WO2007074222A1

WO2007074222A1 - Device and method for injecting a liquid into a pipeline

Info

Publication number: WO2007074222A1
Application number: PCT/FR2006/002709
Authority: WO
Inventors: Emmanuelle Petitjean; Bernard Cottard
Original assignee: Total France
Priority date: 2005-12-27
Filing date: 2006-12-12
Publication date: 2007-07-05
Also published as: FR2895287B1; FR2895287A1; EP1982107A1

Abstract

The invention relates to a device (8') for injecting a liquid into a pipeline (5) comprising a cylinder (1'), which is substantially shaped in the form of a tube of a given axis, closed at the end (2') thereof, partially arranged inside said pipeline (5) and open at the other end thereof supplied with a liquid. The inventive device (8') is characterised in that it comprises incorporated into the wall of said cylinder (1') at least one orifice (3a, 3b, 3c, 3d) corresponding to the end of an injection channel (4a, 4b, 4c, 4d) which is open at both sides (3a, 3b, 3c, 3d, 7') and arranged substantially in a perpendicular position with respect to the longitudinal axis of the cylinder (1') thereinside. A method for operating the device (8') for injecting a liquid into the pipeline (5), in which a liquid and/or gaseous flow runs, is also disclosed.

Description

Device and method for injecting liquid into a pipeline

The present invention relates to a device for injecting liquid into a pipe where a gaseous fluid can circulate, making it possible to obtain a jet substantially parallel to the wall of the pipe, as well as the method associated with injecting the liquid with such a device.

Most of the catalytic reforming processes currently used in petroleum refineries for the manufacture of gasolines involve periodic catalyst regeneration, the main objective of which is the combustion removal of coke accumulated on the surface of said catalyst during the catalytic reaction. This regeneration is carried out in situ, that is to say inside the reactors, by complete shutdown of the process and implementation of a specific regeneration cycle. During this catalyst regeneration operation, hot gaseous hydrochloric acid is formed by elution of the chlorine contained on the catalyst by the water resulting from the combustion of the hydrocarbons contained in the coke, this formed acid then being capable of corrode or erode the metal parts of the installation and, in particular, the cold walls located downstream of the last reactor.

To protect these cold parts catalytic reforming plants against acid corrosion, it is known to circulate a buffer solution through what is commonly called an anti-corrosion loop. The neutralization of the hydrochloric acid formed during the entire regeneration cycle is obtained by a booster solution which is injected continuously into the pipe of said loop. Sodium injection is done in known manner by means of an injection pipe, also called injection rod, which has the shape of a closed tube at one of its ends and whose wall is pierced, close to this closed end, an orifice large enough not to cause excessive pressure drop during the injection of soda. The closed end of the tube and the hole pierced in the wall thereof are introduced into the pipe of the anti-corrosion loop via an orifice or via a short inlet tube having an internal diameter substantially equal to or slightly greater than the outer diameter of the injection rod. By using in its installations a single orifice injection nozzle as described above, and as commercially available, the Applicant has observed at the level of the pipe located immediately downstream of the soda injection point corrosion and / or erosion, which it attributed to the impact of the soda jet on the wall of said pipe.

Tests on pilot plants have indeed shown that the jet of soda issued from known injection rods, not in a direction perpendicular to the longitudinal axis of the pipe and parallel to its wall, but obliquely, hitting the latter to a short distance downstream of the injection point.

The Applicant has therefore tried to modify the design of soda injection rods commonly used in the art in order to obtain an injected liquid jet having an orientation substantially parallel to the wall of the pipe, generally having for objective to improve the liquid-gas contact for a better neutralization of the hydrochloric acid formed, and especially not to expose said wall to a high alkalinity downstream of the injection point.

In addition, the new injection device must be identical to the art, easy to introduce and withdraw into the pipe via orifices or circular inlet tubes of small diameters, already existing in the anti-lock loops. corrosion of reforming facilities.

After numerous tests concerning different geometries of ejection orifices, various nozzle and insert systems intended to modify the flow of the liquid at this ejection orifice, the Applicant has developed an injection device may contain multiple holes having ejection channels open on both sides and extending perpendicularly inwardly of an injection manifold disposed within the pipe. This new device makes it possible to satisfy the requirements indicated above, that is to say to inject the liquid into a jet that is substantially parallel to the wall of the pipe in order to minimize the effects of preferential impacts on the internal wall of the pipe. said pipeline.

The invention therefore relates to a device for injecting liquid into a pipe, comprising, preferably consisting of, a pipe having substantially the shape of a tube of given axis, said pipe being closed at one end and intended for to be located in part inside said pipe, and said pipe being open at its other end which is intended to be supplied with liquid, said device being characterized in that it comprises, in the wall of said pipe, at least one corresponding orifice at one end of an ejection channel open on both sides and disposed substantially perpendicular to the longitudinal axis of the tubing within said tubing.

Preferably according to the invention, each channel is substantially cylindrical in shape, of cross section substantially equal to the section of the corresponding orifice.

In the device according to the invention, the single single orifice provided on the injection rods of the state of the art has therefore been replaced by at least one same orifice which is one of the two ends of a channel disposed in the tubing, substantially perpendicular to the longitudinal axis of the pipe, said device being arranged substantially perpendicular to the longitudinal axis of the pipe so that the injection is substantially parallel to the tube wall.

The size of this channel or of these ejection channels determines inter alia the height of the spray jet and the pressure drop of the tubing. One or more ejection channels extends generally perpendicular to the longitudinal axis of the tubing within said tubing. A length of said channel substantially equal to 10% to 90%, preferably 20% to 80% of the internal diameter of the tubing, has been found to give satisfactory experimental results.

In the device according to the invention, the tubing and the ejection channels may adopt any type of shape and are preferably of substantially cylindrical shape. The ejection channels may also be slightly frustoconical with a convergence towards the outside of the tubing, in other words towards the corresponding orifice.

The optimum number of orifices will depend on the diameter of these, and all the orifices will be aligned along the longitudinal axis of the tubing. Indeed, the overall length of the series of orifices is limited by the diameter of the pipe in which the liquid must be injected. The number of orifices is therefore lower as the size of each orifice, and the distance between two orifices, are large. It is also important to take into consideration not only the total length of the series of orifices, but also the total area of the opening of all the orifices. The more important it is, the lower the pressure drop will be.

The number of orifices is generally from 2 to 7, preferably from 3 to 7, in particular from 4 to 6. The Applicant has in particular obtained the best results in terms of pressure drop and ejection quality of the jet for a number of orifices equal to 4 or 5.

The orifices disposed on the injection pipe must generally be relatively close to each other. Indeed, the total length of the series of orifices should generally not exceed the internal diameter of the pipe in which it is a question of injecting the liquid, and too great a distance between two orifices would imply consequently a smaller number orifices or smaller openings, which would inevitably result in too much pressure drop. In a particularly preferred embodiment, the ejection ports on the tubing are adjacent to each other. As an indication, the distance separating two adjacent orifices is preferably at most equal to the diameter thereof.

As explained in the introduction, the problem underlying the present invention was the existence of corrosion phenomena due to excessive soda concentrations near the wall of the pipe. In order to avoid in the process of the present invention such excessive concentrations in the direct vicinity of the wall of the pipe, it is recommended to maintain a minimum distance between the outer ports of the pipe and the wall of the pipe. In a preferred embodiment of the invention, the distance between the first orifice and the wall of the pipe is equal to at least 15% of the internal diameter of the pipe and the distance between the last orifice and the wall of the pipe is equal to at least 15% of the inside diameter of the pipe. In other words, the total length of the orifices (including the orifices) on the soda injection pipe is at least 30%, preferably at least 40% less than the internal diameter of the pipe, and the first orifice and the last orifice are equidistant from the wall of the pipe. The set of orifices is thus centered in the pipe.

All the channels can have substantially the same length, but it is also envisaged according to the invention channels such as the length of each of said channels may be variable depending on the position of said channel relative to the center of the pipe. In one embodiment of the invention, the length of each of the ejection channels is progressively greater from the first channel farthest from the closed end of the tubing to the last channel closest to said end. For example, the end of the body of the ejection channels extending inside the tubing is tapered with an inclined slope directed towards the open end of the tubing. This last embodiment is particularly interesting and will be described hereinafter with reference to FIG.

Preferably, the diameter of each ejection port is 20% to 80%, preferably 30% to 60% of the internal diameter of the tubing.

As explained in the introduction, the device of the present invention is used to inject into a pipe where circulates a gas and / or liquid flow, usually a gas flow, a liquid in a direction substantially parallel to the wall of said pipe. For this, the end provided with orifices of said injection pipe is inserted into the pipe, perpendicular to the axis thereof.

The present invention therefore also relates to a method of implementing the device according to the invention described above. More particularly, the subject of the invention is a process for injecting a liquid into a pipe where a liquid and / or gaseous flow circulates, comprising:

(a) the insertion into said pipe, by a tube or an inlet orifice present in it, of the closed end of the injection device according to the invention as described above, so that the or the orifices are oriented downstream of the flow flowing in said pipe, and

(b) introducing the liquid through the open end of the tubing at a pressure sufficient to cause the injection of said liquid into the pipe.

By "circulating flow" in said pipe, according to the invention is meant main flow circulating in said pipe.

Preferably, during step a), the insertion is such that said orifices are all located in said pipe. In a preferred embodiment, the method according to the invention is such that gas flow circulates in the pipe. The method according to the invention can of course be used to inject and spray any liquid in a pipe where circulates any type of gaseous fluid, that is to mix intimately with the liquid. However, in a preferred embodiment of the invention, the pipe is a pipe of a catalytic reforming plant, located downstream of the last reforming reactor and upstream of the cooler and the separator tank, the gas stream (gas flowing through this line) is based on hydrochloric acid, preferably hydrochloric acid, formed and / or used during the regeneration of the reforming catalyst, and finally the liquid to be injected is preferably a solution based on sodium hydroxide for neutralizing gaseous hydrochloric acid.

In the context of such a reforming installation, the pipe where the gaseous flow to be neutralized circulates generally has a diameter of about 200 mm to about 600 mm, and the inlet pipe serving for the insertion of the injection pipe. generally has a diameter of from about 20 mm to about 200 mm, and preferably from about 50 mm to about 150 mm.

The present invention is explained in more detail with reference to the following accompanying figures 1 to 6, in which:

FIG. 1 represents a perspective view of a first embodiment of the injection manifold of the present invention comprising four orifices, and

FIG. 2 is a longitudinal sectional view of an injection pipe according to a second embodiment of the present invention comprising four orifices, inserted in a pipe,

FIG. 3 is a curve giving the evolution of the pressure drop (P) as a function of the number of orifices (N) for an exemplary embodiment,

FIG. 4 is a curve giving the evolution of the jet height (H) as a function of the number of orifices (N) for the same embodiment, FIG. 5 is a curve giving the evolution of the jet length (L) as a function of the number of orifices (N) for the same embodiment, and

FIG. 6 is a curve giving the evolution of the jet width (1) as a function of the number of orifices (N) for the same embodiment.

FIG. 1 shows an injection device 8 comprising an injection pipe consisting of a pipe 1 in the form of a metal tube (for example made of stainless steel), closed at one of its ends 2, and comprising a series of four circular orifices 3 aligned in the direction of the longitudinal axis of the tube 1. An ejection channel 4 opens at each of the four orifices 3. In the embodiment of FIG. ejection 4 corresponding to the four orifices have substantially the same length and are substantially adjacent to each other, each of the channels however having a cylindrical wall perfectly distinct from that of neighboring channels. According to the invention, it would also be possible for the walls of neighboring channels to be partially common. The liquid to be sprayed, injected by the open end (not shown) of the tubing, can not leave the tubing 1 through the closed end 2 and is ejected via the channels 4 and orifices 3 upwards, in one direction. which is ideally substantially parallel to the axis of the ejection channels and perpendicular to the axis of the pipe 1.

FIG. 2 shows an injection device 8 'comprising a tubing or tube 1 for injection inserted in a pipe 5 in which flows, from bottom to top (the top and the bottom being those of FIG. 2 as shown) a gaseous flow, for example a flow of gaseous hydrochloric acid to be neutralized by injection of a solution of sodium hydroxide. The injection tubing 1 is inserted into the pipe 5 via the inlet port 6 having an internal diameter slightly greater than the outer diameter of the tube 1 '. To ensure easy insertion and removal of the injection tubing 1 ', it is essential that the tube 1' has no radially outward projecting elements. Four ejection channels 4a (closest to the closed end 2 'of the tubing 1), 4b, 4c and 4d extend radially inwardly of the tubing 1 from four respective ejection ports. 3a, 3b, 3c and 3d. The four orifices 3a, 3b, 3c and 3d are oriented towards the top of Figure 2 in a direction parallel to the wall of the pipe 5 and in the direction of flow of the gas stream. This orientation is generally essential to ensure a good spray ejected liquid jet and to prevent this jet hitting the wall of the pipe 5. The neighboring channels 4a-4d have common walls.

In this embodiment, the length of the ejection channels 4a-4d increases progressively in the direction of flow of the liquid to be injected (from right to left in the figure). In addition, the assembly 7 'of the ends of the channels 4a-4d may not be straight but slightly beveled towards the open end of the tubing 1' from which the liquid arrives. It will also be noted that the first 4a and the last 4d channel are each located at a distance from the wall of the pipe 5 representing approximately 20% of the internal diameter thereof.

Advantageously, such an embodiment makes it possible, thanks to the length of the tube 3a greater than that of the tubes 3b to 3d, to better guide the flow of liquid to be injected out of the device 8 'according to the invention. In addition, the tapered portion 7 'advantageously increases the pressure of said flow.

Figures 3 to 6 are explained below in the exemplary embodiment.

Example of realization

From an injection device according to the present invention which is of the type of that of Figure 1, the Applicant has carried out pressure loss measurements and physical characteristics (height H, length L and width 1) of spray jet in different configurations where only the number N of orifices varies from 1 to 7. Dimensions of the injection nozzle: diameter 100 mm,

Length 400 mm

One end of the tubing constituting the injection device is closed while the other is used for its supply of water to be sprayed with a flow rate of 650 liter / minute and a pressure of 3 bar. The experimental conditions adopted in the present example are identical to those in force in catalytic reforming processes.

The table below groups together all the results obtained for seven different configurations of the injection device, that is to say comprising successively 1, 2, and up to 7 ejection orifices. These orifices are positioned adjacent to each other, parallel to the longitudinal axis of the tubing and extend perpendicularly to the longitudinal axis of the tubing towards the inside of the same tubing to a depth equal to 30% of the diameter of the tubing. the tubing, that is 30 mm. In the present example, these ejection channels are positioned perpendicular to the ground. In this table: the passage section corresponds to the total surface of the ejection orifices;

the opening / tubular section is the ratio of the passage section to the section of the injection manifold;

the load loss P is the difference of the bar pressures recorded upstream and downstream of the injection manifold; the height H of the jet is the measured distance (in mm) between the ejection orifice and the highest part of the spray jet; the length L of the jet is the largest distance (in mm) of the spray measured along the longitudinal axis of the injection pipe; the width 1 of the spray is the largest distance (in mm) of the spray measured along an axis perpendicular to the longitudinal axis of the ejection pipe.

Table: Loss P of charge and shape of the jet issued according to the number

N of orifices.

Figures 3, 4, 5 and 6 are graphical representations of: the pressure drop P; the height H of the jet; the length L of the jet, and the width 1 of the jet, as a function of the number N of ejection orifices present on the ejection pipe.

From the teaching of these curves, it can be seen that: the load loss P decreases as a function of the number N of orifices and tends to stabilize from three orifices installed in the tubing; the height H of the spray jet becomes relatively constant from four orifices; for the length L of the spray, it is from four orifices that it stabilizes, and finally, the width 1 is maximum for an injection manifold having four or five ejection ports.

Consequently, we see that the best results, that is to say a minimum pressure drop (less than 0.2 bar) and an optimization of the spray pattern for a good wetting of the volume of gas contained in the pipe receiving the sprayed liquid, are obtained with an injection pipe containing four or five ejection orifices. Of course, according to a preferred embodiment of the present invention, these four or five adjacent orifices should be positioned centered in the pipe.

Claims

1. Device (8, 8 ') for injecting liquid into a pipe (5), comprising a pipe (1, V) having substantially the shape of a tube of given axis (X' X), said pipe (1 , l ') being closed at one end (2, 2') and intended to be situated partly inside said duct, (5) and said duct (1, l ') being open at its other end which is intended to be supplied with liquid, said device (8, 8 ') being characterized in that it comprises, in the wall of said tubing (1, l'), at least one orifice (3, 3a-3d) corresponding to an end of an ejection channel (4, 4a-4d) open on both sides (3, 7; 3a-3d, 7 '), the device (8, 8') being disposed substantially perpendicular to the longitudinal axis of the pipe so that the injection is substantially parallel to the wall of the tube and the distance between the first orifice and the wall of the pipe being, in addition, equal to at least 15% of the inside diameter. r of the pipe and the distance between the last port and the wall of the pipe is equal to at least 15% of the internal diameter of the pipe.

2. Device (8, 8 ') according to claim 1, such that said ejection channel (4, 4a-4d) is disposed substantially perpendicular to the longitudinal axis (XX') of the tubing (1, l ') inside said tubing (1, 1 '),

3. Device (8, 8 ') according to one of claims 1 or 2, such that the length of said channel (4, 4a-4d) is substantially equal to 10% to 90%, preferably 20% to 80%. % of the internal diameter of the tubing

(1, the)

4. Device (8, 8 ') according to one of claims 1 to 3, such that the ejection channel (4, 4a-4d) has a substantially cylindrical shape.

5. Device (8, 8 ') according to one of the preceding claims, such that the ejection channel (4, 4a-4d) has a slightly frustoconical shape with an outward convergence of the tubing (1, 1 ').

6. Device (8, 8 ') according to one of the preceding claims, such that the number of ejection orifices (3, 3a-3d) is 2 to 7, preferably 3 to 7, still most preferred from 4 to 6.

7. Device (8, 8 ') according to the preceding claim, such that the ejection orifices (3, 3a-3d) on the tubing (1, I') are adjacent to each other.

8. Device (8, 8 ') according to one of claims 6 or 7, such that the distance between two orifices (3.3a-3d) adjacent is at most equal to the diameter thereof.

9. Device (8, 8 ') according to one of claims 6 to 8, such that the total length of the orifices (3,3a-3d) on the tubing (1, l') of injection is less than minus 30%, preferably at least 40%, to the inside diameter of the pipe (5), and the first port (3, 3d) and the last port (3, 3a) are equidistant from the wall (9). ) of the pipe (5).

10. Device (8) according to one of claims 6 to 9, such that all the ejection channels (4) have substantially the same length.

11. Device (8 ') according to one of claims 6 to 9, such that the length of each of the ejection channels (4a-4d) is variable depending on the position of said channel relative to the center of the pipe ( 5).

12. Device (8 ') according to the preceding claim, such that the length of each of the ejection channels (4a-4d) is progressively greater from the first channel (4a) farthest from the closed end (2'). ) of the tubing [V) to the last channel (4d) closest to said end (2 ').

13. Device (8 ') according to the preceding claim, such that the end (7') of the body (4 ') of the ejection channels (4a-4d) extending inside the tubing (1'). ) is beveled with an inclined slope directed towards the open end of the tubing (1 ').

14. Device (8, 8 ') according to one of the preceding claims, such that the diameter of each ejection orifice (3,3a-3d) is equal to 20% to 80%, preferably 30% to 60% of the internal diameter of the tubing (1).

15. A method for injecting liquid into a pipe (5) in which circulates a liquid and / or gaseous stream comprising:

(a) the insertion into said pipe (5), by a tube or an inlet (6) present therein, of the end (2, 2 ') of the injection device (8, 8 ') according to one of the preceding claims, so that the orifices (3; 3a-3d), close to the closed end (2, 2') of the pipe (1, 1 '), are directed downstream of the flow flowing in said pipe (5), and (b) the introduction of the liquid by the open end of the tubing (1, l ') at a pressure sufficient to cause the injection of said liquid into the pipe (5).

16. The injection method according to the preceding claim, such that the gaseous flow circulates in the pipe (5).

17. Injection method according to the preceding claim, such that the pipe (5) is a pipeline of a catalytic reforming plant, located downstream of the last reforming reactor and upstream of the air cooler and separator tank, in the gaseous flow is based on hydrochloric acid formed and / or used during regeneration of the reforming catalyst and in that the liquid to be injected is preferably a solution based on sodium hydroxide.