An intelligent diagnosis system for the operating condition of oxygen-generating air separation system

Abstract

The present invention relates to the technical field of equipment intelligent diagnosis, and specifically discloses an intelligent diagnosis system for the health of the operating condition of an oxygen-making air separation system. The system mainly performs intelligent health diagnosis on the operating conditions of each subsystem of the oxygen generator to solve the problem of low health of the overall operating condition of the oxygen generator unit, and meets the requirements of stable operation and efficiency improvement of the oxygen generator unit. The system mainly includes seven modules: precooling system: energy efficiency diagnosis, energy balance; purification system: molecular sieve adsorption performance cracking diagnosis; expander system: expander energy efficiency diagnosis; main heat exchanger system: air separation cooling capacity balance diagnosis; distillation tower system: oxygen extraction rate, argon extraction rate; argon system: nitrogen plugging early warning diagnosis; comprehensive health diagnosis of the oxygen generator unit. During the operation of the oxygen generator unit, the present invention performs real-time health diagnosis on the operating conditions of each subsystem to provide the operator with the comprehensive health of the oxygen generator unit operation, so as to make a basis for operational adjustment in terms of safety, economy and stability.

Description

Technical Field

[0001] The present invention relates to the technical field of equipment intelligent diagnosis, and in particular to an intelligent diagnosis system for the operating condition of an oxygen production air separation system. Background Art

[0002] The oxygen production air separation system includes six major subsystems: precooling system, purification system, expander system, main heat exchanger system, distillation tower system, and argon system. The operating conditions of each system must be closely coordinated to form a continuous air purification, cooling, liquefaction and distillation process to achieve high product purity and high yield, while also having operational economy, which is suitable for the healthy and stable operation of the unit.

[0003] At present, there is no precedent for online real-time health diagnosis of each air separation subsystem of large and medium-sized oxygen production units at home and abroad. Therefore, it is necessary to design an intelligent diagnosis system for the operating condition of oxygen production air separation system to solve the problem of low overall operating condition health of existing oxygen production units. Summary of the invention

[0004] In view of the problems existing in the prior art, the object of the present invention is to provide an intelligent diagnosis system for the operating condition of an oxygen-producing air separation system.

[0005] The technical solution adopted by the present invention to solve the technical problem is: an intelligent diagnosis system for the operating condition of an oxygen-generating air separation system, including a precooling system, a purification system, an expander system, a main heat exchanger system, a fractionation tower system, a nitrogen plugging early warning system and a comprehensive health diagnosis system for oxygen-generating units.

[0006] The precooling system: performs health diagnosis on the energy efficiency and energy balance of the air cooling tower for the precooling system;

[0007] The purification system: performs cracking diagnosis on the adsorption performance according to the operating conditions of the molecular sieve of the purification system;

[0008] The expander system: diagnoses and monitors the energy efficiency of the expander in the expander refrigeration system.

[0009] According to the inlet and outlet temperatures, inlet and outlet pressures and ratios of the expander, the isentropic efficiency of the expander is calculated and used as the energy efficiency of the equipment for diagnosis, and the diagnosis results are used as the basis for adjusting the operating conditions of the expander;

[0010] The main heat exchanger system: monitors and diagnoses the overall cooling balance of the oxygen generator unit.

[0011] According to the main heat exchanger system as the main equipment for cold exchange, the cold loss due to the temperature difference at the hot end of the main heat exchanger and the cold taken away by the liquid product during the production process of the fractionation tower are diagnosed with the total refrigeration capacity of the expander, and their ratio is monitored as the cold balance of the unit to diagnose whether the system cold capacity is fully utilized, that is, the cold balance is used as the basis for judging the energy consumption of the unit;

[0012] The fractionation tower system: monitors the oxygen extraction rate and argon extraction rate of the product according to the operating conditions of the fractionation tower;

[0013] The nitrogen plugging early warning system: The nitrogen plugging early warning is mainly aimed at the process of operating condition changes and frequent failures of the distillation tower argon system, and diagnoses and warns the nitrogen plugging phenomenon that is most harmful to the system;

[0014] The comprehensive health diagnosis of the oxygen generator unit: establish the comprehensive health of the system, combine the diagnosis results of the previous six system modules and the key parameters of each system part, formulate scoring standards, use the logical diagnosis results as the key scoring items, and finally obtain the comprehensive health of the system.

[0015] Specifically, the energy efficiency of the air-cooling tower in the pre-cooling system is mainly calculated by calculating the heat exchange process between the positive flow air in the air-cooling tower and the two-way circulating cooling water, and the results after the heat exchange, to determine whether the temperature of the higher temperature positive flow air after being cooled meets the process requirements after heat exchange with the countercurrent normal temperature water and chilled water.

[0016] Specifically, the energy balance of the air cooling tower in the precooling system mainly calculates whether the heat released or the cold absorbed by the positive flow air with a higher temperature is balanced with the heat absorbed or the cold released between the two cooling waters of normal temperature water and chilled water, and mainly determines whether the loss of the system's cold capacity is minimal.

[0017]

[0018] In the formula:

[0019] Numerator: The heat released or the cold absorbed by the positive flow air with higher temperature.

[0020] Denominator: The heat absorbed or the cold released by the normal temperature cooling water and the lower temperature chilled water.

[0021] Specifically, the steps of cracking diagnosis of molecular sieve adsorption performance of the purification system are:

[0022] 1) Mainly monitor the changes in the outlet carbon dioxide content during the molecular sieve adsorption cycle. The outlet CO2 content of the molecular sieve is controlled to be less than 1.0ppm. When the rising rate exceeds 0.2ppm / 10 minutes, an alarm is issued and disposal suggestions are popped up;

[0023] 2) Mainly monitor the changes in the cold blowing peak value during the molecular sieve heating regeneration cycle; the cold blowing peak value control range is between 120℃ and 150℃. When it exceeds this range, the system will issue an alarm and pop up disposal suggestions;

[0024] 3) According to the changes in carbon dioxide content and cold blowing peak value, compared with the changes in adsorption capacity, the cracking degree of the molecular sieve is judged. The system automatically integrates the air flow, outlet carbon dioxide content and the changes in cold blowing peak value during the regeneration cycle, comprehensively analyzes the cracking degree of the molecular sieve, and automatically pops up suggestions for operation or maintenance and replacement.

[0025] Specifically, the logic calculation of the expander energy efficiency is:

[0026]

[0027] In the formula: η s is the isentropic efficiency of the expander;

[0028] C p The constant pressure specific volume heat, the inlet pressure of the oxygen expander expansion end is 0.68MPa, the medium is air, and the value is 1.005J / (kg·K);

[0029] K is the adiabatic index, which is 1.403;

[0030] ΔT is the temperature difference between the inlet and outlet of the expansion end of the expander, which is taken according to the actual measurement;

[0031] Z is the gas compressibility coefficient, which is 0.982;

[0032] R is the ideal gas constant, which is 0.287;

[0033] ε is the ratio of the outlet pressure to the inlet pressure at the expansion end of the expander, and is taken according to actual measurement.

[0034] Specifically, the calculation process of the cooling balance of the main heat exchanger system is:

[0035] Q2: The cooling capacity taken away by the temperature difference between the reflux oxygen, nitrogen, dirty nitrogen and the air entering the tower;

[0036] Q3: The cooling capacity taken away by liquid oxygen and liquid argon products;

[0037] Q4: Refrigeration capacity of expansion mechanism;

[0038] Cooling capacity balance P = (Q2 + Q3) / Q4.

[0039] Specifically, the oxygen extraction rate in the fractionation tower system: mainly for the diagnosis of material balance, the oxygen content in the air entering the tower and the oxygen output extracted are used to diagnose the input-output ratio to judge the performance of the oxygen generator unit;

[0040] Oxygen extraction rate = (oxygen production × oxygen purity + liquid oxygen production converted to gaseous oxygen production × oxygen purity) ÷ (total amount of air entering the tower × oxygen content in the air).

[0041] Specifically, the argon extraction rate in the fractionation tower system: mainly diagnoses the operating efficiency of the argon system, and diagnoses the input-output ratio of the argon component content in the air entering the tower and the amount of extracted argon product to determine the performance of the argon system of the oxygen generator;

[0042] Argon extraction rate = (argon production × argon purity) ÷ (total amount of air entering the tower × argon content in the air).

[0043] Specifically, the warning logic of the nitrogen blockage warning system includes: the process argon temperature drop rate and the drop limit value; the process argon argon content drop rate and the drop limit value; the refined argon tower pressure rise rate and the upper limit value; the crude argon condenser liquid air level rise rate and the upper limit value.

[0044] The present invention has the following beneficial effects:

[0045] The oxygen-generating air separation system operating condition health intelligent diagnosis system designed by the present invention provides the operator with the comprehensive health of the oxygen-generating unit operation by performing real-time health diagnosis on the operating conditions of each subsystem during the operation of the oxygen-generating unit, so as to make a basis for operational adjustment in terms of safety, economy and stability.

[0046] Without any reference, the health diagnosis of the operating conditions of each subsystem of the oxygen generator unit is automatically carried out through data analysis and calculation, ensuring that reasonable operating basis and support are provided to the operator to achieve the purpose of optimizing the system operating conditions and optimizing energy consumption. The comprehensive health of this system directly reflects the economy and stability of the overall operation of the unit, and the diagnostic results are simple and clear. DETAILED DESCRIPTION

[0047] The technical solutions in the embodiments of the present invention are described in detail below. 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.

[0048] An intelligent diagnosis system for the operating condition of an oxygen-generating air separation system mainly solves the problem of low overall operating condition health of the oxygen generator unit by performing intelligent health diagnosis on the operating conditions of each subsystem of the oxygen generator, and meets the requirements for stable operation and efficiency improvement of the oxygen generator unit. The main contents include seven modules, as follows:

[0049] (1) Precooling system: energy efficiency diagnosis and energy balance;

[0050] (2) Purification system: molecular sieve adsorption performance cracking diagnosis;

[0051] (3) Expander system: expander energy efficiency diagnosis;

[0052] (4) Main heat exchanger system: air separation cooling capacity balance diagnosis;

[0053] (5) Distillation tower system: oxygen extraction rate, argon extraction rate;

[0054] (6) Argon system: nitrogen blockage early warning diagnosis;

[0055] (7) Comprehensive health diagnosis of oxygen generator units.

[0056] Module 1: Health diagnosis of air cooling tower energy efficiency and energy balance for the precooling system.

[0057] ①Energy efficiency of air cooling tower: mainly through the heat exchange process between the positive flow air of the air cooling tower and the two-way circulating cooling water, and the results after the heat exchange are calculated to determine whether the temperature of the higher temperature positive flow air after being cooled meets the process requirements after the heat exchange with the countercurrent normal temperature water and chilled water;

[0058] ② Energy balance of air-cooling tower: mainly calculates whether the heat released (or the cold absorbed) by the higher temperature positive flow air is balanced with the heat absorbed (or the cold released) between the two cooling waters of normal temperature water and chilled water, mainly to determine whether the loss of cooling capacity of the system is minimal.

[0059]

[0060] In the formula:

[0061] Molecules: the heat released (or the cold absorbed) by the positive air flow with a higher temperature;

[0062] Denominator: The heat absorbed (or the cold released) by the normal temperature cooling water and the lower temperature chilled water.

[0063] Module 2: Crack diagnosis of adsorption performance based on the operating conditions of the molecular sieve in the purification system.

[0064] ① Mainly monitor the changes in the outlet carbon dioxide content during the molecular sieve adsorption cycle. The molecular sieve outlet CO2 content is controlled to be less than 1.0ppm. When the rising rate exceeds 0.2ppm / 10 minutes, an alarm is issued and disposal suggestions are popped up.

[0065] ② Mainly monitor the changes in the cold blowing peak value during the molecular sieve heating regeneration cycle; the cold blowing peak value control range is between 120℃ and 150℃. When it exceeds this range, the system will issue an alarm and pop up disposal suggestions.

[0066] ③ According to the changes of the two, the adsorption capacity is compared to determine the degree of molecular sieve cracking. The system automatically integrates the air flow, outlet carbon dioxide content and the peak change of cold blowing during the regeneration cycle, comprehensively analyzes the degree of molecular sieve cracking, and automatically pops up suggestions for operation or maintenance and replacement.

[0067] Module 3: Diagnose and monitor the energy efficiency of the expander in the expander refrigeration system.

[0068] According to the inlet and outlet temperatures, inlet and outlet pressures and ratios of the expander, the isentropic efficiency of the expander is calculated and used as the energy efficiency of the equipment for diagnosis. The diagnosis result is used as the basis for adjusting the operating conditions of the expander.

[0069] Expander energy efficiency logic calculation:

[0070]

[0071] In the formula:

[0072] (1)η s is the isentropic efficiency of the expander;

[0073] (2)C p The constant pressure specific volume heat, the inlet pressure of the oxygen expander expansion end is 0.68MPa, the medium is air, and the value is 1.005J / (kg·K);

[0074] (3) K is the adiabatic index, which is 1.403;

[0075] (4) ΔT is the temperature difference between the inlet and outlet of the expander, which is taken according to the actual measurement;

[0076] (5) Z is the gas compressibility coefficient, which is 0.982;

[0077] (6) R is the ideal gas constant, which is 0.287;

[0078] (7)ε is the ratio of the outlet pressure to the inlet pressure of the expander, which is taken according to the actual measurement.

[0079] Module 4: Monitor and diagnose the overall cooling balance of the oxygen generator unit.

[0080] According to the main heat exchanger system as the main equipment for cold exchange, the cold lost by the temperature difference at the hot end of the main heat exchanger and the cold taken away by the liquid product during the production process of the distillation tower are diagnosed with the total refrigeration capacity of the expander, and their ratio is monitored as the cold balance of the unit to diagnose whether the system cold capacity is fully utilized, that is, the cold balance is used as the basis for judging the energy consumption of the unit.

[0081] (1) Calculation process of cooling balance:

[0082] Q2: The cooling capacity taken away by the temperature difference between the reflux oxygen, nitrogen, dirty nitrogen and the air entering the tower

[0083] Q3: The cooling capacity taken away by liquid oxygen and liquid argon products

[0084] Q4: Refrigeration capacity of expansion mechanism

[0085] Cooling balance P = (Q2 + Q3) / Q4

[0086] That is: (reflux cooling + liquid cooling) / expansion mechanism cooling

[0087] (2) Actual calculation process:

[0088] Q o (Reflux oxygen) = FIQC102 × (TIA102-TIA101) × 1.429 × 0.92

[0089] Q N (Reflux nitrogen) = FIQC103 × (TIA103-TIA101) × 1.25 × 0.741

[0090] Q WN (Reflux Nitrogen) = FICAS1201 × (TIA105-TIA101) × 1.25 × 0.741 + (FI999-FI102-FI103-FIC701-V7 average opening × 10 × 800-FICAS1201) × (TIA104-TIA101) × 1.25 × 0.741

[0091] Note: The density and constant volume specific heat of contaminated nitrogen are substituted according to the data of pure nitrogen.

[0092] Q2=Q o +Q N +Q WN

[0093] Q3 = V7 average opening × 10 × 1.14 × 0.91895 × [TIA101-(-183)] + FIC701 × 1.784 × 0.312 × [TIA101-(-186)]

[0094] Q4=FI106×(TI41-TI42)×0.31×5.972 or FI106×(TI43-TI44)×0.31×5.972

[0095] Cooling balance P = (Q2 + Q3) / Q4

[0096] The fifth module: monitors the oxygen extraction rate and argon extraction rate of the product according to the operating conditions of the distillation tower;

[0097] (1) Oxygen extraction rate: mainly for material balance diagnosis, the oxygen content in the air entering the tower and the oxygen output extracted are used to diagnose the input-output ratio to judge the performance of the oxygen generator unit.

[0098] Oxygen extraction rate = (oxygen production × oxygen purity + liquid oxygen production converted to gas oxygen production × oxygen purity) ÷ (total amount of air entering the tower × oxygen content in the air)

[0099] (2) Argon extraction rate: This is mainly used to diagnose the operating efficiency of the argon system. The ratio of the argon component content in the air entering the tower to the amount of argon product extracted is used to diagnose the performance of the argon system of the oxygen generator.

[0100] Argon extraction rate = (argon production × argon purity) ÷ (total amount of air entering the tower × argon content in the air)

[0101] Module 6: Nitrogen plugging warning system

[0102] Nitrogen plugging warning is mainly aimed at the operating condition changes and frequent failures of the distillation tower argon system, and diagnoses and warns the nitrogen plugging phenomenon that is most harmful to the system.

[0103] Early warning logic: process argon temperature drop rate and drop limit; process argon argon content drop rate and drop limit; refined argon tower pressure rise rate and upper limit; crude argon condenser liquid air level rise rate and upper limit.

[0104] Module 7: Comprehensive system health: Combine the diagnostic results of the previous six modules and the key parameters of each system, formulate scoring standards, use the logical diagnosis results as the key scoring items, and finally determine the comprehensive health of the system.

[0105] The present invention is not limited to the above-mentioned implementation modes, and anyone should be aware of the structural changes made under the enlightenment of the present invention, and all those having the same or similar technical solutions as the present invention fall within the protection scope of the present invention.

[0106] The techniques, shapes, and structural parts not described in detail in the present invention are all well-known techniques.

Claims

1. An intelligent diagnosis system for the operating condition of an oxygen production air separation system, characterized in that: Including pre-cooling system, purification system, expander system, main heat exchanger system, fractionation tower system, nitrogen plugging warning system and comprehensive health diagnosis of oxygen generator, The precooling system: performs health diagnosis on the energy efficiency and energy balance of the air cooling tower for the precooling system; The purification system: cracking diagnosis of the adsorption performance of the molecular sieve of the purification system is performed according to the operating conditions of the molecular sieve of the purification system. The steps of cracking diagnosis of the adsorption performance of the molecular sieve of the purification system are: 1) Monitor the changes in the outlet carbon dioxide content during the molecular sieve adsorption cycle. The outlet CO2 content of the molecular sieve is controlled to be less than 1.0ppm. When the rising rate exceeds 0.2ppm / 10 minutes, an alarm is issued and disposal suggestions are popped up; 2) Monitor the changes in the cold blowing peak value during the molecular sieve heating regeneration cycle; the cold blowing peak value control range is between 120℃ and 150℃. When it exceeds this range, the system will issue an alarm and pop up disposal suggestions; 3) According to the changes in carbon dioxide content and cold blowing peak value, compared with the changes in adsorption capacity, the cracking degree of the molecular sieve is judged. The system automatically integrates the air flow, outlet carbon dioxide content and the cold blowing peak value changes during the regeneration cycle, comprehensively analyzes the cracking degree of the molecular sieve, and automatically pops up suggestions for operation or maintenance and replacement; The expander system: diagnoses and monitors the energy efficiency of the expander in the expander refrigeration system. According to the expander inlet and outlet temperatures, inlet and outlet pressures, and the ratio of outlet pressure to inlet pressure, the isentropic efficiency of the expander is calculated and used as the energy efficiency of the equipment for diagnosis. The diagnosis result is used as the basis for adjusting the expander working condition. The logical calculation of the expander energy efficiency is: Official: η s is the isentropic efficiency of the expander; C p The constant pressure specific volume heat, the inlet pressure of the oxygen expander expansion end is 0.68MPa, the medium is air, and the value is 1.005J / (kg·K); K is the adiabatic index, which is 1.403; The temperature difference between the inlet and outlet of the expander is taken according to the actual measurement; Z is the gas compressibility coefficient, which is 0.982; R is the ideal gas constant, which is 0.287; ε is the ratio of the outlet pressure to the inlet pressure of the expansion end of the expander, which is taken according to the actual measurement; The main heat exchanger system: monitors and diagnoses the overall cooling balance of the oxygen generator unit. According to the main heat exchanger system as the main equipment for cold exchange, the cold loss due to the temperature difference at the hot end of the main heat exchanger and the cold taken away by the liquid product during the production process of the fractionation tower are diagnosed with the total refrigeration capacity of the expander, and their ratio is monitored as the cold balance of the unit to diagnose whether the system cold capacity is fully utilized, that is, the cold balance is used as the basis for judging the energy consumption of the unit; The fractionation tower system: monitors the oxygen extraction rate and argon extraction rate of the product according to the operating conditions of the fractionation tower; The nitrogen plugging early warning system: The nitrogen plugging early warning system diagnoses and warns the nitrogen plugging phenomenon that is most harmful to the system in view of the change process of the operating conditions of the fractionation tower argon system and the frequent failures; The comprehensive health diagnosis of the oxygen generator unit: establish the comprehensive health of the system, combine the diagnosis results of the previous six system modules and the key parameters of each system part, formulate scoring standards, use the logical diagnosis results as the key scoring items, and finally obtain the comprehensive health of the system.

2. The oxygen production air separation system operating condition health intelligent diagnosis system according to claim 1 is characterized in that: Energy efficiency of the air cooling tower in the precooling system: by calculating the heat exchange process between the positive flow air of the air cooling tower and the two-way circulating cooling water, and the results after the heat exchange, it is determined whether the temperature of the higher temperature positive flow air after being cooled meets the process requirements after heat exchange with the countercurrent normal temperature water and chilled water.

3. The oxygen production air separation system operating condition health intelligent diagnosis system according to claim 1 is characterized in that: The energy balance of the air cooling tower in the precooling system: calculate the heat released or the cold absorbed by the higher temperature positive flow air, and whether it is balanced with the heat absorbed or the cold released between the two cooling waters of normal temperature water and chilled water, and judge whether the loss of system cold capacity is minimal. In the formula: Numerator: The heat released or the cold absorbed by the positive flow air with higher temperature. Denominator: The heat absorbed or the cold released by the normal temperature cooling water and the lower temperature chilled water.

4. The oxygen production air separation system operating condition health intelligent diagnosis system according to claim 1 is characterized in that: The calculation process of the cooling balance of the main heat exchanger system is: Q2: The cooling capacity taken away by the temperature difference between the reflux oxygen, nitrogen, dirty nitrogen and the air entering the tower; Q3: The cooling capacity taken away by liquid oxygen and liquid argon products; Q4: Refrigeration capacity of expansion mechanism; Cooling balance P = (Q2 + Q3) / Q4.

5. The oxygen production air separation system operating condition health intelligent diagnosis system according to claim 1 is characterized in that: Oxygen extraction rate in the fractionation tower system: for material balance diagnosis, the oxygen content in the air entering the tower and the oxygen output extracted are used to diagnose the input-output ratio to judge the performance of the oxygen generator unit; Oxygen extraction rate = (oxygen production × oxygen purity + liquid oxygen production converted to gaseous oxygen production × oxygen purity) ÷ (total amount of air entering the tower × oxygen content in the air).

6. The oxygen production air separation system operating condition health intelligent diagnosis system according to claim 1 is characterized in that: The argon extraction rate in the fractionation tower system: the argon system operating efficiency is diagnosed by diagnosing the input-output ratio of the argon component content in the air entering the tower and the amount of argon product extracted, so as to judge the performance of the oxygen generator unit argon system; Argon extraction rate = (argon production × argon purity) ÷ (total amount of air entering the tower × argon content in the air).

7. The oxygen production air separation system operating condition health intelligent diagnosis system according to claim 1 is characterized in that: The warning logic of the nitrogen plugging warning system: the process argon temperature drop rate and drop limit value; the process argon argon content drop rate and drop limit value; the argon tower pressure rise rate and upper limit value; Crude argon condenser liquid air level rise rate and upper limit.

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