Device and method for recovering sensible heat of magnesium slag

Abstract

The invention discloses a device and method for recovering sensible heat of magnesium slag. The magnesium slag raw material passes through the evaporation section cold slag box, the heating section cold slag box and the cold slag machine from top to bottom in sequence, and the water supply pipe is connected to the heating section cold slag box, the water guide pipe and the boiler drum in sequence. The boiler drum and the evaporation section cold slag box are connected through the downcomer and the lead-out pipe. At the same time, the boiler drum, the downcomer, the evaporation section cold slag box and the lead-out pipe form an evaporation circulation loop. A steam outlet is provided at the top of the boiler drum, so that one channel of water is output through the water supply pipe, the heating section cold slag box, the water guide pipe, the boiler drum, the downcomer, the evaporation section cold slag box, the lead-out pipe, the boiler drum and the steam outlet in sequence, and the other channel of water passes through the water inlet of the cold slag machine, the cold slag machine and the water outlet of the cold slag machine in sequence. The invention discloses a device and method for recovering sensible heat of magnesium slag, which can efficiently recover the heat of high-temperature magnesium slag and avoid polluting the environment at the same time. It is suitable for sensible heat recovery treatment of high-temperature slag similar to that of metal magnesium smelting and other smelting processes.

Description

Technical Field

[0001] The invention relates to the technical field of sensible heat recovery of smelting process tailings, and more particularly to a device and method for recovering sensible heat of magnesium slag. Background Art

[0002] At present, my country is the world's largest magnesium producer. In 2021, China's magnesium production accounted for 80% of the world's magnesium production.

[0003] my country's magnesium resources are mainly solid mineral dolomite (main component CaMg(CO3)2), with large reserves, wide distribution and high quality, and can be found in almost every province. Most of the magnesium metal smelting adopts the silicothermic process.

[0004] The process is divided into four stages: calcining dolomite, preparing raw materials, reducing and refining. First, the dolomite is calcined at 1100℃-1300℃ in a rotary kiln or a vertical kiln to form calcined white. The reaction formula is:

[0005] MgCO 3 ·CaCO 3 =MgO·CaO+2CO 2

[0006] Then it is ground and mixed with ferrosilicon powder (75%) and fluorite powder (95%) to make balls, and then sent to a heat-resistant reduction tank to be reduced to crude magnesium at 1190℃-1210℃. The reaction process is:

[0007] CaO+2MgO+Si=2Mg+2CaO+SiO 2

[0008] Then it goes through solvent refining, ingot casting, surface treatment, and produces metal magnesium ingots.

[0009] The silicon thermal process produces about 5 tons of magnesium slag at a temperature of 1200°C for every ton of metallic magnesium smelted.

[0010] At present, high-temperature magnesium slag is mainly cooled by natural weathering, and the sensible heat is not recovered, resulting in heat waste and environmental pollution. The annual production of magnesium metal in China is 850,000 tons, and 4.25 million tons of magnesium slag are produced each year. If the sensible heat of magnesium slag within the range of 1200℃-200℃ is recovered, 180,000 tons of standard coal can be saved.

[0011] Therefore, how to provide a device and method for recovering the sensible heat of magnesium slag that can avoid polluting the environment and recover the heat of high-temperature magnesium slag is a technical problem that technical personnel in this field urgently need to solve. Summary of the invention

[0012] In view of this, the present invention provides a device and method for recovering sensible heat of magnesium slag, which can efficiently recover the heat of high-temperature magnesium slag while avoiding environmental pollution. It is suitable for sensible heat recovery treatment of high-temperature slag in metal magnesium smelting and other smelting processes similar to that of other smelting processes.

[0013] In order to achieve the above object, the present invention adopts the following technical solution:

[0014] A device for recovering sensible heat of magnesium slag comprises: an evaporation section cold slag box, a heating section cold slag box and a slag cooler arranged in sequence from top to bottom, wherein the heating section cold slag box is connected to the evaporation section cold slag box and the slag cooler respectively, and the evaporation section cold slag box and the heating section cold slag box both have a feed inlet at the top and a feed outlet at the bottom, the slag cooler has a feed inlet at the top and a slag outlet at the bottom, and the slag cooler is respectively provided with a water inlet and a water outlet.

[0015] Furthermore, it also includes: water supply pipe, boiler drum, water guide pipe, downcomer and outlet pipe;

[0016] Wherein, the water supply pipe is connected to the heating section slag cooling box, the water guide pipe and the boiler drum in sequence;

[0017] At the same time, the boiler drum and the evaporation section cold slag box are connected through the downcomer and the outlet pipe, and the boiler drum, the downcomer, the evaporation section cold slag box and the outlet pipe form an evaporation circulation loop, and a steam outlet is opened at the top of the boiler drum.

[0018] Preferably, a distributor is connected to the top of the evaporation section cold slag box.

[0019] Preferably, the distributor and the evaporation section cold slag box, the evaporation section cold slag box and the heating section cold slag box, and the heating section cold slag box and the slag cooler are all connected via an expansion device.

[0020] Preferably, it also includes: a belt conveyor, wherein the belt conveyor is located at the bottom end of the slag outlet of the slag cooler.

[0021] Preferably, it also includes: a pulverizing pipe, one end of which is a closed end and the other end is an air inlet, and a plurality of air outlets connected to the inner cavity of the pulverizing pipe are opened on the side wall of the pulverizing pipe, and the pulverizing pipe is located at the bottom end of the evaporation section cold slag box, and the plurality of air outlets are all facing the discharge port of the evaporation section cold slag box.

[0022] Preferably, the evaporation section cold slag box comprises:

[0023] Four membrane water-cooled walls, the four membrane water-cooled walls are connected to form a first rectangular frame, and every two adjacent membrane water-cooled walls are connected;

[0024] An upper annular header, the upper annular header is connected to the top ends of the four membrane water-cooled walls, and the upper annular header is connected to the outlet pipe;

[0025] A lower annular header, the lower annular header is connected to the bottom ends of the four membrane water-cooled walls, and the lower annular header is connected to the downcomer;

[0026] A plurality of vertical convection tubes are arranged in the first rectangular frame and are distributed at intervals, and the top end of each vertical convection tube is connected to the upper annular header, and the bottom end is connected to the lower annular header.

[0027] Preferably, the heating section slag cooling box comprises:

[0028] Four water jackets, the four water jackets are connected to form a second rectangular frame, and every two adjacent water jackets are connected, and any two relatively distributed water jackets are connected to the water supply pipe and the water guide pipe in a one-to-one correspondence, and the water supply pipe is connected to a water pump;

[0029] A plurality of serpentine tubes are arranged in the second rectangular frame, and the length of each serpentine tube extends along the length direction or the width direction of the second rectangular frame, and both ends of each serpentine tube are connected to two oppositely arranged water jackets in a one-to-one correspondence.

[0030] A method for recovering sensible heat of magnesium slag, comprising the following steps:

[0031] Step 1: Determine the principle and method of sensible heat recovery of magnesium slag raw materials through the experimental results of a small-scale experimental device;

[0032] Step 2: According to the principle of energy cascade utilization and the calculation based on the heat transfer principle, the cooling ratio of the evaporation section cold slag box, the heating section cold slag box and the cold slag machine is optimized, the respective heat exchange amounts are determined, heat transfer calculations are performed, and the heat transfer coefficient is solved. Finally, the heat exchange areas, drop heights and falling speeds of the magnesium slag raw materials of the evaporation section cold slag box, the heating section cold slag box and the cold slag machine are determined, and heat balance verification is performed to ensure that the outlet temperature of the magnesium slag raw material is reduced to 75°C to 85°C;

[0033] Step 3: Perform water circulation calculation to determine the height difference between the boiler drum and the evaporation section slag cooling box, the number and diameter of the downcomers and the outlet pipes, to ensure safe and reliable water circulation and avoid circulation stagnation or backflow;

[0034] Step 4: Calculate the steam-water resistance. According to the flow rate of water in the heating section slag cooler, the flow rate of water in the water guide pipe and the internal structure of the drum, determine the water resistance in the heating section slag cooler to provide a basis for selecting the water pump.

[0035] Step 5: Calculate the flow rate of water in the slag cooler according to the specific heat capacity of the magnesium slag raw material and water and the cooling requirement of the magnesium slag raw material;

[0036] Step 6: The magnesium slag raw material enters the evaporation section cold slag box through the inlet of the evaporation section cold slag box for cooling treatment, and the water in the heating part of the evaporation section cold slag box absorbs the heat of the magnesium slag raw material and evaporates into a steam-water mixture. The steam-water mixture enters the drum along the outlet pipe, and the drum separates the steam-water mixture. The separated water vapor is discharged from the steam outlet at the top of the drum and sent to the required steam-using place. At this time, the temperature of the magnesium slag raw material at the outlet of the evaporation section cold slag box drops to 355°C to 365°C;

[0037] Step 7: The magnesium slag raw material enters the heating section cold slag box through the discharge port of the evaporation section cold slag box and the feed port of the heating section cold slag box in sequence, and then flows downward under the action of gravity. During the downward movement of the magnesium slag raw material in the heating section cold slag box, it contacts with the heating parts of the heating section cold slag box to release heat, and the temperature of the magnesium slag raw material is further reduced to 235° C. to 245° C. At the same time, the water temperature in the heating parts of the heating section cold slag box is increased by 145° C. to 155° C. and then is sent into the boiler drum;

[0038] Step 8: After the magnesium slag raw material is cooled in the slag cooler of the heating section, it enters the slag cooler, and the temperature of the magnesium slag raw material is reduced to 75° C. to 85° C. through water cooling in the slag cooler.

[0039] Preferably, between step 6 and step 7, compressed air is introduced into the pulverizing pipe through the air inlet of the pulverizing pipe, and the compressed air in the pulverizing pipe located at the bottom of the cold slag box of the evaporation section will flow upward through the air outlet on the pulverizing pipe, thereby pulverizing the magnesium slag raw material.

[0040] Preferably, in step 6, the magnesium slag raw material enters the feed inlet of the cold slag box of the evaporation section through the distributor.

[0041] Preferably, after step 8, the magnesium slag raw material falls onto the belt conveyor through the slag outlet of the slag cooler, and the magnesium slag raw material is transported to a storage place.

[0042] Preferably, in step 6, the water in the heating part of the evaporation section slag cooling box absorbs the heat of the magnesium slag raw material and evaporates into a steam-water mixture, and the heating part of the evaporation section slag cooling box includes four membrane water-cooled walls and a plurality of vertical convection tubes.

[0043] Preferably, in step 7, the magnesium slag raw material contacts the heating parts of the heating section cold slag box and releases heat during the process of moving downward in the heating section cold slag box. At the same time, the water temperature in the heating parts of the heating section cold slag box rises by 145°C to 155°C and then is sent into the boiler drum. The heating parts of the heating section cold slag box include: four water jackets and multiple serpentine tubes.

[0044] Preferably, under the action of the water pump, the water supply pipe pumps the supply water (water from the outside) into the four water jackets and the multiple serpentine tubes, and then sends it to the boiler drum through the water guide pipe, and then sends it to the four membrane water-cooled walls and the multiple vertical convection tubes through the downcomer, and finally flows into the boiler drum through the outlet pipe.

[0045] It can be seen from the above technical solutions that, compared with the prior art, the present invention discloses a device and method for recovering sensible heat of magnesium slag, which can achieve the following technical effects:

[0046] It can efficiently recover the heat of high-temperature magnesium slag while avoiding environmental pollution. It is suitable for sensible heat recovery treatment of high-temperature slag in metal magnesium smelting and other smelting processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] 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 or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0048] Figure 1 It is a structural schematic diagram of a device for recovering sensible heat of magnesium slag according to the present invention;

[0049] Figure 2 for Figure 1 A magnified view of the structure at C in the middle;

[0050] Figure 3 for Figure 1 A magnified view of the structure at D in the middle;

[0051] Figure 4 for Figure 1 Sectional view at AA in the middle;

[0052] Figure 5 for Figure 1 Sectional view at the middle BB;

[0053] Figure 6 It is a structural schematic diagram of the experimental device in Experiment 2 of the present invention;

[0054] Figure 7Schematic diagram of the structure of the experimental device in Experiment 3 of the present invention.

[0055] Among them, 1-evaporation section cooling box; 2-heating section cooling box; 3-cooling machine; 4-water supply pipe; 5-boiler drum; 6-water guide pipe; 7-down pipe; 8-outlet pipe; 9-distributor; 101-expansion device; 10-belt conveyor; 102-powdering pipe; 11-membrane water-cooled wall; 12-upper annular header; 13-lower annular header; 14-vertical convection pipe; 21-water jacket; 22-serpentine pipe; 901-first jacketed container; 902-first water inlet; 903-first water outlet; 904-first slag outlet; 801-second jacketed container; 802-second water inlet; 803-second water outlet; 701-air supply pipe; 804-second slag outlet; DETAILED DESCRIPTION

[0056] 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.

[0057] 1. Experimental process

[0058] The background technology mentions that during the smelting process of magnesium metal, a large amount of magnesium slag at about 1200°C is produced. The magnesium slag in the high temperature state is a solid pellet of 40mm×50mm, which gradually releases heat and breaks into powder over time in the coke box.

[0059] First, study the pulverization mechanism of high-temperature magnesium slag to provide a basis for heat exchange.

[0060] Test 1: Place high-temperature magnesium slag on the ground with a thickness of about 50mm and allow it to cool naturally in the air. The magnesium slag temperature drops to 600℃ and begins to pulverize (in 4 minutes), and is basically pulverized in 8 minutes.

[0061] Experiment 2, experimental setup Figure 6 : The high-temperature magnesium slag is placed in the first jacketed container 901, and then the jacket of the first jacketed container 901 is cooled by water (the water enters from the first water inlet 902 of the first jacketed container 901 and exits from the first water outlet 903 of the first jacketed container 901):

[0062] The red slag temperature is 800℃, and 90% of it is pelletized particles. The device is filled with red slag and cooled with water, with a water flow rate of 5.5t / h.

[0063] The temperature of the red slag drops slowly, slightly faster near the water cooling jacket than in the center.

[0064] The outlet water temperature increased from 29°C to 36°C within 1 hour, and then dropped to 32°C and remained stable within 1 hour.

[0065] After 2 hours, the temperature of magnesium slag is 370℃ near the wall and 580℃ in the center.

[0066] The magnesium slag in the cylinder is discharged (discharged from the first slag discharge port 904 of the first jacketed container 901), the magnesium slag pulverization rate is about 20%, basically all exists in the state of particles, and the temperature is relatively high.

[0067] Experiment 3: Experimental setup Figure 7 , the high-temperature magnesium slag is placed in the second jacketed container 801, the jacket of the second jacketed container 801 is cooled by water (water enters from the second water inlet 802 on the second jacketed container 801, and exits from the second water outlet 803 on the second jacketed container 801), and an air supply pipe 701 with a small hole is set in the center of the container:

[0068] The red slag temperature is 800℃, and 90% is pelletized particles. Fill the device with red slag, cool it with water, the water flow rate is 5.5t / h, and the compressed air is passed into the air supply pipe, the flow rate is 0.2m 3 / min.

[0069] The test data are shown in the following table:

[0070]

[0071]

[0072] The test was stopped after 43 minutes, and discharge began (discharged from the second slag discharge port 804 of the second jacketed container 801), with a pulverization rate of about 60%.

[0073] Experimental phenomenon:

[0074] ① 29 minutes after the start of the test, the magnesium slag began to pulverize, and then the pulverization accelerated and released heat. The pulverization of the magnesium slag was completed about 40 minutes later.

[0075] ② After cooling and pulverization, the large particles of the pellets account for about 20-25% of the total slag.

[0076] 2. Test conclusion:

[0077] The cooling time is more than 40 minutes. Therefore, when designing the heat exchanger, the contact time between the magnesium slag and the heating surface of the heat exchanger should be increased to 4 times, that is, more than 160 minutes.

[0078] ② Ventilation cooling in a closed container takes 6-7 times longer than natural air cooling, so sufficient heat exchange time must be allowed when exchanging heat with the heated surface.

[0079] ③ The magnesium slag within 50mm distance from the heated surface can be cooled to 268℃.

[0080] ④ After ventilation in the closed space, the pulverization rate of magnesium slag is significantly improved.

[0081] ⑤The higher the magnesium slag pulverization rate, the higher the heat exchange efficiency between the magnesium slag and the heating surface.

[0082] 3. For the magnesium slag of a magnesium company in Fugu, a cooling and heat exchange device, namely a waste heat boiler, is designed. The magnesium slag processing capacity is 25t / h. The temperature of the slag when transported to the waste heat boiler is 1000℃, and it is required to be cooled to below 100℃.

[0083] 3.1 Scheme Concept

[0084] Magnesium slag is solid sensible heat, which breaks into powder during cooling and exchanges heat with the heated surface in an emulsified phase. Through heat balance calculation, 1000℃ magnesium slag 355×10 4 79% of the KJ / h of heat is utilized in the waste heat boiler.

[0085] 3.2 Design principles for magnesium slag sensible heat recovery device

[0086] The whole magnesium slag sensible heat recovery device is divided into four parts: a distributor 9, a water-cooled heat exchange system, a steel frame platform and escalator, and a slag cooler 3.

[0087] The design principle of the volume of the device for sensible heat recovery of magnesium slag is to determine the volume of the heat exchange surface based on the test conclusion that the heat exchange needs to stay for more than 160 minutes, and use the natural fall of magnesium slag instead of the blowing time. The bulk density of magnesium slag is 0.8t / m 3 , then volume V = (25 / 0.8) × (160 / 60) = 83.3 m 3 The length, width and height of the magnesium slag sensible heat recovery device are determined to be twice 7500×2600×3000mm (because the internal heat exchange surface accounts for about one quarter).

[0088] The design principle of the distributor 9 is that before the magnesium slag enters the heat exchanger, the length and width of the device for recovering the sensible heat of the magnesium slag are large, and the entry of the magnesium slag needs to be evenly distributed. A grid distributor is set, and the grid interval is 100 to 120 mm.

[0089] The design principle of the heat exchange surface tube spacing takes into account the cooling range of each tube and the natural falling fluidity of magnesium slag. According to the experimental conclusion, the net space of the heat exchange single tube designed this time is 2.5 times that of the magnesium slag pellets, that is, the tube spacing is 180mm.

[0090] 3.3 Determination of device parameters for magnesium slag sensible heat recovery

[0091] According to the user's demand for steam quality, the parameters of the device for magnesium slag sensible heat recovery are determined as follows:

[0092] Serial number name unit Numeric Serial number name unit Numeric 1 Magnesium slag processing capacity t / h 25 6 Number of slag coolers tower 3 2 Magnesium slag inlet temperature ℃ 1000 7 Slag cooler inlet / outlet material temperature ℃ 240 / 80 3 Boiler evaporation capacity t / h 5 8 Slag cooler inlet / outlet water temperature ℃ 30 / 50 4 Rated steam pressure MPa 1.25 9 Slag cooler circulating water volume t / h 100 5 Rated steam temperature ℃ saturation

[0093] 4. Determine the structure of a device for recovering sensible heat of magnesium slag according to the present invention:

[0094] The embodiment of the present invention discloses a device for recovering sensible heat of magnesium slag, comprising: an evaporation section cold slag box 1, a heating section cold slag box 2 and a slag cooler 3 arranged in sequence from top to bottom, and the heating section cold slag box 2 is respectively connected to the evaporation section cold slag box 1 and the slag cooler 3, and the evaporation section cold slag box 1 and the heating section cold slag box 2 have a feed inlet at the top and a discharge port at the bottom, the slag cooler 3 has a feed inlet at the top and a slag discharge port at the bottom, and the slag cooler 3 is respectively provided with a water inlet and a water outlet.

[0095] Furthermore, it also includes: a water supply pipe 4, a boiler drum 5, a water guide pipe 6, a downcomer 7 and an outlet pipe 8;

[0096] The water supply pipe 4 is connected to the heating section slag cooling box 2, the water guide pipe 6 and the boiler drum 5 in sequence;

[0097] At the same time, the boiler drum 5 and the evaporation section cold slag box 1 are connected through the downcomer 7 and the lead-out pipe 8, and the boiler drum 5, the downcomer 7, the evaporation section cold slag box 1 and the lead-out pipe 8 form an evaporation circulation loop, and a steam outlet is opened at the top of the boiler drum 5.

[0098] The high-temperature magnesium slag of the present invention relies on gravity to pass through the evaporation section cold slag box 1, the heating section cold slag box 2 and the slag cooler 3 in sequence to cool down and then fall down, thereby achieving the effect of cooling the high-temperature magnesium slag; at the same time, in the process of falling, (1) the high-temperature heat of the high-temperature magnesium slag can heat the water in the evaporation section cold slag box 1 into a water-vapor mixture, and then the water-vapor mixture is sent to the boiler drum 5 through the lead-out pipe 8. After the water vapor of the water-vapor mixture is separated in the boiler drum 5, the steam therein is led out to the steam-using place through the steam outlet; (2) the heating section The slag cooler 2 absorbs the medium-temperature heat of the magnesium slag raw material, heats the water introduced through the water supply pipe 4 into hot water, and then sends it to the boiler drum 5 through the water guide pipe 6, thereby increasing the steam production of the boiler drum 5; (3) the slag cooler 3 absorbs the low-temperature heat of the magnesium slag raw material, heats the water passing through the water inlet of the slag cooler 3 into low-temperature hot water, and then leads it out through the water outlet of the slag cooler 3 for heating. Therefore, the present invention recovers the heat of the magnesium slag raw material at different temperature stages, which can improve the recovery rate of the heat of the magnesium slag, and the whole process is pollution-free, energy-saving and environmentally friendly.

[0099] In order to further optimize the above technical solution, a distributor 9 is connected to the top of the evaporation section cold slag box 1.

[0100] The present invention adopts the above technical solution, and the beneficial effect that can be achieved is: the magnesium slag raw material enters the evaporation section cold slag box 1 through the distributor 9, so that the magnesium slag can fall into the evaporation section cold slag box 1 evenly, ensuring the fullness of the evaporation section cold slag box 1.

[0101] In order to further optimize the above technical solution, the distributor 9 is a steel grille with a plurality of through holes.

[0102] The present invention adopts the above technical solution, which can achieve the following beneficial effects: not only can the magnesium slag raw material pass through the distributor 9 evenly, but the distributor 9 is also heat-resistant and wear-resistant.

[0103] In order to further optimize the above technical solution, the distributor 9 and the evaporation section cold slag box 1, the evaporation section cold slag box 1 and the heating section cold slag box 2, and the heating section cold slag box 2 and the slag cooler 3 are all connected through an expansion device 101.

[0104] The present invention adopts the above technical solution, and can achieve the following beneficial effects: the expansion device 101 can absorb the expansion stress of the distributor 9, the evaporation section cold slag box 1, the heating section cold slag box 2 and the slag cooler 3, thereby ensuring the safe operation of the present invention.

[0105] The expansion device 101 may be a U-shaped metal part, or other connecting parts capable of absorbing the expansion stress of the distributor 9, the evaporation section cold slag box 1, the heating section cold slag box 2 and the slag cooler 3.

[0106] In order to further optimize the above technical solution, it also includes: a belt conveyor 10, which is located at the bottom end of the slag outlet of the slag cooler 3.

[0107] The present invention adopts the above technical scheme, and the beneficial effect that can be achieved is: the magnesium slag processed by the present invention can directly fall onto the belt conveyor 10 after coming out from the slag outlet of the slag cooler 3, so as to be transported to the storage place, thereby avoiding the magnesium slag from accumulating at the slag outlet of the slag cooler 3 and affecting the normal operation of the present application.

[0108] In order to further optimize the above technical solution, it also includes: a pulverizing pipe 102, one end of the pulverizing pipe 102 is a closed end, the other end is an air inlet, and a plurality of air outlets connected to the inner cavity of the pulverizing pipe 102 are opened on the side wall of the pulverizing pipe 102, and the pulverizing pipe 102 is located at the bottom end of the evaporation section cold slag box 1, and the plurality of air outlets are all facing the discharge port of the evaporation section cold slag box 1.

[0109] The present invention adopts the above technical solution, and can achieve the following beneficial effects: compressed air is transmitted to the evaporation section cold slag box 1 through the pulverizing pipe 102, so that the magnesium slag is pulverized when flowing out of the evaporation section cold slag box 1, thereby improving the heat transfer efficiency of the present invention.

[0110] In order to further optimize the above technical solution, the air inlet of the pulverizing pipe 102 is connected to an air supply pipe, the air supply pipe is connected to an air compressor, and a flow valve is connected to the air supply pipe.

[0111] The present invention adopts the above technical solution, and the beneficial effects that can be achieved are: compressed air is generated by an air compressor, and the flow valve can regulate the flow rate of compressed air sent into the pulverizing pipe 102 by the air supply pipe, so that the flow rate and flow rate of the compressed air entering the pulverizing pipe 102 are both within a suitable range.

[0112] In order to further optimize the above technical solution, the evaporation section cold slag box 1 includes:

[0113] Four membrane water-cooled walls 11, the four membrane water-cooled walls 11 are connected to form a first rectangular frame, and every two adjacent membrane water-cooled walls 11 are connected;

[0114] The upper annular header 12 is connected to the top of the four membrane water-cooled walls 11, and the upper annular header 12 is connected to the outlet pipe 8;

[0115] The lower annular header 13 is connected to the bottom ends of the four membrane water-cooled walls 11, and the lower annular header 13 is connected to the downcomer 7;

[0116] A plurality of vertical convection tubes 14 are arranged in the first rectangular frame and are distributed at intervals. The top end of each vertical convection tube 14 is connected to the upper annular header 12 and the bottom end is connected to the lower annular header 13 .

[0117] The present invention adopts the above technical scheme, and the beneficial effects that can be achieved are: (1) The evaporation section cold slag box 1 of the present invention is surrounded by membrane water-cooled walls 11, which absorbs the heat of the magnesium slag while ensuring the tightness of the evaporation section cold slag box 1, thereby reducing the furnace wall temperature and reducing heat loss; (2) by contacting the high-temperature magnesium slag at the same time through four membrane water-cooled walls 11 and multiple vertical convection tubes 14, the heat recovery efficiency of the high-temperature magnesium slag of the present invention will be further improved.

[0118] In order to further optimize the above technical solution, the pulverizing pipe 102 is connected to the lower annular header 13 by a hook.

[0119] In order to further optimize the above technical solution, a plurality of vertical convection tubes 14 are arranged in a square shape within the first rectangular frame.

[0120] The present invention adopts the above technical solution, which can achieve the following beneficial effects: the vertical convection tube 14 is arranged as above, which can not only make the magnesium slag flow smoothly but also ensure that the slag layer around the heating surface of the evaporation section cold slag box 1 is the thinnest, thereby reducing the heat transfer thermal resistance.

[0121] To further optimize the above technical solution, multiple vertical convection tubes 14 are arranged in a square with a side length of 180 mm × 180 mm within the first rectangular frame.

[0122] To further optimize the above technical solution, both the upper annular header 12 and the lower annular header 13 are in the shape of a "mouth".

[0123] To further optimize the above technical solution, each vertical convection tube 14 is respectively connected to the upper annular header 12 and the lower annular header 13 through connecting pipes.

[0124] To further optimize the above technical solution, the heating section slag cooler 2 includes:

[0125] Four water jackets 21, which are connected to form a second rectangular frame, and every two adjacent water jackets 21 are connected. At the same time, any two relatively distributed water jackets 21 are respectively connected to the water supply pipe 4 and the water guide pipe 6 in a one-to-one correspondence, and a water pump is connected to the water supply pipe 4;

[0126] Multiple serpentine tubes 22, which are arranged within the second rectangular frame, and the length of each serpentine tube 22 extends along the length direction or the width direction of the second rectangular frame. At the same time, both ends of each serpentine tube 22 are respectively connected to two relatively arranged water jackets 21 in a one-to-one correspondence.

[0127] By adopting the above technical solution, the beneficial effects that can be achieved by the present invention are: by simultaneously contacting the medium-temperature magnesium slag with the four water jackets 21 and the multiple serpentine tubes 22, the heat recovery efficiency of the present invention for the medium-temperature magnesium slag will be further improved.

[0128] The water jacket is equivalent to a water pipe, and its structure is the prior art in this field.

[0129] To further optimize the above technical solution, multiple serpentine tubes 22 are arranged in a square within the second rectangular frame.

[0130] By adopting the above technical solution, the beneficial effects that can be achieved by the present invention are: when the multiple serpentine tubes 22 are arranged as above, it can not only make the magnesium slag flow smoothly but also ensure that the slag layer around the heating surface of the heating section slag cooler 2 is thinnest, reducing the heat transfer thermal resistance.

[0131] To further optimize the above technical solution, multiple serpentine tubes 22 are arranged in a square with a side length of 180 mm × 180 mm within the second rectangular frame.

[0132] To further optimize the above technical solution, the interior of the water jacket 21 is partitioned into a multi-flow circuit of water, thereby further improving the heat recovery efficiency of the present invention for the medium-temperature magnesium slag.

[0133] Among them, the method of partitioning the interior of the water jacket 21 into a multi-flow circuit of water is common knowledge in this field and will not be elaborated here.

[0134] In order to further optimize the above technical solution, it also includes: a connecting frame with multiple material channels, the connecting frame is arranged across the top opening of the second rectangular frame and is connected to the top ends of the four water jackets 21, and multiple serpentine tubes 22 are suspended and connected to the connecting frame.

[0135] The present invention adopts the above technical solution, which can achieve the beneficial effect of improving the stability of the multiple serpentine tubes 22 located in the second rectangular frame.

[0136] In order to further optimize the above technical solution, the connecting frame is in the shape of a "cross", a "field", etc.

[0137] In order to further optimize the above technical scheme, the cross-section and height of the evaporation section cold slag box 1 and the heating section cold slag box 2 are optimized, and the contact time between the magnesium slag and the heating surface of the evaporation section cold slag box 1 and the heating section cold slag box 2 is prolonged, so that the magnesium slag stays in contact with its heating surface for about 200 minutes.

[0138] In order to further optimize the above technical solution, the slag cooler 3 adopts a water-cooled drum type to better cool the magnesium slag.

[0139] If the temperature reduction requirement for magnesium slag is not high, the slag cooler can be omitted and replaced by a slag discharge control valve.

[0140] A method for recovering sensible heat of magnesium slag, comprising the following steps:

[0141] Step 1: Determine the principle and method of sensible heat recovery of magnesium slag raw materials through the experimental results of a small-scale experimental device;

[0142] Step 2: According to the principle of energy cascade utilization and the calculation based on the heat transfer principle, optimize the cooling ratio of the evaporation section cold slag box 1, the heating section cold slag box 2 and the cold slag machine 3, determine their respective heat exchange capacities, perform heat transfer calculations, solve the heat transfer coefficient, and finally determine the heat exchange area, drop height and falling speed of the magnesium slag raw material of the evaporation section cold slag box 1, the heating section cold slag box 2 and the cold slag machine 3, and perform heat balance verification to ensure that the outlet temperature of the magnesium slag raw material is reduced to 75°C to 85°C;

[0143] Step 3: Calculate the water circulation, determine the height difference between the drum 5 and the evaporation section slag cooling box 1, the number and diameter of the downcomer 7 and the outlet pipe 8, ensure the water circulation is safe and reliable, and avoid circulation stagnation or backflow;

[0144] Step 4: Calculate the steam-water resistance. According to the flow rate of water in the water jacket 21 and the serpentine tube 22, the flow rate of water in the water guide pipe 6, and the internal structure of the drum 5, determine the water resistance in the heating section slag cooler 2 to provide a basis for the selection of the feed water pump.

[0145] Step 5: Calculate the flow rate of water in the slag cooler 3 according to the specific heat capacity of the magnesium slag raw material and water and the cooling requirement of the magnesium slag raw material;

[0146] Step 6: The magnesium slag raw material enters the evaporation section cold slag box 1 through the distributor 9 for cooling treatment, and the water in the heating part of the evaporation section cold slag box 1 absorbs the heat of the magnesium slag raw material and evaporates into a steam-water mixture. The steam-water mixture enters the drum 5 along the outlet pipe 8, and the drum 5 separates the steam-water mixture. The separated water vapor is discharged from the steam outlet at the top of the drum 5 and sent to the required steam use site. At this time, the temperature of the magnesium slag raw material at the outlet of the evaporation section cold slag box 1 drops to 355°C to 365°C;

[0147] Step 7: Compressed air is introduced into the pulverizing pipe 102 through the air inlet of the pulverizing pipe 102, and the compressed air in the pulverizing pipe 102 located at the bottom of the evaporation section cold slag box 1 will flow upward through the air outlet on the pulverizing pipe 102, thereby pulverizing the magnesium slag raw material;

[0148] Step 8: The magnesium slag raw material enters the heating section cold slag box 2 through the discharge port of the evaporation section cold slag box 1 and the feed port of the heating section cold slag box 2 in sequence, and then flows downward under the action of gravity. During the downward movement of the magnesium slag raw material in the heating section cold slag box 2, the magnesium slag raw material contacts with the heating parts of the heating section cold slag box 2 to release heat, and the temperature of the magnesium slag raw material is further reduced to 235° C. to 245° C. At the same time, the water temperature in the heating parts of the heating section cold slag box 2 is increased by 145° C. to 155° C. and then is sent to the boiler drum 5;

[0149] Step 9: After the magnesium slag raw material is cooled by the slag cooler 2 in the heating section, it enters the slag cooler 3, and is cooled by water in the slag cooler 3, so that the temperature of the magnesium slag raw material is reduced to 75° C. to 85° C.;

[0150] Step 10: The magnesium slag raw material falls onto the belt conveyor 10 through the slag outlet of the slag cooler 3, and the magnesium slag raw material is transported to a storage place.

[0151] The invention discloses a method for recovering sensible heat of magnesium slag, which recovers heat of magnesium slag raw materials at different temperature stages, thereby improving the recovery rate of heat of magnesium slag, and the whole process is pollution-free, energy-saving and environmentally friendly.

[0152] In order to further optimize the above technical solution, the heated parts of the evaporation section slag cooling box 1 include: four membrane water-cooled walls 11 and multiple vertical convection tubes 14; the heated parts of the heating section slag cooling box 2 include: four water jackets 21 and multiple serpentine tubes 22.

[0153] The present invention adopts the above technical solution, which can achieve the beneficial effect of: making the heat recovery efficiency of the evaporation section cold slag box 1 and the heating section cold slag box 2 of the present invention higher for magnesium slag.

[0154] In order to further optimize the above technical solution, under the action of the water pump, the water supply pipe 4 pumps the supply water (external water) into four water jackets 21 and multiple serpentine tubes 22, and then sends it to the boiler drum 5 through the water guide pipe 6, and then sends it to the four membrane water-cooled walls 11 and multiple vertical convection tubes 14 through the downcomer 7, and finally flows into the boiler drum 5 through the outlet pipe 8.

[0155] The present invention adopts the above technical scheme, and the beneficial effect that can be achieved is: the water flow path is: water supply pipe 4 → heating section cold slag box 2 → water guide pipe 6 → boiler drum 5 → downcomer 7 → evaporation section cold slag box 1 → lead-out pipe 8 → boiler drum 5 → steam outlet output, thereby improving the utilization rate of water and saving energy.

[0156] Embodiment: The embodiment of the present invention discloses a device and method for recovering sensible heat of magnesium slag, and the working principle is as follows:

[0157] Path of magnesium slag raw materials: Under the action of gravity, magnesium slag raw materials pass through distributor 9 → evaporation section cold slag box 1 → heating section cold slag box 2 → cold slag machine 3 → belt conveyor 10 → storage place in sequence;

[0158] The flow path of one water path is: water supply pipe 4 → heating section cold slag box 2 → water guide pipe 6 → boiler drum 5 → downcomer 7 → evaporation section cold slag box 1 → lead-out pipe 8 → boiler drum 5 → steam outlet output;

[0159] The flow path of the other water is: the water inlet of the slag cooler 3 → the slag cooler 3 → the water outlet of the slag cooler 3 .

[0160] In the above two water flow paths, the water supply pipe 4 → heating section cold slag box 2 → water guide pipe 6 → boiler drum 5 is a forced circulation; the boiler drum 5 → downcomer 7 → evaporation section cold slag box 1 → lead-out pipe 8 → boiler drum 5 is a natural circulation.

[0161] Specifically:

[0162] S1, the high-temperature magnesium slag enters the evaporation section cold slag box 1 through the distributor 9 for cooling treatment, then the water in the heat-receiving parts (four membrane water-cooled walls 11 and multiple vertical convection tubes 14) of the evaporation section cold slag box 1 will absorb the heat of the high-temperature magnesium slag and evaporate into a steam-water mixture, and the steam-water mixture enters the drum 5 (specifically, enters the steam-water separation device in the drum 5) along the outlet pipe 8, and the drum 5 (specifically, the steam-water separation device in the drum 5) will separate the steam-water mixture that enters, and the separated water vapor is discharged from the steam outlet at the top of the drum 5 and sent to the required steam-using place. At this time, the temperature of the magnesium slag raw material at the outlet of the evaporation section cold slag box 1 drops to about 360°C;

[0163] The boiler drum 5 is placed on a separate platform and supported by a boiler drum support. The body of the boiler drum 5 is also provided with a main steam valve, a safety valve, a pressure gauge, a water supply pipe, and four sets of water level gauges are provided in front and behind the body to display and control the pressure and water level of the boiler drum 5, making the boiler drum 5 safer in use. A dosing pipe and a sewage pipe are also provided at the bottom of the boiler drum 5 to remove impurities inside the boiler. The above structures are not marked in the drawings and are all prior art. Their installation positions and connection methods can be installed according to actual use conditions or in accordance with the provisions of current standards and specifications, and will not be described in detail here.

[0164] Furthermore, the structure of the drum 5 (a steam-water separation device is installed in the body of the drum 5) is prior art and will not be described in detail here.

[0165] S2, compressed air is introduced into the pulverizing pipe 102 through the air inlet of the pulverizing pipe 102, and the compressed air in the pulverizing pipe 102 located at the bottom of the evaporation section cold slag box 1 will flow upward through the air outlet on the pulverizing pipe 102, thereby pulverizing the magnesium slag raw material;

[0166] S3, the medium-temperature magnesium slag enters the heating section cold slag box 2 through the discharge port of the evaporation section cold slag box 1 and the feed port of the heating section cold slag box 2 in turn, and then flows downward under the action of gravity. During the process of the medium-temperature magnesium slag moving downward in the heating section cold slag box 2, it contacts and releases heat with the heating parts (four water jackets 21 and multiple serpentine tubes 22) of the heating section cold slag box 2, and the temperature of the medium-temperature magnesium slag is further reduced to about 240°C. At the same time, the water temperature in the heating parts of the heating section cold slag box 2 is increased by about 150°C and then sent to the boiler drum 5;

[0167] S4: The low-temperature magnesium slag enters the slag cooler 3, and is cooled by water in the slag cooler 3. The temperature of the magnesium slag raw material is reduced to about 80°C. At the same time, the water in the slag cooler 3 is heated and output for external use;

[0168] S5: The processed magnesium slag falls onto the belt conveyor 10 through the slag outlet of the slag cooler 3, and the magnesium slag raw material is transported to a storage place.

[0169] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0170] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A device for recovering sensible heat from magnesium slag, characterized in that: include: An evaporation section cold slag box (1), a heating section cold slag box (2) and a cold slag machine (3) are arranged in sequence from top to bottom, and the heating section cold slag box (2) is connected to the evaporation section cold slag box (1) and the cold slag machine (3) respectively, and the evaporation section cold slag box (1) and the heating section cold slag box (2) both have a material inlet at the top and a material outlet at the bottom, and the cold slag machine (3) has a material inlet at the top and a slag outlet at the bottom, and the cold slag machine (3) is respectively provided with a water inlet and a water outlet; Furthermore, it also includes: a water supply pipe (4), a boiler drum (5), a water guide pipe (6), a downcomer (7) and an outlet pipe (8); The water supply pipe (4) is sequentially connected to the heating section slag cooling box (2), the water guide pipe (6) and the boiler drum (5); At the same time, the boiler drum (5) and the evaporation section cold slag box (1) are connected through the downcomer (7) and the outlet pipe (8), and the boiler drum (5), the downcomer (7), the evaporation section cold slag box (1) and the outlet pipe (8) form an evaporation circulation loop, and a steam outlet is provided at the top of the boiler drum (5); The evaporation section cold slag box (1) comprises: Four membrane-type water-cooling walls (11), wherein the four membrane-type water-cooling walls (11) are connected to form a first rectangular frame, and every two adjacent membrane-type water-cooling walls (11) are connected; An upper annular header (12), the upper annular header (12) being connected to the top ends of the four membrane water-cooled walls (11), and the upper annular header (12) being connected to the outlet pipe (8); A lower annular header (13), the lower annular header (13) being connected to the bottom ends of the four membrane water-cooled walls (11), and the lower annular header (13) being connected to the downcomer (7); A plurality of vertical convection tubes (14), wherein the plurality of vertical convection tubes (14) are arranged in the first rectangular frame, and the plurality of vertical convection tubes (14) are distributed at intervals, and the top end of each vertical convection tube (14) is connected to the upper annular header (12), and the bottom end is connected to the lower annular header (13); The invention also comprises: a pulverizing pipe (102), one end of the pulverizing pipe (102) being a closed end and the other end being an air inlet, and a plurality of air outlets connected to the inner cavity of the pulverizing pipe (102) being provided on the side wall of the pulverizing pipe (102), and the pulverizing pipe (102) being located at the bottom end of the evaporation section cold slag box (1), and the plurality of air outlets all facing the discharge port of the evaporation section cold slag box (1); compressed air is introduced into the pulverizing pipe (102) through the air inlet of the pulverizing pipe (102), and the compressed air in the pulverizing pipe (102) located at the bottom of the evaporation section cold slag box (1) will flow upward through the air outlet on the pulverizing pipe (102), thereby achieving the effect of pulverizing the magnesium slag raw material.

2. The device for recovering sensible heat of magnesium slag according to claim 1, characterized in that: The top end of the evaporation section cold slag box (1) is connected to a distributor (9).

3. The device for recovering sensible heat of magnesium slag according to claim 2, characterized in that: The distributor (9) and the evaporation section cold slag box (1), the evaporation section cold slag box (1) and the heating section cold slag box (2), and the heating section cold slag box (2) and the slag cooler (3) are all connected via an expansion device (101).

4. The device for recovering sensible heat of magnesium slag according to claim 1, characterized in that: Also includes: A belt conveyor (10), wherein the belt conveyor (10) is located at the bottom end of the slag outlet of the slag cooler (3).

5. The device for recovering sensible heat of magnesium slag according to claim 1, characterized in that: The heating section slag cooling box (2) comprises: Four water jackets (21), the four water jackets (21) are connected to form a second rectangular frame, and every two adjacent water jackets (21) are connected, and any two relatively distributed water jackets (21) are connected to the water supply pipe (4) and the water guide pipe (6) in a one-to-one correspondence, and the water supply pipe (4) is connected to a water pump; A plurality of serpentine tubes (22) are arranged in the second rectangular frame, and the length of each serpentine tube (22) extends along the length direction or the width direction of the second rectangular frame, and at the same time, both ends of each serpentine tube (22) are connected to two oppositely arranged water jackets (21) in a one-to-one correspondence.

6. The method for recovering sensible heat of magnesium slag according to claim 5, characterized in that: Here are the steps: Step 1: Determine the principle and method of sensible heat recovery of magnesium slag raw materials through the experimental results of a small-scale experimental device; Step 2: According to the principle of energy cascade utilization and calculation based on the heat transfer principle, the cooling ratio of the evaporation section cold slag box (1), the heating section cold slag box (2) and the cold slag machine (3) is optimized, the respective heat exchange amounts are determined, heat transfer calculation is performed, the heat transfer coefficient is solved, and finally the heat exchange area, drop height and falling speed of the magnesium slag raw material of the evaporation section cold slag box (1), the heating section cold slag box (2) and the cold slag machine (3) are determined, and heat balance verification is performed to ensure that the outlet temperature of the magnesium slag raw material is reduced to 75° C. to 85° C.; Step 3: Perform water circulation calculation to determine the height difference between the boiler drum (5) and the evaporation section slag cooling box (1), the number and diameter of the downcomer (7) and the outlet pipe (8), to ensure safe and reliable water circulation and avoid circulation stagnation or backflow; Step 4: Calculate the steam-water resistance. According to the flow rate of water in the heating section slag cooler (2), the flow rate of water in the water guide pipe (6) and the internal structure of the boiler drum (5), determine the water resistance in the heating section slag cooler (2), so as to provide a basis for selecting the water pump. Step 5: Calculating the flow rate of water in the slag cooler (3) according to the specific heat capacity of the magnesium slag raw material and water and the cooling requirement of the magnesium slag raw material; Step 6: The magnesium slag raw material enters the evaporation section cold slag box (1) through the feed port of the evaporation section cold slag box (1) for cooling treatment, and the water in the evaporation section cold slag box (1) absorbs the heat of the magnesium slag raw material and evaporates into a steam-water mixture. The steam-water mixture enters the drum (5) along the outlet pipe (8), and the drum (5) separates the steam-water mixture. The separated water vapor is discharged from the steam outlet at the top of the drum (5) and sent to the required steam-using place. At this time, the temperature of the magnesium slag raw material at the outlet of the evaporation section cold slag box (1) drops to 355° C. to 365° C.; Step 7: The magnesium slag raw material enters the heating section cold slag box (2) through the discharge port of the evaporation section cold slag box (1) and the feed port of the heating section cold slag box (2) in sequence, and then flows downward under the action of gravity. During the downward movement of the magnesium slag raw material in the heating section cold slag box (2), the magnesium slag raw material contacts with the heating section cold slag box (2) to release heat, and the temperature of the magnesium slag raw material is further reduced to 235° C. to 245° C. At the same time, the water temperature in the heating section cold slag box (2) is increased by 145° C. to 155° C. before being fed into the boiler drum (5); Step 8: After being cooled in the heating section slag cooler (2), the magnesium slag raw material enters the slag cooler (3), and is cooled by water in the slag cooler (3), so that the temperature of the magnesium slag raw material is reduced to 75° C. to 85° C.

7. The method for recovering sensible heat of magnesium slag according to claim 6, characterized in that: Also includes: A pulverizing pipe (102), one end of the pulverizing pipe (102) being a closed end and the other end being an air inlet, and a plurality of air outlets connected to an inner cavity of the pulverizing pipe (102) being provided on a side wall of the pulverizing pipe (102), and the pulverizing pipe (102) being located at the bottom end of the evaporation section cold slag box (1), and the plurality of air outlets all facing the discharge port of the evaporation section cold slag box (1); Between step 6 and step 7, compressed air is introduced into the pulverizing pipe (102) through the air inlet of the pulverizing pipe (102), and the compressed air in the pulverizing pipe (102) located at the bottom of the evaporation section cold slag box (1) flows upward through the air outlet on the pulverizing pipe (102), thereby achieving the effect of pulverizing the magnesium slag raw material.

8. The method for recovering sensible heat of magnesium slag according to claim 6, characterized in that: The top of the evaporation section cold slag box (1) is connected to a distributor (9). In step 6, the magnesium slag raw material enters the feed inlet of the evaporation section cold slag box (1) through the distributor (9).

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