JP4967191B2 - Method and apparatus for controlling carburization of DRI - Google Patents

Description

[0001]
(Field of Invention)
The present invention is a reduction reactor containing metallic iron that acts as a reforming catalyst in a steady state, in a reduction reactor system by reforming hydrocarbons with an oxidizing agent such as water, carbon dioxide and oxygen. The present invention relates to a method and an apparatus for producing pre-reduced iron ore, directly reduced iron (DRI), etc. at a steelworks where the reducing gas used in the chemical reduction of iron oxide is generated from natural gas. The amount of carbon in the DRI can be controlled by changing the relative amounts of water, carbon dioxide and oxygen in the composition of the reducing gas supplied to the reduction reactor. The present invention produces DRI with high efficiency and high reliability without using the natural gas reformer currently used outside of the reduction reactor system, thereby making the capital and operation of the direct reduction plant Provide a process that reduces costs.
[0002]
(Background of the Invention)
A direct reduction plant for producing direct reduced iron called DRI or sponge iron (which is generally a pre-reduced material useful as a raw material for iron and steelmaking), high temperature briquette iron, etc. is 750-1050 ° C. At present, this DRI is produced by reacting a reducing gas consisting mainly of hydrogen and carbon monoxide with a bed of particulate iron-containing material in the form of lumps or pellets at temperatures in the range. Yes. Most direct reduction plants in operation today use moving bed reactors in which gas flows simultaneously with a gravity descending bed of particulate iron ore that moves down the reactor. U.S. Pat. Nos. 3,749,386; 3,764,123; 3,816,101; 4,002,422; 4,046,557; 4,336,063; 4,375,983 Nos. 4,428,072; 4,556,417 and 5,078,787 disclose examples of such processes.
[0003]
The DRI used as part of or supplied to a steelmaking electric arc furnace (EAF) should preferably contain some amount of carbon chemically bound to iron in the DRI material. Is well known. In contrast to free carbon, which can be added to the molten iron bath in the EAF as soot in the DRI or as graphite, the bound carbon is, for example, the majority of the carbon (about 70-85%) Further reduction of iron oxide contained in the DRI raw material remaining in the liquid iron bath and forming carbon monoxide further promotes the reduction of the carbon monoxide to protect the EAF wall from the radiant heat of the electric arc. Forms gas bubbles that form a "foam" slag layer on the molten iron bath that has a significant effect, or if carbon monoxide is further oxidized to carbon dioxide, It has many advantages such as supplying energy and thereby reducing electrical energy consumption.
[0004]
There has long been a long-awaited development of a direct reduction process in which DRI contains the correct amount of chemically bonded carbon that is best suited to the specific characteristics of the steelmaking operation.
[0005]
In the case of currently used reduction processes, DRI containing carbon content within a narrow range of 0.8 to 1.8% is produced, depending on the average composition of the reducing gas. Because carburization, primarily, Boudouard reaction, i.e., 2CO -> affected by C + CO _2. This reaction is an exothermic reaction and is promoted at a relatively low temperature, that is, in the range of 500 ° C to 700 ° C. Thus, by circulating a gas containing CO through the cooled discharge portion of the reactor, the carburization reaction is usually accelerated during these profiles where the DRI is cooled to ambient temperature before being released from the reduction reactor. Is done.
[0006]
Another method for producing a DRI product containing the required amount of carbon is to contact the hot DRI product with natural gas in the reactor cooling zone. Hydrocarbons in natural gas are broken down into metallic atoms used in the reduction zone, and hydrogen plus carbon atoms that combine with carbon monoxide, as in methane. This reaction is a well known reaction as disclosed, for example, in US Pat. Nos. 4,046,557 and 4,054,444. The latter U.S. Pat. No. 4,054,444 discloses a natural gas for carburizing in an intermediate zone between the reduction zone and the cooling zone of the reduction reactor to utilize the heat of DRI for the purpose of cracking hydrocarbons. Has proposed a way to supply.
[0007]
Related decomposition _reaction, CH 4 - is> C + 2H _2. Since hydrocarbon decomposition is a strong endothermic reaction, this reaction is often used in these processes to produce “room temperature” DRI products. Due to the above reaction, natural gas has been used as a coolant in certain processes such as, for example, US Pat. Nos. 3,765,872 and 5,437,708. The latter US Pat. No. 5,437,708 discloses a process in which the amount of carbon in the DRI is increased by extending the residence time of the DRI produced in the reaction zone. However, this method is not practical. This is because the residence time is extended from 5-6 hours to 9-15 hours. To do so, a larger reactor is required to obtain the same production.
[0008]
Several proposals have been made to provide the required amount of carbon bonds during the process of manufacturing high temperature DRI. U.S. Pat. Nos. 4,834,792 and 4,734,128 disclose one such method. In these patents, a reducing gas having a predetermined reducing power is produced in another reforming furnace, hydrocarbons in natural gas are converted into H ₂ and CO in the reforming furnace, and the carburized hydrocarbons are converted into Disclosed is a process that is added to the reducing gas supplied to the reactor.
[0009]
German patent OS 4437679 A1 discloses another proposal for producing a “high temperature” DRI containing a large amount of carbon. In this case, natural gas is supplied to the discharge part of the reactor in order to decompose hydrocarbons using the heat of DRI flowing downward from the reduction zone. This carburizing method is the same as the above method. The only difference is that the reducing gas is created in the reactor. However, this patent also has the disadvantage that the amount of energy that can be used to perform the endothermic carburization reaction is the heat of DRI. If the DRI must be removed at high temperatures, the degree of carburization is greatly limited.
[0010]
The present invention is an improvement over the prior art process. More particularly, the present invention discloses an improved version of US Patent No. 5,110,350 to Villarreal-Trevino et al. This US patent discloses a direct reduction process that does not use an external natural gas reformer. In this process, the reducing gas is saturated with hot water from another gas cooling device, so that the natural gas is added by water added to the reducing gas before the reducing gas stream is heated. It is generated by reforming. The mixture of natural gas, water, and recirculated gas is heated by a gas heater and sent to a reduction reactor, where all of the reforming reaction, reduction reaction, and carburization reaction are performed.
[0011]
Other patents related to the prior art include W.C. E. There is Marshall US Pat. No. 3,375,099. This patent discloses an iron oxide reduction process. In this case, natural gas or methane is partially combusted by oxygen in a well-known manner in a combustion chamber that generates hydrogen and carbon dioxide. Only a small portion of the regeneration gas can be recycled to the reactor. This is because the temperature of the gas entering the reactor is excessively lowered because there is no gas heater installed to heat the recycle stream. Therefore, the consumption of new natural gas is large, and because of this limitation, valuable reducing gas must be wasted. The consumption of oxygen is also large because all the heat necessary to raise the temperature of the reducing gas to the reduction level must be supplied by partial combustion of natural gas with oxygen.
[0012]
Dam et al. US Pat. No. 5,064,467 discloses a direct reduction process similar to German patent OS 4437679. In this process, the reducing gas is generated by partial combustion of a mixture of recirculated gas and natural gas with air or a mixture of air and oxygen. In this case, the natural gas hydrocarbon is reformed in a reduction reaction apparatus, as is well known to those skilled in the art. However, this process does not utilize high levels of humidity to reform natural gas, but uses carbon dioxide and oxygen for reforming. Since this process does not include a CO ₂ removal unit to recycle the recycle gas, the amount of gas exiting the system is about 30% of the gas exiting the reactor.
[0013]
Martinez Bella et al U.S. Pat. No. 4,528,030 discloses a reduction process that does not use an external reformer. In this process, natural gas is reformed by steam, which is the main oxidant in the reduction reactor. However, this patent raises the temperature of the reducing gas entering the reactor and supplies the energy required for carburizing the DRI, but oxygen is added to control the amount of carbon flexibly as in the present invention. do not do.
[0014]
(Summary of Invention)
One object of the present invention is to provide a method and apparatus for producing DRI containing a predetermined amount of carbon by controlling the amount of water and oxygen mixed with the reducing gas supplied to the reduction reactor. Is to provide.
[0015]
Another object of the present invention is to provide a method and apparatus for reducing iron oxide with high efficiency in a reduction reaction apparatus without using the currently used natural gas reforming apparatus.
[0016]
Other objects and advantages of the invention will be apparent to those skilled in the art and are set forth in the specification and the accompanying drawings.
[0017]
The objects of the present invention are achieved by the following method and apparatus.
[0018]
The method of the present invention efficiently produces direct reduced iron containing a predetermined amount of carbon by controlling the carburization of direct reduced iron (DRI) in a reduction system without using a natural gas reformer. In this method, the reducing gas is generated by reforming the hydrocarbon of the reducing gas with water and oxygen in the reduction system. This method is executed in a moving bed reduction reactor, the reduction reactor has a reduction zone, in the reduction zone, the particulate material containing iron oxide, at least partially, hydrogen and containing I as carbon monoxide reducing agent, the reducing gas hot containing carbon is reduced to chemically metallic iron. The method of the present invention includes introducing particulate material containing iron oxide into the upper part of the reduction zone of the reactor; and reducing the first gas of the reducing gas at a temperature in the range of about 900 to about 1150 ° C .; Supplying a single stream (feed), the hot reducing gas flows at least partially through the reduction zone, with the hot reducing gas flowing upward to reduce the internal iron oxide, Carburizing with carbon from the reducing gas fed to the reactor, thereby producing a DRI containing carbon that is chemically bonded to a controlled and predetermined extent; in the range of about 250 ° C to about 450 ° C; Removing a second stream (effluent) of exhaust reducing gas from the reduction zone at a temperature within; moving the second stream through a heat exchanger that recovers heat from the second stream; Water from two streams Removed, to purify, steps and contacting the flow of the gas directly with liquid water; first contains only the second from the part of the flow of about 10% to remove carbon dioxide CO to form a fourth stream of reducing gas (mixed reducing gas), steps and the third stream is mixed with natural gas; a step of the third stream (regenerated recycled reducing gas) the gas Increasing the amount of water in the fourth stream by contacting the water with hot water flowing out of the cooling-gas purifier; the amount of water in the fourth stream being in the range of about 5-12% Adjusting to a numerical value; heating the fourth stream to a temperature in the range of about 850 ° C. to about 1000 ° C .; and forming the first stream at a temperature of about 950 Raised to a temperature in the range of ℃ -1150 ℃ Because, the steps and mixing the fourth flow of hot gas containing oxygen; controlled from the reactor, and a step of taking out the DRI containing carbon predetermined amount.
[0019]
An apparatus for producing DRI includes a reduction reactor; a pump means and a conduit means for circulating at least a portion of the top effluent gas from a reactor in a reduction loop comprising the reduction reactor; cooling the top effluent gas A cooling and gas purification unit for purifying; a carbon dioxide removal unit; a gas heater capable of raising the temperature of the gas stream circulating in the loop to a range of about 850 ° C to about 980 ° C; Means for mixing natural gas with the recirculated top effluent gas from the reduction reactor before passing through the gas heater; recirculating gas with an amount of oxygen-containing gas before the gas enters the reactor; And means for mixing and controlling thereby obtaining a DRI product containing a predetermined amount of carbon.
[0020]
(Detailed description of preferred embodiments)
Referring to FIG. 1, reference numeral 5 indicates the entire reduction system comprising a moving bed reduction reactor 10 for chemically reducing iron oxide having a reduction zone 12 and a discharge zone 14. Natural gas is sent from a suitable source 16 to the reduction system 5 and is mixed with the regenerated reducing gas recirculated from the reactor 10 through a pipe 18. Thereafter, the mixture of natural gas and recirculated reducing gas passes through a humidifier 20, where hot water is about 5 to about 12 at a temperature in the range of about 60 ° C to about 90 ° C. A gas stream that flows through the pipe 22 with a water content in the range of volume% is in contact with the gas stream. This water is used in the reduction reaction apparatus 10 as an oxidant for reforming hydrocarbons contained in natural gas. The humidified mixture of natural gas and recirculated reducing gas is brought to a temperature of about 300 ° C. to about 400 ° C. in the heat exchanger 24 by heat recovered from the still hot gas stream exiting the reactor 10 through the pipe 26. Preheated and flows through the pipe 28 to the gas heater 30, where its temperature rises to a range of about 850 ° C to about 960 ° C. The gas heater 30 is ignited by combustion of suitable fuel from the source 32 in a manner well known to those skilled in the art. Thereafter, the hot reducing gas flows through transfer line 34 and is mixed with oxygen-containing gas from source 36. Since most of the gas flowing through the reactor 10 is recycled to the reactor, it is preferable to use pure oxygen instead of air or air containing a high concentration of oxygen. This is because nitrogen in the air accumulates in the recirculating reducing gas. Partial combustion of the reducing gas with oxygen increases its temperature to a range of about 1000 ° C to 1100 ° C. In addition to supplying energy necessary for performing the endothermic carburization reaction of DRI, hydrogen and carbon monoxide are generated from hydrocarbons contained in natural gas supplied to the reduction system 5. Reducing gas containing hydrocarbons from natural gas supplied to the reactor reduces the iron oxide in the reactor, and at the same time, oxidant contained in the reducing gas generates methane and other hydrocarbons in the reduction reactor. It converts to hydrogen and carbon monoxide by the catalytic function of DRI. The reducing gas exits the reactor 10 at a temperature in the range of about 250 ° C. to about 400 ° C. through the pipe 26 connected to the heat exchanger 24 and then through the pipe 38. Cooler-flows to gas scrubber 40 where it cools in direct contact with cooling water. The hot water generated by the chiller-gas scrubber 40 is used to humidify the reducing gas recirculated to the reactor as disclosed in US Pat. No. 5,110,350. After being cooled and the water removed, the reducing gas passes through the pipe 42 and is divided into at least two parts. The smaller flow flows through a pipe 44 having a pressure control valve 46 through which to maintain and control the pressure of the system and to remove unwanted accumulation of inert gases. The gas is purified. The larger flow of reducing gas flows through pipe 48 and is sent by pump means 50 to recirculate the gas to reactor 10. The pump means may be a blower or a compressor. After passing through the pump means 50, the gas flows through the pipe 52 and then passes through a suitable carbon dioxide unit 54, where the carbon dioxide is, for example (such as a hot carbide solution, an amine solution, etc.). ) Separated from other components of the reducing gas stream by suitable means, such as a liquid adsorption solution, a PSA (pressure swing adsorption) unit, or preferably a VSA (volume swing adsorption) unit. Carbon dioxide is separated and flows through pipe 56 and is used in various ways.
[0021]
After separating the carbon dioxide, the recirculated reducing gas flows through the pipe 18, thereby ending the cycle. The iron oxide ore 60 in the form of lumps or particles is sent to the reactor 10 through the top of the reduction zone 12 and reacts with the hot reducing gas flowing in the direction opposite to the feed direction, and finally , Extracted as DRI 62 containing the required amount of carbon.
[0022]
Otherwise, the DRI can be removed from the reduction reactor 10 at a high temperature of, for example, about 500 ° C. or higher, or a cooling gas, typically natural gas, in contact with the DRI. By cooling the DRI at the bottom of the reactor by circulation of the flow, it can also be taken out at temperatures below about 100 ° C. For this purpose, a natural gas stream is sent from a suitable source 64 to the discharge zone 14 and can be recycled to the cooling zone if it is desired, otherwise through a pipe 66. The gas is used for the purpose of reduction by transferring it to a gas reduction circuit, which is supplied to the reduction zone 12 of the reactor 10. A portion of the reducing gas recirculated by the compressor 50 for cooling can be obtained from the pipe 52, flows through the pipe 68, and finally does not mix with the natural gas 64 or natural gas. Without being coupled to the cooling-discharge zone 14.
[0023]
An example of the claimed process performed in the experimental plant where the daily DRI production is 23-25 metric tons is described below. A reducing gas of 935 ° C. to 969 ° C. having a volume composition of 5% to 9.5% of water was mixed with oxygen, and the temperature was raised to a range of 1013 ° C. to 1057 ° C. This gas was then sent to a reduction reactor and reacted with iron oxide to produce DRI with a certain degree of metallization in the range of 93.18% to 93.18%. The carbon content of the DRI product was inversely proportional to the water content in the reducing gas and was in the range of 1.15% to 3.64%. The resulting gas had a carbon dioxide content of 4.975-5.46% volume before mixing with oxygen. This amount of carbon dioxide seems to be constant in practice. The average flow rate of the reducing gas before mixing with oxygen was 2207 NCM / ton iron, and the average flow rate of oxygen mixed with the reducing gas was 57 NCM / ton iron. The amount of natural gas supplied as a supplement to the reduction system was 265 NCM / ton iron. In one cycle of the plant operation, the% capacity of the reducing gas before mixing with oxygen is hydrogen 48.25; carbon monoxide 14.52; carbon dioxide 5.02; methane 25.62; nitrogen 0.97, water 4 97; ethane 0.61 and propane 0.06. For the above composition, the carbon of the DRI product was 3.64% and its metallization was 93.18%.
[0024]
From the above description, it will be apparent that the present invention is capable of achieving the several objects of the foregoing invention. Therefore, the present invention supplies energy for DRI carburization by partial combustion with oxygen of the reducing gas supplied to the reduction reactor without using a reforming furnace to generate the reducing gas. It provides a new and highly efficient method for producing DRI containing a predetermined or controllable amount of carbon.
[0025]
Of course, the above description is illustrative only and various changes may be made to the structure of the system and its operating conditions without departing from the scope of the invention as set forth in the appended claims. Please understand that you can.
[0026]
Of course, the above description is illustrative only and various changes may be made to the structure of the system and its operating conditions without departing from the scope of the invention as set forth in the appended claims. Please understand that you can.
[Brief description of the drawings]
This specification and the accompanying drawings illustrate some preferred embodiments of the present invention and suggest various other and modified embodiments. It should be understood that these are not exhaustive of the embodiments of the invention, and that the invention can be varied and modified in various ways within the scope of the invention. Some suggestions in this specification are intended to enable others skilled in the art to understand the invention and its principles more fully and to vary the invention so that each is best suited to the conditions of a particular application. It is selected and described for the purpose of explanation so that it can be modified into the form of.
FIG. 1 is a simplified drawing of a preferred embodiment of the present invention.

Claims (23)

Without using a reformer for natural gas, in the reduction system, from 1.15% by controlling the amount of water and oxygen 3.64% for efficient production of direct reduced iron containing carbon a method, generating laden reduction gas of hydrogen and carbon monoxide as a reducing agent by modifying with an oxidizing agent naturally occurring hydrocarbons gas recirculating reducing gas and replenishment containing at least water and oxygen and, a method performed by the particulate moving bed reduction reactor having at least a reduction zone a portion is reduced to chemically metallic iron by the reducing gas of the high temperature of the material containing iron oxide,
Introducing a particulate material containing iron oxide into the upper part of the reduction zone of the reactor;
The reduction zone, and providing a supply of the reducing gas at a temperature which is within the range of 900 ° C. to 1150 ° C.,
With at least part of the iron oxide of the reducing zone is reduced to metallic iron, in order to carburizing carbon from the reducing gas, flowing a feed of said hot reducing gas through previous SL reduction zone,
A step of discharging the effluent of the reducing gas from the reduction zone,
Removing carbon dioxide from at least a portion of the effluent to produce regenerated recycled reducing gas comprising 10 vol% or less carbon dioxide;
Mixing the regenerated recycled reducing gas with natural gas to produce a mixed reducing gas;
Adjusting the water content of the mixed reducing gas to 5 to 12 vol%, and this value is inversely proportional to the carbon content, and directly determining the carbon content of the reduced iron;
Heating the mixed reducing gas to a high reduction temperature;
In addition to providing the additional energy required to carburize the reduced iron directly to the desired extent, the high temperature is used to generate hydrogen and carbon monoxide from the hydrocarbons contained in the natural gas supplied to the reduction system. Mixing the mixed reducing gas with a gas containing oxygen to raise the temperature of the mixed reducing gas to a temperature in the range of 950 ° C. to 1150 ° C. to produce a supply of the reducing gas;
Removing the carburized directly reduced iron from the reactor.   2. A method for producing directly reduced iron as claimed in claim 1, characterized in that the discharged reducing gas effluent is cooled, purified and dehydrated.   3. The method for producing directly reduced iron according to claim 1, wherein the discharged reducing gas effluent is quenched with water, and the hot effluent obtained from the rapid cooling is sent to the heater. A method characterized in that it is used to humidify the reducing gas before it is applied.   The method for producing directly reduced iron according to claim 1 or 2, wherein the water content is adjusted by bringing the mixed reducing gas into contact with water vapor.   5. The method for producing directly reduced iron according to claim 1, wherein the carbon content of the directly reduced iron is water of the reducing gas supplied to the reduction reaction device. 6. A method characterized by being controlled by adjusting the content of. A method for producing direct reduced iron according to claims 1 to any one of claims 5, the amount of carbon that frame seen write immersed in particles of the direct reduced iron, 1.1 5% -3 A method characterized in that it can be any numerical value within the range of 64%.   The method for producing directly reduced iron according to any one of claims 1 to 6, wherein the discharged reducing gas effluent and the flow of the mixed reducing gas pass through a heat exchanger, A method characterized in that heat is exchanged from the discharged reducing gas effluent to the mixed reducing gas.   The method for producing directly reduced iron according to any one of claims 1 to 7, wherein the reducing gas containing added natural gas and adjusted water content is a direct ignition heater, 850. A method characterized in that it is heated to a temperature between 0 ° C and 1000 ° C.   9. A method for producing directly reduced iron according to any one of claims 1 to 8, characterized in that carbon dioxide is removed with a volume swing adsorption device (VSA).   9. A method for producing directly reduced iron according to any one of claims 1 to 8, characterized in that carbon dioxide is removed by a pressure swing adsorber (PSA) type.   9. The method for producing directly reduced iron according to any one of claims 1 to 8, wherein carbon dioxide is removed by a removal unit using a liquid solution of amine.   The method for producing directly reduced iron according to any one of claims 1 to 11, wherein the directly reduced iron is taken out from the reduction reaction device at a temperature of 500 ° C or higher. And how to.   The method for producing directly reduced iron according to any one of claims 1 to 12, wherein the directly reduced iron is removed from the reduction reaction apparatus at a temperature of 500 ° C or higher, and thereafter A method characterized in that it is formed into a briquette at high temperature.   12. The method for producing directly reduced iron according to any one of claims 1 to 11, wherein the directly reduced iron is produced by circulating a flow of cooling gas in contact with the directly reduced iron. Is extracted from the reduction reaction apparatus at a temperature of 100 ° C. or lower.   15. The method for producing directly reduced iron according to claim 14, wherein the cooling gas comprises natural gas.   15. The method for producing directly reduced iron according to claim 14, wherein the cooling gas comprises an outflow gas from the reduction zone of the reduction reactor.   The method for producing directly reduced iron according to any one of claims 1 to 16, wherein the discharged reducing gas effluent is at a temperature within a range of 250 ° C to 450 ° C. A method characterized by. The method for producing directly reduced iron according to any one of claims 1 to 17, wherein the content value used in the step of adjusting the water content of the mixed reducing gas is the direct reduction. A method wherein the amount of carbon chemically bound to iron as Fe ₃ C is determined to be a predetermined amount. An apparatus that does not use an external reformer for reducing particles containing particulate iron oxide with a reducing gas in order to produce directly reduced iron containing 1.15% to 3.64% carbon therein. Because
A moving bed reduction reactor with a reduction zone;
Reducing gas that is returned to the reducing zone of the reactor by recirculating at least the main part of the top effluent gas from the reducing zone of the reactor as the recirculated reducing gas regenerated.・ Equipped with a loop
The loop includes a reduction zone;
A cooling and gas purification unit for cooling and purifying the top effluent gas;
A pump for circulating recirculated reducing gas through the loop and the reactor;
A carbon dioxide removal unit for removing carbon dioxide from the recycled reducing gas;
A gas heater capable of raising the temperature of the recirculated reducing gas stream circulating through the loop within a range of 850 ° C to 1000 ° C;
And means for adjusting the water content of the recycle reducing gas so that the value of 5 ~12vol%,
Means for adding natural gas to the reducing gas loop;
In addition to supplying the additional energy necessary to carburize the reduced iron directly to the desired extent, the reaction is used to generate hydrogen and carbon monoxide from the hydrocarbons contained in the natural gas supplied to the reduction system. Means for mixing a gas containing oxygen with a reducing gas stream obtained by mixing the recirculating reducing gas and natural gas before entering the apparatus;
Connected to the device.   The apparatus of claim 19, wherein the carbon dioxide removal unit is a pressure swing adsorption (PSA) unit.   20. The apparatus of claim 19, wherein the carbon dioxide removal unit is a volume swing adsorption (VSA) unit.   The apparatus according to claim 19, wherein the carbon dioxide removal unit is an adsorption unit containing a liquid solution of amine.   23. An apparatus according to any one of claims 19 to 22, further comprising preheating the recirculated reducing gas flow circulating through the loop and cooling the top effluent gas. A device comprising:

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