CN-122016945-A - Biofuel oxidative deterioration assessment method and system based on conductivity characteristic analysis

CN122016945ACN 122016945 ACN122016945 ACN 122016945ACN-122016945-A

Abstract

The invention relates to the technical field of biofuel monitoring, in particular to a biofuel oxidative deterioration assessment method and system based on conductivity characteristic analysis. The method comprises the steps of collecting real-time conductivity and temperature data of biofuel in a storage tank, filtering, calculating absolute values of differences between actual increment and theoretical increment caused by temperature change only based on preset temperature compensation coefficients to obtain non-thermal change rate residual errors, constructing a sliding window to calculate residual error standard deviation, carrying out logarithmic amplification by combining current conductivity to obtain an oxidation microscopic instability index, constructing a time integration window to accumulate the index to obtain dynamic activity, carrying out weighted summation by combining the total amount of static products relative to an initial reference value, and judging deterioration if the comprehensive oxidation deterioration degree exceeds a threshold value. The scheme of the invention can effectively peel off the ambient temperature interference, sensitively capture the early oxidation signal and realize high-precision real-time early warning.

Inventors

ZHANG ZHENGUO
ZHANG ZHENHUI
ZHANG ZHENWEI
ZHANG GUOQING
FAN JIANGYAN
YE PENG

Assignees

洛阳恒玖生物能源有限公司
河南省君恒实业集团生物科技有限公司

Dates

Publication Date: 20260512
Application Date: 20260413

Claims (10)

1. The biofuel oxidative deterioration assessment method based on the conductivity characteristic analysis is characterized by comprising the following steps of: Collecting real-time conductivity data and real-time temperature data of the biofuel in the storage tank, and performing filtering treatment on the real-time conductivity data and the real-time temperature data to obtain a conductivity value and a temperature value at the current sampling moment; based on a preset temperature compensation coefficient, calculating an actual increment of a conductivity value at the current sampling moment relative to the last sampling moment, calculating a theoretical conductivity increment caused by temperature change only, and calculating an absolute value of a difference value between the actual increment and the theoretical conductivity increment to obtain a non-thermally induced change rate residual error; Constructing a sliding time window, calculating standard deviations of a plurality of non-thermal change rate residuals in the sliding time window, and carrying out logarithmic amplification by combining the conductivity value at the current sampling moment to obtain an oxidized microscopic instability index; Constructing a time integration window, carrying out accumulation summation on oxidation microscopic instability indexes in the time integration window to obtain a dynamic activity accumulation value, calculating a difference value of a conductivity value at the current sampling time relative to an initial reference value to obtain a static product total amount, carrying out weighted summation on the dynamic activity accumulation value and the static product total amount to obtain a comprehensive oxidation deterioration degree, and judging that the biological fuel is subjected to oxidation deterioration if the comprehensive oxidation deterioration degree exceeds a preset threshold value.
2. The method for assessing the oxidative deterioration of a biofuel based on conductivity characterization of claim 1, wherein the collecting real-time conductivity data and real-time temperature data of the biofuel in the tank comprises: synchronously acquiring an original data stream at a preset sampling frequency through conductivity sensors and temperature sensors arranged at the bottom and the middle of the storage tank; And carrying out moving average filtering processing on the original data stream to eliminate high-frequency electromagnetic interference, and obtaining the conductivity value and the temperature value of the current sampling moment.
3. The method for assessing the oxidative deterioration of a biofuel based on conductivity characterization according to claim 1, wherein the non-thermally induced rate of change residual is expressed as: ; In the formula, Representing the current sampling instant Is a non-thermally induced rate of change residual, And The conductivity values at the current and last sample times are represented respectively, And The temperature values at the current sampling instant and the last sampling instant are respectively represented, Indicating a preset temperature compensation coefficient of the temperature sensor, Representing an absolute value operation.
4. The method for assessing the oxidative deterioration of a biofuel based on conductivity characterization according to claim 3, wherein the process of obtaining the oxidative microscopic instability index comprises the step of calculating the residual mean value: acquiring a plurality of non-thermally induced rate of change residuals within the sliding time window; And calculating the arithmetic average value of all non-thermal change rate residuals in the sliding time window to obtain the residual average value corresponding to the sliding time window.
5. The method for assessing the oxidative deterioration of a biofuel based on conductivity profiles as set forth in claim 4, wherein said oxidative microscopic instability index is expressed as: ; In the formula, Representing the current sampling instant Is characterized by an index of oxidative microscopic instability, Representing the length of the sliding time window, Representing non-thermally induced rate of change residuals within a sliding time window, Representing the corresponding residual mean value of the sliding time window, Representing the conductivity value at the current sampling instant.
6. The method for assessing the oxidative deterioration of a biofuel based on the analysis of conductivity characteristics according to claim 1, wherein the expression of the comprehensive degree of oxidative deterioration is: ; In the formula, Representing the current sampling instant Is characterized by that its comprehensive oxidation deterioration degree, Representing the length of the time integration window, Representing the index of oxidative microscopic instability within the time integration window, The conductivity value representing the current sampling instant, A reference conductivity value representing the initial stage of biofuel in the tank, The dynamic weight coefficient is represented by a coefficient of dynamic weight, Representing thermodynamic weight coefficients.
7. The method for assessing the oxidative deterioration of a biofuel based on conductivity profile as set forth in claim 6, wherein determining that the biofuel is undergoing oxidative deterioration if the integrated degree of oxidative deterioration exceeds a preset threshold comprises: When the comprehensive oxidation-deterioration degree exceeds a first preset threshold value, judging that the biofuel is in an induction period ending stage, increasing the sampling frequency and prompting manual sampling; when the comprehensive oxidation-deterioration degree exceeds a second preset threshold value, judging that the biofuel is in a rapid oxidation period, and triggering protective measures, wherein the protective measures comprise nitrogen seal protection or circulated cooling; Wherein the second preset threshold is greater than the first preset threshold.
8. The method for evaluating the oxidation deterioration of a biofuel based on the conductivity profile analysis according to claim 3, wherein the temperature compensation coefficient obtaining method comprises the steps of: When the system is operated for the first time or new biofuel is injected, performing reference calibration with the duration being a preset duration; Recording data of conductivity along with temperature change at a stage when the biofuel does not deteriorate; And calculating the unit conductivity change proportion caused by unit temperature change through fitting to obtain the temperature compensation coefficient.
9. The conductivity characterization based biofuel oxidative deterioration assessment method of claim 1, wherein the biofuel comprises fatty acid methyl esters, hydrogenated vegetable oils or sustainable aviation fuels.
10. A biofuel oxidation deterioration evaluation system based on conductivity characterization, comprising: A processor; A memory storing computer instructions for conductivity profile based assessment of biofuel oxidation deterioration, which when executed by the processor, cause the system to perform the conductivity profile based assessment method of biofuel oxidation deterioration as claimed in any one of claims 1 to 9.

Description

Biofuel oxidative deterioration assessment method and system based on conductivity characteristic analysis Technical Field The invention relates to the technical field of biofuel monitoring. More particularly, the invention relates to a biofuel oxidation deterioration assessment method and system based on conductivity profile analysis. Background Because the chemical properties of the biological fuels such as fatty acid methyl ester, hydrogenated vegetable oil, sustainable aviation fuel and the like are relatively active, particularly the biological diesel oil prepared from waste grease is extremely easy to generate autoxidation reaction in the process of storage and transportation. The oxidation process generally comprises an induction period, a rapid oxidation period and a degradation period, wherein the induction period is the most critical period for fuel quality management, and the change of macroscopic physicochemical indexes such as acid value, viscosity and the like is not obvious in the stage of the fuel, while the quality of the oil product is irreversibly and rapidly reduced once the induction period is broken through. In the prior art, the main flow detection method mostly adopts EN14112 standard (namely Rannimat method), however, the method needs to manually sample and carry out off-line heating analysis, so that the operation is complicated, the detection period is long, obvious hysteresis exists, the current state of the oil product in the storage tank cannot be reflected in time by the non-real-time detection mode, and the requirement of modern industry on storage and transportation safety real-time monitoring is difficult to be met. In order to realize real-time monitoring of the oil state and solve the hysteresis problem existing in the off-line detection mode, the industry begins to try to evaluate by using an on-line conductivity sensor, and aims to reflect the oxidation state of the biofuel by detecting the conductivity change of the biofuel on line. However, the conductivity of biofuels is extremely low, and the parameter is extremely sensitive to temperature, and in practical applications, the diurnal fluctuations in ambient temperature can lead to substantial physical shifts in conductivity, which are often more than an order of magnitude greater than the weak chemical signal produced by early oxidation. Because the signal-to-noise ratio is extremely low, the existing on-line monitoring means are extremely easy to report by mistake or not, so that the oxidation state of the oil product is difficult to evaluate accurately under complex environmental conditions. Disclosure of Invention The invention aims to provide a biofuel oxidative deterioration assessment method and system based on conductivity characteristic analysis, which are used for solving the problem that the online monitoring means in the prior art is extremely easy to report by mistake or not, and therefore, the invention provides the scheme in the following two aspects. In a first aspect, the invention provides a method for assessing oxidative deterioration of a biofuel based on conductivity profile analysis, comprising: The method comprises the steps of collecting real-time conductivity data and real-time temperature data of biofuel in a storage tank, carrying out filtering treatment on the real-time conductivity data and the real-time temperature data to obtain a conductivity value and a temperature value at a current sampling time, calculating an actual increment of the conductivity value at the current sampling time relative to a last sampling time based on a preset temperature compensation coefficient, calculating a theoretical conductivity increment caused by temperature change only, calculating an absolute value of a difference value between the actual increment and the theoretical conductivity increment to obtain a non-thermal change rate residual, constructing a sliding time window, calculating standard deviations of a plurality of non-thermal change rate residual in the sliding time window, carrying out logarithmic amplification by combining the conductivity value at the current sampling time to obtain an oxidation microscopic instability index, constructing a time integration window, carrying out accumulated summation on the oxidation microscopic instability index in the time integration window to obtain a dynamic activity accumulated value, calculating a static activity accumulated value corresponding to a difference value at the current sampling time, carrying out weighted summation on the dynamic activity accumulated value and the static product total value to obtain a comprehensive oxidation degree, and judging that the biofuel is oxidized if the comprehensive oxidation degradation degree exceeds a preset threshold value. Therefore, by constructing a non-thermal change rate residual error and utilizing differential and compensation logic, the physical conductivity drift caused by the environmental temperatu