A system and method for regenerating carbon black from waste rubber by pyrolysis under molten salt liquid phase conditions.

Abstract

This invention discloses a system and method for regenerating carbon black from waste rubber through pyrolysis under molten salt liquid phase conditions. The system includes a waste rubber pyrolysis unit, a pyrolysis oil condensation unit, and a hydrogen-rich combustible gas collection unit. The waste rubber pyrolysis unit includes a pyrolyzer, a solar collector, and a carbon storage tank. The pyrolysis oil condensation unit includes an air cooler, an oil storage tank, and a water cooler. The hydrogen-rich combustible gas collection unit includes a compressor and a gas storage tank connected in sequence. This invention utilizes solar energy for heating, and the flat-plate solar collector used has high solar energy conversion efficiency. This heating method reduces the use of fuel oil and natural gas in traditional heating methods. The use of this method greatly improves energy conversion efficiency and reduces energy consumption and the use of traditional energy sources.

Description

Technical Field

[0001] This invention relates to the field of waste treatment and resource recycling technology, specifically to a system and method for regenerating carbon black from waste rubber by pyrolysis under molten salt liquid phase conditions. Background Technology

[0002] Waste rubber contains rubber, carbon black, metals, fiber skeleton materials, and rubber processing aids, and has high resource endowment, making it one of the six major solid renewable resources. The pyrolysis of waste rubber produces solid carbon, pyrolysis oil, and pyrolysis gas. Carbon black is an important product of waste rubber pyrolysis, but the current waste rubber pyrolysis technology has the following problems: (1) The waste rubber pyrolysis process is extensive, with low carbon black yield and high energy consumption; (2) The quality of recycled carbon black from waste rubber is poor, and there is a lack of effective carbon black performance enhancement technology; (3) The waste rubber recycled carbon black process has many types of pollutants and large emissions.

[0003] Currently, scholars have conducted extensive research on the problems of low yield and high energy consumption in the pyrolysis of waste rubber to regenerate carbon black. However, current research only focuses on product distribution and cannot fundamentally solve the problems of high energy consumption and low yield in the pyrolysis process. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides a system and method for regenerating carbon black from waste rubber by pyrolysis under molten salt liquid phase conditions, aiming to solve the problems of low yield and high energy consumption in the regenerated carbon black from waste rubber by pyrolysis.

[0005] The technical solution of the present invention is as follows:

[0006] In a first aspect of the present invention, a waste rubber pyrolysis regeneration carbon black system based on molten salt liquid phase conditions is provided, comprising a waste rubber pyrolysis unit, a pyrolysis oil condensation unit and a hydrogen-rich combustible gas collection unit.

[0007] The waste rubber pyrolysis unit includes a pyrolyzer, a solar collector, and a carbon storage tank. The pyrolyzer is equipped with two inlets and an outlet. Waste rubber and molten salt are introduced into the two inlets, respectively. The outlet is connected to the carbon storage tank. The solar collector is installed on the pyrolyzer to provide heat to the pyrolyzer.

[0008] The pyrolysis oil condensation unit includes an air cooler, an oil storage tank, and a water cooler. The inlet of the air cooler is connected to the bottom of the carbon storage tank, and the oil outlets of both the air cooler and the water cooler are connected to the oil storage tank.

[0009] The hydrogen-rich combustible gas collection unit includes a compressor and a gas storage tank connected in sequence, with the inlet of the compressor connected to the gas outlet of the air cooler.

[0010] In some embodiments of the present invention, one feed port of the pyrolyzer is connected in sequence to a screw feeder and a silo, the silo storing molten salt; the other feed port is connected to a vertical feeder, the feed port of the vertical feeder receiving waste rubber.

[0011] In some embodiments of the present invention, the pyrolyzer is a series-parallel rotary kiln pyrolyzer or a series rotary kiln pyrolyzer.

[0012] In some embodiments of the present invention, the internal part of the series-parallel rotary kiln pyrolyzer is provided with a calcination section, in which molten salt and waste rubber are in direct contact and heat is provided by a heat transfer medium heated by a solar collector for pyrolysis.

[0013] In some embodiments of the present invention, an inclined pipe is provided at the tail end of the series-parallel rotary kiln pyrolyzer, and a screen is installed at the bottom of the inclined pipe to recover the molten salt that was not fully utilized in the previous pyrolysis reaction and return it to the calcination section through the bottom return pipe and connecting pipe.

[0014] In some embodiments of the present invention, the series rotary kiln pyrolyzer is provided with a molten salt pipe and a waste rubber pipe for conveying molten salt and waste rubber respectively, and the solar collector heats the molten salt, which then transfers heat to the waste rubber for pyrolysis.

[0015] In some embodiments of the present invention, multiple molten salt tubes are arranged around the circumference of the waste rubber tube.

[0016] In some embodiments of the present invention, the air outlet of the air cooler is connected to a water cooler via a pipe.

[0017] In a second aspect of the invention, a method for operating a waste rubber pyrolysis regenerated carbon black system based on molten salt liquid phase conditions is provided, comprising:

[0018] Molten salt and waste rubber enter the calcination section of the pyrolyzer, and the solar collector provides heat through the heat transfer medium, so that the waste rubber undergoes a pyrolysis reaction in the molten salt liquid phase environment;

[0019] The solid product carbon black after pyrolysis is stored in a carbon storage tank. The pyrolysis gas is condensed in an air cooler and a water cooler. The volatiles containing pyrolysis oil are condensed and then enter an oil storage tank. The pyrolysis gas containing hydrogen-rich combustible gas is pressurized and then enters a gas storage tank.

[0020] In a third aspect of the invention, a method for operating a waste rubber pyrolysis regenerated carbon black system based on molten salt liquid phase conditions is provided, comprising:

[0021] Molten salt and waste rubber are fed into the calcination section of the pyrolysis unit, respectively. The solar collector provides heat through the molten salt to cause the waste rubber to undergo a pyrolysis reaction.

[0022] The solid product carbon black after pyrolysis is stored in a carbon storage tank. The pyrolysis gas is condensed in an air cooler and a water cooler. The volatiles containing pyrolysis oil are condensed and then enter an oil storage tank. The pyrolysis gas containing hydrogen-rich combustible gas is pressurized and then enters a gas storage tank.

[0023] One or more technical solutions of the present invention have the following beneficial effects:

[0024] 1. The waste rubber pyrolysis system of this invention utilizes solar energy for heating, and the flat-plate solar collector employed has a high solar energy conversion efficiency. This heating method reduces the use of fuel oil and natural gas as in traditional heating methods. This approach significantly improves energy conversion efficiency and reduces energy consumption and the use of traditional energy sources.

[0025] 2. This invention uses molten salt as a heat transfer medium, instead of directly utilizing absorbed and fixed solar energy. Directly utilizing absorbed and fixed solar energy could lead to uneven heating during the pyrolysis of waste rubber. Using molten salt for heat transfer not only makes better use of solar energy but also ensures uniform heating of the waste rubber. In a series-parallel rotary kiln pyrolyzer, the molten salt directly mixes and contacts the waste rubber, significantly increasing the porosity and specific surface area of ​​the carbon black, thus enhancing its performance.

[0026] 3. The present invention sets an inclined pipe and a screen of a certain mesh size at the tail end of the series-parallel rotary kiln pyrolyzer to realize the reuse of incompletely reacted molten salt, improve the efficiency of raw material use, and thus save reaction time.

[0027] 4. The waste rubber pyrolysis system of the present invention, by setting up a waste rubber pyrolysis unit, a pyrolysis oil condensation unit and a hydrogen-rich combustible gas collection unit, collects three products—carbon black, bio-oil and hydrogen-rich combustible gas—through multi-stage treatment, which helps to realize the high-value utilization of waste rubber. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the waste rubber pyrolysis and carbon black recycling system under molten salt liquid phase conditions according to the present invention;

[0029] Figure 2 This is a schematic diagram of the waste rubber pyrolysis and carbon black recycling system under molten salt liquid phase conditions of the present invention;

[0030] Figure 3 This is a front view of the series-parallel rotary kiln pyrolyzer in this invention;

[0031] Figure 4 This is a front view of the series-connected rotary kiln pyrolyzer in this invention;

[0032] Figure 5These are the heat transfer processes in two different devices. The symbol "→" indicates the direction of heat transfer, and "→" indicates a reinforcing effect.

[0033] In the diagram: 1. Hopper; 2. Screw feeder; 3. Fixed device; 4. Vertical feeder; 5. Solar collector; 6. Series-parallel rotary kiln pyrolyzer; 7. Carbon storage tank; 8. Air cooler; 9. Oil storage tank; 10. Water cooler; 11. Compressor; 12. Gas storage tank; 13. First screen; 14. Second screen; 15. Series-connected rotary kiln pyrolyzer; 16. Pyrolysis gas pipeline; 17. Heat transfer medium; 18. Molten salt inlet; 19. Waste rubber inlet; 20. Calcination section; 21. Bottom return pipeline; 22. Connecting pipeline. Detailed Implementation

[0034] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0035] Example 1

[0036] In a typical embodiment of the present invention, a waste rubber pyrolysis and carbon black regeneration system based on molten salt liquid phase conditions is proposed, such as... Figure 1 and Figure 2 As shown, it includes a waste rubber pyrolysis unit, a pyrolysis oil condensation unit, and a hydrogen-rich combustible gas collection unit;

[0037] The waste rubber pyrolysis unit includes a pyrolyzer, a solar collector 5, and a carbon storage tank 7. The pyrolyzer is provided with two inlets and an outlet. Waste rubber and molten salt are respectively fed into the two inlets, and the outlet is connected to the carbon storage tank 7. The solar collector 5 is installed on the pyrolyzer to provide heat to the pyrolyzer.

[0038] The pyrolysis oil condensation unit includes an air cooler 8, an oil storage tank 9, and a water cooler 10. The inlet of the air cooler 8 is connected to the bottom of the carbon storage tank 7, and the oil outlets of both the air cooler 8 and the water cooler 10 are connected to the oil storage tank 9.

[0039] The hydrogen-rich combustible gas collection unit includes a compressor 11 and a gas storage tank 12 connected in sequence. The inlet of the compressor 11 is connected to the gas outlet of the air cooler 8.

[0040] In this embodiment, one feed port of the pyrolyzer is connected in sequence to the screw feeder 2 and the silo 1, and the silo 1 stores molten salt; the other feed port is connected to the vertical feeder 4, and the feed port of the vertical feeder 4 is into the waste rubber.

[0041] Molten salt stored in silo 1 is fed into the pyrolyzer by screw feeder 2. Waste rubber enters the pyrolyzer for pyrolysis through vertical feeder 4. The outlet of the rotary kiln pyrolyzer is connected to carbon storage tank 7 and pyrolysis gas pipeline 16. The solid product carbon black after pyrolysis enters carbon storage tank 7 for storage. A first screen 13 is installed in carbon storage tank 7, and the solid product carbon black is located on the first screen 13. Pyrolysis gas containing volatiles such as pyrolysis oil enters the pyrolysis oil condensation unit through the bottom pipeline of carbon storage tank.

[0042] In this embodiment, the pyrolyzer is a series-parallel rotary kiln pyrolyzer 6 or a series rotary kiln pyrolyzer 15, and the pyrolyzer is fixed on the fixing device 3.

[0043] like Figure 1 and Figure 3 As shown, the internal structure of the series-parallel rotary kiln pyrolyzer 6 is provided with a calcination section 20. In the calcination section of the rotary kiln, molten salt and waste rubber are in direct contact, and heat is provided by the heat transfer medium 17 heated by the solar collector 5 for pyrolysis.

[0044] Furthermore, an inclined pipe is provided at the tail end of the series-parallel rotary kiln pyrolyzer 6, and a second screen 14 is installed at the bottom of the inclined pipe to recover the molten salt that was not fully utilized in the previous pyrolysis reaction and return it to the calcination section 20 through the bottom return pipe and connecting pipe.

[0045] Specifically, the inclined pipe connects to the pyrolysis gas pipe 16. Carbon black, pyrolysis oil, pyrolysis gas, and other products enter the product processing device along the pyrolysis gas pipe 16. A screen of a certain mesh size is installed at the bottom of the inclined pipe to recover the molten salt that was not fully utilized in the previous pyrolysis reaction and return it to the kiln head of the pyrolyzer through the bottom return pipe 21. A spiral riser is installed in the connecting pipe 22 to transport the molten salt in the bottom return pipe 21 to the calcination section 20 of the rotary kiln for reuse. The surface of the pipe in the calcination section of the rotary kiln is covered with a heat transfer medium 17. The solar collector 5 converts the absorbed solar energy into heat energy and transfers it to the heat transfer medium 17. The converted heat energy is then transferred to the calcination section 20 of the rotary kiln for the pyrolysis reaction of waste rubber.

[0046] like Figure 2 and Figure 4 As shown, the series-connected rotary kiln pyrolyzer 15 is equipped with molten salt pipes and waste rubber pipes to transport molten salt and waste rubber respectively. The solar collector 5 heats the molten salt, which then transfers heat to the waste rubber for pyrolysis. Furthermore, multiple molten salt pipes are arranged around the circumference of the waste rubber pipes.

[0047] Specifically, the molten salt has two inlets. A solar collector 5 is attached to the outside of the molten salt transport pipeline. The waste rubber inlet 19 is directly connected to the calcination section 20 of the rotary kiln. After receiving the heat energy from the solar collector 5, the molten salt in the molten salt transport pipeline directly transfers the heat energy to the waste rubber in the calcination section 20 of the rotary kiln. This device is simple in design. The molten salt and waste rubber do not have direct contact. Therefore, the performance of the carbon black recycled from the pyrolysis of waste rubber cannot be improved. The performance improvement work of carbon black still needs to be carried out in the future. Molten salt is still consumed during the heat transfer process. Therefore, the molten salt inlet 18 needs to be continuously replenished.

[0048] In this embodiment, the inlet of the air cooler 8 of the pyrolysis oil condensation unit is connected to the bottom pipe of the carbon storage tank 7, and the gas outlet is connected to the water cooler 10. The water cooler 10 introduces circulating cooling water from the outside to condense the heavy components and a small amount of light components of the pyrolysis oil after pyrolysis. The gas outlet of the water cooler 10 is connected to the hydrogen-rich combustible gas collection section. The oil outlets at the bottom of the air cooler 8 and the water cooler 10 are connected to the oil storage tank 9 for the collection and storage of pyrolysis oil for later processing. By connecting the gas outlet of the air cooler 8 to the water cooler 10 through a pipe, the water cooler 10 is used to further condense the pyrolysis oil that has not been completely condensed by the pyrolysis gas.

[0049] The compressor 11 of the hydrogen-rich combustible gas collection unit is used to pressurize the hydrogen-rich combustible gas at the outlet of the pyrolysis oil condenser. The inlet of the gas storage tank 12 is connected to the compressor 11 for collecting the hydrogen-rich combustible gas.

[0050] The working principle of the waste rubber pyrolysis carbon black recycling system based on molten salt liquid phase conditions provided in this embodiment is as follows:

[0051] like Figure 1-5 As shown, the screw feeder 2 and the vertical feeder 4 respectively feed waste rubber and molten salt into the rotary kiln pyrolyzer. The solid product carbon black after pyrolysis is stored in the carbon storage tank 7, and the pyrolysis gas containing volatiles such as pyrolysis oil is discharged from the rotary kiln pyrolyzer through the pipeline. The pyrolyzer absorbs solar radiation through the solar collector 5, generates heat energy, and transfers it to the rotary kiln pyrolyzer through the heat transfer medium. The transferred heat energy is absorbed by the molten salt, providing energy for the process of regenerating carbon black from waste rubber through pyrolysis. Among them, the kiln tail section of the series-parallel rotary kiln pyrolyzer 6 is equipped with a screen of a certain mesh size to screen out the incompletely reacted molten salt, which is returned to the inlet of the rotary kiln pyrolyzer through the screw feeder. The incompletely reacted molten salt can be reused.

[0052] The pyrolysis gas containing volatile components such as pyrolysis oil enters the air cooler 8, which is continuously circulated by a cooling fan to condense the volatile components containing pyrolysis oil after the waste rubber is pyrolyzed; the outlet of the water cooler 10 is connected to a hydrogen-rich combustible gas collection unit, and circulating condensate is introduced outside the condenser tubes of the water cooler to condense most of the components of the pyrolysis oil; the oil storage tank 9 is used for the collection and storage of pyrolysis oil for later processing and utilization.

[0053] The compressor 11 of the hydrogen-rich combustible gas collection unit is used to pressurize the pyrolysis gas containing a large amount of hydrogen-rich combustible gas generated by the waste rubber pyrolysis section; the inlet of the gas storage tank 12 is connected to the compressor 11 and is used to collect the pyrolysis gas, which is mainly composed of hydrogen-rich combustible gas.

[0054] In this embodiment, the screw feeder 2 is made of high-temperature resistant steel and is used to transport molten salt in the silo; the vertical feeder 4 is used to transport waste rubber. During the feeding process, the conveying pipes of the screw feeder and the vertical feeder are not connected. In the series-parallel rotary kiln pyrolyzer 6, waste rubber enters from inlet A and molten salt enters from inlet B; in the series rotary kiln pyrolyzer 15, waste rubber enters from inlet B and molten salt enters from inlets A and C.

[0055] As a further preferred embodiment, the solar collector 5 in the pyrolysis device is a flat plate type with a large heat absorption area. When the flat plate solar collector is working, solar radiation passes through the transparent cover plate and shines on the heat absorber with an adsorption layer on its surface. Most of the solar radiation is absorbed by the heat absorber and converted into heat energy, which is then transferred to the rotary kiln pyrolyzer through the heat transfer medium. The internal structure of the rotary kiln pyrolyzer is divided into two types: series and series-parallel.

[0056] Inside the series-parallel rotary kiln pyrolyzer 6, a spiral riser is installed between the B feed port and the A feed port. This riser transports the molten salt entering from the B feed port and the molten salt that was not fully utilized in the previous reaction to the calcination section of the rotary kiln cylinder, allowing the waste rubber to undergo pyrolysis in the molten salt liquid phase environment. At the end of the rotary kiln pyrolyzer, an inclined pipe and a screen of a certain mesh size are installed. The pyrolysis product carbon black enters the carbon storage tank from the end of the rotary kiln pyrolyzer along the inclined pipe, while the unreacted molten salt is screened through the screen and then returned to the B feed port through the bottom pipe.

[0057] Inside the series-connected rotary kiln pyrolyzer 15, the middle B inlet is the waste rubber inlet 19, and the upper and lower A and C inlets are molten salt inlets. The molten salt absorbs the solar energy fixed by the solar collector and transfers the heat energy to the waste rubber that moves along the pyrolysis pipe towards the end of the rotary kiln pyrolyzer under the push of the screw, causing the waste rubber to undergo a pyrolysis reaction. The molten salt will be consumed in the process of absorbing and transferring heat energy, so the A and C inlets need to be continuously supplied with molten salt.

[0058] Example 2

[0059] In a typical embodiment of the present invention, a working method for a waste rubber pyrolysis and carbon black regeneration system based on molten salt liquid phase conditions is provided, which, for a rotary kiln pyrolyzer connected in series and parallel, includes:

[0060] Molten salt and waste rubber enter the calcination section of the pyrolyzer, and the solar collector provides heat through the heat transfer medium, so that the waste rubber undergoes a pyrolysis reaction in the molten salt liquid phase environment;

[0061] The solid product carbon black after pyrolysis is stored in a carbon storage tank. The pyrolysis gas is condensed in an air cooler and a water cooler. The volatiles containing pyrolysis oil are condensed and then enter an oil storage tank. The pyrolysis gas containing hydrogen-rich combustible gas is pressurized and then enters a gas storage tank.

[0062] Specifically, the molten salt in the silo is mixed with waste rubber that enters the rotary kiln pyrolyzer via a screw feeder and a vertical feeder. Under an anaerobic environment, the mixture is pyrolyzed to produce carbon black, pyrolysis oil, and pyrolysis gas. Driven by the screw, the pyrolysis products move towards the end of the rotary kiln pyrolyzer. The incompletely reacted molten salt is returned to the kiln head section of the rotary kiln for reuse through a screen. The carbon black is stored in a carbon storage tank, and the volatiles containing pyrolysis oil are discharged from the bottom pipe of the carbon storage tank.

[0063] The volatile components are mainly pyrolysis oil and olefins such as hydrogen, methane, and ethylene. After pyrolysis, the volatile components are condensed twice by air cooler and water cooler. The heavy and light components of the pyrolysis oil are condensed separately and stored in oil storage tanks.

[0064] The remaining hydrogen-rich combustible gas after condensation is pressurized by a compressor and then stored in a gas storage tank.

[0065] Example 3

[0066] In a typical embodiment of the present invention, a working method for a waste rubber pyrolysis and carbon black regeneration system based on molten salt liquid phase conditions is provided, which, for a series rotary kiln pyrolyzer, includes:

[0067] Molten salt and waste rubber are fed into the calcination section of the pyrolysis unit, respectively. The solar collector provides heat through the molten salt to cause the waste rubber to undergo a pyrolysis reaction.

[0068] The solid product carbon black after pyrolysis is stored in a carbon storage tank. The pyrolysis gas is condensed in an air cooler and a water cooler. The volatiles containing pyrolysis oil are condensed and then enter an oil storage tank. The pyrolysis gas containing hydrogen-rich combustible gas is pressurized and then enters a gas storage tank.

[0069] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A system for regenerating carbon black from waste rubber by pyrolysis under molten salt liquid phase conditions, characterized in that, It includes a waste rubber pyrolysis unit, a pyrolysis oil condensation unit, and a hydrogen-rich combustible gas collection unit; The waste rubber pyrolysis unit includes a pyrolyzer, a solar collector, and a carbon storage tank. The pyrolyzer is equipped with two inlets and an outlet. Waste rubber and molten salt are introduced into the two inlets, respectively. The outlet is connected to the carbon storage tank. The solar collector is installed on the pyrolyzer to provide heat to the pyrolyzer. The pyrolysis oil condensation unit includes an air cooler, an oil storage tank, and a water cooler. The inlet of the air cooler is connected to the bottom of the carbon storage tank, and the oil outlets of both the air cooler and the water cooler are connected to the oil storage tank. The hydrogen-rich combustible gas collection unit includes a compressor and a gas storage tank connected in sequence, and the inlet of the compressor is connected to the gas outlet of the water cooler. The pyrolyzer is a series-parallel rotary kiln pyrolyzer; The series-parallel rotary kiln pyrolyzer is equipped with a calcination section inside, where molten salt and waste rubber come into direct contact and heat is provided by the heat transfer medium heated by the solar collector for pyrolysis. The tail end of the series-parallel rotary kiln pyrolyzer is equipped with an inclined pipe. A screen is installed at the bottom of the inclined pipe to recover the molten salt that is not fully utilized in the pyrolysis reaction and return it to the calcination section through the bottom return pipe and connecting pipe.

2. The waste rubber pyrolysis regeneration carbon black system based on molten salt liquid phase conditions as described in claim 1, characterized in that, One feed port on the pyrolyzer is connected in sequence to a screw feeder and a silo, the silo containing molten salt; the other feed port is connected to a vertical feeder, the feed port of which receives waste rubber.

3. The waste rubber pyrolysis regeneration carbon black system based on molten salt liquid phase conditions as described in claim 1, characterized in that, The air outlet of the air cooler is connected to the water cooler via a pipe.

4. A method for operating a waste rubber pyrolysis regenerated carbon black system based on molten salt liquid phase conditions as described in any one of claims 1-3, characterized in that, include: Molten salt and waste rubber enter the calcination section of the pyrolyzer, and the solar collector provides heat through the heat transfer medium, so that the waste rubber undergoes a pyrolysis reaction in the molten salt liquid phase environment; The solid product carbon black after pyrolysis is stored in a carbon storage tank. The pyrolysis gas is condensed in an air cooler and a water cooler. The volatiles containing pyrolysis oil are condensed and then enter an oil storage tank. The pyrolysis gas containing hydrogen-rich combustible gas is pressurized and then enters a gas storage tank.

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