CN-122015428-A - Air separation oxygen periodic liquefaction and reformulation system under peak-valley electricity condition

CN122015428ACN 122015428 ACN122015428 ACN 122015428ACN-122015428-A

Abstract

The invention discloses an air separation oxygen cycle liquefying and re-allocating system under peak-valley electricity conditions, which relates to the technical field of gas separation and comprises a nitrogen compression subsystem, a liquid oxygen vaporizing subsystem and an oxygen liquefying subsystem, wherein the nitrogen compression subsystem is used for providing pressurized nitrogen in a valley electricity period, the liquid oxygen vaporizing subsystem is used for vaporizing stored liquid oxygen by utilizing the cold energy of the pressurized nitrogen and then outputting the vaporized liquid oxygen in the valley electricity period, the oxygen liquefying subsystem is used for liquefying and storing oxygen by utilizing the cold energy of liquid nitrogen in the peak electricity period, and the control module subsystem is used for controlling the nitrogen compression subsystem, the liquid oxygen vaporizing subsystem and the oxygen liquefying subsystem and is used for operating data and forecasting requirements according to history. In the peak electricity period, the invention recovers the oxygen which is limited to be exhausted due to the air separation load, in the valley electricity period, the liquid oxygen recovered by vaporization supplements the air supply, improves the cooperative capacity of the air separation device and the downstream air utilization device, reduces the air separation performance waste when the downstream air utilization is greatly changed, and realizes the efficient utilization of energy and the stable operation of the system.

Inventors

LI GUIQUAN
SHEN WEI
HAO SHAOHUA
ZHANG YUZHE
JING CHAO
HUANG XUANXU
HUANG YIHUI

Assignees

盈德气体工程(浙江)有限公司

Dates

Publication Date: 20260512
Application Date: 20260209

Claims (10)

1. A system for liquefying and reformulating an oxygen cycle of a space division under peak-to-valley electrical conditions, comprising: A nitrogen compression subsystem for providing pressurized nitrogen during the valley period; the liquid oxygen vaporization subsystem is used for vaporizing the stored liquid oxygen by utilizing the cold energy of the pressurized nitrogen and outputting the vaporized liquid oxygen in a valley electricity period; the oxygen liquefaction subsystem is used for liquefying and storing oxygen by utilizing the cold energy of liquid nitrogen in the peak electricity period; The control module subsystem is used for controlling the nitrogen compression subsystem, the liquid oxygen vaporization subsystem and the oxygen liquefaction subsystem, and is used for optimally scheduling the start-stop time sequence and the operation load of the liquid oxygen vaporization subsystem and the oxygen liquefaction subsystem according to historical operation data and predicted requirements.
2. The system for liquefying and reformulating an air-separated oxygen cycle under peak-to-valley electrical conditions of claim 1 wherein said nitrogen compression subsystem comprises a nitrogen compressor; the liquid oxygen vaporization subsystem comprises a vaporization heat exchanger, a liquid oxygen pump, a liquid nitrogen throttle valve and a liquid nitrogen vacuum tank which are sequentially connected through pipelines; the oxygen liquefying subsystem comprises a liquefying heat exchanger, a liquid nitrogen pump, a nitrogen expander, a liquid oxygen throttle valve and a liquid oxygen vacuum tank which are sequentially connected through pipelines; the liquid nitrogen vacuum tank provides a cold source medium for the oxygen liquefaction subsystem and stores a cold energy carrier for the liquid oxygen vaporization subsystem.
3. The system for liquefying and reformulating an air-separation oxygen cycle under peak-to-valley electrical conditions of claim 2 wherein said control module subsystem comprises: The data acquisition module is used for acquiring and storing historical electricity price data, unit time load data of a downstream gas utilization device, environment temperature and humidity data and real-time liquid level, temperature and pressure data of the liquid oxygen vacuum tank and the liquid nitrogen vacuum tank in real time; The analysis and prediction module is used for training and learning the historical data based on a cyclic neural network model, predicting a dynamic gas load curve in a future designated scheduling period and automatically dividing a cost optimization interval of energy input by coupling electricity price policy information; And the scheduling execution module is used for generating and issuing an optimized scheduling instruction sequence for controlling the liquid nitrogen pump rotating speed, the liquid oxygen pump rotating speed, the opening of the inlet guide vane of the nitrogen expansion machine and the opening of the corresponding throttle valve according to the predicted gas load curve and the cost optimization interval and by combining real-time data of the storage tank.
4. The system for liquefying and re-allocating air separation oxygen cycles under peak-valley electricity conditions according to claim 3, wherein the optimized scheduling instruction refers to a target liquefying load which is feedback-regulated based on a real-time oxygen emptying rate, a starting liquid level threshold and a stopping liquid level threshold of a liquid oxygen vaporizing subsystem and a target vaporizing load which is feedback-regulated based on pipe network pressure fluctuation when the oxygen liquefying subsystem is started and operated; The starting time is comprehensively judged according to the predicted gas load descending inflection point and the electricity price peak starting point, and the process preparation time required by system starting is reserved; The target liquefaction load is set to ensure that the predicted oxygen surplus is effectively stored before the electricity price peak is finished, and the safety filling upper limit of the liquid oxygen vacuum tank is not exceeded.
5. The system of claim 4, wherein the analysis prediction module is configured to re-solve, in each scheduling step, for a current system state as an initial condition and for a total cost minimum in a future prediction period as an objective function, the total cost comprising: The total power consumption cost of the system calculated according to the time-of-use power price, the resource loss cost caused by oxygen emptying, the equipment fatigue life conversion cost increased due to severe fluctuation of equipment load, and the production loss penalty cost generated by failing to meet the downstream demand; And when the capacity and working pressure of the liquid oxygen and liquid nitrogen vacuum tank are limited, the flow and lift working range determined by the characteristic curves of the liquid oxygen pump and the liquid nitrogen pump, the isentropic efficiency limit of the nitrogen expander, and the minimum pressure and oxygen supply stability index of the pipe network are set for guaranteeing the continuous downstream production.
6. The system for periodically liquefying and reformulating air-separated oxygen under peak-valley electricity conditions according to claim 2, wherein the outlet of the nitrogen compressor is connected with the tube side high-pressure side inlet of the vaporizing heat exchanger; the tube side high-pressure side outlet of the vaporization heat exchanger is connected with the inlet of the liquid nitrogen throttle valve; The liquid nitrogen throttle valve is provided with a first outlet and a second outlet, the first outlet is connected to the shell side low-pressure side of the vaporization heat exchanger to form a reflux nitrogen loop to recover cold energy, and the second outlet is connected to the inlet of the liquid nitrogen vacuum tank and is used for storing liquefied liquid nitrogen.
7. The system for liquefying and re-allocating an air separation oxygen cycle under peak-valley electricity condition according to claim 6, wherein an outlet of the liquid nitrogen vacuum tank is connected with a shell side inlet of the liquefying heat exchanger through the liquid nitrogen pump, the liquid nitrogen pump is driven by a variable frequency motor, and the rotating speed of the liquid nitrogen pump is directly controlled by the optimizing and scheduling command; The shell side outlet of the liquefaction heat exchanger is connected with the inlet of the nitrogen expander; The outlet of the nitrogen expansion machine is connected with the low-pressure side of the tube side of the liquefaction heat exchanger to form refrigeration cycle; the tube side high-pressure side inlet of the liquefaction heat exchanger is connected to a medium-pressure oxygen output pipeline of the air separation device and is provided with an oxygen flow regulating valve; The tube side high-pressure side outlet of the liquefaction heat exchanger is connected with the inlet of the liquid oxygen throttle valve; The outlet of the liquid oxygen throttle valve is connected with the inlet of the liquid oxygen vacuum tank, and the liquid oxygen vacuum tank is provided with a high-precision liquid level meter, a pressure sensor and a safety relief device.
8. The system for periodically liquefying and re-preparing air-separated oxygen under peak-valley electricity condition according to claim 7, wherein an outlet of the liquid oxygen vacuum tank is connected with a shell side high-pressure side inlet of the vaporizing heat exchanger through the liquid oxygen pump, and the liquid oxygen pump is driven by a variable frequency motor; the shell side high-pressure side outlet of the vaporization heat exchanger is connected to an oxygen supply pipe network, and an oxygen heater, a pressure regulating valve and a flowmeter are sequentially arranged on the connecting pipe, and are used for completely vaporizing and reheating supercooled liquid oxygen and regulating the supercooled liquid oxygen to the pressure and the temperature required by the pipe network for output.
9. An electronic device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, wherein the processor performs the steps of implementing the air separation oxygen cycle liquefaction and re-deployment system under peak to valley electrical conditions of any one of claims 1 to 8 when the program is executed.
10. A computer readable storage medium having stored thereon a computer program, which when executed by a processor performs the steps of the air separation oxygen cycle liquefaction and reformulation system of any one of claims 1 to 8.

Description

Air separation oxygen periodic liquefaction and reformulation system under peak-valley electricity condition Technical Field The invention relates to the field of gas separation, in particular to a system for liquefying and re-allocating an air separation oxygen cycle under peak-valley electricity conditions. Background In the context of energy management where peak-to-valley price policies are widely implemented, the operational economy and stability of air separation plants face significant challenges. Because of the technical characteristics of the traditional air separation device, the starting and stopping process is complex and time-consuming, and the large-scale load adjustment is difficult to realize in a short time, so that the operation flexibility is seriously insufficient. Specifically, in the peak electricity period with higher electricity price, the load of the downstream gas utilization device is often reduced or even stopped, and if the air separation device runs continuously, the produced oxygen can not be effectively consumed and can only be forced to be exhausted, so that not only is the direct waste of precious gas resources caused, but also the overall energy utilization efficiency of the device is greatly reduced. In contrast, during the valley period when electricity prices are low, the downstream gas demand usually reaches a peak, but even if the air separation plant continuously runs at the maximum design load, the gas production capacity of the air separation plant still has difficulty in meeting the sudden increase demand, so that the stability and the continuity of downstream production are restricted. Disclosure of Invention Aiming at the technical problems, the technical scheme adopted by the invention is a space-division oxygen periodic liquefaction and reformulation system under peak-valley electricity conditions, comprising: A nitrogen compression subsystem for providing pressurized nitrogen during the valley period; the liquid oxygen vaporization subsystem is used for vaporizing the stored liquid oxygen by utilizing the cold energy of the pressurized nitrogen and outputting the vaporized liquid oxygen in a valley electricity period; the oxygen liquefaction subsystem is used for liquefying and storing oxygen by utilizing the cold energy of liquid nitrogen in the peak electricity period; The control module subsystem is used for controlling the nitrogen compression subsystem, the liquid oxygen vaporization subsystem and the oxygen liquefaction subsystem, and is used for optimally scheduling the start-stop time sequence and the operation load of the liquid oxygen vaporization subsystem and the oxygen liquefaction subsystem according to historical operation data and predicted requirements. Preferably, the nitrogen compression subsystem comprises a nitrogen compressor; the liquid oxygen vaporization subsystem comprises a vaporization heat exchanger, a liquid oxygen pump, a liquid nitrogen throttle valve and a liquid nitrogen vacuum tank which are sequentially connected through pipelines; the oxygen liquefying subsystem comprises a liquefying heat exchanger, a liquid nitrogen pump, a nitrogen expander, a liquid oxygen throttle valve and a liquid oxygen vacuum tank which are sequentially connected through pipelines; the liquid nitrogen vacuum tank provides a cold source medium for the oxygen liquefaction subsystem and stores a cold energy carrier for the liquid oxygen vaporization subsystem. Preferably, the control module subsystem includes: The data acquisition module is used for acquiring and storing historical electricity price data, unit time load data of a downstream gas utilization device, environment temperature and humidity data and real-time liquid level, temperature and pressure data of the liquid oxygen vacuum tank and the liquid nitrogen vacuum tank in real time; The analysis and prediction module is used for training and learning the historical data based on a cyclic neural network model, predicting a dynamic gas load curve in a future designated scheduling period and automatically dividing a cost optimization interval of energy input by coupling electricity price policy information; And the scheduling execution module is used for generating and issuing an optimized scheduling instruction sequence for controlling the liquid nitrogen pump rotating speed, the liquid oxygen pump rotating speed, the opening of the inlet guide vane of the nitrogen expansion machine and the opening of the corresponding throttle valve according to the predicted gas load curve and the cost optimization interval and by combining real-time data of the storage tank. Preferably, the optimized dispatching instruction refers to a starting time and an operating time of the oxygen liquefaction subsystem, a target liquefaction load adjusted based on real-time oxygen emptying rate feedback, a starting liquid level threshold value and a stopping liquid level threshold value of the liquid oxygen vaporizat