EP2441512A1

EP2441512A1 - Injector

Info

Publication number: EP2441512A1
Application number: EP10013654A
Authority: EP
Inventors: Hans-Rudolf Himmen; Ron C. Dr. Lee; Albert Jost
Original assignee: Linde GmbH
Current assignee: Linde GmbH
Priority date: 2010-10-14
Filing date: 2010-10-14
Publication date: 2012-04-18

Abstract

The invention describes an injector for the injection of a first fluid into a second fluid streaming in a main channel, whereby the injector comprises at least one inlet for said first fluid and a first group of outlet openings for said first fluid, whereby said first group of outlet openings is connected to a conduit means. The first fluid is injected through two different groups 5, 6 of outlet openings 5a, 6a with independent conduit means 7, 8.

Description

The invention describes an injector for the injection of a first fluid into a second fluid streaming in a main channel, whereby the injector comprises at least one inlet for said first fluid and a first group of outlet openings for said first fluid, whereby said first group of outlet openings is connected to a conduit means. The invention is further related to a process for injecting a first fluid into a second fluid streaming in a main channel by an injector and to the use of such an injector and process.
Oxygen enriched air is used as oxidizing agent for oxidation processes in a lot of chemical reactors. Therefore the oxygen is injected into an air stream, whereby an equal distribution of the oxygen in the air stream has to be achieved. Otherwise a local increased concentration of oxygen leads to points with increased temperature (hot spots) in the downstream chemical reaction. Such hot spots are negative for the chemical reaction (locally unbalanced chemical equilibrium) and could induce damages in the reactor.
A device for the mixing of two different gas streams is disclosed in EP0474524 . A first fluid is injected into a second fluid streaming in a main channel. The injector for the injection of the first fluid is partial positioned in the main channel. The outlet end of the injector is coaxially oriented in the main channel and equipped with radial outlet channels directed away from the central axis of the main channel. Additionally the injector is equipped with transverse baffles to induce a rotational motion of the injected first fluid around the central axis of the main channel.
Catalytic fixed bed reactors could be cooled by direct cooling with a cooling fluid. The cooling fluid itself is often cooled by liquid nitrogen. Thereby the liquid nitrogen is injected by an injector in the main channel of the streaming cooling fluid. Such an injector comprises a tube which is closed at the lower end and positioned in the main channel by a connection nozzle. The liquid nitrogen is injected against the flow direction of the cooling fluid by lateral openings in the tube.
Usually an adjustment of the amount of liquid nitrogen injected into the cooling fluid is necessary during the cooling process of the fixed bed reactor. Such an adjustment of the amount of nitrogen injected into the cooling fluid leads to pressure changes. The number and the size of the outlet openings of an injector are given and constant. Therefore a reduction of the amount of applied nitrogen to the injector leads to a reduction of the pressure drop of the injected nitrogen from the interior of the injector to the surrounding of the injector. An increased amount of applied nitrogen induces an increased pressure drop vice versa. A change in the pressure drop induces a change in the spraying pattern of the injected nitrogen in the channel. In particular, a decrease in pressure drop can lead to inefficient spray formation and incomplete vaporisation of the liquid nitrogen. Such a change in the spraying pattern and incomplete vaporisation can lead to contact of liquid, not vaporised, nitrogen and the walls of the main channel. Such "cold spots" could lead to possible damages of the side walls of the main channel.
Therefore changes in the spraying pattern induced by changes in the pressure drop leading to "hot spots" (in the case of oxygen introduction) or "cold spots" (in the case of nitrogen introduction) have to be avoided.
A process and a device for injecting a first fluid into a second fluid streaming in a main channel are disclosed in DE102006007506 . The first fluid is injected by an injector comprising an injection chamber and at least one outlet opening. The injector further comprises means for an adjustment of the pressure drop. A restricting means e.g. formed as a cone is moved vertically in the injection chamber to adjust the pressure drop at the outlet openings.
The object of the present invention is an alternative injector and a process for injecting a first fluid into a second fluid streaming in a main channel, which ensure an easy adjustment of the pressure drop of the injector in a given range without moving parts.
This object is achieved by an injector comprising a second group of outlet openings for said first fluid, whereby said second group of outlet openings is connected to a second conduit means, which is not connected to said first group of outlet opening.
According to the invention the injector comprises more than one group of outlet openings. Each group of outlet openings is connected with a separate conduit means. These separate conduit means ensures an independent delivery of the first fluid to the individual group of outlet openings. Depending on the desired amount of first fluid the individual flow rate is regulated for each group of outlet openings. In accordance to the inventive idea the individual flow rate for the separate conduit means and therefore for the individual group of outlet openings could be adjusted between zero and a certain value.
The regulation of the flow rate in the separate conduit means is the inventive idea. In the simplest example of the invention the injector has two groups of outlet openings each connected with a separate conduit means. In the low flow rate range only one group of outlet openings could be used. In this range the flow rate of the second group of outlet openings and therefore in the second conduit means is adjusted to zero. An increased flow rate would lead to an increased pressure drop at the outlet openings and therefore the spraying pattern would change. Further, an excessive pressure drop may not be reasonable to provide because of pumping or pressure limitations. If the pressure drop would exceed a given value, the flow rate of the second group of outlet openings and therefore through the second conduit means would adjusted to a certain value different from zero. This leads to a decreased pressure drop at both groups of outlet openings and therefore to the desired spraying pattern. The same situation is vice versa. A decreased flow rate leads to a decreased pressure drop. If more than one group of outlet openings are used, the pressure drop could be decreased under a given value and would be therefore outside the given range. A reduction of the used groups of outlet openings would lead to an increased pressure drop at the remaining groups of outlet openings. This would increase the pressure drop at the remaining groups of outlet openings into the desired range.
The inventive injector ensures a pressure drop within a determined range. In dependence on the flow rate one or more groups of outlet openings with the respective conduit means would be used and the first fluid would be flow through one or more group of outlet openings and respective conduit means
Preferably each group of outlet openings consists of one or more outlet openings. The number of outlet openings per group and therefore per individual conduit means could be adjusted to the current conditions in dependence on the geometry of the main channel, minimum and maximum amount of first fluid to be delivered, temperature and/or composition of the second fluid etc.
In a preferred embodiment said first group of outlet openings is connected via a conduit means to a first inlet for said first fluid and said second group of outlet openings is connected via said second conduit means to a second inlet for said first fluid. The connection of each group of outlet openings to a separate inlet for the first fluid is the simplest way to adjust the individual flow rate in each conduit means and therefore at each group of outlet openings.
According to another embodiment the injector comprises at least a third group of outlet openings, whereby said third group of outlet openings is connected to a third conduit means. This embodiment of the invention is suitable for applications which require a very broad range of amount of the first fluid which has to be injected in the second fluid. Even at a large total amount of the first fluid the pressure drop at the individual group of outlet openings could be adjusted in a relatively narrow range.
Advantageously at least one outlet opening, preferably all outlet openings, is designed as spraying nozzle with a v-type opening. These so-called VeeJet nozzles are very well established in the state of the art especially in a cryogenic environment. Such v-type openings provide a good spraying pattern in a very compact design.
According to another embodiment of the invention at least one outlet opening, preferably all outlet openings, is designed as simple bore hole. The injector according to this embodiment of the invention could more cheaply manufactured. Preferably the outlet openings are configured to form a spray.
An injector comprising a combination of spraying nozzles and simple bore hole as outlet openings could be advantageously under certain conditions. Such an injector could be easily designed according the conditions of the application where the injector is used and provide greater flexibility in directing the sprays and controlling the flows.
According to another embodiment the first and/or the second conduit means is equipped with an on/off valve. An on/off valve is the simplest and cheapest possibility to adjust the flow rate in the individual conduit means between zero and a certain value. The on/off valve could be positioned directly in the individual conduit means or at the inlet, if the injector is equipped with individual inlets. In this embodiment of the invention the flow rate of the first fluid is adjusted and the on/off valve is used to switch the first and/or the second group of outlet openings on or off. Thereby the pressure drop at the outlet openings is controlled by the on/off valve/s.
The object of the invention is further achieved by a process for injecting a first fluid into a second fluid streaming in a main channel, whereby the first fluid is introduced via an inlet into an injector, feed by a first conduit means to a first group of openings and injected through the openings into the second fluid stream, and whereby the injector is positioned at least partially into the main channel, characterised in that in dependence on the desired amount of first fluid, which has to be introduce into the second fluid, said first fluid is injected through said first group of openings alone or through said first group of openings in combination with at least a second group of openings, which is connected with a second conduit means different from said first conduit means.
According to the inventive process the first fluid is injected in the second fluid by more than one group of outlet openings whereby each group of outlet openings is connected with an individual conduit means. In dependence on the desired flow rate of the first fluid the first fluid is injected through one or more groups of outlet openings. At low flow rates the first fluid is injected through only one group of outlet openings. An increased flow rate would lead to an increased pressure drop at the outlet openings. The increased pressure drop would lead to change in the spraying pattern. The inventive idea is the control of this pressure drop. The pressure drop is kept in a given range by the inventive process. If the flow rate is increased in such a way that the pressure drop would exceed the desired range by using only one group of outlet openings, the first fluid is injected by more than one group of outlet openings. If the same flow rate is distributed over more than one group of outlet openings the pressure drop would be lower than by using only one group of outlet openings. The same procedure is used vice versa. A decreased flow rate leads to a decreased pressure drop. If more than one group of outlet openings are used, the pressure drop could be decreased under a given value and would be therefore outside the given range. In such a case the spraying pattern could be destroyed in the first fluid is introduced drippingly. This would immediatly lead to a incomplete vaporisation and therefore the establishing of cold spots. A reduction of the used groups of outlet openings would lead to an increased pressure drop at the remaining groups of outlet openings. This would increase the pressure drop at the remaining groups of outlet openings into the desired range. According to the inventive process the first fluid is delivered to more than one group of outlet openings by individual conduit means for the individual group of outlet openings. The flow rate at each group of outlet openings is adjusted separately.
According to a preferred embodiment of the invention the pressure drop of the first fluid from the injector to the main channel is kept in a defined range by the use of at least a second group of outlet openings. According to this embodiment of the invention the first fluid is always injected through the first group of outlet openings. In dependence on the desired amount of the first fluid, the first fluid is injected through a second group of outlet openings. If the pressure drop of the fluid would exceed a given value, the second group of outlet openings is used. If the pressure drop would fall below a given value, the second group of outlet openings would not be used.
Preferably the flow of the first fluid through said second conduit means and said second group of outlet openings is regulated by an on/off valve. According to this embodiment of the invention the second group of outlet openings could be switched on or off.
In another embodiment of the invention the first fluid is injected through more than two groups of outlet openings each connected with an independent conduit means. This embodiment of the invention is suitable for large amounts of the first fluid which has to be injected in the second fluid.
Preferably said first fluid is injected into said second fluid by a spraying nozzle with a v-type opening, a simple bore hole or a combination of both.
The use of the inventive injector for injecting liquid oxygen, liquid nitrogen, liquid air or other liquid inert gases as argon into a fluid stream is very advantageously.
The injector and the process according to the disclosed invention exhibit a number of advantages. The present invention ensures a pressure drop at the outlet openings within a defined range. Therefore a well distributed flow pattern of the out coming first fluid within the second fluid is achieved. The invention is suitable for the injection of liquid oxygen or liquid nitrogen without establishing "hot spots" or "cold spots". According to the invention there is no need for moving parts to adjust the pressure drop at the outlet openings.
An embodiment of the invention is described in the following figures. The figures show:

Figure 1: an embodiment of the inventive injector
Figure 2: a pressure drop over flow rate diagram of an embodiment of the inventive process.

Figure 1 show an embodiment of an inventive injector 1. The injector 1 is positioned in the main channel 2 by the connection nozzle 3. The second fluid (e.g. a nitrogen stream or a cooling fluid) 4 is streaming as indicated by the arrow 4. The injector comprises two groups of outlet openings 5, 6 whereby each group of outlet openings consists of two v- type nozzles 5a, 5b, 6a, 6b as outlet openings. The first group 5 of outlet openings 5a, 5b is connected by the first conduit mean 7 to the inlet 10 for the first fluid (e.g. liquid oxygen or liquid nitrogen). The second group 6 of outlet openings 6a, 6b is connected by the second conduit means 8 to a second inlet 9 for the first fluid. The shown injector could be used for instance for the injection of liquid nitrogen into a cooling fluid. In this example the first conduit means 7 would be a tube with a diameter of 0.5" (12.7 mm) which is positioned within the second conduit means 8, a tube with a diameter of 1.1" (28 mm). The minimum flow rate of nitrogen is 500 Nm³/h in this example. The maximum flow rate of nitrogen is 5000 Nm³/h. The maximum allowable pressure drop at the outlet openings 5a, 5b, 6a, 6b is 15 bar. The minimum allowable pressure drop at the outlet openings 5a, 5b, 6a, 6b is 2 bar.
Figure 2 discloses an embodiment of the inventive process using the injector shown in figure 1. The first group 5 of outlet openings 5a, 5b is always fed with liquid nitrogen through the first conduit means 7, while the second group 6 of outlet openings 6a, 6b is fed through the second conduit means 8 equipped with an on/off valve (not shown in figure 1). The behaviour of the pressure drop in dependence on the flow rate using only the first group 5 of outlet openings 5a, 5b is represented by the curve 11. The behaviour of the pressure drop in dependence on the flow rate using both groups 5, 6 of outlet openings 5a, 5b, 6a, 6b is represented in curve 12. According to the invention the pressure drop at the outlet openings 5a, 5b, 6a, 6b is always adjusted in a defined range, in this example between 2 bar and 15 bar. As pointed out above the first group 5 of outlet openings 5a, 5b is continuously fed with liquid nitrogen. According to curve 11 the pressure drop at the outlet openings 5a, 5b is increasing with the increased flow rate. If the maximum defined pressure drop is reached (15 bar in this example) at point 13, the on/off valve is opened and the first fluid is injected through groups 5, 6 of outlet openings 5a, 5b, 6a, 6b. This leads to a decreased pressure drop at the outlet openings 5a, 5b, 6a, 6b (point 14 in figure 2). Therefore the flow rate could be easily increased further up to the defined maximum of 5000 Nm³/h without leaving the defined range of pressure drop of 2 to 15 bar. A decreased flow rate would lead to the opposite situation. As shown in curve 12 a decreasing flow rate leads to a decreased pressure drop. If the minimum defined pressure drop of 2 bar is reached at point 15 the second group 6 of outlet openings 6a, 6b is switched off. This leads to a resulting pressure drop of 8 bar (point 16 in figure 2) within the defined range. A further decrease of the flow rate would be in line with the curve 11 in figure 2. Therefore a pressure drop within a defined range is ensured in this embodiment of the invention.

Claims

Injector for the injection of a first fluid into a second fluid streaming in a main channel, whereby the injector comprises at least one inlet for said first fluid and a first group of outlet openings for said first fluid, whereby said first group of outlet openings is connected to a conduit means, characterised in that the injector comprises a second group of outlet openings for said first fluid, whereby said second group of outlet openings is connected to a second conduit means, which is not connected to said first group of outlet opening.
Injector according to claim 1, characterised in that each group of outlet openings consists of one or more outlet openings.
Injector according to claim 1 or 2, characterised in that said first group of outlet openings is connected via a conduit means to a first inlet for said first fluid and said second group of outlet openings is connected via said second conduit means to a second inlet for said first fluid.
Injector according to any of the claims 1 to 3, characterised in that the injector comprises at least a third group of outlet openings, whereby said third group of outlet openings is connected to a third conduit means.
Injector according to any of the claims 1 to 3, characterised in that at least one outlet opening, preferably all outlet openings, is designed as spraying nozzle with a v-type openings.
Injector according to any of the claims 1 to 3, characterised in that at least one outlet opening, preferably all outlet openings, is designed as simple bore hole.
Injector according to claim 5 or 6, characterised in that the injector comprises a combination of spraying nozzles and simple bore hole as outlet openings.
Injector according to any of the claims 1 to 7, characterised in that the first and/or the second conduit means is equipped with an on/off valve.
Process for injecting a first fluid into a second fluid streaming in a main channel, whereby the first fluid is introduced via an inlet into an injector, feed by a first conduit means to a first group of openings and injected through the openings into the second fluid stream, and whereby the injector is positioned at least partially into the main channel, characterised in that in dependence on the desired amount of first fluid, which has to be introduce into the second fluid, said first fluid is injected through said first group of openings alone or through said first group of openings in combination with at least a second group of openings, which is connected with a second conduit means different from said first conduit means.
Process according to claim 9, characterised in that the pressure drop of the first fluid from the injector to the main channel is kept in a defined range by the use of at least a second group of outlet openings.
Process according to claim 9 or 10, characterised in that the flow of the first fluid through said second conduit means and said second group of outlet openings is regulated by an on/off valve.
Process according to any of the claims 9 to 11, characterised in that the first fluid is injected through more than two groups of outlet openings each connected with an independent conduit means.
Process according to any of the claims 9 to 11, characterised in that said first fluid is injected into said second fluid by a spraying nozzle with a v-type opening, a simple bore hole or a combination of both.
Use of an injector according to any of the claims 1 to 8 for injecting liquid oxygen, liquid nitrogen, liquid air or other liquid inert gases as argon into a fluid stream.