Ceramsite calcination and firing system

Abstract

Disclosed in the present invention is a ceramsite calcination and firing system. The ceramsite calcination and firing system comprises a ceramsite calcination kiln and further comprises a grate cooler used for cooling a ceramsite, wherein the ceramsite calcination kiln is a rotary ceramsite calcination kiln, and a feeding port and a discharging port of the rotary ceramsite calcination kiln are mounted at a slope of 2.5% at a feeding end of the grate cooler; a temperature measurement device moving horizontally along a kiln body is provided on an outer wall of a kiln body; and a sealing door cover is connected to a discharging end of the rotary ceramsite calcination kiln, and a lower end face of the door cover is connected to a feeding port of the grate cooler in a sealing manner. By using the above rotary ceramsite calcination kiln to produce a ceramsite, the orderly release of gas-generating substances within the ceramsite is realized, and ceramsites of different pore structures are obtained; the liquid phase content on the surface of the ceramsite is increased, the degree of vitrification on the surface of the ceramsite is increased, the water absorption rate is reduced, the surface strength is improved, etc; and by using the grate cooler, the cooling capacity is significantly improved, the efficiency of waste heat recovery is increased, and the power consumption for cooling is reduced.

Description

A ceramsite roasting and firing system Technical Field

[0001] The invention belongs to the technical field of rotary ceramsite roasting kiln and ceramsite roasting, and in particular relates to a ceramsite roasting and firing system. Background Art

[0002] Currently, domestic production of ceramsite is primarily based on plug-in, variable-diameter, double-drum rotary kilns or single-drum, long kilns (φ3.5m-65m). These rotary kilns integrate drying, pelletizing, preheating, calcining, and cooling. While their advantages lie in their high degree of integration, their disadvantages include low fuel utilization, high heat dissipation from the kiln drum due to their long length, low kiln filling rates, and low production output. Furthermore, they occupy a large floor space and produce a limited number of ceramsite products. A British design employs a three-lobed kiln with a high-temperature internal lining made of nickel-cadmium alloy and a three-lobed cross-section. The external castable is alumina fiber. This three-lobed kiln offers greater energy efficiency and environmental benefits compared to traditional rotary kilns. However, due to its complex cross-sectional structure, the kiln is difficult to manufacture, and the uneven thickness of the internal castable leads to significant thermal stress concentration under high-temperature conditions, seriously shortening its service life.

[0003] A Chinese patent (CN 109539777 A) discloses a rotary ceramsite roasting kiln, wherein the inner wall of the rotary kiln cylinder is stacked with a refractory brick layer, and the refractory brick layer has at least three lifting structures formed by arched protrusions along the axial direction of the cylinder and protruding toward the inner side of the cylinder. The arched protrusions of the lifting structure protrude from the surface of the refractory brick layer on its side. This patent builds a three-leaf rotary structure along the axial direction in the kiln. The arched lifting structure built with refractory bricks is prone to high wear rate under the impact of materials and may even fall off. It is especially easy to fall off when the material is relatively sticky or when it forms rings and snowballs, posing a dangerous risk. In addition, the lifting structure is provided with an expansion gap, which is easily blocked when firing larger materials and loses its expansion function, which makes it more likely to cause the arched structure to fall off. In particular, when installing the above-mentioned material turning cylinder, there is always a corner at the connection between the turning cylinder and the inner wall of the cylinder body, and a smooth transition cannot be achieved. Therefore, in the actual production process, this part is prone to material storage problems, and it is also easy to squeeze and break the expanded clay, resulting in poor molding quality and a high breakage rate.

[0004] A Chinese invention (CN103575095B) discloses a waterfall-type rotary ceramsite roasting kiln, wherein the inner wall of the rotary ceramsite roasting kiln is provided with at least three material turning cylinders extending axially along the rotary ceramsite roasting kiln cylinder and arranged along its cross section. Each material turning cylinder is formed by splicing together multiple sections of two-section closed cylinders along the axial direction of the rotary ceramsite roasting kiln cylinder, with a hollow center, and the cross section of the material turning cylinder is semicircular. This material lifting structure can lift the material to a certain height and then drop it, thereby improving the heat exchange efficiency of the material. However, since the material turning cylinders are installed on the inner wall of the rotary ceramsite roasting kiln cylinder, there is always a corner at the connection between the turning cylinder and the inner wall of the cylinder, and a smooth transition cannot be achieved. Therefore, in the actual production process, this part is prone to material storage problems and is also prone to squeezing and breaking the ceramsite, resulting in poor molding quality and a high breakage rate.

[0005] A Chinese invention (CN 113834320 A) discloses a rotary ceramsite roasting kiln for ceramsite roasting. The inner wall layer of the rotary ceramsite roasting kiln cylinder is provided with a plurality of grooves extending axially and evenly distributed along the rotary ceramsite roasting kiln cylinder. The inner wall layer is also provided with a plurality of protrusions extending axially and evenly distributed along the rotary ceramsite roasting kiln cylinder. The cross-sections of the protrusions and grooves are both arc-shaped. The protrusions and grooves are arranged alternately and the transition between adjacent protrusions and grooves is smooth. The depth of the grooves is much greater than the height of the protrusions, and the angle of the arc of the groove cross-section is much greater than the angle of the arc of the protrusion cross-section. In this patent, the kiln cylinder is full of grooves or protrusions, which limits the kiln's rotation speed to a very slow level. The residence time of the ceramsite raw material in the kiln is relatively long, which will result in high energy consumption and low thermal efficiency. Since there is no buffering material in the grooves, the particle breakage rate will be high. Especially when the ceramsite raw material has just entered the grooves from the tail of the kiln, the material residence time is relatively long, resulting in a high raw material particle breakage rate, and the increase in smoke and dust at the tail of the kiln makes subsequent treatment difficult.

[0006] In addition, the existing technology for cooling ceramsite mostly adopts single-cylinder coolers and vertical coolers. Both single-cylinder coolers and vertical coolers cannot effectively recover the heat of ceramsite clinker, and the cooling efficiency is relatively low. Especially when the specifications of the rotary kiln become larger, the ceramsite clinker cannot be effectively cooled, and the heat at the kiln head cannot be effectively recovered to make up for the insufficient waste heat at the kiln tail for drying the ceramsite raw balls.

[0007] Summary of the Invention

[0008] In view of the problems existing in the prior art, the present invention provides a ceramsite roasting and firing system.

[0009] The present invention is achieved in this way: a ceramsite roasting and firing system includes a ceramsite roasting kiln, which is characterized by: further comprising a grate cooler for cooling the ceramsite; wherein the ceramsite roasting kiln is a rotary ceramsite roasting kiln, and the feed port and the discharge port of the rotary ceramsite roasting kiln are installed at the feed end of the grate cooler with a slope of 2.5%; a temperature measuring device is provided on the outer wall of the kiln body and moves horizontally along the kiln body; the discharge end of the rotary ceramsite roasting kiln is connected to a sealed door cover, and the lower end surface of the door cover is sealed and connected to the feed port of the grate cooler.

[0010] Preferably, the rotary ceramsite roasting kiln includes a kiln body, and the inner wall of the kiln body is provided with a refractory layer from the kiln head to the kiln tail, and is characterized in that: the kiln body is composed of a material stopping check zone and a rapid roasting zone from the feed end to the discharge section, a material feeding constriction is provided on the feed port side in the material stopping control zone, a material stopping boss is provided in the middle of the material stopping zone, and the rapid combustion zone is provided with three or more arch height portions of curved surface structures along the circumferential direction of the kiln body; and a discharge constriction is provided in the discharge section of the rapid roasting zone.

[0011] Preferably, both the inlet constriction and the outlet constriction are provided with inward guide slopes.

[0012] Preferably, the height of the material-blocking boss is not greater than 1 / 2 of the height of the arched portion.

[0013] Preferably, the rotary ceramsite roasting kiln comprises a kiln body, the inner wall of the kiln body is provided with a refractory layer from the kiln head to the kiln tail, the kiln body is sequentially composed of a preheating and denitrification zone, a shaping and control zone and a rapid calcination zone from the feeding end to the discharging section, the cross-sectional area in the kiln body decreases in sequence from the preheating and denitrification zone, the shaping and control zone and the rapid calcination zone, and a plurality of annular protrusions for prolonging the residence time of the material and regulating the orderly release of the gas-generating substances inside the ceramsite are provided in the shaping and control zone along the axial direction of the kiln body, and a receiving groove for filling the active substance is formed between adjacent annular protrusions; the rapid combustion zone is provided with three or more arch height portions with curved surface structures along the circumferential direction of the kiln body.

[0014] Preferably, the cross-sectional area of ​​the shaping and regulating zone is 70% to 80% of the cross-sectional area of ​​the preheating and denitrification zone; and the cross-sectional area of ​​the rapid calcination zone is 50% to 60% of the cross-sectional area of ​​the preheating and denitrification zone.

[0015] Preferably, the length of the kiln body is L; the length of the preheating and denitrification zone is less than or equal to 0.3L; the length of the shaping and control zone is 0.25-0.4L; and the length of the rapid calcination zone is 0.3-0.45L.

[0016] Preferably, the distance between each two adjacent annular protrusions is 2-4 times the height of the annular protrusions, the height of each annular protrusion is 0.05-0.1 times the kiln radius, and the width of the root of the annular protrusion is 1-2.5 times the height.

[0017] Preferably, the height of the annular protrusion is the same from the feeding direction to the discharging direction or increases linearly along the moving direction of the ceramsite.

[0018] Preferably, the curve variation of the arch height portion is a function of y=xn, wherein n is an arbitrary real number, and n>0.

[0019] Advantages and technical effects of the present invention: The present invention adopts the above technical solution and has the following advantages:

[0020] 1. By adding the design of the non-return area of ​​ceramsite material, backflow is prevented while the gas-generating substances inside the ceramsite are released in an orderly manner, and ceramsite with different pore structures and bulk densities is obtained; at the same time, the breakage rate of ceramsite is reduced.

[0021] 2. Through the design of the rapid roasting area, the liquid phase amount on the surface of the ceramsite is increased, the porcelain degree of the surface of the ceramsite is improved, the water absorption rate is reduced, and the surface strength is improved.

[0022] 3. The grate cooler is used to replace the traditional single-drum cooler and vertical cooler cooling method, which greatly improves the cooling capacity, increases the waste heat recovery efficiency, and reduces the cooling power consumption.

[0023] Therefore, by optimizing the internal structure design of the rotary ceramsite roasting kiln, efficient and rapid ceramsite production is achieved, and the productivity of ceramsite is improved; the internal structure design of the ceramsite kiln and the production method of the present invention have high application value and promotion value, and have broad market prospects in the field of ceramic production. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] FIG1 is a schematic structural diagram of embodiment 1 of the present invention;

[0025] FIG2 is a schematic structural diagram of a ceramsite roasting kiln according to Example 1;

[0026] FIG3 is a cross-sectional view of FIG2 AA;

[0027] Figure 4 is a sectional view BB in Figure 2;

[0028] Figure 5 is a schematic diagram of the structure of the ceramsite roasting kiln in Example 2;

[0029] FIG6 is a cross-sectional view AA in FIG5;

[0030] Figure 7 is a sectional view BB in Figure 5;

[0031] Figure 8 is a cross-sectional view of CC in Figure 5.

[0032] In the figure, 100, ceramsite roasting kiln; 200, grate cooler; 300, temperature measuring device; 400, sealed door cover;

[0033] 1. Kiln body; 101. Material stopper and check area; 111. Material stopper boss; 102. Rapid roasting area; 103. Feeding neck; 104. Arch height; 105. Discharging neck; 106. Diversion slope; 121. Preheating and denitrification area; 122. Shaping and control area; 123. Rapid calcination area; 124. Annular protrusion; 125. Receiving trough; 126. Arch height; 2. Refractory layer; DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0035] In Example 1, please refer to Figures 1 to 4. A ceramsite roasting and firing system includes a ceramsite roasting kiln 100 and a grate cooler 200 for cooling the ceramsite. In the field of ceramsite roasting technology, the grate cooler is used for the first time. The grate cooler is usually used in cement clinker. Since the liquid phase of cement clinker is mostly large, while the liquid phase of ceramsite is very small, there is basically no agglomeration. Therefore, the existing grate cooler is modified and the rolling device at the discharge port of the grate cooler is cancelled. Since the bulk density of ceramsite is lower than that of cement clinker, the porosity in the stacked state on the grate bed becomes larger, the penetration ability of the cooling air becomes stronger, the required cooling air pressure becomes smaller, and power consumption is saved. Therefore, the height of the material stacking in the grate cooler (or the height of the grate bed) is increased, the unit cooling capacity of the grate cooler is greatly improved, the waste heat recovery efficiency is improved, and the cooling power consumption is reduced. The above-mentioned ceramsite roasting kiln is a rotary ceramsite roasting kiln. The inlet and outlet of the rotary ceramsite roasting kiln are installed at the inlet end of the grate cooler with a slope of 2.5%; a temperature measuring device 3 is provided on the outer wall of the kiln body and moves horizontally along the kiln body; the discharge end of the rotary ceramsite roasting kiln is connected to a sealed door cover 400, and the lower end face of the door cover is sealed and connected to the inlet of the grate cooler.

[0036] The rotary ceramsite roasting kiln in this embodiment adopts the following structure, specifically including a kiln body 1, the inner wall of the kiln body is provided with a refractory layer 2 from the kiln head (discharge end) to the kiln tail (feed end). The kiln body is divided into a material blocking non-return zone 101 and a rapid roasting zone 102 from the feed end to the discharge section, and a material blocking boss 111 is provided in the middle of the material blocking zone. The cross-sectional shape of the material blocking boss is a trapezoidal structure, and the height of the material blocking boss is not more than 1 / 2 of the height of the arch height to avoid being too high; wherein the material blocking non-return zone 101 prevents material return and sealing, and at the same time prolongs the residence time of the material at the kiln tail, and the same material is heated relatively slowly per unit time, preventing the ceramsite from rushing directly to the kiln head, thereby meeting the roasting time of the ceramsite blank and ensuring the quality of the ceramsite; a material inlet constriction 103 is provided on the side of the feed inlet in the material blocking control zone to reduce the breakage of the ceramsite.

[0037] The rapid combustion zone is provided with three or more arch height portions 104 of curved surface structure along the circumferential direction of the kiln body. Preferably, the curve change of the arch height portion is a function of y=xn, wherein n is an arbitrary real number and n>0. In this embodiment, there are four arch height portions. The rapid calcination zone mainly realizes rapid calcination of ceramsite in a thermoplastic state, rapid heat exchange and porcelainization of the ceramsite surface. When entering the rapid calcination zone, facing the high temperature brought by the spray gun flame, the surface of the ceramsite quickly forms a slightly molten liquid phase, sealing the gas inside the ceramsite inside the ceramsite. The gas inside will produce a certain uniform expansion, thereby causing the volume of the ceramsite to begin to expand or slightly expand instantly. At this time, after the ceramsite enters the burner and cools, the surface of the ceramsite forms a porcelain state, which is conducive to reducing water absorption and improving surface strength. A homogeneous porous structure is formed inside, reducing the bulk density of the ceramsite. A discharge constriction 105 is provided in the discharge section of the rapid calcination zone to collect the ceramsite.

[0038] Preferably, the outer wall of the kiln body is provided with a temperature measuring device 3 that moves horizontally along the kiln body. Preferably, the temperature measuring device is a CS400 rotary kiln thermal imaging system, which uses continuous infrared monitoring to image each brick in the kiln in real time, thereby preventing high costs due to downtime and extending the equipment operation time. The CS400 rotary kiln thermal imaging system is designed for harsh furnace environments and is an integrated solution. The equipment can monitor the rotary kiln and detect abnormal hot spots, helping your team avoid high costs and unplanned downtime due to kiln damage; it monitors problems with the cylinder at all times, scans the outer wall of the cylinder, and provides real-time feedback on temperature changes in the entire kiln body. If it is higher than the safe temperature, it proves that the refractory material in the kiln body is damaged and needs to be repaired in time. If it is lower, it means it is under-fired and the roasting temperature needs to be adjusted;

[0039] Preferably, the feed necking, the discharge necking and the arch height are all provided with an inward guide slope 106 to prevent the ceramsite from breaking during transportation and to play a guiding role.

[0040] The present invention adopts the above-mentioned rotary ceramsite roasting kiln to produce ceramsite, and arranges an SNCR high-temperature denitration device at the center of the feed end of the rotary ceramsite roasting kiln. The outlet temperature of the denitration nozzle of the SNCR high-temperature denitration device is ≥750°C, and the SNCR high-temperature denitration device is arranged in the center of the kiln deep into the interior of the kiln tail, and then the rotary ceramsite roasting kiln is opened for firing. Preferably, the rotation speed of the rotary ceramsite roasting kiln is 0.1-5r / min; the fired ceramsite is retained from the discharge end of the rotary ceramsite roasting kiln and enters a grate cooler after passing through a sealed door cover to cool the ceramsite, thereby completing the roasting and cooling of the ceramsite.

[0041] Example 2, please refer to Figures 1, 5 to 8; a ceramsite roasting and firing system, including a ceramsite roasting kiln 100, and also including a grate cooler 200 for cooling the ceramsite; the above-mentioned ceramsite roasting kiln is a rotary ceramsite roasting kiln, and the inlet and outlet of the rotary ceramsite roasting kiln are installed at the inlet end of the grate cooler with a slope of 2.5%; a temperature measuring device 3 that moves horizontally along the kiln body is provided on the outer wall of the kiln body; the discharge end of the rotary ceramsite roasting kiln is connected to a sealed door cover 400, and the lower end face of the door cover is sealed and connected to the inlet of the grate cooler.

[0042] The rotary ceramsite roasting kiln in this embodiment adopts the following structure, specifically including a kiln body 1

[0043] Please refer to Figures 5 to 8. A segmented roasting rotary kiln includes a kiln body 1. The inner wall of the kiln body is provided with a refractory layer 2 from the kiln head (discharge end) to the kiln tail (feed end). The kiln body is divided into a preheating and denitrification zone 121, a shaping and control zone 122 and a rapid calcination zone 123 from the feed end to the discharge section. The cross-sectional area of ​​the kiln body decreases in sequence from the preheating and denitrification zone, the shaping and control zone and the rapid calcination zone. In the shaping and control zone, several annular protrusions 124 are provided along the axial direction of the kiln body to extend the residence time of the material and regulate the orderly release of the gas-generating substances inside the ceramsite. A receiving groove 125 for filling the active substance is formed between adjacent annular protrusions; the rapid combustion zone is provided with three or more arch height portions 126 with curved surface structures along the circumferential direction of the kiln body, and there are three of them in this embodiment. For general solid waste calcination, the refractory layer material solid waste can be made of any of silica-mullite bricks, anti-scaling high-alumina bricks, mullite refractory materials, and magnesia-alumina spinel refractory materials. For hazardous waste raw materials that are severely corroded by alkali, sulfur, chlorine, and other volatile components, silica-mullite bricks are generally used to improve thermal shock resistance and wear resistance. For 3D printing integrated molding technology, amorphous refractory materials are used: cement-free refractory castables, anti-scaling castables, phosphate refractory castables, alkali-resistant castables, and thermal insulation castables.

[0044] The core innovation of the present invention, namely the technical effect of the segmented design, is described in detail below:

[0045] Preheating denitrification zone function: The intelligent in-and-out adjustable SNCR function can be set at the kiln tail according to the denitrification temperature. Because the material carrying height in this area is relatively small, the breakage rate can be reduced, and the drying area is larger than the structure with all protrusions or all three leaves, which can quickly improve the drying of ceramsite raw balls.

[0046] The shaping and control zone ensures sufficient dwell time for the material and regulates the orderly release of gas-generating substances within the ceramsite, thereby producing ceramsite with varying pore structures. Specifically, the groove structure can be pre-filled with silica fume or rice husk ash active substances to coat the ceramsite surface, effectively coating the molten ceramsite with a layer of active substances. For fired gangue and sludge ceramsite, these materials can reside in this zone for sufficient time to volatilize their volatile organic compounds, which are then burned off the thermoplastic ceramsite surface. The collision and friction between the thermoplastic ceramsites creates a tighter surface, sealing the release of internal gases.

[0047] Function of the rapid calcination zone: It is mainly to achieve rapid calcination, rapid heat exchange and ceramicization of ceramsite in a thermoplastic state. When entering the rapid calcination zone, facing the high temperature brought by the torch flame, the surface of the ceramsite quickly forms a slightly molten liquid phase, sealing the gas inside the ceramsite. The internal gas will produce a certain uniform expansion, causing the volume of the ceramsite to begin to expand instantly or slightly. At this time, after the ceramsite enters the burner and cools down, the surface of the ceramsite forms a ceramic state, which is conducive to reducing water absorption and improving surface strength. A homogeneous porous structure is formed inside, reducing the bulk density of the ceramsite.

[0048] In actual production, the above structure can adopt the following technical solutions: the thickness of the steel plate of the ceramsite kiln is 25-40mm; the thickness of the refractory material of the ceramsite kiln cylinder from the kiln tail to the kiln head is 150-200mm, and the aspect ratio is 5-10.

[0049] The masonry method of refractory materials in the kiln: the preheating and denitrification zone adopts ordinary masonry method, and the shaping and control zone is based on the preheating and denitrification zone and uses refractory bricks and kiln shell to be masoned together along the axial section using high-temperature resistant bonding materials and rake nails to form annular protrusions. The distance between each two adjacent annular protrusions is 2-4 times the height of the annular protrusions, the height of each annular protrusion is 0.05-0.1 times the radius of the kiln, and the width of the root of the annular protrusion is 1-2.5 times the height. From the feeding direction to the discharging direction, the height of the annular protrusions is the same or gradually increases linearly along the movement direction of the expanded clay. The rapid calcination zone uses refractory bricks and the refractory materials of the shell to be bonded together with a binder.

[0050] These annular protrusions can be assembled together before shipment and baked at high temperatures to ensure a secure bond. Furthermore, these special-shaped structures can be 3D printed in one piece and then dried at high temperatures before shipment or after on-site installation. Alternatively, they can be 3D printed in sections, tailored to the specific functional areas of the kiln, and then dried at high temperatures to achieve a final shape. This improves construction efficiency and quality while saving labor costs.

[0051] The refractory material in each of the three sections is tailored to the nature of the material, whether it is solid waste or hazardous waste. This prevents the crusting and blockage that can occur during firing in the existing spliced ​​three-lobed structure, which can even cause kiln lining shedding, as well as snowballing damage to the three-lobed structure and even cracking in the kiln body. The refractory material in the arch section, formed in one piece using 3D printing technology, offers high-quality molding, seamlessness, consistent thermal expansion properties, and excellent refractory properties.

[0052] Further preferably, the curve variation of the arch height portion is a function of y=xn, wherein n is an arbitrary real number, and n>0.

[0053] Further preferably, the cross-sectional area of ​​the shaping and regulating zone is 70% to 80% of the cross-sectional area of ​​the preheating and denitrification zone; and the cross-sectional area of ​​the rapid calcination zone is 40% to 50% of the cross-sectional area of ​​the preheating and denitrification zone.

[0054] Further preferably, the length of the kiln body is L; the length of the preheating and denitrification zone is less than or equal to 0.3L, the length of the shaping and control zone is 0.25-0.4L; and the length of the rapid calcination zone is 0.3-0.45L.

[0055] Further preferably, the distance between each two adjacent annular protrusions is 2-4 times the height of the annular protrusions, the height of each annular protrusion is 0.05-0.1 times the radius of the kiln, the width of the root of the annular protrusion is 1-2.5 times the height, and the height of the annular protrusions is the same from the feeding direction to the discharging direction or gradually increases linearly along the direction of movement of the ceramsite.

[0056] Further preferably, the preheating and denitrification zone, the shaping and control zone, and the rapid calcination zone of the kiln body are an integrated structure.

[0057] Furthermore, the kiln's preheating and denitrification zone, shaping and control zone, and rapid calcination zone are preferably separate units. This allows each functional area to achieve optimal calcination of the ceramsite. Each section is equipped with a drive device that can adjust the speed according to the characteristics of the material being fired to adapt to different operating conditions.

[0058] The ceramsite kiln of the present invention is designed with three different functional areas. Firstly, it is to solve the problem that the ceramsite raw material balls have a long residence time in the kiln and a high breakage rate due to the convex or grooved structures along the axial direction of the kiln; secondly, it is to solve the problem that when the kiln is all trilobal structures, the filling rate in the front section is high, and the ceramsite raw material balls at the kiln tail are lifted to nearly 90 degrees and fall, resulting in more breakage and impact damage; thirdly, it is to solve the problem that when the kiln is all smooth straight tube kiln without any structure, the filling rate is low, and the length of the kiln needs to be lengthened to burn qualified ceramsite, and the lengthening of the kiln makes the temperature at the kiln tail lower, which is not conducive to the denitrification efficiency of the high-temperature SNCR at 850°C. In particular, the too low denitrification temperature will make the subsequent denitrification use the SCR denitrification technology with higher investment cost, and the investment and floor space will increase after the kiln becomes longer.

[0059] The present invention also discloses a method for producing ceramsite, which comprises adopting the integrated segmented roasting rotary kiln to roast ceramsite, arranging an SNCR high-temperature denitration device at the center of the feed end of the rotary kiln, the outlet temperature of the denitration nozzle of the SNCR high-temperature denitration device being ≥750°C, and arranging the SNCR high-temperature denitration device at the center of the kiln so as to penetrate into the kiln tail by 1-3 kiln tail inner diameters of the rotary kiln; adding silica ash or rice husk ash active substances to coat the surface of the ceramsite between the annular protrusions in the shaping and control area of ​​the rotary kiln, wherein the presence of the substances can also reduce the impact between particles and reduce the breakage rate; and then starting the rotary kiln to roast the ceramsite.

[0060] The present invention also discloses a production method of ceramsite, which adopts a segmented roasting rotary kiln to fire the ceramsite, wherein the preheating and denitrification zone, the shaping and control zone, and the rapid calcination zone of the rotary kiln are separated, and an SNCR high-temperature denitrification device is arranged at the center of the feed end of the rotary kiln, the outlet temperature of the denitrification nozzle of the SNCR high-temperature denitrification device is ≥750°C, and the SNCR high-temperature denitrification device is arranged in the center of the kiln to penetrate into the kiln tail by 1-3 times of the inner diameter of the rotary kiln at the kiln tail; silica ash or rice husk ash active material is added between the annular protrusions of the shaping and control zone of the rotary kiln to coat the surface of the ceramsite; and then the rotary kiln is started.

[0061] The preheating and denitrification zone, shaping and control zone, and rapid calcination zone of the rotary kiln maintain different rotation speeds respectively;

[0062] Alternatively, when the organic carbon content in the ceramsite is ≤2%, the preheating and denitrification zone, shaping and control zone, and rapid calcination zone of the rotary kiln maintain the same rotational speed. When the organic carbon content in the ceramsite is greater than 2%, the shaping and control zone and rapid calcination zone maintain the same rotational speed and are greater than or equal to the rotational speed of the preheating and denitrification zone of the rotary kiln. This ensures that each functional zone can achieve the optimal effect on the calcination of the ceramsite.

[0063] Preferably, the rotation speed of the preheating and denitrification zone is 1.5-3 r / min, the rotation speed of the shaping and control zone is 2.0-3 r / min, and the rotation speed of the rapid calcination zone is 2.5-4 r / min.

[0064] In summary, by optimizing the internal structure design of the rotary ceramsite roasting kiln, efficient and rapid ceramsite production is achieved, the productivity of ceramsite is improved, the cooling capacity of the grate cooler is greatly improved, the waste heat recovery efficiency is increased, and the cooling power consumption is reduced.

[0065] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A ceramsite roasting and firing system, comprising a ceramsite roasting kiln, characterized in that: It also includes a grate cooler for cooling expanded clay; wherein the expanded clay roasting kiln is a rotary expanded clay roasting kiln, and the feed inlet and discharge port of the rotary expanded clay roasting kiln are installed at the feed end of the grate cooler at a slope of 2.5%; a temperature measuring device that moves horizontally along the kiln body is provided on the outer wall of the kiln body; the discharge end of the rotary expanded clay roasting kiln is connected to a sealed door cover, and the lower end surface of the door cover is sealed and connected to the feed inlet of the grate cooler.

2. The ceramsite roasting and firing system according to claim 1, characterized in that: The rotary expanded clay roasting kiln comprises a kiln body, the inner wall of which is provided with a refractory layer from the kiln head to the kiln tail, and is characterized in that: the kiln body is composed of a material blocking check zone and a rapid roasting zone from the feed end to the discharge section, a material feeding constriction is provided on the feed port side of the material blocking control zone, a material blocking boss is provided in the middle of the material blocking zone, and the rapid combustion zone is provided with three or more arch height parts with curved surface structures along the circumferential direction of the kiln body; and a discharge constriction is provided in the discharge section of the rapid roasting zone.

3. The rotary ceramsite roasting kiln according to claim 2, characterized in that: Both the inlet and outlet constrictions are provided with inward guide slopes.

4. The ceramsite roasting rotary kiln according to claim 2, characterized in that: The height of the material blocking boss is not greater than 1 / 2 of the height of the arched portion.

5. The ceramsite roasting and firing system according to claim 1, characterized in that: The rotary expanded clay roasting kiln comprises a kiln body, the inner wall of the kiln body is provided with a refractory layer from the kiln head to the kiln tail, the kiln body is provided with a preheating and denitrification zone, a shaping and control zone and a rapid calcination zone from the feeding end to the discharging section, the cross-sectional area in the kiln body decreases in sequence from the preheating and denitrification zone, the shaping and control zone and the rapid calcination zone, a plurality of annular protrusions are provided in the shaping and control zone along the axial direction of the kiln body for prolonging the residence time of the material and regulating the orderly release of the gas-generating substances inside the expanded clay, and a receiving groove for filling the active substance is formed between adjacent annular protrusions; the rapid combustion zone is provided with three or more arch height portions with curved surface structures along the circumferential direction of the kiln body.

6. The ceramsite roasting and firing system according to claim 5, characterized in that: The cross-sectional area of ​​the shaping and regulating zone is 70% to 80% of the cross-sectional area of ​​the preheating and denitrification zone; the cross-sectional area of ​​the rapid calcination zone is 50% to 60% of the cross-sectional area of ​​the preheating and denitrification zone.

7. The ceramsite roasting and firing system according to claim 3, characterized in that: The length of the kiln body is L; the length of the preheating and denitrification zone is less than or equal to 0.3L; the length of the shaping and regulating zone is 0.25 to 0.4L; and the length of the rapid calcination zone is 0.3 to 0.45L.

8. The ceramsite roasting and firing system according to claim 1, characterized in that: The distance between each two adjacent annular protrusions is 2-4 times the height of the annular protrusions, the height of each annular protrusion is 0.05-0.1 times the kiln radius, and the width of the root of the annular protrusion is 1-2.5 times the height.

9. The ceramsite roasting and firing system according to claim 1, characterized in that: The height of the annular protrusion is the same from the feeding direction to the discharging direction or increases linearly along the moving direction of the ceramsite.

10. The ceramsite roasting and firing system according to claim 2 or 3, characterized in that: The curve change of the arch height is y=x n function of , where n is any real number, n>0.

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