Heating system of gaseous suspension roaster

Abstract

A heating system of a gaseous suspension roaster relates to the technical field of gaseous suspension roasting and comprises a first-section cyclone cooling system and a roaster PO4, the first-section cyclone cooling system comprises a cyclone cooler CO1, a cyclone cooler CO2, a cyclone cooler CO3 and a cyclone cooler CO4, preheated air of the cyclone cooler CO1 is connected with the roaster PO4 through a pipeline, and preheated air of the cyclone cooler CO2 is connected with the roaster PO4 through a pipeline. A first auxiliary electric heater, a first expansion joint and a second auxiliary electric heater are sequentially arranged on a downcomer in a connecting air pipe from the cyclone cooler CO1 to the main furnace PO4 in the direction from the cyclone cooler CO1 to the main furnace PO4; and a second expansion joint and a main electric heater are sequentially arranged on an ascending pipe in a connecting air pipe from the cyclone cooler CO1 to the main furnace PO4 in the direction from the cyclone cooler CO1 to the main furnace PO4. The electric heater is arranged on the air pipe for connecting the cyclone cooler CO1 to the main furnace PO4, so that the consumption of fossil energy is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of gaseous suspension roasting, in particular to a heating system of a gaseous suspension roasting furnace. Background Art

[0002] Gas suspension roaster is widely used in the alumina industry and has also been used in the field of iron ore magnetization roasting in recent years. Gas suspension roaster is mainly used in the alumina industry to roast aluminum hydroxide into alumina. The main process flow is as follows: Figure 1 As shown in the figure, aluminum hydroxide from the flat disc filter is conveyed by a belt conveyor into the aluminum hydroxide receiving silo L01. The discharged aluminum hydroxide is metered by a quantitative feeder at the bottom of the silo and fed by a feeding screw conveyor into the Venturi dryer AO2. The hydrous aluminum hydroxide is dispersed and rapidly dried by the hot gas from the cyclone preheater PO2. The dried aluminum hydroxide and water vapor mixture enters the cyclone separator PO1 through a flow-carrying pipe. After separation, the dried aluminum hydroxide is thoroughly mixed with the hot gas from the cyclone separator PO3 and enters the cyclone preheater PO2 for preheating and partial roasting. The material separated from the cyclone preheater PO2 enters the roasting furnace PO4 along the inclined wall parallel to the cone of PO4.

[0003] The roaster utilizes coal gas or natural gas as fuel, entering the furnace from the side below the cone. Combustion-supporting air, preheated by the cyclone cooling system, enters the furnace from the bottom of the cone. The material remains in the furnace for only a few seconds before being carried out of the roaster by the high-temperature gases from above and directly into the adjacent cyclone separator PO3. The calcined alumina is separated from the hot gases and enters a cyclone cooling system. The hot gases separated from the cyclone separator enter the cyclone preheater PO2.

[0004] Primary cooling occurs in a four-stage cyclone cooler. The calcined alumina passes from top to bottom through the vertically arranged four-stage cyclone coolers (CO1, CO2, CO3, and CO4), undergoing a thorough countercurrent heat exchange with the cold air from the CO4 inlet from bottom to top. After primary cyclone cooling, the alumina enters the cooler for secondary cooling. After indirect countercurrent cooling with water, the finished alumina (at approximately 80°C) is sent to the alumina storage and transportation process. The flue gas from the aluminum hydroxide roaster is dedusted by a dust collector and discharged through a chimney. The collected dust is returned to the CO2 through the ash return system.

[0005] The above production method consumes a lot of energy. The energy consumption of the aluminum hydroxide roasting process accounts for about 30% of the total energy consumption of the plant, and the energy consumption of purchased electricity accounts for about 6% of the total energy consumption of the plant. It cannot meet the energy saving requirements. Summary of the Invention

[0006] In view of the above-mentioned shortcomings and deficiencies of the prior art, the present invention provides a gas suspension roasting furnace heating system, which reduces the consumption of fossil energy by arranging an electric heater on the air duct connecting the cyclone cooler CO1 to the main furnace PO4.

[0007] In order to achieve the above objectives, the main technical solutions adopted by the present invention include: A gaseous suspension roaster heating system includes a cyclone cooling system and a roaster PO4. The cyclone cooling system includes four cyclone coolers arranged vertically in order from top to bottom, namely, cyclone cooler CO1, cyclone cooler CO2, cyclone cooler CO3, and cyclone cooler CO4. The preheated air of the cyclone cooler CO1 is connected to the roaster PO4 through a pipeline. On the downcomer in the air duct connecting the cyclone cooler CO1 to the main furnace PO4, a first auxiliary electric heater, a first expansion joint, and a second auxiliary electric heater are sequentially arranged from the cyclone cooler CO1 to the main furnace PO4; on the riser in the air duct connecting the cyclone cooler CO1 to the main furnace PO4, a second expansion joint and a main electric heater are sequentially arranged from the cyclone cooler CO1 to the main furnace PO4.

[0008] Furthermore, the first auxiliary electric heater, the second auxiliary electric heater, and the main electric heater include several ceramic electric heaters.

[0009] Furthermore, the first auxiliary electric heater, the second auxiliary electric heater, and the main electric heater are composed of 4-30 ceramic electric heaters.

[0010] Furthermore, each ceramic electric heater among the first auxiliary electric heater, the second auxiliary electric heater and the main electric heater is independently powered and controlled and is embedded in the air duct.

[0011] Furthermore, each ceramic electric heater is arranged in the air duct along the radial direction of the air duct, and a plurality of ceramic electric heaters are arranged in a circular pattern in the air duct.

[0012] Furthermore, the power of the first auxiliary electric heater, the second auxiliary electric heater, and the main electric heater is 5kW to 50MW.

[0013] Furthermore, the first expansion joint and the second expansion joint are metal expansion joints, which are resistant to high temperatures of 1000°C and above.

[0014] Furthermore, the first auxiliary electric heater heats the CO1 discharge air to 700-750°C, the second auxiliary electric heater heats the CO1 discharge air to 800-850°C, and the main electric heater heats the CO1 discharge air to 950-1000°C.

[0015] Furthermore, the CO1 discharge air heated by the main electric heater is heated to 1050-1100°C by gas and fed into the main furnace PO4.

[0016] The beneficial effect of the present invention is that the gas suspension roasting furnace heating system provided by the present invention reduces the consumption of fossil energy by arranging an electric heater on the air duct connecting the cyclone cooler CO1 to the main furnace PO4. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of the heating system of an existing gas suspension roasting furnace; Figure 2 Schematic diagram of the gas suspension roasting furnace heating system of the present invention; Figure 3 This is a schematic diagram of the distribution of ceramic electric heaters in the air duct.

[0018] In the figure: 1 is the first auxiliary electric heater, 2 is the first expansion joint, 3 is the second auxiliary electric heater, 4 is the second expansion joint, and 5 is the main electric heater. DETAILED DESCRIPTION

[0019] In order to better explain the present invention and facilitate understanding, the present invention is described in detail below through specific implementation methods in conjunction with the accompanying drawings.

[0020] The present invention provides a gas suspension roasting furnace heating system. Three electric heaters are added before the gas burner on the air duct from the cyclone cooler CO1 to the main furnace PO4. Before the preheated air from CO1 enters the main furnace PO4, it is first heated by the electric heater and then heated by gas to the temperature required by the main furnace PO4, or directly heated by the electric heater to the temperature required by the main furnace PO4. Figure 2 As shown, the system includes a cyclone cooling system and a roasting furnace PO4. The system comprises four cyclone coolers arranged vertically from top to bottom: cyclone cooler CO1, cyclone cooler CO2, cyclone cooler CO3, and cyclone cooler CO4. The preheated air from cyclone cooler CO1 is connected to roasting furnace PO4 via a pipeline. A first auxiliary electric heater 1, a first expansion joint 2, and a second auxiliary electric heater 3 are sequentially installed on the downpipe connecting the cyclone cooler CO1 to the main furnace PO4, from cyclone cooler CO1 toward the main furnace PO4. A second expansion joint 4 and a main electric heater 5 are sequentially installed on the riser of the cyclone cooler CO1-main furnace PO4, from cyclone cooler CO1 toward the main furnace PO4. The expansion joints compensate for duct deformation caused by temperature changes.

[0021] Specifically, the first auxiliary electric heater 1, the second auxiliary electric heater 3, and the main electric heater 5 include several ceramic electric heaters. More specifically, the first auxiliary electric heater 1, the second auxiliary electric heater 3, and the main electric heater 5 are composed of 4-30 ceramic electric heaters. They use high thermal conductivity alumina ceramic as the outer shell and heat-resistant, refractory, and oxidation-resistant nickel-chromium alloy as the internal resistor to form a heating circuit. The outer shell alumina ceramic can protect the internal resistor from the abrasion of dust in the wind. The power of the first auxiliary electric heater 1, the second auxiliary electric heater 3, and the main electric heater 5 is 5kW to 50MW. Each ceramic electric heater in the first auxiliary electric heater 1, the second auxiliary electric heater 3, and the main electric heater 5 is independently powered, individually controlled, and embedded in the air duct.

[0022] Specifically, if Figure 3 As shown, each ceramic electric heater is arranged in the air duct along the radial direction of the air duct, and several ceramic electric heaters are arranged in a circular pattern in the air duct.

[0023] Specifically, the first expansion joint 2 and the second expansion joint 4 are metal expansion joints, and the material may be stainless steel 310S, which is resistant to high temperatures of 1000° C. and above.

[0024] After passing through the first auxiliary electric heater 1, the CO1 discharge air temperature can be raised from 600-650°C to 700-750°C; after being heated by the second auxiliary electric heater 3, the temperature can be raised to 800-850°C; after being heated by the main electric heater 5, the temperature can be raised to 950-1000°C. Finally, heating with gas can raise the temperature to 1050-1100°C, which can meet the production requirements of the process. The present invention reduces fossil energy consumption by installing an electric heater on the air duct connecting the cyclone cooler CO1 to the main furnace PO4.

[0025] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limiting the present invention. Any changes, modifications, substitutions and variations of the above embodiments by a person skilled in the art fall within the scope of the present invention.

Claims

1. A gaseous suspension roaster heating system, comprising a first-stage cyclone cooling system and a roaster PO4. The first-stage cyclone cooling system comprises four cyclone coolers arranged vertically from top to bottom, namely, cyclone cooler CO1, cyclone cooler CO2, cyclone cooler CO3, and cyclone cooler CO4. The preheated air from cyclone cooler CO1 is connected to the roaster PO4 via a pipeline. The system is characterized by: On the downcomer in the air duct connecting the cyclone cooler CO1 to the main furnace PO4, a first auxiliary electric heater, a first expansion joint, and a second auxiliary electric heater are sequentially arranged from the cyclone cooler CO1 to the main furnace PO4; on the upcomer in the air duct connecting the cyclone cooler CO1 to the main furnace PO4, a second expansion joint and a main electric heater are sequentially arranged from the cyclone cooler CO1 to the main furnace PO4.

2. The gaseous suspension roasting furnace heating system according to claim 1, characterized in that: The first auxiliary electric heater, the second auxiliary electric heater and the main electric heater include a plurality of ceramic electric heaters.

3. The gas suspension roasting furnace heating system according to claim 2, characterized in that: The first auxiliary electric heater, the second auxiliary electric heater and the main electric heater are composed of 4-30 ceramic electric heaters.

4. A gaseous suspension roasting furnace heating system according to claim 2 or 3, characterized in that: Each ceramic electric heater among the first auxiliary electric heater, the second auxiliary electric heater and the main electric heater is independently powered and controlled and is embedded in the air duct.

5. The gaseous suspension roasting furnace heating system according to claim 4, characterized in that: Each ceramic electric heater is arranged in the air duct along the radial direction of the air duct, and a plurality of ceramic electric heaters are arranged in a circumferential manner in the air duct.

6. The gaseous suspension roasting furnace heating system according to claim 1, characterized in that: The power of the first auxiliary electric heater, the second auxiliary electric heater and the main electric heater is 5kW to 50MW.

7. The gaseous suspension roasting furnace heating system according to claim 1, characterized in that: The first expansion joint and the second expansion joint are metal expansion joints, which are resistant to high temperatures of 1000°C and above.

8. The gaseous suspension roasting furnace heating system according to claim 1, characterized in that: The first auxiliary electric heater heats the CO1 discharge air to 700-750°C, the second auxiliary electric heater heats the CO1 discharge air to 800-850°C, and the main electric heater heats the CO1 discharge air to 950-1000°C.

9. The gaseous suspension roasting furnace heating system according to claim 1, characterized in that: The CO1 discharge air heated by the main electric heater is heated to 1050-1100℃ by gas and sent to the main furnace PO4.

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