Energy-saving aluminum hydroxide suspension roasting device and roasting method thereof

Abstract

The invention discloses an energy-saving aluminum hydroxide suspension roasting device and a roasting method thereof. The energy-saving aluminum hydroxide suspension roasting device comprises a cooling assembly, a preheating assembly, a suspension roasting furnace, an SCR reactor, a dryer, a feeding assembly, an exhaust emission assembly and a heat supply device. The cooling assembly comprises a fourth-stage cyclone cooler, a third-stage cyclone cooler, a second-stage cyclone cooler and a first-stage cyclone cooler which are connected in sequence, and an air outlet of the first-stage cyclone cooler is communicated with an inlet of the suspension roasting furnace; the preheating assembly comprises a third-stage preheater, a second-stage preheater, a first-stage preheater and a first-stage preheater which are sequentially connected, the suspension roaster is communicated with the third-stage preheater, the first-stage preheater is communicated with the SCR reactor, the SCR reactor is communicated with the dryer, the dryer is communicated with the first-stage preheater, and the first-stage preheater is communicated with the waste gas emission assembly; the heat supply device can provide heat for the SCR reactor. The heat energy loss can be reduced.

Description

Technical Field

[0001] The invention relates to the technical field of aluminum hydroxide roasting furnaces, and in particular to an energy-saving aluminum hydroxide suspension roasting device and a roasting method thereof. Background Art

[0002] In the industry of producing alumina by roasting aluminum hydroxide, vertical furnaces, rotary kilns, and boiling furnaces have been used, but their heat consumption is very high. In recent decades, aluminum hydroxide suspension roasting furnaces have been used, and the lowest heat consumption per ton of alumina can only be 2.75GJ. Faced with increasingly fierce competition, reducing heat consumption is the basis for the survival of enterprises.

[0003] The existing patent No. 200910012849.X discloses "aluminum hydroxide suspension roasting furnace and its layout in the production plant", including an aluminum hydroxide feeding mechanism consisting of a feeding bin, an electronic quantitative feeder and a spiral feeder, a venturi dryer, a suspension roasting mechanism consisting of a first, second and third stage cyclone preheater and a suspension roasting furnace, a first, second, third and fourth stage cyclone cooler, a fluidized cooler, a dust collection and dust return mechanism, and a U-shaped connecting pipe and connecting pipeline. The spiral feeder is connected to the venturi dryer, the first stage cyclone preheater is connected to the discharge end of the venturi dryer, the discharge end of the second stage cyclone preheater is connected to the feed end of the suspension roasting furnace, the discharge end of the suspension roasting furnace is connected to the feed end of the second stage cyclone preheater, the third stage cyclone preheater is connected to the U-shaped connecting pipe, and the U-shaped connecting pipe is connected to the first stage cyclone cooler and the second stage cyclone cooler. The first-stage cyclone preheater is connected to the dust collecting electrostatic precipitator, the exhaust is sent to the chimney by the blower, the dust is returned to the production process by the Roots blower, and is released by the pipeline ash discharge valve. The whole set of roasting furnace is arranged in a six-story factory building. The invention has the advantages of compact structure, low energy consumption, high degree of automation, and large single machine output.

[0004] However, since only one secondary cyclone preheater is provided in the above-mentioned prior art, the material from the primary cyclone preheater enters the suspension roasting furnace after only one heat exchange, and at the same time, the hot air transported from the secondary cyclone preheater to the venturi dryer is also cooled only once by the secondary cyclone preheater, so the flue gas finally discharged from the chimney is relatively high, resulting in heat waste and poor energy saving effect.

[0005] Therefore, the art is in urgent need of an energy-saving aluminum hydroxide suspension roasting device and a roasting method thereof to solve the above-mentioned problems. Summary of the invention

[0006] The purpose of the present invention is to provide an energy-saving aluminum hydroxide suspension roasting device and a roasting method thereof to solve the problems existing in the above-mentioned prior art, which can effectively reduce heat loss and thus achieve the technical effect of energy saving.

[0007] To achieve the above object, the present invention provides the following solutions:

[0008] The invention discloses an energy-saving aluminum hydroxide suspension roasting device, comprising a cooling component, a preheating component, a suspension roasting furnace, an SCR reactor, a dryer, a feeding component, an exhaust gas emission component and a heat supply device;

[0009] The cooling assembly comprises a four-stage cyclone cooler, a three-stage cyclone cooler, a two-stage cyclone cooler and a one-stage cyclone cooler, the inlet of the four-stage cyclone cooler is connected to the outside atmosphere, the air outlet of the four-stage cyclone cooler is connected to the inlet of the three-stage cyclone cooler, the air outlet of the three-stage cyclone cooler is connected to the inlet of the two-stage cyclone cooler, the air outlet of the two-stage cyclone cooler is connected to the inlet of the one-stage cyclone cooler, and the air outlet of the one-stage cyclone cooler is connected to the inlet of the suspension roasting furnace; the discharge port of the one-stage cyclone cooler is connected to the inlet of the two-stage cyclone cooler, the discharge port of the two-stage cyclone cooler is connected to the inlet of the three-stage cyclone cooler, and the discharge port of the three-stage cyclone cooler is connected to the inlet of the four-stage cyclone cooler;

[0010] The preheating assembly includes a three-stage preheater, a two-stage preheater, a one-stage preheater and a first-stage preheater, the gas outlet of the suspension roasting furnace is connected to the inlet of the three-stage preheater, the gas outlet of the three-stage preheater is connected to the inlet of the two-stage preheater, the gas outlet of the two-stage preheater is connected to the inlet of the one-stage preheater, the gas outlet of the one-stage preheater is connected to the inlet of the SCR reactor, the gas outlet of the SCR reactor is connected to the inlet of the dryer, the outlet of the dryer is connected to the inlet of the first-stage preheater, and the gas outlet of the first-stage preheater is connected to the exhaust gas emission assembly; the discharge port of the first-stage preheater is connected to the inlet of the one-stage preheater, the discharge port of the one-stage preheater is connected to the inlet of the two-stage preheater, the discharge port of the two-stage preheater is connected to the inlet of the suspension roasting furnace, and the discharge port of the suspension roasting furnace is connected to the inlet of the three-stage preheater;

[0011] The heat supply device can provide heat for the SCR reactor.

[0012] Preferably, the cooling assembly further comprises an indirect cooler, and the discharge port of the four-stage cyclone cooler is connected to the inlet port of the indirect cooler.

[0013] Preferably, the exhaust gas emission component includes a dust collector, an induced draft fan and a chimney, the inlet of the dust collector is connected to the air outlet of the first-stage preheater, the air outlet of the dust collector is connected to the chimney, and the induced draft fan is arranged on the pipeline between the dust collector and the chimney.

[0014] Preferably, an ash return device is provided at the ash outlet end of the dust collector, and the ash outlet of the ash return device is connected to the inlet of the primary cyclone cooler.

[0015] Preferably, the feeding assembly includes a raw material bin, a weighing scale and a feeder, the weighing scale is arranged below the discharge port of the raw material bin, the output end of the weighing scale is connected to the feed end of the feeder, and the discharge end of the feeder is connected to the inlet of the dryer.

[0016] Preferably, the discharge port of the feeder is connected to the dryer through two parallel feed conveying pipelines;

[0017] The discharge port of the first-stage preheater is provided with two first-stage material conveying pipelines, and one end of the two first-stage material conveying pipelines away from the first-stage preheater is connected to the inlet of the first-stage preheater;

[0018] The discharge port of the secondary preheater is provided with two secondary material conveying pipelines, and one end of the two secondary material conveying pipelines away from the secondary preheater is connected to the feed port of the suspension roasting furnace.

[0019] Preferably, two first-stage preheaters are provided.

[0020] Preferably, a retention tank is provided between the discharge port of the third-stage preheater and the inlet of the first-stage cyclone cooler.

[0021] Preferably, the heat supply device is a drying station;

[0022] A cooling jacket is provided on the outer wall of the three-stage cyclone cooler, and an air outlet of the cooling jacket is connected to the dryer station through a pipeline.

[0023] The invention discloses a roasting method of an energy-saving aluminum hydroxide suspension roasting device, comprising the following steps:

[0024] Step 1: Start the induced draft fan and dust collector, so that the cold air enters the fourth-stage cyclone cooler, the third-stage cyclone cooler, the second-stage cyclone cooler, the first-stage cyclone cooler, the suspension roaster, the third-stage preheater, the second-stage preheater, the first-stage preheater, the SCR reactor, the dryer, the first-stage preheater, the dust collector, the induced draft fan and the chimney in sequence, and then is discharged into the atmosphere;

[0025] Step 2: Adjust the air volume of the induced draft fan to adjust the negative pressure of the suspension roasting furnace to a pressure suitable for ignition, start the first burner, and when the temperature at the top of the suspension roasting furnace cannot rise any further, start the second burner. After the second burner is adjusted to the maximum combustion capacity, start the third burner. When the top temperature of the suspension roasting furnace is greater than 500°C, prepare to add aluminum hydroxide raw materials;

[0026] Step 3: The raw materials in the raw material warehouse are sent to the dryer through the weighing scale and the feeder. The materials are mixed and dried with the flue gas after denitration by the SCR reactor in the dryer. The dried flue gas and the materials enter the first-stage preheater for further heat exchange and gas-solid separation. The separated dust-containing flue gas enters the dust collector, and the separated powder material enters the ash return device; the flue gas purified by the dust collector is sent to the chimney through the induced draft fan and finally discharged into the atmosphere. The ash return device sends the collected dust to the inlet of the first-stage cyclone cooler and mixes it with the material and gas from the retention tank to remove the crystal water in the ash return so that the ash loss on ignition meets the product requirements;

[0027] Step 4: The materials preheated by gas-solid separation in the first-stage preheater enter the first-stage preheater, the second-stage preheater, the suspension roasting furnace, the third-stage preheater and the retention tank in turn to produce qualified alumina products. After passing through the discharge port of the retention tank, the alumina products pass through the first-stage cyclone cooler, the second-stage cyclone cooler, the third-stage cyclone cooler and the fourth-stage cyclone cooler in turn, so that the materials are cooled to 200°C and then enter the indirect cooler 1 to be finally cooled to below 80°C;

[0028] Step 5: After the three-stage cyclone cooler passes through the alumina, compressed air is introduced into the cooling jacket, and the heated air is transported to the dryer station through the pipeline and finally sent to the dryer to supplement the heat of the dryer;

[0029] Step 6: When the feed load is greater than 90%, the temperature of the flue gas coming out of the primary preheater is insufficient for the reaction temperature of the SCR denitration catalyst and the temperature of the drying material, and the dryer station is started, and the hot flue gas from the combustion makes up for the lack of heat;

[0030] Step 7: Control the combustion capacity of the dryer station to ensure that the exhaust temperature of the induced draft fan is 120-130℃.

[0031] Compared with the prior art, the present invention has achieved the following technical effects:

[0032] The present invention provides an energy-saving aluminum hydroxide suspension roasting device and a roasting method thereof. The present invention arranges a primary preheater and a secondary preheater after the primary preheater, and fully preheats the material through the double preheating effect, thereby reducing the energy consumption of the suspension roasting furnace and achieving energy saving. When the temperature of the suspension roasting furnace is reduced to ≤800°C, the product ignition reduction is qualified. At the same time, the temperature of the gas delivered to the SCR reactor by the primary preheater will also be reduced, thereby reducing the exhaust temperature of the final induced draft fan and reducing it to below 130°C.

[0033] Furthermore, by recovering part of the sensible heat in the cooling jacket on the outer wall of the three-stage cyclone cooler as the combustion air of the dryer, the hot flue gas generated by the fuel ensures that the flue gas temperature discharged by the induced draft fan does not exceed 130°C and is supplemented to the inlet of the SCR reactor, thereby ensuring the minimum operating temperature of the denitrification catalyst and the dryer.

[0034] Furthermore, the first-stage preheater adopts multiple branches to enter the first-stage preheater, the second-stage preheater adopts multiple branches to enter the suspension roasting furnace, and the feeder adopts multiple branches to enter the dryer. This approach can disperse the material more evenly, thereby better exchanging heat with the flue gas and improving the heat transfer efficiency.

[0035] Finally, the entire device adopts a variety of energy-saving measures, which reduces the energy consumption of each ton of alumina produced by 0.1GJ / t compared with the original aluminum hydroxide roasting furnace with the lowest energy consumption, which is equivalent to 3.4 kilograms of standard coal. The roasting furnace with a daily output of 4,000 tons can reduce heat consumption by 13.6 tons of standard coal. The annual output of 1.3 million tons of alumina can reduce heat consumption by 4,420 tons of standard coal, bringing considerable economic benefits to the enterprise. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0037] Figure 1 This is a schematic structural diagram of an energy-saving aluminum hydroxide suspension roasting device according to Example 1;

[0038] In the figure: 1-indirect cooler; 2-fourth-stage cyclone cooler; 3-three-stage cyclone cooler; 4-second-stage cyclone cooler; 5-first-stage cyclone cooler; 6-retention tank; 7-third-stage preheater; 8-suspension roaster; 9-second-stage preheater; 10-first-stage preheater; 11-first-stage preheater; 12-SCR reactor; 13-dryer; 14-raw material bin; 15-feeder; 16-weighing scale; 17-dust collector; 18-ash return device; 19-induced draft fan; 20-chimney; 21-first burner; 22-second burner; 23-third burner; 24-dryer station. DETAILED DESCRIPTION

[0039] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] The purpose of the present invention is to provide an energy-saving aluminum hydroxide suspension roasting device and a roasting method thereof to solve the problems existing in the above-mentioned prior art, which can effectively reduce heat loss and thus achieve the technical effect of energy saving.

[0041] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0042] Embodiment 1

[0043] like Figure 1 As shown, this embodiment provides an energy-saving aluminum hydroxide suspension roasting device, including a cooling component, a preheating component, a suspension roasting furnace 8, an SCR reactor 12, a dryer 13, a feeding component, an exhaust gas emission component and a heat supply device, and the connection relationship between the various structures is as follows:

[0044] The cooling assembly includes a four-stage cyclone cooler 2, a three-stage cyclone cooler 3, a two-stage cyclone cooler 4 and a one-stage cyclone cooler 5. The inlet of the four-stage cyclone cooler 2 is connected to the outside atmosphere, the air outlet of the four-stage cyclone cooler 2 is connected to the inlet of the three-stage cyclone cooler 3 through a pipeline, the air outlet of the three-stage cyclone cooler 3 is connected to the inlet of the two-stage cyclone cooler 4 through a pipeline, the air outlet of the two-stage cyclone cooler 4 is connected to the inlet of the one-stage cyclone cooler 5 through a pipeline, and the air outlet of the one-stage cyclone cooler 5 is connected to the inlet of the suspension roasting furnace 8 through a pipeline. The discharge port of the one-stage cyclone cooler 5 is connected to the inlet of the two-stage cyclone cooler 4 through a pipeline, the discharge port of the two-stage cyclone cooler 4 is connected to the inlet of the three-stage cyclone cooler 3 through a pipeline, and the discharge port of the three-stage cyclone cooler 3 is connected to the inlet of the four-stage cyclone cooler 2 through a pipeline.

[0045] The preheating assembly includes a tertiary preheater 7, a secondary preheater 9, a primary preheater 10 and a primary preheater 11. The gas outlet of the suspension roasting furnace 8 is connected to the inlet of the tertiary preheater 7 through a pipeline, the gas outlet of the tertiary preheater 7 is connected to the inlet of the secondary preheater 9 through a pipeline, the gas outlet of the secondary preheater 9 is connected to the inlet of the primary preheater 10 through a pipeline, the gas outlet of the primary preheater 10 is connected to the inlet of the SCR reactor 12 through a pipeline, the gas outlet of the SCR reactor 12 is connected to the inlet of the dryer 13 through a pipeline, the outlet of the dryer 13 is connected to the inlet of the primary preheater 11 through a pipeline, and the gas outlet of the primary preheater 11 is connected to the exhaust gas emission assembly through a pipeline. The discharge port of the first-stage preheater 11 is connected to the inlet of the first-stage preheater 10 through a pipeline, the discharge port of the first-stage preheater 10 is connected to the inlet of the second-stage preheater 9 through a pipeline, the discharge port of the second-stage preheater 9 is connected to the inlet of the suspension roasting furnace 8 through a pipeline, the discharge port of the suspension roasting furnace 8 is connected to the inlet of the tertiary preheater 7, and the discharge port of the tertiary preheater 7 can be connected to the feed port of the first-stage cyclone cooler 5 through a pipeline.

[0046] It should be noted here that the above-mentioned four-stage cyclone cooler 2, three-stage cyclone cooler 3, two-stage cyclone cooler 4, one-stage cyclone cooler 5, three-stage preheater 7, two-stage preheater 9, one-stage preheater 10 and first-stage preheater 11 have the same structure, and their functions are slightly different only because of their different positions. They are all existing cyclone cooler structures (also called cyclone separators), which include an inlet, an air outlet and a material outlet, and the inlet can be used for air intake and material intake.

[0047] The heat supply device can provide heat for the SCR reactor 12 and the dryer 13 behind it. The dryer 13 is an existing Venturi dryer.

[0048] In actual use, starting the exhaust gas emission component can evacuate the entire system, so that the external cold air enters the fourth-stage cyclone cooler 2, the third-stage cyclone cooler 3, the second-stage cyclone cooler 4, the first-stage cyclone cooler 5, the suspension roasting furnace 8, the third-stage preheater 7, the second-stage preheater 9, the first-stage preheater 10, the SCR reactor 12, the dryer 13, the first-stage preheater 11 and the exhaust gas emission component in sequence, and then is discharged into the atmosphere. Then the feeding component is started to convey the material to the dryer 13, where the material is mixed and dried with the flue gas denitrated by the SCR reactor 12, and the dried flue gas and the material enter the first-stage preheater 11 for further heat exchange and gas-solid separation, and the separated dust-containing flue gas enters the exhaust gas emission component; the material preheated by gas-solid separation in the first-stage preheater 11 enters the first-stage preheater 10, the second-stage preheater 9, the suspension roasting furnace 8 and the third-stage preheater 7 in turn, and the produced material is discharged through the first-stage cyclone cooler 5, the second-stage cyclone cooler 4, the third-stage cyclone cooler 3 and the fourth-stage cyclone cooler 2 in turn.

[0049] In this embodiment, the cooling assembly further includes an indirect cooler 1, and the indirect cooler 1 can be an existing fluidized cooler. The discharge port of the four-stage cyclone cooler 2 is connected to the inlet of the indirect cooler 1, that is, the material flowing out of the four-stage cyclone cooler 2 will be further cooled by the indirect cooler 1 and then transported out.

[0050] In this embodiment, the exhaust gas emission assembly includes a dust collector 17, an induced draft fan 19 and a chimney 20. The dust collector 17 can be an existing electrostatic dust collector 17, and of course, those skilled in the art can also choose other types of dust removal structures. The inlet of the dust collector 17 is connected to the air outlet of the first-stage preheater 11, and the air outlet of the dust collector 17 is connected to the chimney 20. The induced draft fan 19 is arranged on the pipeline between the dust collector 17 and the chimney 20. The induced draft fan 19 provides negative pressure power for the entire system, so that the outside air can be sucked in from the inlet of the four-stage cyclone cooler 2.

[0051] In this embodiment, an ash return device 18 is provided at the ash outlet of the dust collector 17. The ash return device 18 is a device often equipped in the existing suspension roasting furnace 8. The ash outlet of the ash return device 18 is connected to the inlet of the primary cyclone cooler 5. The ash return device 18 sends the collected dust to the inlet of the primary cyclone cooler 5, and can mix it with the product from the retention tank 6 and the high-temperature air, remove the crystal water in the ash return, and make the ash loss on ignition meet the product requirements.

[0052] In this embodiment, the feeding assembly includes a raw material bin 14, a weighing scale 16 and a feeder 15. The weighing scale 16 adopts an existing belt scale, which can not only weigh the material, but also transport it to the next station. The weighing scale 16 is arranged below the discharge port of the raw material bin 14, and the output end of the weighing scale 16 is connected to the feed end of the feeder 15. The feeder 15 is an existing screw feeder, and the discharge end of the feeder 15 is connected to the inlet of the dryer 13.

[0053] In this embodiment, the discharge port of the feeder 15 is connected to the dryer 13 through two parallel feed conveying pipelines; alternatively, two feeders 15 can be arranged at the discharge end of the metering scale 16, so that separate conveying can also be achieved.

[0054] Similarly, Figure 1 As shown, the discharge port of the first-stage preheater 11 is provided with two first-stage material conveying pipelines, and one end of the two first-stage material conveying pipelines away from the first-stage preheater 11 is connected to the inlet of the first-stage preheater 10. Specifically, one end of the first-stage material conveying pipeline is connected to the pipeline between the first-stage preheater 10 and the second-stage preheater 9, and under the action of the second-stage preheater 9 conveying gas to the first-stage preheater 10, the material can be blown into the first-stage preheater 10. Similarly, the pipeline for conveying materials from the first-stage preheater 10 to the second-stage preheater 9 is connected to the pipeline for conveying gas from the third-stage preheater 7 to the second-stage preheater 9, and under the action of the conveying gas, the material is conveyed to the second-stage preheater 9.

[0055] Similarly, the discharge port of the secondary preheater 9 is provided with two secondary material conveying pipelines, and the ends of the two secondary material conveying pipelines away from the secondary preheater 9 are connected to the feed port of the suspension roasting furnace 8. The secondary preheater 9 conveys materials to the suspension roasting furnace 8 through the two secondary material conveying pipelines.

[0056] The reason for setting up two feed conveying pipelines, two first-stage material conveying pipelines and two second-stage material conveying pipelines is to disperse the materials more evenly so that they can fully contact with the flue gas to enhance the heat exchange effect, improve the heat transfer efficiency, and lay a solid foundation for reducing energy consumption of the entire system.

[0057] In this embodiment, two first-stage preheaters 11 are provided, and the two first-stage preheaters 11 are arranged in parallel with each other, that is, the connection relationship between the two first-stage preheaters 11 and the exhaust gas emission component, the first-stage preheater 10 and the dryer 13 is the same.

[0058] In this embodiment, a retention tank 6 is provided between the discharge port of the third-stage preheater 7 and the inlet of the first-stage cyclone cooler 5. The retention tank 6 is a closed container, which is divided into two upper and lower chambers. The upper end and the lower end of the upper chamber are staggered with baffles to increase the flow path of the material. The lower chamber can be used to introduce compressed air. The function of the retention tank 6 is to allow the material to continue to maintain a high temperature for a period of time in the retention tank 6, so that the material produces the final product in the retention tank 6. More importantly, because the retention tank 6 is provided, the combustion temperature of the suspension roasting furnace 8 can be appropriately reduced, thereby playing a role in energy saving.

[0059] In this embodiment, the heat supply device is a dryer station 24 (or dryer), which can provide heat to the SCR reactor 12 .

[0060] A cooling jacket is provided on the outer wall of the three-stage cyclone cooler 3, compressed air is introduced into the air inlet of the cooling jacket, and the air outlet of the cooling jacket is connected to the dryer station 24 through a pipeline. The compressed air can absorb the heat inside the three-stage cyclone cooler 3 through the cooling jacket, and then be transported to the dryer station 24 to provide combustion air with suitable temperature for the dryer station 24. The reason why the cooling jacket is only provided on the outer wall of the three-stage cyclone cooler 3 is that the internal temperature of the two-stage cyclone cooler 4 is higher, and the internal temperature of the four-stage cyclone cooler 2 is lower, and only the internal temperature of the three-stage cyclone cooler 3 is more suitable.

[0061] Embodiment 2

[0062] This embodiment provides a roasting method of an energy-saving aluminum hydroxide suspension roasting device, based on the energy-saving aluminum hydroxide suspension roasting device disclosed in Example 1, comprising the following steps:

[0063] Step 1: Start the induced draft fan 19 and the dust collector 17, so that the cold air enters the fourth-stage cyclone cooler 2, the third-stage cyclone cooler 3, the second-stage cyclone cooler 4, the first-stage cyclone cooler 5, the suspension roasting furnace 8, the third-stage preheater 7, the second-stage preheater 9, the first-stage preheater 10, the SCR reactor 12, the dryer 13, the first-stage preheater 11, the dust collector 17, the induced draft fan 19 and the chimney 20 in sequence, and then is discharged into the atmosphere.

[0064] Step 2: Adjust the air volume of the induced draft fan 19 to adjust the negative pressure of the suspension roasting furnace 8 to a pressure suitable for ignition, and start the first burner 21 to slowly heat up the suspension roasting furnace 8. Figure 1As shown, the first burner 21 is arranged on the pipeline for conveying gas from the second preheater to the first preheater. The first burner 21 is used to heat the lining in the pipeline between the second preheater and the suspension roasting furnace 8. The purpose of such slow heating is to preheat in advance to avoid excessive temperature and damage to the suspension roasting furnace 8. When the temperature at the top of the suspension roasting furnace 8 can no longer rise, the second burner 22 is started. The second burner 22 is an existing premixing burner. After the second burner 22 is adjusted to the maximum combustion capacity, the third burner 23 is started. The second burner 22 and the third burner 23 are both arranged at the air inlet. When the top temperature of the suspension roasting furnace 8 is greater than 500°C, the aluminum hydroxide raw material is ready to be added.

[0065] Step 3: The raw materials in the raw material bin 14 are sent to the dryer 13 through the weighing scale 16 and the feeder 15. The materials are mixed and dried with the high-temperature flue gas after denitration by the SCR reactor 12 in the dryer 13. The dried flue gas and the materials enter the first-stage preheater 11 together for further heat exchange and gas-solid separation. The separated dust-containing flue gas enters the dust collector 17, and the separated powder material enters the ash return device 18. The flue gas purified by the dust collector 17 is sent to the chimney 20 through the induced draft fan 19 and finally discharged into the atmosphere. The ash return device 18 sends the collected dust to the inlet of the first-stage cyclone cooler 5 and mixes it with the material and gas from the retention tank 6, removes the crystal water in the ash return, and makes the ash return loss meet the product requirements.

[0066] Step 4: The materials preheated by gas-solid separation in the first-stage preheater 11 sequentially enter the first-stage preheater 10, the second-stage preheater 9, the suspension roasting furnace 8, the third-stage preheater 7 and the retention tank 6 to produce qualified alumina products. After passing through the discharge port of the retention tank 6, the alumina products sequentially pass through the first-stage cyclone cooler 5, the second-stage cyclone cooler 4, the third-stage cyclone cooler 3 and the fourth-stage cyclone cooler 2, so that the materials are cooled to about 200°C and then enter the indirect cooler 1 to be finally cooled to below 80°C.

[0067] Step 5: After the three-stage cyclone cooler 3 passes through the high-temperature alumina, compressed air is introduced into the cooling jacket, and the heated air is transported to the dryer station 24 through a pipeline, and finally sent to the dryer 13 to supplement the heat for the dryer 13, thereby achieving the technical effect of waste heat recovery.

[0068] Step 6: When the feed load is greater than 90%, the temperature of the flue gas coming out of the primary preheater 10 is insufficient for the reaction temperature of the SCR denitration catalyst and the temperature of the dry material, and the dryer station 24 is started to supplement the heat of the hot flue gas. The reason for supplementing is that the primary preheater 10 and the secondary preheater 9 are set up. After double preheating, the temperature of the gas transported to the SCR reactor 12 and the dryer 13 will be lower than that of only setting one preheater, so the dryer station 24 is needed to supplement the heat.

[0069] Step 7: Control the combustion capacity of the dryer station 24 to ensure that the exhaust temperature of the induced draft fan 19 is 120-130°C.

[0070] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. An energy-saving aluminum hydroxide suspension roasting device, characterized in that: It includes cooling components, preheating components, suspension roasting furnace, SCR reactor, dryer, feeding components, exhaust gas emission components and heat supply device; The cooling assembly comprises a four-stage cyclone cooler, a three-stage cyclone cooler, a two-stage cyclone cooler and a one-stage cyclone cooler, the inlet of the four-stage cyclone cooler is connected to the outside atmosphere, the air outlet of the four-stage cyclone cooler is connected to the inlet of the three-stage cyclone cooler, the air outlet of the three-stage cyclone cooler is connected to the inlet of the two-stage cyclone cooler, the air outlet of the two-stage cyclone cooler is connected to the inlet of the one-stage cyclone cooler, and the air outlet of the one-stage cyclone cooler is connected to the inlet of the suspension roasting furnace; the discharge port of the one-stage cyclone cooler is connected to the inlet of the two-stage cyclone cooler, the discharge port of the two-stage cyclone cooler is connected to the inlet of the three-stage cyclone cooler, and the discharge port of the three-stage cyclone cooler is connected to the inlet of the four-stage cyclone cooler; The preheating assembly includes a three-stage preheater, a two-stage preheater, a one-stage preheater and a first-stage preheater, the gas outlet of the suspension roasting furnace is connected to the inlet of the three-stage preheater, the gas outlet of the three-stage preheater is connected to the inlet of the two-stage preheater, the gas outlet of the two-stage preheater is connected to the inlet of the one-stage preheater, the gas outlet of the one-stage preheater is connected to the inlet of the SCR reactor, the gas outlet of the SCR reactor is connected to the inlet of the dryer, the outlet of the dryer is connected to the inlet of the first-stage preheater, and the gas outlet of the first-stage preheater is connected to the exhaust gas emission assembly; the discharge port of the first-stage preheater is connected to the inlet of the one-stage preheater, the discharge port of the one-stage preheater is connected to the inlet of the two-stage preheater, the discharge port of the two-stage preheater is connected to the inlet of the suspension roasting furnace, and the discharge port of the suspension roasting furnace is connected to the inlet of the three-stage preheater; The heat supply device can provide heat for the SCR reactor.

2. The energy-saving aluminum hydroxide suspension roasting device according to claim 1 is characterized in that: The cooling assembly also includes an indirect cooler, and the discharge port of the four-stage cyclone cooler is connected to the inlet of the indirect cooler.

3. The energy-saving aluminum hydroxide suspension roasting device according to claim 1 is characterized in that: The exhaust gas emission component includes a dust collector, an induced draft fan and a chimney. The inlet of the dust collector is connected to the air outlet of the first-stage preheater, the air outlet of the dust collector is connected to the chimney, and the induced draft fan is arranged on the pipeline between the dust collector and the chimney.

4. The energy-saving aluminum hydroxide suspension roasting device according to claim 3 is characterized in that: An ash return device is provided at the ash outlet end of the dust collector, and the ash outlet of the ash return device is connected to the inlet of the primary cyclone cooler.

5. The energy-saving aluminum hydroxide suspension roasting device according to claim 1 is characterized in that: The feeding assembly includes a raw material bin, a weighing scale and a feeder. The weighing scale is arranged below the discharge port of the raw material bin, the output end of the weighing scale is connected to the feed end of the feeder, and the discharge end of the feeder is connected to the inlet of the dryer.

6. The energy-saving aluminum hydroxide suspension roasting device according to claim 5 is characterized in that: The discharge port of the feeder is connected to the dryer through two parallel feed conveying pipelines; The discharge port of the first-stage preheater is provided with two first-stage material conveying pipelines, and one end of the two first-stage material conveying pipelines away from the first-stage preheater is connected to the inlet of the first-stage preheater; The discharge port of the secondary preheater is provided with two secondary material conveying pipelines, and one end of the two secondary material conveying pipelines away from the secondary preheater is connected to the feed port of the suspension roasting furnace.

7. The energy-saving aluminum hydroxide suspension roasting device according to claim 1 is characterized in that: The first-stage preheaters are provided with two.

8. The energy-saving aluminum hydroxide suspension roasting device according to claim 1 is characterized in that: A retention tank is also provided between the discharge port of the third-stage preheater and the inlet of the first-stage cyclone cooler.

9. The energy-saving aluminum hydroxide suspension roasting device according to claim 1 is characterized in that: The heat supply device is a dryer station; A cooling jacket is provided on the outer wall of the three-stage cyclone cooler, and an air outlet of the cooling jacket is connected to the dryer station through a pipeline.

10. A roasting method of the energy-saving aluminum hydroxide suspension roasting device according to any one of claims 1 to 9, characterized in that: The following steps are involved: Step 1: Start the induced draft fan and dust collector, so that the cold air enters the fourth-stage cyclone cooler, the third-stage cyclone cooler, the second-stage cyclone cooler, the first-stage cyclone cooler, the suspension roaster, the third-stage preheater, the second-stage preheater, the first-stage preheater, the SCR reactor, the dryer, the first-stage preheater, the dust collector, the induced draft fan and the chimney in sequence, and then is discharged into the atmosphere; Step 2: Adjust the air volume of the induced draft fan to adjust the negative pressure of the suspension roasting furnace to a pressure suitable for ignition, start the first burner, and when the temperature at the top of the suspension roasting furnace cannot rise any further, start the second burner. After the second burner is adjusted to the maximum combustion capacity, start the third burner. When the top temperature of the suspension roasting furnace is greater than 500°C, prepare to add aluminum hydroxide raw materials; Step 3: The raw materials in the raw material warehouse are sent to the dryer through the weighing scale and the feeder. The materials are mixed and dried with the flue gas after denitration by the SCR reactor in the dryer. The dried flue gas and the materials enter the first-stage preheater for further heat exchange and gas-solid separation. The separated dust-containing flue gas enters the dust collector, and the separated powder material enters the ash return device; the flue gas purified by the dust collector is sent to the chimney through the induced draft fan and finally discharged into the atmosphere. The ash return device sends the collected dust to the inlet of the first-stage cyclone cooler and mixes it with the material and gas from the retention tank to remove the crystal water in the ash return so that the ash loss on ignition meets the product requirements; Step 4: The materials preheated by gas-solid separation in the first-stage preheater enter the first-stage preheater, the second-stage preheater, the suspension roasting furnace, the third-stage preheater and the retention tank in turn to produce qualified alumina products. After passing through the discharge port of the retention tank, the alumina products pass through the first-stage cyclone cooler, the second-stage cyclone cooler, the third-stage cyclone cooler and the fourth-stage cyclone cooler in turn, so that the materials are cooled to 200°C and then enter the indirect cooler 1 to be finally cooled to below 80°C; Step 5: After the three-stage cyclone cooler passes through the alumina, compressed air is introduced into the cooling jacket, and the heated air is transported to the dryer station through the pipeline and finally sent to the dryer to supplement the heat of the dryer; Step 6: When the feed load is greater than 90%, the temperature of the flue gas coming out of the primary preheater is insufficient for the reaction temperature of the SCR denitration catalyst and the temperature of the drying material, and the dryer station is started, and the hot flue gas from the combustion makes up for the lack of heat; Step 7: Control the combustion capacity of the dryer station to ensure that the exhaust temperature of the induced draft fan is 120-130℃.

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