Device and method for treating wastewater containing easily decomposable ammonium salt

Abstract

The invention discloses a device and method for treating wastewater containing easily decomposable ammonium salts, the device comprises a reboiler, a rectification device, an internal reflux condenser, a feed preheater, a reaction crystallization device, a mother liquor temporary storage tank and a reflux preheater, the upper end of the reboiler is connected to the rectification device and the internal reflux condenser in sequence, the gas outlet of the internal reflux condenser is connected to the reaction crystallization device through a gas outlet pipe, the discharge port of the reaction crystallization device is connected with a solid-liquid separation device, the mother liquor outlet of the solid-liquid separation device is connected with the mother liquor temporary storage tank, the discharge port of the mother liquor temporary storage tank is respectively connected with the feed product of the reaction crystallization device and the feed port of the reflux preheater through a forced reflux pump, the discharge port of the reflux preheater is connected with the reflux port of the rectification device, and the discharge port of the reboiler is connected with a water outlet delivery pump. The invention is simple, effective, energy-saving, and can treat wastewater containing easily decomposable ammonium salts without generating new pollutants.

Description

Technical Field

[0001] The invention relates to the technical field of wastewater treatment, and in particular to a device and a method for treating wastewater containing easily decomposable ammonium salt. Background Art

[0002] Easily decomposable ammonium salts are widely used in chemical production processes, and a considerable amount of easily decomposable ammonium salts are also produced in some chemical production processes. Due to the characteristics of their own chemical properties, they are very easy to decompose into gas. The decomposed gas has a serious impact on the atmosphere, so it must be absorbed by water. However, the wastewater generated after water absorption will also have a serious impact on the water body.

[0003] At present, conventional treatment methods are difficult to effectively treat them, or new pollutants are generated during the treatment process. Summary of the invention

[0004] In view of the above problems, the present invention provides a simple and convenient device for treating wastewater containing easily decomposable ammonium salts, and provides a method for using the device.

[0005] To achieve the above objectives, the present invention adopts the following scheme:

[0006] A device for treating wastewater containing easily decomposable ammonium salts comprises a reboiler, a rectification device, an internal reflux condenser, a feed preheater, a reaction crystallization device, a mother liquid temporary storage tank and a reflux preheater. The upper end of the reboiler is connected to the rectification device and the internal reflux condenser in sequence. The gas outlet of the internal reflux condenser is connected to the reaction crystallization device through an outlet pipe. The discharge port of the reaction crystallization device is connected to a solid-liquid separation device. The mother liquid outlet of the solid-liquid separation device is connected to the mother liquid temporary storage tank. The discharge port of the mother liquid temporary storage tank is respectively connected to the feed product of the reaction crystallization device and the feed port of the reflux preheater through a forced reflux pump. The discharge port of the reflux preheater is connected to the reflux port of the rectification device. The discharge port of the reboiler is connected to a water outlet delivery pump. The outlet of the water outlet delivery pump is connected to the hot water inlet of the feed preheater. The feed port of the feed preheater is connected to the outlet of the feed delivery pump. The discharge port of the feed preheater is connected to the feed port of the rectification device.

[0007] Furthermore, the reboiler is a kettle reboiler.

[0008] Furthermore, the distillation equipment includes an ultra-gravity distillation tower and a distillation tower composed of a plate tower and a packed tower.

[0009] Furthermore, the internal reflux condenser uses 55-60°C hot water as a refrigerant.

[0010] Furthermore, the air outlet pipe is provided with a heating device, and the temperature in the air outlet pipe is higher than 60°C.

[0011] Furthermore, the reaction crystallization equipment is a reactor with a cooling system and a material stirring system.

[0012] Furthermore, the exhaust port of the reaction crystallization equipment is connected to a tail gas absorption system.

[0013] A method for treating wastewater containing easily decomposable ammonium salts comprises the following steps:

[0014] Step 1: Use the heat tracing device of the outlet pipe to heat the outlet pipe to ensure that the temperature inside the outlet pipe is greater than 60°C;

[0015] Step 2: Pass hot water at 55-60° C. into the internal reflux condenser on the distillation equipment;

[0016] Step 3, introducing steam into the reboiler to start heating, while introducing cooling water into the reaction crystallization equipment and starting stirring;

[0017] Step 4: When the outlet temperature of the internal reflux condenser at the top of the distillation equipment reaches 60°C, the reflux preheater is turned on to introduce steam, and the forced reflux pump is turned on to continuously feed the material in the mother liquor temporary storage tank into the reflux port of the distillation equipment;

[0018] Step 5: When the distillation equipment runs stably, start the feed delivery pump to feed the feed preheater; at the same time, start the effluent delivery pump, and the wastewater enters the feed inlet of the distillation equipment after preheating, and the qualified water is sent to the subsequent treatment after heat exchange;

[0019] Step six, placing the material in the reaction crystallization equipment into a solid-liquid separation equipment for solid-liquid separation, the separated recovered ammonium salt is packaged for standby use, and the separated mother liquor enters a mother liquor temporary storage tank.

[0020] Furthermore, after each discharge of the reaction crystallization device in step 6, part of the material in the mother liquor temporary storage tank needs to be transferred to the reaction crystallization device by a forced reflux pump to ensure the stirring effect of the material in the reaction crystallization device.

[0021] Furthermore, in step 4, the outlet temperature of the internal reflux condenser is controlled to be maintained at 60-90° C. by adjusting the steam volume of the reboiler, the flow rate of the feed delivery pump, and the flow rate and temperature of the refrigerant of the internal reflux condenser.

[0022] Furthermore, the temperature in the reaction crystallization equipment is controlled at 0-25°C.

[0023] Furthermore, the temperature in the reboiler is controlled at 100-110°C.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The present invention controls the distillation conditions to decompose the easily decomposable ammonium salt in the distillation equipment, the water after the ammonium salt is removed falls into the reboiler, and then is transferred out through the water outlet delivery pump, the decomposed gas is enriched at the gas outlet of the distillation equipment, the enriched gas is introduced into the reaction crystallization equipment, the decomposed gas is reacted again to generate ammonium salt, the newly generated ammonium salt is recovered through the solid-liquid separation device, and the mother liquor is refluxed into the distillation equipment. The present invention is simple, effective, energy-saving, and can treat wastewater containing easily decomposable ammonium salt without generating new pollutants. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a structural schematic diagram of the present invention;

[0027] In the figure: 1-reboiler, 2-distillation equipment, 3-internal reflux condenser, 4-gas outlet pipe, 5-feed preheater, 6-reaction crystallization equipment, 7-mother liquor temporary storage tank, 8-water outlet delivery pump, 9-forced reflux pump, 10-solid-liquid separation equipment, 11-reflux preheater, 12-feed delivery pump. DETAILED DESCRIPTION

[0028] The technical solution of the present invention is described in more detail below in conjunction with specific implementations and drawings.

[0029] Example 1

[0030] Please refer to Figure 1, an apparatus for treating wastewater containing easily decomposable ammonium salts, comprising a reboiler 1, a distillation device 2, an internal reflux condenser 3, a feed preheater 5, a reaction crystallization device 6, a mother liquor temporary storage tank 7 and a reflux preheater 11. The reboiler 1 is a kettle reboiler. In the actual production process, intermittent distillation is sometimes required. The kettle reboiler is used in the present invention to prevent the U-shaped tube of the split reboiler from being blocked by ammonium salt during intermittent distillation operation; the upper end of the reboiler 1 is connected to the distillation equipment 2 and the internal reflux condenser 3 in sequence, and the distillation equipment 2 includes a supergravity distillation tower and a distillation tower composed of a plate tower and a packed tower. The internal reflux condenser 3 uses 55-60°C hot water as a refrigerant. The decomposition products of the easily decomposable ammonium salt will condense into solids below 58°C. Using 55-60°C hot water as a refrigerant can prevent the ammonium salt from condensing and clogging in the internal reflux condenser 3, and the use of the internal reflux condenser 3 eliminates the reflux pipe, preventing the ammonium salt from condensing and clogging in the reflux pipe. The outlet of the internal reflux condenser 3 is connected to the reaction crystallization device 6 through the outlet pipe 4. The outlet pipe 4 is provided with a heating device. The temperature in the outlet pipe 4 is higher than 60°C to prevent the ammonium salt from condensing and blocking in the outlet pipe 4. The reaction crystallization device 6 is a reactor with a cooling system and a material stirring system. The reaction crystallization device 6 is used as a secondary condenser of the distillation system, and the internal reflux condenser 3 is a primary condenser. Based on the particularity of the material, the reaction crystallization device 6 needs to have the functions of cooling and stirring at the same time. The discharge port of the reaction crystallization device 6 is connected to the solid-liquid separation device 10. The exhaust port of the reaction crystallization device 6 is connected to the tail gas absorption system. The mother liquid outlet of the solid-liquid separation device 10 is connected to the mother liquid temporary storage tank 7. The solid-liquid separation device 10 is a conventional device that can be used to separate solids and liquids. The discharge port of the mother liquid temporary storage tank 7 is connected to the feed product of the reaction crystallization device 6 and the feed port of the reflux preheater 11 through a forced reflux pump 9, and the mother liquid temporary storage tank 7 is a commonly used liquid storage tank. The discharge port of the reflux preheater 11 is connected to the reflux port of the distillation equipment 2, the discharge port of the reboiler 1 is connected to the outlet water delivery pump 8, the outlet of the outlet water delivery pump 8 is connected to the hot water inlet of the feed preheater 5, the feed port of the feed preheater 5 is connected to the outlet of the feed delivery pump 12, and the discharge port of the feed preheater 5 is connected to the feed port of the distillation equipment 2.

[0031] A method for treating wastewater containing easily decomposable ammonium salts comprises the following steps:

[0032] Step 1: Use the heating device of the air outlet pipe 4 to heat the air outlet pipe 4 to ensure that the temperature inside the air outlet pipe 4 is greater than 60° C.

[0033] Step 2: Pass 55° C. hot water into the internal reflux condenser 3 on the distillation equipment 2;

[0034] Step 3, steam is introduced into the reboiler 1 to start heating, and the temperature in the reboiler 1 is controlled at 100° C. to ensure that the residual ammonium salt content in the water is less than 0.1%, and cooling water is introduced into the reaction crystallization device 6 and stirring is started, and the temperature in the reaction crystallization device 6 is controlled at 0° C.;

[0035] Step 4, control the outlet temperature of the internal reflux condenser 3 to maintain 60°C by adjusting the steam volume of the reboiler 1, the flow rate of the feed delivery pump 12, and the flow rate and temperature of the refrigerant of the internal reflux condenser 3. Below 58°C, the ammonium salt will block the outlet; above 90°C, the concentration of the evaporated ammonium salt is too low to precipitate solids; when the outlet temperature of the internal reflux condenser 3 at the top of the distillation equipment 2 reaches 60°C, open the reflux preheater 11 to pass steam, and open the forced reflux pump 9 to continuously feed the material in the mother liquor temporary storage tank 7 into the reflux port of the distillation equipment 2;

[0036] Step five, when the distillation equipment 2 runs stably, start the feed delivery pump 12 to feed the feed preheater 5; at the same time, start the water outlet delivery pump 8, the waste water enters the feed port of the distillation equipment 2 after preheating, and the qualified water goes to subsequent treatment after heat exchange; the feed preheater 5 uses the qualified treated water as a heat source, which can effectively reduce the energy consumption of the system.

[0037] Step 6, as the distillation proceeds, the amount of ammonium salt crystallized in the reaction crystallization device 6 gradually increases. When there are more materials, the materials in the reaction crystallization device 6 are placed in the solid-liquid separation device 10 for solid-liquid separation, the separated recovered ammonium salt is packaged for standby use, and the separated mother liquor enters the mother liquor temporary storage tank 7. After each discharge of the reaction crystallization device 6, part of the materials in the mother liquor temporary storage tank 7 need to be transferred to the reaction crystallization device 6 by the forced reflux pump 9 to ensure the stirring effect of the materials in the reaction crystallization device 6.

[0038] Example 2

[0039] Please refer to Figure 1 , an apparatus for treating wastewater containing easily decomposable ammonium salts is the same as that in Example 1.

[0040] A method for treating wastewater containing easily decomposable ammonium salts comprises the following steps:

[0041] Step 1: Use the heating device of the air outlet pipe 4 to heat the air outlet pipe 4 to ensure that the temperature inside the air outlet pipe 4 is greater than 60° C.

[0042] Step 2: introducing hot water at 58° C. into the internal reflux condenser 3 on the distillation equipment 2;

[0043] Step 3, steam is introduced into the reboiler 1 to start heating, and the temperature in the reboiler 1 is controlled at 105° C. to ensure that the residual ammonium salt content in the water is less than 0.1%, and cooling water is introduced into the reaction crystallization device 6 and stirring is started, and the temperature in the reaction crystallization device 6 is controlled at 12° C.;

[0044] Step 4, control the outlet temperature of the internal reflux condenser 3 to maintain 75°C by adjusting the steam volume of the reboiler 1, the flow rate of the feed delivery pump 12, and the flow rate and temperature of the refrigerant of the internal reflux condenser 3. Below 58°C, the ammonium salt will block the outlet; above 90°C, the concentration of the evaporated ammonium salt is too low to precipitate solids; when the outlet temperature of the internal reflux condenser 3 at the top of the distillation equipment 2 reaches 60°C, open the reflux preheater 11 to pass steam, and open the forced reflux pump 9 to continuously feed the material in the mother liquor temporary storage tank 7 into the reflux port of the distillation equipment 2;

[0045] Step five, when the distillation equipment 2 runs stably, start the feed delivery pump 12 to feed the feed preheater 5; at the same time, start the water outlet delivery pump 8, the waste water enters the feed port of the distillation equipment 2 after preheating, and the qualified water goes to subsequent treatment after heat exchange; the feed preheater 5 uses the qualified treated water as a heat source, which can effectively reduce the energy consumption of the system.

[0046] Step 6, as the distillation proceeds, the amount of ammonium salt crystallized in the reaction crystallization device 6 gradually increases. When there are more materials, the materials in the reaction crystallization device 6 are placed in the solid-liquid separation device 10 for solid-liquid separation, the separated recovered ammonium salt is packaged for standby use, and the separated mother liquor enters the mother liquor temporary storage tank 7. After each discharge of the reaction crystallization device 6, part of the materials in the mother liquor temporary storage tank 7 need to be transferred to the reaction crystallization device 6 by the forced reflux pump 9 to ensure the stirring effect of the materials in the reaction crystallization device 6.

[0047] Example 3

[0048] Please refer to Figure 1 , an apparatus for treating wastewater containing easily decomposable ammonium salts is the same as that in Example 1.

[0049] A method for treating wastewater containing easily decomposable ammonium salts comprises the following steps:

[0050] Step 1: Use the heating device of the air outlet pipe 4 to heat the air outlet pipe 4 to ensure that the temperature inside the air outlet pipe 4 is greater than 60° C.

[0051] Step 2: Pass 60° C. hot water into the internal reflux condenser 3 on the distillation equipment 2;

[0052] Step 3, steam is introduced into the reboiler 1 to start heating, and the temperature in the reboiler 1 is controlled at 110° C. to ensure that the residual ammonium salt content in the water is less than 0.1%, and cooling water is introduced into the reaction crystallization device 6 and stirring is started, and the temperature in the reaction crystallization device 6 is controlled at 25° C.;

[0053] Step 4, control the outlet temperature of the internal reflux condenser 3 to maintain 90°C by adjusting the steam volume of the reboiler 1, the flow rate of the feed delivery pump 12, and the flow rate and temperature of the refrigerant of the internal reflux condenser 3. If the temperature is lower than 58°C, the ammonium salt will block the outlet; if the temperature is higher than 90°C, the concentration of the evaporated ammonium salt is too low to precipitate solids; when the outlet temperature of the internal reflux condenser 3 at the top of the distillation equipment 2 reaches 60°C, turn on the reflux preheater 11 to pass steam, and turn on the forced reflux pump 9 to continuously feed the material in the mother liquor temporary storage tank 7 into the reflux port of the distillation equipment 2;

[0054] Step five, when the distillation equipment 2 runs stably, start the feed delivery pump 12 to feed the feed preheater 5; at the same time, start the water outlet delivery pump 8, the waste water enters the feed port of the distillation equipment 2 after preheating, and the qualified water goes to subsequent treatment after heat exchange; the feed preheater 5 uses the qualified treated water as a heat source, which can effectively reduce the energy consumption of the system.

[0055] Step 6, as the distillation proceeds, the amount of ammonium salt crystallized in the reaction crystallization device 6 gradually increases. When there are more materials, the materials in the reaction crystallization device 6 are placed in the solid-liquid separation device 10 for solid-liquid separation, the separated recovered ammonium salt is packaged for standby use, and the separated mother liquor enters the mother liquor temporary storage tank 7. After each discharge of the reaction crystallization device 6, part of the materials in the mother liquor temporary storage tank 7 need to be transferred to the reaction crystallization device 6 by the forced reflux pump 9 to ensure the stirring effect of the materials in the reaction crystallization device 6.

Claims

1. A device for treating wastewater containing easily decomposable ammonium salts, characterized in that: The invention comprises a reboiler (1), a distillation device (2), an internal reflux condenser (3), a feed preheater (5), a reaction crystallization device (6), a mother liquid temporary storage tank (7) and a reflux preheater (11), wherein the upper end of the reboiler (1) is connected to the distillation device (2) and the internal reflux condenser (3) in sequence, the gas outlet of the internal reflux condenser (3) is connected to the reaction crystallization device (6) through a gas outlet pipe (4), the discharge port of the reaction crystallization device (6) is connected to a solid-liquid separation device (10), the mother liquid outlet of the solid-liquid separation device (10) is connected to the mother liquid temporary storage tank (7), and the discharge port of the mother liquid temporary storage tank (7) is connected to the mother liquid temporary storage tank (7) through a forced reflux pump. (9) are respectively connected to the feed of the reaction crystallization device (6) and the feed port of the reflux preheater (11), the discharge port of the reflux preheater (11) is connected to the reflux port of the distillation device (2), the discharge port of the reboiler (1) is connected to a water outlet pump (8), the outlet of the water outlet pump (8) is connected to the hot water inlet of the feed preheater (5), the feed port of the feed preheater (5) is connected to the outlet of the feed delivery pump (12), the discharge port of the feed preheater (5) is connected to the feed port of the distillation device (2), the reboiler (1) is a kettle reboiler, and the distillation device (2) includes an ultra-gravity distillation tower and a distillation tower composed of a plate tower and a packed tower.

2. The device for treating wastewater containing easily decomposable ammonium salts according to claim 1, characterized in that: The internal reflux condenser (3) uses hot water at 55-60°C as a refrigerant.

3. The device for treating wastewater containing easily decomposable ammonium salts according to claim 1, characterized in that: The air outlet pipe (4) is provided with a heating device, and the temperature inside the air outlet pipe (4) is higher than 60°C.

4. The equipment for treating wastewater containing easily decomposable ammonium salts according to claim 1, characterized in that: The reaction crystallization equipment (6) is a reactor with a cooling system and a material stirring system.

5. The equipment for treating wastewater containing easily decomposable ammonium salts according to claim 1, characterized in that: The exhaust port of the reaction crystallization equipment (6) is connected to the tail gas absorption system.

6. A method for treating wastewater containing easily decomposable ammonium salts as claimed in any one of claims 1 to 5, characterized in that: The steps include: Step 1: using a heating device of the air outlet pipe (4) to heat the air outlet pipe (4) to ensure that the temperature inside the air outlet pipe (4) is greater than 60° C.; Step 2: introducing hot water at 55-60° C. into the internal reflux condenser (3) on the distillation equipment (2); Step 3, steam is introduced into the reboiler (1) to start heating, and cooling water is introduced into the reaction crystallization device (6) and stirring is started; Step 4: When the outlet temperature of the internal reflux condenser (3) at the top of the distillation equipment (2) reaches 60° C., the reflux preheater (11) is turned on to introduce steam, and the forced reflux pump (9) is turned on to continuously feed the material in the mother liquid temporary storage tank (7) into the reflux port of the distillation equipment (2); Step 5, when the distillation equipment (2) runs stably, the feed delivery pump (12) is turned on to feed the feed preheater (5); at the same time, the effluent delivery pump (8) is turned on, and the wastewater enters the feed inlet of the distillation equipment (2) after being preheated, and the qualified water is sent to the subsequent treatment after heat exchange; Step six, placing the material in the reaction crystallization device (6) into the solid-liquid separation device (10) for solid-liquid separation, the separated recovered ammonium salt is packaged for standby use, and the separated mother liquor enters the mother liquor temporary storage tank (7).

7. The method for treating wastewater containing easily decomposable ammonium salts according to claim 6, characterized in that: In the step 6, after each discharge of the reaction crystallization device (6), part of the material in the mother liquid temporary storage tank (7) needs to be transferred into the reaction crystallization device (6) by a forced reflux pump (9) to ensure the stirring effect of the material in the reaction crystallization device (6).

8. The method for treating wastewater containing easily decomposable ammonium salts according to claim 6, characterized in that: In the step 4, the outlet temperature of the internal reflux condenser (3) is controlled to be maintained at 60-90°C by adjusting the steam volume of the reboiler (1), the flow rate of the feed delivery pump (12) and the flow rate and temperature of the refrigerant of the internal reflux condenser (3).

9. The method for treating wastewater containing easily decomposable ammonium salt according to claim 6, characterized in that: The temperature in the reaction crystallization device (6) is controlled at 0-25°C.

10. The method for treating wastewater containing easily decomposable ammonium salts according to claim 6, characterized in that: The temperature in the reboiler (1) is controlled at 100-110°C.

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