System and method for efficiently removing free carbon disulfide in liquid ethyl xanthate

Abstract

The invention discloses a system and a method for efficiently removing free carbon disulfide in liquid ethyl xanthate, belongs to the field of production of liquid ethyl xanthate, and solves the problem that the free carbon disulfide has potential safety hazards and causes environmental pollution. The system comprises an aeration tank, a vacuum system and an absorption tank which are connected in sequence, a liquid inlet pipe, an air outlet pipe and a first liquid discharge pipe are arranged on the aeration tank, and the air outlet pipe is connected to the air inlet end of the vacuum system; a spraying pipe is arranged in the aeration tank and is connected with the liquid inlet pipe; a gas inlet pipe, a tail gas pipe, an ethanol pipe and a second liquid discharge pipe are arranged on the absorption tank; the gas inlet pipe is connected to the gas outlet end of the vacuum system; a first gas distribution pipe is arranged in the absorption tank and is connected with the gas inlet pipe. Tiny liquid drops are formed in a spraying mode, a long gas-liquid contact time is obtained in the falling process, carbon disulfide is converted into gas to be removed, and a gas phase containing carbon disulfide steam enters the absorption tank to be recycled by absolute ethyl alcohol.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of liquid ethyl xanthate production, and particularly relates to a system and method for efficiently removing free carbon disulfide in liquid ethyl xanthate. BACKGROUND

[0002] Carbon disulfide is a main raw material for producing liquid xanthate, which is an extremely volatile organic substance, extremely flammable, and irritating, damaging nerves and blood vessels, and causing problems such as catalyst deactivation and equipment corrosion. The dissolved and unreacted carbon disulfide in liquid ethyl xanthate is collectively referred to as free carbon disulfide, which can cause safety problems, and if it accumulates in a ditch or low-lying area, it can easily cause a fire. Secondly, the volatilization of free carbon disulfide is the source of environmental pollution. SUMMARY

[0003] The purpose of the present application is to provide a system for efficiently removing free carbon disulfide in liquid ethyl xanthate, to solve the problems of safety hazards and environmental pollution caused by free carbon disulfide.

[0004] Another purpose of the present application is to provide a method for efficiently removing free carbon disulfide in liquid ethyl xanthate.

[0005] The technical solution of the present application is: a system for efficiently removing free carbon disulfide in liquid ethyl xanthate, comprising a gas exposure tank, a vacuum system and an absorption tank connected in sequence; The gas exposure tank is provided with a liquid inlet pipe, a gas outlet pipe and a first liquid outlet pipe, the gas outlet pipe is connected to the gas inlet end of the vacuum system; the gas exposure tank is provided with a spraying pipe, the spraying pipe is close to the top of the gas exposure tank, the spraying pipe is connected to the liquid inlet pipe, a plurality of nozzles are arranged on the spraying pipe, and a first valve is arranged on the first liquid outlet pipe; The absorption tank is provided with a gas inlet pipe, a tail gas pipe, an ethanol pipe and a second liquid outlet pipe, the gas inlet pipe is connected to the gas outlet end of the vacuum system, the ethanol pipe is connected to an ethanol feeding system, and a second valve is arranged on the second liquid outlet pipe; the absorption tank is provided with a first gas distribution pipe connected to the gas inlet pipe.

[0006] As a further improvement of the present application, a nitrogen main pipe is further included, the nitrogen main pipe is connected to two nitrogen branch pipes, the gas exposure tank is provided with a second gas distribution pipe and a third gas distribution pipe, the second gas distribution pipe is vertically arranged, the third gas distribution pipe is horizontally arranged, and the second gas distribution pipe and the third gas distribution pipe are respectively connected to the two nitrogen branch pipes.

[0007] As a further improvement of the present application, the gas outlet pipe is located at the top of the gas exposure tank, and a liquid blocking plate is arranged below the gas outlet pipe.

[0008] As a further improvement of the present application, the first liquid outlet pipe is connected to a xanthate storage tank through a discharge shielding pump.

[0009] As a further improvement of the present application, the gas exposure tank is provided with a first pressure monitoring device.

[0010] As a further improvement of the present application, the material holding grid is provided with a wire mesh, and the filler is laid on the wire mesh.

[0011] As a further improvement of the present application, the second liquid discharge pipe is connected to the reaction kettle through a pneumatic diaphragm pump.

[0012] As a further improvement of the present application, the absorption tank is provided with a second pressure monitoring device and a temperature detection device.

[0013] As a further improvement of the present application, a cooling bypass pipe is coiled on the outer wall of the absorption tank, and the cooling bypass pipe is connected to a cooling unit.

[0014] A method for efficiently removing free carbon disulfide in liquid ethyl xanthate, using the above-mentioned system for efficiently removing free carbon disulfide in liquid ethyl xanthate, comprises the following steps: A, start the vacuum system, so that the gas exposure tank has a vacuum degree; B, add anhydrous ethanol into the absorption tank through the ethanol pipe, so that the anhydrous ethanol covers the filler; C, the liquid ethyl xanthate containing free carbon disulfide is poured into the spraying pipe through the liquid inlet pipe, and the liquid ethyl xanthate is sprayed into the gas exposure tank through the nozzle, and in the process of falling of the liquid ethyl xanthate droplets, the free carbon disulfide is removed; D, the gas phase containing carbon disulfide vapor in the gas exposure tank passes through the gas outlet pipe, the vacuum system and the gas inlet pipe in sequence into the absorption tank, and is dispersed in the anhydrous ethanol through the first gas distribution pipe, and the carbon disulfide is absorbed by the anhydrous ethanol, so as to recover the carbon disulfide, and the gas phase is discharged through the tail gas pipe; E, open the first valve, and the liquid ethyl xanthate collected in the gas exposure tank is discharged through the first liquid discharge pipe; F, after a period of operation, open the second valve, and the anhydrous ethanol containing carbon disulfide is discharged through the second liquid discharge pipe.

[0015] The present application has the following advantages: 1. The present application forms micro droplets in the form of spraying, increases the specific surface area of the liquid ethyl xanthate, and increases the gas-liquid contact area, at the same time, the liquid ethyl xanthate containing carbon disulfide falls under the action of gravity, and obtains a larger gas-liquid contact time in the falling process, and the carbon disulfide therein is converted into gas and removed under the condition of negative pressure, and the gas phase containing carbon disulfide vapor enters the absorption tank and is recovered by the anhydrous ethanol. The present application optimizes the distribution of droplets in time and space, and significantly improves the removal efficiency and separation effect of free carbon disulfide.

[0016] 2. The present application sets up vertical second air distribution pipe and horizontal third air distribution pipe in the gas exposure tank, respectively spreads nitrogen to liquid ethyl xanthate from different positions, agitates liquid from different dimensions, and promotes further removal of free carbon disulfide in liquid ethyl xanthate.

[0017] 3. The present application sets up filler in the absorption tank, prolongs the residence time of carbon disulfide gas in anhydrous ethanol, increases the gas-liquid contact time, optimizes the distribution of carbon disulfide gas in time and space, and significantly improves the absorption efficiency of anhydrous ethanol.

[0018] 4. The process method of the present application is simple, has high efficiency in removing free carbon disulfide in liquid ethyl xanthate, has low construction cost and operation cost, and is particularly suitable for large-scale industrial production. It can not only eliminate the ignition hazard from the source, control environmental pollution, and achieve the purpose of treatment, but also can recycle the removed carbon disulfide for production system, and produce certain economic benefits. BRIEF DESCRIPTION OF DRAWINGS

[0019] Fig. 1 is a structural schematic diagram of a system for efficiently removing free carbon disulfide in liquid ethyl xanthate according to the present application; Fig. 2 is a schematic diagram of the internal structure of the gas exposure tank in the present application; Fig. 3 is a schematic diagram of the internal structure of the absorption tank in the present application.

[0020] In the figure, 1 is a gas exposure tank, 2 is an absorption tank, 3 is a vacuum system, 4 is a liquid inlet pipe, 5 is a gas outlet pipe, 6 is a vacuum system gas inlet end, 7 is a first liquid outlet pipe, 8 is a discharge shielding pump, 9 is a nitrogen main pipe, 10 is a nitrogen branch pipe, 11 is a nitrogen valve, 12 is a vacuum system gas outlet end, 13 is a gas inlet pipe, 14 is a second liquid outlet pipe, 15 is a pneumatic diaphragm pump, 16 is a temperature detection device, 17 is a second pressure monitoring device, 18 is a tail gas pipe, 19 is a cooling bypass pipe, 20 is a first pressure monitoring device, 21 is a spraying pipe, 22 is a nozzle, 23 is a second air distribution pipe, 24 is a third air distribution pipe, 25 is a liquid blocking plate, 26 is a material holding grid, 27 is a metal mesh, 28 is a filler, 29 is a first air distribution pipe, 30 is an ethanol pipe, 32 is a second valve, and 33 is a first valve. DETAILED DESCRIPTION

[0021] The present application will be further described in detail below in combination with the drawings and specific embodiments.

[0022] As shown in Figs. 1-3 , a system for efficiently removing free carbon disulfide in liquid ethyl xanthate includes a gas exposure tank 1, a vacuum system 3, and an absorption tank 2 connected in sequence. The gas exposure tank 1 is provided with a liquid inlet pipe 4, an air outlet pipe 5 and a first liquid discharge pipe 7, the air outlet pipe 5 is connected to a vacuum system air inlet end 6; the gas exposure tank 1 is provided with a spraying pipe 21, the spraying pipe 21 is close to the top of the gas exposure tank 1, the spraying pipe 21 is connected to the liquid inlet pipe 4, the spraying pipe 21 is arranged in a ring shape or a cross shape, a plurality of nozzles 22 are arranged on the spraying pipe 21, and a first valve 33 is arranged on the first liquid discharge pipe 7. The absorption tank 2 is provided with an air inlet pipe 13, a tail gas pipe 18, an ethanol pipe 30 and a second liquid discharge pipe 14, the air inlet pipe 13 is connected to a vacuum system air outlet end 12, the tail gas pipe 18 and the ethanol pipe 30 are located at the top of the absorption tank 2, the ethanol pipe 30 is connected to an ethanol feeding system, and a second valve 32 is arranged on the second liquid discharge pipe 14; the absorption tank 2 is provided with a first air distribution pipe 29, the first air distribution pipe 29 is close to the bottom of the absorption tank 2, the first air distribution pipe 29 is connected to the air inlet pipe 13, the first air distribution pipe 29 is arranged in a ring shape or a cross shape, and a plurality of air holes are arranged on the first air distribution pipe 29.

[0023] Further comprising a nitrogen main pipe 9, two nitrogen branch pipes 10 are connected to the nitrogen main pipe 9, a second air distribution pipe 23 and a third air distribution pipe 24 are arranged in the gas exposure tank 1, the third air distribution pipe 24 is close to the bottom of the gas exposure tank 1, the third air distribution pipe 24 is arranged in a ring shape or a cross shape, a plurality of air holes are arranged on the lower section of the second air distribution pipe 23 and the upper section of the third air distribution pipe 24, the second air distribution pipe 23 is arranged vertically, the third air distribution pipe 24 is arranged horizontally, and the second air distribution pipe 23 and the third air distribution pipe 24 are respectively connected to the two nitrogen branch pipes 10. A nitrogen valve 11 is arranged on the nitrogen branch pipe 10, so as to control the on-off and flow rate of each nitrogen branch pipe 10.

[0024] The air outlet pipe 5 is located at the top of the gas exposure tank 1, a liquid blocking plate 25 is arranged below the air outlet pipe 5, a part of the area directly opposite to the air outlet is partially blocked, so as to prevent liquid drops from entering the vacuum system 3 through the air outlet pipe 5.

[0025] The first liquid discharge pipe 7 is connected to a xanthate storage tank through a discharge shielding pump 8.

[0026] A first pressure monitoring device 20 is arranged on the gas exposure tank 1, so as to monitor the vacuum degree in the gas exposure tank 1.

[0027] Further comprising a material containing grid 26, the material containing grid 26 is located above the first air distribution pipe 29, and a filler 28 is arranged on the material containing grid 26. A metal mesh 27 is arranged on the material containing grid 26, and the filler 28 is laid on the metal mesh 27, so as to prevent the filler 28 from falling off.

[0028] The second liquid discharge pipe 14 is connected to a reaction kettle through a pneumatic diaphragm pump 15.

[0029] The second pressure monitoring device 17 and the temperature detecting device 16 are arranged on the absorption tank 2. The frequency of the fan of the tail gas treatment system can be adjusted according to the pressure value monitored by the second pressure monitoring device 17, so that the system maintains a micro negative pressure, thereby ensuring the sufficient absorption of carbon disulfide. The temperature detecting device 16 detects the temperature in the absorption tank 2, thereby facilitating the timely cooling treatment.

[0030] The cooling bypass pipe 19 is coiled on the outer wall of the absorption tank 2 and is connected with the cooling unit.

[0031] The liquid level meters are arranged in the gas exposure tank 1 and the absorption tank 2. When the liquid level in the gas exposure tank 1 reaches a certain height, the spraying is stopped. When the liquid level in the absorption tank 2 reaches a certain height, the gas into the absorption tank 2 is stopped, and the anhydrous ethanol absorbing carbon disulfide is poured into the reaction kettle to participate in the reaction of synthesizing xanthate.

[0032] The nozzle 22 can be a spiral nozzle, or an atomizing nozzle, a hollow conical nozzle, a self-cleaning nozzle, a vortex nozzle, an SMP nozzle, etc.

[0033] The packing 28 can be a Pall ring, a stepped ring, a matrix saddle ring, a Raschig ring.

[0034] The vacuum system 3 adopts a water ring vacuum unit.

[0035] The first pressure detecting device 20 can be associated with the adjusting valve of the vacuum system 3, and the DCS system controls the pressure in the gas exposure tank 1 to be in a suitable range by automatically adjusting the opening degree of the adjusting valve.

[0036] The thickness of the packing 28 is preferably 1000mm-1500mm.

[0037] A method for efficiently removing free carbon disulfide in liquid ethyl xanthate, comprising the following steps: A. The vacuum system 3 is started, and the vacuum degree in the gas exposure tank 1 reaches a predetermined value.

[0038] B. Fresh anhydrous ethanol is added into the absorption tank 2 through the ethanol pipe 30 by the shield pump, so that the anhydrous ethanol covers the packing 28.

[0039] C. The liquid ethyl xanthate containing free carbon disulfide is poured into the spraying pipe 21 by the shield pump through the liquid inlet pipe 4, and the liquid ethyl xanthate is sprayed into the gas exposure tank 1 by the nozzle 22. In the process of falling of the liquid ethyl xanthate droplets, the free carbon disulfide is removed. Nitrogen is transported into the gas exposure tank 1 through the nitrogen main pipe 9 and the nitrogen branch pipe 10, and the nitrogen escapes from the second gas distribution pipe 23 and the third gas distribution pipe 24 into the liquid ethyl xanthate, thereby agitating the liquid and promoting the further removal of the free carbon disulfide in the liquid.

[0040] D. The gas phase containing carbon disulfide vapor in the aeration tank 1 enters the absorption tank 2 sequentially through the outlet pipe 5, vacuum system 3, and inlet pipe 13, and is then distributed into anhydrous ethanol through the first gas distribution pipe 29. The carbon disulfide is absorbed by the anhydrous ethanol, thus recovering the carbon disulfide. The gas phase is discharged to the tail gas treatment system through the tail gas pipe 18. After treatment by the tail gas treatment system, the tail gas is discharged in compliance with standards. The cooling unit introduces 5°C cooling water through the cooling bypass pipe 19. The cooling water enters from the lower end and exits from the upper end of the cooling bypass pipe 19, cooling the anhydrous ethanol in the absorption tank 2 to keep its temperature below 10°C, ensuring sufficient absorption of carbon disulfide.

[0041] E. After the liquid ethyl xanthate collected in the aeration tank 1 reaches the predetermined liquid level, the vacuum is continuously maintained for a period of time. Then, the vacuum system 3 is stopped, nitrogen is added to the aeration tank 1 to normal pressure, and the first valve 33 is opened. The liquid ethyl xanthate after the free carbon disulfide is removed is discharged from the first drain pipe 7 and pumped to the xanthate storage tank by the discharge shield pump 8.

[0042] F. After a period of operation, the anhydrous ethanol absorbs carbon disulfide to a certain concentration. Then, the second valve 32 is opened, and the anhydrous ethanol that has absorbed carbon disulfide is discharged through the second drain pipe 14 and pumped to the reaction vessel by the pneumatic diaphragm pump 15 to participate in the reaction for the synthesis of liquid ethyl xanthate.

[0043] Example 1 The aeration tank 1 has a diameter of 2 meters and a height of 3 meters, and is made of 316L stainless steel to enhance corrosion resistance.

[0044] Nozzle 22 adopts a double-layer spiral nozzle (model: SP-25), which increases the spray coverage to 95% and controls the droplet size to 50-100μm.

[0045] The nitrogen flow rate is dynamically adjusted via the DCS system (0.5-1.5 m³ / min).

[0046] The filler 28 uses high-efficiency Pall rings (material: polytetrafluoroethylene), with a laying height of 1.6 meters and a specific surface area of ​​200 m² / m³.

[0047] The cooling water temperature is 2℃ to ensure that the temperature of anhydrous ethanol remains stable below 5℃.

[0048] Liquid ethyl xanthate containing free carbon disulfide (carbon disulfide content 2.0%) was delivered to aeration tank 1 at a flow rate of 5 m³ / h, and the vacuum degree inside aeration tank 1 was maintained at -0.02 MPa. After the liquid delivery was completed, the degassing time was extended to 40 minutes.

[0049] When the carbon disulfide concentration in anhydrous ethanol reaches 45%, the anhydrous ethanol is discharged and reused.

[0050] After the exhaust gas is treated by the exhaust gas treatment system (activated carbon adsorption), the emission concentration is less than 10 mg / m³ (compliant with GB31571-2015 standard).

[0051] Performance verification: Carbon disulfide removal rate ≥75% (carbon disulfide content in finished solution ≤0.50%); carbon disulfide recovery rate >90% and anhydrous ethanol loss rate <1% through absorption with anhydrous ethanol.

[0052] Example 2 The aeration tank 1 has a diameter of 1.5 meters and a height of 2.5 meters, and is made of PP material to reduce costs.

[0053] Nozzle 22 is a single-layer hollow cone nozzle (model: HC-10) with a spray pressure of 0.3 MPa.

[0054] The filler 28 uses stepped rings (material: PP) and is laid at a height of 1 meter.

[0055] The cooling water temperature is 5-10℃.

[0056] Liquid ethyl xanthate containing free carbon disulfide (carbon disulfide content 2.0%) was delivered to aeration tank 1 at a flow rate of 5 m³ / h. The vacuum degree of aeration tank 1 was set to -0.03 MPa. After the liquid delivery was completed, the degassing time was 50 minutes.

[0057] When the carbon disulfide concentration in anhydrous ethanol reaches 40%, the anhydrous ethanol is discharged and reused.

[0058] After the exhaust gas is treated by the exhaust gas treatment system (alkaline spray tower, NaOH solution concentration 15%), the emission concentration is less than 10 mg / m³ (compliant with GB 31571-2015 standard).

[0059] Performance verification: Carbon disulfide removal rate ≥75% (carbon disulfide content in finished solution ≤0.50%).

Claims

1. A system for efficiently removing free carbon disulfide from liquid ethyl xanthate, characterized in that: It includes an aeration tank (1), a vacuum system (3), and an absorption tank (2) connected in sequence. The aeration tank (1) is provided with an inlet pipe (4), an outlet pipe (5) and a first drain pipe (7). The outlet pipe (5) is connected to the air inlet end (6) of the vacuum system. The aeration tank (1) is provided with a spray pipe (21). The spray pipe (21) is close to the top of the aeration tank (1). The spray pipe (21) is connected to the inlet pipe (4). The spray pipe (21) is provided with multiple nozzles (22). The first drain pipe (7) is provided with a first valve (33). The absorption tank (2) is equipped with an inlet pipe (13), an exhaust pipe (18), an ethanol pipe (30), and a second drain pipe (14). The inlet pipe (13) is connected to the outlet end (12) of the vacuum system. The ethanol pipe (30) is connected to the ethanol feeding system. The second drain pipe (14) is equipped with a second valve (32). The absorption tank (2) is equipped with a first gas distribution pipe (29), which is connected to the inlet pipe (13).

2. The system for efficiently removing free carbon disulfide from liquid ethyl xanthate according to claim 1, characterized in that: It also includes a nitrogen main pipe (9), which is connected to two nitrogen branch pipes (10). The gas aeration tank (1) is equipped with a second gas distribution pipe (23) and a third gas distribution pipe (24). The second gas distribution pipe (23) is set vertically, and the third gas distribution pipe (24) is set horizontally. The second gas distribution pipe (23) and the third gas distribution pipe (24) are respectively connected to the two nitrogen branch pipes (10).

3. The system for efficiently removing free carbon disulfide from liquid ethyl xanthate according to claim 1, characterized in that: The air outlet pipe (5) is located at the top of the air aeration tank (1), and a baffle plate (25) is provided below the air outlet pipe (5).

4. The system for efficiently removing free carbon disulfide from liquid ethyl xanthate according to claim 1, characterized in that: The first drain pipe (7) is connected to the xanthate storage tank via the discharge shield pump (8).

5. The system for efficiently removing free carbon disulfide from liquid ethyl xanthate according to claim 1, characterized in that: The aeration tank (1) is equipped with a first pressure monitoring device (20).

6. A system for efficiently removing free carbon disulfide from liquid ethyl xanthate according to any one of claims 1-5, characterized in that: It also includes a material holding grid (26), which is located above the first air distribution pipe (29) and is equipped with filler (28).

7. A system for efficiently removing free carbon disulfide from liquid ethyl xanthate according to any one of claims 1-5, characterized in that: The second drain pipe (14) is connected to the reactor via a pneumatic diaphragm pump (15).

8. A system for efficiently removing free carbon disulfide from liquid ethyl xanthate according to any one of claims 1-5, characterized in that: The absorption tank (2) is equipped with a second pressure monitoring device (17) and a temperature detection device (16).

9. A system for efficiently removing free carbon disulfide from liquid ethyl xanthate according to any one of claims 1-5, characterized in that: The outer wall of the absorption tank (2) is wrapped with a cooling bypass pipe (19), which is connected to the cooling unit.

10. A method for efficiently removing free carbon disulfide from liquid ethyl xanthate, characterized in that: A system for efficiently removing free carbon disulfide from liquid ethyl xanthate according to any one of claims 1-9 includes the following steps: A. Turn on the vacuum system (3) to give the gas aeration tank (1) a vacuum degree; B. Add anhydrous ethanol into the absorption tank (2) through the ethanol pipe (30) so that the anhydrous ethanol covers the packing (28). C. Liquid ethyl xanthate containing free carbon disulfide is injected into the spray pipe (21) through the inlet pipe (4). Liquid ethyl xanthate is sprayed into the aeration tank (1) through the nozzle (22). During the process of liquid ethyl xanthate dripping, the free carbon disulfide in it is removed. D. The gas phase containing carbon disulfide vapor in the aeration tank (1) passes through the outlet pipe (5), vacuum system (3), and inlet pipe (13) in sequence into the absorption tank (2), and is distributed in anhydrous ethanol through the first gas distribution pipe (29). The carbon disulfide is absorbed by the anhydrous ethanol, thereby recovering the carbon disulfide. The gas phase is discharged from the tail gas pipe (18). E. Open the first valve (33), and the liquid ethyl xanthate collected in the aeration tank (1) is discharged through the first drain pipe (7); F. After a period of operation, open the second valve (32) and the anhydrous ethanol that has absorbed carbon disulfide is discharged through the second drain pipe (14).

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