Ethylene glycol rectification wastewater recovery system

Abstract

The utility model belongs to the technical field of wastewater recovery, and relates to an ethylene glycol rectification wastewater recovery system which comprises a wastewater collecting tank, a cooler, a delivery pump and a coal grinding water tank which are communicated in sequence, the wastewater collecting tank is externally connected with a wastewater header pipe; the ethylene glycol rectification wastewater recovery system further comprises a wastewater branch pipe communicated with the wastewater header pipe; and a wastewater drainage valve is arranged on the wastewater branch pipe. By arranging the waste water collecting tank, the cooler, the conveying pump and the coal grinding water tank, tower boiling waste water can be cooled and conveyed without loading and unloading, the loading and unloading time is saved, the cost is saved, and the risk of scalding personnel is reduced.

Description

Technical Field

[0001] The utility model belongs to the technical field of wastewater recovery, and relates to a glycol distillation wastewater recovery system for recovering the boiling tower wastewater in glycol distillation. Background Technique

[0002] At present, 8 towers are used for glycol distillation, namely 1# methanol recovery tower, 2# methanol recovery tower, dehydration tower, light component removal tower, ethylene glycol product tower, ethylene glycol recovery tower, ethanol recovery tower and aldehyde removal tower; and it includes 1 vacuum pump tail gas scrubbing tower. When glycol distillation generally operates at a high temperature (above 160°C), the formation of side reactants will be intensified; therefore, during the long-term operation of the glycol distillation system, these by-products scale or are locally blocked in the reboiler tubes and internals of each distillation tower, resulting in a gradual decrease in the heat exchange and evaporation effects of the distillation tower, and the distillation separation effect becomes worse. To prevent the phenomenon of blockage of the internals of the tower due to the scaling of glycol by-products, during the annual maintenance, desalted water is added to each distillation tower and steam is introduced for boiling the tower to clean the scale; however, about 245 tons of boiling tower wastewater (also known as wastewater) will be generated during the boiling tower period. The existing treatment method for these boiling tower wastewaters is to temporarily connect a pipeline (metal hose) to discharge the boiling tower wastewater into a wastewater tank truck for loading, and then transport it to the first-stage coal grinding water tank for unloading; however, since no boiling tower wastewater discharge port is designed for each distillation tower, the wastewater during the boiling tower period needs to be respectively connected to the boiling tower wastewater temporary metal hose from the filters, inlets and outlets, and the break of the reflux pipeline of each distillation tower and led to the tank truck. The wastewater tank truck transports a small amount of wastewater, generally about 15 tons / truck, and the time for loading and unloading the wastewater is relatively long. This not only increases the transportation cost, but also has a low transportation efficiency and cannot transport the boiling tower wastewater away in time, seriously affecting the normal operation of the boiling of each distillation tower; in addition, the temperature of the boiling tower wastewater is relatively high, and there is a risk of leakage and scalding personnel during loading and unloading. Content of the Utility Model

[0003] Aiming at the technical problems of the existing boiling tower wastewater, such as long loading and unloading time, high transportation cost and scalding personnel, the utility model provides a glycol distillation wastewater recovery system.

[0004] The utility model realizes the cooling and transportation of the boiling tower wastewater without loading and unloading by setting a wastewater collection tank, a cooler, a transfer pump and a coal grinding water tank, saves the loading and unloading time, saves costs, and reduces the risk of scalding personnel.

[0005] In order to achieve the above purpose, the technical solution adopted by the utility model is:

[0006] A glycol distillation wastewater recovery system further includes a wastewater main pipe, a wastewater collection tank, a cooler, a transfer pump and a coal grinding water tank that are connected in sequence; the wastewater main pipe is also connected to the distillation unit in glycol distillation.

[0007] The ethylene glycol rectification wastewater recovery system further includes a wastewater branch pipe; one end of the wastewater branch pipe is connected to the wastewater main pipe, and the other end of the wastewater branch pipe is connected to the rectification unit.

[0008] The rectification unit includes a rectification tower and a reboiler. One end of the reboiler is connected to the middle of the rectification tower; the other end of the reboiler is connected to the bottom of the rectification tower, and the other end of the wastewater branch pipe is connected to the connecting pipeline between the reboiler and the bottom of the rectification tower.

[0009] A wastewater drain valve is further provided on the wastewater branch pipe.

[0010] The number of the wastewater branch pipes is equal to the number of the rectification units, and both are one or more. The multiple wastewater branch pipes and the multiple rectification units are connected in one-to-one correspondence; the multiple wastewater branch pipes are all connected to the wastewater main pipe.

[0011] Further defined, a wastewater inlet valve is provided on the wastewater main pipe; the wastewater inlet valve is located between the wastewater branch pipe and the wastewater collection tank.

[0012] Further defined, the ethylene glycol rectification wastewater recovery system further includes a wastewater outlet pump provided between the wastewater collection tank and the cooler.

[0013] Further defined, a wastewater outlet valve is provided between the wastewater collection tank and the wastewater outlet pump.

[0014] Further defined, a cooler inlet valve is provided between the wastewater outlet pump and the cooler.

[0015] Further defined, the ethylene glycol rectification wastewater recovery system further includes a buffer tank provided between the cooler and the transfer pump.

[0016] Further defined, a cooler outlet valve is further provided between the cooler and the buffer tank.

[0017] The technical effect of the present utility model is:

[0018] 1. By setting a wastewater collection tank, a cooler, a transfer pump and a coal grinding water tank, the wastewater main pipe is also connected to the rectification unit in ethylene glycol rectification. Thus, the boiling tower wastewater generated by the rectification unit is uniformly collected, cooled and then transported to the coal grinding water tank for recycling by the transfer pump, without the need for loading and unloading, greatly saving the loading and unloading time and reducing the cost; by cooling and then transporting to the coal grinding water tank for recycling, the risk of scalding personnel is reduced.

[0019] 2. In the present utility model, it further includes a waste water branch pipe communicated with the main waste water pipe; the waste water branch pipe is one or more, and multiple waste water branch pipes are all communicated with the main waste water pipe; the boiling tower waste water generated by multiple ethanol rectification units in the ethylene glycol rectification production is respectively introduced into the main waste water pipe through multiple waste water branch pipes, which is convenient for unified collection and treatment, can timely transport away the boiling tower waste water, and ensure the normal operation of the steaming work of each rectification tower.

[0020] 3. In the present utility model, a waste water drain valve is arranged on the waste water branch pipe. During implementation, when the ethanol rectification unit is overhauling the boiling tower, the waste water drain valve is opened to discharge the boiling tower waste water generated by the ethanol rectification unit into the waste water collection tank through the waste water branch pipe; when the ethanol rectification unit is not overhauling the boiling tower, the waste water drain valve is closed to ensure the normal operation of the ethylene glycol rectification production.

[0021] 4. In the present utility model, a buffer tank is arranged between the cooler and the transfer pump, which plays a buffering role for the cooled waste water, avoids directly transporting it to the coal grinding water tank when the water volume is too large, increases the load of the coal grinding water tank, and ensures the stable operation of the system. Description of the Drawings

[0022] Figure 1 is the ethylene glycol rectification waste water recovery system provided by the present utility model;

[0023] Figure 2 is the connection schematic diagram of the waste water collection tank and the rectification unit;

[0024] Wherein:

[0025] 10 - rectification tower; 20 - reboiler;

[0026] 100 - waste water collection tank; 110 - main waste water pipe; 111 - waste water branch pipe; 112 - waste water drain valve; 120 - waste water inlet valve; 200 - waste water outlet valve; 300 - waste water outlet pump; 400 - cooler inlet valve; 500 - cooler; 510 - waste water inlet; 520 - circulating water inlet; 530 - circulating water outlet; 540 - waste water outlet; 600 - cooler outlet valve; 700 - buffer tank; 800 - transfer pump; 900 - coal grinding water tank. Detailed Embodiment

[0027] The following elaborates on the preferred embodiments of the present utility model in conjunction with the drawings, so that the advantages and features of the present utility model can be more easily understood by those skilled in the art, thereby making the protection scope of the present utility model more clearly defined.

[0028] Embodiment 1

[0029] See Figure 1, an ethylene glycol distillation wastewater recovery system provided in this embodiment includes a wastewater main pipe 110, a wastewater collection tank 100, a cooler 500, a transfer pump 800, and a coal grinding water tank 900 that are connected in sequence; the wastewater main pipe 110 is also connected to a distillation unit in ethylene glycol distillation.

[0030] During implementation, the boiling tower wastewater (also known as wastewater) generated by the distillation unit first flows into the wastewater collection tank 100 for collection, and then enters the cooler 500. At the same time, circulating water is introduced into the cooler 500. The circulating water exchanges heat with the boiling tower wastewater. The circulating water heats up, and the boiling tower wastewater cools down. After cooling, it is pumped into the coal grinding water tank 900 by the transfer pump 800. Since the boiling tower wastewater contains inorganic substances and alcohol ester organic substances, it can enter the coal grinding water tank 900 for storage and be used as a raw material for preparing water coal slurry. The ethylene glycol distillation wastewater recovery system provided in this embodiment can cool and transport the boiling tower wastewater without loading and unloading, saving transportation time, greatly reducing costs, realizing the transportation of the boiling tower wastewater in a timely manner, improving the transportation efficiency, and ensuring the normal operation of the cooking work in ethylene glycol distillation; the temperature of the boiling tower wastewater is reduced by the cooler 500, avoiding the risk of scalding operators, and having high safety.

[0031] See Figure 2 , in this embodiment, the distillation unit includes a distillation column 10 and a reboiler 20. One end of the reboiler 20 is connected to the middle of the distillation column 10; the other end of the reboiler 20 is connected to the bottom of the distillation column 10, and the other end of the wastewater branch pipe 111 is connected to the connecting pipe between the reboiler 20 and the bottom of the distillation column 10. A wastewater drain valve 112 is provided on the wastewater branch pipe 111.

[0032] In this embodiment, the number of wastewater branch pipes 111 is one or more, and multiple wastewater branch pipes 111 are all connected to the wastewater main pipe 110. The number of wastewater branch pipes 111 matches the number of distillation units in ethylene glycol distillation production, that is, one distillation unit matches one wastewater branch pipe 111.

[0033] Preferably, if the distillation unit includes 8, then there are eight wastewater branch pipes 111. The eight wastewater branch pipes 111 are connected to the corresponding 8 distillation units one by one, and the boiling tower wastewater generated by the 8 distillation units is respectively collected into the wastewater main pipe 110 through the wastewater branch pipes 111, and finally collected in the wastewater collection tank 100 for subsequent recovery treatment.

[0034] See Figure 2, taking the connection between one of the distillation units and the wastewater branch pipe 111 as an example, the process of connecting the tower boiling wastewater generated by the distillation unit to the wastewater collection tank 100 is explained. The distillation tower 10 and the reboiler 20 have the same axial direction, and the top of the reboiler 20 is connected to the middle of the distillation tower 10; the bottom of the reboiler 20 is connected to the bottom of the distillation tower 10, and a DN50 drainage outlet is added at the low point U-shaped bend on the liquid phase pipeline of the reboiler 20 corresponding to the distillation tower 10 (the connecting pipeline between the bottom of the reboiler 20 and the bottom of the distillation tower 10), one end of the wastewater branch pipe 111 is connected to the drainage outlet, and the other end of the wastewater branch pipe 111 is connected to the wastewater main pipe 110 through the wastewater drainage valve 112, and the tower boiling wastewater generated by the distillation unit is discharged into the wastewater collection tank 100. The connection between the remaining seven distillation units and the wastewater collection tank 100 refers to the above method.

[0035] During implementation, the wastewater branch pipe 111 is mainly used to connect the boiling tower wastewater generated by the distillation unit in the ethylene glycol distillation production with the wastewater main pipe 110, so as to facilitate the collection of the boiling tower wastewater generated by the distillation unit into the wastewater collecting tank 100; the wastewater drainage valve 112 is used to control the discharge of the boiling tower wastewater from the distillation unit, that is, when the boiling tower is overhauled, the distillation unit generates a large amount of boiling tower wastewater, at this time the wastewater drainage valve 112 is opened, and the boiling tower wastewater is discharged into the wastewater collecting tank 100 through the wastewater branch pipe 111; when the boiling tower is not overhauled, the distillation unit operates normally, at this time the wastewater drainage valve 112 is closed to ensure the normal operation of the ethylene glycol distillation production.

[0036] Example 2

[0037] See also Figure 1 On the basis of Example 1, in the ethylene glycol distillation wastewater recovery system provided in this embodiment, a wastewater inlet valve 120 is arranged on the wastewater main pipe 110; the wastewater inlet valve 120 is located between the wastewater branch pipe 111 and the wastewater collecting tank 100; when the ethylene glycol distillation production is overhauled and the boiling tower wastewater is generated, the wastewater drainage valve 112 and the wastewater inlet valve 120 are opened at the same time, and the boiling tower wastewater enters the wastewater branch pipe 111 through the wastewater drainage valve 112, and then merges into the wastewater main pipe 110, and then flows into the wastewater collecting tank 100 through the wastewater inlet valve 120.

[0038] In this embodiment, the two ends of the wastewater main pipe 110 are respectively recorded as the water inlet end and the water outlet end. The water outlet end is connected to the wastewater collecting tank 100. The water inlet end can be connected to other wastewater that can be used as water-coal slurry preparation raw materials. The distillation unit is connected to the middle end of the wastewater main pipe 110 (between the water inlet end and the water outlet end) after passing through the wastewater branch pipe 111.

[0039] The ethylene glycol distillation wastewater recovery system provided by this embodiment further includes a wastewater outlet pump 300 disposed between the wastewater collection tank 100 and the cooler 500; a wastewater outlet valve 200 is provided between the wastewater collection tank 100 and the wastewater outlet pump 300; a cooler inlet valve 400 is provided between the wastewater outlet pump 300 and the cooler 500.

[0040] In implementation, the wastewater outlet valve 200 is used to control the outflow of wastewater from the wastewater collection tank 100, and the cooler inlet valve 400 is used to control the boiling tower wastewater entering the cooler 500. During use, when the liquid level in the wastewater collection tank 100 reaches the 1 / 2 position, the wastewater outlet valve 200 and the cooler inlet valve 400 are opened. After controlling the pressure of the boiling tower wastewater to be 0.4 PMa - 0.45 PMa through the wastewater outlet pump 300, the boiling tower wastewater is pumped into the cooler 500 for cooling.

[0041] Preferably, the cooler 500 adopts a shell-and-tube structure. One path is for circulating water, and the other path is for boiling tower wastewater. These two water paths are in different channels and flow countercurrently for mass transfer, and the boiling tower wastewater is cooled through heat exchange.

[0042] Preferably, a wastewater inlet 510, a circulating water inlet 520, a circulating water outlet 530, and a wastewater outlet 540 are respectively provided on the cooler 500; the wastewater outlet pump 300 is connected to the wastewater inlet 510 through the cooler inlet valve 400, the wastewater inlet 510 is connected to the wastewater outlet 540, and the wastewater outlet 540 is connected to the coal grinding water tank 900 through a transfer pump 800; the circulating water inlet 520 is connected to the circulating water outlet 530. The boiling tower wastewater enters from the wastewater inlet 510 and flows axially from the left side to the circulating water outlet 530 on the right side along the cooler 500; the circulating water enters from the circulating water inlet 520 and flows radially from the right side to the circulating water outlet 530 on the left side along the cooler 500. The boiling tower wastewater and the circulating water flow countercurrently in different channels to achieve heat exchange; the cooled boiling tower wastewater flows out from the wastewater outlet 540 and is sent to the coal grinding water tank 900 for reuse through the transfer pump 800.

[0043] Embodiment 3

[0044] See Figure 1 Based on Embodiment 1 or Embodiment 2, the ethylene glycol distillation wastewater recovery system provided by this embodiment further includes a buffer tank 700 disposed between the cooler 500 and the transfer pump 800.

[0045] During implementation, a cooler water outlet valve 600 is also provided between the cooler 500 and the buffer tank 700; the cooled boiling tower wastewater is first discharged into the buffer tank 700 for caching through the cooler water outlet valve 600, and then by controlling the flow rate of the transfer pump 800, it is avoided that a large amount of the cooled boiling tower wastewater in the wastewater collection tank 100 all enters the coal grinding water tank 900, increasing the load of the subsequent system, ensuring the continuous and stable boiling tower wastewater entering the coal grinding water tank 900, and guaranteeing the normal operation of the system.

[0046] The ethylene glycol rectification wastewater recovery system provided by the present utility model processes the boiling tower wastewater (about 245 tons) generated during the boiling tower period. The boiling tower time is 3 days and 19 hours (a total of 91 hours). If the boiling tower wastewater is transported by tanker trucks (3 tanker trucks), the boiling tower time is 8 days; the boiling tower time is shortened by about 4 days, thereby improving the wastewater treatment efficiency and accelerating the progress of the maintenance work; at the same time, since the present utility model does not require tanker trucks, the unit price of a tanker truck is 0.1560 ten thousand yuan per day. Calculated according to 4 days, 3 tanker trucks can save 1.872 ten thousand yuan in costs; in addition, since 1.0 Mpa (40 t / h) steam is consumed every day during the boiling tower period, if the boiling tower time is shortened by about 4 days (96 h), calculated at a unit price of 50 yuan / t for 1.0 MPa steam, the cost saved is 40 t / h * 0.005 ten thousand yuan / t = 0.2 ten thousand yuan / h, and the steam cost can be saved by 19.2 ten thousand yuan; therefore, for one boiling tower, a total of 21.072 ten thousand yuan in costs can be saved.

[0047] In summary, the ethylene glycol rectification wastewater recovery system provided by the present utility model can not only shorten the boiling tower time, improve the treatment efficiency, realize the recycling of wastewater, but also generate significant economic benefits and has great application prospects.

[0048] The above are only the embodiments of the present utility model, and do not limit the protection scope of the present utility model accordingly. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of the present invention, or directly or indirectly applied to other related technical fields, shall be equally included in the patent protection scope of the present utility model.

Claims

1. A glycol distillation wastewater recovery system, characterized in that, It includes a waste water main pipe (110), a waste water collection tank (100), a cooler (500), a transfer pump (800) and a coal grinding water tank (900) which are connected in sequence; the waste water main pipe (110) is also connected to the rectification unit in ethylene glycol rectification; The ethylene glycol rectification waste water recovery system further includes a waste water branch pipe (111); one end of the waste water branch pipe (111) is connected to the waste water main pipe (110), and the other end of the waste water branch pipe (111) is connected to the rectification unit; The rectification unit includes a rectification tower (10) and a reboiler (20), one end of the reboiler (20) is connected to the middle of the rectification tower (10); the other end of the reboiler (20) is connected to the bottom of the rectification tower (10), and the other end of the waste water branch pipe (111) is connected to the connecting pipe between the reboiler (20) and the bottom of the rectification tower (10).

2. The ethylene glycol rectification wastewater recovery system according to claim 1, wherein A waste water drain valve (112) is also provided on the waste water branch pipe (111).

3. The ethylene glycol rectification wastewater recovery system according to claim 2, wherein The number of the waste water branch pipes (111) is equal to the number of the rectification units, and both are one or more. The multiple waste water branch pipes (111) and the multiple rectification units are connected in one-to-one correspondence; the multiple waste water branch pipes (111) are all connected to the waste water main pipe (110).

4. The ethylene glycol rectification wastewater recovery system according to claim 3, wherein A waste water inlet valve (120) is provided on the waste water main pipe (110); the waste water inlet valve (120) is located between the waste water branch pipe (111) and the waste water collection tank (100).

5. The ethylene glycol rectification wastewater recovery system according to any one of claims 1-4, characterized in that, The ethylene glycol rectification waste water recovery system further includes a waste water outlet pump (300) provided between the waste water collection tank (100) and the cooler (500).

6. The ethylene glycol distillation wastewater recovery system according to claim 5, characterized in that, A waste water outlet valve (200) is provided between the waste water collection tank (100) and the waste water outlet pump (300); a cooler inlet valve (400) is provided between the waste water outlet pump (300) and the cooler (500).

7. The ethylene glycol rectification wastewater recovery system according to claim 6, characterized in that, The ethylene glycol rectification waste water recovery system further includes a buffer tank (700) provided between the cooler (500) and the transfer pump (800).

8. The ethylene glycol rectification wastewater recovery system according to claim 7, wherein A cooler outlet valve (600) is also provided between the cooler (500) and the buffer tank (700).

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