Ionic liquid preheating system

Abstract

The utility model provides an ionic liquid preheating system which comprises a tubular reboiler, a finned tube cooler, an expansion tank and a circulating oil pump, an ionic liquid inlet and an ionic liquid outlet are formed in the side face of the tubular reboiler, the ionic liquid inlet is connected with a feeding port of a plate reboiler through a flow dividing pipe, and the ionic liquid outlet is connected with a regeneration tower; the lower portion of the expansion groove is connected with an inlet of the circulating oil pump through the oil-gas separator, and an outlet of the circulating oil pump is connected with an oil inlet of the finned tube cooler. According to the utility model, the tubular reboiler is matched with the finned tube heat collector, flue gas waste heat of the two acid absorption processes is utilized to preheat the ionic liquid, the use amount of steam is reduced, the consumption of circulating cooling water and power electric energy is also reduced, and heat-conducting oil is used as a heat-conducting medium, so that the utilization rate of the heat-conducting oil is improved. When the sulfuric acid tail gas ionic liquid desulfurization regeneration tower breaks down, operation of a sulfuric acid system is not affected, the number of times of shutdown due to ionic liquid faults can be effectively reduced, and the operation rate of sulfuric acid production is improved.

Description

Technical Field

[0001] This utility model relates to the technical field of sulfuric acid production equipment, and in particular to a preheating system for ionic liquids. Background Technology

[0002] In the ionic liquid desulfurization process of sulfuric acid production, the principle is to utilize the characteristic of ionic liquid to absorb sulfur dioxide in the flue gas at low temperatures. The sulfur dioxide in the flue gas is absorbed and circulated within the desulfurization tower to achieve the purpose of flue gas desulfurization. The sulfur dioxide-rich liquid, under high temperature, then releases the sulfur dioxide, restoring its desulfurization function and achieving a regeneration effect. Existing high-temperature desorption of ionic liquid typically uses low-pressure saturated steam heating for temperature rise, resulting in a large steam consumption. Furthermore, a considerable portion of the flue gas from the second absorption tower has excess heat, requiring a heat exchanger for cooling with cooling water, consuming a large amount of circulating cooling water and electrical energy. To remove this heat through circulating cooling water, a preheating system for the ionic liquid needs to be designed. This involves connecting a tubular reboiler in parallel with the existing plate reboiler design. The heat source for the tubular reboiler is provided by the flue gas entering the second absorption tower, improving the utilization rate of thermal energy and reducing both steam consumption and the consumption of circulating cooling water and electrical energy. Utility Model Content

[0003] To address the aforementioned issues, this invention proposes a preheating system for ionic liquids. This system adds a tubular reboiler in parallel to the existing plate reboiler design. The heat source for the tubular reboiler is provided by the flue gas entering the second absorption tower, thereby improving the utilization rate of thermal energy and reducing both steam consumption and the consumption of circulating cooling water and electrical power.

[0004] This utility model is achieved through the following technical solution:

[0005] This utility model proposes a preheating system for ionic liquid, comprising: a tubular reboiler, a finned tube heat exchanger, an expansion tank, and a circulating oil pump. The tubular reboiler has an ionic liquid inlet and an ionic liquid outlet on its side. The ionic liquid inlet is connected to the feed inlet of a plate reboiler via a diverter pipe, and the ionic liquid outlet is connected to a regeneration tower. The lower part of the expansion tank is connected to the inlet of the circulating oil pump via an oil-gas separator. The outlet of the circulating oil pump is connected to the oil inlet of the finned tube heat exchanger, and the oil outlet of the finned tube heat exchanger is connected to the heat transfer oil inlet of the tubular reboiler. The heat transfer oil outlet of the tubular reboiler is connected to the oil-gas separator via a pipeline.

[0006] Furthermore, it also includes an oil storage tank, which is connected to an expansion tank via an oil injection pump.

[0007] Furthermore, the expansion tank is installed at a higher position than the oil storage tank, and the upper part of the expansion tank is connected to the oil storage tank through an overflow pipe.

[0008] Furthermore, a safety valve is provided on the pipeline between the oil outlet of the finned tube heat exchanger and the heat transfer oil inlet of the tubular reboiler, and the oil discharge end of the safety valve is connected to the overflow pipe through a pipeline.

[0009] Furthermore, the flue gas inlet at the top of the finned tube heat exchanger is connected to the flue gas outlet of the waste heat conversion boiler, and the flue gas outlet at the bottom of the finned tube heat exchanger is connected to the inlet of the sulfuric acid secondary absorption tower.

[0010] Furthermore, there are two circulating oil pumps connected in parallel, and an oil filter is provided between the circulating oil pumps and the oil-gas separator.

[0011] The beneficial effects of this utility model are as follows: By combining the tubular reboiler and the finned tube heat exchanger, the waste heat of the flue gas from the secondary acid absorption process is used to preheat the ionic liquid, which reduces the amount of steam used, as well as the consumption of circulating cooling water and power. Furthermore, by using heat transfer oil as the heat transfer medium, the operation of the sulfuric acid system is not affected when the sulfuric acid tail gas ionic liquid desulfurization and regeneration tower malfunctions. This effectively reduces the number of shutdowns due to ionic liquid failures and improves the operating rate of sulfuric acid production. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the structure of this utility model;

[0013] In the diagram: 1-Tube reboiler, 2-Finned tube heat exchanger, 3-Oil storage tank, 4-Expansion tank, 5-Circulating oil pump, 6-Ion liquid inlet, 7-Ion liquid outlet, 8-Oil-gas separator, 9-Oil injection pump, 10-Overflow pipe, 11-Safety valve, 12-Oil filter. Detailed Implementation

[0014] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Throughout the description, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions. Obviously, the described embodiments are only a part of the embodiments of the present utility model, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present utility model without creative effort are within the scope of protection of the present utility model.

[0015] It should be noted that all directional indicators (such as up, down, left, right, front, back, etc.) in this utility model embodiment are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

[0016] Furthermore, the use of terms such as "first" and "second" in this utility model is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, features defined with "first" and "second" may explicitly or implicitly include at least one of the stated features. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. If the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed by this utility model.

[0017] like Figure 1 As shown, one embodiment of this utility model provides a preheating system for ionic liquid, including: a tubular reboiler 1, a finned tube heat exchanger 2, an expansion tank 4, and a circulating oil pump 5. The tubular reboiler 1 has an ionic liquid inlet 6 and an ionic liquid outlet 7 on its side. The ionic liquid inlet 6 is connected to the feed inlet of the plate reboiler through a diverter pipe, and the ionic liquid outlet 7 is connected to the regeneration tower. The lower part of the expansion tank 4 is connected to the inlet of the circulating oil pump 5 through an oil-gas separator 8. The outlet of the circulating oil pump 5 is connected to the oil inlet of the finned tube heat exchanger 2. The oil outlet of the finned tube heat exchanger 2 is connected to the heat transfer oil inlet of the tubular reboiler 1. The heat transfer oil outlet of the tubular reboiler 1 is connected to the oil-gas separator 8 through a pipe.

[0018] This preheating system for ionic liquids primarily addresses the modification of existing ionic liquid heating systems in sulfuric acid production systems. Current equipment typically uses plate reboilers for heating and regenerating the ionic liquid. To reduce steam consumption by the plate reboiler and to decrease the consumption of circulating cooling water and electrical energy by the secondary absorption acid cooling system, this preheating system utilizes a finned tube heat exchanger 2 to exchange heat with the flue gas from the second absorption tower. A circulating oil pump 5 circulates the heat transfer oil in the pipeline, where it exchanges heat with the flue gas from the second absorption tower, raising the temperature of the heat transfer oil from 130°C to 155°C. This reduces the flue gas temperature from 190℃ to 150℃, thereby lowering the heat dissipation load of the secondary absorption acid cooling system and reducing its consumption of circulating cooling water and power. After the heat transfer oil is heated, it enters the tubular reboiler 1, where it exchanges heat with the ionic liquid diverted from the plate reboiler. This raises the temperature of the ionic liquid, preheating it and reducing steam consumption in the ionic liquid regeneration section. After heat exchange, the heat transfer oil returns to the oil-gas separator 8. After oil-gas and water separation, it flows back to the inlet of the circulating oil pump 5, ensuring continuous circulation. The plate reboiler and tubular reboiler 1 are separated by a regulating pump. During production, the flow rate of the ionic liquid entering the tubular reboiler 1 is adjusted according to the heat load of the flue gas. Any insufficient heat is supplemented by steam heating from the original plate reboiler.

[0019] During production, if the sulfuric acid tail gas ion liquid desulfurization regeneration tower malfunctions, it may shut down and not require heating, while the sulfuric acid system will continue to operate. Since the flue gas temperature of the second absorption tower used in this preheating system can only reach a maximum of 225℃ under abnormal conditions, while the operating temperature of the heat transfer oil is much higher than this temperature, when the ion liquid desulfurization system shuts down, heating to the desulfurization system can be stopped by stopping the heat transfer oil circulation. For the same reason, the circulating oil pump 5 can use a frequency converter to control the circulation flow rate, adjusting the circulation volume according to the production load to achieve energy saving.

[0020] In a preferred embodiment, the system further includes an oil storage tank 3, which is connected to the expansion tank 4 via an oil injection pump 9. The oil storage tank 3 replenishes the expansion tank 4 with heat transfer oil and discharges waste oil, ensuring the effective heat transfer of the heat transfer oil.

[0021] In a preferred embodiment, the expansion tank 4 is installed higher than the oil storage tank 3. The upper part of the expansion tank 4 is connected to the oil storage tank 3 through the overflow pipe 10. When the temperature of the heat transfer oil rises or falls, its volume will expand or shrink. This can be buffered by the expansion tank 4. At the same time, when there is water in the heat transfer oil, the water can rise into the tank and evaporate. When adding heat transfer oil, excess heat transfer oil can flow back to the oil storage tank 3 through the overflow pipe 10 to avoid oil leakage.

[0022] In a preferred embodiment, a safety valve 11 is provided on the pipeline between the oil outlet of the finned tube heat exchanger 2 and the heat transfer oil inlet of the tubular reboiler 1. The oil discharge end of the safety valve 11 is connected to the overflow pipe 10 through a pipeline. When the pipeline is blocked or the temperature is too high, the heat transfer oil expands, causing abnormal oil pressure in the pipeline. After exceeding the threshold, the safety valve 11 automatically opens and discharges the heat transfer oil into the oil storage tank 3, thereby ensuring the safety of the entire heat transfer oil circulation pipeline.

[0023] In a preferred embodiment, the flue gas inlet at the upper part of the finned tube heat exchanger 2 is connected to the flue gas outlet of the waste heat conversion boiler, and the flue gas outlet at the lower part of the finned tube heat exchanger 2 is connected to the inlet of the sulfuric acid secondary absorption tower. The waste heat conversion boiler and the sulfuric acid secondary absorption tower are equipment in the existing sulfuric acid production system. By introducing the flue gas at about 190°C from the waste heat boiler outlet into the finned tube heat exchanger 2, exchanging heat with the heat transfer oil in the finned tube heat exchanger 2, and then returning it to the sulfuric acid secondary absorption tower, the heat dissipation load of the secondary absorption acid cooling system is reduced, and the consumption of circulating cooling water and power energy is reduced.

[0024] Preferably, there are two circulating oil pumps 5 connected in parallel. The circulating oil pumps 5 are configured with one in use and one on standby. If one circulating oil pump 5 fails, the pipeline can be adjusted by valves to use the other circulating oil pump 5 to supply oil, ensuring the reliable operation of the entire preheating system. In addition, an oil filter 12 is provided between the circulating oil pump 5 and the oil-gas separator 8 to filter out impurities in the pipeline and prevent impurities from affecting the operation of the equipment.

[0025] Of course, there may be other implementations of this utility model. Based on this implementation, other implementations obtained by those skilled in the art without any creative effort are all within the scope of protection of this utility model.

Claims

1. A preheating system for ionic liquids, characterized in that, include: The tubular reboiler (1), finned tube heat exchanger (2), expansion tank (4), and circulating oil pump (5) are provided on the side of the tubular reboiler (1), which has an ionic liquid inlet (6) and an ionic liquid outlet (7). The ionic liquid inlet (6) is connected to the feed port of the plate reboiler through a split pipe, and the ionic liquid outlet (7) is connected to the regeneration tower. The lower part of the expansion tank (4) is connected to the inlet of the circulating oil pump (5) through the oil-gas separator (8). The outlet of the circulating oil pump (5) is connected to the oil inlet of the finned tube heat exchanger (2). The oil outlet of the finned tube heat exchanger (2) is connected to the heat transfer oil inlet of the tubular reboiler (1). The heat transfer oil outlet of the tubular reboiler (1) is connected to the oil-gas separator (8) through a pipeline.

2. The preheating system for an ionic liquid according to claim 1, characterized in that, It also includes an oil storage tank (3), which is connected to an expansion tank (4) via an oil injection pump (9).

3. The preheating system for an ionic liquid according to claim 2, characterized in that, The expansion tank (4) is installed at a higher position than the oil storage tank (3), and the upper part of the expansion tank (4) is connected to the oil storage tank (3) through an overflow pipe (10).

4. The preheating system for an ionic liquid according to claim 3, characterized in that, A safety valve (11) is provided on the pipeline between the oil outlet of the finned tube heat exchanger (2) and the heat transfer oil inlet of the tubular reboiler (1). The oil discharge end of the safety valve (11) is connected to the overflow pipe (10) through a pipeline.

5. The preheating system for an ionic liquid according to claim 1, characterized in that, The flue gas inlet at the top of the finned tube heat exchanger (2) is connected to the flue gas outlet of the waste heat conversion boiler, and the flue gas outlet at the bottom of the finned tube heat exchanger (2) is connected to the inlet of the sulfuric acid absorption tower.

6. The preheating system for an ionic liquid according to claim 1, characterized in that, There are two circulating oil pumps (5), which are connected in parallel, and an oil filter (12) is provided between the circulating oil pumps (5) and the oil-gas separator (8).

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