Method and system for detecting purity of hydrogen and carbon dioxide of hydrogen-cooled generator

Abstract

The invention provides a method and system for detecting the purity of hydrogen and carbon dioxide of a hydrogen-cooled generator, and the purity of hydrogen and / or carbon dioxide adopts the following calculation formula: GSS (%) = (((100-DP / a * P0 / (P + P0) * (t + T0) / (t0 + T0)) / 93.04) * 100) * b / 107.3 + c, in the formula, GAS (%) is the gas purity of H2 and / or CO2; dP: MPa is the differential pressure measured by the purity signaling machine; t: DEG C, measuring the temperature; p is MPa, the pressure is measured, and P = Pg + P0; pg: MPa, the working pressure of the gas; p0 is MPa, and the pressure under the standard working condition is P0 = 0.1013 MPa; t0 is DEG C, and t0 is equal to 40 DEG C under the standard working condition; t0 is K, the absolute temperature is T0 = 273.15 K; a is a correction coefficient, and the range is 0.4-0.6; b: a correction coefficient with a range of 60-70; and c: a correction coefficient with a range of 30-40.

Description

Technical Field

[0001] This invention relates to the field of instrument testing technology for thermal power plant generator sets, specifically to a method and system for calculating and testing the purity of hydrogen and carbon dioxide in hydrogen-cooled generators of thermal power generator sets. Background Technology

[0002] Hydrogen-cooled generators in thermal power generating units are cooled by hydrogen. Hydrogen has good flow and thermal conductivity, which can significantly reduce the frictional resistance loss of the high-speed rotating rotor and the wind resistance loss of the stator and rotor ventilation cooling. This can greatly improve the generator efficiency and is non-corrosive to the internal structure and insulation materials of the generator. Therefore, generators in generating units mostly adopt hydrogen cooling for the stator core, rotor and stator windings.

[0003] The mixture ratio of hydrogen to air is within the explosive range of 4% to 74%, so the safety requirements for hydrogen systems are extremely high, and strict control and monitoring are necessary to prevent hydrogen explosion accidents.

[0004] Hydrogen is used as a cooling medium for generators. Changes in its pressure, temperature, purity, and humidity directly affect whether the generator can operate safely, stably, and efficiently. Therefore, accurate analysis and testing of various parameters of hydrogen are crucial.

[0005] The commonly used methods for measuring the purity of hydrogen in hydrogen-cooled generators are density method and thermal conductivity method. Among them, density measurement method is based on the principle of gas density. Mixed gases have different densities, which will produce different pressures at a certain flow rate. A purity transmitter generates a fixed flow rate to form a corresponding pressure difference. After pressure and temperature correction, it is converted into gas percentage concentration (i.e., purity).

[0006] When starting and stopping a generator set, gas purging is essential. The primary concern during purging is the risk of hydrogen explosion. To avoid direct contact between hydrogen and oxygen, an indirect purging method using an intermediate medium is employed. This method utilizes a stable gas (such as CO2) as the intermediate medium to replace the hydrogen in the generator with air, or vice versa. Therefore, in addition to accurately measuring the generator hydrogen purity during unit operation, the purity of CO2 and H2 in the mixed gases (air and CO2 mixture, CO2 and H2 mixture) generated during the generator's hydrogen charging or discharging processes must also be accurately measured and calculated during start-up and shutdown.

[0007] Traditional density-based measurements of generator hydrogen purity during unit operation, as well as CO2 and H2 purity during generator hydrogen charging or purging processes during unit start-up and shutdown, typically employ a dedicated purity calculation controller. Differential pressure, temperature, and pressure signals from the gas or gas mixture are fed into the controller after passing through a safety barrier and converter. The controller has built-in purity calculation and alarm functions, outputting data to field indicators and the DCS system. The main problems with this method include: ① Lack of transparency in the calculation method (the equipment manufacturer configures it within the controller, making it a black box); ② Inability to save historical data for relevant detection signals, making it difficult to trace and find the cause of inaccurate purity detection signals; ③ Controller failure directly leads to loss of hydrogen purity monitoring, posing a significant risk to production. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to overcome the above-mentioned deficiencies of the prior art and provide a method for detecting and calculating the purity of H2 under normal operating conditions of a generator, or the purity of CO2 and H2 in the mixed gas during hydrogen charging and discharging, so as to ensure the accuracy of hydrogen / carbon dioxide purity detection and calculation under various operating conditions of the unit and the traceability of abnormal causes, thereby ensuring the safe, stable and reliable operation of the generator set.

[0009] The technical problem it aims to solve can be addressed through the following technical solutions.

[0010] A method for detecting the purity of hydrogen and carbon dioxide in a hydrogen-cooled generator, wherein the purity of hydrogen and / or carbon dioxide is calculated using the following formula during the detection process:

[0011] GAS(%)=(((100-DP / a×P0 / (P+P0)×(t+T0) / (t0+T0)) / 93.04)×100)×b / 107.3+c

[0012] in:

[0013] GAS (%): Gas purity of H2 and / or CO2;

[0014] DP: MPa, differential pressure measured by a purity transmitter;

[0015] t: °C, measured temperature;

[0016] P: MPa, measured pressure, P = Pg + P0;

[0017] Pg: MPa, working pressure of gas;

[0018] P0: MPa, pressure under standard operating conditions, P0 = 0.1013 MPa;

[0019] t0: °C, under standard operating conditions, t0 = 40 °C;

[0020] T0: K, absolute temperature, T0 = 273.15 K;

[0021] a: Correction factor, ranging from 0.4 to 0.6;

[0022] b: Correction factor, ranging from 60 to 70;

[0023] c: Correction factor, ranging from 30 to 40.

[0024] Another technical problem to be solved by this invention is to provide a system for detecting the purity of hydrogen and carbon dioxide in a hydrogen-cooled generator. The detection signals of differential pressure, temperature, and pressure of the gases inside the generator are respectively transmitted through a differential pressure transmitter, a pressure transmitter, a thermal resistor, and a correction pressure transmitter, and then respectively connected to a purity calculation and regulation unit via a differential pressure transducer, a first pressure transducer, a temperature transducer, and a second pressure transducer. The purity calculation and regulation unit includes a first gas purity calculation module that can convert internal calculations into purity values, and an alarm module. The differential pressure transducer, the first pressure transducer, and the temperature transducer are connected to the first gas purity calculation module, and the second pressure transducer is connected to the alarm module.

[0025] It also includes a DCS system arranged in parallel with the purity calculation regulator. The differential pressure converter, the first pressure converter, the temperature converter, and the second pressure converter are each connected to a distributor. The corresponding signals are processed by the corresponding distributors and then sent to the purity calculation regulator and the DCS system. The DCS system is embedded with a second gas purity calculation module for calculating gas purity.

[0026] Furthermore, the first gas purity calculation module calculates the purity of hydrogen and / or carbon dioxide using the following formula:

[0027] GAS(%)=(((100-DP / a×P0 / (P+P0)×(t+T0) / (t0+T0)) / 93.04)×100)×b / 107.3+c

[0028] in:

[0029] GAS (%): Gas purity of H2 and / or CO2;

[0030] DP: MPa, differential pressure measured by a purity transmitter;

[0031] t: °C, measured temperature;

[0032] P: MPa, measured pressure, P = Pg + P0;

[0033] Pg: MPa, working pressure of gas;

[0034] P0: MPa, pressure under standard operating conditions, P0 = 0.1013 MPa;

[0035] t0: °C, under standard operating conditions, t0 = 40 °C;

[0036] T0: K, absolute temperature, T0 = 273.15 K;

[0037] a: Correction factor, ranging from 0.4 to 0.6;

[0038] b: Correction factor, ranging from 60 to 70;

[0039] c: Correction factor, ranging from 30 to 40.

[0040] Furthermore, the second gas purity calculation module calculates the purity of hydrogen and / or carbon dioxide using the following formula:

[0041] GAS(%)=(((100-DP / a×P0 / (P+P0)×(t+T0) / (t0+T0)) / 93.04)×100)×b / 107.3+c

[0042] in:

[0043] GAS (%): Gas purity of H2 and / or CO2;

[0044] DP: MPa, differential pressure measured by a purity transmitter;

[0045] t: °C, measured temperature;

[0046] P: MPa, measured pressure, P = Pg + P0;

[0047] Pg: MPa, working pressure of gas;

[0048] P0: MPa, pressure under standard operating conditions, P0 = 0.1013 MPa;

[0049] t0: °C, under standard operating conditions, t0 = 40 °C;

[0050] T0: K, absolute temperature, T0 = 273.15 K;

[0051] a: Correction factor, ranging from 0.4 to 0.6;

[0052] b: Correction factor, ranging from 60 to 70;

[0053] c: Correction factor, ranging from 30 to 40.

[0054] Furthermore, the differential pressure of the gas inside the generator is generated by a purity transmitter.

[0055] Furthermore, the alarm module of the purity calculation regulator is connected to the DCS system signal.

[0056] Furthermore, the DCS system is equipped with a historical data query module.

[0057] Furthermore, the DCS system is also equipped with a display terminal that can show the gas purity calculation process.

[0058] Furthermore, the detection parameter exceeding the limit and sensor fault alarm result signals generated by the purity calculation regulator are output to the indicator terminal of the field sealing oil pan.

[0059] The method and system for detecting the purity of hydrogen and carbon dioxide in a hydrogen-cooled generator using the above-mentioned technical solution have the following characteristics and beneficial effects:

[0060] This invention addresses the problems existing in the prior art by researching and deriving a unified calculation formula for the purity of H2 in generators using density measurement methods, as well as the purity of CO2 and H2 in the mixed gas during the hydrogen charging or discharging process of the generator. It also solves the various drawbacks of the aforementioned gas purity detection circuits. By adopting an improved method for detecting and calculating the purity of hydrogen / carbon dioxide in hydrogen-cooled generators, it ensures the accuracy of hydrogen / carbon dioxide purity detection and calculation under various operating conditions of the unit and makes the causes of abnormalities traceable, thus ensuring the safe, stable, and reliable operation of the generator set.

[0061] Practical verification shows that the gas purity calculation formula is applicable to monitoring H2 purity under unit operating conditions, as well as monitoring the H2 and CO2 purity of mixed gases under generator hydrogen charging and purging conditions, and the accuracy of the calculation results meets the requirements. Attached Figure Description

[0062] Figure 1 This is a schematic diagram of the improved gas purity detection system of the present invention;

[0063] Figure 2 Verify the parameter curves for the gas differential pressure y (%) and output gas density x (%) input to the gas calculation regulator (operating conditions: gas temperature 20℃, gas pressure 0.4MPa);

[0064] Figure 3 Verify the parameter curves for the gas differential pressure y (%) and output gas density x (%) input to the gas calculation regulator (operating conditions: gas temperature 40℃, gas pressure 0.4MPa);

[0065] Figure 4 Verify the parameter curves for the gas differential pressure y (%) and output gas density x (%) input to the gas calculation regulator (operating conditions: gas temperature 60℃, gas pressure 0.4MPa);

[0066] In the diagram: ① Valve assembly; ② Purity transmitter; ③ Differential pressure transmitter; ④ Pressure transmitter; ⑤ Resistance temperature detector (RTD); ⑥ Pressure transmitter (for calibration); ⑦ Pressure gauge; ⑧ Differential pressure gauge; ⑨ Safety barrier; ⑩ Differential pressure / pressure / temperature converter. Distributor; Purity calculation regulator; DCS system; Sealing oil pan; dynamo. Detailed Implementation

[0067] The basic principle of the density method for measuring the purity of gases or gas mixtures is that the densities of two mixed gases are different from the individual densities of the gases at the same temperature and pressure. If the density of one gas is known, the content of the other gas in the mixed gas can be calculated by measuring the density of the mixed gas.

[0068] The hydrogen charging and purging process for the generator is as follows: First, CO2 is used to replace air inside the generator. A sample is taken from the top of the generator. When the CO2 purity reaches 95% or higher, the CO2 charging is stopped. Then, H2 is used to replace the CO2 inside the generator. A sample is taken from the bottom of the generator. When the hydrogen purity inside the generator exceeds 96%, the hydrogen charging process is complete. The hydrogen purging process is the reverse of the charging process: first, CO2 replaces H2, and then air replaces CO2. Therefore, in addition to measuring the generator hydrogen purity during unit operation, the purity of H2 and CO2 in the mixed gas must be measured during both the charging and purging processes.

[0069] The density method for measuring gas purity in hydrogen-cooled generators uses a lightly loaded, constant-speed fan (referred to as a purity transmitter) to create a differential pressure in the flowing (mixed) gas. The differential pressure value is mainly determined by the (mixed) gas density, the speed of the purity transmitter, and its geometric dimensions. Since the transmitter speed and geometric dimensions remain constant, the (mixed) gas density can be calculated from the differential pressure value. After temperature and pressure corrections, the gas concentration (i.e., purity) can then be deduced.

[0070] 1. Derivation of formulas for calculating the purity of (mixed) gases under various operating conditions

[0071] (1) Formula for calculating the density of a gas

[0072] After temperature and pressure correction and compensation, the formula for calculating gas density under standard operating conditions is as follows:

[0073] ρ (t,P) =ρ (t0,P0) ×(P / P0)×(T0+t0) / (T0+t)............(1)

[0074] in,

[0075] ρ (t,P) :kg / Nm 3 The density of a gas at a temperature of t (°C) and a pressure of P (MPa);

[0076] ρ (t0,P0) :kg / Nm 3 The density of a gas at a temperature of t0 (°C) and a pressure of P0 (MPa);

[0077] t: °C, measured temperature;

[0078] P: MPa, measured pressure, P = Pg + P0;

[0079] Pg: MPa, working pressure of gas;

[0080] P0: MPa, pressure under standard operating conditions, P0 = 0.1013 MPa;

[0081] t0: °C, under standard operating conditions, t0 = 40 °C;

[0082] T0: K, absolute temperature, T0 = 273.15 K.

[0083] (2) The density ratio of the mixed gas to the air under standard operating conditions is ρ0 (%), calculated as follows:

[0084] ρ0(%)=(rGAS×GAS(%)+rAir[100-GAS(%)]) / 100rAir×100…(2)

[0085] in,

[0086] ρ0(%): %, the density ratio of the mixed gas under standard operating conditions;

[0087] rGAS: kg / Nm 3 The density of H2 or CO2 in the gas mixture, where the density of H2 is rH2 = 0.0899 kg / Nm³. 3 The density of CO2 is rCO2 = 1.977 kg / Nm³. 3 ;

[0088] rAir: kg / Nm 3 Air density, rAir = 1.2928 kg / Nm³ 3 ;

[0089] GAS (%): Gas purity (H2 purity or CO2 purity).

[0090] Based on formulas (1) and (2) above, the basic formulas for calculating the purity of H2 and CO2 in the mixed gas are derived as follows:

[0091] H2(%)=(100-ρ0(%)) / 93.04×100.............(3)

[0092] CO2(%)=(ρ0(%)-100) / 52.92×100.............(4)

[0093] To meet the purity measurement and calculation requirements under various operating conditions of the unit, a unified formula is needed to calculate the purity of H2 and CO2. Combining the individual purity calculation formulas for H2 and CO2 mentioned above, and based on the purity calculation regulator characteristic verification parameter table, typical parameters are selected for comprehensive derivation and adjustment of formula coefficients, resulting in the unified gas purity calculation formula:

[0094] ((100-DP / a×P0 / (P+P0)×(t+T0) / (t0+T0)) / 93.04×100)×b / 107.3+c

[0095] in,

[0096] DP: MPa, differential pressure measured by a purity transmitter;

[0097] t: °C, measured temperature;

[0098] P: MPa, measured pressure;

[0099] P0: MPa, pressure under standard operating conditions, P0 = 0.1013 MPa;

[0100] t0: °C, under standard operating conditions, t0 = 40 °C;

[0101] T0: K, absolute temperature, T0 = 273.15 K;

[0102] a, b, c: Correction coefficients (constants).

[0103] Practical verification has shown that this formula is applicable to monitoring hydrogen purity under unit operating conditions, as well as monitoring the purity of H2 and CO2 in mixed gases under generator hydrogen charging and purging conditions, and the accuracy of the calculation results meets the requirements.

[0104] 2. Improvement of the gas purity detection system

[0105] The original generator gas (H2, CO2) purity detection system directly connects the differential pressure, temperature, pressure and other detection signals of the gas or mixed gas through the safety barrier and converter to the purity calculation and controller. The controller calculates the gas purity and generates alarm results for each detection parameter exceeding the limit and sensor failure, and outputs them to the field indicator and the unit's DCS system (i.e., distributed control system).

[0106] As mentioned earlier, this detection system has many drawbacks, therefore targeted improvements have been made. The main improvements include adding a signal distributor to process parameters such as differential pressure, temperature, and pressure of the gas or gas mixture, sending one path to the purity regulator and the other to the unit's DCS control system; and using the derived (mixed) gas purity calculation formula applicable to various operating conditions, implementing logical functions within the DCS system using various algorithms to perform purity calculations and realize the display, alarm, and historical data storage functions for each signal.

[0107] The invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Taking a coal-fired generator unit that uses co-fired gas in a steel enterprise's self-owned power plant as an example, this unit serves as the generator unit for the steel enterprise's self-owned power plant and plays a role in balancing the by-products of blast furnace gas and coke oven gas. The unit is designed with an installed capacity of 350MW and uses a DCS control system to monitor the main equipment of the generator unit, such as the boiler, turbine, generator, and denitrification system. The generator is a horizontal, all-hydrogen internally cooled, salient-pole brushless excitation turbine generator. The purity of hydrogen / carbon dioxide is measured using the density method. A purity signal transmitter is configured to detect the differential pressure of the generator gas. Pressure and temperature detection elements are used to measure the generator gas pressure and temperature. Each detection signal is connected to a hydrogen purity calculation and regulator after passing through a safety barrier and a converter. The regulator internally realizes gas purity calculation and abnormal alarm functions, and the output results are sent to the unit's DCS system and the purity indicator on the local sealing oil pan for gas purity display and abnormal alarm.

[0108] The hydrogen purity calculation regulator, imported in 1998, is an internal black box, and the specific formula for purity calculation is unknown. During unit shutdown calibration, the purity signal output by the regulator is measured and confirmed by changing the input signal parameters. However, due to years of use, the regulator's performance has deteriorated, resulting in large fluctuations in some parameter values ​​during calibration. Furthermore, during actual generator hydrogen charging and discharging processes, the CO2 detection value only reaches 80%, failing to rise with the increasing amount of CO2 being charged. Since the original regulator of the same type has been discontinued, and the regulator itself is a black box, this poses a significant risk to actual production. There is an urgent need to solve the black box problem and improve the existing purity detection system.

[0109] The core technology of this invention mainly includes the derivation method of the gas purity calculation formula under various operating conditions of the generator set, and the improvement of the existing gas purity detection system. Specifically:

[0110] 1. Derivation of formulas for calculating the purity of (mixed) gases under various operating conditions

[0111] (1) Based on the basic principle of density measurement method and the relationship between density and purity of mixed gas, the basic calculation formulas (3) and (4) for the purity of H2 and CO2 of mixed gas are derived.

[0112] ρ (t,P) =ρ (t0,P0) ×(P / P0)×(T0+t0) / (T0+t).............(1)

[0113] ρ0(%)=(rGAS×GAS(%)+rAir[100-GAS(%)]) / 100rAir×100.....(2)

[0114] in,

[0115] ρ (t,P) :kg / Nm 3 The density of a gas at a temperature of t (°C) and a pressure of P (MPa);

[0116] ρ (t0,P0) :kg / Nm 3 The density of a gas at a temperature of t0 (°C) and a pressure of P0 (MPa);

[0117] t: °C, measured temperature;

[0118] P: MPa, measured pressure, P = Pg + P0;

[0119] Pg: MPa, working pressure of gas;

[0120] P0: MPa, pressure under standard operating conditions, P0 = 0.1013 MPa;

[0121] t0: °C, under standard operating conditions, t0 = 40 °C;

[0122] T0: K, absolute temperature, T0 = 273.15 K;

[0123] ρ0(%): %, the density ratio of the mixed gas under standard operating conditions;

[0124] rGAS: kg / Nm 3 The density of H2 or CO2 in the gas mixture, where the density of H2 is rH2 = 0.0899 kg / Nm³. 3 The density of CO2 is rCO2 = 1.977 kg / Nm³. 3 ;

[0125] rAir: kg / Nm 3 Air density, rAir = 1.2928 kg / Nm³ 3 ;

[0126] GAS (%): Gas purity (H2 purity or CO2 purity);

[0127] From formulas (1) and (2), the following formulas (3) and (4) are derived:

[0128] H2(%)=(100-ρ0(%)) / 93.04×100............(3)

[0129] CO2(%)=(ρ0(%)-100) / 52.92×100.............(4)

[0130] in,

[0131] ρ0(%): %, the density ratio of the mixed gas under standard operating conditions;

[0132] GAS (%): %, gas purity (H2 purity or CO2 purity).

[0133] (2) Refer to Tables 1 to 3 and Figures 2 to 4 Based on the purity calculation regulator calibration parameter records, typical parameter values ​​are selected, and the slope of the curve relating gas purity (%) to gas differential pressure measurement (%) is calculated using a univariate linear regression method. The slope of this curve is a value between 0.4 and 0.6, which is a reference value.

[0134] Table 1: Gas purity verification parameters (temperature 20℃, pressure 0.4MPa)

[0135]

[0136] Table 2: Gas purity verification parameters (temperature 40℃, pressure 0.4MPa)

[0137]

[0138] Table 3: Gas purity verification parameters (temperature 60℃, pressure 0.4MPa)

[0139]

[0140] in, Figures 2 to 4 In the figure, the horizontal axis x represents the gas density value (%), and the vertical axis y represents the gas differential pressure measurement value (%); the gas differential pressure range is 0 to 1.6 kPa; the hydrogen pressure range is 0 to 0.6 MPa; and the hydrogen temperature range is 0 to 100 °C.

[0141] (3) Substituting formulas (1) and (2) into formulas (3) and (4) respectively, the following formulas are obtained for calculating the purity of H2 and CO2 in the mixed gas:

[0142] H2(%)=((100-DP / a×P0 / (P+P0)×(t+T0) / (t0+T0)) / 93.04)×100…(5)

[0143] CO2(%)=((DP / a×P0 / (P+P0)×(t+T0) / (t0+T0)-100) / 93.04)×100…(6)

[0144] in:

[0145] DP: MPa, differential pressure measured by a purity transmitter;

[0146] GAS (%): Gas purity (H2 purity or CO2 purity).

[0147] a: Correction factor (constant).

[0148] (4) Based on the characteristic that the density of the mixed gas and the output current are linearly related, and combined with the regulator calibration parameter records, (5) and (6) are deduced and integrated into a unified gas purity calculation formula (7), where a is the slope of the curve between the gas purity (%) and the gas differential pressure measurement value (%) calculated by the univariate linear regression method, with a reference value range between 0.4 and 0.6, and b and c are constants calculated by the parameter matching method, with reference value ranges between 60 and 70 and 30 and 40, respectively.

[0149] GAS(%)=(((100-DP / a×P0 / (P+P0)×(t+T0) / (t0+T0)) / 93.04)×100)×b / 107.3+c............(7)

[0150] in:

[0151] DP: MPa, differential pressure measured by a purity transmitter;

[0152] GAS (%): Gas purity (H2 purity or CO2 purity);

[0153] a: Correction factor, ranging from 0.4 to 0.6;

[0154] b: Correction factor, ranging from 60 to 70;

[0155] c: Correction factor, ranging from 30 to 40.

[0156] Practical verification shows that this formula is applicable to monitoring hydrogen purity under unit operating conditions, as well as monitoring the purity of H2 and CO2 in mixed gas under generator hydrogen charging and purging conditions, and the accuracy of the calculation results meets the requirements.

[0157] 2. Improvement of the gas purity detection system

[0158] Reference Figure 1 As shown, in the original generator gas purity detection system, the generator interior... The differential pressure (generated by the purity transmitter ②), temperature, and pressure of the (mixed) gas are detected by instruments such as differential pressure transmitter ③, pressure transmitter ④, resistance temperature detector ⑤, and pressure transmitter (for correction) ⑥, respectively. After passing through safety barrier ⑨ and differential pressure / pressure / temperature converter ⑩ (four independent corresponding converters in the figure), they are connected to the hydrogen / carbon dioxide purity calculation and control unit. The regulator calculates the gas purity, generates alarm results for excessive detection parameters and sensor malfunctions, and outputs them to the field sealing oil pan. Indicator gauges and unit DCS system The system provides display and alarm functions. The diagram also shows valve assembly ①, pressure gauge ⑦, differential pressure gauge ⑧, and generator. Components and their positional connections.

[0159] This gas purity detection system has several drawbacks, therefore targeted improvements have been made. The main improvement measures include:

[0160] (1) Add a signal distributor to transmit parameters such as differential pressure, temperature, and pressure of the (mixed) gas through the distributor. After processing by the (signal distributor), one path is sent to the purity calculation regulator. Another power supply unit DCS control system (Distributed Control System), see additional section. Figure 1 Content within the red box;

[0161] (2) Using the above-derived formula (7) for calculating the purity of (mixed) gas applicable to various operating conditions, the original purity calculation regulator... Due to performance degradation and inability to meet on-site requirements, other types of regulators are used as replacements. Furthermore, the gas purity calculation and related alarm functions can be realized by reprogramming the new regulator according to the derived formula (7). In addition, various algorithms are used to program logic functions in the DCS control system to perform purity calculations and realize the display, alarm, and historical data storage functions of various signals. This effectively avoids the problem of gas purity not being monitored normally due to regulator failure, and provides a means to analyze the causes of abnormal purity measurement and trace historical data.

[0162] After adopting this technology, actual verification showed that the derived gas purity calculation formula (7) is applicable to the monitoring of H2 purity under unit operating conditions, as well as the monitoring of H2 and CO2 purity of mixed gas under generator hydrogen charging and hydrogen purging conditions. The accuracy of the calculation results meets the requirements. After the gas purity detection system was improved, in addition to the regulator realizing the calculation function, the DCS control system also realized the gas purity calculation and various alarm functions. Moreover, all signal parameters can be conveniently queried on the DCS control system to retrieve historical data, and the entire process of gas purity calculation can be displayed intuitively. When the purity detection signal is abnormal, the cause can be quickly found and historical data can be traced, which effectively solves the problems of the original detection system.

[0163] This invention provides a method and system for detecting and calculating the purity of hydrogen / carbon dioxide in hydrogen-cooled generators. Based on density measurement methods and fundamental principles, combined with calibration data recording, and through univariate linear regression and parameter matching methods, a unified formula for calculating the purity of mixed gases is derived. Addressing various shortcomings of existing gas purity detection loops, this invention employs logic programmed with various algorithms within a DCS control system to perform purity calculations and display, alarm, and historical data storage functions for various signals. This effectively solves problems such as the lack of transparency in existing purity calculation methods, the inability to save historical data for relevant detection signals, and the difficulty in tracing and finding the cause of inaccurate purity detection signals. Furthermore, it addresses issues such as the loss of hydrogen purity monitoring due to regulator performance degradation or malfunction, posing significant production risks. This method has been implemented in the No. 3 generator unit of a steel company's self-owned power plant, and practical verification has shown good results. It has significant potential for widespread application to similar generator units.

Claims

1. A method for detecting the purity of hydrogen and carbon dioxide in a hydrogen-cooled generator, characterized by, During the detection, the purity of hydrogen and / or carbon dioxide is calculated by the following formula: GAS(%) = (((100-DP / a x P0 / (P+P0) x (t+T0) / (t0+T0)) / 93.04) x 100) x b / 107.3+c Wherein: GAS(%) : gas purity of H2 and / or CO2; DP: MPa, differential pressure measured by purity transmitter; t: ℃, measurement temperature; P: MPa, measurement pressure, P= Pg+P0; Pg: MPa, working pressure of gas; P0: MPa, pressure under standard working condition, P0=0.1013 MPa; t0: ℃, under standard working condition, t0=40 ℃; T0: K, absolute temperature, T0=273.15 K; a: correction coefficient, range 0.4-0.6; b: correction coefficient, range 60-70; c: correction coefficient, range 30-40.

2. A detection system for hydrogen and carbon dioxide purity of a hydrogen-cooled generator, detection signals of differential pressure, temperature and pressure of the gas inside the generator are respectively transmitted through a differential pressure transmitter, a pressure transmitter, a thermal resistance and a correction pressure transmitter, and then respectively input into a purity calculation regulator through a differential pressure converter, a first pressure converter, a temperature converter and a second pressure converter, the purity calculation regulator is provided with a first gas purity calculation module and an alarm module which can convert internal calculation into purity; the differential pressure converter, the first pressure converter and the temperature converter are connected with the first gas purity calculation module, and the second pressure converter is connected with the alarm module; characterized in that, the detection system further comprises a DCS system arranged in parallel with the purity calculation regulator, the differential pressure converter, the first pressure converter, the temperature converter and the second pressure converter are respectively connected with a distributor, corresponding signals are respectively processed through the corresponding distributors, and then one way is sent to the purity calculation regulator and the other way is sent to the DCS system; the DCS system is embedded with a second gas purity calculation module for calculating gas purity. The first gas purity calculation module calculates the purity of hydrogen and / or carbon dioxide by the following formula:

3. The hydrogen and carbon dioxide purity detection system of claim 2, wherein, GAS(%) = (((100-DP / a x P0 / (P+P0) x (t+T0) / (t0+T0)) / 93.04) x 100) x b / 107.3+c Wherein: GAS(%) : gas purity of H2 and / or CO2; DP: MPa, differential pressure measured by purity transmitter; t: ℃, measurement temperature; P: MPa, measurement pressure, P= Pg+P0; Pg: MPa, working pressure of gas; P0: MPa, pressure under standard working condition, P0=0.1013 MPa; t0: ℃, under standard working condition, t0=40 ℃; T0: K, absolute temperature, T0=273.15 K; a: correction coefficient, range 0.4-0.6; b: correction coefficient, range 60-70; c: correction coefficient, range 30-40. The second gas purity calculation module calculates the purity of hydrogen and / or carbon dioxide by the following formula:

4. The hydrogen and carbon dioxide purity detection system of claim 2, wherein, ​ GAS(%) = (((100-DP / a x P0 / (P+P0) x (t+T0) / (t0+T0)) / 93.04) x 100) x b / 107.3 + c Wherein: GAS(%): gas purity of H2 and / or CO2; DP: MPa, differential pressure measured by purity transmitter; t: ℃, measuring temperature; P: MPa, measuring pressure, P= Pg+P0; Pg: MPa, working pressure of gas; P0: MPa, pressure under standard working condition, P0=0.1013 MPa; t0: ℃, under standard working condition, t0=40 ℃; T0: K, absolute temperature, T0=273.15 K; a: correction coefficient, range 0.4~0.6; b: correction coefficient, range 60~70; c: correction coefficient, range 30~40.

5. The hydrogen and carbon dioxide purity detection system for hydrogen cooled generators as claimed in claim 2 wherein, Differential pressure of gas inside the generator is formed by purity transmitter.

6. The hydrogen and carbon dioxide purity detection system of claim 2, wherein, Alarm module of the purity calculation regulator is connected with the DCS system.

7. The hydrogen and carbon dioxide purity detection system of claim 2, wherein, The DCS system is provided with historical data query module.

8. The hydrogen and carbon dioxide purity detection system of claim 2, wherein, The DCS system is further provided with display terminal which can display gas purity calculation process.

9. The hydrogen and carbon dioxide purity detection system of claim 2, wherein, Detection parameter over-limit and sensor fault alarm result signal generated by the purity calculation regulator are output to the indicator terminal of the field seal oil pan.

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