Alkylation modified carbon-based solid waste coupling direct combustion method

Abstract

The invention relates to an alkylation modified carbon-based solid waste coupling direct combustion method, which comprises the following steps: firstly, mixing carbon-based solid waste powder and a tetrahydrofuran solvent, pretreating the carbon-based solid waste powder, introducing N2, stirring for 30 minutes, slowly adding a tetrahydroammonium hydroxide aqueous solution, adding 1-bromobutane, and carrying out alkylation reaction, the method comprises the following steps: adding a tetrahydrofuran solvent into carbon-based solid waste powder, grafting an alkyl group on a functional group on the surface of the carbon-based solid waste powder, adding a diluted hydrochloric acid aqueous solution until the mixed solution is neutral, removing the tetrahydrofuran solvent in the alkylation reaction process by using a rotary evaporator so that only the carbon-based solid waste powder and a reaction product thereof remain in the solution, adding a methanol aqueous solution, and carrying out Soxhlet extraction to obtain the carbon-based solid waste powder. The carbon-based solid waste powder is subjected to vacuum drying, the collected carbon-based solid waste powder subjected to surface alkylation modification and primary air are introduced into a hearth through a combustor to be directly combusted, the combustion temperature is 1500 DEG C, the retention time in the furnace is 2 s, and the advantages of efficient combustion and low nitrogen emission can be achieved.

Description

Technical Field

[0001] The invention relates to the technical field of coupled direct combustion of modified carbon-based solid wastes, and in particular to a coupled direct combustion method of modified carbon-based solid wastes by alkylation. Background Art

[0002] With the rapid development of industry, the output of solid waste has also increased dramatically. Carbon-based solid wastes such as gasification fine ash produced in the coal gasification process, coal gangue and oil shale produced in the coal washing process, and industrial solid waste will bring tremendous pressure to environmental protection if not properly handled. At present, they are mainly treated by landfill and stockpiling, which not only pollutes the environment, but also causes energy waste. In order to achieve the dual carbon strategic goals, how to cleanly and efficiently treat carbon-based solid waste is an important issue currently faced.

[0003] Based on the characteristics of high fixed carbon content (30%-50%) of carbon-based solid waste, combustion treatment is one of the important ways to utilize it as a resource. It not only solves the soil pollution problem caused by current storage and landfill, but also realizes the reuse of energy, which is of great significance for achieving dual carbon goals and green development. However, carbon-based solid waste has low volatile matter content, high ash content, and poor surface reactivity, which leads to problems such as difficulty in ignition and burning out, low combustion efficiency and high NOx emissions. Therefore, it brings challenges to the combustion utilization of carbon-based solid waste.

[0004] In order to solve this problem, it is necessary to develop a technology for efficiently burning and treating carbon-based solid waste powder for modification and then burning. The patent "A coal powder preheating burner and combustion method" (patent number CN202211004191, application publication number CN114923169) uses a preheating fuel nozzle to preheat the coal powder at high temperature before burning. However, due to the poor surface chemical reactivity of carbon-based solid waste, there are still defects in improving combustion efficiency through preheating modification. In summary, it is urgent to develop a method and device for coupling direct combustion of carbon-based solid waste using alkylation modification to solve the problems of low combustion efficiency and high NOx emissions such as poor reactivity of carbon-based solid waste, difficulty in ignition, and difficulty in burning out. Summary of the invention

[0005] The present invention aims to solve the problem of poor surface reactivity of carbon-based solid waste, which leads to low combustion efficiency and high NO x In order to solve the emission problem, a method for coupling direct combustion of alkylated modified carbon-based solid waste is provided.

[0006] The technical solution adopted by the present invention to solve its technical problem is:

[0007] A method for coupling direct combustion of carbon-based solid waste by alkylation modification comprises the following steps:

[0008] First, carbon-based solid waste powder and anhydrous tetrahydrofuran solvent were added to reactor 1 at a solid-liquid ratio of 1:30 to pretreat the carbon-based solid waste powder. N2 was introduced into reactor 1 to prevent side reactions during the experiment. Then, the mixture was stirred for 30 minutes, and tetrahydroammonium hydroxide aqueous solution with a solid-liquid ratio of 1:3 was slowly added to reactor 1. The carbon-based solid waste powder was placed under alkaline conditions to remove the OH bonds and COOH bonds on the functional groups such as hydroxyl groups on the surface of the carbon-based solid waste powder. + , 1-bromobutane with a solid-liquid ratio of 1:1 was added to the reactor 1 for alkylation reaction, and the mixed solution was stirred for 72 hours to graft the alkyl group onto the functional group on the surface of the carbon-based solid waste powder, and then a dilute hydrochloric acid aqueous solution was added to the reactor 1 until the mixed solution was neutral to stop the alkylation reaction. After the alkylation reaction in the reactor 1 was completed, the reaction material was transferred to the reactor 2, i.e., the rotary evaporator, and the tetrahydrofuran solvent in the alkylation reaction was removed in the rotary evaporator at 60°C, so that only the carbon-based solid waste powder and its reaction products were left in the solution. After removing the tetrahydrofuran solvent, the reaction materials are directly transferred to reactor 3, and methanol aqueous solution is added to extract the carbon-based solid waste powder from the solvent, and then Soxhlet extraction is performed. The target compound in the carbon-based solid waste powder is dissolved and collected by circulating the solvent to achieve efficient extraction of the carbon-based solid waste powder. The carbon-based solid waste powder is vacuum dried at 100°C for 2 days, and the collected surface alkylated carbon-based solid waste powder and primary air are directly burned through the burner into the furnace. The combustion temperature is about 1500°C, and the residence time in the furnace is 2s.

[0009] As a further technical solution of the present invention, the mass concentration of the tetrahydroammonium hydroxide aqueous solution is 98%.

[0010] As a further technical solution of the present invention, the mass concentration of the dilute hydrochloric acid aqueous solution is 10%.

[0011] As a further technical solution of the present invention, the mass concentration of the methanol aqueous solution is 50%.

[0012] As a further technical solution of the present invention, the reactor 1 is a mixing container, the reactor 2 is a rotary evaporator, and the reactor 3 is a Soxhlet extractor.

[0013] The beneficial effects of the present invention are as follows: the present invention uses 1-bromobutane reagent to alkylate the surface of carbon-based solid waste powder, introduces an organic alkyl group, makes the surface more organic and hydrophobic, reduces the activation energy of combustion, reduces the ignition temperature, improves the combustion efficiency and rate, is conducive to the heterogeneous reduction reaction of NO and coke, and increases the volatile content, is conducive to the homogeneous reduction reaction of NO, reduces NO xThe present invention alkylates the surface of carbon-based solid waste, changes the chemical properties of the surface, and introduces new organic groups with higher reaction activity, thereby achieving the advantages of efficient combustion and low nitrogen emissions. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 A flow chart of a method for coupling direct combustion of carbon-based solid waste using alkylation modification is provided in an embodiment of the present invention.

[0015] Figure 2 This is a graph showing the weight loss changes of carbon-based solid waste and alkylation modification provided in an embodiment of the present invention.

[0016] Figure 3 This is a graph showing the change in weight loss rate of carbon-based solid waste and alkylation modification provided in an embodiment of the present invention.

[0017] Figure 4 This is a graph showing the NO release characteristics of carbon-based solid waste and after alkylation modification provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] See also Figures 1 to 4 , the embodiment of the present invention provides a method for coupling direct combustion of carbon-based solid waste using alkylation modification, comprising the following steps;

[0020] First, carbon-based solid waste powder and anhydrous tetrahydrofuran solvent were added to reactor 1 at a solid-liquid ratio of 1:30 to pretreat the carbon-based solid waste powder. N2 was introduced into reactor 1 to prevent side reactions during the experiment. Then, the mixture was stirred for 30 minutes, and tetrahydroammonium hydroxide aqueous solution with a solid-liquid ratio of 1:3 was slowly added to reactor 1. The carbon-based solid waste powder was placed under alkaline conditions to remove the OH bonds and COOH bonds on the functional groups such as hydroxyl groups on the surface of the carbon-based solid waste powder. +, add 1-bromobutane with a solid-liquid ratio of 1:1 to the reactor 1 for alkylation reaction, and stir the mixed solution for 72 hours to make the alkyl group grafted on the functional group on the surface of the carbon-based solid waste powder. This step is the key to the experiment, thereby affecting the chemical properties of the carbon-based solid waste powder. Then add dilute hydrochloric acid aqueous solution to the reactor 1 until the mixed solution is neutral to stop the alkylation reaction. After the alkylation reaction in the reactor 1 is completed, the reaction material is transferred to the reactor 2, i.e., the rotary evaporator, and the tetrahydrofuran solvent in the alkylation reaction process is removed in the rotary evaporator at 60°C, so that only the carbon-based solid waste powder and its reaction products are left in the solution. After removing the tetrahydrofuran solvent, the reaction The material should be directly transferred to reactor 3, and methanol aqueous solution is added to extract the carbon-based solid waste powder from the solvent, and then Soxhlet extraction is performed. The target compound in the carbon-based solid waste powder is dissolved and collected by the circulating solvent (the circulating solvent usually refers to the solvent used in the extraction process, and a solvent with good solubility for the target product is usually selected. The specific solvent, methanol, has been specified here) to achieve efficient extraction of the carbon-based solid waste powder. The carbon-based solid waste powder is vacuum dried at 100°C for 2 days, and the collected carbon-based solid waste powder modified by surface alkylation and primary air are directly burned in the furnace through a burner. The combustion temperature is about 1500°C, and the residence time in the furnace is 2s.

[0021] In this embodiment, the mass concentration of the tetrahydroammonium hydroxide aqueous solution is 98%, the mass concentration of the dilute hydrochloric acid aqueous solution is 10%, and the mass concentration of the methanol aqueous solution is 50%.

[0022] In this embodiment, the reactor 1 is a mixing container, the reactor 2 is a rotary evaporator, and the reactor 3 is a Soxhlet extractor. The combustion device includes a burner and a furnace.

[0023] Figure 2 It can be seen that the weight loss of carbon-based solid waste after alkylation modification is advanced, and the curve decreases at a faster rate.

[0024] Figure 3 It can be seen that the maximum weight loss peak of the carbon-based solid waste after alkylation modification becomes narrower, the rate is higher than that without alkylation treatment, and the reaction rate is faster.

[0025] Figure 4 By comparing the NO release pattern, we can know that the NO release amount can be obtained by using the integral area. In the figure, the integral area after alkylation modification is 10.62, while the integral area without alkylation treatment is 14.09. It can be concluded that the NO emission of carbon-based solid waste after alkylation treatment is reduced during combustion.

[0026] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0027] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for coupling direct combustion of carbon-based solid waste using alkylation modification, characterized in that: The steps include: First, carbon-based solid waste powder and anhydrous tetrahydrofuran solvent were added to reactor 1 at a solid-liquid ratio of 1:30 to pretreat the carbon-based solid waste powder. N2 was introduced into reactor 1 to prevent side reactions during the experiment. Then, the mixture was stirred for 30 minutes, and tetrahydroammonium hydroxide aqueous solution with a solid-liquid ratio of 1:3 was slowly added to reactor 1. The carbon-based solid waste powder was placed under alkaline conditions to remove the OH bonds and COOH bonds on the functional groups such as hydroxyl groups on the surface of the carbon-based solid waste powder. + , add 1-bromobutane with a solid-liquid ratio of 1:1 to the reactor 1 for alkylation reaction, and stir the mixed solution for 72 hours to graft the alkyl group onto the functional group on the surface of the carbon-based solid waste powder, and then add dilute hydrochloric acid aqueous solution to the reactor 1 until the mixed solution is neutral to stop the alkylation reaction. After the alkylation reaction in the reactor 1 is completed, transfer the reaction material to the reactor 2, i.e., the rotary evaporator, and use the rotary evaporator at 60°C to remove the tetrahydrofuran solvent in the alkylation reaction process, so that only the carbon-based solid waste powder and its reaction products are left in the solution. After removing the tetrahydrofuran solvent, the reaction materials are directly transferred to reactor 3, and methanol aqueous solution is added to extract the carbon-based solid waste powder from the solvent, and then Soxhlet extraction is performed. The target compound in the carbon-based solid waste powder is dissolved and collected by circulating the solvent to achieve efficient extraction of the carbon-based solid waste powder. The carbon-based solid waste powder is vacuum dried at 100°C for 2 days, and the collected carbon-based solid waste powder modified by surface alkylation and primary air are introduced into the furnace through a burner for direct combustion. The combustion temperature is about 1500°C, and the residence time in the furnace is 2s.

2. The method of coupling direct combustion of carbon-based solid waste using alkylation modification according to claim 1 is characterized in that: The mass concentration of the tetrahydroammonium hydroxide aqueous solution is 98%.

3. The method of coupling direct combustion of carbon-based solid waste using alkylation modification according to claim 1 is characterized in that: The mass concentration of the dilute hydrochloric acid aqueous solution is 10%.

4. The method of coupling direct combustion of carbon-based solid waste using alkylation modification according to claim 3 is characterized in that: The mass concentration of the methanol aqueous solution is 50%.

5. The method of coupling direct combustion of carbon-based solid waste using alkylation modification according to claim 1 is characterized in that: The reactor 1 is a mixing container, the reactor 2 is a rotary evaporator, and the reactor 3 is a Soxhlet extractor.

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