Energy recovery system
By designing an energy recovery system in the acetic anhydride production process of acetic acid cracking, the condensed water is heated by using the heat during high-temperature vapor to condense to generate pressurized steam, the problem of heat waste in high-temperature thermal logistics is solved, and efficient heat utilization and energy saving and consumption reduction are achieved.
Patent Information
- Application Number
- CN202420750673.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-04-12
- Publication Date
- 2025-04-18
- Estimated Expiration
- 2034-04-12
AI Technical Summary
In the acetic anhydride process for cleavage of acetic acid, the condensation and cooling of the high-temperature thermal logistics require a large amount of cooling medium, resulting in waste of heat, and the prior art is difficult to effectively utilize the thermal energy in the high-temperature thermal logistics.
An energy recovery system is designed, including a heat exchanger and a gas-liquid separator. By heating the condensed water by evaporating high-temperature vapor after the evaporation of crude acetic anhydride, a low-pressure vapor is generated, and the pressure is raised through the steam compressor to obtain high-quality supercharged vapor.
The full utilization of heat energy is achieved, the demand for steam production in boilers is reduced, energy consumption is reduced, the efficiency of heat energy utilization is improved, and the cost of steam production is reduced.
Smart Images
Figure CN222773269U_ABST
Abstract
Description
Technical Field
[0001] The utility model belongs to the field of energy recycling and relates to an energy recovery system. Background Art
[0002] In the process of producing acetic anhydride by cracking acetic acid, the cracking temperature of acetic acid is as high as nearly 700°C. In order to prevent the reverse reaction, the high-temperature cracking gas needs to be condensed and cooled in a very short time. After acetic acid absorbs ketene, acetic anhydride is generated, which is mixed with unreacted acetic acid and then separated by distillation. During the whole process, the condensation and cooling of high-temperature hot logistics not only consumes a large amount of cooling water, frozen brine and other cooling media, but also wastes the heat in the high-temperature hot logistics. Utility Model Content
[0003] The utility model provides an energy recovery system, which can improve the thermal energy utilization efficiency of the acetic anhydride separation and purification process in the process of preparing acetic anhydride by acetic acid cracking method.
[0004] The purpose of the utility model can be achieved through the following technical solutions:
[0005] An energy recovery system is used in the process of preparing acetic anhydride by cracking acetic acid, comprising a heat exchanger and a first gas-liquid separator. The heat exchanger is provided with a heat exchange tube, the water inlet end of the heat exchange tube is connected to a first pipeline, the water outlet end of the heat exchange tube is connected to a second pipeline, the water outlet end of the second pipeline is connected to the first gas-liquid separator, condensed water enters the heat exchanger through the first pipeline, and the first pipeline is also connected to a pressure pump.
[0006] Optionally, a storage container for storing condensed water is further included, and the first pipeline is connected to the storage container.
[0007] Optionally, it further includes a second gas-liquid separator disposed downstream of the first gas-liquid separator, the first gas-liquid separator and the second gas-liquid separator are connected via a third pipe, and the open end of the third pipe is connected to the upper part of the first gas-liquid separator.
[0008] Optionally, a steam compressor is provided on the third pipeline.
[0009] Optionally, a fifth pipeline is further connected to the lower portion of the second gas-liquid separator, and a water outlet end of the fifth pipeline is connected to a storage container.
[0010] Optionally, a fourth pipeline is further connected to the lower portion of the first gas-liquid separator, and a water outlet end of the fourth pipeline is connected to a fifth pipeline or directly connected to a storage container.
[0011] Optionally, a gas-liquid separation structure is provided in both the first gas-liquid separator and the second gas-liquid separator.
[0012] Optionally, the gas-liquid separation structure is one or more of a baffle, a wire mesh, and a filler.
[0013] Optionally, the heat exchanger includes a plate heat exchanger or a shell and tube heat exchanger.
[0014] Optionally, the steam compressor is a screw steam compressor.
[0015] The beneficial effects of the utility model include:
[0016] Compared with directly using a boiler to produce saturated water vapor, the energy recovery system disclosed in the utility model can obtain a large amount of low-pressure steam by supplying pressurized condensed water with a temperature higher than the water vaporization temperature with the waste heat released after evaporation of crude acetic anhydride and cooling it, and can obtain more low-pressure steam than directly reducing the pressure of condensed water. After pressurization and temperature increase, this part of low-pressure steam obtains higher-quality pressurized steam, which is suitable for more usage scenarios. Therefore, the saturated steam formed after the condensed water absorbs heat can replace part of the saturated steam produced by the boiler, reducing the amount of boiler saturated steam consumed in the industrial production process, thereby reducing energy consumption and truly achieving energy saving and consumption reduction. At the same time, the steam production cost of the energy recovery system of the utility model is significantly lower than the cost of boiler steam production. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Figure 1 The utility model discloses an energy recovery system structure schematic diagram.
[0018] In the figure: 1. storage container; 2. pressure pump; 3. heat exchanger; 4. first gas-liquid separator; 5. steam compressor; 6. second gas-liquid separator; 7. first pipeline; 8. second pipeline; 9. third pipeline; 10. fourth pipeline; 11. fifth pipeline. DETAILED DESCRIPTION
[0019] The utility model is further described below in conjunction with the accompanying drawings and embodiments.
[0020] In the process of preparing acetic anhydride by acetic acid cracking, the temperature of the steam formed after the crude acetic anhydride evaporates is relatively high. When these steam condenses, they can release considerable latent heat of phase change. Therefore, the heat released when the crude acetic anhydride steam condenses can be used to heat the condensed water at a temperature of about 100°C. After the condensed water absorbs heat, a large amount of low-pressure steam will be generated, which can not only fully utilize the thermal energy, but also save a lot of energy consumption for producing steam. To this end, the inventor proposes an energy recovery system mainly used in the process of preparing acetic anhydride by acetic acid cracking, which recovers a large amount of condensation heat in the process and achieves the effect of energy saving and emission reduction.
[0021] like Figure 1As shown, an energy recovery system includes a storage container 1 for storing condensate and a heat exchanger 3. A first pipe 7 is connected between the storage container 1 and the heat exchanger 3. A pressure pump 2 is also provided on the first pipe 7 to pressurize the condensate. The condensate in the storage container 1 is pressurized by the pressure pump 2 and then transported to the heat exchanger 3 through the first pipe 7.
[0022] The storage container 1 is also connected to a water inlet pipe, and condensed water generated in other production processes can enter the storage container 1 through the water inlet pipe.
[0023] Heat exchange tubes are arranged in the heat exchanger 3, and the open ends of the heat exchange tubes are connected to the outlet end of the first pipe 7. A flow path of high-heat material is also formed in the heat exchanger 3. Accordingly, a feed port and a discharge port of the high-heat material flow path are also provided on the heat exchanger 3. The high-heat material flow path enters the heat exchanger 3 from the feed port and finally leaves the heat exchanger 3 from the feed port. In order to improve the heat exchange efficiency, the flow direction of the high-heat material in the heat exchanger 3 is opposite to the flow direction of the condensed water in the heat exchanger 3. In short, the high-heat material flow is introduced into the heat exchanger 3 at the same time as the condensed water, and the condensed water absorbs heat from the high-heat material and the temperature rises.
[0024] The first pipeline 7 is connected to a solenoid valve for controlling the water inflow of the heat exchanger 3 .
[0025] The energy recovery system also includes a first gas-liquid separator 4, which is arranged downstream of the heat exchanger 3. A second pipeline 8 is arranged between the heat exchanger 3 and the first gas-liquid separator 4, that is, the heat exchanger 3 is connected to the first gas-liquid separator 4 through the second pipeline 8, and the open end of the second pipeline 8 is fixedly connected to the outlet end of the heat exchange tube of the heat exchanger 3, and the outlet end thereof is fixedly connected to the opening of the first gas-liquid separator 4, and the condensed water flowing out of the heat exchanger 3 flows into the first gas-liquid separator 4 through the second pipeline 8.
[0026] The temperature of the condensed water entering the heat exchanger 3 is substantially the same as the boiling temperature of water. After entering the heat exchange tube of the heat exchanger 3, the condensed water absorbs heat and its temperature rises to become superheated water. Since the first gas-liquid separator 4 has a relatively large internal accommodating chamber, after the superheated water enters the internal accommodating chamber of the first gas-liquid separator 4 through the second pipe 8, the pressure on the superheated water decreases due to the increase in the internal volume of the container. When the pressure is less than the saturated pressure of water vaporization at this temperature, the superheated water will generate a large amount of low-pressure steam in the gas-liquid separator.
[0027] The upper part of the first gas-liquid separator 4 is also connected to a third pipe 9. The superheated water moves in the upper space of the first gas-liquid separator 4 accommodating chamber, and finally flows out of the first gas-liquid separator 4 through the third pipe 9, while the ungasified water gathers at the bottom of the first gas-liquid separator 4 accommodating chamber.
[0028] Furthermore, in order to improve the gas-liquid separation effect, a baffle is arranged in the accommodating chamber of the first gas-liquid separator 4, and the baffle can intercept the mixed droplets in the low-pressure steam generated by the hot water, so that the formed steam is drier and has better steam quality.
[0029] The first gas-liquid separator 4 outputs low-pressure steam, and pressurized steam can be obtained by pressurizing the low-pressure steam. Therefore, a steam compressor 5 is also connected to the third pipeline 9 to pressurize the low-pressure steam output by the first gas-liquid separator 4 to obtain pressurized steam.
[0030] After the low-pressure steam is pressurized, part of the low-pressure steam will liquefy into liquid. In order to obtain dry high-quality pressurized steam, the pressurized steam formed by the steam compressor 5 needs to be further dried. Therefore, a second gas-liquid separator 6 is provided downstream of the first gas-liquid separator 4. Therefore, the outlet end of the third pipeline 9 is connected to the second gas-liquid separator 6. The steam pressurized by the steam compressor 5 enters the second gas-liquid separator 6 through the third pipeline 9.
[0031] The second gas-liquid separator 6 has the same structure as the first gas-liquid separator 4. In other words, a baffle is also arranged in the accommodating chamber of the second gas-liquid separator 6. After the steam output by the steam compressor 5 passes through the baffle, the liquid droplets and the steam are separated. The second gas-liquid separator 6 is also connected to an exhaust pipe. The dry pressurized steam is discharged from the second gas-liquid separator 6 through the exhaust pipe and is collected for production use. The intercepted liquid droplets are collected at the bottom of the second gas-liquid separator 6.
[0032] A fourth pipe 10 is connected to the lower part of the first gas-liquid separator 4, and a fifth pipe 11 is also connected to the bottom of the second gas-liquid separator 6 to discharge the liquid droplets collected at the bottom. Considering that the condensed water collected from the gas-liquid separator is also at a relatively high temperature, the outlet ends of the fourth pipe 10 and the fifth pipe 11 can be connected to the storage container 1, so that the condensed water separated from the gas-liquid separator can enter the gasification cycle again.
[0033] In other embodiments, the water outlet end of the fourth pipe 10 can also be connected to the fifth pipe, and the water outlet end of the fifth pipe 11 can be connected to the storage container 1; or the water outlet end of the fifth pipe 11 can be connected to the fourth pipe 10, and the water outlet end of the fourth pipe 10 can be connected to the storage container 1.
[0034] Optionally, in addition to the baffle plates, the first gas-liquid separator 4 and the second gas-liquid separator 6 may also be provided with one or more structures capable of achieving gas-liquid separation, such as wire mesh and filler, to achieve the gas-liquid separation function.
[0035] Optionally, the heat exchanger 3 may be a plate heat exchanger 3 or a shell and tube heat exchanger 3 .
[0036] Optionally, the steam compressor 5 is a screw steam compressor 5 that can provide a high compression ratio.
[0037] It should be noted that the high-temperature material introduced into the heat exchanger 3 is crude acetic anhydride vapor.
[0038] Embodiment 1
[0039] The temperature of the condensed water in the storage container 1 is 109.9°C. The condensed water is transported to the heat exchanger 3 via the pressure pump 2. The condensed water inlet of the heat exchanger 3 is controlled by the solenoid valve to be 450 kg / min. After the pressurized condensed water absorbs heat in the heat exchanger 3, the temperature rises slightly to 110.1°C. The steam flow rate is measured in the third pipeline 9 to be approximately 40 kg / min. The remaining unvaporized condensed water in the first gas-liquid separator 4 flows back to the storage container 1 and the condensed water storage container 1 through the fourth pipeline 10 for recycling.
[0040] The temperature of the high-heat material measured at the feed port of the heat exchanger 3 is 136°C, and the temperature of the high-heat material measured at the discharge port of the heat exchanger 3 is 120°C. Part of the heat of the high-heat material is absorbed by the condensed water in the heat exchanger 3, which reduces the energy consumption of heating the condensed water and makes full use of the heat of the high-heat material. At the same time, the temperature of the high-heat material drops, and less cooling water can be used in the subsequent cooling of the high-heat material, saving cooling water.
[0041] The low-pressure steam pressure in the third pipeline 9 is measured to be 0.14 MPa. After the low-pressure steam is compressed by the steam compressor 5, for example, when the compression ratio of the steam compressor 5 is 3, the boosted steam pressure measured in the exhaust pipe reaches 0.4 MPa.
[0042] Embodiment 2
[0043] The temperature of the condensed water in the storage container 1 is 104.9°C. The condensed water is transported to the heat exchanger 3 via the pressure pump 2. The condensed water inlet of the heat exchanger 3 is controlled by the solenoid valve to be 450 kg / min. After the pressurized condensed water absorbs heat in the heat exchanger 3, the temperature rises slightly to 105.3°C. The steam flow rate is measured in the third pipeline 9 to be about 38 kg / min. The remaining unvaporized condensed water in the first gas-liquid separator 4 flows back to the storage container 1 and the condensed water storage container 1 through the fourth pipeline 10 for recycling.
[0044] The temperature of the high-heat material measured at the feed port of the heat exchanger 3 is 120°C, and the temperature of the high-heat material measured at the discharge port of the heat exchanger 3 is 114°C. Part of the heat of the high-heat material is absorbed by the condensed water in the heat exchanger 3, which reduces the energy consumption of heating the condensed water and makes full use of the heat of the high-heat material. At the same time, the temperature of the high-heat material drops, and less cooling water can be used in the subsequent cooling of the high-heat material, saving cooling water.
[0045] The low-pressure steam pressure in the third pipeline 9 is measured to be 0.12 MPa. After the low-pressure steam is compressed by the steam compressor 5, for example, when the compression ratio of the steam compressor 5 is 2.5, the boosted steam pressure measured in the exhaust pipe reaches 0.3 MPa.
[0046] It should be noted that the pressure in the energy recovery system disclosed in the present invention is always greater than the standard atmospheric pressure, so even when the temperature of the condensed water is higher than 100° C., it can maintain a liquid state without gasification.
[0047] It should be noted that the low-pressure steam mentioned above is steam with a pressure of 0.05 to 0.15 MPa, and the pressurized steam is steam with a pressure of 0.4 to 0.6 MPa.
[0048] In addition, it should be noted that the pressures mentioned above are all relative pressures.
[0049] The above-mentioned related explanations and descriptions of the embodiments are for the purpose of facilitating the understanding and application of the present invention by ordinary technicians in the technical field. It is obvious that those familiar with the technical field can easily make various modifications to these contents and apply the general principles described herein to other embodiments without creative work. The present invention is not limited to the above-mentioned related explanations and descriptions of the embodiments. Improvements and modifications made by technicians in the field based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.
Claims
1. An energy recovery system for use in the process of producing acetic anhydride by cracking acetic acid, characterized in that: It includes a heat exchanger and a first gas-liquid separator. The heat exchanger is provided with a heat exchange tube. The water inlet end of the heat exchange tube is connected to a first pipeline. The water outlet end of the heat exchange tube is connected to a second pipeline. The water outlet end of the second pipeline is connected to the first gas-liquid separator. Condensate enters the heat exchanger through the first pipeline. The first pipeline is also connected to a pressure pump.
2. The energy recovery system according to claim 1, characterized in that: The invention also comprises a storage container for storing condensed water, wherein the first pipe is connected to the storage container.
3. The energy recovery system according to claim 1, characterized in that: It also includes a second gas-liquid separator arranged downstream of the first gas-liquid separator, the first gas-liquid separator and the second gas-liquid separator are connected through a third pipeline, and the open end of the third pipeline is connected to the upper part of the first gas-liquid separator.
4. The energy recovery system according to claim 3, characterized in that: The third pipeline is provided with a steam compressor.
5. The energy recovery system according to claim 3, characterized in that: The lower part of the second gas-liquid separator is also connected to a fifth pipeline, and the water outlet end of the fifth pipeline is connected to the storage container.
6. The energy recovery system according to claim 3, characterized in that: The lower part of the first gas-liquid separator is also connected to a fourth pipeline, and the water outlet end of the fourth pipeline is connected to the fifth pipeline or directly connected to the storage container.
7. The energy recovery system according to claim 6, characterized in that: The first gas-liquid separator and the second gas-liquid separator are both provided with a gas-liquid separation structure.
8. The energy recovery system according to claim 7, characterized in that: The gas-liquid separation structure is one or more of a baffle, a wire mesh, and a filler.
9. The energy recovery system according to claim 1, characterized in that: The heat exchanger includes a plate heat exchanger or a shell and tube heat exchanger.
10. The energy recovery system according to claim 4, characterized in that: The steam compressor is a screw steam compressor.