Device and method for obtaining near-primary pyrolysis product of carbon-based fuel

Abstract

The invention discloses a device and a method for obtaining near-primary pyrolysis products of carbon-based fuel, and relates to a device and a method for obtaining pyrolysis products, and an internal component with pores or channels is arranged in a reactor of the device. And the pressure of the reactor is adjusted to be close to an absolute vacuum state through the pressure regulation and control device. The solid fuel is heated by an external high-temperature area in the reactor to be pyrolyzed, and a pyrolysis product radially penetrates through a central low-temperature solid fuel bed layer. Along with the proceeding of the heat transfer process, when the bed temperature exceeds the boiling point of the condensed tar, the adsorbed tar is desorbed again. Due to the fact that the reactor is in the nearly absolute vacuum state, the boiling points of almost all tar are lower than the cracking temperature of the tar, in the bed layer heating process, the condensed and adsorbed tar is almost not cracked, the nearly primary pyrolysis product information of the carbon-based fuel can be accurately obtained, and a basis is provided for detailed analysis of the nearly primary tar.

Description

Technical Field

[0001] The present invention relates to a device and method for pyrolysis products, and particularly to a device and method for obtaining near-primary pyrolysis products of carbon-based fuels. Background Art

[0002] Hydrocarbon solid fuels, such as coal, biomass, oil shale, and municipal solid waste, are currently mainly utilized through direct combustion and gasification. However, neither of these two methods can efficiently utilize the high-value volatile components in solid fuels. The application of pyrolysis technology can, under relatively mild conditions, release volatile components rich in hydrogen in the form of high-quality liquid and gaseous products, while producing char rich in carbon. Through pyrolysis tar, high-value aromatic chemicals can be extracted, or it can be converted into fuel oil through a hydrogenation process, which to a certain extent helps alleviate the shortage of oil product supply in China. Pyrolysis gas has a relatively high calorific value. After purification, it can be directly used as city gas, or used for power generation and heating, or even for synthesizing chemical products such as ammonia and methanol. In addition, char can also be used as a fuel or gasification raw material. Therefore, the solid fuel pyrolysis technology can significantly improve the utilization efficiency and value of solid fuels.

[0003] The pyrolysis reaction follows a two-step free radical reaction mechanism: primary pyrolysis (particle reaction) determines the total extraction rate of volatile components, while secondary reaction (volatile component reaction) determines the final distribution of oil and gas. Accurately analyzing the characteristics of primary pyrolysis products will be the cornerstone for obtaining the theoretical upper limit of pyrolysis tar yield. However, since secondary reactions cannot be completely avoided, it is theoretically impossible to accurately analyze primary pyrolysis products. Therefore, domestic and foreign scholars are committed to obtaining near-primary pyrolysis products.

[0004] The evaluation criterion for whether pyrolysis products belong to primary pyrolysis products is that the degree of secondary reaction in this process is low enough. The less the degree of secondary reaction, the closer it is to primary pyrolysis products. In recent years, the internal component regulated pyrolysis technology significantly suppresses the secondary reaction of tar cracking by "co-directionally" matching the gas-phase product flow and heat flow. However, this technology still has selective cracking of heavy tar. The fundamental reason is that when pyrolysis volatiles pass through a low-temperature particle bed layer, pyrolysis oil is condensed and intercepted. As heat transfer progresses, the temperature of the particle bed layer gradually increases; the boiling point of light tar is lower than its cracking temperature, so it evaporates and leaves the bed layer before reaching the reaction temperature; the boiling point of most heavy tar is higher than its cracking temperature, so significant cracking reactions occur when it leaves the surface of the bed particles. Therefore, the key to eliminating the secondary reaction of this technology lies in reducing the boiling points of all components of tar below the cracking temperature. The cracking temperature is difficult to regulate, while applying negative pressure can lower the boiling point. Therefore, the pyrolysis technology regulated by internal components under high vacuum can almost completely eliminate the secondary reaction of pyrolysis volatiles, and thus become an analysis method for near-primary pyrolysis products. Summary of the Invention

[0005] The object of the present invention is to provide a device and a method for obtaining near-primary pyrolysis products of carbon-based fuels. The internal component reactor of the present invention can significantly reduce secondary reactions during pyrolysis, thereby increasing the tar yield. The present invention utilizes conditions close to absolute vacuum to lower the boiling points of heavy components to below the cracking temperature, so that all components of the tar evaporate directly without undergoing the cracking process, and finally near-primary pyrolysis products are obtained.

[0006] The object of the present invention is achieved by the following technical solutions: A device for obtaining near-primary pyrolysis products, the device includes a heating furnace, a reactor, a tar condensation and recovery unit, and a vacuum pump. The heating furnace is placed outside the reactor to provide heat for the reactor. A gas collecting pipe is arranged in the center of the reactor, and the gas collecting pipe is provided with pores or channels for the volatiles to pass through; a solid fuel channel is formed between the gas collecting pipe and the outer wall of the reactor, and the inside of the gas collecting pipe is a volatiles escape channel. The volatiles escape channel is successively connected to the tar condensation and recovery unit and the vacuum pump.

[0007] The material of the gas collecting pipe is preferably 310s, and the gas collecting pipe is provided with uniform pores and channels to form the only channel for the gas-phase products to escape.

[0008] The entire reaction system is carried out under conditions close to absolute vacuum.

[0009] The heat of the reactor is provided by the heating furnace (1), and the temperature distribution of the reactor (2) gradually decreases from the outside to the inside.

[0010] A method for obtaining near-primary pyrolysis products, the method includes the following steps: Solid fuel is pyrolyzed by heating in the external high-temperature region of the reactor, and the pyrolysis products radially pass through the central low-temperature solid fuel bed, where the pyrolysis tar is adsorbed and condensed by the low-temperature particles.

[0011] As the heat transfer process proceeds, when the bed temperature exceeds the boiling point of the condensed tar, the adsorbed tar is desorbed again. Since the reactor is in a state close to absolute vacuum, the boiling points of almost all tars are lower than their cracking temperatures. Therefore, during the heating process of the bed, the condensed and adsorbed tar hardly undergoes cracking. The gas-phase products escaping through the gas collecting pipe are collected by the tar condensation and recovery unit for tar.

[0012] The pyrolysis pressure is close to absolute vacuum. Preferably, the absolute pressure is 0 - 3000 Pa, so that the boiling points of all tars are lower than their cracking temperatures.

[0013] The advantages and effects of the present invention are: The present invention provides a method for preparing near-primary tar, and the tar cracking rate of this method has been proven to be negligible. As Figure 2As shown, the yields of the feedstock oil under atmospheric pressure and near absolute vacuum are completely different. The oil yield under near vacuum can reach over 95%, while it is only 74% under atmospheric pressure. This shows from the oil yield that the cracking rate of tar in the feedstock oil under near absolute vacuum conditions can be neglected. Figure 3 The GC-MS spectra of the feedstock oil, the oil collected under near absolute vacuum conditions, and the oil collected under atmospheric pressure conditions were measured by GC-MS. From the peak intensities of the spectra, it can be seen that the spectrum of the oil under near absolute vacuum conditions is basically no different from that of the feedstock oil, indicating that their compositions are almost the same; while under atmospheric pressure conditions, it is obvious that the peak intensity decreases and even peaks disappear at the end of the spectrum, which shows that the cracking of the feedstock oil under atmospheric pressure is very obvious. In addition, the primary tar obtained by other methods is in milligram level, which restricts its characterization and analysis. The present invention provides a method for the macroscale preparation of near-primary tar, providing a basis for the detailed analysis of near-primary tar. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic diagram of a device for obtaining primary pyrolysis products by pyrolyzing a carbon-based fuel according to the present invention; Figure 2 It is a diagram for proving the effect of the present invention; Figure 3 It is a diagram for proving the GC-MS effect of the present invention.

[0015] Components in the figure: 1. Heating furnace; 2. Reactor, where 2-1. Solid particle bed layer, 2-2. Internal component, 2-3. Volatile component channel. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0016] The present invention will be described in detail below with reference to the embodiments shown in the drawings.

[0017] The device of the present invention includes a heating furnace and a reactor. An internal component is arranged on the reactor, and pores or channels for the passage of volatile components are provided on the internal component. A solid particle bed layer is formed between the internal component and the outer wall of the reactor, and the inside of the internal component is a volatile component channel. The volatile component channel is connected to a tar separation and recovery unit and a gas purification unit to collect near-primary pyrolysis products; the entire reaction system is provided with a near-vacuum state by a vacuum pump. The heat of the reactor is provided by the heating furnace, and the temperature distribution of the reactor gradually decreases from the outside to the inside. Embodiment

[0018] As Figure 1As shown in the figure, a device for obtaining primary pyrolysis products by pyrolyzing carbon-based fuels includes a heating furnace 1 and a reactor 2. A gas collecting pipe 2-2 is provided on the inner reactor 2. The gas collecting pipe 2-2 is provided with pores or channels for the volatiles to pass through, so that the volatiles generated by pyrolysis flow radially. A solid particle bed layer 2-1 is formed between the gas collecting pipe 2-2 and the outer wall of the reactor 2. There is no gas outlet on the solid particle bed layer 2-1, so that the pyrolysis volatiles can only be discharged through the pores or channels on the gas collecting pipe member 2-2.

[0019] The inside of the gas collecting pipe 2-2 is a volatile component channel 2-3. The volatile component channel 2-3 is connected to a tar separation and recovery unit and a gas purification unit to collect near-primary pyrolysis products; the entire reaction system is provided with a near-absolute vacuum state by a vacuum pump.

[0020] The heat of the reactor 2 is provided by the heating furnace 1, and the temperature distribution of the reactor 2 gradually decreases from the outside to the inside.

[0021] The method for obtaining primary pyrolysis products based on the above-mentioned carbon-based fuel pyrolysis of the present invention includes the following steps: 1. The hydrocarbon fuel is pyrolyzed in the reactor through the heating furnace. The volatiles generated by pyrolysis flow radially through the central low-temperature solid fuel layer. Since the temperature inside is lower than that outside, the secondary reaction of the volatiles generated by pyrolysis is avoided. At the same time, the inner fuel layer can be used as a filtering medium, so that the dust content of the volatiles is greatly reduced. At the same time, when the volatiles pass through the inner low-temperature fuel layer, heavy tar is adsorbed and condensed on the surface of the low-temperature particles, and light oil and pyrolysis gas are discharged from the reactor through the internal component 2-2.

[0022] 2 As the temperature of the central solid particle bed layer gradually increases, since the boiling point of the adsorbed heavy tar is higher than its cracking temperature, cracking will occur under normal pressure. In order to obtain near-primary pyrolysis products, through the near-vacuum condition provided by the vacuum pump, the boiling point of the adsorbed heavy tar is lower than its cracking temperature, so that the heavy tar adsorbed on the surface of the low-temperature particles evaporates, avoiding its cracking.

[0023] 3 The light and heavy components escaping from the central channel jointly enter the tar separation and recovery unit and the gas purification unit.

[0024] The primary volatiles generated by the pyrolysis of the hydrocarbon fuel, the heavy components are condensed and adsorbed on the surface of the low-temperature bed particles, while the light components and pyrolysis gas are directly discharged through the gas channel of the central internal component.

[0025] Under near-vacuum conditions, the boiling point of the heavy components decreases and is lower than its cracking temperature. Therefore, the heavy components evaporate and escape from the reactor through the gas channel of the internal component without cracking.

[0026] It should be noted that all such substitutions and modifications are obvious to those skilled in the art and are all considered to be included in the present invention. The method and application of the present invention have been described by means of preferred embodiments. It is obvious that relevant personnel can make changes or appropriate alterations and combinations to the methods and applications described herein without departing from the content, spirit and scope of the present invention to implement and apply the technology of the present invention, but none of them will depart from the scope and basic spirit of the present invention as defined in the claims.

Claims

1. An apparatus for obtaining near-primary pyrolysis products of carbon-based fuels, characterized in that , The device includes a heating furnace (1), a reactor (2), a tar condensation and recovery unit (3), and a vacuum pump (4); the heating furnace (1) is placed outside the reactor (2) to provide heat for the reactor (2); a gas collecting pipe (2-2) is arranged in the center of the reactor (2), and the gas collecting pipe is provided with pores or channels for the volatile matter to pass through; a solid fuel channel (2-1) is formed between the gas collecting pipe (2-2) and the outer wall of the reactor (2), and the inside of the gas collecting pipe (2-2) is a volatile matter escape channel (2-3); the volatile matter escape channel (2-3) is successively connected to the tar condensation and recovery unit (3) and the vacuum pump (4).

2. The device for obtaining near-primary pyrolysis products of carbon-based fuels according to claim 1, characterized in that, , The material of the gas collecting pipe is preferably 310s, and the gas collecting pipe is provided with uniform pores and channels to form the only channel for the gas-phase product to escape.

3. The device for obtaining near-primary pyrolysis products of carbon-based fuels according to claim 1, characterized in that , The entire reaction system is carried out under vacuum conditions.

4. The device for obtaining near-primary pyrolysis products of carbon-based fuels according to claim 1, characterized in that , The heat of the reactor (2) is provided by the heating furnace (1), and the temperature distribution of the reactor (2) gradually decreases from the outside to the inside.

5. A method for obtaining near-primary pyrolysis products of carbon-based fuels, characterized in that , The method includes the following steps: 1) The solid fuel is pyrolyzed by being heated in the reactor in the external high-temperature area, and the pyrolysis products radially pass through the solid fuel bed layer with a low temperature in the center, and the pyrolysis tar is adsorbed and condensed by the low-temperature particles. 2) As the heat transfer process proceeds, when the bed temperature exceeds the boiling point of the condensed tar, the adsorbed tar is desorbed again; since the reactor is in a state close to absolute vacuum, the boiling points of almost all tar are lower than their cracking temperatures, so during the bed temperature rise process, the condensed and adsorbed tar hardly cracks. 3) The gas-phase products escaping through the gas collecting pipe are collected by the tar condensation and recovery unit.

6. The method for obtaining near-primary pyrolysis products of carbon-based fuels according to claim 5, wherein , The solid fuel includes but is not limited to coal, oil shale, and biomass.

7. A method for obtaining near-primary pyrolysis products of carbon-based fuels according to claim 5, characterized in that , The pyrolysis pressure is vacuum, and the preferred pressure is 0-3000 Pa, so that the boiling points of all tar are lower than their cracking temperatures.

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