CZ290636B6 - Process for dry desulfurizing gaseous combustion products of fossil fuels and apparatus for making the same - Google Patents

Abstract

The suggested process is characterized by dispersion of water, in turbulent way, in a stream of combustion products after addition of a desulfurizing agent therein and separation solid particles of the reacted desulfurizing agent together with fly ash from the combustion products. Apparatus for dry desulfurizing gaseous combustion products employed for the above indicated process comprises a desulfurizing column (4) in the bottom section of which there is disposed an apparatus (21), by means of which water is dispersed into the gaseous products stream in a whirling way. This apparatus consists of a water inlet (14), a dispersing gas inlet (15) dispersing nozzles (12) and a dispersion means (16) situated above the nozzles (12) and serving for making whirls of water with the dispersing gas in the stream of the desulfurized gaseous products.

Description

Technical field

The present invention relates to a method for dry desulfurization of flue gases resulting from the combustion of fossil fuels containing considerable amounts of simulated compounds. Such fuels are different types of coal and heavy oils. The invention also relates to an apparatus for desulfurization of the resulting flue gases (flue gases) in order to eliminate their harmfulness before being released into the atmosphere.

BACKGROUND OF THE INVENTION

Fossil fuels, such as heavy oils and coal, are widely used in combustion plants, such as thermal power plants. The flue gases leaving such combustion plants usually contain 1 to 50.10 ^-2 % of harmful acidic substances such as sulfur oxides (SO _x ) and hydrochloric acid. When such harmful substances are released into the atmosphere, they cause acid rain and photochemical smog. To eliminate such harmful substances, desulphurisation equipment is installed. Desulphurization processes are divided into wet and dry processes. A representative example of wet desulfurization is a method using limestone and producing gypsum. This method is particularly suitable when it is necessary to achieve a highly efficient desulfurization. The main feature of the dry type method, on the other hand, is the fact that no waste water is produced. Examples of dry-type desulfurization methods include the activated carbon process and the reaction method using alkali metal compounds or the like. In particular, the latter method is economically advantageous if its economy relates to a mass unit of sulfur dioxide.

In a typical example of this method, the flue gas (flue gas) from the boiler is cooled in an air heater and fed to a desulfurization column. The desulfurizing agent, which may be slaked lime, is dispersed into the flame in the furnace or the flue gas duct or into the heat exchanger outlet or desulfurization column. Simultaneously with the water jets located on the manifold ring, the incoming water disperses by means of the incoming air to cool the flue gases while increasing their humidity, which promotes the desulfurization reaction.

The water may be supplied separately or with the desulfurizing agent in the form of a slurry. The reacted desulfurizing agent is trapped in the dust separator together with the ash from the off-gas. Sometimes the part of the entrapped particles that contains the unreacted desulfurizing agent is fed back to the desulfurizing agent preparation device again dispersed into the flue gas duct or desulfurization column.

The higher the relative humidity, the higher the desulfurization efficiency is achieved. The reason is that as the moisture inside the desulfurization column rises, the content of water adsorbed on the surface of the slaked lime dispersed in the desulfurization column also increases. Sulfur dioxide from the flue gas can more easily dissolve in this water to form sulfuric acid. The reaction between H 2 SO 3 and Ca (OH) 2 is a neutralization reaction that proceeds rapidly to form CaSO ₃ and is stable under these conditions.

When the water content of the slaked lime is high, the amount of dissolved SO2 is also large, so that considerable moisture is desirable. The resulting CaSO ₃ increases in volume, thereby destroying the CaSO ₃ layer covering the slaked lime particles and re-exposing the slaked lime surface to SO ₂ , thereby accelerating the desulfurization reaction.

It is therefore desirable to maximize the relative humidity. However, in a real plant at high relative humidity, water condenses either in the low temperature part of the desulfurization column, in the subsequent dust separator, or in another part of the flue gas duct. This raises problems, such as formation of liquid waste, the formation of scale and the corrosion of the material upon exposure to H ₂ SO ₃ or H2SO4.

- 1 GB 290636 B6

In addition, at high relative humidity, the temperature in the bottom (conical) part of the desulfurization column decreases, causing condensation of water vapor on the bottom of the column or wetting of the desulfurizing agent, so that the powdered desulfurizing agent has reduced fluidity, making it difficult to remove the bottom of the desulfurization column.

Therefore, it is customary to control the temperature of the bottom of the desulfurization column so that it is about 10 ° C higher than the saturation temperature at the outlet thereof. The relative humidity is maintained at about 60%. With such temperature control, the relative humidity cannot be higher than the stated value, and therefore the desulfurization efficiency is also low.

On the other hand, in order to increase the desulfurization performance and maintain the relative humidity to about 60%, countermeasures have been proposed (Japanese Unexamined Patent Application No. 2-152520). After the addition of water and siliceous materials such as ash and coal to a desulfurizing agent such as slaked or quicklime, the formed slurry is heated to form a large specific surface area of the desulfurizing agent and thereby a large SO ₂ absorbing capacity. However, when the desulfurizing agent is prepared by said process, it is necessary to heat the desulfurizing agent material to high temperatures, above 100 ° C, for a long time (ten to several tens of hours) as described in the cited Japanese patent application. This makes the desulfurizing agent preparation large and the energy consumption for heating also increases. If the heating temperature is lower or the heating time is shorter, the desulfurization efficiency decreases. In addition, it disperses into the slurry desulfurization column, the spray nozzle wears at a much higher rate than when dispersing the powder, and there are also problems with slurry sedimentation in the pipeline. The use of a desulfurizing agent having a large specific surface area also presents a further problem, namely the fluidity of the slurry, which has to be overcome by using more water. Compared to the method in which the desulfurizing agent is supplied in the form of a powder, the slurry has to be additionally dried, thus the system becomes complicated and the cost of the desulfurizing agent produced increases.

As is known, the desulfurization efficiency increases with the relative humidity in the desulfurization column and in the dust / fly ash separator, but the desulfurizing agent and fly ash deposit on the inner surface of the apparatus, which then corrodes. However, these problems are ignored and therefore desulfurization columns cannot function stably for extended periods of time and the functionality of the entire system is often impaired. Conversely, if the flue gas temperature in the desulfurization column rises (i.e., the relative humidity is reduced), deposits and corrosion may be somewhat suppressed, but the desulfurization efficiency is reduced.

From publications dealing with the flue gas desulphurisation problems, DE 40 23 030 A1 proposes to supply a furnace or flue gas desulphurization agent, which is a salt obtained by at least partially neutralizing the calcium desulphurization agent with acid. , especially organic, such as acetic, oxalic or formic acid. In DE-A-38 05 037 C2, a process for purifying gases containing harmful substances is carried out by dividing the hot gas stream into at least three consecutive stages by indirect heat exchange, these steps being up to 200 ° C, 300 to 400 ° C and 900-1050 ° C. The desulfurizing agent is then divided into individual stages. WO 92/01509 (PCT / US91 / 03644) discloses a process for preparing a mixture of aluminum materials to remove SO _X from gases. According to this document, a ramming clay suspension in water is prepared to which an alkali metal or alkaline earth metal salt is added, the suspension is dried and the dried material is used as a desulfurizing agent. Japanese Patent Application No. 63-306025 describes the preparation of an absorbent slurry for desulfurization and denitration of gases. In this process, the silica material is ground and lime material and water are added thereto, with further grinding and stirring to obtain the desired absorbent slurry. The aforementioned drawbacks of the prior art in this field are largely eliminated in the dry flue gas desulphurisation process of fossil fuels and in the apparatus for carrying out the process of the invention.

-2GB 290636 B6

SUMMARY OF THE INVENTION

SUMMARY OF THE INVENTION The present invention provides a process for dry desulfurization of fossil flue gas, wherein a desulfurizing agent is added to the flue gas and the solid particles of the reacted desulfurizing agent and fly ash are separated from the desulfurized flue gas.

The essence of the dry flue gas desulfurization process of the present invention is that after addition of the desulfurizing agent to the flue gas stream, water is dispersed and the solid particles of the reacted desulfurizing agent are separated from the flue gas together with the fly ash.

The water is preferably dispersed into the flue gas by means of a scattering gas, which is air or water vapor.

It is preferred to cool the flue gas prior to desulfurization by exchanging heat to a temperature below 200 ° C and to add a desulfurizing agent in this temperature range.

Water is usually dispersed in the flue gas stream in an amount of 0.02 to 0.05 liters per Nm ^{3 of} flue gas.

It is particularly preferred to disperse water into the flue gas stream at an angle of 40 to 180 ° relative to the flue gas stream. Water is scattered into the flue gas stream to form a moisture gradient in a plane perpendicular to the direction of the flue gas stream, whereby the moisture gradient decreases from the center of the flue gas stream towards the periphery of the flue gas stream.

The separated solid particles of the reacted (predominantly) desulfurizing agent together with the fly ash may, after separation from the flue gas stream, be fed to the flue gas stream in a temperature range of 500 to 900 ° C to react the desulfurizing agent.

According to the invention, water can be added to the separated solid particles of the reacted desulfurizing agent and fly ash, and the resulting slurry can be fed into the flue gas stream in a temperature range of 500 to 900 ° C.

In another embodiment of the process of the invention, the resulting slurry is dried and the resulting powder is sprayed into a flue gas stream in a temperature range of 500 to 900 ° C.

The present invention also relates to an apparatus for dry desulfurization of fossil flue gas gases which is composed of a desulfurization column, into the bottom of which a flue gas duct extends from a fossil fuel furnace, desulfurizing agent reservoir and a desulfurizing agent and fly ash separator connected to the desulfurizing plant. flue gas column.

The principle of this device is that in the bottom of the desulfurization column there is an apparatus for swirling water dispersion into the flue gas stream, which consists of a water supply, a dispersion gas supply, dispersion nozzles and dispersing means situated above them to create water swirls with dispersion gas in a stream of flue gas desulphurized.

In one preferred embodiment of the device according to the invention, a heat exchanger is arranged between the flue gas leading from the fossil fuel furnace and the flue gas leading to the bottom of the desulfurization column, and the outlet of the desulfurizing agent reservoir is directed to the flue gas duct.

The scattering nozzles are preferably located 1 to 5 m from the flue gas inlet to the desulfurization column.

Another embodiment of the device according to the invention is characterized in that the vortex water scattering apparatus is composed of two groups of scattering nozzles which are located in opposite parts of the desulfurization column.

-3GB 290636 B6

Advantageously, the apparatus is further provided with a portion of hot flue gas or heated air connected to the flue gas duct to the desulfurization column.

The dispersant is in the form of a plate, plate or cylinder. The dry flue gas desulphurisation process of the present invention and the apparatus of the present invention achieve a high degree of desulfurization and prevent the formation of deposits on the walls of the apparatus, thereby preventing corrosion thereof.

When slaked lime Ca (OH) _{2 is considered} as an example of a desulfurizing agent, the desulfurization reaction with SO ₂ gas can be expressed as follows:

H ₂ O + SO ₂ -> H ₂ SO ₃

Ca (OH) ₂ + H ₂ SO ₃ -> CaSO ₃ + H ₂ O

According to reaction (1), SO _{2 is} absorbed with water and the resulting sulfuric acid, which, according to reaction (2), then reacts with slaked lime to calcium sulfite. If areas with high humidity are formed in the desulfurization column, the water content of the slaked lime increases, which supports the reaction (1). The desulfurization efficiency is then greater in such high humidity zones. Humidity in areas other than high humidity areas is low, but all of the supplied water evaporates at the outlet of the desulfurization column, and therefore the moisture increases so as to achieve a determined desulfurization efficiency that is high.

In conventional technologies, a surface of calcium sulfite or calcium sulfate is formed on the surface of the desulfurizing agent that has reacted with SO ₂ in the flue gas at temperatures up to 200 ° C, so that the desulfurizing agent contacts the SO ₂ and no further desulfurization takes place. However, if the desulfurizing agent is scattered again into the flue gas at a temperature of 500 to 900 ° C, a dehydration reaction takes place which disrupts the calcium sulfite shell so that good contact of the desulfurizing agent with SO ₂ is restored and the desulfurization efficiency is increased. A portion of the calcium sulfite is oxidized to calcium sulfate, thereby facilitating its deposition in the landfill.

When the water in the desulfurization column is dispersed, the desulfurizing agent disperses into the flue gas. Part of the desulfurizing agent is not transferred to the dust separator, but settles at the bottom of the desulfurization column. Moistening reduces the flowability (flowability) of the desulfurizing agent. When the temperature at the bottom of the desulfurization column is reduced, water in the gas condenses on the surface of the desulfurization agent and on the walls of the bottom of the desulfurization column, so that the flowability of the desulfurization agent decreases further. This disrupts the smooth removal of the desulfurization agent from the bottom of the desulfurization column.

The bottom of the desulfurization column is equipped with a manifold for blowing a portion of the hot flue gas or heated air up along the wall of the bottom of the desulfurization column. This removes moisture from the settled desulfurizing agent while maintaining the temperature of this portion at a temperature 5 ° C higher than the saturation temperature of the flue gas, thereby preventing water condensation on the inner walls of the bottom of the column.

These measures can increase the flowability of the settling desulfurizing agent and ensure its smooth removal from the bottom of the column. For this purpose, the temperature at the bottom of the desulfurization column is measured and the amount of flue gas or heated air supplied to the bottom of the column is controlled accordingly.

Water is dispersed in the desulfurization column to cool the flue gas. When water droplets come into contact with the flue gas, they evaporate by the heat of the flue gas. Thus, the water is converted to steam before it leaves the desulfurization column. When converted to water vapor, the temperature of the water droplets is not the same as that of the flue gas, but is reduced by the latent evaporation heat of the water, usually an adiabatic saturation temperature is achieved.

-4GB 290636 B6

In order to control the amount of water dispersed in the desulfurization column, it is therefore advisable to measure the temperature of these droplets in order to avoid condensation of water in the flue gas while increasing the desulfurization efficiency.

However, the size of the water droplets in the desulfurization column is only a few tens of pm and it would be difficult to measure their temperature by conventional measurement techniques. If, for example, a rod thermometer is inserted into the column, only the gas temperature can be measured, since the water droplets are carried by the gas.

Therefore, the temperatures in the various parts of the desulfurization column were measured in detail, and the part of the column in which the temperature was the same as the water droplets was detected. It is the part that the spray droplets directly hit. By measuring this temperature in this part of the column, the temperature of the flue gas at the outlet of the desulfurization column is controlled, while avoiding condensation of water which promotes the formation of deposits. Thus, high desulfurization efficiency can be achieved.

In conventional technologies, siliceous substances, such as coal ash, are added to the corrosive earth metal compounds, such as slaked lime, and then the mixture is heat treated in the presence of water. The reactivity between the corrosive earth metal compounds and the silica is poor, so heating to at least 1000 ° C must take place over a longer period (ten to several tens of hours). In addition, since the desulfurizing agent prepared is in the form of a slurry, much energy is required to dry it and convert it into a powder. When the desulfurizing agent is sprayed through the slurry nozzle, the nozzle is heavily worn and the slurry particles sediment in the lance. However, if sodium silicate is added to the slurry, the slurry is matured when the slurry is mixed and the dispersibility of the caustic and silica compounds in the water is stabilized so that their reactivity with each other is also improved. Therefore, a desulfurizing agent having a high SO ₂ -sorbency can be prepared by this maturation process at a lower temperature and in a shorter time. When the slurry is heated, the dispersibility (dispersibility) of the particles of the corrosive earth compound and the siliceous substance in the water increases simultaneously. The slurry thus prepared diffuses into the flue gas duct and has a high desulphurization capacity.

From the caustic earth compound, an oxide is obtained which is mixed with a silica substance (coal ash, sodium silicate, etc.) and water. The hydration heat generated by the addition of water induces a reaction between the desulfurizing agent and the siliceous material and also causes the excess water to evaporate. With this method, a desulfurizing agent having a high desulfurizing capability can be produced more economically.

In this case, sodium silicate is added in the form of an aqueous solution to the caustic earth metal, so that a considerable amount of hydration heat is released, and therefore no additional thermal equipment is required to evaporate the excess water.

The flue gas leaving the boiler and containing harmful acidic substances such as SO ₂ is fed to a heat exchanger, in which it heats the desulfurized flue gases exiting the desulfurization column, thereby lowering their temperature. The flue gas with such a reduced temperature enters the desulfurization column and the SO ₂ contained therein is removed with a desulfurizing agent comprising fine particles of at least one compound selected from the group of alkali metal and alkaline earth metal compounds. At the same time, in order to increase the desulfurization efficiency, the temperature of the flue gases fed to the desulfurization column is reduced by the already desulfurized flue gases leaving the desulfurization column. Thus, the flue gases exiting the desulfurization column are heated in the heat exchanger before they enter the dust separator. The flue gas temperature at the outlet of the desulfurization column can thus be adjusted to a value just above the adiabatic saturation temperature and the desulfurization efficiency can then be very high.

In the processes of the present invention, the desulfurization efficiency may be higher than the conventional methods for the reasons described below, the desulfurization apparatus may be smaller and the desulfurizing agent used may be less.

-5GB 290636 B6 [1] Desulphurization efficiency is increased due to locally generated areas with high humidity.

[2] The unreacted desulphurisation agent is captured by a dust trap and is again sprayed into flue gas at a temperature of 500 to 900 ° C. This results in a dehydration reaction (Ca (OH) ₂ -> CaO + H ₂ O) and destruction of the sulphite or calcium sulfate shell, so that the contact of the desulfurizing agent and SO ₂ is improved, which increases the desulfurization efficiency.

[3] Part of the flue gas or heated air is fed to the bottom of the desulfurization column. Thus, condensation at the bottom of the desulfurization column and desulfurizing agent deposits on the walls can be prevented even when the relative humidity inside the desulfurization column is high. Also, the moisture of the deposited desulfurizing agent is reduced, thereby improving its fluidity. As a result, the bottom of the desulfurization column is not closed or blocked and therefore the desulfurization agent deposited can be drained smoothly from the desulfurization column and the desulfurization efficiency can be maintained at a high level.

[4] The temperature at the point where the droplets directly fall is measured and the amount of spray water supplied is controlled according to this temperature. Thus, the temperature at the outlet of the desulfurization column is maintained at a level above the condensation temperature of the water. This prevents the condensation of water and the formation of deposits due to this condensation. Therefore, it is possible to maintain a high relative humidity within the desulfurization column. This increases the desulfurization efficiency, the desulfurization column can operate stably for a long time, and the apparatus can be constructed in a compact manner.

[5] The siliceous substance is mixed with at least one of the alkali or corrosive earth oxides and water is added to the mixture. The two substances react together and the excess heat is removed by the reaction heat released by the hydration of the oxide. Thus, a desulfurizing agent having a high specific surface area is prepared. Therefore, high desulfurization efficiency can be achieved.

[6] Sodium silicate is added to the desulfurizing agent containing calcium-containing particles, thereby increasing the dispersibility of the calcium-containing solids or siliceous particles in water. As a result, their mutual reactivity is also increased and the desulfurizing agent having higher desulfurization efficiency can be prepared more economically (at a lower temperature and in a shorter time). High desulfurization efficiency can be achieved even when the Ca / S ratio is low and when the mean residence time of the particles when mixing the slurry is high.

[7] The dispersibility of sodium silicate, calcium-containing substances and silicon-containing substances in water is further enhanced by heating. Moreover, the dispersibility of the calcium-containing and silicon-containing substances is increased by the fact that the slurry is intensively mixed in a high shear mixer or wet grinding of the slurry.

Overview of the drawings

Giant. 1 Scheme of desulfurization plant according to Examples 1 and 4.

Giant. 2A and 2B The conditions for dispersing water in the desulfurization column shown in FIG. 1.

Giant. 3 Arrangement of water dispersion nozzles in a desulfurization column according to Examples 2 and 3.

Giant. 4 is a cross-sectional view of a water dispersion nozzle with a gas tube for vortexing, as shown in FIG.

Giant. 5A and 5B Conditions under which vortices are formed when water is sprayed into the flue gas through the nozzle shown in FIG. 4.

Giant. 6 Dispersion plates positioned above the water jets shown in FIG. 4.

-6GB 290636 B6

Giant. 7 Diagram of the desulfurization efficiency versus the spray angle of the water nozzle of Fig. 5. Giant. 8 Diagram of the desulfurization efficiency versus the mean diameter of the water droplets sprayed through the nozzle of Fig. 5. Giant. 9 Diagram of desulfurization efficiency versus surface velocity using nozzles of Fig. 5. Giant. 10 Diagram of the flue gas desulfurization efficiency versus the angle of the fixed nozzles according to Fig. 5. Giant. 11 Water spray conditions in the desulfurization column of Example 5. Giant. 12 Diagram of test results according to Examples 1 to 5. Giant. 13 Scheme of the desulfurization plant of Example 6. Giant. 14 Diagram of desulfurization efficiency versus diabetic saturation temperature. Giant. 15 Dec Scheme of desulfurization plant according to Example 7. Giant. 16 Scheme of the desulfurization plant of Example 8. Giant. 17 Diagram of desulfurization efficiency versus flue gas temperature in the flue gas duct according to Example 9.

Giant. 18A and 18B. Diagram of the desulfurizing agent particle behavior of Example 10.

Giant. 19 Dec The relationship between desulfurization efficiency and the amount of desulfurizing agent supplied (Ca / S ratio) according to Example 10. Giant. 20 May Scheme of the desulfurization plant of Example 13. Giant. 21 Scheme of desulfurization plant according to Example 14. Giant. 22nd Scheme of the modified desulfurization plant according to Example 14. Giant. 23 Scheme of the desulfurization plant of Example 15. Giant. 24 Detail of a part of the desulfurization column of Fig. 23 with a water scattering apparatus. Giant. 25 Block diagram of the desulfurizing agent preparation apparatus of Example 17. Giant. 26 Diagram of desulfurization efficiency versus Ca / S ratio according to Example 18. Giant. 27 Mar: Diagram of the desulfurization efficiency versus the amount of sodium silicate added according to Example 19. Giant. 28 Diagram of the desulfurization efficiency versus the amount of sodium hydroxide added according to Example 20. Giant. 29 Block diagram of the desulfurizing agent preparation apparatus of Example 21. Giant. 30 Diagram of the relationship between desulfurization efficiency and temperature within the hydration apparatus of Example 21. Giant. 31 Block diagram of the desulfurizing agent preparation apparatus of Example 24.

-7EN 290636 B6

Giant. 32 Diagram of desulfurization efficiency versus Ca / S ratio according to Example 25 and Comparative Example. Giant. 33 Diagram of the desulfurization efficiency versus the amount of silicate added according to Example 26. Giant. 34 Diagram of specific surface area versus amount of sodium silicate added according to Example 26. Giant. 35 Diagram of desulfurization efficiency versus quicklime temperature according to Example 27. Giant. 36 Scheme of the desulfurization plant of Example 30. Giant. 37 Diagram of desulfurization efficiency versus Ca / S ratio according to Example 31 and Comparative Example. Giant. 38 Diagram of the desulfurization efficiency vs. mean residence time of the part in the apparatus of Example 32 and Comparative Example. Giant. 39 Diagram of the desulfurization efficiency versus the amount of sodium silicate added according to Example 36. Giant. 40 Diagram of the desulfurization efficiency versus shear mixing rate of the slurry in the desulfurizing agent preparation apparatus of Example 33. Giant. 41 Scheme of the desulfurization plant of Example 35. Giant. 42 Diagram of desulfurization efficiency versus sodium silicate viscosity according to Example 35. Giant. 43 Scheme of the desulfurization plant of Example 36. Giant. 44 Scheme of the desulfurization plant of Example 37. Giant. 45 Temperature versus desulfurization efficiency diagram.

In the following examples, the method and apparatus of the present invention are described in more detail.

DETAILED DESCRIPTION OF THE INVENTION

Example 1

The flue gas exiting the coal-fired boiler is desulfurized and slaked lime is used as the desulfurizing agent.

According to Fig. 1, the flue gas from the boiler 1 is cooled in the air heat exchanger 3 and fed to the desulfurization column 4 via a flue gas duct 6. The desulfurizing agent (slaked lime) is supplied to the flue gas duct 13 from the reservoir 5 via a supply pipe W. water is dispensed through line 14 and sprayed through nozzles 12. The same nozzles also disperse air or vapor supplied through line 15. Nozzles 12 are two fluid for atomizing water by air. The water droplets dispersed by the nozzles 12 come into contact with the flue gas exiting the boiler at a temperature of about 150 ° C, so that

-8GB 290636 B6 evaporate. Immediately above each dispersion nozzle 12 is a dispersion roll 16. According to FIG. 2A, the stream of dispersed droplets is interrupted by the dispersion roll 16 and swirls upward. The rollers cause high turbulence. The water droplets are vigorously mixed with the flue gas over the dispersion cylinder 16, and at the same time a large number of vortices 17 (Karman's vortices) are formed with high humidity.

The water droplets evaporate in these vortices: As a result of the vortex formation, their interior does not mix with the flue gases outside the vortices, so the interior of the vortices has a high humidity. The vortex contains SO2 from the flue gas and a desulfurizing agent, which are stirred over the dispersion cylinder 16 and reacted together under high humidity conditions to achieve a high degree of desulfurization efficiency. In areas without vortices, humidity is low. The vortices disintegrate as they move towards the exit of the desulfurization column 4. When all the droplets evaporate, the moisture rises to an average water concentration, and thus a desulfurization reaction efficiency corresponding to that moisture can be achieved. Indeed, regions of high water concentration, i.e., regions with high humidity vortices, are formed only in place within the desulfurization column 4, thereby increasing the reactivity within the vortices and thereby increasing the desulfurization efficiency at the exit of the desulfurization column 4.

This method contrasts with the conventional method of ensuring good mixing of water droplets and flue gas to increase evaporation rate, thereby achieving a rapidly uniform distribution of water concentration. In the process according to the invention, however, a higher desulfurization efficiency is achieved.

The desulfurization test was carried out on this apparatus under the following conditions. Coal A is burned in the boiler and the SO ₂ concentration in the flue gas is 0.2%. The desulfurizing agent is slaked lime, which is supplied at twice the molar amount relative to the amount of SO ₂ contained in the flue gas (hereinafter referred to as the "Ca / S ratio"). The water is dispersed through the nozzles 12 so that the exhaust temperature of the flue gas from the desulfurization column is 70 ° C. The liquid / gas ratio (feed water flow / flue gas flow containing sulfur oxides through the flue gas duct) is 0.04 liter / m ^{3 of} flue gas and the average water droplet size is 30 µm, the nozzles 12 being located 1.5 m from the flue gas inlet to the desulfurization column 4. The nozzle water scattering angle A is 50 ° and the surface velocity of the gas in the desulfurization column 4 is 2 m / s. In Fig. 2B, the angle A of the water dispersion through the nozzle 12 is shown in vertical section of the nozzle.

At the outlet of the boiler 1 and the outlet of the dust separator 8, the SO ₂ concentration is measured, which is 0.2 and 0.04% at these two locations. Hence, 80% of SO ₂ is removed from the flue gas. The degree of Ca utilization in the desulfurizing agent particles trapped at the bottom of the dust separator is 40%.

Example 2

Referring to Figures 3 to 5B, the apparatus 21 is located within the desulfurization column so that the water dispersion nozzles are directed upstream of the gas flow. As can be seen from the detail of Fig. 4, the mouth of the water tube 14 is located in the center of the dispersing nozzle 12 and the mouth of the tube 15 supplying the atomizing gas surrounds the mouth of the water tube 14. Therefore. In addition, the gas tube 18 that separates the vortices surrounds the spray water nozzle 12 and therefore vortices containing fine water particles sprayed from the mouth of the nozzle 12 can easily be separated from the nozzle 12.

Since atomized water is sprayed in a direction opposite to the flue gas flow direction, stable vortices 17 are formed near the water spray nozzle 12 as shown in Figures 5A and 5B. Since the stable vortices 17 contain sprayed water droplets and because they separate from the nozzle 12, a vortex stream 17 is produced with high humidity. In Fig. 5A, water is ejected at a nozzle angle of 180 ° relative to the flue gas flow, and in Fig. 5B, water is ejected at a nozzle angle of 135 ° relative to the flue gas flow.

Nozzle angle means the angle between the trajectory of a particle emerging from the nozzle in the direction of its axis and the flue gas flow direction in the desulfurization column. A stable vortex 17 is formed at the same location

-9GB 290636 B6 and practically does not mix with the surroundings. Therefore, a gas is admitted to the vortex separating tube 18 which separates the vortices 17 from the water nozzle 12. The vortexes 17 just separated are entrained by the flue gas upwards and hence fresh vortices 17 having high humidity are created repeatedly. Although the vortex separating gas can flow continuously, a greater effect is achieved by interrupting the gas flow. Water is injected into vortices 17 with high humidity against the flue gas flow. Therefore, the sprayed water droplets are immediately retarded and then entrained in the flue gas.

Owing to the formation of vortices 17 of the desulfurizing agent and the flue gas containing SO ₂ good mixing and entering the vortices 17. Because these vortices 17 are present in water droplets which evaporate, it can easily be achieved relative humidity close to 100%. The vortices 17 separated from the vicinity of the nozzle 12 are mixed with the surrounding flue gas to a limited extent, flowing with the flue gas and retain high humidity. Therefore, the interior of these vortices shows high desulfurization efficiency.

The high humidity vortices 17 are mixed with the surrounding flue gas at the outlet of the desulfurization column 4, the water concentration increases to a uniform level and therefore a high overall desulfurization efficiency is achieved.

Since the diameter of the desulfurization column 4 is relatively large compared to the diameter of the flue gas duct 13, the flow velocity in the connecting widening portion slows and a backflow region is formed. Therefore, the desulfurizing agent particles flowing through the flue gas duct 13 enter the reflux region and thus become stagnant, i.e. they float and form an area in which the desulfurizing agent concentration is high. This region extends from the inlet of the flue gas duct 13 to a distance generally equal to the diameter of the desulfurization column. As a result of the spraying of water in this region, the high concentration desulfurization agent is contacted with vortices of high relative humidity, and therefore a higher desulfurization efficiency can be achieved.

The desulfurization test of this apparatus was performed under the same conditions as in Example 1.

The SO ₂ concentration was measured in the gas from which water vapor was removed at the outlet of boiler 1 and at the outlet of the dust collection facility 8. Concentrations of 0.2 and 0.04% were found. 80% SO ₂ in the flue gas is thus removed by this procedure. The Ca utilization in the desulfurizing agent particles obtained from the bottom of the dust separator 8 is 40%.

Comparative example

The desulfurization test of a conventional coal A desulfurization plant was conducted under the same conditions as in Example 1. The desulfurization apparatus used in the Comparative Example differed from the apparatus used in Example 1 in that the water distributor nozzles inside the desulfurization column were adapted to inject water. parallel to each other, in the same direction as the flue gas flows.

At the same time, the SO ₂ concentration at the outlet of the dust separator was 8.10 ² % and a desulfurization efficiency of 60% was achieved. The Ca utilization in the desulfurizing agent particles obtained from the bottom of the dust separator is 30%.

Example 3

In this example, a desulfurization apparatus similar to that described in Example 2 is used. As in Example 2, water is sprayed inside the desulfurization column in a direction intersecting the flue gas flow. The desulfurization test for coal A is carried out in the same manner as in Example 1. As shown in Fig. 6, this example differs from Example 2 in that the dispersion plate 16 is positioned immediately above each water nozzle to safely create vortices 17 Atomized water droplets are exposed to the dispersion plate 16 and must flow around and then flow

-106 290636 B6 together with the flue gas stream. These water droplets are vigorously mixed with the flue gas on the dispersion plate 16, and at the same time a high number of vortices 17 are generated.

As a result of this process, the inner part of the vortex 17 retains high humidity and reaction between SO? and the desulfurizing agent is promoted. In the desulfurization test, the concentration of SO? at the outlet of the 3.10 " ² % dust separator and the Ca utilization in the desulfurizing agent particles obtained from the bottom of the dust separator was 42.5%.

As already mentioned, when water and atomizing gas are injected into the flue gas in the opposite direction to the flue gas flow, high humidity areas are created. Therefore, desulfurization tests for different spray directions and a comparison test in which water was injected parallel to the flue gas flow were performed on the apparatus of Example 2. The parameters used are as follows:

The spray angle A (see Fig. 2B) of the water spray nozzle was 10, 20, 30, 50, 70, 120, 140, 160 and 180 °, the mean diameter of the water droplets was 10, 20, 30, 50, 70, 100, 140 170 and 200 µm and the mean sequential gas velocity was 0.5; 1.0; 3.0; 5.0; 7.0; 10.0 and 15 m / s.

The results of these tests are shown in Figures 7, 8 and 9. It has been found that spraying water against the flue gas direction results in higher desulfurization efficiency compared to co-jet spraying.

Water jet spray angle A: 20 to 90 °: Center of droplet diameter: 20 to 140 μπι. Gradual flue gas velocity in the desulfurization column: 1 to 10 m / s.

Example 4

In order to find a suitable mounting angle of the water spray nozzle 12 with respect to the flue gas flow, as shown in FIG. 5B, a desulfurization test was performed with different mounting angles. The desulfurization test was carried out with coal and under the same conditions as in Example 2.

The results of this test are shown in FIG. 10. When the water-containing fluid is sprayed at an angle of between 40 and 180 °, a higher desulfurization efficiency is achieved than with a co-current flow.

The SO2 concentration at the dust separator outlet was 4.10 ~ ² % and the desulfurization efficiency achieved was 80%. The use of Ca in the desulfurizing agent particles obtained from the bottom of the dust separator is 40%.

It is not appropriate if the liquid / gas ratio is less than 0.02 L of water per m ^{3 of} flue gas, because in this case the flue gas temperature becomes high and the desulfurization efficiency decreases. On the other hand, if the liquid / gas ratio is greater than 0.05 l of water per m ^{3 of} flue gas, the flue gas temperature approaches an adiabatic saturation temperature and the water content often reaches a dew point, which is also not appropriate. The liquid / gas ratio should be between 0.02 and 0.05 l of water per m ^{3 of} flue gas.

The location of the water spray nozzles 12 will be described, for example, for the desulfurization column design shown in Fig. 3. If the spray water is injected onto the wall of the desulfurization column, or other structure within the desulfurization column 4, it is moistened and allowed to collect dust and create dust deposits on wet parts. To prevent this, the moisture in the plane perpendicular to the flue gas flow must fall from the central part of the column to its wall. Also, the column outlet temperature must be maintained above the saturation temperature. To ensure this, the nozzle 12 is positioned in a plane of a perpendicular gas flow within the desulfurization column, a plane parallel to the gas flow, thereby ensuring that the wall portion of the column has as low humidity as possible. Further, it is desirable that the effective distance of the desulfurization column wall from the nozzles considered in the direction of gas flow be of sufficient size. When the water jets 12 are mounted high, the overall height of the desulfurization column increases, which is uneconomical.

-11 CZ 290636 B6

Thus water spray nozzles should preferably be placed so that the ratio L / D (distance from the inlet / diameter desulfurization column) was greater than 1 (for equipment which has a processing capacity of several tens of thousands of m ³ per hour, the nozzle should be positioned within 5 m of the desulfurization column inlet in the direction of the flow of liquids.

Example 5

In the example shown in Fig. 11, the groups of water nozzles 12 are positioned opposite each other so that in this desulfurization column 4 the water jets are sprayed against each other. Stable vortices are formed at the outlets of the water nozzles 12 downstream of the flue gas. By impacting the jets from each other, the pressure in this impingement portion rises, so that the jets flow upward downward, rightward and leftward. Because of these fluctuations, the stable vortices 17 separate from the proximity of the nozzles 12, moving upwards, so that the vortices 17 are formed repeatedly. This creates the effect of enclosing the droplets in the vortices 17 and the overall desulfurization efficiency at the outlet of the desulfurization column is increased as in the previous examples.

The desulfurization test of this apparatus was performed using coal A under the same conditions as in Example 1.

The SO ₂ concentration at the outlet of the dust separator is 4.10 " ² % and the desulphurisation is 80%. The Ca utilization in the desulfurizing agent obtained from the bottom of the dust separator is 40%.

Giant. 12 shows the results of the tests described in the previous examples. Obviously, the desulfurization efficiency achieved with this invention is higher than that of conventional methods.

To sum up, the reaction between SO ₂ and the desulfurizing agent is promoted by creating vortices within the flue gas stream in the desulfurization column. In these vortices, regions of higher relative humidity are formed which promote the desulfurization reaction when admixing the desulfurizing agent. This achieves a high desulfurization efficiency.

In order to efficiently control the amount of water supplied and the fluid dispersion for the water dispersion, the desulfurization column or its outlet must be equipped with at least one of the sensors for measuring temperature, humidity or water concentration. Thereafter, the amount of water and the amount of liquid to disperse it is controlled according to the data of these sensors.

Example 6

Figure 13 shows the application of the present invention to an industrial boiler. The flue gases containing SO _X from coal or heavy oil leaving the boiler 1 are cooled to 150 ° C in an air heater 3. In the case of coal combustion, the water content of the flue gases is about 7 to 10%, in the case of heavy oil combustion 12 to 13%. The flue gas is injected into the heat exchanger 30, where heat is exchanged between the gas leaving the desulfurization column and the incoming flue gas and, consequently, further reducing the flue gas temperature. The flue gas entering the desulfurization column 4, the desulfurizing agent, which is slaked lime or the like, and water, are injected into the desulfurization column so that the SO _X from the flue gas is removed. The desulfurization efficiency is strongly dependent on the temperature inside the desulfurization column 4, i.e. the difference between the temperature inside the column and the adiabatic saturation temperature. The apparatus in this example is characterized in that the desulphurized flue gas leaving the desulphurisation column is heated in the heat exchanger 30 entering the desulphurisation column before entering the dust separator. In this apparatus, the desulfurization column outlet temperature can be reduced to a value just above the adiabatic saturation temperature so that the above-mentioned difference is large and thus a high desulfurization efficiency is achieved.

- 12GB 290636 B6

The relationship between the desulfurization efficiency and the difference between the actual adiabatic saturation temperature was investigated for different gas reaction temperatures using a device allowing accurate humidity control. The results of these experiments are shown in Figure 14. The desulfurization efficiency strongly depends on this temperature difference and it is clear that if the desulfurization column temperature is close to the adiabatic saturation temperature, the desulfurization efficiency is high.

Hot air with a flow rate of 200 m7h, containing 10% water vapor, is produced in a heavy oil-fired furnace, and SO ₂ gas is mixed into the hot air from the SO ₂ cylinder. This results in simulated flue gas, corresponding to flue gas leaving the boiler, in which the concentration is 0.2% SO ₂ . The temperature of the simulated flue gas is maintained by a condenser at approximately 150 ° C, which corresponds to the temperature of the actual flue gas at the outlet of the air heater 3 (see Fig. 13).

When the simulated flue gas is injected into the regenerative heat exchanger (Jungstorm preheater) under the above conditions, their outlet temperature drops to 90 ° C. Then the simulated flue gas is fed to the desulfurization column. The slaked lime is supplied in an amount such that the molar ratio of slaked lime to SO ₂ gas is 2. Based on the temperature information in the central part of the desulfurization column, the water supply is controlled so that this temperature is 5 ° C higher than the adiabatic saturation temperature. In this case, the adiabatic saturation temperature was 59 ° C.

The SO ₂ concentration at the outlet of the desulfurization column is 3.5 to 3.6.10 ^-2 % and the desulfurization efficiency is about 83%.

On the other hand, the temperature of the flue gas leaving the heat exchanger is about 90 ° C and is about 30 ° C higher than the adiabatic saturation temperature. Immediately after the test, the dust separator was disassembled and subjected to a visual inspection. No condensation was found.

Comparative test

A comparative test was performed in the above apparatus. In this case, the heat exchanger was not used and instead the flue gas was directly fed into the dust separator. While monitoring the temperature, water was continuously added so that the gas temperature at the outlet of the desulfurization column was 10 ° C higher than the adiabatic saturation temperature (64 ° C in this case), which would prevent corrosion caused by dew formation inside the dust separator.

The SO ₂ concentration at the desulfurization plant outlet is 8.5 x 10 ^-2 % and the desulfurization efficiency is 58%, which is not much.

Example 7

In this example, shown in Fig. 15, lime 5 serving as a desulfurizing agent is added to the boiler 1 to cause high temperature desulfurization and water 9 is injected into the desulfurization column downstream of the flue gas duct 13 to cause low temperature desulfurization. The heat exchanger is located between the air heater 3 and the desulfurization column 4. This exchanger cools the flue gases entering the desulfurization column and heats the outgoing gas. Also in this example, the reaction temperature inside the desulfurization column 4 can be lowered and an effect similar to Example 6 can be achieved.

In Examples 6 and 7, condensation within the dust collector 8 can be prevented even though the temperature in the desulfurization column is lowered close to the adiabatic saturation temperature. This is ensured by heat exchange between the flue gases entering the desulfurization column 4 and the flue gases exiting the desulfurization column 4. Thus, even when using a unit in which the desulfurization column forms a unit with a dust separator, the operation of the desulfurization column will not be disturbed by corrosion of the dust separator 8. that the desulfurization efficiency depends on the relative humidity, the water content required for

Achieving the same humidity can be reduced by lowering the temperature at the inlet of the desulfurization column and the desulfurization efficiency can be increased.

Example 8

The desulfurization efficiency is evaluated on the apparatus shown in FIG. 16. The apparatus leaves a portion of the particles (trapped in the dust collector 8 and therefore called the trapped particles) containing the unreacted and reacted desulfurizing agent, and the ash and residue is re-injected into the flue 6 , in which the flue gas temperature is 600 to 900 ° C, and then reacts again with acidic pollutants such as SO ₂ in the flue gas.

Using this apparatus, a desulfurization test was carried out in the combustion of coal B (the sulfur content of the coal is 0.8%). Slaked lime was used as the desulfurizing agent and the Ca / S ratio was 1.5. The amount of water injected corresponded to 3% of the flue gas and the water could be injected either with two fluid nozzles together with air or with one fluid nozzles. The outlet temperature of the desulfurization column 4 was 70 ° C. Half of the particles (by weight) trapped in the dust collector 8 were drained and the remainder was injected again from line 22 into the flue gas duct 6 where the flue gas temperature reached 600 ° C.

After removal of the water from the off-gas at the outlet of the boiler 1 and at the outlet of the dust separator 8, concentrations of 6.4.10 ² % and 6.10 ^-3 % SO ₂ were measured. Thus, the desulfurization efficiency was 91%.

Example 9

The desulfurization efficiency was measured using the same equipment and under the same conditions as in Example 8. However, the site into which the trapped particles were injected was changed. The dependence of the desulfurization efficiency on the flue gas temperature in the flue gas duct 6 was investigated. The results are shown in Fig. 17. The desulfurization efficiency depends on the flue gas temperature in the flue gas duct 6 and it appears that the preferred temperature range is 500-900 ° C. Similar examinations have been made with other types of coal and desulfurizing agents and it has also been found to be advantageous to operate in the temperature range of 500 to 900 ° C.

If the temperature is sufficiently high, the dehydration reaction, expressed as the following equation, occurs when slaked lime is used as the desulfurizing agent:

Ca (OH) ₂ ->CaO; + H ₂ O

In this case, the evaporation of the water destroys the sulphite and calcium sulfate skin covering the surface of the desulfurizing agent, and the pores of the desulfurizing agent particles increase their volume.

As a result, the efficiency of contact of the desulfurizing agent with SO ₂ in the flue gas will increase (see Fig. 18A). When the flue gas temperature is low, high desulfurization efficiency cannot be achieved (see Fig. 18 B).

On the other hand, at temperatures above 900 ° C carbon dioxide reacts CO ₂ with a desulfurizing agent to form CaCO _3, which has the effect of reducing the amount of desulfurizing agent that can react with SO _2, and high-temperature scrubbing particles sintered, which prevents increase pore volume. Therefore, in a conventional process where the entrapped particles are mixed into a slurry and injected into the boiler at a gas temperature of 1000 to 1200 ° C, high desulfurization efficiency cannot be achieved.

Example 10

The desulfurization efficiency was measured using the same equipment and under the same conditions as in Example 8. However, the amount of desulfurizing agent used, expressed in molar Ca / S ratio, however

The results are shown in Fig. 19. The desulfurization efficiency is about 80% using a Ca / S ratio of 1.

Example 11

The desulfurization efficiency was measured using the same equipment and under the same conditions as in Example 8, but other types of coal were used, namely five types C to G. Table 1 shows the sulfur content of these types of coal, SO ₂ concentration in the flue gas at the outlet and at the outlet of the dust separator 8 and the calcium sulfate ratio (hereinafter referred to as the "oxidation ratio") in the reacted desulfurizing agent (calcium sulfate and sulfite) discharged from the dust separator 8. High desulfurization efficiency was achieved for all coal types.

Table 1

Type of coal C D E F G Sulfur content (%) 0.3 0.5 0.5 2.0 3.1 SO ₂ at boiler outlet (%) 2,3.10 ' ² 4.0.10 ' ² 4,2.10 ^-2 1,68.10 ^-1 2,55.10 ^-1 SO ₂ at the dust separator outlet (%) 2,5.10 ³ 3,5.10 ^-3 4,0.10 ^-3 1,55.10 ^-2 2,3.10 ^-2 Oxidation ratio (%) 92 90 85 88 85

Example 12

Using the same equipment as in Example 8 and under the same conditions as in Example 8, the desulfurization efficiency was measured. However, other desulfurizing agents CaO, CaCO3, NaOH, and Mg (OH) _{2 were used} and tested for their desulfurizing ability. The results are shown in Table 2.

Table 2

Desulphurising agent CaO CaCO3 NaOH Mg (OH) ₂ SO ₂ concentration at the dust separator outlet (%) 5,0.10 ^-3 1,2.10 ^-2 4,0.10 ^-3 5,0.10 ^-3

Comparative example 2

In the same apparatus as in Comparative Example 1, the oxidation and desulfurization efficiency was measured using six different types of coal B to G under the same conditions as in Examples 8 and 11. Water was added in an amount of 3 wt. % flue gas by spraying into the flue gas duct 6 and 50 wt. % of the particles trapped in the separator were again fed to desulphurisation column 4 via line 22. The results are shown in Table 3. The oxidation and desulphurisation efficiencies found are worse than those achieved in the examples in which the methods of the invention were used.

-15GB 290636 B6

Table 3

Type of coal (B) C D E F G Sulfur content (%) 0.8 0.3 0.5 0.5 2.0 3.1 SO ₂ at boiler outlet (%) 6.4.10 ' ² 2,3.10 ' ² 4,0.10 ^-2 4,2.10 ^-2 1,68.10 ^-1 2,55.10 ^-1 SO ₂ at the dust separator outlet (%) 3.3.10 ' ² 1.7.10 ^-2 1,9.10 ^-2 2,2.10 ^-2 8,6.10 ^-2 1,35.10 ^-1 Oxidation ratio (%) 25 21 15 Dec 22nd 13 22nd

Comparative example

In the same apparatus as in Comparative Example 1, the desulfurization efficiency for coal B was measured under the same conditions as in the experiment of Example 10. The results are shown in Fig. 19. When compared to the desulfurization efficiency achieved by the process of the invention, lower under all conditions and there is a tendency to indicate that the difference between the results is more pronounced when less desulfurizing agent is used.

Comparative Example 4

In the same apparatus as in Comparative Example 1, the desulfurization efficiency for coal B was measured under the same conditions as in the experiment of Example 12 using the desulfurizing agents CaO, CaCO ₃ , NaOH, and Mg (OH) ₂ . The results of these experiments are shown in Table 4. Compared to the desulfurization method of the present invention, the desulfurization efficiency in this comparative example has always been low and the SO ₂ concentration at the outlet of the separator 8 is high.

Table 4

Desulphurising agent CaO CaCO ₃ NaOH Mg (OH) ₂ SO ₂ concentration at separator outlet (%) 2,95.10 ^-2 4,1.10 ^-2 2,5.10 ^-2 3,55.10 ^-2

Example 13

In contrast to the device shown in Fig. 16, where the trapped dry powder particles are sprayed into the flue gas duct 6 at 600 ° C, the trapped particles can be mixed with water to form a slurry which is then sprayed into the flue gas duct 6. As is As shown in FIG. 20, one portion of the entrapped particles is injected from the separator into the desulfurizing agent preparation apparatus 37 and is mixed with the water supplied through line 28 to form a slurry. This slurry is then supplied to the flue gas duct 6 by a pump 29. This method of spraying the slurry into the flue gas duct 6 is advantageous in that the shell of the reaction product on the surface of the desulfurizing agent particle is readily removable and that the desulfurizing agent particle is readily removable and with CO ₂ in the flue gas. As a result, high desulfurization efficiency can be achieved.

The desulfurizing agent supplied through the tube 10 can be recycled. After adding water to the entrapped particles, the particles are dried again, the desulfurization reaction product skin is broken; and the particles are re-injected into the flue gas duct 6. In this method, the particles do not agglomerate due to the destruction of the skin of the desulfurization reaction products upon drying. This improves the spray properties of the desulfurizing agent.

-16GB 290636 B6

Example 14

In the example shown in Fig. 21, the flue gas from the boiler 1 is cooled by an air preheater 3. The desulfurizing agent coming through the tube 10 is sprayed from the nozzle 11. The desulfurizing agent flows through the flue gas duct 13 into the desulfurization column 4. it cooled the flue gas and thus promoted the reaction between the desulfurizing agent and the sulfur oxides in the flue gas. The reacted desulfurizing agent is trapped in the dust separator 8 and removed from the process. Flue gases are discharged through chimney 7.

As already described in the above desulfurization process, a moistened powder having poor fluidity is deposited at the bottom of the desulfurization column 4. To allow the moistened powder to be efficiently removed, it is necessary to maintain the temperature of the lower reservoir 5 ° C above the saturation temperature. flue gas. Therefore, a portion of the flue gas is discharged through the conduit 23 and injected into the bottom of the desulfurization column 4 using a blower 24. In this case, the ring manifold 26 is located at the bottom of the tank and the flue gas is blown up along the tank cone from the ring manifold 26. the amount of flue gas supplied by the manifold 26 based on the data of the temperature sensor 27 located at the bottom of the column. In other words, to maintain the temperature of the bottom of the tank at 5 ° C above the saturation temperature of the flue gas, the amount of flue gas injected is controlled by the blower 24 depending on the temperature of this part of the tank detected by sensor 27. The desulfurizing agent stored at the bottom of the desulfurization column is drained through drain line 25.

After 100 hours of continuous operation, the powder can be easily removed from the lower container. At the end of the experiment, the inside of the desulfurization column was inspected and no solids were found as a desulfurization agent.

Fig. 22 shows an example in which an aeration system is used to deliver flue gas to the bottom of the desulfurization column stack 4.

Example 15

In the examples shown in FIGS. 23 and 24, the flue gas from the boiler 1 flows through the flue gas duct 6 and is cooled in the air preheater 3 and injected into the desulfurization column 4 through the flue gas duct 11. The desulfurizing agent, which is slaked lime, is sprayed from the nozzle 11 into the flue gas duct 13 through the introduction pipe for the desulfurizing agent 10. The desulfurizing agent is carried to the desulfurization column 4 through the flue gas duct 13. In the desulfurization column water is sprayed from the nozzles 12 flue gas.

At the same time, the thermocouple 57 measures the temperature at the point 55 directly impacted by the water droplets. The signal from thermocouple 57 is sent to the detector 58 and to an electronic data processing device in which the amount of water sprayed is calculated. This amount is controlled by the control valve 60 so that the temperature at the outlet of the desulfurization column 4 may be higher than this detected temperature.

The flue gas discharged from the desulfurization column 4 is injected into the dust separator 8. Inside the desulfurization column 4, the desulfurization agent reacts with harmful acid gases such as SO ₂ and the reacted desulfurization agent with ash is collected by the dust separator 8 and removed. Flue gases are discharged through chimney 7.

The desulfurization test is carried out on this apparatus. Coal A is burned (the SO ₂ concentration in the flue gas is 0.2%). The desulfurizing agent used is slaked lime in a Ca / S = 2 molar ratio. The temperature at the outlet of the desulfurization column 4 is controlled to be 10 ° C higher than the temperature at 55 detected by thermocouple 57 and the amount of water sprayed through the nozzles 2 was controlled by a signal from this thermocouple.

-17GB 290636 B6

After removing water from the gases at the outlet of the boiler 1 and at the outlet of the separator 8, the corresponding SO2 concentrations were 0.2 and 0.04%, respectively. Thus, 80% of SO2 in the flue gas was removed.

After 100 hours of continuous operation, the interior of the desulfurization column 4 was inspected and no solids were found as desulfurization agent.

Example 16

The desulfurization efficiency was measured on the same apparatus and under the same conditions as in Example 15. However, the gas temperature at the outlet of the desulfurization column was controlled to be 5 ° C higher than the temperature at 55 detected by the thermocouple 57 while the water sprayed through the nozzles 12 was adjusted according to the signal from the thermocouple 57.

After removing the water from the gases at the outlet of the boiler 1 and at the outlet of the separator 8, the corresponding SO ₂ concentrations were 0.2 and 0.02%, respectively. Thus, 90% of the SO ₂ in the flue gas was removed.

As in Example 15, after 100 hours of continuous operation, the interior of the desulfurization column 4 was inspected and no solids were found as desulfurizing agent.

Comparative example

The same equipment as in Comparative Example 1 was used and the desulfurization test was carried out for coal A under the same conditions as in Example 15.

As in Example 15, after 100 hours of continuous operation, the interior of the desulfurization column 4 and the interior of the dust separator were inspected, and 2 kg of solids such as desulfurizing agent (about 1% of the desulfurizing agent used in the experiment) were found. In addition, corrosion of the nozzle tube surface in the desulfurization column was observed.

Comparative example 6

Using the same conventional apparatus as in Comparative Example 1, a desulfurization test for coal A was performed under the same conditions as in Example 16.

As in Example 16, after 100 hours of continuous operation, the interior of the desulfurization column 4 and the interior of the dust separator were inspected and 10 kg of solids such as desulfurizing agent (about 5% of the desulfurizing agent used in the experiment) were found. In addition, corrosion of the nozzle tube surface in the desulfurization column was observed.

The thermocouple 57 can be placed anywhere if droplets of water spray directly onto it, and in the arrangement of the present invention, the thermocouple can be positioned above the nozzles.

In order to prevent desulfurizing agent deposits on the internal walls of the desulfurization column using a conventional method, it is necessary that the temperature at the outlet of the desulfurization column be about 10 to 20 ° C higher than the saturation temperature. However, the arrangement of the present invention allows a stable operation even when the temperature is only 5 ° C higher than the adiabetic saturation temperature. Thus, high desulfurization efficiency can be achieved.

-18GB 290636 B6

Example 17

Fig. 25 shows an example of a desulfurizing agent preparation apparatus. The limestone is heated in an oven to form quicklime. Then, in the mixer, quicklime is mixed with coal ash. This mixture of quicklime and coal ash is supplied from the mixer to the hydration apparatus; wherein quicklime and coal ash react together to form a desulfurizing agent with a high specific surface area.

To create the burnt lime, limestone desulfurization agent in the preparation device shown in Fig. 25 stripped of CO ₂ in the furnace. Any type of kiln can be used as long as it can decompose the limestone. If the desulfurizing agent particles obtained from the hydration apparatus agglomerate, it is possible to use a dusting apparatus to disperse them again.

Desulphurization efficiency of equipment; in which the desulfurizing agent prepared in this manner was fed to the flue gas in flue gas line 13 (FIG. 1) was tested for coal A. The amount of limestone corresponded to the molar ratio Ca / S = 2. The coal ash was supplied in an amount corresponding to 60% quicklime (quicklime: ash = 5: 3). The amount of water was three times the molar amount of quicklime. The mean residence time of the particles in the hydrator was 1 hour. The other conditions were the same as in Example 1.

The SO ₂ concentration was measured in the gas from which water vapor was removed. At the outlet of boiler 1 this concentration was 0.2% and at the outlet of the dust separator 8, 0.02%. Thus, 90% of the SO ₂ contained in the flue gas was removed.

Example 18

The desulfurization efficiency was tested using the same apparatus and conditions as in Example 17. However, the amount of quicklime used, i.e. the Ca / S ratio, was varied. The ratio of quicklime to coal ash was the same as in Example 17. The results are shown in Figure 26. The higher the Ca / S ratio, the higher the desulfurization efficiency. With a Ca / S ratio of 1, the desulfurization efficiency is greater than 75%.

Example 19

The desulfurization efficiency was tested using the same apparatus and under the same conditions as in Example 17. However, sodium silicate was added to the water that was sprayed into the hydration apparatus in which the desulfurizing agent was prepared. Figure 27 shows the dependence of desulfurization efficiency on the amount of sodium silicate added (in weight percent based on quicklime). 0% of the added sodium silicate corresponds to the addition of water at a molar ratio of 3.5 to the amount of quicklime. An increase in desulphurization efficiency is already apparent with added amounts of 0.01%. When 10 to 20% is added, the desulfurization efficiency is maximized. In view of economical desulfurization, it has been found in tests with other types of coal that the amount of sodium silicate, based on the amount of quicklime, should be in the range of 5 to 20% by weight.

Example 20

Using the same equipment as in Example 17, the desulfurization efficiency is tested under the same conditions as in Example 17. However, sodium hydroxide was added to the water which was injected into the hydration apparatus in which the desulfurization agent was prepared. Figure 27 shows the dependence of desulfurization efficiency on the amount of sodium hydroxide added (in percent by weight based on quicklime). An increase in desulfurization efficiency is already apparent with the added amount

-19GB 290636 B6 corresponding to 0.01%. When 10 to 20% is added, the desulfurization efficiency is maximized. In terms of economical desulfurization, it has been found in tests with other types of coal that the amount of sodium hydroxide relative to the amount of quicklime should be in the range of 5 to 20 wt%.

Example 21

In Example 17, the temperature of the hydration process in the preparation of the desulfurizing agent is not controlled. By introducing temperature control, the desulfurizing agent quality can be improved. Giant. 29 shows such an example: The hydration apparatus is equipped with steam heating and water cooling. The desulfurization test is performed under the same conditions as in Example 17, but the desulfurizing agent prepared according to this example is used. The dependence of the desulfurization efficiency on the temperature inside the desulfurizing agent preparation apparatus is shown in Figure 30. It is preferred that the temperature inside the desulfurizing agent preparation apparatus is in the range of 80 to 130 ° C. The desulfurization efficiency is reduced if the temperature is outside this range.

In the same apparatus as in Example 17, a desulfurization test was performed under the same conditions as in Example 1, using five types of coal with different sulfur contents. The results are shown in Table 5.

Table 5

Type of coal H AND J TO L Sulfur content (%) 0.3 0.3 0.8 1.0 3.0 Desulphurization efficiency (%) 94 94 90 92 88

Example 23

In the same apparatus as in Example 1 and under the same conditions as in this Example, a desulfurization test was carried out using magnesium carbonate (MgCO ₃ ) and magnesium-calcium carbonate (CaCO _3. MgCO ₃ ). The results are shown in Tab. 6.

Table 6

Desulphurising agent MgCO ₃ CaCO ₃ .MgCO ₃ Desulphurization efficiency (%) 86 89

Example 24

Fig. 31 shows an example of a desulfurizing agent preparation apparatus. The limestone is heated in a heating furnace to form quicklime. The quicklime is supplied to the mixer: In the mixer, an aqueous sodium silicate solution is added to the quicklime, and the quicklime reacts with sodium silicate in an aqueous sodium silicate solution. The mixture is further stirred for a period of time to form a desulfurizing agent having a high specific surface area.

In the desulfurizing agent preparation apparatus shown in FIG. 31, the limestone is free of carbon dioxide in the furnace. Any type of furnace can be used as long as it can de-carbonate the limestone. Any mixer may be used as long as it is suitable for mixing powders.

The desulfurizing agent thus prepared is injected into the flue gas in the flue gas duct 13 of the boiler 1, see FIG. 1. With this desulfurizing agent, the desulfurization efficiency was tested using coal M (content of

Sulfur lime is supplied to the furnace in an amount corresponding to a molar ratio of Ca / S = 1.5. Sodium silicate (water glass) is added to the mixer in an amount corresponding to 5% by weight, based on quicklime. The amount of water supplied in the sodium silicate solution is 2.5 times (molar) higher than the quantity of quicklime. An amount corresponding to 3 wt. flue gas. This water is supplied via line 14. 50% of the particles trapped in the dust separator 8 are returned to the desulfurization column 4 through a tube 22 and the remainder is discharged. Unreacted desulfurizing agent contained in the particles trapped by the separator 8 is not included in the Ca / S value.

After removing water from the gases at the outlet of the boiler 1 and at the outlet of the separator 8, the corresponding SO ₂ concentrations were 0.154% and 0.018% respectively. Thus, 88% of SO _{2 was} removed from the flue gas.

Example 25

The desulfurization efficiency was measured on the same apparatus and under the same conditions as in Example 24, except that the amount of quicklime used was changed, i.e. the Ca / S ratio was changed. The results are shown in Fig. 32. The desulfurization efficiency is generally higher than that measured in the comparative examples described later. The higher the Ca / S, the higher the desulfurization efficiency. Desulfurization efficiency of more than 70% was achieved even at a Ca / S ratio of 1.0.

Example 26

The desulfurization efficiency was measured on the same apparatus and under the same conditions as in Example 24, except that the amount of sodium silicate used in the preparation of the desulfurizing agent was varied. Figure 23 shows the dependence of desulfurization efficiency on the amount of sodium silicate used. The value of 0% sodium silicate added corresponds to the addition of water in a molar amount of 2.5 to the amount of quicklime. An increase in desulphurization efficiency is already apparent with added amounts of 0.01%. At 10 to 20% the desulfurization efficiency is maximum. If the amount of sodium silicate is greater than 50%, the desulfurization efficiency is equal to or less than that of a silicate-free reagent. In terms of economical desulfurization, it has been found in tests with other types of coal that the amount of sodium silicate should be in the range of 1 to 20 wt.

Although the reason for reducing the desulfurization efficiency when using a higher amount of sodium silicate is not entirely clear, it can be assumed that the already formed pores are closed with an excess of sodium silicate. Figure 34 shows the dependence of the specific surface area measured by the N ₂ BET method on the amount of sodium silicate. It appears that the specific surface area initially formed decreases.

Example 27

The desulfurization activity was measured on the same apparatus and under the same conditions as in Example 24, except that the limestone was first de-carbonated and then cooled and the temperature of the quick lime for delivery to the mixer was varied after addition of aqueous calcium silicate solution to quick lime. Giant. 35 shows the dependence of desulfurization efficiency on the temperature of quicklime when adding an aqueous calcium silicate solution. If the calcined lime temperature is less than 100 ° C, the desulfurization efficiency tends to decrease somewhat. Preferably, the sodium silicate solution to be added is at least 100 ° C.

-21 GB 290636 B6

Example 28

The desulfurization efficiency was measured on the same apparatus and under the same conditions as in Example 24 using five types of coal having different sulfur contents. The results are shown in Table 7.

Table 7

Type of coal H AND J TO L Sulfur content (%) 0.3 0.3 0.8 1.0 3.0 Desulphurization efficiency (%) 90 91 87 90 84

Example 29

The desulfurization efficiency was measured on the same apparatus and under the same conditions as in Example 24, using magnesium carbonate (MgCO ₃ ) and magnesium-calcium carbonate (CaCO _3. MgCO ₃ ). The results are shown in Table 8.

Table 8

Desulphurising agent MgCO ₃ CaCO ₃ .MgCO ₃ Desulphurization efficiency (%) 82 85

Comparative example 7

In the same apparatus as in Comparative Example 1 and under the same conditions as described in Example 24, the desulphurization efficiency for coal M was measured. the efficiency recorded in the processes of the present invention is lower.

Comparative example 8

Following the same procedure as in Comparative Example 7 (but at a Ca / S ratio of 1.5), the desulfurization efficiency was measured in experiments with five types of coal as shown in Example 28. The results are shown in Table 9. Compared to the procedures of of the present invention, the desulfurization efficiency is lower for all types of coal.

Table 9

Type of coal H AND J TO L Sulfur content (%) 0.3 0.3 0.8 1.0 3.0 Desulphurization efficiency (%) 32 39 36 30 30

Comparative example 9

In the same apparatus as in Comparative Example 1 and under the same conditions as in Example 28, the desulfurization efficiency for coal M was measured. The results are shown in Table 10.

-22GB 290636 B6

A comparison with the desulfurization efficiency of the processes of the present invention shows that the desulfurization efficiency found is lower.

Table 10

Desulphurising agent MgCO3 CaCO ₃ .MgCO ₃ Desulphurization efficiency 30 32

In contrast to the above examples 17 to 19, where calcined lime is obtained by heating limestone, it is also possible to use calcined lime obtained by heating the slaked lime. In addition, any suitable clay material may be used as long as caustic earth metal oxide is formed upon heating or the like.

Example 30

The desulfurizing agent obtained by heating the slurry obtained by mixing ash from slaked lime was used. This slurry is then sprayed into the flue gas in the flue gas duct and the flue gas produced by the combustion of coal in the boiler is desulfurized.

As shown in Fig. 36, the flue gas from the boiler 1 is cooled in an air heater 3 and fed to a desulfurization column 4. Slaked lime, ash ash, desulfurizing agent particles obtained in the separator 8, water and sodium silicate are injected into the preparation plant. desulfurizing agent 37 and mixed in a mixer. Any mixer capable of processing the mixture may be used. This mixture is a desulfurization slurry having a high specific surface area and injected into the flue gas duct 13 or desulfurization column 4 to react with harmful acidic substances such as SO ₂ . At the same time, water can be injected into the flue gas duct 13 or the desulfurization column 4 to cool the flue gas and increase its humidity. The desulfurizing agent that has partially reacted is trapped together with the ash in the flue gas in the dust separator 8 and a part is supplied to the desulfurizing agent manufacturing apparatus 37. The remaining desulfurizing agent and coal ash are discharged. Inside the desulfurizing agent preparation there are slaked lime, coal ash, water and sodium silicate. Using this apparatus, the desulfurization efficiency of coal M was measured. An amount of slaked lime was used such that the Ca / S ratio was 1.5. Sodium silicate (water glass) was supplied in an amount of 5% by weight, based on the amount of solids in the desulfurizing agent preparation apparatus 37. Water was sprayed in the desulfurization column in an amount corresponding to 3% by weight. flue gas. The desulphurizing agent prepared was supplied to the flue gas duct 13 via line 22. In the desulphurizing agent preparation, the slurry is treated with water to contain 30 wt. of reagent and is heated to 100 ° C. The mean residence time of the particle in this device is 2 hours. The shear rate achieved in the desulfurizing agent preparation apparatus 37 is 10 s ^-1 . 50% of the particles trapped in the particle separator 8 are returned to the desulfurizing agent preparation apparatus 37; the rest is drained. Unreacted desulfurizing agent contained in the particles trapped by the dust separator 8 is not included in the Ca / S ratio.

The SO ₂ concentration was measured in the gas samples from which water vapor was removed, at the boiler outlet 1, 0.154%, and at the dust separator outlet 8, 0.015%. Thus, 90% of the SO ₂ contained in the flue gas was removed. The specific surface area of the desulfurizing agent prior to the desulfurization reaction is 65 m ² / g. The fact that the specific surface of slaked lime and coal ash is more than 10 m ² / g suggests that the described process of maturation of the desulfurizing agent increases its specific surface area.

-23GB 290636 B6

Example 31

The desulfurization efficiency was measured in the same apparatus as in Example 30 and under the same conditions as in the Example 31. However, the amount of slaked lime used (and thus the Ca / S ratio) was varied. The results are expressed in curve a in Figure 37. The higher the Ca / S ratio, the higher the desulfurization achieved. Desulfurization efficiency of at least 75% was achieved even with a Ca / S = 1 ratio. 37 shows the desulfurization efficiency achieved when only coal and water ash were mixed in the desulfurizing agent preparation apparatus (without the use of sodium silicate see curve b).

The desulfurization efficiency was measured in the same apparatus as in Example 30 and under the same conditions as in the experiment of Example 30. However, the mean residence time was changed by changing the hold in the desulfurizing agent preparation apparatus 37. The dependence of desulfurization efficiency on the mean residence time is shown in FIG. A sufficiently high desulfurization efficiency can be achieved even if the mean residence time is short. Giant. 38 also shows the desulfurization efficiency values when the desulfurizing agent is prepared from coal and water ash which are mixed without the addition of sodium silicate (b).

Example 32

The desulfurization efficiency was measured in the same apparatus as in Example 30 and under the same conditions as in the Example 30. However, the amount of sodium silicate added (relative to the solid particles) was varied. The results are shown in FIG. 39. The desulfurization efficiency increase is already apparent with the addition of 0.1% solids. In the case of coal M at a higher addition than 10 wt. desulfurization efficiency no longer increases. Thus, from an economic point of view, it is suitable to add 0.1 to 10 wt. Similar investigations were carried out in experiments with coal types that differed in sulfur content. It has been found that the preferred amount of sodium silicate added is 0.1 to 30% by weight based on the total weight of the solid particles.

Example 33

The desulfurization efficiency was measured in the same apparatus as in Example 30 and under the same conditions as in the Example 30. However, the rotational speed of the mixer stirrer in the desulfurizing agent preparation 37 was varied and the dependence of the desulfurization efficiency on the shear rate was determined. The results are shown in Figure 40. At high shear rate, slurry dispersion is good and therefore desulfurization efficiency increases. In terms of desulphurisation efficiency, good mixing should be ensured at shear rates of at least 10 s ^-1 .

Example 34

The desulfurization efficiency was measured in the same apparatus as in Example 30 and under the same conditions as in the Example 30 experiment using five types of coal having different sulfur contents. The results are shown in Table 11.

Table 11

Type of coal H AND J TO L Type of coal 0.3 0.3 0.8 1.0 3.0 Desulphurization efficiency (%) 94 95 93 92 88

-24GB 290636 B6

Example 35

Using the apparatus depicted in FIG. 41, the desulfurization efficiency was measured in coal trials. In this example, the added sodium silicate is mixed with water in the viscosity modifying container 38, and then the mixture is fed to the desulfurizing agent preparation apparatus 37. The viscosity of an aqueous sodium silicate solution is strongly dependent on its concentration. When the high viscosity aqueous solution is supplied to the desulfurizing agent preparation 37, sodium silicate cannot readily dissolve in the slurry. Therefore, the silicate concentration is locally increased and, as a result, the slaked or quicklime particles agglomerate and hence the desulfurizing agent having a high specific surface area cannot be prepared. To prevent this, the sodium silicate is diluted with water in the reservoir 38 so that the viscosity of the solution does not exceed 10 Pa.s. It has been found that the above-described problem can be solved by adding the sodium silicate solution thus treated to the desulfurizing agent preparation apparatus 37.

Giant. 42 shows the dependence of desulfurization efficiency on the viscosity of the sodium silicate solution (adjusted by changing the dilution ratio in the viscosity treatment container 38. Desulfurization conditions are the same as in Example 30). When the viscosity exceeds 10 Pa.s, the specific surface area of the desulfurizing agent gradually increases. Therefore, the viscosity of the sodium silicate solution should not exceed 10 Pa.s.

Example 36

The desulfurization efficiency was measured on the apparatus shown in Fig. 43 using coal Μ. In this example, a wet grinding mill 39 is used at the inlet of the desulfurizing agent preparation 37 and slaked lime, water and sodium silicate are treated in the presence of coal ash. The ground slurry is supplied from the mill 39 to the desulfurizing agent preparation apparatus 37 and heated during grinding to prepare a high specific surface desulfurizing agent. Grinding of slaked lime and ash from coal increases their reactivity so that a desulfurizing agent having a high SO2 absorption capacity can be prepared. Under the same conditions as in Example 30, the desulfurization efficiency of the coal experiments is measured. Table 12 shows the desulphurisation efficiency with and without the addition of sodium silicate and in the case of the addition of ground or unground sodium silicate.

Table 12

no sodium silicate 5% sodium silicate without grinding 35 90 with grinding 58 96

The heating jacket of the mill 39 causes the maturation to take place simultaneously with the grinding in the mill 39 and the desulfurizing agent preparation device 37 can be omitted.

Although in the previous cases the desulfurizing agent is sprayed as a slurry into the flue gas duct 13 or desulfurization column 4, the slurry leaving the desulfurizing agent preparation 37 can be dried to a powder and subsequently sprayed into the flue gas duct or desulfurization column 4.

Example 37

In the example shown in Figure 44, the slaked lime, coal ash, water, and sodium silicate are mixed in the mixer 33, instead of heating the desulfurizing agent slurry in the desulfurizing agent preparation 37 as described in Examples 30-37.

The slurry obtained is sprayed into the furnace of the boiler 1 or into the flue gas duct 13. In this way the same maturing effect can be achieved, but in a shorter time. The mixer 33 only mixes the pulverulent substances and the mixer may be smaller than the desulfurizing agent 37, e.g. a pipeline mixer. Giant. 45 illustrates the temperature dependence of the desulfurization efficiency when the desulfurizing agent prepared under the same conditions as in Example 30 (except for heating) is dispersed into the boiler or flue. In terms of desulfurization efficiency, this temperature should be in the range 300-1000 Deň: 32 ° C. At temperatures above 1000 ° C, the desulfurizing agent particles sintered, and at temperatures below 300 ° C, there is no reaction between slaked lime and coal ash. If the operating conditions are outside this range, the desulfurization efficiency can be expected to be reduced for these reasons.

Comparative example 10

Following the same procedure as in Comparative Example 1 (but at a Ca / S ratio of 1.5), it was in the experiments with the five types of coal shown in Example 34; the desulfurization efficiency measured. The results are shown in Table 13. Compared to the examples according to the invention, the desulfurization efficiency in the comparative examples is in all cases lower.

Table 13

Type of coal H AND J TO L Sulfur content (%) 0.3 0.3 0.8 1.0 3.0 Desulphurization efficiency (%) 40 47 44 39 32

In the above Examples 30-37, slaked lime was used as a caustic earth metal compound and coal ash as a silica, but limestone, calcium sulfite and calcium sulfate and coal ash could be used as the caustic earth metal compounds; quartz sand, bentonite or kaolin. It is also possible to use two or more substances in combination. Although waterglass (JIS No. 1) has also been used, other types of sodium silicate can also be used.

Although slaked lime, quicklime, magnesium carbonate or magnesium calcium carbonate have been used as desulfurizing agents in the above examples, an alkali metal or caustic earth metal oxide, hydroxide or carbonate such as sodium hydroxide or sodium carbonate can be used.

Claims (10)

A method of dry desulphurization of fossil flue gas, wherein a desulphurizing agent is added to the flue gas and the solid particles of the reacted desulphurizing agent and fly ash are separated from the desulphurized flue gas, characterized in that Water is scattered in a swirling manner and the solid particles of the reacted desulfurizing agent are separated from the flue gas together with the fly ash. Method for dry desulfurization of gaseous flue gases according to claim 1, characterized in that water is dispersed into the flue gas by means of a scattering gas, which is air or water vapor. -26GB 290636 B6 Process for dry flue gas desulphurisation according to claims 1 and 2, characterized in that the flue gas is cooled to less than 200 ° C by heat exchange prior to desulphurisation. A process for dry desulfurization of gaseous flue gases according to claims 1 to 3, characterized in that the desulfurizing agent is added to the flue gas stream at temperatures up to 200 ° C. 5. The method of dry desulfurization of gaseous flue gases according to claims 1 to 4, characterized in that the water is dispersed in the flue gas stream in an amount of 0.02 to 0.05 liters per m ^{3 of} flue gas. 6. A process for dry desulfurization of gaseous flue gases according to claims 1 to 5, characterized in that the water is dispersed into the flue gas stream at an angle of 40 to 180 [deg.] Relative to the flue gas stream. 7. The method for dry desulfurization of gaseous flue gases according to claims 1 to 6, characterized in that water is dispersed into the flue gas stream to form a moisture gradient in a plane perpendicular to the direction of the flue gas stream, to the perimeter of the flue gas stream. 8. The method of dry flue gas desulphurisation according to claims 1-7, characterized in that a portion of the flue gas or heated air, both at least 5 [deg.] C. higher than above), is fed to the flue gas stream after addition of the desulfurizing agent. than the flue gas temperature. A method for dry flue gas desulphurisation according to claims 1 to 8, characterized in that the separated solids of the reacted desulfurizing agent together with the fly ash after separation from the flue gas stream are fed to the flue gas stream in a temperature range of 500 to 900 ° C. reagents. 10. The method of dry desulfurization of gaseous flue gases according to claims 1 to 9, characterized in that water is added to the separated solid particles of the reacted desulfurizing agent and fly ash and the resulting slurry is fed to the flue gas stream in a temperature range of 500 to 900 ° C. Process for dry desulfurization of gaseous flue gases according to claims 1 to 10, characterized in that the resulting slurry is dried and the resulting powder is sprayed into the flue gas stream in a temperature range of 500 to 900 ° C. 12. Apparatus for the dry desulphurisation of fossil fuel gases, consisting of a desulphurisation column, into the bottom of which a flue gas duct extending from a fossil fuel furnace, a desulphurisation agent reservoir and a flue-gas desulfurizer separator and fly ash connected to the flue-gas desulfurization column; The apparatus according to claim 1, characterized in that an apparatus (21) is disposed in the lower part of the desulfurization column (4), by means of which the water is vortexed into a flue gas stream composed of a water supply (14), a scattering gas supply (15), scattered nozzles (12) and dispersing means (16) situated therein for generating water swirls with scattering gas in the flue gas desulphurized stream. 13. A flue gas desulphurisation device according to claim 12, characterized in that a flue gas duct (6) extending from the fossil fuel furnace (1) and a flue gas duct (13) leading to the bottom of the desulfurization column (4) is provided. the heat exchanger (3), and the outlet (10) from the desulfurizing agent reservoir (5) is led to the flue gas duct (13). 14. The flue gas desulfurization plant according to claims 12 and 13, characterized in that the angle of the axes of the scattering nozzles (12) with respect to the flow direction of the flue gas is 40 to 180 [deg.]. -27GB 290636 B6 15. The flue gas dry desulfurization plant according to claim 12, wherein the dispersion nozzles are located at a distance of 1 to 5 m from the flue gas inlet of the desulfurization column (4). 16. The flue gas desulfurization plant according to claim 12, characterized in that the vortex water scattering apparatus (21) is composed of two groups of scattering nozzles (12) mounted in opposite parts of the desulfurization column (4). ). 17. Apparatus for dry desulfurization of gaseous flue gases according to claims 12 to 16, characterized in that it is equipped with an inlet (22) of a portion of the hot flue gas or of heated air connected to the flue gas outlet (13) to the desulfurization plant. column (4).