System for reducing organic acid enrichment of ethylene glycol device

Abstract

The utility model discloses a system for reducing organic acid enrichment of an ethylene glycol device. The system comprises an evaporation tower system, a vacuum effect evaporation tower, a dehydration tower, an MEG tower, an MEG circulating tower, a DEG tower, a TEG tower, an MEG circulating tower injection pump system, a TEG separating tower injection pump system, a hot well, a hot well pump, a circulating water discharge cooler, a water treatment unit, a recirculating water storage tank and a circulating water pump. The evaporation tower system is sequentially connected in series with the bottoms of the vacuum effect evaporation tower, the dehydration tower, the MEG tower, the MEG circulating tower, the DEG tower and the TEG tower through pipelines, an MEG circulating tower condenser at the top of the MEG circulating tower is communicated with the hot well after passing through an MEG circulating tower injection pump system, and a DEG product cooler at the top of the DEG tower is communicated with the hot well after passing through a TEG separation tower injection pump system; a TEG tower condenser at the top of the TEG tower passes through a TEG separation tower injection pump system and then is communicated with a hot well, the hot well passes through a hot well pump and then is communicated with a circulating water discharge cooler, and the circulating water discharge cooler sequentially passes through a water treatment unit, a recirculating water storage tank and a circulating water pump through pipelines and then is communicated with an evaporation tower system.

Description

Technical Field

[0001] The utility model relates to the technical field of chemical device process corrosion prevention, in particular to a system for reducing organic acid enrichment in an ethylene glycol device. Background Art

[0002] The ethylene glycol unit is a typical chemical unit. Its process principle is to oxidize ethylene and oxygen to generate ethylene oxide (EO) under the action of a silver catalyst, and then absorb water, strip, remove CO2, and hydrate to generate ethylene glycol. The concentration of ethylene glycol generated by the reaction is relatively low, and then it is evaporated / dehydrated and ethylene glycol concentrated through a multi-effect evaporator and a dehydration tower in sequence, and then sent to the ethylene glycol refining unit to obtain ethylene glycol products. While ethylene is oxidized to generate EO, EO will also isomerize to acetaldehyde, which will quickly oxidize to CO2 and H2O, accompanied by the generation of a small amount of by-products such as formic acid and acetic acid. These acids enter the downstream and pose a corrosion threat to related unit equipment. In an aqueous environment, carbon steel equipment and pipelines are severely electrochemically corroded, and in an anhydrous environment, the high-temperature chemical corrosion of the ethylene glycol refining unit is severe. Judging from the current operation of domestic ethylene glycol units, corrosion is particularly common in the high-temperature parts of the reboiler of the multi-effect steam system, the multi-effect condensate tank, and the tower kettle of the refining system. The corrosion problem is still the main problem affecting the long-term operation of the unit, and reducing the concentration of organic acids in the system is the main way to slow down the corrosion.

[0003] Chinese patent document CN106866363B discloses a large-scale synthetic gas preparation device and method for ethylene glycol, the invention discloses a large-scale synthetic gas preparation device and method for ethylene glycol, the gas outlet of the methanol rectification washing tower is connected to the gas inlet of the esterification tower, the heavy components after the reaction of the esterification tower are transported to the carbonylation reactor, the residual liquid of the esterification tower is discharged, the gas inlet of the carbonylation reactor is connected to the gas outlet of the esterification tower, the heavy components after the reaction of the carbonylation reactor are transported to the methanol rectification washing tower, the dimethyl oxalate at the discharge port of the dimethyl oxalate rectification tower is heated and vaporized and connected to the gas inlet of the hydrogenation reactor, the gas outlet of the hydrogenation reactor is discharged, the ethylene glycol refining tower is connected to the discharge port of the ethylene glycol distillation device, the gas outlet of the ethylene glycol distillation device is connected to the esterification tower, and the waste liquid of the ethylene glycol distillation device is discharged. Reduce the number of device series, reduce the number of equipment units, reduce engineering investment, reduce the generation of side reactions, and reduce consumption.

[0004] In the prior art, it is difficult for organic acids (formic acid and acetic acid) in the evaporation system to be discharged from the device along with steam or the recombinant components diethylene glycol and triethylene glycol. They mainly circulate in the pipelines of each tower along with the system, corroding the circulating system equipment and affecting the production of products. Utility Model Content

[0005] In view of the shortcomings of the prior art, the present invention provides a system for reducing the enrichment of organic acids in an ethylene glycol device, with the purpose of providing a simple and rapid method for leading the main corrosive medium all the way to a special water treatment unit (deacidification, dealdehyde treatment) for treatment through the transformation of part of the process route, and then returning it to the process system, and discharging all or part of the organic acid-rich materials in the hot well to the water treatment unit, thereby reducing the circulation amount of organic acids in the multiple-effect evaporation system, thereby reducing enrichment, and greatly reducing the concentration of organic acids circulating in the system without affecting the production load operation of the device and the change of product output, which can effectively reduce the risk of corrosion of the device equipment pipeline.

[0006] The technical solution adopted by the present invention is:

[0007] A system for reducing organic acid enrichment in an ethylene glycol device comprises an evaporation tower system, a vacuum effect evaporation tower, a dehydration tower, an MEG tower, an MEG circulation tower, a DEG tower, a TEG tower, an MEG circulation tower jet pump system, a TEG separation tower jet pump system, a hot well, a hot well pump, a circulating water discharge cooler, a water treatment unit, a recirculating water storage tank and a circulating water pump; the evaporation tower system is connected in series with the vacuum effect evaporation tower, the dehydration tower, the MEG tower, the MEG circulation tower, the DEG tower and the bottom pipe openings of the TEG tower in sequence through pipelines; a MEG circulation tower condenser at the top of the MEG circulation tower is connected to the hot well via the MEG circulation tower jet pump system; a DEG product cooler at the top of the DEG tower is connected to the hot well via the TEG separation tower jet pump system; a TEG tower condenser at the top of the TEG tower is connected to the hot well via the TEG separation tower jet pump system; the hot well is connected to the circulating water discharge cooler via the hot well pump; and the circulating water discharge cooler is connected to the evaporation tower system via pipelines in sequence via the water treatment unit, the recirculating water storage tank and the circulating water pump;

[0008] As a preferred technical solution of the utility model, the evaporation tower system includes a first-effect evaporation tower, a second-effect evaporation tower, a third-effect evaporation tower, a fourth-effect evaporation tower, a fifth-effect evaporation tower, and a sixth-effect evaporation tower connected in series in sequence through pipelines;

[0009] As the preferred technical solution of the utility model, the bottoms of the first-effect evaporation tower, the second-effect evaporation tower, the third-effect evaporation tower, the fourth-effect evaporation tower, the fifth-effect evaporation tower, the sixth-effect evaporation tower, the vacuum-effect evaporation tower, the dehydration tower, the MEG tower, the MEG circulation tower, the DEG tower and the TEG tower are all provided with pipelines for reflux of the tower body;

[0010] As a preferred technical solution of the utility model, the top of the first-effect evaporation tower is connected to the de-aldehyde tower through a pipeline via a second-effect reboiler condenser, and then connected in series with a fourth-effect reboiler condenser, a fifth-effect reboiler condenser, a sixth-effect reboiler condenser, and a vacuum effect reboiler condenser after passing through a third-effect reboiler condenser; the top of the second-effect evaporation tower is connected to the third-effect reboiler condenser through a pipeline, the top of the third-effect evaporation tower is connected to the fourth-effect reboiler condenser through a pipeline, the top of the fourth-effect evaporation tower is connected to the fifth-effect reboiler condenser through a pipeline, and the top of the fifth-effect evaporation tower is connected to the sixth-effect reboiler condenser through a pipeline;

[0011] As a preferred technical solution of the utility model, the top of the vacuum effect evaporation tower is connected to the tower body through a pipeline through the evaporator hot water tank and then refluxed;

[0012] As a preferred technical solution of the utility model, the top of the dehydration tower is divided into two branches through a pipeline through the dehydration tower hot well, the first branch is refluxed and connected to the tower body, and the second branch is connected to the sewage treatment device;

[0013] As a preferred technical solution of the utility model, the top of the MEG tower passes through the MEG tower condenser and the MEG tower reflux tank in sequence through a pipeline and then refluxes to connect to the tower body; the MEG tower is connected to the product MEG storage tank through a pipeline;

[0014] As a preferred technical solution of the utility model, the MEG circulation tower is connected to the vacuum effect evaporation tower through a pipeline for mid-stage reflux;

[0015] As a preferred technical solution of the utility model, the TEG tower is connected to the DEG tower through a pipeline, and the DEG tower is connected to the product DEG storage tank through a pipeline;

[0016] As a preferred technical solution of the utility model, the TEG tower body is connected to the product TEG through a pipeline, and the TEG tower bottom is connected to the polyethylene glycol storage tank through a pipeline.

[0017] Compared with the prior art, the utility model has the following beneficial effects:

[0018] Based on the locations where organic acids are enriched and the distribution of formic acid and acetic acid, this system removes organic acids from the enriched locations without changing the original process. The acids are then returned to the system, and the concentration of organic acid radicals and total acid values ​​circulating in the system are effectively reduced by tracking and detecting changes in the concentration of corrosion-related media. At the same time, the pH value in the system is increased, which effectively improves the corrosion environment of the device, reduces the risk of equipment corrosion, and eliminates safety hazards.

[0019] The method has a simple, reasonable, and reliable process, is easy to implement on site, and has obvious effects, and has a certain promotion effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is the process flow chart of the production equipment of this system.

[0021] In the figure:

[0022]

[0023] DETAILED DESCRIPTION

[0024] The following will be combined with the implementation of the utility model to clearly and completely describe the technical solutions in the implementation of the utility model. Obviously, the described implementation is only a part of the implementation of the utility model, not all of the implementations. Based on the implementation of the utility model, all other implementations obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0025] In the present application, monoethylene glycol is abbreviated as MEG, diethylene glycol is abbreviated as DEG, and triethylene glycol is abbreviated as TEG.

[0026] Example:

[0027] The utility model provides Figure 1 A system for reducing organic acid enrichment in an ethylene glycol device is shown, comprising an evaporation tower system, a vacuum effect evaporation tower, a dehydration tower, a MEG tower, a MEG circulation tower, a DEG tower, a TEG tower, a MEG circulation tower jet pump system, a TEG separation tower jet pump system, a hot well, a hot well pump, a circulating water discharge cooler, a water treatment unit, a recirculating water storage tank and a circulating water pump; the evaporation tower system is connected in series with the vacuum effect evaporation tower, the dehydration tower, the MEG tower, the MEG circulation tower, the DEG tower and the bottom of the TEG tower through pipelines, the MEG circulation tower condenser at the top of the MEG circulation tower is connected to the hot well via the MEG circulation tower jet pump system, the DEG product cooler at the top of the DEG tower is connected to the hot well via the TEG separation tower jet pump system, the TEG tower condenser at the top of the TEG tower is connected to the hot well via the TEG separation tower jet pump system, the hot well is connected to the circulating water discharge cooler via the hot well pump, and the circulating water discharge cooler is connected to the evaporation tower system via pipelines through the water treatment unit, the recirculating water storage tank and the circulating water pump in sequence.

[0028] The liquid in the hot well F710 has a high concentration of organic acids, which comes from the top of the MEG circulation tower T630, DEG tower T710, and TEG tower T720. It is composed of condensed water produced by the steam jet pump and volatile condensable gases extracted from the distillation system. All or part of the organic acid-rich materials in the hot well F710 are discharged to the water treatment unit U550 to reduce the content of organic acids, and then connected to the evaporation tower system or vacuum effect evaporation tower T537 through pipelines to circulate in the system. (The pipeline circulation of the system is as follows Figure 1 In, ①- section, and then connect the pipeline marked "After Modification" as shown).

[0029] The top of the MEG circulation tower T630 is provided with a MEG circulation tower condenser E631, which condenses the high-temperature gaseous substances output from the pipeline at the top of the tower. After condensation, the gaseous substances are connected to the hot well F710 through the pipeline via the MEG circulation tower jet pump system J632;

[0030] A DEG product cooler E711 is provided at the top of the DEG tower T710 to condense the high-temperature gaseous substances output from the pipeline at the top of the tower. After condensation, the gaseous substances are connected to the hot well F710 through a pipeline via the TEG separation tower jet pump system J712.

[0031] The top of TEG tower T720 is provided with TEG tower condenser E721, which condenses the high-temperature gaseous substances output from the pipeline at the top of the tower, and then connects to the hot well F710 through the pipeline via the TEG separation tower jet pump system J712;

[0032] The outlet of the hot well F710 is connected to the circulating water discharge cooler E553 through a pipeline via the hot well pump G713. The cooled circulating water enters the water treatment unit U550 and the recycling water storage tank (F550) in turn, and is then connected to the evaporation tower system through the circulating water pump G550.

[0033] The evaporation tower system includes a first-effect evaporation tower T531, a second-effect evaporation tower T532, a third-effect evaporation tower T533, a fourth-effect evaporation tower T534, a fifth-effect evaporation tower T535, and a sixth-effect evaporation tower T536 which are connected in series through pipelines.

[0034] The bottoms of the first-effect evaporation tower T531, the second-effect evaporation tower T532, the third-effect evaporation tower T533, the fourth-effect evaporation tower T534, the fifth-effect evaporation tower T535, the sixth-effect evaporation tower T536, the vacuum-effect evaporation tower T537, the dehydration tower T610, the MEG tower T620, the MEG circulation tower T630, the DEG tower T710 and the TEG tower T720 are all provided with pipelines for reflux of the tower body, and heat exchangers (E531, E532, E533, E534, E535, E536, E537, E610, E620, E630, E710, E720) are provided in each loop pipe.

[0035] It should be noted that upstream of E531 is the factory’s high-pressure steam pipeline network, which is mainly used to provide heat to T531.

[0036] Comparative Example:

[0037] An ethylene glycol device comprises: a vacuum effect evaporation tower, a dehydration tower, a MEG tower, a MEG circulation tower, a DEG tower, a TEG tower, a MEG circulation tower jet pump system, a TEG separation tower jet pump system, a hot well, a hot well pump, a circulating water discharge cooler, a water treatment unit, a recirculating water storage tank and a circulating water pump; the evaporation tower system is connected in series with the vacuum effect evaporation tower, the dehydration tower, the MEG tower, the MEG circulation tower, the DEG tower and the bottom of the TEG tower in sequence through pipelines, the MEG circulation tower condenser at the top of the MEG circulation tower is connected to the hot well via the MEG circulation tower jet pump system, the DEG product cooler at the top of the DEG tower is connected to the hot well via the TEG separation tower jet pump system, the TEG tower condenser at the top of the TEG tower is connected to the hot well via the TEG separation tower jet pump system, and the hot well outlet is connected to the evaporation tower system through a pipeline.

[0038] Different from the embodiment: the outlet of the hot well F710 is directly connected to the evaporation tower system through a pipeline, and the flow direction is from the first effect evaporation tower T531, to the second effect evaporation tower T532-vacuum effect evaporation tower T537→dehydration tower T610→MEG tower T620→MEG circulation tower T630→DEG tower T710→TEG tower T720, and it keeps circulating in the system. The circulation method of the comparative example will cause the acid to be enriched in the system all the time.

[0039] The system provided by the utility model is based on the comparative example, in which the flow of the hot well liquid in the hot well F710 originally flowing to the first-effect evaporation tower T531 is switched to flow to the water treatment unit U550 for treatment, and then enters the top of the first-effect evaporation tower T531 to the vacuum effect evaporation tower T537 through the recycling water storage tank F550 for circulation.

[0040] The specific measures are as follows: the hot well fluid in the hot well F710 is partially returned to the inlet of the circulating water discharge cooler E553 through the hot well pump G713, mixed with the water treatment unit U550 (the circulating water discharge heat exchanger E552 is the outlet), and then enters the recirculating water storage tank F550 unit to remove organic acids, thereby reducing the risk of corrosion.

[0041] In the comparative example, the organic acid concentration distribution of each part is as follows:

[0042] Table 1 shows the distribution of organic acids in typical parts of the comparative examples

[0043]

[0044] Table 2 shows the distribution of organic acids in typical parts of the examples

[0045]

[0046] Table 3 shows the distribution of pH and acid value (in acetic acid) at typical locations of the embodiment.

[0047]

[0048] The effect of the embodiment is evaluated by analyzing the concentration of organic acid radicals, pH value and total acidity of each typical part of the embodiment. The organic acid radicals of each typical part of the embodiment for 24 hours are shown in Table 2. It can be seen that the effect of the embodiment is obvious, and the concentration of organic acid is reduced, indicating that the degree of enrichment of organic acid in the entire multi-effect system and ethylene glycol refining system is greatly reduced, especially the organic acid concentration of the bottom of the polyethylene glycol tower T720 is reduced by more than 90%. The acid value of the embodiment also decreases to varying degrees, and the pH value increases, which greatly improves the organic acid corrosion environment of the device.

[0049] The utility model uses the above embodiments to illustrate the technical concept of the utility model, but the utility model is not limited to the above embodiments, that is, it does not mean that the utility model must rely on the above embodiments to be implemented. Those skilled in the art should understand that the relevant improvements to the utility model fall within the protection scope and disclosure scope of the utility model.

Claims

1. A system for reducing organic acid enrichment in an ethylene glycol device, comprising an evaporation tower system, a vacuum effect evaporation tower (T537), a dehydration tower (T610), a MEG tower (T620), a MEG circulation tower (T630), a DEG tower (T710), a TEG tower (T720), a MEG circulation tower jet pump system (J632), a TEG separation tower jet pump system (J712), a hot well (F710), a hot well pump (G713), a circulating water discharge cooler (E553), a water treatment unit (U550), a recirculating water storage tank (F550) and a circulating water pump (G550); It is characterized in that The evaporation tower system is connected in series with the vacuum effect evaporation tower (T537), the dehydration tower (T610), the MEG tower (T620), the MEG circulation tower (T630), the DEG tower (T710) and the TEG tower (T720) through pipelines. The MEG circulation tower condenser (E631) at the top of the MEG circulation tower (T630) is connected to the hot well (F710) through a pipeline via a MEG circulation tower jet pump system (J632). The DEG product cooler (E711) at the top of the DEG tower (T710) is connected to the TEG separation system (J632) through a pipeline. The tower jet pump system (J712) is connected to the hot well (F710), the TEG tower condenser (E721) at the top of the TEG tower (T720) is connected to the hot well (F710) through a pipeline via the TEG separation tower jet pump system (J712), the hot well (F710) is connected to the circulating water discharge cooler (E553) through a pipeline via the hot well pump (G713), and the circulating water discharge cooler (E553) is connected to the evaporation tower system after passing through the water treatment unit (U550), the recycling water storage tank (F550) and the circulating water pump (G550) in sequence through a pipeline.

2. The system for reducing organic acid enrichment in an ethylene glycol device according to claim 1, characterized in that: The evaporation tower system includes a first-effect evaporation tower (T531), a second-effect evaporation tower (T532), a third-effect evaporation tower (T533), a fourth-effect evaporation tower (T534), a fifth-effect evaporation tower (T535), and a sixth-effect evaporation tower (T536) which are connected in series via pipelines.

3. The system for reducing organic acid enrichment in an ethylene glycol device according to claim 1, characterized in that: The bottoms of the first-effect evaporation tower (T531), the second-effect evaporation tower (T532), the third-effect evaporation tower (T533), the fourth-effect evaporation tower (T534), the fifth-effect evaporation tower (T535), the sixth-effect evaporation tower (T536), the vacuum-effect evaporation tower (T537), the dehydration tower (T610), the MEG tower (T620), the MEG circulation tower (T630), the DEG tower (T710) and the TEG tower (T720) are all provided with pipelines for reflux of the tower bodies.

4. The system for reducing organic acid enrichment in an ethylene glycol device according to claim 1, characterized in that: The top of the first-effect evaporation tower (T531) is connected to the aldehyde removal tower (T560) through a pipeline via the second-effect reboiler condenser (D532), and then connected in series with the fourth-effect reboiler condenser (D534), the fifth-effect reboiler condenser (D535), the sixth-effect reboiler condenser (D536), and the vacuum effect reboiler condenser (D537) after passing through the third-effect reboiler condenser (D533); the top of the second-effect evaporation tower (T532) is connected to the third-effect reboiler condenser (D533) through a pipeline, the top of the third-effect evaporation tower (T533) is connected to the fourth-effect reboiler condenser (D534) through a pipeline, the top of the fourth-effect evaporation tower (T534) is connected to the fifth-effect reboiler condenser (D535) through a pipeline, and the top of the fifth-effect evaporation tower (T535) is connected to the sixth-effect reboiler condenser (D536) through a pipeline.

5. The system for reducing organic acid enrichment in an ethylene glycol device according to claim 1, characterized in that: The top of the vacuum effect evaporation tower (T537) is connected to the tower body through a pipeline via the evaporator hot water tank (F536) and then refluxes.

6. The system for reducing organic acid enrichment in an ethylene glycol device according to claim 1, characterized in that: The top of the dehydration tower (T610) is divided into two branches through a pipeline via a dehydration tower hot well (F610), the first branch is refluxed and connected to the tower body, and the second branch is connected to a sewage treatment device.

7. The system for reducing organic acid enrichment in an ethylene glycol device according to claim 1, characterized in that: The top of the MEG tower (T620) passes through the MEG tower condenser (E621) and the MEG tower reflux tank (D621) in sequence through a pipeline and then refluxes to the tower body; the MEG tower (T620) is connected to the product MEG storage tank through a pipeline.

8. The system for reducing organic acid enrichment in an ethylene glycol device according to claim 1, characterized in that: The MEG circulation tower (T630) is connected to the vacuum effect evaporation tower (T537) through a pipeline for mid-stage reflux.

9. The system for reducing organic acid enrichment in an ethylene glycol device according to claim 1, characterized in that: The TEG tower (T720) is connected to the DEG tower (T710) through a pipeline, and the DEG tower (T710) is connected to the product DEG storage tank through a pipeline.

10. The system for reducing organic acid enrichment in an ethylene glycol device according to claim 1, characterized in that: The body of the TEG tower (T720) is connected to the product TEG through a pipeline, and the bottom of the TEG tower (T720) is connected to the polyethylene glycol storage tank through a pipeline.

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