JPH01500251A - How to reduce NOx in flue gas - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] How to reduce NO in flue gas Technical field The present invention relates to reducing nitrogen oxide levels in flue gas from combustion equipment. or, more particularly, in a location where favorable reaction conditions can be obtained in the combustion apparatus. By introducing a reducing agent into the built-in cyclone separator, NO levels can be reduced. The aim is to achieve a reduction in

Background of the invention The present invention is suitable for virtually all fuels, such as solid fuels, sludges, gaseous fuels or A method to reduce nitrogen oxides in flue gas generated when similar fuels are burned This is related to. However, the present invention provides a particularly improved fluidized bed combustion system. There are some methods that can be used to manage the outflowing chimney gas to meet current environmental standards. It can be managed economically.

Wave combustion of fuel is a well known practical method.

Typically, air is introduced through a plenum, which , dispersed through the air or through a dispersion grid. Fuel flow particles and absorbents, e.g. Limestone or dolomite grains are typically heated in a furnace at a temperature range of 1400-1700'F. It flows and reacts within. This temperature is higher than the temperature at which ordinary furnaces are operated. is also essentially low. This temperature range can achieve excellent complete fuel combustion. In addition, it is also suitable for reacting sulfur oxides with absorbents in the combustion chamber. write to actually reduce TI and yellow oxide emissions from sulfur-containing fuels, The addition of graystone also reduces environmental pollution when burning coal with a relatively high sulfur content. Decrease ゛C.

Nitrogen oxides are produced when all fuels are combusted, and nitrogen in the air is heated and oxidized. It can be fixed as a substance or converted into nitrogen in fuel.

The former reaction is preferably performed at high temperatures (approximately 1800'F or higher), and However, the latter reaction can be performed at lower temperatures, such as those commonly found in fluidized bed combustion systems. degree is very important. It is related to the formation of nitrogen oxides or photochemical smock, and has a low Exposure level (NO,.

The N emitted from the combustion system can be toxic (with a TLV of 5 ppm). One of the growing concerns is minimizing the number of people.

U.S. Special Treaty No. 3,900,554 requires temperatures of 1,600-2.000°F. By injecting ammonia into the exhaust stream while in the i range, The process of non-contact reactive removal of nitrogen oxides from exhaust gas generated from It is. European Patent Application Publication No. 176.293 also describes centrifugation NOx can be controlled by injecting NH into the exhaust gas stream before entering the machine. is disclosed. Patent No. 4,335,084 discloses even higher temperatures. ing. A number of other patents describe the use of ammonia or nitrogen acids with catalysts. It discloses that it is effective in reducing chemical substances. Low temperature (e.g. 250- Some examples of these patents utilizing U.S. Patent No. 3.88 No. 7,683 (activated carbon catalyst), No. 4,056,660 (V2O5/Mn201 No. 4,010,238 (various transition metal catalysts), No. 4,002,723 (Cyanic acid catalyst), No. 4,049,777% (CrO catalyst), No. 4,031. ．． No. 185 (copper-halogenite catalyst) and No. 4,070,440 (alpha) Fe2O3 catalyst) etc. are included.

Several other U.S. patents, such as No. 3,894,141 and No. 3,8 No. 67.507 uses hydrocarbons rather than ammonia to reduce nitrogen oxides. Disclose that you are using. Still other U.S. patents, e.g. No. 5,924 and No. 4,208,386 discuss the use of urine to reduce No.I excretion. The fourth, . 1.54, No. 803 and No. 4,507゜2 No. 69 discloses another ammonia precursor. Other US patents, e.g. National Patent No. 4,119,702 and No. 4゜1.15.515 are Additives such as hydrogen, ozone and hydrogen peroxide are used to improve workability. Ru.

U.S. Pat. No. 4,218,427 discloses a fluidized bed of pulverized coal of approximately 400-700 It discloses use at temperatures of °C. U.S. Patent No. 4,181,705 , injecting ammonia or ammonia-forming precursors directly into the fluidized bed combustion zone of the furnace. No. 1, U.S. Pat. No. 3,929,967, which discloses that the and S.O.

Disclose a treatment method for flue gas containing (first of all, reduce the amount of S08 For contacting the exhaust gas with gaseous ammonia, preferably about 7'O- A temperature of 800”F is sufficient to react with virtually all of the WL yellow trioxide present. By using a quantity of gaseous ammonia, we can convert 5 (lx) as expected. This reaction results in the formation of ammonium bisulfite, rum salt, and ammonium bisulfate. The large amount of solid product produced can then be separated using a mechanical separator such as a cyclone separator. removed and subsequently processed in a high temperature electrostatic precipitator.

Ammonia is then recovered from the solid oxidation value & ammonium salt.

There are many other alternative methods that are indicated primarily for the removal of sulfur dioxide in five industrial technologies. For example, US Pat. No. 4,369,167 teaches the use of an aqueous lime solution. and here also using a suitable washing medium, e.g. dichromate solution. In particular, it is possible to include a second scum washer for removing NO. Of course, S It is also well known that limestone is added to the combustion chamber itself to reduce Ox. Is Rukoto. Ammonia is also used for flue gas treatment, especially at constant temperatures. Then, ammonium sulfate is produced by reaction with ammonia and water, and S 03 can be removed, so the use of ammonia or ammonia precursors is It is also known that it is effective in reducing SOx levels. It's here.

fish 1 of 11 One critical parameter in the effective implementation of NOx reduction methods is the reduction agent and combustion It has been found that achieving good mixing of the composition with the flue gas. another by limestone or collapsing limestone (Cab) used for SOX control. In catalysis, undesirable side reactions from the reducing agent and oxygen must be avoided. Even worse things have been discovered. Using a high temperature cyclone separator or similar injecting the reducing agent into the fluid by and at a special location in the thermocyclone. By doing so, a very effective mixing of the reducing agent and the combustion products with the flue gas is achieved. This is achieved after the particles such as limestone and CaO have been separated from each other. It has also been found that High temperature cyclone separator is lined with refractory material. or cover its outer surface with ice, water vapor, or air. Due to its ability to circulate and cool, it is suitable for operating in thermal conditions. It happens when you do something like this. Depending on the reducing agent and process conditions, the reducing agent may be a carrier. It can be added with gas or without carrier gas. This character The rear gas can be water vapor, nitrogen, flue gas, any inert gas or C is composed of a combination. Inlet or inlet in the cyclone The location of can be more or less depending on the process conditions and the 110° reducing agent used. It's decided. Process conditions to be considered when selecting the location of the inlet include flue gas temperature, flue gas composition, loading adjustment, type of reducing agent or reducing agents, and specific includes the amount of granular load, etc.

The use of high-temperature cyclone separators significantly simplifies the introduction of reducing agents, especially in the current In comparison to Equipment E, which is currently in use and has a very complex loading arrangement. If you look at it, it's obvious that it's easy.

In one preferred combination, the present invention is incorporated as part of a fluidized bed combustion system. The fluidized bed in which the fuel is burned contains an absorbent for collecting ash and sulfur, i.e. Contains limestone and similar materials and is suitable for flue smoke in the temperature range of 1400-1800°F. It generates a flow of stream. Removal of nitrogen oxides is effective, and gas cleaning equipment may be added. The present invention is also effective for all furnace systems. For example, pulverized coal or stokers or oil-burning equipment. It may be used where NOx emissions must be minimized. Wear. A cyclone (or cyclones) uses flue gas or generally some amount of heat. give constant primary convection to the surface, then) to the flue gas or then to the cyclone or other The temperature remains at an appropriate temperature even when the gas passes through the high vortex device, and this cyclone produces no combustion. Product flue gas (after entrained particles have been separated therefrom) and input reduction The arrangement is such that highly effective mixing occurs with the agent or reducing agent. smoke The path gas is then diverted to another tropospheric region or further heat exchange occurs. It may be possible to return to other parts of the troposphere.

Brief description of the drawing Figure 1 shows a schematic diagram of a standard fuel combustion system, which In general, the claimed invention can be used in many combustion systems. This represents one type of combustion, which is guided by a tact or convection section connected to the combustion furnace. The convection section includes a detour to the cyclone, which is then ultimately guided into the chimney and into the chimney. and is emitted into the atmosphere.

Figure 2 is a top drawing showing the preferred loading location on the top of the cyclone separator. There are many inlets with radial zero velocity bands passing through the top of the cyclone. The inner wall of the cyclone and the cylinder wall of the central gas outlet duct It is located approximately midway between.

Figure 3 is a vertical cross-sectional view generally taken along line 3-3 in Figure 2, and is a size 1 illustrates a generally preferred dosing device arrangement for one type of Kron separator;

Figure 4 is a schematic diagram of a NOx removal system for fluids that entrain large amounts of CaSO4. A diagram is shown in which the NOx reducing agent, e.g. urea particles, is supplied into the cyclone. The urea may optionally be mixed with some solid material, such as nickel oxide or other catalysts. It can contain media.

These particles are collected from the bottom of the cyclone and either partially or using a gas transport medium. Here, too, the gas is circulated back to the cyclone inlet duct through the gas transport vibrator. Any absorbent present has the opportunity to react further.

The 5th tJ shows a schematic M of another specific example of a circulating fluidized bed combustion system. combination, where some heat transfer is generally occurring throughout the combustion path; Subsequently, the entire fluid waves toward the cyclone, which in turn converges with the convection section. from this convection section through a bag or similar to the chimney.

Figure 6 shows a vertical section of another cyclone machine similar to the example shown in Figure 5. The figure shows the preferred location for the injection of NOx reducing agent.

You 1, 111, Ibegawa Iwasu Oni” ammonia or ammonia liberating precursors or some other similar reducing agent. , a technology used to reduce NOx in a stream of thermal combustion products, or is temperature sensitive. The overall composition of the waste stream and, most importantly, the reducing agent and lime , limestone or similar particulate materials used for SOx reduction. between the injected reducing agent and the NO8 component of the gas stream, while minimizing contact between It has already been found that individuals are sensitive to rapid and close contact. the latter The purpose of the This cyclone molecule obtained by achieving in the area of cyclone separator method There is a strong vortex present that effectively separates particulate matter from the gas stream. It has been discovered that some have already been completed. Refractory lined service Keep the Ikron separator or its metal body walls within the permissible temperature range and avoid high heat. Designed to avoid potential structural deterioration from subsequent exposure. A more standard cyclone separator with a cooled external cooling jacket is also used. Wear.

As discussed in more detail below, the gas streams to be treated are A combustion product gas stream generated from a furnace that uses air to burn carbon-based fuels. This carbon-based fuel 1 may contain nitrogen oxides and/or sulfur oxides. combustion products including nitrogen oxides and sulfur oxides. Generally speaking, countries around the world must maintain a minimum emission standard. Sea urchins are regulated. Further, as explained below, a suitable reducing agent or nitrogen oxide applied to produce an effective chemical reaction to lower the standard and meet a specific standard. into the gas stream at the appropriate location. Figures 2 and 3 are the convolutions used and A cyclone separator 11 is illustrated that is adapted for high temperature operation. Cyclone minute #Iall includes the upper body cylinder 13 in the right-hand pivoted cross section; It rests on a body cylinder 13 or a hollow frustum-shaped body cone 15, The lower end of this body cone 15 is connected to the particle outlet 17.

An exit tact 19 is placed in the center of the body cylinder, which also rotates. The diameter is approximately 30% and 80% of the inner diameter of the cylinder. Equal between. Generally, the outlet duct 19 is coaxial with the body cylinder 13. and preferably extend a practical distance during the cyclone, e.g. several feet downward. This creates an annular large opening region 21 into which the incoming gas flow flows. Recruited. A combustion product gas stream is supplied through the inlet duct 23 at a suitable temperature. , reaching a tether 25, which tethers the exit from the duct and the cyclone. Configure the entrance to the server. This kind of connecting part is against most cyclones. The cross-sectional area may be slightly smaller or the same area.

As best seen in FIG. 2, the gas flow enters the annular region 21 with the particles. line direction, where it is immediately forced outward in the direction of the area adjacent to the exterior wall, with most The minute gas inside the annular space creates a strong swirling motion, leading to the exit duct 19. There is a generally downward spiral descent along the outer surface. the only one from the cyclone The second gas outlet is designed to rise inside the outlet duct 19. The vortex develops inside the first vortex, and the gas spirals toward the L direction and travels along the inner surface of the tact. Rise. Of course, the primary purpose of the cyclone separator is to remove particulate matter or its inertia of 4 m. Therefore, it can occur immediately while moving outward toward the outer wall of the body cylinder 13 portion. The object is to reach the outlet 17 at the bottom in such a shape. Cyclone 11 Works just as well in a horizontal position as it does in a vertical position or eliminates accumulated particles It may be difficult to Because there is a tendency to It's good to be selected. Similarly, the cyclone 11 It works equally well whether it is placed on the suction side of the gas transfer device (221) or on the pressure side. move.

In order to adapt the cyclone 11 for high temperature use, the body cylinder portion 13 is Preferably, the entire inner surface of the cylindrical wall of the lower cylindrical wall is provided with a high temperature insulating layer 27. Preferably, the decone portion 15 also includes such high temperature insulation. suitable A lining layer of suitable wear-resistant firebrick material may be used or A suitable fire-resistant insulation material that can withstand the temperature (for example, aluminium-based A felt-like material can be used. Temperature and output operated by cyclone 11 [] Depending on the metal that is the material of tact 19*1, its outer surface and, if possible, its inner surface. Surfaces may also be insulated with thermal insulation material, or they may not be insulated. However However, since the outlet duct 19 does not have a load-bonding section, is it necessary to use an insulator? Little or in some cases no insulation is required. Part of cyclone body 13, the external surface of which is coated with an insulating material is cooled by a suitable method υ. For example, if a cooling jacket surrounding the outside is provided, this jacket may be A relatively cold liquid or gas refrigerant can be heated up to 8°C in a structure V of 7°C! Every time 1. Continue to flow so that the temperature can be maintained at the desired temperature. water, air, steam or Mixtures of these or examples of suitable coolants that can be applied to these cyclones for high temperature regeneration. It is.

The reducing agent or reducing agents used is 31 in one piece or one measuring instrument. (The drawing shows four inputs placed at the same angle.) ports 31a-31d), the number of these ports depends on the cyclone used. It will be generally decided according to the format. If at a realistic distance downwards Extending outlet duct or, if not used, inlet 31d or inlet 31d and 31c is N11. [slippage] J, i.e. NH, or If you don't respond, it will bypass directly to the cyclone exit tact and escape and become invalid. to avoid generally undesirable phenomena such as . All of the input ports are preferably equipped with suitable feed racks with suitable metering fittings ff134. In 33. Similarly, whether only a single cyclone or However, depending on the type of overall equipment or whether one or more cyclones are used, It will be up to you to decide whether or not to do so. In the past, often quite large I wonder if there were actually many Ikrons to be built, but recently there have been multiple smaller [one-diameter There has been a trend toward the use of cyclones, and these multiple small-diameter cyclones or parallel In operation, each cyclone is connected to the inlet gas stream and the outlet stream is connected to one outlet. I'm trying to get it back through the mouth manifold.

The feeding position can be changed within certain limits and satisfactorily operability can be obtained. ing. Preferably, the inlet 31 introduces the reducing agent into the annular region 21 at the top of the annular region. Located near the border or in several locations that are generally close to the border. There is. A gaseous reducing agent is introduced into the volute at a position slightly below the annular region. It is said that the efficiency is slightly lower depending on whether it is done or not. The most effective way to add a reducing agent One practical configuration is where the gas flow momentarily has a very slow radial outward velocity. It has been discovered that this is what is traditionally called the zero velocity zone. like this Proper dosing into the equipment will result in rapid and thorough mixing. In fact, it has been discovered. Input is through the cap of the cyclone or into the annular area. 21, preferably near the upper part thereof, e.g. For example, use a suitable inlet or the upper area of the body cylinder 13 near its top cover to fill it with normal water. It is carried out by supporting the inlet in a position that penetrates flatly. . The inlet is installed so as to penetrate outward through the outlet duct 19 and enter the annular area. It is also possible. However, such a location is probably around the exit tact. This would require more input ports along the line. More preferably, multiple The inlet 31 of the cyclone is supported by the top cover of the cyclone, and the annular area is placed at relatively the same angle. It is located in As most commonly seen in the fFS2 diagram, the four input ports are They are placed at 0° intervals, or they can be placed 2 or 180° apart. . The input ports shown are the external surface of the outlet tact 19 and the body cylinder 13. is located radially approximately midway between the internal surface of the It is located relatively perpendicular to the path of the incoming hot gas stream.

The above-mentioned input is caused by the gas flowing in a strong spiral descending from the gas stream. , it has been found that it results in strong and rapid scum mixing. Overall, the input is The gas flow must begin within at least about 0.1 seconds after entering the annular region 21. Must be. Particles carried by a gas stream or actually radially outward by centrifugal force The point that is separated from the gas flow as a result of moving to the radial zero velocity zone is By being injected at or near the reductant, the reductant is very rapidly distributed throughout the gas stream. thus preventing the reducing agent from being present in localized pockets. , thereby avoiding reactions between e.g. ammonia and oxygen or sulfur trioxide. It will be done. These reactions may be undesirable for achieving the desired tightening result. CaO and limestone from 0 limestone, which is especially NH, +02 → NO, +8 It is a catalyst that effectively catalyzes 20 reactions, and therefore it N) Inputting 13 must be avoided, otherwise the treatment itself may be seriously affected. Essentially, the use of ammonia or pre-ammonia in such a method would have the opposite effect. The injection of the ammonia is expected to form an "ammonia curtain" in the center of the cyclone. It is believed that this prevents the dissipation of NO, while clearly NH,,02 Simultaneous contact with ammonia and CaO is therefore minimized. If a desirable chemical reaction occurs, NO.

It has been practically confirmed that the gas turns into nitrogen gas and water vapor. For example, NH3 mol /NOX by adding ammonia at a molar ratio of about 371 to 5/1. Therefore, it is possible to achieve a reduction in the amount of NOx in the combustion product gas stream by more than 70%. It was discovered. Usually a ratio of at least about 0.5/l is used.

As previously indicated, nitrogen acids in the flue gas stream from the combustion of carbonaceous products The use of reducing agents to reduce NOx emissions is well known. Power plant, Industrial furnaces, incinerators and similar equipment are significant contributors to NO. NOx is generally in the form of NO, which is associated with fire rather than carbonaceous fuels. It is derived from oxygen that combines with atmospheric nitrogen present in the flame, and nitrogen fixation (n It is well known that this reaction is called trogen fixation. It is. If organic nitrogen compounds are present in the fuel, the NO will be removed when the fuel is burned. generated. At high temperatures, most of the nitrogen oxides exist in the form of NO, with only a small amount Whether there is a higher amount of NO and a higher oxide or a smaller amount, at lower temperatures the NO It also reacts with atmospheric oxygen to produce NO2. f! Yellow gold compounds, usually react with oxygen produces sulfur dioxide. However, there is also some amount of sulfur trioxide and a small amount of 0 Coal, gas, oil, shale oil, peat, lignite and the like, which also produce high levels of sulfur oxides. Other wastes contain varying amounts of organic nitrogen compounds and acid-containing compounds.

There are many known NO-reducing agents that are used to reduce NO levels in flue gases. Use all of these or as part of the invention to operate effectively over the relevant temperature ranges. The present invention is designed to operate at temperatures above about 800°F. and since this method is usually carried out at almost atmospheric pressure, pressure cannot be considered as a condition. combustible waste and materials can be removed sufficiently to meet the needs of the furnace or combustion furnace. The required pressure is sufficient. In other words, the primary concern is how to use the furnace or combustion furnace to produce heat. For example, to generate the necessary heat for electricity generation, industrial heat sources or similar The method of reduction is to operate the furnace at maximum operation so that it is operated normally. Easily designed to operate effectively between conversion and minimum operating rates. Like Alternatively, each step is operated at temperatures above 1200"F and about 2000°F, typically The NOx reduction method uses heat from a fluidized bed boiler between about 1400” and about 1900°F. Operated in combination with a combustion product gas stream to achieve NO, levels within existing BAC standards. It is possible to achieve.

Within the above temperature range, the preferred NO, reducing agents are ammonia and ammonia It is a precursor. Some ammonia precursors include ammonium carbonate and ammonium formate. Ammonium oxalate, ammonium oxalate, and urea, especially urea. For this purpose, it is considered an ammonia precursor. Ammonia is , which can be used in gaseous form or as an aqueous solution; Aqueous solutions of the substances can also be used. Does urea react directly with NO? or first dissociates to form ammonia, which then participates in a chemical reaction. It is unclear whether either of them is correct, or the final result is the same and the molecular For this reason, urea is an ammonia precursor. It is called. Urea is preferably used in the form of atomized liquid droplets, e.g. Used in the form of an aqueous solution.

The reducing agent used depends on the composition and final depending on the desired level of flue gas discharged into the atmosphere. Big In the body, about 0.2 moles and about 1 mole of NOx in the gas stream exiting the combustion furnace. The amount of NOx reducing agent between 0 molar and expected to be used is 0, e.g. To meet local environmental standards, the NOx content of the final gas stream should be reduced to 100 pp1. It is necessary to lower it to below 0.00pp. If this is the case, compared to a more lenient standard, e.g. 150 ppm or 200 ppm. Assuming the treatment of a combustion product gas stream whose initial NOx content is x A reducing agent or ff1 will be used.

Additionally, ammonia or ammonia precursor or NO, when used as reducing agent Considerations must be made to control the oxygen flow of the gas flow. This has the potential to react with either N113 or 02, and this reaction results in additional NO. The reaction rate of this particularly unfavorable reaction, which is unfavorable because of the formation of In the preferred temperature range of 1500" to 1700'F, the desired HN3 was found to catalyze a reaction that is particularly less favorable than the reaction between As long as the presence of CaO is avoided, the reaction is quite slow, and thus At some point after the particles have actually been separated, the reducing agent can be removed quickly and completely. Is dispersion of the fuel product in the gas stream possible, a desirable reaction or priority? It has been discovered. However, to minimize any potential effects of oxygen, To avoid this, the oxygen gas flow entering the cyclone should not exceed 10% by volume. It is preferable to control the Control in this manner can be achieved by using combustion or atmospheric oxygen. It can be effectively carried out using a fluidized bed combustion boiler. The content must be maintained well within these limits to achieve sufficient combustion and heat transfer. I'll come.

The first UA is a combustion product gas stream leaving a coal-fired boiler or similar combustion device. 1 illustrates an example of a typical total load adapted to reduce NOx in the air. Bo It is depicted that granular coal or combustible material is burned in about 140 yen. Produces a generated combustion product stream having a temperature that can range from 0@F to about 2800°F. to be accomplished. This gas flow exits the top of the combustion furnace 35 and passes through conduit 37 to the convection section 3. 9, where most of the heat is extracted from the hot gas to generate steam or similar uses. applied to. Various heat transfer components may be located within the convection section, e.g. If the economizer 41 is located directly above the transversely extending heat transfer component 43, The heat transfer component 43 includes a number of normal heat exchange tubes; These heat exchange tubes interrupt the descending waste flow within the convection section 39 and are arranged in a substantially horizontal direction. 2 and 3 leading to a separator 11 of the type shown in more detail in FIGS. Almost all of the flue gas is branched into the pipe 23. NOx reducing agent is 4f! Throw (Input is made through 131, and these four inlets are inserted through the top cover of the cyclone. uniformly near the annular region 21, each or each other at an angle of 90°. They are placed at intervals.

The treated flue gas exits upwards through the outlet duct 19 and enters the annular conduit 47. , this conduit 47 directs the gas flow to a location directly below the branched heat exchange component 43 of the convection section 39. from which the gas flow finally cools down primarily to the final discharge temperature through the heat exchanger section. It passes downward through minute 49.51. At this point, the gas flow is directed to the side discharge conduit 53 Exit through. A discharge conduit 53 directs the gas stream through a fan 54 to a chimney for direct discharge. through a scrubber or can be routed through a particle treatment device such as a Yatsugu Twilter or an electrostatic precipitator. Ru. Particulate solids separated from the flue gas in the high temperature cyclone 11 fall by gravity. down, through the outlet 17 in the lower part, and from there to a suitable evacuation device, e.g. a water-cooled screw. - Discharged by conveyor 55 or the like. In addition to this, particle fall is also caused by convection. It also occurs in part 39 and is depicted in the rice temperature diagram 4, or is there another specific example? The iron is equipped with similar equipment parts to those described above. Combustion furnace 35 The combustion products from ' are similarly passed through the duct 37' to reach the convection section 39'. , this convection section 39' includes a heat exchanger 43' configured to change the course of the waste flow. The economizer 41' may also be located above the convection section.

A similar inlet tact 23' removes the high temperature cycle from the area directly above the heat exchanger 43'. It leads to Ron 11'. Another example of this is to use solid urine to reduce NOx. It is designed to inject either elementary particles or an aqueous solution of carbon. Inlet port 31 'The NOx reducing agent is supplied or atomized using air, flue gas or steam. used for Preferably, the feed line 63 is located in the cyclone 11'. Steam is supplied to the input port 31'. The water vapor is just past the metering device 34'. a surrounding coaxial pipe attached to the NOx supply line 33' that continues downstream In this case, the inlet 31' is connected to the annular area as described above. It is installed in 21'.

The treated gas flow descends in a similar manner through the cyclone, first moving upward through the center. It passes through the outlet duct 19' and returns to the convection section 39' via the return tact 47'. , re-enters the convection section 39' just below the heat exchanger. fly ash, C aSO4, CaCO3, CaO and some NO, reducing agent powder (if used ) are removed from the gas stream as a result of cyclonic motion, The separated ash containing some of the ash from the furnace eventually finds its way to the lower outlet 57'. The particulate matter is separated at the time of discharge, and some of it is transferred to the screw conveyor 5 as shown in Figure 1. 5' and exhausted. For the rest, use Sukusoyu Conveyor-67. The screw conveyor 67 transfers these particles to the pneumatic transport pipe 69. and this air transport pipe returns these extracted particles to the inlet duct 23'. However, the particles are now circulated through another path into the gas stream before the cyclone.

Analysis of the gas in the gas flow transfer conduit 37' and into the atmosphere through the exhaust conduit 53'. Analysis of the gas stream leading to the exhausting stack determines both the NOx content and the S08 content. or that it is actually greatly reduced by adding only a reasonable amount of reducing agent. It shows.

Depicted in Figure 5 is the N in the combustion product gas stream leaving a circulating fluidized bed boiler. O, is a device designed to lower the level. Combustion furnace 135 is drawn. , in which granular oak coal is burned in a fluidized bed and heated from about 1550"F to about 1650° A combustion bale material waste wave having a temperature in the range of F is generated. The actual amount of heat produced is from the combustion furnace. Heat is exchanged throughout, and one heat exchanger 136 located at the top of the combustion furnace 135 Therefore, it is exemplified. The gas flow exiting the top of the combustion furnace 135 is directed to a portion of the cylinder. A short gas transfer duct having a vertical dimension practically greater than half the height of 113 Moving horizontally through 137, FIGS. 2 and 3 show more detailed conventional morphological views. The liquid flows to a cyclone separator 111 having a shape shown in FIG. The NOx reducing agent consists of two The input is made through the input port 131, and the input port 131 is connected to the cylinder side 11 of the cyclone. 13 and protrudes inward, or the input port 31a in FIG. and the annular area determined by the vertical projection of the exit tact at generally the same angular position of It is slightly below area 121.

The treated flue gas exits to one side through outlet duct 1-119 and exits to outlet duct 1-119. duct 119 discharges the gas flow into tubular conduit 147, and tubular conduit 147 directs the gas flow. Flow section i39, from where the gas stream passes through another heat exchanger 149. through isi Two sets of air descending and then supplying primary and secondary air to the fluidized bed combustion furnace It passes through F heaters 155 and 157. The temperature of the gas stream from these T-heaters or gas streams It absorbs supplementary heat until the actual final discharge temperature is lowered. At this point the gas flow is , through a side discharge conduit 153, where the discharge conduit 153 is It passes through a filter 154 and reaches a chimney for exhausting into the atmosphere.

FIG. 6 shows a centrifuge 111' which generally resembles the apparatus shown in FIG. It is a contour diagram. The inlet duct 137' includes a cylindrical portion 113' having a height rhJ. Leading to the top of the minute am shown as right. Central exit tact 119 ' is located at the top, and this duct extends downward into the northern area, It helps form the annular region. As shown, the exit tact 11 9' extends downward into the cyclone for a distance approximately equal to 0.25h: preferred. Preferably, the outlet duct extends into the cyclone for a distance between about 0.1 h and about 0.8 h. ing. Two input ports 131' are depicted, which are the same as the input ports in FIG. At the cyclone inlet located at each position of 31a and 31b , the inlet is preferred if large limestone or lime particles are present in the flue gas. Specifically, it extends downward from the top of the cyclone and is equal to between approximately 0.1 h and 0.9 h. In the illustrated example, this distance is approximately equal to 0.7h, but However, if the gas contains very few or no solid particles, then The inlet must extend downward beyond h until it reaches the ejector or sloped wall. I'll come. Also distance @1. Is this L the outer surface of the exit tact 119? It means the half frame distance from the inner surface of the vertical cylinder side wall 113'. This distance The distance is shown as 0.5L for the illustrated inlet and is as shown above. As mentioned above, the preferred distance of the inlet is between about 0.1L and about 0.8L.

As a special illustrative example, about 1 weight percent nitrogen and about 3 weight percent sulfur Particle size containing yellow or granularity up to about 1/4 inch flows in the combustion furnace 135. It was burned as part of the floor. Such coal flows into the fluidized bed combustion furnace 135 at a flow rate of about iio, ooo bond/hour, air or air at a temperature of approximately 400°F. A weight ratio of coal of approximately 1O to IT' was introduced. Under these conditions, coal particles Combustion is performed by creating a fluidized bed at a temperature of about 1500'F to 1650°F. do. large amounts of heat) or removed by the generation of water vapor from the combustion gases, or It is removed by a water-cooled tube located within the combustion furnace 135. The combustion product gas flow is approximately Temperatures from 1500°F to approximately 1650@F and approximately 65 million ACF/hour (average (cubic translation/hour) leaves the top of the combustion furnace. Gas transfer from combustion of high sulfur content coal F)-137 sludge analysis revealed NO, about 160 ppm and SOx, about 300 ppm. It shows pm.

The cyclone 111 used to accommodate this flow rate of thermal combustion products is 13 feet in diameter and 17 feet in height above the body cone section It has a main body cylinder. This cyclone is made from carbon steel. The inner surface is thermally insulated with a layer of corrosion-resistant insulation material approximately 12 inches thick. Ru.

Outlet L1 duct 19 is located coaxially and approximately 5 feet from the outer frame of the cyclone. It protrudes downward from the top a distance of about 3 feet, thereby increasing its height and approx. An annular band with a radius of 4 feet is created, and a downward spiral is generated within this annular band. do. The inlet 131 is inserted approximately downward from the refractory material insulating the cyclone top cover. There is a tube extending 4 inches and its inside diameter is approximately 778 inches.

The lower end of the input tube is open. Two such tubes, Figures 2 and 3 are approximately 180° apart within the annular region, as shown in FIG. Radial distance between the outer surface of the duct and the inner insulating surface of the cyclone body cylinder The 9-car input [-] 131, which is placed in the middle of the direction, is an appropriate plan. The metering device 134 is fed from the normal supply line 133 using the metering device 134. , in response to changes in the rate at which the combustion products are being produced in the fluidized bed boiler. You can either increase or decrease the side flow rate.

Gaseous ammonia is passed through the supply line to the upper portion of the cyclone annular region 121. During one injection, ammonia was introduced at a rate of about 15 bonds per hour. Ru. The diffusion of the ammonia flash seeding injected into the incoming total waste stream causes a strong swirling flow. This occurs as a result of intensive mixing, which is facilitated by 'C'. Enter the cyclone (The temperature of the incoming gas is approximately 1600"F. It passes through the exhaust conduit 153 and into the atmosphere.) The analysis value of the gas that is being crushed into the chimney for discharge is approximately 64pp of NO. It shows that it is m.

As a second illustrative example, about 1 weight percent nitrogen and about 3 weight percent nitrogen Contains sulfur A...'? 1. Use charcoal of approximately 1/4 inch particle size in the combustion furnace. Flk is burned as part of the fluidized bed in 53. stone) (or fluidized bed combustion furnace) Approximately t, io, oo per hour during 135.

Flow rate of cylinder 1 ~ - C = 4 air at a temperature of about 400'H at a time, or air vs. stone The charcoal is first introduced at a flow rate corresponding to a weight ratio of about 10 to 1.

Under these conditions, coal particles burn between approximately 1500'F and 1650"F. 5 granules A1 Ashite CaC (L+ or P! It is put into the kiln and quickly M-fired to C It becomes aO, where most of CaO reacts with SOX and becomes calcium sulfate raw I & do. A large amount of heat is placed in C' or combustion furnace 135 by steam generation. Therefore, in this example, the water vapor generated by the water cooling pipe is about 120,000 yen. is taken from the combustion gases at a raw rate to maintain the fluidized bed temperature at approximately 1550-1630°F. . The combustion product gas stream has a temperature of about 1600°F and about 65 million ACF/hour. The flow rate leaves one end of the combustion furnace. Analysis of the gas in the gas transfer duct 137 is approximately It shows 160 ppm NOx and about 300 ppm SOX.

11 in the cyclone used to accommodate this amount of thermal combustion product flow. 13 foot diameter and 17 foot height body resting on cone section It has a cylinder. The cyclone is made from carbon steel and its inner surface It is thermally insulated with approximately 12 inches thick of corrosion-resistant insulation material. Outlet duct 19 are located coaxially and have an outside diameter of approximately 5 feet and are approximately 5 feet from the top of the cyclone. It projects downward a distance of 3 feet, thereby increasing its height and approximately 4 feet. This creates an actual annular zone with the radius of the Generate a roll. Injection L) 131 is the refractory material insulating the cyclone top cover. a central tube projecting downwardly from the tube and having an inside diameter of approximately 174 inches. this The tube is open at its lower end, connecting the outer surface of the outlet duct and the body of the cyclone. It is positioned radially midway between the cylinder and the internal insulating surface. ing. Supplied using one inlet 131 or a suitable metering device 134. This metering device 134 indicates whether the combustion products are being produced in the fluidized bed boiler. Corresponding to the change in speed, the flow value of the reducing agent may increase or decrease.

An aqueous urea solution of about 50% urea by weight or at a temperature of about 120°F is passed through the C1 supply line. is introduced into the input port 131, and at this input port 131, the cooling air The water is also atomized by steam flowing through a coaxial 1/2 inch tube.

The inlet extends approximately six feet downward through the top of the cyclone. urine The hydrogen aqueous solution is added at a rate equal to approximately 1 mole of NO, corresponding to approximately 1 mole of NO. be done. The input port is input Fl 31. C is located in a place similar to a and enters. The instantaneous diffusion of steam atomized ammonia into all the gas inside, or the powerful vortex 8 wave. This occurs as a result of intensive mixing facilitated by this. Temperature of gas entering Cyuron The temperature is approximately 1600°F. through the discharge conduit 153 (for discharge into the atmosphere). Gas analysis of the flow leading to the chimney of It is 5.8%, and the NOx level is 175 ppm based on the NO of the incoming gas. It was reduced by about 68%, that is, by about 56 ppm.

L in the E direction so that the atomized urea aqueous solution is introduced approximately 6 inches below the top cover. The results of repeated tests showed that at a molar ratio of about 1.43:1 (NoX level of about 1 70 ppm and 02 content of approximately 5.4%), NO of approximately 62%, The urea aqueous solution or NO,1 By increasing the molar ratio to about 4 moles of 11N3 per mole, N Approximately 86% reduction in OJ was achieved, where N113 is approximately 10 ppm and base The NOx load that became the source was 175 ppm. If the combustion furnace operation is NOx based If the load can be changed to lower it to about 135 ppm, the same molar ratio of N O, is reduced by about 82%, and the ammonia flux is about 8 ppm. The stray current is about 44pp. must be maintained at a level no greater than m, preferably about 10 ppm. m or less.

The present invention is based on certain methods which the inventors at this time deem best suited for carrying out the method of the invention. Does it describe selected examples or be clear to those skilled in the art? Obvious changes and modifications may be made without departing from the scope of the invention. There are only so many things you can do. For example, instead of using a single cyclone Can be used with multiple cyclones or in parallel. Alternative to using a cyclone For example, a device that creates a strong swirl 1. For example, a gas wave is tangentially shaped into a circular shape. Alternatively, use a device that creates a swirl by introducing it into a closed container with an oval cross-sectional area. You can use it. The inlet is used to prevent viscosity from decreasing and precipitation of llliI form. It is preferable to inject a preheated liquid solution in order to Therefore, the C1 inlet should be used for fully loaded droplets or coarse particles not larger than approximately 500 microns in size. Forming liquid disease. The features of the invention are emphasized in the claims that follow. It is.

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Claims (19)

[Claims] 1. the hot gaseous combustion products to at least partially convert the NOx content to N2; The above reducing agent is brought into contact with a reducing agent that effectively causes a chemical reaction to be reduced by ammonia, ammonia precursor or These mixtures refine the gaseous combustion products by reducing the NOx content. The improvement in the method of making Route the gas flow through the area where the reductant is created, and immediately remove the reducing agent. A method characterized in that it is introduced into the gas stream towards the entrance to the swirl region. 2. The reducing agent causes the gas stream to have a NOx content of more than 200 ppm. Claim No. The method described in Section 1. 3. The above introduction is carried out radially into the high temperature cyclone separator equipment of the above reducing agent at zero velocity. It is carried out by throwing the material into a certain area at a certain speed, and its zero speed The band is located within an inner radius from the outer boundary of the cyclone separator. This causes the reducing agent to rapidly disperse into the gas stream and then to the silica. Claim 1, characterized in that the movement is a spiral movement within the Cron separator. Method. 4. The above-mentioned injection into the above-mentioned gas flow is performed continuously at multiple points, and each of the multiple points are either on a circumference radiating outward from the exit duct or in a cyclonic section. At each point in the vertical direction making up the internal boundary of the upper annular region of the separating device. , the circumferences are approximately 0.1L and 0.8L, where this is the radial width of the annular region, 4. A method according to claim 3, characterized in that the distance between the two points is equal to the distance between the two points. 5. Claim 4, characterized in that said circumference is at a position of approximately 0.5L. How to put it on. 6. The reducing agent comprises between about 0.2 moles and about 10 moles of reducing agent per mole of NOx. 4. A method according to claim 3, characterized in that it is introduced in an amount. 7. A claim characterized in that the aqueous solution of the NOx reducing agent is atomized by water vapor. The method according to item 2 of the scope of the invention. 8. The NOx reducing agent is applied to the gas at a temperature between about 1400°F and about 1900°F. 3. A method according to claim 2, characterized in that the method is introduced into a gas stream. 9. The reducing agent is configured such that the O2 content in the gas stream is not more than 10% of the total volume. 9. A method according to claim 8, characterized in that: . 10. A claim characterized in that the urea aqueous solution is introduced using water vapor and atomized. The method described in item 9 of the scope of the request. 11. A gaseous fuel whose NOx content is reduced by contacting it with a reducing agent. In a system that produces a baked product, the system is heated to at least about 1400°F. A conduit device conveying a stream of gaseous combustion products at a temperature of a high temperature cyclone separator connected to the outlet from said conduit device for said gas stream immediately directing the reducing agent and reductant to the inlet to said swirl-generating cyclone separator; A system characterized in that it includes an input device for introducing into the system. 12. The swirl generator is a cyclone separator, and the input device is the reducer. agent into an essentially zero velocity zone radiating inward from the outer boundary of the cyclone separator. introduction of the reducing agent, which causes the reducing agent to rapidly disperse into the gas stream and then 12. The system of claim 11, characterized in that it descends spirally. 13. The above swirl generator is a body cylinder part and usually has a circular cross section. A cyclone distribution device containing an internal outlet duct, and the above-mentioned input device The reducing agent is introduced into the annular region between the outlet duct and the body cylinder part. an annular region located radially within and substantially within the surface of said body cylinder portion; 12. The system of claim 11, wherein the system is located at a location where the product is introduced into the area. 14. said input is at multiple points through the upper bounding surface of said cyclone separator; 14. The system of claim 13, wherein: 15. through the above-mentioned input device or the vertical cylinder side wall of the above-mentioned cyclone separator. Above 10% from the top of the inner height of the above cyclone vertical cylinder part The contract is characterized by protruding inward at a position between 80% and 80%. The system according to item 13. 16. The dosing device is capable of producing liquid in the form of droplets not larger than approximately 500 microns in size. The system according to claim 11, characterized in that it is designed to input stem. 17. The feeding device feeds the NOx reducing agent into the cyclone in the form of an aqueous solution of urea. Claim 11, characterized in that it is designed to be introduced into a separation device. The system described. 18. The dosing device supplies about 0.1 L and about 0.8 L of the reducing agent to the gas stream. where L is the radial distance between the outlet duct and the body cylinder wall. 12. The system according to claim 11, wherein the system is injected at the position. 19. The injection device feeds the NOx reducing agent into the cyclone separator at about 0.00%. 1h and about 0.9h, where h is the vertical dimension of the above body cylinder part. Claim 13, characterized in that the injection is performed at equal vertical positions between system.