• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    The present invention discloses an energy—saving, water—saving and environment—friendly method for preparing furfural, specifically a method for heating reaction materials and stripping furfural with high—temperature flue gas of a boiler. The method of the present invention uses residual heat of the high—temperature flue gas of a boiler as a heat source of a reactor. Meanwhile, dust and sulfur trioxide in the flue gas are trapped in the reactor, and the flue gas is purified. The sulfur trioxide trapped in the reactor reacts With water and is converted into dilute sulfuric acid, so that a formation reaction of furfural in the reactor is enhanced. The heat load of a condenser of mixed gas of flue gas and furfural is greatly reduced, the moisture content of a crude furfural product stripped by the flue gas is low, the subsequent refining cost is greatly reduced, and wastewater generated by a refining process is greatly reduced.
    公开号:NL2024450A
    申请号:NL2024450
    申请日:2019-12-13
    公开日:2020-01-29
    发明作者:Wang Jun；Chen Mingqiang；Yu Yiming；Yang Zhonglian；Li Fuhu；Zhang Ye；Cheng Dongchao；Jiang Qing；Song Gengzhe；Liu Shaomin；Wang Yishuang
    申请人:Univ Anhui Sci & Technology；
    IPC主号:
    专利说明:

    BACKGROUND
    Technical Field
    The present invention relates to a method for preparing furfural, and in particular relates to a method for heating reaction materials and stripping furfural by high-temperature flue gas of a boiler.
    Related Art
    Furfural is an important chemical raw material. At present, high-pressure water vapor is used in industrial production to heat reactant and strip the furfural. The pressure of water vapor used is 0.8 MPa-1 MPa, and the reaction temperature is about 180°C. There are several drawbacks in the above process as follows. First, the consumption of water vapor is large, and the accompanying energy consumption is also large. Second, furfural residue produced by the process is used as steam boiler fuel. Although the problem of solid waste treatment is partially solved, flue gas produced by combustion of the furfural residue contains smoke dust and sulfur trioxide (produced when a sulfuric acid catalyst remaining in the furfural residue is thermally decomposed). Direct emission of the flue gas can pollute the atmosphere, while dedusting and desulfurization require high costs. Third, the temperature of the exhausted flue gas is very high, and a large amount of sensible heat of the flue gas is wasted. Fourth, the total amount of an aqueous phase of crude furfural obtained by stripping of water vapor is large. Since the content of furfural in the aqueous phase is very low, recovery of the furfural from the aqueous phase by distillation is high in energy consumption and produces more wastewater.
    SUMMARY
    To avoid the above problems existing in the prior art, the present invention provides a method for heating reaction materials and stripping furfural by high-temperature flue gas of a boiler, thereby overcoming the shortcomings of large water vapor consumption, high energy consumption, air pollution caused by flue gas emission or high cost of flue gas purification, and the like of the prior art.
    The technical solution adopted by the present invention to solve the technical problem thereof is listed as follows.
    The method of the present invention is characterized in that high-temperature flue gas of a boiler is used as a heating medium of reactant as well as a stripping medium of product furfural. The specific process scheme is shown in Fig. 1. The method of the present invention operates in a process as follows.
    High-temperature flue gas SI enters a reactor from the bottom of the reactor 1, and dust in the flue gas is trapped in solid reactant in the reactor. The temperature of the high-temperature flue gas can be adjusted at 150°C-4()0°C. The high-temperature flue gas transfers heat to the reactant and heats the reactant to 170°C-25()°C. The materials react under the catalysis of a sulfuric acid catalyst to form mixed gas S2 of flue gas and furfural formed by mixing of the furfural and the flue gas, and the mixed gas enters a condenser 2 to form a gas phase and a liquid phases. The gas phase low-temperature flue gas S3 is introduced into a furnace of the boiler, in which trace organic matter is combusted and converted into carbon dioxide and water. The liquid phase enters a liquid separation tower to form an aqueous phase S6 and an aldehyde phase S7, and the aqueous phase S6 and the aldehyde phase S7 enter the subsequent refining section to obtain high-purity furfural.
    The pressure of the high-temperature flue gas SI is controlled to be greater than the sum of material resistance and flue gas duct resistance in the reactor to ensure that the high-temperature flue gas can enter the reactor. Cooling capacity provided by the condenser 2 is sufficient to ensure that the furfural mixed gas S2 is cooled to 97°C or below to ensure that an aldehyde water azeotrope having an azeotropic point of 97.9°C is condensed into the liquid phase S4. Meanwhile, that the amount of furfural contained in the low-temperature flue gas S3 is at a very low level, that is, less than 2% of the total mass of the formed furfural is ensured.
    Compared with the prior art, the beneficial effects of the present invention are embodied as follows.
    1. Compared with a traditional water vapor stripping method, the high-temperature flue gas of a steam boiler of furfural plants is used to heat the reactants and strip the furfural, so that the purpose of energy saving and water saving is achieved. At the same time, sulfur trioxide in the flue gas is recovered as a sulfuric acid catalyst to enhance the catalytic effect. The dust in the flue gas is removed by being adsorbed on the surface of the reactant. The organic phase ratio in crude furfural is increased, and the aqueous phase is reduced, so that the energy consumption for recovering furfural is reduced, the produced wastewater is reduced, and the cost of the subsequent refining process is greatly reduced.
    2. Compared with the traditional water vapor stripping method, when the reactant is heated by the flue gas and the furfural is stripped, the pressure of the flue gas can be controlled at a low level, as long as the pressure of the flue gas can overcome the reactor resistance and the duct resistance and enter the reactor. It is not necessary to control the pressure to be 0.8 MPa or higher, so that the steam temperature can reach 180°C, like water vapor stripping. The temperature of the flue gas is generated by the combustion of the furnace, so that high temperatures of 180°C or higher can be achieved without high pressure. Therefore, the reactor is subjected to less pressure and production is safer. Moreover, when the flue gas is used for heating, the reaction temperature can be appropriately increased, which is more favorable for increasing the yield of furfural.
    3. Compared with the traditional water vapor stripping method, when the reactant is heated by the flue gas and the furfural is stripped, since the furfural is mostly condensed in the form of an aldehyde phase during condensation, and since the atmospheric boiling point of the furfural is 161.7°C, most of the furfural is condensed when the mixed gas of the flue gas and the furfural is cooled to 161.7°C or lower. However, in the traditional water vapor stripping method, in the condensation process, the furfural is mostly condensed in the form of the aqueous phase, and since the azeotrope formed by the furfural and water has an azeotropic point of 97.9°C, the mixed gas of the water and the furfural needs to be cooled to 97.9°C or lower to condense. Moreover, compared with the high-temperature flue gas, the latent heat of high-temperature water vapor is large, and the consumption amount of a coolant required for condensation of water vapor is large. Therefore, when the new process of heating the reactant by the flue gas and stripping the furfural is used, the used amount of the coolant in the condensation process can be greatly reduced.
    BRIEF DESCRIPTION OF THE DRAWINGS
    Fig. 1 is a schematic view of the process flow of the present invention.
    Numbers in the drawing: 1 reactor, 2 condenser, 3 combustion boiler, 4 liquid separation tower, S I high-temperature flue gas, S2 mixed gas of flue gas and furfural, S3 low-temperature flue gas, S4 crude furfural, S5 venting, S6 aqueous phase, S7 aldehyde phase
    DETAILED DESCRIPTION
    The present invention is further described below in conjunction with specific embodiments.
    Embodiment 1
    The reaction raw material of com cobs was 2.7 t with the water content of 18%. The flue gas temperature was 220°C. The total flue gas flow rate was 759.2 standard cubic meters per hour. The flow rate of water was 124.5 standard cubic meters per hour. The flow rate of nitrogen was 399.8 standard cubic meters per hour. The flow rate of carbon dioxide was 199.9 standard cubic meters per hour. The flow rate of oxygen was 35.0 standard cubic meters per hour. The flue gas pressure was 0.8 MPa. The reactor temperature was controlled at 190°C. The condenser temperature was controlled at 50°C. The reaction results were as follows: the total flow of furfural formed was 333 kilograms per hour, the flow of the furfural in condensate was 329.3 kilograms per hour, the flow of the furfural in an equilibrium gas phase was 3.7 kilograms per hour, and the percentage of the furfural in the equilibrium gas phase was 1.1% of the total flow of the furfural formed.
    Embodiment 2
    The conditions were the same as in Embodiment 1. Only the flue gas pressure of 0.8
    MPa was reduced to 0.5 MPa. The reaction results were as follows: the total flow of furfural formed was 333 kilograms per hour, the flow of the furfural in condensate was 327.0 kilograms per hour, the flow of the furfural in an equilibrium gas phase was 6.0 kilograms per hour, and the percentage of the furfural in the equilibrium gas phase was 1.8% 5 of the total flow of the furfural formed.
    Embodiment 3
    The conditions were the same as in Embodiment 1. Only the condenser temperature of
    50°C was reduced to 20°C. The reaction results were as follows: the total flow of furfural formed was 333 kilograms per hour, the flow of the furfural in condensate was 332.0 10 kilograms per hour, the flow of the furfural in an equilibrium gas phase was 1.0 kilogram per hour, and the percentage of the furfural in the equilibrium gas phase was 0.3% of the total flow of the furfural formed.
    权利要求:
    Claims (2)
    [1]
    Conclusions
    An energy-saving, water-saving and environmentally-friendly method for preparing furfural, wherein reaction materials are heated and furfural
    5 is stripped with a high temperature flue gas from a boiler, dust in the flue gas is trapped in a solid reactant of a reactor, and sulfur trioxide in the flue gas reacts with water in the reactant in a sulfuric acid enhanced catalytic reaction to obtain furfural.
    [2]
    The method of claim 1, wherein the high temperature flue gas of
    The boiler enters the reactor from a bottom of the reactor and the reactant heats to 170 ° C to 250 ° C, mixed gas from the flue gas and furfural formed by the mixture of the furfural and the flue gas formed in the reactor enters a condenser to form a gas phase and a liquid phase, wherein the gas phase low temperature flue gas is introduced into a furnace of the boiler and the liquid phase
    15 enters a liquid separation tower to form an aqueous phase and an aldehyde phase.
    -o-o-o-o-o-
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    同族专利:
    公开号 | 公开日
    CN110066261A|2019-07-30|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    法律状态:
    优先权:
    申请号 | 申请日 | 专利标题
    CN201910317057.7A|CN110066261A|2019-04-18|2019-04-18|A kind of method for preparing furfural of energy-saving and water-saving environmental protection|
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