Waste heat recovery and desulfurization synergistic system

Abstract

According to the waste heat recovery and desulfurization synergistic system provided by the invention, the two heat exchangers are respectively arranged inside and outside the desulfurization tower, and the two heat exchangers are communicated with each other inside and outside, so that the space of the desulfurization tower is not obviously occupied, and heat energy generated in the desulfurization tower can be utilized to the greatest extent. Furthermore, local materials are used, the intensity of the desulfurization reaction in the desulfurization tower can be detected by utilizing temperature change caused by an internal heat exchanger, and then coarse adjustment and fine adjustment can be performed by utilizing a circulating pipeline for conveying desulfurization slurry, so that the progress of the desulfurization reaction is effectively adjusted.

Description

Technical Field

[0001] The invention relates to a waste heat recovery and desulfurization efficiency enhancement system. Background Art

[0002] At present, with the vigorous development of my country's heating industry, the flue gas emissions of various chemical companies and the flue gas pollution caused by them are becoming increasingly serious. The sulfur content in the flue gas is an important indicator for measuring flue gas pollution. Therefore, reducing the sulfur content in the flue gas through desulfurization towers has become an effective means for chemical companies to reduce pollution.

[0003] However, in existing actual engineering applications, desulfurization towers are generally only used to achieve flue gas desulfurization. In fact, the input flue gas at the inlet of the desulfurization tower is usually at a high temperature, usually as high as 100-150°C. After spraying in the desulfurization tower, the total heat of the flue gas enters the desulfurization slurry. On the one hand, this will cause a large amount of heat waste. On the other hand, the heat accumulates in the desulfurization tower and is absorbed by the desulfurization tower itself, which is also likely to reduce the operating life of the desulfurization tower.

[0004] Current desulfurization towers often have heat exchangers installed outside the desulfurization tower to reduce the temperature of the flue gas and the desulfurization tower, but few people have proposed relevant plans for effectively utilizing the heat energy of the flue gas and the desulfurization tower. Summary of the invention

[0005] The present invention provides a waste heat recovery and desulfurization efficiency enhancement system, which effectively solves the problems existing in the prior art.

[0006] Specifically, the present invention provides a waste heat recovery and desulfurization efficiency enhancement system, in which the flue gas is input from the flue gas inlet to the desulfurization tower through the flue, the desulfurization tower includes a tower kettle at the bottom of the desulfurization tower and used to contain the desulfurization slurry, the tower kettle is connected to the n spray layers stacked up and down above the tower kettle in the desulfurization tower via n circulation pipes, wherein n≥2, a one-way pump is arranged on each circulation pipe, and when any one-way pump is turned on, the circulation pipe corresponding to the one-way pump will extract the desulfurization slurry from the tower kettle to the corresponding spray layer, and the desulfurization slurry will be discharged from the tower kettle to the corresponding spray layer. The sulfur slurry is sprayed downward from the spray layer, thereby spraying the flue gas input from the flue gas inlet, and the flue gas reacts with the sprayed desulfurization slurry to desulfurize the flue gas. The desulfurized flue gas rises in the desulfurization tower and escapes from the flue gas outlet at the top of the desulfurization tower through the demister. In this system, the first heat exchanger surrounds the flue, and the second heat exchanger is arranged in the desulfurization tower at a height between the spray layer and the tower kettle. Cooling water flows in from the water inlet of the second heat exchanger, flows through the second heat exchanger, and then flows out from the water outlet of the second heat exchanger. The cooling water flowing out from the outlet of the second heat exchanger further flows to the inlet of the first heat exchanger, and then flows out from the outlet of the first heat exchanger through the first heat exchanger to cool the flue gas in the flue. A temperature sensor is installed at the outlet of the second heat exchanger to sense the real-time temperature T of the cooling water at the outlet of the second heat exchanger. The minimum acceptable temperature in the desulfurization tower is set as MinT, and the maximum acceptable temperature in the desulfurization tower is set as MaxT. The temperature sensor transmits the real-time temperature T to the remote central processing unit in real time. Once the central processing unit determines that the real-time temperature T is outside the interval range [MinT, MaxT], the central processing unit sends an instruction to the one-way pump. When the current k circulation pipes are completely unblocked and the remaining nk circulation pipes are completely blocked, the temperature T is roughly adjusted by changing the number of unblocked circulation pipes, and the temperature T is fine-tuned by adjusting the pumping force of the one-way pump to ensure that the adjusted real-time temperature T falls within the interval range [MinT, MaxT], where 1≤k <n。

[0007] Preferably, n=4, that is, there are four circulation pipes in the system, corresponding to four spray layers one by one, wherein the tower bottom is connected to the first spray layer via the first circulation pipe, connected to the second spray layer via the second circulation pipe, connected to the third spray layer via the third circulation pipe, and connected to the fourth spray layer via the fourth circulation pipe.

[0008] Preferably, if the real-time temperature T>MaxT, the central processing unit sends an instruction to one of the k unobstructed circulation pipes, requiring to shut down the one-way pump corresponding to the one of the circulation pipes, thereby weakening the desulfurization reaction and pushing the real-time temperature T from above MaxT to within the interval range [MinT, MaxT].

[0009] Preferably, if shutting down the one-way pump corresponding to one of the circulation pipelines causes the real-time temperature T to drop below MinT, the central processing unit sends an instruction to the one-way pump corresponding to the one circulation pipeline that has been shut down again, re-opens this one-way pump and finely tunes this one-way pump to partially unblock the one circulation pipeline that has been shut down, so that the real-time temperature T gradually returns to within the range [MinT, MaxT].

[0010] Preferably, if the real-time temperature T < MinT, the central processing unit sends an instruction to one of the remaining n - k circulation pipelines, requiring to strengthen the desulfurization reaction by completely opening the one-way pump corresponding to this one circulation pipeline to increase one completely unblocked circulation pipeline, so as to push the real-time temperature T from below MinT into the range [MinT, MaxT].

[0011] Preferably, if increasing one completely unblocked circulation pipeline causes the real-time temperature T to be greater than MaxT, the central processing unit sends an instruction to the one-way pump corresponding to this newly added completely unblocked circulation pipeline again, gradually reduces the pumping force of this one-way pump, so that the real-time temperature T gradually returns to within the range [MinT, MaxT].

[0012] In summary, a waste heat recovery and desulfurization efficiency enhancement system provided by the present invention is provided with a heat exchanger inside and outside the desulfurization tower respectively. These two heat exchangers are connected to each other inside and outside, do not significantly occupy the space of the desulfurization tower, and can maximize the utilization of the heat energy generated inside the desulfurization tower, improve the utilization rate of heat energy, and achieve the purpose of doubling the effect. Further, by using local materials and the temperature change caused by the internal heat exchanger, the intensity of the desulfurization reaction inside the desulfurization tower can be detected. Then, the circulation pipeline for transporting the desulfurization slurry can be used for rough adjustment and fine adjustment, so as to effectively adjust the progress of the desulfurization reaction. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will discuss the drawings required for describing the embodiments or the prior art. Obviously, the technical solutions described in conjunction with the drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other embodiments and their drawings can be obtained according to the embodiments shown in these drawings.

[0014] Figure 1 Shows a basic structure diagram of a waste heat recovery and desulfurization efficiency enhancement system according to the present invention.

[0015] Figure 2 Shows a top view of the second heat exchanger in a waste heat recovery and desulfurization efficiency enhancement system according to the present invention. DETAILED DESCRIPTION

[0016] The technical solutions of various embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments described in the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0017] This patent aims to provide a waste heat recovery and desulfurization efficiency enhancement system, which can effectively absorb and utilize the heat of the flue gas passing through the desulfurization tower, and can even effectively monitor whether the desulfurization process in the desulfurization tower is progressing smoothly or excessively during the heat absorption process.

[0018] Figure 1 The basic structure diagram of a waste heat recovery and desulfurization efficiency enhancement system according to the present invention is shown.

[0019] like Figure 1 As shown, a waste heat recovery and desulfurization efficiency enhancement system according to the present invention includes a flue gas inlet 101, and the flue gas is input from the flue gas inlet 101 to a desulfurization tower through a flue 100. The desulfurization tower includes a kettle 102 located at the bottom of the desulfurization tower and used to accommodate desulfurization slurry. The kettle 102 is connected to n spray layers 104 (where n≥2) stacked up and down above the kettle 102 in the desulfurization tower via n circulation pipes 103, that is, the kettle 102 is connected to a corresponding spray layer 104 through each circulation pipe 103.

[0020] exist Figure 1 , n=4, that is, the tower bottom 102 is connected to the first spray layer via the first circulation pipe, connected to the second spray layer via the second circulation pipe, connected to the third spray layer via the third circulation pipe, and connected to the fourth spray layer via the fourth circulation pipe.

[0021] A one-way pump 105 is provided on each circulation pipeline 103. When any one-way pump 105 is turned on, the circulation pipeline 104 corresponding to the one-way pump 105 extracts the desulfurization slurry from the tower bottom 102 to the corresponding spray layer 104, whereby the desulfurization slurry is sprayed downward from the spray layer 104, thereby spraying the flue gas input from the flue gas inlet 101, and the flue gas reacts with the sprayed desulfurization slurry to desulfurize the flue gas, and the desulfurized flue gas rises in the desulfurization tower and escapes from the flue gas outlet 107 at the top of the desulfurization tower through the demister 106.

[0022] like Figure 1As shown, the demister 106 may also include a tubular demister 106a and a plate demister 106b stacked up and down, and the desulfurized flue gas passes through the plate demister 106b and the tubular demister 106a successively and escapes from the flue gas outlet 107 .

[0023] The waste heat recovery and desulfurization efficiency enhancement system provided by the present invention also includes a first heat exchanger 108 and a second heat exchanger 109. The first heat exchanger 108 surrounds the flue 100. The second heat exchanger 109 is arranged in the desulfurization tower and is located between the spray layer 104 and the tower bottom 102 in height. Cooling water flows in from the water inlet 109a of the second heat exchanger 109, flows through the second heat exchanger 109, and flows out from its water outlet 109b. Then, the cooling water flowing out from the water outlet 109b further flows to the water inlet 108a of the first heat exchanger 108, and then flows out from its water outlet 108b through the first heat exchanger 108. It can be seen that two heat exchangers are arranged in the waste heat recovery and desulfurization efficiency enhancement system of the present invention, one heat exchanger is arranged inside the desulfurization tower, and the other heat exchanger surrounds the flue. Therefore, the two heat exchangers will not occupy additional space in the desulfurization tower, effectively saving the site of the desulfurization tower. At the same time, the two heat exchangers are interconnected, and the water outlet of the second heat exchanger is connected to the water inlet of the first heat exchanger. Therefore, only a separate water circulation is needed to achieve simultaneous heat exchange of the flue gas inside the desulfurization tower and the flue gas outside the desulfurization tower (flue), which effectively improves the heat exchange efficiency and achieves the purpose of doubling the effect.

[0024] As described above, the structure of a waste heat recovery and desulfurization efficiency enhancement system provided by the present invention has been basically introduced. In fact, through the introduction of the above structure, the operation process of the waste heat recovery and desulfurization efficiency enhancement system is also basically introduced. Of course, in order to make the interval clearer, this article also briefly introduces the basic operation process of the above waste heat recovery and desulfurization efficiency enhancement system.

[0025] Based on the above structure, the flue gas flows in from the flue 100, and in the process of the flue gas flowing through the flue 100, it has been cooled for the first time by the first heat exchanger 108 surrounding the flue 100. The flue gas after the first cooling in the flue 100 flows into the desulfurization tower. At this time, the desulfurization slurry in the tower bottom 102 flows to the spray layer 104 through the circulation pipe 103 under the pumping of the one-way pump 105, and the desulfurization slurry is sprayed downward from the spray layer 104, thereby reacting with the flue gas entering the desulfurization tower. During the desulfurization reaction, the second heat exchanger 109 inside the desulfurization tower and connected to the first heat exchanger 108 cools the flue gas for the second time. The flue gas that has been cooled twice continues to rise in the desulfurization tower, passes through the demister 106 for demisting, and then escapes from the desulfurization tower from the flue gas outlet 107.

[0026] As mentioned above, in the whole process, the flue gas is cooled twice outside and inside the desulfurization tower, which means that the cooling water in the interconnected first heat exchanger 108 and the second heat exchanger 109 absorbs heat twice. The cooling water mainly absorbs the heat generated by the flue gas desulfurization reaction in the second heat exchanger 109, and the cooling water mainly absorbs the heat of the original flue gas in the flue 100 in the first heat exchanger 108. Therefore, the cooling water effectively absorbs as much heat as possible in the whole desulfurization process, thereby maximally absorbing the heat in the desulfurization process, and "transporting" the heat away with the cooling water as a carrier. The heat can be recycled in other heating occasions to achieve effective utilization of thermal energy without causing the heat to be lost in vain in the desulfurization tower.

[0027] Figure 2 FIG. 2 shows a top view of the second heat exchanger in a waste heat recovery and desulfurization efficiency enhancement system according to the present invention. Figure 2 As shown, the second heat exchanger 109 presents a serpentine structure in the top view, so as to provide a larger contact area as possible to maximize the heat exchange with the flue gas undergoing desulfurization reaction in the desulfurization tower.

[0028] As described above, the second heat exchanger 109 is placed inside the desulfurization tower, which helps the desulfurization tower save space as much as possible, and can absorb heat to the maximum extent and make the heat energy in the desulfurization tower be utilized as much as possible. However, in fact, under the scheme of the present invention, the role of the second heat exchanger 109 is far more than this, which will be further explained below.

[0029] like Figure 1 As shown, a temperature sensor 201 is installed at the water outlet 109b of the second heat exchanger 109 to sense the temperature T of the cooling water at the water outlet 109b. Since the temperature T reflects the temperature of the cooling water at the water outlet 109b, and since the second heat exchanger 109 is arranged inside the desulfurization tower, it means that the temperature T actually reflects the degree of heat exchange between the second heat exchanger 109 in the desulfurization tower and the flue gas in the desulfurization tower, which means that the temperature T further reflects the intensity of the desulfurization reaction between the flue gas in the desulfurization tower and the desulfurization slurry sprayed down.

[0030] In other words, precisely because the second heat exchanger 109 is disposed in the desulfurization tower, the intensity of the desulfurization reaction in the desulfurization tower can be effectively monitored by monitoring the temperature T, which is crucial to the overall control of the desulfurization tower.

[0031] In fact, in the desulfurization tower, the desulfurization reaction cannot be too intense, otherwise it will cause serious corrosion of the components in the desulfurization tower, and seriously damage the service life of the desulfurization tower; of course, the desulfurization reaction cannot be too bland, otherwise it will seriously affect the desulfurization effect and cause the sulfur content of the flue gas escaping from the flue gas outlet to be too high.

[0032] Therefore, correspondingly, the temperature T reflecting the intensity of the desulfurization reaction should be maintained within a suitable range, which is set as [MinT, MaxT]. That is, MinT is the lowest acceptable temperature in the desulfurization tower, and MaxT is the highest acceptable temperature in the desulfurization tower. In practice, it is often set as [130°C, 140°C]. In other words, MinT = 130°C, which is the lowest acceptable temperature in the desulfurization tower, and MaxT = 140°C, which is the highest acceptable temperature in the desulfurization tower.

[0033] The temperature sensor 201 transmits the temperature T to the remote central processing unit in real time. Once the central processing unit determines that the temperature T is outside the range [MinT, MaxT] (i.e., T > MaxT or T < MinT), the central processing unit sends an instruction to the unidirectional pump. When the current k circulating pipes are completely unblocked and the remaining n - k circulating pipes are completely blocked (where 1 ≤ k < n), the temperature T is roughly adjusted by changing the number of unblocked circulating pipes, and the temperature T is finely adjusted by adjusting the pumping intensity of the unidirectional pump, thereby ensuring that the adjusted temperature T falls within the range [MinT, MaxT].

[0034] Here, the present invention utilizes two mechanisms of rough adjustment and fine adjustment to ensure that the temperature T finally falls within the range.

[0035] More specifically, if the temperature T > MaxT, it indicates that the desulfurization reaction is too intense. Then the central processing unit sends an instruction to one of the k unblocked circulating pipes to shut off the unidirectional pump corresponding to that one circulating pipe, thereby greatly reducing the delivery volume of the desulfurization slurry, and then weakening the desulfurization reaction, so as to push the temperature T from above MaxT to within the range [MinT, MaxT] as much as possible. However, in practice, shutting off one circulating pipe will cause the temperature T to drop significantly, and it is very likely that the real-time temperature T will be less than MinT, making the temperature T too low. In this case, the central processing unit sends an instruction to the unidirectional pump corresponding to the one shut-off circulating pipe again to restart this unidirectional pump, so that the one shut-off circulating pipe is partially unblocked. Through this fine adjustment, the real-time temperature T gradually returns to within the range [MinT, MaxT].

[0036] Conversely, if the real-time temperature T < MinT, it indicates that the desulfurization reaction is too mild. Then the central processing unit sends an instruction to one of the remaining n - k circulation pipes, requiring the one-way pump corresponding to this circulation pipe to be fully opened, thereby significantly increasing the delivery volume of the desulfurization slurry, further strengthening the desulfurization reaction, and thus pushing the temperature T from below MinT to within the range [MinT, MaxT] as much as possible. However, in practice, adding one completely unobstructed circulation pipe will cause a significant increase in the temperature T, and it is very likely that the real-time temperature T will be greater than MaxT, resulting in an excessive temperature T. In this case, the central processing unit sends an instruction to the one-way pump corresponding to this newly added unobstructed circulation pipe again, gradually reducing the pumping force of this one-way pump, so that this circulation pipe is partially unobstructed. Through this fine adjustment, the real-time temperature T is gradually brought back to within the range [MinT, MaxT].

[0037] So far, the specific structure and operation process of a waste heat recovery and desulfurization efficiency enhancement system provided by the present invention have been introduced. The waste heat recovery and desulfurization efficiency enhancement system provided by the present invention is provided with a heat exchanger inside and outside the desulfurization tower respectively. These two heat exchangers are connected to each other inside and outside, do not significantly occupy the space of the desulfurization tower, and can maximize the utilization of the heat energy generated inside the desulfurization tower. Further, by making use of local materials and the temperature change caused by the internal heat exchanger, the intensity of the desulfurization reaction inside the desulfurization tower can be detected. Then, the coarse adjustment and fine adjustment can be carried out by using the circulation pipe for transporting the desulfurization slurry, thereby effectively adjusting the progress of the desulfurization reaction.

[0038] The above are only exemplary embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A waste heat recovery and desulfurization efficiency enhancement system, characterized in that: In this system, flue gas is input from the flue gas inlet to the desulfurization tower through the flue. The desulfurization tower includes a tower kettle at the bottom of the desulfurization tower for containing desulfurization slurry. The tower kettle is connected to n spray layers stacked up and down above the tower kettle in the desulfurization tower via n circulation pipes, where n≥2. A one-way pump is arranged on each circulation pipeline. When any one-way pump is turned on, the circulation pipeline corresponding to the one-way pump will extract the desulfurization slurry from the tower kettle to the corresponding spray layer, and the desulfurization slurry will spray downward from the spray layer, thereby spraying the flue gas input from the flue gas inlet. The flue gas reacts with the sprayed desulfurization slurry to desulfurize the flue gas. The desulfurized flue gas rises in the desulfurization tower and escapes from the flue gas outlet at the top of the desulfurization tower through the demister. In this system, the first heat exchanger surrounds the flue, and the second heat exchanger is arranged in the desulfurization tower at a height between the spray layer and the tower kettle. Cooling water flows in from the water inlet of the second heat exchanger, flows through the second heat exchanger, and then flows out from the water outlet of the second heat exchanger to cool the flue gas in the desulfurization tower. Then, the cooling water flowing out from the water outlet of the second heat exchanger further flows to the water inlet of the first heat exchanger, and then flows out from the water outlet of the first heat exchanger through the first heat exchanger to cool the flue gas in the flue. A temperature sensor is installed at the outlet of the second heat exchanger to sense the real-time temperature T of the cooling water at the outlet of the second heat exchanger. The minimum acceptable temperature in the desulfurization tower is set as MinT, and the maximum acceptable temperature in the desulfurization tower is set as MaxT. The temperature sensor transmits the real-time temperature T to the remote central processing unit in real time. Once the central processing unit determines that the real-time temperature T is outside the interval range [MinT, MaxT], the central processing unit sends an instruction to the one-way pump. When the current k circulation pipes are completely unobstructed and the remaining nk circulation pipes are completely blocked, the temperature T is roughly adjusted by changing the number of unobstructed circulation pipes, and the temperature T is finely adjusted by adjusting the pumping force of the one-way pump to ensure that the real-time temperature T after adjustment falls within the interval range [MinT, MaxT], where 1≤k <n。 2. The system according to claim 1, characterized in that n=4, that is, there are four circulation pipes in the system, corresponding to four spray layers one by one, wherein the tower bottom is connected to the first spray layer via the first circulation pipe, connected to the second spray layer via the second circulation pipe, connected to the third spray layer via the third circulation pipe, and connected to the fourth spray layer via the fourth circulation pipe.

3. The system according to claim 1, characterized in that During coarse adjustment, if the real-time temperature T>MaxT, the central processing unit sends an instruction to one of the k unobstructed circulation pipes, requiring the one-way pump corresponding to one of the circulation pipes to be shut down, thereby weakening the desulfurization reaction and pushing the real-time temperature T from above MaxT to within the interval range [MinT, MaxT].

4. The system according to claim 3, characterized in that During fine tuning, if turning off the one-way pump corresponding to one of the circulating pipes causes the real-time temperature T to drop below MinT, the central processing unit sends a command to the one-way pump corresponding to the one circulating pipe that has been turned off again, turns on this one-way pump again and adjusts this one-way pump to make a part of the one circulating pipe that has been turned off unblocked, so that the real-time temperature T returns to the range [MinT, MaxT].

5. The system according to claim 1, characterized in that During coarse tuning, if the real-time temperature T < MinT, the central processing unit sends a command to one of the remaining n - k circulating pipes, and requests to strengthen the desulfurization reaction by completely opening the one-way pump corresponding to this one circulating pipe, thereby increasing one completely unblocked circulating pipe, so as to push the real-time temperature T from below MinT to within the range [MinT, MaxT].

6. The system according to claim 5, characterized in that During fine tuning, if adding one completely unblocked circulating pipe causes the real-time temperature T to be greater than MaxT, the central processing unit sends a command to the one-way pump corresponding to this newly added completely unblocked circulating pipe again, gradually reduces the pumping force of this one-way pump, so that the real-time temperature T gradually returns to the range [MinT, MaxT].

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