Denitration system utilizing flue gas waste heat of copper smelting anode furnace

Abstract

The utility model discloses a denitration system utilizing flue gas waste heat of a copper smelting anode furnace, which comprises an anode furnace, an air cooler, a dust remover, a hot flue gas cooling channel of a heat exchanger, a desulfurizing tower, a demister, a cold flue gas heating channel of the heat exchanger, a flue gas preheater and an SCR (Selective Catalytic Reduction) device which are sequentially communicated through a pipeline, and a heat pipe evaporation section and a heat pipe condensation section of the heat exchanger are respectively arranged in the hot flue gas cooling channel and the cold flue gas heating channel of the heat exchanger. According to the utility model, air-cooled high-temperature flue gas (400-450 DEG C) of the flue gas of the anode furnace is used for preheating the flue gas subjected to impurity removal at the outlet of the desulfurization facility through the heat exchanger, so that the use cost of natural gas can be greatly reduced, the use of redundant equipment is reduced, and the operation cost is greatly reduced.

Description

Technical Field

[0001] The utility model relates to the field of flue gas treatment of copper smelting anode furnace, in particular to a denitration system that utilizes the waste heat of the flue gas of the copper smelting anode furnace. Background Technique

[0002] At present, there are two methods for denitration of the flue gas of copper smelting anode furnace.

[0003] One is the ozone oxidation absorption method for denitration. Its main principle is to utilize the strong oxidizing property of ozone to instantaneously oxidize the low-valent nitrogen oxides that are slightly soluble in water into soluble high-valent nitrogen oxides, and then absorb the nitrogen oxides in the scrubbing tower to achieve the purpose of removal, without affecting the emission control of other pollutants. The final reaction occurring in the ozone oxidation of NOx is that NO is oxidized to generate N 2 O 5 . The N 2 O 5 generated by oxidation exists in the form of nitric anhydride, is easily soluble in water, and generates nitric acid after being absorbed by wet scrubbing. The molar ratio of NO and O 3 in the final reaction of oxidation to generate N 2 O 5 is 1:1.5. When the ozone denitration device actually operates, the molar ratio of NO and O 3 should consider a certain excess coefficient and be designed and operated according to 1:1.6 - 1.7 to ensure that NOx is completely oxidized and absorbed by O 3 to achieve the up-to-standard emission of NOx. The problems existing in the ozone method for denitration are: the nitrate wastewater generated needs to be collected separately and then subjected to salt evaporation treatment, and the generated salt may be hazardous waste and needs to be outsourced for disposal, with high disposal costs. In addition, when there is a small amount of ozone emission, it may cause the atmospheric ozone concentration to exceed the standard, affecting the atmospheric environmental quality. Therefore, this scheme is not recommended.

[0004] The second is to adopt the flue gas SCR method for denitration. Using ammonia as a reducing agent, ammonia reacts with nitrogen oxides to generate non-toxic and non-secondary-polluting N2 and H2O. By selecting an appropriate catalyst for the SCR denitration process, the reaction can be controlled to proceed efficiently within a relatively low temperature range, and the occurrence of side reactions can be effectively inhibited. Selecting the currently relatively mature and advanced SCR medium and low temperature catalyst denitration process in China, within a certain space velocity condition, when the starting reaction temperature range is 220 - 260 °C, even under the condition of ultra-high concentration of nitrogen oxides, the nitrogen oxides can react efficiently, and the denitration efficiency can reach up to more than 99%. The flue gas entering the SCR denitration device needs to be pretreated for dust removal and desulfurization to prevent catalyst blockage. In addition, the temperature of the flue gas after wet desulfurization is 50 - 70 °C, and an internal heating furnace is required, consuming energy.

[0005] The utility model preheats the flue gas after impurity removal at the outlet of the desulfurization facility through a heat exchanger by using the high-temperature flue gas (400 - 450 °C) after air cooling of the anode furnace flue gas, which can greatly reduce the use cost of natural gas, reduce the investment in redundant equipment, and greatly reduce the operation cost. Summary of the Invention

[0006] To solve the above technical problems, the utility model designs a denitration system that utilizes the waste heat of the copper smelting anode furnace flue gas.

[0007] The utility model adopts the following technical solutions:

[0008] A denitration system that utilizes the waste heat of the copper smelting anode furnace flue gas, including a hot flue gas cooling channel of an anode furnace, an air cooler, a dust collector, a heat exchanger, a desulfurization tower, a demister, a cold flue gas heating channel of the heat exchanger, a flue gas preheater, and an SCR device, which are connected in sequence through pipelines. The heat pipe evaporation section and the heat pipe condensation section of the heat exchanger are respectively arranged in the hot flue gas cooling channel and the cold flue gas heating channel of the heat exchanger.

[0009] Preferably, the demister adopts a wet electrostatic demister or a water washing tower.

[0010] Preferably, the heat exchanger adopts a horizontal heat exchanger.

[0011] Preferably, the dust collector adopts a metal filter bag.

[0012] Preferably, the flue gas preheater adopts a natural gas combustion device.

[0013] Preferably, an induced draft fan is connected between the hot flue gas cooling channel of the heat exchanger and the desulfurization tower.

[0014] The beneficial effects of the utility model are as follows: (1) After configuring a wet electrostatic demister (or a water washing tower) behind the flue gas desulfurization facility to further remove impurities and salts in the flue gas, the high-temperature flue gas (400 - 450 °C) after air cooling of the anode furnace flue gas is used to preheat the flue gas after impurity removal at the outlet of the desulfurization facility through a heat exchanger (indirect heat exchange), and then connected to the SCR denitration system; (2) The temperature of the flue gas at the outlet of the electrostatic demister is 50 °C - 70 °C. After the hot-end flue gas (380 °C - 400 °C) and the cold-end flue gas (50 °C - 70 °C) are heat-exchanged, the temperature of the outlet flue gas rises to about 220 °C - 250 °C. Compared with the current method of heat-exchanging the flue gas (220 °C - 260 °C) after SCR denitration with the flue gas at the outlet of the electrostatic demister (50 °C - 70 °C) and burning a large amount of natural gas for heating, not only the heating efficiency is improved, but also a large amount of gas use is saved; (3) The installation and use of the waste heat boiler for the anode furnace hearth flue gas are cancelled, saving a large amount of equipment costs. Brief Description of the Drawings

[0015] Figure 1 is the process flow chart of the present utility model;

[0016] Figure 2 is the schematic flow chart of the implementation mode of the flue gas denitration system of the present utility model;

[0017] Figure 3 is the structural schematic diagram of the horizontal heat exchanger in the present utility model;

[0018] Wherein: 1. Flue gas after metal filter bag dust removal, 2. Horizontal heat exchanger, 3. Induced draft fan, 4. Desulfurization tower, 5. Demister, 6. Natural gas combustion device, 7. Flue gas at the outlet of the electric demister, 8. Flue gas at the inlet of SCR, 21. Hopper, 22. Heat pipe evaporation section, 23. Heat pipe condensation section, 24. Hot flue gas cooling channel, 25. Cold flue gas heating channel. Specific implementation mode

[0019] The technical solution of the present utility model will be further specifically described below through specific embodiments in conjunction with the accompanying drawings:

[0020] Embodiment: As Figures 1 - 3 shown, a denitration system using the waste heat of the flue gas from a copper smelting anode furnace includes an anode furnace, an air cooler, a dust collector, a hot flue gas cooling channel of a heat exchanger, a desulfurization tower 4, a demister 5, a cold flue gas heating channel of a heat exchanger, a flue gas preheater, and an SCR device that are connected in sequence through pipelines. The heat pipe evaporation section and the heat pipe condensation section of the heat exchanger are respectively arranged in the hot flue gas cooling channel and the cold flue gas heating channel of the heat exchanger. The demister adopts a wet electric demister or a water washing tower. The heat exchanger adopts a horizontal heat exchanger. The dust collector adopts a metal filter bag. The flue gas preheater adopts a natural gas combustion device 6. A induced draft fan 3 is connected between the hot flue gas cooling channel of the heat exchanger and the desulfurization tower.

[0021] As Figure 1 shown, when the present utility model is implemented, the flue gas of two anode furnaces is respectively connected to the air cooler, and the outlet flue gas temperature of the air cooler is controlled at 400 - 450 degrees Celsius.

[0022] After the flue gas is cooled, it enters the metal filter bag, and the temperature of the flue gas 1 after metal filter bag dust removal is controlled at 380 - 400 degrees Celsius, and the dust content in the flue gas is ≤ 10 mg / Nm 3 ;

[0023] The flue gas 1 after metal filter bag dust removal enters the hot end of the horizontal heat exchanger 2 and exchanges heat with the flue gas 7 (50°C - 70°C) at the outlet of the electric demister.

[0024] After heat exchange, the SCR inlet flue gas 8 is heated to 220°C to 260°C and enters the SRC device for denitrification. If the temperature of the outlet flue gas is difficult to rise to the range of 220°C to 260°C when heating the inlet flue gas of the SCR device through the horizontal heat exchanger 2 due to weather reasons or production reasons, the natural gas combustion device 6 should be started to supplement the heating and temperature rise.

[0025] The horizontal heat exchanger 2 is a horizontal parallel arrangement heat storage device based on heat pipes. During the heat storage condition, the flue gas 1 (380°C to 400°C) after metal mesh bag dust removal flows through the heat exchange channel of the horizontal heat exchanger 2. The gas conducts the heat in the flue gas to the heat pipe evaporation section 22 in the heat exchange channel through convective heat transfer. The heat of the heat pipe evaporation section 22 is conducted to the heat pipe condensation section 23; the dust in the flue gas falls into the ash hopper 21 for ash discharge; the heat of the heat pipe condensation section 23 is conducted to the heat storage body, and the flue gas 1 (380°C to 400°C) after metal mesh bag dust removal gradually cools down along the hot flue gas cooling channel 24 and finally discharges from the heat exchange device. The electric demisting outlet flue gas 7 (50°C to 70°C) rapidly heats up along the cold flue gas heating channel 25, and finally the SCR inlet flue gas 8 is heated to 220°C to 260°C.

[0026] The characteristic of the heat exchange process of the horizontal heat exchanger 2 is that the dust and heat are separated, and clean air is used for heat exchange during the heat release process, avoiding the ash accumulation in the cold flue gas heating channel 25. The structure of the hot flue gas cooling channel 24 is simple. Once the inside of the heat exchange channel is blocked, it can be solved by conventional means such as vibration, thus fundamentally avoiding the channel blockage.

[0027] The above-described embodiments are only a preferred solution of the present invention, and do not impose any form of limitation on the present invention. There are other variants and modifications without exceeding the technical solutions recorded in the claims.

Claims

1. A denitrification system utilizing waste heat from flue gas of anode furnace in copper smelting, characterized in that: It includes an anode furnace, an air cooler, a dust collector, a hot flue gas cooling channel of a heat exchanger, a desulfurization tower, a demister, a cold flue gas heating channel of a heat exchanger, a flue gas preheater, and an SCR device, which are sequentially connected through pipelines. The hot flue gas cooling channel of the heat exchanger and the cold flue gas heating channel of the heat exchanger are respectively provided with a heat pipe evaporation section and a heat pipe condensation section of the heat exchanger.

2. A denitrification system utilizing flue gas waste heat from anode furnace of copper smelting according to claim 1, characterized in that: The demister is a wet electric demister or a water washing tower.

3. The denitrification system using waste heat from flue gas of anode furnace of copper smelting according to claim 1 is characterized in that: The heat exchanger is a horizontal heat exchanger.

4. The denitrification system using waste heat from flue gas of anode furnace of copper smelting according to claim 1 is characterized in that: The dust collector adopts a metal filter bag.

5. The denitrification system using waste heat from flue gas of anode furnace of copper smelting according to claim 1 is characterized in that: The flue gas preheater adopts a natural gas combustion device.

6. The denitrification system using waste heat from flue gas of anode furnace of copper smelting according to claim 1 is characterized in that: An induced draft fan is connected between the hot flue gas cooling channel of the heat exchanger and the desulfurization tower.

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