System and method for comprehensive utilization of waste heat of Mannheim furnace

Abstract

The invention relates to the technical field of heat comprehensive utilization, and discloses a system for comprehensive utilization of waste heat of a Mannheim furnace. The system comprises a flue gas waste heat recovery unit and a calcium chloride solution concentration unit, the flue gas waste heat recovery unit is used for recovering tail gas flue gas waste heat of the Mannheim furnace for preheating combustion-supporting air or heating potassium chloride powder by the calcium chloride solution concentration unit; and the calcium chloride solution concentration unit is used for concentrating a low-concentration calcium chloride solution into a high-concentration calcium chloride solution through tail gas and flue gas waste heat of the Mannheim furnace. Through flue gas purification treatment, waste heat recovery and direct application to the calcium chloride concentration unit, the heat energy utilization efficiency can be remarkably improved, the energy consumption and the production cost are reduced, meanwhile, the environmental pollution is reduced, and powerful support is provided for sustainable development of potassium sulfate production enterprises. And energy conservation, emission reduction and sustainable development are realized.

Description

Technical Field

[0001] The present application relates to the technical field of comprehensive heat utilization, and more specifically, to a system and method for comprehensive utilization of waste heat from a Mannheim furnace. Background Art

[0002] The Mannheim furnace is a core piece of equipment in potassium sulfate production. Its primary principle is the reaction of sulfuric acid with potassium chloride to produce potassium sulfate and hydrogen chloride gas. However, during this reaction, the Mannheim furnace generates a significant amount of waste heat, including flue gas heat from the combustion chamber and residual heat released from the reaction chamber. If this waste heat is not effectively utilized, it will result in significant energy waste.

[0003] Waste heat from a Mannheim furnace primarily originates from the combustion chamber and reaction chamber. The flue gas from the combustion chamber typically reaches temperatures as high as 750°C, while the waste heat from the reaction chamber is around 350°C. After heat exchange, 200°C of residual heat remains. This waste heat is not only high in temperature but also generated in large quantities, possessing significant thermal energy value.

[0004] Currently, the comprehensive utilization technologies of Mannheim furnace waste heat mainly include the following: Flue gas energy recovery system: The flue gas heat generated in the combustion chamber is recovered through the flue gas heat exchanger to preheat the combustion air or heat potassium chloride powder, thereby increasing the temperature of the raw materials entering the reaction chamber and accelerating the reaction speed.

[0005] Cogeneration technology: Use cogeneration equipment to convert waste heat into electricity and thermal energy, achieving dual utilization of energy.

[0006] The above technologies have achieved the comprehensive utilization of waste heat to a certain extent, but there are still some shortcomings, such as large equipment investment, high maintenance costs, and low thermal energy utilization efficiency. Summary of the Invention

[0007] The purpose of the present invention is to provide a method for comprehensive utilization of waste heat from a Mannheim furnace with small equipment investment, low maintenance cost and high thermal energy utilization efficiency.

[0008] The object of the present invention is achieved as follows: In a first aspect, the present invention provides a system for comprehensive utilization of waste heat from a Mannheim furnace, comprising a flue gas waste heat recovery unit and a calcium chloride solution concentration unit; The flue gas waste heat recovery unit is used to recover the exhaust flue gas waste heat of the Mannheim furnace for use in the calcium chloride solution concentration unit to preheat the combustion air or heat potassium chloride powder; The calcium chloride solution concentration unit is used to concentrate a low-concentration calcium chloride solution into a high-concentration calcium chloride solution by utilizing the waste heat of the tail gas of the Mannheim furnace.

[0009] Furthermore, the flue gas waste heat recovery unit includes: High-efficiency flue gas heat exchanger, with its input end connected to the flue gas outlet of the Mannheim furnace. The high-efficiency flue gas heat exchanger recovers the waste heat in the process waste heat flue gas generated by the Mannheim furnace for preheating combustion-supporting air or heating potassium chloride powder; Flue gas induced draft fan, with its input end connected to the low-temperature tail gas outlet of the high-efficiency flue gas heat exchanger; Waste heat boiler, with its input end connected to the output end of the flue gas induced draft fan, for converting the waste heat of the low-temperature tail gas into secondary steam.

[0010] Furthermore, the high-efficiency flue gas heat exchanger is a multi-stage series heat exchanger, including: First-stage heat exchange section: reducing the flue gas temperature from 55°0C to 400°C, and the output heat is used to preheat combustion-supporting air; Second-stage heat exchange section: reducing the flue gas temperature from 400°C to 300°C, and the output heat is used to heat potassium chloride powder; Third-stage heat exchange section: reducing the flue gas temperature from 300°C to 200°C, and outputting the tail gas to the waste heat boiler.

[0011] Furthermore, the calcium chloride solution concentration unit includes: Preheating unit, connected to the output end of the waste heat boiler, and preheating the 15% low-concentration calcium chloride solution with the secondary steam generated by the waste heat boiler; Three-stage co-current heat exchange unit, with its input end connected to the output end of the preheating unit, for multi-stage heating of the calcium chloride solution; Calcium chloride concentration unit, with its input end connected to the output end of the three-stage co-current heat exchange unit, and outputting 35% high-concentration calcium chloride solution at the output end.

[0012] Furthermore, the calcium chloride concentration unit includes: Falling film evaporator: initially concentrating the calcium chloride solution with the heat output from the three-stage co-current heat exchange unit; Forced circulation evaporator: further concentrating the solution to 35% and then outputting.

[0013] In a second aspect, the present invention provides a method for comprehensive utilization of waste heat from a Mannheim furnace based on the system described in the first aspect, including the following steps: Recovering the waste heat of the 500°C - 550°C waste heat flue gas generated by the Mannheim furnace through a high-efficiency flue gas heat exchanger to generate 200°C - 300°C low-temperature tail gas; Introducing the low-temperature tail gas into a waste heat boiler to generate low-pressure secondary steam for preheating a 15% concentration calcium chloride solution; Concentrating the solution to 35% through three-stage co-current heat exchange and a calcium chloride concentration unit and then outputting.

[0014] In summary, the present application has the following beneficial effects: Through flue gas purification treatment, waste heat recovery, and direct use in the calcium chloride concentration unit, the present invention can significantly improve the thermal energy utilization efficiency, reduce energy consumption and production costs, and at the same time reduce environmental pollution, providing strong support for the sustainable development of potassium sulfate production enterprises. It realizes energy conservation, emission reduction, and sustainable development. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a schematic structural diagram of an embodiment of the present invention; Figure 2 is a schematic principle diagram of an embodiment of the present invention.

[0016] BRIEF DESCRIPTION OF THE DRAWINGS: 1. Mannheim furnace; 2. Flue gas heat exchanger; 3. Flue gas induced draft fan; 4. Combustion air blower; 5. Waste heat boiler. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0017] The following further details the structure and effects of the present application in conjunction with embodiments. It can be understood that the specific embodiments described herein are only used to explain the present invention, rather than limiting the present invention. Additionally, it should be noted that for the sake of description, only parts related to the present invention are shown in the drawings, rather than all the structures.

[0018] Embodiment:

[0019] The embodiment of the present application discloses a system for comprehensive utilization of waste heat from a Mannheim furnace, which includes a flue gas waste heat recovery unit and a calcium chloride solution concentration unit. The flue gas waste heat recovery unit is used to recover the waste heat of the tail gas flue gas of the Mannheim furnace for preheating combustion air or heating potassium chloride powder in the calcium chloride solution concentration unit; the calcium chloride solution concentration unit is used to concentrate the low-concentration calcium chloride solution into a high-concentration calcium chloride solution by the waste heat of the tail gas flue gas of the Mannheim furnace.

[0020] Referring to Figure 1 and Figure 2 , the flue gas waste heat recovery unit includes: a high-efficiency flue gas heat exchanger 2, the input end of which is connected to the flue gas outlet of the Mannheim furnace 1, and the high-efficiency flue gas heat exchanger 2 recovers the waste heat in the process waste heat flue gas generated by the Mannheim furnace 1 for preheating combustion air or heating potassium chloride powder; a flue gas induced draft fan 3, the input end of which is connected to the low-temperature tail gas outlet of the high-efficiency flue gas heat exchanger 2; a waste heat boiler 5, the input end of which is connected to the output end of the flue gas induced draft fan 2, and is used to convert the waste heat of the low-temperature tail gas into secondary steam.

[0021] In this embodiment, the high-efficiency flue gas heat exchanger 2 is a multi-stage series heat exchanger, including: a primary heat exchange section: preheating the flue gas from the flue gas preheating unit 6 from 550 °C to 400 °C, and outputting heat for preheating the combustion-supporting air; a secondary heat exchange section: reducing the flue gas from 400 °C to 300 °C, and outputting heat for heating potassium chloride powder; a tertiary heat exchange section: reducing the flue gas from 300 °C to 200 °C, and outputting the tail gas to the waste heat boiler 5.

[0022] Referring to Figure 1 and Figure 2 , the calcium chloride solution concentration unit includes: a preheating unit, connected to the output end of the waste heat boiler 5, and preheating the 15% low-concentration calcium chloride solution with the secondary steam generated by the waste heat boiler 5; a tertiary countercurrent heat exchange unit, with the input end connected to the output end of the preheating unit, for multi-stage heating of the calcium chloride solution; a calcium chloride concentration unit, with the input end connected to the output end of the tertiary countercurrent heat exchange unit, and outputting 35% high-concentration calcium chloride solution at the output end.

[0023] In this embodiment, the calcium chloride concentration unit includes: a falling film evaporator: preliminarily concentrating the calcium chloride solution by using the heat output by the tertiary countercurrent heat exchange unit; a forced circulation evaporator: further concentrating the solution to 35% and then outputting.

[0024] A method for comprehensive utilization of waste heat from a Mannheim furnace based on the system of this embodiment is as follows: The 500 °C - 550 °C process waste heat flue gas generated by the Mannheim furnace 1 is exchanged heat by the flue gas heat exchanger 2 into 200 °C - 300 °C low-temperature tail gas discharge heat source, introduced into the waste heat boiler 5 by the flue gas induced draft fan 3, and the waste heat boiler 5 generates low-pressure secondary steam to preheat the 15% calcium chloride solution, send it into the inlet of the tertiary countercurrent heat exchange unit, and output 35% calcium chloride solution through the outlet after tertiary countercurrent heat exchange and calcium chloride concentration unit.

[0025] After calculation, by using the system and method of the present invention, the waste heat generated by a 10,000 t Mannheim furnace device is utilized in the calcium chloride concentration system, which can reduce the heat consumption by 30%, reduce the total heat consumption, and improve the production efficiency.

[0026] The beneficial effect of the present invention is that the present invention uses the waste heat to concentrate the calcium chloride solution, directly uses the remaining 200 °C waste heat for the calcium chloride concentration unit, and realizes the concentration of the calcium chloride solution by using the waste heat. It can significantly improve the thermal energy utilization efficiency, reduce energy consumption and production costs, and at the same time reduce environmental pollution, providing strong support for the sustainable development of potassium sulfate production enterprises. Realize energy conservation, emission reduction and sustainable development.

[0027] This specific embodiment is only an interpretation of the present application and does not limit the present application. After reading this specification, those skilled in the art can make modifications to this embodiment without creative contributions as needed, but as long as it is within the scope of the claims of the present application, it is protected by the patent law.

Claims

1. A system for comprehensive utilization of waste heat from a Mannheim furnace, characterized in that, It includes a flue gas waste heat recovery unit and a calcium chloride solution concentration unit; The flue gas waste heat recovery unit is used to recover the waste heat of the tail gas of the Mannheim furnace for preheating combustion-supporting air or heating potassium chloride powder in the calcium chloride solution concentration unit; The calcium chloride solution concentration unit is used to concentrate the low-concentration calcium chloride solution into a high-concentration calcium chloride solution by the waste heat of the tail gas of the Mannheim furnace.

2. The system for comprehensive utilization of waste heat from a Mannheim furnace according to claim 1, characterized in that, The flue gas waste heat recovery unit includes: A high-efficiency flue gas heat exchanger, the input end of which is connected to the flue gas outlet of the Mannheim furnace, and the high-efficiency flue gas heat exchanger recovers the waste heat in the process waste heat flue gas generated by the Mannheim furnace for preheating combustion-supporting air or heating potassium chloride powder; A flue gas induced draft fan, the input end of which is connected to the low-temperature tail gas outlet of the high-efficiency flue gas heat exchanger; A waste heat boiler, the input end of which is connected to the output end of the flue gas induced draft fan, and is used to convert the waste heat of the low-temperature tail gas into secondary steam.

3. The system for comprehensive utilization of waste heat from a Mannheim furnace according to claim 2, wherein The high-efficiency flue gas heat exchanger is a multi-stage series heat exchanger, including: The first-stage heat exchange section: cools the flue gas from 550 °C to 400 °C, and the output heat is used to preheat combustion-supporting air; The second-stage heat exchange section: cools the flue gas from 400 °C to 300 °C, and the output heat is used to heat potassium chloride powder; The third-stage heat exchange section: cools the flue gas from 300 °C to 200 °C, and outputs the tail gas to the waste heat boiler.

4. The system for comprehensive utilization of waste heat of Mannheim furnace according to claim 1, characterized in that, The calcium chloride solution concentration unit includes: A preheating unit, which is connected to the output end of the waste heat boiler, and preheats the 15% low-concentration calcium chloride solution by the secondary steam generated by the waste heat boiler; A three-stage countercurrent heat exchange unit, the input end of which is connected to the output end of the preheating unit, and is used for multi-stage heating of the calcium chloride solution; A calcium chloride concentration unit, the input end of which is connected to the output end of the three-stage countercurrent heat exchange unit, and the output end outputs a 35% high-concentration calcium chloride solution.

5. The system for comprehensive utilization of waste heat from a Mannheim furnace according to claim 4, characterized in that, The calcium chloride concentration unit includes: A falling film evaporator: preliminarily concentrates the calcium chloride solution by using the heat output by the three-stage countercurrent heat exchange unit; A forced circulation evaporator: further concentrates the solution to 35% and then outputs it.

6. A method for comprehensive utilization of waste heat from a Mannheim furnace based on the system according to any one of claims 1-5, characterized in that, It includes the following steps: Recover the waste heat of the 500 °C - 550 °C waste heat flue gas generated by the Mannheim furnace through a high-efficiency flue gas heat exchanger to generate 200 °C - 300 °C low-temperature tail gas; Introduce the low-temperature tail gas into the waste heat boiler to generate low-pressure secondary steam and preheat the 15% concentration calcium chloride solution; Concentrate the solution to 35% through three-stage countercurrent heat exchange and the calcium chloride concentration unit and then output it.

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