A method and apparatus for preparing combustible gas by biomass baking and co-pyrolysis of polypropylene

Abstract

This invention discloses a method and apparatus for preparing combustible gas by co-pyrolysis of biomass with polypropylene. Biomass is mixed with water, subjected to wet roasting, and then cooled. Solid-liquid separation is performed, and the resulting solid sample is washed to neutral pH and then dried to constant weight. The resulting biomass and polypropylene are mixed and pyrolyzed under a protective atmosphere, and the pyrolysis gas is collected. This invention, using biomass co-pyrolysis of polypropylene to prepare combustible gas, is convenient to operate, facilitates product collection, and improves product quality. It also increases the biomass pyrolysis gasification conversion rate and hydrogen collection rate, achieving high-value utilization of biomass.

Description

Technical Field

[0001] This invention relates to the field of biomass energy technology, and in particular to a method and apparatus for preparing combustible gas by biomass baking and co-pyrolysis of polypropylene. Background Technology

[0002] Black tea residue, the waste generated after the use of black tea, belongs to a type of biomass. Biomass is carbon-containing and renewable, giving it a natural advantage over other renewable resources (such as solar and wind power). Thermochemical technologies such as biomass pyrolysis and gasification are green and sustainable ways to utilize biomass, effectively converting it into high-calorific-value gaseous fuels, liquid fuels, and functional carbon materials. These products can be used for power generation, combustion heating, or the synthesis of various high-value-added chemical substances. However, biomass has a high oxygen content and low hydrogen content, resulting in a high proportion of oxygen-containing gases in the syngas. This significantly reduces the combustion efficiency of the pyrolysis gas, making it difficult to use as fuel and reducing its utilization value. Furthermore, the high oxygen content leads to the production of black tea residue pyrolysis tar, which can easily clog downstream pipelines and seriously affect the safety of the process system.

[0003] Appropriate pretreatment of dark tea residue can alter its recalcitrant structure and remove inorganic elements, thereby improving its composition, pyrolysis efficiency, and product quality. Furthermore, co-pyrolysis of dark tea residue with polypropylene can improve the quality of the pyrolysis products. On one hand, the free radicals generated during the pyrolysis of dark tea residue can promote the breaking of CH bonds in high-molecular-weight polypropylene, increasing pyrolysis efficiency. On the other hand, the addition of hydrogen-rich polypropylene can significantly increase the content of combustible gases such as hydrogen in the syngas, improving the quality of the pyrolysis gas.

[0004] To achieve high-value utilization of black tea residue and improve the conversion rate of black tea residue to gas and the hydrogen collection rate, combustible gas is prepared by wet roasting pretreatment of black tea residue followed by polypropylene co-pyrolysis.

[0005] This invention is applicable not only to black tea residue, but also to biomass such as Chinese medicine residue, rice straw, and chili straw. Summary of the Invention

[0006] The purpose of this invention is to provide a method and apparatus for preparing combustible gas by first pre-treating biomass by baking and then co-pyrolyzing polypropylene. This invention can effectively improve the conversion rate of biomass pyrolysis to gas and the hydrogen collection rate.

[0007] To achieve the above technical objectives, the present invention adopts the following technical solution:

[0008] A method for preparing combustible gas by biomass baking and co-pyrolysis of polypropylene includes the following steps:

[0009] Step 1: Mix biomass with water, perform wet baking treatment, and then cool; separate solid and liquid, wash the obtained solid sample to neutral pH, and then dry to constant weight;

[0010] Step 2: Mix the biomass obtained in Step 1 with polypropylene and pyrolyze under a protective atmosphere, then collect the pyrolysis gas.

[0011] The biomass mentioned includes at least one of the following: black tea residue, Chinese medicine residue, rice straw, and chili straw.

[0012] The preferred particle size range for biomass is 0.15–0.25 mm.

[0013] The ratio of biomass to water in step one is 1:5 to 1:15, and the temperature range is 140℃ to 200℃, preferably 150-180℃.

[0014] The wet baking time described in step one shall not exceed 2 hours.

[0015] Step 2: The mixing ratio of biomass and polypropylene is 1:1 to 1:5; preferably 1:1 to 1:2.

[0016] The initial temperature range for pyrolysis in step two is 20℃~50℃, preferably 20℃~30℃, and the final temperature range is 700℃~900℃, preferably 750℃~850℃.

[0017] Step 2: The heating rate is 8-12℃ / min. When the temperature reaches 150℃~250℃ (preferably 200℃), the pyrolysis gas is collected. When the temperature starts to drop from 700℃~900℃ (preferably 800℃), the collection of pyrolysis gas is stopped.

[0018] Step two involves a protective atmosphere, which includes nitrogen.

[0019] Further optimization: A method for preparing combustible gas by roasting black tea residue and co-pyrolyzing polypropylene, comprising:

[0020] A measured amount of black tea residue was mixed with an appropriate amount of distilled water and subjected to wet roasting to obtain a roasted sample. After the reaction was completed, the reactants were cooled in an ice-water bath. Solid and liquid samples were separated by vacuum filtration. The obtained solid sample was washed several times with deionized water to neutralize the pH value, and then dried overnight in an oven to achieve a constant weight.

[0021] Further, approximately 10g of each of the roasted black tea residue and polypropylene mixed sample were weighed and placed in a quartz boat, and the sample weight was recorded as m1. At the same time, the gas collecting bottles No. 1 and No. 2 and all the conduits of the gas collecting device were weighed and recorded as m2, m3 and m4.

[0022] The quartz boat containing the sample was then placed into a tube furnace, the furnace plugs were sealed on both sides, and the nitrogen cylinder and pyrolysis oil collection device were connected.

[0023] Further open the nitrogen cylinder switch, control the nitrogen flow rate to 80-120 ml / min and check the airtightness of the device. After purging the air by passing nitrogen for 10 minutes, start the heating device. Set the initial temperature of the heating device to 20℃-50℃, the heating rate to 8℃ / min-12℃ / min, the final temperature to 700℃-900℃, and the holding time to 1-2 hours.

[0024] Further, a pyrolysis gas collection bag was connected when the temperature reached 150℃~250℃. The gas bag was removed after the temperature began to drop from 700℃~900℃. At the end of the experiment, the three-phase products were collected and weighed.

[0025] As a further improvement of the present invention, the baking temperatures of the samples are 150°C, 170°C and 190°C.

[0026] The present invention also provides an apparatus for the method described, comprising an air intake device, a reaction device, a condensation device and a gas collection device connected in sequence.

[0027] The reaction device includes a sealed reaction tube with gas pipes at both ends and a heating unit. The sealed reaction tube contains reactants, and one end is connected to a gas inlet device to introduce a protective atmosphere, while the other end is connected to a condenser device to discharge pyrolysis gases. The heating unit heats the sealed reaction tube.

[0028] The condensation device includes a condensation unit and a drying unit. The condensation unit is connected to a sealed reaction tube and condenses the pyrolysis gas. The drying unit dries the remaining gas after condensation and discharges it into a gas collection device.

[0029] The sealed reaction tube is a quartz tube, and a quartz boat for placing the reactants is also provided inside the quartz tube; both ends of the quartz tube are provided with furnace plugs for heat preservation, and flanges are provided at the outer ends of the furnace plugs for sealing; the heating unit is a tube furnace.

[0030] The condensation unit of the condensation device includes at least two condensation gas collecting bottles connected in series, and the drying unit is a drying gas collecting bottle with a desiccant inside. Both the condensation gas collecting bottle and the drying gas collecting bottle are placed in a low-temperature environment, and both the condensation gas collecting bottle and the drying gas collecting bottle are provided with an inlet pipe and an outlet pipe. The inlet pipe extends to the bottom of the bottle body, and the outlet pipe is located at the top of the bottle body.

[0031] The beneficial effects of this invention are as follows:

[0032] (1) In this invention, the wet baking pretreatment of biomass can improve the pore structure of biochar, increase the specific surface area, and use it for pyrolysis to prepare combustible gas.

[0033] (2) In the method of the present invention, as the baking temperature rises, the hydrogen content in the black tea residue can be effectively increased and the oxygen content can be reduced, and the yield of black tea residue pyrolysis gasification is significantly increased by 10%.

[0034] (3) In the method of the present invention, the co-pyrolysis of black tea residue and polypropylene has a synergistic effect. The co-pyrolysis of black tea residue and polypropylene can increase the output value of high-calorific-value combustible gas and realize the high-value utilization of black tea residue. Attached Figure Description

[0035] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0036] Figure 1 This is a diagram of a biomass pyrolysis apparatus provided in an embodiment of the present invention.

[0037] In the diagram: 1. Nitrogen cylinder; 2. Furnace stopper; 3. Quartz tube; 4. Quartz boat; 5. Tube furnace; 6. Glass tubing; 7. Rubber stopper; 8. Desiccant bottle; 9. Ice pack; 10. Condenser bottle; 11. Water; 12. Color-changing silica gel; 13. Gas storage bag. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0039] This invention provides a method and apparatus for preparing combustible gas by biomass roasting and co-pyrolysis of polypropylene. The following examples use black tea residue as an example.

[0040] Black tea residue sieved through a 100-mesh sieve was mixed with distilled water at a ratio of 1:10 and poured into a reaction vessel. Wet roasting was then performed at different temperature gradients, yielding roasted samples treated for 2 hours at each gradient. After the reaction, the reactants were cooled in an ice-water bath. Solid and liquid samples were separated by vacuum filtration. The resulting solid samples were washed several times with deionized water to neutralize the pH, and then dried overnight in an oven to achieve a constant weight.

[0041]

[0042] a By difference

[0043] Example 1: Pyrolysis of unroasted black tea residue. Figure 1The diagram shows the pyrolysis apparatus for black tea residue provided in this embodiment of the invention. Approximately 10g of unbaked sample is weighed and placed in a quartz boat, and the sample weight is recorded as m1. Simultaneously, the weights of gas collecting bottles 1 and 2, as well as all the conduits of the gas collecting device, are weighed and recorded as m2, m3, and m4, respectively. The quartz boat containing the sample is then placed in a tube furnace, with plugs secured on both sides. The nitrogen cylinder and pyrolysis oil collecting device are then connected. Next, the nitrogen cylinder switch is turned on, the nitrogen flow rate is controlled at 100ml / min, and the airtightness of the apparatus is checked. After purging the air by passing nitrogen for 10 minutes, the heating device is run. The initial temperature of the heating device is set to 30℃, the heating rate to 10℃ / min, the final temperature to 800℃, and the holding time to 2 hours. When the temperature reaches 200℃, the pyrolysis gas collecting bag is connected. The gas bag is removed when the temperature begins to decrease from 800℃. At the end of the experiment, the three-phase products are collected and weighed.

[0044] gas liquid solid <![CDATA[H2]]> CO <![CDATA[CH4]]> <![CDATA[CO2 <!-- 3 -->]]> Yield 60.0wt% 13.0wt% 27.0wt% 29.0％ 34.0％ 21.0％ 16.0％

[0045] Example 2: Black tea residue was roasted at 150℃ and then pyrolyzed separately. Figure 1 The diagram shows the pyrolysis apparatus for black tea residue provided in this embodiment of the invention. Approximately 10g of the roasted sample is weighed and placed in a quartz boat, and the sample weight is recorded as m1. Simultaneously, the weights of gas collecting bottles 1 and 2, as well as all the conduits of the gas collecting device, are weighed and recorded as m2, m3, and m4, respectively. The quartz boat containing the sample is then placed in a tube furnace, with plugs secured on both sides. The nitrogen cylinder and the pyrolysis oil collecting device are then connected. Next, the nitrogen cylinder switch is turned on, the nitrogen flow rate is controlled at 100ml / min, and the airtightness of the apparatus is checked. After purging the air by passing nitrogen for 10 minutes, the heating device is run. The initial temperature of the heating device is set to 30℃, the heating rate to 10℃ / min, the final temperature to 800℃, and the holding time to 2 hours. When the temperature reaches 200℃, the pyrolysis gas collecting bag is connected. The gas bag is removed when the temperature begins to decrease from 800℃. At the end of the experiment, the three-phase products are collected and weighed.

[0046] gas liquid solid <![CDATA[H2]]> CO <![CDATA[CH4]]> <![CDATA[CO2]]> Yield 59.0wt% 13.0wt% 28.0wt% 35.0％ 12.0％ 30.0％ 23.0％

[0047] Example 3: Black tea residue was roasted at 170℃ and then pyrolyzed separately. Figure 1The diagram shows the pyrolysis apparatus for black tea residue provided in this embodiment of the invention. Approximately 10g of the roasted sample is weighed and placed in a quartz boat, and the sample weight is recorded as m1. Simultaneously, the weights of gas collecting bottles 1 and 2, as well as all the conduits of the gas collecting device, are weighed and recorded as m2, m3, and m4, respectively. The quartz boat containing the sample is then placed in a tube furnace, with plugs secured on both sides. The nitrogen cylinder and the pyrolysis oil collecting device are then connected. Next, the nitrogen cylinder switch is turned on, the nitrogen flow rate is controlled at 100ml / min, and the airtightness of the apparatus is checked. After purging the air by passing nitrogen for 10 minutes, the heating device is run. The initial temperature of the heating device is set to 30℃, the heating rate to 10℃ / min, the final temperature to 800℃, and the holding time to 2 hours. When the temperature reaches 200℃, the pyrolysis gas collecting bag is connected. The gas bag is removed when the temperature begins to decrease from 800℃. At the end of the experiment, the three-phase products are collected and weighed.

[0048] gas liquid solid <![CDATA[H2]]> CO <![CDATA[CH4]]> <![CDATA[CO2]]> Yield 63.4 wt% 10.0wt% 26.6wt% 34.0％ 27.0％ 20.0％ 19.0％

[0049] Example 4: Black tea residue was roasted at 190℃ and then pyrolyzed separately. Figure 1 The diagram shows the pyrolysis apparatus for black tea residue provided in this embodiment of the invention. Approximately 10g of the roasted sample is weighed and placed in a quartz boat, and the sample weight is recorded as m1. Simultaneously, the weights of gas collecting bottles 1 and 2, as well as all the conduits of the gas collecting device, are weighed and recorded as m2, m3, and m4, respectively. The quartz boat containing the sample is then placed in a tube furnace, with plugs secured on both sides. The nitrogen cylinder and the pyrolysis oil collecting device are then connected. Next, the nitrogen cylinder switch is turned on, the nitrogen flow rate is controlled at 100ml / min, and the airtightness of the apparatus is checked. After purging the air by passing nitrogen for 10 minutes, the heating device is run. The initial temperature of the heating device is set to 30℃, the heating rate to 10℃ / min, the final temperature to 800℃, and the holding time to 2 hours. When the temperature reaches 200℃, the pyrolysis gas collecting bag is connected. The gas bag is removed when the temperature begins to decrease from 800℃. At the end of the experiment, the three-phase products are collected and weighed.

[0050] gas liquid solid <![CDATA[H2]]> CO <![CDATA[CH4]]> <![CDATA[CO2]]> Yield 69.4wt% 3.2wt% 27.4wt% 31.0％ 28.0％ 23.4％ 17.6％

[0051] Example 5: Black tea residue was roasted at 150℃ and then co-pyrolyzed with polypropylene. Figure 1The diagram shows the pyrolysis apparatus for black tea residue provided in this embodiment of the invention. A 1:1 mixture of roasted sample and polypropylene is weighed and placed in a quartz boat, with the sample weight recorded as m1. Simultaneously, gas collecting bottles 1 and 2, as well as all the conduits of the gas collecting device, are weighed and recorded as m2, m3, and m4, respectively. The quartz boat containing the sample is then placed in a tube furnace, with plugs secured on both sides. A nitrogen cylinder and a pyrolysis oil collecting device are connected. Next, the nitrogen cylinder is turned on, the nitrogen flow rate is controlled at 100 ml / min, and the airtightness of the apparatus is checked. After purging the air by passing nitrogen for 10 minutes, the heating device is run. The initial temperature of the heating device is set to 30°C, the heating rate to 10°C / min, the final temperature to 800°C, and the holding time to 2 hours. When the temperature reaches 200°C, the pyrolysis gas collecting bag is connected. The gas bag is removed when the temperature begins to drop from 800°C. At the end of the experiment, the three-phase products are collected and weighed.

[0052] gas liquid solid <![CDATA[H2]]> CO <![CDATA[CH4]]> <![CDATA[CO2]]> Yield 70.0wt% 11.0wt% 19.0wt% 52.0％ 7.0％ 17.0％ 24.0％

[0053] Example 6: Black tea residue was roasted at 170℃ and then co-pyrolyzed with polypropylene. Figure 1 The diagram shows the black tea residue pyrolysis apparatus provided in this embodiment of the invention. A roasted sample is mixed with polypropylene at a 1:1 ratio, and approximately 10g is weighed and placed in a quartz boat. The sample weight is recorded as m1. Simultaneously, gas collecting bottles 1 and 2, as well as all the conduits of the gas collecting device, are weighed and recorded as m2, m3, and m4, respectively. The quartz boat containing the sample is then placed in a tube furnace, with plugs secured on both sides. A nitrogen cylinder and a pyrolysis oil collecting device are connected. Next, the nitrogen cylinder switch is turned on, the nitrogen flow rate is controlled at 100ml / min, and the airtightness of the apparatus is checked. After purging the air by passing nitrogen for 10 minutes, the heating device is started. The initial temperature of the heating device is set to 30℃, the heating rate to 10℃ / min, the final temperature to 800℃, and the holding time to 2 hours. When the temperature reaches 200℃, the pyrolysis gas collecting bag is connected. The gas bag is removed when the temperature begins to drop from 800℃.

[0054] At the end of the experiment, the three-phase products were collected and weighed.

[0055]

[0056]

[0057] Analysis of the above implementation cases shows that wet roasting of black tea residue can effectively increase the hydrogen content of black tea residue, and the increase in roasting temperature significantly improves the yield of black tea residue pyrolysis conversion to gasification; compared with black tea residue pyrolysis alone, co-pyrolysis of black tea residue with polypropylene significantly increases the hydrogen and methane content.

[0058] The scope of protection of this invention includes, but is not limited to, the above embodiments. The scope of protection of this invention is defined by the claims. Any substitutions, modifications, or improvements to this technology that are easily conceived by those skilled in the art fall within the scope of protection of this invention.

Claims

1. A method for preparing combustible gas by biomass baking and co-pyrolysis of polypropylene, characterized in that, Black tea residue sieved through a 100-mesh sieve was mixed with distilled water at a ratio of 1:10 and poured into a reaction vessel. The mixture was then wet-baked at 150℃ for 2 hours to obtain a baked sample. The baked sample was mixed with polypropylene at a ratio of 1:1, and approximately 10g was weighed and placed in a quartz boat. The sample weight was recorded as m1. Simultaneously, the weights of gas collecting bottles 1 and 2, as well as all the conduits of the gas collecting device, were weighed and recorded as m2, m3, and m4, respectively. The quartz boat containing the sample was then placed in a tube furnace, with plugs secured on both sides. A nitrogen cylinder and a pyrolysis oil collecting device were connected. Next, the nitrogen cylinder switch was turned on, and the nitrogen flow rate was controlled at 100mL / min. The airtightness of the device was checked, and nitrogen was purged for 10 minutes to remove all air before running the heating device. The initial temperature of the heating device was set to 30℃, the heating rate to 10℃ / min, and the final temperature to 800℃, with a holding time of 2 hours. When the temperature reached 200℃, a pyrolysis gas collecting bag was connected. The gas bag was removed when the temperature began to decrease from 800℃.

2. A method for preparing combustible gas by biomass baking and co-pyrolysis of polypropylene, characterized in that, Black tea residue sieved through a 100-mesh sieve was mixed with distilled water at a ratio of 1:10 and poured into a reaction vessel. The mixture was then wet-roasted at 170℃ for 2 hours to obtain a roasted sample. The roasted sample was mixed with polypropylene at a ratio of 1:1, and approximately 10g was weighed and placed in a quartz boat. The sample weight was recorded as m1. Simultaneously, the weights of gas collecting bottles 1 and 2, as well as all the conduits of the gas collecting device, were weighed and recorded as m2, m3, and m4, respectively. The quartz boat containing the sample was then placed in a tube furnace, with plugs secured on both sides. A nitrogen cylinder and a pyrolysis oil collecting device were connected. Next, the nitrogen cylinder switch was turned on, and the nitrogen flow rate was controlled at 100mL / min. The airtightness of the device was checked, and after purging the air by passing nitrogen for 10 minutes, the heating device was run. The initial temperature of the heating device was set to 30℃, the heating rate to 10℃ / min, and the final temperature to 800℃, with a holding time of 2 hours. When the temperature reached 200℃, a pyrolysis gas collecting bag was connected. The gas bag was removed when the temperature began to decrease from 800℃.

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