SU1369769A1 - Method of wet catching of aerosol from revolving steam and air flow - Google Patents

Abstract

This invention relates to a technique for the wet cleaning of vapor / air (vapor-gas) streams from fine particles of slaked lime suspended in them (aerosols of slaked lime). The purpose of the invention is to reduce emissions of hydrated lime toxic aerosols with water vapor into the atmosphere and to reduce the specific consumption of water. The vapor-air flow at a temperature of 50-60 ° C is brought into contact with a fine-dispersed water curtain at a temperature of 20-30 ° C, formed by fine spraying of water in the zone of quasi-solid rotation of the downward vortex flow, where a significant vacuum is created (150-250 mm water. ) due to the high velocities of vapor-air flow in the main and narrowed sections of the vortex. The resulting hydrated lime slurry in the form of a liquid film formed at the periphery of a rotating vortex flow is separated from the air flow and returned to the beginning of the process. 2 Il. since sl 00 and so

Description

This invention relates to a technique for the wet cleaning of vapor-air (vapor-gas) streams from fine particles of extinguished lime suspended in them (extinguished lime aerosols) and can be used in the building materials industry, for example in the technology of preparing a mixture for silicate bricks, and other industrial areas where possible. formation of an inhomogeneous aerosol system of hydrated lime in the vapor-air flow.

The aim of the invention is to increase the efficiency of the capture of hydrated lime aerosol by reducing emissions of B-atmosphere and reducing specific water consumption.

The vapor-air flow at 50-60 ° C is brought into contact with a fine water curtain at 20-30 ° C under a vacuum of 150-250 mm created in the zone of quasi-solid rotation of the downward vortex flow, after which the flow is narrowed and the resulting water suspension is quenched lime in the form of., a bone film formed on the periphery of a rotating vortex flow, is separated from the air flow and returns to the beginning of the process.

At 20-30 ° C, sprayed water is introduced into the zone of quasi-solid rotation of the downward vortex poyuk, where a rather significant vacuum is created (150-2 psi mm water column) due to the high velocity of the vapor-air flow in the main and narrowed vortex sections (in the vortex cross section, the liner velocity of the vapor-air flow is 6–9 m / s, in the narrowed section, 12–15 m / s). Under vacuum conditions, which are enhanced by the narrowing of the flow, evaporation from the surface of droplets of sprayed water supplied at 20-30 ° C occurs, and a highly developed surface (fine water on the curtain) is created to contact the incoming rotating air-flow with a temperature of 50 ° C. 60 (;, in which the hydrated lime aerosol is located. When the water temperature is below 20 ° C under the same hydrodynamic conditions, evaporation from the surface of liquid droplets decreases, the contact surface decreases, and the possibility of leakage Steam section of X air stream with aerosol

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hydrated lime with the same specific consumption of water (in studies it is 0,015-0,030 kg / m, which is about 2-3 times lower than the specific consumption of water in comparison with the known method). When the water temperature is above 30 ° C (under the same other conditions), the driving force of the vapor condensation process decreases, and it becomes possible to partially break through the hydrated lime spray with the vapor flow.

Studies have shown that in the specified temperature range of a vapor-air flow (50-60 ° C) brought into contact with a fine water curtain, the rate of vapor condensation is sufficient to completely condense the vapor to form a hydrated lime slurry in the form of a liquid film formed on the periphery. rotating vortex flow. When the temperature of the vapor stream is below 50 ° C, the rate of condensation of water vapor decreases, and it becomes possible to partially break through the sprayed slab of lime through the water curtain, resulting in a decrease in the efficiency of vapor stream cleaning. When the temperature of the vapor stream is above 60 ° C, the rate of condensation of water vapor from the vapor stream increases due to the greater amount of heat released per unit of time during condensation, but more water evaporates from the surface of the sprayed water droplets, resulting in the possibility of breakthrough hydrated lime aerosol through a water curtain.

The observed events were observed at specific water consumption of 0.015-0.030 kg / m. Naturally, it is possible to achieve complete capture of the hydrated lime aerosol by increasing the specific water consumption, 040 kg / m), but this is not economical. The features of the proposed

The wet method of trapping aerosol hydrated lime from the vapor-air flow allows for complete capture of the hydrated lime spray with little specific water consumption.

Figure 1 shows the installation of the implementation of the proposed method; figure 2 - section aa in figure 1 (with a device for supplying water).

The installation includes a centrifugal type apparatus, including a housing 1, a vortex chamber 2, a cylindrical nozzle 3, in the lower part of which a blade swirl A with a cone 5, inlet 6 and outlet 7 tangential nozzles, a centrifugal nozzle 8 with a needle valve, a float chamber 9 with a float 10, a fitting 11 with a supply pipe 12, an overflow pipe 13 and a pipe 14 for supplying water to the nozzle 8.

The installation also contains an exhaust fan 15, a discharge 16 and a suction pipe 17, an exhaust pipe 18, an intermediate tank 19, a stirrer 20, a transfer pipe 21, a mixer 22, mixing rollers 23, sand supply lines 24 and hydrated lime 25, fitting 26 for air leaks into the mixer 22 and the nozzle 27 for removal of the technological mass, directed to the formation of silicate bricks.

The method of wet trapping aerosol hydrated lime from a vapor-air flow is carried out as follows.

In mixer 22 as a result of the interaction of water with slaked lime (lines 24 and 25 are introduced into the mixer, respectively, slaked lime and quartz sand, which, upon adding water under conditions of thorough mixing with the help of paddle rollers 23, form the technological mixture for making silicate bricks) a significant amount of heat is generated, due to which water evaporates with part of the hydrated lime aerosol. Formed in the mixer 22 over the technological mass of the vapor phase with fine particles of slaked lime has a temperature of 70-80 ° C. To create an air vapor flow with a temperature of 50-60 ° C, necessary according to the proposed cleaning method, from the opposite side of the mixer 22 from the pipe 17 through the fitting 26 there is a part of the air from the room (the slide is installed at the fitting to control the air supply which is not shown).

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Thus, the resulting vapor-air mixture with a hydrated aerosol is carried out in an amount of 5,000 m / h at 55 ° C using an exhaust fan 15 via line 17 to a centrifugal-type apparatus for clearing off hydrated lime. The device is introduced into the apparatus through a tangential nozzle 6, as a result of which the vapor-air flow acquires a rotational (vortex) motion and in this state contacts with a fine water curtain having a temperature of 25 C.

Water for spraying is supplied to the nozzle 8 from the float chamber 9 through line 14 by gravity flow, spraying is carried out due to the pressure of water created by the liquid column between the nozzle and the float chamber (water consumption for spraying is controlled by a needle valve inside the nozzle). The centrifugal nozzle 8 complete with the float chamber 9 ensures uniform and constant water consumption without energy consumption for spraying.

The water on the curtain is formed when the nozzle 8 sprays water under vacuum conditions in the zone of quasi-solid rotation of the vortex flow of 200 mm of water flow, with a specific flow rate of 0.02 kg / m and a vapor-air flow rate of 8 m / s. full cross section of the vortex chamber 2. As a result of the highly developed contact surface formed, water vapor is condensed with hydrated lime aerosol. The liquid film formed from the periphery of the vortex flow moves under the action of centrifugal force and gravity from top to bottom along the surface of the vortex chamber 2, enters the cylindrical nozzle 3 where the flow is stabilized and then passes into the blade vortex A to enhance the centrifugal phase separation. A cone 5 is installed under the swirler 4 to prevent the secondary vortex that is formed.

The liquid phase separated from the air flow with ghee lime (an aqueous slurry of hydrated lime) aerosol moves to the lower part of the apparatus and is discharged into the intermediate tank 19 with a 2P agitator (the agitator serves to prevent sedimentation

solid particles of slaked lime to the bottom of the tank 19). The lower end of the apparatus with a liquid in the intermediate tank 19 forms a water seal, ensuring stable operation of the apparatus. The liquid level in the intermediate tank 19 is maintained by means of a transfer pipe 21, through which excess liquid (suspension) enters the mixer 22, where a technological mass is formed to form the silicate brick with the help of mixing rollers 23.

Separated from the suspension, the air flow from the vane swirler 4 is discharged through the output tangential nozzle 7, through the pipe 16 with the help of the fan 15 and discharging

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peraturu 25 ° C. The velocity of the vapor-air flow in the vortex chamber is 8 m / s, the specific water flow rate is 0.02 kg / m, and the negative pressure is 200 mm of water.

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Art.

At the same time, the efficiency of cleaning the vapor stream from aerosol of hydrated lime was 100%. 10 Example 3. Steam-air flow with Slaked lime aerosol is brought into contact with a fine water curtain having a temperature of 25 ° C. The velocity of the steam-air flow in the vortex chamber is 8 m / s, the specific water flow rate is 0.02 kg / m, vacuum - 200 mm of water. Art.

Efficiency of vapor cleaning

into the atmosphere through the exhaust pipe flow from the aerosol of the slaked hut 18.

Under these conditions, complete capture of the hydrated lime aerosol from the vapor stream is ensured, and the resulting hydrated lime slurry returns to the beginning of the process (to mixer 22). The hydraulic resistance of the apparatus is 110 mm of water. Art.

When carrying out the cleaning method at temperatures of a steam-air flow of 50 and 60 ° С with a contacted water curtain at 20 and 30 with the same hydrodynamic regime, no significant changes in the cleaning of the steam-air flow from hydrated lime were observed - 100% capture of the aerosol was carried out hydrated lime.

Example 1. A vapor stream with hydrated lime spray at 55 C. is brought into contact with a finely dispersed water curtain having a temperature of 50

The 25 ° C steam-air flow rate in the vortex chamber of the new flow, calculated for a full set of 8 m / s, the specific flow rate of the hooped section of the vortex chamber, the elevation was 0.02 kg / m, the depression - 200 held at 8 m / s. The specific consumption of water was 0.02 kg / m (0.02 kg of water per 1 m of air). The vacuum in the vortex chamber - 200 mm of water. Art.

Under these conditions, a 100% capture of the hydrated lime spray was carried out.

Example 2. A steam-air stream with hydrated lime aerosol at 50 ° C is introduced into KOHTaifCT with a finely dispersed water curtain having a temperature of

waters Art.

under these conditions, the cleaning efficiency was 97.6%. This is probably due to the fact that during the phase contact process, the vapor condensation rate increases due to the heat of condensation released per unit time, and therefore more water evaporates from the surface of the water curtain per unit time. The possibility of an aerosol slip through the air stream.

Under these conditions, news was 100%.

Example A. Steam-air flow with hydrated lime aerosol at

45 C is brought into contact with a fine-dispersed water curtain having a temperature of 25 C. The velocity of the vapor-air flow in the vortex chamber is 8 m / s, the specific water flow is 0.02 kg / m, the vacuum in the vortex chamber is 200 mm water. Art.

Under these conditions, the rate of vapor condensation decreases and the possibility of partial aerosol slipping through a fine water curtain appears. As a result, the efficiency of cleaning the air flow from the slaked lime aerosol drops to 96%.

Example 5. Steam Air

Current with hydrated lime at 65 ° C is brought into contact with a fine water curtain having a temperature of 25 ° C. Steam locomotive speed50

45 air flow in the vortex chamber was 8 m / s, the specific consumption of water - 0.02 kg / m, vacuum - 200

mm

waters Art.

under these conditions, the cleaning efficiency was 97.6%. This is probably due to the fact that during the phase contact process, the vapor condensation rate increases due to the heat of condensation released per unit time, and therefore more water evaporates from the surface of the water curtain per unit time. The possibility of an aerosol slip through the air stream.

Example 6. A vapor-air stream with hydrated lime aerosol at 55 ° C is brought into contact with a fine water curtain having a temperature of 16 ° C. The velocity of the vapor-air flow in the vortex chamber was 8 m / s, the specific water flow rate was 0.02 kg / m, the vacuum pressure was 200 mm of water. Art.

Under these conditions, the efficiency of cleaning the vapor-air flow from the azo-hydrated lime was 98.5%. This decrease in cleaning efficiency is due to the fact that the contact surface of the water curtain is somewhat reduced due to the deterioration of evaporation of a part of the sprayed water, and consequently, some aerosol slip with the air flow appears. In order to improve the evaporation conditions of sprayed water, it is possible to increase the vacuum in the center of the quasi-solid rotation of the vortex, increasing the velocity of the vapor-air flow, however, this leads to an increase in the hydraulic resistance

Example 7. A vapor-air stream with hydrated lime aerosol at 55 ° C is brought into contact with a fine water curtain having a temperature of 35 ° C. The velocity of the vapor-air flow in the vortex chamber is 8 m / s, the negative pressure is 200 mm of water. Art., specific water consumption - 0.02 kg / m.

The efficiency of cleaning the vapor stream from aerosol under these conditions is 98%. This is caused by the fact that the rate of vapor condensation decreases under these conditions as compared with the previous example, and at the indicated specific water flow rate, a partial overshoot of aero appears possible. angry lime with air flow through the water curtain.

Example 8. A vapor-air stream with hydrated lime aerosol at 55 ° C is brought into contact with a fine water curtain having a temperature of 20 C. The velocity of the vapor-air flow in the vortex chamber is 8 m / s, the vacuum is 200 mm of water. Art., specific water consumption - 0.02 kg / m

Under these conditions, the cleaning efficiency of the vapor stream from the aerosol of lime was 100%,

Example 9. Steam-air flow with hydrated lime aerusol at

current 50 ° С

55 ° C is brought into contact with a fine water curtain having a temperature. The velocity of the vapor-air flow in the vortex chamber was 8 m / s, the vacuum pressure was 200 mm of water. Art., specific water consumption - 0.02 kg / m.

Under these conditions, the efficiency of cleaning the vapor-air flow from the azrozole slaked lime was 100%.

Example 10. A vapor-air stream with hydrated lime aerosol at 50 ° C is introduced into contact with a fine water curtain, having a temperature of 20 ° C. The velocity of the vapor-air flow in the vortex chamber was 8 m / s, the vacuum pressure was 200 mm of water. Art., the specific consumption of water 0.02 kg / m.

The cleaning efficiency of the vapor stream from aerosol was 100%.

Example 1. A vapor-air aerosol of hydrated lime is brought into contact with a fine water curtain having a temperature of 30 C. The velocity of the vapor-air flow in the vortex chamber is 8 m / s, the vacuum is 200 mm of water. Art., specific consumption of water-0.02 kg / m.

The cleaning efficiency of the vapor-air flow from aerosol under these conditions was 100%.

Example 12. A vapor-air stream with hydrated lime aerosol at 60 ° C is brought into contact with a fine water curtain having a temperature of 20 ° C. Hydrodynamic conditions are the same as in the previous examples.

The cleaning efficiency of the vapor stream from aerosol was 100%.

Example 13. A steam-air stream with hydrated lime aerosol at 60 ° C is brought into contact with a fine water curtain having a temperature of 30 ° C. The hydrodynamic conditions are the same as in the previous examples.

At the same time, the efficiency of cleaning the vapor flow from aerusol hydrated lime was 100%.

Example 14. A vapor-air stream with hydrated lime aerosol at 55 ° C is brought into contact with a fine water curtain having a temperature of 25 ° C. The rate of the vapor-air flow calculated for a full 913

The cross section of the vortex chamber was maintained at 6 m / s, the specific water consumption was 0.02 kg / m. The vacuum at the same time amounted to 140 mm of water. Art.

Under these conditions, the efficiency of cleaning the air flow from the slaked lime aerosol falls to 97.9%. This is due to the deterioration of the conditions of evaporation of a portion of the sprayed water and a decrease in the surface of contact with the hydrated lime aerosol. However, the hydraulic resistance decreases and amounts to 65 mm of water. Art. (in the conditions of example 1, hydraulic resistance 110mm water. Art.).

Example 15. A vapor-air stream with hydrated lime aerosol at 55 ° C is brought into contact with a fine water curtain having a temperature of 25 C. The vapor-air flow rate calculated for the total cross-section of the vortex chamber is maintained at 10 m / s, the specific flow rate of POD151 is 0 , 02 kg / m.

The vacuum at the same time was 255 mm of water. Art.

Under these conditions, the cleaning efficiency is 100%. However, the hydraulic resistance increases dramatically and amounts to 182 mm of water. Art. (in the conditions of example 1, the hydraulic resistance was 110 mm water. Art.).

Studies have shown that a rational interval for changing the vacuum is 150–200 mm of water. Art. In this range, under all conditions of temperature and specific consumption

water purification rate is 100%. 40 vapor flow.

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Thus, the use of the invention makes it possible to continuously purify the vapor-air flow from a toxic spray of slaked lime at a specific flow rate. water, less than 2-3 times compared with the known method.

It should also be noted that this method is recommended to be carried out under conditions of a downward swirling vapor-air flow interacting with high speed with water.

curtain and providing the specified vacuum required for this cleaning method, as well as preventing the separation of liquid particles from the liquid film and their discharge with the nostril stream.

Claims (1)

Invention Formula A method for wetly collecting an aerosol from a rotating vapor-air stream by contacting it with water, characterized in that, in order to increase the efficiency of collecting the aerosol of hydrated lime by reducing emissions into the atmosphere and reducing the specific consumption of water, the vapor-air flow is brought into contact at 50–60 ° C with a finely dispersed water curtain at 20–30 ° C in conditions of dilution of 150-250 mm of water, station generated in the zone of quasi-solid rotation of the downward vortex flow, and the resulting aqueous suspension of hydrated lime is returned to the ////////////////// /////////////////// Л FIG. 1 A A YU P If / 13