (m) of water and in accordance with the known formula for the kinetic energy W = mV ^2/2 requires significant energy. The main purpose of this separation device was to maximize the development of the contact surface of air and water. The purpose of the centrifuge in the proposed filter is fundamentally different. It consists only in the removal of entrained water droplets from the air stream, which reduces energy consumption by an order of magnitude. The combination of in-depth cooling (formation of mist droplets) of air and the subsequent inertial separation of droplets from the stream increases the quality of air purification by an order of magnitude.

Each of the above signs should be recognized as essential and necessary. Their combination provides sufficient conditions for solving the task.

The technical result achieved when using the proposed air purification device is as follows.

1. The proportion of dust captured by the proposed method is more than 99.995%. A deep degree of air purification is largely ensured by the implementation in this method of a fundamentally different mechanism of air purification. The device provides conditions for the removal of all, including initially hydrophobic particles, due to the high efficiency of wetting the particles.

The lower limit of the size of the particles removed by the device is not limited (for comparison, the size of the captured particles for the HEPA filter is limited and is more than 0.3 μm). Thus, the proposed device provides a deeper degree of air purification than a vacuum cleaner with a HEPA filter.

Thus, the proposed device allows you to exclude from circulation HEPA filter as an expendable structural element, i.e. provides a solution to the problem.

2. The device increases the reliability and durability of the filter. Improving the reliability and durability of the filter (the safety of its operation) is largely ensured by the introduction of the preliminary stage of "dry cleaning", implemented using a battery of cyclones. This ensures the practical independence of the filter to the qualitative and quantitative side of the dust (provides increased "omnivorous" filter). The quality of the previous stage always significantly affects the quality of further work of the product.

3. The device simplifies the process of waste disposal and increases its safety. The practice of using any air purification devices leads to the conclusion that it is necessary to perfect the operation of concentrated waste treatment, in terms of simplicity and cleanliness of the waste disposal process, which consists in the absence of a reverse discharge of some dust and a minimum of final operations. This is an important point in operating reusable devices. The simplicity and cleanliness of the waste disposal process is largely provided in the device by separating the possible discharge of the spent solution and dumping solid waste into a special container. Reverse emission of part of the dust during filter cleaning is excluded.

4. The device provides dust removal both when cleaning the air, and when cleaning the room.

A diagram of the proposed device is shown in the drawing.

The cleaning device includes a battery of cyclones 1 of small diameter with a sump 2 for temporary collection and storage of coarse dust. The sump 2 contains a grate 3 for separating coarse dust from the liquid phase during waste disposal and a drain valve. To create a vacuum at the air inlet 4, there is an electric motor with a fan 5. Further, the device includes a bubbler mixer 6 of air with water, an electric Peltier 7 and a centrifuge (separating device) 8. The mixer contains a grid 9 for crushing the air flow and a condenser 10. The hot side of the Peltier electric refrigerator 7 is directed to heating the water of the mixer, and its cold side serves to cool the air flow after the bubbled cleaning step. Condensed moisture is collected in condensate collector 11.

The device operates as follows. Initially, a dusty stream of air 4 is sucked in by a fan 5 operating from an electric motor into a small diameter cyclone battery 1 (4-10 pieces). Using cyclones, the air is cleaned of coarse dust (generally about 90-96% by weight). Coarse dust (particle size greater than 5-10 microns) settles in settler 2, as in a trap. Such a cyclone battery at the airflow inlet is used, for example, in Dyson vacuum cleaners. Relatively cleaned and dry air “washes” and cools the electric motor. In this case, the air flow is heated to approximately 40-65 ° C and sent to the mixer 6 bubbler type.

At the second stage of air purification, the main thing that should be ensured when air is in contact with water is wetting the surface of the particle. The wetted particle already remains irreversibly in the water. Effective wetting of dust particles requires water heating (not more than 90 ° C), which is provided by the hot surface of the Peltier 7 electric refrigerator, and the presence of surface-active substances (ordinary washing powder). Dust with natural hydrophobicity, with the help of surfactants passes the stage of hydrophilization. In the second stage, the air is cleaned of particles up to 0.1 microns in size. At this stage of cleaning, approximately 90-95% of the available dust entering the mixer 6 is removed. Nevertheless, part of the dust contained in the air bubbles passes through the bubbler mixer through the grid 9. In this case, the treatment with the surfactant particles of initially heated particles continues in the gas phase in the condenser 10.

In the next stage, the air is cooled in the condenser to approximately the temperature of the medium (3-6 degrees higher) and the remaining dust particles of all sizes become nuclei of condensation of water vapor. The enlargement of particles in the form of mist droplets is further enhanced with decreasing temperature upon contact of air with the cold surface of the electric refrigerator 7 (cold surface temperature is about minus 6-10 ° C). In general, dust particles are thus enlarged in size and mass by at least 1-1.5 orders of magnitude. It is this enlargement of particles that determines the final cleaning efficiency according to the filter mechanism described above. Condensed water enters the tank 11.

In such an already cooled state, air is introduced into a centrifuge (separating device) 8, where the final effective separation of fog particles with dust particles from the air stream is performed. At this stage of air treatment, the possible presence of surfactants that are easily detectable by smell is also effectively eliminated.

Introduction to the design of the device of an electric refrigerator allows you to increase not only the degree of purification, but also the level of control of the air purification process, which is no less important. In fact, the refrigerator is a tool for implementing the above washing mechanism. The introduction of the cooling stage also allows you to further dry the air at the outlet. The level of heating water in the mixer and the degree of air cooling (about 1-3 degrees below the temperature of the medium) by the refrigerator are determined from the required degree of air purification. This ensures the necessary savings in energy consumption. The energy consumption of the dust cleaning process is saved on the damage of a conventional vacuum cleaner.

In practice, design optimization and its energy costs will be determined by the specific application. When dusting (short-term operation of the device in vacuum mode), the power consumption of the device will be maximum. When cleaning air (continuous operation of the device in air purifier mode), the power consumption of the device will be minimal. In the latter case, the cyclone battery is temporarily shut down from operation (particle size of the floating dust is less than 1-3 microns), and the device itself is connected to the water main and sewage system or to the sump.

Cleaning the device after the end of its operation consists in draining the entire solution into the sump 2. All the dust in the sump is wetted. In this case, the dust passing through the mesh 3 of the sump is drained into the sewer, and the largest moistened dust remaining on the mesh is shaken off into the solid waste container. Thus, separate disposal of liquid and solid wastes is realized and the reverse discharge of part of the dust into the atmosphere is excluded. Such waste disposal simplifies the process and ensures the safety of waste disposal.

The performance of all elements of the device separately and the system as a whole is determined and verified experimentally.

The fraction of dust collected by the device is not less than 99.995%, the size of the captured particles is more than 0.02 μm (for comparison, the size of the captured particles for the HEPA filter is more than 0.3 μm).

Claims (1)

A device for cleaning air from aerosols, including a mixer with water, a centrifuge and an electric motor with a fan, characterized in that it further comprises a cyclone battery, an electric refrigerator operating on the basis of the Peltier cooling effect, and a condenser operating on the principle of an inverse refrigerator, the main elements of the device are located in the following sequence in the direction of air flow: a cyclone battery for preliminary rough cleaning of intake air, an electric motor with a fan orom, a bubbler air mixer with water containing a dosed amount of a surfactant, a moisture condenser with its return drain to the mixer, an electric refrigerator, the hot side of which is in contact with the liquid phase of the mixer, and its cold side serves to further cool the air stream after the bubbler stage of cleaning condensate collector and centrifuge as a separator for separating moisture drops from the air stream.

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