Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23L—SUPPLYING AIR OR NON-COMBUSTIBLE LIQUIDS OR GASES TO COMBUSTION APPARATUS IN GENERAL ; VALVES OR DAMPERS SPECIALLY ADAPTED FOR CONTROLLING AIR SUPPLY OR DRAUGHT IN COMBUSTION APPARATUS; INDUCING DRAUGHT IN COMBUSTION APPARATUS; TOPS FOR CHIMNEYS OR VENTILATING SHAFTS; TERMINALS FOR FLUES
  • F23L17/00—Inducing draught; Tops for chimneys or ventilating shafts; Terminals for flues
  • F23L17/16—Induction apparatus, e.g. steam jet, acting on combustion products beyond the fire
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
  • B05B12/00—Arrangements for controlling delivery; Arrangements for controlling the spray area
  • B05B12/16—Arrangements for controlling delivery; Arrangements for controlling the spray area for controlling the spray area
  • B05B12/18—Arrangements for controlling delivery; Arrangements for controlling the spray area for controlling the spray area using fluids, e.g. gas streams
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23L—SUPPLYING AIR OR NON-COMBUSTIBLE LIQUIDS OR GASES TO COMBUSTION APPARATUS IN GENERAL ; VALVES OR DAMPERS SPECIALLY ADAPTED FOR CONTROLLING AIR SUPPLY OR DRAUGHT IN COMBUSTION APPARATUS; INDUCING DRAUGHT IN COMBUSTION APPARATUS; TOPS FOR CHIMNEYS OR VENTILATING SHAFTS; TERMINALS FOR FLUES
  • F23L2700/00—Installations for increasing draught in chimneys; Specific draught control devices for locomotives
  • F23L2700/001—Installations for increasing draught in chimneys

Definitions

• the invention relates to a device for dispersing gas leaving a chimney, in particular for exhausting fumes or stale air.
• chimneys are provided to disperse the gaseous effluents at a certain height in the atmosphere.
• the height of the chimneys varies according to the nature and the composition of the gases, the regulations in force and the results of the study of dispersion of gaseous, particulate and smelly pollutants. Dispersion and dilution of the gases in the environment is improved by increasing the stack height.
• a turbulent and sustained wind regime has the effect of mixing the gases with the ambient air and thus promoting the dispersion of pollutants.
• the chimneys consist of an outer barrel welded metal ferrule or an outer barrel of cylindrical concrete or frustoconical shape.
• One or more internal conduits may be provided; these conduits which channel the gases can be either metallic or synthetic resin, depending on the nature and temperature of the gases to be evacuated.
• the chimney can reach an external diameter of several meters.
• the dispersion of gases in the atmosphere therefore has a ground impact as important as the quantity of emissions produced at the source.
• US Patent 3,670,666 shows a device installed near the outlet of a chimney, comprising at least one auxiliary gas injector, oriented so that the auxiliary gas jet is directed upwards, and feed means the auxiliary gas injector under pressure.
• the injectors are below the outlet of the chimney.
• the jets are oriented to replace a mechanical damper and to change the residence time of the fumes in the chimney. The improvement of the dispersion of fumes in the atmosphere is not dealt with in this document.
• the object of the invention is, above all, to provide a device for dispersing gas leaving a chimney which makes it possible, under unfavorable atmospheric conditions, to avoid a crossing of the maximum admissible concentration threshold for pollutants or odors at the level of of the soil, by limiting the energy consumption required, without imposing an expensive increase in the chimney height.
• a device installed near the outlet of a chimney comprising at least one auxiliary gas injector, oriented so that the auxiliary gas jet is directed upwards, and feed means of the pressurized auxiliary gas injector, characterized in that the or each injector is mounted so that its orientation is adjustable, and is installed and oriented so that the auxiliary gas jet meets the plume of gas from the stack, and produces an upward induction effect, promoting the dispersion of the gas plume exiting the chimney.
• the device generally comprises several injectors supplied with auxiliary gas.
• the jets produced by the injectors are oriented so as to burst the plume of smoke or nauseating air.
• the jets produced by the injectors are divergent
• the injectors may be arranged in a diameter of the section of the outlet of the chimney, or may surround this outlet, in particular in a circle.
• each injector allows, in particular, to limit the "Coanda" effect between the flows, when several chimneys are adjacent.
• the injectors are preferably installed above or at the level of the outlet of the chimney.
• the dimensions and the number of injectors are determined according to the gas flow rate of the stack and the desired dispersion rate.
• Each injector, installed on the same ramp, can have a different geometry and inclination of its own. Thus, the geometry and orientation of each jet can be different individually.
• the supply pressure of the auxiliary gas injectors is a function of the atmospheric conditions and the characteristics of the gases discharged by the chimney; the pressure can be variable in operation to adapt to climatic conditions.
• At least one auxiliary gas distribution rail may be provided between two adjacent chimney ducts, with at least one auxiliary gas injector associated with each duct. , oriented to improve the dispersion of the plume of gas exiting this conduit.
• the supply means of the injector or injectors may be provided to supply the auxiliary gas under a variable pressure of 100 to 1000 daPa.
• the feed means of the injectors preferably comprise at least one fan located at the foot of the chimney, and at least one connecting pipe between the outlet of the fan and a feed ramp of the injector or injectors.
• the feed means of the injector are advantageously adjustable so as to allow the pressure and the flow of auxiliary gas sent to the injectors to be modulated according to the atmospheric conditions of the moment, and the properties of the gas plume, or fumes, the stopping of the means. feeding being controlled when the natural dispersion is sufficient.
• the injected auxiliary gas may be air or gas taken from the main circuit of the gaseous effluents to be discharged through the chimney.
• Fig.1 is an elevational diagram of a chimney and plume of gas evacuated according to the state of the art.
• Fig.2 is an elevational diagram, similar to Fig.1, of a chimney equipped with a dispersing device according to the invention.
• Fig. 3 is a view along the line III-III of FIG. 2, on a larger scale, of the dispersion device shown schematically.
• Fig.4 is an enlarged view along line IV-IV of
• Fig. 5 is an elevational diagram of a chimney according to the state of the art with two adjacent ducts in the same barrel.
• Fig. 6 is a diagram, similar to FIG. 5, a chimney with two ducts equipped with a dispersing device according to the invention, and
• Fig. 7 is a diagrammatic view from above, on a larger scale, of the dispersion device and the chimney of FIG. 6.
• a chimney 1 schematically shown a chimney 1, according to the state of the art, for the dispersion at a certain height in the atmosphere of gaseous effluents that exit according to an ejection cone 2a, widening from the outlet 3 of the chimney.
• the ejection cone 2a forms the lower part of the outgoing gas plume.
• the gaseous effluents to be dispersed may come from a plant (not shown) for thermal energy production, in particular from waste, or may be stale or foul air from wastewater treatment plants. , or come from any other source.
• the chimney has a height of several tens of meters, and can reach or exceed 100 m.
• the chimney has a height of 80 m, and the velocity of the gaseous effluents at the outlet 3 is about 20 m / s.
• the exit of the gases at the outlet 3 can cause a reduced effect of induction of the surrounding air as schematically illustrated by arrows Fa.
• the speed of the ejected gases gradually decreases and is of the order of 12 m / s at a distance of 10 m from the outlet of the chimney, and about
• the gaseous effluents Up to this height H2 the gaseous effluents remain essentially inside the cone 2a. Beyond the height H2, the gaseous effluents are dispersed in an upper part 4a of the plume, schematically represented in a generally oval and upwardly directed form. According to the atmospheric conditions, especially in the presence of wind schematized by an arrow 5 directed from left to right in FIG. 1, the upper part 4a of the plume is more or less inclined in the direction of the wind.
• the facilities, factories or others, are planned to comply with the regulations concerning the release of pollutants at the exit of the chimney.
• Atmospheric conditions in particular a folding wind, may occur resulting in folding the plume to the ground S as shown schematically by the contour 6a.
• Such unfavorable conditions causing the plume to become more drawn down to the ground, can cause a concentration of pollutants or odors at ground level above a maximum allowable threshold.
• a gas dispersion device D is installed near the outlet 3 of the chimney 1.
• the device D comprises at least one and generally several injectors 7.1, 7.2 of auxiliary gas jets.
• the injectors 7.1, 7.2 are oriented so that the auxiliary gas jets are directed upwards, meet the plume of gas 2 from the stack 1 and produce a high induction effect F at the periphery of the ejection cone 2
• the auxiliary gas jets are divergent, so as not to cross each other.
• Means E supply of injectors auxiliary gas at a high pressure of about 100 to 1000 daPa are provided.
• These means E may comprise a fan 8, with a drive motor, provided at the bottom of the chimney 1, the output of which is connected by a pipe 9 to a manifold ramp 10 provided near the outlet 3 of the chimney to distribute the gas auxiliary to the injectors.
• Each injector as illustrated in FIG. 4, comprises a cylindrical pipe terminating radially outwards by a frustoconical nozzle 1 1.
• the section of the nozzle 1 1 narrows to the outlet end; the shape of the conical jet 12 has an external ejection angle of about 24 degrees.
• the axis 12x of the jet is oriented upwards at an angle ⁇ with the horizontal. This angle ⁇ may be between 30 ° and 60 °, and is in particular about 45 °.
• the injectors 7.1 -7.2 communicate with the supply ramp 10.
• the injectors are located generally above or at the level of the outlet 3. Preferably, the injectors are mounted so that their orientation is adjustable, that is to say such that the angle ⁇ can be modified and adjusted.
• the auxiliary gas may be constituted by air or by a fraction of gaseous effluents taken from the main circuit.
• the auxiliary gas injectors 7a, 7b may be arranged along a diameter of the chimney 1. As illustrated schematically in FIG. 3, the Collector ramp 10 is then oriented along a diameter of the chimney and, according to the illustrated example, nine injectors represented by arrows are distributed on either side of the ramp 10, orthogonally to this ramp.
• the injectors 7.1, 7.2 distributed on each side are substantially symmetrical with respect to a vertical plane passing through the axis of the ramp 10 as illustrated in FIG. 4.
• the injectors 7.1, 7.2 may be arranged around the outlet 3 of the chimney, in particular in a circle.
• the line 9 for supplying auxiliary gas may be juxtaposed outside the chimney as shown in FIG. 2, or be inserted into this chimney (Fig.7).
• auxiliary gas pressure supplied by the fan motor 8 is ensured by a variable speed drive or any other mechanical means (tilting device, damper, etc.).
• a variable speed drive or any other mechanical means (tilting device, damper, etc.).
• the pressure at the injectors 7.1, 7.2 can be adjusted.
• the dispersion device D can be stopped when it appears that the concentration of pollutants or odors at ground level is well below the maximum permissible threshold.
• the operation of the device is as follows.
• the position of the injectors 7.1, 7.2 inside the plume produces a strong induction of ambient air at the periphery of the ejection cone, as illustrated by the arrows F.
• This induction effect promotes the dispersion of the plume of gases or fumes. by rapid dilution with ambient air.
• the upward induction favors the dynamic rise of the plume when the effects of a falling wind current are greater than the effects due to the density difference between the outgoing gases and the ambient air.
• the plume will be significantly less folded than according to the state of the art, as illustrated by the outline 6 in FIG. 2.
• the jets produced by the injectors are oriented so as to burst the plume 2, 4 smoke or foul air. Their upward orientation helps support the plume during wind down periods.
• Fig. 5 is an elevational diagram of a chimney 1b consists of an outer barrel 1 c, welded metal ferrule or concrete, cylindrical or frustoconical. Inside this barrel several internal ducts, namely two ducts 1 d1 and 1 d2 in the example shown, are provided for channeling the gaseous effluents to the outlet 3b. These ducts 1 d1, 1 d2, can be metal or synthetic resin depending on the nature and temperature of the gaseous effluents. The proximity of the ducts 1 d1, 1 d2 has the consequence that the ejection cones 2a1, 2a2 of the gaseous effluents meet according to the effect
• the dispersion device D is advantageously installed between the outlets of the ducts 1 d1, 1 d2, for example according to a diameter of the barrel 1 c.
• the injectors 7.1 located on the left according to FIG. 6 produce jets which meet the ejection cone of duct 1d1 located on the left, while injectors 7.2 on the right produce jets which meet the ejection cone of duct 1 d2.
• the drive created by the divergent auxiliary gas jets from the injectors 7.1, 7.2 causes a deviation of the ejection cones 4b1, 4b2 and their spacing, which limits the effect "Coanda” and promotes dispersion.
• Fig. 7 shows schematically in plan view the two ducts
• the injectors 7.1, 7.2 are distributed on either side of the ramp 10 orthogonally thereto.
• the supply pipe 9 is disposed inside the barrel 1c.
• gas dispersing device D installed at the outlet of the chimney, makes it possible to substantially increase the dispersion of pollutants or of malodorous air. In some cases, the presence of such a dispersion device will make it possible to construct chimneys of reduced height compared to the height that would have been necessary in the absence of such a device.
• the energy consumption of the device D is low compared to the significant dilution effect with the ambient air, the energy being introduced at best in the whole system to obtain the maximum dispersion effect.
• the auxiliary gas flow rate delivered by the injectors is of the order of one-tenth (1/10) of the effluent flow exiting the stack.
• the dispersion device D according to the invention can be easily added to an existing chimney, without any notable modification, especially when the external drum 1c contains several separate ducts.
• Such a dispersion device D makes it possible to avoid work important if it appears after construction of a chimney that the atmospheric conditions, on the basis of which the preliminary study and the construction of the chimney were made, do not correspond exactly to the reality and lead more frequently than expected to exceed the permissible concentration of pollutants in the soil.
• the invention can be applied to many installations, including:

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Treating Waste Gases (AREA)

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• 2008
  • 2008-10-14 FR FR0805671A patent/FR2937120B1/fr not_active Expired - Fee Related
• 2009
  • 2009-10-13 EP EP09740990A patent/EP2334986A1/de not_active Withdrawn
  • 2009-10-13 WO PCT/IB2009/054495 patent/WO2010044055A1/fr not_active Ceased

Non-Patent Citations (1)

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