Carbon dioxide automatic absorbing and weighing device and method for measuring biological decomposition capability

Abstract

The invention provides an automatic carbon dioxide absorbing and weighing device and method for measuring biological decomposition capacity. The device comprises an absorption tower, a multi-stage carbon dioxide absorbing system, an infrared analyzer measuring system, a weighing balance and an automatic control system. The absorption tower is provided with a gas inlet and a tail gas outlet, the biodegradation reaction container is connected with the gas inlet, and gas to be detected is conveyed to the gas inlet; the multi-stage carbon dioxide absorption system is arranged in the absorption tower, is positioned between the gas inlet and the tail gas outlet and is used for absorbing carbon dioxide in the input gas to be detected; the infrared analyzer is used for detecting the content of residual carbon dioxide in the tail gas; the detection end of the weighing balance is connected with the absorption tower to detect the weight change of the absorption tower before and after carbon dioxide is absorbed; and the automatic control system is connected with the multi-stage carbon dioxide absorption system, the infrared analyzer measurement system and the weighing balance. The carbon dioxide cumulant automatic measurement is realized, and the carbon dioxide cumulant measurement precision is improved.

Description

Technical Field

[0001] This patent relates to the field of material biodegradability determination, and in particular provides a carbon dioxide automatic absorption weighing device and method for determining biodegradability. Background Art

[0002] Biodegradation refers to the process in which materials are degraded by microorganisms under natural conditions or specific conditions (such as controlled composting conditions), and eventually completely decomposed to produce carbon dioxide, methane, water, mineralized inorganic salts of the elements they contain, and new biomass. GB / T 19277.1 / ISO 14855-1 "Determination of the final aerobic biodegradability of materials under controlled composting conditions by measuring the amount of carbon dioxide released Part 1: General method" standard specifies the method for determining biodegradability. The standard specifies a determination method: the final aerobic biodegradability of the material is determined by measuring the amount of carbon dioxide it emits under controlled composting conditions as an organic compound. The ratio of the actual amount of carbon dioxide produced by the test material in the test to the theoretical amount of carbon dioxide that the material can produce is the biodegradation rate. The test period of this method shall not exceed 6 months. The test material shall contain at least 20g of organic carbon (equivalent to 73.3g of carbon dioxide). During the test, the amount of carbon dioxide produced by the test container (3 parallel samples), blank container (3 blank samples) and reference container (3 reference samples) shall be continuously monitored and measured regularly. The cumulative amount of carbon dioxide produced shall be measured to calculate the biodegradation rate. During the test, the carbon dioxide in the exhaust gas of each test container shall be measured regularly by direct measurement method (gas chromatograph, total organic carbon analyzer, infrared analyzer) or cumulative measurement method (measuring the absorbed carbon dioxide after absorption with alkali solution) as the cumulative amount of carbon dioxide released. If the direct measurement method is used, the measurement shall be conducted at least twice a day during the biodegradation stage, with an interval of about 6h, and at least once a day during the stable stage. If the cumulative measurement method is used, the measurement shall be conducted once a day during the biodegradation stage and twice a week during the stable stage. The validity requirements of the test results are: the biodegradation rate of the reference material exceeds 70% after 45 days; the relative deviation of the biodegradation rate of each test container does not exceed 20% at the end of the test; within the first 10 days of cultivation, the blank container inoculum produces 50-150 mg carbon dioxide / g volatile solids.

[0003] At present, the cumulative measurement method of measuring carbon dioxide by biodegradability test instruments on the market adopts the balance weighing method and acid-base titration method after absorption by alkaline solution absorption bottle, and the direct measurement method mainly adopts the infrared analyzer method. However, there are many problems in the existing biodegradability test for measuring carbon dioxide:

[0004] Cumulative measurement method, that is, using three alkali solution absorption bottles to chemically absorb carbon dioxide three times, and then measure it by manually operating the balance weighing method or acid-base titration method. The current defects of this method are: first, the carbon dioxide absorption is incomplete, which affects the biodegradation test results and even causes the test failure; 2. The alkali solution in the absorption bottle needs to be replaced many times, and weighing or acid-base titration requires manual operation, which makes it difficult to realize the automation of the biodegradation test; secondly, the loss of water directly affects the measurement results of carbon dioxide. Usually, the absorption rate of carbon dioxide by one alkali solution absorption does not exceed 80%. After three absorptions, at least 0.8% of carbon dioxide is not absorbed, resulting in low measurement results. Experiments have shown that in a 7-day test cycle, the cumulative amount of carbon dioxide has a deviation of 5% due to factors such as water loss and residual carbon dioxide in the exhaust gas. Since this method has low measurement accuracy and cannot be automated, it is often not used in biodegradability tests.

[0005] The infrared analyzer direct measurement method usually uses infrared sensors and flow meters to directly measure the carbon dioxide generated by biological decomposition. The infrared analyzer method has high test sensitivity and good accuracy when detecting low-concentration gases, but when measuring high concentrations, there is usually a problem of exceeding the equipment range, so that some of the data exceeding the range cannot be retained, resulting in low measurement results and a significant decrease in accuracy. The general data of carbon dioxide produced by the decomposition of nutrient-demanding organisms is between 500ppm and 2300ppm. In order to make the reading within the range of measurement, a carbon dioxide sensor with a range of 5000ppm is required. Under normal circumstances, the error value of the carbon dioxide sensor or equipment measurement method is generally 1% of the range, so the error of the sensor is 50ppm; at the same time, the minimum detection concentration is generally 1% of the range. After the experiment enters the final stable stage, the measurement data of carbon dioxide produced by the decomposition of nutrient-demanding organisms is around 500ppm. Considering the above two factors, a 10% error, that is, a 5ppm error, will be introduced when measuring 50ppm. Summary of the invention

[0006] Based on this, the present invention provides a carbon dioxide automatic absorption weighing device and method for measuring biodegradability, so as to realize the automatic measurement of the accumulated amount of carbon dioxide and improve the measurement accuracy of the accumulated amount of carbon dioxide.

[0007] In order to achieve the above-mentioned object, in the first aspect, the present invention provides a carbon dioxide automatic absorption weighing device for measuring biodegradability, comprising an absorption tower, a multi-stage carbon dioxide absorption system, an infrared analyzer measuring system, a weighing balance and an automatic control system. The absorption tower is provided with a gas inlet and a tail gas outlet, the biodegradation reaction container is connected to the gas inlet, and the gas to be detected is delivered to the gas inlet; the multi-stage carbon dioxide absorption system is arranged in the absorption tower and located between the gas inlet and the tail gas outlet, and absorbs the carbon dioxide in the input gas to be detected; the infrared analyzer measuring system is arranged at the tail gas outlet, and detects the residual carbon dioxide content in the tail gas; the weighing balance detection end is connected to the absorption tower, and detects the weight change of the absorption tower before and after the carbon dioxide is absorbed; the automatic control system is connected to the multi-stage carbon dioxide absorption system, the infrared analyzer measuring system and the weighing balance.

[0008] Furthermore, the multi-stage carbon dioxide absorption system includes an alkali solution collection absorption tank, a secondary packing tower and a leaching alkali solution storage tank; the alkali solution collection absorption tank is arranged at the lower part of the absorption tower to collect and store alkali solution; the secondary packing tower is provided with at least two layers of corrugated packing, and each layer is provided with an alkali solution distributor, a packing pressure plate, a polypropylene corrugated packing, a packing support plate and an alkali solution collector from top to bottom; the leaching alkali solution storage tank is arranged at the upper part of the absorption tower.

[0009] Furthermore, two semicircular parts are arranged on the upper part of the absorption tower: a dehydration pipe is arranged on the lower part of the left semicircle, and an alkali absorption pipe is arranged on the upper part. The gas absorbed by the packing tower enters the dehydration pipe for dehydration, and the dehydrated gas enters the alkali absorption pipe, and water and residual carbon dioxide are removed through the dehydration pipe and the alkali absorption pipe; a leaching alkali solution storage tank is arranged on the right semicircle, and the leaching alkali solution storage tank is connected with the alkali solution flowmeter and the injection alkali solution storage tank through a hose, and alkali solution is quantitatively added to the injection alkali solution storage tank to adjust the alkali solution concentration of the leaching alkali solution storage tank.

[0010] Furthermore, the absorption tower is also provided with an air pressure balance system, and the alkali solution in the elution alkali solution storage tank is quantitatively added to the packing tower by a flow meter. The elution alkali solution storage tank is connected to the alkali solution collection absorption tank through an air pipe and a gas valve control to ensure air pressure balance during gas absorption.

[0011] Furthermore, the absorption tower is also provided with an alkali solution lifting circulation system. The elution alkali solution storage tank is connected with the alkali solution collection absorption tank through the alkali solution lifting pipe and the alkali solution valve control. The alkali solution in the alkali solution collection absorption tank is automatically pressurized and lifted to the elution alkali solution storage tank through the gas pressurization of the alkali solution collection absorption tank.

[0012] During the implementation process, the absorption tower body is made of polyethylene material, and the air inlet, air outlet, alkali solution addition port and alkali solution discharge port of the absorption tower are connected by silicone hoses. The support and fixation of the absorption tower are provided with a fixed base at the bottom and a fixed frame at the top. The fixed base and the fixed frame support and fix the absorption tower through support balls;

[0013] During the implementation process, an electrically liftable weighing scale is arranged on the fixed platform at the bottom of the absorption tower. When weighing, the lifting platform rises and the absorption tower is automatically weighed by the weighing scale. The weighing control software calculates the carbon dioxide absorption amount according to the weight. When not weighing, the lifting platform descends and the absorption tower is supported by the fixed platform and the fixed frame to protect the scale.

[0014] In order to achieve the above object, in a second aspect, a carbon dioxide automatic absorption weighing method for determining biodegradability is provided, characterized in that the carbon dioxide absorption process comprises:

[0015] The gas from the biodegradation reaction container enters the alkali liquid collection pool. After the alkali liquid in the alkali liquid collection pool absorbs carbon dioxide, the gas rises and enters the packed absorption tower. The alkali liquid is automatically adjusted by the elution alkali liquid flow valve to be distributed to the absorption tower packing. The gas and alkali liquid are countercurrently exchanged in the packed tower to absorb carbon dioxide.

[0016] During the absorption of carbon dioxide in the absorption tower, the sprayed alkali liquid flows into the alkali liquid collection tank; when the alkali liquid flowing from the alkali liquid spray storage tank to the alkali liquid collection tank reaches the maximum capacity, the flow meter at the tail gas outlet closes the outlet gas, and the air pressure balance pipe valve and the alkali liquid elution flow valve are closed. When the pressurized gas enters the alkali liquid collection tank, the pressure in the collection tank increases, and the alkali liquid rises through the alkali liquid lifting pipe and enters the elution alkali liquid storage tank, realizing the automatic lifting circulation of the alkali liquid.

[0017] Furthermore, the gas flow range of the absorption tower is set to be consistent with the measurement range of the biodegradation reaction container and is adjusted by the gas control flowmeter of the biodegradation reaction container, and the alkali solution lifting amount and speed are adjusted by the air intake flow of the air inlet.

[0018] Furthermore, the flow rate of the leaching alkali solution is controlled and regulated according to the gas flow rate and the carbon dioxide concentration in the gas. According to the carbon dioxide absorption amount and the gas flow change measured by automatic weighing, the flow rate of the leaching alkali solution is automatically adjusted to achieve the best absorption state of the absorption tower.

[0019] Compared with the prior art, the technical advantages of the provided automatic carbon dioxide absorption weighing device and method for determining biodegradability are as follows:

[0020] First, the carbon dioxide produced by the biodegradation reaction is dehydrated and then passed into an automatic weighing absorption tower. The mass of carbon dioxide absorbed by alkali is automatically weighed online through an alkali solution absorption tower and a weighing balance. The cumulative amount of carbon dioxide is determined by automatic weighing, and the mass of carbon dioxide in the gas after alkali absorption is calculated, thereby achieving accurate and automatic measurement of the total accumulated mass of carbon dioxide. The accuracy and degree of automation of carbon dioxide measurement by weighing method are improved.

[0021] Secondly, the carbon dioxide concentration and gas flow after alkali absorption are automatically measured by infrared analyzer and flowmeter. The infrared analyzer is used to monitor the residual carbon dioxide in the exhaust gas after absorption to avoid incomplete carbon dioxide absorption affecting the measurement results. A dehydration pipe is installed in the absorption tower to prevent the loss of water in the absorption liquid from affecting the weighing measurement results. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0023] Figure 1 It is a cumulative schematic diagram of the carbon dioxide automatic absorption weighing device provided;

[0024] Description of the accompanying drawings:

[0025] 1-fixed base; 2-weighing balance; 3-lifting platform; 4-support ball; 5-gas inlet; 6-air pressure balance pipe; 7-alkali solution lifting pipe; 8-alkali solution collection absorption tank; 9-filling support plate; 10-polypropylene corrugated filler; 11-absorption tower; 12-filling pressure plate; 13-alkali solution distributor; 14-elution alkali solution storage tank; 15-dehydration pipe; 16-alkali absorption pipe; 17-injection alkali solution storage tank; 18-infrared analyzer; 19-gas flowmeter; 20-elution alkali solution flowmeter; 21-injection alkali solution flowmeter; 22-air pressure balance control valve; 23-alkali solution lifting control valve; 24-alkali solution discharge valve; 25-fixed frame; 26-exhaust gas outlet. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. 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.

[0027] Since there is no method or device for automatically measuring the cumulative amount of carbon dioxide on the market, the measurement of the cumulative amount of carbon dioxide in biodegradability testing equipment requires manual operation. Since the biodegradability determination takes a long time and the frequency of carbon dioxide measurement is high, manual operation requires frequent opening of the instrument, which not only causes gas leakage when reconnecting the device, resulting in test failure, but also causes large deviations in the carbon dioxide measurement results.

[0028] Although direct carbon dioxide measurement methods such as infrared analyzers can easily automate carbon dioxide measurement, infrared analyzers and other instruments have large measurement deviations for high concentrations of carbon dioxide above 1% (m / m), and there are problems such as instrument baseline drift within the 6-month test period, resulting in large deviations in measurement results (the precision of a single measurement is less than 3%, but the cumulative measurement precision of repeated measurements exceeds 10%). Sometimes the carbon dioxide measurement accuracy exceeds the standard requirements, which can lead to test failure.

[0029] The present invention adopts a measurement method that combines an automatic weighing absorption tower and an infrared analyzer 18 to greatly improve the measurement accuracy of the cumulative amount of carbon dioxide and realize the automation of the cumulative amount of carbon dioxide measurement. This high-precision, high-throughput, automated carbon dioxide measurement method and device can effectively solve the problems of accuracy, efficiency, and automatic detection faced by biodegradability measurement. The mass of carbon dioxide absorbed by alkali is automatically weighed online through an alkali solution absorption tower and a mass sensor, and the carbon dioxide concentration and gas flow after alkali absorption are automatically measured through an infrared analyzer 18 and a flowmeter, and the mass of carbon dioxide in the gas after alkali absorption is calculated, thereby realizing accurate and automatic measurement of the total cumulative mass of carbon dioxide.

[0030] The carbon dioxide produced by the biodegradation reaction is dehydrated and then passed into the automatic weighing absorption tower (see the absorption tower structure for details). Figure 1 ), a dehydration pipe 15 is installed in the absorption tower to prevent the loss of water in the absorption liquid from affecting the weighing measurement result, an infrared analyzer 18 is used to monitor the residual carbon dioxide in the tail gas after absorption to avoid incomplete carbon dioxide absorption affecting the measurement result, and an automatic weighing method is used to measure the cumulative amount of carbon dioxide, thereby obtaining the accuracy and automation of the carbon dioxide measurement by weighing method.

[0031] like Figure 1As shown, the absorption tower structure includes an alkali liquid collection absorption pool 8, a secondary packing absorption tower, a dehydration pipe 15, an alkali absorption pipe 16, an automatic weighing system, an infrared analyzer 18 tail gas monitoring and measuring system, an air pressure balance system, an alkali liquid lifting circulation system, an automatic control system, an absorption tower support and fixing components, etc.; the absorption tower 11 is made of polyethylene material, and the gas inlet 5, the gas outlet, the alkali liquid addition port, and the alkali liquid discharge port of the absorption tower are connected by a silicone hose. The support and fixation of the absorption tower consists of a fixed base 1 at the bottom and a fixed frame 25 at the top. The fixed base 1 and the fixed frame 25 support and fix the absorption tower through support balls 4, which not only ensures the stability of the absorption tower, but also has little effect on automatic weighing. The absorption tower weighing adopts an automatic weighing design with an electrically liftable balance 2 placed on the bottom fixed platform. After the lifting platform 3 rises, the balance 2 can automatically weigh the absorption tower. After the lifting platform 3 descends, the absorption tower is supported and stabilized by the fixed platform and the fixed frame 25. The design of the absorption tower support and fixing and connecting pipelines has an effect on the weighing of no more than 1 mg, which is suitable for the application scenario of automatic weighing with a balance 2 with a sensitivity of 1 mg. The device of the present invention uses a balance 2 with a sensitivity of 10 mg and a weighing capacity of 2 kg to perform weighing, which can meet the requirements of the biodegradability determination experiment.

[0032] During the implementation process, the absorption tower has an inner diameter of 12 cm and a total height of 86 cm. The absorption tower consists of a lower alkali collection absorption tank 8, a middle secondary packing tower, an upper alkali injection storage tank 17, a dehydration pipe 15, and an alkali absorption pipe 16. The lower alkali collection absorption tank 8 has a height of 10 cm, an inner diameter of 12 cm, a volume of 1.13 L, and can collect and store 1 L of alkali. The packing tower in the middle is a two-layer corrugated packing absorption tower, each layer is 36 cm high, and each layer is composed of an alkali distributor 13, a packing pressure plate 12, a packing, a packing support plate 9 and an alkali collector from top to bottom. The packing layer is 30 cm high, and the packing adopts a polypropylene corrugated packing 10. The upper part of the absorption tower consists of two semicircular parts on the left and right, with a height of 14 cm. The lower part of the left semicircle of the upper part of the absorption tower is a dehydration pipe 15 with a length of 6cm, and the upper part is an alkali absorption pipe 16 with a length of 7cm. The gas of the packing tower is dehydrated and residual carbon dioxide through the dehydration pipe 15 and the alkali absorption pipe 16, and then connected to the infrared analyzer 18 through the gas outlet. The upper right semicircle of the absorption tower is a leaching alkali solution storage tank 14, with a volume of 0.79L, which can store 0.7L of alkali solution. The storage tank is connected to the injection alkali solution flowmeter 21 and the injection alkali solution storage tank 17 through a silicone hose, and alkali solution is quantitatively added to adjust the alkali solution concentration of the elution alkali solution storage tank 14. The elution alkali solution of the elution alkali solution storage tank 14 can be quantitatively added to the packing tower by the alkali solution discharge valve 24. The elution alkali solution storage tank 14 is connected to the alkali solution collection absorption tank 8 through the gas line pipe and the gas valve control to ensure the pressure balance during gas absorption. The leaching alkali solution storage tank 14 is connected to the alkali solution collection absorption tank 8 through the alkali solution lifting pipe 7 and the alkali solution lifting control valve 23. The alkali solution in the alkali solution collection absorption tank 8 can be automatically pressurized and lifted to the leaching alkali solution storage tank 14 through the gas pressurization of the alkali solution collection absorption tank 8.

[0033] The gas flow rate input from the biodegradation reaction container to the absorption tower is 0.01-2L / min, and the carbon dioxide concentration in the gas is 10-3000ppm. The gas flow range of the absorption tower is designed to be consistent with the measurement range of the biodegradation reaction container, and is adjusted by the gas control flowmeter of the biodegradation reaction container. The flow range of the elution alkali solution is designed to be 0.01-0.05L / min, and can be automatically controlled and adjusted according to the gas flow rate and the carbon dioxide concentration in the gas. The packing tower is designed according to the packing tower's carbon dioxide absorption rate greater than 90%. The inner diameter of the packing tower is 12cm, the height of the packing layer is 30cm, and the two-layer packing tower uses polypropylene corrugated packing 10. The alkali solution is lifted from the alkali solution collection absorption tank 8 to the elution alkali solution storage tank 141 times. The lifting amount is 0.4-0.7L, which can be automatically pre-set. The alkali solution lifting amount and speed are adjusted by the air intake flow rate of the gas inlet 5. When the flow rate is 2L / min, the alkali solution lifting takes 15s once, which has no effect on the biodegradation test and carbon dioxide determination. When the gas flow rate is 2L / min and the carbon dioxide concentration is 1%, the carbon dioxide absorption rate of the entire absorption tower is greater than 99% after absorption by the alkali solution absorption tank, the packing tower and the alkali absorption tube 16. The outlet tail gas is measured by a 500ppm infrared analyzer 18 to compensate for the residual carbon dioxide after absorption. The weighing balance 2 has a sensitivity of 10mg and a maximum weighing range of 3kg. The measurement deviation of carbon dioxide by the absorption tower is no more than 1%.

[0034] A 28g / L potassium hydroxide solution was prepared with water as the absorption liquid of the carbon dioxide packed tower. At the beginning of the test, 1500mL of 28g / L potassium hydroxide was added as the absorption liquid, 140.7L of the alkali solution storage tank was rinsed, and 80.8L of the alkali solution was collected in the absorption tank. A 560g / L potassium hydroxide solution was prepared as the alkali concentration adjustment liquid. When the potassium hydroxide concentration dropped to 15-20g / L after the absorption liquid absorbed carbon dioxide, 560g / L of potassium hydroxide was automatically added through the automatic liquid adding valve to adjust the potassium hydroxide concentration in the absorption liquid to 28g / L. After the entire test, 100mL of 560g / L potassium hydroxide was required to complete the absorption of 20g of organic carbon. After the entire test, the total volume of the alkali solution was 1600mL.

[0035] The gas and liquid connections of the entire absorption tower are designed and installed with polyethylene, polypropylene and silicone rubber materials, which have the characteristics of good sealing, light weight and strong alkali corrosion resistance. The total weight of the weighing part of the absorption tower is controlled below 2900g (including absorption liquid), and a 3000g / 0.01g weighing balance 2 is selected to meet the maximum weighing weight and carbon dioxide measurement accuracy requirements. The internal structure of the absorption tower is designed with polypropylene corrugated packing 10, and the carbon dioxide absorption rate is improved to more than 99% through the alkali collection pool, secondary packing tower and alkali absorption pipe 16 multi-stage absorption. The experimental data are shown in Table 1.

[0036] Table 1 Data list of 0.2% (m / m) standard carbon dioxide gas after three absorption weighing comparison tests

[0037]

[0038] The addition, discharge, lifting and concentration adjustment of the alkali solution at the bottom of the tower are carried out automatically. The entire test process does not require manual intervention, which avoids the situation where manual replacement of alkali solution affects the test results or even causes the test failure. The dehydration pipe 15 and the alkali solution absorption pipe at the outlet of the packed absorption tower are easy to install and replace. They are replaced once a month and can be replaced in 1 minute. The replacement and installation do not affect the absorption of carbon dioxide. The exhaust gas from the packed tower absorbs moisture and residual carbon dioxide through the dehydration pipe 15 and the alkali solution absorption pipe, reducing the loss of moisture and residual carbon dioxide brought by the gas and causing deviations in weighing measurement.

[0039] As shown in Figure 2, an infrared analyzer 18 is installed at the exhaust gas outlet 26 of the absorption tower. The gas discharged from the absorption tower is monitored and measured by the infrared sensor and the gas flow meter 19. The 1% carbon dioxide content in the exhaust gas of the absorption tower is automatically measured by the infrared analyzer 18 and the flow meter with a deviation of less than 3%, compensating for the loss of unabsorbed carbon dioxide. After experimental verification with standard gas and reference samples, the relative deviation of the measurement accuracy of 20g organic carbon accumulation is no more than 1%, which far exceeds the measurement accuracy and automation of existing similar instruments.

[0040] Table 2 Data list of 5000ppm infrared analyzer testing 500ppm and 2000ppm standard carbon dioxide gas

[0041]

[0042]

[0043] In order to achieve accurate measurement of the cumulative amount of carbon dioxide generated by biological decomposition reaction, the present invention innovatively adopts a combined method of carbon dioxide automatic weighing absorption tower measurement method and infrared analyzer 18 method. That is, firstly, the absorption tower automatically absorbs and weighs, with an absorption rate of 99% and a weighing accuracy of 10mg. The tail gas after absorption is measured by infrared analyzer 18 to compensate for the residual carbon dioxide in the tail gas. The infrared analyzer 18 has a range of 500ppm and a precision of 3%. Even when the carbon dioxide concentration in the reaction gas is the highest value (2300ppm), the carbon dioxide in the tail gas can be accurately measured. The relative deviation of carbon dioxide measurement in the method of the present invention does not exceed 1%, so the deviation of the measurement of the cumulative amount of carbon dioxide generated by the biological decomposition reaction can be reduced to the greatest extent, the validity of the measurement result is improved, and the test failure is avoided. The method of the present invention makes the test result of calculating the sample decomposition rate based on the measurement of the cumulative amount of carbon dioxide and judging its biodegradability accurate and reliable, and the test operation is automated.

[0044] Automatic absorption weighing and lye adjustment process:

[0045] Automatic lifting and adjustment process of alkali solution. Before the test, 700mL of 28g / L potassium hydroxide solution was injected from the alkali solution injection storage tank to the alkali solution spray storage tank, and 800mL was injected into the alkali solution collection tank. Then the alkali solution in the alkali solution injection storage tank was replaced with 560g / L alkali solution as the alkali solution concentration regulating liquid for the absorption process. During the absorption process of carbon dioxide in the absorption tower, the spray alkali solution finally flows into the alkali solution collection tank. When the alkali solution flowing from the alkali solution spray storage tank to the collection tank reaches 650mL, the tail gas outlet 26 flow meter closes the outlet gas, the air pressure balance pipe valve 22 and the alkali solution elution flow valve are closed, and when the pressure gas enters the alkali solution collection tank, the pressure of the collection tank increases, and the alkali solution rises through the alkali solution lifting pipe 7 and enters the alkali solution elution storage tank, realizing the automatic lifting circulation of the alkali solution. The alkali solution circulation time and lifting amount are automatically realized according to the amount calculated by the elution alkali solution flow meter 20 to realize the alkali solution circulation lifting. The alkali solution regulating valve can automatically and quantitatively add 560g / L potassium hydroxide regulating solution to adjust the concentration of the spray alkali solution to 28g / L.

[0046] Carbon dioxide absorption. After the alkali solution is lifted, the carbon dioxide in the gas is absorbed. The flow meter at the tail gas outlet 26 of the absorption tower is opened, the elution alkali solution flow valve and the valve of the air pressure balance pipe 6 are opened, and the valve of the alkali solution lifting pipe 7 is closed. The gas in the biological decomposition reaction container enters the alkali solution collection pool, and the gas after the alkali solution in the collection pool absorbs carbon dioxide rises and enters the packed absorption tower. The alkali solution is automatically adjusted by the elution alkali solution flow valve to be distributed to the absorption tower packing, and the gas and alkali solution are countercurrently exchanged in the packed tower to achieve carbon dioxide absorption. The gas absorbed by the packed tower enters the dehydration pipe 15 for dehydration, and the dehydrated gas enters the alkali absorption pipe 16. According to the carbon dioxide absorption and gas flow changes measured by automatic weighing, the elution alkali solution flow is automatically adjusted to achieve the best absorption state of the absorption tower. The carbon dioxide absorption tower is used to achieve efficient absorption of carbon dioxide, and the absorption tower can achieve a carbon dioxide absorption rate of 99%. The carbon dioxide in the gas can reach a carbon dioxide absorption rate of more than 99.5% after being absorbed by the alkali collection pool, the absorption tower and the alkali absorption tube 16. The absorbed gas is dehydrated by the dehydration tube 15 and the alkali absorption tube 16, and the water loss does not exceed 100 mg. Automatic alkali lifting adjustment and liquid addition are achieved, and the automatic measurement of the cumulative amount of carbon dioxide is achieved through the automatic weighing balance 2. The residual carbon dioxide in the tail gas is monitored and measured by the infrared analyzer 18. During the biodegradability test for 6 consecutive months, the measurement deviation of the cumulative total amount of carbon dioxide generated by the biological decomposition of 20g of organic carbon is no more than 1%.

[0047] Automatic weighing measurement of absorbed carbon dioxide. A mass sensor with a sensitivity of 10 mg is used to automatically weigh the absorption tower online to accurately measure the accumulated amount of absorbed carbon dioxide. Through automatic temperature calibration, prevention of water loss, tail gas monitoring and other measures, the measurement deviation of the accumulated amount of carbon dioxide measured multiple times is no more than 50 mg, and the single measurement deviation is no more than 10 mg during the entire test cycle. The automatic weighing balance 2 is placed on the lifting platform 3 at the bottom of the absorption tower. When weighing, the lifting platform 3 rises and the weighing control software calculates the amount of carbon dioxide absorbed according to the weight. When not weighing, the lifting platform 3 drops to protect the balance 2. The fixed design of the absorption tower is fixed by the absorption tower fixed base 1 and the fixed bracket and the ball between it and the absorption tower, which ensures the stability of the absorption tower and minimizes the impact on the weighing of the absorption tower. The analytical balance 2 with a sensitivity of 0.0001 mg is used for testing. The design has an impact deviation of less than 1 mg on the weighing, which meets the requirements of automatic weighing of the absorption tower and can be applied to other automatic weighing occasions. The specific test is shown in Table 3.

[0048] Table 3 provides a list of data for the automatic weighing absorption tower device and method for detecting 2000ppm standard carbon dioxide gas

[0049] Number of experiments Total absorption rate CO2 sensor readings Total CO2 detection rate 1 80.75％ 403ppm 100.03％ 2 79.97％ 395ppm 99.97％ 3 79.17％ 395ppm 99.99％ 4 80.86％ 396ppm 100.03％ 5 80.86％ 397ppm 100.00％ 6 79.91％ 405ppm 100.00％ 7 79.13％ 404ppm 100.03％ 8 79.52％ 402ppm 100.02％ 9 79.69％ 402ppm 100.01％ 10 79.01％ 401ppm 99.97％ 11 79.28％ 401ppm 100.03％ 12 80.88％ 401ppm 100.01％ 13 79.37％ 397ppm 100.00％ 14 79.58％ 397ppm 100.02％ 15 80.43％ 397ppm 100.01％ 16 78.96％ 395ppm 99.99％ 17 79.01％ 403ppm 100.02％ 18 80.23％ 395ppm 99.98％ 19 80.37％ 404ppm 100.02％ 20 81.01％ 400ppm 99.97％ 21 79.58％ 404ppm 99.99％ 22 80.32％ 396ppm 100.01％ 23 79.78％ 401ppm 100.03％ 24 80.97％ 395ppm 99.99％

[0050] The present invention provides a method for accurately measuring the cumulative amount of carbon dioxide produced by biodegradation capacity determination. Within a 6-month test period, the relative deviation of the detection of the cumulative amount of carbon dioxide produced by the complete degradation of 20g of organic carbon is less than 1%, which is better than the measurement accuracy of the biodegradability tester currently on the market. The present invention provides an automatic carbon dioxide absorption and weighing device for accurately measuring the cumulative amount of carbon dioxide produced by biodegradation capacity determination. The absorption efficiency of the absorption tower for carbon dioxide in air with a carbon dioxide concentration of 1% (V / V) is not less than 99%. The addition, discharge and replacement of alkali solution are fully automatic, avoiding the occurrence of test failures caused by gas leakage due to manual operation.

[0051] An automatic weighing device of the present invention can not only ensure good support and stability of the object to be weighed, but also reduce the impact on the automatic weighing result, and can ensure that the sensitivity of the balance 2 reaches 1 mg. When a balance 2 with a sensitivity of 1 mg is used, the automatic weighing accuracy can reach up to 1 mg. The design of the device can be applied to a variety of automatic weighing occasions, and automatic weighing can be achieved by replacing a balance 2 with different ranges and sensitivities.

[0052] Table 4 Test data list of biodegradability of thin layer chromatography grade cellulose using alkali bottle absorption method, infrared analyzer method and the method of the present invention

[0053]

[0054] As shown in Table 4, the method of the present invention for automatically absorbing and weighing the absorbed tail gas and monitoring and measuring it with an infrared analyzer 18 can achieve a relative deviation of less than 0.1% for one carbon dioxide measurement, which can meet the needs of high-precision measurement of carbon dioxide in various occasions. Compared with the absorption method and sensor method in the prior art, the method and device for measuring the cumulative amount of carbon dioxide provided by the present invention greatly improve the accuracy of the measurement of the cumulative amount of carbon dioxide, improve the validity of the results of the determination of the biodegradability, and avoid the test failure that may be caused by manual operation.

[0055] The cases described are only preferred use cases of the present invention. The present invention is not intended to limit the preferred cases presented above. Different researchers and technicians engaged in related fields can understand that various changes can be made to the present invention in form and detail. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and scope of the present invention shall be included in the protection scope of the present invention.

Claims

1. A carbon dioxide automatic absorption weighing device for determining biodegradability, characterized in that: include: An absorption tower (11) is provided with a gas inlet (5) and an exhaust gas outlet (26); a biodegradation reaction container is connected to the gas inlet (5) to transport the gas to be detected to the gas inlet (5); A multi-stage carbon dioxide absorption system is arranged in the absorption tower (11) and is located between the gas inlet (5) and the tail gas outlet (26), and absorbs carbon dioxide in the input gas to be detected; An infrared analyzer (18) measurement system, comprising an infrared analyzer (18) disposed at the exhaust gas outlet (26) to detect the residual carbon dioxide content in the exhaust gas; A weighing balance (2), the detection end of which is connected to the absorption tower (11), for detecting the weight change of the absorption tower (11) before and after the carbon dioxide is absorbed; and An automatic control system is connected to the multi-stage carbon dioxide absorption system, the infrared analyzer (18) measurement system and the weighing balance (2).

2. The automatic carbon dioxide absorption weighing device for measuring biodegradability according to claim 1, characterized in that: The multi-stage carbon dioxide absorption system comprises an alkali solution collection absorption tank (8), a secondary packing tower and an elution alkali solution storage tank (14); The alkali solution collection absorption tank (8) is arranged at the lower part of the absorption tower (11) to collect and store the alkali solution; The secondary packing tower is provided with at least two layers of corrugated packing, each layer being provided with an alkali liquid distributor (13), a packing pressure plate (12), a polypropylene corrugated packing (10), a packing support plate (9) and an alkali liquid collector from top to bottom; The elution alkali solution storage tank (14) is arranged on the upper part of the absorption tower (11).

3. The automatic carbon dioxide absorption weighing device for measuring biodegradability according to claim 2, characterized in that: The upper part of the absorption tower (11) is provided with two left and right semicircular parts: A dehydration pipe (15) is arranged at the lower part of the left semicircle, and an alkali absorption pipe (16) is arranged at the upper part. The gas absorbed by the packing tower enters the dehydration pipe (15) for dehydration, and the dehydrated gas enters the alkali absorption pipe (16) for removal of residual carbon dioxide. The right semicircle is provided with a leaching alkali solution storage tank (14), which is connected to an alkali solution flow meter and an injection alkali solution storage tank (17) via a hose. Alkali solution is quantitatively added to the injection alkali solution storage tank (17) to adjust the alkali solution concentration of the leaching alkali solution storage tank (14).

4. The automatic carbon dioxide absorption weighing device for measuring biodegradability according to claim 1, characterized in that: The absorption tower (11) is also provided with a gas pressure balance system. The alkali solution in the elution alkali solution storage tank (14) is quantitatively added to the packing tower by a flow meter. The elution alkali solution storage tank (14) is connected to the alkali solution collection absorption tank (8) through a gas pressure balance pipe (6) and a gas valve control to ensure gas pressure balance during gas absorption.

5. The automatic carbon dioxide absorption weighing device for measuring biodegradability according to claim 1, characterized in that: The absorption tower (11) is also provided with an alkali solution lifting circulation system. The leaching alkali solution storage tank (14) is connected to the alkali solution collection absorption tank (8) through the alkali solution lifting pipe (7) and the alkali solution valve control. The alkali solution in the alkali solution collection absorption tank (8) is automatically pressurized and lifted to the leaching alkali solution storage tank (14) by gas pressurization of the alkali solution collection absorption tank (8).

6. The automatic carbon dioxide absorption weighing device for measuring biodegradability according to claim 1, characterized in that: The absorption tower (11) is made of polyethylene material. The air inlet, air outlet, alkali solution addition port and alkali solution discharge port of the absorption tower (11) are connected by silicone hoses. The absorption tower (11) is supported and fixed by a fixed base (1) at the bottom and a fixed frame (25) at the top. The fixed base (1) and the fixed frame (25) support and fix the absorption tower (11) via support balls (4).

7. The automatic carbon dioxide absorption weighing device for measuring biodegradability according to claim 6, characterized in that: A lifting platform (3) carrying a weighing scale (2) is arranged on the bottom fixed platform of the absorption tower (11). When weighing, the lifting platform (3) rises and the absorption tower (11) is automatically weighed by the weighing scale (2). The weighing control software calculates the carbon dioxide absorption amount according to the weight. When not weighing, the lifting platform (3) descends and the absorption tower (11) is supported by the fixed platform and the fixed frame (25) to protect the scale.

8. A method for weighing carbon dioxide automatic absorption for determining biodegradability, characterized in that: include: The gas in the biodegradation reaction container enters the alkali liquid collection pool, and the gas after the alkali liquid in the alkali liquid collection pool absorbs carbon dioxide rises and enters the packed absorption tower (11). The alkali liquid is automatically adjusted by the elution alkali liquid flow valve to be distributed to the packing of the absorption tower (11), and the gas and the alkali liquid are countercurrently exchanged in the packed tower to absorb carbon dioxide; During the absorption process of carbon dioxide in the absorption tower (11), the sprayed alkali solution flows into the alkali solution collection tank; when the alkali solution flowing from the alkali solution spray storage tank to the alkali solution collection tank reaches the maximum capacity, the flow meter at the tail gas outlet (26) closes the outlet gas, the valve of the air pressure balance pipe (6) and the alkali solution elution flow valve are closed, and when the pressurized gas enters the alkali solution collection tank, the pressure of the collection tank increases, and the alkali solution rises through the alkali solution lifting pipe (7) and enters the elution alkali solution storage tank (14), thereby realizing the automatic lifting circulation of the alkali solution.

9. The automatic carbon dioxide absorption weighing method for determining biodegradability according to claim 8, characterized in that: The gas flow range of the absorption tower (11) is set to be consistent with the measurement range of the biodegradation reaction container and is adjusted by the gas control flow meter of the biodegradation reaction container. The alkali solution lifting amount and speed are adjusted by the air intake flow rate of the air inlet.

10. The automatic carbon dioxide absorption weighing device for measuring biodegradability according to claim 8, characterized in that: The flow rate of the eluting alkali solution is controlled and adjusted according to the gas flow rate and the carbon dioxide concentration in the gas. The flow rate of the eluting alkali solution is automatically adjusted according to the carbon dioxide absorption amount and the gas flow change measured by automatic weighing, so that the absorption tower (11) can reach the optimal absorption state.

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