FI117323B - A method and apparatus for purifying a gas such as air from unwanted gaseous compounds - Google Patents

Description

117323 METHOD AND APPARATUS FOR GAS CLEANING UNWANTED GASEOUS COMPOUNDS

The invention relates to a method as described in the preamble of claim 1 and to an apparatus as described in the preamble of claim 4 for purifying a gas such as air from unwanted gaseous compounds.

The purification of air from malignant odors has proven to be very difficult due to the presence, in most cases, of a complex mixture of compounds with varying odor thresholds and very low levels for some compounds. Studies have been published analyzing, for example, landfill odors, about 100 compounds with odor thresholds for some compounds in the range of 1 ppb (part per billion). In other words, the odors on the human nose represent very small amounts of odor.

A typical disgusting odor compound is hydrogen sulfide. It has an odor threshold of 0.5 ppm (part per million). A common odor compound commonly found in the pulp industry is methyl mercaptan, which has a Odor Threshold of a few tens of ppb.

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Biofilters have been extensively researched and applied in practice. Biofilters are generally large box-shaped devices filled with bark of wood or the like. The medium is implanted with a 5 limiting bacterial strain which has the ability to "eat" some of the compounds present in the odorous air, mainly hydrogen sulphide. These nitrogen compounds cannot be eliminated to the same extent, and thus the result is in most cases a slight decrease in odor intensity. Bio-based events are slow 10, so processing times are long and devices very long. Another problem is to provide a sufficiently large contact surface between the odorous air and the bioactive surface. By increasing the size, the contact between air and the medium in the biofilters is increased.

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Strong oxidizing agents have been used to calculate the odor intensity of the air. An example of this is ozone gas. There are devices that generate in situ ozone gas by means of an electric current and then blow ozone gas into the volatile air stream. The problem is that some of the odor compounds are oxidizable while others are more oxidizable. In addition, a practical problem is to feed the ozone stream to a smelly * · * large amount of air so that the contact or mixing * # is even. The method is also limited by the fact that it is safe; * ·· 25 ozone levels are very low for oral reasons. In practice, "* ·: In practice, only a slight reduction in the odor intensity is achieved by the use of ozone.

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Gas scrubbers are mainly used to remove a particular compound 30 from the air stream. A typical example is the removal of sulfur dioxide from air in industrial processes. In a gas scrubber, air is usually blown through a vertical reactor filled with a porous medium and circulated upstream by a suitable chemical solution of sulfur dioxide. The method is suitable for the situation where «·« I is, for example, to calculate a concentration of a compound from 10,000 '* ppm to 10 ppm. In a situation where a highly variable 117323 3 batch of compounds have to be removed from a concentration range of 5 ppm to a range of 0.1 ppm, the method is poorly suited. It is very difficult to obtain sufficiently effective contact with the chemical and by-pass air in the washer. This factor is sought to be enhanced by adding multiple washes to the process, but the cost increases accordingly.

The so-called dry cleaning technology has long been known. In this process, the inert porous medium is treated with some strong oxidant e.g. potassium permanganate. When smelly air is blown through the porous material, it oxidizes the oxidizable compounds, mainly hydrogen sulphide, thereby reducing the odor intensity of the air discharged. In order for the oxidation reactions to be sufficiently complete, it is necessary to use several overlapping steps, which result in high costs. For this method to achieve a sufficiently complete contact with the reactive solid and the flow-through gas, the rising cost is due to two reasons. Increasing the contact surface 20 requires multiple steps, which in turn increases the flow resistance, which in turn implies an increasing need for electricity.

• 4 • · «* ♦ ♦ • * *. *: Also used for cleaning air from odors. activated charcoal * #; *** 25 additional filters. Some sulfur-containing compounds are adhered to or adsorbed on the carbon surface. In particular, activated carbon filters are used to remove hydrogen sulphide. They do not remove the odors as a whole.

It is an object of the present invention to provide a process for the purification of undesirable gaseous compounds and an apparatus for purifying gases such as air, with the limitations of the methods described above: ** : exit. Outgoing air is substantially free of odor; ] · Β 35 of the relevant compounds (using the sense of smell) and additionally * * · **. * The method is economical.

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The first condition for the complete removal of very low concentrations of odoriferous compounds from the air is that the odor-binding event, in this case the liquid solution, hereinafter referred to as the binder solution, is completely contacted with the odor-causing compounds. It is essential for the process according to the invention that in the purification process the sooty air is brought into contact with a so-called. binder solution in a manner that allows near-complete contact with it and odor-inducing compounds. In the process of the invention, the incoming air is first decomposed in a so-called. with super-oxidizer films. This step breaks the air into a large number of small gas bubbles. Thereafter, the scavenged air encounters a reactor fill which is of such a nature as to further reduce the size of the air bubbles and to cause the bubble stream to circulate randomly. As such material, the reactor filling is a lathe chip packed in the process of the invention. It provides a large free surface area in terms of volume, is randomly guided by gas bubbles and, in addition, due to its sharp edges, cuts and disrupts gas bubbles. In one embodiment of the method, the amount of contact between the gas bubbles and the * * * binder solution is increased by the fact that the binder solution will also have to undergo * * · 25 random turbulent movements as it passes countercurrently through the reactor fill.

fc *: **: The basic idea of the invention is to bring the odorous air and the active binder solution into perfect contact with each other so that almost all of the air odor molecules are able to contact the surface of the binder solution absorbed into the binder solution and thus · · This should happen as quickly as possible, • keeping the size of the plant in relation to the airflow small. The operation according to the invention requires that the reactions between the perfume compounds and the binder solution are sufficiently rapid and do not constitute a complete bottleneck in the process. There are many known alternatives based on the principles of organic chemistry.

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The method according to the invention is characterized by what is stated in the characterizing part of claim 1 and the apparatus is what is described in the characterizing part of claim 4.

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The invention will be explained in more detail by way of one example applying the invention, with reference to the accompanying figure, in which the method and apparatus of the invention are schematically and simplified. Other preferred embodiments of the invention are characterized in what is stated in the claims.

The entry point 8 of the gas to be cleaned, such as bad odor air, is located in the lower part of the apparatus, which also houses a compressor 7, which acts as a fan 7 and feeds air into the reactor 1. At the bottom of the reactor there is a box-like space 10 for equilibrating the air flow, which provides a direct pressure over the entire bottom area of the reactor. The body following the airborne web as it goes up is a superoxide film 20 or equivalent air-dispersing porous material 6. This part is characterized by having small holes β · β · β or porous channels of thousands per dm 2. At this stage, the air decomposes into a large number of small gas bubbles which

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.2 * begin to rise in reactor-filled binding solution. Binding: ** The top surface of the 25 solutions is in step 2. The reactor fill 3 is lying * * over the steel mesh 5. The reactor charge consists of metal grit * · ·: V, more suitably stainless steel lathe * # · 2. This flexible material, when formed, has a density of 100-120 kg / m3. It is compressed between a steel mesh 11, which acts as a top stiffener: 30 and a bottom mesh 5 to a density of 100-400. ** ·. kg / m3. As the density increases, this filling more efficiently breaks down the gas bubbles from the bottom. While its flow resistance «· · ••• | increases, higher pressure is required to provide air bubble flow and the compressor power demand increases.

m • · * · 35: When the binding solution is flowing through the reactor • * filling described above, it is also subjected to a stream of occasional small swirls .1 ------- 117323 6. When gas bubble flow is passed through the binder solution in such a flow state, the chances of encountering the gas molecules and the binder solution are increased. In the method according to the invention, this situation 5 can be achieved by installing a circulation pump 4 at position 12, i.e. in the lower part of the reactor, immediately above the air-dissipating elements 6. The pump transfers the solution to the top of the reactor at position 13, thereby providing a top-down flow of the binding solution.

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The batch of binder solution fed to the reactor is saturated after a specified operating time. After that it must be replaced. This is done by opening the drain valve 14 at the bottom of the reactor, after which the solution flows gravitatively from the reactor 15.

The purified air is discharged into the reactor fill and through the binding solution after passing from the top of the reactor to position 9.

Instead of steel chips, the chips produced by turning plastics can also be used as reactor filler. Crushed rock material, "like a lacquer grate, is also an alternative reactor filler * * * * ·" · [a. Without first-stage disintegrators, all of the so-called super-oxidant films that form microbubbles in 4: *** 25 binder solution .Micro-bubble refers to an air bubble *! * '! In a solution having a diameter of one millimeter or less ** In addition to super-diffuser films, the method is applicable to: ***; ceramic materials characterized by a large * * * pore space area for.

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The method and apparatus of the invention provide one or more of the following advantages: *: **: - The method is more efficient than all known methods. The result of purification is the human mind tuna perfect.

• · · - The method is economical because it requires simple construction and can utilize industrial waste.

- Due to the simplicity of operation, the method is 5 reliable and almost maintenance free.

- The method is very safe for the user.

- The method is environmentally friendly. While operating, the 10-way reactor is not loud no matter what the compressor is, because sound insulation can be made very simple by very simple means.

It will be apparent to any person skilled in the art that the invention is not limited to the above example. Its applications may range, for example, from the following applications: - removal of toxic gases from the air 20 - removal of general air pollutants • 1 · ***** - removal of odors from the breathing air • · • 1 »« t • ·: 2 · 25 - passing through a suitable liquid most airborne particles are transferred to it. The process of the invention is characterized in that it can be freely dimensioned for any amount of air. As the flow of II-30 increases, the diameter of the reactor and the size of the decomposing organs will increase.

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Claims (8)

A process for purifying a gas, such as air, from unwanted gaseous compounds, comprising contacting the gas to be purified with a solution (2) which binds said undesired gaseous compounds, characterized in that the gas to be purified is decomposed in a gas stream. by means of a diffuser (6), such as a super-diffuser film or the like, which are micro-bubbles which are made to flow under pressure through a reactor filler (3) cutting the microbubbles and causing random turbulence in a state filled with a solution of undesirable gaseous compounds ( 2). Method according to Claim 1, characterized in that the solution (2} which binds the unwanted gaseous compounds is made to flow in the reactor space (1) in a substantially opposite direction to the gas stream formed from the microbubbles. Method according to claim 1 or 2, characterized. , making microbubbles collide in a reactor space • ·; \ (1) Micro-bubble-cutting and sporadic turbulence * * «** forming a reaction filler (3), or • ·! ** 25 matching. Apparatus for purifying gas, such as air, from unwanted gaseous compounds having at least a purge gas inlet (8), a gas flow blower (7) or the like, a gas flow equalization state · * · « . ·· *. (10), reactor space (1) and reactor space reactor backfill (3) arranged in a reactor space (1) arranged to be surrounded by a solution of ¢ 2) unwanted gaseous compounds, known that the apparatus is substantially small in the direction of gas flow 35 prior to the reactor charge (3): the microbubble gas flow diffuser (6), and that the reactor charge (3) consists of at least microbubble cutting and random vortex material. Apparatus according to Claim 4, characterized in that the apparatus comprises a pump (4) for circulating a solution (2) that binds unwanted gaseous compounds, which is arranged to circulate the solution (2) in the reactor space (1) in a substantially opposite direction to a gas stream in relation to. 10 Apparatus according to claim 4 or 5, characterized in that the microbubble gas stream diffuser (6) is a super-oxidant film or the like. Apparatus according to one of Claims 4 to 6, characterized in that the reaction filler (3) consists of at least lathe or similar sharp-edged material. Apparatus according to any one of claims 5 to 7, characterized in that the reaction filler (3) is extruded. ^ reaction mode (1) to a density * * higher than the original density. • · · · • · · ft ft ft ft ϋ ϋ · · ft ϋ ϋ ϋ ϋ ϋ ϋ ϋ ϋ ϋ ϋ ϋ ϋ ϋ ϋ ϋ ϋ ϋ ϋ ϋ ϋ ϋ ϋ ϋ ϋ ϋ ϋ. • ft • ft • ft • ft * ft ft • · · ft • ··· • • ft • ft • · · · · · ftft ft «« ft • · ft • ·· ft · 117323