CN216273563U - Acrylonitrile waste liquid treatment system - Google Patents
Acrylonitrile waste liquid treatment system Download PDFInfo
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Abstract
The utility model provides an acrylonitrile waste liquid treatment system, which comprises: the device comprises a high-boiling-point substance separation module, a low-boiling-point substance separation module, a high-boiling-point component treatment module, an advanced treatment module and a residual liquid treatment module; the system provided by the utility model adopts the high-boiling-point substance separation module and the low-boiling-point substance separation module, reduces the Chemical Oxygen Demand (COD) and the content of various pollutants in the evaporated condensate by controlling the evaporation temperature and the separation parameters, so that heavy component pollutants in the acrylonitrile waste liquid are left in the high-boiling-point component, thereby achieving the purpose of reducing the acrylonitrile waste liquid, and improves the combustibility of the high-boiling-point component, recycles the available resources and reduces the incineration cost through the high-boiling-point component treatment module and the residual liquid treatment module; the separated water components are further treated by an advanced treatment module, and the water resource is recycled.
Description
Technical Field
The utility model relates to the technical field of industrial water treatment, in particular to an acrylonitrile waste liquid treatment system.
Background
Acrylonitrile is an important chemical raw material and has wide application in the field of manufacturing chemical products such as ABS plastics, nitrile rubber, acrylamide, acrylic fibers, synthetic resin and the like.
The existing acrylonitrile production process adopts a classical propylene ammoxidation method (sohio method), propylene, ammonia gas and air are used as main raw materials, acrylonitrile is produced under certain reaction conditions and the action of a catalyst, and byproducts are mainly acetonitrile and hydrocyanic acid.
In the acrylonitrile production process, a high-concentration cyanogen-containing waste liquid can be generated, the water quality and the components are complex, the pollutant concentration is high, various organic matters and polymers are contained, and the biotoxicity is high. Through preliminary analysis, the waste water usually contains acrylonitrile, acetonitrile, hydrocyanic acid, acrolein, acetaldehyde, acrylamide, acetone cyanohydrin, methyl acrylate, sulfate, heavy components and a large amount of polymers, the COD content is more than 20 ten thousand mg/L, and simultaneously the content of nitrile compounds is an important characteristic of the waste water in acrylonitrile production, and the nitrile compounds have strong toxicity and inhibition effects on microorganisms and can cause great damage to a system when directly discharged into a biochemical treatment system; and the high total nitrogen content is another remarkable characteristic of the acrylonitrile wastewater and accounts for about 20 percent of all pollutants. The polymers in the acrylonitrile wastewater are mainly from low molecular polymers and copolymers of nitrile substances, and the polymers generally exist in a colloidal or dissolved form in water, are difficult to hydrolyze and be utilized by microorganisms, so that the polymers cannot be treated by the conventional treatment technology. Due to the high hazard and difficult treatment of acrylonitrile wastewater, the search for a proper treatment method becomes one of the recognized problems at home and abroad.
Data of main water quality
| Item | pH | CODcr | NH4+-N | CN- | SS |
| Unit of | Dimensionless | mg/L | mg/L | mg/L | mg/L |
| Numerical value | 6-8 | 2×105～3×105 | 3×104～4×104 | 2000～3000 | － |
SUMMERY OF THE UTILITY MODEL
The utility model aims to provide an acrylonitrile waste liquid treatment system to solve at least one of the problems in the prior art.
In order to achieve the purpose, the utility model adopts the following technical scheme:
an acrylonitrile waste liquid treatment system comprising:
the high-boiling-point substance separation module is used for separating the acrylonitrile waste liquid to be treated into a high-boiling-point component and a low-boiling-point component through a first set evaporation temperature;
a low boiling point component separation module for separating the low boiling point component by a second set evaporation temperature to form a water component and an organic component;
the high-boiling-point component processing module is used for separating the high-boiling-point component in a centrifugal mode to form a precipitate component and a non-precipitate component; wherein the precipitated fraction is disposed of in a landfill;
the advanced treatment module is used for carrying out advanced treatment on the water components to obtain standard water;
and the residual liquid treatment module is used for separating the non-precipitation components to obtain oil-phase components and non-oil-phase components, and the non-oil-phase components are discharged after being burnt.
In a preferred embodiment, the system further comprises a preprocessing module, wherein the preprocessing module comprises: buffer tank and filter, pending acrylonitrile waste liquid passes through the buffer tank entry gets into the buffer tank, the buffer tank export is connected with the filter import.
In a preferred embodiment, the high boiler separation module comprises:
the system comprises a first-effect separator, a second-effect separator, a first-effect evaporator, a second-effect evaporator, a first condensate tank, a second condensate tank and a first condenser; the acrylonitrile waste liquid to be treated enters the first-effect evaporator through a lower inlet of the first-effect evaporator, a top outlet of the first-effect evaporator is connected with a middle inlet of the first-effect separator, a bottom outlet of the first-effect separator is connected with a lower inlet of the first-effect evaporator, a top outlet of the first-effect separator is connected with a top inlet of the second-effect evaporator, a lower inlet of the second-effect evaporator is respectively connected with a lower outlet of the first-effect evaporator and a bottom outlet of the second-effect separator, a lower outlet of the second-effect evaporator is connected with an inlet of the first condensate tank, an outlet of the first condensate tank is respectively connected with an upper inlet of the first-effect separator and an upper inlet of the second-effect separator, a top outlet of the second-effect separator is connected with an inlet of the first condenser, an outlet of the first condenser is connected with an inlet of the second condensate tank, and an outlet of the second condensate tank is connected with an upper inlet of the second-effect separator.
In a preferred embodiment, the low boiler separation module comprises:
take off low knockout tower, reboiler, second condenser, low jar and the product water jar of boiling, low boiling point component export is connected with taking off low knockout tower upper portion entry, takes off low knockout tower upper portion export and is connected with second condenser top entry, and second condenser top is connected with low jar entry of boiling, takes off low knockout tower bottom export and is connected with the reboiler entry, and the reboiler export is connected with taking off low knockout tower lower part entry, takes off low knockout tower lower part export and is connected with the product water jar entry.
In a preferred embodiment, the depth processing module comprises: the device comprises an advanced treatment module inlet, an advanced treatment module first outlet and an advanced treatment module second outlet, wherein the advanced treatment module inlet is connected with the water component, and the advanced treatment module second outlet is connected with the high-boiling-point substance separation module inlet.
In a preferred embodiment, the device further comprises a thickener, wherein the thickener inlet is connected with the high-boiling-point component outlet.
In a preferred embodiment, the raffinate treatment module inlet is connected to the thickener outlet.
In a preferred embodiment, the high boiling point component treatment module is in communication with the thickener.
In a preferred embodiment, the device further comprises a vacuum device, and the inlets of the vacuum device are respectively connected with the high-boiling-point substance separation module and the low-boiling-point substance separation module.
In a preferred embodiment, the device further comprises an incineration device, and the inlet of the incineration device is respectively connected with the outlet of the residual liquid treatment module, the outlet of the vacuum device and the outlet of the organic component.
The utility model has the advantages of
The utility model provides an acrylonitrile waste liquid treatment system, which comprises: the high-boiling-point substance separation module is used for separating the acrylonitrile waste liquid to be treated into a high-boiling-point component and a low-boiling-point component through a first set evaporation temperature; a low boiling point component separation module for separating the low boiling point component by a second set evaporation temperature to form a water component and an organic component; the high-boiling-point component processing module is used for separating the high-boiling-point component in a centrifugal mode to form a precipitate component and a non-precipitate component; wherein the precipitated fraction is disposed of in a landfill; the advanced treatment module is used for carrying out advanced treatment on the water components to obtain standard water; a residual liquid treatment module for separating the non-precipitation components to obtain oil phase components and non-oil phase components, wherein the non-oil phase components are discharged after being burned; the system provided by the utility model adopts the high-boiling-point substance separation module and the low-boiling-point substance separation module, so that heavy component pollutants in the acrylonitrile waste liquid are left in the high-boiling-point component, and further the aim of reducing the acrylonitrile waste liquid is achieved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
Fig. 1 is an overall process block diagram provided by an embodiment of the present invention.
FIG. 2 is a schematic structural view of a high boiling substance separation system provided in an embodiment of the present invention.
FIG. 3 is a schematic structural view of a low boiling substance separation system provided in an embodiment of the present invention.
Fig. 4 is a flowchart of a processing apparatus according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.
The following disclosure provides many different embodiments, or examples, for implementing different features of the utility model. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to limit the utility model. In addition, technical solutions between the various embodiments can be combined with each other, but must be realized by a person skilled in the art, and when the technical solutions are contradictory or cannot be realized, the combination of the technical solutions should be considered to be absent and not be within the protection scope of the present invention.
In order to facilitate understanding of the technical solutions provided in the present application, the following briefly describes the research background of the technical solutions in the present application.
At present, the most widely used method for industrialization is an incineration method, and the method is easy to be applied in large scale due to more thorough treatment and is widely applied in China. Such as Jilin petrochemical, Shanghai petrochemical group company, Anqing petrochemical and Qilu petrochemical, etc. However, the waste water is directly incinerated, and the waste water has low heat value and contains a large amount of salt, so that the problems of high auxiliary fuel consumption and secondary pollution exist, and the treatment cost is high.
In addition to the incineration method, the pressure hydrolysis-biochemical method is also applied domestically. The pressure hydrolysis method is generally used for pretreating acrylonitrile production wastewater through high-temperature high-pressure reaction under an alkaline condition, has a good cyanide removal effect, but has low polymer removal efficiency, and pollutants such as COD (chemical oxygen demand) and ammonia nitrogen in effluent are not obviously reduced.
Other treatment methods include wet catalytic oxidation, ozone catalytic oxidation, biochemical method, activated carbon adsorption and the like, but the wastewater has complex components, high polymer and copolymer content and inorganic salt content, so that the actual treatment effect is not ideal, the requirements on reaction conditions, catalysts and equipment are high, and the industrial popularization and application effects are not ideal.
Chinese utility model patent CN102399044A provides an integrated processing method of acrylonitrile waste water, and acrylonitrile waste water at first gets into the equalizing basin and carries out the homogeneous mixing, then gets into the AO biochemical treatment pond and carry out biochemical treatment, goes out water and gets into the advanced treatment module after ultrafiltration treatment and carry out advanced treatment. Chinese utility model patent CN103304096A provides a method for treating acrylonitrile waste water by ozone catalysis coupling biological nitrification, the incoming water firstly enters into the equalizing basin and carries out the equilibrium of quality of water volume, flows through the pre-oxidation tower and the catalytic oxidation tower after again, and the ozone that remains in the aquatic is got rid of in the ozone desorption pond of flowing into certainly, carries out getting rid of ammonia nitrogen through nitrifying the pond, finally produces water from the clear water pond discharge.
The treatment process combining the biochemical method and the physicochemical method has an obvious promotion effect on the achievement of the standard discharge of the acrylonitrile wastewater, but the prior treatment process generally has the problems of insufficient recognition of the characteristics of the acrylonitrile wastewater, incomplete denitrification function of a biochemical system, lack of standard-reaching guarantee measures for effluent of the biochemical system and the like. Therefore, the research and development of the efficient and economic acrylonitrile wastewater treatment technology is one of the research hotspots in the field of environmental engineering at present.
Based on this, an embodiment of the present invention provides an acrylonitrile waste liquid treatment system, including:
the high-boiling-point substance separation module is used for separating the acrylonitrile waste liquid to be treated into a high-boiling-point component and a low-boiling-point component through a first set evaporation temperature;
specifically, the high boiling point component contains a water phase, an oil phase and solid salt, and the low boiling point component contains a large amount of water and a small amount of organic impurities; the high-boiling-point substance separation module adopts a two-effect or three-effect evaporation mode, and meanwhile, inorganic salt and oil substances are generated due to the fact that the materials are evaporated and concentrated, so that in order to prevent the materials from generating coking and scaling phenomena on a heat exchange surface of an evaporator, the materials in the evaporation device are carried out in a forced circulation mode.
A low boiling point component separation module for separating the low boiling point component by a second set evaporation temperature to form a water component and an organic component;
specifically, the organic components are discharged after being incinerated.
The high-boiling-point component processing module is used for separating the high-boiling-point component in a centrifugal mode to form a precipitate component and a non-precipitate component; wherein the precipitated fraction is disposed of in a landfill;
specifically, the precipitated component is mainly solid salt, and the non-precipitated component contains water and organic matter.
The advanced treatment module is used for carrying out advanced treatment on the water components to obtain standard water;
and the residual liquid treatment module is used for separating the non-precipitation components to obtain oil-phase components and non-oil-phase components, and the non-oil-phase components are discharged after being burnt.
In particular, the oil phase components can be recycled as fuel.
From the above examples, it can be known that the system provided by this embodiment adopts high-boiling-point substance separation module and low-boiling-point substance separation module, makes heavy component pollutant in acrylonitrile waste liquid stay in high boiling point component, and then reaches the purpose of minimizing acrylonitrile waste liquid, and experiments show that can make the volume of raffinate control between 25% -35%, then through high boiling point component processing module and raffinate processing module, improve high boiling point component combustibility, the recovery available resource, reduce the cost of burning, after the water component after the separation adopts advanced treatment module to further handle, realize the recycle of water resource, and then realized the thorough processing of propylene cyanide high concentration cyanogen-containing waste liquid.
It can be seen that the core concept of the present invention is: aiming at the characteristics and treatment requirements of acrylonitrile wastewater, the utility model provides an acrylonitrile wastewater treatment process, which comprises the steps of firstly carrying out separation pretreatment on the wastewater, controlling evaporation temperatures and separation parameters in different stages through a high-boiling-point substance separation module and a low-boiling-point substance system, reducing COD (chemical oxygen demand) and various pollutant contents in condensate after evaporation separation, and leaving main heavy component pollutants in waste liquid in evaporation residual liquid to achieve the purpose of reducing the waste liquid, wherein the residual liquid amount is controlled to be 25-35%, and the residual liquid treatment system is used for improving the combustibility of the residual liquid, recycling available resources and reducing the incineration cost; and the separated condensate enters a deep treatment system for treatment, the deep treatment system comprises an RO membrane device, a biochemical treatment device and an advanced oxidation device, wherein the advanced oxidation device comprises ozone catalytic oxidation, electrochemical oxidation, Fenton process and the like, and the deep oxidation system comprises independent use or any process combination of the devices, so that the requirements on water resource recycling and standard emission are finally met.
According to the condition of the acrylonitrile waste liquid, the waste liquid is firstly introduced into a buffer tank to adjust the water quality and the water quantity, and then the waste liquid passes through a self-cleaning filter to remove residual catalyst particles and other substances in the waste liquid, so that the influence of the residual catalyst particles on subsequent equipment is prevented; then carrying out separation pretreatment, wherein the separation pretreatment process comprises a high-boiling-point substance separation module and a low-boiling-point substance separation system, the high-boiling-point substance separation module consists of a multi-effect evaporation separation device, the multi-effect evaporation can be a two-effect to five-effect evaporation device, and the low-boiling-point substance separation system consists of a rectification separation device.
The waste liquid can pass through the high-boiling-point substance separation module, and the COD and various pollutant contents in the evaporation condensate are reduced by controlling the evaporation temperature and separation parameters of each effect, so that the main heavy component pollutants in the waste liquid are left in the evaporation residual liquid, the purpose of reducing the waste liquid is achieved, and the residual liquid amount is controlled to be 25-35%.
After the high-boiling-point substance is treated by the high-boiling-point substance separation module, the separated condensate contains less pollutants, wherein the condensate contains some low-boiling-point organic pollutants and ammonia nitrogen except water. And (3) sending the partial condensate into a low-boiling separation system, separating pollutants such as low-boiling-point light component organic matters, ammonia nitrogen and the like in the condensate through a rectification separation device, recovering partial substances, and sending noncondensable tail gas into a residual liquid incineration system for treatment.
The waste liquid can also pass through a low boiling point substance separation system firstly, a rectification separation device is utilized, a small amount of low boiling point organic pollutants and ammonia nitrogen and other pollutants contained in the waste liquid are separated from the waste liquid, low boiling point substances are recovered, noncondensable tail gas is sent into a residual liquid incineration system for treatment, then the residual waste liquid is sent into a high boiling point substance separation module for treatment, the COD (chemical oxygen demand) and various pollutant contents in evaporation condensate are reduced by controlling evaporation temperature and separation parameters of various effects, main heavy component pollutants in the waste liquid are left in the evaporation residual liquid, the purpose of reducing the waste liquid is achieved, and the quantity of the residual liquid is controlled to be 25-35%.
The residual evaporation raffinate after the treatment of the high-boiling-point substance separation module contains organic pollutants such as inorganic salt, high-concentration copolymer and the like, and enters a raffinate treatment system for treatment. The residual liquid treatment system comprises a crystallization separation device and a liquid phase separation device. The residual liquid is firstly separated into liquid phase and salt through a crystallization separation system and the like, the separated solid waste salt can be directly buried or purified and recovered through modes such as pyrolysis and the like, separated oil phase substances exist in the separated liquid phase, an oil product can be recovered as fuel oil or a product through the liquid phase separation system, and the residual bottom waste liquid is sent to an incineration system for treatment. The residual liquid amount is reduced to 18-20% of the original waste liquid amount, and after concentration, the organic matter content of the residual liquid is high, the combustibility is improved, so the fuel cost required by incineration is greatly reduced.
The final condensate obtained by the previous separation still contains a small amount of organic matters and other pollutants, the COD is lower than 2000mg/L, and the final condensate is sent into an advanced treatment system for treatment due to better overall water quality. The advanced treatment system comprises an RO membrane device, a biochemical treatment device and an advanced oxidation device, wherein the advanced oxidation device comprises an ozone catalytic oxidation, an electrochemical oxidation, a Fenton process and the like, and the advanced treatment system comprises the devices which are used independently or combined in any process matching mode, so that the requirements of water resource recycling and standard emission are finally met.
Through the combined process, the acrylonitrile cyanide-containing waste liquid can be effectively treated, the waste liquid is reduced through the pretreatment process, the incineration treatment capacity is reduced, the combustion performance of the residual liquid is improved, the treatment cost of an incineration working section is reduced, and the separation condensate is treated through an advanced method, so that the water resource is recycled, and the purpose of standard emission is met.
Through the process, the acrylonitrile cyanide-containing waste liquid can be effectively treated, the reduction of the waste liquid is realized, the incineration treatment capacity is reduced, the residual liquid combustion performance is improved, the treatment cost of an incineration workshop section is reduced, and the cyclic utilization of water resources and the standard emission requirement are realized through advanced treatment.
In some embodiments, the method for treating acrylonitrile waste liquid further comprises pretreating the acrylonitrile waste liquid to be treated by a pretreatment module, wherein the pretreatment module comprises: buffer tank and filter, pending acrylonitrile waste liquid passes through the buffer tank entry gets into the buffer tank, the buffer tank export is connected with the filter import.
Specifically, cyanide-containing waste liquid generated in the acrylonitrile production process is firstly introduced into a buffer tank to adjust the water quality and the water quantity, and then passes through a self-cleaning filter to remove residual catalyst particles and other substances in the waste liquid, so that the influence of the waste liquid on subsequent equipment is prevented.
The method for separating the high-boiling-point substances mainly comprises a multi-effect evaporation device, wherein the multi-effect evaporator is usually composed of two-effect to five-effect evaporation devices, and a separation device is connected behind each effect evaporator to improve the separation effect of the high-boiling-point organic substances; meanwhile, as the materials are concentrated by evaporation, inorganic salt and oil substances are generated, and in order to prevent the materials from coking and scaling on the heat exchange surface of the evaporator, the bottom of the evaporation device is provided with a circulating pump, and the uniform flowing state of the materials in the method is ensured by a forced circulation ensuring mode.
The method for separating a high boiling substance will be described by taking a two-effect evaporator as an example. As shown in fig. 2, the high boiler separation module includes: the system comprises a first-effect separator, a second-effect separator, a first-effect evaporator, a second-effect evaporator, a first condensate tank, a second condensate tank and a first condenser; the acrylonitrile waste liquid to be treated enters the first-effect evaporator through a lower inlet of the first-effect evaporator, a top outlet of the first-effect evaporator is connected with a middle inlet of the first-effect separator, a bottom outlet of the first-effect separator is connected with a lower inlet of the first-effect evaporator, a top outlet of the first-effect separator is connected with a top inlet of the second-effect evaporator, a lower inlet of the second-effect evaporator is respectively connected with a lower outlet of the first-effect evaporator and a bottom outlet of the second-effect separator, a lower outlet of the second-effect evaporator is connected with an inlet of the first condensate tank, an outlet of the first condensate tank is respectively connected with an upper inlet of the first-effect separator and an upper inlet of the second-effect separator, a top outlet of the second-effect separator is connected with an inlet of the first condenser, an outlet of the first condenser is connected with an inlet of the second condensate tank, and an outlet of the second condensate tank is connected with an upper inlet of the second-effect separator.
In a specific scene, waste liquid firstly enters a first-effect evaporator (a first-effect evaporator), heat exchange is carried out between the waste liquid and raw steam in a heat exchanger (the first-effect evaporator), the waste liquid flows out from the top of the heat exchanger (the first-effect evaporator) after the temperature is raised, and enters a separator (the first-effect separator) through a lower position in the middle of the first-effect separator (the first-effect separator), the first-effect separator (the first-effect separator) is divided into an upper part and a lower part, the lower part is in a hollow tower form, after the waste liquid enters, the liquid flows downwards, and after being pressurized by a bottom circulating pump, the waste liquid returns to the evaporation heat exchanger (the second-effect evaporator) for reheating; the steam is evaporated from the liquid surface in the first-effect separator (the first-effect separator), wherein the steam contains water and various organic pollutants, in order to reduce the content of organic matters in an evaporation condensate (low boiling point component), the upper part of the separator (the first-effect separator and the second-effect separator) adopts a packing type rectifying tower structure, the packing adopts a metal corrugated packing, also can adopt various forms such as a wire mesh or a plate type and the like, in order to prevent organic polymers and precipitated salt in materials from blocking the packing of the separator (the first-effect separator and the second-effect separator), and the packing is positioned above the liquid surface in the separator (the first-effect separator and the second-effect separator); the waste liquid which is not evaporated in the first effect enters a second-effect evaporator (second-effect evaporator), the primary steam generated in the first effect enters the second-effect evaporator (second-effect evaporator) through a first-effect separator (first-effect separator), the second-effect waste liquid is heated and evaporated, and the primary steam is stored in a primary condensate tank (first condensate tank) after being condensed; the structure of the second-effect evaporator (second-effect evaporator) is the same as that of the first-effect evaporator (first-effect evaporator), waste liquid which is not evaporated by the second-effect evaporator finally enters a subsequent residual liquid treatment method (a high-boiling-point component treatment device and an oil phase separation device) for separation treatment, and secondary steam obtained by the second-effect evaporation is cooled by a condenser and then is stored in a secondary condensation water tank (a second condensation liquid tank).
In a preferred embodiment, in order to reduce the content of organic matters in the evaporated condensate, the upper part of the separator adopts a packing type rectifying tower structure, and the packing adopts a metal corrugated packing, and can also adopt various forms such as a wire mesh or a plate type and the like. In order to prevent organic polymers and precipitated salts in the material from blocking the filler of the separator, the filler is positioned above the liquid surface in the separator.
Furthermore, micro-nano scale depressions and protrusions are formed on the surface of the metal corrugated packing, specifically, the depressions and protrusions can be formed through laser scanning, and the depressions and protrusions with the micro-nano scale form a super-hydrophobic surface, so that mixing is enhanced and the metal corrugated packing is easy to clean.
In a further preferred embodiment, the packing may be arranged in multiple layers, for example, a first layer is a metal corrugated packing, a second layer is a polytetrafluoroethylene packing, and a third layer is a metal corrugated packing, wherein the polytetrafluoroethylene packing forms a plurality of cells, and the cells are provided with ball particles, so that in use, organic polymers and precipitated salts in the material can be further prevented from blocking the separator packing.
In some embodiments, as shown in fig. 3, the low boiler separation module comprises: take off low knockout tower, reboiler, second condenser, low jar and the product water jar of boiling, low boiling point component export is connected with taking off low knockout tower upper portion entry, takes off low knockout tower upper portion export and is connected with second condenser top entry, and second condenser top is connected with low jar entry of boiling, takes off low knockout tower bottom export and is connected with the reboiler entry, and the reboiler export is connected with taking off low knockout tower lower part entry, takes off low knockout tower lower part export and is connected with the product water jar entry.
Specifically, the wastewater can be directly treated by a low-boiling-point substance separation method, or the wastewater can be treated by a condensate after being placed in a high-boiling-point substance separation method. Therefore, the feeding of the low-boiling method can be directly fed in the method material, and can also be condensate and secondary steam after high-boiling separation, and the secondary steam can be fed in from the middle part of the low-boiling substance separation tower. The first-effect condensate and the second-effect condensate are respectively collected in a condensate tank, although the condensate (low-boiling point component) is separated by a front-end separator (a first-effect separator and a second-effect separator), a small amount of low-boiling point organic matter and ammonia nitrogen are still contained in the condensate, so that in order to further reduce the organic matter and the ammonia nitrogen in the condensate (low-boiling point component), the condensate (low-boiling point component) in the condensate tanks (a first condensate tank and a second condensate tank) is pressurized by a pump and then enters a low-boiling tower (a low-boiling separation tower) from the upper part, the low-boiling tower (the low-boiling separation tower) adopts a packed tower structure, metal corrugated packing is filled in the low-boiling tower (the low-boiling separation tower) or various forms such as a wire mesh or a plate type, a reboiler is arranged at the bottom of the low-boiling tower (the low-boiling separation tower) and can adopt various forms such as a thermal siphon type, a built-in type, a forced circulation type and the like, the condensate (the low-boiling separation tower) passes through the packed material from top to the bottom of the separation tower, and the heat required by gas-liquid phase separation in the tower is provided by a reboiler at the bottom, the separated steam (organic components) enters a cold hydrazine (a second condenser) for cooling and recovery, the obtained low-boiling condensate is stored in a low-boiling tank, and the separated water is stored in a water production tank.
The high boiling separation method is characterized in that the residual liquid phase after final effect evaporation enters a residual liquid treatment method for treatment, and the residual liquid method comprises a thickener, a centrifugal desalting device, an oil-water separation device and an incineration device.
The vacuum state in the multi-effect evaporator and the low-boiling tower is provided by a vacuum pump, the vacuum pump can adopt a liquid ring vacuum pump or a Roots type vacuum pump, and the inlets of the vacuum pump are respectively a shell pass of a heat exchanger of the double-effect evaporator, a condenser and a shell pass of the cold trap. The gas discharged by the vacuum pump contains organic matters with certain concentration and ammonia nitrogen non-condensable gas, and is sent into a residual liquid treatment method incineration device for treatment.
After the treatment by the separation method, the wastewater enters an advanced treatment method and is treated by single or combined processes such as biochemical, advanced oxidation, membrane filtration and the like, and the effluent can be recycled or discharged after reaching the standard.
In some embodiments, the depth processing module comprises: an A/O biochemical system, an ozone (catalytic) oxidation system, an electrochemical oxidation system, a Fenton oxidation system, a double-membrane system and the like.
Specifically, the condensate (low boiling point component) is separated by a low boiling tower (low boiling point removal separation tower), and the liquid phase (water component) obtained at the bottom enters an intermediate water production tank, wherein a small amount of organic pollutants are firstly treated by a biochemical system, and then treated by an advanced oxidation system, an ultrafiltration membrane system and an RO membrane system, so that the standard discharge or the recycling is realized.
In some embodiments, the acrylonitrile waste stream treatment process further comprises a thickener having an inlet connected to the high boiling point component outlet.
Further, the high boiling point component processing device is communicated with the thickener.
Further, the inlet of the oil phase separation device is connected with the outlet of the thickener.
Further, an outlet of the oil phase separation device, an outlet of the vacuum device and an outlet of the organic component are respectively connected with an inlet of the incineration device.
Specifically, the residual liquid after evaporation contains a water phase, an oil phase and solid salt, the residual liquid is discharged from a two-effect evaporation system and enters a thickener to realize solid-liquid separation, the obtained salt contains part of organic pollutants, the salt is directly buried, and the liquid obtained by centrifugation returns to the thickener. And overflowing the upper liquid phase of the thickener to a liquid phase separation method, separating the oil phase and the water phase, recovering the oil phase as fuel oil, and burning the liquid phase in a burning device.
It can be understood that the vacuum state in the above multi-effect evaporator (first effect evaporator and second effect evaporator) and low boiling tower (low boiling separation tower) is provided by vacuum pump, the vacuum pump can adopt liquid ring vacuum pump or roots type vacuum pump, the vacuum pump inlet is respectively the shell pass of heat exchanger of second effect evaporator (second effect evaporator), condenser (first condenser) and cold hydrazine (second condenser), the gas discharged by vacuum pump contains organic matter with certain concentration and ammonia nitrogen noncondensable gas, and is sent into the burning device for burning treatment.
The method for treating acrylonitrile waste liquid provided by the utility model is explained by combining specific examples.
The cyanide-containing waste liquid discharged in the production process of a certain acrylonitrile plant comprises 200000-270000mg/L COD, 30000-40000mg/L ammonia nitrogen, 2000-3000mg/L cyanide and 7-13% salt. The waste liquid is red brown, wherein the COD and the ammonia nitrogen are high in content, a large amount of inorganic salt and a plurality of organic matters and polymers are contained, the water quality components are complex, the pollutant concentration is high, and the biotoxicity is high. At present, the direct incineration process is adopted for treatment.
By adopting the process route of the utility model, a pilot-scale treatment experiment is carried out on the waste liquid, so that the effective treatment of the waste liquid is finally realized, the incineration treatment capacity is reduced, the combustion performance of the residual liquid is improved, the treatment cost of an incineration section is reduced, and the separated condensate is treated by an RO method, thereby achieving the recycling of water resources.
The pilot plant experiment treatment scale is 1t/h, the residual liquid amount is controlled to be 25% -30%, the condensate amount is controlled to be 70% -85%, the mixture enters an RO membrane method for treatment, the RO method recovery rate is 75%, and concentrated water returns to a front-end multi-effect evaporation method for treatment. After the residual liquid is subjected to solid-liquid separation, the content of the obtained solid salt is about 10 percent, and the rest is used as a mixed liquid phase for incineration treatment.
After the waste liquid is treated, the whole waste water recovery rate is more than or equal to 70 percent, the solid salt is 10 percent, and the incineration residue amount is 20 percent of the original waste liquid amount, thereby achieving the purposes of incineration reduction and water resource recovery.
The main pollutant indexes of each main process section are as follows:
it can be seen that, because the cyanide-containing waste liquid contains a plurality of reaction byproducts, in the conventional multi-effect evaporation process, because the evaporation temperature is higher and no separation method is adopted, the contents of organic matters and other pollutants in the recovered condensate are higher, for example, acetone cyanohydrin is easily decomposed and converted into acetone and HCN with low boiling points under the heated condition and enters the condensate along with the evaporation process. By adopting the traditional multi-effect evaporation treatment process, the content of main pollutants such as COD, ammonia nitrogen, cyanide and the like in the recovered condensate is higher, wherein the COD is more than 15000mg/L, the ammonia nitrogen is more than 3500mg/L, the cyanide content is more than 1200mg/L, and the subsequent treatment difficulty is higher.
The process route provided by the utility model can meet the treatment requirement on the acrylonitrile high-concentration cyanide-containing waste liquid, (1) incineration reduction: the main heavy component pollutants in the waste liquid are left in the evaporation residual liquid through an evaporation separation method to achieve the purpose of reducing the waste liquid, the residual liquid amount is controlled to be 25-35%, the combustibility of the residual liquid is improved through a residual liquid treatment method, the available resources are recycled, and the incineration cost is reduced; (2) and (3) water resource recovery: the content of pollutants in the evaporation condensate is reduced through the design of an evaporation separation method and the optimization of parameters, the quality of the effluent is further improved after the treatment by an advanced method, the recycling of water resources is achieved, and the recovery rate is over 70 percent; (3) resource recovery: by separating the residual liquid, the recovery of available resources can be realized.
In the description of the present specification, reference to the description of the terms "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the embodiments of the present specification. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example.
Furthermore, the various embodiments or examples and features of the various embodiments or examples described in this specification can be combined and combined by those skilled in the art without contradiction. The above description is only an embodiment of the present disclosure, and is not intended to limit the present disclosure. Various modifications and changes may occur to those skilled in the art to which the embodiments of the present disclosure pertain. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the embodiments of the present specification should be included in the scope of the claims of the embodiments of the present specification.
Claims (10)
1. An acrylonitrile waste liquid treatment system, characterized by comprising:
the high-boiling-point substance separation module is used for separating the acrylonitrile waste liquid to be treated into a high-boiling-point component and a low-boiling-point component through a first set evaporation temperature;
a low boiling point component separation module for separating the low boiling point component by a second set evaporation temperature to form a water component and an organic component;
the high-boiling-point component processing module is used for separating the high-boiling-point component in a centrifugal mode to form a precipitate component and a non-precipitate component; wherein the precipitated fraction is disposed of in a landfill;
the advanced treatment module is used for carrying out advanced treatment on the water components to obtain standard water;
and the residual liquid treatment module is used for separating the non-precipitation components to obtain oil-phase components and non-oil-phase components, and the non-oil-phase components are discharged after being burnt.
2. The system of claim 1, further comprising a pre-processing module, the pre-processing module comprising: buffer tank and filter, pending acrylonitrile waste liquid passes through the buffer tank entry gets into the buffer tank, the buffer tank export is connected with the filter import.
3. The system according to claim 1, wherein the high boiler separation module comprises:
the system comprises a first-effect separator, a second-effect separator, a first-effect evaporator, a second-effect evaporator, a first condensate tank, a second condensate tank and a first condenser; the acrylonitrile waste liquid to be treated enters the first-effect evaporator through a lower inlet of the first-effect evaporator, a top outlet of the first-effect evaporator is connected with a middle inlet of the first-effect separator, a bottom outlet of the first-effect separator is connected with a lower inlet of the first-effect evaporator, a top outlet of the first-effect separator is connected with a top inlet of the second-effect evaporator, a lower inlet of the second-effect evaporator is respectively connected with a lower outlet of the first-effect evaporator and a bottom outlet of the second-effect separator, a lower outlet of the second-effect evaporator is connected with an inlet of the first condensate tank, an outlet of the first condensate tank is respectively connected with an upper inlet of the first-effect separator and an upper inlet of the second-effect separator, a top outlet of the second-effect separator is connected with an inlet of the first condenser, an outlet of the first condenser is connected with an inlet of the second condensate tank, and an outlet of the second condensate tank is connected with an upper inlet of the second-effect separator.
4. The system according to claim 1, characterized in that the low boiler separation module comprises:
take off low knockout tower, reboiler, second condenser, low jar and the product water jar of boiling, low boiling point component export is connected with taking off low knockout tower upper portion entry, takes off low knockout tower upper portion export and is connected with second condenser top entry, and second condenser top is connected with low jar entry of boiling, takes off low knockout tower bottom export and is connected with the reboiler entry, and the reboiler export is connected with taking off low knockout tower lower part entry, takes off low knockout tower lower part export and is connected with the product water jar entry.
5. The system of claim 1, wherein the depth processing module comprises: biochemical systems, advanced oxidation systems, membrane treatment systems, the various systems of which are combined individually or in combination.
6. The system of claim 1, further comprising a thickener having an inlet coupled to the high boiling point component outlet and the raffinate treatment module inlet coupled to the thickener outlet.
7. The system of claim 4, wherein the low-boiling-point-removal separation column comprises a plurality of layers of packing.
8. The system of claim 6, wherein the high boiling point component treatment module is in communication with a thickener.
9. The system according to claim 1, further comprising a vacuum device, wherein the vacuum device inlet is connected with the high boiler separation module and the low boiler separation module, respectively.
10. The system of claim 9, further comprising an incineration device, wherein the incineration device inlet is connected to the raffinate treatment module outlet, the vacuum device outlet, and the organic component outlet, respectively.
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| CN202121504853.0U CN216273563U (en) | 2021-07-02 | 2021-07-02 | Acrylonitrile waste liquid treatment system |
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