WO2017129872A9

WO2017129872A9 - Homogenised reaction method, such as lean-gas combustion, and devices implementing same

Info

Publication number: WO2017129872A9
Application number: PCT/FR2017/000025
Authority: WO
Inventors: Jean Marie Gabriel Charles LUCAS
Original assignee: Lucas Jean Marie Gabriel Charles
Priority date: 2016-01-28
Filing date: 2017-01-30
Publication date: 2017-09-28
Also published as: WO2017129872A1; FR3047299A1

Abstract

The invention relates to an exothermic reaction method in which the reagents are mixed with the reaction products, the whole being rotated and reaching a temperature such that the reagents, diluted in the reaction products, react with one another. Said method is particularly suitable for performing a stable, partial or total combustion of lean gas at a temperature that is low enough to only produce small amounts of NOx. The invention also relates to devices which allow the method to be implemented.

Description

Homogenized reaction process, such as a poor gas combustion, and devices implementing it

TECHNICAL AREA

The invention is part of the processes and techniques for reacting reactants between them difficult to react spontaneously with each other, such as for example blast furnace gas and air or poor gases gasification and air .

The application of the invention to combustion, which will then be performed in a highly homogeneous manner, is not the only interesting industrial application of the process that is the subject of this patent. This process can also be used more generally for gas-gas reactions. reactions of suspended matter in one or more gases and even for reactions between liquids in which it is desired to homogenize the media and / or temperatures.

PRIOR ART To obtain a stable combustion of a fuel that is both rich and poor, it is often possible to use so-called pre-mix burners or burners that make mixtures between more or less rotating jets that are generally rendered turbulent: in the burners with When the mixture is mixed, the fuel is mixed as homogeneously as possible with the oxidant (for example air) and the mixture is ignited in a combustion chamber. It then develops a flame by the usual process of flame front propagation. But if the gas to be burned is a poor or very poor gas, given the low content of components If this gas is fired, the flame propagation velocity may be low or very low, which may lead to unstable flames.

The problems posed by the flame stability of combustion increase when one has to deal with poor or particularly poor gases, which leads, to burn these poor gases, to particular solutions often unsatisfactory. For the combustion of, for example, blast furnace gas, it is not easy to stabilize a free flame. Good stability of the combustion is obtained only by an initial heating of the combustion air, heating which, moreover, increases the temperature of the fumes. But to heat the combustion air has the disadvantage, regardless of an additional cost due to the price of the exchanger used for this, to increase at least all the high temperatures reached in the flame and thereby increase the NO _x products.

The innovation that is the subject of this patent meets various needs and in particular the following: achieve a stable partial or total combustion of gas (which can be poor because of its composition and in particular because of a nitrogen and vapor content very large quantities of water) without producing too much NO _x . This is important for example when you want to burn poor gases.

In general, flaming combustion is based on the existence of particularly hot areas (flames) in which the production of NO _x is activated because of the very high temperature prevailing in these zones. The technique currently used to make burners "low NO _x " (for example methane burners or different hydrocarbons) is to recycle in the combustion zone a certain amount of fumes. But the fact of mixing fumes with fuel and with the oxidant depletes the fuel-oxidant mixture and leads to the same difficulties of flame stabilization as those which one faces for the combustion of poor gases. However, the recycling of fumes is an advantageous way to obtain a homogeneous gas combustion

The principle of a recycling of fumes in the mixture of fuel and oxidant inspired the work that led to the invention developed here. SUMMARY OF THE INVENTION

Let us begin by describing the process which is the subject of this patent in the case where the reagents to which it applies are an oxidant and a gaseous fuel. In this case, the products of the reaction may be called smoke.

In this case, the invention described here produces a combustion approaching a homogeneous combustion which has the advantage of being without a particularly hot point. In addition, it makes it possible to stably achieve total or partial combustion of even poor fuel gases.

Call room the place in which the combustion takes place.

According to this invention, the fuel and the oxidant introduced into the chamber are vigorously and rapidly mixed with large volumes of very hot fumes (because heated by combustion) which are rapidly re-circulated in the chamber by a substantially rotary movement of the fuel. set of gases in this space. The important mixture obtained thanks to the rotation of the gases in the combustion chamber, allows the fuel and the oxidizer to be rapidly brought to a temperature sufficient for the combustion to take place and this without, however, locally reaching the very high temperatures that would have to be obtained for a stable flame combustion in this mixture. The temperatures reached must only be those which are necessary for the homogeneous combustion by contact of the diluted oxidant with the diluted fuel also by the fumes.

This patent presents a method and devices for implementing it that achieve in several ways the rather homogeneous combustion referred to. This method and the devices for implementing it are advantageously applied for example to the total or partial combustion of a lean gas gasification gas, in which case it is obviously not limited. The method involves introducing the fuel and the oxidant into the mass of high temperature gas rotating in a combustion chamber in which a circular bulk flow takes place around an axis that will be called the axis of the chamber. dimension of the chamber in the direction of the axis of the chamber being called length of the chamber, the faces of the chamber limiting it in length being called ends of the chamber and the other faces of the chamber being called the walls of the chamber .

In the process described here, the temperatures, the mixing conditions between fuel, oxidizer and fumes rotating in the chamber, as well as the movements of the gases in the chamber are such that the oxidant and the fuel are mixed in less than one turn around. from the axis of the chamber. It is advantageous for the fuel and the oxidant to react with each other in less than one turn.

The injection of fuel and oxidant into the chamber is made either at the periphery of the chamber, through openings through the walls or at the ends of the chamber, or through pipes supplying fuel or oxidant to the interior of the chamber. chamber, these pipes being provided with orifices in their end part. The movement of the gases in the chamber can be maintained by the supply of momentum to the gas rotating in the chamber that is the injection of fuel or oxidant into the chamber. This contribution is even greater than the speed of the injected gas is large. The injection of a reagent into the chamber brings all the more momentum to the rotational movement in the chamber that this injection takes place in the direction of the movement of the gases at the injection point in question, ie approximately perpendicular to the axis of rotation and the radius of curvature of the rotational movement at this point. The movement of the gases in the chamber can also be maintained by a mechanical means of rotation such as a fan resistant to the temperatures that prevail in the chamber, or by a combination of supply of momentum by the injection of reagents and by mechanical means of rotating such as a fan.

In any case, the amount of movement transmitted to the rotating gases should be sufficient to maintain the rotation of the gases in the chamber despite the losses created in the flow by the presence of walls and possible pipes introducing fuel and combustion in the room.

This will be all the easier as the possible fuel and / or combustive conduits inside the chamber will be designed so as to disturb as little as possible the flow of gases in the chamber, that is to say will be aerodynamic vis-à-vis the flow of gases in the chamber. This will therefore usually lead to the pipes that are not approximately in the axis of the chamber being of flattened shape in the direction of flow.

In order for the injection of fuel and / or oxidant to participate significantly in maintaining the rotational movement of the gases in the chamber, the amount of movement added by the injected gas (s) must be sufficiently high, which imposes sufficient speeds. of at least one of the injected gases.

At a constant reagent flow, injecting this gas through small orifices rather than through large orifices makes it possible to increase the injection speed. Such an arrangement also has the advantage of facilitating the mixing of the reagent in question with the gases circulating in the chamber.

Depending on the case, the lines that bring a reagent into the chamber may be composed of one or more parts. In all cases, at least a portion of these pipes comprises the reagent injection ports in the gases flowing in the chamber. This part of the pipe or, where appropriate the entire pipe, is called the introduction pipe. The introduction lines may be fed by another pipe called supply line, either directly or via pipes called intermediate pipes. As mentioned above, it is advantageous that the conduits supplying the reagents to the orifices through which they are injected into the chamber are aerodynamic vis-à-vis the flow of gases in the chamber.

It has also been explained that it is advantageous for the injections of reagents to take place in a direction both perpendicular to the chamber axis and the radius of curvature of the injection point flow.

Ensuring that the injections of reagents into the chamber take place in the direction of the flow of gases in the chamber through the trailing edge of the introduction lines is therefore advantageous. The fuel and the oxidant can be supplied to the orifices through which they are injected into the chamber by separate pipes or by pipes having a common face.

The introduction pipes may be in the form of a fin filling all or part of a quarter circle of the section of the combustion chamber, a fin whose leading edge is rounded and which introduces the fuel or oxidant by its trailing edge (about 90 ^th from the leading edge). The flap does not necessarily go to the axis of the room.

The introduction lines, or the intermediate or supply lines, can also be flattened and aerodynamically shaped vis-à-vis the flow that surrounds and parallel to the axis of revolution of the chamber. The pipes may comprise straight or curved sections.

It is advantageous to provide a supply line approximately in the axis of the chamber in order to minimize the disturbances it induces in the flow.

The part of the pipes that joins the outside of the chamber can be powered by a box outside the chamber. It should be noted that, despite the dominance of the tangential component of the velocity in the chamber, the fact that the gases finally exit the chamber can induce an axial component of velocity. It is the composition of the rotational component and the axial component that defines the velocity at the various points of the chamber. The speeds are therefore not precisely in a plane perpendicular to the axis of the chamber but more precisely, in the case of a gas outlet at one end of the combustion chamber, on a helix with increasing pitch towards the outlet of which the axis is the axis of the chamber. This can cause fins or flattened conduits carrying oxidant and fuel to be not exactly disk sectors but rather sectors of propellers.

The description of the process in the most general case where the reactants are not an oxidant and a gaseous fuel is the same as that described in this case by replacing the fuel and the oxidant with the reactants of the reaction, the fumes by the products. of the reaction, the gases present in the chamber by the reagents and the reaction products present in the chamber and the combustion or oxidation by the reaction. It can be seen that this process can be applied only to an exothermic reaction between several reactants whose initial temperatures, dosage and nature are such that, if the reaction takes place, the products of the reaction are carried by the reaction to a reaction. sufficient temperature so that at this temperature the reaction takes place.

It should be noted in particular that this process may concern the reaction between a fuel and a non-gaseous oxidant.

It is possible to introduce more than two reagents into the chamber.

In particular, it is possible to introduce into the chamber, in addition to at least two substances which react with each other exothermically, a substance which will be mixed with the substances which react with each other exothermically and with the products of their reaction, and will undergo various transformations related to the conditions that prevail in the room.

For example, it is possible to introduce into the chamber, in addition to an oxidizer and a fuel, a substance which will undergo gasification therein.

MANNER OF REALIZING THE INVENTION

Devices for applying this method may be various. In particular, three devices are used which implement the method of the invention:

a high temperature elevation device (up to 1000-1200 ° C.) of intermediate gases of a biomass air gasifier, a device located in a closed chamber, advantageously cylindrical in shape of revolution (but which could also be cylindrical of square section, polyhedral or other). The flow inside the chamber is generally helical around the axis of the chamber.

a device, corresponding to an open reactor in which the shape of the chamber is that of an upside down trough of semi-cylindrical bottom extended by parallel flat faces, which corresponds to a reactor whose chamber is opened by a longitudinal strip; which can be very wide on another zone of the apparatus which contains it and that it can supply very hot gas, gas which leaves the chamber by the slit in the form of very wide band. It will be noted that, in this device, the main flow, in the reaction space, remains generally of revolution about the axis of the half-cylinder of the partially enveloping surface

a third device that can be called a "lean gas burner". It is indeed a device that can be introduced into the central chamber of a boiler designed to put a conventional oil burner or gas. In the place of the conventional burner, the device is introduced which brings combustion air into the combustion chamber by a supply line, of gradually decreasing section, advantageously of square section and can gradually decrease the introduction lines, flattened, connected to the supply line, return the oxidizer by rotating it around the room. To facilitate the construction and reduce the pressure drop in the oxidant, it is possible to choose to use straight introduction pipes inclined at an acute angle with respect to the supply pipe to which they are connected directly, the section of the supply line being square and constant. Fuel introduction is made around the oxidizer feed line by rotating it around the oxidizer feed line.

The injection of oxidant is made in the chamber and vigorously rotates the gases in this chamber. The chamber can advantageously be the chamber of a boiler in which the flame of oil or gas would develop if it were equipped with a burner. oil or gas.

The device that can be called "lean gas burner" ensures a stable and fairly homogeneous combustion of the fuel gas, which can be a lean gas gasifier, in a boiler built to receive a conventional burner.

In these three cases, the combustion space is advantageously at least partially defined by a cylindrical material chamber wall of revolution.

The details concerning these devices are given below, in the description part of the drawings.

SUMMARY DESCRIPTION OF THE DRAWINGS

FIG. 1 represents a cylindrical combustion chamber of revolution corresponding to the first case above, seen in section along a plane perpendicular to the axis of the chamber, in which the injection of the oxidant and the fuel are made through the wall; outside the chamber by two slots having a wall in common. It shows the outer wall (1), the insulation layer (2) and the inner wall (3) thin sheet. It also shows the flattened lines (4) which bring the gases and the air in parallel plane layers and having a common face. It shows the leading edge (5) of the aerodynamic profile of these flattened pipes and the trailing edge (6) through which the fuel in the center and the oxidant in thin layer out on both sides. We see baffles (7) which guide the air space so that it is well perpendicular to the radius and thus in the direction of the general flow when it leaves. It shows, grouped together in one space the fuel supply boxes (8) and air (9) feeding the various flattened pipes. It shows the pipe (10) which brings air to the supply box (9) which concerns it. Finally, there is a flange (11) which makes it easier to assemble and connect the boxes. It shows the plates (12) for fixing the ignition burners and the gas starting line (13).

FIG. 2 represents the same chamber as FIG. 1, seen in section along a particular axial plane. The fact that the pitch of the speed propeller is increasing leads to the gradual increase of the angle with respect to the axis of the fuel and air injection pipes when approaching the exit of the gases. .

FIG. 3 is a perspective view of a combustion chamber integrated into a device corresponding to the second case above and to a configuration in which the fuel enters through flattened ducts located in planes perpendicular to the axis of the chamber. (One of the formulas mentioned in the description) while the air enters by an aerodynamic conduit parallel to the axis of the chamber and fed at one end. It will be noted the outer wall (1), the thermal insulation (2), the inner wall (3) which is here of polyhedral section, more closed than a half-cylinder, and completed by flat walls (14) of each side. Here the flattened pipes (4) are located in planes perpendicular to Taxe and bring the fuel gas from the box (8). Here, the oxidant is not distributed around the pipes bringing the fuel as in the previous case but it is distributed along the trailing edge of the sheet metal (15) by a slot. It is brought into this sheet metal (15) whose aerodynamic shape will be noted, by an air duct (16) immersed in the insulation of the bottom of the chamber. Note the inlet (17) of the flame of the ignition burner in the chamber.

FIG. 4 represents a section of the chamber seen in perspective in FIG.

Figures 5, 6 and 7 relate to the third case described above.

Figure 5 shows a lean gas burner (20) in the inner chamber (21) of a commercial boiler. The central air supply duct (18), the aerodynamic flat ducts (19), which transport and inject air into the flow from the duct (18), will be noted. The conduit (22) brings the fuel rotating around the central air supply line (18).

Figure 6 shows an enlargement of the aerodynamic flattened and curved lines (19).

FIG. 7 represents a section of one of the flattened ducts (19) which inject the air into the chamber represented in FIG. 5. It will be noted the thin slot (23) through which the air is injected and the aerodynamic shape of the air. the cup. Figures 8, 9 and 10 show another version of lean gas burner (20) can be introduced into the inner chamber of a commercial boiler. It shows the air supply line (18) which will be in the axis of the inner chamber of the boiler, the aerodynamic intermediate ducts (24) and the flattened introduction ducts (19) which inject air into the boiler. bedroom.

Figure 9 shows an overview of the device.

Figure 8 shows a more detailed perspective view of a part of the same device.

Figure 10 shows a sectional detail of a small part of the device on which can be seen on a distribution line one of the thin slots (23) through which the air is injected. The arrows in thick lines represent the flow of air from the supply line to the intermediate pipes. INDUSTRIAL APPLICATIONS

The first described version of the invention can advantageously be used in gasification plants of various materials and in particular more or less wet biomass in which it will advantageously achieve a high temperature elevation chamber of the intermediate gases of the oxidation gasifier. partial of these gases by air.

The second version of the invention described above can advantageously be used in compact and monobloc biomass gasification plants where it will advantageously make it possible to produce a high temperature elevation chamber for the intermediate gases of the gasifier by partial oxidation of these gases by air. The third version has a large number of industrial applications insofar as it advantageously makes it possible to post-burn lean gas both by using cold air and heated air, and in particular to make this post-combustion by Instead of a burner that would supply a boiler, making existing boilers likely to be supplied with lean gas, including gas gasification air biomass or coal. The application of the invention, which allows in particular to achieve a highly homogeneous combustion developed throughout the following text is not the only interesting industrial application of the process that can also be used more generally for gas-gas reactions , reactions of suspended matter in one or more gases and even for reactions between liquids in which it is desired to homogenize the media.

The industrial applications of the process and the devices making it possible to implement it objects of the present patent are not limited to the cases cited above.

Claims

claims

1) a process for carrying out an exothermic reaction between several reactants whose initial temperatures, dosage and nature are such that, if the reaction takes place, the products of the reaction are carried by the reaction at a sufficient temperature so that, at this temperature, the reaction takes place, the place in which the process takes place being called chamber, characterized in that:

1) in the chamber, the reagents and the products of the reaction are in rotation movement about an axis that will be called axis of the chamber, driven in this movement by mixing the amount of movement of the reagents entering the chamber and reaction products and reagents therein or by the use of a mechanical rotating means, the dimension of the chamber in the direction of the axis of rotation being referred to as the length of the chamber and the faces of the room limiting it in length being called ends of (a room

2) the reactants are injected into the flow in a distributed manner along the length of the chamber and mixed with the reaction products present in the chamber

3) the rate of rotation of the mixture in the chamber and the characteristics of the injection of the reagents into the chamber are such that the reactants are mixed with the reaction products in less than one turn around the axis of the chamber

2) Process according to claim 1 characterized in that the reactants are a fuel and an oxidizer, the process then being called a combustion process and the combustion chamber reactor,

3) Process according to any one of the preceding claims characterized in that the reaction between the reagents takes place less than one turn after their introduction into the chamber. 4) Process according to any one of the preceding claims, characterized in that the reaction products exit either by at least one of the ends of the chamber or by a slot-shaped strip oriented in the direction of the length of the chamber, or both ways

5) Device for implementing the method according to any one of the preceding claims, characterized in that the injection into the flow of at least one of the reagents is made by at least one aerodynamically shaped pipe vis- with respect to the flow that will be called introduction pipe.

6) Device according to claim 5 characterized in that the fluid which passes through an introduction conduit out of this pipe to the flow by at least one orifice or slot located on the trailing edge of this pipe.

7) Device according to any one of claims 5 and 6 characterized in that at least one of the introduction pipes injecting a reagent into the flow has a common wall with at least one pipe injecting another reagent into the flow .

8) Device according to any one of claims 5 to 7 characterized in that at least one section of an introduction pipe is either parallel to the axis of the chamber, or approximately perpendicular to the axis of the chamber .

9) Device according to any one of claims 5 to 8 characterized in that one or more introduction lines are fed directly or or via at least one pipe called intermediate pipe, of aerodynamic shape vis-à-vis the flow, by a so-called supply pipe approximately parallel to the axis of the chamber s 10) Device according to the claim 9 characterized in that at least one supply line is located approximately in the axis of the chamber.

11) Device according to any one of claims 9 and 10 characterized in that in the near part of the branch of an introduction line on the pipe which feeds, the angle between the direction of flow in these two pipes is an acute angle.

12) Device according to any one of claims 9 to 11 characterized in that at least some introduction pipes are bent perpendicularly to their trailing edge to facilitate the passage of reagents of the pipe which feeds these lines of introduction to these introductory lines. 0 13) Device according to any one of claims 5 to 12 characterized in that the introduction lines are fed directly or via intermediate pipes, by at least one feed pipe located approximately in the axis of the chamber and in that all of these pipes can be threaded into the combustion chamber5 of a boiler through the orifice reserved for the installation of a conventional burner, so that this assembly can be easily substituted for a classic burner 14) Device according to any one of the preceding claims characterized in that it comprises means for adjusting the amount of each reagent introduced into the chamber as a function of a temperature or a content of a component, for example oxygen , mixture coming out of the chamber.

15) Carbonaceous material gasification device characterized in that it comprises a high temperature gas elevating device according to any one of the preceding claims.

16) Device according to any one of the preceding claims characterized in that, in addition to the reactants, is introduced into the chamber, a material which will be mixed with the mixture of reagents and reaction products and will undergo different transformations related thereto the chemical and thermal conditions that prevail in the room.