WO2016181215A1

WO2016181215A1 - Installation and method for purifying industrial combustion gases

Info

Publication number: WO2016181215A1
Application number: PCT/IB2016/000657
Authority: WO
Inventors: Ferhat Nili
Original assignee: NILI, Fatma
Priority date: 2015-05-13
Filing date: 2016-05-13
Publication date: 2016-11-17
Also published as: FR3036042A1; FR3036042B1

Abstract

The present invention relates to an installation for purifying industrial combustion gases, comprising: a sealed vessel (100) in which purification water (105) is stored, which vessel has an outlet orifice (106); a dip tube (110) installed in the vessel (100), which tube has an inlet orifice (111) for the admission of the combustion gases and an inlet orifice (112) immersed in the purification water (105); a means (108) for creating a depression inside the vessel (100) so that the combustion gases are set in motion between the inlet orifice (111) of the dip tube (110) and the outlet orifice (106) of said vessel by passing through said dip tube (110) leaving it at the outlet orifice (112) of said tube, then bubbling through the purification water (105); a first spray means (120) for spraying water onto the combustion gases circulating through the dip tube (110) in order to cool them, the temperature of the water to be sprayed by the said means (120) being below 15°C; said purification installation being characterized in that the dip tube (110) comprises, in its lower part, at least one notch (114) of flared shape, extending from the outlet orifice (112) of said tube toward the inlet orifice (111) of said tube, and has a notch part (1140) that is not immersed in the purification water (105); in that the vessel (100) incorporates a second spray means (130) for spraying an aqueous liquid onto the combustion gases after they have bubbled through the purification water (105) and onto the combustion gases leaving via the non-submerged part of the notch (114), the temperature of the aqueous liquid sprayed being below 15°C; in that said installation comprises means for withdrawing a given volume of the purification water (105) when the level of this water exceeds a determined maximum level (N_max) in the vessel (100) and for ensuring that said notch part (1140) remains non-submerged.

Description

INSTALLATION AND METHOD FOR PURIFYING GAS

INDUSTRIAL COMBUSTION

Description

Technical Field of the Invention

The invention relates to an installation and a method for the purification of industrial combustion gases emitted by a waste combustion device containing organic matter. The invention relates to the technical field of the treatment of industrial combustion gases. It applies in particular to the purification of combustion gases emitted by cement plants and industrial waste incinerators.

State of the art

"Combustion gas" or "industrial combustion gas" means according to the present invention the gases and fumes generated by the industrial combustion of fossil fuels (for example natural gas, fuel oil, coal, petroleum derivatives or other) and or waste of domestic, industrial or similar types (for example household refuse, agricultural waste, hospital waste, paper, cardboard, wood, plastic, tire residues, grease, sludge, waste oil, or other). The industrial combustion in question can be carried out in a waste incinerator or in a cement kiln or thermal power plant furnace or glassmaking furnace or steelmaking furnace. In general, flue gases contain many pollutants that may represent an environmental and health hazard (toxicity and irritation) and water vapor. Examples of such pollutants include:

gaseous pollutants such as: carbon monoxide; carbon dioxide ; nitrogen oxides, in particular nitrogen monoxide; sulfur oxides, particularly sulfur dioxide; hydrogen chloride; hydrogen fluoride, organic molecules especially aromatic, and volatile metals such as mercury, and

- particulate pollutants such as soot and fly ash.

These flue gases must be purified before being discharged in order to avoid the transfer of their pollutants to the atmosphere.

In this context, the Applicant has already described in the patent application WO2008 / 086814, a flue gas purification plant emitted by a combustion device such as a waste incineration furnace urban and / or industrial or a cement kiln. This installation is shown in FIG. It comprises a sealed tank 100 in which is stored purification water 105. The tank 100 has an outlet 106 for evacuation of purified gases. The arrival of the combustion gases to be purified is symbolized by the arrow F1 and the evacuation of purified gases is represented by the arrow F2. This known installation also comprises a dip tube 1 10 installed in the tank 100, which tube has an inlet 1 1 1 for the admission of the combustion gases and an outlet 1 12 immersed in the water purification 105. The inlet 1 1 1 of the dip tube coincides with the inlet port 102 of the gases in the tank 100. In operation, the tank 100 is depressurized via a suction turbine 108 (motorized) connected to the outlet 106 so that the combustion gases are set in motion between the inlet 1 1 1 of the dip tube 1 10 and the outlet port 106, passing through said dip tube 1 10 and then bubbling with purification water 05.

A means 120 makes it possible to spray water on the combustion gases flowing through the dip tube 1 10. In practice for purifying the combustion gases, they are forced through the dip tube 1 in which they are washed and cooled. by spraying with water spray; and then bubbling in the purification water 105 to rid them of their particulate pollutants and at least a portion of their gaseous pollutants, before rejecting them to the outside.

However, the Applicant has found that such a purification plant does not allow effective removal of gaseous pollutants contained in the industrial combustion gases (purification rate of at most equal to 80%). Moreover, the study of this purification plant has led to the conclusion that the successive steps described above had to be operated under a strong depression in the tank 100. Indeed, this strong depression has proved necessary, because on the one hand, to force the combustion gases to pass through the plunger tube 10 and to bubble in the purification water 105, and, on the other hand, to set the combustion gases in motion from the furnace (or industrial installation) combustion gas emitter to be purified to said tank 100. However, when one seeks to reduce the depression in said tank 100, in particular to reduce the flow of combustion gases bubbling in the purification water 105 in order to to promote the best capture of their pollutants, there is frequently an increase in the purification water 105 in the dip tube and a very poor circulation of the combustion gases within the tank 100 and between the latter and the furnace ( or installation i industrial combustion) combustion gas emitter purified. This adversely affects the purification process of the flue gases and causes disturbances potentially detrimental to the operation of said furnace (or industrial installation) combustion. Also, it has also been observed by the Applicant that, firstly, the volume of sewage water (V _ea u treatment) in the tank was 100, for optimal treatment, be about 0.33 x V _CU ve (or 1/3 x Widow), with V _CU ve represents the internal volume of the tank 100, and that, on the other hand, when this volume V purification _water becomes excessive (c ' is to say V _Others ud purification> 0.40 x V _CU ve) due to the washing of flue gases by water spray, the tank 100 must be emptied at least partially to reduce this volume. It is understood that, from a practical point of view, this is almost inconceivable because the at least partial emptying of the tank 100 requires the complete shutdown of the installation and causes the interruption of the purification operation in progress .

The purification plant described in WO2008 / 086814 must therefore be improved to limit the emissions of combustion gases.

Faced with this state of affairs, an object of the invention is to provide an installation that improves the purification of industrial combustion gases.

Another object of the invention is to reduce the discharge of industrial combustion gases. Yet another object of the invention is to improve the performance of the purification plant known from WO2008 / 086814 without it being necessary to question its original design.

Yet another object of the invention is to provide a purification plant that is easy to install and whose cost is limited. A further object of the invention is to provide a solution for regulating the volume of purification water contained in the tank 100 without requiring the complete shutdown of the purification plant.

Disclosure of the invention.

The solution proposed by the invention is an industrial combustion gas purification plant, comprising:

- A sealed tank in which is stored purification water, which tank has an outlet port;

a dip tube installed in the tank, which tube has an inlet for the admission of combustion gases and an inlet port immersed in the water purification;

means for causing the inside of the vessel to depressurize so that the combustion gases are set in motion between the inlet of the plunger tube and the outlet orifice of said vessel while passing through said plunger tube; , exiting at the outlet of said tube, then bubbling in the purification water;

a first spraying means for spraying water on the combustion gases flowing through the dip tube in order to cool them, the temperature of water to be sprayed by said means (120) being less than 15 ° C .;

This installation is remarkable in that:

the plunger tube comprises at its lower part at least one notch, which notch has a flared shape, extends from the outlet orifice of said plunger tube to the intake orifice of said plunger tube, and has a portion of notch which is not immersed in the purification water;

the tank incorporates a second spraying means for spraying an aqueous liquid onto the combustion gases after they have been bubbled into the purification water and on the flue gases exiting through the non-submerged portion of the notch, the temperature of the aqueous sprayed liquid being less than 15 ° C;

said installation comprises means for taking a given volume of the purification water when the level thereof exceeds a maximum level N _ma x determined in the tank, and for ensuring that said notch portion remains non-immersed.

The Applicant has now found that, surprisingly and unexpectedly, the use of a dip tube having at its lower part at least one notch, which has a flared shape, extends from the outlet orifice of said dip tube to the inlet of said dip tube, and has a notch portion which is not immersed in the purifying water, has many advantages. A first advantage is that thanks to the non-immersed portion of said notch, the purifying water no longer rises in the dip tube, especially when the depression inside the tank is interrupted or has become lower than the prevailing depression. in the dip tube. Another advantage is that this non-immersed portion of said notch also allows part of the combustion gases to escape. This promotes a continuous flow of combustion gases from the industrial plant (or furnace) emitting flue gas to the purification tank, even when reducing the vacuum in said tank to reduce the flow rate combustion gases bubbling in the purification water to maximize the capture of gaseous pollutants. It should also be noted that the continuous flow of combustion gases between said tank and said industrial installation induces in it a draft depression which causes a fresh air intake "oxidizer" from the atmosphere, and contributes to prevent hot combustion gases from escaping through the waste and / or fossil fuel charging openings, which openings are not necessarily sealed. Furthermore, the non-immersed portion of said notch also allows at least partially evacuate the heat accompanying the flow of combustion gas, which helps to improve the flow of combustion gases. By elsewhere, the removal of a given volume of the purification water when its level exceeds a maximum level (N _ma x) determined in the tank (100), makes it possible to ensure that the part of the notch in question remains non -immergée. The Applicant has also been able to observe that the cooling operation initiated by the second purification means makes it possible to condense in liquid form at least part of the gaseous pollutants which have not been captured by the purification water or which are are escaped by the non-immersed portion of the notch of the dip tube, which further reduces the discharge of gaseous pollutants.

Thus, the use of a dip tube having at least one notch at least part of which is not immersed in the purification water and a second spray tube improves the depuration installation while optimizing the elimination of gaseous pollutants (elimination rate greater than 90%).

Finally, the solution proposed by the invention is simple, effective and economical. Other advantageous features of the invention are listed below. Each of these features may be considered alone or in combination with the outstanding characteristics defined above, and may be subject, where applicable, to one or more divisional patent applications:

The purification water may be an aqueous solution comprising one or more reagents chosen from alkali or alkaline earth hydroxides; and / or from alkali or alkaline earth carbonates.

Preferably, the second spraying means is a pipe arranged in a serpentine inside the tank and around the dip tube, said pipe being pierced with a plurality of spray holes.

Preferably, said sampling means comprise a sampling line equipped with a pump making it possible to take and send said given volume of purification water to a recycling line, and at least one high level detector capable of controlling the startup of said pump when the purification water exceeds said maximum level N _ma x.

Advantageously, the purification plant further comprises a recycling circuit in which at least:

(i) a treatment means receiving, via the recycle line, the purification water taken from the tank and providing at least partial purification of the said purified water;

(ii) a cooling means arranged after the treatment means and ensuring the cooling of the purified purification water at a temperature below

15 ° C, and

(iii) a pipe for conveying the purification water purified and cooled by the cooling means to the second spraying means.

The processing means integrated in the recycling circuit may comprise at least one membrane filtration means selected from tangential filtration means, front filtration means, semi-frontal filtration means and reverse osmosis filtration means.

The purification plant may further comprise means for measuring the pH of the purification water.

- The purification plant may further comprise means for injecting into the tank, a chemical additive for adjusting the pH of the purification water to the desired value greater than 7 and / or to adjust the water of purification to the types of combustion gases to be purified.

The installation according to the present invention is typically equipped with an electronic management unit for controlling and adjusting:

o the depression inside the tank,

the temperature and the pressure of water sprayed by the first spraying means,

the temperature and the pressure of the aqueous liquid sprayed by the second spraying means. According to another aspect, the present invention also relates to the use of said purification plant for purifying the combustion gases emitted by an industrial plant for the combustion of domestic and / or industrial waste and / or fossil fuels and / or biomass. This industrial combustion plant may in particular be a waste incinerator or a cement kiln.

According to yet another aspect, the present invention also relates to a method for the purification of combustion gases emitted by a waste combustion device containing organic matter. This method comprises at least the following steps:

storing purifying water in a sealed tank having an outlet port for exhausting purified gas-eombustion, which outlet port ^" is connected to means for putting and maintaining in depression the inside said tank,

forcing the combustion gases to pass through a dip tube installed in the tank placed and kept under vacuum, said dip tube having an inlet for the admission of the combustion gases, an outlet immersed in the purification water and at least one notch least part of it is not immersed in the purification water,

by means of a first spraying means arranged in said dip tube, spraying water on the combustion gases passing through said dip tube for washing and cooling, the water temperature being less than 15 ° C ,

bubbling the combustion gases thus washed and cooled in the purification water in order to retain their particulate pollutants and at least a part of their gaseous pollutants,

using a second spraying means installed in said tank and outside said dip tube, spraying an aqueous liquid on the combustion gases escaping through the non-immersed part of the notch and the gases of which have not been retained in the purification water, the temperature of the said water spray being less than 15 ° C,

withdrawing a given volume of the purification water when its level exceeds a maximum level Nma determined in the tank, to ensure that said notch portion remains non-immersed,

exhausting the purified combustion gases through said outlet orifice.

In general, the flue gases entering the tank have a temperature of between 50 ° C and 100 ° C. Preferably, the temperature of the water flowing in the first spraying means is 5 ° C.

Description of the figures.

Other advantages and characteristics of the invention will appear better on reading the description of a preferred embodiment which will follow, with reference to the accompanying drawings, carried out as indicative and non-limiting examples and in which:

- Figure 1, above, schematically shows a flue gas purification plant according to the prior art;

- Figure 2 schematically shows a first embodiment of an installation according to the invention;

- Figure 3 schematically shows a second embodiment of the installation of Figure 2;

- Figure 4 shows schematically an installation according to the invention incorporating a system for recycling purified water taken from the tank; or used water purification.

- Figure 5 schematically shows another embodiment of the installation of Figure 2. Preferred embodiments of the invention

Figure 2 shows an industrial flue gas cleaning plant. These can be generated by the burning, in an industrial facility, of fossil fuels (eg natural gas, fuel oil, coals, petroleum derivatives or other); and / or lignocellulosic biomass (eg wood) and / or waste of domestic, industrial or similar types (for example household refuse, agricultural waste, hospital waste, paper, cardboard, plastic, tire residues, greases , sludge, waste oil, asbestos, drilling mud, or other)

As d'exemple-burning devices dont1es ^~ ^~ gas combustion can be captured through the installation of the invention include cement kilns and incinerators of domestic waste, industrial or similar.

The installation according to the invention comprises a sealed tank 100 which is preferably cylindrical on the side wall, closed at its upper end by a ceiling 101 and at its lower end by a bottom 103 provided with a drain hole 104 to evacuate the tank. purification water 105 when used. The tank 100 is further provided in its upper part with an outlet orifice 106 for purified combustion gases, that is to say combustion gases that are depleted of their particulate pollutants and at least a large part of their gaseous pollutants. . In general, the tank 100 is made of corrosion-resistant material, for example stainless steel. Of course, a person skilled in the art will be able to determine for himself the capacity and the dimensions of the tank 100 that are best adapted to the reception of the flue gas stream and to their purification. For example, the tank 100 has a height (H ve) of between 1.5 meters to 15 meters, preferably between 2 meters and 8 meters, and a diameter of between 0.5 meters to 5 meters, preferably between 1 meter and 3 meters. The tank 100 is connected, via its outlet port 106, to a suction line 107 equipped with a means 108 whose function is to create and maintain the tank 100 in depression during the purification of the combustion gases and also to repress the purified combustion gases to the outside. Typically, the depression means 100 is a motorized suction turbine whose start, stop and suction flow are managed by a control unit (not shown) associated with the purification plant according to the invention. 'invention.

The sealed tank 100 contains purification water 105. This is used to purify the combustion gases by capturing their particulate pollutants and at least some of their gaseous pollutants by absorption, by dissolution and / or by chemical reaction. , in particular by acid-base neutralization of gaseous acid pollutants such as hydrogen chloride or sulfurous acid or by ionic reaction, in particular transforming sulfur dioxide into sulphite ions or sulphate ions or their salts.

Typically, the purification water 105 comprises at least water and one or more reagents chosen from alkali or alkaline earth hydroxides such as NaOH, KOH, Ca (OH) 2 or Mg (OH) 2; and / or from alkali or alkaline earth carbonates such as K 2 CO ₃ or MgCO ₃ .

In general, the pH of the purification water is set at a value greater than 7 for example between 9 and 12, depending on the composition of the combustion gases to be purified.

In practice, the purification water composition 105 and its volume are set according to the composition and the volume of the combustion gases to be purified. In general, for an optimal operation of the installation, the volume of purification water does not exceed half the internal volume of the tank 100. Preferably, the volume of purification water (water purification) in the tank (100) represents approximately 0.33 x V _CU ve V _CU ve being the interior volume of the tank 100. A dip tube 1 10 is installed in the tank 100. This dip tube 1 10 has an inlet 1 1 1 for the admission of combustion gases and an outlet 1 12 immersed in the water purification 105. The inlet 1 1 1 allows to establish a fluid communication between the dip tube 1 10 and the combustion device, and this via a pipe 1 13 channeling the combustion gases to be purified.

It should be specified that the combustion gases presented at the inlet 1 1 1 of the tank 100 generally have a temperature between 50 ° C and 150 ° C, in particular between 50 ° C and 100 ° C, and can have a flow rate between 000 m ³ / h and 90000 m ³ / h.

Preferably, the plunger tube has the following dimensions:

2

- a height (Htu e dip) greater than ^ x Hcuve; H _CU ve being the height of the tank 100. For example, H dip tube - X Hcuve, and

6

a diameter varying between 100 mm and 600 mm.

According to the invention, the plunger tube 1 10 furthermore has at least one notch 1 14, at least one part 1 140 of which is not immersed in the purification water 105. The non-immersed part 1 140 has the following advantages: function of avoiding the rise of the purification water 105 in the dip tube 1 10 when the depression inside the tank 100 is interrupted or has become lower than the depression in the dip tube 1 10. This part non-submerged 1140 also allows the evacuation of at least a portion of the heat accompanying the combustion gases to be purified, and optionally the exhaust of a portion of the combustion gases flowing in the plunger tube 1 10.

Preferably, the notch 14 is formed in the lower part of the dip tube 1 10. In FIG. 2, the notch 1 14 has a flared shape which extends from the outlet orifice 1 12 towards the orifice of FIG. admission 1 1 1, its vertex S is located above the level of the purification water 105 at a height H so that the part 1 140 of the notch 1 14 corresponding to this height remains free (not immersed).

The optimal operation of the purification plant according to the present invention was obtained with a notch 1 14 having the following dimensions:

1

- a height greater than - x H _CU ve; and

6

a height H for the non-immersed part, ranging from 40 mm to 100 mm, preferably from 50 mm to 80 mm;

- An angle at the top S of the notch 1 14 from 42 ° to 48 °, preferably equal to 45 °.

In practice, the dip tube 1 10 has a single notch 1 14.

A first spraying means 120 makes it possible to spray water on the combustion gases flowing through the plunger tube 1. Typically, the water sprayed by the means 120 has a temperature of less than 15 ° C., preferably a temperature of 15 ° C. 5 ° C.

Passing through the plunger tube 1 10, the combustion gases come in contact with the water droplets sprayed from the first spray means 120, ^s' are set (this is especially the case for particulate pollutants) and / or s They condense (this is particularly the case of gaseous pollutants condensable at the water spray temperature) and then fall back into the purification water 105 in which they are retained by absorption or chemical reaction, for example by acid neutralization. basic acidic pollutants such as hydrogen chloride, hydrogen fluoride and sulfurous acid (H2SO3), or by ionic reaction transforming sulfur dioxide into sulfite ions or sulfate ions or their salts. By way of example, the first spraying means 120 is a spray tube pierced with lateral holes 121. These are preferably equipped with spray nozzles, preferably solid cone spray nozzles such as those sold by the American company Spraying Systems Co ^® . This spray tube is arranged coaxially in the dip tube 1 10 and defines therewith an annular space 122 which is traversed by the combustion gases when the purification plant is in use. This spray tube is supplied with pressurized water by a feed pipe 123.

To allow the supply of water under pressure, the pipe 123 is generally equipped with a pump (or booster) 125 and optionally a control valve 124. This pipe 123 is connected to a water source which may be a water supply 127 or the water distribution network.

The cooling of the water spray is provided by a cooler 126 installed in the pipe 123. Preferably, the cooler 126 includes a heat exchanger of the tubular or plate type, optionally equipped with at least one thermostat.

Advantageously, the combustion gases which are found inside the tank 100 are subjected after their bubbling into the purification water 105 and / or after their exit by the non-submerged portion 1140 of the notch 1 4, to a second cooling. This second cooling operation makes it possible to rid these combustion gases of at least an additional part of their gaseous pollutants before discharging them externally via the outlet 106. For this purpose, it has been placed inside the tank. 100 second spray means 130 for spraying an aqueous liquid on these combustion gases.

The aqueous liquid sprayed by the second spraying means 130 may be water from the distribution network, or purification water taken from the tank 100 and recycled (as described further in the description). In practice, the temperature of the aqueous sprayed liquid is 5 ° C to 15 ° C.

Advantageously, the second spray means 130 is a conduit disposed in coil around the plunger tube 1 10. The turns of this duct are installed in ^the space between ^the ^suction port 106 and the scrubbing water area 105 and between the plunger tube 1 10 and the inner wall of the vessel 100. This pipe coil is closed at its lower end 131 and pierced ^by a plurality of lateral holes 134 for spraying the aqueous liquid to the flue gases. It is connected by its upper end 132 to a pipe 133 ^for supplying aqueous liquid under pressure at a temperature ranging from 5 ° C to 15 ° C. To allow pressurizing the aqueous liquid, the pipe 133 may be equipped with ^at least one pump (or blower) 135 and optionally a regulator valve 138. In addition, this pipe 133 is connected to a source of aqueous liquid which may be a water tank or purification water tank or the water dispensing network.

Preferably, the lateral spray holes 134 are equipped with spray nozzles, preferably solid cone spray nozzles such as those sold by the American company Spraying Systems Co ^® .

The cooling of the aqueous liquid is provided by a cooler 136 installed in the pipe 133. Preferably, the cooler 136 includes a heat exchanger of the tubular or plate type, optionally equipped with at least one thermostat.

The design of the second spray means 130 in the form of a pipe coil allows efficient cooling of the combustion gases, on ^the one hand, in contact with the droplets of the sprayed aqueous liquid, and on the other hand, by the conduit coil itself playing the role of heat exchanger aqueous liquid gas. The combustion gases thus cooled condense in liquid form and fall back into the purification water in which they are retained by absorption, by solubilization and / or by neutralization.

Those skilled in the art can determine the length and the number of turns of the helical coil tube and the number of spray holes necessary to maximize the contact with the combustion gases and thus optimize the cooling and condensation of the latter , in particular condensable pollutants at room temperature.

With reference to FIG. 3, the plant according to the present invention further comprises a system for taking a given volume of the purification water 105 when its level exceeds a maximum level ^~ (N _ma x) ^~ determined ^"there in tank 100. the given volume of sewage water 105 to take the vessel 100 is the .différence between the maximum level (N _ma x) and minimum (N _m, n) determined the purification water 105 in the tank 100.

Preferably, the system for sampling the given volume of purification water 105 comprises:

a suction pipe 141 connected to an outlet orifice 140 of the tank 100, which suction pipe 141 is equipped with a pump 142 of the motor pump type, for taking and sending the given volume of water of purification to an evacuation point 143, 150,

a high level detector D1 installed in the tank 100, which detector D1 is capable of triggering the suction of the given volume of purification water by the pump 142 when the purification water exceeds the maximum level Nmax, and

a low level detector D2 installed in the vessel 100, detector D2 which is capable ^of stopping the suction of the pump 142 when the scrubbing water 105 reaches the minimum level N _min.

The level detectors D1 and D2 may be float probes. The withdrawal of this given volume of purification water 105 does not require the shutdown of the purification plant and does not disturb its operation. It ensures that the non-submerged part 1140 of ^the notch 1 14 remains open (non-submerged) during operation of this system. It also makes it possible to use only a tank 100 of small capacity and of small bulk unlike a tank (for example that described in WO2008 / 086814) which must have a greater capacity to be able to store purification water. 105 supplemented with the amount of water and sprayed aqueous liquid must either be drained after each flue gas cleaning cycle or when the level of scrubbing water rises inside the tank 100 to one level such that proper operation of the purification plant can no longer be ensured.

In FIG. 3, the evacuation point of the volume taken from the purification water is in the form of a collection tank (143) in which the purified or used purification water is stored before being reprocessed. .

In Figure 4, said point of discharge is in the form of a recycling circuit 150 for processing and cooling ^the sewage water taken from the tank 100.

In practice, this recycling circuit 150 integrates at least one processing means 151; a cooling means 152 and a pipe 153 which connects the suction pipe 141 to the pipe 133.

The treatment means 151 receives, via the conduit 141, the purification water 105 taken from the tank 100 and makes it possible to recover purified water at least partially, by separating the solid particles and, where appropriate, where appropriate, the ions and the dissolved salts of said purified waste water. The treatment envisaged by means 151 may consist of a treatment by decantation, by centrifugation, by filtration (microfiltration or ultrafiltration) on membrane (s) tangential, frontal or semi-frontal (s) or by reverse osmosis membrane filtration.

The cooling means 152 is arranged downstream of the processing means 151. It ensures the cooling of the water leaving the treatment means 151 at a temperature below 15 ° C. This means 152 is, preferably, a cooler including a heat exchanger of the tubular or plate type, optionally equipped with at least one thermostat. The pipe 153 directs the at least partially purified water and cooled to the supply line 1 33 of the second spraying means 1 30. It can in particular direct the purified water to the tank 1 37 in which it is stored before use by the second spraying means 30. The operation of the recycling system 150 can be made automatic thanks to the two level detectors D1 and D2 which respectively trigger the start and stop of the pump 142.

Furthermore, a water supply line 155 of the distribution network may be connected to the treatment means 151, possibly for conventional washes and / or backwashes.

It should be noted that the treatment means 151 may also be used to treat the purification water 105 discharged through the drain line 1040 connected to the emptying orifice 104 of the tank 100.

In practice, the purification plant according to the present invention is provided with a means 1 for measuring the pH of the purification water 105 in order to control its chemical state, in particular its basicity. The means for measuring the pH can. be in the form of a pH electrode immersed in the tank 100, a pH paper, or other. It should be noted that after one or more cleaning operations of the combustion gases, the purification water 105 is diluted with water and the aqueous liquid respectively sprayed by the spray means 120 and 130. The pH value of the purification water 105 is in fact modified following in particular the neutralization of the gaseous acid pollutants of the combustion gases. It is therefore desirable to provide a means for adjusting this pH to a desired value greater than 7. It is also desirable to provide a means for enhancing or modifying the physicochemical properties of the purification water so as to best adapt them to the characteristics of the combustion gases to be purified. For these purposes, the plant according to the present invention advantageously comprises means 160 (see FIG. 5) for injecting a chemical additive intended to adjust the pH of purification water, to the desired value greater than 7 and / or to adapt (That is to say, strengthen or modify) the physico-chemical properties of the purification water characteristics of the combustion gases to be purified. This chemical additive is preferably non-toxic to the environment. Such a chemical additive may be concentrated purification water or an aqueous solution comprising one or more of the components of the purification water 105 or a lime or limestone reagent.

Typically, the injection means 160 comprise a pipe 162 connecting an injection point (or orifice) 161 of the tank 100 to a storage tank 164 storing said chemical additive. Line 162 is equipped with a metering pump 163, for example a peristaltic pump, capable of withdrawing from the storage tank 164 a determined volume V of the chemical additive and of injecting it into the tank 100 to ensure the adjustment. the pH of the purification water 105 to the desired value greater than 7 and / or to adapt the purification water to the types of combustion gases to be purified. The metering pump 163 may be manually triggered, or automatic in particular in response to a control signal provided by the pH measuring means 1 15. The tank 100 may further be equipped with a window 109 (see Figure 2 to 5) preferably located at the water ^surface treatment 105. This window allows visual inspection of the treatment water and its level in the tank 100 during the flue gas cleaning operation.

The installation according to the present invention is preferably equipped with an electronic management unit for controlling and regulating:

the depression inside the tank 100, controlling the means 108, the pressure and the temperature of the water sprayed into the dip tube 1 10 by the first spraying means 120, respectively controlling the pump 125 and the cooler 126,

c the pressure and the temperature of the aqueous liquid sprayed in the tank 100 by the second spraying means 130, respectively controlling the pump 135 and the cooler 136,

c, where appropriate, the means for sampling a given volume of purification water from the tank 100, by controlling the pump 142,

c if applicable, the recirculation system 150 of the ^scrubbing water taken from the tank 100 by controlling the processing means 151 and cooling means 152,

where appropriate, the injection means 160 of the chemical additive in the tank 100, by controlling the metering pump 163.

Furthermore, the electronic management unit is also configured to receive the information addressed by the pH measuring means 105, the level detectors D1 and D2, the thermostat (not shown) equipping the cooling means 152 and the pressure gauges (not shown) equipping the various pumps 125, 135, 142, 163 may be integrated into the installation of the present invention. And in view of this information, the electronic management unit controls, as appropriate, the corresponding means or organs. Typically the electronic management unit comprises at least one main switch and, where appropriate, a "punch" emergency stop device to ensure the safe operation of the installation of the present invention.

The tank 100, the plunger tube 1 10, the spraying means 120, the spraying means 130 and the various members (for example the first and the second spraying means 120 and 130, the lines 107, 123, 133, 141, 153, 162, 1040, the detectors D1 and D2) possibly equipping the purification plant according to the present invention are preferably made of stainless steel.

In general, the tank 100 is positioned vertically on a support frame (not shown). The plant and method proposed by the present invention can capture 100% of particulate pollutants and remove more than 90% of the gaseous pollutants contained in the industrial combustion gases.

The arrangement of the various elements and / or means and / or steps of the invention, in the embodiments described above, should not be understood as requiring such an arrangement in all implementations. In any case, it will be understood that various modifications may be made to these elements and / or means and / or steps, without departing from the spirit and scope of the invention. In particular :

the plunger tube may have several notches,

the cooling means 126, 136 and 152 may be in the form of a common cooler.

- The pipe 141 may be equipped with a means for measuring the pH (not shown) of the purified water taken, for example a pH meter or a pH paper or other. This pH measuring means can be used in place of the means 1 15. the pipe 13 for collecting the combustion gases can be equipped with means for determining the temperature of the combustion gases entering the tank 100.

the tank 100 can integrate at least one thermometer (not shown) to monitor the temperature of the purification water 105 during the flue gas cleaning process.

- The tank 100 may also have a parallelepiped shape.

Claims

claims

1. Industrial flue gas purification plant, comprising: a sealed tank (100) in which purifying water (105) is stored, which tank has an outlet port (106);

a dip tube (1 10) installed in the tank (100), which tube has an inlet (1 1 1) for the admission of the combustion gases and an inlet (1 12) immersed in the water purification (105);

means (108) for causing the interior of the vessel (100) to depressurize so that the combustion gases are moved between the inlet (1 1 1) of the dip tube (1 10) and the outlet orifice (106) of said tank passing through said dip tube (1 10), exiting at the outlet orifice (1 12) of said tube, then bubbling in the purification water ( 105);

first spray means (120) for spraying water on the combustion gases flowing through the dip tube (1 10) to cool them, the temperature of water to be sprayed by said means (120) being less than 15 ° C; said purification plant being characterized by the fact that:

- the plunger tube (1 10) has at its lower part at least one notch (1 14), which notch (1 14) has a flared shape, extends from the outlet (1 12) of said tube to the inlet port (11) of said tube, and has a notch portion (1140) which is not immersed in the purification water (105); the tank (100) incorporates a second spraying means (130) for spraying an aqueous liquid on the combustion gases after they have been sparged in the purification water (105) and on the combustion gases that exit through the non-combustible part; immersed in the notch (11), the temperature of the aqueous sprayed liquid being less than 15 ° C .;

said installation comprises means for taking a given volume of the purification water (105) when the level thereof exceeds a maximum level (Nmax) determined in the tank (100), and to ensure that said portion ^of slot (1140) remains non-submerged.

2. purification plant according to claim 1, characterized in that the purification water is an aqueous solution comprising one or more reagents selected from alkali or alkaline earth hydroxides; and / or from alkali or alkaline earth carbonates.

3. Treatment plant according to claim 1, characterized in that the second spraying means (130) is a pipe arranged in a serpentine inside the tank (100) and around the dip tube (1 10), said conduit being pierced with a plurality of spray holes (134).

4. purification plant according to one of claims 1 to 3, characterized in that the sampling means comprises a sampling line (141) equipped with a pump (142) to collect and send said given volume of purifying water to a recycle line (141), and at least one high level detector (D1) capable of controlling the start of said pump (142) when the purifying water exceeds said level maximum (N max /.

5. purification plant according to claim 4, characterized in that it further comprises a recycling circuit (150) in which is integrated at least:

(i) a treatment means (151) receiving, via the recycle line (141), the purifying water taken from the tank (100) and ensuring at least partial purification of said water purge,

(ii) cooling means (152) arranged after the treatment means (151) and cooling the purified purification water to a temperature below 15 ° C, and (iii) a conduit (153) for conveying purified purification water cooled by the cooling means (152) to the second spray means (130).

6. purification plant according to claim 5, characterized in that the processing means (151) comprises at least one membrane filtration means selected from tangential filtration means, front filtration means, semi filtration means frontal and reverse osmosis filtration means. 7. A purification plant according to one of claims 1 to 6, characterized in that it further comprises means for measuring the pH of the purification water (105).

8. purification plant according to one of claims 1 to 7, characterized in that it further comprises means (162) for injecting into the tank (100), a chemical additive for adjusting the pH of purification water to the desired value greater than 7 and / or to adapt the purification water to the types of combustion gases to be purified. 9I. Installation according to claim 1, characterized in that it further comprises an electronic management unit for controlling and adjusting:

o the depression inside the tank (100),

the temperature and the pressure of water sprayed by the first spraying means (120),

the temperature and the pressure of the aqueous liquid sprayed by the second spraying means (130).

10. Use of a purification plant according to one of claims 1 to 9 for purifying the combustion gases emitted by an installation industrial combustion of domestic and / or industrial waste and / or fossil fuels and / or biomass.

1 1. Use according to claim 10, characterized in that said industrial combustion plant is a waste incinerator or a cement kiln.

12. Process for purifying industrial flue gas, said method comprising at least the following steps:

I 0 - storing purifying water (105) in a sealed tank (100) having an outlet (106) for exhausting the purified combustion gases, which outlet (106) is connected to means (108) for placing and maintaining in depression the interior of said tank (100),

force the combustion gases through a dip tube (1 10) installed

1 5 in the tank (100) placed and maintained in depression, said dip tube (1 10) having an inlet (1 1 1) for the admission of combustion gases, an outlet (1 12) immersed in the water purification (105) and at least one notch (1 14) of which at least a portion (1 140) is not immersed in the purification water,

with the aid of a first spraying means (120) arranged in said plunger tube (1 10), spraying water on the combustion gases passing through said plunger tube (1 10) in order to wash and cool them, the water spray temperature being below 15 ° C,

bubbling the combustion gases thus washed and cooled in the purification water (105) in order to retain their particulate pollutants and at least part of their gaseous pollutants,

using a second spraying means (130) installed in said tank and outside said dip tube (1 10), spraying an aqueous liquid on the combustion gases escaping from the non-immersed portion of the notch (1140) and combustion gases which have not been retained in the purification water (105), the temperature of said water spray being less than 15 ° C, withdrawing a given volume of the purification water (105) when its level exceeds a maximum level (Nmax) determined in the tank (100), to ensure that said notch portion (1140) remains immersed ,

exhausting the purified combustion gases through said outlet orifice (1 06).

1 3; Process according to Claim 1 2, characterized in that the combustion gases to be purified have a temperature of between 50 ° C and 100 ° C.

14. The method of claim 1 3, characterized in that the water flowing in the first spraying means has a temperature of 5 ° C.