JPH07500525A - Waste gas purification method - 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] Waste gas purification method The invention relates to waste gases produced, for example, from combustion, gasification or any chemical or metallurgical process. The present invention relates to a method for purifying gas. Sulfur dioxide, ammonia, chlorine and fluorine compounds and Condensed hydrocarbons and condensed hydrocarbons are typical contaminants contained in these gases. The present invention is particularly Reagents and/or absorbents that react with the contaminants contained in these gases moisten them. The method is activated by introducing the method into a wet reactor. This reagent and/or Absorbents are added to the process itself or to the gases exiting from the process. contained in gas Wetting the gas with water or steam to activate the reagent into the water reactor. Gas is first supplied to the lower part of the wet reactor and then The suspension formed from the gas and reagent is fed upwardly into the wetting zone, where the suspension formed from the gas and the reagent is mixed with water or moistened with water vapor. Completely or partially reacted reagent and/or absorbent particles Before this gas is discharged from the reactor, it passes through a filter in the upper part of the wet reactor. Therefore, it is separated from the gas. For example, either alkali metal or alkaline earth metal Carbonates, oxides or hydroxides are used as reagents or absorbents.

As is known, the combustion of fossil fuels produces flue gases, which contain sulfur oxides and causes environmental acidification. The sulfur content of the flue gas varies depending on the sulfur content of the fuel. Become. Even as restrictions on sulfur emissions become increasingly strict, more and more sulfur-containing fuels will be used. Efforts are being made to find devices that will Waste ashing plants, the number of which continues to increase However, it also produces sulfur-containing flue gases, which must be carefully kept within specified limits. It needs to be manufactured. For example, when plastic compounds are burned, waste In addition to SO8 and SOs emissions, the flue gas generated in the ashing plant contains hydrochloric acid and fluoride. Contains hydrogen acid and other existing gaseous and solid compounds.

Process gases produced in various gasification processes may also contain harmful amounts of sulfur or other compounds. However, this must be separated from the gas before further processing.

Several methods have been developed to reduce sulfur emissions from combustion plants.

The most common method used so far is wet scraping, in which , the gas is scrubbed with an aqueous suspension of an agent such as lime, which reacts with the sulfur oxides. will be uploaded. This water suspension is deposited within the gas stream in a flapper arranged after the combustor. This causes the sulfur to be absorbed into the water suspension and the sulfur dioxide to be dissolved in stone. Reacts with ash to form calcium sulfate or calcium sulfite.

CaO+SO, Jugi/x Ot ---> CaSO4 or CaO+SOz -1-) Ca5O *When the sulfur compound formed in this way does not dry out Water is poured in such an amount that it is discharged as a slurry from the lower part of the flapper, although there is a gap in between. Suspension or spray.

This wet scraping method requires equipment for preparing the aqueous suspension and subsequent processing. It is complicated because it requires special equipment. Additionally, this method can be used in slurry post-treatment plants. Drying the resulting slurry typically requires additional energy. So Therefore, water suspensions should be kept as dry as possible to minimize energy requirements. is normally supplied. Due to the considerable dish water suspension used, the gas is is cooled to a relatively low temperature in the flapper and is subsequently discharged from the flapper. Gases cause corrosion and clogging of filters. Furthermore, before deriving these from the system Energy is consumed reheating this flue gas. This wet scraping In the system, for example, the degree of separation of SO□ is about 95%.

In recent years, semi-dry scraping methods have been developed in which a fine alkaline suspension A liquid, e.g. a calcium hydroxide suspension, is introduced into the hot flue gas flow in a catalytic reactor. is sprayed through a nozzle, where the sulfur oxides dissolve in the water and a suspension is formed. When drying, it is bound to lime compounds. Water contacts to form solid waste The reaction products of e.g. sulfur and lime are evaporated in the reactor, whereby the reaction products of It can be easily separated from the gas by a router. The heat content of the flue gas will cause the water to The composition of the calcium hydroxide suspension at such a level that it is sufficient to evaporate Attempts are made to keep Chinshi. However, the thick lime suspension It quickly settles on the soil and especially around the spray nozzle and eventually clogs the nozzle completely. let The reactor must be made relatively large to minimize this defect due to deposits. No. Furthermore, the production of lime suspension requires separation equipment, which requires considerable Quantity equipment is also required in semi-dry scraping processes and gas purification is quite expensive. Another drawback is the abrasive effect of lime suspension on the nozzle.

This semi-dry scraping method allows contaminants in the gas to be removed as dry waste. This is a useful process. This process is difficult to control and wet scraping It has the disadvantage of exhibiting a sulfur absorption of less than 90%. Another drawback is Since limestone reacts with sulfur very slowly, it is difficult to use solid limestone for this semi-dry method. It cannot be used. Calcium oxide or hydroxide, which is much more expensive must be used instead. In large combustion plants, absorbent The costs are significant.

The addition of limestone has already been suggested during the actual combustion or gasification stage. of this addition As a result, limestone (calcium oxide) is calcined according to the reaction below.

CaCO5--->CaO+CO! Calcium oxide already reacts in the combustor with the sulfur oxide formed there. Can be done. The reaction occurs as follows: CaO + S, +1Δ Ox ---> Ca5OaHowever, as the reaction proceeds, calcium sulfate or calcium sulfite The mucous layer covers the surface of calcium oxide particles and prevents sulfur from penetrating the particles. , which slows down and finally inhibits the reaction between sulfur and lime. Therefore, the lime does not react completely and is therefore not utilized optimally. many other parameters The factors such as Ca/S molar ratio, temperature and residence time also influence sulfur absorption.

The closer to the dew point the reaction occurs, the more reactive the alkaline compound will be.

Good reactivity is due to the fact that in wet particles the reaction occurs in the aqueous phase as a rapid ionic reaction. caused by facts. Near the dew point, the particles can remain wet. The reactivity remains at the desired level for an extended period of time. The wettability of the particles is preferably such that water covers the particles. Surrounding and also penetrating these are kept at a high level. Water penetrates lime particles As the sulfate or sulfite layer deposited on the particles is destroyed, new Indicates a new reactive lime zone. The sulfur dioxide contained in the gas is absorbed into the water surrounding the particles. dissolves and reacts with calcium compounds in the liquid phase.

Finnish Patent Specification No. 78401 discloses that sulfur dioxide from the flue gas is conversion into solid sulfates and sulfites that undergo a reaction and are separable from the flue gas Disclose the method to be used. This flue gas enters the lower part of the vertical long contact reactor. be guided. Furthermore, powdered lime and water are separately led into the reactor from several places to absorb sulfur. is absorbed by lime. The flue gas suspension is discharged from the upper part of the flow reactor. The dust is then further guided to a dust separation stage. Powdered lime and water are fed separately into this reactor. This avoids the preparation, processing and spraying of aqueous suspensions. According to this specification , when this method is used for calcium oxide and sulfur absorption, Ca/S=1. Ca/S=2.56 molar ratio and S02 reduction of about 8096 Molar ratio of 22 This results in an 802 reduction of approximately 90%. 98% SOx reduction occurs when the molar ratio is Ca/S=4 You can't get it until

This method also removes solids from the flue gas suspension onto the walls of pipes and other equipment. The temperature of the flue gas stream should be optimal as it deposits layers and thus causes trouble in dust separation. should not be allowed to fall near the dew point.

, European Patent Specification No. 0104335 describes another two-phase semi-dry flue gas purification system. Disclose the system. In this method, in the first step, either the dry reagent or the flue gas in the catalytic reactor is and in the second step water or an aqueous solution containing the reagents was added. First stage At the bottom, an inert surface layer is formed on the reagent particles. This layer contains reagents and e.g. Slows or prevents reactions between sulfur. By adding water in the second step, The agent is reactivated. In this manner, the reagents are more completely utilized. The gas temperature is Do not allow the dew point to drop to such a level that it remains above 105°C at all times. This method also assumes that the gas temperature is lower and the activity of the reagent is much better. Also, the wetted particles that probably form will cause difficulties with long runs, so the dew point Don't let it fall too close. This method allows you to Contains reagents that are separated from the source and then regenerated either by grinding or some other method ゛Recirculation of solid materials can reduce the amount of reagents required. But long However, the disadvantage of this method is that separate equipment is required for handling and storage of recycled solids. .

U.S. Patent No. 4.509.049 discloses a dry gas purification system, in which In this case lime is added to the flue gas in the boiler and then lime is added to the flue gas in the reactor. I am left to react to the situation. The lime that has partially reacted with the contaminants in the flue gas is removed from the reactor. It is separated from the gas by a filter in the upper part. separated from the gas in this way The dry lime is recovered and crushed and then subjected to dry steaming to increase the reactivity of the dry lime. The lime is then recycled into the gas stream at a pre-reactor location.

Dry steam processing of lime takes 2 to 24 hours, which involves high consumption of energy. It's a long time.

The object of the present invention is to treat, for example, sulfur, chlorine and fluorine compounds or other condensable compounds. The object of the present invention is to provide an improved method for the purification of waste gas containing compounds.

Another object of the invention is that the gas to be purified is heated in a humidified reactor at a dew point, e.g. By providing a method that is humidified very close to The particles separated from the solution are allowed to be removed in a dry state.

In order to achieve the above objective, the ash layer is quite thick and the gas is injected in the lower part of the wet reactor. The ash layer formed from the particles separated from the gas is kept below mouth level so it is moist homogenize the particles and the water droplets fall downward from the upper part of the wet reactor. is a feature of the method according to the invention.

This ash layer is preferably filled with small particles to homogenize the temperature and humidity of the ash layer. Mechanical mixers for mixing and crushing possible lumps, e.g. blade mixers A server will be placed. The purpose is to ensure that the ash is conveyed pneumatically from the wet reactor. The goal is to maintain a properly dried ash layer. Quantification of the ash layer, e.g. humidity is maintained in the lower part of the reactor by adjusting the amount of Preferably, The amount of ash layer is at least 50 kg/m”/s of feed gas. In practice, the ratio In a wet reactor with a relatively straight bottom, this means that at least It means the ash layer of 25CI11. If the reactor bottom is V-shaped, this ash layer Must be thicker. For the effective operation of the horizontal blade mixer, it is necessary to It has been found that the key is that the ash level is preferably higher than the mixer shaft.

On the other hand, this ash layer is affected by the effective action of the mixer in the upper part of the ash layer and the gas void above it. Generally thicker than is necessary for the ability to eject particles from the ash layer into the should not.

Also, this ash level must not be higher than the actual inlet level of the gas.

The hot gas introduced into the reactor also serves as a drying gas and contact with moistened ash particles and particle clumps flowing downward from the surface and guide them to dry. It will be destroyed. Ash particles from the lower part of the reactor are carried away by the drying gas flowing upwards. and a wet zone to activate any unreacted reagents or absorbents in the ash. It is transported back upwards inside the container. In this wet reactor, particles are filtered out by a filter. is separated from the gas and then returned to the lower part of the reactor. In this method, the reagent or Internal circulation of absorbent particles occurs in the wet reactor and a relatively high density of particles therein. is maintained.

The particles may be removed, for example, by a textile filter, an electric filter or some other equivalent type of separator. separated from the gas. Particles e.g. pulse flushing, pack washing or separated from the filter by shaking, either intermittently or continuously. The particles fall down into the wet reactor either individually or in clumps.

At least some of the particles stick together in the wet zone or on the filter and are larger. form agglomerates and then pass through the wetting zone all the way to the lower part of the reactor. Single small particles, on the other hand, are easily carried away by the upwardly flowing gas. from the wet zone to the upper part of the reactor. Larger clumps of particles and The wet, heavy particles either mix when they reach the ash layer in the lower part of the reactor. and ground into fine particles.

Ash production is achieved by thorough mixing of the particles by mixing the constituents in the lower part of the reactor. Positive effect on homogenizing quality, i.e. equalizing heat and humidity in the ash layer or can be obtained. As the particles are crushed smaller, their reaction area increases and this At least some of these swirl upwards above the ash level and eventually rise into the wet zone. It is transported by dry gas. In the humid zone, particles are reactivated and Sulfur can be absorbed again in the reaction zone. mechanical or equivalent strong mixer The mixing caused by this will affect the runnability of the wet reactor. turned out to be of essential importance.

Mixed work is serves as a means of transport for a portion of the reactor, which is then transported from various parts of the bottom of the reactor to a single Exit/rIl number of exits. - Homogenize the ash, preferably by mixing it into a form suitable for pneumatic conveyance. death; It is the grinding of some wet or dry mass into a fine form.

Dryer that separates the flue gas from the flue gas as it falls during filter cleaning or otherwise enters the reactor. serves as an effective desiccant agent for wet methods and water droplets falling from the wet zone. Miki The sir mixes the wet and dry substances, thereby effecting the homogenization described above.

This mixer also swirls the ash over an ash layer or ash buffer, which lowers the The hot gases (flue gases) directed to the top level transport the ash, which causes it to flow into the reactor. causes internal ash circulation. Additionally, this is due to the drying energy released by the ash to the wet particles. Strengthens the conduction of energy.

Mixing and recycling of particles is controlled by residence time, dust density, Ca/S molar ratio in the reaction zone. and increases the total surface area of the lime particles, thereby reducing the need for new reagents.

According to the invention, the average particle density is maintained by internal circulation in the humidified reactor; The density is clearly higher than the particle density in the gas introduced into the reactor. Swirling upward from the ash layer This internal circulation can be controlled by adjusting the amount and speed of the circulating particle stream. Enter The arrangement of the gas supply points also includes a color tube for this recirculation. Gas spray directed towards ash layer The shorter the traveling distance, the more particles are entrained in the gas spray and the more particles are carried upwards.

A portion of the particles preferably passes through an outlet provided in the lower part of the wet reactor below the drying zone. is removed from the reactor through. A portion of the discharged particles can be transferred to the wet reactor as desired. be returned to. Thus, an external circulation of particles can also be provided in connection with the wet reactor. Wear. Particles can be processed outside the reactor, eg, certain reagents can be regenerated.

Adjusting the amount of particles removed from the lower part of the reactor, e.g. By directing particles from the ash layer above the overflow to the discharge opening and further into the ash discharge pipe. The particle density can be more controlled in the reactor. The volume of the ash layer can also be adjusted using a level control device. This controls the flow through the discharge opening or conduit.

External particle circulation in wet reactors can be achieved by connecting a filter or equivalent particle separator. Therefore, it is provided in the upper part of the wet reactor, wholly or partially outside the reactor. will be placed in In this filter or particle separator, reacted or still unreacted absorbent The absorbent particles are separated from the gas and at least a portion of the particles are present in the lower part of the wet reactor. minutes, preferably directly returned to the dry zone. Particles are removed from the filter continuously or intermittently. It is separated at one of the targets and returned to the lower part of the wet reactor. Particle separator The separated portion of the material can be removed from the system in its entirety.

The method of the invention allows the average temperature of the gas in the wet reactor to be lowered from the dew point to about 0-20°C. to a temperature that is preferably between 0 and 10°C and to the actual dew point, and then the reactor Avoid defects caused by too wet particles in the upper or lower part Is possible. Particles that are wetted in the wet zone and fall downward are exposed to the hot particles in the dry zone. It is dried with a gas stream, which does not cause any trouble in the lower part of the reactor.

Due to recirculation, differences in temperature and humidity are also generated over the wet zone at various cross-sectional points in the reactor. and very small. In this way, local hassles caused by wet particles are avoided. I get kicked.

In accordance with a preferred embodiment of the invention, at least a portion of the gas supplied to the wetting zone is into the wet reactor as a packet flow, thus indirectly or directly formed by wet particles in the wall soil of a wet reactor. This avoids layers that will be affected. The gas enters the reactor through tubes placed in the wall, e.g. The hot gases flowing in the tube are prevented from cooling by the walls, and this Prevents depositing layers on solid or wall soil. This gas is inside the reactor It protects the wall by injecting it directly and causing it to flow downwards along the wall.

This allows the wet particles to move away from the wall or to the jacket before contacting the wall. It dries as it passes through the flow. This jacket flow is e.g. This occurs by feeding gas into a cylindrical reactor through an opening.

Removal of deposits from walls can also be achieved by shaking or assembling walls of flexible material. , which causes the pressure fluctuations that normally occur in the system to shake the walls. and cause deposits to fall.

Particularly in large reactors, humidification is required to provide as uniform a gas distribution as possible in the reactor. Gas is also introduced into the interior of the band. The gas in the central part of the reactor is e.g. It can be fed through a number of nozzles or slots in the tube. How much gas is there again? It can be fed into the wet reactor from different levels.

The hot gas introduced into the lower part of the reactor is important because its work is has a meaning: for example, Release the drying energy to dry the wet ash or water droplets and return them to the wet zone. The mixer conveys the swirled ash, thereby providing internal ash circulation in the reactor. Shi: And One keeps the reactor walls warm, which further reduces the tendency to deposit layers on the walls.

A wetting zone is provided in the upper or central part of the wetting reactor by spraying water or steam. . Water is preferably sprayed into the flue gas, primarily from above the gas inlet downwards. . The water or steam spray is placed so that as much of the gas stream as possible is evenly covered. be done.

The wet zone of the wet reactor is preferably provided with downwardly directed water or steam nozzles. for example, on a support member running horizontally through the wet reactor.

The filter in the upper part of the wet reactor is preferably a hose or a cassette. A textile filter, such as a filter, or perhaps an electric or some other equivalent type of filter. lter, from which the particles are reacted by shaking or filter backblowing. It is returned to the lower part of the vessel.

The lower part of the reactor is preferably provided with a mechanical mixer. Mix the solid substances accumulated in the. Mixing of solid substances equalizes the moisture and heat of the particles. This allows the still wet particles to come into contact with the dryer and the hotter particles. It will be dried when it turns. At the same time, this mixer allows the particles to be transferred into the reactor by the gas flow. The particle clumps are broken up so that they can be easily transported upwards within. Thus, the mixer - enhances the effectiveness of the drying gas by creating internal circulation of particles in the reactor. mixer The speed of is adjustable and together with the gas flow entering the mixing zone, this A wide range of regulation of the child circulation is obtained.

The lower part of the wet reactor is provided with a device for discharging particles from the reactor.

The particles are preferably discharged by the mixer described above. This is the mixer blade or oriented obliquely to gradually move the particles to one end of the lower part of the reactor, where they The particles can be removed by drying through a suitable sealing device. These are also separate It can be removed by a discharge screw or a discharge conveyor. The particle is further is preferably discharged from the wet reactor in a dry state, such as by pneumatic conveyance. .

The IJF outlet opening should be arranged to form an ash storage mixer and this ash storage The storage capacity (height) varies depending on the mixer dimensions. For example, a brake whose axis is horizontal If a bed mixer is used, the ash level is preferably at least equal to shaft level. The same is true. However, the ash level is so low that the mixer no longer mixes anything in the upper layer of ash. It should not go beyond areas where it has no combined effect. With blade mixers, the effective high The diameter is about 1 to 4 times the mixer diameter. Mixer diameter is approximately twice the blade length It is.

In addition to blade mixers with a horizontal axis, other types of mixers can also be used. . Cylindrical reactors can be used, for example, with vertical mixers or jet mill-based local mixers. A grinder or a grinder can be used, where steam or air produces a mixing effect.

If necessary, separate feed ports for reagents or absorbents may be provided in the lower part of the wet reactor. An int is provided. Several different methods are used to remove harmful substances from gas in one step. reagents can be introduced into the wet reactor.

The device according to the invention exhibits several advantages over previously known devices, for example: functions such as sulfur absorption, reagent wetting, particle separation and drying in one device. I can concentrate. It can be arranged in the same space as the wetness of the gas or the residual ash capacity, thereby No extra equipment or separate reactors are required for each sub-step.

According to the present invention, the filter is placed directly into the reactor and no gas line is required. Since there is no dew point, it is possible to operate very close to the dew point, even almost at the dew point, This allows the wall soil of this gas pipe to be used when transporting gas that becomes wet near the dew point. The problem of deposited layers can be avoided. Being able to operate near the dew point is SO,,SO,, This results in very efficient desorption of 11Cl and HP release.

- Internal circulation of particles through the wetting zone reduces consumption of reagents or absorbents. this method Due to this, the residence time of the absorbent in the reactor is not inherently long, preferably according to conventional It is about 2 to 10 times longer than a single pass reactor.

- Fine pressure is also separated from the gas in this device. Ash and spent absorbent are dried and can be recovered through a common process. Only one ash removal system and ash treatment required It is. The drying pressure and absorbent can be conveyed pneumatically.

- In the conventionally known method, only when the SOx content of the artificial gas is <40 PPm Almost complete sulfur absorption is obtained in the wetting stage with SO, containing gas. Book By the method of the invention, even when the SO1 content of the inlet gas is >+ooppm Complete sulfur removal is possible.

-This method is simple.

In the device according to the invention, three main elements have a positive effect on the absorption reaction: Two systems that can be used simultaneously and optimally - in a knee reaction zone where the gas is cooled to a temperature level close to the dew point to provide a rapid reaction High Ca/S mol: and - long residence time for optimal utilization of the absorbent.

The invention will be further described below, by way of example, with reference to the accompanying schematic drawings, in which: FIG.

FIG. 1 is a schematic diagram of a preferred apparatus for carrying out the method of the invention.

2 and 3 are schematic illustrations of two other apparatuses for carrying out the method of the invention. ri, and FIG. 4 shows the ratio of SO2 reduction to Ca/S molar ratio in an embodiment of the present invention.

Figure 1 shows the gas populations 12 and 14, the gas outlet duct 16 and the particles separated from the gas. 1 shows a wet reactor IO with an exhaust duct 18 for the child. This wet reactor has Also above the gas inlet is a nozzle 20 for spraying water or steam into the wet reactor. provided. In the upper part of the reactor there is a A filter 22 is provided.

The wet reactor according to the invention can be a grate furnace, a powdered fuel combustor or a fluidized bed combustor, e.g. can be placed in the flue gas pipe after the combustion chamber of a circulating fluidized bed combustor, thereby providing a wet reaction The reactor is preferably placed after the heat recovery boiler. Before entering the wet reactor, smoke The pipe gas is cooled to 300°C, preferably 150°C. Io from flue gas To remove uroxides, absorbents such as limestone are added to combustion chambers or fluidized bed reactors or was then supplied. This absorbent absorbs at least some oxidized calcium in the hot flue gas. Calcinated with aluminum, this absorbs calcium as calcium sulfate and calcium sulfite. collect. 1. A lime/sulfur molar ratio of 5 to 2.1 is approximately 80 in a circulating fluidized bed reactor. resulting in a 95% sulfur reduction. The flue gas is still ionic when entering the wet reactor. Contains corrugated iron and unreacted lime. An important purpose of the wet reactor according to the invention is to lime or other adsorption in the flue gas so that the remainder of the The purpose is to activate the agent.

In the apparatus shown in FIG. Transported through 4. Before supplying the flue gas to the reactor, it is and 28 into two separate flue gas streams. The flue gas flow in tube 26 is substantially water spray. 20 into the reactor at the same level. The flue gas flow in tube 28 is at a substantially lower level. guided by the bell.

One flue gas stream is substantially at the same level as the water spray, above or below the water spray or exactly At the same level it is led into a wet reactor. The gas supplied to the reactor is well with water spray It is essential to be mixed. a spray in which both gas and water preferably flow downwards; is fed into the reactor, which is flipped upwards a short distance from the inlet. In this method A vortex of gas and water spray is provided in the wetting zone and this provides a good mixing effect. It will be done.

This water spray constitutes a wetting zone 30 in the wetting reactor. In this wet zone, flue gas moistened and cooled as close to its dew point as possible, preferably about 0-3°C from the dew point. Rejected. In the humid zone, the lime particles are moistened and this causes sulfur to be absorbed by the particles. Absorption and a rapid ionic reaction between sulfur and calcium occur in the liquid phase.

The water is preferably sprayed from a nozzle, which produces small droplets, preferably 100 μm in size. m, and the angle is large enough to cover the reactor cross section and gas flow. Can be attached. Water is sprayed downwards. The wetting zone covers the vertical zone of the reactor and this is preferably equal to the hydraulic diameter of the reactor.

In the example shown in Figure 1, the flue gas is introduced into the reactor as a jacket flow. Ru. From the tube 26 the gas is first conveyed to a tubular duct 42 surrounding the reactor. this From the tubular duct the gas flows into one or more downwardly directed ducts formed in the reactor wall 34. It is further conveyed to the duct 36. This reactor is closed for flue gas between walls 34 and 38. It is double-walled so as to form an opening duct 36. Flue gas flows from duct 36 to reactor It is transferred through the inlet 12 into the wet zone 30 therein.

Correspondingly, the gas is led from the lower gas duct 28 into a tubular duct 42 surrounding the reactor. and from there to a downwardly directed duct 46 formed in the reactor wall 44. It will be done. From the duct 46, the flue gas is transferred to the lower part, i.e. the drying or mixing zone 4 of the reactor. Flows into 0.

The introduction of gas into the wet reactor can be achieved, for example, by means of dampers 27 and 27 in ducts 26 and 28. and 29. The introduction of gas is also controlled by an adjustable stop in the duct 46. It can be controlled by lot 4B.

Gas flows upward from the dry zone, which causes it to flow downward through the filter and the wet zone. Dry the particles. The flow of drying gas depends on the temperature of the gas in the lower part of the reactor or can be automatically adjusted by means of elements 47 and 49 according to the temperature of the particles to be discharged. be.

Furthermore, a mechanical mixer 50 is provided in the lower part of the reactor. Tools shown in Figure 1 The example has two mixers and is equipped with blades 52 above the bottom of the reactor. available. This mixer breaks up the particle clumps that fall into the lower part of the reactor. . At the same time, they equalize the temperature and humidity between the particles. Is this mixer a gray layer? It operates to “splash” some of the particles upward into the gas space of the dry zone, From there the hot gas stream flowing upwards covers the wetting zone as far as possible in the upper part of the reactor. transport these particles through the As the mixer blades rotate, this reacts with the particles. It is often arranged to gradually move the particles to one end of the lower part of the vessel, and one end of said is provided with an exhaust duct 18 for particles. Particles are preferably not shown Flows over the overflow plate into the discharge duct. With this method, particles flowing downward A “buffer” of particles that equalizes the temperature and humidity of the reactor is always maintained in the reactor. It will be done.

FIG. 2 shows a wet reactor lO similar to that in FIG. into the lower part of the reactor via a gas inlet duct 54 located inside the . This gas inlet duct is provided with a downwardly directed nozzle 56 through which The gas flows first towards the particles accumulated in the lower part of the reactor and then upwards. flows. In this way, the gas also forms in the particles accumulated in the lower part of the reactor. A good mixture is obtained.

In the reactor according to Figure 2, the amount of water fed into the wetting zone is equal to the amount of gas in the upper part of the reactor. The temperature is regulated by member 21 according to the temperature. The wet reactor has gas equalized as needed. Water nozzles can be provided at several different levels to be wetted at once.

In Figures 1 and 2, the reactor consists of a hose filter chamber, each of which The lower part of the t=S filter and chamber has a wet zone and a dry zone.

FIG. 3 shows a reactor located just outside the filter 60 or reactor chamber. write In addition to the internal circulation, an external circulation of the particles also takes place in the reactor. wet zone 3 The particles wetted with zero will separate themselves from the gas and, due to their weight, flow downwards, where they are placed under the influence of drying gas. Particles become gas after drying is entrained and flows upward again, thereby forming an internal circulation. wet A portion of the removed particles follows the gas into the upper part of the reactor and into the filter 60 and dries. It will be returned to the drying section 40 via duct 62. If necessary, the particles are transferred to the outlet device 6 4, which can be closed with a valve 66.

In Figure 3, the flue gas inlet ducts 26 and 28 can be connected to different points in the combustion process. For example, the gas led to the reactor via duct 26 for this purpose may be routed through duct 28. This duct ensures that the drying process is further cooled than the gas guided through the directs hot gas.

Compared to the prior art, the present invention shows that the tests conducted on certain coal and limestone grades much better sulfur content in the flue gas with much lower lime consumption, as shown in the attached results of Provides absorption.

palanquin An apparatus according to Figure 1 was used for the test run. From circulating fluidized bed reactor to wet reactor A flue gas of 870°C was supplied to which the molar ratio Ca/S was 1.41-2.33. supplied limestone. The theoretical SO3 content of flue gas is 860 to 960 ppm. there were.

such that the SO1 content of the flue gas entering the wet reactor is about 60 to 201 ppm. In this system, the sulfur contained in the flue gas is already removed in a circulating fluidized bed reactor before the wet reactor. reacted to. This gas is introduced into a wet reactor at a temperature of about 139 to 160°C. Ta. The theoretical dew point of the gas in the wet reactor was approximately 54°C.

The test results are shown in the table below.

1.88 55 201 27 97 1.91 55 111 2 100 1.95 55 107 0 100 1.94 57 105 0 100 2.33 57 129 2 100 1.93 59 60 0 100 1.41 61 183 83 91 1.87 63 121 25 97 2.00 66 136 61 93 2.08 81 77 53 95 This test result shows that the method according to the invention shows that the final reaction is close to the dew point, i.e. from the dew point. Sulfur absorption is almost complete even at very low Ca/S molar ratios when occurring at 1-5°C. It is clearly shown that The highest temperature, i.e. 10-30℃ from the dew point, very good results can be obtained even with much lower lime consumption than with previously known methods. Ru.

According to information in the literature, wet reactors of the prior art have Ca/S=2. With a molar ratio of 22 Approximately 90% SO□ reduction occurred. Approximately 98% SO□ reduction occurs when the molar ratio is Ca/S = 4. I couldn't get it until I had it.

FIG. 4 shows the C received in the aforementioned series of test runs when applying the method according to the invention. SO to a/S molar ratio! Indicates the ratio of decrease. As a comparison, this figure also shows the test lab ni can be sharpened. - A wet reactor created from the space beneath a filter cassette, etc. placed in this space A nozzle system is used to wet the ash and absorbent particles and at temperatures close to the dew point, That is, water is sprayed therefrom to make the flue gas fall at 0-20°C.

- such as textile filters, which together with pressure pulses, backwash or shaking, It works on the usual countercurrent cleaning principle.

- for example, a set for ash and absorbent placed in a receiving hopper at the bottom of the reactor; Combined mixing and transport equipment. This mixing device preferably high enough to destroy deposits that fall from the router and are dried by the hot gas stream. Rotate at speed.

circulation of absorbent and flue gas which enters the reactor via the lower part of the reactor. This occurs by injecting some of the water into the air. The gas becomes fluidized and the particle mass is deposited under the reactor. The gas is also blown into the reactor from the bottom of the mixer in such a way that it accumulates in the lower part of the mixer. It will be done. Gas introduced into the reactor from its lower part along with the main gas flow coming from the side wall. The gas dries the wet mass of particles that fall from the upper part of the wet reactor. this gas traps some of the particles returning into the wetting zone, thereby allowing the interior of the particles to Causes circulation.

Figure 2 Figure 3 Copy and translation of amendment) Submission (Article 84-8 of the Patent Act) February 22, 1994 ―

Claims (20)

[Claims] 1. For example, sulfur oxides, chlorine or is used in one step or in purification processes for gases containing contaminants such as fluorine compounds. Later on, reagents and/or absorbents that react with the contaminants contained in the gas may be added. evening, gas with water or steam to activate reagents and/or absorbents contained in the gas. Here below, by introducing gas into the wetting reactor for wetting the gas Introducing gas into the wet reactor into the wet reactor section and further upward into the wet zone of the wet reactor. a suspension prepared from a gas and a reagent and/or an absorbent is mixed with water and /or moistened with steam and - A filter placed in the upper part of the wet reactor before discharging gas from the wet reactor. to separate completely or partially reacted reagent and/or absorbent particles evening, In the above purification method, Since the ash layer is kept thick in the lower part of the wet reactor below the gas inlet level, An ash layer formed from the separated ions falls downward from the upper part of the wet reactor. The above-mentioned refinement is characterized in that it is capable of homogenizing wet ash particles and water droplets. Manufacturing method. 2. Solid particles are removed from the wet reactor by a filter placed in the upper part of the wet reactor. It is separated from the exhausted gas, from which filter particles are intermittently desorbed. and then allowed to fall into the wetting zone and/or into the lower part of the wetting reactor. The method according to claim 1, wherein: 3. so that the inlet gas contacts and dries the wet particles flowing downward from the wetting zone. The method according to claim 1, characterized in that: 4. Particles accumulated in the lower part of the wetting reactor due to the gas supplied to the space below the wetting zone Claim 1 characterized in that it causes recirculation of a part of the The method described in. 5. A mixer is placed in the ash layer to mix the wet particles and water droplets with the ash layer. The method according to claim 1, characterized in that: 6. The mixer can also serve as a grinder to break up large clumps of particles. The method according to claim 5, characterized in that: 7. one or more gases supplied to the space below the humid zone, at least partially directed downwards; This gas spray is fed into the lower part of the reactor. A claim characterized in that the clumps of accumulated particles are broken and the particles are mixed. The method described in 1. 8. Claim 1, characterized in that the particles are discharged from the lower part of the wet reactor. The method posted. 9. Part of the particles discharged from the lower part of the wet reactor is recycled into the wet reactor 9. The method according to claim 8, characterized in that: 10. characterized in that the particles are moistened outside the wet reactor before recycling them 10. The method according to claim 9. 11. Characterized by the fact that the gas is cooled in a humid reactor to a temperature of about 0-20 °C from the dew point The method according to claim 1, wherein: 12. Claim characterized in that the gas is cooled to a temperature of about 0-10°C from the dew point. The method described in 11. 13. In particular, the volume of the ash layer is at least 50 kg per m3/s of inlet gas. 2. The method according to claim 1, wherein the method is characterized by: 14. Claim 1, characterized in that the thickness of the ash layer is at least 25 cm. The way I did it. 15. Claim characterized in that the ash layer reaches at least the level of the mixer shaft. The method described in 1. 16. At least part of the gas to be introduced into the wet zone is as a jacket flow. The wet reactor is fed into the wet reactor as a spray so that the gas flows downwards. into the wetting zone through ducts located in the walls and/or along the walls of the wetting reactor. This jacket flow prevents the wall from cooling and solidifies it. The method according to claim 1, characterized in that it prevents body layers from depositing on the walls. Law. 17. At least part of the gas to be introduced into the dry zone is as a jacket flow. The gas is guided into the wet reactor and for this purpose the gas passes through a duct placed in the wall of the wet reactor. The cooling of the wall is prevented by flowing into the dry zone through the The method described in claim 1. 18. Characterized by the fact that water or steam is supplied as a downward spray into the wet zone The method according to claim 1, wherein: 19. characterized in that water or steam is fed into the wet reactor in a continuous band A method according to claim 1. 20. Recirculation or internal particle circulation in the wet reactor regulates the flow of ash to be discharged 2. A method according to claim 1, characterized in that the method is controlled by: