Treatment system for calcium chloride raffinate generated in vinylidene chloride production process

Abstract

The utility model discloses a system for treating calcium chloride raffinate generated in the production process of vinylidene chloride, which comprises a collecting and adjusting tank, an inlet end of which is used for introducing and collecting the raffinate after saponification reaction is finished; the inlet end of the neutralizing tank is connected with the outlet end of the collecting and adjusting tank; the inlet end of the coagulation tank is connected with the outlet end of the neutralizing tank; the inlet end of the post-coagulation wastewater temporary storage tank is connected with the liquid outlet of the coagulation tank; the inlet end of the sand filter is connected with the outlet end of the coagulated wastewater temporary storage tank, and the inlet end of the activated carbon filter is connected with the outlet end of the sand filter; the inlet end of the ultrafiltration device is connected with the outlet end of the activated carbon filter, and the outlet end of the ultrafiltration device is connected with the ultrafiltration wastewater temporary storage tank; the inlet end of the reverse osmosis device is connected with the outlet end of the ultra-filtered wastewater temporary storage tank; and the evaporating crystallizer is connected with a concentrated solution outlet of the reverse osmosis device and is used for evaporating and crystallizing.

Description

Technical Field

[0001] The utility model relates to the technical field of calcium chloride residual liquid processing equipment, in particular to a calcium chloride residual liquid processing system generated in the production process of vinylidene chloride. Background Art

[0002] During the vinylidene chloride production process, 1,1,2-trichloroethane (TCE) and prepared limewater are introduced into a saponification reactor in a specific ratio to produce vinylidene chloride. The vinylidene chloride vapor enters a crude distillation column for distillation. After partial condensation in the crude column condenser, the condensate is pumped back to the crude distillation column via a crude column reflux pump as overhead reflux. The remaining vapor is condensed in the crude column condenser and then passed through a crude distillation water separator to separate the residual liquid. The crude vinylidene chloride enters the crude distillation tank and is pumped by the crude distillation pump to the high-boiling column in the rectification process for further rectification. The overhead product is condensed in the overhead condenser, with a portion of the condensate returning to the column, while the remainder enters the refined distillation storage tank as the product. The crude distillation residue from the saponification reactor overflows into the saponification secondary reactor to recover the remaining vinylidene chloride. The remaining saponification residue is collected in a residual liquid buffer tank.

[0003] Every ton of vinylidene chloride produced produces approximately 4 tons of reaction residue. The main components of this residue are calcium chloride, excess calcium hydroxide, incompletely reacted TCE, vinylidene chloride that was not completely separated after distillation, and polychlorinated alkanes and chlorinated hydrocarbons introduced as side reactions with the TCE reactant. The concentrations of suspended solids and calcium chloride in the residue are high at 7,000-8,000 mg / L and 100,000-200,000 mg / L, respectively, indicating poor biodegradability.

[0004] Currently, vinylidene chloride production companies have several methods for treating calcium chloride residue: (1) mixing it with other residual liquids from the production system, diluting it to meet the standards, and then discharging it on the surface; (2) pre-treating the calcium chloride residue and then using evaporation and crystallization to obtain CaCl2·2H2O or anhydrous CaCl2. With the increasing emphasis on environmental protection, the first treatment method will pollute the environment and is completely unsuitable for inland production companies. The second evaporation salt production method has problems such as high treatment costs, difficulty in stable and continuous operation of evaporation and crystallization, and high salt impurity content.

[0005] Therefore, a system for treating the calcium chloride residue produced in the vinylidene chloride production process is needed. Utility Model Content

[0006] In view of the above technical problems, the utility model provides a system for treating calcium chloride residual liquid generated in the production process of vinylidene chloride.

[0007] In order to achieve the above-mentioned purpose, the technical solution of the present utility model is as follows:

[0008] A system for treating calcium chloride residual liquid generated in the production process of vinylidene chloride, comprising:

[0009] The collecting and regulating tank is used to collect the residual liquid after the saponification reaction is completed;

[0010] A neutralization tank, the inlet of which is connected to the outlet of the collection and adjustment tank;

[0011] The inlet of the coagulation tank is connected to the outlet of the neutralization tank;

[0012] The inlet of the temporary storage tank for wastewater after coagulation is connected to the outlet of the coagulation tank;

[0013] A sand filter and an activated carbon filter, wherein the inlet end of the sand filter is connected to the outlet end of the temporary storage tank for wastewater after coagulation, and the inlet end of the activated carbon filter is connected to the outlet end of the sand filter;

[0014] The inlet end of the ultrafiltration device is connected to the outlet end of the activated carbon filter, and the outlet end is connected to the temporary storage tank for wastewater after ultrafiltration;

[0015] The inlet of the reverse osmosis device is connected to the outlet of the temporary storage tank for wastewater after ultrafiltration;

[0016] The evaporation crystallizer is connected to the concentrated liquid outlet of the reverse osmosis device to perform evaporation crystallization.

[0017] The coagulation tank also includes a plate and frame filter press. The bottom drain port of the coagulation tank is connected to the plate and frame filter press through a delivery pump, and the filtrate discharge port of the plate and frame filter press is connected to the inlet end of the collection and adjustment tank.

[0018] The utility model also comprises a sodium sulfate preparation tank, the top water outlet of which is connected with the condensate discharge outlet of the evaporation crystallizer through a pipeline.

[0019] A stirring device is provided in the collecting and regulating tank and the neutralizing tank.

[0020] The refined brine outlet end of the reverse osmosis device is connected to a water production tank, and the water outlet end of the water production tank is connected to a chlor-alkali salt pool.

[0021] The refined brine outlet end of the reverse osmosis device is also connected to a backwash water tank, and the outlet end of the backwash water tank is respectively connected to the backwash water outlets of the sand filter, the activated carbon filter, the ultrafiltration device and the reverse osmosis device. The backwash water outlets of the sand filter, the activated carbon filter, the ultrafiltration device and the reverse osmosis device are connected to the neutralization tank through pipes.

[0022] The wastewater outlet of the reverse osmosis device is connected to the temporary storage tank for wastewater after ultrafiltration.

[0023] The beneficial effects of the present invention are as follows: by providing a regulating tank, a neutralization tank, and a coagulation tank, the present invention converts calcium chloride in the residual liquid into sodium chloride, reducing the concentrations of calcium chloride and suspended solids to 90 mg / L and 120 mg / L, respectively. After COD is removed from the residual liquid using a sand filter, an activated carbon filter, an ultrafiltration device, and a reverse osmosis device, the calcium chloride concentration in the dilute solution is reduced to 30 mg / L, and the COD is reduced from an initial 300 mg / L to 36 mg / L, fully meeting the brine specifications of the chlor-alkali system. The concentrated liquid enters the evaporation crystallizer and is then processed outsourced for miscellaneous salts. The present invention achieves zero residual liquid discharge, eliminating the environmental impact of residual liquid discharge from the system, and has the advantages of low operating costs, stable and reliable treatment effects, and environmental protection and energy conservation. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0025] Figure 1 It is a principle diagram of the present utility model. DETAILED DESCRIPTION

[0026] To make the objectives, technical solutions, and advantages of the present invention more clearly understood, the present invention is further described below in conjunction with specific embodiments and with reference to the accompanying drawings. It should be understood that these descriptions are merely illustrative and are not intended to limit the scope of the present invention. Furthermore, descriptions of known structures and technologies are omitted in the following description to avoid unnecessary confusion regarding the concepts of the present invention.

[0027] like Figure 1As shown, a calcium chloride residual liquid treatment system generated in the production process of vinylidene chloride, comprising: a collecting and regulating tank 1, the inlet of which is fed into and collected from the residual liquid after the saponification reaction is completed; a neutralization tank 2, the inlet of which is connected to the outlet of the collecting and regulating tank 1; a coagulation tank 3, the inlet of which is connected to the outlet of the neutralization tank 2; a temporary storage tank 4 for wastewater after coagulation, the inlet of which is connected to the liquid outlet of the coagulation tank 3; a sand filter 51 and an activated carbon filter 52, the inlet of the sand filter 51 being connected to the outlet of the temporary storage tank 4 for wastewater after coagulation, and the inlet of the activated carbon filter 52 being connected to the outlet of the sand filter 51; an ultrafiltration device 6, the inlet of which is connected to the outlet of the activated carbon filter 52, and the outlet of which is connected to the temporary storage tank 61 for wastewater after ultrafiltration; a reverse osmosis device 7, the inlet of which is connected to the outlet of the temporary storage tank 61 for wastewater after ultrafiltration; an evaporation crystallizer 8, connected to the concentrated liquid outlet of the reverse osmosis device 7 for evaporation and crystallization, and the coagulation tank 3 also includes a plate and frame filter press 31 The bottom drain port of the coagulation tank 3 is connected to the plate and frame filter press 31 through a delivery pump, and the filtrate discharge port of the plate and frame filter press 31 is connected to the inlet end of the collecting and regulating tank 1. The utility model also includes a sodium sulfate preparation tank 9, the top water outlet of which is connected to the condensate discharge port of the evaporation crystallizer 8 through a pipeline, and a stirring device is provided in the collecting and regulating tank 1 and the neutralization tank 2. The refined brine outlet end of the reverse osmosis device 7 is connected to the water production tank 71, and the water outlet end of the water production tank 71 is connected to the chlor-alkali salt pool. The refined brine outlet end of the reverse osmosis device 7 is also connected to a backwash water tank 10, and the outlet end of the backwash water tank 10 is respectively connected to the backwash water outlet of the sand filter 51, the activated carbon filter 52, the ultrafiltration device 6 and the reverse osmosis device 7. The backwash water drain outlets of the sand filter 51, the activated carbon filter 52, the ultrafiltration device 6 and the reverse osmosis device 7 are connected to the neutralization tank 2 through a pipeline, and the wastewater outlet of the reverse osmosis device 7 is connected to the temporary storage tank 61 for wastewater after ultrafiltration.

[0028] When the utility model is in use, the collecting and regulating tank 1 collects the residual liquid after the saponification reaction is completed, and adds a certain amount of hydrochloric acid to convert the excess calcium hydroxide therein into calcium chloride; the neutralization tank 2 is connected to the water outlet of the regulating tank, and adds 40% sodium sulfate solution to the residual calcium chloride liquid, and uses the sodium salt replacement method to convert the calcium ions in the residual liquid into dihydrated calcium sulfate; the coagulation tank 3 is connected to the water outlet of the neutralization tank, and adds 0.1% polyacrylamide (PAM) and 0.015% polyferric sulfate (PFS) mixed flocculant, and the deposited dihydrated calcium sulfate enters the plate and frame filter press 31 through the delivery pump for filtration, and the filtrate returns to the collecting and regulating tank 1, and the filter cake is dried and transported out, which can be used as a raw material for cement or hemihydrated calcium sulfate; the sand filter 51 and the activated carbon filter Filter 52 is where the waste liquid in the wastewater storage tank 4 after coagulation is pumped to. It undergoes secondary filtration to remove suspended matter and COD from the residual liquid. Ultrafiltration device 6 is connected to the outlet of activated carbon filter 52 and filters the decontaminated brine to further reduce the content of particulate matter and macromolecular organic matter in the system. The filtered dilute solution enters the ultrafiltration wastewater storage tank 61. Reverse osmosis device 7 receives the waste liquid in the ultrafiltration wastewater storage tank 61, reduces the COD content in the wastewater, and produces refined brine, which enters water production tank 71 and is pumped to the chlor-alkali system salt pool. Evaporation crystallizer 8 is connected to the concentrated liquid outlet of reverse osmosis device 7 and further evaporates and crystallizes it. The condensate is used to prepare the additives for the neutralization tank. The impurity salts obtained after the mother liquor is evaporated and crystallized are outsourced for processing.

[0029] Among them, the collecting and regulating tank 1 and the neutralization tank 2 are provided with stirring devices to accelerate the occurrence of the neutralization reaction through rapid stirring.

[0030] The top of the neutralization tank 2 is connected to the sodium sulfate preparation tank 9. The sodium sulfate solution enters the neutralization tank 2 through a pipeline and reacts with the calcium chloride residual liquid to form calcium sulfate dihydrate.

[0031] The solvent required for the sodium sulfate preparation tank 9 is provided by the condensed water of the evaporation crystallizer device 8, and sodium sulfate solution is added according to the content of calcium chloride in the neutralization tank 2 at the ratio of n (SO42-): n (Ca2+) = 1:1.

[0032] The mixed flocculant PAM+PAC is added to the coagulation tank 3 to make the calcium sulfate dihydrate settle quickly. The upper clear liquid overflows to the temporary storage tank 4 for wastewater after coagulation, and the calcium sulfate dihydrate settled in the lower layer is discharged through the sedimentation outlet.

[0033] After the ultrafiltration device 6 is completed, a temporary storage tank 61 for wastewater is set up after ultrafiltration, and after the reverse osmosis device 7 is completed, a water production tank 71 is set up to ensure that the subsequent reverse osmosis device 7 and the chlor-alkali salt pool will not affect the previous process during abnormal treatment, thereby ensuring the stable operation of the entire device.

[0034] The ultrafiltration device 6 includes an ultrafiltration raw water pump, a self-cleaning filter, an ultrafiltration membrane element, and an ultrafiltration backwash pump.

[0035] Part of the produced water of the reverse osmosis device 7 enters the backwash water tank 51 and is used as backwash water for the sand filter 51, the activated carbon filter 52, the ultrafiltration device 6 and the reverse osmosis device 7. The water after flushing enters the neutralization tank 2.

[0036] The working process of the utility model is as follows: the saponified residual liquid in the residual liquid buffer tank from the vinylidene chloride production process first enters the collecting and regulating tank 1, the stirring is started, and a certain amount of hydrochloric acid is added to convert the calcium hydroxide suspension in the residual liquid into water-soluble calcium chloride. The residual liquid after the addition of hydrochloric acid is sent to the neutralization tank 2 by a delivery pump. After sampling and analyzing the calcium ion concentration, a pre-prepared sodium sulfate solution is added according to n (SO42-): n (Ca2+) = 1:1 under mechanical stirring to convert the calcium ions in the residual liquid into calcium sulfate dihydrate. The residual liquid is pumped to the coagulation tank 3, 0.1% polyacrylamide (PAM) and 0.015% polyferric sulfate (PFS) are added as a mixed flocculant to cause the calcium sulfate dihydrate to flocculate and settle. The residual liquid is then sent to the plate and frame filter press 31 through a delivery pump for filtration. The filtrate re-enters the collecting and regulating tank 1, the filter cake is dried and transported out to be used as cement or hemihydrate calcium sulfate raw material, and the supernatant of the coagulation tank 3 overflows into the temporary storage tank 4 for wastewater after coagulation to reach a certain After reaching a certain level, the residual liquid is pumped to a sand filter 51 and an activated carbon filter 52 for the initial removal of suspended solids and COD in the residual liquid. After treatment in the activated carbon filter 52, the residual liquid is pumped to an ultrafiltration unit 6 for further removal of particulates and macromolecular organic matter. The ultrafiltration membrane device uses hollow fiber membranes and employs backwashing technology. The backwash liquid enters the inner side of the external pressure hollow fiber membrane through the permeate outlet of the membrane element, washing the membrane surface from the inside out to remove contaminants. The washed wastewater is discharged from the membrane element's sewage outlet. The residual liquid treated by the ultrafiltration unit 6 enters a temporary storage tank 61 for post-ultrafiltration wastewater. After reaching a certain level, it enters a reverse osmosis unit 7, effectively reducing the COD in the residual liquid to below 25 mg / L. The produced water meets the requirements for entering the salt pool of the chlor-alkali system. The concentrated water enters an evaporation crystallizer 8. The condensate obtained from the evaporation crystallization 8 is used to prepare the sodium sulfate solution in the neutralization tank. The impurities produced by drying the mother liquor are outsourced for treatment.

[0037] It should be understood that the above-described specific embodiments of the present invention are merely illustrative of or explanation of the principles of the present invention and do not constitute limitations of the present invention. Therefore, any modifications, equivalent substitutions, improvements, etc. made without departing from the spirit and scope of the present invention shall be included within the scope of protection of the present invention. In addition, the appended claims of the present invention are intended to cover all variations and modifications that fall within the scope and metes and bounds of the appended claims, or equivalents thereof.

Claims

1. A system for treating calcium chloride residual liquid generated in the production process of vinylidene chloride, characterized in that: include: A collecting and regulating tank (1) is provided with a collecting and regulating tank (1), wherein the residual liquid after the saponification reaction is collected at the inlet end; The neutralization tank (2) has an inlet end connected to the outlet end of the collection and adjustment tank (1); The coagulation tank (3) has an inlet end connected to the outlet end of the neutralization tank (2); A temporary storage tank (4) for wastewater after coagulation, the inlet of which is connected to the outlet of the coagulation tank (3); A sand filter (51) and an activated carbon filter (52), wherein the inlet end of the sand filter (51) is connected to the outlet end of the temporary storage tank (4) for wastewater after coagulation, and the inlet end of the activated carbon filter (52) is connected to the outlet end of the sand filter (51); An ultrafiltration device (6), the inlet end of which is connected to the outlet end of the activated carbon filter (52), and the outlet end of which is connected to a temporary storage tank (61) for wastewater after ultrafiltration; The inlet end of the reverse osmosis device (7) is connected to the outlet end of the temporary storage tank (61) for wastewater after ultrafiltration; The evaporation crystallizer (8) is connected to the concentrated liquid outlet of the reverse osmosis device (7) to perform evaporation crystallization.

2. The system for treating calcium chloride residual liquid generated in a vinylidene chloride production process according to claim 1, characterized in that: The coagulation tank (3) further includes a plate-frame filter press (31), the bottom discharge port of the coagulation tank (3) is connected to the plate-frame filter press (31) via a delivery pump, and the filtrate discharge port of the plate-frame filter press (31) is connected to the inlet end of the collection and adjustment tank (1).

3. The system for treating calcium chloride residual liquid generated in a vinylidene chloride production process according to claim 1, characterized in that: It also includes a sodium sulfate preparation tank (9), the top water outlet of which is connected to the condensate discharge outlet of the evaporation crystallizer (8) through a pipeline.

4. The system for treating calcium chloride residual liquid generated in a vinylidene chloride production process according to claim 1, characterized in that: A stirring device is provided in the collecting and regulating tank (1) and the neutralization tank (2).

5. The system for treating calcium chloride residual liquid generated in a vinylidene chloride production process according to claim 1, characterized in that: The refined brine outlet end of the reverse osmosis device (7) is connected to the water production tank (71), and the water outlet end of the water production tank (71) is connected to the chlor-alkali salt pool.

6. The system for treating calcium chloride residual liquid generated in a vinylidene chloride production process according to claim 5, characterized in that: The refined brine outlet of the reverse osmosis device (7) is also connected to a backwash water tank (10), and the outlet of the backwash water tank (10) is respectively connected to the backwash water outlets of the sand filter (51), the activated carbon filter (52), the ultrafiltration device (6) and the reverse osmosis device (7), and the backwash water outlets of the sand filter (51), the activated carbon filter (52), the ultrafiltration device (6) and the reverse osmosis device (7) are connected to the neutralization tank (2) through a pipeline.

7. The system for treating calcium chloride residual liquid generated in a vinylidene chloride production process according to claim 1, characterized in that: The wastewater outlet of the reverse osmosis device (7) is connected to the temporary storage tank (61) for wastewater after ultrafiltration.

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