Equipment and method for treating high-salinity wastewater generated in production of L-carnitine

Abstract

The invention discloses L-carnitine production high-salinity wastewater treatment equipment which is characterized in that a feeding pump is connected with a first-effect evaporator, an external steam control valve is connected with the first-effect evaporator, a first pressure gauge is mounted at the input end or the output end of the external steam control valve, and the output end of the first-effect evaporator is connected with the input end of a second-effect evaporator; the system further comprises a wiped-film evaporator, a condensing unit and a vacuumizing unit, the wiped-film evaporator is provided with a plurality of input ends and a plurality of output ends, and the input ends of the wiped-film evaporator are connected with the output end of the second-effect evaporator; the input end of the condenser is connected with the first output end of the wiped-film evaporator, and the cooling liquid input control valve and the cooling liquid output control valve are respectively connected with the condenser; the output end of the condenser is connected with one end of the adjusting valve through a third pipeline, the other end of the adjusting valve is connected with the vacuum pump, and the second pressure gauge is connected with the third pipeline. According to the invention, energy consumption and cost can be reduced.

Description

Technical Field

[0001] The invention relates to the technical field of L-carnitine production, and in particular to equipment and a method for treating high-salt wastewater produced by L-carnitine production. Background Art

[0002] L-carnitine is widely used in functional beverages, animal feed, pharmaceuticals, and other fields. The market is huge and growing at over 5% annually. The main industrial preparation method for L-carnitine is: S-epichlorohydrin is reacted with trimethylamine hydrochloride to produce L-(-)-2-hydroxypropyltrimethylammonium chloride through a ring-opening reaction. This is then reacted with sodium cyanide to produce L-(-)-3-cyano-2-hydroxypropyltrimethylammonium chloride. This is then hydrolyzed with concentrated hydrochloric acid to produce L-(-)-3-carboxy-2-hydroxypropyltrimethylammonium chloride. Finally, the chloride ions are removed through an anion exchange resin to produce L-carnitine.

[0003] The production process generates large amounts of high-salt wastewater with concentrations of 5-15% sodium chloride and 5-15% ammonium chloride. According to production statistics, every ton of L-carnitine produced generates approximately 15 tons of high-salt wastewater. This high-salt wastewater dehydrates and kills the biochemical microorganisms involved in environmental treatment, making environmental biochemical treatment impossible, thus creating serious environmental problems.

[0004] Currently, distillation and crystallization are the primary methods used to treat high-salinity wastewater in L-carnitine production. As water evaporates from high-salinity wastewater, its salt concentration increases. Once the saturation concentration is exceeded, the salt crystals precipitate. The evaporated water can then be condensed and recycled, achieving environmentally friendly treatment. Triple-effect evaporators or MVR evaporators are commonly used to treat high-salinity wastewater in industrial production. The principles of these two devices are as follows.

[0005] The principle of a triple-effect evaporator is to utilize the latent heat of steam for multi-stage evaporation. The specific process is as follows: The material in the first-effect heating chamber is heated to boiling by external steam, then passes through the first-effect separation chamber to generate and separate secondary steam. The secondary steam enters the second-effect heating chamber, where it serves as a heat source to further heat the material, and then passes through the second-effect separation chamber to generate and separate tertiary steam. The tertiary steam enters the third-effect heating chamber, where it serves as a heat source to further heat the material, and then passes through the third-effect separation chamber to generate and separate quaternary steam, which is condensed into water through a condenser. Finally, the concentrated liquid crystallizes to precipitate salts. Advantages of this equipment include low cost, mature technology, stable operation, low failure rate, and easy maintenance. However, its disadvantages in treating L-carnitine-rich wastewater include the need for a circulating pump for material circulation in each evaporator, which increases energy consumption. The high-salinity wastewater generated during L-carnitine production is high in concentration and spreads widely, leading to premature precipitation of inorganic salts in the three-effect heating and separation chambers, which can cause blockage. This is particularly true when evaporating wastewater containing ammonium chloride, where the agglomeration of ammonium chloride can easily lead to blockage. This affects the operation of the equipment and thus the production progress of L-carnitine.

[0006] The principle of an MVR evaporator is that the material is first heated and evaporated in a heater using external steam, generating secondary steam. This secondary steam is then compressed by a compressor, increasing its pressure and temperature, and its thermal enthalpy. The compressed steam is separated by a separator, and the condensed water enters the preheater. The uncondensed steam re-enters the heating chamber of the heater, serving as a heat source to further heat the material. The concentrated liquid at the bottom crystallizes and precipitates salt. Advantages of this equipment include a small footprint, high degree of automation, and low energy consumption, requiring only a small amount of external steam. Disadvantages include high equipment price and high compressor power consumption. MVR equipment is approximately three times more expensive than a triple-effect evaporator with the same hourly evaporation capacity. The compressor is susceptible to damage due to prolonged operation at high temperatures and pressures, resulting in high maintenance costs. A major disadvantage of treating L-carnitine-rich wastewater is the high concentration of ammonium chloride produced by L-carnitine. This creates the risk of ammonium chloride agglomeration in the heater and separator, leading to equipment blockage. Once the agglomerated salt is drawn into the compressor, it can cause compressor seizure and damage. Summary of the Invention

[0007] The present invention provides equipment and a method for treating high-salt wastewater in L-carnitine production, which can reduce energy consumption and cost.

[0008] The technical solutions to the above problems are as follows:

[0009] L-carnitine production high-salt wastewater treatment equipment includes an external steam control valve, a first pressure gauge, a first-effect evaporator, a second-effect evaporator, and a feed pump for conveying high-salt wastewater, wherein the feed pump is connected to the first-effect evaporator, the external steam control valve is connected to the first-effect evaporator, the first pressure gauge is installed at the input end or the output end of the external steam control valve, the output end of the first-effect evaporator is connected to the input end of the second-effect evaporator, and the equipment also includes a wiped film evaporator, a condensing unit, and a vacuum unit. The wiped film evaporator has multiple input ends and multiple output ends, and the input end of the wiped film evaporator is connected to the output end of the second-effect evaporator.

[0010] The condensing unit includes a condenser, a coolant input control valve, and a coolant output control valve. The input end of the condenser is connected to the first output end of the scraped film evaporator. The coolant input control valve and the coolant output control valve are respectively connected to the condenser.

[0011] The vacuum unit includes a regulating valve, a third pipeline, a second pressure gauge, and a vacuum pump. The output end of the condenser is connected to one end of the regulating valve through the third pipeline, the other end of the regulating valve is connected to the vacuum pump, and the second pressure gauge is connected to the third pipeline.

[0012] The method for treating high-salt wastewater produced by L-carnitine production adopts high-salt wastewater treatment equipment produced by L-carnitine production, comprising the following steps:

[0013] S1, turn on the vacuum pump and regulating valve. When the reading on the second pressure gauge is -0.05 to -0.098 MPa, open the coolant input control valve and the coolant output control valve to start the wiped film evaporator.

[0014] S2, open the external steam control valve to preheat the equipment;

[0015] S3, when the reading on the first pressure gauge is 0.3-0.5Mpa, the feed pump is started, and the feed pump inputs the high-salt wastewater into the first-effect evaporator. The high-salt wastewater is continuously heated and evaporated by external steam during the downward movement due to the pressure difference in the first-effect evaporator. The primary steam generated in the first-effect evaporator is output to the second-effect evaporator to heat the second-effect evaporator. The high-salt wastewater evaporated in the first-effect evaporator enters the second-effect evaporator under the action of the pressure difference to continue evaporation and generate secondary steam;

[0016] S4, the secondary steam in the second-effect evaporator enters the scraped film evaporator and heats the scraped film evaporator. The high-salt wastewater after evaporation at the bottom of the second-effect evaporator enters the scraped film evaporator under the action of pressure difference and continues to be heated and evaporated. The salt produced in the scraped film evaporator is discharged from the second output end of the scraped film evaporator.

[0017] The present invention maintains the internal pressure difference of the equipment by means of vacuum pumping, and interlocks and controls the feed pump, electric valve and steam supply valve through a specific gravity tester. During the distillation process, the opening of the external steam control valve and the electric valve are adjusted according to the real-time test of the specific gravity of the wastewater, so that the high-salt wastewater entering the equipment can reach the node where the salt is just precipitated in the subsequent scraped film evaporator, thereby ensuring that the equipment maintains efficient operation and saves operating costs.

[0018] The first two effects of the evaporator in this invention utilize a falling-film evaporator. High-salt wastewater enters the evaporator from the top, where it is gradually heated and evaporated by the pressure differential during its descent. This eliminates the need for an external circulation pump, saving equipment investment and maintenance costs. The final effect utilizes a wiped-film evaporator. The scraper within the scraper rotates continuously, driven by a drive motor, and the salt precipitated within the scraper is discharged from the bottom, preventing equipment blockage caused by salt agglomeration. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Schematic diagram of the high-salt wastewater treatment equipment for L-carnitine production.

[0020] Figure 2 This is the structural diagram of the wiped film evaporator.

[0021] Figure 3 for Figure 2 Enlarged view of the P part in the figure. DETAILED DESCRIPTION

[0022] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0023] like Figures 1 to 3 As shown, the L-carnitine production high-salt wastewater treatment equipment of the present invention includes an external steam control valve 1, a first pressure gauge P1, a first-effect evaporator A, a second-effect evaporator B, a feed pump H for conveying high-salt wastewater, a wiped film evaporator C, a condensing unit, and a vacuum unit. The following is a detailed description of each part and the relationship between them.

[0024] A feed pump H is connected to a high-salt wastewater tank FS, which is also connected to a first-effect evaporator A. The input of an external steam control valve 1 is connected to a steam supply device. External steam control valve 1 is connected to the first-effect evaporator A. External steam control valve 1 is preferably an electric valve. A first pressure gauge P1 is installed at the input or output of external steam control valve 1. The output of the first-effect evaporator A is connected to the input of the second-effect evaporator B. The wiped-film evaporator C has multiple inputs and multiple outputs, and the input of the wiped-film evaporator C is connected to the output of the second-effect evaporator B.

[0025] In this embodiment, both the first-effect evaporator A and the second-effect evaporator B preferably employ falling film evaporators, and the first-effect evaporator A is located at a higher height than the second-effect evaporator B. Both the first-effect evaporator A and the second-effect evaporator B have a steam input, a wastewater input, a wastewater output, a steam output, and a condensed water output. The steam input of the first-effect evaporator A is connected to the output of an external steam control valve 1, the wastewater input of the first-effect evaporator A is connected to the output of a feed pump H, the wastewater output of the first-effect evaporator A is connected to the wastewater input of the second-effect evaporator B, the steam output of the first-effect evaporator A is connected to the steam input of the second-effect evaporator B, and the condensed water outputs of the first-effect evaporator A and the second-effect evaporator B are connected to a water collection tank J.

[0026] The scraped film evaporator C in the present invention includes a cylinder 11, a jacket 12, an upper end cover 13, a bracket 14, a reduction motor 15, a stirring shaft 16, a scraper assembly 17, and a lower head 18. The cylinder 11 is hollow and has openings at both ends. The jacket 12 surrounds the cylinder 11 and is fixed to the cylinder 11. A cavity 19 is formed between the jacket 12 and the cylinder. The cylinder 11 is equipped with a first input end 11a for inputting wastewater. The cylinder 11 is also equipped with a first output end 11b for outputting steam in the cylinder. The first input end 11a and the first output end 11b are both located above the jacket 12, and the first output end 11b is located above the first input end 11a. The wastewater output end of the second-effect evaporator B is connected to the first input end 11a of the scraped film evaporator C, and the first output end 11b is connected to the input end of the condenser D. The jacket 12 is provided with a second input end 12a for inputting steam, and the steam output end of the second-effect evaporator B is connected to the second input end 12a of the scraped film evaporator C. The jacket 12 is provided with a third output end 12b, and the third output end 12b of the scraped film evaporator C is connected to the water collection tank J.

[0027] The upper end cover 13 is matched with the upper end opening of the cylinder 11 and fixed to the cylinder 11, the bracket 14 is fixed to the upper end cover 13, and the reduction motor 15 is installed on the bracket 14. The reduction motor 15 consists of a motor and a reducer, and the output end of the motor is connected to the input end of the reducer.

[0028] One end of the stirring shaft 16 is connected to the reduction motor 15, that is, the stirring shaft 16 is connected to the output end of the reducer in the reduction motor 15. The other end of the stirring shaft 16 passes through the upper end cover 13 and enters the cylinder 11 and is connected to a bearing 20. The scraper assembly 17 surrounds the stirring shaft 16 and is fixed to the stirring shaft 16.

[0029] One end of the lower end cap 18 engages with the lower opening of the cylinder 11 and is fixed to the cylinder 11. The other end of the lower end cap 18 is provided with a second output port 18a for discharging solid salt. A support member 21 is mounted between the lower end cap 18 and the cylinder 11. The bearing 20 is mounted on the support member 21. The support member 21 can be a perforated plate or a strip-shaped support plate. The width of the support plate is one-fifth of the inner diameter of the cylinder 11.

[0030] The wiped-film evaporator C also includes a liquid separator, which comprises a base 22. The base 22 is provided with a first through-hole 23 and a second through-hole 24 extending through the axial end surface of the base 22. After the stirring shaft 16 passes through the first through-hole 23, it is secured to the base 22, for example, by welding. Steam generated during evaporation within the cylinder 11 passes through the second through-hole 24 and is ultimately discharged from the first output end 11b.

[0031] A water collecting trough 22a for receiving high-salt wastewater is provided on the circumferential surface of the seat body 22. The water collecting trough 22a is an annular groove. A liquid-throwing trough 25 that passes through the water collecting trough 22a is also provided on the circumferential surface of the seat body 22. The axial direction of the liquid-throwing trough 25 is inclined to the circumferential direction of the seat body 22. After the high-salt wastewater enters the water collecting trough 22a, it is dispersed into each liquid-throwing trough 25. When the stirring shaft 16 rotates, the seat body 22 rotates with the stirring shaft 16. The rotating seat body 22 generates centrifugal force on the high-salt wastewater, and throws the high-salt wastewater toward the inner wall surface of the cylinder 11.

[0032] In order to make the high-salt wastewater be thrown toward the inner wall surface of the cylinder 11 in a centrifugal manner, a gap must be formed between the cylinder 11 and the seat 22. After the conventional first input end 11a is installed on the cylinder 11, there is a gap between the first input end 11a and the cylinder 11. When the high-salt wastewater is sprayed from the first input end 11a into the water collecting tank 22a, since the seat 22 has no restraining effect, as the seat 22 rotates, most of the high-salt wastewater is directly thrown from the water collecting tank 22a to the inner wall surface of the cylinder 11, and only a small amount of high-salt wastewater will flow into the water collecting tank 22a. Therefore, the high-salt wastewater acting on the inner wall surface of the cylinder 11 is uneven.

[0033] In order to overcome the above-mentioned problem of uneven high-salt wastewater acting on the inner wall surface of the cylinder 11, the scraped film evaporator C in the present invention also includes a first baffle 26 and a second baffle 27. The first baffle 26 and the second baffle 27 are both annular. The first baffle 26 and the second baffle 27 are located in the cylinder 11 and are arranged at intervals. One end of the first baffle 26 and the second baffle 27 are fixed to the inner wall surface of the cylinder 11, so that an annular shielding assembly is formed between the first baffle 26 and the second baffle 27 and the cylinder 11, and the annular shielding assembly is respectively cooperated with the first input end 11a and the water collecting tank 22a.

[0034] After the high-salt wastewater is sprayed out from the first input end 11a, the high-salt wastewater enters the water collection tank 22a after passing through the space between the first baffle 26 and the second baffle 27. Due to the shielding effect of the first baffle 26 and the second baffle 27, the high-salt wastewater cannot be directly thrown from the water collection tank 22a to the inner wall surface of the cylinder 11. Therefore, the high-salt wastewater can only flow from the water collection tank 22a to the liquid-throwing tank 25, and finally be thrown from the liquid-throwing tank 25 to the inner wall surface of the cylinder 11. Since the first baffle 26 and the second baffle 27 are both annular, a water storage space is formed between the first baffle 26 and the second baffle 27 and the water collection tank 22a. The liquid that has not been thrown out in time can be filled in the water storage space, and the high-salt wastewater is evenly distributed from the water storage space to each liquid-throwing tank 25, so that the high-salt wastewater thrown to the inner wall surface of the cylinder 11 is also uniform.

[0035] The wiped-film evaporator C also includes a demister located within the barrel 11. The demister comprises a cover 28, a frame 29, and a connecting sleeve 30. The cover 28 is conical and has openings at both ends. One end of the frame 29 is secured to the cover 28, while the other end is secured to the connecting sleeve 30. After the connecting sleeve 30 is mounted and secured to the agitator shaft 16, the demister is positioned above the liquid separator. When high-salinity wastewater evaporates within the barrel 11, it not only produces steam but also some foam. The foam and steam flow upward from bottom to top. After passing through the second through-hole 24, the foam collides with the cover 28 and is intercepted by it. The steam then passes through the cover 28 and is output from the first output end 11b to the condenser D.

[0036] The condensing unit includes a condenser D, a coolant input control valve 5, and a coolant output control valve 4. The input end of the condenser D is connected to the first output end 11b of the scraped film evaporator C, and the coolant input control valve 5 and the coolant output control valve 4 are respectively connected to the condenser D.

[0037] The vacuum unit includes a regulating valve 3, a third pipe G3, a second pressure gauge P2, and a vacuum pump F. The output end of the condenser D is connected to one end of the regulating valve 3 through the third pipe G3, the other end of the regulating valve 3 is connected to the vacuum pump F, and the second pressure gauge P2 is connected to the third pipe G3.

[0038] The present invention further includes a first pipeline G1, an electric valve 2, a second pipeline G2, a specific gravity tester G, and an interlocking control device E. One end of the first pipeline G1 is connected to the output end of the feed pump H, the other end of the first pipeline G1 is connected to one end of the electric valve 2, the other end of the electric valve 2 is connected to the wastewater input end of the first-effect evaporator A, the second-effect evaporator B is connected to the scraped-film evaporator C via the second pipeline G2, the specific gravity tester G is connected to the second pipeline G2, and the interlocking control device E is electrically connected to the electric valve 2 and the specific gravity tester G, respectively. The interlocking control device E preferably employs a PLC controller.

[0039] When the high-salt wastewater in the second-effect evaporator B is input into the scraped-film evaporator C, the wastewater discharged from the second-effect evaporator B is tested by the specific gravity tester G, and the interlocking control device E obtains the test result of the specific gravity tester G. The interlocking control device E controls the opening of the external steam control valve 1 and the electric valve 2 according to the test result of the specific gravity tester G.

[0040] If the value provided by the specific gravity tester G obtained by the interlocking control device E is within the range of 1.13-1.16, the interlocking control device E controls the opening of the external steam control valve 1 and the electric valve 2 to remain unchanged; if the value provided by the specific gravity tester G obtained by the interlocking control device E is greater than 1.16, the interlocking control device E controls the opening of the external steam control valve 1 and the electric valve 2 to increase; if the value provided by the specific gravity tester G obtained by the interlocking control device E is less than 1.13, the interlocking control device E controls the opening of the external steam control valve 1 and the electric valve 2 to decrease.

[0041] The present invention also includes a steam supply valve 6. The input of the steam supply valve 6 is connected in parallel to the input of the external steam control valve 1 and to the steam supply device. The output of the steam supply valve 6 is connected to the wiped-film evaporator C. The output of the steam supply valve 6 is connected to the second input of the wiped-film evaporator C. The steam supply valve 6 is also connected to an interlocking control device E. The steam supply valve 6 is normally closed. If the interlocking control device E obtains a value from the specific gravity meter G that is less than 1.13, the interlocking control device E controls the steam supply valve 6 to open, allowing external steam to be directly supplied to the wiped-film evaporator C to heat the wastewater in the wiped-film evaporator C.

[0042] Example 1

[0043] The method for treating high-salt wastewater from L-carnitine production comprises the following steps:

[0044] S1. Chemical analysis shows that the concentration of sodium chloride wastewater in the high-salt wastewater pool FS is 8%. Turn on the vacuum pump F and the regulating valve 3. When the reading on the second pressure gauge P2 is -0.08MPa, open the coolant input control valve 5 and the coolant output control valve 4, and start the wiped film evaporator C.

[0045] S2, open the external steam control valve 1, and the steam enters the first-effect evaporator A to preheat the equipment.

[0046] In step S3, when the reading on the first pressure gauge P1 reaches 0.4 MPa, feed pump H is started and electric valve 2 is opened. Feed pump H feeds high-salt wastewater with a sodium chloride concentration of 8% from the high-salt wastewater tank FS into the first-effect evaporator A. Due to the pressure differential, the high-salt wastewater is continuously heated and evaporated by external steam as it moves downward within the first-effect evaporator A. Primary steam is generated within the first-effect evaporator A and output to the second-effect evaporator B, which heats the second-effect evaporator B. After evaporation in the first-effect evaporator A, the high-salt wastewater enters the second-effect evaporator B under the pressure differential and continues to evaporate, generating secondary steam. Condensate L generated in the first-effect evaporators A and B is output to the sump J through the condensate output port.

[0047] In step S4, the secondary steam from second-effect evaporator B enters wiped-film evaporator C and heats it. The high-salt wastewater from the bottom of second-effect evaporator B enters wiped-film evaporator C under a pressure differential, where it continues to be heated and evaporated. The salt produced in wiped-film evaporator C is discharged from the second output port of wiped-film evaporator C. When the high-salt wastewater from second-effect evaporator B enters wiped-film evaporator C, the specific gravity meter G indicates that the specific gravity of the high-salt wastewater entering wiped-film evaporator C is 1.14. Therefore, the interlocking control device E controls the openings of external steam control valve 1 and electric valve 2 to remain unchanged. The condensed water L produced in wiped-film evaporator C is output to sump J. The steam produced in wiped-film evaporator C is condensed into water in condenser D and then enters sump J. The sodium chloride waste salt produced at the bottom of wiped-film evaporator C is discharged into a salt collection bag.

[0048] Example 2

[0049] The method for treating high-salt wastewater from L-carnitine production comprises the following steps:

[0050] S1. Chemical analysis shows that the concentration of sodium chloride wastewater in the high-salt wastewater pool FS is 9%. Turn on the vacuum pump F and the regulating valve 3. When the reading on the second pressure gauge P2 is -0.07MPa, open the coolant input control valve 5 and the coolant output control valve 4, and start the wiped film evaporator C.

[0051] S2, open the external steam control valve 1, and the steam enters the first-effect evaporator A to preheat the equipment.

[0052] In step S3, when the reading on the first pressure gauge P1 reaches 0.3 MPa, feed pump H is started and electric valve 2 is opened. Feed pump H feeds high-salt wastewater with a sodium chloride concentration of 9% from the high-salt wastewater tank FS into the first-effect evaporator A. Due to the pressure differential, the high-salt wastewater is continuously heated and evaporated by external steam as it moves downward within the first-effect evaporator A. Primary steam is generated in the first-effect evaporator A and output to the second-effect evaporator B, which heats the second-effect evaporator B. After evaporation in the first-effect evaporator A, the high-salt wastewater enters the second-effect evaporator B due to the pressure differential and continues to evaporate, generating secondary steam. Condensate L generated in the first-effect evaporators A and B is output to the sump J through the condensate output port.

[0053] S4, the secondary steam in the second-effect evaporator B enters the scraped film evaporator C and heats the scraped film evaporator C. The high-salt wastewater after evaporation at the bottom of the second-effect evaporator B enters the scraped film evaporator C under the action of pressure difference and continues to be heated and evaporated. The salt produced in the scraped film evaporator C is discharged from the second output end of the scraped film evaporator C. When the high-salinity wastewater from second-effect evaporator B is fed into wiped-film evaporator C, the specific gravity meter G indicates a specific gravity of 1.17, indicating a high concentration of high-salinity wastewater entering wiped-film evaporator C, namely, a high sodium chloride content. Therefore, interlocking control device E increases the openings of external steam control valve 1 and electric valve 2 by 2.5% from their current values, accelerating the feed rate of the high-salinity wastewater. As treatment continues, when the specific gravity meter G indicates the specific gravity of the high-salinity wastewater entering wiped-film evaporator C falls within the range of 1.13-1.16, interlocking control device E decreases the openings of external steam control valve 1 and electric valve 2 by 1.3% from their current values. Condensate L generated in wiped-film evaporator C is output to sump J. Steam generated in wiped-film evaporator C is condensed into water in condenser D and then enters sump J. The sodium chloride waste salt generated at the bottom of wiped-film evaporator C is discharged into a salt collection bag.

[0054] Example 3

[0055] The method for treating high-salt wastewater from L-carnitine production comprises the following steps:

[0056] S1. Chemical analysis shows that the concentration of sodium chloride wastewater in the high-salt wastewater pool FS is 10%. Turn on the vacuum pump F and the regulating valve 3. When the reading on the second pressure gauge P2 is -0.09 MPa, open the coolant input control valve 5 and the coolant output control valve 4, and start the wiped film evaporator C.

[0057] S2, open the external steam control valve 1, and the steam enters the first-effect evaporator A to preheat the equipment.

[0058] In step S3, when the reading on the first pressure gauge P1 reaches 0.5 MPa, feed pump H is started and electric valve 2 is opened. Feed pump H feeds high-salt wastewater with a sodium chloride concentration of 10% from the high-salt wastewater tank FS into the first-effect evaporator A. Due to the pressure differential, the high-salt wastewater is continuously heated and evaporated by external steam as it moves downward within the first-effect evaporator A. Primary steam is generated in the first-effect evaporator A and output to the second-effect evaporator B, which heats the second-effect evaporator B. After evaporation in the first-effect evaporator A, the high-salt wastewater enters the second-effect evaporator B under the pressure differential and continues to evaporate, generating secondary steam. Condensate L generated in the first-effect evaporators A and the second-effect evaporators B is output to the sump J through the condensate output port.

[0059] In step S4, the secondary steam from the second-effect evaporator B enters the wiped-film evaporator C and heats it. The high-salt wastewater, after evaporation at the bottom of the second-effect evaporator B, enters the wiped-film evaporator C under the pressure differential, where it continues to be heated and evaporated. The salt produced in the wiped-film evaporator C is discharged from the second output port of the wiped-film evaporator C. When the high-salt wastewater from the second-effect evaporator B enters the wiped-film evaporator C, the specific gravity meter G indicates that the specific gravity of the high-salt wastewater entering the wiped-film evaporator C is 1.1, indicating that the concentration of the high-salt wastewater entering the wiped-film evaporator C has decreased, that is, the water content in the high-salt wastewater is high. Therefore, the interlocking control device E controls the opening of the external steam control valve 1 and the electric valve 2 by 3% from the current level, slowing the feed rate of the high-salt wastewater. Furthermore, the interlocking control device E controls the opening of the supplemental steam valve 6, allowing external steam to be directly supplied to the wiped-film evaporator C, heating the wastewater in the wiped-film evaporator C and increasing the evaporation rate of the wiped-film evaporator C. As treatment continues, when the specific gravity meter G indicates that the specific gravity of the high-salt wastewater entering wiped-film evaporator C falls within the range of 1.13-1.16, the interlocking control device E closes the steam supply valve 6 and increases the openings of the external steam control valve 1 and the electric valve 2 by 1.8% from their current values. Condensate L generated by the wiped-film evaporator C is output to the sump J. Steam generated by the wiped-film evaporator C is condensed into water in condenser D and then enters the sump J. The sodium chloride waste salt generated at the bottom of the wiped-film evaporator C is discharged into the salt collection bag.

[0060] Example 4

[0061] The method for treating high-salt wastewater from L-carnitine production comprises the following steps:

[0062] S1. Chemical analysis shows that the concentration of ammonia chloride wastewater in the high-salt wastewater pool FS is 9.5%. Turn on the vacuum pump F and the regulating valve 3. When the reading on the second pressure gauge P2 is -0.08 MPa, open the coolant input control valve 5 and the coolant output control valve 4, and start the wiped film evaporator C.

[0063] S2, open the external steam control valve 1, and the steam enters the first-effect evaporator A to preheat the equipment.

[0064] In step S3, when the reading on the first pressure gauge P1 reaches 0.45 MPa, feed pump H is started and electric valve 2 is opened. Feed pump H feeds high-salt wastewater with a 9.5% ammonium chloride concentration from the high-salt wastewater tank FS into the first-effect evaporator A. Due to the pressure differential, the high-salt wastewater is continuously heated and evaporated by external steam as it moves downward within the first-effect evaporator A. Primary steam is generated in the first-effect evaporator A and output to the second-effect evaporator B, which heats the second-effect evaporator B. After evaporation in the first-effect evaporator A, the high-salt wastewater enters the second-effect evaporator B due to the pressure differential and continues to evaporate, generating secondary steam. Condensate L generated in the first-effect evaporators A and B is output to the sump J through the condensate output port.

[0065] In step S4, the secondary steam from the second-effect evaporator B enters the wiped-film evaporator C and heats it. The high-salt wastewater, after evaporation at the bottom of the second-effect evaporator B, enters the wiped-film evaporator C under the pressure differential, where it continues to be heated and evaporated. The salt produced in the wiped-film evaporator C is discharged from the second output port of the wiped-film evaporator C. When the high-salt wastewater from the second-effect evaporator B enters the wiped-film evaporator C, the specific gravity meter G indicates that the specific gravity of the high-salt wastewater entering the wiped-film evaporator C is 1.12, indicating that the concentration of the high-salt wastewater entering the wiped-film evaporator C has decreased, that is, the water content in the high-salt wastewater is high. Therefore, the interlocking control device E controls the opening of the external steam control valve 1 and the electric valve 2 by 2% from the current level, slowing the feed rate of the high-salt wastewater. Furthermore, the interlocking control device E controls the opening of the supplemental steam valve 6 to open, allowing external steam to be directly supplied to the wiped-film evaporator C, heating the wastewater in the wiped-film evaporator C and increasing the evaporation rate of the wiped-film evaporator C. As treatment continues, when the specific gravity meter G indicates that the specific gravity of the high-salt wastewater entering wiped-film evaporator C falls within the range of 1.13-1.16, the interlocking control device E closes the steam supply valve 6 and increases the openings of the external steam control valve 1 and the electric valve 2 by 1%. Condensate L generated in the wiped-film evaporator C is output to the water collection tank J. Steam generated in the wiped-film evaporator C is condensed into water in the condenser D and then enters the water collection tank J. The ammonium chloride waste salt generated at the bottom of the wiped-film evaporator C is discharged into the salt collection bag.

Claims

1. An L-carnitine production high-salt wastewater treatment device, comprising an external steam control valve (1), a first pressure gauge (P1), a first-effect evaporator (A), a second-effect evaporator (B), and a feed pump (H) for conveying high-salt wastewater, wherein the feed pump (H) is connected to the first-effect evaporator (A), the external steam control valve (1) is connected to the first-effect evaporator (A), the first pressure gauge (P1) is installed at the input end or the output end of the external steam control valve (1), the output end of the first-effect evaporator (A) is connected to the input end of the second-effect evaporator (B), and is characterized in that: The system further comprises a scraped film evaporator (C), a condensing unit, and a vacuum unit. The scraped film evaporator (C) has a plurality of input ends and a plurality of output ends. The input end of the scraped film evaporator (C) is connected to the output end of the second-effect evaporator (B). The condensing unit comprises a condenser (D), a coolant input control valve (5), and a coolant output control valve (4); the input end of the condenser (D) is connected to the first output end of the scraped film evaporator (C); the coolant input control valve (5) and the coolant output control valve (4) are respectively connected to the condenser (D); The vacuum unit comprises a regulating valve (3), a third pipeline (G3), a second pressure gauge (P2), and a vacuum pump (F); the output end of the condenser (D) is connected to one end of the regulating valve (3) through the third pipeline (G3); the other end of the regulating valve (3) is connected to the vacuum pump (F); and the second pressure gauge (P2) is connected to the third pipeline (G3).

2. The L-carnitine production high-salt wastewater treatment equipment according to claim 1, characterized in that, The invention also includes a first pipeline (G1), an electric valve (2), a second pipeline (G2), a specific gravity tester (G), and an interlocking control device (E). One end of the first pipeline (G1) is connected to the output end of the feed pump (H), the other end of the first pipeline (G1) is connected to one end of the electric valve (2), the other end of the electric valve (2) is connected to the first-effect evaporator (A), the second-effect evaporator (B) is connected to the scraped film evaporator (C) through the second pipeline (G2), the specific gravity tester (G) is connected to the second pipeline (G2), and the interlocking control device (E) is electrically connected to the electric valve (2) and the specific gravity tester (G) respectively.

3. The L-carnitine production high-salt wastewater treatment equipment according to claim 1, characterized in that, The invention also includes a steam supply valve (6), wherein the input end of the steam supply valve (6) is connected in parallel with the input end of the external steam control valve (1), the output end of the steam supply valve (6) is connected to the scraped film evaporator (C), and the steam supply valve (6) is also connected to the interlocking control device (E).

4. A method for treating high-salt wastewater from L-carnitine production, comprising: using the high-salt wastewater treatment equipment from L-carnitine production according to claim 1, characterized in that: The following steps are involved: S1, start the vacuum pump (F) and the regulating valve (3), and when the reading on the second pressure gauge (P2) is -0.05 to -0.098 MPa, open the coolant input control valve (5) and the coolant output control valve (4), and start the wiped film evaporator (C); S2, open the external steam control valve (1) to preheat the equipment; S3, when the reading on the first pressure gauge (P1) is 0.3-0.5Mpa, the feed pump (H) is started, and the feed pump (H) inputs the high-salt wastewater into the first-effect evaporator (A). The high-salt wastewater is continuously heated and evaporated by external steam during the downward movement due to the pressure difference in the first-effect evaporator (A). The primary steam generated in the first-effect evaporator (A) is output to the second-effect evaporator (B) to heat the second-effect evaporator (B). After evaporation in the first-effect evaporator (A), the high-salt wastewater enters the second-effect evaporator (B) under the action of the pressure difference to continue evaporation and generate secondary steam; S4, the secondary steam in the second-effect evaporator (B) enters the scraped film evaporator (C) and heats the scraped film evaporator (C). The high-salt wastewater after evaporation at the bottom of the second-effect evaporator (B) enters the scraped film evaporator (C) under the action of the pressure difference and continues to be heated and evaporated. The salt generated in the scraped film evaporator (C) is discharged from the second output end of the scraped film evaporator (C).

5. The method for treating high-salt wastewater produced by L-carnitine production according to claim 4, wherein: The invention also includes using a specific gravity tester (G) to test the high-salt wastewater discharged from the second-effect evaporator (B), an interlocking control device (E) obtains the test result of the specific gravity tester (G), and the interlocking control device (E) controls the opening of the external steam control valve (1) and the electric valve (2) according to the test result of the specific gravity tester (G).

6. The method for treating high-salt wastewater produced by L-carnitine production according to claim 5, wherein: If the value provided by the specific gravity tester (G) obtained by the interlocking control device (E) is within the range of 1.13-1.16, the interlocking control device (E) controls the opening of the external steam control valve (1) and the electric valve (2) to remain unchanged; If the value provided by the specific gravity tester (G) obtained by the interlocking control device (E) is greater than 1.16, the interlocking control device (E) controls the opening of the external steam control valve (1) and the electric valve (2) to increase; If the value provided by the specific gravity tester (G) obtained by the interlocking control device (E) is less than 1.13, the interlocking control device (E) controls the opening of the external steam control valve (1) and the electric valve (2) to decrease.

7. The method for treating high-salt wastewater produced by L-carnitine production according to claim 6, wherein: If the interlocking control device (E) obtains a value provided by the specific gravity tester (G) that is less than 1.13, the interlocking control device (E) controls the steam supply valve (6) to open, so that external steam is directly supplied to the scraped film evaporator (C) to heat the high-salt wastewater in the scraped film evaporator (C).

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