Method for measuring tar content in a pressurized fluidized bed biomass gasification process

Abstract

The present application belongs to the field of biomass gasification tar measurement, and relates to a method for measuring tar content in a pressurized fluidized bed biomass gasification process, comprising a tar sampling device and content determination. The sampling device comprises a stop valve, a sampling tube, a drying tube, a sampler, a pressure reducing valve, a cooling device, a wet gas flow meter and a pressure gauge, and can realize constant-speed sampling under high-temperature and high-pressure conditions. The measurement method is based on the filter membrane weighing method measurement principle, successfully separates the tar and dust content for measurement, realizes accurate measurement of the tar content, and is simple to operate, low in measurement cost and beneficial to practical application in industry.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of biomass gasification tar measurement, and particularly relates to a method for measuring tar content in a pressurized fluidized bed biomass gasification process. BACKGROUND

[0002] China is rich in biomass resources and has a wide distribution. Biomass gasification is an efficient biomass thermal conversion technology. This technology uses biomass as the basic raw material and uses oxygen, steam or hydrogen as the gasification medium to convert the combustible part of biomass into combustible gas under high temperature conditions. Biomass gasification is one of the effective ways to utilize biomass resources, and can convert agricultural and forestry waste such as straw and rice husk into valuable synthesis gas. It has the advantages of being green, clean and widely used. Among them, the gasification technology under high temperature and high pressure is called biomass pressurized gasification. Compared with normal pressure gasification, biomass pressurized gasification has high gasification efficiency and high quality synthesis gas, and has a wide application prospect in the energy field. Tar is a common by-product in the gasification process and is a complex organic mixture. Too high tar content can corrode the gasification equipment, reduce the gasification efficiency, and pollute the environment. The use of synthesis gas, the selection of purification process, and the stable operation of equipment are all directly affected by the tar content. Therefore, it is crucial to explore a method for detecting the tar content in the biomass pressurized gasification process.

[0003] At present, most of the literature uses gas chromatography-mass spectrometry (GC-MS) to analyze the yield and composition of tar. However, this technology has many limitations in industrial practice and is not widely applicable. The national standard GB 12208-2008 specifies the measurement method for tar and dust content in artificial gas, but it cannot achieve separate measurement of tar and dust, and the measurement result has a large error when the gas humidity is too large. GB 40508-2021 specifies the measurement method for tar content in biomass gas. This method uses solvent cold capture method to absorb tar into chloroform, and then separates the solvent and tar by rotary evaporator to measure the tar content. However, this method requires complex equipment and is not suitable for tar measurement under high pressure conditions.

[0004] In summary, there is currently a lack of suitable methods for measuring the tar content produced in the pressurized fluidized bed biomass gasification process, and therefore it is necessary to develop a method for measuring the tar produced in the pressurized fluidized bed biomass gasification process to achieve accurate measurement of the tar content. SUMMARY

[0005] The present application aims to solve the problem of tar measurement in industrial pressurized fluidized bed biomass gasification technology, and provides a method for simply measuring tar in the biomass pressurized gasification process, which achieves the purpose of accurately measuring the tar content and ensures the stable operation of the process equipment.

[0006] To achieve the above object, the technical scheme of the present application is as follows:

[0007] A method for measuring the tar content in a pressurized fluidized bed biomass gasification process, which utilizes a sampling device to measure the tar content;

[0008] The sampling device comprises a sampling tube, which is sequentially provided with a stop valve, a drying tube, a sampler, a pressure reducing valve, a cooling device, a wet gas flow meter and a pressure gauge;

[0009] The measuring method comprises the following steps:

[0010] (1) Put the dry glass fiber filter membrane with a mass of m1 into the sampler, and install the sampler;

[0011] (2) Connect the sampling device, and check the air tightness of the device; after the leak detection is completed, close the pressure reducing valve, and use N2 to charge the pressure in the sampling tube to the same pressure as that of the biomass gasification pipeline;

[0012] (3) Before sampling, open the stop valve and the pressure reducing valve for 1 min, and discharge the N2 in the sampling tube; during sampling, first open the stop valve, and then open the pressure reducing valve, and adjust the gas flow rate in the sampling tube to be the same as that of the biomass gasification pipeline; after sampling, first close the stop valve, and then close the pressure reducing valve, and record the readings of the wet gas flow meter before and after sampling;

[0013] (4) Open the sampler, take out the glass fiber filter membrane, dry it, and then weigh it, and the mass is recorded as m2;

[0014] (5) Place the glass fiber filter membrane in step (4) into a suction filtration device, add dichloromethane solution into the filter cup, and wait until the solution completely permeates into the bottom conical flask, and repeat the operation for 3-4 times, until the tar on the glass fiber filter membrane completely dissolves in the dichloromethane solution;

[0015] (6) Take out the glass fiber filter membrane in step (5), dry it, and then weigh it, and the mass is recorded as m3;

[0016] (7) Open the drying tube, take out the drying agent, and weigh it, and the mass is recorded as m4;

[0017] (8) Soak the drying agent in the dichloromethane solution for 1 h, after the soaking is completed, filter the solution using a funnel with a quantitative filter paper with a mass of m5, dry the filter paper and the residue after the filtration is completed, weigh and record m6;

[0018] After the above steps are completed, the tar content is calculated as follows:

[0019]

[0020] C = (m1 - m2) / V 3 )

[0021] m1 - mass of filter membrane before sampling (mg)

[0022] m2 - mass of filter membrane after sampling (mg)

[0023] m3 - mass of filter membrane after filtration and drying (mg)

[0024] m4 - mass of desiccant after sampling (mg)

[0025] m5 - mass of filter paper (mg)

[0026] m6 - mass of filter paper and residue after filtration and drying (mg)

[0027] V - volume of sampled gas (L)

[0028] Further, the sampling tube is made of stainless steel.

[0029] Further, the sampler is the same as that used in GB 12208-2008 Determination of tar and dust content in artificial gas.

[0030] Further, the glass fiber filter membrane is type 59 ultra-fine glass fiber filter membrane.

[0031] Further, the desiccant is calcium oxide and magnesium oxide.

[0032] Tar content measurement principle: a certain volume of gas passes through a glass fiber filter membrane of known mass, and the tar and dust in the gas are captured by the filter membrane. By measuring the mass difference of the filter membrane before and after sampling and the volume of the gas passing through, the tar and dust content can be calculated. Then, the tar on the filter membrane is completely dissolved in an organic solvent, and after drying, it is weighed again to obtain the content of the dust and tar captured by the filter membrane, respectively. Finally, the tar content adsorbed in the desiccant is added to the tar content captured by the filter membrane to obtain the tar content of the sampled gas.

[0033] Compared with the prior art, the present application has the following advantages:

[0034] The present application provides a method for measuring tar content during biomass pressurized gasification. The method can measure the tar content during biomass gasification under high temperature and high pressure, successfully separates the measurement of tar and dust content, realizes accurate measurement of tar content, is simple to operate, does not require complex instruments, has low measurement cost, and is beneficial to practical application in industry. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1This is a schematic diagram of a sampling device for a method of measuring tar content during pressurized fluidized bed biomass gasification according to the present invention. Detailed Implementation

[0036] To facilitate understanding of the present invention, a more comprehensive description will be given below. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the present invention.

[0037] Example 1

[0038] like Figure 1 As shown, a sampling device is installed at a stable point in the gas flow of the biomass gasification pipe 1. The sampling device includes a sampling pipe 3, on which are sequentially installed a shut-off valve 2, a drying pipe 4, a sampler 5, a pressure reducing valve 6 (to reduce gas pressure and adjust the gas flow rate through the pipe), a cooling device 7 (to reduce gas temperature and ensure accurate measurement by the wet gas flow meter), a wet gas flow meter 8, and a pressure gauge 9. The sampling pipe 3 is made of stainless steel, possessing the characteristic of withstanding high temperature and high pressure environments. The sampler 5 uses the same sampler as described in GB 12208-2008 for the determination of tar and dust content in manufactured gas. The drying pipe 4 contains desiccants calcium oxide and magnesium oxide to remove moisture from the gas and avoid the influence of gas moisture on tar measurement.

[0039] A method for measuring tar content during pressurized fluidized bed biomass gasification includes the following steps:

[0040] (1) After drying the Type 59 ultrafine glass fiber filter membrane (pore size 0.24μm) in a desiccator for 1 hour, weigh it and perform a check drying every 30 minutes until the difference between the two weighings does not exceed 0.3mg. Record its mass m1. Then, put the glass fiber filter membrane into the sampler and install the sampler.

[0041] (2) Connect the sampling device. With the shut-off valve closed, use high-pressure N2 to check the airtightness of the sampling device to ensure that the device is leak-free. After the leak test is completed, close the pressure reducing valve and use high-pressure N2 to pressurize the sampling tube to the same pressure as the biomass gasification pipeline.

[0042] (3) Before sampling, open the stop valve and the pressure reducing valve for 1 min to discharge N2 in the sampling tube. During sampling, the gas flow rate in the sampling tube should be adjusted to be the same as that in the biomass gasification pipeline to realize equal-speed sampling. According to the gas flow rate of the synthesis gas and the diameters of the biomass gasification pipeline and the sampling tube, the gas flow rate in the sampling tube can be calculated. During sampling, first open the stop valve, and then open the pressure reducing valve to adjust the gas flow rate in the sampling tube to the calculated value. After sampling, first close the stop valve, and then close the pressure reducing valve. Record the readings of the wet gas flow meter before and after sampling to calculate the volume of the sampled gas.

[0043] (4) After the device is depressurized, open the sampling device, take out the glass fiber filter membrane, and place it in a desiccator to dry for 1 h. After the check drying, record the mass m2.

[0044] (5) Place the glass fiber filter membrane of step (4) in a suction filtration device, add dichloromethane solution in the filter cup, and wait until the solution is completely infiltrated into the bottom conical flask. Repeat the operation for 3-4 times to completely dissolve the tar on the glass fiber filter membrane in the dichloromethane solution.

[0045] (6) Take out the glass fiber filter membrane of step (5) and place it in a drying dish. Then, transfer the drying dish to a constant temperature drying oven at 80°C to dry for 3 h. After drying, take out the drying dish and place it in a desiccator. After natural cooling to room temperature, weigh the glass fiber filter membrane, and record the mass m3 after check drying.

[0046] (7) Open the drying tube, take out all the drying agents, and weigh the mass as m4.

[0047] (8) Soak the drying agents in a beaker containing dichloromethane solution for 1 h. Then, take a quantitative filter paper with a mass of m5 and place it in a funnel. Filter the solution in the beaker through the funnel. After filtration, place the filter paper and the residue in a constant temperature drying oven at 80°C to dry for 4 h. Then, place them in a desiccator. After natural cooling to room temperature, weigh them and record the mass m6.

[0048] After the above steps are completed, the tar content is calculated as follows:

[0049]

[0050] In the formula, C—tar content in the gas (g / m 3 )

[0051] m1—mass of the filter membrane before sampling (mg)

[0052] m2—mass of the filter membrane after sampling (mg)

[0053] m3—mass of the filter membrane after filtration and drying (mg)

[0054] m4 - mass of the dried sample (mg)

[0055] m5 - mass of the filter paper (mg)

[0056] m6 - mass of the dried filter paper and residue (mg)

[0057] V - volume of the sampled gas (L)

[0058] Example 2

[0059] Taking the measurement of tar content in the pressurized fluidized bed biomass gasification engineering experiment as an example, the experiment pressure is 1.0 MPa, the gasification temperature is 850°C, and the sampling port temperature is 200°C. The sampling position is selected in the smooth pipeline of the gas flow after the multi-stage cyclone separator, at which time a part of the dust carried in the gas flow has been removed.

[0060] The sampling and content measurement are performed according to the steps of Example 1, and the measured tar content is 5.4 g / m 3 .

[0061] Example 3

[0062] Taking the measurement of tar content in the pressurized fluidized bed biomass gasification engineering experiment as an example, the experiment pressure is 2.0 MPa, the gasification temperature is 900°C, and the sampling port temperature is 250°C.

[0063] The sampling and content measurement are performed according to the steps of Example 1, and the measured tar content is 0.8 g / m 3 .

[0064] Example 4

[0065] Taking the measurement of tar content in the pressurized fluidized bed biomass gasification engineering experiment as an example, the experiment pressure is 1.5 MPa, the gasification temperature is 900°C, and the sampling port temperature is 220°C.

[0066] The sampling and content measurement are performed according to the steps of Example 1, and the measured tar content is 2.2 g / m 3 .

[0067] The above only serves to better explain the embodiments of the present application, and is not a limitation thereof, and any modification or equivalent replacement within the spirit and scope of the present application is included in the scope of the present application.

Claims

1. A method for measuring tar content during pressurized fluidized bed biomass gasification, characterized in that, The tar content was measured using a sampling device; The sampling device includes a sampling tube, on which a shut-off valve, a drying tube, a sampler, a pressure reducing valve, a cooling device, a wet gas flow meter, and a pressure gauge are sequentially arranged. The measurement method includes: (1) Place the dried glass fiber filter membrane with a mass of m1 into the sampler and install the sampler. (2) Connect the sampling device and check the airtightness of the device; after the leak test is completed, close the pressure reducing valve and use N2 to fill the pressure in the sampling tube to the same pressure as the biomass gasification pipeline. (3) Before sampling, open the shut-off valve and the pressure reducing valve for 1 minute to purge the N2 in the sampling tube; during sampling, first open the shut-off valve, then open the pressure reducing valve, and adjust the gas flow rate in the sampling tube to be the same as the gas flow rate in the biomass gasification pipeline; after sampling, first close the shut-off valve, then close the pressure reducing valve, and record the readings of the wet gas flow meter before and after sampling. (4) Open the sampler, take out the glass fiber filter membrane, dry it and weigh it, and record its mass as m2; (5) Place the glass fiber filter membrane from step (4) into the vacuum filtration device, add dichloromethane solution to the filter cup, and wait for the solution to completely seep into the bottom conical flask. Repeat the operation 3-4 times until the tar on the glass fiber filter membrane is completely dissolved in the dichloromethane solution. (6) Take out the glass fiber filter membrane from step (5), dry it and weigh it, and record its mass as m3; (7) Open the drying tube, take out the desiccant and weigh it. Record its mass as m4. (8) Soak the desiccant in dichloromethane solution for 1 hour. After soaking, filter the solution through a funnel with quantitative filter paper of mass m5. After filtration, dry the filter paper and filter residue, weigh and record m6. After completing the above steps, the tar content is calculated as follows: In the formula, C—tar content in the gas (g / m³) 3 ) m1 — Mass of the filter membrane before sampling (mg) m2 — Mass of the filter membrane after sampling (mg) m3 — Mass of the filter membrane after filtration and drying (mg) m4 — Mass of desiccant after sampling (mg) m5 — Mass of filter paper (mg) m6 — Mass of the dried filter paper and filter residue (mg) V — Sample gas volume (L).

2. The method for measuring tar content during pressurized fluidized bed biomass gasification according to claim 1, characterized in that, The sampling tube is made of stainless steel.

3. The method for measuring tar content during pressurized fluidized bed biomass gasification according to claim 1, characterized in that, The sampler used is the same sampler used in GB 12208-2008 for the determination of tar and dust content in manufactured gas.

4. The method for measuring tar content during pressurized fluidized bed biomass gasification according to claim 1, characterized in that, The glass fiber filter membrane is a type 59 ultrafine glass fiber filter membrane.

5. The method for measuring tar content during pressurized fluidized bed biomass gasification according to claim 1, characterized in that, The desiccant is calcium oxide and magnesium oxide.

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