Centrifugal mother liquor wastewater back to kettle treatment system

Abstract

The application provides a centrifugal mother liquor wastewater back to the kettle treatment system, comprising: a catalytic containing unit for reducing the chemical oxygen demand and the colority of the centrifugal mother liquor wastewater, and a filtered water treatment unit for filtering and classifying the centrifugal mother liquor wastewater after treatment; the catalytic containing unit comprises an ozone module, a catalytic module, an inner containing module and an outer containing module; the inner containing module is arranged in the outer containing module; the catalytic module is arranged in the inner containing module; the ozone module is communicated with the inner containing module and extends into the lower part of the inner containing module, so that the ozone released by the ozone module enters the inner containing module and the outer containing module, and a chemical reaction occurs among the ozone, the centrifugal mother liquor wastewater and the catalytic module; and the outer containing module is connected with the filtered water treatment unit. After the final centrifugal mother liquor wastewater is discharged from the outer containing module, the circulating water replenishment standard is reached, the centrifugal mother liquor wastewater can be reused in the original polymerization kettle, and the purpose of high-order reuse of the centrifugal mother liquor wastewater is achieved.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and in particular to a centrifugal mother liquor wastewater return treatment system. Background Technology

[0002] Currently, a large amount of centrifugal mother liquor wastewater is generated during the production of polyvinyl chloride (PVC). This centrifugal mother liquor wastewater is characterized by large discharge volume, relatively low conductivity, and poor biodegradability.

[0003] However, the mainstream domestic manufacturers treat centrifugal mother liquor wastewater using a combination of biological treatment, coagulation sedimentation, and filtration. The treated wastewater can only be used for circulating water makeup, stripping tower or polymerization reactor rinsing water, and acetylene water, failing to meet the water quality standards for polymerization reactors and thus constituting downgraded reuse. Additionally, a small number of manufacturers further treat the biochemically treated centrifugal mother liquor wastewater using a dual-membrane method. While this method meets the water quality standards for reactor return, the recovery rate of the return system is low, investment and operating costs are high, and the resulting concentrated wastewater requires secondary treatment. Summary of the Invention

[0004] In view of the problems existing in the background technology, the purpose of the present invention is to provide a centrifugal mother liquor wastewater return treatment system, which can not only effectively treat the biochemically treated mother liquor wastewater that meets the circulating water replenishment standard, but also return the treated mother liquor wastewater to the original polymerization reactor for use, thereby achieving the purpose of high-level reuse of centrifugal mother liquor wastewater.

[0005] To achieve the above objectives, the present invention provides a centrifugal mother liquor wastewater return treatment system, comprising: a catalytic containment unit and a water filtration unit connected to each other, wherein the catalytic containment unit is used to reduce the chemical oxygen demand and color of the centrifugal mother liquor wastewater, and the water filtration unit is used to filter and classify the centrifugal mother liquor wastewater after treatment.

[0006] The catalytic containment unit includes an ozone module, a catalytic module, an internal containment module, and an external containment module. The internal containment module is disposed within the external containment module, and the catalytic module is disposed within the internal containment module. The ozone module is connected to the internal containment module and extends into the lower part of the internal containment module, so that the ozone released by the ozone module enters the internal containment module and the external containment module, causing a chemical reaction between the ozone, the centrifuged mother liquor wastewater, and the catalytic module. The external containment module is connected to the water filtration treatment unit.

[0007] Optionally, the content storage module includes a first content storage unit and a second content storage unit formed by division, the first content storage unit and the second content storage unit being separated by a partition and arranged side by side independently;

[0008] The catalyst in the catalytic module is divided into two parts and disposed in the first and second internal containers respectively. The catalyst divided into two parts is located in the middle region of the first and second internal containers respectively, so that the lower and upper parts of the first and second internal containers form independent spaces.

[0009] The ozone module extends into a separate space from the lower part.

[0010] Optionally, the outer containment module includes an outer containment container and two water outlet weirs. The two water outlet weirs are respectively disposed on the upper sides of the outer containment container for drainage. The two water outlet weirs are respectively connected to the water filtration unit. The inner containment module is disposed inside the outer containment container.

[0011] Optionally, the ozone module includes an ozone pipeline and two aerators, with the two aerators connected to the ozone pipeline. The two aerators are respectively disposed in the lower independent spaces of the first and second internal containers.

[0012] Optionally, the catalytic containment unit further includes a water inlet module, which is connected to the upper part of the internal containment module to transport centrifuged mother liquor wastewater into the internal containment module, and the water inlet module is connected to the lower part of the internal containment module to clean the internal containment module.

[0013] Optionally, the water inlet module includes a water inlet pipe, a pulse valve, a water inlet valve, and two water distributors. The two water distributors are located at the lower part of the internal storage module. The pulse valve is respectively installed between the water inlet pipe and the two water distributors to control the connection or closure between the water inlet pipe and the two water distributors. The water inlet pipe is connected to the upper part of the internal storage module, and a water inlet valve is provided on the water inlet pipe to control the centrifugal mother liquor wastewater to enter the internal storage module.

[0014] Optionally, the water filtration unit includes a water filtration module and a water quality standard module, the water filtration module and the water quality standard module are connected, and the external receiving module is connected to the water filtration module.

[0015] Optionally, the water filtration module includes a carbon filter tank and a filtered water tank, the carbon filter tank and the filtered water tank are connected, and the filtered water tank is connected to the water quality standard module.

[0016] Optionally, the water quality standard module includes a cation exchange bed, a decarbonator, an intermediate water tank, an anion exchange bed, and a mixed bed connected in sequence, and the filtered water tank is connected to the cation exchange bed.

[0017] Optionally, it also includes a wastewater tank, a pure water tank, and a neutralization tank. The filtered water tank is connected to the wastewater tank, the water quality standard module is connected to the pure water tank, the cation bed is connected to both the wastewater tank and the neutralization tank, and the anion bed is connected to both the wastewater tank and the neutralization tank.

[0018] This invention catalyzes the self-decomposition of ozone in water by placing the internal nano-module within the external containing module, the catalytic module within the internal nano-module, and the ozone module communicating with and extending into the lower part of the internal nano-module. This catalyzes the self-decomposition of ozone in water, increasing the amount of OH generated in the water. - The concentration is increased to improve the ozone oxidation effect, and the reaction is further carried out in the outer containment module. This allows the final centrifugal mother liquor wastewater to meet the circulating water replenishment standard after being discharged from the outer containment module, and then return to the original polymerization reactor for reuse, thus achieving the goal of high-level reuse of centrifugal mother liquor wastewater. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the catalytic containment unit structure of the centrifugal mother liquor wastewater return treatment system according to an embodiment of the present invention;

[0020] Figure 2 This is a schematic diagram of the filtration unit structure of the centrifugal mother liquor wastewater return treatment system according to an embodiment of the present invention.

[0021] The reference numerals in the attached figures are explained as follows:

[0022] Content storage module 10, first content storage unit 11, second content storage unit 12;

[0023] External containment module 20, external containment container 22, water outlet weir 21, reaction zone 23;

[0024] Catalyst module 30, catalysts 31 and 32;

[0025] Ozone module 40, ozone pipeline 43, aerators 41 and 42;

[0026] Water inlet module 50, water inlet pipe 51, water distributor 52, 53, pulse valve 54, 55, water inlet valve 56;

[0027] Filter module 60, carbon filter tank 61, filtered water tank 62;

[0028] Water quality standard module 70, cation bed 71, decarbonator 72, intermediate water tank 73, anion bed 74, mixed bed 75, wastewater pool 76, pure water tank 77, neutralization pool 78. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of this application, but not all embodiments.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein in the specification of the application is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings of this application are intended to cover non-exclusive inclusion.

[0031] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0032] The following reference Figure 1 and Figure 2 The present application describes a centrifugal mother liquor wastewater recycling system according to this application. The system includes a catalytic containment unit and a filtration unit connected to each other. The catalytic containment unit reduces the chemical oxygen demand (COD) and color of the centrifugal mother liquor wastewater (hereinafter referred to as wastewater). The filtration unit filters and classifies the treated centrifugal mother liquor wastewater. Figure 1 As shown, the catalytic containment unit includes an ozone module 40, a catalytic module 30, an internal containment module 10, and an external containment module 20. The internal containment module 10 is disposed within the external containment module 20, and the catalytic module 30 is disposed within the internal containment module 10. The ozone module 40 communicates with the internal containment module 10 and extends into its lower part, allowing ozone released from the ozone module 40 to enter both the internal containment module 10 and the external containment module 20, resulting in a chemical reaction between the ozone, centrifuged mother liquor wastewater, and the catalytic module 30. The external containment module 20 is connected to the water filtration unit. The catalytic module 30 catalyzes the self-decomposition of ozone in water, increasing the OH- ions generated in the water. -The concentration is increased, thereby improving the ozone oxidation effect. Furthermore, the wastewater can be further reacted in the outer containment module 20. That is, the catalytic module 30 can contact the decomposed wastewater and further catalyze the self-decomposition of the wastewater in the outer containment module 20. This allows the final centrifugal mother liquor wastewater to meet the circulating water replenishment standard after being discharged from the outer containment module 20 and be sent back to the original polymerization reactor for reuse, thus achieving the purpose of high-level recycling of centrifugal mother liquor wastewater.

[0033] In one embodiment, the storage module 10 includes a first storage container 11 and a second storage container 12, which are divided and arranged side by side and independently. The centrifugal mother liquor wastewater enters from the upper part of the first storage container 11 and the second storage container 12. The catalysts 31 and 32 in the catalytic module 30 are divided into two parts and respectively disposed in the first storage container 11 and the second storage container 12. The catalysts 31 and 32 divided into two parts are respectively located in the middle region of their respective first storage container 11 and the second storage container 12, so that the lower and upper parts of the first storage container 11 and the second storage container 12 form independent spaces. The ozone module 40 extends into the independent space in the lower part. It should be noted that the first container 11 and the second container 12 are formed by vertically and evenly dividing the main space inside the container module 10 by partitions. The contact time between the two catalysts 31 and 32 and the wastewater is 10-30 minutes. Moreover, the contact between the wastewater and the ozone catalysts 31 and 32 in the ozone module 40 can catalyze the self-decomposition of ozone in the wastewater, increasing the OH- produced in the wastewater. - The concentration is increased, thereby improving the ozone oxidation effect. Moreover, the wastewater undergoes two reactions, one in the first container 11, the other in the second container 12, and the other in the outer container module 20. This ensures that the centrifugal mother liquor wastewater meets the circulating water replenishment standard after being discharged from the outer container module 20 and can be returned to the original polymerization reactor for reuse.

[0034] In one embodiment, the outer containment module 20 includes an outer containment container 22 and two outlet weirs 21. The two outlet weirs 21 are respectively disposed on both sides of the upper part of the outer containment container 22 for drainage. The two outlet weirs 21 are respectively connected to the water filtration unit. The inner containment module 10 is disposed inside the outer containment container 22. Further, the wastewater after the reaction is completed flows out from the two outlet weirs 21 into the water filtration unit. The volume of the reaction zone 23 of the outer containment container 22 (i.e., the reaction zone 23 formed by the water flowing out from the inner containment module 10 and further reacting inside the outer containment container 22) is 2.5 times the volume of the contact zone (the contact zone formed by the catalytic module 30 and the wastewater). During normal operation, the mother liquor wastewater is pumped into the inner containment module 10 by a water pump. The wastewater comes into countercurrent contact with the catalysts 31 and 32 installed in the inner container module 10 and the ozone coming out of the ozone module 40. After the wastewater comes out from the bottom of the inner container module 10 into the outer container 22, the reaction takes place in the outer container 22, and the water after the reaction flows out from the upper outlet weir 21.

[0035] In one embodiment, the ozone module 40 includes an ozone pipeline 43 and two aerators 41 and 42. The two aerators 41 and 42 are connected to the ozone pipeline 43 and are respectively disposed in the lower independent spaces within the first inner container 11 and the second inner container 12. Optionally, a control valve is also provided on the ozone pipeline 43 to control the amount of ozone. Specifically, the mother liquor wastewater is pumped into the inner container module 10. In the inner container module 10, the wastewater comes into countercurrent contact with the catalysts 31 and 32 and the ozone output from the ozone pipeline 43, which exits into the aerators 41 and 42. After contact, the wastewater exits from the bottom of the inner container module 10 into the outer container 22, where it reacts to obtain the desired water.

[0036] In one embodiment, the catalytic containment unit further includes a water inlet module 50, which is connected to the upper part of the inner containment module 10 to transport centrifuged mother liquor wastewater into the inner containment module 10. The water inlet module 50 is also connected to the bottom of the inner containment module 10 to clean the inner containment module. By using the water inlet module 50, there is no need to configure a backwash water pump, ensuring the cleanliness of the catalysts 31 and 32, reducing operating costs, saving cleaning water, and improving the system water recovery rate.

[0037] In one embodiment, the water inlet module 50 includes a water inlet pipe 51, pulse valves 54 and 55, a water inlet valve 56, and two water distributors 52 and 53. The two water distributors 52 and 53 are disposed at the lower part of the internal storage module 10. The pulse valves 54 and 55 are respectively disposed between the water inlet pipe 51 and the two water distributors 52 and 53 to control the connection or closure between the water inlet pipe 51 and the two water distributors 52 and 53. The water inlet pipe 51 is connected to the upper part of the internal storage module 10, and a water inlet valve 56 is provided on the water inlet pipe 51 to control the centrifugal mother liquor wastewater to enter the internal storage module 10. Optionally, every 20 minutes during operation, the inlet valve 56 on the inlet pipe 51 automatically switches valves (i.e., closes the inlet valve 56 and opens the pulse valves 54, 55, and 55) to stop the centrifugal mother liquor wastewater from entering the inner container module 10. The inlet pipe 51 is connected to two water distributors 52 and 53, allowing clean water to enter the inner container module 10 for pulse cleaning of the catalysts 31 and 32 and any remaining wastewater within them. The pulse duration is 30 seconds. During pulse cleaning, the clean water enters the catalyst module 30 from the water distributors 52 and 53 located at the bottom of the inner container module 10, backwashing the catalysts 31 and 32. The clean backwash water flows through the lower parts of the first inner container 11 and the second inner container 12 to the outer container 22 and exits from the outlet weir 21 on the outer container 22. Due to the short pulse cycle and frequent pulses, the water quality remains relatively clean and can be directly used as product water for subsequent processes.

[0038] In one embodiment, the water filtration unit includes a water filtration module 60 and a water quality standard module 70, which are connected. The external receiving module 20 is connected to the water filtration module 60. The water filtration module 60 is used to ensure the long-term stable operation of the pure water system, preventing it from being contaminated or oxidized, ensuring the quality of the effluent and the service life of the water filtration module 60, and also allows for cleaning to restore its filtration function.

[0039] In one embodiment, the water filtration module 60 includes a carbon filter tank 61 and a filtered water tank 62, which are connected. The filtered water tank 62 is connected to the water quality standard module 70. Specifically, to ensure the long-term stable operation of this pure water system, a carbon filter tank 61 is provided, containing high-efficiency activated carbon, which can effectively adsorb and remove organic matter from the raw water, reduce turbidity, colloids, and residual chlorine, protect the ion exchange resin from contamination and oxidation, ensure the quality of the effluent, and extend the service life of the resin. The filtered water tank 62 contains an activated carbon filter. A backwash pump is installed on the activated carbon filter, which draws water from the filtered water tank 62 to periodically clean the activated carbon filter and restore its filtration function.

[0040] In one embodiment, the water quality standard module 70 includes a cation exchange bed 71, a decarbonator 72, an intermediate water tank 73, an anion exchange bed 74, and a mixed bed 75 connected in sequence. The filtered water tank 62 is connected to the cation exchange bed 71. Specifically, water from the filtered water tank 62 is pumped into the cation exchange bed 71, which contains cation exchange resin. Most of the cations in the water are removed through the cation exchange bed 71. The effluent from the cation exchange bed 71 enters the decarbonator 72. When the bicarbonate ion content in the influent is greater than 50 mg / L, a carbon dioxide removal device (referred to as decarbonator 72) needs to be installed. This device mainly removes HCO3- from the water. 3- The carbon dioxide remover removes carbonate ions and free CO2 to reduce the burden on the anion exchange bed 74. The removal rate of the carbon dioxide is 95%-97%, and it does not require regeneration, significantly reducing water production costs. The effluent from the carbon dioxide remover 72 is collected in the intermediate water tank 73 and then pumped into the subsequent anion exchange bed 74. The anion exchange bed 74 contains both weak and strong base anion exchange resins, removing most of the anions in the water. The effluent from the anion exchange bed 74 enters the mixed bed 75, which contains both anion exchange resins and cation exchange resins to further remove anions and cations, meeting the effluent quality standards. The cation exchange bed 71, anion exchange bed 74, and mixed bed 75 are regenerated through a connected regeneration system after ion exchange to saturation. The regeneration system includes acid and alkali storage tanks, acid and alkali metering tanks, acid and alkali injectors, and acid mist absorbers. Simultaneously, to prevent resin loss during ion exchange, a resin trap is installed at the outlet of each resin exchanger.

[0041] In one embodiment, the system further includes a wastewater tank 76, a pure water tank 77, and a neutralization tank 78. The filtered water tank 62 is connected to the wastewater tank 76, the water quality standard module 70 is connected to the pure water tank 77, the cation exchange bed 71 is connected to both the wastewater tank 76 and the neutralization tank 78, and the anion exchange bed 74 is connected to both the wastewater tank 76 and the neutralization tank 78. The wastewater tank 76, pure water tank 77, and neutralization tank 78 can receive different water qualities, facilitating subsequent classification, collection, and utilization of different water types.

[0042] In summary, after treating the biochemically treated mother liquor wastewater that meets the circulating water makeup standard, the product water quality can achieve a conductivity ≤1μS / cm, COD ≤5mg / L, and a system recovery rate ≥95%. This allows it to be reused in the original polymerization reactor, achieving the goal of high-level reuse of centrifugal mother liquor wastewater. It also boasts advantages such as low investment and operating costs and no concentrated wastewater generation. Furthermore, the system has low investment and operating costs, high recovery rate, and high reuse value; the system generates no concentrated wastewater, requires no secondary treatment, and only produces a small amount of acidic or alkaline wastewater during resin regeneration.

Claims

1. A centrifugal mother liquor wastewater back to the kettle treatment system, characterized in that, The centrifugal mother liquor wastewater back processing system comprises: a catalytic containing unit and a water filtering processing unit connected, wherein the catalytic containing unit is used to reduce the chemical oxygen demand and chroma of the centrifugal mother liquor wastewater, and the water filtering processing unit is used to filter and classify the centrifugal mother liquor wastewater after processing; the catalytic containing unit comprises an ozone module, a catalytic module, an inner containing module and an outer containing module, the inner containing module is arranged in the outer containing module, the catalytic module is arranged in the inner containing module, the ozone module is communicated with the inner containing module and extends into the lower part of the inner containing module, so that the ozone released by the ozone module enters the inner containing module and the outer containing module, and a chemical reaction occurs among the ozone, the centrifugal mother liquor wastewater and the catalytic module, and the outer containing module is connected with the water filtering processing unit; the catalytic containing unit further comprises a water inlet module, the water inlet module is communicated with the upper part of the inner containing module to convey the centrifugal mother liquor wastewater into the inner containing module, and the water inlet module is communicated with the lower part of the inner containing module to clean the inner containing module; the inner containing module comprises a first inner containing device and a second inner containing device which are formed by being divided, and the first inner containing device and the second inner containing device are separated from each other by a partition plate; the catalyst in the catalytic module is divided into two parts and arranged in the first inner containing device and the second inner containing device respectively, wherein the catalyst divided into two parts corresponds to the middle region of the first inner containing device and the second inner containing device respectively, so that the lower part and the upper part of the first inner containing device and the second inner containing device form independent spaces; the ozone module extends into the independent space of the lower part; the ozone module comprises an ozone pipeline and two aerators, the ozone pipeline is connected with the two aerators, and the two aerators are arranged in the independent space of the lower part of the first inner containing device and the second inner containing device respectively; the water inlet module comprises a water inlet pipeline, a pulse valve, a water inlet valve and two water distributors, the two water distributors are arranged in the lower part of the inner containing module, the pulse valve is arranged between the water inlet pipeline and the two water distributors to control the communication or closing between the water inlet pipeline and the two water distributors, the water inlet pipeline is communicated with the upper part of the inner containing module, and the water inlet valve is arranged on the water inlet pipeline to control the centrifugal mother liquor wastewater to enter the inner containing module.

2. The centrifugal mother liquor wastewater back processing system according to claim 1, wherein the outer containing module comprises an outer containing device and two water outlet weirs arranged on the upper part of the outer containing device on both sides to drain water, the two water outlet weirs are connected with the water filtering processing unit respectively, and the inner containing module is arranged in the outer containing device.

3. The centrifugal mother liquor wastewater back processing system according to claim 1, wherein the water filtering processing unit comprises a water filtering module and a water quality standard module, the water filtering module and the water quality standard module are communicated, and the outer containing module is communicated with the water filtering module.

4. The centrifugal mother liquor wastewater back to kettle treatment system according to claim 3, characterized in that, The water filtering module comprises a carbon filter tank and a filtered water tank, the carbon filter tank and the filtered water tank are communicated, and the filtered water tank is connected with the water quality standard module.

5. The centrifugal mother liquor wastewater back to kettle treatment system according to claim 4, characterized in that, The water quality standard module comprises a positive bed, a carbon remover, an intermediate water tank, a negative bed and a mixed bed connected in sequence, and the filtered water tank is connected with the positive bed.

6. The centrifugal mother liquor wastewater back to kettle treatment system according to claim 5, characterized in that, It further comprises a wastewater tank, a pure water tank and a neutralization tank, the filtered water tank is connected with the wastewater tank, the water quality standard module is connected with the pure water tank, the positive bed is respectively connected with the wastewater tank and the neutralization tank, and the negative bed is respectively connected with the wastewater tank and the neutralization tank.

Images