Online flushing device and method for ethylene glycol steam three-stage jet vacuum pump

Abstract

The invention discloses an ethylene glycol steam three-stage jet vacuum pump on-line flushing device and method. The ethylene glycol steam three-stage jet vacuum pump on-line flushing device comprises an EG on-line flushing pipeline and a switch valve arranged on the EG on-line flushing pipeline, wherein the two ends of the EG on-line flushing pipeline are connected with an EG conveying system and a steam main pipe of an air inlet of a first-stage ethylene glycol steam jet pump respectively; the EG online flushing pipeline is provided with an EG buffering mechanism, and the EG buffering mechanism is provided with an air pressure compensation mechanism. Hot EG in the EG buffer mechanism is injected into the steam main pipe through the air pressure compensation mechanism to flush the first-stage ethylene glycol steam jet pump, so that a nozzle of the first-stage ethylene glycol steam jet pump, an inlet vacuum pipeline and an outlet vacuum pipeline can realize pressure stabilization control after automatic air pressure compensation in the online flushing process; therefore, the vacuum fluctuation in the vacuum pipeline is small, and meanwhile the flushing effect is improved.

Description

Technical Field

[0001] The invention relates to the technical field of polyester production equipment, and in particular to an online flushing device and method for an ethylene glycol steam three-stage jet vacuum pump. Background Art

[0002] Steam jet pumps utilize the principle of conversion between static and dynamic pressure energy during fluid flow to pump and deliver fluids. They primarily consist of a nozzle, mixing chamber, diffuser, cooler, and steam supply system. To achieve a higher vacuum, steam jet pumps can be connected in multiple stages in series. In a multi-stage series jet system, the airflow ejected by the first-stage ejector contains not only the pumped gas but also the working steam of that stage, increasing the load on the next stage. To reduce steam consumption in the next stage, a condenser can be installed between the two jet stages to condense most of the condensable vapor in the mixed gas.

[0003] In polyester production, ethylene glycol steam three-stage jet vacuum pump is a commonly used vacuum system, such as Figure 1 As shown, it mainly includes a first-stage ethylene glycol steam jet pump, a first-stage condenser, a second-stage ethylene glycol steam jet pump, a second-stage condenser, a third-stage ethylene glycol steam jet pump and a third-stage condenser; Power gas steam delivery system: used to deliver power steam to each glycol steam injection pump of the ethylene glycol steam three-stage injection system as a negative pressure power source, wherein each glycol steam injection pump is connected to the power gas steam delivery system through a main air pipe, and a compensation air pipe with a power steam compensation valve is provided between the first-level glycol steam injection pump and the second-level glycol steam injection pump and the main air pipe; after long-term operation, scaling is easily formed on the nozzle and inlet and outlet vacuum pipelines of the glycol steam injection pump, affecting the normal operation and vacuum pumping effect of the system, especially at the nozzle and inlet and outlet vacuum pipelines of the first-level glycol steam injection pump. Once the structure is serious and the vacuum degree fluctuates too much, it will have a direct impact on the quality of the product.

[0004] Therefore, at present, the main air pipe of the first-stage ethylene glycol steam jet pump is connected in series with the EG delivery system through a flushing pipeline and a switch valve. After the switch valve is opened, the hot EG is directly flushed into the air inlet and nozzle of the first-stage ethylene glycol steam jet pump for high-pressure flushing. However, after the hot EG used for flushing enters, since the hot EG is rushed into at positive pressure and the vacuum pipeline is at negative pressure, the EG needs to ensure a certain flow rate to achieve the flushing effect. Therefore, after a large amount of EG flows in under high pressure, it will cause fluctuations in the internal vacuum pressure, because the over-pressure hot EG will cause the vacuum pressure to fluctuate after entering the vacuum system. When the vacuum pressure in the first-stage ethylene glycol steam jet pump fluctuates, the secondary and tertiary vacuum pressures will also fluctuate due to the vacuum pipeline pressure of the previous stage. Fluctuations will cause an impact, so once the first-stage ethylene glycol steam jet pump is flushed by over-pressure hot EG, this direct flushing method will cause the vacuum degree in the vacuum pipeline of the third-stage jet vacuum pump to fluctuate too much, so that the vacuum pipeline cannot ensure constant and equal pressure internal pressure, which will eventually affect product quality. By controlling the flow rate or flow to reduce fluctuations, the flow rate and flow rate cannot be accurately controlled. When the flow rate is too fast, it is easy to cause large fluctuations in the vacuum pressure, and when the flow rate is too small, the flushing effect is not good. When the flow rate is controlled, there will also be problems of poor flushing effect or large fluctuations in vacuum pressure. Therefore, at present, the only way to reduce the impact of vacuum fluctuations on the product is to reduce the flushing frequency. Summary of the Invention

[0005] In order to solve certain technical problems existing in the prior art, one of the purposes of this application is to provide an online flushing device for a three-stage ethylene glycol steam jet vacuum pump, which can realize pressure stabilization control of the nozzle and inlet and outlet vacuum pipelines of the first-stage ethylene glycol steam jet pump by automatically compensating the air pressure during the online flushing process, thereby reducing the vacuum fluctuation inside the vacuum pipeline and improving the flushing effect.

[0006] The second purpose of this application is to provide an online flushing method for an ethylene glycol steam three-stage jet vacuum pump, which can reduce the vacuum fluctuations caused by hot EG flushing, thereby making the internal pressure of the vacuum pipeline more constant and isobaric, without affecting the product quality during the flushing process, and is easy to control during flushing.

[0007] In order to solve the above existing technical problems, one of the objectives of this application is achieved by adopting the following technical solutions: An ethylene glycol steam three-stage jet vacuum pump online flushing device comprises an EG online flushing pipeline between a steam main pipe whose two ends are respectively connected to an EG conveying system and an air inlet of a first-stage ethylene glycol steam jet pump, and a switch valve arranged on the EG online flushing pipeline. The EG online flushing pipeline is provided with an EG buffer mechanism, and the EG buffer mechanism is provided with an air pressure compensation mechanism. The air pressure compensation mechanism automatically replenishes the air pressure of the EG buffer mechanism according to Boyle's law, so that the pressure in the EG buffer mechanism and the pressure in the vacuum pipeline remain constant and close to the vacuum pressure of the production system. Then, the hot EG in the EG buffer mechanism is injected into the steam main pipe through the air pressure compensation mechanism to flush the first-stage ethylene glycol steam jet pump, thereby reducing the vacuum fluctuation caused by the hot EG flushing.

[0008] Preferably, the EG buffer mechanism includes an EG buffer tank provided on the EG online flushing pipeline, a feed valve provided at the feed end of the EG buffer tank, and a liquid level sensor provided on the EG buffer tank.

[0009] Preferably, the air pressure compensation mechanism includes a nitrogen tank, an air inlet pipe connected to the air inlet of the nitrogen tank and the nitrogen delivery system, a pressure gauge provided on the nitrogen tank, an air outlet pipe between the nitrogen tank and the EG buffer tank, a pressure regulating valve provided on the air inlet pipe, and an air outlet valve provided on the air outlet pipe.

[0010] Preferably, a controller is further included, and the liquid level sensor and the pressure gauge are connected to the controller. The current values ​​detected by the liquid level sensor and the pressure gauge can be displayed on the display on the controller, and the switch valve, feed valve, pressure regulating valve and air outlet valve are all controlled by the controller.

[0011] Preferably, the volume ratio of the nitrogen tank and the EG buffer mechanism is 2:1000±20.

[0012] Preferably, the pressure in the EG buffer mechanism is constant at 200~210Pa.

[0013] Preferably, the nitrogen pressure in the nitrogen tank is 0.1 MPa.

[0014] According to Boyle's law, the nitrogen buffer tank is used to automatically replenish the air pressure. At a pressure of 0.1MPa, 0.002 cubic meters of nitrogen gas is needed to diffuse to an atmospheric pressure of 200Pa, and the volume will become 1 cubic meter. That is to say, the pressure is close to the vacuum degree of 200Pa, so the air pressure is kept constant at 200Pa, which is close to the vacuum pressure of the production system, reducing vacuum fluctuations. After flushing, the vacuum constant pressure is stable and does not affect product quality.

[0015] The second purpose of this application is achieved by the following technical solution: An online flushing method of a glycol steam three-stage ejector vacuum pump, characterized in that: the method comprises an online flushing device of the glycol steam three-stage ejector vacuum pump, in an initial state, liquid level sensor data displayed on a screen of a controller is in a zero return state, nitrogen tank pressure displayed after pressure regulating valve control is 0.1 Mpa, and the switch valve, the feed valve and the gas outlet valve are all in a closed state; when the online flushing device is used to flush the first-stage glycol steam ejector pump, the flushing steps comprise: S1, opening the feed valve by the controller to inject hot EG in the EG delivery system into the EG buffer tank, and closing the feed valve when the hot EG liquid level in the EG buffer tank reaches a set liquid level; S2, opening the gas outlet valve by the controller to make nitrogen in the nitrogen tank enter the EG buffer tank through the gas outlet pipe, then opening the switch valve to inject hot EG in the EG buffer tank into the vacuum pipeline at the inlet end of the first-stage glycol steam ejector pump along the EG online flushing pipeline by the nitrogen pressure, and flushing the nozzle and the inlet and outlet vacuum pipelines; S3, closing the switch valve, the feed valve and the gas outlet valve again when the liquid level sensor data is in the zero return state, and completing one flushing; S4, judging the flushing effect by the opening value of the power steam compensation valve, repeating steps S1-S3 for the next round of flushing when the opening value of the power steam compensation valve does not meet the standard, and stopping until the opening value of the power steam compensation valve is normal.

[0016] Preferably, in step S2, the pressure in the nitrogen tank is kept constant by linkage of the pressure gauge and the pressure regulating valve after the gas outlet valve is opened.

[0017] Preferably, the flushing time of the first-stage glycol steam ejector pump can be set by the controller, and the flushing condition of the first-stage glycol steam ejector pump is that the opening of the power steam compensation valve is less than a set value or a fixed interval time.

[0018] Preferably, after the switch valve of the EG online flushing pipeline is opened, the valve on the steam main gas pipeline is closed, so that the inlet end of the first-stage glycol steam ejector pump is flushed by the hot EG and a negative pressure power source is formed.

[0019] Compared with the prior art, the method has the following beneficial effects: 1. All components can be added separately without flushing, and the normal operation of the glycol steam three-stage ejector vacuum pump is not affected during the adding process.

[0020] 2. According to the Boyle's law, the EG buffer mechanism is automatically supplemented with air pressure by the air pressure compensation mechanism, and then the hot EG is injected into the steam main pipe to flush the nozzle and the inner wall of the inlet and outlet vacuum pipeline of the first-stage ethylene glycol steam jet pump, so that the internal pressure of the vacuum pipeline is constant and isobaric during flushing, and the influence on product quality is small.

[0021] 3. When flushing, the internal vacuum fluctuation is reduced to a negligible level, so that the problem of product quality reduction caused by changes in vacuum fluctuation can be ignored, and the purpose of regular or immediate flushing can be achieved; both the problem of internal vacuum pressure fluctuation caused by the inflow of a large amount of hot EG under high pressure in the existing flushing method and the problem of flow and flow rate that cannot be accurately controlled caused by manual control of injection pressure through the on-off valve can be solved, so that the effect of hot EG during flushing is stable, the cleaning efficiency and the three-stage spraying effect are improved, the equipment disassembly and manual operation are reduced, and the safe and stable operation of the equipment is ensured. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 The online flushing device of the existing ethylene glycol steam three-stage jet vacuum pump in the present application; Figure 2 The online flushing device of the improved ethylene glycol steam three-stage jet vacuum pump in the present application; Figure 3 The partial enlarged view of the present application; In the figure: 1, power steam delivery system; 11, steam main pipe; 12, compensation air pipe; 13, power steam compensation valve; 2, on-off valve; 3, EG online flushing pipeline; 4, second-stage ethylene glycol steam jet pump; 5, second-stage condenser; 6, third-stage ethylene glycol steam jet pump; 7, third-stage condenser; 8, first-stage condenser; 9, first-stage ethylene glycol steam jet pump; 20, EG buffer mechanism; 21, EG buffer tank; 22, feed valve; 23, liquid level sensor; 30, air pressure compensation mechanism; 31, air inlet pipe; 32, pressure regulating valve; 33, pressure gauge; 34, nitrogen tank; 35, air outlet pipe; 36, air outlet valve; 40, controller. DETAILED DESCRIPTION

[0023] In the following, the present application will be further described in conjunction with the drawings and specific embodiments. It should be noted that the embodiments described below or the technical features thereof can be combined in any manner to form new embodiments without conflict.

[0024] In the description of this application, it should be understood that the terms "up", "down", "left", "right", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they should not be understood as limitations on this application.

[0025] The terms "first," "second," and the like in this application are used to distinguish similar objects, and are not used to describe a specific order or precedence. It should be understood that the terms used in this manner are interchangeable where appropriate, so that the embodiments of this application can be implemented in an order other than that illustrated or described herein, and that the objects distinguished by "first," "second," and the like are generally of the same type, and do not limit the number of objects; for example, the first object can be one or more. In addition, "and / or" in the specification and claims refers to at least one of the connected objects, and the character " / " generally indicates that the objects connected are in an "or" relationship. Embodiment 1:

[0026] like Figure 2 and 3 As shown, an ethylene glycol steam three-stage jet vacuum pump online flushing device includes a first-stage ethylene glycol steam jet pump 9, a first-stage condenser 8, a second-stage ethylene glycol steam jet pump 4, a second-stage condenser 5, a third-stage ethylene glycol steam jet pump 6 and a third-stage condenser 7; a steam main gas pipe 11 for conveying motive steam to each ethylene glycol steam jet pump as a negative pressure motive source and two compensation gas pipes 12 with motive steam compensation valves 13; and an EG online flushing pipeline 3 provided between the steam main gas pipe 11, the two ends of which are respectively connected to the EG conveying system and the air inlet of the first-stage ethylene glycol steam jet pump 9, and a valve 12 provided on the EG online flushing pipeline 3. The switch valve 2 on the EG is provided, and an EG buffer mechanism 20 is provided on the EG online flushing pipeline 3. The EG buffer mechanism 20 is provided with an air pressure compensation mechanism 30. The air pressure compensation mechanism 30 automatically replenishes the air pressure of the EG buffer mechanism 20 according to Boyle's law, so that the pressure in the EG buffer mechanism 20 and the pressure in the vacuum pipeline are kept constant and close to the vacuum pressure of the production system. The hot EG in the EG buffer mechanism 20 is then injected into the steam main pipe 11 through the air pressure compensation mechanism 30 to flush the primary ethylene glycol steam jet pump 9, thereby reducing the vacuum fluctuation caused by the hot EG flushing.

[0027] The application is based on the existing EG online flushing pipeline 3, and only needs to cut off the total pipeline connection port valve of the EG delivery system and the switch valve 2 on the EG online flushing pipeline 3 to realize the modification. All the added components can be added separately without flushing, and the normal operation of the ethylene glycol steam three-stage jet vacuum pump will not be affected during the installation process. After the modification is completed, when the nozzle of the first-stage ethylene glycol steam jet pump 9 and the scale on the inner wall of the front and rear vacuum pipelines need to be flushed, the air pressure compensation mechanism 30 first automatically supplements the air pressure of the EG buffer mechanism 20 according to the Boyle law, so that the pressure in the EG buffer mechanism 20 and the pressure displayed in the vacuum pipeline in the first-stage ethylene glycol steam jet pump 9 remain constant, and then the pressure is close to the vacuum pressure of the production system. The hot EG in the EG buffer mechanism 20 is injected into the steam main gas pipeline 11 through the air pressure compensation mechanism 30 to flush the nozzle of the first-stage ethylene glycol steam jet pump 9 and the inner wall of the inlet and outlet vacuum pipelines, thereby reducing the vacuum fluctuation caused by hot EG flushing, ensuring the internal pressure of the vacuum pipeline constant and isobaric during flushing, and having little effect on product quality. After flushing by this method, the problem of internal vacuum pressure fluctuation caused by a large amount of hot EG flowing under high pressure is solved, and the problem of flow and flow rate being difficult to accurately control after manually controlling the injection pressure through the switch valve 2 is solved, so that the effect of hot EG during flushing is stable, the cleaning efficiency and three-stage spraying effect are effectively improved, the equipment disassembly and manual operation are reduced, and the safe and stable operation of the equipment is ensured.

[0028] The hot EG after flushing can be recycled through the recycling system of the ethylene glycol steam three-stage jet vacuum pump, and no waste liquid is generated. After recycling in the system, the entire cleaning process can realize online circulation cleaning. After adding the EG buffer mechanism 20 and the air pressure compensation mechanism 30, the internal vacuum fluctuation is reduced to a negligible level during flushing, so that the problem of product quality reduction caused by vacuum fluctuation change can be ignored, and the purpose of regular or random flushing can be achieved.

[0029] Further improvement is that the EG buffer mechanism 20 includes an EG buffer tank 21 arranged on the EG online flushing pipeline 3, a feed valve 22 arranged at the feed end of the EG buffer tank 21, and a liquid level sensor 23 arranged on the EG buffer tank 21.

[0030] Since the pressure of the EG delivery system itself is relatively large, the hot EG is prone to cause large vacuum pressure fluctuation during flushing. Therefore, before the hot EG is flushed, it is first injected into the EG buffer tank 21 through the EG online flushing pipeline 3 for buffering. When the EG buffer tank 21 is filled to the required liquid level by the liquid level sensor 23, the feed valve 22 at the feed end is directly closed, thereby avoiding the problem that the flushing pressure is uncontrollable due to the pressure of the EG delivery system when the EG buffer tank 21 is flushed by the pressure injected by the gas pressure compensation mechanism 30. By setting a constant pressure in advance for flushing, the pressure fluctuation of the inlet of the first EG vapor jet pump 9 during flushing can be controlled, thereby keeping the internal vacuum stable. After the pressure is controlled, the problem that the hot EG is prone to cause large vacuum pressure fluctuation in the first EG vapor jet pump 9 during flushing is solved. The EG buffer tank 21 is a heat preservation tank, which can ensure the temperature of the hot EG during hot EG injection, thereby avoiding the problem of excessive temperature difference.

[0031] Further improvement is that the gas pressure compensation mechanism 30 includes a nitrogen tank 34, an inlet pipe 31 connected between the gas inlet of the nitrogen tank 34 and the nitrogen delivery system, a pressure gauge 33 arranged on the nitrogen tank 34, an outlet pipe 35 arranged between the nitrogen tank 34 and the EG buffer tank 21, a pressure regulating valve 32 arranged on the inlet pipe 31, and an outlet valve 36 arranged on the outlet pipe 35.

[0032] When the hot EG in the EG buffer tank 21 is flushed by the gas pressure compensation mechanism 30, since the pressure of the nitrogen delivery system is constant and cannot be adjusted, direct pressure flushing after connecting the inlet pipe 31 and the pressure regulating valve 32 is prone to cause pressure fluctuation. Therefore, a nitrogen tank 34 is added to the inlet pipe 31 connected to the nitrogen delivery system, an outlet valve 36 is added to the outlet pipe 35 of the nitrogen tank 34, and a pressure gauge 33 is added to the nitrogen tank 34. Through the combination of the pressure gauge 33 and the pressure regulating valve 32, the pressure in the nitrogen tank 34 can always remain constant, so that when the hot EG in the EG buffer tank 21 needs to be flushed, the constant nitrogen pressure can be directly injected into the EG buffer tank 21 as a power source for flushing. During nitrogen flushing, the injected pressure can always remain constant, thereby reducing the pressure fluctuation caused by the hot EG during flushing.

[0033] Further improvement is that a controller 40 is further included, the liquid level sensor 23 and the pressure gauge 33 are connected to the controller 40, the current values detected by the liquid level sensor 23 and the pressure gauge 33 can be displayed on the display of the controller 40, and the on-off valve 2, the feed valve 22, the pressure regulating valve 32, and the outlet valve 36 are all controlled by the controller 40.

[0034] The controller 40 can remotely control and display each valve, the liquid level sensor 23, the pressure gauge 33, etc., so as to ensure that the opening and closing of each valve is more convenient. Without affecting the normal operation of the system, efficient online circulation cleaning is achieved, and the flushing operation is less labor-intensive. The hot EG can also control its flow rate according to the scaling condition of the pipeline to improve the cleaning efficiency.

[0035] Further improvements are as follows: the volume ratio of the nitrogen tank 34 and the EG buffer mechanism 20 is 2:1000±20; the pressure in the EG buffer mechanism 20 is constant at 200~210Pa; and the nitrogen pressure in the nitrogen tank 34 is 0.1Mpa.

[0036] Since 0.002 cubic meters of nitrogen gas is required to diffuse to 1 cubic meter at a pressure of 0.1MPa and the volume becomes 1 cubic meter when the atmospheric pressure reaches 200Pa, the pressure is close to the vacuum degree of 200Pa. Flushing in this state can make the first-level ethylene glycol steam jet pump 9 stable in vacuum constant pressure after flushing through hot EG. Example 2:

[0037] A method for online flushing of a three-stage ethylene glycol steam jet vacuum pump includes an online flushing device for the three-stage ethylene glycol steam jet vacuum pump. In an initial state, the data of the liquid level sensor 23 displayed on the screen of the controller 40 is in a zero state, the pressure in the nitrogen tank 34 displayed after controlling the pressure regulating valve 32 is 0.1 MPa, and the switch valve 2, the feed valve 22, and the outlet valve 36 are all in a closed state. When the first-stage ethylene glycol steam jet pump 9 is flushed by the three-stage ethylene glycol steam jet vacuum pump online flushing device, the flushing steps include: S1. Open the feed valve 22 through the controller 40 to inject the hot EG in the EG delivery system into the EG buffer tank 21. When the hot EG liquid level in the EG buffer tank 21 reaches the set liquid level, close the feed valve 22. S2. Open the outlet valve 36 through the controller 40 to allow the nitrogen in the nitrogen tank 34 to enter the EG buffer tank 21 through the outlet pipe 35. Then open the on-off valve 2 to inject the hot EG in the EG buffer tank 21 along the EG online flushing pipeline 3 into the vacuum pipeline at the inlet end of the first-level ethylene glycol vapor injection pump 9 through the nitrogen pressure to flush the nozzle and the inlet and outlet vacuum pipelines. S3. When the data of the liquid level sensor 23 returns to zero, the switch valve 2, the feed valve 22 and the air outlet valve 36 are closed again to complete one flushing; S4. Determine the flushing effect by the opening value of the power steam compensation valve 13. When the opening of the power steam compensation valve 13 does not meet the standard, repeat steps S1 to S3 for the next round of flushing until the opening of the power steam compensation valve 13 is normal.

[0038] When flushing is performed using the above method, since the pressures of the hot EG and steam ethylene glycol flowing into the EG online flushing pipeline 3 are close to or the same, a gas-liquid mixture can be formed when the nozzle and the inner wall of the inlet and outlet vacuum pipes are flushed in the vacuum pipeline injected into the inlet end of the first-stage ethylene glycol steam jet pump 9, thereby using the liquid hot EG to flush the scaling materials on the pipe wall. Moreover, since the external pressure is controllable, the pressure fluctuation caused by the hot EG flushing on the vacuum pipeline is reduced, and the problem of excessive vacuum fluctuation difference caused by excessive hot EG injection pressure in the vacuum degree of the ethylene glycol steam three-stage jet vacuum pump is avoided, so that the quality of the product is more stable and will not be affected by vacuum fluctuations. Moreover, since the hot EG is pressurized and flushed by nitrogen, the entire flushing process is not affected by the EG delivery system. Therefore, repeated cleaning can be performed, and the problem of excessive vacuum fluctuation will not be caused during the multiple cleaning processes. Moreover, the flushing effect is associated with the power steam compensation valve 13 and is judged by the opening value of the power steam compensation valve 13. During the production process, the control of the frequency, number and timing of flushing are more flexible. The entire operation process can be directly controlled by the controller 40, and the operation difficulty is low.

[0039] As a further improvement, in step S2, after the outlet valve 36 is opened, the pressure in the nitrogen tank 34 is kept constant by the linkage of the pressure gauge 33 and the pressure regulating valve 32, which makes the adjustment of the nitrogen pressure more flexible and the fluctuation of the adjusted nitrogen pressure smaller, thereby avoiding the problem of vacuum fluctuation caused by excessive or insufficient nitrogen pressure during flushing of the hot EG.

[0040] As a further improvement, the flushing time of the first-stage ethylene glycol steam jet pump 9 can be set by the controller 40. The flushing condition of the first-stage ethylene glycol steam jet pump 9 is that the opening of the power steam compensation valve 13 is less than the set value or a fixed interval time.

[0041] During the production process, if the opening of the power steam compensation valve 13 becomes smaller, it means that the internal scaling is relatively serious. At this time, if flushing is performed again, the flushing time and the amount of hot EG required will be longer, which leads to the problem that the existing flushing scaling is prone to cause continuous pressure fluctuations. Although the improved scaling can reduce the fluctuation changes, long-term use of hot EG flushing will inevitably cause fluctuations. Therefore, in order to further reduce the impact of vacuum pressure fluctuations on the product, after the transformation, the flushing time of the first-level ethylene glycol steam jet pump 9 is no longer simply judged by the power steam compensation valve 13, but an intermittent flushing method is adopted, generally 3-5 days or once a week. One flushing is a round of one tank of hot EG described in steps S1~S3. After flushing with hot EG at this frequency, the nozzle of the first-level ethylene glycol steam jet pump 9 can always be kept in a unobstructed state, thereby reducing the continuous fluctuation problem caused by long-term hot EG flushing.

[0042] As a further improvement, after the switch valve 2 of the EG online flushing pipeline 3 is opened, the valve on the steam main pipe 11 is closed, so that the air inlet end of the first-level ethylene glycol steam jet pump 9 is completely flushed by the hot EG and forms a negative pressure power source.

[0043] When flushing with hot EG, steam is normally injected into the steam main pipe 11, thereby forming a gas-liquid mixed flushing state. In this state, it is easy for the liquid hot EG to be quickly carried away by the gaseous ethylene glycol, and the trajectory is uncertain. In this state, it is easy to cause the problem of local scaling areas not being flushed cleanly. When this phenomenon lasts for a long time, it is easy to cause the gas ejection shape from the nozzle to change. Therefore, in order to solve this problem, during flushing, the valve on the steam main pipe 11 is closed, so that the air inlet end of the first-level ethylene glycol steam jet pump 9 is completely flushed by hot EG, and the internal hot EG injection pressure forms a negative pressure power source, thereby ensuring the pressure stability of the internal vacuum pipeline and the flushing effect, making the flushing of scaling materials cleaner. After the flushing is completed, the liquid hot EG is closed by switching the valve, and the switching is completed by injecting gaseous ethylene glycol. When switching, it is only necessary to form a partial gas-liquid mixed state at the beginning and end to avoid the problem of pressure interruption.

[0044] The above-mentioned embodiments are only preferred embodiments of the present application and cannot be used to limit the scope of protection of the present application. Any non-substantial changes and replacements made by technicians in this field based on the present application shall fall within the scope of protection required by the present application.

Claims

1. An ethylene glycol steam three-stage jet vacuum pump online flushing device, comprising an EG online flushing pipeline (3) between a steam main gas pipe (11) with two ends respectively connected to an EG delivery system and an air inlet of a first-stage ethylene glycol steam jet pump (9), and an on-off valve (2) provided on the EG online flushing pipeline (3), characterized in that: The EG online flushing pipeline (3) is provided with an EG buffer mechanism (20), and the EG buffer mechanism (20) is provided with an air pressure compensation mechanism (30). The hot EG in the EG buffer mechanism (20) is injected into the steam main pipe (11) through the air pressure compensation mechanism (30) to flush the primary ethylene glycol steam jet pump (9).

2. The ethylene glycol steam three-stage jet vacuum pump online flushing device according to claim 1, characterized in that: The EG buffer mechanism (20) comprises an EG buffer tank (21) provided on the EG online flushing pipeline (3), a feed valve (22) provided at the feed end of the EG buffer tank (21), and a liquid level sensor (23) provided on the EG buffer tank (21).

3. The online flushing device of the ethylene glycol steam three-stage jet vacuum pump according to claim 2, characterized in that: The air pressure compensation mechanism (30) comprises a nitrogen tank (34), an air inlet pipe (31) provided at an air inlet of the nitrogen tank (34) and connected to a nitrogen delivery system, a pressure gauge (33) provided on the nitrogen tank (34), an air outlet pipe (35) provided between the nitrogen tank (34) and the EG buffer tank (21), a pressure regulating valve (32) provided on the air inlet pipe (31), and an air outlet valve (36) provided on the air outlet pipe (35).

4. The online flushing device of a three-stage ethylene glycol steam jet vacuum pump according to claim 3, characterized in that: The invention also includes a controller (40), the liquid level sensor (23) and the pressure gauge (33) are connected to the controller (40), and the current values ​​detected by the liquid level sensor (23) and the pressure gauge (33) can be displayed on a display on the controller (40), and the switch valve (2), the feed valve (22), the air outlet pipe (35), the pressure regulating valve (32) and the air outlet valve (36) are all controlled by the controller (40).

5. The online flushing device of the ethylene glycol steam three-stage jet vacuum pump according to claim 3, characterized in that: The volume ratio of the nitrogen tank (34) and the EG buffer mechanism (20) is 2:1000.

6. The ethylene glycol steam three-stage jet vacuum pump online flushing device according to claim 1, characterized in that: The pressure in the EG buffer mechanism (20) is constant at 200 Pa.

7. The online flushing device for a three-stage ethylene glycol steam jet vacuum pump according to claim 5, characterized in that: The nitrogen pressure in the nitrogen tank (34) is 0.1 MPa.

8. An online flushing method for a three-stage ethylene glycol steam jet vacuum pump, characterized in that: The flushing device comprises the flushing device as claimed in claims 1 to 7, wherein in an initial state, the data of the liquid level sensor (23) displayed on the screen of the controller (40) is in a zero state, the pressure in the nitrogen tank (34) displayed after controlling the pressure regulating valve (32) is 0.1 MPa, and the switch valve (2), the feed valve (22) and the outlet valve (36) are all in a closed state; when the first-stage ethylene glycol steam jet pump (9) is flushed by the ethylene glycol steam three-stage jet vacuum pump online flushing device, the flushing steps include: S1. Open the feed valve (22) through the controller (40) to inject the hot EG in the EG conveying system into the EG buffer tank (21). When the hot EG liquid level in the EG buffer tank (21) reaches the set liquid level, close the feed valve (22); S2. Open the outlet valve (36) through the controller (40) to allow the nitrogen in the nitrogen tank (34) to enter the EG buffer tank (21) through the outlet pipe (35), then open the switch valve (2), and inject the hot EG in the EG buffer tank (21) along the EG online flushing pipeline into the vacuum pipeline at the inlet end of the first-level ethylene glycol steam injection pump (9) through the nitrogen pressure, and then flush the nozzle and the inlet and outlet vacuum pipelines; S3. When the data of the liquid level sensor (23) returns to zero, the switch valve (2), the feed valve (22) and the air outlet valve (36) are closed again to complete one flushing; S4, judging the flushing effect by the opening value of the power steam compensation valve (13); when the opening value of the power steam compensation valve (13) does not meet the standard, repeating steps S1 to S3 for the next round of flushing until the opening value of the power steam compensation valve (13) is normal.

9. The online flushing method for a three-stage ethylene glycol vapor jet vacuum pump according to claim 8, characterized in that: In step S2, after the outlet valve (36) is opened, the pressure gauge (33) and the pressure regulating valve (32) are linked to ensure that the pressure in the nitrogen tank (34) is constant.

10. The online flushing method for a three-stage ethylene glycol vapor jet vacuum pump according to claim 8, characterized in that: The flushing time of the first-stage glycol steam jet pump (9) can be set automatically by the controller (40), and the flushing condition of the first-stage glycol steam jet pump (9) is that the opening of the power steam compensation valve (13) is less than the set value or the fixed interval time.

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