Electromagnetic heat radiation circulating light calcined magnesia shaft kiln

Abstract

The invention relates to a light calcined magnesia shaft kiln, in particular to an electromagnetic heat radiation circulation light calcined magnesia shaft kiln which comprises a mineral aggregate conveying device, a light calcined magnesia shaft kiln body and a light calcined magnesia shaft kiln body. The shaft kiln is used for roasting the mineral aggregate and comprises a preheating zone and a roasting zone for preheating the mineral aggregate, a soaking zone for soaking the roasted light calcined magnesia powder and a cooling zone for cooling; and the tail gas treatment system is used for treating the tail gas discharged from the kiln. The mineral aggregate is roasted by electromagnetic heating (radiation), only pure carbon dioxide gas generated by decomposition of magnesite is in the furnace, the pure carbon dioxide gas can be obtained while the light calcined magnesia powder is obtained, zero emission of carbon dioxide in the magnesite light calcined magnesia process is realized, and the utilization rate of magnesite resources is 100%. Energy is saved, and the heat utilization rate is improved. And the produced carbon dioxide is subjected to catalytic hydrogenation to continuously produce methanol, so that clean and green production is realized in the process.

Description

Technical Field

[0001] The invention relates to a light-burned magnesium oxide vertical kiln, in particular to an electromagnetic heat radiation circulation light-burned magnesium oxide vertical kiln. Background Art

[0002] Suspension kilns, rotary kilns and vertical kilns are used to heat magnesia to produce light-burned magnesium oxide. Since the combustion exhaust gas is used to directly heat and decompose the magnesia, the combustion exhaust gas is mixed with the decomposed carbon dioxide, which not only discharges the combustion exhaust gas in an disorderly manner, but also cannot directly recover the decomposed carbon dioxide. This is one of the fundamental reasons for the low utilization rate of magnesia resources. In direct-fired heating furnaces, the recovery and utilization of waste heat from magnesium oxide powder and tail gas is limited to heating combustion-supporting air or producing hot water for heating, and the thermal utilization rate is not high. Compared with suspension and rotary kilns, vertical kilns are good at processing magnesia lump ores, but the gas-solid heat transfer time is long, the effect is poor, and the heat transfer efficiency is low, which is also one of the fundamental reasons for the low production capacity of vertical kilns.

[0003] The invention provides a novel light-burned magnesium oxide vertical kiln with an electric-thermal-electric cycle, which completely realizes the green production of the magnesite light-burned magnesium oxide process. Summary of the invention

[0004] The purpose of the present invention is to provide an electromagnetic heat radiation circulation light-burned magnesium oxide vertical kiln. The light-burned magnesium oxide vertical kiln has a rectangular double-chamber roasting method, which increases the volume flow rate of the vertical kiln, performs all-round electric heating roasting, improves the heat transfer efficiency, shortens the heating decomposition time, improves the production capacity of the vertical kiln, reduces the processing amount of carbon dioxide dust, and realizes the clean production of light-burned magnesium oxide.

[0005] The objective of the present invention is achieved through the following technical solutions: A vertical kiln for lightly calcined magnesium oxide with electromagnetic heat radiation circulation, which roasts ore materials, comprises a preheating zone for preheating the ore materials, a roasting zone for roasting the ore materials, a soaking zone for evenly heating the magnesium oxide obtained by roasting, and a cooling zone for cooling the magnesium oxide obtained after roasting; it also comprises a feeding and distribution device for conveying and distributing the materials into the vertical kiln; and a tail gas treatment system for treating the carbon dioxide decomposed by roasting magnesite, an electric-heat system for heating the ore materials entering the vertical kiln until they are decomposed to generate magnesium oxide and carbon dioxide, and a waste heat boiler steam power generation system for cooling the magnesium oxide powder entering the cooling zone and recovering waste heat for power generation; the vertical kiln is provided with a preheating zone, a roasting zone, a soaking zone and a cooling zone; the preheating zone is used to treat the carbon dioxide decomposed by roasting magnesite, an electric-heat system for heating the ore materials entering the vertical kiln until they are decomposed to generate magnesium oxide and carbon dioxide, and a waste heat boiler steam power generation system for cooling the magnesium oxide powder entering the cooling zone and recovering waste heat for power generation; the vertical kiln is provided with a preheating zone, a roasting zone, a soaking zone and a cooling zone; Utilize the waste heat from roasting and the heat carried by carbon dioxide; the soaking zone plays a role in overcoming the "raw and overburned" "stewing" effect on the magnesium oxide powder; the cooling zone is coupled with the waste heat boiler and the steam power generation system to change the low waste heat recovery rate of the magnesium oxide powder; the preheating zone, roasting zone and soaking zone are rectangular "double-chamber" structures, which heat the ore in all directions and are electromagnetic heating with a large heat penetration depth; the loading and distribution device is a belt-type conveyor distribution that moves back and forth, and the ore is evenly distributed through a "ridge"-shaped redistributor; the waste heat boiler steam power generation system uses tubular heat exchange to generate steam, cools the magnesium oxide powder entering the cooling zone, and recovers the waste heat through the steam power generation system to generate electricity; a belt conveyor is set at the bottom of the vertical kiln to transport the magnesium oxide powder into the silo; the vertical kiln is a rectangular double-chamber structure with full-angle radiation roasting.

[0006] The electromagnetic heat radiation circulating light-burning magnesium oxide vertical kiln and the tail gas treatment system include dust recovery equipment, carbon dioxide waste heat recovery device and carbon dioxide treatment equipment for recovering carbon dioxide.

[0007] The electromagnetic heat radiation cycle light burning magnesium oxide vertical kiln and the electric heating system adopt electromagnetic heating to heat the roasting zone in all directions, so as to heat the ore entering the vertical kiln until it decomposes and generates magnesium oxide and carbon dioxide.

[0008] The advantages and effects of the present invention are: 1. Compared with other kiln designs, the present invention provides a rectangular double-chamber roasting method, increases the volume flow of the vertical kiln, and uses all-round electric heating to improve the heat transfer efficiency, process small-particle ore, and shorten the heating and decomposition time. Through the kiln design and the processing of small-particle ore, the production capacity of the vertical kiln is greatly improved.

[0009] 2. The present invention adopts electromagnetic heat to roast magnesite ore, and no combustion exhaust gas enters the roasting zone in the kiln. The carbon dioxide gas decomposed by the ore can be directly obtained as a high-purity carbon dioxide product after heat exchange in the preheating zone, which greatly improves the utilization rate of magnesite resources. Due to the use of a heat exchange cooling zone, the roasting zone is free from the interference of cooling wind, which greatly reduces the processing amount of carbon dioxide dust.

[0010] 3. The present invention produces lightly burned magnesium oxide powder, MgO: 85%, 90%, 95%; a magnesium oxide powder soaking zone is arranged in the furnace, which plays a role of "stewing materials", and the raw overburning rate is extremely small (≤1%); activity: ≥400ml; carbon dioxide purity is 99.5%.

[0011] 4. The present invention further uses a waste heat power generation system to convert the waste heat of the carbon dioxide gas leaving the kiln into waste heat to cool the magnesium oxide, produces steam through a tubular heat exchange system, and couples it with a steam power generation system and an electromagnetic heating system to achieve an electric-heat-electric cycle, which greatly reduces energy costs, improves energy efficiency, and also achieves clean production of light-burned magnesium oxide. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a schematic diagram of the overall structure of the vertical kiln of the present invention; Figure 2 It is a schematic diagram of the electromagnetic heating preheating roasting zone of the vertical kiln of the present invention.

[0013] Numbers in the figure: feed 1, ridge-type cloth 2, air outlet 3, preheat zone 4, partition wall 5, baking zone 6, soaking zone 7, cooling zone 8, discharge 9, water inlet 10, decomposition gas treatment system 11, carbon dioxide 12, water inlet 13, power generation system 14. DETAILED DESCRIPTION

[0014] The present invention will be described in detail below with reference to the embodiments shown in the accompanying drawings.

[0015] The light-burned magnesium oxide vertical kiln with electric heat cycle of the present invention comprises a feed 1, a ridge-type distribution 2, an air outlet 3, a preheating zone 4, a partition wall 5, a roasting zone 6, a soaking zone 7, a cooling zone 8, a discharge 9, a water inlet 10, a decomposition gas treatment system 11, carbon dioxide 12, a water inlet 13, and a power generation system 14. The feed and distribution device is used to transport and distribute the material into the vertical kiln; the light-burned vertical kiln adopts a rectangular double-chamber design and is used to roast the ore. The light-burned vertical kiln comprises a preheating zone for preheating the ore, a roasting zone for roasting the ore, a soaking zone for soaking the magnesium oxide obtained by roasting, and a cooling zone for cooling the magnesium oxide obtained after roasting; a tail gas treatment system for treating carbon dioxide decomposed by roasting magnesite; an electric-heat system for heating the ore entering the vertical kiln until it is decomposed to generate magnesium oxide and carbon dioxide; a waste heat boiler steam power generation system for cooling the magnesium oxide powder entering the cooling zone and recovering waste heat for power generation.

[0016] A middle partition is installed in the rectangular vertical kiln, which not only allows for all-round electromagnetic heating, but also provides a "double-chamber roasting" mode, which increases the processing capacity exponentially.

[0017] After the magnesite ore in the rectangular shaft kiln is heated by electromagnetic heat, the contact between combustion exhaust gas and the ore is avoided, and the ore in the roasting zone is heated evenly, ensuring that the magnesite is simply decomposed into magnesium oxide and carbon dioxide, which is conducive to the direct recovery and utilization of high-purity carbon dioxide.

[0018] After the magnesite ore in the rectangular vertical kiln is heated by electromagnetic heat, the heat transfer rate is improved, the ore is heated evenly, and it can process ore with a size of 6mm~20mm. It completely solves the coking caused by local overheating or the burning caused by being far away from the fire mouth, and greatly improves the production capacity of the vertical kiln.

[0019] The ore in the preheat zone in the rectangular vertical kiln is heated by the carbon dioxide decomposed by the magnesite. The ore in the preheat zone recovers the waste heat of the carbon dioxide and also ensures that no impurity gas is generated.

[0020] A uniform heating zone is set in the rectangular vertical kiln, which receives the magnesium oxide decomposed by heating in the "double-chamber" roasting zone. It not only has the double-chamber magnesium oxide mixing function, but also plays the role of stewing the materials, ensuring the uniform heating of the light-burned magnesium oxide and avoiding "raw" and over-burning.

[0021] By adopting the above technical solution, on the one hand, the ore can be preheated efficiently, and on the other hand, dust can be greatly reduced, the amount of dust treatment can be reduced, and more importantly, high-purity carbon dioxide gas can be obtained, thereby improving the utilization rate of magnesite resources; the electric heating method not only provides a pure carbon dioxide production mode, but also can heat small-particle ore. In addition, the "double-chamber" roasting structure greatly improves the production capacity of the vertical kiln.

[0022] The rectangular vertical kiln is equipped with a waste heat power generation system, which uses the waste heat of the carbon dioxide gas leaving the preheating zone and the waste heat of the magnesium oxide leaving the soaking zone to heat water through a tubular heat exchanger to generate steam, which is coupled to the steam power generation system.

[0023] By adopting the above technical solution, waste heat is recovered for power generation and connected to the electromagnetic heating system to form an electric-heat-electric cycle mode. Compared with other waste heat recovery and utilization methods, this technical solution not only improves the waste heat recovery rate, but also overcomes the high cost of using electric heating alone.

[0024] The rectangular vertical kiln is equipped with a carbon dioxide gas recovery system. The carbon dioxide gas leaving the vertical kiln is introduced into a heat exchange dust removal device for dust removal, and then flows out through a tubular heat exchanger and is pressurized and liquefied to produce liquid carbon dioxide or dry ice. It can also use a homemade copper-based catalyst for catalytic hydrogenation to produce methanol.

[0025] The rectangular vertical kiln cooling zone has changed the previous method of cooling magnesium oxide powder by cold air. Tubular heat exchangers are arranged around the cooling zone and connected to the carbon dioxide waste heat tubular heat exchange system. The steam produced is generated through the steam power generation system and reused.

[0026] By adopting the above technical solution, the waste heat of carbon dioxide and the waste heat of light-burned magnesium oxide are coupled to the steam power generation system, which not only improves the energy utilization rate but also reduces the cost of electric heating, while obtaining a high-purity carbon dioxide product.

Claims

1. An electromagnetic heat radiation cycle light burning magnesium oxide vertical kiln, characterized in that: The light-burned magnesium oxide vertical kiln roasts the ore material, and includes a preheating zone for preheating the ore material, a roasting zone for roasting the ore material, a soaking zone for evenly heating the roasted magnesium oxide, and a cooling zone for cooling the roasted magnesium oxide; it also includes a feeding and distribution device for conveying and distributing the material into the vertical kiln; and a tail gas treatment system for treating the carbon dioxide decomposed by roasting magnesite, an electric-heat system for heating the ore material entering the vertical kiln until it decomposes to generate magnesium oxide and carbon dioxide, and a waste heat boiler steam power generation system for cooling the magnesium oxide powder entering the cooling zone and recovering waste heat for power generation; the vertical kiln is provided with a preheating zone, a roasting zone, a soaking zone and a cooling zone; the preheating zone utilizes the waste heat from roasting and The heat carried by carbon dioxide; the soaking zone plays a role in overcoming the "raw and overburned" "stewing" effect on the magnesium oxide powder; the cooling zone is coupled with the waste heat boiler and the steam power generation system to change the low waste heat recovery rate of the magnesium oxide powder; the preheating zone, roasting zone and soaking zone are rectangular "double-chamber" structures, which heat the ore in all directions and are electromagnetic heating with a large heat penetration depth; the loading and distribution device is a belt-type conveyor distribution that moves back and forth, and the ore is evenly distributed through a "ridge"-shaped redistributor; the waste heat boiler steam power generation system uses tubular heat exchange to generate steam, cools the magnesium oxide powder entering the cooling zone, and recovers waste heat through the steam power generation system to generate electricity; a belt conveyor is set at the bottom of the vertical kiln to transport the magnesium oxide powder into the silo; the vertical kiln is a rectangular double-chamber structure with full-angle radiation roasting.

2. The electromagnetic heat radiation cycle light-burned magnesium oxide vertical kiln according to claim 1, characterized in that: The tail gas treatment system includes dust recovery equipment, a carbon dioxide waste heat recovery device and a carbon dioxide treatment equipment for recovering carbon dioxide.

3. The electromagnetic heat radiation cycle light-burned magnesium oxide vertical kiln according to claim 1, characterized in that: The electric heating system adopts electromagnetic heating to heat the roasting zone in all directions, and is used to heat the ore entering the vertical kiln until it decomposes and generates magnesium oxide and carbon dioxide.

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