Method for preparing alcohol-based fuel from methanol industrial production waste

Abstract

The invention provides a method for preparing an alcohol-based fuel by using methanol industrial production wastes, which comprises the following steps of: rectifying fusel oil and wastewater generated in methanol industrial production as raw materials outside a methanol production system; collecting a product with the organic matter concentration higher than 95 wt% obtained at the tail section of rectification as a high-concentration alcohol-based fuel, controlling the COD content of the wastewater obtained by rectification to be 400-1200 mg / L, and directly combusting the non-condensable gas generated by rectification. According to the method, an original waste treatment device can be omitted, waste can be turned into wealth, and the method has extremely high economic value.

Description

Technical Field

[0001] The present invention relates to alcohol-based fuel, in particular to an alcohol-based fuel prepared by utilizing waste from methanol industrial production, and a method and application thereof. Background Art

[0002] Methanol is one of the important basic industrial organic raw materials and can be used to manufacture a variety of organic products, pesticides and various esters. The resulting products are further used in applications such as wood processing, plastics, coatings, textiles, paper, adhesives, etc.

[0003] Methanol was originally produced by dry distillation of wood. With the development of the chemical synthesis industry, hydrogenation of carbon oxides became the primary technology for industrial methanol production. This involves the catalytic reaction of carbon monoxide and hydrogen under high temperature and pressure to produce methanol, also known as coal-to-methanol technology. Another industrial route for methanol production is the oxidation or partial oxidation of natural gas (primarily methane).

[0004] In the industrial methanol production process, crude methanol is distilled to produce refined methanol. Byproducts include fusel oil and wastewater containing some methanol and other organic matter. These byproducts are highly polluting and, if discharged directly, would severely pollute the environment. Early treatment methods primarily treated them as hazardous waste, which incurs significant processing time and costs, and prevents the reuse of useful substances (including methanol and fusel oil). Currently, the industry generally chooses to use them as industrial fuels. Methanol wastewater and fusel oil are fed together into a coal-water slurry as feedstock for factory boilers. This approach eliminates the cost of hazardous waste treatment and allows for the reuse of heat. However, this fuel's combustion conditions are poor, and the combustion products still require hazardous waste disposal, resulting in secondary pollution. This makes it unsuitable for widespread application, particularly for civilian use.

[0005] Chinese invention patent CN 107162874A (and its Chinese utility model CN207101939U filed on the same day) discloses a distillation process and system for extracting refined methanol and fusel oil from crude methanol. The process steps are as follows: the crude methanol is treated in a pre-distillation tower, a purge gas scrubber, a pressure distillation tower, an atmospheric distillation tower, a recovery tower, and a fusel oil distillation tower to obtain refined methanol and fusel oil. A portion of fusel oil is obtained after passing through the purge gas scrubber, and another portion is obtained after passing through the fusel oil distillation tower. The two portions of fusel oil are mixed and sold directly as fusel oil for use as an alcohol-based fuel or gasoline blending component. The specific scheme includes: a distillation system for extracting refined methanol and fusel oil from crude methanol, the system including a purge gas washing tower, a pre-distillation tower, a pressure distillation tower, an atmospheric distillation tower, a recovery tower and a fusel oil distillation tower; a heat exchanger A is connected to the pre-distillation tower through a pipeline, the top of the pre-distillation tower is connected to the heat exchanger B through a pipeline, the heat exchanger B is connected to the purge gas washing tower and the reflux tank A respectively through pipelines, the bottom of the purge gas washing tower and the bottom of the reflux tank A are connected to the pre-distillation tower through pipelines, the bottom of the pre-distillation tower is connected to the pressure distillation tower through a pipeline via heat exchanger C, the bottom of the pressure distillation tower is connected to the atmospheric distillation tower through a pipeline via heat exchanger C, the top of the pressure distillation tower is connected to the reflux tank B through a pipeline, the reflux tank B is connected to the industrial methanol storage tank and heat exchanger D respectively through pipelines, the heat exchanger D is connected to the pressure distillation tower through a pipeline, the top of the atmospheric distillation tower is connected to the heat exchanger E through a pipeline, and the heat exchanger E is connected to the reflux tank through a pipeline. C is connected, the reflux tank C is respectively connected to the atmospheric distillation tower, the recovery tower and the heat exchanger F through pipelines, the heat exchanger F is connected to the industrial methanol storage tank through a pipeline, the bottom of the atmospheric distillation tower is connected to the heat exchanger G through a pipeline, the atmospheric distillation tower is connected to the recovery tower through a pipeline via a feed trough, the top of the recovery tower is connected to the atmospheric distillation tower through a pipeline, the bottom of the recovery tower is connected to the heat exchanger H through a pipeline, the recovery tower is connected to the fusel oil distillation tower through a pipeline via a heat exchanger I, the bottom of the fusel oil distillation tower is connected to the heat exchanger K through a pipeline, the lower end of the fusel oil distillation tower is connected to the heat exchanger L through a pipeline, the heat exchanger L is connected to the fusel oil distillation tower through a pipeline, the top of the fusel oil distillation tower is connected to the reflux tank D through a pipeline via a heat exchanger J, the reflux tank D is connected to the fusel oil distillation tower through a pipeline, the reflux tank A and the reflux tank D are connected to the fusel oil storage tank through pipelines, and the bottoms of the heat exchanger G, the heat exchanger H and the heat exchanger K are all connected to the wastewater system.

[0006] This patented technology claims that fusel oil with a total alcohol content of over 80% can be obtained by combining a portion of fusel oil obtained from a purge gas scrubber with another portion obtained after treatment in a fusel oil fractionator, and can be sold as a fuel product. However, this technology only concentrates the fusel oil to a certain extent, barely meeting the minimum requirements for a fuel product, and does not fully treat all waste generated in the methanol production process. Consequently, wastewater still remains, requiring further treatment. For example, this technology still requires the wastewater to be used as a coal-water slurry as mentioned in prior art, which still poses the problem of secondary pollution. Furthermore, the purge gas scrubber and fusel oil fractionator involved in this technology participate in the overall operation of the methanol product distillation system (pre-fractionator, atmospheric fractionator, and pressurized fractionator). Failures in these operations could affect the normal operation of the methanol product distillation system.

[0007] Chinese utility model patent document CN 208161074U discloses a device for recovering fusel oil and wastewater in a methanol production process, comprising a recovery tower, which is divided into a rectifying section, a stripping section and a bottom section from top to bottom. The rectifying section is provided with structured packing, the stripping section is provided with 16-20 high-efficiency trays from top to bottom, 3-5 feed ports are provided from top to bottom in the middle and upper part of the stripping section, and 6-10 fusel oil side-line extraction ports are provided from bottom to top in the stripping section. A methanol vapor discharge pipeline is provided at the top of the recovery tower, and part of the waste liquid from the bottom section of the recovery tower is cooled by a sewage discharge pipeline to a wastewater cooler. The cooled wastewater is then detoxified by a sewage treatment device, and the other part is transported to the recovery tower via a pipeline. The tower reboiler exchanges heat with the low-pressure steam and then returns to the bottom of the recovery tower. The recovery tower feed trough is used to buffer the fusel alcohol fraction generated in the methanol distillation process, the waste water at the bottom of the distillation tower, and the methanol sewage liquid in the methanol production and distillation process. The material in the recovery tower feed trough is pumped into the heat exchanger through the recovery tower feed pump and heat-exchanged with the methanol steam coming out of the methanol steam discharge pipeline at the top of the recovery tower. The material outlet of the heat exchanger is connected to each feed port of the recovery tower. The methanol steam coming out of the heat exchanger enters the recovery tower cooler for cooling. The cooled methanol enters the recovery tower reflux tank. The recovery tower reflux tank is connected to the methanol reflux pipeline at the top of the recovery tower. A recovery tower reflux pump is provided on the methanol reflux pipeline.

[0008] This technology collects the fusel alcohol fraction (collected from the atmospheric sidestream during the methanol distillation process), distillation column bottoms wastewater, and various methanol wastewater streams from the methanol production and distillation processes into the recovery column feed trough. This is then preheated with methanol vapor before being fed into the recovery column. Structured packing is used in the distillation section to separate the methanol vapor, while high-efficiency trays are used in the stripping section to purify the fusel oil. The stripping section is equipped with 6-10 fusel oil sidestream outlets from bottom to top. The purity of each outlet determines the extraction point of the fusel oil product, which is then sold as a fuel product. The overhead methanol vapor passes through a heat exchanger and enters the recovery column cooler for further cooling before entering the recovery column feed trough. Part of the crude methanol in the recovery column feed trough serves as overhead reflux to the recovery column, while the remainder is fed as overhead reflux to the pre-distillation column of the methanol distillation system. The bottoms wastewater is cooled and then sent to sewage treatment.

[0009] Although this technology claims to refine fusel oil, reduce its moisture content, and improve its quality, and that the refined fusel oil can be sold as fuel, improving the company's economic benefits, the refined fusel oil technology employed in this technology still involves partial concentration of fusel oil, resulting in fusel oil fuel products of varying concentrations for sale. Furthermore, this technology uses recovered crude methanol as reflux in the pre-distillation tower of the methanol distillation system. As a result, the presence of other byproduct components introduced by the reflux into the distillation system can affect the operation of the methanol distillation system, compromising the quality and stability of the refined methanol product. Furthermore, this technology does not disclose the fusel alcohol content in the resulting fusel oil, making it unclear whether it meets the moisture content requirements for alcohol-based fuels.

[0010] Chinese utility model patent document CN 217549031U discloses a methanol distillation fusel oil concentration reduction process system. During the operation of the distillation system, a portion of the fusel oil produced by the recovery tower is returned to the recovery tower feed tank and recovery tower feed pipeline through a newly added modified pipeline and control valve group, and then re-enters the recovery tower for distillation and purification. The scheme specifically includes: a recovery tower, the inlet pipeline end of the recovery tower is connected to the recovery tower feed tank and the atmospheric tower side line extraction pipeline via a pipeline and a pressure pump on the pipeline; the outlet pipeline end of the recovery tower is connected to the fusel oil tank via a pipeline; the fusel oil tank is connected to the pipeline from the fusel oil production to the fusel oil storage tank; a concentration reflux branch is also provided between the fusel oil tank and the pipeline from the fusel oil production to the fusel oil storage tank; the concentration reflux branch is equipped with a regulating valve group; the pipeline of the regulating valve group is connected to the recovery tower feed tank via a valve; and the pipeline of the regulating valve group is connected to the inlet pipeline end of the recovery tower via a valve. A sealed sampling point is also provided on the inlet pipeline of the recovery tower. A pipeline for fusel oil to be transported to the boiler for blending is also provided between the fusel oil tank and the pipeline from fusel oil production to the fusel oil storage tank. The recovery tower is connected to the pipeline for alcohol-containing process water from the atmospheric pressure tower. The bottom pipeline of the recovery tower is connected to the pipeline for process wastewater treatment.

[0011] While this technology claims to significantly increase the concentration of fusel alcohol components in the fusel oil recovered from the recovery tower, significantly reducing fusel oil production while ensuring the quality of the refined methanol product, and furthermore, the recovered fusel oil can be fed to the power boiler for co-firing via newly added and modified pipelines as needed, enabling internal recycling of the fusel oil within the production system and reducing the generation of hazardous fusel oil waste, resulting in significant economic and environmental benefits, this technology returns the recovered fusel oil (containing a large amount of methanol) to the distillation system for re-distillation and purification. However, the presence of other byproduct components introduced by the reflux into the distillation system can affect the operation of the methanol distillation system, compromising the quality and stability of the refined methanol product. Furthermore, the fusel alcohol content of the resulting fusel oil after concentration is only 38.52%, far below the water content requirement for alcohol-based fuels.

[0012] In summary, the existing technologies for treating fusel oil and wastewater generated in methanol industrial production still have problems such as the recovered methanol affecting the quality of the refined methanol product, the fusel oil obtained by distillation treatment cannot be used as high-quality alcohol-based fuel, and the waste reprocessing cannot be completely avoided. Summary of the Invention

[0013] In order to solve the above technical problems, the present invention provides a method for preparing alcohol-based fuel using methanol industry production waste, comprising: re-distilling methanol industry fusel oil to obtain a distillate with a concentration of more than 95wt% as high-concentration alcohol-based fuel.

[0014] Furthermore, the distillation is carried out outside the methanol production system, and the COD content of the wastewater obtained by the distillation is controlled to be 400-1200 mg / L before being discharged, and the non-condensable gas generated by the distillation is directly burned.

[0015] Furthermore, the method further comprises extracting a distillate having an organic matter concentration of 70-95 wt %, preferably 70 wt %, as a low-concentration alcohol-based fuel.

[0016] Preferably, the concentration of the low-concentration alcohol-based fuel is adjusted by extracting the high-concentration alcohol-based fuel into the low-concentration alcohol-based fuel.

[0017] Furthermore, the raw material is preheated to 40-60°C, preferably 50°C before distillation.

[0018] Preferably, the raw material is preheated by exchanging heat between the wastewater produced by the rectification and the raw material.

[0019] Most preferably, fusel oil and wastewater generated by methanol industrial production are used as raw materials for further distillation, the distillation is carried out outside the methanol production system, the raw materials are preheated to 50°C before distillation, and the distillation conditions are: tower bottom temperature 105-115°C, sensitive point temperature 95-105°C, and tower top pressure 30-40kPa; the distillate obtained by the distillation with an organic matter concentration of more than 95wt% is extracted as a high-concentration alcohol-based fuel, and the distillate with an organic matter concentration of 70-95wt% is extracted as a low-concentration alcohol-based fuel. The low-concentration alcohol-based fuel is adjusted by extracting the high-concentration alcohol-based fuel into the low-concentration alcohol-based fuel, and the COD content of the wastewater obtained by the distillation is controlled to be 400-1200 mg / L before discharge treatment, and the non-condensable gas generated by the distillation is directly burned.

[0020] The present invention also provides an alcohol-based fuel prepared by the method of the present invention.

[0021] The present invention also provides the use of fusel oil, a waste produced from methanol industrial production, in alcohol-based fuel.

[0022] The present invention has the following beneficial effects: By using the method of the present invention, fusel oil and alcohol-containing wastewater generated by methanol industrial production are recovered by a distillation tower, and two products, 95# alcohol-based fuel and 70# alcohol-based fuel, can be produced. The original waste treatment device is omitted, the production cost can be reduced, and no production waste is generated. Waste is turned into treasure to obtain products with high economic value, realizing green production and becoming a truly waste-free factory.

[0023] Compared with the existing technology of adding a distillation tower to recover the crude methanol and then returning it to the methanol production system, the present invention uses the top product of an independent distillation tower directly as 95# alcohol-based fuel, and no longer recycles methanol to the original production system. This can effectively avoid contamination of the distillation system of the original refined methanol product itself when the tower production process fails, and is more conducive to stable industrial production, fully ensuring the quality of each product.

[0024] This invention recovers heat from the tower bottom wastewater as a heat source for the raw material preheater. The feed is heated to approximately 50°C before entering the distillation tower. The raw material preheater preheats the feed, saving energy in the tower bottom. It also cools the bottom water in the tower bottom, reducing circulating water consumption and achieving energy savings.

[0025] The 95# alcohol-based fuel and the 70# alcohol-based fuel produced by the present invention can be extracted separately, and the 95# alcohol-based fuel can also be extracted into the 70# alcohol-based fuel for processing when the water content of the product exceeds the standard. This not only ensures product quality, but also avoids the cost increase caused by the increased energy consumption of the device due to the need to return the material due to unqualified water content in the prior art. DETAILED DESCRIPTION

[0026] The following is further described in detail through specific embodiments. However, it should be noted that the following embodiments of the present invention are merely for the purpose of better illustrating the content of the present invention, and do not mean that the content of the present invention is limited to the examples. Therefore, those skilled in the art may make non-essential improvements and adjustments to the embodiments based on the above invention, which still fall within the scope of protection of the present invention and are subject to the scope of protection of the appended claims.

[0027] The methanol production mentioned in the present invention refers to the coal-based methanol or natural gas-based methanol process, which respectively produces methanol by hydrogenating carbon oxides, using carbon monoxide and hydrogen to react catalytically at high temperature and high pressure to produce methanol, and by oxidizing or partially oxidizing natural gas (mainly methane) to produce methanol.

[0028] The fusel oil mentioned in the present invention refers to a mixture of by-products produced in the methanol industrial production, mainly including by-products such as dimethyl ether, carbon monoxide, carbon dioxide, water, etc., and also includes some unrefined methanol products and other alcohol by-products (such as ethanol, propanol, glycerol, butanol, etc.).

[0029] The distillation described in this invention is a typical method for separating miscible liquid mixtures in chemical production. Its essence is multi-stage distillation. Under a certain pressure, the different boiling points or saturated vapor pressures of the components of a miscible liquid mixture are exploited to vaporize the light component (the component with the lower boiling point or higher saturated vapor pressure). Through multiple partial liquid vaporizations and partial gas condensations, the concentrations of the light component in the gas phase and the heavy component in the liquid phase gradually increase, achieving separation. The feedstock is introduced into the tower at an appropriate position in the middle, dividing the tower into two sections: the upper section, which contains no feed, is the rectifying section, and the lower section, which contains the feed plate and is the stripping section. A condenser provides liquid reflux from the top of the tower, and a reboiler provides gas reflux from the bottom. In the rectifying section, the light component is continuously refined as the gas phase rises, continuously concentrating in the gas phase, and the light component product is obtained at the top of the tower. In the stripping section, the light component is continuously stripped out as the liquid phase descends, continuously concentrating the heavy component in the liquid phase, and the heavy component product is obtained at the bottom of the tower. The temperature, pressure, reflux ratio, etc. of different trays have an important influence on the distillation effect. The distillation effect can be optimized by adjusting these parameters.

[0030] In the present invention, due to their boiling points, light components such as dimethyl ether, carbon monoxide, and carbon dioxide are not condensed during the distillation process. These non-condensable gases are discharged through the exhaust gas discharge channel at the top of the distillation tower and directly burned in a flare combustion unit, such as a methanol refining unit, without the need for additional waste gas treatment. Alcohols and some other organic compounds can form azeotropic mixtures with water, with their azeotropic points typically between 80-100°C. When the temperature is below the azeotropic point, they can condense to form a liquid mixture, which can be distilled from appropriate locations in the distillation tower to produce aqueous mixtures with varying organic concentrations, namely, alcohol-based fuels.

[0031] The alcohol-based fuel described herein refers to a mixture primarily composed of alcohols (such as methanol, ethanol, and butanol) that can be burned to generate energy. It exists in liquid or solid form and typically refers to liquid alcohol-based fuel. Alcohol-based fuel can be used in environments without natural gas supply, such as restaurants and construction sites in remote areas. Of course, alcohol-based fuel can also replace existing natural gas, gasoline, and diesel fuels in applications such as residential boilers, industrial boilers, and kilns. Alcohol-based fuel is widely used in industrial applications such as industrial boilers, kilns, ceramic firing, hot air furnaces, paint spraying, hardware die-casting, and the dissolution of copper, aluminum, and zinc alloys. Alcohol-based fuel can be used in most applications where diesel is used, saving significant amounts of diesel and fuel costs for users, creating positive social benefits.

[0032] The advantages of alcohol-based fuels include environmental friendliness, thermal efficiency, affordability, practicality, and safety. The primary combustion products of alcohol-based fuels are H2O and CO2. They are smokeless, odorless, pressure-free, pollution-free, require no flue, and leave no residue. Alcohol-based fuels have high thermal efficiency and burn completely, with a latent heat of vaporization approximately three times that of gasoline. Currently, alcohol-based fuels enjoy a significant price advantage, and their cost is expected to decrease over time. Compared with liquefied petroleum gas (LPG), kerosene, and diesel, alcohol-based fuels are less expensive and contribute less to air pollution. Compared with solid fuels such as coal and firewood, alcohol-based fuels significantly reduce environmental pollution and are easy to store and transport. Unlike natural gas, alcohol-based fuels do not require expensive pipeline systems. They are non-toxic, easy to store, have high anti-explosion properties, and have a high ignition point, making them less prone to fire accidents. With a flash point of 20°C, they can be extinguished with water, making them safer than petroleum, natural gas, and city gas. The 95# and 70# alcohol-based fuels described in the present invention are defined by the mass percentage content of organic matter in the product. 95# alcohol-based fuel refers to an alcohol-based fuel with an organic matter concentration greater than 95wt% or a water content not greater than 5wt%, also referred to as a high-concentration alcohol-based fuel in the present invention; 70# alcohol-based fuel refers to an alcohol-based fuel with an organic matter concentration of 70wt% or a water content not greater than 30wt%. National standard GB 16663-1996 "Alcohol-based liquid fuels" stipulates that the organic matter concentration of alcohol-based fuels shall not be less than 70wt%, so the 70# product is the alcohol-based fuel product with the lowest concentration that can be sold. Other alcohol-based fuel products with an organic matter concentration between 70-95% can also be formed, i.e., the low-concentration alcohol-based fuel described in the present invention. The concentration of organic matter in the product can be adjusted by directly collecting alcohol-based fuel products of different concentrations during the distillation process of the present invention, or by refluxing the 95# product of the present invention.

[0033] Methods for determining the organic matter and water content in alcohol-based fuels are well known to those skilled in the art. For example, the Karl Fischer water analysis method is used for water content determination. This method is recognized worldwide as a classic method for determining the water content of substances and is widely used as a standard method for determining the water content of various substances in the fields of petroleum, chemical industry, pharmaceuticals, commodity inspection, and environmental protection. For detailed procedures, refer to the national standard GB T 6283-2008, "Determination of Water Content in Chemical Products - Karl Fischer Method (General Method)."

[0034] Alcohol content is calculated by subtracting the alcohol content from the water content: alcohol content (%) = 1 - water content (%). A simplified method for determining alcohol content can also be used using the oil layer volume stratification method specified in Section 4.2 of the national standard GB 16663-1996, "Alcohol-based Liquid Fuels."

[0035] Example 1 The present invention provides a method for preparing alcohol-based fuel using waste from the methanol industry production process. Fusel oil and wastewater generated by the methanol industry production line are combined and collected as raw materials. A separate and independent distillation tower is installed outside the methanol industry production line. The distillation tower comprises, from top to bottom, a distillation section, a stripping section, and a bottom section. Packing and trays are conventionally arranged within the tower. A high-concentration alcohol-based fuel outlet is provided at the top of the distillation section, along with a reflux device for returning a portion of the high-concentration alcohol-based fuel to the distillation section. A raw material inlet is provided in the upper portion of the stripping section, while a low-concentration alcohol-based fuel outlet is provided in the middle. The bottom section is connected to a reactor, which can accommodate bottom water and distillation condensate wastewater and provides water vapor for reflux into the stripping section via a reboiler.

[0036] The collected fusel oil and wastewater are preheated to 50°C in a raw material preheater and then enter the distillation column through the raw material inlet of the stripping section for distillation. The raw material preheater is connected to the bottom of the distillation column and uses bottom water and distillation condensate as heat sources to exchange heat with the raw materials to preheat the raw materials.

[0037] The specific conditions of distillation are: bottom temperature of 110℃, sensitive point temperature of 100℃, and top pressure of 30kPa.

[0038] High-concentration alcohol-based fuel is collected from the top of the distillation section as the 95# alcohol-based fuel product and stored in the corresponding storage tank for future use. Low-concentration alcohol-based fuel is collected from the middle of the stripping section as the 70# alcohol-based fuel product and stored in the corresponding storage tank for future use. The organic matter and water content of the product are tested. If the 70# alcohol-based fuel product does not meet the standards, the reflux of 95# alcohol-based fuel to 70# alcohol-based fuel is opened to adjust the concentration to meet the standards.

[0039] The COD content of the wastewater in the distillation tower is tested, and after the COD content is controlled within 1200 mg / L, the wastewater is collected from the tower and used for conventional discharge treatment. The non-condensable gas produced at the top of the distillation tower is directly sent to the flare device of the existing methanol industrial production line for combustion treatment.

[0040] Example 2 A method for producing alcohol-based fuel using waste from the methanol industry production process involves combining and collecting fusel oil and wastewater generated by the methanol production line as raw materials. A separate, independent distillation tower is installed outside the methanol production line. The tower comprises, from top to bottom, a rectifying section, a stripping section, and a bottom section, with conventional packing and trays. A high-concentration alcohol-based fuel outlet is provided at the top of the rectifying section, along with a reflux device for returning a portion of the high-concentration alcohol-based fuel to the rectifying section. A raw material inlet is provided in the upper middle portion of the stripping section, while a low-concentration alcohol-based fuel outlet is provided in the middle. The bottom section is connected to a reactor, which can accommodate bottom water and distillation condensate wastewater and provides water vapor for reflux into the stripping section via a reboiler.

[0041] The collected fusel oil and wastewater are preheated to 50°C in a raw material preheater and then enter the distillation column through the raw material inlet of the stripping section for distillation. The raw material preheater is connected to the bottom of the distillation column and uses bottom water and distillation condensate as heat sources to exchange heat with the raw materials to preheat the raw materials.

[0042] The specific conditions of distillation are: bottom temperature of 110℃, sensitive point temperature of 103℃, and top pressure of 35kPa.

[0043] High-concentration alcohol-based fuel is collected from the top of the distillation section as the 95# alcohol-based fuel product and stored in the corresponding storage tank for future use. Low-concentration alcohol-based fuel is collected from the middle of the stripping section as the 70# alcohol-based fuel product and stored in the corresponding storage tank for future use. Testing the organic matter and water content of the products revealed that the 70# alcohol-based fuel product met the standards, but the water content of the 95# alcohol-based fuel exceeded the standard, and the alcohol content did not meet the ≥95% requirement. The sensitive temperature must be lowered to 100°C until the 95# alcohol meets the standards before it can be produced.

[0044] The COD content of the wastewater in the distillation tower was tested and found to be 400 mg / L. The wastewater was then used for conventional discharge treatment. The non-condensable gas produced at the top of the distillation tower was directly sent to the flare device of the existing methanol industrial production line for combustion treatment.

[0045] Example 3 A method for producing alcohol-based fuel using waste from the methanol industry production process involves combining and collecting fusel oil and wastewater generated by the methanol production line as raw materials. A separate, independent distillation tower is installed outside the methanol production line. The tower comprises, from top to bottom, a rectifying section, a stripping section, and a bottom section, with conventional packing and trays. A high-concentration alcohol-based fuel outlet is provided at the top of the rectifying section, along with a reflux device for returning a portion of the high-concentration alcohol-based fuel to the rectifying section. A raw material inlet is provided in the upper middle portion of the stripping section, while a low-concentration alcohol-based fuel outlet is provided in the middle. The bottom section is connected to a reactor, which can accommodate bottom water and distillation condensate wastewater and provides water vapor for reflux into the stripping section via a reboiler.

[0046] The collected fusel oil and wastewater are preheated to 50°C in a raw material preheater and then enter the distillation column through the raw material inlet of the stripping section for distillation. The raw material preheater is connected to the bottom of the distillation column and uses bottom water and distillation condensate as heat sources to exchange heat with the raw materials to preheat the raw materials.

[0047] The specific conditions of distillation are: bottom temperature of 107℃, sensitive point temperature of 100℃, and top pressure of 30kPa.

[0048] High-concentration alcohol-based fuel is collected from the top of the distillation section as the 95# alcohol-based fuel product and stored in the corresponding storage tank for future use. Low-concentration alcohol-based fuel is collected from the middle of the stripping section as the 70# alcohol-based fuel product and stored in the corresponding storage tank for future use. The organic matter and water content of the product are tested. If the 70# alcohol-based fuel product does not meet the standards, the reflux of 95# alcohol-based fuel to 70# alcohol-based fuel is opened to adjust the concentration to meet the standards.

[0049] The COD content of the wastewater in the tower bottom obtained by the distillation was tested, and the COD content was 3700 mg / L. The wastewater extracted from the tower bottom shall not be used for conventional discharge treatment. At this time, the bottom water should be sent to the raw material tank and the working conditions should be readjusted to meet the COD requirements before it can be discharged.

[0050] Example 4 A method for producing alcohol-based fuel using waste from the methanol industry production process involves combining and collecting fusel oil and wastewater generated by the methanol production line as raw materials. A separate, independent distillation tower is installed outside the methanol production line. The tower comprises, from top to bottom, a rectifying section, a stripping section, and a bottom section, with conventional packing and trays. A high-concentration alcohol-based fuel outlet is provided at the top of the rectifying section, along with a reflux device for returning a portion of the high-concentration alcohol-based fuel to the rectifying section. A raw material inlet is provided in the upper middle portion of the stripping section, while a low-concentration alcohol-based fuel outlet is provided in the middle. The bottom section is connected to a reactor, which can accommodate bottom water and distillation condensate wastewater and provides water vapor for reflux into the stripping section via a reboiler.

[0051] The collected fusel oil and wastewater are preheated to 50°C in a raw material preheater and then enter the distillation column through the raw material inlet of the stripping section for distillation. The raw material preheater is connected to the bottom of the distillation column and uses bottom water and distillation condensate as heat sources to exchange heat with the raw materials to preheat the raw materials.

[0052] The specific conditions of distillation are: bottom temperature of 112℃, sensitive point temperature of 98℃, and top pressure of 40kPa.

[0053] High-concentration alcohol-based fuel is collected from the top of the distillation section as the 95# alcohol-based fuel product and stored in the corresponding storage tank for future use. Low-concentration alcohol-based fuel is collected from the middle of the stripping section as the 70# alcohol-based fuel product and stored in the corresponding storage tank for future use. The organic matter and water content of the product are tested. If the 70# alcohol-based fuel product does not meet the standards, the reflux of 95# alcohol-based fuel to 70# alcohol-based fuel is opened to adjust the concentration to meet the standards.

[0054] The COD content of the wastewater in the distillation tower bottom was tested and found to meet the COD control index of 1200 mg / L. The wastewater was then extracted from the tower bottom and used for conventional discharge treatment. The non-condensable gas produced at the top of the distillation tower was directly sent to the flare device of the existing methanol industrial production line for combustion treatment.

[0055] Example 5 Economic Value Calculations show that this production line, with a raw material feed rate of 6 tons per hour, produces 3.15 tons per hour of 95# alcohol-based fuel and 0.26 tons per hour of 70# alcohol-based fuel. Based on current market prices, 95# alcohol-based fuel costs 2,000 yuan per ton, generating a daily economic value of 3.15 * 24 * 2,000 = 151,200 yuan; 70# alcohol-based fuel costs 800 yuan per ton, generating a daily economic value of 0.26 * 24 * 800 = 4,992 yuan. The combined daily economic value of these two products is 156,192 yuan, demonstrating extremely high economic value.

[0056] Example 6: Saved Return Material Processing Cost Calculations show that conventional recycle treatment of 70# alcohol-based fuel with excessive water content, using a 170m³ tank capacity and 60 tons of recycle per batch, requires at least 30 hours to complete due to its concentration of approximately 65%. Based on a steam consumption of 5 tons / hour and the current price of 160.27 yuan / ton, this translates to a processing cost of 160.27*5*30=24,040.5 yuan. However, using the present invention, the 95# alcohol-based fuel extracted and directly concentrated into 70# alcohol-based fuel requires only 3.2 tons of 95# alcohol-based fuel, costing only 3.2*2,000=6,400 yuan. This represents a significant cost savings of 17,640.5 yuan compared to conventional recycle treatment.

[0057] In summary, the method of the present invention is used to recover fusel oil and alcohol-containing wastewater generated by industrial production of methanol using a distillation tower. This not only saves the original waste treatment device, but also turns waste into treasure and produces 95# alcohol-based fuel and 70# alcohol-based fuel, two products with great economic value. At the same time, the pollution and product quality impact caused by methanol recovery are avoided. The product quality of 70# alcohol-based fuel is adjusted by 95# alcohol-based fuel to avoid return material processing, which also greatly saves economic costs.

[0058] The above is only an embodiment of the present invention. The commonly known technical common sense in the scheme is not described in detail here. Those of ordinary skill in the art are aware of all the common technical knowledge in the technical field to which the invention belongs before the application date, can obtain all the existing technologies in the field, and have the ability to apply conventional experimental means before that date. Those of ordinary skill in the art can improve and implement this scheme in combination with their own abilities under the enlightenment given by this application. Some typical commonly known technologies should not become obstacles for those of ordinary skill in the art to implement this application. It should be pointed out that for those skilled in the art, without departing from the structure of the present invention, several adjustments and improvements can be made, which should also be regarded as the scope of protection of the present invention. These will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A method for preparing alcohol-based fuel using methanol industrial production waste, characterized by: The methanol industrial fusel oil is distilled again to obtain a distillate with a content of more than 95 wt% which is used as a high-concentration alcohol-based fuel.

2. The method according to claim 1, wherein: The distillation is carried out outside the methanol production system, and the COD content of the wastewater obtained by the distillation is controlled to be 400-1200 mg / L before discharge treatment, and the non-condensable gas generated by the distillation is directly burned.

3. The method according to claim 2, characterized in that The method also includes extracting a distillation product with an organic matter concentration of 70-95 wt% as a low-concentration alcohol-based fuel.

4. The method according to claim 3, characterized in that The concentration of the low-concentration alcohol-based fuel is adjusted by extracting the high-concentration alcohol-based fuel into the low-concentration alcohol-based fuel.

5. The method according to claim 4, characterized in that The organic matter concentration of the low-concentration alcohol-based fuel is adjusted to 70 wt %.

6. The method according to any one of claims 1 to 5, characterized in that The feedstock was preheated to 40-60°C before distillation.

7. The method according to claim 6, characterized in that The wastewater generated by the distillation is used to perform heat exchange with the raw material to preheat the raw material.

8. The method according to any one of claims 1 to 7, characterized in that Fusel oil and wastewater generated by methanol industrial production are used as raw materials for secondary distillation. The distillation is carried out outside the methanol production system. The raw materials are preheated to 50°C before distillation. The distillation conditions are: a bottom temperature of 105-115°C, a sensitive point temperature of 95-105°C, and a top pressure of 30-40kPa. The distillate obtained by the distillation with an organic matter concentration of more than 95wt% is extracted as a high-concentration alcohol-based fuel, and the distillate with an organic matter concentration of 70-95wt% is extracted as a low-concentration alcohol-based fuel. The low-concentration alcohol-based fuel is adjusted by extracting the high-concentration alcohol-based fuel into the low-concentration alcohol-based fuel. The COD content of the wastewater obtained by the distillation is controlled to be 400-1200 mg / L before discharge treatment. The non-condensable gas generated by the distillation is directly burned.

9. An alcohol-based fuel prepared by the method according to any one of claims 1 to 8.

10. Application of fusel oil, a waste product from methanol industry production, in alcohol-based fuels.