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

Abstract

The invention 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, which comprises a tar sampling device and content measurement. The sampling device comprises a stop valve, a sampling pipe, a drying pipe, a sampler, a pressure reducing valve, a cooling device, a wet gas flowmeter and a pressure gauge, and can realize constant-speed sampling under high-temperature and high-pressure conditions. The measuring method is based on the measuring principle of a filter membrane weighing method, the tar content and the dust content are successfully measured separately, accurate measurement of the tar content is achieved, operation is easy, the measuring cost is low, and industrial practical application is facilitated.

Description

Technical Field

[0001] The present invention belongs to the technical field of biomass gasification tar measurement, and specifically relates to a method for measuring the tar content during the pressurized fluidized bed biomass gasification process. Background Art

[0002] Biomass resources in China are abundant and widely distributed. Biomass gasification is an efficient biomass thermal conversion technology. This technology uses biomass as the basic raw material, and uses oxygen, steam, hydrogen, etc. as the gasification medium. Through thermochemical reactions under high temperature conditions, the combustible part of biomass is converted into combustible gas. Biomass gasification is one of the effective ways to utilize biomass resources, which can convert agricultural and forestry waste such as straw and rice husks into valuable syngas, and has the advantages of being green, clean, and widely used. Among them, the gasification technology under high temperature and high pressure conditions is called biomass pressurized gasification. Compared with atmospheric pressure gasification, biomass pressurized gasification has high gasification efficiency and high-quality syngas, and has broad application prospects in the energy field. Tar is a common by-product in the gasification process and is a complex organic mixture. Excessive tar content will corrode the gasification equipment, reduce the gasification efficiency, and pollute the environment. The uses of syngas, the selection of purification processes, and the stable operation of equipment are all directly affected by the tar content. Therefore, it is crucial to explore a detection method for tar content during biomass pressurized gasification.

[0003] At present, most of the literature uses gas chromatography-mass spectrometry (GC-MS) to analyze the yield and composition of tar. However, the application of this technology in industrial practice is restricted by many factors and does not have wide applicability. National Standard GB 12208-2008 stipulates the measurement method for tar and dust content in artificial gas, but it cannot achieve the separate measurement of tar and dust, and when the gas humidity is too high, the measurement result error is large. GB 40508-2021 stipulates the measurement method for tar content in biomass gas. This method uses the solvent cold trapping method to absorb tar into chloroform, and then separates the solvent and tar through a 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 a suitable method for measuring the tar content generated during the pressurized fluidized bed biomass gasification process. Therefore, it is very necessary to develop a method for measuring pressurized fluidized bed biomass gasification tar to achieve accurate measurement of tar. Summary of the Invention

[0005] Aiming at the problem of difficult tar measurement in the industrial pressurized fluidized bed biomass gasification technology, the present invention provides a method for simply measuring tar during the biomass pressurized gasification process, achieving the purpose of accurately measuring the tar content to ensure the stable operation of process equipment.

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

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

[0008] The sampling device includes a sampling pipe, on which a stop valve, a drying pipe, a sampler, a pressure reducing valve, a cooling device, a wet gas flowmeter and a pressure gauge are sequentially arranged;

[0009] The measurement method includes:

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

[0011] (2) Connect the sampling device and check the airtightness of the device; after the leak detection is completed, close the pressure reducing valve and fill the pressure in the sampling pipe with N 2 to be the same as the pressure in the biomass gasification pipeline;

[0012] (3) Before sampling, open the stop valve and the pressure reducing valve for 1 min to exhaust the N 2 in the sampling pipe; when sampling, first open the stop valve, then open the pressure reducing valve, and adjust the gas flow rate in the sampling pipe to be the same as the gas flow rate in the biomass gasification pipeline; after sampling is completed, first close the stop valve, then close the pressure reducing valve, and record the readings of the wet gas flowmeter before and after sampling;

[0013] (4) Open the sampler, take out the glass fiber filter membrane, dry it and weigh it, and record its mass as m 2 ;

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

[0015] (6) Take out the glass fiber filter membrane in step (5), dry it and weigh it, and record its mass as m 3 ;

[0016] (7) Open the drying pipe, take out the desiccant and weigh it, and record its mass as m 4 ;

[0017] (8) Immerse the desiccant in dichloromethane solution for 1 h. After the immersion is completed, filter the solution through a funnel lined with a quantitative filter paper with a mass of m 5 . After the filtration is completed, dry the filter paper and the filter residue, weigh them and record m 6 ;

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

[0019]

[0020] In the formula, C—the tar content in the gas (g / m 3 )

[0021] m 1 —the mass of the filter membrane before sampling (mg)

[0022] m 2 —the mass of the filter membrane after sampling (mg)

[0023] m 3 —the mass of the filter membrane after filtration and drying (mg)

[0024] m 4 —the mass of the desiccant after sampling (mg)

[0025] m 5 —the mass of the filter paper (mg)

[0026] m 6 —the mass of the filter paper and the filter residue after filtration and drying (mg)

[0027] V—the volume of the sampled gas (L).

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

[0029] Furthermore, the sampler uses the same sampler as that for the determination of tar and dust content in artificial coal gas in GB 12208-2008.

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

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

[0032] Principle of tar content measurement: A certain volume of gas passes through a glass fiber filter membrane with a known mass. The tar and dust in the gas will be captured by the filter membrane. By measuring the mass difference of the filter membrane before and after sampling and the volume of the gas passed through, the content of tar and dust can be calculated. Then, the tar on the filter membrane is completely dissolved in an organic solvent, dried and weighed again to obtain the content of dust and tar captured by the filter membrane respectively. Finally, adding the tar content adsorbed by the desiccant to the tar content captured by the filter membrane can obtain the tar content of the sampled gas.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0034] The present invention provides a method for measuring tar content during biomass pressurized gasification. This method can measure the tar content in the biomass gasification process under high temperature and high pressure conditions, successfully separate and measure the tar and dust contents, achieve accurate measurement of the tar content, and has the advantages of simple operation, no need for complex instruments, low measurement cost, and being conducive to practical industrial applications. Brief Description of the Drawings

[0035] Figure 1 It is a schematic diagram of the sampling device for measuring the tar content in the pressurized fluidized bed biomass gasification process of the present invention. Detailed Embodiments

[0036] To facilitate the understanding of the present invention, the present invention will be described more comprehensively below. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosed content of the present invention more thorough and comprehensive.

[0037] Embodiment 1

[0038] As Figure 1 shown, a sampling device is installed at a place with stable gas flow in the biomass gasification tube 1. The sampling device includes a sampling tube 3, on which a stop valve 2, a drying tube 4, a sampler 5, a pressure reducing valve 6 (one is to reduce the gas pressure, and the other is to adjust the gas flow rate through the pipeline), a cooling device 7 (which can reduce the gas temperature to ensure accurate measurement by the wet gas flowmeter), a wet gas flowmeter 8 and a pressure gauge 9 are sequentially arranged. Among them, the sampling tube 3 is made of stainless steel material and has the characteristic of withstanding high temperature and high pressure environments; the sampler 5 uses the same sampler as that for the determination of tar and dust contents in artificial coal gas in GB 12208 - 2008; the drying tube 4 is filled with desiccants calcium oxide and magnesium oxide to remove the moisture in the gas and avoid the influence of gas moisture on tar measurement.

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

[0040] (1) After drying a 59 - type ultra - fine glass fiber filter membrane (pore size 0.24μm) in a dryer for 1 h, weigh it, and conduct an inspection drying every 30 min until the difference between the second weighing and the first weighing does not exceed 0.3 mg, and record its mass m 1 . Subsequently, put this glass fiber filter membrane into the sampler and install the sampler well.

[0041] (2) Connect the sampling device. Without opening the stop valve, use high - pressure N 2 to check the airtightness of the sampling device to ensure that the device is airtight. After the leak detection is completed, close the pressure reducing valve and use high - pressure N 2Fill the pressure in the sampling pipe to be the same as that in the biomass gasification pipeline.

[0042] (3) Before sampling, open the stop valve and pressure reducing valve for 1 min to drain the N in the sampling pipe. 2 . During sampling, it is necessary to adjust the gas flow rate in the sampling pipe to be the same as that in the biomass gasification pipeline to achieve isokinetic sampling. According to the different synthesis gas flow rates and the diameters of the biomass gasification pipe and the sampling pipe, the gas flow rate in the sampling pipe can be calculated. During the sampling process, first open the stop valve, the gas passes through the drying tube and the sampler, then open the pressure reducing valve, and adjust the gas flow rate in the sampling pipe to the calculated value above. After sampling, first close the stop valve, and then close the pressure reducing valve. Record the readings of the wet gas flowmeter before and after sampling to calculate the volume of the sampled gas.

[0043] (4) After the device is depressurized, open the sampler, take out the glass fiber filter membrane, place it in a dryer and dry it for 1 h, then weigh it. After checking and drying, record its mass m. 2 .

[0044] (5) Place the glass fiber filter membrane in step (4) in a suction filtration device, add dichloromethane solution to the filter cup, wait for the solution to completely penetrate into the bottom conical flask, and repeat the operation 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 in step (5) and place it in a drying dish. Then transfer the drying dish to a constant temperature drying oven at 80 °C and dry it for 3 h. After drying, take out the drying dish and put it in a dryer. After it naturally cools to room temperature, weigh the glass fiber filter membrane. After checking and drying, record its mass m. 3 .

[0046] (7) Open the drying tube, take out all the desiccants, and weigh its mass and record it as m. 4 .

[0047] (8) Soak the desiccant in a beaker containing dichloromethane solution for 1 h. Then take a quantitative filter paper with a mass of m. 5 and place it in a funnel. Filter the solution in the beaker through the funnel. After filtration, place the filter paper and the filter residue in a constant temperature drying oven at 80 °C and dry it for 4 h. Then put it in a dryer. After it naturally cools to room temperature, weigh it and record its mass m. 6 .

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

[0049]

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

[0051] m 1 — Mass of the filter membrane before sampling (mg)

[0052] m 2 — Mass of the filter membrane after sampling (mg)

[0053] m 3 — Mass of the filter membrane after filtration and drying (mg)

[0054] m 4 — Mass of the desiccant after sampling (mg)

[0055] m 5 — Mass of the filter paper (mg)

[0056] m 6 — Mass of the filter paper and filter residue after filtration and drying (mg)

[0057] V — Sampling gas volume (L)

[0058] Example 2

[0059] Taking the measurement of tar content in the pressurized fluidized bed biomass gasification engineering test as an example, the test 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 after the multi-stage cyclone separator, and at this time, a part of the dust carried in the gas flow has been removed.

[0060] Sampling and content measurement were carried out according to the steps of Example 1, and the measured tar content was 5.4 g / m 3 .

[0061] Example 3

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

[0063] Sampling and content measurement were carried out according to the steps of Example 1, and the measured tar content was 0.8 g / m 3 .

[0064] Example 4

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

[0066] Sampling and content measurement were carried out according to the steps of Example 1, and the measured tar content was 2.2 g / m 3 .

[0067] The above is only for better explaining the embodiments of the present invention and is not a limitation thereof. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention shall fall within the scope covered by the present invention.

Claims

1. A method for measuring tar content in a pressurized fluidized bed biomass gasification process, characterized in that: Using sampling device to measure tar content; The sampling device comprises a sampling tube, on which a stop 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 measuring method comprises: (1) Place a dry glass fiber filter membrane with a mass of m1 into the sampler and install the sampler; (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 fill the pressure in the sampling tube to the same pressure as the biomass gasification pipeline; (3) Before sampling, open the stop valve and the pressure reducing valve for 1 min to exhaust the N2 in the sampling tube; when sampling, open the stop valve first, 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, close the stop valve first, 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. The mass is recorded as m2; (5) Place the glass fiber filter membrane in step (4) into a suction filtration device, add dichloromethane solution into the filter cup, and wait for the solution to completely penetrate 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) taking out the glass fiber filter membrane from step (5), drying it and weighing it, and recording its mass as m3; (7) Open the drying tube, take out the desiccant and weigh it. Its mass is recorded as m4; (8) Soak the desiccant in a dichloromethane solution for 1 hour. After the soaking, filter the solution through a funnel padded with a quantitative filter paper with a mass of m5. After the filtration is completed, dry the filter paper and the filter residue, weigh them, and record m6; After the above steps are completed, the tar content is calculated as follows: Where, C—tar content in gas (g / m 3 ) m1—Mass of 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 filter paper and filter residue after filtration and drying (mg) V—Sampling gas volume (L).

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

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

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

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

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