阅读说明：本技术 一种用棉籽油生产生物柴油的制备方法 (Preparation method for producing biodiesel by using cottonseed oil ) 是由 沈楠 任从容 沈田 祝康祥 沈井然 于 2019-11-21 设计创作，主要内容包括：本发明公开了一种用棉籽油制备生物柴油的方法,采用有机碱为催化剂,一步法进行酯交换反应,生产生物柴油,将空化设备、超声波反应器或二级以上空化设备、超声波反应器串联,强化反应过程；具体步骤如下：以棉籽油为原料,添加甲醇,棉籽油与甲醇的油醇比(W/W)为5～8:1,有机碱质量用量为棉籽油质量的3～8‰,酯交换反应温度为40～64℃,反应时间在10～60min；酯交换反应过程中施加空化设备或超声波反应器产生的超声波至反应物。采用的催化剂包括甲醇钾、甲醇钠或甲醇钙。本发明将液力空化和电子超声空化两大功效进行有机结合,以更加简便、快捷、节能的方式将棉子油加工为生物柴油。(The invention discloses a method for preparing biodiesel by cottonseed oil, which adopts organic base as a catalyst to carry out ester exchange reaction by a one-step method to produce biodiesel, and cavitation equipment, an ultrasonic reactor or more than two-stage cavitation equipment and the ultrasonic reactor are connected in series to strengthen the reaction process; the method comprises the following specific steps: the method comprises the following steps of adding methanol into cottonseed oil serving as a raw material, wherein the ratio of the cottonseed oil to the methanol in oil to alcohol (W/W) is 5-8: 1, the mass of an organic base is 3-8 per mill of the mass of the cottonseed oil, the transesterification reaction temperature is 40-64 ℃, and the reaction time is 10-60 min; during the ester exchange reaction, ultrasonic waves generated by a cavitation device or an ultrasonic reactor are applied to reactants. The catalyst used comprises potassium methoxide, sodium methoxide or calcium methoxide. The invention organically combines the hydraulic cavitation and the electronic ultrasonic cavitation, and processes the cottonseed oil into the biodiesel in a more simple, convenient, rapid and energy-saving way.)

1. A method for preparing biodiesel by cottonseed oil is characterized in that organic base is used as a catalyst, ester exchange reaction is carried out by a one-step method to produce biodiesel, a cavitation device, an ultrasonic reactor or a cavitation device with more than two stages and the ultrasonic reactor are connected in series, and ultrasonic waves act on reactants to strengthen the reaction process; the method comprises the following specific steps: the method comprises the following steps of adding methanol into cottonseed oil serving as a raw material, wherein the ratio of the cottonseed oil to the methanol in oil to alcohol (W/W) is 5-8: 1, the mass of an organic base is 3-8 per mill of the mass of the cottonseed oil, the transesterification reaction temperature is 40-64 ℃, and the reaction time is 10-60 min; during the ester exchange reaction, ultrasonic waves generated by a cavitation device or an ultrasonic reactor are applied to reactants.

2. The method of claim 1, wherein the catalyst comprises potassium methoxide, sodium methoxide, or calcium methoxide.

3. The method of claim 1, wherein the water content of potassium methoxide, sodium methoxide or calcium methoxide is not greater than 0.5%.

4. The method for preparing biodiesel by using cottonseed oil according to claim 1, wherein the cavitation device is a reed liquid whistle pump, the ultrasonic reactor is a plate or rod type ultrasonic transducer, and the application time is more than 10 min.

5. The method for preparing biodiesel by using cottonseed oil according to claim 1 or 4, wherein the ultrasonic frequency of the ultrasonic reactor is 25 to 100K.

6. The method for preparing biodiesel by using cottonseed oil according to claim 1, 2 or 3, wherein cottonseed oil, methanol and organic base catalyst are respectively strictly metered, and corresponding raw materials are respectively conveyed into a preheating mixing kettle by a cottonseed oil pump, a methanol pump and a catalyst pump through pipelines, then conveyed into an ultrasonic reactor by a reed liquid whistle pump, and then conveyed into an esterification kettle; after the kettle material is added to a specified amount, the feeding is switched to another esterification kettle connected in parallel; stopping stirring after the materials react in the esterification kettle for 10-30 min, and standing, settling and layering; after layering, the glycerol was cut tangentially into the crude glycerol receiving tank.

7. The preparation method for producing biodiesel by using cottonseed oil according to claim 6, wherein the oleyl alcohol ratio (W/W) of the cottonseed oil to the methanol is 6:1, the using amount of the organic base is 3-4.5 per mill, the preheating temperature is 30-64 ℃, and the stirring speed is 90-120 r/m.

8. The method as claimed in claim 6, wherein the raw materials are fed into the esterification reactors connected in parallel via a reed liquid whistle pump and at least one ultrasonic reactor, and a circulation pipeline is formed by switching the reed liquid whistle pump, at least one ultrasonic reactor and the inlet and outlet of the esterification reactors connected in parallel via a pipeline and a valve.

9. The method for preparing biodiesel from cottonseed oil as claimed in claim 8, wherein when the liquid level in the pre-heating mixing kettle exceeds 50%, the reed liquid whistle pump is started to feed the esterification kettle through the ultrasonic reactor; starting the kettle to stir when feeding; when the liquid level in the esterification kettle reaches 1/4, a valve of a reed liquid removing whistle pump at the bottom of the esterification kettle is opened, a discharge valve of the preheating mixing kettle is controlled, the circulation of materials in the esterification kettle through a kettle external circulation pipeline is ensured, and reaction materials can enter the reed liquid whistle pump and the ultrasonic reactor again to carry out secondary cavitation.

10. The method for preparing biodiesel by using cottonseed oil according to claim 1 or 8, wherein an ultrasonic reactor is arranged in the esterification kettle, and the esterification kettle is provided with a heating control device and a stirring device; at least the first ultrasonic reactor is a rod-type ultrasonic reactor.

Technical Field

The invention relates to a new method for producing biodiesel by using cottonseed oil.

Background

Biodiesel (Biodiesel) refines automatic vegetable oils, commonly used in tractors, trucks, ships, and the like. It is a renewable diesel fuel which can replace petroleum diesel and is prepared by taking oil crops such as wild oil plants such as soybean, rape, cottonseed and palm kernel, aquatic plant oil such as engineering microalgae, animal oil, food and beverage garbage oil and the like as raw materials and performing ester exchange or thermochemical process. Biodiesel is one of the biomass energy sources, which is close to petrochemical diesel in physical properties, but different in chemical composition. Biodiesel is a complex mixture of organic constituents with extremely high oxygen content, and the mixture is mainly organic substances with large molecular weight, and almost all kinds of oxygen-containing organic substances, such as ester, ether, aldehyde, ketone, phenol, organic acid, alcohol and the like. The composite biological diesel oil is synthesized by using waste animal and vegetable oil, waste engine oil and by-product of oil refinery as raw material, adding catalyst and special equipment and special process.

Due to the outstanding environmental protection and renewability of biodiesel, the advanced countries in the world, especially the resource-poor countries, pay high attention. In the last decade, the biodiesel industry has developed rapidly in countries around the world. The United states is the country which researches the biodiesel at the earliest, in order to reduce the production cost of the biodiesel, 10 to 20 percent of the biodiesel is generally added into the common diesel, such as the American B-20 biodiesel, and the emission of the tail gas pollutants can be reduced by more than 50 percent. In recent years, 5 percent of biodiesel is added into deep hydrofined common diesel to improve the lubricating property of the common diesel.

Biodiesel is a new industry in China and starts late. In the early eighties of the last century, the specialized money of medium petrochemicals was allocated, and a series of basic researches on biodiesel were carried out by the Shanghai institute of internal combustion engines. In the nineties, biodiesel was listed in the national "eighty-five" program as a major scientific and technological project. In 2007, the yield of biodiesel in China reaches 200 million tons.

The development of biodiesel is an important measure for environmental protection, namely, the tail gas of a diesel engine refers to the exhaust gas sprayed by the diesel engine after the diesel is combusted, the tail gas contains hundreds of different compounds, and the tail gas of the diesel engine is recognized by experts of the world health organization to be the same as substances such as asbestos, arsenic and the like, and has high carcinogenicity. The pollutants mainly comprise carbon monoxide, hydrocarbon, oxynitride, sulfur dioxide, smoke particles (certain heavy metal compounds, lead compounds, black smoke and oil mist), and odor (formaldehyde and the like).

The most significant harm of diesel exhaust is the formation of photochemical smog. The smog can cause people to have red eyes, sore throat, suffocating breath, dizziness and headache, and is the essential condition for forming PM 2.5. The method has the advantages that the atmospheric pollution needs to be controlled, a living environment of blue sky and white cloud is possessed, and the diesel engine tail gas pollution is controlled and cannot be controlled. Generally, 10-20% of biodiesel is added into common diesel, and the emission of tail gas pollutants can be reduced by more than 50%.

The development of the biodiesel is a necessary of circular economy, the biodiesel is a clean renewable energy source and mainly takes natural animal and vegetable oil or various waste oil leftovers discarded by human beings in daily life as raw materials. These are renewable resources and are fully utilized here.

The cottonseed oil is selected as a raw material for producing the biodiesel, and the cotton is a large economic crop, the cottonseed exists in all cotton production areas, and the amount of the cottonseed is far greater than that of finished cotton. The ratio between them is approximately such that the ratio of cotton yield (lint) to cotton seed yield is approximately 3.5 to 6.5, i.e. 1 tonne of cotton, i.e. 1.86 tonnes of cotton seeds. The cottonseed oil can be squeezed out at 0.13t for 1t, and the by-products are cottonseed meal at 0.5t and cottonseed hull at 0.35 t. According to the data published by the State statistics office in 2019 in 3 months, the cotton yield in China in 2018 is 610 ten thousand tons. The amount of cottonseed in the country is 1135 ten thousand tons, and 147 ten thousand tons of cottonseed oil can be produced.

The cottonseed oil is oil extracted from cottonseed, and is divided into pressed cottonseed oil and leached cottonseed oil according to the processing technology; the processing degree is divided into crude cottonseed oil and finished cottonseed oil. The refined cottonseed oil is generally orange yellow or brown, the cottonseed oil fatty acid contains 21.6-24.8% of palmitic acid, 1.9-2.4% of stearic acid, 0-0.1% of arachidic acid, 18.0-30.7% of oleic acid and 44.9-55.0% of linoleic acid, and the refined clear cotton oil removes toxic substances such as gossypol and the like and can be eaten by people.

Gossypol, a phenol-containing toxoside, is a very strong spermicidal drug, and has great toxicity to the liver, blood vessels, intestinal tracts and nervous systems. Free gossypol also affects most male hyposexuality. Consumption of crude cottonseed oil can cause damage to spermatogenic cells, resulting in aspermia and infertility. The cottonseed oil contains gossypol which is difficult to remove and clean, so that the cottonseed oil has great harm to human bodies, and the edible oil series are gradually faded out. Cottonseed oil is commonly used in industry to produce soap, glycerin, printing ink, lubricating oil, pesticide solvent, and leather fatting agent instead of soybean oil as epoxide. But has gained much attention in recent years as a renewable oil resource and as a feedstock for the production of biodiesel.

At present, biodiesel is mainly produced by a chemical method. That is, animal and vegetable oil and low carbon alcohol are made to produce ester exchange reaction in the presence of acid or alkali catalyst and certain temperature and pressure to produce corresponding fatty acid ester, which is washed and dried to obtain biological diesel oil. According to different catalysts and reaction conditions, the method is divided into a plurality of categories, namely a, alkaline catalysis ester exchange reaction; b. carrying out acid catalysis transesterification; c. carrying out a transesterification reaction catalyzed by a biological enzyme; d. transesterification without catalysis.

A reed liquid whistle pump is a type of hydraulic cavitation equipment. The earliest emergence in China was the sixty years of the last century, and was introduced from the current Soviet Union. For various reasons, the technology is not popularized and applied in time. In more than ten years, the popularization and application cases related to reed liquid whistle pumps are more and more, and a small number of reed liquid whistle pump products are sold in the market. Reed liquid whistle pump characteristics: simple structure, low cost, large treatment capacity, convenient operation and durability, and is particularly suitable for long-period industrial devices. The ultrasonic reactor is self-made equipment assembled by outsourcing parts. The reed liquid whistle is one of ultrasonic cavitators, which is an acoustic transducer using liquid as power source and has the principle that liquid jet impacts reed at high speed to excite the reed to radiate high frequency or ultrasonic wave to generate cavitation.

The ultrasonic wave is a sound wave with a frequency higher than 20000 hertz, and has good directivity, strong penetrating power, and easy acquisition of concentrated sound energy.

The reed liquid whistle pump or the ultrasonic reactor has different structures and different sound producing mechanisms, but can generate cavitation effect during operation. The partial pressure of the liquid is lower than the corresponding saturated vapor pressure, and vacuoles, cavities or cavities can be formed in the liquid flow. When the cavitation bubbles collapse, extreme physical phenomena such as local high temperature and high pressure, luminescence, shock waves, micro-jet and the like are generated, and the complex fluid dynamics phenomenon is called cavitation.

Cavitation-when ultrasound propagates in a liquid, small voids are created inside the liquid due to the violent vibration of the liquid particles. These small voids rapidly expand and close, causing violent impact between the liquid particles, thereby creating pressures of several thousand to tens of thousands of atmospheres. The violent interaction between the particles can raise the temperature of the liquid suddenly to play a good role in stirring, so that two immiscible liquids (such as water and oil) are emulsified, the dissolution of a solute is accelerated, and a chemical reaction is accelerated. The various effects caused by the action of ultrasound in a liquid are known as cavitation of the ultrasound.

Disclosure of Invention

The invention mainly aims to organically combine the two effects of hydrodynamic cavitation and ultrasonic cavitation of equipment and process the cottonseed oil into the biodiesel in a more simple, convenient, rapid and energy-saving mode. The invention also aims to accelerate the speed of ester exchange reaction, reduce reaction temperature, reduce the dosage of catalyst and improve product yield and product quality.

The technical scheme of the invention is that the method for preparing biodiesel by cottonseed oil adopts organic base as a catalyst, ester exchange reaction is carried out by a one-step method to produce biodiesel, and cavitation equipment, an ultrasonic reactor or more than two stages of cavitation equipment and the ultrasonic reactor are connected in series to strengthen the reaction process; the method comprises the following specific steps: the method comprises the following steps of adding methanol into cottonseed oil serving as a raw material, wherein the ratio of the cottonseed oil to the methanol in oil to alcohol (W/W) is 5-8: 1, the mass of an organic base is 3-8 per mill of the mass of the cottonseed oil, the transesterification reaction temperature is 40-64 ℃, and the reaction time is 10-60 min; during the ester exchange reaction, ultrasonic waves generated by a cavitation device or an ultrasonic reactor are applied to reactants. The ultrasonic wave may be applied to the reactants multiple times during the transesterification process.

The catalyst is organic alkali type, and the most important is common potassium methoxide, sodium methoxide and calcium methoxide. In order to ensure the catalytic effect, the catalyst needs to be prepared on site, the moisture of the reagent needs to be strictly controlled, the moisture is not more than 0.5 percent, and the shelf life of the prepared catalyst is not more than twenty-four hours.

The cavitation equipment is a reed liquid whistle pump 8, the ultrasonic reactor 9 is a plate type or bar type ultrasonic transducer, ultrasonic waves are applied to reactants of cottonseed oil, methanol and organic base for more than two times, and the application time is more than 10 min.

The ultrasonic frequency of the ultrasonic reactor is especially 20-100K. Higher frequencies are also possible.

Cottonseed oil, methanol and an organic base catalyst are respectively and strictly metered, are respectively sent into a preheating (mixing) kettle 7 through pipelines by a cottonseed oil pump 2, a methanol pump 4 and a catalyst pump 6, are then sent to an ultrasonic reactor 9 through a reed liquid whistle pump 8, and are then removed from an esterification kettle 10; after the kettle material is added to a specified amount, the feeding is switched to another esterification kettle connected in parallel; stopping stirring after the materials react in the esterification kettle for 10-30 min, and standing, settling and layering; after 1h, the glycerol was cut tangentially into the crude glycerol receiving tank 11. Further settling and separating to obtain crude glycerol; crude biodiesel with glycerol phase cut off.

The crude biodiesel is sent to a quenching and tempering dealcoholization kettle through a discharge pump 12. The product is subjected to necessary thermal refining treatment, and excessive methanol is recovered.

The oleyl-alcohol ratio (W/W) of the cottonseed oil to the methanol is 6:1, the using amount of the organic base is 3-4.5 per thousand, the preheating temperature is 30-64 ℃, and the stirring speed is 90-120 r/min during esterification.

When the liquid level of the preheating mixing kettle exceeds 50%, starting a reed liquid whistle pump to feed materials to the esterification kettle through an ultrasonic reactor; starting the kettle to stir when feeding; when the liquid level in the esterification kettle reaches 1/4, a valve of a reed liquid removal whistle pump at the bottom of the esterification kettle is opened, a discharge valve of the preheating mixing kettle is controlled, and the materials in the esterification kettle are enabled to circulate outside the esterification kettle and enter the reed liquid whistle pump and the ultrasonic reactor again to carry out secondary cavitation (circular ultrasonic action).

Raw materials are prepared into a feeding kettle (preheating kettle) and then are fed into esterification kettles connected in parallel through a reed liquid whistle pump 8 and at least one stage of ultrasonic reactor 9, a pipeline and a valve are arranged for switching, so that the reed liquid whistle pump 8, the at least one stage of ultrasonic reactor 9 and the inlet and the outlet of each esterification kettle connected in parallel form a circulating pipeline (heat preservation pipeline), the ultrasonic reactor can be arranged in the esterification kettle, and the esterification kettle is provided with a heating control device and a stirring device; at least the first-stage ultrasonic reactor can be a rod-type ultrasonic reactor, the circulation of materials is carried out in a circulation pipeline, and the process is also a process for accelerating the reaction.

The whole process comprises the following processes and process conditions: mixing and preheating raw materials in the first step. The raw materials of cottonseed oil, methanol and organic alkali are conveyed to a preheating mixing kettle by a pump conveying mode, and are preheated and mixed at the preheating mixing kettle. The metering accuracy of the delivery flow is strictly controlled. The accumulated flow and the instantaneous flow are controlled. When the material liquid level in the preheating kettle is close to 50%, the conveying amount of each pump is controlled at 50%.

The oleyl alcohol ratio (W/W) of the cottonseed oil to the methanol is 6:1, the dosage of the organic base is 3-8 per thousand, the preheating temperature is 30-40 ℃, and the stirring speed is 90-120 r/min.

The second step cavitation accelerates the transesterification process.

When the liquid level of the preheating mixing kettle exceeds 50%, the reed liquid whistle pump is started to feed materials to the esterification kettle through the ultrasonic reactor. As the feeding amount increases, the temperature in the esterification kettle gradually rises and needs to be controlled. The kettle was started to stir during feeding.

When the liquid level in the esterification kettle reaches 1/4, a valve of a reed liquid removal whistle pump at the bottom of the esterification kettle is opened, a discharge valve of the preheating mixing kettle is controlled, and the materials in the esterification kettle are enabled to enter the reed liquid whistle pump and the ultrasonic reactor again for secondary cavitation through the external circulation of the esterification kettle. The ester exchange reaction temperature is 40-64 ℃, and the reaction time is 10-30 min.

And when the liquid level in the esterification kettle reaches a specified value, stopping the circulation outside the esterification kettle. The feed was transferred to the next pot. When the operation is switched, the flow of each raw material delivery pump needs to be adjusted timely.

And thirdly, standing and layering to remove byproducts.

When the kettle feed was complete, stirring was continued for 10 minutes (more) and then stopped. And standing for 40-60 min, and cutting off reaction byproducts at the bottom of the kettle. The material is pumped to a quenching and tempering dealcoholization kettle.

And fourthly, the product can be subjected to quality-adjusting dealcoholization.

After the materials enter a kettle for sampling and analysis, a proper amount of auxiliary agent is added according to the splitting result, and then dealcoholization operation is carried out under the negative pressure condition. When the temperature and pressure reach the specified values, the total dealcoholization amount is calculated. Sampling and analyzing, and obtaining a finished product after the product is qualified.

The tiny bubbles formed during the cavitation of the ultrasonic waves greatly increase the contact area between the two phases, and are very beneficial to the generation of interphase reaction. Meanwhile, when cavitation occurs, local high temperature and high pressure are generated due to the fact that micro bubbles are generated and destroyed very quickly, and therefore some harsh reaction conditions can be mild and even the reaction can be carried out at normal temperature and normal pressure. The biodiesel is synthesized by ultrasonic assistance, low-frequency ultrasonic radiation has good emulsification effect on part of compatible liquid systems in a methyl esterification reaction system, and the radiated system can promote the reaction because the grease and the methanol are partially compatible. The cavitation effect and the mechanical mass transfer effect of the ultrasonic wave promote the mutual mixing of alcohol and oil, increase the reaction interface and strengthen the mass transfer effect, the reaction time can be obviously shortened under the assistance of the ultrasonic wave, and the dosage of the alkali catalyst is reduced by 2-3 times. The method for preparing the biodiesel by adopting the ultrasonic process to strengthen and catalyze the grease transesterification has the advantages of simple operation, short action time, high yield, higher purity of the byproduct glycerol and the like. The ultrasonic wave not only shortens the reaction time of producing the biodiesel by the base catalysis, but also improves the molecular structure of the biodiesel and reduces the size of biodiesel molecular clusters, thereby improving the physicochemical property and the combustion performance of the biodiesel product.

In the invention, the effects of the hydrodynamic cavitation and the ultrasonic cavitation equipment are organically combined, so that the cavitation effect is enhanced, the reaction effect is improved, and the remarkable effect is achieved in production.

Has the advantages that: the core of the invention is that the two effects of the hydrodynamic cavitation and the ultrasonic cavitation of the equipment are organically combined, and the cottonseed oil is processed into the biodiesel in a more convenient, faster and energy-saving way. Aims to accelerate the ester exchange reaction, reduce the reaction temperature, reduce the dosage of the catalyst (the dosage is less than half of the prior art) and improve the product yield and the product quality in the production process of the biodiesel. The invention adopts the combination of strong alkali and ultrasound, especially at least two-stage ultrasound action, and has fast reaction speed and energy saving; the reaction temperature is low, and the color value of the product is good; the reaction is complete, the product can meet the quality requirement without washing, distilling and purifying, the reaction efficiency is high, and the comprehensive cost is low; no process wastewater is discharged. The process is reasonable, and the yield is improved. Because the reaction period is shortened, the utilization rate of equipment is greatly improved, and the investment of fixed assets is greatly reduced. The technology can be used for the construction of new devices and is also suitable for the technical transformation of old devices. The product does not need to be washed by water, so that the process wastewater in the whole production process is zero, and the discharge amount of three wastes is very little. The method takes cottonseed oil as a raw material, adopts two technologies of hydrodynamic cavitation and ultrasonic cavitation to carry out organic combination, and produces the biodiesel by a biochemical technology in a more simple, rapid and energy-saving way.

Drawings

FIG. 1 is a schematic diagram of the process and equipment of the present invention.

Detailed description of the preferred embodiments

The following is a further description with reference to examples.