Low-nitrogen internal circulation fused salt heating device for solid caustic soda concentration

Abstract

The utility model relates to the technical field of solid caustic soda heating concentration, in particular to a low-nitrogen internal circulation fused salt heating device for solid caustic soda concentration, which comprises a fused salt furnace, a low-nitrogen burner, a fused salt tank and an alkali concentrator. A first fused salt pipeline is communicated between the fused salt tank and the fused salt furnace, a second fused salt pipeline is communicated between the fused salt furnace and the alkali concentrator, a third fused salt pipeline is communicated between the alkali concentrator and the fused salt tank, a fourth fused salt pipeline is communicated between the second fused salt pipeline and the fused salt tank, and the alkali concentrator is communicated with a first alkali liquor pipeline. And the alkali concentrator is communicated with a second alkali liquor pipeline. The molten salt furnace is reasonable and compact in structure and convenient to use, the content of nitric oxide (NOX) in the molten salt furnace is reduced, the heat efficiency of the molten salt furnace is improved, the natural gas cost input of solid caustic soda production is reduced, and pollution to the atmospheric environment is reduced.

Description

Technical Field

[0001] This utility model relates to the field of solid alkali heating and concentration technology, and is a low-nitrogen internal circulation molten salt heating device for solid alkali concentration. Background Technology

[0002] A chemical company uses a high-temperature molten salt method to concentrate 48% alkali solution obtained from evaporation in an evaporator into 98.5% alkali solution. This alkali solution is then processed into flakes and packaged to obtain the final caustic soda flake product. The high-temperature molten salt method involves introducing fuel into a combustion furnace and igniting it. The combustion flame heats the molten salt, and the resulting high-temperature molten salt is then transported to an alkali concentration device for further alkali concentration.

[0003] Currently, the combustion of natural gas in a natural gas furnace produces a large amount of nitrogen oxides (NOx). X ), nitrogen oxides (NO) X Increasing this number will have the following drawbacks:

[0004] 1. Reduced combustion efficiency

[0005] NO X The generation of oxygen consumes some of the oxygen in the combustion furnace, reducing the amount of oxygen available for combustion, resulting in incomplete combustion of natural gas and reducing the thermal efficiency of the combustion furnace.

[0006] II. Increased energy consumption

[0007] To maintain the combustion temperature in the furnace, the supply of natural gas needs to be increased, leading to higher energy costs.

[0008] III. Factors Affecting Combustion Stability

[0009] NO in the combustion furnace X An increase in this amount will alter combustion dynamics, affect the stability of the flame inside the furnace, and increase the risk of flameout or backfire inside the furnace.

[0010] IV. Increased Pollution Emissions

[0011] NO X It is itself a pollutant, NO X Increased levels will exacerbate environmental pollution and may also react with other substances to generate secondary pollutants.

[0012] V. Corrosion Equipment

[0013] NO X When combined with water vapor, it forms nitric acid, which corrodes the internal components of the combustion furnace and shortens the equipment's lifespan.

[0014] VI. Affecting heat transfer

[0015] NO X Increasing the amount of heat transfer will alter the temperature distribution inside the furnace, affecting heat transfer efficiency and further reducing the combustion effect of natural gas inside the furnace.

[0016] In combustion furnaces fueled by natural gas, nitrogen oxides (NOx) are produced. X The main issue is that nitrogen in the air oxidizes to form nitrogen oxides under high temperatures, while NO in a natural gas combustion furnace... X The main influencing factors of the content are: first, the flame temperature in the combustion furnace and the natural gas combustion time under high temperature conditions; and second, the oxygen concentration in the flame combustion zone of the combustion furnace.

[0017] Therefore, reducing nitrogen oxides (NOx) in the combustion furnace X Improving the content of alkali, increasing the thermal efficiency of combustion furnaces, reducing input costs, and mitigating environmental pollution have become urgent technical challenges for solid alkali production enterprises. Summary of the Invention

[0018] This invention provides a low-nitrogen internal circulation molten salt heating device for solid alkali concentration, which overcomes the shortcomings of the prior art and can effectively solve the problems of low thermal efficiency, high cost, and environmental pollution caused by the increase of nitrogen oxides in the combustion furnace used for solid alkali concentration.

[0019] The technical solution of this utility model is achieved through the following measures: A low-nitrogen internal circulation molten salt heating device for solid alkali concentration includes a molten salt furnace, a low-nitrogen burner, a molten salt tank, and an alkali concentrator. A low-nitrogen burner is installed at the top inlet of the molten salt furnace, and a natural gas input pipeline is fixedly connected to the top inlet of the low-nitrogen burner. A first molten salt pipeline is fixedly connected between the top outlet of the molten salt tank and the lower inlet of the molten salt furnace. A second molten salt pipeline is fixedly connected between the upper outlet of the molten salt furnace and the upper inlet of the alkali concentrator. A third molten salt pipeline is fixedly connected between the lower outlet of the alkali concentrator and the first inlet at the top of the molten salt tank. A fourth molten salt pipeline is fixedly connected between the second molten salt pipeline and the second inlet at the top of the molten salt tank. A first alkali solution pipeline is fixedly connected to the top inlet of the alkali concentrator, and a second alkali solution pipeline is fixedly connected to the bottom outlet of the alkali concentrator.

[0020] The following are further optimizations and / or improvements to the above-mentioned utility model technical solution:

[0021] The aforementioned device also includes an air preheater, with a first combustion-supporting pipeline fixedly connected between the upper outlet of the air preheater and the upper inlet of the molten salt furnace, and a first return pipeline fixedly connected between the lower outlet of the molten salt furnace and the lower inlet of the air preheater.

[0022] The lower inlet of the air preheater is fixedly connected to a second combustion-supporting pipeline, and the top outlet of the air preheater is fixedly connected to a vent pipeline. A second return pipeline is fixedly connected between the vent pipeline and the second combustion-supporting pipeline.

[0023] The third inlet at the top of the molten salt tank is fixedly connected to a nitrogen input pipeline.

[0024] A molten salt pump is fixedly installed on the first molten salt pipeline, and an air pump is fixedly installed on the second combustion-supporting pipeline and the second return pipeline between the second return pipeline and the lower inlet of the air preheater.

[0025] Control valves are fixedly installed on the second molten salt pipeline, the fourth molten salt pipeline, and the nitrogen input pipeline between the fourth molten salt pipeline and the upper inlet of the alkali concentrator.

[0026] Temperature gauges are fixedly installed on both the air preheater and the molten salt furnace.

[0027] A pressure gauge is fixedly installed on the aforementioned molten salt tank.

[0028] A flow meter is fixedly installed on the aforementioned natural gas input pipeline.

[0029] The aforementioned device also includes a controller, and the molten salt pump, air pump, control valve, thermometer, pressure gauge, and flow meter are all electrically connected to the controller.

[0030] This utility model has a reasonable and compact structure and is easy to use. It uses a low-NOx burner to burn natural gas, and the combustion flame spreads completely inside the molten salt furnace. Furthermore, the molten salt furnace employs a top-down flue gas recirculation mode, which helps reduce the oxygen concentration in the flame zone and thus reduces nitrogen oxides (NOx) levels within the furnace. X The content of ) improves the thermal efficiency of molten salt furnaces, reduces the natural gas cost of solid alkali production, and also reduces pollution to the atmospheric environment. Attached Figure Description

[0031] Appendix Figure 1 This is a schematic diagram of the process flow of this utility model.

[0032] Appendix Figure 1 The codes in the diagram are as follows: 1 for molten salt furnace, 2 for low-NOx burner, 3 for molten salt tank, 4 for alkali concentrator, 5 for natural gas input pipeline, 6 for first molten salt pipeline, 7 for second molten salt pipeline, 8 for third molten salt pipeline, 9 for fourth molten salt pipeline, 10 for first alkali solution pipeline, 11 for second alkali solution pipeline, 12 for air preheater, 13 for first combustion-supporting pipeline, 14 for first return pipeline, 15 for second combustion-supporting pipeline, 16 for second return pipeline, 17 for nitrogen input pipeline, 18 for molten salt pump, 19 for air pump, 20 for control valve, 21 for thermometer, 22 for pressure gauge, 23 for flow meter, and 24 for vent pipeline. Detailed Implementation

[0033] This utility model is not limited to the following embodiments, and the specific implementation method can be determined according to the technical solution of this utility model and the actual situation.

[0034] Unless otherwise specified, all equipment and devices used in this invention are existing, publicly known, and commonly used equipment and devices in the field.

[0035] In this utility model, for ease of description, the description of the relative positions of the components is based on the appendix to the specification. Figure 1 The layout is described using a diagrammatic method, such as the positional relationships of front, back, top, bottom, left, and right, which are based on the instructions attached. Figure 1 The orientation of the layout is determined by the direction of the map.

[0036] The present invention will be further described below with reference to the embodiments and accompanying drawings:

[0037] Example 1: As shown in the attached document Figure 1 As shown, the low-NOx internal circulation molten salt heating device for solid alkali concentration includes a molten salt furnace 1, a low-NOx burner 2, a molten salt tank 3, and an alkali concentrator 4. The low-NOx burner 2 is installed at the top inlet of the molten salt furnace 1, and a natural gas input pipeline 5 is fixedly connected to the top inlet of the low-NOx burner 2. A first molten salt pipeline 6 is fixedly connected between the top outlet of the molten salt tank 3 and the lower inlet of the molten salt furnace 1. A second molten salt pipeline 7 is fixedly connected between the upper outlet of the molten salt furnace 1 and the upper inlet of the alkali concentrator 4. A third molten salt pipeline 8 is fixedly connected between the lower outlet of the alkali concentrator 4 and the first inlet at the top of the molten salt tank 3. A fourth molten salt pipeline 9 is fixedly connected between the second molten salt pipeline 7 and the second inlet at the top of the molten salt tank 3. A first alkali solution pipeline 10 is fixedly connected to the top inlet of the alkali concentrator 4, and a second alkali solution pipeline 11 is fixedly connected to the bottom outlet of the alkali concentrator 4.

[0038] As required, the low-NOx burner 2 is a low-NOx type burner. The low-NOx burner 2 can fully expand the flame inside the furnace of the molten salt furnace 1. The flame shape is spindle-shaped. Through the multi-inclined tube flame jet, the flame is pushed to a fixed height. The flame adhesion effect of the low-NOx burner 2 is reflected in the fact that the number of nozzles at the lower adhesion point of the central flame reaches up to 8. The flame nozzles are multiple nozzle holes. The inner diameter of the low-NOx burner 2 is 640mm.

[0039] The above-mentioned low-nitrogen internal circulation molten salt heating device for solid alkali concentration can be further optimized and / or improved according to actual needs:

[0040] Example 2: Its difference from Example 1 is as follows: (See attached) Figure 1 As shown, the device also includes an air preheater 12, with a first combustion-supporting pipeline 13 fixedly connected between the upper outlet of the air preheater 12 and the upper inlet of the molten salt furnace 1, and a first return pipeline 14 fixedly connected between the lower outlet of the molten salt furnace 1 and the lower inlet of the air preheater 12.

[0041] Example 3: Its difference from Examples 1 to 2 is as follows: (See attached) Figure 1As shown, the lower inlet of the air preheater 12 is fixedly connected to the second combustion-supporting pipeline 15, the top outlet of the air preheater 12 is fixedly connected to the vent pipeline 24, and the vent pipeline 24 and the second combustion-supporting pipeline 15 are fixedly connected to the second return pipeline 16.

[0042] As needed, the molten salt furnace 1 can be preheated by the air preheater 12, and the flue gas burning in the molten salt furnace 1 can also be circulated externally by the air preheater 12.

[0043] Example 4: Its difference from Examples 1 to 3 is as follows: (See attached) Figure 1 As shown, a nitrogen input pipeline 17 is fixedly connected to the third inlet at the top of the molten salt tank 3.

[0044] As needed, nitrogen can be introduced into the molten salt tank 3 through the nitrogen input pipeline 17 to provide positive pressure protection for the pressure balance inside the molten salt tank 3.

[0045] Example 5: It differs from Examples 1 to 4 in that, as shown in the appendix... Figure 1 As shown, a molten salt pump 18 is fixedly installed on the first molten salt pipeline 6, and an air pump 19 is fixedly installed on the second combustion-supporting pipeline 15 and the second return pipeline 16 between the second return pipeline 16 and the lower inlet of the air preheater 12.

[0046] Example 6: Its difference from Examples 1 to 5 is as follows: (See attached) Figure 1 As shown, control valves 20 are fixedly installed on the second molten salt pipeline 7, the fourth molten salt pipeline 9, and the nitrogen input pipeline 17 between the fourth molten salt pipeline 9 and the upper inlet of the alkali concentrator 4.

[0047] Example 7: Its difference from Examples 1 to 6 is as follows: (See attached) Figure 1 As shown, temperature gauges 21 are fixedly installed on both the air preheater 12 and the molten salt furnace 1.

[0048] Example 8: It differs from Examples 1 to 7 in that: as shown in the appendix Figure 1 As shown, a pressure gauge 22 is fixedly installed on the molten salt tank 3.

[0049] Example 9: It differs from Examples 1 to 8 in that: as shown in the appendix Figure 1 As shown, a flow meter 23 is fixedly installed on the natural gas input pipeline 5.

[0050] Example 10: It differs from Examples 1 to 9 in that, as shown in the appendix... Figure 1 As shown, it also includes a controller, and the molten salt pump 18, air pump 19, control valve 20, thermometer 21, pressure gauge 22, and flow meter 23 are all electrically connected to the controller.

[0051] Depending on the requirements, the pipelines and equipment of the low-nitrogen internal circulation molten salt heating device for solid alkali concentration may also be equipped with conventional valves, thermometers, and pressure gauges known in the art, according to production needs. The controller is a PLC controller, and the PLC controller model can be GL-FJ-XL01. The PLC controller is equipped with a Yokogawa CS3000DCS control system.

[0052] After this utility model is put into use, it can achieve precise control of natural gas consumption and temperature inside the molten salt furnace 1, breaking the environment for nitrogen oxide generation inside the molten salt furnace 1, reducing nitrogen oxide generation, improving the thermal efficiency of the molten salt furnace 1, and also reducing the natural gas cost input for solid alkali production. Nitrogen oxide emissions from the molten salt furnace 1 can be reduced from 100 mg / m³. 3 Reduced to 50 mg / m 3 It meets the Class A enterprise standard in the chlor-alkali industry (≤80mg / m³). 3 The dry flue gas volume of each molten salt furnace is 12000 Nm³. 3 If the system operates for 8000 hours per year, the annual reduction in nitrogen oxide emissions can reach 4.8 tons.

[0053] The above technical features constitute various embodiments of this utility model, which have strong adaptability and implementation effect. Unnecessary technical features can be added or removed according to actual needs to meet the needs of different situations.

[0054] The usage process of this utility model is as follows: First, the hot air in the air preheater 12 enters the molten salt furnace 1 through the first combustion-supporting pipeline 13 for furnace preheating. The gas in the molten salt furnace 1 returns to the air preheater 12 through the first return pipeline 14, forming a top-down combustion-supporting flow in the molten salt furnace 1. Next, natural gas enters the low-NOx burner 2 through the natural gas input pipeline 5 for ignition. The combustion flame heats the furnace of the molten salt furnace 1 to the required operating temperature. Then, the molten salt in the molten salt tank 3 enters the molten salt furnace 1 through the first molten salt pipeline 6 for high-temperature heating to obtain high-temperature molten salt. Finally, the high-temperature molten salt in the molten salt furnace 1 enters the alkali concentrator 4 through the second molten salt pipeline 7 to heat and concentrate the alkali solution in the alkali concentrator 4 at high temperature, obtaining a high-concentration alkali solution which enters the downstream process system through the second alkali solution pipeline 11.

[0055] The above-mentioned utility model also includes the following steps: On the one hand, the high-temperature molten salt in the alkali concentrator 4 is returned to the molten salt tank 3 through the third molten salt pipeline 8, and nitrogen enters the molten salt tank 3 through the nitrogen input pipeline 17 to provide positive pressure protection for the molten salt circulation in the molten salt tank 3; On the other hand, when the alkali concentrator 4 stops concentrating alkali, the control valve 20 on the second molten salt pipeline 7 is closed, and the molten salt in the molten salt furnace 1 enters the molten salt tank 3 through the fourth molten salt pipeline 9 to perform low-temperature molten salt circulation. At this time, the amount of natural gas input to the molten salt furnace 1 is reduced, and the air preheater 12 provides the required circulation heat for the molten salt in the molten salt furnace 1 to ensure the normal operation of the low-temperature molten salt circulation.

Claims

1. A low-nitrogen internal circulation molten salt heating device for solid alkali concentration, characterized in that... The system includes a molten salt furnace, a low-NOx burner, a molten salt tank, and an alkali concentrator. The molten salt furnace is equipped with a low-NOx burner at its top inlet, and a natural gas input pipeline is fixedly connected to the top inlet of the low-NOx burner. A first molten salt pipeline is fixedly connected between the top outlet of the molten salt tank and the lower inlet of the molten salt furnace. A second molten salt pipeline is fixedly connected between the upper outlet of the molten salt furnace and the upper inlet of the alkali concentrator. A third molten salt pipeline is fixedly connected between the lower outlet of the alkali concentrator and the first inlet at the top of the molten salt tank. A fourth molten salt pipeline is fixedly connected between the second molten salt pipeline and the second inlet at the top of the molten salt tank. A first alkali solution pipeline is fixedly connected to the top inlet of the alkali concentrator, and a second alkali solution pipeline is fixedly connected to the bottom outlet of the alkali concentrator.

2. The low-nitrogen internal circulation molten salt heating device for solid alkali concentration according to claim 1, characterized in that... It also includes an air preheater, with a first combustion-supporting pipeline fixedly connected between the upper outlet of the air preheater and the upper inlet of the molten salt furnace, and a first return pipeline fixedly connected between the lower outlet of the molten salt furnace and the lower inlet of the air preheater.

3. The low-nitrogen internal circulation molten salt heating device for solid alkali concentration according to claim 2, characterized in that... The lower inlet of the air preheater is fixedly connected to a second combustion-supporting pipeline, and the top outlet of the air preheater is fixedly connected to a vent pipeline. A second return pipeline is fixedly connected between the vent pipeline and the second combustion-supporting pipeline.

4. The low-nitrogen internal circulation molten salt heating device for solid alkali concentration according to claim 1, 2, or 3, characterized in that... A nitrogen input pipeline is fixedly connected to the third inlet at the top of the molten salt tank.

5. The low-nitrogen internal circulation molten salt heating device for solid alkali concentration according to claim 4, characterized in that... A molten salt pump is fixedly installed on the first molten salt pipeline, and an air pump is fixedly installed on both the second combustion-supporting pipeline and the second molten salt pipeline between the second return pipeline and the lower inlet of the air preheater.

6. The low-nitrogen internal circulation molten salt heating device for solid alkali concentration according to claim 5, characterized in that... Control valves are fixedly installed on the second molten salt pipeline, the fourth molten salt pipeline, and the nitrogen input pipeline between the fourth molten salt pipeline and the upper inlet of the alkali concentrator.

7. The low-nitrogen internal circulation molten salt heating device for solid alkali concentration according to claim 5 or 6, characterized in that... Temperature gauges are fixedly installed on both the air preheater and the molten salt furnace.

8. The low-nitrogen internal circulation molten salt heating device for solid alkali concentration according to claim 7, characterized in that... A pressure gauge is fixedly installed on the molten salt tank.

9. The low-nitrogen internal circulation molten salt heating device for solid alkali concentration according to claim 8, characterized in that... A flow meter is fixedly installed on the natural gas input pipeline.

10. The low-nitrogen internal circulation molten salt heating device for solid alkali concentration according to claim 9, characterized in that... It also includes a controller, and the molten salt pump, air pump, control valve, thermometer, pressure gauge, and flow meter are all electrically connected to the controller.

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