Air separation plant stable operation method based on molecular sieve

Abstract

The invention provides an air separation plant stable operation method based on molecular sieves. The air separation plant stable operation method comprises the following steps that a pressure sensor and a temperature sensor are arranged in an air separation plant to detect the adsorption pressure and temperature of an A-group molecular sieve and a B-group molecular sieve in real time; calculating the adsorption resistance of the group A molecular sieve based on the adsorption pressure and temperature of the group A molecular sieve, and calculating the adsorption resistance of the group B molecular sieve based on the adsorption pressure and temperature of the group B molecular sieve; the adsorption resistance is compared with a preset resistance threshold value, and whether the adsorption resistance exceeds the preset resistance threshold value or not is judged; and when the adsorption resistance exceeds a preset resistance threshold value, adjusting the operation parameters of the molecular sieve, recalculating the adsorption resistance, and comparing the adsorption resistance with the preset resistance threshold value until the adsorption resistance is less than or equal to the preset resistance threshold value. Degradation of air separation rectification working conditions is avoided, and the purity and the yield of gas products are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of air separation and rectification, and in particular to a method for stable operation of an air separation device based on molecular sieves. Background Art

[0002] Air separation and distillation technologies play a vital role in modern industrial production. Air separation and distillation utilizes distillation towers to separate air. By utilizing the differences in boiling points between different gas components, this technology allows for the efficient extraction of key gases like oxygen and nitrogen, providing critical support for the normal operation of air separation equipment and industrial production.

[0003] Currently, several technologies exist for the application of molecular sieves in air separation processes. Typically, a specific type of molecular sieve is used as an adsorption material to absorb impurities and other substances from the air, thereby optimizing the air separation and distillation process. During operation, the adsorption and subsequent treatment of the molecular sieve are controlled according to specific process parameters and procedures, aiming to enhance gas separation efficiency and meet certain industrial production requirements.

[0004] However, existing technologies have significant shortcomings when dealing with A / B dual molecular sieve systems. As air separation systems age, the physical and chemical properties of the A and B molecular sieves deteriorate differently. Existing correction methods typically only optimize a single type of molecular sieve. For complex systems containing both A and B molecular sieves, these methods are unable to effectively address the deterioration of air separation distillation conditions caused by differences in their adsorption characteristics under different resistances. The correction effect is difficult to achieve ideal, making it difficult to meet the needs of long-term, stable, and efficient air separation distillation condition control. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to propose a method for stable operation of an air separation device based on molecular sieves to solve the problem of deterioration of the existing air separation distillation conditions.

[0006] The technical means adopted in the present invention are as follows:

[0007] A method for stable operation of an air separation plant based on molecular sieves comprises the following steps:

[0008] A pressure sensor and a temperature sensor are set in the air separation equipment to detect the adsorption pressure and temperature of the molecular sieve group A and the molecular sieve group B in real time;

[0009] When it is detected that the adsorption pressure and temperature of the molecular sieve group A are inconsistent with the adsorption pressure and temperature of the molecular sieve group B, the adsorption resistance of the molecular sieve group A is calculated based on the adsorption pressure and temperature of the molecular sieve group A, and the adsorption resistance of the molecular sieve group B is calculated based on the adsorption pressure and temperature of the molecular sieve group B;

[0010] comparing the adsorption resistance with a preset resistance threshold to determine whether the adsorption resistance exceeds the preset resistance threshold;

[0011] When the adsorption resistance exceeds the preset resistance threshold, the operating parameters of the molecular sieve are adjusted, and the adsorption resistance is recalculated and compared with the preset resistance threshold until the adsorption resistance is less than or equal to the preset resistance threshold.

[0012] Furthermore, the pressure sensor is arranged at the inlet and outlet of group A molecular sieve and the inlet and outlet of group B molecular sieve; the temperature sensor is arranged at the inlet and outlet of group A molecular sieve and the inlet and outlet of group B molecular sieve.

[0013] Furthermore, the formula for calculating the adsorption resistance of group A molecular sieve and group B molecular sieve is as follows:

[0014]

[0015] Where R is the adsorption resistance; ΔP is the molecular sieve bed pressure difference, that is, the difference between the inlet pressure and the outlet pressure; Q is the gas volume flow rate, and μ(T) is the dynamic viscosity of the gas at temperature T.

[0016] Furthermore, the specific strategy for adjusting the operating parameters of the molecular sieve is as follows:

[0017] Resistance exceeds the preset resistance threshold of 0-5kPa: flow rate increases by 0.3%-0.5%;

[0018] If the resistance exceeds the preset resistance threshold by more than 5kPa: the flow rate increases by 0.6%-1.0% and the pressure is adjusted in conjunction;

[0019] Monitor the air fractionation distillation conditions after adjusting the operating parameters in real time. If the conditions are improved, maintain the current operating parameters.

[0020] Furthermore, the preset resistance threshold is the resistance value when the molecular sieve of the air separation system is put into use and the adsorption capacity is optimal.

[0021] The present invention also provides a storage medium, which includes a stored program, wherein when the program is run, any of the above-mentioned methods for stable operation of an air separation device based on molecular sieves is executed.

[0022] The present invention also provides an electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes any of the above-mentioned methods for stable operation of an air separation device based on molecular sieves through the operation of the computer program.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] The present invention can accurately calculate the adsorption resistance of each group of molecular sieves by real-time monitoring of the adsorption pressure and temperature of the two groups of molecular sieves A and B, providing a reliable basis for timely adjustment of operating parameters. This method can flexibly adjust the operating parameters corresponding to each group of molecular sieves according to the change in adsorption resistance, ensuring stable operation of the equipment under different resistances. It can effectively prevent the deterioration of air separation distillation conditions due to changes in the adsorption resistance of A / B molecular sieves, improve the purity and output of gas products, and increase the oxygen purity from 99.8% of the traditional method to 99.99%. This correction method is highly versatile and applicable to different air separation equipment and molecular sieve combinations. In a certain 60,000 Nm 3 / h air separation equipment to reduce the A / B molecular sieve resistance fluctuation by 40%, with high practical value. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] 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 any creative labor.

[0026] Figure 1 Flow chart of the method of the present invention. DETAILED DESCRIPTION

[0027] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions 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 embodiments described are only 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 making creative efforts should fall within the scope of protection of the present invention.

[0028] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0029] like Figure 1As shown, the present invention provides a method for stable operation of an air separation plant based on molecular sieves, comprising the following steps:

[0030] Pressure sensors and temperature sensors are set in the air separation equipment to detect the adsorption pressure and temperature of group A molecular sieve and group B molecular sieve in real time; the pressure sensors are set at the inlet and outlet of group A molecular sieve and the inlet and outlet of group B molecular sieve; the temperature sensors are set at the inlet and outlet of group A molecular sieve and the inlet and outlet of group B molecular sieve.

[0031] The adsorption resistance of the molecular sieve of group A is calculated based on the adsorption pressure and temperature of the molecular sieve of group A, and the adsorption resistance of the molecular sieve of group B is calculated based on the adsorption pressure and temperature of the molecular sieve of group B;

[0032] The formula for calculating the adsorption resistance of group A molecular sieve and group B molecular sieve is as follows:

[0033]

[0034] Where R is the adsorption resistance, ΔP is the molecular sieve bed pressure difference (i.e., the difference between the adsorption pressure and the desorption pressure), Q is the gas volume flow rate, and μ(T) is the dynamic viscosity of the gas at temperature T.

[0035] The adsorption resistance is compared with the preset resistance threshold to determine whether the adsorption resistance exceeds the preset resistance threshold. The preset resistance threshold is used in this scheme. The resistance threshold is not set arbitrarily. Its derivation is based on the following: the resistance threshold is an empirical value in the production process and is not fixed. It refers to the resistance value when the molecular sieve of the air separation system is just put into use and the adsorption capacity is optimal.

[0036] If the adsorption resistance of group A molecular sieve or group B molecular sieve exceeds the resistance threshold, the operating parameters corresponding to each group of molecular sieves are adjusted respectively, including adjusting the feed flow rate, changing the adsorption pressure or desorption pressure, etc., to reduce the adsorption resistance; when the adsorption resistance exceeds the preset resistance threshold, after adjusting the operating parameters of the molecular sieve, the adsorption resistance is recalculated and compared with the preset resistance threshold until the adsorption resistance is less than or equal to the preset resistance threshold.

[0037] Resistance exceeds the preset resistance threshold of 0-5kPa: flow rate increases by 0.3%-0.5%;

[0038] If the resistance exceeds the preset resistance threshold by more than 5kPa: the flow rate increases by 0.6%-1.0% and the pressure is adjusted in conjunction;

[0039] Monitor the air fractionation distillation conditions after adjusting the operating parameters in real time. If the conditions are improved, maintain the current operating parameters.

[0040] Example

[0041] In a large air separation plant, the air separation unit uses two molecular sieves, A and B, as adsorbents. To prevent deterioration in air separation distillation conditions under varying resistances, the plant implemented the correction method of the present invention. During operation, the molecular sieve A resistance (PDI) 2603 and the molecular sieve B resistance (PDI) 2604 are monitored in real time. PDI 2603 is the difference between the molecular sieve A inlet pressure (PT) 2603 and the air separation tower inlet pressure (PT) 2615. PDI 2604 is the difference between the molecular sieve B inlet pressure (PT) 2604 and the air separation tower inlet pressure (PT) 2615. If the molecular sieves operate for extended periods of time and the packing is not replaced, PDI 2603 and PDI 2604 will gradually increase, indicating molecular sieve degradation. Before replacing the packing, two sets of thresholds are set to ensure stable operation of the unit. These thresholds are displayed on the operator interface and can be adjusted by process operators based on the unit's operating status. Each molecular sieve group has two thresholds and corresponding air volume increase or decrease correction values. When the resistance exceeds threshold 1, the incoming air volume is increased by threshold correction 1. When the resistance exceeds threshold 2, the incoming air volume is increased by threshold correction 2. By continuously adjusting operating parameters, the adsorption resistance of each group of molecular sieves is kept at a low level, thus ensuring stable operation of the air separation and distillation process. Through practical application, the plant has successfully avoided deterioration of the air separation and distillation process and improved the purity and yield of gas products.

[0042] 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 above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for stable operation of an air separation plant based on molecular sieves, characterized in that: The steps include: A pressure sensor and a temperature sensor are set in the air separation equipment to detect the adsorption pressure and temperature of the molecular sieve group A and the molecular sieve group B in real time; When it is detected that the adsorption pressure and temperature of the molecular sieve group A are inconsistent with the adsorption pressure and temperature of the molecular sieve group B, the adsorption resistance of the molecular sieve group A is calculated based on the adsorption pressure and temperature of the molecular sieve group A, and the adsorption resistance of the molecular sieve group B is calculated based on the adsorption pressure and temperature of the molecular sieve group B; comparing the adsorption resistance with a preset resistance threshold to determine whether the adsorption resistance exceeds the preset resistance threshold; When the adsorption resistance exceeds the preset resistance threshold, the operating parameters of the molecular sieve are adjusted, and the adsorption resistance is recalculated and compared with the preset resistance threshold until the adsorption resistance is less than or equal to the preset resistance threshold.

2. The method for stable operation of an air separation plant based on molecular sieve according to claim 1, characterized in that: The pressure sensors are arranged at the inlet and outlet of the molecular sieve group A and the inlet and outlet of the molecular sieve group B; the temperature sensors are arranged at the inlet and outlet of the molecular sieve group A and the inlet and outlet of the molecular sieve group B.

3. The method for stable operation of an air separation plant based on molecular sieve according to claim 1, characterized in that: The formula for calculating the adsorption resistance of group A molecular sieve and group B molecular sieve is as follows: Where R is the adsorption resistance; ΔP is the molecular sieve bed pressure difference, that is, the difference between the inlet pressure and the outlet pressure; Q is the gas volume flow rate, and μ(T) is the dynamic viscosity of the gas at temperature T.

4. The method for stable operation of an air separation plant based on molecular sieve according to claim 1, characterized in that: The specific strategies for adjusting the operating parameters of molecular sieves are as follows: Resistance exceeds the preset resistance threshold of 0-5kPa: flow rate increases by 0.3%-0.5%; If the resistance exceeds the preset resistance threshold by more than 5kPa: the flow rate increases by 0.6%-1.0% and the pressure is adjusted in conjunction; Monitor the air fractionation distillation conditions after adjusting the operating parameters in real time. If the conditions are improved, maintain the current operating parameters.

5. The method for stable operation of an air separation plant based on molecular sieve according to claim 1, characterized in that: The preset resistance threshold is the resistance value when the molecular sieve of the air separation system is put into use and the adsorption capacity is optimal.

6. A storage medium, characterized in that The storage medium includes a stored program, wherein when the program is run, the method for stable operation of an air separation plant based on molecular sieve according to any one of claims 1 to 5 is executed.

7. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: The processor executes the method for stable operation of an air separation plant based on molecular sieves according to any one of claims 1 to 5 by running the computer program.

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