JPS61133122A - Method and device for neutralizing and separating injurious material in flue gas and exhaust gas - Google Patents

Abstract

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

Description

[Detailed Description of the Invention] A method for neutralizing and separating hazardous substances containing acids, especially hazardous substances containing sulfur, from flue gas and exhaust gas in furnace equipment, comprising: , refined lime (new lime that has not been used) and/or old lime in the flue gas reactor (6
; 18) and flue gas - a method for supplying gas in a pipeline and an apparatus for carrying out this method.

Wet and dry gas cleaning methods are known for neutralizing acid-containing toxic substances, especially sulfur dioxide, in flue gases and exhaust gases from furnace equipment. British Patent No. 1,380,869 discloses the combination of sulfur dioxide and sulfides from the flue gas of a glass melting furnace in a wet process.

Caustic soda solution or sodium carbonate is sprayed as a neutralizing medium into the area of contact with the exhaust gas stream. Parallel bodies additionally placed in the contact zone cause the particles to break up during the absorption phenomenon, forming new surfaces on which to react with the remaining harmful substances. The sodium sulfate produced during this neutralization process is recycled in glass production. Since the flue gas is relatively hot,
Uni-7 cleaning is used in which a neutralizing agent is added for cooling.

In the case of the known wet processes for the separation of sulfur dioxide, the production of large amounts of gypsum as the final product means that the commercial gypsum sales market is only available in very limited quantities. , resulting in a disadvantage. Using the known dry cleaning methods, large gypsum formations of this type can be avoided in exhaust gas treatment. In the known dry cleaning process, a neutralizing agent, for example an aqueous lime suspension, is continuously sprayed into the flue gas using a pump-driven fluid atomizer. As a result, the pollutants are converted into neutral salts as the carrier fluid carried in with the suspension dries at the same time, and these neutral salts are removed from the flue gas together with the airborne dust in the dust separator.

Furthermore, dry processes are also known in which the cooled and conditioned exhaust gas, ie sufficiently pretreated of harmful substances for the reaction, is sent to a Venturi reactor and accelerated there. In a section designed as a diffuser, the exhaust gas in the Venturi reactor is fed fresh with refined lime and a dust-old lime mixture separated by a subsequent cloth filter. In this case, it is unavoidable to interrupt the operation of the reactor after a relatively short operating time. The reason for this is that in order to reduce the operating costs of desulfurization equipment, old lime separated by a cloth filter can be effectively recirculated or reused until it is completely saturated.

The object of the present invention is to configure the neutralization of harmful substances in flue gases, in particular sulfur dioxide, using lime as an adsorbent without causing any problems, especially in the case of recycled and new processes. The purpose is to not cause any problems in re-feeding old lime grains that are supplied to the plant, and to keep equipment costs as low as possible.

According to the invention, this object is achieved in that the agglomerated lime grains are pulverized in front of the injection nozzle in the flue gas reactor. Here, one factor is the knowledge that refined lime (new, unused lime) tends to clump in storage silos, resulting in lime grains that are too large for good binding with harmful substances. is the starting point. On the other hand, when old lime or refined lime is used, the spherical old lime grains that were previously filtered and returned to a new cleaning process are surrounded by a thin layer of sulfur, and this sulfur layer does not contain the required harmful substances. Not only does it prevent the binding of substances, but it also increases the particle size with the amount of lime, which leads to very rapid deposits of undesirable size, which cannot be used for the purpose of neutralization of harmful substances, i.e. Make equipment inoperable.

This negative effect is eliminated by the present invention in a very simple way, i.e. by crushing the thin SO□-enveloping layer, the lime content of the old lime itself, and the lumpy refined lime grains which are not combined with harmful substances at that time. It was done.

With aged lime used in a ratio of 8:1 to 12:1, ie with a small amount of refined lime, sulfur dioxide is quickly and completely removed. The ideal mixing ratio of old lime and refined lime is 1:10.

Preferably, the aged lime particles and refined lime particles, which are mixed and agglomerated during the agglomeration with the flue gas in the first stage, are finely pulverized in front of the injection nozzle in the second reactor. Effects can be obtained. For this purpose, a second reactor is connected downstream of the flue gas reactor, and here also initially lime from old lime or purified lime with harmful substances in the first reaction process.
The agglomerate produced from the adsorbent is pulverized and then fed to a second reactor.

Advantageously, mixing lime particles with water during comminution helps to simplify the neutralization process; a good humidity of the lime ensures that a given amount of water is absorbed by the circulating lime, i.e. old lime. and/or about 10-15% of the total amount of refined lime. In the case of a suitable mixing ratio where the ratio of old lime to refined lime is l0 = 1, 200 kg of old lime and 20 kg of refined lime are used.
Approximately 22 to 33 I2 of water are required for a kg of circulating lime.

It is thus clear that flue gases at temperatures below about 160° C. can be cooled to about 100° C., the temperature for entering the filter, simply by supplying this required amount of water directly to the mill itself. This water was regenerated in the mill, i.e.
By providing sufficient moisture to the pulverized refined lime and aged lime, when spraying the refined/aged lime mixture into the flue gas reactor, it is possible to not only lower the temperature of the flue gas flowing through the reactor. (In this case, the lime does not dry out completely when the temperature drops, but maintains sufficient humidity, thereby preserving the necessary binding capacity of the lime for harmful substances.) This allows gas cooling, which increases equipment costs up to high temperature ranges. It can be done without any equipment.

Spherical old lime, old lime particles mixed with each other, and refined lime particles are crushed or crushed by a crusher or crusher installed in the old lime supply means and a pipe connecting two reactors to each other. This is done using a second crusher/grinder connected thereto. The crusher arranged in the first reactor is preferably connected upstream of the supply means for the aged lime, which is configured as a scree conveyor. The crusher is equipped with a plurality of hammer blades that are disposed on a shaft inside the crusher housing. During the rotation of the shaft, the blades, which are also free-suspended below, are erected, pulverizing the supplied lime and forcing the pulverized lime into the reactor which is then connected. The pulverization of the old lime grains and refined lime grains takes place before their introduction into the first reactor, and the refined lime line opens into the suction pipe of the crusher, which is connected to the supply means for the old lime. .

The crusher is preferably disposed directly in the reactor, and its outlet side can be opened into the inside of the reactor. The pulverizer dumps the pulverized components directly into the reactor interior, where the pulverizer is positioned in the reactor so that the adsorbent can be dumped at an angle of approximately 90″ to the reactor cross section. The crusher fulfills the task of pulverizing the adsorbent and
It also contributes to its uniform distribution in the reactor, ie good mixing with the flue gas. For effective adsorption, homogeneous mixing of gas and adsorbent is of no small importance, as is sufficient fineness, ie, a sufficient amount of reaction surface.

The water channel can enter the center of the crusher on the inlet side near the feed channel for refined (fresh) lime and/or old lime. Furthermore, it is also possible to arrange the disc just below the water channel. The water is then fed into the center of the crusher, ie to the rotary shaft with the blades of the fine means designed as a crusher or crusher, so that a particularly effective mixing with the lime is achieved. For this purpose, it is possible to install a disk, for example made of copper, which is arranged about 3 degrees below the outlet end of the channel and which scatters and distributes the exiting water stream.

A regulator connected to the water channel supplies water periodically, for example under computer control.

It is emphasized that the required amount of water should be supplied in about 15 minutes. The binding of harmful substances is effectively achieved while the humidity of the circulating lime is 60-65% of the final humidity. The starting point is that the humidity begins to decrease after about 10 minutes and reaches the computer-determinable limit value in the next 5 minutes, ie in a total of 15 minutes.

The diffuser part, i.e. the venturi chamber with an upwardly flaring flue gas channel, which is integrated as a reactor, creates a negative pressure in the feed area of old lime and refined lime, which area is exposed to the inflow caused by this negative pressure. The injection action ensures distribution of lime components. The gas flows through the reactor from bottom to top, creating a vortex bed with negative acceleration in a portion of the diffuser, in which agglomeration of the adsorbent loaded with harmful substances with the hot carrier gas takes place. This process and the resulting accelerated reaction are additionally supported through Brownian motion in reactors with flow from the bottom up. The residence times of the flue gas and adsorbent are not the same due to the force of gravity acting on the dust particles. Here, the particle velocity can be subtracted from the gas velocity, resulting in a sufficiently long residence time in the reactor. On the other hand, in a falling flow reactor, for example, the gas velocity and the particle velocity are added, and the residence time in the reactor is extremely short.

The temperature of the flue gas or exhaust gas is lowered in a gas cooler connected upstream of the reactor. Water is therefore sprayed into the gas cooler using compressed air. Water/water placed in the gas cooler in the direction of gas flow
In the case of air nozzles, the residence time of the splashed water in the gas cooler is increased. This allows the water to dry further on its way to the cooler floor and contributes to constant humidity.

Nevertheless, the moisture that reaches the floor of the cooler is captured by the diagonally extending floor of the cooler, collects at the lowest point, and is discharged.

Due to the use of lime as an adsorbent, the final product produced after the cleaning process still contains large gypsum components, so this waste can be used as a plastic material for the production of lime-sandstone or as a material for plastering. used. For this purpose, a predetermined amount of cement or sand must be added to this waste material depending on the purpose of use.

The invention will now be explained in detail with reference to embodiments shown as flowcharts.

According to FIG. 1, hot flue gases and exhaust gases coming from a furnace installation (not shown) enter tangentially via a line 1 into the upper region of an evaporative cooler 2, in which a subsequent filter 3 is installed. Cooled to entry temperature. Because the gas is supplied tangentially, it swirls in the cooler 2, which aids its mixing with the cooling medium and, if necessary, removes any condensation droplets that may form. For cooling, water is sprayed in a fine droplet spectrum above the cooler 2 using water/air nozzles 4. For example, four of these nozzles 4 are arranged above, ie, opposite the gas flow, in the annulus connected to the water channel and the air channel, and in the center of the cooler 2. By spraying with this nozzle, complete evaporation of the cooling water is achieved in an extended path from immediately above and finally from top to bottom, ie in the same direction as the gas flow.

In the cooler, the necessary conditioning, i.e. the preparation of the harmful substances for reaction, is facilitated and any residual alcohol still present in the exhaust gas stream is extinguished. The fine droplet spectrum and temperature-dependent actuation of the nozzle 4 further ensures a dry cooler floor surface and avoids scorching and sludge accumulation.

In the case of the slanted floor 5 of the cooler 2, fluid that has reached the floor is captured and collected at the deepest point. This point is located below the line 7 which runs from the cooler 2 to the subsequent flue gas reaction line 6. During the suction of flue gases and exhaust gases through the overall system by the furnace fan 8 following the filter 3, a suction effect takes place which drags the collected fluid along.

The cooled and conditioned exhaust gas is passed through the conduit 7 at the lower end of the cooler 2.
A two-draft furnace 8 led to a first flue gas-reactor 6 by
The velocity of the gas produced by is approximately 35 in the reactor 6
m/s. Due to this high speed, the injector action, which is assisted in lime application, is exerted on the refined lime and aged lime fed into the lower part of the reactor 6. Refined lime is removed from the lime silo 9 and fed via a suitable dosing device, such as a weighing scale 10 or a weighing hopper 11, to a motor-driven screw conveyor 13, from which it passes through a line 13 and is then fed to a motor-driven screw conveyor 13 for stale lime. to a suction pipe 15 of a crusher or crusher 16 which is connected to a screw conveyor 14 and which is arranged in the reactor 6 as close as possible to the gas stream. A horizontal supply line 17 opens into the reaction line from the outlet side, that is, the pressure side, of the crusher 16.
Old lime and/or refined lime, which has been previously pulverized in the crusher 16, is fed through this.

The particles agglomerated in the reactor 6, so-called especially old lime components, are recycled until they are completely saturated. For this purpose, the spherical old lime particles are fed into the process anew after separation of the dust-adsorbent mixture in the downstream filter 3. A motor-driven screw conveyor 14 is therefore placed in front of the reactor 6 under the filter 3, which consists of individual filter modules that are arranged freely in a filter unit for bulk gases, e.g. as a hose bag filter. It has been extended to The refined lime component, which is optionally calcined together with old lime grains, is crushed in a crusher or pulverizer 16 disposed below the screw conveyor 14 before being newly introduced into this process. It is then forced from the rotating crusher 16 via line 17 into the reactor where it is swept away by the flowing gas.

A second reactor 18 can be seen downstream of the first reactor 6 in order to optimize the separation capacity. The pipe line 19 connects the outlet side of the first reactor 6 and the inlet side of the second reactor 18. In order to prevent the particles agglomerated in the first reactor 6 from entering the subsequent reactor 18 with an undesirable particle size, a further crusher or crusher 20 is connected to the connecting line 19; The particles are atomized at the top of the nozzle of the reactor 18. After leaving the subsequent reactor 18, the particles loaded with dust and sulfur dioxide reach the separation filter 3 via the line 21.

Saturated, i.e. unrecyclable, deposited ash particles are filtered through filter 3.
A screw conveyor 22 arranged under the ash is conveyed to a collection silo 23 for the deposited ash mixture, from which it is taken off in batches and used for the production of lime sandstone or as plastering material. After the cleaned (desulfurized, etc.) gas passes through the filter 3, it reaches the chimney 25 via the pipe line 24.

The equipment shown in Figure 2 has several process differences compared to the equipment previously described. Firstly, the crusher or crusher 16 is provided with another water channel 26 with a regulator 27 . This waterway 26 enters the center of the inlet side of the crusher 16 along with the suction pipe 15 for supplying ash and the conduit 13 for supplying refined lime connected to this pipe 15. Disposed at a short distance from the outlet end of the water channel 26 is a disc 28 which splashes the water periodically supplied by the regulator 27 via the pipe 26 and distributes it within the crusher. . This water is mixed internally with finely ground lime, for example by means of a rotary shaft of a crusher (not shown) using implants or by a grinder of the crusher. The crusher 16 forces the pulverized, moistened lime mixture into the reactor 6 where it meets the flowing hot flue gases. The flue gas is then cooled, on the one hand, by the moist lime mixture in its passage from bottom to top, and on the other hand, pollutants are simultaneously neutralized. The crusher 20 of the subsequent reactor 18 is not provided with water channels. This is because the required moisture of the recycled or returned lime is maintained by the periodically supplied water in the crusher 16. However, it is also within the scope of the present invention to provide the second crusher or the second crusher 20 with a water channel.

It is not possible to mix an unlimited amount of water.

If the temperature of the flue gas does not exceed approximately 140 °C to 160 °C, water mixing is sufficient, since the installation can be operated without pre-cooling the gas, i.e. without gas cooling. is shown.

Another important measure is that at least the crusher or crusher of the reactor 6, into which the flue gas first flows, is arranged directly in the reactor, i.e. the crusher 16 has its outlet side or pressure side 29 connected to the reactor. 6 through the wall 30 and opened into the inside of the reactor. This mill 16 forces or accelerates the pulverized adsorbent to uniformly distribute it within the reactor and mix it homogeneously with the gas stream.

[Brief explanation of the drawing]

The drawings show embodiments of the present invention, FIG. 1 is a flowchart showing a first embodiment of equipment for the separation and neutralization of hazardous substances containing sulfur, and FIG. It is a flowchart which shows the 2nd implementation, Example of the installation for neutralization. 2...Cooler, 3...Filter, 6.
...First reactor, 9...Lime silo, 1
6... Pulverizer, 18... Second reactor,
25...Chimney.

Claims (1)

[Scope of Claims] [1] Acids in flue gas or exhaust gas in furnace equipment,
A method for the neutralization and separation of acid-containing harmful substances, especially sulfur-containing harmful substances, in which purified lime and/or old lime is added to the flue gas reactor (6; 18) or the flue. Gas - A method for supplying gas in a pipeline, characterized in that agglomerated lime particles are pulverized in front of an injection nozzle in a flue gas reactor. Methods for neutralization and separation. [2] The old lime grains and refined lime grains mixed and agglomerated during the agglomeration with the flue gas in the first stage are pulverized in front of the injection nozzle in the second reactor (18). The method according to claim [1]. [3] Refined lime and old lime are 1:8 to 1:12, especially 1:1
The method according to claim 1 or claim 2, characterized in that the ingredients are mixed at a ratio of: :10. [4] The method according to any one of claims [1] to [3], wherein the lime particles are mixed with water during pulverization. [5] Any one of claims [1] to [4], characterized in that the amount of water supplied is about 10 to 15% of the total amount of circulating lime. Method described. [6] Refined lime and/or aged lime in a flue gas reactor (
6; 18) and flue gas - gas in the pipeline, agglomerated lime particles are pulverized in front of the injection nozzle in the flue gas reactor, and the flue gas - reaction is carried out in the supply of old lime. A device for neutralizing and separating harmful substances, especially harmful substances containing sulfur, in which a crusher and a crusher (16) are arranged side by side in a furnace (6). [7] The device according to claim [6], characterized in that the screw conveyor (14) is connected in series to the crusher (16). [8] New lime pipe (13) is old lime supply pipe (14)
The device according to claim 6 or 7, characterized in that the device is open to a suction pipe of a crusher (16) connected to the pulverizer (16). [9] Claim No. 1, characterized in that the crusher (16) is disposed directly in the reactor (6) and opens into the reactor at the outlet side (29) of the reactor. 6
] to [8]. [10] The device according to any one of claims [8] to [9], characterized in that the waterway (26) communicates with the crusher (16). [11] The waterway (26) is connected to the crusher (16) on the inlet side near the supply channel (13, 15) for refined lime and/or old lime.
) The device according to claim 10, wherein the device is inserted into the center of the device. [12] Claim [10] or [11], characterized in that a disc (28) is disposed immediately below the water channel (26) in the crusher (16). The device described in. [13] Claims [11] to [1] characterized in that a regulator (27) is connected to the water channel (26).
12]. [14] Device according to claim [6], characterized in that the flue gas reactor (6) is followed by a second flue gas reactor (18). [15] Claim [6], characterized in that a second crusher or crusher (20) is connected to the pipe line (19) that connects the two reactors (6; 18) to each other. The apparatus according to any one of Items 1 to 14. [16] Claim [15] characterized in that the pipe line (19) connects the outlet side of the first reactor (6) and the inlet side of the second reactor (18) The device described. [17] The floor (5;
2. The device according to any one of claims [6] to [16], characterized in that a gas cooler (2) having a gas cooler (2) is connected thereto. [18] Claims [6] to [17] characterized in that the water/air nozzles (4) of the gas cooler (2) are arranged opposite to each other in the gas flow direction. Apparatus according to any of the following paragraphs. [19] Claims [6] to [18] characterized in that the reactor (6; 18) has a venturi structure.
] Apparatus described in any of the following paragraphs.