Combined tower for wet condensation of sulfuric acid and heat recovery

Abstract

The utility model belongs to the technical field of wet-process acid making equipment, and particularly relates to a combined tower for wet-process sulfuric acid condensation and heat recovery. The combined tower comprises a liquid accumulation section arranged at the bottom of the combined tower; the circulating acid heat transfer section is arranged above the liquid accumulation section, an acid distributor is arranged at the upper part of the circulating acid heat transfer section, and a flue gas inlet is formed in the lower part of the circulating acid heat transfer section; the condensation acid production section is arranged above the circulating acid heat transfer section, a partition plate is arranged between the condensation acid production section and the circulating acid heat transfer section, a plurality of gas rising caps are arranged on the partition plate, an acid outlet is formed in the upper portion of the partition plate, a condensation pipe is arranged above the acid outlet, an air inlet is formed in the upper portion of the condensation pipe, and an air outlet is formed in the lower portion of the condensation pipe; and the demisting section is arranged above the condensation acid production section. The absorption tower is used for solving the technical problem of low heat recovery efficiency of the absorption tower in the prior art.

Description

Technical Field

[0001] This utility model belongs to the technical field of wet acid production equipment, specifically relating to a combined tower for wet condensation of sulfuric acid and heat recovery. Background Technology

[0002] The wet acid production process involves multiple stages, such as flue gas conversion and flue gas acid formation, which generate a large amount of heat. The theoretical basis for this process is shown in the following formula:

[0003] The heat of reaction for SO2 + ½O2 → SO3+ is 96.1 kJ / mol; (1)

[0004] SO3(g) + H2O(g) = H2SO4(g) + heat of reaction (124.8 kJ / mol); (2)

[0005] H2SO4 (gas) = ​​H2SO4 (liquid) + heat of reaction (50.1 kJ / mol); (3)

[0006] Equation (1) corresponds to the flue gas conversion stage, while equations (2) and (3) correspond to the flue gas acidification stage.

[0007] Existing absorption towers typically allow flue gas to enter and be absorbed by circulating acid. A portion of the acid mist is condensed (cooled by 98% pure sulfuric acid introduced into the condensation section), and the resulting sulfuric acid is mixed with the circulating acid. The circulating acid is then discharged into an evaporator to exchange heat with cooling water, thus achieving heat recovery. However, in this structure, the condensed acid mixes with the circulating acid, lowering its temperature and reducing the temperature difference between the circulating acid and the cooling water, thereby affecting the efficiency of heat recovery. Utility Model Content

[0008] This invention provides a combined tower for wet condensation of sulfuric acid and heat recovery, which solves the technical problem of low heat recovery efficiency in existing absorption towers.

[0009] This utility model includes: a liquid collection section, located at the bottom of the combined tower;

[0010] A circulating acid heat transfer section is provided above the liquid accumulation section. An acid separator is provided at the upper part of the circulating acid heat transfer section, and a flue gas inlet is provided at the lower part of the circulating acid heat transfer section.

[0011] A condensation acid-generating section is provided above the circulating acid heat transfer section, and a partition is provided between the condensation acid-generating section and the circulating acid heat transfer section. The partition is provided with a plurality of gas lifting caps, and an acid outlet is provided above the partition. A condensation pipe is provided above the gas lifting caps, and an air inlet is provided above the condensation pipe and an air outlet is provided below the condensation pipe.

[0012] A demisting section is located above the condensation and acid-producing section.

[0013] In this application, the sulfuric acid formed after the acid mist condenses in the acid-producing section will be directly discharged and will not fall into the circulating acid, thus not lowering the temperature of the circulating acid and not affecting the efficiency of heat recovery of the subsequent circulating acid.

[0014] Furthermore, the height of the acid outlet is lower than the height of the gas lift cap. The beneficial effect of this step is that the condensed acid drips onto the partition plate and can be discharged directly from the acid outlet after converging, without overflowing into the gas lift cap.

[0015] Furthermore, the condenser tube is equipped with a spirally arranged baffle. The beneficial effect of this step is that the baffle extends the contact time between the acid mist and the condenser tube, thereby improving the condensation effect.

[0016] Furthermore: the acid separator is a spray pipe, one end of which extends out of the circulating acid heat transfer section;

[0017] A packing zone is also provided between the acid separator and the flue gas inlet. The packing zone includes a packing support frame and packing material filled in the packing support frame. The beneficial effects of this step are: the spray pipe increases the splashing range of the circulating acid, and the packing material increases the contact area between the circulating acid and the acid mist, thereby improving the heat exchange effect.

[0018] Furthermore, an acid circulation tank is externally connected to the bottom of the liquid accumulation section.

[0019] The acid circulation tank is equipped with an acid discharge port;

[0020] Both the liquid accumulation section and the bottom of the acid circulation tank are equipped with drain outlets. The beneficial effect of this step is that, during the actual reaction process, the circulating acid will still absorb a small amount of SO₂ from the flue gas. 3， This leads to an increase in the amount of circulating acid. Excessive circulating acid will occupy the space in the liquid accumulation section, reduce the amount of flue gas entering the flue, and affect the subsequent acid production.

[0021] Furthermore: the demisting section is equipped with several sets of fiber demisters, which are filled with glass fiber filaments or PTFE filaments. The beneficial effect of this step is that the excess acid mist is removed by the limiting demisters, allowing the exhaust gas to meet the emission standards.

[0022] Furthermore: the cylinder of the liquid accumulation section is made of Q345 carbon steel and is lined with acid-resistant bricks inside;

[0023] The cylinders of the circulating acid heat transfer section and the condensation acid production section are both made of 304 stainless steel and are lined with polytetrafluoroethylene (PTFE) pads.

[0024] The cylinder of the demisting section is made of 316L stainless steel. The advantages of this step are that by combining the characteristics of the corrosiveness of the contents of the cylinder in different stages under different environments, the materials can be selected selectively, which can save costs while ensuring the performance.

[0025] The beneficial effects of this utility model are:

[0026] The combined tower of this application can prevent condensed sulfuric acid from entering the circulating acid in the condensation acid production section, thereby avoiding a drop in the temperature of the circulating acid, reducing the temperature difference with the cooling water, and affecting the efficiency of heat recovery. Attached Figure Description

[0027] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0028] Figure 1 A schematic diagram of a combined tower for wet condensation of sulfuric acid and heat recovery provided by this utility model;

[0029] Figure 2 This utility model provides a structural schematic diagram of the condensation and acid production section of a combined tower for wet condensation of sulfuric acid and heat recovery.

[0030] Figure label:

[0031] 1-Liquid accumulation section; 2-Circulating acid heat transfer section; 3-Condensation and acid production section; 4-Demisting section; 5-Baffle plate; 6-Acid outlet; 7-Acid circulation tank;

[0032] 11-Level gauge; 21-Flue gas inlet; 22-Acid separator; 23-Packaging area; 24-First thermometer; 31-Condenser; 32-Baffle plate; 33-Second thermometer; 41-Fiber demister; 42-Tail gas outlet; 43-Inspection port; 44-Pressure gauge; 51-Lift cap;

[0033] 311 - Demisting structure; 321 - Spiral baffle; 322 - Planar baffle. Detailed Implementation

[0034] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings. These embodiments are merely illustrative of the present invention and should not be construed as limiting the scope of protection of the present invention.

[0035] It should be noted that, unless otherwise stated, the technical or scientific terms used in this application shall have the ordinary meaning as understood by one of ordinary skill in the art to which this utility model pertains.

[0036] Example

[0037] Before explaining this application, it should be noted that in the existing wet acid production technology, the types of waste heat generated are generally divided into three categories: 1. High-temperature waste heat, that is, the heat of SO2 converting into SO3 (the highest reaction temperature); 2. Medium-temperature waste heat, that is, the heat of SO3 and H2O generating H2SO4 gas; 3. Low-temperature waste heat, that is, the heat generated by the circulating acid absorbing too much SO3, and the medium-temperature waste heat absorbed during the spraying process. Then, the circulating acid is sent to the evaporator to exchange heat with deoxygenated water to produce saturated steam and realize energy recovery. However, in the process of generating medium-temperature waste heat, the flue gas (a mixture of SO3 and H2O, the same below) reacts in the absorption tower to generate H2SO4 gas and generates a large amount of reaction heat. The H2SO4 gas is cooled and condensed into sulfuric acid droplets in the condensation section (the working medium used to cool the H2SO4 gas is generally 98% pure sulfuric acid injected into the condenser tube, and the heat of the heated sulfuric acid cannot be fully utilized). However, after the sulfuric acid droplets are formed, they will flow into the circulating acid, lowering the temperature of the circulating acid, thereby reducing the temperature difference between the circulating acid and the cooling water, resulting in a poorer heat recovery effect.

[0038] like Figure 1 As shown, in order to solve the problem of insufficient utilization of heat generated by wet sulfuric acid production, this utility model provides a combined tower for wet sulfuric acid condensation and heat recovery, specifically including: a liquid collection section 1, which is located at the bottom of the combined tower;

[0039] The circulating acid heat transfer section 2 is located above the liquid accumulation section 1. An acid separator 22 is provided at the upper part of the circulating acid heat transfer section 2, and a flue gas inlet 21 is provided at the lower part of the circulating acid heat transfer section 2. The circulating acid enters the circulating acid heat transfer section 2 through the acid separator 22 and is used to absorb the reaction heat of the flue gas entering from the flue gas inlet 21. It should be noted that the proportion and temperature of each component in the flue gas can be controlled so that the partial pressure of each component in the flue gas is less than the partial pressure of the corresponding component in the circulating acid. In this way, the circulating acid will not absorb or will absorb only a small amount of SO3 and H2O in the flue gas, maintaining a low growth rate and only playing a heat transfer role.

[0040] The acid-generating condensation section 3 is located above the circulating acid heat transfer section 2, and a partition 5 is provided between the acid-generating condensation section 3 and the circulating acid heat transfer section 2. The partition 5 is provided with several gas lifting caps 51, and an acid outlet 6 is provided above the partition 5. A condenser tube 31 (generally made of glass) is provided above the gas lifting caps 51. An air inlet is provided above the condenser tube 31, and an air outlet is provided below the condenser tube 31. The cooling medium of the condenser tube 31 is the SO2 flue gas before conversion. Since the SO2 flue gas needs to be heated to the reaction temperature before conversion, the SO2 flue gas can not only cool the acid mist and help it produce acid, but also use the medium-temperature waste heat to raise its own temperature and reach the reaction temperature as soon as possible, which is equivalent to reducing the heating power before conversion.

[0041] Demisting section 4 is located above the condensation and acid production section 3.

[0042] In this application, the sulfuric acid formed after the acid mist in the condensation acid production section 3 is condensed will be discharged directly from the acid outlet 6 and will not fall into the circulating acid, thus not reducing the temperature and concentration of the circulating acid and not affecting the efficiency of heat recovery of the subsequent circulating acid.

[0043] Based on the above technical solution, the height of the acid outlet 6 is lower than the height of the gas lifting cap 51. The condensed acid drips onto the partition plate 5 and can be discharged directly from the acid outlet 6 after converging, without overflowing into the gas lifting cap 51.

[0044] like Figure 2 As shown, based on the above technical solution, the condenser tube 31 includes several glass tubes. The inside of each glass tube is a first flow channel for acid mist, where the acid mist flows in from the bottom and out from the top. Outside the glass tubes is a second flow channel for SO2 flue gas, where the SO2 flue gas flows in from the top side and out from the bottom side. The relative flow of the two increases the heat exchange distance between the fluids inside and outside the glass tubes. A spiral baffle 321 is installed in the first flow channel, and multiple planar baffles 322 are installed in the second flow channel. The spiral baffle 321 extends the flow path of the acid mist, increases the residence time, enlarges the acid mist particle size, and increases the weight of the sulfuric acid droplets, allowing them to flow downwards under gravity. The planar baffles 322 extend the contact time between the SO2 flue gas and the condenser tube 31, improving the heat exchange effect and ultimately enhancing the condensation effect. Furthermore, the outlet of the first flow channel is equipped with a demisting structure filled with materials such as PTFE wire to remove acid mist.

[0045] Based on the above technical solution, the acid separator 22 is a spray pipe, one end of which extends out of the circulating acid heat transfer section 2 and is then connected to an external circulating acid storage tank, and circulation is promoted by a circulating pump.

[0046] A packing zone 23 is also provided between the acid separator 22 and the flue gas inlet 21. The packing zone 23 includes a packing support frame and packing material filled in the packing support frame. The spray pipe is used to increase the spray range of the circulating acid, and the packing material is used to increase the contact area between the circulating acid and the acid mist, thereby improving the heat exchange effect.

[0047] Based on the above technical solution, an acid circulation tank 7 is also externally connected to the bottom of the liquid accumulation section 1.

[0048] The acid circulation tank 7 is equipped with an acid discharge port;

[0049] Both the liquid accumulation section 1 and the bottom of the acid circulation tank 7 are equipped with drain outlets; during the actual reaction process, the circulating acid will still absorb a small amount of SO2 from the flue gas. 3， This leads to an increase in the amount of circulating acid. Excessive circulating acid will occupy the space of the liquid accumulation section 1, reduce the amount of flue gas entering the system, and affect the subsequent acid production. Therefore, it is necessary to discharge the excess circulating acid into the acid circulation tank 7.

[0050] Based on the above technical solution, the demisting section 4 is provided with several sets of fiber demisters 41, which are filled with glass fiber filaments or PTFE filaments; the excess acid mist is removed by the limiting demisters, so that the exhaust gas meets the emission standards.

[0051] Based on the above technical solution, the cylinder of the liquid accumulation section 1 is made of Q345 carbon steel and is lined with acid-resistant bricks inside.

[0052] The cylinders of the circulating acid heat transfer section 2 and the condensation acid production section 3 are both made of 304 stainless steel and are lined with polytetrafluoroethylene.

[0053] The cylinder of the demister section 4 is made of 316L stainless steel. By selectively choosing materials based on the varying corrosiveness of the contents in different environments at different stages, the effectiveness of the product can be guaranteed while saving costs. Furthermore, the acid separator 22 and the pipes through which the circulating acid flows can be made of 310S stainless steel or high-silicon stainless steel.

[0054] In the above embodiments, this application also provides a level gauge 11 at the liquid accumulation section 1 to monitor the circulating acid storage in the liquid accumulation section 1, so that the circulating acid storage has sufficient heat carrying capacity without occupying too much reaction space; a first thermometer 24 is provided above the condensation acid production section 3 and a second thermometer 33 is provided above the circulating acid heat transfer section. By comparing the temperature difference between the two thermometers, the quality of the condensation effect can be determined; and pressure gauges are provided at both ends of the demisting section 4 to monitor the filtration and demisting effect from the pressure difference between the two locations.

[0055] This application aims to separate and utilize high, medium, and low-temperature waste heat as much as possible, eliminating heat loss during wet acid production, and maximizing the utilization of waste heat.

[0056] Numerous specific details are set forth in this specification. However, it will be understood that embodiments of this invention may be practiced without these specific details. In some instances, well-known methods, structures, and techniques have not been shown in detail so as not to obscure the understanding of this specification. In the description of this specification, references to the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of the different embodiments or examples.

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and not to limit it. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this utility model, and they should all be covered within the scope of the claims and specification of this utility model.

Claims

1. A combined column for wet condensing sulfuric acid and heat recovery, characterized by, The application relates to a combined tower for producing sulfuric acid, which comprises the following parts: a liquid accumulation section arranged at the bottom of the combined tower; a circulating acid heat removal section arranged above the liquid accumulation section, wherein the upper part of the circulating acid heat removal section is provided with an acid distributor, and the lower part of the circulating acid heat removal section is provided with a flue gas inlet; a condensation acid production section arranged above the circulating acid heat removal section, wherein a partition plate is arranged between the condensation acid production section and the circulating acid heat removal section, a plurality of lift caps are arranged on the partition plate, an acid outlet is arranged above the partition plate, a condensation pipe is arranged above the lift caps, an air inlet is arranged above the condensation pipe, and an air outlet is arranged below the condensation pipe; a demisting section arranged above the condensation acid production section.

2. The combined column for wet condensation of sulphuric acid and heat recovery according to claim 1, characterized in that, The height of the acid outlet is lower than the height of the lift caps.

3. The combined column for wet condensation of sulphuric acid and heat recovery according to claim 1, characterized in that, The condensation pipe is internally provided with helically arranged baffles.

4. The combined column for wet condensation of sulphuric acid and heat recovery according to claim 1, characterized in that, The acid distributor is a spray pipe, one end of the spray pipe extends out of the circulating acid heat removal section. A filler area is further arranged between the acid distributor and the flue gas inlet, and the filler area comprises a filler support frame and fillers filled in the filler support frame.

5. The combined column for wet condensation of sulphuric acid and heat recovery according to claim 1, characterized in that, The bottom of the liquid accumulation section is further externally connected with an acid circulation groove, the acid circulation groove is provided with an acid outlet, the bottom of the liquid accumulation section and the bottom of the acid circulation groove are both provided with a blowdown outlet.

6. The combined column for wet condensation of sulphuric acid and heat recovery according to claim 1, characterized in that, A plurality of groups of fiber demisters are arranged in the demisting section, and the fiber demisters are filled with glass fiber filaments or tetrafluoro filaments.

7. The combined column for wet condensation of sulphuric acid and heat recovery according to claim 1, characterized in that, The cylinder body of the liquid accumulation section is made of Q345 carbon steel, and is internally attached with acid-resistant bricks; the cylinder bodies of the circulating acid heat removal section and the condensation acid production section are both made of 304 stainless steel, and are internally lined with polytetrafluoroethylene pads; the cylinder body of the demisting section is made of 316L stainless steel.

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