CN-122014655-A - Full-automatic start-stop control method for steam compressor based on DeltaV system

CN122014655ACN 122014655 ACN122014655 ACN 122014655ACN-122014655-A

Abstract

The invention discloses a full-automatic start-stop control method of a vapor compressor based on a DeltaV system, which relates to the technical field of vapor compressor automatic control, and abandons the stiff fixed slope speed-up by introducing a multi-dimensional self-adaptive control strategy, the self-adaptive climbing mechanism based on the pressure change rate and the current rising rate is innovatively established, so that the self-adaptive climbing mechanism can automatically pause the frequency rising when the pressure fluctuates, and can further execute micro frequency-reducing backspacing at critical time, the tripping risk in the starting process is effectively eliminated, and the flexible soft starting is realized. And, the real-time steam theoretical temperature rise is also used as the highest priority limit condition of the mechanical action. By dynamically calculating the theoretical exhaust temperature as a spray target, forcibly locking the lifting frequency and switching the spray valve to the manual minimum opening under the low-load or low-steam theoretical temperature rise, the potential liquid impact hazard caused by PID integral saturation is thoroughly eliminated, the thermodynamic balance under the full working condition is ensured, and the service life of the compressor is greatly prolonged.

Inventors

CHEN QUANHE
YAN HUA
FU ZHIWEN
ZHU YUFENG
TIAN ZHENG
WANG YONGGANG
GUO TAIWEI
LIU CHONGBIAO
HAN XIAOYU

Assignees

内蒙古通威高纯晶硅有限公司

Dates

Publication Date: 20260512
Application Date: 20260306

Claims (10)

1. A full-automatic start-stop control method of a vapor compressor based on a DeltaV system is characterized by comprising the following steps: Step S1, sequentially starting an oil pump, a spray water pump and a main motor based on a received starting instruction, and setting initial working frequency of a compressor; Step S2, the compressor starts to climb automatically according to climbing terminal frequency, the change rate of the operation parameters is monitored in real time in the automatic climbing process, and the operation of continuous frequency increase, suspension frequency increase or micro frequency decrease is executed according to the monitored change rate of the operation parameters, wherein the change rate of the operation parameters comprises at least one of the change rate of the outlet pressure of the compressor or the current increase rate of the main motor; Step S3, synchronously calculating steam theoretical temperature rise in the automatic climbing stage, when the steam theoretical temperature rise is lower than a preset locking threshold value, forcibly stopping automatic climbing of the compressor, and continuously executing the automatic climbing stage after the steam theoretical temperature rise exceeds the locking threshold value; And S4, normally operating the compressor after the frequency of the compressor reaches the climbing end frequency.
2. The full-automatic start-stop control method for a vapor compressor based on a DeltaV system according to claim 1, wherein the specific steps of starting an oil pump, a spray water pump and a main motor in sequence in the step S1 are as follows: Starting an oil pump, detecting that the inlet oil pressure is larger than a starting threshold value in a first starting time period, and starting a main motor fan and a main motor after the inlet oil pressure is continuously larger than the starting threshold value and reaches a second starting time period; And if the inlet oil pressure does not reach the starting threshold value within the first starting time period or the inlet oil pressure is not kept to be larger than the starting threshold value for reaching the second starting time period, executing the pump stopping valve closing operation.
3. The full-automatic start-stop control method of a vapor compressor based on a DeltaV system according to claim 1, further comprising an anti-surge control step based on frequency segmentation in step S2, specifically comprising the following steps: dividing an automatic climbing process of the compressor into a low-frequency region and a high-frequency region by taking an anti-surge threshold value as a boundary; in a low frequency region equal to or below the anti-surge threshold, forcing the anti-surge valve to remain fully open and rapidly pass through the surge zone in an open loop manner; and in a high-frequency region above the surge-preventing threshold, PID (proportion integration differentiation) adjustment of the opening of the surge-preventing valve is performed based on the distance between the working point and the surge line.
4. The full-automatic start-stop control method of a vapor compressor based on a DeltaV system according to claim 1, wherein in step S2, when performing the operation of continuous frequency up-conversion, pause frequency up-conversion or micro-frequency down-conversion according to the monitored change rate of the operation parameter, the method specifically comprises the following steps: Setting a first pressure change rate threshold and a second pressure change rate threshold, wherein the first pressure change rate threshold is smaller than the second pressure change rate threshold; performing a maintenance boost operation when the monitored compressor outlet pressure rate of change is less than or equal to the first pressure rate of change threshold; When the monitored outlet pressure change rate of the compressor is between the first pressure change rate threshold value and the second pressure change rate threshold value, executing a pause frequency-raising operation, keeping the current frequency operation, and waiting for the pressure change rate to fall back; And when the monitored change rate of the outlet pressure of the compressor is greater than or equal to the second pressure change rate threshold value, executing micro frequency-reducing operation, reducing the preset step length of the running frequency, and trying to continuously increase the frequency after keeping the preset stable interval time.
5. The full-automatic start-stop control method for a DeltaV system-based vapor compressor of claim 4, wherein, The specific implementation parameters of the trace frequency reduction are as follows: And performing frequency-reducing operation with a set step length, wherein the interval time between two adjacent frequency-reducing operations is set as the set time.
6. The full-automatic start-stop control method of a vapor compressor based on a DeltaV system according to claim 1, further comprising an exhaust spray control process in step S3, specifically comprising the following steps: Calculating the theoretical temperature of the exhaust gas of the compressor under the current working condition according to the fixed characteristic parameters of the impeller and the shell of the compressor, the compression ratio of the outlet pressure of the compressor and the inlet pressure of the compressor in real time and the inlet temperature of the compressor; and taking the theoretical exhaust temperature of the compressor as a set value of exhaust spraying, and automatically adjusting the opening of a spray valve by adopting PID control according to the set value.
7. The full-automatic start-stop control method of a vapor compressor based on a DeltaV system according to claim 1, wherein the specific trigger conditions for forcibly stopping the automatic climbing of the compressor in step S3 are: Calculating the difference between the theoretical exhaust temperature of the compressor and the steam temperature at the inlet of the compressor in real time to serve as the theoretical steam temperature rise; when the steam theoretical temperature rise is smaller than the locking threshold value, judging that the steam theoretical temperature rise is too low, and forcibly stopping automatic climbing of the compressor; and when the difference value is recovered to be higher than the locking threshold value, recovering the automatic climbing of the compressor.
8. The DeltaV system-based vapor compressor full-automatic start-stop control method of claim 7, wherein said exhaust spray control process further comprises a low load forced manual mode, as follows: presetting a lowest opening value of a spray valve; monitoring the running frequency of the compressor and the theoretical temperature rise of steam in real time; When the operation frequency of the compressor is detected to be lower than the initial operation frequency or the theoretical temperature rise of steam is detected to be lower than the forced manual threshold value, switching PID control to manual control, and setting the opening of the spray valve to be the lowest opening value; The manual control of the exhaust spray control is switched back to PID control only when the theoretical steam temperature rises above the mandatory manual threshold.
9. The full-automatic start-stop control method of a DeltaV system based on a vapor compressor of claim 1, further comprising a step of staged shut-down, specifically as follows: Monitoring the radial vibration value and the high-speed shaft displacement value of the compressor in real time; triggering a normal shutdown program when the change rate of the outlet pressure of the compressor exceeds a third pressure change rate threshold, or the radial vibration value is in a dangerous vibration interval, or the high-speed shaft displacement exceeds a displacement threshold; When the radial vibration value is detected to exceed the dangerous vibration interval, an emergency shutdown procedure is triggered.
10. The full-automatic start-stop control method for a DeltaV system-based vapor compressor of claim 9, further comprising a step of stopping spray control during the step of stopping in stages, wherein the step of stopping spray control is as follows: when a shutdown program is executed, collecting the inlet steam pressure of the compressor in real time, and looking up a table or calculating the saturation temperature corresponding to the pressure; and adjusting the opening of the spray valve until the inlet temperature of the compressor is equal to the saturation temperature, and maintaining the opening during the stopping process.

Description

Full-automatic start-stop control method for steam compressor based on DeltaV system Technical Field The invention belongs to the technical field of automatic control of a steam compressor, and particularly relates to a full-automatic start-stop control method of a steam compressor based on a DeltaV system. Background The control of the vapor compressor is usually realized by an advanced distributed control system, the running states of all components need to be precisely coordinated in the starting stage, the working condition switching from the static standby machine to the high-speed running is completed, and meanwhile, key thermodynamic parameters such as vibration, displacement, temperature, pressure and the like need to be monitored in real time so as to maintain the thermodynamic balance and mechanical safety of the system. Existing vapor compressor control logic has certain limitations. On the one hand, in the stage of starting up a climbing, the traditional control strategy generally adopts a fixed linear rising rate to adjust the frequency converter, and nonlinear fluctuation in the process of establishing the outlet pressure cannot be fully considered, so that when the pressure rises too fast or the load suddenly changes, the frequency converter is triggered to trip due to too large current impact or pressure overshoot, and the starting-up success rate is influenced. On the other hand, the traditional spray temperature reduction control mostly adopts a fixed temperature set value to carry out PID regulation, so that the influence of severe change of exhaust pressure on saturation temperature in an unsteady state process is ignored, and when the outlet working condition fluctuates, the phenomenon of hydraulic liquid shrinkage caused by excessive water spray quantity or the exhaust overtemperature caused by insufficient water spray quantity is extremely easy to occur, thereby causing irreversible mechanical damage to the compressor impeller and the sealing component. Disclosure of Invention Aiming at the defects in the prior art, the invention provides a full-automatic start-stop control method for a vapor compressor based on a DeltaV system, so as to solve the technical problems. A full-automatic start-stop control method of a vapor compressor based on a DeltaV system comprises the following steps: Step S1, sequentially starting an oil pump, a spray water pump and a main motor based on a received starting instruction, and setting initial working frequency of a compressor; Step S2, the compressor starts to climb automatically according to climbing terminal frequency, the change rate of the operation parameters is monitored in real time in the automatic climbing process, and the operation of continuous frequency increase, suspension frequency increase or micro frequency decrease is executed according to the monitored change rate of the operation parameters, wherein the change rate of the operation parameters comprises at least one of the change rate of the outlet pressure of the compressor or the current increase rate of the main motor; Step S3, synchronously calculating steam theoretical temperature rise in the automatic climbing stage, when the steam theoretical temperature rise is lower than a preset locking threshold value, forcibly stopping automatic climbing of the compressor, and continuously executing the automatic climbing stage after the steam theoretical temperature rise exceeds the locking threshold value; And S4, normally operating the compressor after the frequency of the compressor reaches the climbing end frequency. Preferably, the specific steps of starting the oil pump, the spray water pump and the main motor in sequence in the step S1 are as follows: Starting an oil pump, detecting that the inlet oil pressure is larger than a starting threshold value in a first starting time period, and starting a main motor fan and a main motor after the inlet oil pressure is continuously larger than the starting threshold value and reaches a second starting time period; And if the inlet oil pressure does not reach the starting threshold value within the first starting time period or the inlet oil pressure is not kept to be larger than the starting threshold value for reaching the second starting time period, executing the pump stopping valve closing operation. Preferably, in step S2, an anti-surge control step based on frequency segmentation is further included, specifically as follows: dividing an automatic climbing process of the compressor into a low-frequency region and a high-frequency region by taking an anti-surge threshold value as a boundary; in a low frequency region equal to or below the anti-surge threshold, forcing the anti-surge valve to remain fully open and rapidly pass through the surge zone in an open loop manner; and in a high-frequency region above the surge-preventing threshold, PID (proportion integration differentiation) adjustment of the opening of the surge-preventing va