Correction method for headspace purge error in automatic batch fermentation device

Abstract

The invention relates to the technical field of fermentation experiment measurement, and discloses a method for correcting a headspace purge error in an automatic batch fermentation device. The method comprises: obtaining preparation parameters; constructing a number-residual ratio function relationship between the number of metering times and the headspace purge gas residual ratio based on the preparation parameters, and determining the headspace purge gas residual ratio at each metering based on the number-residual ratio function relationship; constructing a number-error function relationship between a gas production error value and the number of metering times according to the headspace purge gas residual ratio at two adjacent metering times, and determining the gas production error value at each metering based on the number-error function relationship; calculating a true gas production based on the gas production error value, and determining the cumulative gas production of the automatic batch fermentation device through the true gas production; the invention adopts an algorithm and a correction mechanism to reduce or eliminate the error introduced by the purge gas, effectively reduce the influence of the purge gas on the experimental results, and improve the accuracy and reliability of the experiment.

Description

Technical Field

[0001] The invention relates to the technical field of fermentation experiment determination, and in particular to a method for correcting headspace purge errors in an automatic batch fermentation device. Background Art

[0002] With the rapid development of renewable energy technology, the application of anaerobic digestion technology to produce clean energy by treating organic waste such as organic garbage, livestock manure, straw crops, etc. is becoming more and more widespread. Since different anaerobic organisms have different abilities to degrade organic waste, it is necessary to conduct degradability tests on anaerobic organisms to determine their ability to degrade organic waste, so as to select suitable anaerobic organisms for the degradation of organic waste.

[0003] In order to conduct anaerobic biodegradability determination, measures must be taken to purge inert gas before starting to create an anaerobic environment. However, the purge gas will fill the headspace of the fermentation unit, affecting the subsequent measurement of the metered gas production. At present, in the existing degradability determination, it is assumed that all the purge gas in the headspace of the fermentation unit has been completely pushed out, and the metered gas production produced by the biochemical reaction of anaerobic organisms is corrected by directly subtracting the purge gas in the headspace of the fermentation unit. However, when the fermentation unit produces too little gas, the purge gas in the headspace of the fermentation unit has not been completely pushed out. It can be seen that the existing metered gas measurement method not only has a large deviation from the actual gas production, but also cannot be corrected and monitored in real time. Summary of the invention

[0004] The invention provides a method for correcting headspace purge error in an automatic batch fermentation device, so as to solve the problem that the existing metered gas determination method not only has a large deviation from the actual gas production, but also cannot be corrected and monitored in real time.

[0005] In order to achieve the above object, the present invention is implemented by the following technical solutions:

[0006] The present invention provides a method for correcting a headspace purge error in an automatic batch fermentation device, which is applied to an automatic batch fermentation device. The automatic batch fermentation device includes a fermentation unit, an alkali solution absorption unit, a metering unit and a main control unit. The correction method includes:

[0007] Biochemical reactions occur inside the fermentation unit to produce mixed gases;

[0008] The alkali liquid absorption unit absorbs the acidic components in the mixed gas discharged from the fermentation unit and discharges the remaining gas into the metering unit;

[0009] The metering unit measures the volume of the remaining gas after being absorbed by the alkali solution absorption unit, and generates a pulse signal based on the metering result and sends it to the main control unit;

[0010] The main control unit obtains the preparation parameters of the automatic batch fermentation device for biochemical reaction based on the pulse signal, wherein the preparation parameters include: the total volume of the fermentation unit, the effective working volume of the fermentation unit, the resolution of the metering unit, and the gas concentration of the purge gas;

[0011] The main control unit constructs a frequency-residual ratio functional relationship between the number of metering times and the residual ratio of the headspace purge gas based on the preparation parameters, and determines the residual ratio of the headspace purge gas during each metering based on the frequency-residual ratio functional relationship;

[0012] The main control unit constructs a number-error function relationship between the gas production error value and the number of metering times according to the headspace purge gas residual ratio during two adjacent meterings, and determines the gas production error value during each metering based on the number-error function relationship;

[0013] The main control unit calculates the actual gas production based on the gas production error value, and determines the cumulative gas production of the automatic batch fermentation device through the actual gas production.

[0014] Optionally, a frequency-residual ratio functional relationship between the metering frequency and the headspace purge gas residual ratio is constructed based on the preparation parameters, including:

[0015] According to the relationship between the single metering gas flow rate and the headspace volume, the calculation formula of the headspace purge gas residual ratio during the first metering is constructed, and the calculation formula satisfies the following relationship:

[0016] (1-1);

[0017] In the formula, represents the total volume of the fermentation unit, Indicates the effective working volume of the fermentation unit, represents the headspace volume of the fermentation unit, Indicates the measurement unit resolution, Indicates the residual ratio of the headspace purge gas at the first measurement. It indicates the residual ratio of headspace purge gas after the purge is completed, and is 1;

[0018] The calculation formula of the headspace purge gas residual ratio at the i-th measurement is determined according to the calculation formula of the headspace purge gas residual ratio at the first measurement, and the calculation formula satisfies the following relationship:

[0019] (2-1);

[0020] In the formula, represents the total volume of the fermentation unit, Indicates the effective working volume of the fermentation unit, represents the headspace volume of the fermentation unit, Indicates the measurement unit resolution, represents the residual ratio of headspace purge gas at the i-th measurement, It represents the residual ratio of headspace purge gas at the i-1th measurement, i represents the i-th measurement of the metering unit;

[0021] By combining equations (1-1) and (2-1), we can obtain the frequency-residual ratio function relationship between the metering times and the residual ratio of the headspace purge gas. The frequency-residual function relationship satisfies the following relationship:

[0022] (3-1);

[0023] In the formula, represents the total volume of the fermentation unit, Indicates the effective working volume of the fermentation unit, represents the headspace volume of the fermentation unit, Indicates the measurement unit resolution, It represents the residual ratio of headspace purge gas at the i-th measurement, and i represents the i-th measurement of the metering unit.

[0024] Optionally, a number-error function relationship between the gas production error value and the number of metering times is constructed according to the headspace purge gas residual ratio during two adjacent meterings, including:

[0025] Based on the headspace purge gas residual ratio, the headspace volume of the fermentation unit and the gas concentration of the purge gas during two adjacent measurements, a functional relationship for calculating the gas production error value is constructed, and the functional relationship satisfies the following relationship:

[0026] (4-1);

[0027] In the formula, represents the gas production error value of the i-th measurement, Indicates the concentration of the metered gas in the gas produced by the biochemical reaction. Indicates the concentration of gas in the purge gas that can be absorbed by the alkali solution. represents the residual ratio of headspace purge gas at the i-th measurement, It indicates the residual ratio of headspace purge gas at the i-1th measurement, represents the total volume of the fermentation unit, Indicates the effective working volume of the fermentation unit;

[0028] Combining equations (3-1) and (4-1), we get the error value of gas production and the number of metering times - the error function relationship, which satisfies the following relationship:

[0029] (5-1);

[0030] In the formula, represents the gas production error value of the i-th measurement, Indicates the concentration of the metered gas in the gas produced by the biochemical reaction. Indicates the concentration of gas in the purge gas that can be absorbed by the alkali solution. represents the total volume of the fermentation unit, Indicates the effective working volume of the fermentation unit, represents the headspace volume of the fermentation unit, It represents the resolution of the measurement unit, and i represents the i-th measurement of the measurement unit.

[0031] Optionally, the actual gas production is calculated based on the gas production error value, including:

[0032] The calculation formula for the actual gas production of the metering gas in the biochemical reaction output gas at each metering is determined based on the gas production error value and the metering unit resolution, and the actual gas production at each metering is calculated using this calculation formula, and the calculation formula satisfies the following relationship:

[0033] (6-1);

[0034] In the formula, Indicates the actual gas production of the metered gas in the biochemical reaction output gas. represents the gas production error value of the i-th measurement, Indicates the measurement unit resolution.

[0035] Optionally, the cumulative gas production of the automated batch fermentation device is determined by the actual gas production, including:

[0036] The calculation formula for the cumulative gas production of the metered gas in the biochemical reaction output gas at the last i-time metering is determined according to the actual gas production, and the cumulative gas production of the last i-time metering of the automatic batch fermentation device is determined by the calculation formula, and the calculation formula satisfies the following relationship:

[0037] (7-1);

[0038] In the formula, Indicates the actual cumulative gas production of the previous i measurements, Indicates the actual cumulative gas production of the previous i-1 measurements, Indicates the actual gas production of the metered gas in the biochemical reaction output gas.

[0039] Optionally, before obtaining the preparation parameters of the automatic batch fermentation device for biochemical reaction, the calibration method further includes:

[0040] A purge gas is introduced into the fermentation unit in the automatic batch fermentation device to replace all the air in the fermentation unit with the purge gas.

[0041] Beneficial effects:

[0042] The method for correcting the headspace purge error in an automatic batch fermentation device provided by the present invention is to obtain the preparation parameters of the automatic batch fermentation device when used for biochemical reactions; and to construct a number-residual ratio functional relationship between the number of metering times and the residual ratio of the headspace purge gas based on the preparation parameters; and then to construct a number-error functional relationship between the gas production error value and the number of metering times according to the residual ratio of the headspace purge gas during two adjacent meterings; thereby calculating the actual gas production according to the gas production error value, and finally determining the cumulative gas production of the automatic batch fermentation device according to the actual gas production; determining the actual gas production by the above method can greatly reduce the interference of the residual gas in the headspace on the calculation, thereby reducing the error in the measurement of the actual gas production.

[0043] It is worth noting that this method establishes an accurate mathematical model to simulate the process in which the purge gas remaining in the headspace of the fermentation unit is gradually pushed out during the gas production stage of the fermentation unit, quantifies the actual cumulative metered gas production in the process, corrects the measurement error caused by the purge gas staying in the headspace of the fermentation unit in the biochemical reaction, and monitors the actual cumulative gas production in real time. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 Flow chart of a method for correcting headspace purge error in an automatic batch fermentation device according to a preferred embodiment 1 of the present invention;

[0045] Figure 2 Schematic diagram of the gas production headspace error principle of the preferred embodiment 1 of the present invention, wherein (a) is a schematic diagram after gas purging before gas production, (b) is a schematic diagram of the first metering after gas production, (c) is a schematic diagram of the second metering after gas production, and (d) is a schematic diagram of the i-th metering after gas production;

[0046] Figure 3 4 is a logic block diagram of a method for correcting headspace purge error in an automatic batch fermentation device according to a preferred embodiment 1 of the present invention;

[0047] Figure 4 This is a graph showing the error of the fermentation gas production headspace in the preferred embodiment 2 of the present invention;

[0048] Figure 5 This is a cumulative gas production curve diagram after the headspace error compensation of the fermentation gas production in the preferred embodiment 2 of the present invention;

[0049] Figure 6 Flow chart of a method for correcting headspace purge error in an automatic batch fermentation device according to a preferred embodiment 2 of the present invention;

[0050] Figure 7 It is a structural schematic diagram of an automatic batch fermentation device according to a preferred embodiment of the present invention;

[0051] In the figure, 1. fermentation unit; 2. alkali solution absorption unit; 3. metering unit; 4. gas hose; 5. main control unit. DETAILED DESCRIPTION

[0052] The technical solution of the present invention is described clearly and completely below. Obviously, the described embodiments are only a 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 creative work are within the scope of protection of the present invention.

[0053] Unless otherwise defined, the technical terms or scientific terms used in the present invention shall have the usual meanings understood by persons with ordinary skills in the field to which the present invention belongs. The words "first", "second" and similar words used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, words such as "one" or "one" do not indicate quantity restrictions, but indicate the existence of at least one. Words such as "connect" or "connected" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the object being described changes, the relative positional relationship also changes accordingly.

[0054] Example 1

[0055] The embodiment of the present application provides a method for correcting the headspace purge error in an automatic batch fermentation device, which is applied to an automatic batch fermentation device, the automatic batch fermentation device comprising a fermentation unit 1, an alkali solution absorption unit 2, a metering unit 3 and a main control unit 5, and aims to further improve the accuracy of the device in gas metering. The correction method is based on the gas production of the fermentation unit, and performs conversion correction after the metering unit and the main control unit obtain data. The correction method is as follows Figure 1 As shown, including:

[0056] A biochemical reaction occurs inside the fermentation unit 1, producing a mixed gas including methane, carbon dioxide, and hydrogen sulfide;

[0057] The alkaline solution absorption unit 2 absorbs the acidic components in the mixed gas discharged from the fermentation unit 1, and converts the harmful acidic gas into harmless salts or other compounds through a chemical reaction between the alkaline solution inside and the acidic components (such as sulfur dioxide, carbon dioxide, hydrogen sulfide, etc.) in the gas, and discharges the remaining gas into the metering unit 3;

[0058] The metering unit 3 measures the volume of the remaining gas after being absorbed by the alkali solution absorption unit 2, and generates a pulse signal based on the metering result and sends it to the main control unit 5;

[0059] The main control unit 5 obtains the preparation parameters of the automatic batch fermentation device for biochemical reaction based on the pulse signal, wherein the preparation parameters include: the total volume of the fermentation unit, the effective working volume of the fermentation unit, the resolution of the metering unit and the gas concentration of the purge gas;

[0060] The main control unit 5 constructs a frequency-residual ratio functional relationship between the number of metering times and the residual ratio of the head space purge gas based on the preparation parameters, and determines the residual ratio of the head space purge gas at each metering based on the frequency-residual ratio functional relationship;

[0061] The main control unit 5 constructs a number-error function relationship between the gas production error value and the number of measurement times according to the head space purge gas residual ratio during two adjacent measurements, and determines the gas production error value during each measurement based on the number-error function relationship;

[0062] The main control unit 5 calculates the actual gas production based on the gas production error value, and determines the cumulative gas production of the automatic batch fermentation device through the actual gas production.

[0063] In the above embodiment, the preparation parameters of the automatic batch fermentation device for biochemical reaction are obtained; and based on the preparation parameters, a function relationship between the number of metering times and the number-residual ratio of the headspace purge gas residual ratio is constructed; and then a function relationship between the gas production error value and the number of metering times is constructed according to the headspace purge gas residual ratio during two adjacent metering times; thereby, the actual gas production is calculated according to the gas production error value, and the cumulative gas production of the automatic batch fermentation device can be finally determined according to the actual gas production; determining the actual gas production by the above method can greatly reduce the interference of the headspace residual gas on the calculation, thereby reducing the error in the measurement of the actual gas production.

[0064] The general process of gas production error is as follows Figure 2 As shown, Figure 2 Taking a single N2 purge as an example, before the biochemical reaction starts, N2 is used for purge, and N2 stays in the headspace of fermentation unit 1, such as Figure 2 As shown in (a), as the fermentation unit 1 produces gas, the gas produced by the biochemical reaction is mixed with N2 and pushed out of the fermentation unit 1, passes through the alkali solution absorption unit 2 and is then measured by the metering unit 3. This part of the measured N2 is pushed out by the gas produced by the biochemical reaction, but it has a different gas component from the gas produced and cannot be absorbed when passing through the alkali solution absorption unit 2, thus causing a methane gas production error, as shown in Figure 1. Figure 2 Middle (b) - Figure 2 As shown in (d).

[0065] First, it is necessary to carry out the purging preparation work, that is, to introduce the purging gas into the fermentation unit 1, the alkali solution absorption unit 2 and the metering unit 3, and to discharge all the air in the device from the automatic batch fermentation device.

[0066] In this embodiment, methane CH4 is specifically used as the metering gas produced by the biochemical reaction during the biochemical reaction;

[0067] The implementation flow chart of this embodiment is as follows Figure 3 As shown, after the purging preparation work is completed, the main control unit 5 calculates the real cumulative metering gas production according to the input original data, and calls the real cumulative gas production output according to different monitoring requirements. The specific steps are as follows:

[0068] Step 1: Biochemical reaction preparation, the process is as follows:

[0069] Step 1.1: The fermentation unit 1 is filled with the test sample, and then the fermentation unit 1, the alkali solution absorption unit 2 and the metering unit 3 are checked for air tightness and purged with inert gas. The purging gas mainly includes N2, CH4, CO2 and their mixed gases.

[0070] Step 1.2: Determine the total volume V of the fermentation unit 1, the effective working volume VS of the fermentation unit, and the resolution of the metering unit in step 1.1 , the CO2 concentration of the purge gas is , input main control unit 5.

[0071] Step 2: Fermentation unit 1 starts to produce gas, and the methane concentration of the produced gas is For the convenience of calculation, it is assumed that the headspace gas of fermentation unit 1 is mixed evenly, and metering unit 3 starts metering. When metering occurs, a pulse signal is generated. The biomethane potential test is a continuous gas production process.

[0072] Step 3: The main control unit 5 receives the pulse signal, calls the original input data of step 1.2, and constructs the headspace purge gas residual ratio at the i-th measurement As a function of the metering times i, the headspace purge gas residual ratio is the ratio of the purge gas to the headspace of the fermentation unit 1. The specific calculation process is as follows:

[0073] Step 3.1: Based on the relationship between the single measurement gas flow rate and the headspace volume, calculate the headspace purge gas residual ratio during the first measurement. , the specific functional relationship is as follows:

[0074] ;

[0075] In the formula, represents the total volume of the fermentation unit, Indicates the effective working volume of the fermentation unit, represents the headspace volume of the fermentation unit, Indicates the measurement unit resolution, Indicates the residual ratio of the headspace purge gas at the first measurement. It indicates the residual ratio of headspace purge gas after the purge is completed, and is 1.

[0076] Step 3.2: According to the headspace purge gas residual ratio calculated in step 3.1 at the first measurement , calculate the headspace purge gas residual ratio during the second measurement , and so on, according to the residual ratio of the headspace purge gas at the i-1th measurement , calculate the headspace purge gas residual ratio at the i-th measurement , the specific functional relationship is as follows:

[0077] ;

[0078] In the formula, represents the total volume of the fermentation unit, Indicates the effective working volume of the fermentation unit, represents the headspace volume of the fermentation unit, Indicates the measurement unit resolution, represents the residual ratio of headspace purge gas at the i-th measurement, It represents the residual ratio of the headspace purge gas at the i-1th measurement, and i represents the i-th measurement of the metering unit.

[0079] Step 3.3: According to the formula in step 3.2, the headspace purge gas residual ratio can be calculated, and then the headspace purge gas residual ratio at the i-th measurement can be derived. The functional relationship with the measurement times i is as follows:

[0080] ;

[0081] In the formula, represents the total volume of the fermentation unit, Indicates the effective working volume of the fermentation unit, represents the headspace volume of the fermentation unit, Indicates the measurement unit resolution, It represents the residual ratio of headspace purge gas at the i-th measurement, i represents the i-th measurement of the measurement unit, and the volume unit is mL.

[0082] Step 4: Construct the methane gas production error value of the i-th measurement based on the headspace purge gas residual ratio between two adjacent measurements The functional relationship with the measurement number i is as follows:

[0083] Step 4.1: The error in methane production is caused by the purge gas staying in the headspace of fermentation unit 1. Therefore, the headspace purge gas residual ratio obtained in step 3.2 during two adjacent measurements is multiplied by the headspace volume to obtain the purge gas pushed out from fermentation unit 1 in this measurement. The purge gas is pushed out by the biochemical reaction output gas, one part of which is pushed out by CH4 in the output gas, and the other part is pushed out by CO2 in the output gas. After the pushed out purge gas passes through the alkali solution absorption unit 2, the CO2 part of it is absorbed, and the non-CO2 part is measured by the metering unit 3. Because the ratio of CO2 and non-CO2 in the purge gas and the biochemical reaction output gas is different, the methane production is overestimated or underestimated. Therefore, a formula is established to calculate the error value of methane production in the i-th measurement. , the specific functional relationship is as follows:

[0084] ;

[0085] Where: It represents the error value of methane production measured for the i-th time. Positive value is overestimation and negative value is underestimation. represents the total volume of the fermentation unit, Indicates the effective working volume of the fermentation unit, Indicates the headspace volume of the fermentation unit, and the volume unit is mL. Indicates the CH4 concentration in the gas produced by the biochemical reaction. Indicates the CO2 concentration in the purge gas, and the concentration unit is volume percentage.

[0086] Step 4.2: Combine the formulas of step 3.3 and step 4.1 to obtain the error value of methane production for the i-th measurement The functional relationship with the measurement times i is as follows:

[0087] ;

[0088] Where: It represents the error value of methane production measured for the i-th time. Positive value is overestimation and negative value is underestimation. represents the total volume of the fermentation unit, Indicates the effective working volume of the fermentation unit, represents the headspace volume of the fermentation unit, Indicates the resolution of the measurement unit. The volume unit is mL. Indicates the CH4 concentration in the gas produced by the biochemical reaction. It indicates the CO2 concentration in the purge gas. The concentration unit is volume percentage. i indicates the i-th measurement of the metering unit.

[0089] Step 5: The error value of methane production for the i-th measurement calculated according to step 4.2 , calculate the actual methane production of the ith measurement , the specific formula is as follows:

[0090] ;

[0091] Where: represents the actual methane production measured for the i-th time, It represents the error value of methane production measured for the i-th time. Positive value is overestimation and negative value is underestimation. Indicates the measurement unit resolution, and the volume unit is mL.

[0092] Step 6: Calculate the actual cumulative methane production based on the previous i-1 measurements and the actual methane production measured for the i-th time , calculate the actual cumulative methane production of the previous i measurements , the specific formula is as follows:

[0093] ;

[0094] Where: Indicates the actual cumulative methane production of the previous i measurements, Indicates the actual cumulative methane production in the previous i-1 measurements. It represents the actual methane production in the ith measurement, and the volume unit is mL.

[0095] Step 7: When the metering unit 3 performs a measurement, a pulse signal is generated, and the main control unit 5 records the number of pulse signals, which is the number of flow meter measurement times i.

[0096] ① Mid-term monitoring: The main control unit 5 directly calls the actual cumulative methane production of the previous i measurements in step 6 according to the current flow meter measurement number i Output.

[0097] ② Gas production ends: The main control unit 5 directly calls the actual cumulative methane production of the previous i measurements in step 6 according to the flow meter measurement times i at the end. Output.

[0098] In the above embodiment, the step of using methane CH4 as the metering gas produced by the biochemical reaction during the biochemical reaction is only an example and not a limitation. Any metering gas that can be measured by this method is included in this embodiment.

[0099] Example 2

[0100] In this embodiment, methane CH4 is specifically used as the metering gas produced by the biochemical reaction during the biochemical reaction, and different purge gases are used to perform the biomethane potential test to apply the content of the present invention.

[0101] The purge gases used were 100% N2, 80% N2 + 20% CO2, 100% CO2, and 20% N2 + 80% CO2. The total volume V of the fermentation unit 1 was 600 mL, and the effective working volume of the fermentation unit was The resolution of the metering unit is 400mL. is 1.8mL, and the concentration of purge gas CO2 is See Table 1 for specific values:

[0102] Table 1 CO2 concentration C of different purge gases CO2-F

[0103]

[0104] In order to form an anaerobic environment, gas purging is a necessary step in the biomethane potential test. However, in engineering practice, the purge gas will stay in the headspace of the fermentation unit 1, causing methane production errors. Calculating the methane production error caused by the purge gas is the key to achieving accurate measurement of methane potential.

[0105] In this example, it is assumed that the methane concentration of the produced gas is is 60%, because the standard biogas methane concentration is 60%. This value can be adjusted according to different materials. The error value of methane production in the i-th measurement is calculated. Functional relationship with the number of measurements i.

[0106] ;

[0107] Where: Indicates the error value of methane production in the i-th measurement, with positive values ​​being overestimated and negative values ​​being underestimated. The total volume of the fermentation unit The effective working volume of the fermentation unit is 600mL The headspace volume of the fermentation unit is 400 mL The metering unit resolution is 200mL. is 1.8mL, the volume unit is mL, the CH4 concentration in the biochemical reaction output gas is 60%, It indicates the CO2 concentration in the purge gas. The concentration unit is volume percentage. i indicates the i-th measurement of the metering unit.

[0108] Select the methane gas production error value of each measurement calculated by the first 200 measurement units 3 ,like Figure 4 As shown, If it is positive, it is an overestimation. If it is a negative value, it is an underestimate. As the gas production gradually progresses, the measurement times i gradually increase, and the error value of single measurement of methane gas production is This process is consistent with the process in which the purge gas is gradually pushed out of the fermentation unit 1, and the purge gas is gradually reduced in each measurement.

[0109] According to the calculated methane production error value for the i-th measurement , calculate the actual cumulative methane production of the previous i measurements , the calculation formula is as follows:

[0110] ;

[0111] Where: represents the actual methane production measured for the i-th time, Indicates the error value of methane production measured for the i-th time. Positive values ​​are overestimated, negative values ​​are underestimated. The resolution of the metering unit is The volume is 1.8mL, and the volume unit is mL.

[0112] ;

[0113] Where: Indicates the actual cumulative methane production of the previous i measurements, Indicates the actual cumulative methane production in the previous i-1 measurements. It represents the actual methane production in the ith measurement, and the volume unit is mL.

[0114] Select the actual cumulative methane production calculated by the first 200 times of metering unit 3, such as Figure 5 As shown, with the increase of the number of measurements, the corrected curve and the uncorrected curve gradually become parallel. This is because with the increase of the number of measurements, the original gas in the headspace gradually decreases, and the error value of methane production in each measurement gradually decreases and gradually approaches zero.

[0115] The correction method in this embodiment is as follows: Figure 6 As shown, the fermentation unit 1 starts to produce gas, the metering unit 3 generates a metering transmission pulse signal to the main control unit 5, and the main control unit 5 calculates the headspace gas residual ratio, and then calculates the actual methane production for each metering. When the gas production ends, the actual cumulative methane production is output.

[0116] In the above embodiment, the step of using methane CH4 as the metering gas produced by the biochemical reaction during the biochemical reaction is only an example and not a limitation. Any metering gas that can be measured by this method is included in this embodiment.

[0117] like Figure 7 As shown, the embodiment of the present application also provides an automatic batch fermentation device, including a fermentation unit 1, an alkali solution absorption unit 2, a metering unit 3 and a main control unit 5;

[0118] The fermentation unit 1 is used to carry out the biochemical reaction of anaerobic organisms and discharge the mixed gas produced by the biochemical reaction;

[0119] The alkali solution absorption unit 2 is used to absorb the acidic components in the mixed gas discharged from the fermentation unit 1;

[0120] The metering unit 3 is used to measure the flow rate of the gas after being absorbed by the alkali solution absorption unit 2, and is also used to generate a pulse signal from the metering result and send it to the main control unit 5;

[0121] The main control unit 5 is used to receive the preparation parameters of the automatic batch fermentation device obtained according to the pulse signal, wherein the preparation parameters include: the total volume of the fermentation unit in the automatic batch fermentation device, the effective working volume of the fermentation unit, the resolution of the metering unit in the automatic batch fermentation device, and the gas concentration of the purge gas;

[0122] The main control unit 5 is also used to construct a frequency-residual ratio functional relationship between the number of metering times and the residual ratio of the head space purge gas based on the preparation parameters, and determine the residual ratio of the head space purge gas at each metering based on the frequency-residual ratio functional relationship;

[0123] The main control unit 5 is also used to construct a number-error function relationship between the gas production error value and the number of measurement times according to the head space purge gas residual ratio during two adjacent measurements, and determine the gas production error value during each measurement based on the number-error function relationship;

[0124] The main control unit 5 is further used to calculate the actual gas production based on the gas production error value, and determine the cumulative gas production of the automatic batch fermentation device through the actual gas production.

[0125] The gas outlet of the fermentation unit 1 is connected to the gas inlet of the alkali solution absorption unit 2 through the gas hose 4 , the gas inlet of the alkali solution absorption unit 2 is connected to the gas inlet of the metering unit 3 through the gas hose 4 , and the metering unit 3 is electrically connected to the main control unit 5 .

[0126] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A method for correcting headspace purge error in an automatic batch fermentation device, applied to an automatic batch fermentation device, the automatic batch fermentation device comprising a fermentation unit (1), an alkali solution absorption unit (2), a metering unit (3) and a main control unit (5), characterized in that: The correction method comprises: A biochemical reaction occurs inside the fermentation unit (1) to produce a mixed gas; The alkali liquid absorption unit (2) absorbs the acidic components in the mixed gas discharged from the fermentation unit (1), and discharges the remaining gas into the metering unit (3); The metering unit (3) measures the volume of the remaining gas after being absorbed by the alkali solution absorption unit (2), and generates a pulse signal based on the metering result and sends it to the main control unit (5); The main control unit (5) obtains preparation parameters of the automatic batch fermentation device for biochemical reaction based on the pulse signal, wherein the preparation parameters include: the total volume of the fermentation unit, the effective working volume of the fermentation unit, the resolution of the metering unit, and the gas concentration of the purge gas; The main control unit (5) constructs a number-residual ratio functional relationship between the number of metering times and the residual ratio of the head space purge gas based on the preparation parameters, and determines the residual ratio of the head space purge gas during each metering based on the number-residual ratio functional relationship; Wherein, the constructing of the number-residual ratio functional relationship between the metering times and the headspace purge gas residual ratio based on the preparation parameters includes: According to the relationship between the single metering gas flow rate and the headspace volume, the calculation formula of the headspace purge gas residual ratio during the first metering is constructed, and the calculation formula satisfies the following relationship: （1-1）； In the formula, represents the total volume of the fermentation unit, Indicates the effective working volume of the fermentation unit, represents the headspace volume of the fermentation unit, Indicates the measurement unit resolution, Indicates the residual ratio of the headspace purge gas at the first measurement. It indicates the residual ratio of headspace purge gas after the purge is completed, and is 1; The calculation formula of the headspace purge gas residual ratio at the i-th measurement is determined according to the calculation formula of the headspace purge gas residual ratio at the first measurement, and the calculation formula satisfies the following relationship: （2-1）； In the formula, represents the total volume of the fermentation unit, Indicates the effective working volume of the fermentation unit, represents the headspace volume of the fermentation unit, Indicates the measurement unit resolution, represents the residual ratio of headspace purge gas at the i-th measurement, It represents the residual ratio of headspace purge gas at the i-1th measurement, i represents the i-th measurement of the metering unit; By combining equations (1-1) and (2-1), we can obtain the frequency-residual ratio function relationship between the metering times and the residual ratio of the headspace purge gas. The frequency-residual function relationship satisfies the following relationship: （3-1）； In the formula, represents the total volume of the fermentation unit, Indicates the effective working volume of the fermentation unit, represents the headspace volume of the fermentation unit, Indicates the measurement unit resolution, It represents the residual ratio of headspace purge gas at the i-th measurement, i represents the i-th measurement of the metering unit; The main control unit (5) constructs a number-error function relationship between a gas production error value and the number of metering times according to the headspace purge gas residual ratios during two adjacent meterings, and determines the gas production error value during each metering based on the number-error function relationship; The main control unit (5) calculates the actual gas production based on the gas production error value, and determines the cumulative gas production of the automatic batch fermentation device through the actual gas production.

2. The method for correcting headspace purge error in an automatic batch fermentation device according to claim 1, characterized in that: The method of constructing a number-error function relationship between a gas production error value and a number of metering times according to the headspace purge gas residual ratio during two adjacent meterings includes: Based on the headspace purge gas residual ratio, the headspace volume of the fermentation unit and the gas concentration of the purge gas during two adjacent measurements, a functional relationship for calculating the gas production error value is constructed, and the functional relationship satisfies the following relationship: （4-1）； In the formula, represents the gas production error value of the i-th measurement, Indicates the concentration of the metered gas in the gas produced by the biochemical reaction. Indicates the concentration of gas in the purge gas that can be absorbed by the alkali solution. represents the residual ratio of headspace purge gas at the i-th measurement, It indicates the residual ratio of headspace purge gas at the i-1th measurement, represents the total volume of the fermentation unit, Indicates the effective working volume of the fermentation unit; By combining equations (3-1) and (4-1), we can obtain the error value of gas production and the number of metering times - the error function relationship, which satisfies the following relationship: （5-1）； In the formula, represents the gas production error value of the i-th measurement, Indicates the concentration of the metered gas in the gas produced by the biochemical reaction. Indicates the concentration of gas in the purge gas that can be absorbed by the alkali solution. represents the total volume of the fermentation unit, Indicates the effective working volume of the fermentation unit, represents the headspace volume of the fermentation unit, It represents the resolution of the measurement unit, and i represents the i-th measurement of the measurement unit.

3. The method for correcting headspace purge error in an automatic batch fermentation device according to claim 1, characterized in that: The calculating the actual gas production amount based on the gas production error value includes: According to the gas production error value and the measurement unit resolution, the calculation formula for the actual gas production of the metering gas in the biochemical reaction output gas at each measurement is determined, and the actual gas production at each measurement is calculated. The calculation formula satisfies the following relationship: （6-1）； In the formula, Indicates the actual gas production of the metered gas in the biochemical reaction output gas. represents the gas production error value of the i-th measurement, Indicates the measurement unit resolution.

4. The method for correcting headspace purge error in an automatic batch fermentation device according to claim 1, characterized in that: The step of determining the cumulative gas production of the automatic batch fermentation device by using the actual gas production comprises: The calculation formula for the cumulative gas production of the metered gas in the biochemical reaction output gas during the previous i-time metering is determined according to the actual gas production, and the cumulative gas production of the previous i-time metering of the automatic batch fermentation device is determined by the calculation formula, and the calculation formula satisfies the following relationship: （7-1）； In the formula, Indicates the actual cumulative gas production of the previous i measurements, Indicates the actual cumulative gas production of the previous i-1 measurements, Indicates the actual gas production of the metered gas in the biochemical reaction output gas.

5. The method for correcting headspace purge error in an automatic batch fermentation device according to claim 1, characterized in that: Before obtaining the preparation parameters of the automatic batch fermentation device for biochemical reaction, the calibration method further includes: A purge gas is introduced into the fermentation unit in the automatic batch fermentation device to replace all the air in the fermentation unit with the purge gas.

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