An industrial flue gas preheating device

Abstract

The utility model discloses an industrial flue gas preheating device, including hot blast furnace, high temperature transition flue, heat exchanger, empty flue, combustion air fan, circulating fan, natural gas control valve group, process flue gas inlet pipe, outlet pipe etc. The natural gas control valve group controls and regulates the natural gas of entering hot blast furnace and the clean air of combustion air fan sending in and mixes according to the suitable proportion, and the hot flue gas of full combustion in hot blast furnace burner is mixed with the hot flue gas of circulating again of external circulating fan sending in hot blast furnace, and sends out from hot blast furnace outlet, first enters high temperature transition flue and carries out the buffer transition, and enters the upper air chamber of heat exchanger from high temperature transition flue outlet, then from top to bottom passes through the tube pass channel of heat exchanger, and the process flue gas from the process flue gas inlet of heat exchanger, from bottom to top through the shell pass channel of heat exchanger, carries out the reverse full heat exchange in heat exchanger, and finally process flue gas temperature is preheated to 420~520 DEG C and is discharged from the heat exchanger process flue gas outlet flue for industrial production.

Description

Technical Field

[0001] This utility model relates to the field of process flue gas treatment in the sulfuric acid industry, and specifically to an industrial flue gas preheating device. Background Technology

[0002] In sulfuric acid production, preheating of the process flue gas and catalyst layer in the conversion system, as well as supplemental heating when the conversion system is insufficient, are generally achieved through flue gas preheating devices.

[0003] Conventional flue gas preheating devices often suffer from the following problems in practical use: 1. The hot flue gas, which serves as the heat source for the preheating device, is entirely supplied by the continuous combustion of a certain fuel in the device's hot blast stove. Furthermore, the hot flue gas is directly discharged after heat exchange and not recycled, resulting in significant heat waste, low heat recycling rate, and failure to achieve energy conservation and environmental protection. 2. The hot blast stove and heat exchanger are directly connected. The 650℃ high-temperature flue gas sent from the hot blast stove enters the heat exchanger directly without a transition buffer process, causing continuous high-temperature burning and damage to the heat exchanger's main components such as the inlet chamber, tube sheet, and heat exchange tubes. This ultimately leads to the destruction of the heat exchanger, rendering the entire preheating device unable to function properly and causing significant economic losses to production. 3. The hot blast stove burner has a simple structure and single function, failing to achieve sufficient mixing and combustion of natural gas and combustion air. The resulting hot flue gas contains a large amount of free carbon and NO. X 4. The preheating device can only meet the short-term intermittent preheating requirements of small-volume process flue gas in small industrial production systems, and cannot meet the preheating requirements of large-volume process flue gas in large production systems.

[0004] Therefore, how to provide preheating for process flue gas in large-scale sulfuric acid industrial production systems under the premise of safety, efficiency, energy conservation, environmental protection, and continuous stability is a problem worthy of research. Utility Model Content

[0005] In view of this, the purpose of this utility model is to provide an industrial flue gas preheating device that can achieve safe, efficient, energy-saving, environmentally friendly, and continuous stable operation, and meet the preheating needs of process flue gas in large-scale industrial production.

[0006] To achieve the above objectives, this utility model provides the following technical solution: An industrial flue gas preheating device includes a hot blast stove, a heat exchanger, a combustion fan, a circulating fan, and a natural gas storage tank. The heat exchanger has an upper chamber at the top and a lower chamber at the bottom. A heat exchanger shell is located between the upper and lower chambers, and a heat exchanger tube bundle is installed inside the shell. The tube bundle communicates with the upper and lower chambers. A process flue gas inlet pipe is located at the bottom of the shell, and a process flue gas outlet pipe is located at the top. The hot blast stove has a natural gas inlet and an outlet pipe. The system includes a combustion air inlet, a circulating hot flue gas inlet and outlet. The hot blast stove outlet is connected to the upper chamber of the heat exchanger via a high-temperature transition flue. The lower chamber of the heat exchanger is connected to the inlet of the circulating fan via a pipe. The outlet of the circulating fan is connected to the circulating hot flue gas inlet of the hot blast stove via a pipe. The outlet of the combustion air blower is connected to the combustion air inlet of the hot blast stove via a pipe. The combustion air inlet of the hot blast stove is connected to the burner of the hot blast stove. The outlet of the natural gas storage tank is connected to the natural gas inlet of the hot blast stove via a pipe. The natural gas inlet is connected to the burner of the hot blast stove.

[0007] Furthermore, an vent pipe is installed on the inlet pipe of the circulating fan, and a natural gas control valve assembly is installed on the outlet pipe of the natural gas storage tank.

[0008] Furthermore, the high-temperature transition flue is composed of a stainless steel pipe and an internal high-temperature resistant castable material layer.

[0009] Furthermore, the bottom plate of the upper air chamber of the heat exchanger serves as the upper tube sheet of the heat exchanger tube bundle, and the top plate of the lower air chamber of the heat exchanger serves as the lower tube sheet of the heat exchanger tube bundle.

[0010] Furthermore, the upper chamber of the heat exchanger is made of steel, all pipe openings of the upper tube sheet are fitted with high-temperature resistant ceramic sleeves, and the inner wall of the upper chamber is provided with a layer of high-temperature resistant castable material.

[0011] Furthermore, the lower air chamber of the heat exchanger is made of steel, and several evenly distributed support pipes are provided inside the lower air chamber, with reinforcing ribs and reinforcing rings between the support pipes.

[0012] The natural gas supplied to the hot blast stove and the clean air supplied by the combustion blower are uniformly mixed in the burner by the natural gas control valve group on the outlet pipeline of the natural gas storage tank. The resulting hot flue gas, reaching up to 1000°C, is mixed with the recirculated hot flue gas (300-350°C) supplied by the circulating blower after heat exchange. The two are diluted, cooled, and mixed to form a high-temperature flue gas of about 650°C. Exiting the hot blast stove, the flue gas first enters a certain length of high-temperature transition flue for buffering. Then, it enters through the inlet of the upper chamber of the heat exchanger, flowing downwards through the tube side of the heat exchanger. It then mixes with the process flue gas inlet pipe of the heat exchanger, flowing upwards through the shell side of the heat exchanger at a temperature of 40-250°C, with a maximum temperature of 110,000 Nm³. 3The process flue gas with a flow rate of / h undergoes counter-current heat exchange in the heat exchanger. The process flue gas temperature is preheated to 420-520 ℃ and then discharged from the process flue gas outlet duct of the heat exchanger for industrial production. The hot flue gas is cooled to 300-350 ℃ and enters the circulating fan inlet duct from the lower gas chamber outlet of the heat exchanger. A small portion of it is no longer used and is directly discharged through the vent pipe, while most of it is pressurized again by the circulating fan and transported to the hot blast furnace for recycling.

[0013] Compared to traditional flue gas preheating devices, the main features of the flue gas preheating device provided in this application include: 1. The hot flue gas provided by the hot blast stove as a heat source consists of two types of flue gas. The first type is high-temperature hot flue gas at up to 1000℃ generated by burning natural gas in the hot blast stove. The second type is circulating hot flue gas at 300-350℃, which is pressurized and sent in by a circulating fan after heat exchange. The two types of flue gas are diluted, cooled, and mixed in the hot blast stove to form high-temperature flue gas at about 650℃ required for heat exchange. By using high-temperature flue gas to dilute high-temperature flue gas, the overall heat loss is small, the heat utilization rate is high, and energy saving and environmental protection are achieved. 2. The high-temperature flue gas at about 650℃ provided by the hot blast stove must pass through a high-temperature filter flue of a certain length for appropriate transition and buffering before entering the heat exchanger for flue gas heat exchange. This avoids the high-temperature flue gas sent from the hot blast stove directly entering the heat exchanger, which would continuously burn and damage the main components of the heat exchanger, such as the inlet chamber, tube sheet, and heat exchange tubes, ultimately leading to the destruction of the heat exchanger and the inability of the entire preheating device to work properly. 3. The hot air furnace burner achieves enhanced mixing of natural gas and combustion air, thereby reducing the excess air coefficient, enabling precise control of flame temperature through staged and segmented air distribution, and reducing harmful components such as free carbon and NO in the flue gas. X The generation of green and environmentally friendly operation. 4. The flue gas preheating device achieves a maximum of 110,000 Nm³ under the premise of high efficiency, safety, environmental protection, continuous operation, and stability. 3 Industrial production flue gas with a flow rate of / h is preheated from 40–250 °C to 420–520 °C. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the structure of the industrial flue gas preheating device of this utility model; In the diagram: 1. Circulating fan, 2. Combustion fan, 3. Hot blast stove, 4. Hot blast stove burner, 5. Natural gas control valve assembly, 6. Natural gas storage tank, 7. High-temperature transition flue, 8. Heat exchanger, 81. Upper chamber of heat exchanger, 82. Upper tube sheet, 83. Heat exchanger tube bundle, 84. Lower tube sheet, 85. Heat exchanger shell, 86. Lower chamber of heat exchanger, 9. Process flue gas outlet pipe, 10. Process flue gas inlet pipe, 11. Vent pipe. Detailed Implementation

[0015] The technical solution of this utility model will be further described in detail below with reference to the accompanying drawings, but the protection scope of this utility model is not limited thereto.

[0016] An industrial flue gas preheating device, such as Figure 1 As shown, the system includes a hot air furnace 3, a heat exchanger 8, a combustion air blower 2, a circulating air blower 1, and a natural gas storage tank 6. The heat exchanger 8 has an upper air chamber 81 at its top and a lower air chamber 86 at its bottom. A heat exchanger shell 85 is located between the upper air chamber 81 and the lower air chamber 86. A heat exchanger tube bundle 83 is housed within the heat exchanger shell 85. The bottom plate of the upper air chamber 81 serves as the upper tube sheet 82 of the heat exchanger tube bundle 83, and the top plate of the lower air chamber 86 serves as the lower tube sheet 84 of the heat exchanger tube bundle 83. All heat exchanger tube bundles 83 of the heat exchanger 8 are connected to the upper and lower tube sheets, thus communicating with the upper air chamber 81 and the lower air chamber 86. The lower part of the heat exchanger shell 85... The system includes a process flue gas inlet pipe 10 and a process flue gas outlet pipe 9 on the upper part of the heat exchanger shell 85. The hot blast stove 3 has a natural gas inlet, a combustion air inlet, a circulating hot flue gas inlet, and an outlet. The outlet of the hot blast stove 3 is connected to the upper chamber 81 of the heat exchanger via a high-temperature transition flue 7. The lower chamber 86 of the heat exchanger is connected to the inlet of the circulating fan 1 via a pipe. The outlet of the circulating fan 1 is connected to the circulating hot flue gas inlet of the hot blast stove 3 via a pipe. The outlet of the combustion air fan 2 is connected to the combustion air inlet of the hot blast stove via a pipe. The combustion air inlet of the hot blast stove is connected to the burner 4 of the hot blast stove. The outlet of the natural gas storage tank 6 is connected to the natural gas inlet of the hot blast stove via a pipe. The natural gas inlet is connected to the burner 4 of the hot blast stove. An vent pipe 11 is installed on the inlet pipe of the circulating fan 1, and a natural gas control valve assembly 5 is installed on the outlet pipe of the natural gas storage tank 6.

[0017] The heat exchanger 8 has a shell-and-tube structure with two flue gas passages inside: the tube side and the shell side. The upper gas chamber 81, the upper tube sheet 82, the tube space of all heat exchange tube bundles 83, the lower tube sheet 84, and the lower gas chamber 86 constitute the tube side passage for hot flue gas inside the heat exchanger 8. The upper tube sheet 82, the lower tube sheet 84, the shell 85 connecting the upper and lower tube sheets, and the tube space outside all heat exchange tube bundles 83 constitute the shell side passage for process flue gas inside the heat exchanger 8.

[0018] The high-temperature transition flue 7 is a section of 304 stainless steel pipe, with the inner wall of the pipe entirely lined with a certain thickness of high-temperature resistant castable material. The function of the high-temperature transition flue 7 is to provide a proper transition and buffer for the 650 ℃ mixed high-temperature flue gas provided by the hot blast stove 3 before sending it into the upper air chamber 81 of the heat exchanger.

[0019] The upper air chamber 81 of the heat exchanger is made of 304 stainless steel, the upper tube sheet 82 is made of 304 stainless steel, all tube openings of the upper tube sheet 82 are equipped with high-temperature resistant ceramic sleeves, and the surface of the tube sheet is cast with a certain thickness of high-temperature resistant casting material. The inner wall of the upper air chamber 81 is entirely cast with a certain thickness of high-temperature resistant casting material.

[0020] The lower air chamber 86 of the heat exchanger is made of Q345B material, the lower tube sheet 84 is made of Q345B material, and a certain number of evenly distributed support tubes are provided between the lower tube sheet 84 and the bottom of the lower air chamber 86. The support tubes are made of Q345B material, and Q345B reinforcing ribs and reinforcing rings are provided between all the support tubes. All the support tubes are connected to form a rigid support body for firmly supporting the lower tube sheet 84 of the heat exchanger.

[0021] The heat exchanger shell 85 is made of Q345B, and the heat exchanger tube bundle 83 is made of No. 20 aluminized tube.

[0022] Heat exchanger 8 is a shell-and-tube heat exchanger. Hot flue gas flows from top to bottom through the tube side of heat exchanger 8, while process gas flows from bottom to top through the shell side of heat exchanger 8. The two types of flue gas exchange heat in countercurrent flow within heat exchanger 8.

[0023] The hot air furnace 3 consists of a burner 4 and a furnace body. The burner 4 is made of heat-resistant stainless steel, and the furnace body is made of Q345B material. The inner wall of the furnace is lined with high-temperature refractory bricks and refractory material. The burner 4 achieves enhanced mixing and complete combustion of natural gas and combustion air, thereby reducing the excess air coefficient. It also enables precise control of flame temperature through staged and segmented air distribution, reducing harmful components such as free carbon and NO in the flue gas. X Its generation and operation are green and environmentally friendly.

[0024] The circulating fan 1 forces most of the hot flue gas after heat exchange in the lower air chamber 86 of the heat exchanger into the hot air furnace 3, diluting and cooling the high-temperature flue gas in the furnace at 1000 ℃ to 650 ℃ before circulating it for heat exchange. By using high-temperature flue gas to dilute high-temperature flue gas, the overall heat loss is small, the heat utilization rate is high, and it is energy-saving and environmentally friendly.

[0025] The combustion-supporting fan 2 delivers an appropriate amount of clean air into the hot air furnace burner 4, thereby achieving enhanced mixing and complete combustion of air and natural gas, and providing precise control of flame temperature through graded and segmented air distribution.

[0026] The natural gas storage tank 6 is a low-pressure vertical storage tank for storing natural gas fuel, stabilizing the natural gas pressure, and providing natural gas fuel for the high-temperature flue gas generated by the hot blast stove 3.

[0027] The exhaust pipe 11 is a pipe that directly discharges a small portion of the hot flue gas sent out from the lower air chamber 86 of the heat exchanger after heat exchange, which is no longer needed. The exhaust pipe 11 is located on the inlet pipe of the circulating fan 1 and is made of Q345B.

[0028] The natural gas supplied to the hot blast stove 3 and the clean air supplied by the combustion blower 2 are uniformly mixed in the burner 4 by the natural gas control valve group 5 on the outlet pipeline of the natural gas storage tank 6. The hot flue gas of about 1000°C generated by the complete combustion is mixed with the recycled hot flue gas of 300-350°C after heat exchange supplied by the circulating blower 1. The two are diluted, cooled and mixed to form a high temperature flue gas of about 650°C. The flue gas exits from the hot blast stove 3 and first enters a certain length of high temperature transition flue 7 for transition and buffering. Then it enters through the inlet of the upper air chamber 81 of the heat exchanger and passes through the tube side channel of the heat exchanger 8 from top to bottom. It enters through the process flue gas inlet pipe 10 of the heat exchanger and passes through the shell side channel of the heat exchanger 8 from bottom to top. The maximum temperature is 110,000 Nm³. 3 The process gas, with a flow rate of / h, undergoes counter-current heat exchange in the heat exchanger 8. The process gas temperature is preheated to 420-520℃ and then discharged from the process flue gas outlet pipe 9 of the heat exchanger for industrial production. The hot flue gas is cooled to 300-350℃ and enters the inlet flue of the circulating fan 1 from the outlet of the lower gas chamber 86 of the heat exchanger. A small portion of the flue gas is no longer used and is directly discharged through the vent pipe 11. Most of the flue gas is pressurized again by the circulating fan 1 and transported to the hot blast furnace 3 for recycling.

[0029] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the specific implementation of this utility model and not to limit it. Those skilled in the art should understand that any equivalent substitutions or obvious modifications made to the implementation of this utility model without changing its performance or use, without violating the spirit of this utility model, should be covered within the scope of protection claimed by this utility model.

Claims

1. An industrial flue gas preheating device, characterized in that, The system includes a hot blast stove, a heat exchanger, a combustion air blower, a circulating air blower, and a natural gas storage tank. The heat exchanger has an upper chamber at the top and a lower chamber at the bottom. A heat exchanger shell connects the upper and lower chambers, and a heat exchanger tube bundle is housed within the shell. The tube bundle communicates with the upper and lower chambers. A process flue gas inlet pipe is located at the bottom of the shell, and a process flue gas outlet pipe is located at the top. The hot blast stove has a natural gas inlet and a combustion air inlet. The circulating hot flue gas inlet and outlet are connected as follows: the hot blast stove outlet is connected to the upper chamber of the heat exchanger via a high-temperature transition flue; the lower chamber of the heat exchanger is connected to the inlet of the circulating fan via a pipe; the outlet of the circulating fan is connected to the circulating hot flue gas inlet of the hot blast stove via a pipe; the outlet of the combustion air blower is connected to the combustion air inlet of the hot blast stove via a pipe; the combustion air inlet of the hot blast stove is connected to the burner of the hot blast stove; the outlet of the natural gas storage tank is connected to the natural gas inlet of the hot blast stove via a pipe; and the natural gas inlet is connected to the burner of the hot blast stove.

2. The industrial flue gas preheating device according to claim 1, characterized in that, An vent pipe is installed on the inlet pipe of the circulating fan, and a natural gas control valve assembly is installed on the outlet pipe of the natural gas storage tank.

3. The industrial flue gas preheating device according to claim 1, characterized in that, The high-temperature transition flue consists of a stainless steel pipe and an inner layer of high-temperature resistant castable material.

4. The industrial flue gas preheating device according to claim 1, characterized in that, The bottom plate of the upper air chamber of the heat exchanger serves as the upper tube sheet of the heat exchanger tube bundle, and the top plate of the lower air chamber of the heat exchanger serves as the lower tube sheet of the heat exchanger tube bundle.

5. The industrial flue gas preheating device according to claim 4, characterized in that, The upper chamber of the heat exchanger is made of steel, and all pipe openings of the upper tube sheet are fitted with high-temperature resistant ceramic sleeves. The inner wall of the upper chamber is provided with a layer of high-temperature resistant castable material.

6. The industrial flue gas preheating device according to claim 4, characterized in that, The lower chamber of the heat exchanger is made of steel, and several evenly distributed support tubes are provided inside the lower chamber. Reinforcing ribs and reinforcing rings are provided between the support tubes.

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