Preheating pipeline of pump in atmospheric and vacuum distillation unit

Abstract

The utility model provides a preheating pipeline of a machine pump in an atmospheric and vacuum distillation unit, which comprises a first pipeline and a second pipeline, the first pipeline is provided with the machine pump, and an inlet pipeline of the machine pump is provided with an inlet valve and is communicated with an upstream process pipeline through the inlet pipeline; the first pipeline is communicated with a discharge port pipeline and a downstream process pipeline on an outlet pipeline of the pump; the inlet end of the second pipeline is connected to the position, between the pump and the inlet valve, of the inlet pipeline, the outlet end of the second pipeline is connected to the discharge outlet pipeline, and the inlet end of the second pipeline is located at the high point of the inlet pipeline. By changing the position, connected with the heavy dirty oil discharging pipeline, of the inlet pipeline of the machine pump and additionally arranging the steam purging line on the inlet pipeline of the machine pump, residual heavy dirty oil in the dirty oil pipeline is purged into the heavy dirty oil tank through steam after the machine pump is filled and preheated; the problems that in the pump filling process, gas phase residues exist in a pipeline, preheating is insufficient, and heavy dirty oil is condensed to block the pipeline are solved.

Description

Technical Field

[0001] The utility model relates to the technical field of petrochemical industry, in particular to a preheating pipeline of a machine pump in a normal and low pressure distillation device. Background Art

[0002] The heavy oil medium transported by the hot oil pump generally has high viscosity and low freezing point. It will solidify at room temperature and low temperature, or even freeze the pump body pipeline, resulting in no flow or small flow and head after the pump is started, or even causing tripping. The temperature of the hot oil pump is generally around 200℃~350℃. If it is not preheated, the cold oil and condensed water in the pump body will mix with the hot oil, which will vaporize and cause the pump to be emptied; after the hot oil enters the pump body, the various parts of the pump body are unevenly heated and expand unevenly, causing leakage, cracks, etc., and will also cause the shaft to arch. Preheating the pump can effectively prevent the hot oil pump from clogging and ensure that the entire pump startup process is safe and controllable. The preheating technology of the petrochemical hot oil pump is an important means to ensure its normal operation and a necessary measure to improve production efficiency.

[0003] At present, the preheating method used by major petrochemical refineries is more suitable for small pumps. However, the traditional preheating method is no longer applicable to large vacuum residue oil pumps of tens of millions of tons of atmospheric and vacuum distillation units. The disadvantage of this method for large hot oil pumps is that there is a dead point at a high point during preheating, and incomplete preheating can easily cause the pump to be emptied.

[0004] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the utility model, and therefore may include information that does not constitute the prior art known to ordinary technicians in the field. Utility Model Content

[0005] In view of the shortcomings of the prior art mentioned above, the preheating pipeline of the machine pump in the atmospheric and vacuum distillation device of the utility model changes the position of the second pipeline connected to the inlet pipeline of the machine pump in the first pipeline for discharging heavy dirty oil, and at the same time adds a steam purge line on the inlet pipeline of the machine pump. After the machine pump is primed and preheated, the heavy dirty oil remaining in the dirty oil pipeline is purged into the heavy dirty oil tank by steam, so as to solve the problems of gas phase residue in the pipeline during the priming process, insufficient preheating and condensation of heavy dirty oil blocking the pipeline.

[0006] The utility model provides a preheating pipeline of a machine pump in a normal and low pressure distillation device, comprising a first pipeline and a second pipeline, wherein the machine pump is arranged on the first pipeline, an inlet valve is arranged on the inlet pipeline of the machine pump, and the inlet pipeline is connected with an upstream process pipeline, and the first pipeline is connected with a discharge outlet pipeline and a downstream process pipeline on the outlet pipeline of the machine pump; the inlet end of the second pipeline is connected to the inlet pipeline between the machine pump and the inlet valve of the first pipeline, and the outlet end of the second pipeline is connected to the discharge outlet pipeline of the first pipeline.

[0007] In one embodiment of the present invention, there is a height difference between the inlet pipeline and the inlet valve, and the inlet end of the second pipeline is located at a high point of the inlet pipeline.

[0008] In one embodiment of the present invention, the position of the inlet valve on the inlet pipeline is higher than the position of the pump on the inlet pipeline, and the inlet end of the second pipeline is located on a side of the inlet pipeline close to the inlet valve.

[0009] In one embodiment of the utility model, four outlet pipelines are installed on the machine pump, and two of the four outlet pipelines are respectively provided to connect the downstream process pipeline and the discharge outlet pipeline; wherein, one of the two outlet pipelines connected to the downstream process pipeline is also connected to the discharge outlet pipeline.

[0010] In one embodiment of the present invention, two outlet pipelines connected to the downstream process pipeline are arranged in parallel, and bypass pipelines are respectively arranged on the two outlet pipelines arranged in parallel.

[0011] In one embodiment of the present invention, two outlet pipes connected to the discharge pipe are respectively connected to the top and the bottom of the pump.

[0012] In one embodiment of the utility model, a steam purge pipeline is further included, wherein the outlet end of the steam purge pipeline is connected to the outlet pipeline of the first pipeline and is located on a side of the outlet pipeline connected to the downstream process pipeline.

[0013] In one embodiment of the present invention, a steam purge branch line is further connected between the second pipeline and the steam purge pipeline, and the steam purge branch line is connected to a side close to the inlet end of the second pipeline.

[0014] In one embodiment of the present invention, the steam purge branch line forms a tee at the portion connected to the second pipeline, and a stop valve is respectively provided on the three pipelines connected by the tee.

[0015] In one embodiment of the present invention, a stop valve on the steam purge branch line is further provided with a blind plate on the side facing the steam purge line.

[0016] The beneficial effects of the utility model include at least the following:

[0017] 1. The utility model provides a preheating pipeline for a machine pump in a normal and vacuum distillation device. By changing the second pipeline for discharging heavy waste oil behind the inlet valve of the machine pump from the low point position of the first pipeline in the inlet pipeline to the high point position of the first pipeline in the inlet pipeline, the first pipeline from the inlet valve to the machine pump is fully preheated, and there is no gas phase accumulation at the highest point of the first pipeline in between.

[0018] 2. By adding a steam purge line to the pipeline behind the inlet valve of the machine pump, the heavy dirty oil remaining in the dirty oil pipeline can be purged into the heavy dirty oil tank through steam after the machine pump is primed and preheated, so as to avoid the heavy dirty oil condensing in the pipeline and clogging the pipeline.

[0019] It should be understood that the above general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The drawings herein are incorporated into the specification and constitute a part of the specification, showing embodiments consistent with the present utility model, and together with the specification, are used to explain the principles of the present utility model. Obviously, the drawings described below are only some embodiments of the present utility model, and for those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative work. In the drawings:

[0021] Figure 1 It is a pipeline diagram of a preheating pipeline of a pump in an existing atmospheric and vacuum distillation device;

[0022] Figure 2 The utility model is a pipeline diagram of the preheating pipeline of the machine pump in the atmospheric and vacuum distillation device.

[0023] In the figure: 100, first pipeline; 10, machine pump; 20, inlet pipeline; 201, inlet valve; 30, upstream process pipeline; 40, outlet pipeline; 401, bypass pipeline; 50, discharge outlet pipeline; 60, downstream process pipeline; 200, second pipeline; 300, steam purge pipeline; 310, steam purge branch line; 70, stop valve; 71, blind plate. DETAILED DESCRIPTION

[0024] The following describes the implementation of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementations, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict. It should also be understood that the terms used in the embodiments of the present invention are intended to describe specific implementations, rather than to limit the scope of protection of the present invention.

[0025] See also Figure 1 to Figure 2. It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings in this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the restrictive conditions for the implementation of the utility model, so they have no substantial technical significance. Any structural modification, change in proportional relationship, or adjustment of size, without affecting the effects and purposes that can be achieved by the utility model, should still fall within the scope of the technical content disclosed by the utility model. At the same time, the terms such as position and quantitative relationship quoted in this specification are only for the convenience of description, and are not used to limit the scope of the implementation of the utility model. Changes or adjustments in their relative relationships should also be regarded as the scope of the implementation of the utility model without substantially changing the technical content.

[0026] See also Figure 1 , which is a pipeline diagram of a conventional vacuum residue pump preheating line, wherein the red line portion is the pipeline portion improved in the embodiment of the utility model, Figure 1 The hot oil pump preheating method corresponding to the overall piping diagram includes the following steps (wherein the [P] before the step represents that the step is an external and on-site operation step, and (P) represents that the step is an internal operation, that is, it is operated through the control system):

[0027] [P]-Operators can only start working after receiving instructions and making relevant preparations and wearing labor protection;

[0028] (P)-Confirm that the overhaul of pump 10 is completed, the pump body and related accessories are in good condition and clean, and the equipment professional returns the overhaul work ticket of pump 10, and the pump is ready for use;

[0029] [P]-Change the sealing oil pressure test process and slowly introduce the sealing oil pressure test exhaust;

[0030] (P)-Confirm that there is a change in the pressure on the pressure gauge on the pump;

[0031] [P]-Slightly open the pump outlet vent valve to exhaust all the air from the outlet vent valve and then close it;

[0032] (P)-Confirm that there is no leakage in the pump seal, oil seal line joint and pump flange during the oil seal pressure test;

[0033] [P]- In the absence of leakage, the seal oil is discharged to the dirty oil system using the pressure in the pump chamber;

[0034] [P]-After priming the pump, slowly open the pump inlet valve to preheat the standby pump normally and put the sealing oil into use;

[0035] [P]-During preheating, turn the pump 180 degrees every 30 to 40 minutes to prevent the pump shaft from bending due to uneven heating up and down;

[0036] (P)-Confirm that there is no problem, and slowly fully open the inlet valve 201 at a preheating rate of ≯50℃ / hour;

[0037] [P]-Contact an electrician to supply power to the pump 10;

[0038] [P]-After preheating is completed and the pump is in normal standby mode, test the pump to confirm that the pump rotation direction is normal and the starting sound is normal.

[0039] In the embodiment of the utility model, for the vacuum residue oil pump of the large machine pump 10, the above-mentioned hot oil pump preheating method will cause a high dead point during the preheating period of the large machine pump 10, resulting in incomplete preheating and causing the pump body to be emptied.

[0040] See also Figure 2 In order to solve the above problems, the utility model provides a preheating pipeline of a machine pump 10 in a normal and vacuum distillation device, comprising: a first pipeline 100 and a second pipeline 200, the first pipeline 100 is equipped with a machine pump 10, and an inlet valve 201 is installed on the inlet pipeline 20 of the machine pump 10, and the inlet pipeline 20 is connected to the upstream process pipeline 30, and the first pipeline 100 is connected to the discharge outlet pipeline 50 and the downstream process pipeline 60 on the outlet pipeline 40 of the machine pump 10; the inlet end of the second pipeline 200 is connected to the inlet pipeline 20 between the machine pump 10 and the inlet valve 201 of the first pipeline 100, and the outlet end of the second pipeline 200 is connected to the discharge outlet pipeline 50 of the first pipeline 100.

[0041] Further, there is a height difference between the inlet pipeline 20 and the inlet valve 201, and the inlet end of the second pipeline 200 is located at the high point of the inlet pipeline 20. The position of the inlet valve 201 on the inlet pipeline 20 is higher than the position of the pump 10 on the inlet pipeline 20, and the inlet end of the second pipeline 200 is located on the side of the inlet pipeline 20 close to the inlet valve 201.

[0042] Specifically, in the embodiment of the present utility model, for the preheating pipeline of the pump 10 of the atmospheric and vacuum distillation device, the first pipeline 100 can be understood as shown in the attached Figure 2 The black line diagram portion shown in FIG. 2 is the second pipeline 200. Figure 2 The heavy oil medium in the residual oil of the atmospheric and vacuum distillation unit comes from the upstream process pipeline 30, enters the machine pump 10 through the inlet pipeline 20 on the first pipeline 100, and along the outlet pipeline 40 of the machine pump 10, the residual oil and the waste oil of the heavy oil medium therein enter the downstream process pipeline 60 and the discharge outlet pipeline 50 respectively.

[0043] Furthermore, compared with the Figure 1 The pipeline of the second pipeline 200 shown in FIG. 1 is in the corresponding appendix of the embodiment of the utility model. Figure 2In the process, by changing the inlet end of the second pipeline 200 behind the inlet valve 201 on the inlet pipeline 20 of the pump 10 from a low point to a high point, the position where the heavy oil in the inlet pipeline 20 enters the second pipeline 200 is changed, and the distribution state of the heavy oil medium in the inlet pipeline 20 is adjusted, so that the inlet pipeline 20 from the inlet valve 201 to the pump 10 is fully preheated during the preheating process, and no gas phase is accumulated at the highest point of the pipeline. In this way, the preheating process of the pump 10 is sufficient, no gas phase remains in the inlet pipeline 20, and the pump 10 is effectively avoided from being emptied.

[0044] See also Figure 2 In one embodiment, four outlet pipelines 40 are installed on the machine pump 10, and two outlet pipelines 40 are respectively provided in the four outlet pipelines 40 to connect the downstream process pipeline 60 and the discharge outlet pipeline 50; wherein, one of the two outlet pipelines 40 connected to the downstream process pipeline 60 is also connected to the discharge outlet pipeline 50.

[0045] Furthermore, two outlet pipelines 40 connected to the downstream process pipeline 60 are arranged in parallel, and bypass pipelines 401 are also arranged on the two outlet pipelines 40 arranged in parallel. The two outlet pipelines 40 connected to the discharge port pipeline 50 are connected to the top and bottom of the pump 10 respectively.

[0046] Specifically, after the residual oil and heavy oil medium of the atmospheric and vacuum distillation unit enter the inlet pipeline 20 of the pump 10, a part of them flows directly to the discharge outlet pipeline 50 through the second pipeline 200, and the other part is transported by the pump 10 to transport the residual oil and the heavy oil medium therein to the downstream process pipeline 60 and the discharge outlet pipeline 50. In addition, the outlet pipeline 40 is connected to the part of the downstream process pipeline 60 connected to the discharge outlet pipeline 50, and the stop valves 70 installed on each pipeline part can be used to control the opening and closing of each stop valve 70 and the opening and closing of the corresponding pipeline to cooperate with the preheating operation of the pump 10. Similarly, the outlet pipelines 40 connected to different positions of the pump 10 are respectively connected to control the opening state of the stop valves 70 installed thereon to achieve the preheating operation of the pump body of the pump 10.

[0047] See also Figure 2 In one embodiment, a steam purge line 300 is further included, wherein the outlet end of the steam purge line 300 is connected to the outlet pipeline 40 of the first pipeline 100 and is located on a side of the outlet pipeline 40 connected to the downstream process pipeline 60 .

[0048] Furthermore, a steam purge branch line 310 is connected between the second pipeline 200 and the steam purge pipeline 300, and the steam purge branch line 310 is connected to the side close to the inlet end of the second pipeline 200. The steam purge branch line 310 forms a tee at the part connected to the second pipeline 200, and a stop valve 70 is respectively provided on the three pipelines connected by the tee. The stop valve 70 on the steam purge branch line 310 is also equipped with a blind plate 71 on the side facing the steam purge pipeline 300.

[0049] Specifically, by installing a steam purge branch line 310 connected to the second pipeline 200, the heavy oil medium remaining in the first pipeline 100 and the second pipeline 200 is purged into the heavy oil tank by steam to prevent the heavy oil from condensing in the pipeline and blocking the pipeline. In addition, by installing multiple stop valves 70 at the three-way position formed by the steam purge pipeline 300 and the second pipeline 200, the cooperation between the different stop valves 70 is used to meet the medium transportation operation in the first pipeline 100 and the preheating operation of the pump 10.

[0050] Please refer to the attached Figure 2 As shown in the pipeline diagram, according to the preheating pipeline of the pump 10 in the above-mentioned embodiment of the utility model, the steps for performing the preheating operation are as follows (wherein the [P] before the step represents that this step is an external operation and on-site operation step, and (P) represents that this step is an internal operation, that is, operation is performed through the control system):

[0051] The first step is to prepare the centrifugal pump for starting the pump (in the embodiment of the utility model, the centrifugal pump can be understood as the pump 10, and the "pump" in the following steps can also be understood as the pump 10);

[0052] (P) - Confirm that the coupling and protective cover are installed securely;

[0053] (P) - The mechanical, instrument and electrical confirmation of the pump has been completed;

[0054] (P) - When the pump is cold, the turntable is evenly stressed and rotates flexibly;

[0055] (P) - Confirm that the oil level of the bearing box is within the range of 1 / 2 to 2 / 3;

[0056] [P] - Close the condensate drain valve at the bottom of the pump;

[0057] [P] - Close the preheating valve at the bottom of the pump;

[0058] [P] - Close the exhaust valve at the top of the pump chamber;

[0059] [P] - Close the exhaust valve in the pump inlet valve 201;

[0060] [P] - Close the valve of the heavy oil removal line at the pump outlet (i.e. the stop valve 70 from the outlet pipeline 40 of the pump 10 to the discharge outlet pipeline 50);

[0061] (P) - Confirm that the pump outlet pressure gauge is installed properly;

[0062] [P] - Open the manual valve of the pressure gauge by 2 buttons;

[0063] (P) - Confirm that the pump inlet and outlet process facilities are complete;

[0064] (P) - Confirm that the water supply of the desalted water station is normal;

[0065] [P] - Open the cooling water supply valve and drain valve to supply water to each cooling point;

[0066] [P] - Open the cooling water branch valves;

[0067] (P) - Check through the cooling water return pipe sight glass to confirm that the cooling water return of each branch is unobstructed;

[0068] (P) - Confirm that there is no leakage in the cooling water line and that the auxiliary pipes are complete and normal;

[0069] (P) - Confirm that the oil seal pump is operating normally and the outlet pressure is around 1.18Mpa;

[0070] [P] - The seal flushing system of the predetermined plan is put into use, the seal flushing system pressure is replenished to 0.8Mpa, and the pressure transmitter is put into use normally.

[0071] At this point, it indicates that the centrifugal pump is ready for priming.

[0072] The second step is to prime the centrifugal pump for pressure testing (this operation is performed only when the pump 10 that has been unchecked is started), and the steps are as follows:

[0073] [P] - Open the oil sealing valves of the two pre-set schemes before and after the pump body until the oil sealing flow rate reaches 10L / min;

[0074] [P] - Open the valve from the pump outlet to the heavy oil line to exhaust (i.e. the stop valve 70 from the pump 10 outlet pipeline 40 to the discharge outlet pipeline 50);

[0075] [P] - Open the valve from the pump inlet to the heavy oil line to exhaust (i.e. the stop valve 70 from the pump 10 inlet pipeline 20 to the second pipeline 200);

[0076] [P] - Open the valve from the top of the pump body to the heavy oil line to exhaust (i.e. the stop valve 70 from the outlet pipeline 40 at the top of the pump 10 to the discharge outlet pipeline 50);

[0077] (P) - Confirm that the temperature of each exhaust valve of the pump has increased;

[0078] [P] - Close the exhaust valves of the pump, pressurize the pump 10 to 0.45Mpa with sealing oil, and close the sealing oil valve;

[0079] [P] - Maintain the pump body pressure for 10 minutes, and check to make sure there is no leakage in the pump seal, oil seal line joint, and pump body flange;

[0080] [P] - Open the valves at the bottom of the pump body and from the pump inlet and outlet to the heavy oil line to drain the medium from the pump cavity and the inlet and outlet pipelines.

[0081] It should be noted that during the pump filling operation, the following two points should be noted:

[0082] 1. If the hot oil pump has sealing oil, it must be filled with sealing oil. If the pump does not have sealing oil, use its own medium to fill the pump.

[0083] 2. During the oil sealing pressure test, the test pressure should not exceed the design pressure of the pump inlet.

[0084] The third step is to preheat the centrifugal pump; the steps include:

[0085] a. For preheating after normal switching:

[0086] [P] - The bypass preheating line valve at the pump outlet and the one-way valve bypass preheating line valve are each opened to 1 / 2 (the bypass preheating line valve is the stop valve 70 installed on the bypass pipeline 401);

[0087] [P] - The first valve of the pump body preheating line is opened to 1 / 2 opening, and the second valve is fully opened (i.e. the stop valve 70 on the inlet pipeline 20 and the outlet pipeline 40 of the machine pump 10).

[0088] b. Preheating after oil sealing and pump pressure test:

[0089] (P) - Confirm that the pump inlet and outlet valves 201 are in the closed state;

[0090] [P] - The pump outlet valve bypass preheating line valve and the check valve bypass preheating line valve are opened to 1 / 2 opening;

[0091] [P] - The first valve of the pump body preheating line is opened to 1 / 2, and the second valve is fully opened;

[0092] [P] - Fully open the pump inlet valve 201 to the heavy oil line valve and start preheating the standby pump;

[0093] [P] - Control the amount of sealing oil injected into the preheating pump during preheating. An appropriate excess amount is sufficient to prevent condensation. It is strictly forbidden to inject too much sealing oil to affect the preheating speed.

[0094] [P] - Control the pump preheating speed ≯50℃ / hour, and use an infrared thermometer to measure the pump casing surface temperature for judgment;

[0095] [P] - Turning at 180℃ / half hour;

[0096] [P]-After the temperature of the heavy dirty oil line after the pump inlet valve 201 reaches 200℃, close the valve of the heavy dirty oil line after the inlet valve 201, and slowly open the valve of the inlet valve 201 of the pump 10 until it is fully opened. During this period, strengthen the inspection of the operating condition of the running pump to prevent the running pump from being exhausted;

[0097] [P] - During the preheating period, strengthen the inspection of the preheating machine pump 10 to prevent leakage of the pump and pipeline after temperature changes;

[0098] [P] - Control the preheating flow rate at the pump outlet and the preheating flow rate at the pump bottom. During the preheating period, the temperature difference between the upper and lower surfaces of the pump body should be ≯30°C. During the preheating period, check and measure more frequently and adjust the branch flow rate in time.

[0099] (P) - Check cooling water to ensure that the return water temperature is ≯40℃;

[0100] (P) - Confirm that the preheating temperature is stable and continuous, the preheating temperature of the pump casing surface is ≮300℃, the preheating of the machine pump 10 is completed, and it is in normal standby.

[0101] It should be noted that during the preheating operation, the following two points should be noted:

[0102] 1. When preheating from cold state, preheat the upper and lower parts simultaneously, preheating speed ≯50℃ / hour, final preheating temperature of pump body surface ≮300℃, temperature difference between upper and lower surfaces ≯30℃

[0103] 2. For preheating after normal switching, the pump outlet preheating valve should be opened directly to 1 / 2 opening, the first valve of the pump body preheating line should be half open, and the second valve should be fully open.

[0104] In this way, the preheating operation is changed accordingly through the improved preheating pipeline of the machine pump 10, so as to realize the smooth operation of the pump filling and preheating operation after the machine pump 10 is overhauled.

[0105] In summary, the preheating pipeline of the machine pump in the atmospheric and vacuum distillation device provided by the utility model ensures that there is no gas phase in the pipeline during the pump filling process and that the preheating is sufficient by changing the position of the second pipeline connected to the heavy dirty oil discharge pipeline on the inlet pipeline of the machine pump in the first pipeline. At the same time, a steam purge line is added to the inlet pipeline of the machine pump. After the machine pump is filled and preheated, the heavy dirty oil remaining in the dirty oil pipeline is purged into the heavy dirty oil tank through steam to prevent the heavy dirty oil from condensing in the pipeline and blocking the pipeline.

[0106] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the technology may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed in the present invention shall still be covered by the claims of the present invention.

Claims

1. A preheating pipeline for a pump in a atmospheric and vacuum distillation device, characterized in that: include: a first pipeline (100), wherein the pump (10) is installed on the first pipeline (100), an inlet valve (201) is installed on the inlet pipeline (20) of the pump (10), and the inlet pipeline (20) is connected to an upstream process pipeline (30), and the first pipeline (100) is connected to a discharge outlet pipeline (50) and a downstream process pipeline (60) on the outlet pipeline (40) of the pump (10); A second pipeline (200), wherein the inlet end of the second pipeline (200) is connected to the inlet pipeline (20) between the machine pump (10) and the inlet valve (201) of the first pipeline (100), and the outlet end of the second pipeline (200) is connected to the discharge outlet pipeline (50) of the first pipeline (100).

2. The preheating pipeline according to claim 1, characterized in that There is a height difference between the inlet pipeline (20) and the inlet valve (201), and the inlet end of the second pipeline (200) is located at the highest point of the inlet pipeline (20).

3. The preheating pipeline according to claim 2, characterized in that: The position of the inlet valve (201) on the inlet pipeline (20) is higher than the position of the machine pump (10) on the inlet pipeline (20), and the inlet end of the second pipeline (200) is located on a side of the inlet pipeline (20) close to the inlet valve (201).

4. The preheating pipeline according to claim 1, characterized in that: The pump (10) is provided with four outlet pipelines (40), and two of the four outlet pipelines (40) are respectively provided to connect the downstream process pipeline (60) and the discharge outlet pipeline (50); wherein one of the two outlet pipelines (40) connected to the downstream process pipeline (60) is also connected to the discharge outlet pipeline (50).

5. The preheating pipeline according to claim 4, characterized in that The two outlet pipelines (40) connected to the downstream process pipeline (60) are arranged in parallel, and bypass pipelines (401) are respectively arranged on the two outlet pipelines (40) arranged in parallel.

6. The preheating pipeline according to claim 4, characterized in that The two outlet pipelines (40) connected to the discharge outlet pipeline (50) are respectively connected to the top and the bottom of the pump (10).

7. The preheating pipeline according to claim 1, characterized in that It also includes a steam purge pipeline (300), the outlet end of which is connected to the outlet pipeline (40) of the first pipeline (100) and is located on a side of the outlet pipeline (40) that is connected to the downstream process pipeline (60).

8. The preheating pipeline according to claim 7, characterized in that A steam purge branch line (310) is also connected between the second pipeline (200) and the steam purge pipeline (300), and the steam purge branch line (310) is connected to a side close to the inlet end of the second pipeline (200).

9. The preheating pipeline according to claim 8, characterized in that The steam purge branch line (310) forms a tee at the portion connected to the second pipeline (200), and a stop valve (70) is respectively provided on the three pipelines connected by the tee.

10. The preheating pipeline according to claim 9, characterized in that The stop valve (70) on the steam purge branch line (310) is further provided with a blind plate (71) on the side facing the steam purge pipeline (300).

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