Method for producing of aluminosilicate microspheres from ash and slag wastes of heating electric power stations and furnace for drying of aluminosilicate microsperes

FIELD: process and equipment for producing of aluminosilicate microspheres.

SUBSTANCE: method involves separating aluminosilicate microspheres from ash and slag wastes by submerging said wastes into liquid; collecting aluminosilicate microspheres from liquid surface and drying in two stages: first drying stage involving holding of aluminosilicate microspheres at temperature of at least 2 C until residual moisture content of microspheres is below 30%, and second drying stage involving heating of aluminosilicate microspheres to temperature of 100-300 C in drum-type furnace by direct contacting of aluminosilicate microspheres with drum surface heated by means of external heating source until relative moisture content of microspheres is less than 3%. Furnace for drying of dispersed materials comprises drying chamber having inlet and outlet and made in the form of cylindrical drum mounted for rotation around its axis. Drying chamber inlet is equipped with device for feeding of material to be dried therein, and outlet is equipped with device for removal of dried material therefrom. Axis of cylindrical drum is positioned at an angle to horizontal plane so that drying chamber inlet is arranged higher than its outlet. Cylindrical drum is mounted on two axially aligned shafts positioned for rotation around their axes and connected with drum. First shaft is disposed adjacent drying chamber inlet and second shaft is disposed adjacent drying chamber outlet and is made hollow. External heat source is arranged outside cylindrical drum so as to heat drum wall. Device for feeding material into drying chamber is formed as vibrating trough and device for removal of dried material from drying chamber is formed as screw mounted within second shaft.

EFFECT: reduced consumption of power, increased efficiency in drying of dispersed materials containing low weight particles, preferably hollow aluminosilicate microspheres, with increased extent of moisture removal, and provision for preventing microspheres from getting into atmosphere.

17 cl, 2 dwg

The invention relates to technologies for producing aluminosilicate microspheres and equipment for the implementation of the mentioned technologies. It can be used mainly in the energy industry to obtain aluminosilicate microspheres fly ash of thermal power plants.

Named aluminosilicate microspheres are an important commercial product, widely used in the production of lightweight ceramic insulation materials, spheroplasts, plugging materials and drilling fluids, radiotransparent and lightweight construction ceramics, insulating Besobrasova materials and heat-resistant concrete. Aluminosilicate microspheres can be obtained through industrial processes, but is most profitable to extract them from ash-slag waste generated during fuel combustion in thermal power plants, since the cost of such microspheres is more than 10 times lower than that of the microspheres obtained by the industrial method.

A method of obtaining hollow aluminosilicate microspheres, in accordance with which of ash and slag waste of thermal power plants produce these microspheres flotation method - dropping named waste water aluminosilicate microspheres float and stay on the surface of a pond, while the remainder of the waste is deposited on the bottom. With the surface of the water aluminosilicate Mick is ospero harvested mechanically using special tools. Next, the microsphere is served in a device for thermal drying, which is carried out by using the hot gases produced during the combustion of diesel fuel [Components angry and slag/ Kiselstein L.Y., Oaks IV, and others - M.: Energoatomizdat, 1995, p.59-62].

This method is adopted for the prototype of the invention. Its disadvantages include high consumption of flue gas and, accordingly, large power consumption, because after removing from the water aluminosilicate microspheres having a relative humidity of more than 50%, directly fed to the heat treatment and drying.

The invention solves the problem of creating a less energy-intensive economical method of producing silica-alumina microspheres of ash and slag waste TPP.

The problem is solved in that the proposed method of producing microspheres, which are separated aluminosilicate microspheres from ash waste by immersing the mentioned waste liquid collecting aluminosilicate microspheres from the surface of the liquid and dried in two stages, with the first stage of drying stand aluminosilicate microspheres at a temperature not lower than 2°before they reach the residual relative humidity less than 30%, and in the second stage of drying is heated aluminosilicate microspheres to a temperature of 100-300°in a rotary furnace by direct contact drained alumosilicate the x microspheres with heated from an external source the walls of the drum called the oven until they reach a relative humidity of not more than 3%.

Between the first and second stages of drying, it is advisable to clean aluminosilicate microspheres by wiping, i.e. skip microspheres through a coarse sieve to remove large unwanted inclusions.

After drying aluminosilicate microspheres become low, sift them through a sieve to separate fine inclusions and division on fractions.

Figure 1 shows the scheme of the proposed technology, where:

1 - "Division" means flotation separation of ash and slag waste, heavy ash fraction settles to the bottom, and a light hollow silica microsphere surface of the reservoir;

2 - "Warehousing" means the exposure of aluminosilicate microspheres to reduce its moisture content due to runoff and natural drying fluid;

3 - "Wiping" means the transmission of microspheres through a coarse sieve to remove large unwanted activation;

4 - "Drying" means forced drying in a special furnace to a residual relative humidity of not more than 3%;

5 - "Dispersion" means the purification of the finished product - aluminosilicate microspheres and division on fractions by sieving through one or more sieves.

The technology is implemented as follows.

Ash wastes method hydraulic output in ponds-UTS is Eunice hydraulic power station. Due to the difference of densities is a natural flotation separation of ash and slag waste, heavy ash fraction settles to the bottom, and a light hollow silica microsphere surface of the reservoir. Using pumps or even shovels collected from the surface and warehoused in handy for this purpose location: in the storage room, outdoors, or under a canopy. The relative humidity of the microspheres when the storage exceeds 50%. Further, when it is prone for any positive temperatures, excessive moisture from the microspheres evaporates, flows with its particles and after some time its relative humidity reaches 30%. After that silica microsphere sent for further processing. Thus it is clear from the various undesirable inclusions (particles of slag, stones, etc. by wiping, which is carried, the humid microsphere through a sieve. After that microspheres come in a drying furnace drum, which is heated wall to 100-300°C. the Drying is carried out until reaching a relative humidity of not more than 3%.

To carry out the proposed technology does not require flue gases, which simplifies design solutions, and the energy required is reduced.

When selecting aluminosilicate microspheres ash waste is ES important technological stage is drying. The drying aluminosilicate microspheres requires special equipment, as on the drying conditions, impose strict limitations on the temperature and residual moisture, as well as the particles are very light weight and easily carried by air, the equipment must also comply with environmental requirements and to prevent the release of particles into the atmosphere.

Known drying drum-type furnace for osushivaniya aluminosilicate microspheres [Components angry and slag/ Kiselstein L.Y., Oaks IV, and others - M.: Energoatomizdat, 1995 p.59-62]. It contains the drying chamber in the form of a hollow stationary drum provided with an input, an output and means for venting steam. Inside the chamber along its entire length is a screw designed to move material. Heat treatment of the microspheres is achieved by the combustion of diesel fuel in the combustion chamber. This oven has a complex structure, as it contains a combustion chamber for the combustion gases.

Famous kilns of various designs for drying various other particulate materials.

For example, known drying furnace for bulk materials, in particular wood chips, which contains the drum, the inner cavity of which is divided into sections of a co-current, countercurrent and removal of the drying agent annular partitions with fewer and larger inside them diameters, United profiled nozzle [RF Patent №2159915]. The drum has a mesh side wall and vertical disk drive installed in a section of the outlet of the drying agent can move along the axis of the drum and hold it in place, which is regulated by the degree of filling material sections are parallel. The degree of filling of dried material section of the counter is adjusted by moving the mesh of the end wall. The drying agent is fed through the mesh of the end wall, and is discharged through the perforations in the drum. The disadvantages of this furnace are also its complex design, the use of a drying agent, which makes its value is high enough. In addition, this drying oven is also unsuitable for drying of dispersed materials with low weight particles, such as silica-alumina microspheres, which due to the aforementioned low weight particles will be in large quantity be captured and carried away by the drying agent and discarded together with him in the atmosphere.

Also known drum dryer dispersed, predominantly granular materials. The dryer includes a drum in the form of a hollow perforated cylinder, made with the possibility of rotation around the longitudinal axis, the pipe for supplying the coolant, the loading means and unloading funnel [RF Patent №2159915]. Under what arabena mounted tube with holes, associated with pipeline supply of fluid inside the drum is installed on the spiral blades and the drum is made from a frame consisting of longitudinal rails connected by spokes and covered with removable grid.

This dryer is most similar to the claimed drying oven of similar features adopted for the prototype of the invention. The drawbacks of the dryer because the dryer is used coolant, so it has a complex structure, and it is unsuitable for drying in it dispersed materials with low weight particles, such as hollow aluminosilicate microspheres, due to entrainment of these particles coolant and contamination of their environment.

The invention solves the problem of creating a drying oven, suitable for drying of dispersed materials with low weight particles, mainly hollow aluminosilicate macrostar, with a high degree of moisture removal, and also prevents the ingress of dispersed particles in the atmosphere.

The problem is solved in that a furnace for drying particulate materials, comprising a drying chamber having entrance and exit is made in the form of a hollow cylindrical drum mounted for rotation around its own axis, with the entrance of the drying chamber is provided with means for supplying it the drying material, and in the course equipped with a means to remove the dried material, whose axis is called the cylindrical drum is at an angle to the horizontal so that the entrance of the drying chamber is located above its release, it called a cylindrical drum mounted on two coaxially arranged shafts made with the possibility of rotation around its own axis, with each of which he is still connected with the first shaft is located on the input side of the drying chamber, and the second shaft is located on the output side of the drying chamber and is hollow inside and outside of the cylindrical drum is equipped with an external heat source so that the heated wall of the drum, means for supplying the drying material in the drying chamber is made in the shape of the vibrator channel, and a means of removing the dried material from the drying chamber is made in the form of a screw mounted in a cavity called the second shaft.

To improve heat transfer in the drying chamber on its inner walls installed profiled blades, which increase the heat exchange surface, and also perform an additional function grab and move portions of the drying material during the rotation of the cylindrical drum. Blades can be installed radially and at an angle to the wall of the drying chamber.

To increase the residence time of the drying material in the drying ka the ore can be installed transverse annular partition, retarding the progress of the drying material from the entrance to the exit of the drying chamber and preventing the accumulation of dried material at the exit.

Installed at the outlet of the drying chamber of the screw can be equipped with a receiving hopper that receives drained material and then is captured and pushed to the exit through the cavity of the second shaft working body of the screw, which, as you know, is a shaft having a spiral ridge.

To the dried material is not in contact with the emitted during the drying in the drying chamber steam, the entrance to the drying chamber may be provided with a means for forced exhaust water vapor.

The means for supplying the drying material in the drying chamber and means for removing dried material from the drying chamber are located on opposite ends of the drying chamber.

An external heat source, heating the cylindrical wall of the drum may be made in the form of electric heaters, for example, the tube (Supplied)installed on the outer side of the aforementioned drum with a gap, allowing it to rotate.

It should be noted that to improve heat transfer and energy saving heating the material in the drying chamber can be carried out on areas with the possibility of independent control of the input power and maintaining the temperature for each of the Ohe. The temperature that must be maintained in each zone is determined for the specific operating conditions of the drying chamber, depending on the moisture content of the drying material. The length of the drying chamber can be divided into three zones: the entrance (35-45% of the length)adjacent to the input and output (15-25% of the length)adjacent to the outlet, and a Central, located between the input and output areas. When this quantity of heat supplied to the drying chamber, divided by zones as follows: in the entrance area can be allocated up to 50% of the total input of heat energy, in the Central 30% of the total input of heat energy, and in the output area - up to 20% of the total input of heat energy. Such an opportunity is created due to the different density of the heating elements along each zone: the greatest density of the heating elements along the entrance area, the lowest density of the heating elements along the outlet zone.

To reduce heat loss into the environment, the space around the heat sources, it is advisable to close the airtight casing with insulation.

We offer a drying oven shown in figure 2, where:

1 is a cylindrical drum, 2 - cover, 3 - shaft, 4 - spoke, 5 - vibrator channel, 6 - screw 7 - loading hopper, 8 - external heat source, 9 - heat solace, 10 - vanes are mounted radially, 11 - second shaft 12 is a means for forced exhaust of water vapor, 13 - blades set at an angle to the wall of the drying chamber, 14 - seal 15 - output drained material 16 is annular partition 17 is a bearing support, 18 - bearing screw 19 to the endcap.

The cylindrical drum 1 is set at an angle to the horizontal on the first shaft 3 and the second shaft 11. The first shaft is mounted in a bearing support 17 with the possibility of rotation and a cylindrical drum it is connected by means of spokes 4. Named the bearing support has a possibility of displacement along the axis of the drum to compensate for thermal expansion of the drum and is located in the cold zone. The second shaft is still connected to the cylindrical drum by means of the front flange 19, is made hollow and is mounted for rotation in a rigid bearing support located in the cold zone.

We offer a drying oven works as follows.

In the cavity of the drum 1 (drying chamber) is drained dispersed material, such as silica-alumina microsphere through a vibrator channel 5. The entrance of the drying chamber is higher than its output, since the cylindrical drum 1 is set at an angle to the horizontal, while it is mounted on the shaft 3 by means of spokes 4 still regarding him and on the second shaft 11 when the SIP the soup of the front flange 19 is stationary with respect to it. This allows the cylindrical drum 1 to rotate around its own axis on bearings 17.

During the rotation of the drum external heat source 8 heats the wall to the required temperature and the particles of the dispersed material, such as silica-alumina microsphere contact named walls, also heated. The blades 10 and 13 installed inside the drying chamber on the walls of the drum, also made of metal and heated together with the drum to the same temperature. They come into contact with the drained material, which increases the heat exchange surface. In addition, the blades capture the portion of the drying material and move them to the rotation of the drum. Annular partition 16 break the array of dried material into portions, resulting in a material more evenly moves inside the drying chamber from the entrance to the exit, preventing the accumulation output.

At the outlet of the drying chamber is installed loading hopper 7, which by means of the blades 13 is supplied reclaimed material and samotekom enters the screw 6, which is derived from the drying chamber.

Produced by heating the material within the drying chamber water vapor through the tool to force the exhaust water vapor is withdrawn from the drying chamber from the entrance, so it is not the mandate to engage the t with the dried material.

To prevent the infiltration of cold outside air into the volume of the drying chamber to reduce heat loss and ash particles dispersed material from the discharge unit of the drained material is made as follows. A cylindrical drum 1 on the output side of the drying chamber is closed by the flange 19 with a Central hole, in which is mounted a second shaft 11, is made hollow in the shape of a tube. Auger, comprising a tubular housing and a working body in the form of a shaft with a helical ridge, is installed inside the hollow shaft and mounted console on a support 18. At the end of the tubular housing screw that enters the drying chamber, rigidly mounted loading hopper 7, which receives the dried material and then moving the auger to the output. This solution allows you to close the internal volume of the drying chamber against ingress of cold outdoor air and allows the light particles of the dried material to diffuse to the atmosphere and pollute the atmosphere. With the same purpose furnace is equipped with a sealed heat-resistant seals installed in the places of entry and discharge of dispersed material, and removing the pair.

To prevent heat drying furnace is closed by a cover 2 with insulation 9.

The rate of passage of material through the drying chamber is determined by the tilting axis tsilindricheskoj the drum and the speed of its rotation.

Thus, the described drying oven is suitable for drying of dispersed materials, including low-weight particles, such as hollow aluminosilicate microspheres, while simple in construction, convenient in operation and does not contaminate the atmosphere with particles of dried material.

Example.

Hollow silica microsphere obtained from ash-slag waste heat power plants as fuel coal. Ash wastes method hydraulic appear in ponds hydraulic power station. Due to the difference of densities is a natural flotation separation of ash and slag waste, heavy ash fraction settles to the bottom, and hollow silica microsphere surface of the reservoir. With the help of pumps it is collected from the surface and warehoused in handy for this purpose place in the storage room. The relative humidity of the microspheres when the storage exceeds 50%. Further, when prone with temperature fluctuations from 2 to 30°With excess moisture from the microspheres evaporates, flows with its particles, and after 148 days, its relative humidity drops below 30%. After that silica microsphere sent for further processing. Thus it is clear from the various undesirable inclusions (particles of slag, stones, etc. by wiping that the implementation is given, the humid microsphere through a sieve with mesh size of 10-20 mm After the microsphere is supplied to the vibrator channel drying furnace and then into the drying chamber. When this wall drying oven heated to a temperature of 280°in the entrance area, 230°in the middle zone and 190°in the output area. At the outlet of the drying chamber with screw down aluminosilicate microsphere having a residual relative humidity less than 3%. Next microsphere emerging from the furnace, cooled to 50°With fractions according to particle size by sieving through a sieve and Packed.

1. A method of producing microspheres, which are separated aluminosilicate microspheres from ash waste by immersing the mentioned waste liquid collecting aluminosilicate microspheres from the surface of the liquid and dried, characterized in that the drying is carried out in two stages, with the first stage of drying stand aluminosilicate microspheres at a temperature not lower than 2°before they reach the residual relative humidity less than 30%, and in the second stage of drying is heated aluminosilicate microspheres to a temperature of 100-300°in a rotary furnace by direct contact drained aluminosilicate microspheres with heated from an external source to the walls of the drum named the oven until they reach a relative humidity of not more than 3%.

3. Oven for drying aluminosilicate microspheres, comprising a drying chamber having entrance and exit is made in the form of a hollow cylindrical drum mounted for rotation around its own axis, with the entrance of the drying chamber is provided with means for supplying it the drying material, and provided with a means to remove the dried material, characterized in that the axis of the mentioned cylindrical drum is at an angle to the horizontal so that the entrance of the drying chamber is located above its release, it called a cylindrical drum mounted on two coaxially arranged shafts made with the possibility of rotation around its own axis, with each of which he is still connected with the first shaft is located on the input side of the drying chamber, and the second shaft is located on the output side of the drying chamber and is hollow inside and outside of the cylindrical drum is equipped with an external heat source so that the heated wall of the drum, means for supplying the drying material in the drying chamber is made in the form of a vibrator channel, and a means of removing the dried material from the drying chamber is made in the form of a screw mounted in the spine called the second shaft.

4. Furnace according to claim 3, characterized in that the drying chamber is equipped with blades mounted on its walls.

5. Furnace according to claim 4, characterized in that the blades are installed perpendicular to the inner surface of the drying chamber.

6. Furnace according to claim 4, characterized in that the blades are installed at an angle to the inner surface of the drying chamber.

7. Furnace according to claim 3, characterized in that the drying chamber provided with a transverse annular partition.

8. Furnace according to claim 3, characterized in that the auger is provided by the admissions funnel, located in the drying chamber.

9. Furnace according to claim 3, characterized in that the drying chamber provided with a means of forced removal of vapor from it, which is installed on the input side.

10. Furnace according to claim 3, characterized in that the inlet and outlet are located on opposite ends of the drying chamber.

11. Furnace according to claim 3, characterized in that the drying chamber is airtight.

12. Furnace according to claim 3, characterized in that the drying chamber is equipped with an external insulation.

13. Furnace according to claim 3, characterized in that the external heat source is electric.

14. Furnace according to claim 3, characterized in that the drying chamber consists of an input area equal to 35-45% of the length of the drying chamber and adjacent to its input, the output area equal to 15-25% of the length of the drying chamber and adjacent to its outlet, and the Central C is well, located between the input and output zones.

15. Oven 14, characterized in that the input area comes not more than 50% of thermal energy.

16. Oven 14, characterized in that the Central zone receives no more than 30% of thermal energy.

17. Oven 14, characterized in that the output zone receives no more than 20% of thermal energy.