Automatic constant load control method for air separation plant

Abstract

The present application relates to air separation device system control technical field, specifically disclose a kind of automatic constant load control method of air separation device, material balance module system air transparent guide vane tracks raw material air flow of purification system, editing module system controls air transparent guide vane constant purification system processing air volume;Editing module system controls oxygen production regulating valve to track actual oxygen flow;3) editing module system controls nitrogen production regulating valve to track the oxygen, nitrogen multiple of actual oxygen flow;Editing module system controls dirty nitrogen production regulating valve to track actual dirty nitrogen flow;Expansion air volume tracks oxygen production or processing air volume editing module control expander nozzle opening and bypass valve, adjust expansion air into upper column processing air volume and bypass air volume;Process argon flow regulating valve tracks process argon flow editing module system control;The present application does not independently unit configuration automatic load variation system with additional investment, realizes processing air volume and output balance prediction, material balance.

Description

Technical Field

[0001] This invention relates to the field of air separation unit system control technology, and specifically to an automatic constant load control method for an air separation unit. Background Technology

[0002] At present, the control of oxygen production in air separation units is mostly done through daily adjustments by operators. Large diurnal temperature variations cause fluctuations in the amount of raw air processed, which in turn affects oxygen production and requires operational adjustments. Furthermore, the variable load operation of air separation units involves significant changes in operating conditions, necessitating skilled technicians to stably control the unit's operating conditions.

[0003] In recent years, "automatic load change systems for air separation units" developed both domestically and internationally have begun to be applied to air separation units. These systems require a separate computer to integrate with the air separation unit's DCS system for intelligent control. Because automatic load change systems require automation of the air separation unit and have relatively high equipment configuration requirements, the investment in a separate automatic load change system is substantial. Currently, the processing air volume and output of air separation units are calculated manually to maintain material balance. The load of the air separation unit is manually adjusted on the DCS based on the user's oxygen consumption to keep oxygen production within a reasonable range. Problems and shortcomings include: 1. High workload of manual operation. 2. High workload of manual load change. 3. Poor stability of manual load change. Therefore, it is necessary to design a system that utilizes the air separation unit's DCS module program to achieve automatic constant load control. This system can be used for air separation units with lower entry barriers, allowing for simple hardware upgrades without requiring a separate investment in an automatic load change system. Summary of the Invention

[0004] In view of the problems existing in the prior art, the purpose of this invention is to provide an automatic constant load control method for an air separation unit.

[0005] The technical solution adopted by this invention to solve its technical problem is: an automatic constant load control method for an air separation unit, comprising the following steps:

[0006] 1) The material balance module system tracks the raw material air flow of the purification system through the guide vane, and the editing module system controls the constant processing air volume of the purification system through the guide vane.

[0007] 2) The editing module system controls the oxygen production regulating valve to track the actual oxygen flow rate, and uses oxygen purity adjustment to limit the oxygen production adjustment too quickly and to correct deviations;

[0008] 3) The editing module system controls the nitrogen production regulating valve to track the actual oxygen flow rate and the oxygen-nitrogen ratio, adjusting and limiting excessively rapid nitrogen production adjustments and correcting deviations;

[0009] 4) The editing module system controls the waste nitrogen production regulating valve to track the actual waste nitrogen flow rate and adjust the waste nitrogen production;

[0010] 5) The expanded air volume tracking module controls the expansion compressor nozzle opening and bypass valve to adjust the amount of expanded air entering the upper tower for processing and the bypass air volume.

[0011] 6) The process argon flow regulating valve tracks the process argon flow editing module system control;

[0012] 7) The nitrogen production regulating valve, the main heat exchanger inlet air distribution valve, the expander bottom extraction valve, the purification system waste nitrogen regeneration valve, and the waste nitrogen to water cooling tower regulating valve are all automatically controlled and regulated under different loads in the editing module system.

[0013] Specifically, in step 5), the amount of expanded air is tracked to track the oxygen production. When the oxygen production is input, the editing module system converts it into the amount of air to be processed and pushes it to the constant flow control of the air-permeable guide vane of the material balance module system.

[0014] Specifically, in the editing module system control state in step 6), when a sudden shutdown occurs, the above-mentioned nitrogen production regulating valve, main heat exchanger inlet air distribution valve, expander bottom extraction valve, purification system waste nitrogen regeneration valve, and waste nitrogen to water cooling tower regulating valve are all switched to manual operation to prevent accidents from occurring in the air separation unit.

[0015] Specifically, in step 1), the editing module system calculates the raw material flow rate:

[0016] Raw material air flow rate = Oxygen production ÷ 20.93% ÷ Oxygen extraction rate of fractionation system + Bypass air volume;

[0017] Process argon flow rate = Oxygen production × Argon fraction flow rate multiple

[0018] Among them, the argon fraction flow rate multiple is 1.02-1.05.

[0019] Specifically, the calculation of the actual oxygen flow rate in step 2) is as follows:

[0020] Actual oxygen flow rate = (processing air volume - bypass air volume) × 20.93% × oxygen extraction rate.

[0021] Specifically, the calculation of the actual nitrogen flow rate in step 4) is as follows:

[0022] Actual nitrogen flow rate = (processing air volume - bypass air volume) × 78.03% × nitrogen purity - waste nitrogen flow rate.

[0023] Specifically, the calculation of the process argon flow rate in step 6) is as follows:

[0024] Process argon flow rate = (processing air volume - bypass air volume) × 0.932% × argon extraction rate;

[0025] According to the material balance, the flow rate of waste nitrogen gas = processing air volume - oxygen production - nitrogen production - argon production.

[0026] Specifically, the editing module system is a DCS module system.

[0027] The present invention has the following beneficial effects:

[0028] The automatic constant load control method for air separation unit designed in this invention allows for simple hardware upgrades without requiring additional investment in an independent unit configuration for an automatic load-changing system. The DCS module system automatically changes the load, saving operating costs and achieving balanced prediction of processing air volume and output, as well as material balance. Detailed Implementation

[0029] The technical solutions in the embodiments of the present invention will be described clearly, completely, and in further detail below. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0030] Example 1:

[0031] An automatic constant load control method for an air separation unit, the specific technical solution of which is as follows:

[0032] I. Module program calculates flow

[0033] 1. Actual oxygen flow rate = (processing air volume - bypass air volume) × 20.93% × oxygen extraction rate (substitute this data based on the extraction rate statistically obtained from the long-term operation of each set of equipment).

[0034] Example: 30252=(156000-10000)×20.93%×99%

[0035] 2. Actual nitrogen flow rate = (processing air volume - bypass air volume) × 78.03% × nitrogen purity - waste nitrogen flow rate.

[0036] Example: 78992=(156000-10000)×78.03%×99.999%-35000

[0037] 3. Process argon flow rate = (processing air volume - bypass air volume) × 0.932% × argon extraction rate (substitute this data with the extraction rate statistically obtained from the long-term operation of each set of equipment).

[0038] Example: 1020=(156000-10000)×0.932%×75%

[0039] 4. According to the material balance, the flow rate of waste nitrogen = processing air volume - oxygen production - nitrogen production - argon production.

[0040] Example: 45736=156000-30252-78992-1020

[0041] II. Editing module system, calculating raw material flow rate

[0042] 1. Raw material air flow rate = Oxygen production ÷ 20.93% ÷ Oxygen extraction rate of fractionation system + Bypass air volume.

[0043] 2. Process argon flow rate = Oxygen production × Argon fraction flow rate multiple.

[0044] Among them, the argon fraction flow rate multiple is 1.02-1.05.

[0045] III. Material Balance Module System

[0046] 1. The material balance module system tracks the air flow of the raw material in the purification system using the air guide vane, and the editing module system controls the air flow of the purification system to maintain a constant processing air volume using the air guide vane.

[0047] 2. The editing module system controls the oxygen production regulating valve to track the actual oxygen flow rate, and uses oxygen purity adjustment to limit the oxygen production adjustment too quickly and to correct deviations.

[0048] 3. The editing module system controls the nitrogen production regulating valve to track the actual oxygen flow rate and the oxygen-nitrogen ratio, adjusting and limiting excessively rapid nitrogen production adjustments and correcting deviations.

[0049] 4. The editing module system controls the waste nitrogen production regulating valve to track the actual waste nitrogen flow rate and adjust the waste nitrogen production.

[0050] 5. The expansion air volume tracking module controls the expansion compressor nozzle opening and bypass valve to adjust the amount of expansion air entering the upper tower for processing and the bypass air volume.

[0051] 6. Process argon flow regulating valve tracking process argon flow editing module system control.

[0052] 7. The nitrogen production regulating valve, the main heat exchanger inlet air distribution valve, the expander bottom extraction valve, the purification system waste nitrogen regeneration valve, and the waste nitrogen to water cooling tower regulating valve are all automatically controlled and regulated under different loads in the editing module system.

[0053] Fourth, the programmable variable load controller converts the input oxygen production into the required processing air volume and pushes it to the constant flow control of the air permeable guide vanes in the material balance module program.

[0054] V. Editing module system control: In the event of a sudden shutdown, the aforementioned nitrogen production regulating valve, main heat exchanger inlet air distribution valve, expander bottom extraction valve, purification system waste nitrogen regeneration valve, and waste nitrogen to water cooling tower regulating valve will all switch to manual operation. This is to prevent accidents in the air separation unit.

[0055] VI. The above module operations require the collection of important data during the operation of the air separation unit. Based on the different performance of each air separation unit, the programming is based on the model derived from the collected data.

[0056] Due to differences in the age of the equipment, some equipment may have fewer automatic valve controls and flow meters installed. The above functions can be selectively used to achieve automatic or semi-automatic variable load operation of the air separation unit.

[0057] This invention is not limited to the above-described embodiments. Anyone should know that any structural changes made under the guidance of this invention, and any technical solutions that are the same as or similar to this invention, fall within the protection scope of this invention.

[0058] The technologies, shapes, and structures not described in detail in this invention are all known technologies.

Claims

1. An automatic constant load control method of an air separation plant, characterized by, It comprises the following steps: 1) The air flow of the air transparent guide vane of the material balance module system tracks the raw material air flow of the purification system, the raw material air flow = oxygen production ÷ 20.93% ÷ oxygen extraction rate of the fractionation system + bypass air amount; the process argon flow = oxygen production × argon fraction flow multiple, wherein: the argon fraction flow multiple is 1.02-1.05; the editing module system controls the constant air flow of the air transparent guide vane of the purification system; 2) The editing module system controls the oxygen production regulating valve to track the actual oxygen flow, the actual oxygen flow = (the process air flow - the bypass air flow) × 20.93% × the oxygen extraction rate, and the oxygen production is adjusted to limit the adjustment of the oxygen production from being too fast and to correct the deviation; 3) The editing module system controls the nitrogen production regulating valve to track the oxygen and nitrogen multiple of the actual oxygen flow, and adjusts the nitrogen production to limit the adjustment of the nitrogen production from being too fast and to correct the deviation; 4) The editing module system controls the waste nitrogen production regulating valve to track the actual waste nitrogen flow, the actual nitrogen flow = (the process air flow - the bypass air flow) × 78.03% × the nitrogen purity - waste nitrogen flow, and the waste nitrogen production is adjusted; 5) The expansion air flow tracks the oxygen production or the process air flow of the editing module to control the nozzle opening degree of the expander and the bypass valve, and the expansion air into the upper tower is adjusted to the process air flow and the bypass air flow; 6) The process argon flow regulating valve is controlled by the editing module system; the process argon flow = (the process air flow - the bypass air flow) × 0.932% × the argon extraction rate; according to the material balance, the waste nitrogen flow = the process air flow - the oxygen production - the nitrogen production - the argon production; 7) The nitrogen production regulating valve, the air distribution valve of the main heat exchanger, the bottom extraction valve of the expander, the waste nitrogen regeneration valve of the purification system, and the waste nitrogen water cooling tower regulating valve are all automatically adjusted by the editing module system under different loads.

2. The automatic constant load control method of an air separation apparatus according to claim 1, characterized by, In the step 5), the expansion air flow tracks the oxygen production, when the input oxygen production is input, the editing module system is converted into the process air flow, which is pushed to the constant flow control of the air transparent guide vane of the material balance module system.

3. The automatic constant load control method of the air-spaced device according to claim 1, characterized in that, In the step 6), when a sudden shutdown occurs, the editing module system is in the control state, and the nitrogen production regulating valve, the air distribution valve of the main heat exchanger, the bottom extraction valve of the expander, the waste nitrogen regeneration valve of the purification system, and the waste nitrogen water cooling tower regulating valve are all manually operated to prevent accidents of the air separation device.

4. The automatic constant load control method of an air-spaced device according to claim 1, wherein, The editing module system is a DCS module system.