Process equipment for high-temperature nitrogen-free sintered magnesia
By using artificial nitrogen-free combustion air and a gas cooling desulfurization system, the high energy consumption and environmental risks of nitrogen oxide treatment in high-temperature magnesia production have been solved, achieving low-cost, zero-emission magnesia production.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- XINGTAI PENGFEI MAGNESIUM SALT FACTORY
- Filing Date
- 2025-04-03
- Publication Date
- 2026-04-21
AI Technical Summary
In existing high-temperature magnesia production processes, the treatment of high-concentration nitrogen oxide flue gas presents environmental risks such as high energy consumption, high operating costs, and ammonia escape, making it difficult to meet environmental standards.
Artificial nitrogen-free combustion air is used instead of air as combustion air. The sintering of magnesia is completed by mixing carbon dioxide and oxygen, avoiding the generation of nitrogen oxides. Zero emissions of flue gas are achieved through gas cooling and desulfurization systems.
It reduces energy consumption and operating costs, reduces nitrogen oxide emissions, eliminates ammonia escape, achieves zero emissions of flue gas, and is in line with low-carbon economic policies.
Smart Images
Figure CN224151417U_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of high-temperature combustion technology of industrial kilns, and in particular relates to a process equipment for high-temperature nitrogen-free sintering of magnesia. Background Technology
[0002] Burnt magnesia is a major high-temperature refractory material with a wide range of applications. It is primarily used in the steel industry, and there are numerous domestic manufacturers producing it in large quantities.
[0003] Currently, the production process for high-grade calcined magnesia is as follows: Magnesite ore is calcined into lightly calcined magnesia, then pressed into apricot-shaped pellets, which are fed into a high-temperature calcining furnace. Using natural gas or heavy oil as fuel, the pellets are sintered and melted at 1800-1900℃. Cold air is blown in from the bottom of the furnace to cool and shrink the sintered material before it is processed into magnesia products. Cold air is blown in from the bottom of the furnace to contact the sintered material and cool it. The preheated cold air becomes combustion air, which is mixed with natural gas (or heavy oil) in a specific ratio and then burned to produce a high-temperature flame, completing the sintering of the magnesia. The high-temperature flue gas rises to preheat the magnesia pellets from top to bottom, and the flue gas is discharged from the top of the furnace after cooling.
[0004] The flue gas discharged from the top of the furnace enters the bag filter for dust removal. The purified flue gas is heated to 320°C by natural gas combustion and sent to the SCR denitrification unit. Concentrated ammonia water is used for catalytic reduction denitrification. The denitrified flue gas enters the wet desulfurization process and is discharged into the atmosphere after meeting the standards.
[0005] This technology is mature, has low energy consumption, and produces high-quality magnesia products, making it the mainstream production process for high-quality dead-burned magnesia in my country. However, its main drawback is that sintering at 1800-1900℃ causes nitrogen and oxygen in the air entering the sintering furnace to undergo significant oxidation at high temperatures (1300℃), generating nitrogen oxides, which the environmental protection industry refers to as "thermal NO." X Furthermore, with increasing temperature, especially above 1300℃, the production rate of nitrogen oxides increases exponentially. In actual production processes, when the temperature rises to 1800~1900℃, the NO content in the flue gas emitted from the sintering furnace increases significantly. X The concentrations were all between 5000 and 7000 mg / M. 3 Such high levels of nitrogen oxides in flue gas make denitrification difficult and costly.
[0006] High-concentration nitrogen oxide flue gas is generally treated with SCR (semi-catalytic reduction) ammonia reduction to remove nitrogen oxides, which allows the flue gas to meet emission requirements. However, the SCR process has the following four disadvantages:
[0007] First, the flue gas needs to be heated to above 320℃, and natural gas is used as the energy source for heating, which results in high energy consumption.
[0008] Secondly, the catalyst needs to be replaced regularly, especially at the end of its service life. The reduced denitrification capacity can easily lead to a decrease in the denitrification rate and excessive nitrogen oxides in the flue gas.
[0009] Third, the use of large amounts of ammonia (generally 18% concentrated ammonia water) is costly and can easily lead to ammonia escape.
[0010] Fourth, the operating costs are high. A typical magnesia furnace with a daily output of 150 tons requires 6 to 7 tons of concentrated ammonia water per day. The operating cost of denitrification is over 100 yuan per ton, resulting in an economic burden of 15,000 yuan per day.
[0011] In summary, traditional nitrogen-containing sintering industries, especially the production processes and equipment for reburned magnesia products, suffer from high energy consumption and operating costs due to the treatment of high-concentration nitrogen oxide flue gas. In severe cases, there are also environmental risks due to excessive nitrogen oxide emissions and ammonia escape.
[0012] Therefore, it is imperative to innovate safe, reliable, low-cost, and environmentally compliant high-temperature combustion processes, equipment, and methods that meet the characteristics of the high-temperature combustion industry, in order to achieve significant progress in existing technologies. Summary of the Invention
[0013] The purpose of this invention is to provide a process equipment for high-temperature nitrogen-free sintering of magnesia. This equipment uses artificial nitrogen-free combustion air instead of air as the combustion air to be sent into the calcining kiln to complete the sintering of magnesia.
[0014] The purpose of this invention is to provide a process equipment for high-temperature nitrogen-free sintering of magnesia. This equipment can synthesize artificial nitrogen-free combustion air to replace air as the combustion air and send it into the calcining kiln to complete the sintering of magnesia.
[0015] To achieve the aforementioned objectives, this invention provides a process equipment for high-temperature nitrogen-free sintered magnesia, comprising a calcining kiln, a bag filter, an induced draft fan, a gas cooler, a gas mixer, a liquid oxygen storage tank, a gasifier, a PLC control system, and a high-pressure blower.
[0016] The calcining kiln includes an artificial nitrogen-free combustion air inlet, a flue gas outlet, a natural gas inlet, a raw material inlet, and a magnesia outlet. The artificial nitrogen-free combustion air inlet is matched and connected to the high-pressure blower outlet, and the flue gas outlet is matched and connected to the flue gas inlet of the bag filter.
[0017] The bag filter includes a flue gas inlet, a clean flue gas outlet, and a discharge outlet. Its flue gas inlet is matched and connected to the flue gas outlet of the calcining kiln, and its clean flue gas outlet is matched and connected to the inlet of the gas cooler and the flue gas inlet of the desulfurization system, respectively.
[0018] The induced draft fan includes a clean flue gas inlet and a clean flue gas outlet. Its clean flue gas inlet is matched and connected to the clean flue gas outlet of the bag filter, and its clean flue gas outlet is matched and connected to the clean flue gas inlet of the gas cooler and the inlet of the desulfurization system, respectively.
[0019] The high-pressure blower includes an artificial nitrogen-free combustion air inlet and an artificial nitrogen-free combustion air outlet. The artificial nitrogen-free combustion air inlet is matched and connected to the artificial nitrogen-free combustion air outlet of the gas mixer, and the artificial nitrogen-free combustion air outlet is matched and connected to the artificial nitrogen-free combustion air inlet of the calcining kiln.
[0020] Unlike traditional nitrogen calcination,
[0021] The gas cooler includes a clean flue gas inlet, a cooled clean flue gas outlet, a cooling water inlet, and a cooling water outlet. Its clean flue gas inlet is matched and connected to the clean flue gas outlet of the induced draft fan, and its cooled clean flue gas outlet is matched and connected to the cooled clean flue gas inlet of the gas mixer.
[0022] The liquid oxygen storage tank includes a liquid oxygen inlet and a liquid oxygen outlet, with the liquid oxygen outlet being matched and connected to the vaporizer inlet.
[0023] The vaporizer also includes an oxygen outlet, which is matched and connected to the oxygen inlet of the gas mixer;
[0024] The gas mixer also includes a PLC action command interface and an artificial nitrogen-free combustion air outlet. The PLC action command interface controls the flow rate of the oxygen outlet of the gasifier, and the artificial nitrogen-free combustion air outlet is matched and connected to the artificial nitrogen-free combustion air inlet of the high-pressure blower.
[0025] The PLC control equipment includes a gas mixer detection signal terminal and a PLC action command interface. The gas mixer detection signal terminal is inserted into the inner shell of the gas mixer, and the PLC action command interface is matched with the oxygen outlet of the gasifier.
[0026] Preferably, the gas mixer (4) further includes a PLC action command interface and an artificial nitrogen-free combustion air outlet. Its PLC action command interface controls the cooling clean flue gas inlet of the gas cooler (3) and the oxygen outlet of the gasifier (6), respectively. Its artificial nitrogen-free combustion air outlet is matched and connected to the artificial nitrogen-free combustion air inlet of the high-pressure blower (8).
[0027] Preferably, the PLC control equipment includes a gas mixer detection signal terminal and a PLC action command interface. The gas mixer detection signal terminal extends into the inner shell of the gas mixer, and the PLC action command interface is matched with the cooled clean flue gas outlet of the gas cooler and the oxygen outlet of the gasifier, respectively.
[0028] Preferably, the calcining kiln is an internal combustion vertical calcining furnace.
[0029] The resulting mixed gas primarily consists of carbon dioxide and oxygen. Carbon dioxide does not participate in the reaction, while the oxygen in the gas undergoes an oxidative combustion reaction with natural gas (or heavy oil), releasing heat. This completes the high-temperature calcination of magnesia. The mixture of water-cooled flue gas and oxygen reaches room temperature, allowing for the cooling and quenching of the sintered magnesia material and the recovery of its heat to form combustion air, without altering the operating state of the calcining kiln. The discharged kiln gas primarily consists of carbon dioxide. A portion is recycled to produce artificial nitrogen-free combustion air, while the remainder is sent to the desulfurization system for flue gas desulfurization.
[0030] This operation eliminates the need for air as combustion air, and the absence of nitrogen during the calcination process prevents the production of nitrogen oxides. Therefore, it eliminates the need for ammonia catalytic reduction denitrification, thus preventing ammonia escape. Because no heating of the flue gas is required, natural gas energy costs are saved. The exhaust gas contains over 90% carbon dioxide, which can be pressurized and converted into liquid carbon dioxide for sale, turning waste into a valuable resource and ultimately achieving zero emissions – making it highly suitable for current low-carbon economic policies.
[0031] Compared with the prior art, the beneficial effects of the present invention are reflected in:
[0032] This invention provides a process and equipment for high-temperature nitrogen-free sintering of magnesia. It uses artificial nitrogen-free combustion air instead of air to complete the sintering of magnesia. Because air is not used, the 79% nitrogen component in the air is prevented from entering the combustion system, reducing exhaust emissions by more than two-thirds. This reduction in exhaust emissions also reduces heat loss in the flue gas, and the total amount of impurities is significantly reduced. Since no nitrogen oxides are produced, catalytic reduction denitrification is unnecessary, thus eliminating the risk of ammonia escape. Because no heating of the flue gas is required, natural gas energy costs are saved. The exhaust gas can contain over 90% carbon dioxide, which can be pressurized to produce liquid carbon dioxide for sale, turning waste into treasure and ultimately achieving zero emissions, making it highly suitable for current low-carbon economic policies. Attached Figure Description
[0033] The present invention will be further described below with reference to the accompanying drawings and embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0034] Figure 1 is a schematic diagram of the process equipment for high-temperature nitrogen-free sintered magnesia provided by the present invention.
[0035] Attached Figure
[0036] 1- Baghouse dust collector, 2- Exhaust fan, 3- Gas cooler, 4- Gas mixer, 5- Liquid oxygen storage tank, 6- Gasifier, 7- PLC controller, 8- High-pressure blower, 9- Internal combustion vertical calcining furnace. Detailed Implementation
[0037] Example 1: As Figure 1 As shown, this invention provides a process equipment for high-temperature nitrogen-free sintering of magnesia.
[0038] It consists of a bag filter (1), an induced draft fan (2), a gas cooler (3), a gas mixer (4), a liquid oxygen storage tank (5), a vaporizer (6), a PLC control system (7), a high-pressure blower (8), and an internal combustion vertical calcining furnace (9).
[0039] The internal combustion vertical calcining furnace (9) includes an artificial nitrogen-free combustion air inlet, a flue gas outlet, a natural gas inlet, an apricot pellet inlet, and a magnesia outlet. Its artificial nitrogen-free combustion air inlet is matched and connected to the outlet of the high-pressure blower (8), and its flue gas outlet is matched and connected to the flue gas inlet of the bag filter (1).
[0040] The bag filter (1) includes a flue gas inlet, a clean flue gas outlet and a discharge port. Its flue gas inlet is matched and connected to the flue gas outlet of the internal combustion vertical calciner (9), and its clean flue gas outlet is matched and connected to the inlet of the gas cooler (3) and the flue gas inlet of the desulfurization system, respectively.
[0041] The induced draft fan (2) includes a clean flue gas inlet and a clean flue gas outlet. Its clean flue gas inlet is matched and connected to the clean flue gas outlet of the bag filter (1), and its clean flue gas outlet is matched and connected to the clean flue gas inlet of the gas cooler (3).
[0042] The gas cooler (3) includes a clean flue gas inlet, a cooled clean flue gas outlet, a cooling water inlet and a cooling water outlet. Its clean flue gas inlet is matched and connected to the clean flue gas outlet of the induced draft fan (2), and its cooled clean flue gas outlet is matched and connected to the cooled clean flue gas inlet of the gas mixer (4).
[0043] The liquid oxygen storage tank (5) includes a liquid oxygen inlet and a liquid oxygen outlet, and its liquid oxygen outlet is matched and connected to the inlet of the vaporizer (6);
[0044] The vaporizer (6) also includes an oxygen outlet, which is matched and connected to the oxygen inlet of the gas mixer (4);
[0045] The gas mixer (4) also includes a PLC action command interface and an artificial nitrogen-free combustion air outlet. Its PLC action command interface controls the cooling clean flue gas outlet of the gas cooler (3) and the oxygen outlet of the gasifier, respectively. Its artificial nitrogen-free combustion air outlet is matched and connected to the artificial nitrogen-free combustion air inlet of the high-pressure blower (8).
[0046] The high-pressure blower (8) includes an artificial nitrogen-free combustion air inlet and an artificial nitrogen-free combustion air outlet. Its artificial nitrogen-free combustion air inlet is matched and connected to the artificial nitrogen-free combustion air outlet of the gas mixer (4), and its artificial nitrogen-free combustion air outlet is matched and connected to the artificial nitrogen-free combustion air inlet of the internal combustion vertical calciner (9).
[0047] The PLC control equipment (7) includes a gas mixer (4) detection signal terminal and a PLC action command interface. The gas mixer (4) detection signal terminal is inserted into the inner shell of the gas mixer (4), and the PLC action command interface is matched with the oxygen outlet of the gasifier (6) and the cooled clean flue gas outlet of the gas cooler (3), respectively.
Claims
1. A process equipment for high-temperature nitrogen-free sintered magnesia, comprising a calcining kiln (9), a bag filter (1), an induced draft fan (2), a gas cooler (3), a gas mixer (4), a liquid oxygen storage tank (5), a gasifier (6), a PLC control system (7), and a high-pressure blower (8). The calcining kiln (9) includes an artificial nitrogen-free combustion air inlet, a flue gas outlet, a natural gas inlet, a raw material inlet, and a magnesia outlet. Its artificial nitrogen-free combustion air inlet is matched and connected to the outlet of the high-pressure blower (8), and its flue gas outlet is matched and connected to the flue gas inlet of the bag filter (1). The bag filter (1) includes a flue gas inlet, a clean flue gas outlet and a discharge port. Its flue gas inlet is matched and connected to the flue gas outlet of the calcining kiln (9), and its clean flue gas outlet is matched and connected to the inlet of the gas cooler (3) and the flue gas inlet of the desulfurization system, respectively. The induced draft fan (2) includes a clean flue gas inlet and a clean flue gas outlet. Its clean flue gas inlet is matched and connected to the clean flue gas outlet of the bag filter (1), and its clean flue gas outlet is matched and connected to the clean flue gas inlet of the gas cooler (3) and the desulfurization system inlet, respectively. The high-pressure blower (8) includes an artificial nitrogen-free combustion air inlet and an artificial nitrogen-free combustion air outlet. Its artificial nitrogen-free combustion air inlet is matched and connected to the artificial nitrogen-free combustion air outlet of the gas mixer (4), and its artificial nitrogen-free combustion air outlet is matched and connected to the artificial nitrogen-free combustion air inlet of the calcining kiln (9). Its features are: The gas cooler (3) includes a clean flue gas inlet, a cooled clean flue gas outlet, a cooling water inlet and a cooling water outlet. Its clean flue gas inlet is matched and connected to the clean flue gas outlet of the induced draft fan (2), and its cooled clean flue gas outlet is matched and connected to the cooled clean flue gas inlet of the gas mixer (4). The liquid oxygen storage tank (5) includes a liquid oxygen inlet and a liquid oxygen outlet, and its liquid oxygen outlet is matched and connected to the inlet of the vaporizer (6); The vaporizer (6) also includes an oxygen outlet, which is matched and connected to the oxygen inlet of the gas mixer (4); The gas mixer (4) also includes a PLC action command interface and an artificial nitrogen-free combustion air outlet. Its PLC action command interface controls the flow rate of the oxygen outlet of the gasifier (6), and its artificial nitrogen-free combustion air outlet is matched and connected to the artificial nitrogen-free combustion air inlet of the high-pressure blower (8). The PLC control equipment (7) includes a gas mixer (4) detection signal terminal and a PLC action command interface. The gas mixer (4) detection signal terminal is inserted into the inner shell of the gas mixer (4), and the PLC action command interface is matched with the oxygen outlet of the cold vaporizer.
2. A process equipment for high temperature nitrogen-free sintered magnesia according to claim 1, characterized in that: The gas mixer (4) also includes a PLC action command interface and an artificial nitrogen-free combustion air outlet. Its PLC action command interface controls the cooling clean flue gas outlet of the gas cooler (3) and the oxygen outlet of the gasifier (6), respectively. Its artificial nitrogen-free combustion air outlet is matched and connected to the artificial nitrogen-free combustion air inlet of the high-pressure blower (8).
3. The process equipment for high temperature nitrogen-free sintered magnesia according to claim 1, characterized in that: The PLC control equipment (7) includes a gas mixer (4) detection signal terminal and a PLC action command interface. The gas mixer (4) detection signal terminal is inserted into the inner shell of the gas mixer (4), and the PLC action command interface is matched with the cooling clean flue gas outlet of the gas cooler (3) and the oxygen outlet of the gasifier (6).
4. A process equipment for high temperature nitrogen-free sintered magnesia according to claim 1 or 2 or 3, characterized in that: The calcining kiln (9) is an internal combustion vertical calcining furnace.