A method and system for utilizing steam produced as a byproduct of ethylene glycol distillation

Abstract

This invention discloses a system and method for utilizing by-product steam from ethylene glycol distillation, belonging to the field of chemical energy conservation technology. The system includes an ethylene glycol distillation system comprising first and second ethylene glycol distillation units; a low-pressure steam pipeline network with first, second, and third steam treatment branches; the first branch connects to an air-cooling system; the second branch connects the first ethylene glycol distillation unit to a steam upgrading system, with the outlet of the steam upgrading system connected to a first heat-requiring device via a medium-pressure steam pipeline network; the third branch connects the second ethylene glycol distillation unit to the second heat-requiring device. The method includes pressurizing the low-pressure by-product steam from the first ethylene glycol distillation unit and then conveying it to the first heat-requiring device, and directly conveying the low-pressure by-product steam from the second ethylene glycol distillation unit to the second heat-requiring device. This invention achieves cascade utilization of by-product steam, avoids energy waste, and fills gaps in the pipeline network.

Description

Technical Field

[0001] This invention relates to the field of energy-saving technology in the chemical industry, specifically to a method and system for utilizing steam produced as a byproduct of ethylene glycol distillation. Background Technology

[0002] The coal-to-ethylene glycol production process typically includes multiple stages such as ethylene glycol distillation and dimethyl oxalate distillation. During operation, the dehydrogenation column of the ethylene glycol distillation unit continuously produces low-pressure steam as a byproduct from its top waste boiler. Taking a typical production scale as an example, about half of the low-pressure steam produced by the waste boiler of a single ethylene glycol distillation unit is used in the reboiler of the methanol recovery tower within the unit, with the remainder being surplus steam. For large plants with multiple ethylene glycol distillation units, the total latent heat of this surplus low-pressure steam is considerable. In existing technologies, this surplus low-pressure steam is usually directly fed to an air-cooling system for condensation to recover the condensate, but a large amount of latent heat in the steam is wasted, and the operation of the air-cooling system also consumes a significant amount of electricity.

[0003] On the other hand, the plant's steam network suffers from a supply-demand imbalance. The steam drum of the ethylene glycol synthesis unit was originally one of the main steam sources for the plant's medium-pressure steam network. When the medium-pressure steam produced by this steam drum is repurposed for direct supply to other processes due to process optimization, a significant steam supply gap will occur in the medium-pressure steam network. To maintain stable network pressure and ensure the normal operation of downstream heat-consuming equipment, the plant has to fill this gap by reducing pressure and supplementing steam from higher-pressure networks or by starting auxiliary boilers. This undoubtedly increases the consumption of high-grade steam and overall operating costs.

[0004] In summary, the existing technology presents a contradictory situation where there is surplus waste of low-pressure steam and a shortage of medium-pressure steam. It fails to achieve tiered energy utilization based on differences in steam quality, resulting in low overall energy efficiency, which urgently needs to be optimized. Summary of the Invention

[0005] The purpose of this invention is to provide a method and system for utilizing steam produced as a byproduct of ethylene glycol distillation, so as to overcome the technical problems of energy waste and pipeline supply and demand imbalance caused by the lack of cascade utilization of low-pressure steam produced as a byproduct of ethylene glycol distillation in the prior art.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: This invention provides a system for utilizing steam produced as a byproduct of ethylene glycol distillation, comprising: An ethylene glycol distillation system, comprising a first ethylene glycol distillation unit and a second ethylene glycol distillation unit; The low-pressure steam network includes a first steam treatment branch, a second steam treatment branch, and a third steam treatment branch; The first steam treatment branch is connected to an air-cooling system, which is used to transport low-pressure steam to the air-cooling system for condensation. The second steam treatment branch is connected at one end to the first ethylene glycol distillation unit and at the other end to a steam upgrading system. The outlet of the steam upgrading system is connected to the first heat-requiring equipment through a medium-pressure steam pipeline network and outputs steam at a first pressure value. The third steam treatment branch is connected at one end to the second ethylene glycol distillation unit and at the other end to the second heat-requiring equipment, which outputs steam at the second pressure value.

[0007] According to one embodiment of the present invention, the first ethylene glycol distillation apparatus includes a first dealcoholization column and a first waste pot connected to the first dealcoholization column, and the second ethylene glycol distillation apparatus includes a second dealcoholization column and a second waste pot connected to the second dealcoholization column; the first waste pot is connected to the second steam treatment branch through a pipeline, and the second waste pot is connected to the third steam treatment branch through a pipeline.

[0008] According to one embodiment of the present invention, the steam upgrading system connected to the second steam treatment branch is a steam upgrading compressor with inlet guide vane adjustment or frequency conversion adjustment function.

[0009] According to one embodiment of the present invention, it further includes a deoxygenated water replenishment pipeline, which is connected to the inlet of the steam upgrading compressor.

[0010] According to one embodiment of the present invention, the steam transport distance between the steam upgrading compressor and the first ethylene glycol distillation unit is less than the steam transport distance between the steam upgrading compressor and other ethylene glycol distillation units.

[0011] According to one embodiment of the present invention, the system further includes a first supplementary pipeline and a second supplementary pipeline; the steam pressure value output by the first supplementary pipeline is greater than a first pressure value, and the first supplementary pipeline is connected to a medium-pressure steam network for supplementing steam to the medium-pressure steam network when the steam upgrading system fails; the steam pressure value output by the second supplementary pipeline is greater than a second pressure value, and the second supplementary pipeline is connected to a second heat-requiring device for supplementing steam to the second heat-requiring device when the steam output of the third steam processing branch is abnormal.

[0012] According to one embodiment of the present invention, a first control valve is provided on the first steam treatment branch, a second control valve is provided on the second steam treatment branch, and a third control valve is provided on the third steam treatment branch, which are respectively used to control the on / off state of each branch.

[0013] According to one embodiment of the present invention, the air-cooling system connected to the first steam treatment branch is mounted on an air-cooling island, and the condensate outlet of the air-cooling system is connected to a condensate pipe network.

[0014] According to one embodiment of the present invention, the second heat-requiring device is an ethanol separation device, which includes an ethanol product tower reboiler and an ethanol concentration tower reboiler. Both the ethanol product tower reboiler and the ethanol concentration tower reboiler are high-efficiency reboilers adapted to the steam heating requirements of the second pressure value.

[0015] This invention also provides a method for utilizing ethylene glycol distillation by-product steam, applied to the ethylene glycol distillation by-product steam utilization system of the above embodiments, comprising the following steps: The low-pressure steam produced by the first ethylene glycol distillation unit is pressurized by the steam upgrading system and then transported to the first heat-requiring equipment through the medium-pressure steam pipeline network. The low-pressure steam produced as a byproduct of the second ethylene glycol distillation unit is directly transported to the second heat-requiring equipment via the third steam treatment branch. When the second or third steam treatment branch malfunctions, the low-pressure steam produced by the corresponding ethylene glycol distillation unit is switched to the first steam treatment branch for condensation.

[0016] Compared with the prior art, the present invention has the following beneficial technical effects: This invention provides a system for utilizing steam produced as a byproduct of ethylene glycol distillation. By setting up a first ethylene glycol distillation unit and a second ethylene glycol distillation unit, and configuring a steam upgrading system and a second steam processing branch consisting of a medium-pressure steam pipeline network for the first ethylene glycol distillation unit, the low-pressure steam produced as a byproduct of the first ethylene glycol distillation unit is pressurized and then transported to a first heat-requiring device that requires medium-pressure steam. This effectively fills the gap in the medium-pressure steam pipeline network caused by adjustments to the steam supply source, avoiding the additional consumption of high-grade steam. Simultaneously, a third steam processing branch is configured for the second ethylene glycol distillation unit, directly connected to the second heat-requiring device, directly transporting the low-pressure steam produced as a byproduct of the second ethylene glycol distillation unit to the second heat-requiring device adapted to low-pressure steam. This replaces the high-grade steam originally provided by the medium-pressure steam pipeline network, eliminating the latent heat waste caused by direct air-cooling and condensation of the low-pressure steam. This system uses three branches to differentiate the low-pressure steam produced by the two ethylene glycol distillation units, matching steam of different qualities to corresponding energy use scenarios. This fundamentally solves the problem of unreasonable energy utilization in existing technologies, where low-pressure steam waste and medium-pressure steam shortage coexist.

[0017] This invention also provides a method for utilizing by-product steam from ethylene glycol distillation. By pressurizing the low-pressure steam produced by the first ethylene glycol distillation unit through a steam upgrading system and then integrating it into a medium-pressure steam network, the low-pressure steam originally consumed by the air-cooling system is converted into medium-pressure steam that can fill gaps in the network. This recovers the latent heat of the steam and solves the problem of insufficient steam supply in the medium-pressure network. Simultaneously, the low-pressure steam produced by the second ethylene glycol distillation unit is directly transported to the second heat-demanding equipment, allowing the heating scenarios that previously relied on high-grade steam to be met by low-pressure steam, avoiding excessive consumption of high-grade steam. When the second or third steam processing branch malfunctions, the corresponding steam is switched to the first steam processing branch for condensation, ensuring a reliable and safe outlet for the system under any operating condition. This method, through two parallel and differentiated processing steps and a backup guarantee mechanism, achieves full and efficient utilization of low-pressure steam produced by multiple ethylene glycol distillation units and ensures safe system operation, solving the problems of energy waste and network supply-demand imbalance caused by the mismatch between steam quality and energy demand. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of a system for utilizing steam from ethylene glycol distillation byproducts in an embodiment of the present invention.

[0019] Figure 2 This is a schematic diagram of a method for utilizing steam produced as a byproduct of ethylene glycol distillation in an embodiment of the present invention.

[0020] In the diagram, 100 is the ethylene glycol distillation system; 101 is the low-pressure steam network; 102 is the first deethanolination tower; 103 is the first waste heat boiler; 104 is the second deethanolination tower; 105 is the second waste heat boiler; 200 is the first steam treatment branch; 201 is the air-cooling system; 202 is the condensate network; 300 is the second steam treatment branch; 301 is the steam upgrading system; 302 is the medium-pressure steam network; 303 is the first heat-requiring equipment; 400 is the third steam treatment branch; and 401 is the second heat-requiring equipment. Detailed Implementation

[0021] During ethylene glycol production, the waste boiler of the distillation unit's alcohol removal column continuously produces low-pressure steam as a byproduct. Some of this surplus steam is typically wasted after condensation by the air-cooling system. Simultaneously, adjustments to the steam supply source lead to significant gaps in the medium-pressure steam network, requiring the additional consumption of high-grade steam to fill these gaps, resulting in inefficient energy utilization.

[0022] Based on the above background, this invention proposes a system and method for utilizing by-product steam from ethylene glycol distillation. By configuring two differentiated processing branches—one for upgrading and conveying, and the other for direct utilization—for two ethylene glycol distillation units, and retaining an air-cooling system as a backup, the system achieves cascaded utilization of low-pressure steam. This scheme involves pressurizing the by-product steam from the first ethylene glycol distillation unit and integrating it into the medium-pressure pipeline network to fill the gap, while directly conveying the by-product steam from the second ethylene glycol distillation unit to heat-using equipment adapted to low-pressure steam. This avoids the waste of latent heat caused by air cooling and solves the problems of insufficient steam supply from the medium-pressure pipeline network and excessive consumption of high-grade steam.

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0025] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installed," "equipped with," "sleeved / connected," "connected," etc., should be interpreted broadly. For example, "connection" 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 an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0026] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a number" means two or more, unless otherwise explicitly specified.

[0027] Example 1 ReferenceFigure 1 As shown, a system for utilizing ethylene glycol distillation by-product steam provided by the present invention includes: Ethylene glycol distillation system 100 includes a first ethylene glycol distillation unit and a second ethylene glycol distillation unit; The low-pressure steam pipeline network 101 includes a first steam treatment branch 200, a second steam treatment branch 300, and a third steam treatment branch 400. The first steam processing branch 200 is connected to an air-cooling system 201, which is used to transport low-pressure steam to the air-cooling system for condensation. The second steam treatment branch 300 is connected at one end to the first ethylene glycol distillation unit and at the other end to a steam upgrading system 301. The outlet of the steam upgrading system 301 is connected to the first heat-requiring equipment 303 through a medium-pressure steam pipeline network 302 and outputs steam at a first pressure value. The third steam treatment branch 400 is connected at one end to the second ethylene glycol distillation unit and at the other end to the second heat-requiring device 401, which outputs steam at a second pressure value.

[0028] In this specific embodiment, a complete architecture for differentiated treatment of low-pressure steam produced as a byproduct from multiple ethylene glycol distillation units is constructed by setting up an ethylene glycol distillation system 100, a low-pressure steam network 101, and three steam treatment branches with different functions. The ethylene glycol distillation system 100, comprising a first ethylene glycol distillation unit and a second ethylene glycol distillation unit, continuously produces low-pressure steam as a byproduct during production. This low-pressure steam is collected in the low-pressure steam network 101. The low-pressure steam network 101 serves as a hub for steam distribution, introducing the received low-pressure steam into the first steam treatment branch 200, the second steam treatment branch 300, and the third steam treatment branch 400, respectively.

[0029] The first steam treatment branch 200 connects to the air-cooled system 201, serving as the system's regular processing path and backup safety guarantee. When other branches are not in operation or malfunction, low-pressure steam can enter the air-cooled system 201 via the first steam treatment branch 200 for condensation, preventing the steam from having nowhere to go and causing system risks. After condensing the steam, the air-cooled system 201 forms condensate, which can be further recycled.

[0030] The second steam processing branch 300 connects the first ethylene glycol distillation unit to the steam upgrading system 301, forming a supply path for the demand for high-quality steam. Low-pressure steam, a byproduct of the first ethylene glycol distillation unit, is fed into the steam upgrading system 301 via the second steam processing branch 300. This system pressurizes the low-pressure steam to a first pressure value, which is then transported to the first heat-requiring device 303 via the medium-pressure steam network 302. The first pressure value is preferably 0.5 MPaG. The first heat-requiring device 303 is a heat-using device requiring 0.5 MPaG steam, such as the reboiler of the ethanol product tower or the reboiler of the ethanol concentration tower. This path converts low-pressure steam, which might otherwise be wasted by the air-cooling system, into high-quality energy that can fill the gap in the medium-pressure steam network, achieving improved steam quality and efficiency.

[0031] The third steam processing branch 400 connects the second ethylene glycol distillation unit and the second heat-requiring device 401, forming a supply path for direct utilization of low-pressure steam. Low-pressure steam, a byproduct of the second ethylene glycol distillation unit, is directly transported to the second heat-requiring device 401 via the third steam processing branch 400, outputting steam at a second pressure value. The second pressure value is preferably 0.15 MPaG, and the second heat-requiring device 401 is a heat-using device capable of directly utilizing 0.15 MPaG low-pressure steam. This path achieves direct substitution of high-grade steam with low-pressure steam, avoiding excessive consumption of high-grade steam.

[0032] The three steam processing branches operate independently yet collaboratively within the system. The second and third steam processing branches, 300 and 400 respectively, cater to different energy demands, ensuring that steam of varying qualities is matched to appropriate heating scenarios. The first steam processing branch, 200, serves as a backup path, providing a safety net for the system. Through this architecture, the system achieves the cascaded utilization of low-pressure steam produced as a byproduct from multiple ethylene glycol distillation units. This not only meets the supplementary steam requirements of the medium-pressure steam network but also provides alternative energy sources for heating equipment that can directly utilize low-pressure steam, effectively solving the problem of simultaneous low-pressure steam waste and medium-pressure steam shortages in existing technologies.

[0033] Example 2 Based on Example 1, this example further describes in detail the specific composition of the first ethylene glycol distillation unit and the second ethylene glycol distillation unit, the steam upgrading system 301 connected to the second steam treatment branch 300, and related auxiliary structures.

[0034] The first ethylene glycol distillation unit includes a first dealcoholization column 102 and a first waste pot 103 connected to the first dealcoholization column 102. The second ethylene glycol distillation unit includes a second dealcoholization column 104 and a second waste pot 105 connected to the second dealcoholization column 104. The first dealcoholization column 102 and the second dealcoholization column 104 are the core distillation equipment in the two ethylene glycol distillation units, respectively, used to remove alcohol components from the ethylene glycol material. The first waste pot 103 and the second waste pot 105 are respectively connected to the corresponding dealcoholization column, utilizing the heat from the top material of the dealcoholization column to produce low-pressure steam as a byproduct. The first waste pot 103 is connected to the second steam treatment branch 300 through a pipeline, conveying the low-pressure steam produced by the first ethylene glycol distillation unit to the second steam treatment branch 300; the second waste pot 105 is connected to the third steam treatment branch 400 through a pipeline, conveying the low-pressure steam produced by the second ethylene glycol distillation unit to the third steam treatment branch 400. This connection enables the directional distribution of by-product steam from the two ethylene glycol distillation units, allowing the by-product steam from different units to enter the corresponding processing branches according to preset paths, laying the foundation for subsequent differentiated utilization.

[0035] The steam upgrading system 301 connected to the second steam treatment branch 300 is a steam upgrading compressor, which adopts a structure with inlet guide vane adjustment or frequency conversion adjustment function. After the low-pressure steam from the first ethylene glycol distillation unit enters the steam upgrading compressor, the compressor performs work on the steam through impeller rotation, raising the steam pressure from a second pressure value to a first pressure value. In this embodiment, the second pressure value is 0.15 MPaG, and the first pressure value is 0.5 MPaG. Since the operating load of the ethylene glycol distillation unit may fluctuate with production plan adjustments, the amount of steam from the first waste boiler 103 will also change accordingly. The steam upgrading compressor has inlet guide vane adjustment or frequency conversion adjustment function, enabling real-time monitoring of inlet steam parameters and outlet steam pressure, dynamically adjusting the compressor's operating state, ensuring a stable outlet pressure under different load conditions, and ensuring that the upgraded steam meets the usage requirements of the medium-pressure steam network. This adaptive adjustment capability allows the steam upgrading system to adapt to fluctuations in upstream steam volume, improving the system's operational stability and reliability.

[0036] In this embodiment, the ethylene glycol distillation by-product steam utilization system also includes a deoxygenated water replenishment pipeline connected to the inlet of the steam upgrading compressor. When the low-pressure steam produced by the first ethylene glycol distillation unit enters the steam upgrading compressor, the deoxygenated water replenishment pipeline replenishes a certain amount of deoxygenated water to the compressor inlet. Deoxygenated water refers to boiler feedwater that has undergone deoxygenation treatment to remove dissolved oxygen, and its replenishment to the steam serves to regulate steam parameters. On the one hand, the addition of deoxygenated water can regulate the humidity of the steam, preventing wet steam from corroding the compressor blades; on the other hand, the deoxygenated water is heated and vaporized in the compressor, increasing the total amount of steam and stabilizing the steam output after upgrading. Taking a typical operating condition as an example, the first ethylene glycol distillation unit produces approximately 42 t / h of 0.15 MPaG low-pressure steam as a by-product. By supplementing with approximately 3 t / h of deoxygenated water, approximately 45 t / h of 0.5 MPaG steam can be obtained after upgrading, achieving a stable increase in steam output.

[0037] To reduce heat loss during steam transport, especially in low-temperature winter environments, the steam transport distance between the steam upgrading compressor and the first ethylene glycol distillation unit is shorter than the steam transport distance between the steam upgrading compressor and other ethylene glycol distillation units. During long-distance transport, steam experiences temperature drops and partial condensation due to heat dissipation from the pipeline, leading to a decrease in steam parameters entering the compressor and affecting its operating efficiency and outlet steam quality. By placing the steam upgrading compressor near its corresponding first ethylene glycol distillation unit, the steam transport distance between the compressor and this unit is significantly shorter than the distance between the compressor and other ethylene glycol distillation units. This effectively shortens the low-pressure steam transport path, reduces heat loss along the way, and ensures that the steam parameters entering the compressor remain stable within the range of 0.15 ± 0.02 MPaG. This arrangement is particularly important in low-temperature winter environments, effectively preventing steam parameter drops due to heat loss and ensuring the stable operation of the steam upgrading system.

[0038] Through the synergistic combination of the aforementioned technical features, this embodiment constructs a complete system for steam generation, transportation, upgrading, and parameter control. The first ethylene glycol distillation unit, consisting of the first dealcoholization tower 102 and the first waste boiler 103, generates low-pressure steam, which is transported via a short-distance pipeline arranged nearby to a steam upgrading compressor with adaptive adjustment function. The compressor dynamically adapts to steam quantity fluctuations through guide vane adjustment or frequency conversion adjustment. Simultaneously, deoxygenated water is supplied to the compressor inlet via a deoxygenated water replenishment pipeline to adjust steam parameters and stabilize output. Finally, the upgraded 0.5 MPaG steam is transported to the first heat-requiring equipment 303 through the medium-pressure steam network 302. This system ensures that the low-pressure steam byproduct of the first ethylene glycol distillation unit can be efficiently and stably converted into high-quality steam, providing a reliable guarantee for filling the gap in the medium-pressure steam network.

[0039] Example 3 Based on Example 1, this example further details the specific implementation of the backup pipeline, branch control device, and air-cooling system in the ethylene glycol distillation by-product steam utilization system.

[0040] The ethylene glycol distillation by-product steam utilization system also includes a first replenishment pipeline and a second replenishment pipeline. The steam pressure output by the first replenishment pipeline is greater than a first pressure value. This first replenishment pipeline is connected to the medium-pressure steam network 302 and is used to replenish steam to the medium-pressure steam network when the steam upgrading system 301 fails. The steam upgrading system 301, as the core equipment for upgrading low-pressure steam to the first pressure value, directly affects the steam supply to the medium-pressure steam network 302. When the steam upgrading system 301 is shut down due to equipment failure, maintenance, or other reasons, the low-pressure steam by-product from the first ethylene glycol distillation unit cannot be upgraded through the second steam treatment branch 300. The medium-pressure steam network 302 will lose this steam source, causing a drop in network pressure. At this time, the first replenishment pipeline is activated to replenish the medium-pressure steam network 302 with high-pressure steam with a pressure value greater than the first pressure value, quickly balancing the network pressure through pressure reduction regulation. Taking a typical operating condition as an example, the first pressure value is 0.5 MPaG. The first supplementary pipeline can be connected to high-pressure steam of 1.7 MPaG. By adjusting the opening of the pressure reducing valve, the high-pressure steam is reduced to 0.5 MPaG and then sent to the medium-pressure steam pipeline network 302, thereby filling the steam gap caused by the shutdown of the steam upgrading system 301, maintaining the stability of the pipeline network pressure, and ensuring the normal operation of the downstream first heat-requiring equipment 303.

[0041] The second supplementary pipeline outputs steam at a pressure greater than the second pressure value. This second supplementary pipeline is connected to the second heat-requiring device 401 and is used to supplement steam to the second heat-requiring device 401 when the steam output of the third steam processing branch 400 is abnormal. The third steam processing branch 400 is responsible for directly transporting the low-pressure steam produced as a byproduct of the second ethylene glycol distillation unit to the second heat-requiring device 401. When the second ethylene glycol distillation unit is shut down for maintenance and does not produce low-pressure steam, or when the low temperature in winter causes excessive heat loss during steam transportation, resulting in insufficient calorific value of the steam delivered to the second heat-requiring device 401, the third steam processing branch 400 cannot provide sufficient steam to the second heat-requiring device 401. In this case, the second supplementary pipeline is activated to supplement the second heat-requiring device 401 with high-grade steam at a pressure greater than the second pressure value. Taking a typical operating condition as an example, the second pressure value is 0.15 MPaG. The second supplementary pipeline can be connected to high-grade steam of 0.5 MPaG, which is directly delivered to the second heat-requiring equipment 401 to ensure that the equipment can continue to operate when the steam output of the third steam processing branch 400 is abnormal, thus avoiding process interruption.

[0042] The establishment of the first and second supplementary pipelines forms a dual guarantee mechanism for the steam supply side. The first supplementary pipeline ensures the stability of the medium-pressure steam network 302, while the second supplementary pipeline ensures the stability of the second heat-requiring equipment 401. Both are designed for different fault scenarios and complement the second steam processing branch 300 and the third steam processing branch 400, jointly improving the operational reliability of the entire system.

[0043] A first control valve is installed on the first steam treatment branch 200, a second control valve is installed on the second steam treatment branch 300, and a third control valve is installed on the third steam treatment branch 400, respectively, to control the on / off state of each branch. The low-pressure steam pipeline network 101 serves as the hub for steam distribution, delivering steam to different processing terminals through the three branches. The control valves allow the system to flexibly switch the steam flow direction according to operating conditions. Under normal operating conditions, the second and third control valves are open, and the first control valve is closed, allowing the low-pressure steam produced as a byproduct of the first ethylene glycol distillation unit to enter the second steam treatment branch 300 for upgrading treatment, and the low-pressure steam produced as a byproduct of the second ethylene glycol distillation unit to enter the third steam treatment branch 400 and be directly delivered to the second heat-requiring equipment 401. When the steam upgrading system 301 malfunctions, the second control valve is closed and the first control valve is opened, switching the low-pressure steam originally entering the second steam processing branch 300 to the first steam processing branch 200 for air-cooled condensation, thus preventing the risk of pressure buildup due to the steam having nowhere to go. When the third steam processing branch 400 malfunctions or the second heat-requiring equipment 401 is under maintenance, the third control valve is closed and the first control valve is opened, switching the low-pressure steam originally entering the third steam processing branch 400 to the first steam processing branch 200 for air-cooled condensation. Through the coordinated control of the first, second, and third control valves, flexible switching of low-pressure steam between the three processing branches is achieved, enabling the system to maintain safe and stable operation under different operating conditions.

[0044] The air-cooling system 201 connected to the first steam processing branch 200 is mounted on an air-cooling island, and the condensate outlet of the air-cooling system 201 is connected to a condensate pipe network 202. As the terminal processing equipment of the first steam processing branch 200, the air-cooling system 201 uses air as the cooling medium to condense low-pressure steam. After entering the air-cooling system 201, the steam exchanges heat with the air, releases latent heat, and condenses into liquid water, i.e., condensate. This condensate is collected through the condensate outlet to the condensate pipe network 202 and finally sent to the plant's condensate recovery system for reuse. The air-cooling system 201 provides a reliable backup processing path for the system. When the second steam processing branch 300 or the third steam processing branch 400 fails to operate normally, low-pressure steam can enter the air-cooling system 201 via the first steam processing branch 200 for condensation, avoiding energy waste caused by direct steam discharge and preventing safety risks caused by steam pressure buildup.

[0045] Through the coordinated operation of the first and second supplementary pipelines, the first control valve, the second control valve, the third control valve, and the air-cooling system 201, this embodiment constructs a complete backup and safety assurance system. The first and second supplementary pipelines solve the problem of insufficient steam supply, the control valves enable flexible switching of steam flow direction, and the air-cooling system 201 provides a reliable backup processing terminal. This system ensures that the ethylene glycol distillation by-product steam utilization system can operate safely, stably, and efficiently under various operating conditions, significantly enhancing the system's engineering practical value.

[0046] Example 4 Based on Example 1, this example further details the specific implementation of the second heat-requiring device 401.

[0047] The second heat-requiring equipment 401 is an ethanol separation unit, which includes an ethanol product tower reboiler and an ethanol concentration tower reboiler. The ethanol separation unit is a crucial downstream stage in the ethylene glycol production process, used to further purify the ethanol-containing components separated during ethylene glycol distillation. Specifically, the ethanol product tower reboiler provides a heat source to the ethanol product tower, ensuring the material reaches the required temperature for separation; the ethanol concentration tower reboiler provides a heat source to the ethanol concentration tower, further increasing the concentration of the ethanol product. In the original design, both reboilers relied on a 0.5 MPaG medium-pressure steam network for steam supply, making them major consumers of high-grade steam.

[0048] Both the ethanol product tower reboiler and the ethanol concentration tower reboiler are high-efficiency reboilers adapted to the second pressure value steam heating requirement. The preferred second pressure value is 0.15 MPaG, which is the low-pressure steam pressure of the by-product from the second ethylene glycol distillation unit. A high-efficiency reboiler is a reboiler device that can provide sufficient heat even under lower steam pressure conditions by increasing the heat exchange area, optimizing the heat exchange tube structure, or adopting enhanced heat transfer technology. Compared with conventional reboilers, high-efficiency reboilers have lower steam pressure requirements under the same heat load demand, and can fully utilize the latent heat of low-pressure steam to complete the heating task. By replacing the ethanol product tower reboiler and the ethanol concentration tower reboiler with high-efficiency reboilers adapted to 0.15 MPaG steam, the heating scenario that originally required 0.5 MPaG high-grade steam can be met by using the low-pressure steam produced as a by-product of the second ethylene glycol distillation unit. Taking a typical production scale as an example, the reboiler of the ethanol product tower consumes about 11 t / h of steam during operation, and the reboiler of the ethanol concentration tower consumes about 4 t / h of steam. The two reboilers consume a total of about 15 t / h of steam. Through the technical solution of this embodiment, this 15 t / h of steam can be directly replaced by low-pressure steam, achieving effective savings in high-grade steam.

[0049] The 0.15 MPaG low-pressure steam, a byproduct of the second ethylene glycol distillation unit, is transported to the ethanol separation unit via the third steam treatment branch 400, entering the reboilers of the ethanol product tower and the ethanol concentration tower. In the high-efficiency reboiler, the low-pressure steam exchanges heat with the medium inside the tower, releasing latent heat and condensing into liquid water, i.e., condensate. Since this condensate is generated during the low-pressure steam heating process, its pressure is approximately 0.15 MPaG, lower than the pressure requirement of the plant's existing 0.5 MPaG condensate pipeline network, and therefore cannot be directly integrated into the medium-pressure condensate pipeline network for recovery. To address this issue, this embodiment includes a condensate collection tank and a condensate transfer pump downstream of the ethanol separation unit. The condensate collection tank, located downstream of the ethanol product tower and the ethanol concentration tower reboiler, collects the low-pressure condensate discharged from both reboilers. The condensate transfer pump is connected to the outlet of the condensate collection tank, and its outlet is connected to the condensate recovery system of the ethylene glycol distillation unit. After the low-pressure condensate is collected in the condensate collection tank, the condensate is pressurized by the condensate transfer pump to increase its pressure to a level that meets the inlet requirements of the condensate recovery system of the ethylene glycol distillation unit. The pressurized condensate is then transported to the condensate recovery system for reuse.

[0050] To prevent liquid accumulation in the pipeline during long-distance steam transportation, which could affect transportation efficiency, a condensate trap is installed on the pipeline connecting the second ethylene glycol distillation unit and the second heat-requiring equipment 401. During the transportation of low-pressure steam, a byproduct of the second ethylene glycol distillation unit, to the ethanol separation unit via the third steam treatment branch 400, some steam condenses due to heat dissipation in the pipeline, forming liquid. The condensate trap is located at the lowest point along the pipeline, using gravity to collect the condensate. The condensate outlet of the condensate trap is connected to a condensate collection tank, which transports the collected condensate to the condensate collection tank. Together with the condensate discharged from the reboiler, the condensate is pressurized by a condensate transfer pump and sent to the condensate recovery system of the ethylene glycol distillation unit. The condensate trap effectively prevents liquid accumulation in the pipeline from obstructing steam flow, ensuring the smoothness and stability of low-pressure steam transportation.

[0051] Through the synergistic combination of the aforementioned technical features, this embodiment constructs a complete system for the direct utilization of low-pressure steam and the recovery of condensate. The 0.15 MPaG low-pressure steam, a byproduct of the second ethylene glycol distillation unit, is transported to the ethanol separation unit via the third steam treatment branch 400, and enters a high-efficiency reboiler adapted to the heating requirements of low-pressure steam, replacing the original 0.5 MPaG high-grade steam to complete the heating task. The low-pressure condensate generated after heating, as well as the condensate accumulated during pipeline transportation, are collected by condensate collection tanks and condensate bags, respectively. After being pressurized by the condensate transfer pump, they are sent to the condensate recovery system of the ethylene glycol distillation unit, realizing a closed-loop recycling of the energy medium. This system solves both the problem of replacing high-grade steam and the problem of recovering low-pressure condensate, enabling the full and efficient utilization of the low-pressure steam byproduct of the second ethylene glycol distillation unit, further improving the overall energy efficiency of the ethylene glycol distillation byproduct steam utilization system.

[0052] Example 5 This embodiment provides a method for utilizing steam produced as a byproduct of ethylene glycol distillation. This method is applied to the ethylene glycol distillation byproduct steam utilization system described in any one of Embodiments 1 to 4 above, and includes the following steps: The low-pressure steam produced by the first ethylene glycol distillation unit is pressurized by the steam upgrading system 301 and then transported to the first heat-requiring equipment 303 through the medium-pressure steam pipeline network 302.

[0053] The low-pressure steam produced as a byproduct of the second ethylene glycol distillation unit is directly transported to the second heat-requiring equipment 401 via the third steam treatment branch 400.

[0054] When the second steam treatment branch 300 or the third steam treatment branch 400 malfunctions, the low-pressure steam produced by the corresponding ethylene glycol distillation unit is switched to the first steam treatment branch 200 for condensation treatment.

[0055] In this specific embodiment, the method achieves differentiated treatment and safe operation of low-pressure steam produced as a byproduct of multiple ethylene glycol distillation units through the coordinated operation of three steps.

[0056] The first step involves processing the low-pressure steam produced as a byproduct of the first ethylene glycol distillation unit. During production, the first ethylene glycol distillation unit continuously generates low-pressure steam, which is fed into the steam upgrading system 301 via the second steam processing branch 300. The steam upgrading system 301 pressurizes the low-pressure steam to a level that meets the requirements of the medium-pressure steam network 302, i.e., the first pressure value. The pressurized steam is then transported to the first heat-requiring equipment 303 via the medium-pressure steam network 302. The first heat-requiring equipment 303 is heat-using equipment that requires steam at the first pressure value, including but not limited to the reboiler of the ethanol product tower and the reboiler of the ethanol concentration tower. This step converts the low-pressure steam, which might otherwise be wasted by the air-cooling system, into high-quality energy that can fill the gap in the medium-pressure steam network, thus recovering the latent heat of the steam and solving the problem of insufficient steam supply in the medium-pressure network caused by adjustments to the steam source.

[0057] The second step involves processing the low-pressure steam produced as a byproduct of the second ethylene glycol distillation unit. During production, the second ethylene glycol distillation unit continuously generates low-pressure steam, which is directly supplied to the second heat-requiring device 401 via the third steam processing branch 400. The second heat-requiring device 401 is a heat-using device that can directly utilize low-pressure steam at a second pressure value, including but not limited to an ethanol separation unit and its included ethanol product tower reboiler and ethanol concentration tower reboiler. This step directly utilizes the low-pressure steam produced as a byproduct of the second ethylene glycol distillation unit for heat-using scenarios that previously relied on a medium-pressure steam network to provide high-grade steam, achieving a direct substitution of high-grade steam with low-pressure steam and avoiding excessive consumption of high-grade steam.

[0058] The third step is a safety assurance step, used to handle abnormal operating conditions. When the second steam processing branch 300 cannot operate normally due to equipment failure, maintenance, or other reasons, the low-pressure steam produced as a byproduct of the first ethylene glycol distillation unit cannot be sent to the steam upgrading system 301 for processing; when the third steam processing branch 400 cannot operate normally due to equipment failure, maintenance, or other reasons, the low-pressure steam produced as a byproduct of the second ethylene glycol distillation unit cannot be delivered to the second heat-requiring equipment 401. In this case, the low-pressure steam produced as a byproduct of the corresponding ethylene glycol distillation unit is switched to the first steam processing branch 200 and enters the air-cooling system 201 for condensation. After condensation, the air-cooling system 201 forms condensate, which is sent to the plant's condensate recovery system through the condensate pipeline network 202. This step provides an alternative processing path for the steam, avoiding the risk of pressure buildup caused by the steam having nowhere to go due to a failure of the main branch, and ensuring the safe operation of the system.

[0059] The three steps are independent yet coordinated. The first and second steps correspond to two different energy demands: medium-pressure pipeline steam replenishment and low-pressure heat user steam supply. This ensures that steam of different qualities is matched to the corresponding heat application scenarios, achieving full and efficient utilization of the by-product low-pressure steam. The third step serves as a safety guarantee, intervening when the first or second step fails to execute properly, ensuring a reliable steam processing path for the system under any operating condition. Through the organic combination of these three steps, this method fundamentally solves the problem of energy waste and pipeline supply-demand imbalance caused by the mismatch between steam quality and energy demand, while simultaneously ensuring the system's operational safety and reliability.

[0060] Example 6 This embodiment takes a production plant with three ethylene glycol distillation units as an example to illustrate the complete implementation plan for energy-saving renovation using the ethylene glycol distillation by-product steam utilization system of the present invention.

[0061] The plant originally had three ethylene glycol distillation units, designated as the first, second, and third ethylene glycol distillation units. Each unit's waste boiler in the deethanolination tower continuously produced 0.15 MPaG of low-pressure steam as a byproduct during production, with a single unit producing 84 t / h of steam. Of this, 42 t / h was used in the reboiler of the methanol recovery tower within the unit, and the remaining 42 t / h was surplus steam. The total surplus steam from the three units reached 126 t / h. In the original process design, this surplus steam was directly fed to the air-cooled island for condensation, and then recycled into the condensate network, resulting in a significant waste of latent heat and increased electricity consumption for the air-cooling system. On the other hand, because the 0.5MPaG steam by-product from the ethylene glycol synthesis unit's steam drum is planned to be used directly by the DMO (dimethyl oxalate) distillation unit, a steam shortage of about 100t / h has appeared in the plant's 0.5MPaG medium-pressure steam pipeline network. This requires additional consumption of higher-grade steam to make up for the shortfall, which significantly increases energy costs.

[0062] To address the above problems, the ethylene glycol distillation by-product steam utilization system of this invention is adopted for modification. The specific solution is as follows: The first ethylene glycol distillation unit is used as a device connected to the second steam treatment branch 300, the second ethylene glycol distillation unit is used as a device connected to the third steam treatment branch 400, and the third ethylene glycol distillation unit serves as a backup regulating device. The first ethylene glycol distillation unit includes a first dealcoholization column 102 and a first waste pot 103 connected thereto, which is connected to the second steam treatment branch 300 via a pipeline; the second ethylene glycol distillation unit includes a second dealcoholization column 104 and a second waste pot 105 connected thereto, which is connected to the third steam treatment branch 400 via a pipeline; the third ethylene glycol distillation unit includes a third dealcoholization column and a third waste pot connected thereto, and the low-pressure steam outlet of the third waste pot can be selectively connected to either the second steam treatment branch 300 or the first steam treatment branch 200.

[0063] The low-pressure steam network 101 serves as a steam collection and distribution hub, connecting to the low-pressure steam outlets of the first waste boiler 103, the second waste boiler 105, and the third waste boiler, and branching out into three steam processing branches. The first steam processing branch 200 connects to the air-cooling system 201, which is mounted on an air-cooling island. The condensate outlet of the air-cooling system 201 connects to the condensate network 202. The second steam processing branch 300 connects to the steam upgrading system 301, which is a steam upgrading compressor with guide vanes at the inlet. Its outlet connects to the first heat-requiring device 303 via the medium-pressure steam network 302. The third steam processing branch 400 directly connects to the second heat-requiring device 401. A first control valve, a second control valve, and a third control valve are respectively installed at the connections of the first steam processing branch 200, the second steam processing branch 300, and the third steam processing branch 400 to the low-pressure steam network 101.

[0064] The steam upgrading compressor is located near the first ethylene glycol distillation unit, making the steam delivery distance between it and the first waste boiler 103 significantly shorter than the distance between it and other ethylene glycol distillation units. The steam upgrading compressor inlet is also connected to a deoxygenated water supply line for replenishing deoxygenated water to the inlet of the steam upgrading compressor.

[0065] The ethylene glycol distillation by-product steam utilization system is also equipped with a first supplementary pipeline and a second supplementary pipeline. The first supplementary pipeline is connected to a 1.7 MPaG high-pressure steam source and then to the medium-pressure steam network 302; the second supplementary pipeline is connected to a 0.5 MPaG steam source and then to the second heat-requiring equipment 401.

[0066] The second heat-requiring equipment 401 is an ethanol separation unit, which includes a reboiler for the ethanol product tower and a reboiler for the ethanol concentration tower. Both reboilers are high-efficiency reboilers adapted to the heating requirements of 0.15 MPaG low-pressure steam. Downstream of the ethanol separation unit are a condensate collection tank and a condensate transfer pump. The condensate collection tank is connected to the condensate outlets of the two reboilers, and the outlet of the condensate transfer pump is connected to the condensate recovery system of the ethylene glycol distillation unit. On the delivery pipeline of the third steam processing branch 400, condensate collection trays are installed at low points along the route, and the condensate outlets of these trays are also connected to the condensate collection tanks.

[0067] Under normal operating conditions, the second and third control valves are open, while the first control valve is closed. 42 t / h of 0.15 MPaG low-pressure steam, a byproduct of the first ethylene glycol distillation unit, enters the steam upgrading compressor via the second steam treatment branch 300. Simultaneously, approximately 3 t / h of deoxygenated water is supplied to the inlet of the steam upgrading compressor via the deoxygenated water makeup line. The steam upgrading compressor dynamically adapts to steam volume fluctuations through its inlet guide vane adjustment function, boosting the low-pressure steam to 0.5 MPaG, resulting in a stable steam output of 45 t / h after upgrading. This portion of steam is transported to the first heat-requiring equipment 303 via the medium-pressure steam network 302, including the ethanol product tower reboiler, the ethanol concentration tower reboiler, and other 0.5 MPaG heat-requiring equipment, effectively filling the approximately 100 t / h gap in the medium-pressure steam network. The 42 t / h of 0.15 MPaG low-pressure steam, a byproduct of the second ethylene glycol distillation unit, is transported to the ethanol separation unit via the third steam treatment branch 400. Of the total steam output, 15 t / h enters the reboilers of the ethanol product tower and the ethanol concentration tower, directly replacing the original 0.5 MPaG steam for heating. The remaining 27 t / h of steam can be temporarily left unused or switched to the first steam treatment branch 200 for air-cooled condensation as needed. The low-pressure condensate discharged from the two high-efficiency reboilers flows by gravity into the condensate collection tank. The condensate accumulated in the pipeline during the transport process in the third steam treatment branch 400 is collected by condensate collection bags along the way and also sent to the condensate collection tank. The condensate in the condensate collection tank is pressurized by the condensate transfer pump and then transported to the condensate recovery system of the ethylene glycol distillation unit, realizing a closed-loop circulation of condensate.

[0068] When the steam upgrading compressor malfunctions and shuts down, immediately close the second control valve and open the first control valve to switch the low-pressure steam, a byproduct of the first ethylene glycol distillation unit, to the first steam treatment branch 200, where it enters the air-cooling system 201 for condensation, preventing steam pressure buildup and potential safety risks. Simultaneously, start the first supplementary pipeline, adjusting the opening of the 1.7 MPaG steam pressure reducing valve to supplement steam to the medium-pressure steam network 302, quickly balancing the network pressure and ensuring the normal operation of the downstream first heat-requiring equipment 303.

[0069] When the second ethylene glycol distillation unit is shut down for maintenance and does not produce low-pressure steam, or when the calorific value of the steam delivered to the ethanol separation unit is insufficient due to low winter temperatures, the third control valve is closed and the first control valve is opened. This switches the steam from the original third steam treatment branch 400 to the first steam treatment branch 200 for air cooling and condensation. Simultaneously, the second supplementary pipeline is started to supply 0.5 MPaG of steam to the reboiler of the ethanol product tower and the reboiler of the ethanol concentration tower, ensuring continuous operation of the ethanol separation unit and preventing process interruption.

[0070] The third ethylene glycol distillation unit serves as a backup regulating device, with its waste heat boiler low-pressure steam outlet selectively connected to either the second steam treatment branch 300 or the first steam treatment branch 200. When the pressure gap in the medium-pressure steam network 302 is significant or the load on the steam upgrading compressor of the first ethylene glycol distillation unit is low, the connecting valve between the third ethylene glycol distillation unit and the second steam treatment branch 300 is opened, allowing the low-pressure steam produced by the third ethylene glycol distillation unit to also be fed into the steam upgrading compressor. After pressurization, it is then integrated into the medium-pressure steam network 302 to further fill the gap. When the pressure in the medium-pressure steam network 302 is stable or the load on the steam upgrading compressor is high, the steam produced by the third ethylene glycol distillation unit is switched to the first steam treatment branch 200 for air-cooled condensation. Through the dynamic regulation of the third ethylene glycol distillation unit, the system can flexibly adapt to changes in steam supply and demand under different operating conditions, achieving optimal balance of the entire plant's steam system.

[0071] After implementation, this embodiment achieved significant energy-saving and economic benefits. The first ethylene glycol distillation unit's upgrading and supplementary network path increased annual steam production by 360,000 tons of 0.5 MPaG, generating annual steam revenue of 25.2 million yuan. After deducting electricity and water consumption, the annual net benefit was 10.315 million yuan. The second ethylene glycol distillation unit's replacement and consumption-reducing path saved 120,000 tons of 0.5 MPaG steam annually, generating annual steam revenue of 8.4 million yuan. Simultaneously, the reduced load on the air-cooling system saved electricity, resulting in an annual net benefit of 8.7514 million yuan. The comprehensive annual net benefit was 19.0664 million yuan, with a total project investment of approximately 15 million yuan and a payback period of approximately 0.79 years. This scheme filled a 100t / h gap in the 0.5 MPaG medium-pressure steam network, avoiding additional consumption of high-grade steam and optimizing the plant's overall energy structure. The system retained the original air-cooling process as a backup and set up a first and second supplementary pipeline, significantly improving operational safety and reliability.

[0072] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A system for utilizing steam produced as a byproduct of ethylene glycol distillation, characterized in that, include: An ethylene glycol distillation system (100) includes a first ethylene glycol distillation unit and a second ethylene glycol distillation unit; The low-pressure steam network (101) includes a first steam treatment branch (200), a second steam treatment branch (300), and a third steam treatment branch (400); The first steam processing branch (200) is connected to an air-cooling system (201) for conveying low-pressure steam to the air-cooling system for condensation. The second steam treatment branch (300) is connected at one end to the first ethylene glycol distillation unit and at the other end to a steam upgrading system (301). The outlet of the steam upgrading system (301) is connected to the first heat-requiring equipment (303) through a medium-pressure steam pipeline network (302) and outputs steam at a first pressure value. The third steam treatment branch (400) is connected at one end to the second ethylene glycol distillation unit and at the other end to the second heat-requiring equipment (401) and outputs steam at the second pressure value.

2. The ethylene glycol distillation by-product steam utilization system according to claim 1, characterized in that, The first ethylene glycol distillation apparatus includes a first dealcoholization column (102) and a first waste pot (103) connected to the first dealcoholization column (102); the second ethylene glycol distillation apparatus includes a second dealcoholization column (104) and a second waste pot (105) connected to the second dealcoholization column (104). The first waste boiler (103) is connected to the second steam treatment branch (300) via a pipeline, and the second waste boiler (105) is connected to the third steam treatment branch (400) via a pipeline.

3. The ethylene glycol distillation by-product steam utilization system according to claim 1, characterized in that, The steam upgrading system (301) connected to the second steam treatment branch (300) is a steam upgrading compressor with inlet guide vane adjustment or frequency conversion adjustment function.

4. The ethylene glycol distillation by-product steam utilization system according to claim 3, characterized in that, It also includes a deoxygenated water replenishment pipeline, which is connected to the inlet of the steam upgrading compressor.

5. The ethylene glycol distillation by-product steam utilization system according to claim 3, characterized in that, The steam transport distance between the steam upgrading compressor and the first ethylene glycol distillation unit is less than the steam transport distance between the steam upgrading compressor and other ethylene glycol distillation units.

6. The ethylene glycol distillation by-product steam utilization system according to claim 1, characterized in that, It also includes a first supplementary pipeline and a second supplementary pipeline; The steam pressure value output by the first supplementary pipeline is greater than the first pressure value. The first supplementary pipeline is connected to the medium-pressure steam network (302) and is used to supplement steam to the medium-pressure steam network (302) when the steam upgrading system (301) fails. The steam pressure value output by the second supplementary pipeline is greater than the second pressure value. The second supplementary pipeline is connected to the second heat-requiring device (401) and is used to supplement steam to the second heat-requiring device (401) when the steam output of the third steam processing branch (400) is abnormal.

7. The ethylene glycol distillation by-product steam utilization system according to claim 1, characterized in that, A first control valve is provided on the first steam treatment branch (200), a second control valve is provided on the second steam treatment branch (300), and a third control valve is provided on the third steam treatment branch (400), which are used to control the on / off state of each branch respectively.

8. The ethylene glycol distillation by-product steam utilization system according to claim 1, characterized in that, The air-cooling system (201) connected to the first steam treatment branch (200) is mounted on the air-cooling island, and the condensate outlet of the air-cooling system (201) is connected to the condensate pipe network (202).

9. The ethylene glycol distillation by-product steam utilization system according to claim 1, characterized in that, The second heat-requiring device (401) is an ethanol separation device, which includes an ethanol product tower reboiler and an ethanol concentration tower reboiler. Both the ethanol product tower reboiler and the ethanol concentration tower reboiler are high-efficiency reboilers adapted to the second pressure value steam heating requirements.

10. A method for utilizing steam produced as a byproduct of ethylene glycol distillation, applied to the ethylene glycol distillation byproduct steam utilization system according to any one of claims 1 to 9, characterized in that, Includes the following steps: The low-pressure steam produced by the first ethylene glycol distillation unit is pressurized by the steam upgrading system (301) and then transported to the first heat-requiring equipment (303) through the medium-pressure steam pipeline network (302); The low-pressure steam produced by the second ethylene glycol distillation unit is directly transported to the second heat-requiring equipment (401) via the third steam treatment branch (400); When the second steam treatment branch (300) or the third steam treatment branch (400) malfunctions, the low-pressure steam produced by the corresponding ethylene glycol distillation unit is switched to the first steam treatment branch (200) for condensation treatment.

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