CHAMBER

Technical field

The present document relates to an adaptive device and system for reducing nitrogen oxide in a combustion chamber.

5

Background

Nitrogen oxide (NO _x ) is one of the major air pollutants from boilers and combustion chambers in power plants and waste-to-energy plants, i.e. from the combustion of waste in order to produce energy. They appear due to the

10 high temperatures involved in the combustion. Much of the nitrogen oxide in the flue gases of the combustion chambers can be removed by injecting reduction agents such as ammonia or urea, whereby both NO _x and the injected chemical are converted into harmless water vapour and free nitrogen gas which is a gas which is naturally occurring in air. So called selective non-

15 catalytic reduction (SNCR) systems are adapted to inject solutions of

ammonia or urea in flue gas at temperatures of around 870-1 150 °C

depending on the substance used for the reduction. These temperatures are optimal for achieving a reaction which is fast enough for almost complete consumption of the injected chemical within the available time frame. The

20 remaining un-reacted ammonia, i.e. ammonia slip, in the combustion chamber also depends on how much ammonium that is injected, and that the mixing of the flue gas and reduction agent is sufficient.

There is a desire to reduce the consumption of these chemicals, in order to reduce ammonia slip, and a desire to improve the overall efficiency of

25 the NOx reduction system.

Conventionally the injection of ammonia and urea may be performed by fixed injection lances that are mounted into the combustion chamber.

However, the position of the lances may be such that the optimal temperature window for the injection of the reduction agents is not reached. Further to this,

30 streaks of flue gas may be formed in the chamber, and if the reduction agent is injected into a flue gas streak it will not be efficiently spread in the rest of the chamber. The depth of penetration into the chamber of the conventional lances is also a limiting factor for an efficient distribution of reduction agents, in that they may not be able to penetrate the flow of flue gas, depending on

35 the temperature where the lance is positioned. In US5315914 an injection conduit is arranged to be moved in parallel with flow of the flue gases, the injection is made at a nozzle at the end of the injection conduit. In CN204051973 a lance for injection of reduction agents is arranged through a hole in the wall of the combustion chamber to be roteably moveable in the combustion chamber and compressed air and the reduction agent is arranged to be released from a nozzle at the end of the lance. In WO2013/055285 a supply device or tube is disclosed which is axially displaceable into and out of a combustion chamber through a hole in the chamber wall.

Due to the quick and substantial increase of volatile power sources, the numbers of boilers that are subject to variable load and material compound is increasing. For this reason there is a need for a device and system that efficiently can be variably positioned to inject reduction agents at a correct position in relation to the optimal temperature window and in the optimal flow of flue gas, as well as being efficiently mounted onto or into the combustion chamber.

Summary

It is an object of the present disclosure, to provide an improved device for injection reduction agents into a combustion chamber, which eliminates or alleviates at least some of the disadvantages of the prior art devices and systems.

More specific objects include providing a device for injection of reduction agents, which is vertically displaceable in a combustion chamber.

The invention is defined by the appended independent claims.

Embodiments are set forth in the appended dependent claims and in the following description and drawings.

According to a first aspect, there is provided a device for supplying at least one stream of a reduction agent to a combustion chamber, wherein said device is adapted to be at least partially inserted into a combustion chamber, and wherein said device comprises an elongated body having a central axis, wherein said elongate body comprises a first portion and a second portion, and wherein when said device is inserted into said combustion chamber said first portion is located on an inside of said combustion chamber, in which combustion chamber there is a main flow of flue gases, wherein at least one part of the first portion of the device is displaceable along the main flow of flue gases in the combustion chamber. This means that the point of injection of reduction agent or agents can be varied continuously along the direction of the main flow of flue gases. The device is thus displaceable in a direction substantially parallel to the flow of flue gases in the combustion chamber. This means that the device can be moved such that the reduction agents can be supplied or injected in the correct temperature window.

The displacement may be anyone of a translational and an angular movement.

This means that the device can either be moved for instance in a channel in a wall of the combustion chamber or be angled, i.e. levered inside the combustion chamber.

The first portion of the device may be moveable to/at an angle from a first axial position to a second angled position, wherein said angle is in the range of from 0 ^° to 40 ^° , or in the range of from 10 ^° to 30 ^° .

By first axial position is meant a position where the first portion of the device is arranged substantially perpendicular to an inside wall of the combustion chamber. This device provides for a way of in a stepless or continuous manner adjust the position of the device when it is inserted into a combustion chamber. This means that the device is able to cover a large area inside the combustion chamber for the supply of reduction agent, for instance, if the first portion is 4 meters long it may be displaced around 4 meters in height inside the combustion chamber.

The first portion may be provided with at least two nozzles, wherein said nozzles are arranged to supply said reduction agent in different directions, wherein said nozzles are arranged around the central axis at an angle of 30 to 180 ^° relative to each other.

The device may be provided with at least one array of nozzles arranged along the central axis of the first portion.

By this alternative the array may be placed such that it emits the reduction agent in one direction only.

The first portion may be provided with at least two arrays of nozzles, wherein said arrays of nozzles are arranged around the central axis at an angle of 30 to 180 ^° relative to each other.

This means that if the first portion is provided with e.g. four arrays of nozzles. These may be placed perpendicular to each other, i.e. one array of nozzles is pointed along the main flow of flue gas, one array is directed against the main flow of flue gas, and two arrays are directed to either side. This means that it is possible to supply the reduction agent in substantially all directions, i.e. 360 ^° , around the device. The nozzles directed to the sides provides for a way of supplying the reduction agent over the entire depth of the chamber.

Each array of nozzles may be divided into at least two sections.

The nozzles, array of nozzles or sections of the array of nozzles may be controllable independently from each other.

This means that the nozzles may be controlled independently, i.e. one section of an array can be controlled differently from another with regards to activation of the nozzles, the amount of reduction agent and the depth of penetration of the reduction agent. This provides not only for an even more efficient NO _x reduction, but also a way of better reducing residues from the reduction agents.

The device may further comprise a cooling arrangement.

The device may for instance be double-jacketed, and the cooling of the device may be achieved by transporting a cooling liquid between an inner and outer jacket. The cooling may also be provided by air cooling or evaporation.

The device may further be provided with sensors.

The sensors may be sensors for determining the type and amount of flue gases, the amount of ammonia in the combustion chamber, temperature etc.

According to a second aspect there is provided an arrangement comprising a combustion chamber, having a wall, and at least one device according to the first aspect, wherein said at least one device is arranged to be at least partially inserted into said combustion chamber through an opening in said wall and wherein the arrangement comprises a feed-through bushing and a displacement arrangement for adjustment of the position of a first portion of said device inside the combustion chamber, wherein said feed- through bushing and said displacement arrangement are arranged on an outside of said wall.

The feed-trough bushing provides a sealing and protection from flue gases and heat radiation escaping from the inside of the combustion chamber to the outside, while still allowing for the movement or displacement of the device inside the combustion chamber. The displacement arrangement may for instance be a continuous electrical or hydraulic actuator, and it may be arranged to either provide a translational or an angled movement of the device or lance. The device may further be fully retractable from the combustion chamber, when it is not in use or for cleaning or repair.

The arrangement may comprise at least two devices.

These devices may be inserted into the combustion chamber on opposite sides of the chamber, at the same or different levels along the main gas flow.

The feed-through bushing may comprise a protective cover.

The protective cover may be provided with a Teflon shield and may also contain a blocking gas.

The length of the first portion of the device may correspond to around half the width or diameter of the combustion chamber.

According to a third aspect there is provided a method for reducing NOx emissions from a combustion chamber, wherein said combustion chamber is provided with at least one device according to the first aspect, thus constituting an arrangement according to the second aspect, wherein said at least one device is arranged to be at least partially inserted into said combustion chamber through an opening in a wall of said combustion chamber, and wherein a feed-through bushing, and a displacement arrangement for vertical adjustment of the position of a first portion of said device inside the combustion chamber, are arranged on an outside of said wall, and wherein said first portion of the device is provided with at least two nozzles, or at least one array of nozzles, wherein said method comprises the steps of:

monitoring the temperature in at least one section inside said combustion chamber;

determining an optimal temperature window in said section for the supply of reduction agents;

adjusting the position, if necessary, by the displacement arrangement, of said device inside said combustion chamber such that the device is positioned to supply a reduction agent at or in the optimal temperature window; and

supplying at least one stream of a reduction agent to the inside of said combustion chamber, through the at least two nozzles or array of nozzles, at or in the optimal temperature window.

The temperature may be measured using various types of techniques, such as for instance AGAM which is a sonic or acoustic temperature measurement system. The measurement may provide a computer system with the temperature information, from which the computer system in turn will calculate and determine the optimal temperature window and from that calculation determine the optimal position of the device or lance. If the position of the device is outside the optimal window, the computer system will automatically send a signal to the displacement device such that the vertical position of the device is adjusted accordingly.

This method thus allows for the supply of the reduction agent at an optimal position in a very efficient manner.

The arrangement of the feed-trough bushing on the outside of the combustion chamber will ensure that no flue gases or heat is emitted through the opening in the wall, while still allowing for the device or lance to be moveable inside the combustion chamber.

The method may further comprise monitoring the flow and the direction of flow of flue gases inside the combustion chamber before adjusting the position of said device.

By determining also the flow and direction of the flow of the flue gases inside the combustion chamber, an even better determination of the positioning of the device or lance can be made.

The method may further comprise controlling said of the supply of reaction agent through at least two nozzles or through the at least one array of nozzles.

By controlling is meant that the nozzles are activated to supply the reduction agent and air, or de-activated, i.e. stopped from supplying reduction agent and air, if needed for an optimal performance.

This means that the nozzles, or array of nozzles, best positioned in relation to the optimal temperature window may be activated.

The array of nozzles may comprise at least two sections, and wherein said sections are controlled and activated independently from each other.

This means that one section of an array may be activated to supply reduction agent, while the section is not. This provides for a better way of controlling not only the reduction of emissions, but also for a better way of reducing the ammonia slip, since the amount of reduction agent supplied can be very specifically determined and dosed into the combustion chamber.

The reduction agent may be supplied to the combustion chamber simultaneously with an injection or supply of air.

By supplying air, as a carrier together with the injection or supply of the reduction agent a turbulent flow may be achieved inside the combustion chamber. The turbulent flow may further increase the effect and the retention time of the reduction agent in the combustion chamber. The carrier air may further provide for a transport of the reduction agent to an optimal zone in the chamber. The tertiary air may thus carry the reduction agent out of the lance or nozzles.

According to a fourth aspect there is provide the use of a device according to the first aspect, or an arrangement according to the second aspect, for supplying at least one stream of reduction agent into a combustion chamber.

The device or the arrangement may further be adapted for supplying air simultaneously with the at least one stream of reduction agent.

Brief Description of the Drawings

Embodiments of the present solution will now be described, by way of example, with reference to the accompanying schematic drawings.

Fig. 1 is a schematic side view of the arrangement and system for adaptive nitrogen oxide reduction.

Fig. 2 is a schematic bottom and side view of the device for adaptive nitrogen oxide reduction.

Fig. 3 is a schematic perspective view of the system for adaptive nitrogen oxide reduction.

Fig. 4 is a schematic perspective view of the system for adaptive nitrogen oxide reduction.

Figs 5 A-D are schematic views of the system showing the nozzles and the system for controlling the nozzles.

Fig. 6 is a sectional of the device for adaptive nitrogen oxide reduction. Fig. 7 is a diagram over the function of the control system illustrating one possible way of controlling the actions and the resulting effects of these actions.

Description of Embodiments

Fig. 1 illustrates an adaptive SNCR system or arrangement 1 1 , with a combustion chamber 5 having a device 1 inserted therein. Inside the combustion chamber there is a main flow of flue gas. In a combustion chamber the device 1 may in a first position be inserted perpendicular to the flow of flue gases. In Fig. 1 the device 1 is shown in an angled position. The device 1 may also be called a lance. The combustion chamber 5 may be provided with more than one device 1 . As illustrated the chamber may be provided with at least two devices 1 , 1 ' inserted from opposite directions, and at the same or different heights. It may be advantageous to construct the devices 1 such that they extend over substantially half the width of the combustion chamber such that they can penetrate the full width. The devices 1 , 1 ' may be placed such that they are aligned or off-set in relation to each other.

The device 1 is moveable or displaceable in a direction along the main flow of flue gases in the combustion chamber 5. This means that if the flow of flue gases is vertical, the device is displaceable in a vertical direction as shown by Fig. 1 .

By vertical in this respect could thus be a direction substantially parallel to the direction of gravity.

The device 1 may be retracted from and inserted into the combustion chamber 5 by an insertion apparatus 15. This apparatus may comprise for instance a slide or a rail.

As shown in Fig.1 it may further be possible to have an elevating device or lifting platform 16 for lowering and lifting the device 1 to and from ground level, for instance for simplifying repairs etc.

The insertion apparatus 15, the elevating device 16, as well as the lance 1 , may be located inside a housing 17, which may thus be arranged directly adjacent to the combustion chamber 5.

The position of the device 1 inside the combustion chamber 5 may be adjusted by a displacement arrangement 8. The displacement arrangement 8 may preferably be placed on the outside 6 of the combustion chamber.

The adjustment arrangement 8 thus provides a vertical or horizontal adjustment of device 1 inside the combustion chamber depending on the direction and flow of flue gases.

The device 1 is inserted into the combustion chamber 5 through a hole or aperture 10 in a wall 12 of the chamber. On the outside 6 of the chamber 5 there is provided a feed-through bushing 9, for protection against flue gases and heat radiation from the chamber. The feed-through bushing is adapted to allow for the displacement of the device 1 when it is inserted into the chamber 5.

As shown in Figs 2a and 2b the device 1 comprises a tubular body 2, having a first portion 3 and a second portion 4. The first portion 3 may be inserted into the combustion chamber 5, and the second portion 4 remains on an outside 6 of the chamber 5. Through the first position 3 at least one reduction agent may be injected or supplied to the combustion chamber 5. The reduction agent or agents may be supplied to reduce nitrous oxides (NOx) in the flues gas. The length L of the first portion will be adapted according to the width of the combustion chamber, and may correspond to substantially half the width or cross-section of the combustion chamber. It may also be possible to construct a device 1 where the first portion 3 substantially corresponds to the entire width or diameter of the combustion chamber.

The length L may be in range of 1 to 5 meters.

The displacement of the device 1 may be provided as a translational (not shown) or an angled movement.

In Fig. 2b the angled movement is illustrated. The lance or device is moved by leverage adjustment of the first portion 3 upstream or downstream of the flow of flue gases. As illustrated in Fig. 2b the device 1 may have a first position 19, where the first portion or at least a part of the first portion 3 is placed perpendicular to the combustion chamber. The first portion, or at least a part of the first portion, may be moved at or to an angle a, a', from a first position to a second angled position 20, 20', in an interval of 0 to 40 ^° , or preferably in an interval of 0 to 30 ^° . As illustrated in for instance Fig. 1 the device has been angled upwards in the combustion chamber to a second angled position. The device can thus be moved, i.e. adapted to a position in the combustion chamber where the temperature interval for the injection of reduction agents is optimal.

In Fig. 3 the adjustment arrangement 8 and the feed-trough bushing 9 are illustrated in more detail. As shown in fig. 3 the second portion 4 of the device 1 protrudes from the wall 12 of the chamber. The adjustment arrangement 8 is arranged on the outside 6 of the chamber wall 12, thus moving or displacing the second portion 4 such that first portion 3 is levered inside the chamber 5. The adjustment of the device 1 may be facilitated by an actuator, which may move, i.e. angle or lever the device 1 in a continuous or stepless manner. The device 1 may be suspended with a ball bearing 18 allowing for a leverage or rotating movement of the device 1 . The actuator may be hydraulic actuator or preferably an electrical actuator. The actuator is sufficiently adapted to be able to carry the weight of the device 1. The adaptive aspect of the SNCR-system is provided by displacing the device 1 in a direction parallel to the flow of flue gases inside the combustion chamber. In the case of a vertical flow of flue gases the device is adapted to be vertically displaceable. By the actuator 8 the device 1 can thus be moved to an optimum temperature interval for the injection or supply of reduction agent into the combustion chamber.

The combustion chamber may have three different types of loads or temperature intervals. The first position of the device 1 , i.e. where it is mounted or inserted into the combustion chamber may represent the temperature interval at a middle load. At a high load of the combustion chamber the optimum temperature interval is elevated inside the chamber, and the device 1 is thus adapted, i.e. displaced to this optimum temperature interval (as shown in for instance Fig. 1 ). Alternatively, when there is a low load, i.e. when the optimum temperature interval is below the optimum interval in the first position, the device is displaced or lowered to this optimum interval (not shown).

In Fig. 3 a feed-through bushing 9 for protecting the environment from heat radiation and flue gases is illustrated. The device 1 , is inserted into the combustion chamber 5 through an opening 10 in the wall 12. The first portion 3 is directed to the inside of the chamber 5, and the second portion 4 protrudes from the outside of the wall 12. The feed-through bushing 9 may comprise a protective cover 22. The inside of the protective cover 22 may be provided with a shield 23. The shield may be formed by a heat resistant material, such as for instance Teflon. The hot flue gases may be handled by providing a blocking gas inside the protective cover, thus preventing the flue gases from entering the cavity formed by the protective cover 22 through the hole 10. It may also be possible to (not shown) provide a steel brush arranged around the hole 10 to stop particles and gas from reaching the outside of the chamber. However, due to the fact that the chamber has an under-pressure the need for a blocking gas may be reduced.

The shield 23 may comprise two portions (not shown), where a first portion may be fixedly mounted and a second inner portion may be arranged such that it can follow the movement of the device 1 thus providing an efficient seal of the hole 10.

As illustrated in Fig. 4 the device 1 may be arranged on an insertion device or arrangement 15. This provides for a way of extracting the lance from the combustion chamber. The insertion device 15 may comprise a rail in which a base structure 24 that carries the device 1 may be slided. The insertion device 15 may be placed or mounted to an elevating or lifting arrangement 16 or a stand (not shown) resting on the ground floor. The insertion device may be further placed in a housing or frame 17.

As illustrated in Fig. 5A the device 1 may be provided with internal tubing 26, 27 for supplying reduction agent and air into the combustion chamber. The reduction agent and air may either be provided through constructed openings (not shown) in the wall 28 of the device, or through multiple injectors or nozzles 25. Fig. 5A only illustrates the nozzles or injectors as pipes going through the wall 28 of the device but it is to be understood that the design of the nozzles will be dependent on the desired spread etc.

Through the nozzles 25 the reduction agent 27 together with tertiary air 26 can thus be injected or supplied into the combustion chamber (Fig. 5D).

The nozzles 25 may be arranged in a linear row along the length L and central axis A of the first portion 3. Alternatively the device is provided with multiple rows of nozzles 25. The nozzles 25 may be arranged around the central axis (A) at an angle (β) of 30 to 180 ^° relative to each other as illustrated by Fig. 5B, where a distribution pattern D from the nozzles 25 is illustrated, and the first portion 3 of the device is provided with four rows of nozzles placed perpendicular, i.e. β is 90 ^° , to each other around the central axis A of the device.

The rows of nozzles may further be divided into different sections S1 , S2 as illustrated by Fig. 5B, where the rows have been divided into two different sections, such that the sections may be individually controlled or activated depending on the optimum temperature interval in the combustion chamber. It is possible to divide the rows into even more sections, and also to control and activate each nozzle individually.

The number of nozzles or injectors arranged in each row will depend on the length L of the first portion 3.

The rows of nozzles and/or the sections of nozzles may thus be controlled and activated individually, depending on where or in which direction the reduction agent is to be supplied in the combustion chamber.

In Fig. 5C a flow chart is illustrated where each section comprising four nozzles or injectors is provided with a separate feed of reduction agent 26 and tertiary air 28, and thus may be controlled and activated individually. The activation may for instance be made by opening or closing a magnetic valve 29. In Fig. 5C, the block C1 denotes section 1 (S1 ), row 1 , injector/nozzle 1 -4, block C2, denotes section 1 , row 2, nozzle/injector 5-8, block C3 denotes section 1 , row 3, nozzle/injector 9-12, block C4 denotes section 1 , row 4, nozzle/injector 13-16. Correspondingly block C5 denotes section 2 (S2), row 1 , injector/nozzle 17-20, block C6 denotes section 2, row 2, nozzle/injector 21 -24, block C7 denotes section 2, row 3, nozzle/injector 25-28, block C8 denotes section 2, row 4, nozzle/injector 29-32. According to this flow chart the device 1 thus comprises eight individually controllable portions, but this may be designed in any appropriate manner.

The adaptive system as described above provides for a way of having the device covering the entire width of the combustion chamber. The reduction agent may be supplied or injected at the area where it provides for the best effect. If for instance the optimum temperature interval is in the middle of the combustion chamber the nozzles adjacent to this location may be activated and the device may be positioned such that the reduction agent is injected at the right place. Compared to a conventional introduction of reduction agent through and at the wall of the combustion chamber the amount of reduction agent used may be significantly reduced.

The optimum temperature window for injection of reduction agent varies in the combustion chamber. In a combustion chamber with a vertical flow of flue gases this optimum temperature window is varied vertically, depending on load variations, change of fuel, increased pollution and altered operation parameters. By the system having a continuous or stepless adjustment of the vertical position of the device 1 the problems connected to the varying position of the temperature window may be greatly reduced.

If the first portion 3 is 4 m long, and with a maximum leverage of the device by a 60 ^° adjustment the tip of the first portion, can be displaced 4.6 meters in height. This range corresponds to, in a reference combustion chamber, a span of 4 meters in the optimal temperature window, between normal load and low load, at 82 and 60 ton steam/hour respectively.

The amount of reduction agent being injected may be controlled for each row of nozzle, or for each section of the row, this means that the optimal amount of reduction agent may be used at all times, thus reducing the risk of overdosage of the reduction agent and the formation of ammonia slip.

The simultaneous injection of reduction agent and air increases the turbulence in the combustion chamber, which in turn may increase the mixing of reduction agent and the flue gases. This reduces the formation of streaks of flue gas, and makes the reduction process more efficient in that the reduction agent is injected in a turbulent flow, compared to conventional systems. The creation of a turbulent flow further provides smaller differences in temperature and gas concentrations at the same height.

Since the innovative concept reduces the formation of streaks and introduces turbulent flow patterns this may provide for a longer retention time of the reduction agent in the flow of flue gas, which is beneficial not only for the reduction of NO _x but also in that it causes less formation of ammonia slip (i.e. more of the reduction agent is used).

, The device 1 needs to be cooled, to protect it from being damaged by the high temperatures. The cooling might be provided by cooling fluid cooling system, such as for instance water cooling, an air cooling system,

evaporation cooling system or by other techniques.

As illustrated by Fig. 6 one way of performing water cooling is by providing the wall 28 of the device 1 , with double-jackets, and by transporting a cooling liquid in a space 31 between an inner 30 and outer 29 jacket. The air and retention agent are transported in tubing 26, 27 on the inside of the inner jacket 30. The cooling system may be provided with double pumps (not shown).

To fully utilize the cooling effect the cooling water from the devices may be heat exchanged against for instance a district heating network, through a pressurized heat exchanger. The heated cooling water should then have a temperature around 85 ^° C. In order to avoid overheating or boiling of the cooling water the system may be provided with a safety vent and a high temperature alarm in the control system as well as activation of an automatic extraction of the device from the combustion chamber if there is a risk that the device is exposed to a too high temperature for an efficient cooling to take place or if there for some reason is a malfunction in the cooling system. The cooling need may be calculated based on conventional methods.

According to one alternative the combustion chamber may be provided with devices placed in parallel on the same height (not shown in the drawings). The need for this may be determined based on the size of the combustion chamber, as it might be necessary to have parallel lances to cover the entire width of the chamber with reduction agent.

The devices or lances will be subjected to extremely high

temperatures, particles and corrosive flue gases. The demands on the material for not only the lance, but also the nozzles and any thereto attached constructions are therefore high. The material should also be able to withstand oxidation at the high temperatures present in the chamber. It should have good characteristics also in sulphurizing and carburizing environments. Another important characteristic is that the material should have a good shape-resistance, i.e. low creep strain. Further to this, it is important that the material is weldable, and shapeable, and a high wearability.

One example of such a material is a high temperature steel called 253 MA/SS 2368/1 .4835.

The dimensions of the tubular body, and different tubes of the lance should preferably be adapted to accomadate the different media transported inside the tube, i.e. the reduction agent, the tertiary air, and where applicable, the cooling media or water. The diameter of the air flow tube may be assumed to be 0.2 m, having a maximum air flow speed of 15 m/s. If the lance is cooled by cooling water flowing a double-jacketed tube, a cooling water gap of 5 mm may be assumed. The diameter of the tube for

transporting reduction agent may be calculated based on a desired flow, and may be assumed to be 8 mm/lance. This gives a total diameter of the lance of approximatley 220 mm (200 + 2 ^* 5 + 8 mm).

Depending on the size of the combustion chamber the number and dimensions of the devices, the cooling water pump, the air system and the reduction agent pump may have to adapted. The control system can be used for different types and sizes of combustion chambers, as well as any software used for controlling the lances and the nozzles.

The device 1 , or the first portion 3 thereof, is the only part of the system which is placed inside the combustion chamber. This means that maintenance can be performed on most parts of the system without interfering with the operation of the combustion chamber. As the device or lance is extractable from the combustion chamber, also repairs and

maintenance can be performed on the device without interfering with the operation of the combustion chamber, other than its NOx-performance.

The adaptive SNCR system may be equipped with different types of sensors and control equipment. These sensors and control equipment may provide signals to a control system, which in turn controls and activates the function and movement of the lance and nozzles.

In order to adapt the position of the lances inside the combustion chamber to the correct temperature zone inside the combustion chamber it is advantageous to have a temperature monitoring system connected to the control system. The temperature monitoring system may comprise temperature sensors inside the combustion chamber.

An alternative temperature monitoring system may be an acoustic gas temperature measurement system (AGAM). This system may provide for a more flexible way of determining the temperature distribution inside the combustion chamber, and thus for a way of providing the control system with the relevant information on how to position and activate the lances and nozzles. The AGAM system measures the speed of sound along a number of lines across the furnace, thus providing a way of calculating the temperature profile at the specific level. An AGAM system may be installed at each level or height of the lances. This would provide a temperature profile according to which each lance can be adapted and positioned to provide the reduction agent at the optimum temperature interval.

It is further possible to monitor the amount of ammonia slip in the flue gases in real-time, by using ammonia sensors. The sensor may be placed in situ in the flue gas channel, thus providing a quick measurement of the ammonia slip, and thus a signal to the control system to control the dosage of reduction agent into the chamber.

Other sensors, such as sensors measuring the flow and direction of the flue gases may also be useable to event better control the position of the lance.

The control system itself may comprise a computer and a specific software adapted to receive input signals, that, based on the received signal, determines whether the device or lance is positioned correctly or if the nozzles are activated correctly, and to provide output signals for controlling, adjusting and activating the device and nozzles accordingly.

The input signals to the control system may comprise information from a temperature measurement, measurement of the amount of ammonia slip etc. from different measurement systems and sensors.

The output signals from the control system may comprise signals to the equipment moving and adjusting the position of the lance, or to the different arrays of nozzles or sections of nozzles to be activated or deactivated.

In Fig. 7 a control diagram over the function of the control system is provided, illustrating one possible way of controlling the actions and the resulting effects of these actions.

In step 101 the temperature inside the combustion chamber, for instance by using an AGAM measurement. In step 201 the signals and information provided by the temperature measurement in step 101 are handled, for instance by a computer and a computer program. In step 301 the control system, i.e. the computer calculates which areas or zones in the combustion chamber having an optimal temperature. In step 401 the control system checks if the lance is at the correct height or position. If the response is "no" then the control system will provide a signal to adjust position of the device in step 501 . If the device is in the correct position, i.e. the answer is "yes" in step 401 , or when it has been adjusted in step 501 , the control system determines if the correct array of nozzles are activated in step 601. If the answer is "no" the control system will provide a signal to activate the correct array of nozzles in step 701 . If the answer to step 601 is "yes" or if step 701 has been performed, the control system determines if the correct section of the array of nozzles is activated in step 801 . If the answer is "no" the control system will provide a signal to activate the correct section in step 901. If the answer to step 801 is "yes" or if step 901 has been performed, the amount of ammonia slip is measured in step 1001 . In step 1 101 the control system determines if the amount of ammonia slip is in the correct range. If the answer is "no" the control system will provide a signal to adjust the amount of reduction agent is adjusted in step 1201 . If the answer is "yes" or of the amount has been adjusted in step 1201 the control system measures the cooling water temperature in step 1301 . In step 1401 the control system determines if the temperature of the cooling water is in the correct range. If the answer is "no" the control system will provide a signal to adjust the cooling water flow in step 1501. This process may then be continuously iterated at any suitable interval or time periods.

It may further be possible to adapt the control system such that the different steps may be performed in parallel, which may be done

independently of the other steps.

The control system may also be provided with routines for protecting the device. For instance of the lance is overheated or if there is a malfunction in the adjustment system the control system may output a signal to the extraction device, thus pulling the lance out of the combustion chamber to avoid damages to the lance.