RU209137U1 - Electric Vermiculite Kiln - Google Patents

Abstract

The utility model relates to an electric vermiculite kiln. SUBSTANCE: electric furnace for firing vermiculite contains a dispenser, baking sheets made of refractory material, set at an angle of 45° for pouring vermiculite and containing covers made of ceramic vermiculite plates with zigzag heaters placed under each of them and held by fastening heads and earrings fixed on the covers, in plate accelerators of vermiculite are installed on the upper end parts of the baking sheets, made symmetrically with respect to the longitudinal axes of symmetry of the baking sheets in the form of a set of fixed plates with different angles of inclination with respect to the refractory bases of the baking sheets and so that the plate located in the central zone of the baking sheet has the largest angle, at adjacent plates to the left and to the right of it, the angles of inclination are smaller than those of the central plate, the plates following them to the left and right have even smaller angles, and the extreme plates do not have an angle of inclination relative to the refractory surfaces of the baking sheets, the dosing drum is made with longitudinal steps o-variable in depth grooves on its surface, with the greatest depth being the grooves located above the central plate, the grooves of the dispenser drum adjacent to the left and right have a slightly smaller depth, the grooves following to the left and right have an even smaller depth, and the extreme grooves have the smallest depth, moreover, the extreme plates are fixed rigidly, and all other plates are hinged and equipped with screws to change the angle of inclination relative to the refractory bases of the pan. EFFECT: increased productivity during firing of vermiculite. 6 ill.

Description

The utility model relates to the field of building materials, namely to technological equipment for the production of expanded vermiculite from vermiculite concentrates.

Known electric oven for firing vermiculite (RU No. 161281, IPC F27B 15/00, published 20.04.2016), containing trays with lids; the trays are made of refractory material and are installed relative to each other at an angle that ensures the pouring of intumescent vermiculite from one to another, and electric heaters placed under the covers of the trays longitudinally and fixed on heads with parallel edges, electric heaters made with consoles and located above the surface of the baking sheets with a gap, while the consoles of the electric heaters are suspended in the lower part of the baking sheets on earrings, hinged through ceramic bushings on the rods installed on the covers of the baking sheets.

Common features with the claimed utility model are a baking sheet made of refractory material, a lid, electric heaters placed with a gap along the baking sheet under the covers, heads for attaching heaters and earrings.

This oven has the following disadvantage. Electric heaters do not provide uniform heating across the width of the refractory surface of the baking sheets and, therefore, heat the vermiculite moving along the baking sheets and intumescent also not evenly. Measurements of temperatures in the operating furnace in different zones of the trays showed that the temperature of the refractory base in the central zone can reach 600...680 °C, and at the edges of the tray 470...540 °C. Therefore, the vermiculite leaving the oven is completely expanded in the central zone of the lower pan and has a lower density than the vermiculite leaving the oven along its edges.

This is due to the fact that any section of the refractory base in the central part receives thermal radiation from the heaters located above it, as well as from the heaters located to the right and left of it.

The same section, taken in the side zones of the refractory base, receives thermal radiation from the heaters located above it and from neighboring heaters only to the right or only to the left. Therefore, the vermiculite moving along the baking sheets in the side zones receives significantly less thermal energy than the vermiculite moving in the central zone.

Known electric furnace for firing vermiculite (RU No. 179055, IPC F27B 9/00, published 04/25/2018), containing baking sheets with lids made of refractory material and installed relative to each other at an angle that provides pouring of vermiculite during the firing process from one on the other, and electric heaters placed under the covers of the baking sheets longitudinally above the surface of the baking sheets with a gap, fixed on heads with parallel edges to ensure their parallel installation and made with consoles suspended in the lower part of the baking sheets on swivel earrings fixed through ceramic electrically insulating bushings pivotally on the rods mounted on the covers of the baking sheets, the earrings are made in the form of L-shaped levers, one of the arms of which hold the consoles of the electric heaters, and the others are equipped with weights that ensure the tension of the electric heaters and the constancy of the gap.

Common features with the claimed utility model are a baking sheet made of refractory material, a thermal cover, electric heaters placed under it, heads for attaching heaters and earrings.

This oven has the same disadvantage. Electric heaters provide non-uniform heating of the refractory surface of the trays and, therefore, heat the moving and intumescent vermiculite unevenly. Therefore, the vermiculite exiting the oven is fully expanded in the central area of the lower pan and has a lower bulk density than slightly under-expanded vermiculite exiting the oven along the sides of the lower pan.

As a prototype, an electric oven for firing vermiculite (RU No. 202161, IPC F27B 9/00, published on February 4, 2021) was adopted, containing a housing connected to a dispenser containing a drum, while the upper baking sheet, the lower baking sheet and the lower baking sheet are placed in the furnace body vermiculite particles, installed with an inclination for the possibility of pouring vermiculite particles, each of which is made of a refractory material and contains a lid with a ceramic vermiculite plate, while a zigzag heater is fixed under the ceramic vermiculite plate with fastening heads and earrings, an accelerator of movement of vermiculite particles in the form of a set of plates containing a rigidly fixed base plate, symmetrically with respect to the longitudinal axes of symmetry of the baking sheet, other rigidly fixed plates and a central plate, which is fixed in the central zone of the baking sheet at an angle α _{4 of} inclination to the base of the baking sheet, other plates to the left and right of it are fixed are at an angle α _{3 of} inclination to the base of the pan, the plates following them are fixed at an angle of α _{2 of} inclination to the base of the pan, and the base plate, installed at the extreme, is fixed without an angle of inclination to the base of the pan, while α ₂ < α ₃ < α ₄ , and on the surface of the drum, longitudinal grooves with a step-variable depth are made, while the grooves with the greatest depth are located above the central plate of the upper pan, above the plates to the left and right of the central one there are grooves with a smaller depth, after which there are grooves with an even smaller depth, and the extreme grooves, located under the main plate have the smallest depth.

Common features with the claimed utility model are a housing, a dispenser with a drum, on the surface of which there are longitudinal grooves that are stepwise variable in depth, while the grooves with the greatest depth are located above the central plate of the upper pan, above the plates to the left and right of the central plate there are grooves with a smaller depth , after them there are grooves with an even smaller depth, and the extreme grooves have the smallest depth; the upper baking sheet, the lower baking sheet and the lower baking sheet, installed with an inclination for the possibility of pouring vermiculite particles, the baking sheets are made of refractory material and contain lids with a ceramic vermiculite plate, a zigzag heater is fixed under it with fastening heads and earrings, an accelerator of particle movement is installed in the upper end part of each baking sheet in the form of a set of plates, which includes a rigidly fixed base plate, symmetrically to the longitudinal axis of symmetry of the baking sheet, rigidly fixed plates adjacent to it and a central plate; the latter is fixed in the central zone of the baking sheet at the greatest angle to the base of the baking sheet, the other plates to the left and right of it are fixed at a smaller angle to the base of the baking sheet, the plates following them are fixed at another angle to the base of the baking sheet, and the base plate along the edges of the baking sheet is fixed without an angle of inclination to the base of the baking sheet.

The considered furnace has the same disadvantage. Electric baking tray heaters do not provide uniform heating across the width of their refractory surface and, therefore, heat the moving and intumescent vermiculite along the trays also unevenly. Measurements of temperatures in the operating furnace in different zones of the trays showed that the temperature of the refractory base of the trays in the central zone can reach 600 ... 680 ° C, and in the side zones 470 ... 540 ° C. Therefore, the vermiculite leaving the oven in the central zone of the lower pan swells completely and even undergoes burnout (especially small particles), which partially reduces its strength due to the increase in the fragility of the grains, and the vermiculite leaving the oven along its edges barely has enough thermal energy to swell , and large particles may remain underexpanded.

At the same time, vermiculite particles move at the same speed in the center and on the sides, while in more heated zones they could move faster, increasing the productivity of the furnace and at the same time maintaining high-quality swelling without overburning.

The claimed utility model is aimed at improving the performance of an electric furnace during the firing of vermiculite of different fractions by controlling the speed of movement of its intumescent grains in more heated areas of baking sheets with an increased temperature relative to the side zones.

The technical result of the utility model is to increase the productivity of the electric furnace when firing different fractions by controlling the speed of movement of the intumescent vermiculite grains in the more heated areas of the baking sheets.

The specified technical result is achieved by the fact that an electric furnace for firing vermiculite, containing a dispenser, baking sheets made of refractory material, set at an angle of 45 ° for pouring vermiculite and containing covers made of ceramic vermiculite plates with zigzag heaters placed under each of them and held by fixing heads and earrings attached to the lids. At the same time, the drum of the dispenser is made with longitudinal grooves, stepwise variable in depth, on its surface.

In the upper parts of the trays, plate accelerators of vermiculite are installed, made symmetrically about the longitudinal axes of symmetry of the trays in the form of a set of plates with different angles of inclination with respect to the refractory bases of the trays. The plate placed in the central zone of the baking sheet has the largest angle, the adjacent plates to the left and right of it have the same slope angles and are smaller than those of the central plate, the plates following them to the left and right have equal and even smaller angles, and the most extreme plates have a zero angle relative to the refractory surfaces of the baking sheets. Due to the different inclination of the plates, the vermiculite particles receive different initial velocities.

On the surface of the dispenser drum, the grooves located above the central plate of the upper accelerator of the upper pan have the greatest depth, i.e. above the most heated zone, where vermiculite particles move at maximum speed and where the supply of the feedstock - vermiculite concentrate, should be maximum.

The slots of the dosing drum adjacent to the left and to the right have a slightly smaller depth so that the supply of raw materials would correspond to the local productivity in the neighboring less heated zones corresponding to these slots and the accelerator plates below them (adjacent to the central zone).

And so on: the farther from the central zone the grooves of the dispenser drum are located, the smaller their depth. The most extreme grooves have such a depth that in the drums of batchers of furnaces (analogues) not equipped with vermiculite accelerators, it is sustained over the entire surface of the drum.

The most extreme plates of lamellar accelerators of vermiculite are rigidly fixed without the possibility of changing the angle of inclination relative to the refractory bases of the pans, and all their other plates are hinged and provided with screws to change the angle of inclination relative to the refractory bases of the pan. This is done in order to change their angle of inclination with the help of screws and control the speed of movement of intumescent vermiculite grains in each differently heated zone, including when switching to firing from one raw material fraction to another.

Those intumescent grains of vermiculite that enter the refractory surface of each of the pans from the central accelerator plate have the highest, but adjustable with screws, speed in the central most heated zone of the pan, which allows you to optimally adjust the local (in the central zone with maximum heating) performance, at the same time, the optimal time of movement of these grains is ensured, at which they have time to fully swell.

Other particles of vermiculite, which enter the refractory surface of each of the pans from the adjacent central plates, move at a slightly lower, but controlled speed, since their angle of inclination is smaller (but also adjustable), and therefore the initial speed is also lower. But in this zone, the heating of the refractory bases of the oven trays is also less.

And so on: the farther from the central zone the vermiculite accelerator plates are located, the lower (but adjustable) the speed of vermiculite particles in their zones. But here the heating of refractory bases is also less.

In the side zones, the slope of the accelerator plates is zero; therefore, in these zones, the particles move at an unincreased speed equal to that with which all particles would move in the absence of a vermiculite accelerator plate.

Thus, the local productivity (productivity by heating zones) in the claimed utility model is different and manageable, but on average it is significantly higher than in similar furnaces not equipped with lamellar vermiculite accelerators.

Distinctive features of the claimed utility model is the use of lamellar vermiculite accelerators, in which the extreme plates are fixed rigidly without the possibility of changing the angle of inclination relative to the refractory bases of the pans, and all other plates are hinged and equipped with screws to change the angle of inclination relative to the refractory bases of the pan.

The presence of distinctive features proves the compliance of the claimed utility model with the condition of patentability "novelty".

In FIG. 1 schematically shows an electric vermiculite kiln.

In FIG. 2 schematically shows a vermiculite kiln tray (side view).

In FIG. 3 is a schematic cross-sectional view of a plate-like vermiculite accelerator.

In FIG. 4 is a schematic view of the electric heater, the refractory base of the pan, the vermiculite accelerator plate, and a longitudinal section through the dosing drum of the oven, indicating the approximate distribution of temperatures across the width.

In FIG. 5 shows vector diagrams of the velocities of vermiculite particles as they pass through the plates of the vermiculite accelerator.

In FIG. 6 schematically shows two sections of the dosing drum in its center and along the edges.

Electric vermiculite kiln, fig. 1, contains a drum dispenser of raw materials (vermiculite concentrate) with a chute 1, through which the concentrate is poured onto a plate vermiculite accelerator, fixed in the upper part of the upper baking sheet 2. The same vermiculite accelerators are installed on two other baking sheets 3 and 4. The oven trays are installed in its body 5 at an angle of 45° and include heaters 6 with covers made of ceramic vermiculite plates 7, Fig. 1 and 2, with a metal corner edging 8, fig. 2.

The wire heater 6 is placed and fixed under the ceramic vermiculite plate 7 of the baking sheet lid with rounded hooks 9 of the earrings and on the fixing heads 10, fig. 1 and 2 mounted on the lids of trays 2, 3 and 4, FIG. 1. The earrings themselves are held in the holes 11 of the ceramic vermiculite plate 7 due to the flat hooks 12, FIG. 2.

Mounting heads 10 provide electrical contact between themselves and the two ends of the heater 6 due to the threaded connection 13, Fig. 2 and 4, and supply electrical cables (not shown in the figures).

There is a gap a between the heaters 6 and the refractory bases of the trays, fig. 2, the same along the entire length of the baking sheet l, fig. 2.

A vermiculite accelerator plate is installed at the top of each pan, FIG. 1, 2, 3 and 4, consisting of a base plate 14, FIG. 2, 3 and 4, stop 15 and a set of hinged plates 16, 17 and 18, FIG. 3, with different angles of inclination α ₂ , α ₃ and α ₄ associated with screws 19.

The dispenser drum is made with longitudinal grooves 20, 21, 22 and 23, stepwise variable in depth, Fig. 4 and 6, with the grooves 20 above the central plate 18 of the vermiculite accelerator having the greatest depth (t ₄ ). To the left and right of the grooves 20, the grooves 21 of the drum, located above the plates 17 of the vermiculite accelerator, have a somewhat shallower depth (t ₃ ). The grooves 22 adjacent to the grooves 21 above the plates 16 have an even shallower depth (t ₂ ), while the outermost grooves 23 have a minimum depth (t ₁ ), FIG. 4.

The number of vermiculite accelerator plates and their corresponding number of grooves on the drum may vary depending on the overall width of the pan B. In addition, the width of the grooves of the drum B ₁ , B ₂ , B ₃ , and B ₄ and the corresponding width of the vermiculite accelerator plates may also be different depending on the total width of the tray B and depending on the temperature distribution in zones 1, 2, 3, etc.

Electric kiln for firing vermiculite works as follows.

Raw materials are fed through tray 1 from the oven dispenser to the vermiculite accelerator of the upper baking sheet 2 and then to its refractory surface, along which it moves in the thermal field of the heaters 6. The vermiculite partially expanded on the upper baking sheet 2 is poured onto the vermiculite accelerator of the lower baking sheet 3, where it is also exposed to heat from heaters 6. Then, almost completely expanded vermiculite is poured onto the plate accelerator of the lower pan 4 and finally swells in its thermal field created by the heater 6 of the lower pan, fig. 1 and exits as a finished product from the oven. The duration of firing in such a furnace with a baking sheet length of 950 mm, as shown by measurements on a pilot furnace, is approximately 3 seconds [Nizhegorodov A.I., Zvezdin A.V. Energy technological units for the processing of vermiculite concentrates / Irkutsk: Publishing House of IRNITU, - 2015. - 250 p.]. During the production operation of the pilot furnace, it was found that electric heaters do not provide uniform heating of the refractory surface of the baking sheets along the width (the same 950 mm) and when firing vermiculite concentrates of various fractional composition, its temperature in the central zone can reach 600 ... 680 ° C, and in the side zones 470...540 °C, as shown in Fig. 4. Therefore, the vermiculite passing through the baking sheets of the oven in the central zones (zones 4 and 3, Fig. 4) swelled completely, but was slightly burnt from excess thermal radiation, and the vermiculite passing through the baking sheets of the oven in the side zones (zones 2 and 1, Fig. 4) there was barely enough thermal energy for swelling. At the same time, both in the center and along the edges of the baking sheets, vermiculite particles moved with the same speeds [Nizhegorodov A.I., Zvezdin A.V. Energy technological units for the processing of vermiculite concentrates / Irkutsk: Publishing House of IRNITU, - 2015. - 250 p.].

In the oven design under consideration, plate accelerators of these particles are installed in each baking sheet to set different speeds for particles of intumescent vermiculite, Fig. 2, 3 and 4.

Thus, the particles falling on the plates 18, Fig. 3 and 4 located in the central zone No. 4, FIG. 4, get the highest initial speed along the refractory surfaces v _04x due to the larger angle of inclination α _{4 of} the plate 18 to the surface of the refractory base (see also vector diagrams of the velocities of vermiculite particles when passing through the vermiculite accelerator plates, Fig. 5). Therefore, the speed of their movement along the central zones of the baking sheets (zones No. 4, Fig. 4) is greater than it would be if there were no vermiculite accelerators. Therefore, due to the increase in the average speed of particles in the central zones, the local productivity in the central zone No. 4 will increase in proportion to the speed of movement, and the time for particles to pass through them will decrease. Nevertheless, despite the reduction in the firing time, the swelling of vermiculite will be complete (in the absence of overburning) due to a more powerful temperature effect.

In zones 3 in all oven trays the temperature is lower than in the hottest zone 4 of the trays, but it is still significantly higher than in zones 1 at the edges of the trays. Therefore, here the particles falling on the plates 17, Fig. 3 and 4 located in the central zones No. 3, FIG. 4, a slightly lower initial velocity along the refractory surfaces v _{03x is obtained} due to the slightly smaller angle of inclination α _{3 of} the plate 17 to the surface of the refractory base (see also FIG. 5). The average velocity of vermiculite particles in zones #3 is less than in zones #4, but more than it would be if the oven were not equipped with vermiculite accelerators. Due to the increase in the average speed of particles in zones No. 3, the local productivity in these zones will be proportional to the average speed of movement, and the time for particles to pass through them will be reduced.

In zones No. 2, the average speeds v _02x , Fig. 4 and 5, due to the smaller angle of inclination α ₂ the plates 16 are smaller than in zones #3 and #4, but larger than in zones #1.

Thus, due to the different inclinations of the plates 18, 17 and 16, FIG. 2 and 3, such a predetermined distribution of average speeds over zones No. 4, No. 3, No. 2 and No. 1 of the oven trays is provided that in more heated zones, Fig. 4, the vermiculite swells in less time on the oven trays, while still fully swells. Due to the increase in average particle velocities in the hotter zones, the local productivity of the furnace in these zones increases where the refractory bases of the pans are heated more.

Using the screws 19, you can adjust the angle of inclination of the plates 16, 17 and 18 and control the speed of movement of the intumescent vermiculite grains in zones No. 1, No. 2, No. 3 and No. 4 when setting the oven for optimal performance by zones or in cases where the oven is being adjusted for optimal operation with a different type of raw material or a different fraction of raw materials, with larger or smaller particles on average, since the size of the particles affects their speed.

Vermiculite accelerator plates located in zones No. 1 have a zero angle of inclination to the refractory base of trays 2, 3 and 4, therefore the initial velocity of particles passing through them is zero: v _01x = 0, fig. 5 and 4.

Plates of 16 vermiculite accelerators inclined at an angle α₂and located in zones No. 2, have an initial velocity of particles passing through them equal to: v_02x > 0, fig. 5 and 4.

Plates of 17 vermiculite accelerators inclined at an angle α₃and located in zones No. 3, have an initial velocity of particles passing through them equal to: v_03x >v_02x, fig. 5 and 4.

Plates of 18 vermiculite accelerators inclined at an angle α₄and located in the central zones No. 4, have the initial velocity of particles passing through them equal to: v_04x >v_03x, fig. 5 and 4.

To change the local productivity by zones, the angles of the accelerator plates can be changed by means of screws 19, while the angular speed of rotation of the drum must also be corrected in one direction or another.

To ensure increased local productivity, the metering drum, rotating at an angular velocity ω, is made with longitudinal grooves 20, 21, 22 and 23, stepwise variable in depth, Fig. 4 and 6, on their surface with their equal width b, fig. 6.

Due to the different depths of the grooves, in zone No. 4, Fig. 4, where the vermiculite particles move at the maximum average speed, the supply of vermiculite concentrate is maximum.

The grooves 21 of the dispenser drum adjacent to the left and right have a slightly shallower depth, so that the supply of raw materials would correspond to the local productivity in zones No. 3 corresponding to these grooves and accelerator plates 17, Fig. 4.

And so on: the farther from the central zone No. 4 the grooves of the dispenser drum are located, the smaller their depth. The most extreme grooves have a minimum depth, corresponding in terms of feed to the average particle velocities in zones No. 1.

Due to the fact that the electric furnace for firing vermiculite is equipped with an accelerator of vermiculite particles for heating zones on each baking sheet and a dispenser with a drum with longitudinal grooves that are stepwise variable in depth on its surface, an increase in local (by zones) productivity and productivity of the furnace as a whole is provided.

So, with a width of baking sheets B = 95 cm (as in a pilot-industrial furnace), the productivity of the furnace without lamellar accelerators on vermiculite concentrate of the KVK-4 brand (4 is a conditional number reflecting the size of the concentrate) is approximately 0.75 m ³ / hour, and the hourly productivity reduced to a unit of width will be equal, m ³ / cm h:

P _pr \u003d 0.75 / 95 \u003d 0.0079.

Local productivity in zone No. 4 with an increase in the average particle velocity, for example, by 20%, with a plate width of 18 (and, accordingly, zone No. 4) B ₄ \u003d 18 cm, will be equal, m ³ / hour:

P _{No. 4} \u003d 0.0079 18 1.2 \u003d 0.1707.

Local productivity in two zones No. 3 with an increase in the average particle velocity in them, for example, by 15%, with a plate width of 17 (and, accordingly, zones No. 3) B ₃ \u003d 14 cm, will be equal, m ³ / hour:

P _{No. 3} \u003d 2 0.0079 14 1.15 \u003d 0.2544.

Local productivity in two zones No. 2 with an increase in the average particle velocity in them, for example, by 9%, with a plate width of 16 (and, accordingly, zones No. 2) B ₂ \u003d 12 cm, will be equal, m ³ / hour:

P _{No. 2} \u003d 2 0.0079 12 1.09 \u003d 0.2067.

Local productivity in two zones No. 1, where the average speed does not increase, with the width of zones No. 1 in B ₁ \u003d 12.5 cm, will be equal, m ³ / hour:

P _{No. 1} \u003d 2 0.0079 12.5 1.0 \u003d 0.1975.

The total productivity of the furnace will be equal, m ³ / hour:

P \u003d 0.1707 + 0.2544 + 0.2067 + 0.1975 \u003d 0.8293,

which is 10.6% more.

Depending on the temperature distribution of the refractory surface by zones, on the width of the plates of the vermiculite accelerators, on the adjustable values of their inclination angles, and on the depth of the grooves of the furnace dosing drum, as well as depending on the type of raw material and its fraction, local and total productivity may differ in some limits.

This is how a useful technical result is achieved - increasing the productivity of an electric furnace when firing different fractions of vermiculite by controlling the speed of movement of intumescent vermiculite grains in more heated areas of baking sheets.

Claims (1)

Electric oven for firing vermiculite, containing a dispenser, baking sheets made of refractory material, set at an angle of 45 ° for pouring vermiculite and containing lids of ceramic vermiculite plates with zigzag heaters placed under each of them and held by fixing heads and earrings attached to the lids, in the upper end parts of the baking sheets, plate accelerators of vermiculite are installed, made symmetrically about the longitudinal axes of symmetry of the baking sheets in the form of a set of fixed plates with different angles of inclination with respect to the refractory bases of the baking sheets and so that the plate located in the central zone of the baking sheet has the largest angle, at neighboring plates to the left and right of it, the angles of inclination are less than those of the central plate, the plates following them to the left and right have even smaller angles, and the outer plates do not have an angle of inclination relative to the refractory surfaces of the baking sheets, the dosing drum is made with longitudinal steps grooves that are often variable in depth on their surface, with the grooves located above the central plate having the greatest depth, the grooves of the dispenser drum adjacent to the left and right have a slightly smaller depth, the grooves following to the left and right have an even smaller depth, and the extreme grooves have the smallest depth, characterized in that the extreme plates are fixed rigidly, and all other plates are hinged and equipped with screws to change the angle of inclination relative to the refractory bases of the pan.

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