FI82202C - Device for purification of fan gases - Google Patents

Description

1 82202 Ventilation cleaning system

The invention relates to arrangements for the incineration of industrial waste, more particularly to arrangements for neutralizing gaseous wastes or toxic gases, and in particular to arrangements for cleaning ventilation emissions.

The present invention is most preferably used in arrangements for cleaning low toxicity ventilation emissions from paint and drought areas using organic solvents and having local vacuum cleaners in the workplace.

The invention can be used in mechanical engineering, metallurgy, instrumentation and any field of industry where varnishes and paints are used.

A known arrangement for cleaning ventilation emissions (SU-A 520489) comprises a jacket inside which a combustion chamber with a burner, a mixing chamber with a perforated tube and an afterburning chamber with catalytic elements formed of two perforations are arranged in succession. coaxial cone and tube heat exchanger.

The perforated tube in the mixing chamber provides a uniform heating of the vent emissions to the oxidation reaction temperature in the catalytic elements of the array. The coaxial position of the burner and the perforated pipe of the mixing chamber does not guarantee the uniform mixing of the combustion gases with the ventilation emissions, which leads to an uneven temperature of the air flow in front of the catalytic elements and, consequently, inefficient operation of the arrangement. Forming catalytic elements in the form of two perforated coaxial cones requires additional costs for the thermal insulation of a large afterburner.

Known arrangement for the purification of ventilation emissions (Lurgi, "Reinforcement of gases, abrasions and absorption of absorption and

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2 82202

Katalyse ") comprises a jacket inside which a combustion chamber with a burner is arranged, over which a pipeline is installed to supply ventilation emissions. The pipeline for supplying ventilation emissions and the burner are placed in parallel.

Such a combustion and afterburning chamber structure in which the catalytic elements are arranged horizontally creates unfavorable conditions for the equalization of the air flow velocity in front of the catalytic elements, which leads to uneven loading of the different areas of the catalytic elements and correspondingly impairs the arrangement. The parallel placement of the vent exhaust supply pipe and the burner results in an uneven temperature of the air flow in front of the catalytic elements, which also impairs the performance of the arrangement.

The object of the invention is to provide an arrangement for cleaning ventilation emissions, in which by changing the structure of the combustion and afterburning chamber, the air flow is equalized when it enters the heat exchanger.

The core idea of the invention is that the arrangement for cleaning the ventilation emissions comprises a jacket inside which a combustion chamber with a burner on which a pipeline for supplying ventilation emissions is placed, an afterburning chamber with a catalytic element heat exchanger and a heat exchanger according to the invention. and between the afterburner, a manifold with a V-shaped tip directed toward the afterburner is installed, and in addition, the catalytic elements are formed in the form of two inclined quadrangular prisms contacting each other at their upper edges and the pipeline is mounted so as to the line cuts the burner line to equalize the airflow temperature.

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Preferably, the angle of the manifold is 120-140 °.

The point of intersection of the pipeline line and the burner line is preferably located on the opposite wall of the combustion chamber relative to the burner.

The surface of the manifold is preferably perforated so that the holes make up 20-40% of the area of the manifold and the perforation has projections which are bent downwards and are convex relative to the tip of the manifold.

Equipping the arrangement with a manifold allows an even distribution of the air flow as it enters the heat exchanger over a small distance between the afterburner and the heat exchanger. The formation of the catalytic elements in the form of two inclined quadrangular prisms which contact each other at their upper edges allows a smooth flow of ventilation emissions through the catalytic elements and protects them from flame bursts when the burner operates in extreme conditions without additional protection devices.

Next, the invention will be clarified by means of an exemplary embodiment thereof and a drawing showing, in longitudinal section, an arrangement according to the invention for cleaning ventilation emissions.

The arrangement comprises a jacket 1, inside which a combustion chamber 2 with a burner 3 is placed. A pipe 4 is placed above the burner 3 to supply ventilation emissions. An afterburning chamber 5 with two catalytic elements 6, 7 is placed on top of the combustion chamber 2. The pipeline 4 and the burner 3 are placed on the same wall of the combustion chamber 2. Line 8 of the pipeline 4 intersects the line 9 of the burner 3 with the opposite wall of the combustion chamber 2 at point 10. The expediency of cutting such line 8 of the pipeline 4 and line 9 of the burner 3 is proved by the formula

Atx = ΔtQ · n \ | , with 4 82202

At = temperature difference between ventilation flow and flue gas flow at distance X; X = distance from the point of the maximum temperature difference of the ventilation emissions to the point of the minimum temperature difference;

At = temperature difference between the vent flow and the flue gas flow at the outlet of burner 3; n = coefficient of variation of the temperature of the ventilation emissions in the flue gas stream; bQ = height at the outlet to supply the vent emissions of pipeline 4.

It follows from the formula that the best distance X and correspondingly the minimum temperature difference Δt at the inlet of the heated vent stream to the catalytic elements 6, 7 is ensured by placing a pipe 4 for supplying vent lines so that its line 8 intersects the burner 3 with the line 9 opposite the burner 3.

A heat exchanger 11 with three air ducts 12, 15, 14 is mounted on the afterburner 5. The air duct 15 leads to a pipe branch 13 for supplying part of the ventilation emissions to the burner 3. A V-shaped distribution grille 16 is installed between the heat exchanger 11 and the afterburner 5. The installation of the distribution grid immediately between the heat exchanger 11 and the catalytic elements 6, 7 ensures a constant air flow rate as it enters the heat exchanger 11 and enables the reduction of installation costs as well as the reduction of heat loss to the environment by reducing the heat transfer surface. Jakoriti 16 has a tip pointing towards the afterburner 5. The angle of the tip of the manifold 16 is 120-140 °.

Outside these angular values, the airflow roughness factor begins to increase sharply defined by the ratio v Vmax K = -, where V. mm K = air flow velocity roughness factor, 5 82202

Vmax = maximum airflow rate, V „. = minimum air flow rate, min c

The uneven velocity factor of the air flow does not exceed 10% when the angle is 120-140 ° and the hydraulic losses are 10-15 Pa.

The surface of the distribution grate 16 is perforated, which is 20-40% of the total area of the distribution grid. If the perforation makes up less than 20% of the area of the manifold 16, the heat losses will increase sharply. If the perforation exceeds 40% of the total area of the manifold, the flow rate unevenness increases and reaches more than 25%. On the surface of the manifold 16, protrusions 17 are formed from each of its holes, which are bent downwards and have a convex shape relative to the tip of the manifold 16. The protrusions are necessary to change the direction of the air flow before it enters the heat exchanger 11. The catalytic elements 6, 7 of the afterburning chamber 5 are formed in the form of two inclined quadrangular prisms which contact each other at their upper edges. Such formation of catalytic elements ensures a constant velocity of air flow due to the reduction of the inlet area between the catalytic elements 6, 7, where the heated ventilation emissions enter the combustion chamber 2. The space between the catalytic elements 6, 7 decreases in such a way that, upon arrival at the uppermost contacting edges, the entire current passes through the filterable surfaces of the catalytic elements 6, 7. The decrease in the inlet area between the catalytic elements 6, 7 due to the relative decrease in the amount of air flow is equal to the air flow velocity over the entire surface of the catalytic elements, which produces an air flow smoothing effect.

The arrangement works as follows.

Ventilation emissions enter through the air duct 12 to the heat exchanger 11, where they are heated by the heat of the purified gases. Thereafter, part of the ventilation emissions passes from the heat exchanger 11 through the air duct 15 and pipeline 4 to the combustion chamber 2. Another part of the ventilation emissions passes through the pipe branch 13 to the burner 3 to guarantee the combustion process of fuel gas, for example from a gas tank. Thereafter, the combustion gases leave the burner 3 and move in the direction of the line 9 of the burner 3 with the ventilation gases. Ventilation emissions from pipeline 4 move in the direction of line 9 of pipeline 4 and mix with the combustion gases. The most efficient mixing of flue gases and ventilation emissions is achieved by a structure of the pipeline 4 and the burner 3 where the line 8 of the pipeline 4 and the line 9 of the burner 3 intersect at a point 10 on the opposite wall of the combustion chamber 2 with respect to the burner. pass through the air-receiving surfaces of the catalytic elements 6, 7, where the process of cleaning the ventilation emissions takes place in the form of flameless oxidation. The purified ventilation emissions continue to pass through the manifold 16. The projections 17 in the manifold ensure that the air flow is evenly balanced. The purified ventilation emissions continue to pass through the heat exchanger 11, transfer some of their heat to the ventilation emissions as they pass through the air duct 12 and leave the arrangement through the air duct 14.

The use of the presented arrangement makes it possible to increase the efficiency of the arrangement, reduce its size and reduce metal consumption.

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Claims (4)

Apparatus for purifying the fan gases comprising a jacket (1) containing a combustion chamber (2) provided with a burner (3), above which a pipe piece (4) for supplying the fan gases is arranged, in series after the combustion chamber (2). a post-combustion chamber (5) is provided, catalytic elements (6, 7) are provided, and a heat exchanger (11), characterized in that a distribution grid (16) is arranged between the heat exchanger (11) and the post-combustion chamber (5). , the tip of which is V-shaped and facing the post-combustion chamber (5), in addition, the catalytic elements (6, 7) have the shape of two inclined prisms, the upper edges of which are in contact with each other, and the pipe piece (4) is arranged on a in such a way that its shaft (8) cuts the shaft (9) of the burner (3) for equalizing the temperature of the air stream. Device according to claim 1, characterized in that the tip angle of the distribution grid (16) varies between 120 ° and 140 °. Device according to claim 1, characterized in that the point of intersection between the shaft (8) of the pipe piece (4) and the shaft (9) of the burner (3) lies on the opposite wall of the combustion chamber (2). Device according to claim 1 or 2, characterized in that the surface of the distribution grid (16) is provided with a perforation which constitutes 20-40% of the total surface area of the distribution grid, which perforation exhibits from the downwardly curved projections (17) of the distribution grid, which are convex. in relation to the tip of the distribution grid (16).