Recycling system for acetic acid recovery discharged produced water

Abstract

The utility model discloses a recycling system for acetic acid recovery discharged produced water, which belongs to the technical field of waste liquid treatment and comprises a circulating pump, a heat exchanger a, a refrigerating machine, an acetic acid recovery system and a waste water storage tank, the circulating pump is communicated with the heat exchanger a through a pipeline, and the heat exchanger a is communicated with the refrigerating machine through a pipeline; the refrigerating machine is communicated with the acetic acid recovery system through a pipeline, and the acetic acid recovery system is communicated with the waste water storage tank through a pipeline, and is characterized in that a heat exchanger b is additionally arranged between the heat exchanger a and the refrigerating machine, and the waste water storage tank is communicated with the heat exchanger b through a pipeline to form heat exchange so as to secondarily cool process water; the device is mainly applied to an acetic acid recovery unit in the PTA production process.

Description

Technical Field

[0001] The utility model relates to the technical field of waste liquid treatment, in particular to a system for recycling and reusing the externally discharged water from acetic acid recovery. Background Technique

[0002] In the production process of PTA with the latest process, the acetic acid content in the water produced by the acetic acid recovery unit is between 3,000 - 4,000 PPM, the temperature is about 23 °C, and the flow rate is 80 tons per hour. This water has been directly pumped to the sewage treatment unit as wastewater and lacks effective utilization. Therefore, it is of great significance to carry out the research and development project on the reuse of the water produced by the PTA acetic acid recovery unit.

[0003] At present, in several newly launched similar devices in China, the utilization of the water produced by the acetic acid recovery unit is limited. This water has a low temperature and a low acid content, and there is a large space for reuse.

[0004] After research by the applicant, improvements and research are mainly carried out from the following aspects, which can achieve the purpose of wastewater reuse, and remarkable results have been obtained in the actual application process, and it is suitable for comprehensive promotion and application.

[0005] The temperature of the cooling water used in the PTA device is between 28 - 35 °C. The wastewater at 23 °C is much lower than the temperature of the cooling water used in the device, and can partially replace the cooling water to cool down the device materials. The cooling effect is better than that of the device cooling water.

[0006] Low temperature and low acid content: The process water of the PTA device is 35 °C, and the acid content is about 1.8%. The wastewater with a low acid content at 23 °C can replace part of the process water of the PTA device as the spray water of the washing tower, and the washing effect is better.

[0007] Wastewater reuse: As the spray water of the waste gas washing device, it is directly discharged to the sewage treatment device after use. It can save an equal amount of deionized water or industrial water. Content of the Utility Model

[0008] The purpose of the utility model is to provide a system for recycling and reusing the externally discharged water from acetic acid recovery to solve the problems raised in the above background technique.

[0009] To achieve the above purpose, the utility model provides the following technical solutions:

[0010] A system for recycling and reusing the externally discharged water from acetic acid recovery includes a circulation pump, a heat exchanger a, a chiller, an acetic acid recovery system, and a wastewater storage tank. The circulation pump is connected to the heat exchanger a through a pipeline, the heat exchanger a is connected to the chiller through a pipeline, the chiller is connected to the acetic acid recovery system through a pipeline, and the acetic acid recovery system is connected to the wastewater storage tank through a pipeline. Since the above equipment belongs to the prior art, the applicant will not elaborate here.

[0011] The core improvements of the present utility model are as follows:

[0012] A heat exchanger b is added between the heat exchanger a and the chiller. The heat exchanger b is used for secondary cooling heat exchange, thereby reducing the steam consumption of the chiller. The waste water storage tank is connected to the heat exchanger b through a pipeline to form a heat exchange for secondary cooling of the process water.

[0013] The working principle of the above improvement is as follows:

[0014] The low-temperature waste water generated by the acetic acid recovery system is used to cool the process water. Before the process water enters the acetic acid recovery system, it is cooled by secondary heat exchange in the heat exchanger b to reduce the temperature of the process water, thereby achieving the purpose of reducing the VLS steam consumption of the chiller. Especially during the operation of the device in summer, when the temperature of the device cooling water rises from 28°C to 34°C, this development can ensure that the feed temperature of the acetic acid recovery membrane module is stable at 18 - 20°C, and stabilize the normal operation of the acetic acid recovery unit.

[0015] Preferably: In order to make better use of the process waste water, the heat exchanger b is connected to the vent scrubber through a pipeline. The vent scrubber normally uses TW separated water and RW industrial water for spray washing, with a consumption of 10 tons per hour. The low-temperature waste water generated by the acetic acid recovery system has a low acid content and a small amount of organic matter, and can completely replace TW separated water and RW industrial water for spray washing, saving the consumption of TW separated water and RW industrial water in the device. At the same time, the waste water with a low acid content can dissolve the sodium salt crystals formed in the vent scrubber, improving the washing effect in the tower.

[0016] Compared with the prior art, the beneficial effects of the present utility model are as follows:

[0017] (1) The feed temperature before the chiller in the acetic acid recovery unit is reduced from 35°C to about 29°C.

[0018] (2) The VLS steam consumption of the acetic acid recovery chiller is reduced by 800 kg / hour.

[0019] (3) The consumption of TW separated water and RW industrial water in the device is reduced by 10 tons per hour.

[0020] (4) The sewage discharge of the device is reduced by 10 tons per hour. Description of the Drawings

[0021] Figure 1 It is the working principle diagram of the present utility model. Detailed Embodiment

[0022] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0023] Please refer to Figure 1 , a technical solution provided by the present invention:

[0024] Add a heat exchanger b3 between the heat exchanger a2 and the refrigerator 4, and use the low-temperature wastewater generated by the acetic acid recovery system 6 to cool the process water. Before the process water enters the acetic acid recovery system 6, it is secondarily cooled by the heat exchanger b3. Since the temperature of the process water after secondary cooling is lower, the consumption of VLS steam by the refrigerator 4 is reduced. Especially during the operation of the device in summer, when the temperature of the device cooling water rises from 28 °C to 34 °C, this development can ensure that the feed temperature of the acetic acid recovery membrane module is stable at 18 - 20 °C, and the normal operation of the acetic acid recovery unit is stabilized.

[0025] Since the vent scrubber 5 normally uses TW separated water and RW industrial water for spray washing, with a consumption of 10 tons per hour. The low-temperature wastewater generated by the acetic acid recovery system has a low acid content and a small amount of organic matter, and can completely replace TW separated water and RW industrial water for spray washing, saving the consumption of TW separated water and RW industrial water in the device. At the same time, the wastewater with a low acid content can dissolve the sodium salt crystals formed in the vent scrubber 5, improving the washing effect in the scrubber 5.

[0026] In this embodiment, the basic principles, main features and advantages of the present invention have been shown and described above. Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments and the descriptions in the specification are only preferred examples of the present invention and do not limit the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. A system for reusing the externally discharged production water for acetic acid recovery, comprising a circulation pump (1), a heat exchanger a (2), a chiller (4), an acetic acid recovery system (6) and a waste water storage tank (7). The circulation pump (1) is connected to the heat exchanger a (2) through a pipeline. The heat exchanger a (2) is connected to the chiller (4) through a pipeline. The chiller (4) is connected to the acetic acid recovery system (6) through a pipeline. The acetic acid recovery system (6) is connected to the waste water storage tank (7) through a pipeline. It is characterized in that, a heat exchanger b (3) is added between the heat exchanger a (2) and the chiller (4), and the waste water storage tank (7) is connected to the heat exchanger b (3) through a pipeline to form a heat exchange for secondary cooling of the process water.

2. The acetic acid recovery and discharged water reuse system according to claim 1, wherein The heat exchanger b (3) is connected to an air release scrubbing tower (5) through a pipeline.

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