Device for separating sodium carbonate from waste alkali liquor and recovering alkali liquor in calcium carbide method PVC (polyvinyl chloride) production

Abstract

The utility model relates to a device for separating sodium carbonate from waste lye and recovering lye in calcium carbide method PVC (polyvinyl chloride) production. The device comprises a waste lye buffer tank, a waste lye feeding pump, an air cooler, a primary condenser, a secondary condenser, a thickener, a centrifugal machine, a mother liquor tank and a mother liquor pump. An inlet pipeline of the waste alkali liquor feeding pump is communicated with the waste alkali liquor buffer tank, an outlet pipeline of the waste alkali liquor feeding pump is communicated with the air cooler, a sewer line of the air cooler is communicated with the primary condenser, a sewer line of the primary condenser is communicated with the secondary condenser, a sewer line of the secondary condenser is communicated with the thickener, and an overflow pipeline is arranged on the upper portion of the thickener. A mother liquor pipeline of the centrifugal machine is communicated with a mother liquor tank, an outlet pipeline of the mother liquor tank is communicated with a mother liquor pump, and a second backflow pipeline of the mother liquor pump is communicated with the mother liquor tank. Through the structure, the problems of waste of alkali liquor, increase of production cost and environmental pollution in the existing technological process for producing PVC through a calcium carbide method are solved.

Description

Technical Field

[0001] The utility model relates to the technical field of waste alkali solution separation, in particular to a sodium carbonate separation and alkali solution recovery device in waste alkali solution in the production of PVC by calcium carbide process. Background Art

[0002] Polyvinyl chloride, abbreviated as PVC (Polyvinyl chloride) in English, is a polymer formed by the polymerization of vinyl chloride monomer (VCM) in the presence of initiators such as peroxides and azo compounds, or by the free radical polymerization mechanism under the action of light or heat. Vinyl chloride homopolymers and vinyl chloride copolymers are collectively referred to as vinyl chloride resins.

[0003] PVC is an amorphous white powder with a small degree of branching, a relative density of about 1.4, a glass transition temperature of 77-90°C, and begins to decompose at around 170°C. It has poor stability to light and heat. At temperatures above 100°C or after prolonged exposure to sunlight, it will decompose to produce hydrogen chloride, and further autocatalytically decompose, causing discoloration and a rapid decline in physical and mechanical properties. In practical applications, stabilizers must be added to improve stability to heat and light.

[0004] PVC was once the world's most produced general-purpose plastic, and it is widely used in building materials, industrial products, daily necessities, floor coverings, floor tiles, artificial leather, pipes, wires and cables, packaging films, bottles, foaming materials, sealing materials, fibers, etc.

[0005] The calcium carbide production process is to use calcium carbide calcium carbide to react with water to generate acetylene, then use acetylene and hydrogen oxide to react to synthesize vinyl chloride monomer, and then polymerize it to generate PVC. The calcium carbide method has a lower production cost, so it is widely used.

[0006] In the existing process of producing PVC by calcium carbide method, the vinyl chloride production synthesis unit is designed with an alkali washing tower, the material used inside is a NaOH solution with a certain concentration, and the HCL and CO in the vinyl chloride gas are removed by chemical absorption. 2 When the gas is absorbed to a certain extent, the NaOH solution needs to be washed and replaced. The waste alkali solution is neutralized with hydrochloric acid, and then the solid and liquid are separated by evaporation equipment, and the liquid wastewater is discharged in compliance with the standards, resulting in waste of alkali solution, increased production costs and environmental pollution. Utility Model Content

[0007] The utility model provides a sodium carbonate separation and alkali solution recovery device in the production of PVC by calcium carbide method, which solves the problems of alkali solution waste, increased production cost and environmental pollution in the existing process of producing PVC by calcium carbide method.

[0008] The technical solution of the utility model to solve the above technical problems is as follows:

[0009] The inlet pipeline of the waste alkali liquid feeding pump is connected to the waste alkali liquid buffer tank, the outlet pipeline of the waste alkali liquid feeding pump is connected to the air cooler, the drain pipeline of the air cooler is connected to the primary condenser, the drain pipeline of the primary condenser is connected to the secondary condenser, the drain pipeline of the secondary condenser is connected to the thickener, an overflow pipeline is provided on the upper part of the thickener, the discharge pipeline of the thickener is connected to the centrifuge, the mother liquor pipeline of the centrifuge is connected to the mother liquor tank, the outlet pipeline of the mother liquor tank is connected to the mother liquor pump, and the second reflux pipeline of the mother liquor pump is connected to the mother liquor tank.

[0010] The utility model has the beneficial effects that the waste alkali liquid can be cooled in three stages through an air cooler, a primary condenser and a secondary condenser, and after cooling, the waste alkali liquid is passed through a centrifugal device to precipitate sodium carbonate and the like in the solution in a solid form, and the centrifugal mother liquor containing a higher NaOH concentration is reused in the alkali washing tower. After the waste alkali liquid is separated into solid and liquid, the NaOH containing a higher concentration is recycled, thereby reducing the loss of alkali liquid and reducing the production cost.

[0011] On the basis of the above technical solution, the present invention can also be improved as follows.

[0012] Furthermore, a first vent is provided at the top of the waste alkali liquid buffer tank, a first drain port is provided at the bottom, a first drain valve is provided at the first drain port, the outlet pipeline of the waste alkali liquid buffer tank is connected to the inlet pipeline of the waste alkali liquid feeding pump, and a first liquid level gauge, a first valve and a second valve are provided on the outlet pipeline of the waste alkali liquid buffer tank.

[0013] The beneficial effect of adopting the above further scheme is that the waste alkali liquid buffer tank has a first vent, and the first vent facilitates the venting operation of the waste alkali liquid buffer tank. The first vent of the waste alkali liquid buffer tank is opened, so that the sodium carbonate waste in the waste alkali liquid buffer tank is discharged through the first drain port at the bottom of the alkali liquid buffer tank, and the first drain valve can adjust the discharge amount of sodium carbonate. The first drain valve facilitates the drainage management of the waste alkali liquid buffer tank. The sodium hydroxide in the waste alkali liquid buffer tank enters the waste alkali liquid feeding pump through the first valve and the second valve. The first liquid level meter set in the waste alkali liquid buffer tank is a remote liquid level meter, which is convenient for remote liquid level monitoring of the waste alkali liquid buffer tank.

[0014] On the basis of the above technical solution, the present invention can also be improved as follows.

[0015] Furthermore, a first inlet valve is arranged on the inlet pipeline of the waste alkali liquid feeding pump, a first outlet valve, a first outlet pressure gauge and an outlet flow meter are arranged on the outlet pipeline of the waste alkali liquid feeding pump, the first reflux pipeline of the waste alkali liquid feeding pump is connected to the top of the waste alkali liquid buffer tank, and a first reflux valve is arranged on the first reflux pipeline of the waste alkali liquid feeding pump.

[0016] The beneficial effect of adopting the above further scheme is that the first inlet valve of the waste alkali liquid feeding pump can control the amount of sodium hydroxide entering the waste alkali liquid buffer tank. The waste alkali liquid feeding pump will allow part of the sodium hydroxide entering the pump to enter the air cooler through the outlet pipeline, and the other part will flow back to the waste alkali liquid buffer tank through the first reflux pipeline, and then flow into the waste alkali liquid feeding pump through the waste alkali liquid buffer tank again, and thus circulate. The first reflux pipeline of the waste alkali liquid feeding pump is connected to the waste alkali liquid buffer tank to form a circular flow, and the outlet flowmeter of the waste alkali liquid buffer tank and the waste alkali liquid feeding pump can be frequency-controlled to achieve the reflux of the waste alkali liquid buffer tank itself and stabilize the liquid level. The first outlet valve on the outlet pipeline of the waste alkali liquid feeding pump can control the amount of sodium hydroxide entering the air cooler, and observe and calculate the flow through the first outlet pressure gauge, and the frequency conversion and outlet flow remote transmission adjustment of the waste alkali liquid feeding pump are carried out through the outlet flowmeter.

[0017] On the basis of the above technical solution, the present invention can also be improved as follows.

[0018] Furthermore, a fan is arranged on the top of the air cooler, and a drain valve is arranged on the drain pipe of the air cooler.

[0019] The beneficial effect of adopting the above further scheme is that the sodium hydroxide entering the air cooler is cooled in the first step by the fan, and then the drain valve is opened to control the sodium hydroxide to enter the primary condenser through the drain pipeline.

[0020] On the basis of the above technical solution, the present invention can also be improved as follows.

[0021] Furthermore, the first-stage condenser has a water supply pipeline, a return pipeline and a drain pipeline. The water supply pipeline is provided with a first water supply regulating valve, a first water supply front regulating valve, and a first water supply rear regulating valve. The return pipeline is provided with a first return valve, and the drain pipeline is provided with a first outlet thermometer.

[0022] The beneficial effect of adopting the above further scheme is that the water supply pipeline and the return water pipeline of the primary condenser are connected to the channel circulating water main, and the circulating water is used to perform the second step of cooling and cooling of the sodium hydroxide in the primary condenser. Then, the value of the first outlet thermometer is observed, and the first outlet thermometer is set as a remote thermometer monitoring, and the cooling temperature of the waste alkali liquid can be remotely controlled and adjusted in real time. When the value of the first outlet thermometer meets the numerical standard for cooling, the drain valve is opened to control the sodium hydroxide to enter the secondary condenser through the drain pipeline.

[0023] On the basis of the above technical solution, the present invention can also be improved as follows.

[0024] Furthermore, the secondary condenser has a water supply pipeline, a return water pipeline and a drain water pipeline. The water supply pipeline is provided with a second water supply regulating valve, a second water supply front regulating valve, and a second water supply rear regulating valve. The return water pipeline is provided with a second return water valve, and the drain water pipeline is provided with a second outlet thermometer.

[0025] The beneficial effect of adopting the above further scheme is that the water supply pipeline and the return water pipeline of the secondary condenser are connected to the channel cold water main, and the sodium hydroxide in the secondary condenser is cooled down in the third step by low-temperature cold water. Then, the value of the second outlet thermometer is observed. In this embodiment, the second outlet thermometer is set as a remote thermometer monitoring, and the waste alkali solution cooling temperature can be remotely controlled and adjusted in real time. When the value of the second outlet thermometer meets the numerical standard for cooling, the drain valve is opened to control the sodium hydroxide to enter the thickener through the drain pipeline.

[0026] On the basis of the above technical solution, the present invention can also be improved as follows.

[0027] Furthermore, the thickener has a water supply pipeline, a return pipeline, a discharge pipeline and an overflow pipeline. The top of the thickener is provided with an agitator and a vent valve. The water supply pipeline of the thickener is provided with a water supply control valve, the return pipeline is provided with a reflux control valve, and the discharge pipeline is provided with a discharge regulating valve.

[0028] The beneficial effect of adopting the above further scheme is that the sodium hydroxide entering the thickener is stirred by the agitator, so that the waste alkali solution is mixed evenly and the storage buffer is prepared for the centrifugation of the mother liquor. The water supply pipeline and the return water pipeline of the thickener are connected to the channel cooling water pipeline, and the cooling water is used to cool the sodium hydroxide in the thickener in the fourth step. At the same time, when the sodium hydroxide entering the thickener exceeds the height of the overflow pipeline, it can be overflowed and discharged through the overflow pipeline, and the other sodium hydroxide in the thickener enters the centrifuge through the discharge pipeline.

[0029] On the basis of the above technical solution, the present invention can also be improved as follows.

[0030] Furthermore, the centrifuge has a mother liquor pipeline and a solid discharge pipeline, and the solid discharge pipeline is connected to the receiving box.

[0031] The beneficial effect of adopting the above further scheme is that the sodium carbonate entering the centrifuge is separated by utilizing the centrifugal principle of the centrifuge, the liquid sodium hydroxide enters the mother liquid tank, and the solid sodium carbonate is discharged through the discharge pipe.

[0032] On the basis of the above technical solution, the present invention can also be improved as follows.

[0033] Furthermore, the top of the mother liquid tank has a second vent, the bottom has a second drain port, the second drain port is provided with a second drain valve, and the mother liquid tank outlet pipeline is provided with a third valve, a fourth valve and a second liquid level gauge.

[0034] The beneficial effect of adopting the above further scheme is that the mother liquid tank has a second vent, and the second vent facilitates the emptying operation of the mother liquid tank. The liquid sodium hydroxide entering the mother liquid tank enters the mother liquid pump through the third valve and the fourth valve of the outlet pipeline, and other substances are discharged through the second vent. The second vent valve facilitates the drainage management of the waste alkali liquid buffer tank. The second liquid level gauge provided in the mother liquid tank is a remote liquid level gauge, which is convenient for remote liquid level monitoring of the mother liquid tank. The second liquid level gauge is controlled and adjusted to monitor and control the liquid level height in the mother liquid tank in real time.

[0035] On the basis of the above technical solution, the present invention can also be improved as follows.

[0036] Furthermore, a second reflux valve is arranged on the second reflux pipeline of the mother liquid pump, a second outlet valve and a second outlet pressure gauge are arranged on the outlet pipeline of the mother liquid pump, and a second inlet valve is arranged on the inlet pipeline of the mother liquid pump.

[0037] The beneficial effect of adopting the above further scheme is that part of the sodium hydroxide in the mother liquid pump flows out through the outlet pipeline, and the other part flows back into the mother liquid tank through the second reflux pipeline, enters the mother liquid pump again from the mother liquid tank, and flows out again through the outlet pipeline and the second reflux pipeline, and circulates out in this way. The mother liquid pump is connected to the mother liquid tank through the second reflux pipeline, which can relieve the pressure in the mother liquid pump. The sodium hydroxide flowing out through the outlet pipeline is collected in the alkali tank for recycling. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 The utility model is a schematic diagram of the process flow of a device for separating sodium carbonate from waste alkali liquor and recovering alkali liquor in the production of PVC by the calcium carbide process.

[0039] In the attached drawings, the parts represented by the reference numerals are as follows: 10-waste alkali liquid buffer tank; 11-first vent; 12-first drain valve; 13-first liquid level gauge; 15-first valve; 16-second valve; 20-waste alkali liquid feeding pump; 21-first inlet valve; 22-first outlet valve; 23-first outlet pressure gauge; 24-outlet flow meter; 25-first reflux valve; 26-first reflux pipeline; 30-air cooler; 31-fan; 32-down valve; 40-first condenser; 41-first water supply regulating valve; 42-first water supply front regulating valve; 43-first water supply rear regulating valve; 44-first water return valve; 45-first outlet thermometer; 50-secondary condenser; 51-first Second water supply regulating valve; 52-second water supply regulating valve before; 53-second water supply regulating valve after; 54-second return valve; 55-second outlet thermometer; 60-thickener; 61-agitation machine; 62-vent valve; 63-water supply control valve; 64-reflux control valve; 65-discharging regulating valve; 66-overflow pipeline; 70-centrifuge; 71-mother liquor pipeline; 72-solid discharging pipeline; 80-mother liquor tank; 81-second vent port; 82-second drain valve; 83-third valve; 84-fourth valve; 85-second liquid level gauge; 90-mother liquor pump; 91-second outlet valve; 92-second reflux pipeline; 93-second reflux valve; 94-second outlet pressure gauge; 95-second inlet valve. DETAILED DESCRIPTION

[0040] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0041] Example 1

[0042] like Figure 1 As shown, the inlet pipeline of the waste alkali liquid feeding pump 20 is connected to the waste alkali liquid buffer tank 10, the outlet pipeline of the waste alkali liquid feeding pump 20 is connected to the air cooler 30, the downpipeline of the air cooler 30 is connected to the primary condenser 40, the downpipeline of the primary condenser 40 is connected to the secondary condenser 50, the downpipeline of the secondary condenser 50 is connected to the thickener 60, an overflow pipeline 66 is provided on the upper part of the thickener 60, the downpipeline of the thickener 60 is connected to the centrifuge 70, the mother liquor pipeline 71 of the centrifuge 70 is connected to the mother liquor tank 80, the outlet pipeline of the mother liquor tank 80 is connected to the mother liquor pump 90, and the second reflux pipeline 92 of the mother liquor pump 90 is connected to the mother liquor tank 80.

[0043] Specifically, the waste alkali liquid in the waste alkali liquid buffer tank 10 can be transferred to the air cooler 30, the primary condenser 40 and the secondary condenser 50 through the waste alkali liquid feeding pump 20 for three-stage cooling, and then passed through a centrifugal device after cooling to precipitate the sodium carbonate and the like in the solution in a solid form. The centrifuged mother liquor containing a higher NaOH concentration is returned to the mother liquor tank 80 and transferred to the alkali washing tower for repeated use by the mother liquor pump 90.

[0044] like Figure 1 As shown, a first vent 11 is provided at the top of the waste alkali liquid buffer tank 10, a first drain port is provided at the bottom, a first drain valve 12 is provided at the first drain port, the outlet pipeline of the waste alkali liquid buffer tank 10 is connected to the inlet pipeline of the waste alkali liquid feeding pump 20, and a first liquid level gauge 13, a first valve 15 and a second valve 16 are provided on the outlet pipeline of the waste alkali liquid buffer tank 10.

[0045] Specifically, the first vent 11 of the waste alkali liquid buffer tank 10 is opened, so that the sodium carbonate in the waste alkali liquid buffer tank 10 can be precipitated to the bottom of the waste alkali liquid buffer tank 10, and the sodium carbonate is discharged through the first drain port at the bottom of the waste alkali liquid buffer tank 10. The first drain valve 12 can adjust the discharge amount of sodium carbonate. The sodium hydroxide in the waste alkali liquid buffer tank 10 enters the waste alkali liquid feeding pump 20 through the outlet pipeline. In this embodiment, the first liquid level gauge 13 provided in the waste alkali liquid buffer tank 10 is a remote liquid level gauge, which is convenient for remote liquid level monitoring of the waste alkali liquid buffer tank 10. The liquid level height is remotely monitored by the first liquid level gauge 13, and the sodium hydroxide entering the waste alkali liquid feeding pump 20 is controlled by the first valve 15 and the second valve 16.

[0046] like Figure 1 As shown, a first inlet valve 21 is arranged on the inlet pipeline of the waste alkali liquid feeding pump 20, a first outlet valve 22, a first outlet pressure gauge 23, and an outlet flow meter 24 are arranged on the outlet pipeline of the waste alkali liquid feeding pump 20, a first reflux pipeline 26 of the waste alkali liquid feeding pump 20 is connected to the top of the waste alkali liquid buffer tank 10, and a first reflux valve 25 is arranged on the first reflux pipeline 26 of the waste alkali liquid feeding pump 20.

[0047] Specifically, the first inlet valve 21 of the waste alkali liquid feeding pump 20 controls the amount of sodium hydroxide in the waste alkali liquid buffer tank 10 entering the waste alkali liquid feeding pump 20. The waste alkali liquid feeding pump 20 will allow part of the sodium hydroxide entering the pump to enter the air cooler 30 through the outlet pipeline, and the other part will flow back to the waste alkali liquid buffer tank 10 through the first reflux pipeline 26, which is controlled by the first reflux valve 25. Then, it flows into the waste alkali liquid feeding pump 20 through the waste alkali liquid buffer tank 10 again, and circulates in this way. The first outlet valve 22 on the outlet pipeline of the waste alkali liquid feeding pump 20 controls the amount of sodium hydroxide entering the air cooler 30, and observes and calculates the flow rate through the first outlet pressure gauge 23, and the frequency of the waste alkali liquid feeding pump 20 is changed and the outlet flow rate is remotely adjusted through the outlet flowmeter 24.

[0048] like Figure 1 As shown, a fan 31 is arranged on the top of the air cooler 30 , and a drain valve 32 is arranged on the drain pipe of the air cooler 30 .

[0049] Specifically, the sodium hydroxide entering the air cooler 30 is cooled in the first step by the fan 31 , and then the drain valve 32 is opened to control the sodium hydroxide to enter the primary condenser 40 through the drain pipeline.

[0050] like Figure 1 As shown, the primary condenser 40 has a water supply pipeline, a return water pipeline and a drain water pipeline. The water supply pipeline is provided with a first water supply regulating valve 41, a first water supply front regulating valve 42, and a first water supply rear regulating valve 43. The return water pipeline is provided with a first return water valve 44, and the drain water pipeline is provided with a first outlet thermometer 45.

[0051] Specifically, the water supply pipeline and the return water pipeline of the primary condenser 40 are connected to the channel circulating water main, and the circulating water is used to perform the second step of cooling and cooling the sodium hydroxide in the primary condenser 40. The amount of circulating water entering the primary condenser 40 is adjusted by adjusting the water supply pipeline on the water supply pipeline, which is provided with a first water supply regulating valve 41, a first water supply front regulating valve 42, and a first water supply rear regulating valve 43. In this embodiment, the water temperature of the circulating water is between 24°C and 25°C. Then, the value of the first outlet thermometer 45 is observed. In this embodiment, the first outlet thermometer 45 is set to remote thermometer monitoring, and the cooling temperature of the waste alkali solution can be remotely controlled and adjusted in real time. When the value of the first outlet thermometer 45 drops to 20°C, the drain valve of the primary condenser 40 is opened to control the sodium hydroxide to enter the secondary condenser 50 through the drain pipeline.

[0052] like Figure 1As shown, the secondary condenser 50 has a water supply pipeline, a return water pipeline and a drain water pipeline. The water supply pipeline is provided with a second water supply regulating valve 51, a second water supply front regulating valve 52, and a second water supply rear regulating valve 53. The return water pipeline is provided with a second return water valve 54, and the drain water pipeline is provided with a second outlet thermometer 55.

[0053] Specifically, the water supply pipeline and the return water pipeline of the secondary condenser 50 are connected to the channel cold water main, and the sodium hydroxide in the secondary condenser 50 is cooled and cooled in the third step by low-temperature cold water. The amount of cold water entering the secondary condenser 50 is adjusted by adjusting the second water supply regulating valve 51, the second water supply front regulating valve 52, and the second water supply rear regulating valve 53 on the water supply pipeline. In this embodiment, the water supply entering the secondary condenser 50 is 7°C cold water. Then, observe the value of the second outlet thermometer 55. In this embodiment, the second outlet thermometer 55 is set as a remote thermometer monitoring, and the cooling temperature of the waste alkali solution can be remotely controlled and adjusted in real time. When the value of the second outlet thermometer 55 is 7°C, open the drain valve of the secondary condenser 50 to control the sodium hydroxide to enter the thickener 60 through the drain pipeline.

[0054] like Figure 1 As shown, the thickener 60 has a water supply pipeline, a return pipeline, a discharge pipeline and an overflow pipeline 66. An agitator 61 and a vent valve 62 are arranged on the top of the thickener 60. The water supply pipeline of the thickener 60 is provided with a water supply control valve 63, the return pipeline is provided with a return control valve 64, and the discharge pipeline is provided with a discharge regulating valve 65.

[0055] Specifically, the vent valve 62 of the thickener 60 is opened, and the sodium hydroxide entering the thickener 60 is stirred by the stirrer 61. The water supply line and the return line of the thickener 60 are connected to the cooling water pipeline, and the inflow and outflow of cooling water are controlled by the water supply control valve 63 and the return control valve 64. The cooling water is used to cool the sodium hydroxide in the thickener 60 in the fourth step. At the same time, when the sodium hydroxide entering the thickener 60 exceeds the height of the overflow line 66, it can be overflowed and discharged through the overflow line 66, and the other sodium hydroxide in the thickener 60 enters the centrifuge 70 through the discharge line.

[0056] like Figure 1 As shown, the centrifuge 70 has a mother liquor pipeline 71 and a solid discharge pipeline 72, and the solid discharge pipeline 72 is connected to a receiving box.

[0057] Specifically, the sodium hydroxide entering the centrifuge 70 is separated by the centrifugal principle of the centrifuge 70 , the liquid sodium hydroxide enters the mother liquid tank 80 , and the solid sodium carbonate is discharged through the solid discharge pipe 72 .

[0058] like Figure 1As shown, the top of the mother liquid tank 80 has a second vent 81, the bottom has a second drain port, the second drain port is provided with a second drain valve 82, and the outlet pipeline of the mother liquid tank 80 has a third valve 83, a fourth valve 84 and a second liquid level meter 85.

[0059] Specifically, the second venting port 81 is opened to empty the mother liquid tank 80. The liquid sodium hydroxide entering the mother liquid tank 80 enters the mother liquid pump 90 through the outlet pipeline. In this embodiment, the second liquid level gauge 85 provided in the mother liquid tank 80 is a remote liquid level gauge, which is convenient for remote liquid level monitoring of the mother liquid tank 80. The second liquid level gauge 85 is controlled and adjusted to monitor and control the liquid level in the mother liquid tank 80 in real time. The third valve 83 and the fourth valve 84 are used for input control. Other substances are discharged through the second exhaust port and controlled by the second exhaust valve 82.

[0060] like Figure 1 As shown, a second reflux valve 93 is provided on the second reflux pipeline 92 of the mother liquid pump 90 , a second outlet valve 91 and a second outlet pressure gauge 94 are provided on the outlet pipeline of the mother liquid pump 90 , and a second inlet valve 95 is provided on the inlet pipeline of the mother liquid pump 90 .

[0061] Specifically, part of the sodium hydroxide in the mother liquid pump 90 flows out into the alkali tank through the outlet pipeline, and the other part flows back into the mother liquid tank 80 through the second reflux pipeline 92, and then enters the mother liquid pump 90 again from the mother liquid tank 80, and then flows out in a cycle through the outlet pipeline and the second reflux pipeline 92. The mother liquid pump 90 is connected to the mother liquid tank 80 through the second reflux pipeline 92, which can relieve the pressure in the mother liquid pump 90. The sodium hydroxide flowing out through the outlet pipeline is collected in the alkali tank for recycling.

[0062] The beneficial effect of this embodiment is that the waste alkali liquid can be cooled in three stages through the air cooler 30, the primary condenser 40 and the secondary condenser 50, and after cooling, the waste alkali liquid can be separated by the centrifugal device using the centrifugal principle of the centrifuge 70 to separate the sodium hydroxide entering the centrifuge 70, so that the sodium carbonate and the like in the solution are precipitated in a solid form, and the centrifugal mother liquor containing a higher NaOH concentration is reused in the alkali washing tower. After the waste alkali liquid is separated into solid and liquid, the NaOH containing a higher concentration is recycled, thereby reducing the loss of alkali liquid and reducing the production cost.

[0063] The working process of this embodiment is as follows: the first venting port 11 of the waste alkali liquid buffer tank 10 is opened, so that the sodium carbonate in the waste alkali liquid buffer tank 10 can be precipitated to the bottom of the waste alkali liquid buffer tank 10, and the sodium carbonate is discharged through the first draining port at the bottom of the waste alkali liquid buffer tank 10, and the first draining valve 12 can adjust the discharge amount of the sodium carbonate. The sodium hydroxide in the waste alkali liquid buffer tank 10 enters the waste alkali liquid feeding pump 20 through the outlet pipeline, and the liquid level height in the waste alkali liquid buffer tank 10 is remotely monitored by the first liquid level meter 13, and the sodium hydroxide entering the waste alkali liquid feeding pump 20 is controlled by the first valve 15 and the second valve 16.

[0064] The first inlet valve 21 of the waste alkali liquid feeding pump 20 controls the amount of sodium hydroxide in the waste alkali liquid buffer tank 10 entering the waste alkali liquid feeding pump 20. The waste alkali liquid feeding pump 20 allows part of the sodium hydroxide entering the pump to enter the air cooler 30 through the outlet pipeline, and the other part flows back to the waste alkali liquid buffer tank 10 through the first reflux pipeline 26, which is controlled by the first reflux valve 25. Then, it flows into the waste alkali liquid feeding pump 20 again through the waste alkali liquid buffer tank 10, and circulates in this way. The first outlet valve 22 on the outlet pipeline of the waste alkali liquid feeding pump 20 controls the amount of sodium hydroxide entering the air cooler 30, and observes and calculates the flow rate through the first outlet pressure gauge 23, and the frequency of the waste alkali liquid feeding pump 20 is changed and the outlet flow rate is remotely adjusted through the outlet flowmeter 24.

[0065] The sodium hydroxide entering the air cooler 30 is cooled in the first step by the fan 31 , and then the drain valve 32 is opened to control the sodium hydroxide to enter the primary condenser 40 through the drain pipeline.

[0066] The water supply pipeline and the return water pipeline of the primary condenser 40 are connected to the circulating water main, and the circulating water is used to perform the second step of cooling and lowering the temperature of the sodium hydroxide in the primary condenser 40. The amount of circulating water entering the primary condenser 40 is adjusted by adjusting the first water supply regulating valve 41, the first water supply front regulating valve 42, and the first water supply rear regulating valve 43 provided on the water supply pipeline. In this embodiment, the water temperature of the circulating water is between 24°C and 25°C. Then, the value of the first outlet thermometer 45 is remotely observed. When the value of the first outlet thermometer 45 drops to 20°C, the drain valve is opened to control the sodium hydroxide to enter the secondary condenser 50 through the drain pipeline.

[0067] The water supply pipeline and the return water pipeline of the secondary condenser 50 are connected to the cold water main pipe, and the sodium hydroxide in the secondary condenser 50 is cooled down in the third step by using low-temperature cold water. The amount of cold water entering the secondary condenser 50 is adjusted by adjusting the second water supply regulating valve 51, the second water supply front regulating valve 52, and the second water supply rear regulating valve 53 on the water supply pipeline. In this embodiment, the water supply entering the secondary condenser 50 is 7°C cold water. Then, the value of the second outlet thermometer 55 is remotely observed. When the value of the second outlet thermometer 55 is 7°C, the water discharge valve is opened to control the sodium hydroxide to enter the thickener 60 through the water discharge pipeline.

[0068] The vent valve 62 of the thickener 60 is opened, and the sodium hydroxide entering the thickener 60 is stirred by the stirrer 61. The water supply pipeline and the return water pipeline of the thickener 60 are connected to the cooling water pipeline, and the inflow and outflow of cooling water are controlled by the water supply control valve 63 and the return control valve 64. The cooling water is used to cool the sodium hydroxide in the thickener 60 in the fourth step. At the same time, when the sodium hydroxide entering the thickener 60 exceeds the height of the overflow pipeline 66, it can overflow and discharge through the overflow pipeline 66, and the other sodium hydroxide in the thickener 60 enters the centrifuge 70 through the discharge pipeline.

[0069] The sodium hydroxide entering the centrifuge 70 is separated by the centrifugal principle of the centrifuge 70 , the liquid sodium hydroxide enters the mother liquid tank 80 , and the solid sodium carbonate is discharged through the solid discharge pipe 72 .

[0070] The second venting port 81 is opened to empty the mother liquid tank 80. The liquid sodium hydroxide entering the mother liquid tank 80 enters the mother liquid pump 90 through the outlet pipeline, and is controlled and regulated by the second liquid level meter 85 to monitor and control the liquid level in the mother liquid tank 80 in real time. The third valve 83 and the fourth valve 84 control the input. Other substances are discharged through the second exhaust port, which is controlled by the second exhaust valve 82.

[0071] A part of the sodium hydroxide in the mother liquid pump 90 flows out into the alkali tank through the outlet pipeline, and the other part flows back into the mother liquid tank 80 through the second reflux pipeline 92, and then enters the mother liquid pump 90 again from the mother liquid tank 80, and then flows out in a cycle through the outlet pipeline and the second reflux pipeline 92. The mother liquid pump 90 is connected to the mother liquid tank 80 through the second reflux pipeline 92, which can relieve the pressure in the mother liquid pump 90. The sodium hydroxide flowing out through the outlet pipeline is collected in the alkali tank for recycling.

[0072] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0073] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present utility model, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0074] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0075] In the present utility model, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0076] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the utility model. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0077] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations of the present invention. Ordinary technicians in the field can change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A device for separating sodium carbonate from waste alkali liquor and recovering alkali liquor in the production of PVC by calcium carbide process, characterized in that: The invention comprises a waste alkali liquid buffer tank (10), a waste alkali liquid feeding pump (20), an air cooler (30), a primary condenser (40), a secondary condenser (50), a thickener (60), a centrifuge (70), a mother liquid tank (80) and a mother liquid pump (90), wherein the inlet pipeline of the waste alkali liquid feeding pump (20) is connected to the waste alkali liquid buffer tank (10), the outlet pipeline of the waste alkali liquid feeding pump (20) is connected to the air cooler (30), the drain pipeline of the air cooler (30) is connected to the primary condenser (40), and the primary condenser ( The downflow pipeline of the secondary condenser (40) is connected to the secondary condenser (50), the downflow pipeline of the secondary condenser (50) is connected to the thickener (60), an overflow pipeline (66) is provided on the upper part of the thickener (60), the downflow pipeline of the thickener (60) is connected to the centrifuge (70), the mother liquor pipeline (71) of the centrifuge (70) is connected to the mother liquor tank (80), the outlet pipeline of the mother liquor tank (80) is connected to the mother liquor pump (90), and the second reflux pipeline (92) of the mother liquor pump (90) is connected to the mother liquor tank (80).

2. The device for separating sodium carbonate from waste alkali liquor and recovering alkali liquor in the production of PVC by calcium carbide process according to claim 1, characterized in that: The waste alkali liquid buffer tank (10) is provided with a first vent (11) at the top and a first drain port at the bottom. A first drain valve (12) is provided at the first drain port. The outlet pipeline of the waste alkali liquid buffer tank (10) is connected to the inlet pipeline of the waste alkali liquid feeding pump (20). The outlet pipeline of the waste alkali liquid buffer tank (10) is provided with a first liquid level meter (13), a first valve (15) and a second valve (16).

3. The device for separating sodium carbonate from waste alkali liquor and recovering alkali liquor in the production of PVC by calcium carbide process according to claim 1, characterized in that: The inlet pipeline of the waste alkali liquid feeding pump (20) is provided with a first inlet valve (21); the outlet pipeline of the waste alkali liquid feeding pump (20) is provided with a first outlet valve (22), a first outlet pressure gauge (23), and an outlet flow meter (24); the first reflux pipeline (26) of the waste alkali liquid feeding pump (20) is connected to the top of the waste alkali liquid buffer tank (10); and the first reflux valve (25) is provided on the first reflux pipeline (26) of the waste alkali liquid feeding pump (20).

4. The device for separating sodium carbonate from waste alkali liquor and recovering alkali liquor in the production of PVC by calcium carbide process according to claim 1, characterized in that: A fan (31) is provided on the top of the air cooler (30), and a drain valve (32) is provided on the drain pipeline of the air cooler (30).

5. The device for separating sodium carbonate from waste alkali liquor and recovering alkali liquor in the production of PVC by calcium carbide process according to claim 1, characterized in that: The primary condenser (40) comprises a water supply pipeline, a water return pipeline and a water discharge pipeline. The water supply pipeline is provided with a first water supply regulating valve (41), a first water supply front regulating valve (42) and a first water supply rear regulating valve (43). The water return pipeline is provided with a first water return valve (44). The water discharge pipeline is provided with a first outlet thermometer (45).

6. The device for separating sodium carbonate from waste alkali liquor and recovering alkali liquor in the production of PVC by calcium carbide process according to claim 1, characterized in that: The secondary condenser (50) comprises a water supply pipeline, a water return pipeline and a water discharge pipeline. The water supply pipeline is provided with a second water supply regulating valve (51), a second water supply front regulating valve (52) and a second water supply rear regulating valve (53). The water return pipeline is provided with a second water return valve (54). The water discharge pipeline is provided with a second outlet thermometer (55).

7. The device for separating sodium carbonate from waste alkali liquor and recovering alkali liquor in the production of PVC by calcium carbide process according to claim 1, characterized in that: The thickener (60) comprises a water supply pipeline, a water return pipeline, a material discharge pipeline and an overflow pipeline (66). A stirrer (61) and a vent valve (62) are arranged on the top of the thickener (60). The water supply pipeline of the thickener (60) comprises a water supply control valve (63), the return pipeline comprises a return control valve (64), and the material discharge pipeline comprises a material discharge regulating valve (65).

8. The device for separating sodium carbonate from waste alkali liquor and recovering alkali liquor in the production of PVC by calcium carbide process according to claim 1, characterized in that: The centrifuge (70) comprises a mother liquid pipeline (71) and a solid discharge pipeline (72), and the solid discharge pipeline (72) is connected to a material receiving box.

9. The device for separating sodium carbonate from waste alkali liquor and recovering alkali liquor in the production of PVC by calcium carbide process according to claim 1, characterized in that: The mother liquid tank (80) has a second vent (81) at the top and a second drain port at the bottom. The second drain port is provided with a second drain valve (82). The mother liquid tank (80) outlet pipeline is provided with a third valve (83), a fourth valve (84) and a second liquid level gauge (85).

10. The device for separating sodium carbonate from waste alkali liquor and recovering alkali liquor in the production of PVC by calcium carbide process according to claim 9, characterized in that: A second reflux valve (93) is provided on the second reflux pipeline (92) of the mother liquid pump (90), a second outlet valve (91) and a second outlet pressure gauge (94) are provided on the outlet pipeline of the mother liquid pump (90), and a second inlet valve (95) is provided on the inlet pipeline of the mother liquid pump (90).

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