CN212476557U - Device for preparing magnesium phosphate cement by using medium-burned magnesium oxide - Google Patents
Device for preparing magnesium phosphate cement by using medium-burned magnesium oxide Download PDFInfo
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Abstract
The utility model relates to a device for preparing magnesium oxide for magnesium phosphate cement, a raw material bin of the device is communicated with a raw material preheating device, the raw material preheating device is communicated with a suspension state calcining furnace, the suspension state calcining furnace is communicated with a gas material separating device, the gas material separating device is communicated with a dust removing device, the gas material separating device is communicated with a transition bin and a product heat recovery device in turn, and the product heat recovery device is communicated with a product bin; the dust removal equipment is communicated with the raw material preheating device, the dust removal equipment is connected with the suspension state calcining furnace, the raw material preheating device is communicated with the waste gas treatment device, and the waste gas treatment device is respectively communicated with the smoke exhaust device and the suspension state calcining furnace; the product heat recovery device is communicated with the combustion furnace, and a charging structure is arranged between the combustion furnace and the suspension state calcining furnace. The utility model provides a current shaft furnace that adopts is main calcining equipment, need grind after calcining the completion, production cycle is long, and the energy consumption is high, the unstable problem of quality.
Description
Technical Field
The utility model relates to a building material additive field specifically relates to a device of middle-burning magnesium oxide for preparing magnesium phosphate cement.
Background
The Magnesium Phosphate Cement (MPC) is a novel cementing material which is coagulated and hardened based on the acid-base reaction of magnesium oxide and phosphate, has the characteristics of high coagulation speed, high early strength, good bonding performance, small drying shrinkage, wear resistance, freezing resistance and the like, and has good application prospect in the aspects of quick repair materials of engineering structures, refractory materials, biological adhesives, solidified heavy metals, radioactive wastes and the like.
The main raw materials for preparing magnesium phosphate cement are dead burned MgO, soluble phosphate, retarder, etc., wherein dead burned MgO is one of the most important raw materials of MPC, usually from magnesite (the main component is MgCO)3) The magnesium phosphate cement is prepared by grinding after high-temperature calcination at 1300-1700 ℃, the activity and specific surface area (fineness) of MgO have large influence on the performance of the MPC material, the higher the activity of MgO is, the faster the reaction speed of the magnesium phosphate cement is, the uncontrollable the setting time is, and the magnesium phosphate cement cannot be applied to engineering practice; the larger the specific surface area of MgO, the faster the coagulation and the higher the early strength, so the property of the magnesium oxide can be controlled by controlling the calcination process of the raw material magnesium oxide, and the purpose of controlling the property of the MPC material is achieved.
The prior production process flow generally takes blocky magnesite or pellets pressed by light-burned magnesia as raw materials, takes a shaft furnace as main calcining equipment, and grinds the raw materials after calcining, so that the production period is long, the energy consumption is high, the energy regulating capability is poor, the product is not uniformly calcined inside and outside, and the quality is unstable. Therefore, the construction of the efficient and stable production process has great practical significance.
SUMMERY OF THE UTILITY MODEL
Utility model purpose: the utility model provides a device of magnesium oxide burns in preparation magnesium phosphate cement is with, its aim at solve and have now to adopt the shaft furnace to be main calcining equipment, need grind after calcining the completion, production cycle is long, and the energy consumption is high, the unstable problem of quality.
The technical scheme is as follows:
a raw material bin of the device is communicated with a raw material preheating device through a material pipeline, the raw material preheating device is communicated with a suspension state calcining furnace through a material pipeline, the suspension state calcining furnace is communicated with a gas-material separating device through a gas-material pipeline, the gas-material separating device is communicated with a dust removing device through a gas-material pipeline, the gas-material separating device is sequentially communicated with a transition bin and a product heat recovery device through the material pipeline, and the product heat recovery device is communicated with a product bin; the dust removal equipment is communicated with the raw material preheating device through a gas pipeline, the dust removal equipment is converged with a material pipeline of the raw material preheating device through a material pipeline and is connected with the suspension state calcining furnace, the raw material preheating device is communicated with the waste gas treatment device through a gas pipeline, and the waste gas treatment device is respectively communicated with the smoke exhaust device and the suspension state calcining furnace through gas pipelines; the product heat recovery device is communicated with a combustion furnace integrally arranged below the suspension state calcining furnace, and a charging structure is arranged between the combustion furnace and the suspension state calcining furnace.
The dust removing equipment is metal film dust removing equipment.
The internal diameter of the feeding structure is a structure with two gradually expanded ends, the middle part of the feeding structure is communicated with a third gas pipeline, and the axis of the third gas pipeline is perpendicular to the axis of the feeding structure.
A combustion air fan is arranged on a pipeline for communicating the combustion air with the product heat recovery device; a combustion-supporting air valve is arranged on a pipeline of the product heat recovery device communicated with the combustion chamber; a secondary air valve and a secondary air fan are sequentially arranged on a gas pipeline communicated with the suspended state calcining furnace by the waste gas treatment device; a system fan and a flue gas valve are sequentially arranged on a gas pipeline communicated with the smoke exhaust device.
The gas material separation device comprises a primary recovery cyclone and a secondary recovery cyclone, the primary recovery cyclone is communicated with the suspension calcining furnace through a gas material pipeline, the primary recovery cyclone is communicated with the secondary recovery cyclone through a gas material pipeline, the secondary recovery cyclone is communicated with the metal film dust removal equipment through a gas material pipeline, and a material pipeline of the primary recovery cyclone and a material pipeline of the secondary recovery cyclone are converged and communicated with the product heat recovery device.
Raw materials preheating device and product heat recovery unit pile up by a plurality of heat transfer modules and constitute, and the heat transfer module is arranged in proper order by a plurality of heat transfer boards and is constituteed, forms the runner between the adjacent heat transfer board, and material and combustion air's runner sets up with alternating mode interval.
The two sides of the heat exchange plates are provided with bulges, the bulges on one side are arranged densely relatively, the bulges on one side are arranged sparsely relatively, and the bulges between the two adjacent heat exchange plates are arranged in a staggered manner.
The material and the combustion air are reversely mixed.
Has the advantages that:
a) the powder with small particle size and large specific surface area is adopted for calcination, the production period is short, and the product quality is uniform and stable.
b) The calcination temperature is between the light-calcined magnesia and the heavy-calcined magnesia, the activity of the product is lower than that of the light-calcined magnesia, and the requirement of preparing the heavy-calcined MgO for the magnesium phosphate cement is met.
c) After the raw materials are preheated by a preheating device, the temperature can be raised to 450-550 ℃; and part of the flue gas is taken as secondary air distribution and returned to the suspension calciner for adjusting the temperature and the air quantity of the flue gas, so that the energy consumption of the suspension calciner can be reduced.
d) The dividing wall type heat exchanger is used for cooling the materials, so that the materials are prevented from being mixed with gas, and the cooled materials can be directly discharged to a storage bin; meanwhile, combustion air is preheated to 100-200 ℃, the combustion temperature of the fuel is increased, and the energy consumption of the suspension calciner is reduced.
Drawings
FIG. 1 is a schematic view of a process for producing calcined magnesia by calcining light calcined magnesia in a suspended state;
FIG. 2 is a system diagram of the suspension calcination production device of the present invention;
FIG. 3 is a schematic front view of a heat exchanger used in the raw material preheating device and the product heat recovery device;
FIG. 4 is a schematic side view of a heat exchanger used in the raw material preheating apparatus and the product heat recovery apparatus;
FIG. 5 is a schematic diagram of a front structure of a heat exchange module;
FIG. 6 is a schematic side view of a heat exchange module;
FIG. 7 is a schematic view of a cross-sectional view A-A of a heat exchange module;
FIG. 8 is a schematic structural diagram of a throat feeding region in a suspension calciner.
Reference numerals: 1. a raw material bin, 1-1, a first material pipeline, 2, a raw material preheating device, 2-1, a first gas pipeline, 2-2, a second material pipeline, 3, a suspension calcining furnace, 3-1, a first gas pipeline, 4, a primary recovery cyclone, 4-1, a second gas pipeline, 4-2, a third material pipeline, 5, a secondary recovery cyclone, 5-1, a third gas pipeline, 5-2, a fourth material pipeline, 6, a metal film dust removal device, 6-1, a fifth material pipeline, 6-2, a second gas pipeline, 7, a waste gas treatment device, 7-1, a third gas pipeline, 7-2, a fourth gas pipeline, 8, a system fan, 9, a smoke valve, 10, a smoke exhaust device, 11, a transition bin, 12, a product heat recovery device, 13, a product bin, 14. the device comprises a combustion-supporting air fan, 15 combustion-supporting air valves, 16 combustion chambers, 17 secondary air valves, 18 secondary air fans, 19 gas inlets, 20 gas outlets, 21 material inlets, 22 material outlets, 23 feeding bins, 24 heat exchange modules, 25 heat exchange plates, 26 magnesium oxide powder flow channels, 27 gas flow channels, 27-1 holes, 28 and a feeding structure.
Detailed Description
The present invention will be further explained with reference to the accompanying drawings.
The utility model directly uses the light-burned magnesia powder as the raw material to be calcined in a suspended state, and the calcined magnesia powder is insulated. Considering that the raw material is powder, the particle size is small, the specific surface area is large, and the calcination product has the requirements of low activity and high specific surface area, so that the calcination temperature is between that of light-calcined magnesia and that of heavy-calcined magnesia, the activity of the product is lower than that of the light-calcined magnesia, and the magnesia produced under the process condition is called as medium-calcined magnesia.
The medium-calcined magnesia refers to magnesia with lower activity produced by calcining light-calcined magnesia under the calcining condition between light calcination and heavy calcination; the device comprises a raw material bin, a raw material preheating device, a suspension state calcining furnace, a gas-material separation device, a product heat recovery device, a fan system, metal film dust removal equipment, a waste gas treatment device, a product bin and the like; the light-burned magnesium oxide is sent into a raw material preheating device from a raw material bin, is preheated by high-temperature flue gas and then enters a suspension state calcining furnace for calcining, then enters a gas-material separation device, the separated high-temperature flue gas enters metal film dust removal equipment for dust fall, the flue gas after dust fall enters the raw material preheating device for preheating the raw material, the separated product enters a transition bin for heat preservation, and enters a product heat recovery device for preheating combustion-supporting air after heat preservation is completed; after the flue gas is treated by the preheated raw material and the flue gas, one part of the flue gas is introduced into the hearth to be used as secondary air, and the rest is discharged. Compare traditional magnesium phosphate magnesium oxide production method for cement, the utility model discloses the magnesium oxide of producing has low activity and high specific surface area's characteristics, need not to grind after calcining the completion, makes the production cycle of preparation magnesium phosphate cement short, the adjustable performance is good, product quality is stable, waste heat utilization rate is high.
As shown in figure 2, a device for preparing magnesium oxide from magnesium phosphate cement by intermediate burning, a raw material bin 1 of the device is communicated with a raw material preheating device 2 through a first material pipeline 1-1, the raw material preheating device 2 is communicated with an exhaust gas treatment device 7 through a first gas pipeline 2-1, the raw material preheating device 2 is communicated with a suspension state calcining furnace 3 through a second material pipeline 2-2, the suspension state calcining furnace 3 is communicated with a gas-material separation device through a first gas pipeline 3-1, the gas-material separation device is communicated with a metal film dust removal device 6 through a third gas pipeline 5-1, the gas-material separation device is communicated with a transition bin 11 and a product heat recovery device 12 in sequence through a third material pipeline 4-2, and the product heat recovery device 12 is communicated with a product bin 13; the waste gas treatment device 7 is respectively communicated with the suspension calciner 3 and the smoke exhaust device 10; the combustion-supporting air is communicated with a combustion furnace 16 integrally arranged below the suspension state calcining furnace 3 through a product heat recovery device 12, and a charging structure 28 is arranged between the combustion furnace 16 and the suspension state calcining furnace 3.
The temperature of the flue gas and the temperature of the materials discharged from the suspension calciner are controlled by adjusting the mass flow ratio of the material feeding amount and the high-temperature flue gas;
a combustion air fan 14 is arranged on a gas pipeline for communicating combustion air with the product heat recovery device 12 and provides power for the combustion air to enter a combustion chamber 16;
a combustion air valve 15 is arranged on a gas pipeline of the product heat recovery device 12 communicated with the combustion chamber 8, and the combustion air valve 15 controls the amount of air entering the product heat recovery device 12 by changing the opening degree of the valve, so that the amount of combustion air and the preheating temperature of the combustion air are adjusted according to the actual production requirement.
And a secondary air valve 17 and a secondary air fan 18 are sequentially arranged on a gas pipeline communicated with the suspension calciner 7 by the waste gas treatment device 16 and are used for adjusting the flow of returned flue gas so as to achieve the effects of controlling the temperature of the suspension calciner and the flow rate of gas in the suspension calciner.
A system fan 8 and a flue gas valve 9 are sequentially arranged on a gas pipeline communicated with the exhaust device 10 of the waste gas treatment device 7, the flue gas valve 8 is used for controlling the flow of flue gas exhausted from the system, and is matched with the secondary air valve 9 to control the flow of the returned flue gas, so that the pressure in the system is kept stable.
The combustion air fan 14, the secondary air fan 18 and the system fan 8 jointly form a fan system of the device, and the system fan 8 is used for maintaining a negative pressure environment in the whole system and guaranteeing the flow speed of flue gas and the flow direction among all devices; the combustion air fan 14 is responsible for blowing air into the combustion chamber to ensure the normal operation of combustion; the secondary air fan 18 is used for overcoming the pressure difference between the suspension calciner 3 and the waste gas treatment device 7, which is generated by the loss along the way and the loss of each device, and ensuring that the flue gas can flow back into the suspension calciner 3.
As shown in fig. 8, the suspension state calciner 3 is respectively a refractory material a, a thermal insulation material B, a brick structure C and a steel structure D from inside to outside, the bottom of the suspension calciner 3 is provided with a charging structure 28, the inner diameter of the charging structure 28 is a structure with two gradually expanding ends, the effect of changing the inner diameter is achieved by changing the thickness of the filled thermal insulation material B, a third gas pipeline 7-1, namely a secondary air pipeline, is arranged at the position with the smallest inner diameter of the charging structure 28, namely the throat, preferably, the diameter of the throat is half of the diameter of the main furnace, when the flue gas flow rate and the local negative pressure are increased, the occurrence of material blockage can be avoided, and the degree of the gradually expanding ends of the inner diameter can achieve. A combustion chamber 16 is connected below the throat. The axis of the third gas pipeline 7-1 is vertical to the axis of the suspension state calcining furnace and is communicated with the interior of the suspension state calcining furnace 3; a material outlet pipe second material pipeline 2-2 of the raw material preheating device 2 and a material outlet pipe fifth material pipeline 6-1 of the metal film dust removing equipment 6 are converged and vertically downwards converged into a third gas pipeline 7-1; the materials enter under the push of secondary air and move to the suspension state calcining furnace, meanwhile, the suspension state calcining furnace 3 is in a negative pressure state, and the materials are sucked into the calcining furnace under the action of the negative pressure. The design that the diameter of the furnace is reduced at the throat part increases the flow velocity of the smoke at the throat part, enhances the entrainment effect on the materials, enhances the mixing effect of the materials and the smoke, fully breaks up the fuel, and ensures that the product quality is more uniform.
The gas material separation device comprises a primary recovery cyclone 4 and a secondary recovery cyclone 5, wherein the primary recovery cyclone 4 is communicated with the suspension calciner 3 through a first gas material pipeline 3-1, the primary recovery cyclone 4 is communicated with the secondary recovery cyclone 5 through a second gas material pipeline 4-1, the secondary recovery cyclone 5 is communicated with the metal film dust removal equipment 6 through a third gas material pipeline 5-1, and a third material pipeline 4-2 of the primary recovery cyclone 4 and a fourth material pipeline 5-2 of the secondary recovery cyclone 5 are converged and communicated with the transition bin 11.
As shown in fig. 3-7, the raw material preheating device 2 and the product heat recovery device 12 are both of a dividing wall type heat exchanger structure, the heat exchange working mediums are respectively high-temperature flue gas-raw material and combustion air-high temperature product, the heat exchangers used by the two devices are formed by stacking a plurality of heat exchange modules 24 along the gravity direction, the shell of each heat exchange module 24 is a square box body without cover and bottom, a plurality of heat exchange plates 25 are vertically arranged in the box body according to the designed interval, different heat exchange plates 25 are parallel to each other, preferably, an even number of heat exchange plates 25 are arranged in pairs relatively, as shown in fig. 6, two adjacent heat exchange plates 25 form a flow channel to pass through the material or gas, the flow channels of the material and the gas are alternately arranged at intervals, namely, the flow channels of the material-gas-material- … …' are alternately arranged at intervals, the heat exchange effect is enhanced. As shown in fig. 5-7, the formed material flow channel is through from top to bottom, the gas flow channel is closed from top to bottom, and the bottom and the top side of the gas flow channel are both provided with holes 27-1 for gas blowing in and discharging. The heat exchange plate 25 and the shell of the heat exchange module 24 are tightly welded together, so that the air tightness of the gas flow channel is ensured, and the condition that gas or powder escapes (overflows) to an adjacent material flow channel is avoided. The length of the heat exchange plate 25 in the vertical direction is slightly lower than the height of the shell of the heat exchange module 24, so that the heat exchange plate 25 and the corresponding flow channel can be protected by the shell of the heat exchange module 24, and the installation is convenient.
As shown in fig. 6, the two sides of the heat exchange plate 25 are provided with protrusions, one side is provided with relatively dense protrusions, one side is provided with relatively sparse protrusions, and the protrusions between two adjacent heat exchange plates 25 are arranged in a staggered manner. The cross section of the flow channel between two adjacent heat exchange plates 25 is rectangular. The bulges are used for increasing the contact area of the heat exchange plate 25 and materials or gas and improving the heat exchange effect, wherein the bulges arranged on the inner wall of the light-burned magnesia powder flow passage 26 for circulating the materials are fewer, so that the influence of the bulges on the circulation of the materials is avoided; the bulges arranged on the inner wall of the gas flow channel 27 for circulating combustion air or high-temperature flue gas are more, the influence of the bulges on the gas is small and can be ignored, and the surface area of the heat exchange plate 25 which can be contacted with the gas can be increased as much as possible, so that the heat exchange is facilitated.
The gas inlet 19 and the gas outlet 20 are cylindrical, one side of the cylinder is provided with a row of circular tubular interfaces, and the interfaces are connected with a hole 27-1 formed in a gas flow passage 27; cold air enters and fills the cylinder of the gas inlet 19 under the pushing of the combustion air fan 14, then enters the gas flow channel 27 from the opening 27-1 along the pipeline under the action of the fan and completes the heat exchange with the material, and then the air enters the gas flow channel 27 corresponding to the heat exchange module arranged above the heat exchange module from the opening 27-1 at the upper part of the gas flow channel 27 along the U-shaped pipe; for the uppermost heat exchange module 24, air will pass from the upper opening 27-1 along the tube into the cylinder of the gas outlet 20; similarly, under the negative pressure caused by the suction of the system fan 8, the high-temperature flue gas enters the heat exchange module 24 from the gas inlet 19 along the pipeline through the opening 27-1 of the gas flow channel 27 to preheat the raw material, then enters the gas flow channel of the heat exchange module arranged above through the opening 27-1 at the top of the gas flow channel 27 along the U-shaped pipe, and enters the gas outlet 20 for the heat exchange module 24 at the uppermost layer.
The plurality of heat exchange modules 24 are connected in series in sequence, specifically, the heat exchange module 24 at the lowest layer is connected with the gas inlet 19 through a pipeline through an opening 27-1 at the bottom of the gas flow channel 27, the heat exchange module 24 at the uppermost layer is communicated with the air hot side outlet 20 through an opening 27-1 at the top of the gas flow channel 27, and between the adjacent heat exchange modules 24, the opening 27-1 at the top of the pre-gas flow channel 27 of the heat exchange module 24 at the lower side is connected with the opening 27-1 at the bottom of the gas flow channel 27 of the heat exchange module 24 at the upper side through a U-shaped pipeline, so that the two adjacent heat exchange modules 24 are penetrated.
The whole heat exchanger is formed by stacking a feeding hole 21, a feeding bin 23, a heat exchange module 24 and a discharging hole 22 from top to bottom in sequence, the cross sections of the bottom of the feeding bin 23, the heat exchange module 24 and the upper part of the discharging hole 22 are the same in shape and are hermetically connected through flanges to form a whole, the feeding hole 21 of the raw material preheating device 2 is communicated with the discharging hole of the raw material bin 1, and the discharging hole 22 is communicated with the feeding hole of the suspension calciner 3; the feed inlet 21 of the product heat recovery device 12 is communicated with the discharge outlet of the transition bin 11, and the discharge outlet 22 is communicated with the product bin 13. The whole device is fixed on an additional steel frame to ensure the stability of the device.
The material and the combustion air adopt a counter-flow type, namely the material enters from the upper part of the heat exchanger, the material is discharged from the lower part, the combustion air enters from the lower part and is discharged from the upper part, and the two working media are not in direct contact, so the material cannot permeate into the combustion air.
Product heat recovery unit piles up along vertical direction by a plurality of heat transfer modules and constitutes, if output is great or the product temperature after keeping warm is higher, then can increase the heat transfer requirement of quantity in order to reach the design of heat transfer module.
Before entering the raw material preheating device 2, the high-temperature flue gas needs to be subjected to dust reduction treatment in order to avoid blockage caused by long-term use of a gas flow passage in the raw material preheating device 2 due to high dust content. Considering the higher temperature of the flue gas, a rigid metal film is adopted as dust settling equipment, the use temperature is as high as 800 ℃, and the dust content at the outlet is lower than 5mg/Nm3。
As shown in fig. 1, a process for preparing calcined magnesia for magnesium phosphate cement comprises a preheating process, a calcining process, a cyclone separation process, a heat preservation process and a waste heat recovery process:
a preheating procedure: the raw material preheating device 2 is a raw material preheating heat exchanger in the form of a dividing wall type heat exchanger, the raw material preheating device 2 preheats the light-burned magnesium oxide raw material from normal temperature to 450-550 ℃ through the heat exchange between high-temperature flue gas (high-temperature flue gas separated by a cyclone separation process) and low-temperature material (light-burned magnesium oxide raw material), the temperature of the raw material entering a calcining furnace is increased, the fuel consumption is reduced, and compared with the existing cyclone barrel type preheating equipment, the dust content of the flue gas subjected to metal film dust removal after the material preheating is not increased again, dust removal is not needed, and the flue gas can directly enter the waste gas treatment device 7; after the heat-exchanged high-temperature flue gas is treated by the waste gas treatment device 7, part of the high-temperature flue gas enters a calcining process as secondary air, namely the high-temperature flue gas is provided in the suspension calciner 3 and used for adjusting the temperature of the suspension calciner and auxiliary materials enter the suspension calciner 3, and part of the high-temperature flue gas is discharged through a smoke exhaust device 10.
A calcination process: regulating the temperature and the gas flow rate of the flue gas entering the suspension calciner 3 by controlling the supply amount of fuel and the supply amount of secondary air, then controlling the technological parameters of calcination, and carrying out suspension calcination on the preheated raw material at the calcination temperature of 1400-1600 ℃ for 2-4 s to obtain a calcined product with low activity, namely discharging the high-temperature flue gas carrying the calcined magnesia; because the raw material is powder, the particle size is small, the specific surface area is large, and the calcination product has the requirements of low activity and high specific surface area, the calcination temperature is between that of light-calcined magnesia and that of heavy-calcined magnesia, and the activity of the product is lower than that of the light-calcined magnesia.
A cyclone separation process: the high-temperature flue gas with magnesium oxide discharged in the calcining process enters a cyclone separation process, namely a multi-stage recovery cyclone, the high-temperature flue gas with magnesium oxide is separated to obtain high-temperature flue gas with a small amount of magnesium oxide and calcined magnesium oxide, the high-temperature flue gas with a small amount of magnesium oxide enters metal film dust removing equipment 6 through the multi-stage recovery cyclone, and the high-temperature flue gas passing through the metal film dust removing equipment 6 enters a preheating process, namely a raw material preheating device 2, so that the temperature of the raw material is increased; and (3) the calcined magnesia in the separated product enters a heat preservation procedure, namely enters a transition bin 11 for heat preservation.
A heat preservation procedure: and preserving the heat of the magnesium oxide discharged by the cyclone separation process for 0.5-2 h, and enabling the preserved medium-fired magnesium oxide material to enter a waste heat recovery process.
A waste heat recovery process: the heat-insulated medium-burned magnesia material enters the product heat recovery device 12, and the waste heat of the medium-burned magnesia material and combustion air complete heat exchange in the product heat recovery device 12. So as to improve the temperature of the combustion air, the temperature of the material entering the product heat recovery device 12 is more than 800 ℃, the temperature after heat exchange is 250-350 ℃, and the combustion air is preheated to 100-200 ℃ from the room temperature. Namely, the waste heat of the magnesium oxide is reasonably utilized by the product heat recovery device, the temperature of the magnesium oxide product is reduced, and the temperature of combustion air is increased.
Finally, the heat-insulated magnesium oxide enters a product bin 13 to prepare a finished product of the medium-calcined magnesium oxide with low activity and high specific surface area for the magnesium phosphate cement. Compared with the traditional procedures of light-burned magnesia ball pressing, pellet shaft furnace heavy burning and fine grinding, the production procedure is simplified; compared with the shaft furnace for roasting the magnesium oxide pellets, the production time of the suspension calciner 3 is greatly reduced; compared with the method for roasting the pellets, the method for directly roasting the magnesium oxide powder raw material has the advantages of lower temperature, reduced energy consumption and more uniform roasting.
The high-temperature flue gas generated in the calcining process enters a cyclone separation process to separate the high-temperature flue gas from magnesium oxide (primary recovery cyclone 4 and secondary recovery cyclone 5), then enters metal film dust removal equipment 6 to reduce dust, then enters a preheating process to preheat materials, the flue gas enters a waste gas treatment device to be treated to reach the standard after the materials are preheated, and finally part of the flue gas enters the calcining process and part of the flue gas is discharged.
In the calcining procedure, the temperature of the flue gas and the temperature of the material out of the suspension calcining furnace are controlled by changing the mass flow ratio of the material feeding amount to the high-temperature flue gas, wherein the material feeding amount is as follows: the mass flow mass ratio of the flue gas is 1: 1.5-1: 2, so that the raw materials are calcined at the calcining temperature of 1400-1600 ℃.
The combustion air is preheated to 100-200 ℃ through the heat exchange process, the combustion temperature of the fuel entering the combustion chamber 8 is increased, and the fuel enters the calcining process.
Example 1
The working process of the materials and the gas is described by combining the process and the device as follows:
light-burned magnesia powder in the raw material bin 1 enters the raw material preheating device 2 through conveying equipment to be preheated by smoke, the preheated raw material descends along a pipeline and is converged with powder intercepted by the metal dust removal equipment 6, and the preheated raw material enters the suspension calciner 3 under the action of secondary air entrainment and negative pressure in the suspension calciner 3; the light calcined magnesia is heated, calcined and densified in the suspension calciner 3, then enters a primary recovery cyclone 4 and a secondary recovery cyclone 5 in sequence for gas-material separation, the separated materials enter a transition bin 11 for heat preservation, the materials after heat preservation enter a product heat recovery device 12 for preheating combustion air, and the cooled materials enter a product bin 13.
Combustion-supporting air is blown into the system by a combustion-supporting air fan 14, is preheated by heat-insulated magnesium oxide in the product heat recovery device 12, enters a combustion chamber 16 to be mixed with fuel and then is combusted to generate high-temperature flue gas, the flue gas enters the suspension calciner 3 to provide heat for the calcination process, the flue gas is discharged out of the suspension calciner 3 from a gas material outlet pipe, the dust content is obviously reduced after passing through a primary recovery cyclone 4 and a secondary recovery cyclone 5 in sequence, and the flue gas enters the raw material preheating device 2 to complete the preheating of the raw material after entering the metal film dust removal equipment 6 to reduce dust; after the flue gas after preheating the raw materials is treated by the waste gas treatment device 7, one part of the flue gas enters the smoke exhaust device 10 (chimney) through the system fan 8, and the other part of the flue gas returns to the suspension calciner 3 through the secondary air fan 18 to be used as secondary air.
The specific material flow is as follows: the method comprises the steps that materials in a raw material bin 1 enter a raw material preheating device 2 through a first material pipeline 1-1 and are preheated by smoke after dust is reduced by metal film dust removing equipment 6, the preheated materials are converged with materials intercepted from the metal film dust removing equipment 6 through a fifth material pipeline 6-1 through a second material pipeline, then enter a suspension state calcining furnace 3 through pipelines under the pushing action of secondary air and the negative pressure action of the suspension state calcining furnace, the calcined products enter a multi-stage recycling cyclone device through a first gas pipeline 3-1, firstly the products enter a primary recycling cyclone 4 through the first gas pipeline 3-1 and then enter a secondary recycling cyclone 5 through a second gas pipeline 4-1, after the primary recycling cyclone 4 and the secondary recycling cyclone 5 are separated, the dust content is remarkably reduced, magnesium oxide enters a transition bin 11 through a third material pipeline 4-2 for heat preservation, then the magnesium oxide enters a product heat recovery device 12, and after heat exchange and heat preservation, the magnesium oxide enters a product bin 13. And finishing the preparation of the finished product of the medium-burned magnesium oxide for the magnesium phosphate cement.
The specific gas flow is as follows: combustion-supporting gas enters the product heat recovery device 12 to exchange heat with the heat-insulating magnesium oxide under the action of the combustion-supporting air fan 14, the temperature of the combustion-supporting gas is preheated by using the waste heat of the magnesium oxide, and then the combustion-supporting gas enters the combustion chamber 16, so that the theoretical combustion temperature of fuel is increased, and the energy consumption is reduced. After the material is suspended and calcined in a suspension calciner 3, the calcined product enters a multi-stage recovery cyclone device through a first gas material pipeline 3-1, the calcined product firstly enters a primary recovery cyclone 4 through the first gas material pipeline 3-1, after the gas material separation of the primary recovery cyclone 4, high-temperature flue gas with a small amount of magnesium oxide enters a secondary recovery cyclone 5 through a second gas material pipeline 4-1, after the separation of the secondary recovery cyclone 5, the high-temperature flue gas enters a metal film dust removal device 6 through a third gas material pipeline 5-1 for dust removal, then the high-temperature flue gas enters a raw material preheating device 2 through a second gas pipeline 6-2 for preheating the raw material, the temperature of the flue gas after preheating the raw material is obviously reduced, then the flue gas enters an exhaust gas treatment device 7 through a first gas pipeline 2-1, part of the gas discharged by the exhaust gas treatment device 7 enters the suspension calciner 3 as secondary air through a third gas pipeline 7-1, the secondary air is used for adjusting the temperature and the air quantity of the flue gas, and part of the gas is communicated with the smoke exhaust device 10 through a fourth gas pipeline 7-2 to exhaust the smoke.
In the embodiment, the preheating temperature of combustion air is 150 ℃, the temperature of secondary air is 300 ℃, and fuel is not preheated.
Natural gas is adopted (calculated according to third party detection data, the lower heating value is 36000kJ/Nm3) As fuel, 1Nm per combustion3The actual required air amount of the natural gas is 10.85Nm3Yield 11.88Nm3The combustion products of (1). Under the preheat conditions of this example, the theoretical combustion temperature was 1950 deg.C, and the outlet burner flue gas temperature was 1658 deg.C, taking into account heat losses. The secondary air coefficient is 0.262, corresponding to a flow of 3.12Nm3/Nm3That is, the temperature of the gas in the furnace is guaranteed to be 1400 ℃, and each combustion time is 1Nm3The amount of the flue gas to be refluxed is 3.12Nm3。
In this embodiment, the waste heat recovery amount and the corresponding ratio of each waste heat recovery device are shown in table 1, for example, the first column in the table is a waste heat recovery link (device) in the system; the second column is the heat recycled by a waste heat recycling link (device) when unit fuel is consumed; the third column is the proportion (heat exchange quantity/low-level heating quantity) of the heat quantity recovered by each link (device) relative to the low-level heating quantity of the fuel. For a device system with annual output of 30000t, the recovery amount of waste heat is about 1.94 multiplied by 104MJ/year, corresponding to the use of 16.3% of the energy contained in the fuel, with a return flow of flue gases recovering heat of 4.75X 103MJ/year, accounting for 24.6% of total recovery amount, and the product waste heat recovery device recovers 6.05 × 10% of heat3MJ/year, accounting for 31.3% of total recovery amount, and the raw material multi-stage preheating device recovers 8.55 × 10 heat3MJ/year, accounting for 44.1% of the total recovery.
TABLE 1 the utility model discloses the waste heat recovery condition of each waste heat utilization link (device)
Claims (8)
1. The device for preparing the medium-burned magnesium oxide for the magnesium phosphate cement is characterized in that: a raw material bin (1) of the device is communicated with a raw material preheating device (2) through a material pipeline, the raw material preheating device (2) is communicated with a suspension state calcining furnace (3) through a material pipeline, the suspension state calcining furnace (3) is communicated with a gas-material separating device through a gas-material pipeline, the gas-material separating device is communicated with a dust removing device through a gas-material pipeline, the gas-material separating device is sequentially communicated with a transition bin (11) and a product heat recovery device (12) through the material pipeline, and the product heat recovery device (12) is communicated with a product bin (13); the dust removal equipment is communicated with the raw material preheating device (2) through a gas pipeline, the dust removal equipment is converged with a material pipeline of the raw material preheating device (2) through a material pipeline and is connected with the suspension state calcining furnace (3), the raw material preheating device (2) is communicated with the waste gas treatment device (7) through a gas pipeline, and the waste gas treatment device (7) is respectively communicated with the smoke exhaust device (10) and the suspension state calcining furnace (3) through gas pipelines; the product heat recovery device (12) is communicated with a combustion chamber (16) which is integrally arranged below the suspension state calcining furnace (3), and a charging structure (28) is arranged between the combustion chamber (16) and the suspension state calcining furnace (3).
2. The apparatus for producing mid-burned magnesium oxide for magnesium phosphate cement according to claim 1, wherein: the dust removing equipment is metal film dust removing equipment (6).
3. The apparatus for producing mid-burned magnesium oxide for magnesium phosphate cement according to claim 1, wherein: the inner diameter of the feeding structure (28) is a structure with two gradually-expanded ends, the middle part of the feeding structure (28) is communicated with a third gas pipeline (7-1), and the axis of the third gas pipeline (7-1) is vertical to the axis of the feeding structure (28).
4. The apparatus for producing mid-burned magnesium oxide for magnesium phosphate cement according to claim 1, wherein: a combustion air fan (14) is arranged on a pipeline for communicating the combustion air with the product heat recovery device (12); a combustion-supporting air valve (15) is arranged on a pipeline of the product heat recovery device (12) communicated with the combustion chamber (16); a secondary air valve (17) and a secondary air fan (18) are sequentially arranged on a gas pipeline communicated with the suspension state calcining furnace (3) by the waste gas treatment device (7); a system fan (8) and a flue gas valve (9) are sequentially arranged on a gas pipeline communicated with the exhaust gas treatment device (7) and the smoke exhaust device (10).
5. The apparatus for producing mid-burned magnesium oxide for magnesium phosphate cement according to claim 1, wherein: the gas material separation device comprises a primary recovery cyclone (4) and a secondary recovery cyclone (5), the primary recovery cyclone (4) is communicated with the suspension state calcining furnace (3) through a gas material pipeline, the primary recovery cyclone (4) is communicated with the secondary recovery cyclone (5) through a gas material pipeline, the secondary recovery cyclone (5) is communicated with the metal film dust removal equipment (6) through a gas material pipeline, and a material pipeline of the primary recovery cyclone (4) and a material pipeline of the secondary recovery cyclone (5) are converged and communicated with the product heat recovery device (12).
6. The apparatus for producing mid-burned magnesium oxide for magnesium phosphate cement according to claim 1, wherein: raw materials preheating device (2) and product heat recovery unit (12) are piled up by a plurality of heat transfer module (24) and are constituteed, and heat transfer module (24) are arranged in proper order by a plurality of heat transfer board (25) and are constituteed, form the runner between adjacent heat transfer board (25), and the runner of material and combustion air sets up with alternating mode interval.
7. The apparatus for producing mid-burned magnesia for magnesium phosphate cement according to claim 6, wherein: the two sides of the heat exchange plates (25) are provided with bulges, the bulges on one side are arranged densely relatively, the bulges on one side are arranged sparsely relatively, and the bulges between the two adjacent heat exchange plates (25) are arranged in a staggered manner.
8. The apparatus for producing mid-burned magnesia for magnesium phosphate cement according to claim 6, wherein: the material and the combustion air adopt a counter-flow mode.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111825351A (en) * | 2020-08-20 | 2020-10-27 | 辽宁圣世资源环境科技有限公司 | Device and process for preparing calcined magnesium oxide for magnesium phosphate cement |
| CN113899220A (en) * | 2021-10-21 | 2022-01-07 | 榆林学院 | Magnesium slag waste heat utilization system |
-
2020
- 2020-08-20 CN CN202021747064.5U patent/CN212476557U/en active Active
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111825351A (en) * | 2020-08-20 | 2020-10-27 | 辽宁圣世资源环境科技有限公司 | Device and process for preparing calcined magnesium oxide for magnesium phosphate cement |
| CN111825351B (en) * | 2020-08-20 | 2023-10-27 | 辽宁东大粉体工程技术有限公司 | Device and process for preparing middle-burned magnesia for magnesium phosphate cement |
| CN113899220A (en) * | 2021-10-21 | 2022-01-07 | 榆林学院 | Magnesium slag waste heat utilization system |
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Effective date of registration: 20230918 Address after: No.19 Caita Street, Shenhe District, Shenyang, Liaoning 110069 Patentee after: LIAONING NORTHEAST UNIVERSITY POWDER PROJECT TECHNOLOGY CO.,LTD. Address before: 110027 No.20, 4th Street, economic and Technological Development Zone, Tiexi District, Shenyang City, Liaoning Province Patentee before: Liaoning Shengshi resources and Environment Technology Co.,Ltd. |