Method for safe operation of nitric acid high-voltage motor dragging unit

Abstract

A method for safe operation of a nitric acid high-voltage motor dragging unit comprises the steps that a high-voltage motor is connected with a nitric oxide compressor through a coupler, the diameter of a shaft head of the high-voltage motor is 90 mm, the length of the shaft head of the high-voltage motor is 350 mm, the shaft head of the high-voltage motor is in a conical shape, and the shaft head of the high-voltage motor is connected with the nitric oxide compressor through a coupler. The nitric oxide compressor is connected with the axial flow compressor through the gearbox, and the axial flow compressor is connected with the tail gas turbo expander. The high-voltage motor has the advantages that the length of the shaft head of the high-voltage motor is shortened, and the shape of the shaft head is changed, so that the operation stability of the high-voltage motor is improved, and the production safety and the production operation stability are ensured.

Description

Technical Field

[0001] The invention belongs to the field of nitric acid production, in particular to a method for safe operation of a nitric acid high-voltage motor-driven unit. Background Art

[0002] At present, the four-in-one unit used in nitric acid production is a more common production equipment. The four-in-one unit includes a steam turbine, a nitrogen oxide compressor, an axial flow compressor and a tail gas turbine expander. At present, the four-in-one unit drives the nitrogen oxide compressor, the axial flow compressor and the tail gas turbine expander through the steam turbine. However, the operating conditions of the steam turbine are relatively harsh and the maintenance operation is relatively complicated, resulting in high production costs. In order to reduce the operating difficulty and production costs, there is currently a method of using a high-voltage motor to replace the steam turbine as a driving device for operation. The operating conditions of the high-voltage motor are simple and the maintenance operation is simple, which can effectively reduce the production cost. However, when the current high-voltage motor is connected to the nitrogen oxide compressor, the axial flow compressor and the tail gas turbine expander during operation, after running to 8000rpm / min, the vibration value continues to increase, and the vibration curve becomes a sine wave, which continues to increase, and finally reaches the unit interlocking value and jumps, resulting in inability to produce continuously, affecting production efficiency. Summary of the invention

[0003] The invention provides a method for safe operation of a nitric acid high-voltage motor-driven unit, which is used to solve the defects in the prior art.

[0004] The present invention is achieved through the following technical solutions:

[0005] A method for safely operating a nitric acid high-pressure motor-driven unit comprises the following steps: the high-pressure motor is connected to a nitrogen oxide compressor via a coupling, the shaft head diameter of the high-pressure motor is 90 mm, the shaft head length of the high-pressure motor is 350 mm, the shaft head of the high-pressure motor is conical, the nitrogen oxide compressor is connected to an axial flow compressor via a gear box, and the axial flow compressor is connected to a tail gas turbine expander.

[0006] In the above-mentioned method for safe operation of a nitric acid high-voltage motor-driven unit, the weight of the coupling is 28-40kg.

[0007] The method for safe operation of a nitric acid high-voltage motor-driven unit is described above, wherein the high-voltage motor is an asynchronous motor.

[0008] In the method for safe operation of a nitric acid high-voltage motor-driven unit as described above, the rated power of the high-voltage motor is 6500KVA; the rated voltage of the high-voltage motor is input 10KV / output 6.6kV.

[0009] According to the method for safe operation of a nitric acid high-voltage motor-driven unit, the speed fluctuation range of the high-voltage motor during production operation is 75%-105%; the speed control range of the high-voltage motor is 70-100% square torque, 100-105% constant power.

[0010] As described above, a method for safe operation of a nitric acid high-voltage motor-driven unit is provided, wherein the speed of the high-voltage motor is 9250rpm / min according to its design operating condition, i.e., 100% load, and the maximum operating condition, i.e., 105% load; when the load drops to a minimum of 70%, the speed of the high-voltage motor is 8787rpm / min, and the speed adjustment is achieved through a frequency converter.

[0011] In the method for safe operation of a nitric acid high-voltage motor-driven unit as described above, two supporting points are added to the lower portion of the base of the high-voltage motor to improve the stability of the base.

[0012] In the above-mentioned method for safe operation of a nitric acid high-voltage motor-driven unit, the insulating portion of the coupling is removed and replaced with a rigid adapter plate.

[0013] The advantages of the present invention are as follows: the present invention improves the running stability of the high-voltage motor by shortening the shaft head length of the high-voltage motor and changing the shape of the shaft head, thereby ensuring production safety and stability of production operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0015] Figure 1 This is the vibration spectrum before the transformation;

[0016] Figure 2 This is one of the improved research schematic diagrams of the present invention:

[0017] Figure 3 This is the second schematic diagram of the improved research of the present invention:

[0018] Figure 4 This is the third schematic diagram of the improved research of the present invention:

[0019] Figure 5 It is the fourth schematic diagram of the improvement research of the present invention. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] A method for safely operating a nitric acid high-pressure motor-driven unit comprises the following steps: the high-pressure motor is connected to a nitrogen oxide compressor via a coupling, the shaft head diameter of the high-pressure motor is 90 mm, the shaft head length of the high-pressure motor is 350 mm, the shaft head of the high-pressure motor is conical, the nitrogen oxide compressor is connected to an axial flow compressor via a gear box, and the axial flow compressor is connected to a tail gas turbine expander.

[0022] Specifically, the weight of the coupling described in this embodiment is 28-40kg.

[0023] The method for safe operation of a nitric acid high-voltage motor-driven unit is described above, wherein the high-voltage motor is an asynchronous motor.

[0024] Specifically, the rated power of the high-voltage motor described in this embodiment is 6500KVA; the rated voltage of the high-voltage motor is input 10Kv / output 6.6kV.

[0025] More specifically, the speed fluctuation range of the high-voltage motor during production and operation described in this embodiment is 75%-105%; the speed control range of the high-voltage motor is 70-100% square torque, 100-105% constant power.

[0026] Furthermore, the high-voltage motor described in this embodiment has a speed of 9250 rpm / min according to its design operating condition, i.e. 100% load, and the maximum operating condition, i.e. 105% load; when the load drops to a minimum of 70%, the speed of the high-voltage motor is 8787 rpm / min, and the speed is adjusted by the frequency converter.

[0027] Furthermore, two supporting points are added to the lower part of the base of the high-voltage motor described in this embodiment to improve the stability of the base.

[0028] Furthermore, the insulating portion of the coupling described in this embodiment is removed and replaced with a rigid adapter plate.

[0029] Verification test

[0030] After the high-voltage motor was installed, all relevant indicators were normal in the single-unit test run on November 14, 2023. On November 15, 2023, it was connected to the nitrogen oxide compressor, axial flow compressor and tail gas turbine expander for no-load operation. It was found that the motor operated normally below 8000rpm / min, and the vibration value at the motor coupling end was large in the range of 8000rpm / min to 9250rpm / min; and the vibration value fluctuated, rising to the interlock value in a short time, causing the interlock to trip. The vibration spectrum is as follows Figure 1 shown.

[0031] The research operations conducted to analyze and study the above problems and solve the above problems include:

[0032] 1. Adjust the inverter parameters to try to change the vibration situation;

[0033] 2. Adjust the alignment curve between the high-voltage motor and the nitrogen oxide compressor to reduce the height of the high-voltage motor;

[0034] 3. Disconnect the coupling between the nitrogen oxide compressor and the gearbox, and run the motor only with the nitrogen oxide compressor;

[0035] 4. High voltage motor installation positioning pin;

[0036] 5. Add two support points at the bottom of the high-voltage motor base to improve the stability of the base;

[0037] 6. Check the bearing clearance and interference on the coupling side of the high-voltage motor and increase the bearing interference;

[0038] 7. Remove the insulating part of the coupling and replace it with a rigid adapter plate;

[0039] 8. Adjust the counterweight at the motor coupling end to adjust the high-speed balance of the coupling;

[0040] 9. Strengthen the positioning of the nitrogen oxide compressor to prevent deviation;

[0041] After actual operation, except for adding two support points at the bottom of the high-voltage motor base, improving the stability of the base and removing the insulating part of the coupling and replacing it with a rigid adapter plate, which had a certain effect, other methods had no effect. Even if there was an effect, it failed to meet the expected standards and the interlock jump would still occur due to fluctuations in vibration values.

[0042] Since no solution was found in external machinery and system design, the improvement object was transferred to the high-voltage motor. After a lot of research, it was found that the shaft head length and coupling weight of the high-voltage motor would have a certain impact on the vibration value fluctuation of the high-voltage motor at a speed above 8000rpm / min. The influencing factors were found and further improvement research was carried out. The operation is as follows Figure 2-5 shown.

[0043] After research, the weight of the coupling was reduced by 11kg, the shaft head of the high-voltage motor was changed from the original cylindrical double-key to a conical type, and the shaft head length was shortened to 350mm. After the above transformation, the high-voltage motor ran smoothly, and all vibration measurement points were below 15um, thus avoiding the occurrence of interlocking jumps due to fluctuations in vibration values, ensuring safe and stable production operation.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for safe operation of a nitric acid high-voltage motor driven unit, characterized in that: Its operation is: the high-voltage motor is connected to the nitrogen oxide compressor through a coupling, the shaft head diameter of the high-voltage motor is 90 mm, the shaft head length of the high-voltage motor is 350 mm, the shaft head of the high-voltage motor is conical, the nitrogen oxide compressor is connected to the axial flow compressor through a gear box, and the axial flow compressor is connected to the exhaust gas turbine expander.

2. The method for safe operation of a nitric acid high-voltage motor-driven unit according to claim 1, characterized in that: The weight of the coupling is 28-40kg.

3. The method for safe operation of a nitric acid high-voltage motor-driven unit according to claim 1, characterized in that: The high voltage motor is an asynchronous motor.

4. The method for safe operation of a nitric acid high-voltage motor-driven unit according to claim 1, characterized in that: The rated power of the high-voltage motor is 6500KVA; the rated voltage of the high-voltage motor is input 10Kv / output 6.6kV.

5. The method for safe operation of a nitric acid high-voltage motor-driven unit according to claim 1, characterized in that: The speed fluctuation range of the high-voltage motor during production and operation is 75%-105%; the speed control range of the high-voltage motor is 70-100% square torque, 100-105% constant power.

6. The method for safe operation of a nitric acid high-voltage motor-driven unit according to claim 5, characterized in that: According to the design working condition, i.e. 100% load, and the maximum working condition, i.e. 105% load, the speed of the high-voltage motor is 9250rpm / min; when the load drops to 70%, the speed of the high-voltage motor is 8787rpm / min, and the speed is adjusted by the frequency converter.

7. The method for safe operation of a nitric acid high-voltage motor-driven unit according to claim 1, characterized in that: Two supporting points are added to the lower part of the base of the high-voltage motor to improve the stability of the base.

8. The method for safe operation of a nitric acid high-voltage motor-driven unit according to claim 1, characterized in that: The insulating part of the coupling is removed and replaced with a rigid adapter plate.

Images