System and method for recovering ethylene glycol from waste heat power generation condensate water

Abstract

The invention provides a system and method for recovering ethylene glycol from waste heat power generation condensate water, and relates to the technical field of ethylene glycol recovery, the system comprises a process tower, a waste heat power generation mechanism, a condensate water tank, a recovery tank and a pipeline mechanism; the process tower is provided with a tower top gas phase outlet, a tower top reflux inlet and a tower bottom liquid phase outlet, the condensate water tank is provided with a water tank liquid phase inlet and a water tank liquid phase outlet, and the recovery tank is provided with a recovery tank liquid phase inlet and a recovery tank liquid phase outlet; the waste heat power generation mechanism is respectively communicated with the tower top gas phase outlet and the water tank liquid phase inlet through the pipeline mechanism, the water tank liquid phase outlet is communicated with the recovery tank liquid phase inlet through the pipeline mechanism, and the recovery tank liquid phase outlet is communicated with the tower top reflux inlet through the pipeline mechanism; the system provided by the invention alleviates the technical problem of tedious system flow for increasing the ethylene glycol recovery amount through 2-MD decomposition in the related technology.

Description

Technical Field

[0001] The present invention relates to the technical field of ethylene glycol recovery, and in particular to a system and method for recovering ethylene glycol from waste heat power generation condensate water. Background Art

[0002] The polyester unit will produce a large amount of esterification steam with a temperature of about 100-105℃. This steam carries a large amount of low-grade heat and has always been the focus of research on energy optimization. At present, the most commonly used solution for the utilization of waste heat is to convert heat energy into electricity through the organic Rankine cycle (ORC) power generation technology, but the esterification water condensed by waste heat power generation is usually discharged to the sewage station after stripping treatment. The waste heat power generation esterification water still contains a large amount of organic matter such as ethylene glycol, acetaldehyde and 2-methyl-1,3-dioxolane (2-MD). Among them, ethylene glycol and acetaldehyde can react to generate 2-MD and water. The reaction is a reversible reaction. The specific chemical reaction equation is shown in formula (1). When there is an excess of water, the reaction proceeds in the reverse direction. Acidic and high temperature conditions can increase the reaction rate and promote the rapid decomposition of 2□MD into acetaldehyde and ethylene glycol. Therefore, the ethylene glycol content in the esterification water can be increased by heating, which is conducive to the subsequent separation and recycling of ethylene glycol.

[0003]

[0004] Currently in the polyester industry, there are many systems that increase the recovery of ethylene glycol through 2-MD decomposition, but most of them have lengthy processes, high energy consumption, and require a lot of modifications to the original esterification unit equipment. Summary of the invention

[0005] The object of the present invention is to provide a system and method for recovering ethylene glycol from waste heat power generation condensate water, so as to alleviate the technical problem of lengthy system process in the related art of increasing the amount of ethylene glycol recovered by 2-MD decomposition.

[0006] In a first aspect, the system for recovering ethylene glycol from waste heat power generation condensed water provided by the present invention comprises: a process tower, a waste heat power generation mechanism, a condensed water tank, a recovery tank and a pipeline mechanism; the process tower has a tower top gas phase outlet, a tower top reflux port and a tower bottom liquid phase outlet, the condensed water tank has a water tank liquid phase inlet and a water tank liquid phase outlet, and the recovery tank has a recovery tank liquid phase inlet and a recovery tank liquid phase outlet;

[0007] The waste heat power generation mechanism is connected to the tower top gas phase outlet and the water tank liquid phase inlet respectively through the pipeline mechanism, the water tank liquid phase outlet is connected to the recovery tank liquid phase inlet through the pipeline mechanism, and the recovery tank liquid phase outlet is connected to the tower top reflux port through the pipeline mechanism.

[0008] Optionally, the recovery tank comprises a tank body, and the tank body is provided with a liquid phase inlet of the recovery tank and a liquid phase outlet of the recovery tank;

[0009] The recovery tank liquid phase inlet is provided with two, namely a first recovery tank liquid phase inlet and a second recovery tank liquid phase inlet, the first recovery tank liquid phase inlet and the recovery tank liquid phase outlet are respectively provided at both ends of the tank body, and the second recovery tank liquid phase inlet is provided in the middle of the tank body;

[0010] The recovery tank also includes a first partition, which is arranged in the middle of the tank body, dividing the interior of the tank body into a first chamber and a second chamber that are interconnected, the first recovery tank liquid phase inlet is connected to the first chamber, and the recovery tank liquid phase outlet and the second recovery tank liquid phase inlet are both connected to the second chamber.

[0011] Optionally, the tank body further includes a plurality of second partitions, and the plurality of second partitions are all arranged in the first chamber, and the area of ​​each second partition is smaller than the area of ​​the radial cross section of the tank body; the plurality of second partitions are distributed in two rows and are arranged in an alternating manner.

[0012] Optionally, the pipeline mechanism includes a first recovery branch pipe and a second recovery branch pipe, the liquid phase inlet of the first recovery tank is connected to the condensed water tank through the first recovery branch pipe, and the liquid phase inlet of the second recovery tank is connected to the condensed water tank through the second recovery branch pipe;

[0013] The first recovery branch pipe is provided with a first recovery control valve, and the second recovery branch pipe is provided with a second recovery control valve.

[0014] Optionally, the pipeline mechanism also includes a recovery main pipe and a gas recovery pipe, the recovery main pipe is connected to the liquid phase outlet of the water tank, the first recovery branch pipe and the second recovery branch pipe respectively, the recovery main pipe is provided with a first recovery pump and a total recovery control valve, the gas recovery pipe is connected to the recovery main pipe, and the connection point is located between the first recovery pump and the total recovery control valve.

[0015] Optionally, the waste heat power generation mechanism includes an evaporator and a preheater, the evaporator has a first heat flow inlet and a first heat flow outlet, and the preheater has a second heat flow inlet and a second heat flow outlet; the pipeline mechanism includes a first cooling pipe, a second cooling pipe and a third cooling pipe;

[0016] The first heat flow inlet is connected to the tower top gas phase outlet through the first cooling pipe, the first heat flow outlet is connected to the second heat flow inlet through the second cooling pipe, and the second heat flow outlet is connected to the water tank liquid phase inlet through the third cooling pipe.

[0017] Optionally, the pipeline mechanism also includes a fourth cooling pipe, which is connected to the second cooling pipe and the third cooling pipe respectively, and the third cooling pipe is provided with a first cooling control valve, and the first cooling control valve is located between the second heat flow outlet and the connection point between the fourth cooling pipe and the third cooling pipe, and the fourth cooling pipe is provided with a second cooling control valve.

[0018] Optionally, the system further comprises a condenser, the condenser having a condensation heat flow inlet and a condensation heat flow outlet; the condensation water tank further comprises a water tank gas phase outlet, and the recovery tank further comprises a recovery tank gas phase outlet;

[0019] The pipeline mechanism includes a first condenser and a second condenser. The gas phase outlet of the water tank is connected to the condensation heat flow inlet through the first condenser, and the gas phase outlet of the recovery tank is connected to the condensation heat flow inlet through the second condenser.

[0020] Optionally, both the outside of the recovery tank and the outside of the pipeline mechanism are provided with a heat-insulating layer.

[0021] In a second aspect, the present invention provides a method for recovering ethylene glycol from waste heat power generation condensate water, comprising:

[0022] Cooling the esterification steam to obtain condensed water at 60-70°C, and collecting the condensed water;

[0023] The collected condensed water is transported to the stripping section and the recovery tank respectively;

[0024] The recovered condensed water is allowed to stay in the recovery tank for 2-3 hours to obtain esterification reflux water with increased ethylene glycol content;

[0025] The esterification reflux water is refluxed to the top of the process tower, and then discharged from the bottom of the tower after separation and purification.

[0026] When the system for recovering ethylene glycol from waste heat power generation condensed water provided by the present invention is used, the esterified steam extracted from the top of the process tower is transported to the waste heat power generation mechanism, and after heat exchange with the organic medium in the waste heat power generation mechanism, 60-70°C waste heat power generation condensed water is obtained, and the condensed water in the condensed water tank is collected; the condensed water in the condensed water tank is transported to the recovery tank, and after the condensed water stays in the recovery tank for 2-3 hours, 2-MD is decomposed into acetaldehyde and ethylene glycol at 60-70°C to obtain esterified reflux water with increased ethylene glycol content; the esterified reflux water is transported to the top of the process tower, and then discharged from the bottom of the tower after separation and purification by the process tower to obtain a reusable ethylene glycol solution. By adding a recovery tank at the rear end of the waste heat power generation mechanism to achieve more efficient recovery of ethylene glycol in the condensed water, the system for recovering ethylene glycol from waste heat power generation condensed water provided by the present invention has a short process, a simple structure and a reasonable design, and at the same time increases the amount of ethylene glycol recovered in the overall process. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the related technologies, the drawings required for use in the specific embodiments or the related technical descriptions will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0028] Figure 1 A schematic diagram of a system for recovering ethylene glycol from waste heat power generation condensate water provided in an embodiment of the present invention;

[0029] Figure 2 A schematic diagram of the internal structure of a recovery tank in a system for recovering ethylene glycol from waste heat power generation condensate water provided by an embodiment of the present invention;

[0030] Figure 3 A schematic structural diagram of a first baffle in a system for recovering ethylene glycol from waste heat power generation condensate water provided by an embodiment of the present invention;

[0031] Figure 4 A schematic diagram of the structure of a second partition in a system for recovering ethylene glycol from waste heat power generation condensate water provided in an embodiment of the present invention.

[0032] Icons: 100 - process tower; 110 - gas phase outlet at the top of the tower; 120 - reflux port at the top of the tower; 130 - liquid phase outlet at the bottom of the tower; 140 - second recovery pump; 150 - recovery regulating valve;

[0033] 210 - evaporator; 211 - first heat flow inlet; 212 - first heat flow outlet; 213 - first cooling inlet; 214 - first cooling outlet; 220 - preheater; 221 - second heat flow inlet; 222 - second heat flow outlet; 223 - second cooling inlet; 224 - second cooling outlet;

[0034] 300 - condensed water tank; 310 - water tank liquid phase inlet; 320 - water tank liquid phase outlet; 330 - water tank gas phase outlet;

[0035] 400-recovery tank; 410-tank body; 411-liquid phase inlet of the first recovery tank; 412-liquid phase inlet of the second recovery tank; 413-liquid phase outlet of the recovery tank; 414-gas phase outlet of the recovery tank; 415-first chamber; 416-second chamber; 420-first partition; 421-first arc-shaped portion; 422-first straight portion; 430-second partition; 431-second arc-shaped portion; 432-second straight portion; 440-liquid level gauge;

[0036] 510-first recovery branch pipe; 511-first recovery control valve; 520-second recovery branch pipe; 521-second recovery control valve; 530-recovery main pipe; 531-first recovery pump; 532-main recovery control valve; 540-gas recovery pipe; 550-first cooling pipe; 551-gas control valve; 560-second cooling pipe; 570-third cooling pipe; 571-first cooling control valve; 580-fourth cooling pipe; 581-second cooling control valve; 591-first condenser pipe; 592-second condenser pipe;

[0037] 600 - condenser; 610 - condensation heat flow inlet; 620 - condensation heat flow outlet; 630 - condensation inlet; 640 - condensation outlet; 650 - fan;

[0038] 710-ethylene glycol recycling section; 720-stripping section; 730-public utility heat medium boiler. DETAILED DESCRIPTION

[0039] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0041] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0042] like Figure 1As shown, the system for recovering ethylene glycol from waste heat power generation condensed water provided by an embodiment of the present invention includes: a process tower 100, a waste heat power generation mechanism, a condensed water tank 300, a recovery tank 400 and a pipeline mechanism; the process tower 100 has a tower top gas phase outlet 110, a tower top reflux port 120 and a tower bottom liquid phase outlet 130, the condensed water tank 300 has a water tank liquid phase inlet 310 and a water tank liquid phase outlet 320, and the recovery tank 400 has a recovery tank liquid phase inlet and a recovery tank liquid phase outlet 413; the waste heat power generation mechanism is connected to the tower top gas phase outlet 110 and the water tank liquid phase inlet 310 respectively through the pipeline mechanism, the water tank liquid phase outlet 320 is connected to the recovery tank liquid phase inlet through the pipeline mechanism, and the recovery tank liquid phase outlet 413 is connected to the tower top reflux port 120 through the pipeline mechanism.

[0043] Specifically, the tower top gas phase outlet 110 is arranged at the top of the process tower 100, and is connected to the waste heat power generation mechanism through a pipeline mechanism. The tower top reflux port 120 is arranged at the upper end of the outer peripheral wall of the process tower 100, and is connected to the recovery tank liquid phase outlet 413 of the recovery tank 400 through a pipeline mechanism, and a second recovery pump 140 and a recovery regulating valve 150 are arranged on the connected pipeline, and the second recovery pump 140 is used to extract the esterification reflux water in the recovery tank 400 into the process tower 100. The tower bottom liquid phase outlet 130 is arranged at the bottom of the process tower 100, and is connected to the external ethylene glycol recycling section 710 through a pipeline mechanism. The water tank liquid phase inlet 310 is arranged at one end of the condensed water tank 300, and is connected to the waste heat power generation mechanism through a pipeline mechanism, and the water tank liquid phase outlet 320 is arranged at the other end of the condensed water tank 300, and is connected to the recovery tank liquid phase inlet through a pipeline mechanism.

[0044] When using the system for recovering ethylene glycol from waste heat power generation condensed water provided by the embodiment of the present invention, the esterification steam extracted from the top of the process tower 100 is transported to the waste heat power generation mechanism, and after heat exchange with the organic medium in the waste heat power generation mechanism, the waste heat power generation condensed water at 60-70°C is obtained, and collected in the condensed water tank 300; the condensed water in the condensed water tank 300 is transported to the recovery tank 400, and after the condensed water stays in the recovery tank 400 for 2-3 hours, 2-MD is decomposed into acetaldehyde and ethylene glycol at 60-70°C, and esterification reflux water with increased ethylene glycol content is obtained; the esterification reflux water is transported to the top of the process tower 100, and then separated and purified by the process tower 100 and discharged from the bottom of the tower to obtain a reusable ethylene glycol solution. By adding the recovery tank 400 at the rear end of the waste heat power generation mechanism to achieve more efficient recovery of ethylene glycol in the condensed water, the system for recovering ethylene glycol from waste heat power generation condensed water provided by the embodiment of the present invention has a short process, a simple structure and a reasonable design, and at the same time increases the amount of ethylene glycol recovered in the overall process.

[0045] like Figure 2As shown, the recovery tank 400 includes a tank body 410, and the tank body 410 is provided with a recovery tank liquid phase inlet and a recovery tank liquid phase outlet 413; there are two recovery tank liquid phase inlets, namely a first recovery tank liquid phase inlet 411 and a second recovery tank liquid phase inlet 412, the first recovery tank liquid phase inlet 411 and the recovery tank liquid phase outlet 413 are respectively arranged at both ends of the tank body 410, and the second recovery tank liquid phase inlet 412 is arranged in the middle of the tank body 410; the recovery tank 400 also includes a first partition plate 420, the first partition plate 420 is arranged in the middle of the tank body 410, and the interior of the tank body 410 is divided into a first chamber 415 and a second chamber 416 which are interconnected, the first recovery tank liquid phase inlet 411 is connected to the first chamber 415, and the recovery tank liquid phase outlet 413 and the second recovery tank liquid phase inlet 412 are both connected to the first chamber.

[0046] Specifically, the cross-section of the outer peripheral wall of the tank body 410 is circular, and the recovery tank liquid phase outlet 413 is provided on the tank body 410. Figure 2 At the left end shown, the first recovery tank liquid phase inlet 411 is provided on the tank body 410 Figure 2 At the right end shown, the second recovery tank liquid phase inlet 412 is arranged in the middle of the tank body 410, and the first recovery tank liquid phase inlet 411, the second recovery tank liquid phase inlet 412 and the recovery tank liquid phase outlet 413 are all connected to the inside of the tank body 410. A liquid level gauge 440 connected to the inside of the tank body 410 is also arranged at one end of the tank body 410, and the liquid level gauge 440 is used to detect the change of the liquid level in the tank body 410.

[0047] like Figure 2 As shown, the first partition 420 is located in the middle of the tank body 410 and is in an arched shape. Figure 3 As shown, the side of the first partition plate 420 includes a first arcuate portion 421 and a first straight portion 422, and the two ends of the first straight portion 422 are respectively connected to the two ends of the first arcuate portion 421. The curvature of the first arcuate portion 421 is the same as the curvature of the cross section of the inner wall of the tank body 410. The first arcuate portion 421 is fixedly connected to the inner wall of the tank body 410 by welding or bonding. The first straight portion 422 is located above the first arcuate portion 421 and is spaced apart from the inner wall of the tank body 410. The first partition 420 divides the interior of the tank body 410 into a first chamber 415 and a second chamber 416 of approximately equal volume. The first chamber 415 and the second chamber 416 are connected via the gap between the first partition 420 and the inner wall of the tank body 410. The first recovery tank liquid phase inlet 411 is connected to the first chamber 415 and extends to the bottom of the first chamber 415. The second recovery tank liquid phase inlet 412 is connected to the second chamber 416 and extends to the bottom of the second chamber 416.

[0048] When the condensed water enters the tank body 410 through the first recovery tank liquid phase inlet 411, the effective volume in the recovery tank 400 is the volume of the tank body 410. When the condensed water enters the tank body 410 through the second recovery tank liquid phase inlet 412, the effective volume in the recovery tank 400 is half the volume of the tank body 410. The first partition 420 is used to separate the interior of the tank body 410 into a first chamber 415 and a second chamber 416 of nearly equal volume. The condensed water enters the tank body 410 from the first recovery tank liquid phase inlet 411 or the second recovery tank liquid phase inlet 412 according to the flow rate of the condensed water, so as to adapt to the required residence time of the condensed water under different flow conditions.

[0049] like Figure 2 As shown, the recovery tank 400 also includes a plurality of second partitions 430, which are all disposed in the first chamber 415, and the area of ​​each second partition 430 is smaller than the area of ​​the radial cross section of the tank body 410; the plurality of second partitions 430 are distributed in two rows and are arranged alternately.

[0050] like Figure 4 As shown, each second partition 430 is in an arc shape, and the side of each second partition 430 includes a second arc portion 431 and a second straight portion 432, the two ends of the second straight portion 432 are respectively connected to the two ends of the second arc portion 431, and the curvature of the second arc portion 431 is the same as the curvature of the cross section of the inner wall of the tank body 410. The plurality of second partitions 430 are distributed in two rows, upper and lower, in the tank body 410, and are arranged in a staggered manner, the second straight portion 432 of the second partition 430 in the upper row is located below its second arc portion 431, and the second straight portion 432 of the second partition 430 in the lower row is located above its second arc portion 431. Each second arc portion 431 is fixedly connected to the inner wall of the tank body 410 by welding or bonding, the second straight portion 432 is spaced from the inner wall of the tank body 410, and the height range of the space is 0.2-0.4 of the diameter of the tank body 410, the spacing between adjacent second partitions 430 is 0.3-0.5 of the distance between the tank body 410, and the projections of the upper and lower rows of second partitions 430 on the end surface of the tank body 410 have overlapping parts. Arranging multiple second partitions 430 in the tank body 410 can change the movement direction of condensed water in the first chamber 415, thereby increasing the time the condensed water stays in the tank body 410.

[0051] In order to study the influence of the notch height and spacing of the second partition 430 in the recovery tank 400 on the residence time, esterified water with a flow rate of 2kg / h, an initial ethylene glycol content of 0.3%wt and a temperature of 70°C was introduced into the recovery tank 400 with a volume of 5L through the first recovery tank liquid phase inlet 411, and the ethylene glycol content in the esterified water at the outlet recovery tank liquid phase outlet 413 was measured. The filling volume in the tank is 70% here.

[0052] The preliminary experimental results show that after the esterified water with an initial ethylene glycol content of 0.3%wt is heated at 70℃ for 4h, the 2-MD conversion rate basically reaches the limit, and the ethylene glycol content is basically maintained in the range of 0.8%-0.9%wt. Therefore, the residence time can be qualitatively judged by the ethylene glycol content in the esterified water at the outlet. The higher the ethylene glycol content, the longer the residence time.

[0053] The experimental results are shown in the following table:

[0054]

[0055] It can be seen from the above table that when the spacing of the second partitions 430 is consistent, the smaller the gap height, the longer the residence time, and the higher the ethylene glycol content of the esterified water at the corresponding outlet; when the gap height of the second partitions 430 is consistent, the smaller the spacing of the second partitions 430, the longer the residence time, and the higher the ethylene glycol content of the esterified water at the corresponding outlet. In actual production, when the second partition 430 is set in the recovery tank 400, the inlet flow range of the esterified water and the initial ethylene glycol content should be fully considered to ensure sufficient residence time as much as possible to convert 2-MD into ethylene glycol.

[0056] like Figure 1 As shown, the pipeline mechanism includes a first recovery branch pipe 510 and a second recovery branch pipe 520. The liquid phase inlet 411 of the first recovery tank is connected to the condensate water tank 300 through the first recovery branch pipe 510, and the liquid phase inlet 412 of the second recovery tank is connected to the condensate water tank 300 through the second recovery branch pipe 520; the first recovery branch pipe 510 is provided with a first recovery control valve 511, and the second recovery branch pipe 520 is provided with a second recovery control valve 521.

[0057] Specifically, the first recovery control valve 511 and the second recovery control valve 521 are both configured as ball valves. When the effective volume in the tank body 410 needs to be equal to the volume of the tank body 410, the first recovery control valve 511 is opened, and the second recovery control valve 521 is closed, so that the condensed water enters the tank body 410 through the first recovery tank liquid phase inlet 411; when the effective volume of the recovery tank 400 needs to be half the volume of the tank body 410, the first recovery control valve 511 is closed, and the second recovery control valve 521 is opened, so that the condensed water enters the tank body 410 through the second recovery tank liquid phase inlet 412. By providing the first recovery branch pipe 510, the second recovery branch pipe 520, the first recovery control valve 511, and the second recovery control valve 521, the condensed water is controlled to enter the tank body 410 from different positions, and the effective volume in the tank body 410 is adjusted.

[0058] As an implementation manner, the first recovery branch pipe 510 and the second recovery branch pipe 520 may be respectively connected to the recovery tank liquid phase outlet 413 .

[0059] In one embodiment of the present application, Figure 1 As shown, the pipeline structure also includes a recovery main pipe 530 and a gas recovery pipe 540. The recovery main pipe 530 is connected to the water tank liquid phase outlet 320, the first recovery branch pipe 510 and the second recovery branch pipe 520 respectively. The recovery main pipe 530 is provided with a first recovery pump 531 and a total recovery control valve 532. The gas recovery pipe 540 is connected to the recovery main pipe 530, and the connection point is located between the first recovery pump 531 and the total recovery control valve 532.

[0060] Specifically, one end of the recovery main pipe 530 is connected to the water tank liquid phase outlet 320, and the other end is connected to the first recovery branch pipe 510 and the second recovery branch pipe 520 through a tee pipe, respectively. One end of the gas recovery pipe 540 is connected to the portion of the recovery main pipe 530 located between the first recovery pump 531 and the total recovery control valve 532, and the other end is connected to the stripping section 720. Along the flow direction of the condensed water in the recovery main pipe 530, the first recovery pump 531 is located upstream of the total recovery control valve 532, and the total recovery control valve 532 is configured as a regulating valve.

[0061] The condensed water in the condensed water tank 300 has two paths, one path flows to the stripping section 720 through the gas recovery pipe 540, and the other path flows to the B recovery tank 400, and the flow to the recovery tank 400 and the stripping section 720 can be adjusted by the total recovery control valve 532.

[0062] like Figure 1 As shown, the waste heat power generation mechanism includes an evaporator 210 and a preheater 220, the evaporator 210 has a first heat flow inlet 211 and a first heat flow outlet 212, and the preheater 220 has a second heat flow inlet 221 and a second heat flow outlet 222; the pipeline mechanism includes a first cooling pipe 550, a second cooling pipe 560 and a third cooling pipe 570; the first heat flow inlet 211 is connected to the tower top gas phase outlet 110 through the first cooling pipe 550, the first heat flow outlet 212 is connected to the second heat flow inlet 221 through the second cooling pipe 560, and the second heat flow outlet 222 is connected to the water tank liquid phase inlet 310 through the third cooling pipe 570.

[0063] Specifically, a gas control valve 551 is provided on the first cooling pipe 550, and the gas control valve 551 can be set as a regulating valve for adjusting the flow rate of the esterification steam flowing to the evaporator 210. The evaporator 210 is also provided with a first cooling inlet 213 and a first cooling outlet 214, and the preheater 220 is also provided with a second cooling inlet 223 and a second cooling outlet 224, and the second cooling outlet 224 is connected with the first cooling inlet 213, and the cooling medium enters the preheater 220 from the second cooling inlet 223, and the cooling medium flowing out of the second cooling outlet 224 enters the evaporator 210 through the first cooling inlet 213, and finally flows out from the first cooling outlet 214. The esterification steam passes through the evaporator 210 and the preheater 220 in sequence, and performs heat exchange with the cooling medium to generate condensed water, and the condensed water enters the condensed water tank 300 through the third cooling pipe 570, thereby realizing the condensation and collection of the esterification steam.

[0064] The pipeline mechanism also includes a fourth cooling pipe 580, which is connected to the second cooling pipe 560 and the third cooling pipe 570 respectively. The third cooling pipe 570 is provided with a first cooling control valve 571. The first cooling control valve 571 is located between the second hot flow outlet 222 and the connection point between the fourth cooling pipe 580 and the third cooling pipe 570. The fourth cooling pipe 580 is provided with a second cooling control valve 581.

[0065] Specifically, the first cooling control valve 571 and the second cooling control valve 581 are both configured as ball valves. The temperature of the condensed esterified water can reach 60-70°C in summer, at which time the first cooling control valve 571 can be opened and the second cooling control valve 581 can be closed, so that the cooled esterified water directly enters the condensed water tank 300; in winter, the temperature of the condensed esterified water is lower than 60°C, at which time the second cooling control valve 581 can be opened and the first cooling control valve 571 can be closed to lead a gas-liquid mixture with a temperature of 80-100°C from the first hot flow outlet 212 directly to the condensed water tank 300, thereby playing a role in heating the condensed water in the condensed water tank 300.

[0066] like Figure 1 As shown, the system also includes a condenser 600, which has a condensation heat flow inlet 610 and a condensation heat flow outlet 620; the condensation water tank 300 also has a water tank gas phase outlet 330, and the recovery tank 400 also has a recovery tank gas phase outlet 414; the pipeline mechanism includes a first condensation pipe 591 and a second condensation pipe 592, the water tank gas phase outlet 330 is connected to the condensation heat flow inlet 610 through the first condensation pipe 591, and the recovery tank gas phase outlet 414 is connected to the condensation heat flow inlet 610 through the second condensation pipe 592.

[0067] The condenser 600 is located above the condensation water tank 300 and the recovery tank 400, and is provided with a condensation inlet 630 and a condensation outlet 640. The condensation medium can enter the condenser 600 from the condensation inlet 630 and flow out from the condensation outlet 640. One end of the first condensation pipe 591 is connected to the condensation heat flow inlet 610, and the other end is connected to the water tank gas phase outlet 330. One end of the second condensation pipe 592 is connected to the first condensation pipe 591, and the other end is connected to the recovery tank gas phase outlet 414. The condensation heat flow outlet 620 is connected to the fan 650. The volatilized gas in the condensation water tank 300 and the volatilized gas in the recovery tank 400 can enter the condenser 600 through the first condensation pipe 591 and the second condensation pipe 592. The 2-MD escaping in the gas phase is condensed and refluxed to the condensation water tank 300 or the recovery tank 400 by cooling water, thereby reducing the loss of 2-MD and increasing the subsequent ethylene glycol production. At the same time, the volatilized non-condensable gas in the condensation water tank 300 and the recovery tank 400 is extracted by the fan 650 and sent to the public engineering heat medium furnace 730 for incineration.

[0068] The outside of the recovery tank 400 and the outside of the pipeline mechanism are both provided with an insulation layer. Specifically, the insulation layer is provided with insulation cotton, so as to ensure that the heated esterified water can maintain a certain temperature and stay in the recovery tank 400, thereby promoting the conversion of 2-MD in the esterified water into ethylene glycol.

[0069] In a second aspect, the method for recovering ethylene glycol from waste heat power generation condensate water provided by an embodiment of the present invention comprises:

[0070] Cooling the esterification steam to obtain condensed water at 60-70°C, and collecting the condensed water;

[0071] The collected condensed water is transported to the stripping section 720 and the recovery tank 400 respectively;

[0072] The recovered condensed water is allowed to stay in the recovery tank 400 for 2-3 hours to obtain esterification reflux water with increased ethylene glycol content;

[0073] The esterification reflux water is refluxed to the top of the process tower 100, and then discharged from the bottom of the tower after separation and purification.

[0074] In one embodiment, about 13,000 kg / h of esterified steam containing 0.1%-0.3% wt ethylene glycol and 103°C is generated at the top of the process tower 100. When the esterified steam passes through the evaporator 210 and the preheater 220, it exchanges heat with the organic medium R245 flowing through the preheater 220 and the evaporator 210 to generate condensed water and collect it in the condensed water tank 300. The temperature of the condensed esterified water can reach 60-70°C in summer and below 60°C in winter. At this time, by closing the first cooling control valve 571 and opening the second cooling control valve 581, part of the gas-liquid mixture at the first hot flow outlet 212 can flow directly to the condensed water tank 300, thereby playing the role of heating the esterified water in the condensed water tank 300. The upper end of the water tank gas phase outlet 330 is connected to a condenser 600. The cooling water flowing through the condenser 600 can be used to condense the 2-MD escaping from the gas phase and return it to the condenser water tank 300, thereby reducing the loss of 2-MD and increasing the subsequent production of ethylene glycol. At the same time, the volatile non-condensable gas in the condenser water tank 300 is drawn away by the fan 650 and led to the utility heat medium furnace 730 (11) for incineration. The condensed water in the condenser water tank 300 with a temperature of 70°C is sent to the stripping section 720 and the recovery tank 400 through the first recovery pump 531, with flow rates of 7200 kg / h and 5800 kg / h respectively.

[0075] When the second recovery control valve 521 is opened and the first recovery control valve 511 is closed, the condensed water enters the recovery tank 400 through the second recovery tank liquid phase inlet 412. At this time, the volume in the tank is only half of the volume of the tank body 410, which is 25m 3 , and no partition is provided in the second chamber 416. When the filling amount is 70%, the corresponding condensed water stays in the recovery tank 400 wrapped with insulation cotton for about 3 hours, wherein 2-MD is decomposed into ethylene glycol and acetaldehyde. After the decomposition is complete, 5800 kg / h of esterified water containing 0.5%-0.7% wt ethylene glycol in the recovery tank 400 is refluxed to the top of the process tower 100 through the second recovery pump 140, and further separated and purified by the process tower 100, and finally an ethylene glycol solution with a purity of 90%-95% can be obtained at the bottom of the tower, which is used for the ethylene glycol recycling section 710. In addition, the volatile gas in the recovery tank 400 can enter the condenser 600 through the second condenser pipe 592, and the condensed solution is refluxed to the recovery tank 400, reducing the loss of 2-MD, and the non-condensable gas is drawn away by the fan 650 and led to the utility heat medium furnace 730 for incineration.

[0076] During the whole process, the waste heat power generation condensate water is heated and the ethylene glycol recovery tank 400 is added to increase the residence time, promote the decomposition of 2-MD, and increase the ethylene glycol content in the reflux esterification water. Then, the ethylene glycol recovery amount is increased by separation and purification through the process tower 100, thereby realizing the efficient recovery and utilization of ethylene glycol in the esterification water.

[0077] In another embodiment, the difference between this embodiment and the above embodiment is that the condensed water with a temperature of 60°C is respectively sent to the stripping section 720 and the ethylene glycol recovery tank 400 through the first recovery pump 531, and the flow rates are 2000kg / h and 11000kg / h respectively.

[0078] When the first recovery control valve 511 is opened and the second recovery control valve 521 is closed, the condensed water enters the recovery tank 400 through the first recovery tank liquid phase inlet 411. At this time, the volume in the tank is 50m 3 The volume of the second partition 430 in the first chamber 415 is 0.4 of the diameter of the tank body 410, and the spacing is 0.50 of the diameter of the tank body 410. The multiple second partitions 430 in the first chamber 415 change the direction of fluid movement and increase the residence time. When the filling amount is 70%, the corresponding condensed water stays in the recovery tank 400 wrapped with insulation cotton for about 4 hours, and 2-MD is decomposed into ethylene glycol and acetaldehyde. After the decomposition is complete, 11000 kg / h of esterified water containing 0.5%-0.7% wt ethylene glycol in the recovery tank 400 is refluxed to the top of the process tower 100 through the second recovery pump 140. Through further separation and purification of the process tower 100, an ethylene glycol solution with a purity of 90%-95% wt can be obtained at the bottom of the tower, which is used in the ethylene glycol recycling section 710. In addition, the volatile gas in the recovery tank 400 can enter the condenser 600 through the second condenser pipe 592, and the condensed solution flows back into the recovery tank 400, reducing the 2-MD loss. The non-condensable gas is extracted by the fan 650 and flows to the utility heat medium furnace 730 for incineration.

[0079] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A system for recovering ethylene glycol from waste heat power generation condensate, characterized in that: include: A process tower (100), a waste heat power generation mechanism, a condensed water tank (300), a recovery tank (400) and a pipeline mechanism; the process tower (100) has a tower top gas phase outlet (110), a tower top reflux port (120) and a tower bottom liquid phase outlet (130); the condensed water tank (300) has a water tank liquid phase inlet (310) and a water tank liquid phase outlet (320); and the recovery tank (400) has a recovery tank liquid phase inlet and a recovery tank liquid phase outlet (413); The waste heat power generation mechanism is connected to the tower top gas phase outlet (110) and the water tank liquid phase inlet (310) respectively through the pipeline mechanism, the water tank liquid phase outlet (320) is connected to the recovery tank liquid phase inlet through the pipeline mechanism, and the recovery tank liquid phase outlet (413) is connected to the tower top reflux port (120) through the pipeline mechanism.

2. The system for recovering ethylene glycol from waste heat power generation condensate water according to claim 1, characterized in that: The recovery tank (400) comprises a tank body (410), and the tank body (410) is provided with the recovery tank liquid phase inlet and the recovery tank liquid phase outlet (413); The recovery tank is provided with two liquid phase inlets, namely a first recovery tank liquid phase inlet (411) and a second recovery tank liquid phase inlet (412); the first recovery tank liquid phase inlet (411) and the recovery tank liquid phase outlet (413) are respectively arranged at two ends of the tank body (410), and the second recovery tank liquid phase inlet (412) is arranged in the middle of the tank body (410); The recovery tank (400) further comprises a first partition (420), wherein the first partition (420) is arranged in the middle of the tank body (410), and divides the interior of the tank body (410) into a first chamber (415) and a second chamber (416) which are interconnected, wherein the first recovery tank liquid phase inlet (411) is connected to the first chamber (415), and the recovery tank liquid phase outlet (413) and the second recovery tank liquid phase inlet (412) are both connected to the second chamber (416).

3. The system for recovering ethylene glycol from waste heat power generation condensate water according to claim 2, characterized in that: The recovery tank (400) further comprises a plurality of second partitions (430), wherein the plurality of second partitions (430) are all arranged in the first chamber (415), and the area of ​​each second partition (430) is smaller than the area of ​​the radial cross section of the tank body (410); the plurality of second partitions (430) are distributed in two rows and are arranged in a staggered manner.

4. The system for recovering ethylene glycol from waste heat power generation condensate water according to claim 2, characterized in that: The pipeline mechanism comprises a first recovery branch pipe (510) and a second recovery branch pipe (520); the first recovery tank liquid phase inlet (411) is connected to the condensed water tank (300) through the first recovery branch pipe (510); and the second recovery tank liquid phase inlet (412) is connected to the condensed water tank (300) through the second recovery branch pipe (520); The first recovery branch pipe (510) is provided with a first recovery control valve (511), and the second recovery branch pipe (520) is provided with a second recovery control valve (521).

5. The system for recovering ethylene glycol from waste heat power generation condensate water according to claim 4, characterized in that: The pipeline mechanism further comprises a recovery main pipe (530) and a gas recovery pipe (540); the recovery main pipe (530) is respectively connected to the water tank liquid phase outlet (320), the first recovery branch pipe (510) and the second recovery branch pipe (520); the recovery main pipe (530) is provided with a first recovery pump (531) and a total recovery control valve (532); the gas recovery pipe (540) is connected to the recovery main pipe (530), and the connection point is located between the first recovery pump (531) and the total recovery control valve (532).

6. The system for recovering ethylene glycol from waste heat power generation condensate water according to any one of claims 1 to 5, characterized in that: The waste heat power generation mechanism comprises an evaporator (210) and a preheater (220), the evaporator (210) having a first heat flow inlet (211) and a first heat flow outlet (212), and the preheater (220) having a second heat flow inlet (221) and a second heat flow outlet (222); the pipeline mechanism comprises a first cooling pipe (550), a second cooling pipe (560) and a third cooling pipe (570); The first heat flow inlet (211) is connected to the tower top gas phase outlet (110) through the first cooling pipe (550), the first heat flow outlet (212) is connected to the second heat flow inlet (221) through the second cooling pipe (560), and the second heat flow outlet (222) is connected to the water tank liquid phase inlet (310) through the third cooling pipe (570).

7. The system for recovering ethylene glycol from waste heat power generation condensate water according to claim 6, characterized in that: The pipeline mechanism also includes a fourth cooling pipe (580), which is connected to the second cooling pipe (560) and the third cooling pipe (570) respectively, and the third cooling pipe (570) is provided with a first cooling control valve (571), and the first cooling control valve (571) is located between the second heat flow outlet (222) and the connection point between the fourth cooling pipe (580) and the third cooling pipe (570), and the fourth cooling pipe (580) is provided with a second cooling control valve (581).

8. The system for recovering ethylene glycol from waste heat power generation condensate water according to any one of claims 1 to 5, characterized in that: The system further comprises a condenser (600), wherein the condenser (600) has a condensation heat flow inlet (610) and a condensation heat flow outlet (620); the condensation water tank (300) further comprises a water tank gas phase outlet (330), and the recovery tank (400) further comprises a recovery tank gas phase outlet (414); The pipeline structure includes a first condenser (591) and a second condenser (592); the water tank gas phase outlet (330) is connected to the condensation heat flow inlet (610) through the first condenser (591); and the recovery tank gas phase outlet (414) is connected to the condensation heat flow inlet (610) through the second condenser (592).

9. The system for recovering ethylene glycol from waste heat power generation condensate water according to any one of claims 1 to 5, characterized in that: The outside of the recovery tank (400) and the outside of the pipeline mechanism are both provided with a heat-insulating layer.

10. A method for recovering ethylene glycol from waste heat power generation condensate, characterized in that: include: Cooling the esterification steam to obtain condensed water at 60-70°C, and collecting the condensed water; The collected condensed water is transported to the stripping section (720) and the recovery tank (400) respectively; The recovered condensed water is allowed to stay in the recovery tank (400) for 2-3 hours to obtain esterification reflux water with increased ethylene glycol content; The esterification reflux water is refluxed to the top of the process tower (100), and then discharged from the bottom of the tower after separation and purification in the process tower (100).

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