阅读说明：本技术 石蜡通过分子蒸馏提纯得到优质相变原料蜡的方法 (Method for obtaining high-quality phase-change raw material wax by purifying paraffin wax through molecular distillation ) 是由 刘新涛 林俊涛 袁学明 于 2020-12-31 设计创作，主要内容包括：本发明公开了一种石蜡通过分子蒸馏提纯得到优质相变原料蜡的方法,包括以下步骤：(1)在70-100℃条件下,将熔点60-70℃的石蜡熔化,获得液态石蜡；(2)将步骤(1)获得的液态石蜡采用薄膜蒸发-分子蒸馏精制,获得提纯的优质相变原料蜡。本发明利用薄膜蒸发-分子蒸馏结合技术来对石蜡进行提纯,具有操作简单、分子量分布窄、成本低等优势,可获得熔点58-62℃,正构含量≥80％的优质相变原料蜡。(The invention discloses a method for obtaining high-quality phase-change raw material wax by purifying paraffin through molecular distillation, which comprises the following steps: (1) melting paraffin with a melting point of 60-70 ℃ at 70-100 ℃ to obtain liquid paraffin; (2) and (2) refining the liquid paraffin obtained in the step (1) by adopting thin film evaporation-molecular distillation to obtain purified high-quality phase-change raw material wax. The invention purifies the paraffin by utilizing the combination technology of thin film evaporation and molecular distillation, has the advantages of simple operation, narrow molecular weight distribution, low cost and the like, and can obtain high-quality phase-change raw material wax with the melting point of 58-62 ℃ and the normal content of more than or equal to 80 percent.)

1. A method for purifying paraffin wax by molecular distillation to obtain high-quality phase-change raw material wax is characterized by comprising the following steps:

(1) melting paraffin with a melting point of 60-70 ℃ at 70-100 ℃ to obtain liquid paraffin;

(2) and (2) refining the liquid paraffin obtained in the step (1) by adopting thin film evaporation-molecular distillation to obtain purified high-quality phase-change raw material wax.

2. The method as claimed in claim 1, wherein the evaporation temperature of the thin film is 170-250 ℃, the vacuum degree is 10-100Pa, the rotation speed of the scraped film is 100-180rpm, the condensation temperature is 70-90 ℃, and the temperature of the cold well is 10-40 ℃.

3. The method for purifying paraffin wax by molecular distillation to obtain high-quality phase-change raw material wax as claimed in claim 1, wherein the molecular distillation temperature is 180-250 ℃, the vacuum degree is 1-15Pa, the rotating speed of the scraped film is 50-80rpm, the condensation temperature is 70-90 ℃, and the cold well temperature is 10-40 ℃.

4. The method for purifying paraffin wax by molecular distillation to obtain high-quality phase-change raw material wax as claimed in claim 1, wherein the melting point of the phase-change raw material wax is 58-62 ℃, the carbon distribution is C21-C35, and the normal content is not less than 80%.

Technical Field

The invention relates to the field of chemical separation, in particular to a method for obtaining high-quality phase-change raw material wax by purifying paraffin through molecular distillation.

Background

The phase change energy storage material is a substance which changes the state of a substance with the change of temperature and can provide latent heat of phase change. The process of a phase change energy storage material changing from one state to another is called a phase change process, in which the phase change energy storage material absorbs or releases a large amount of latent heat of phase change. As a phase change energy storage material, the material mainly meets the phase change temperature required by practical application, has a large amount of phase change latent heat, stable chemical properties, reusability, small expansibility and contractibility during phase change, good thermal conductivity, high phase change rate, good phase change reversibility, low raw material cost, easy obtainment and the like

The phase-change material can be used for solving the contradiction between heat energy supply and demand imbalance, and is widely applied to the industries and fields of aerospace, energy, buildings, military, refrigeration equipment, communication, electric power and the like. The demand of human beings for energy is increasing day by day, and there is serious waste in the utilization of energy. In recent years, phase change materials have become hot spots in energy utilization and material science research at home and abroad.

Paraffin is a mixture of solid high-grade alkanes, the main component is straight-chain alkane, and a small amount of alkane with individual branch chain and monocyclic cycloalkane with long side chain. The phase-change wax is wax capable of absorbing or emitting a large amount of heat energy when the physical state of the wax is changed. The melting point, the phase transition temperature and the phase transition heat of the alloy material increase along with the increase of carbon number, because the melting needs to overcome intermolecular force and possibly hydrogen bonds, the longer the molecular chain, the larger the intermolecular force, the more energy is needed for melting, and the larger the phase transition heat is.

The paraffin as the phase change energy storage material has the advantages of high phase change latent heat, large heat storage density, no supercooling and precipitation phenomenon, low steam pressure during melting, stable chemical performance, small change of phase change temperature and phase change latent heat after repeated absorption and heat release, no toxicity and corrosivity and low cost. Wide melting point range and wide application. The defects are small heat conductivity coefficient, small density and poor heat storage capacity per unit volume.

The use of phase change to store and release heat is the primary purpose of phase change waxes, so the enthalpy of phase change and how much heat (or density) can be stored per unit volume (or weight) is an important indicator of phase change waxes.

(1) Influence of n-alkane content: the products with high normal content have higher enthalpy in the same rectification range.

(2) Influence of the distillation range on the enthalpy of phase change.

The narrower the molecular weight distribution, the more similar the wax, the better the wax crystallization, the higher the enthalpy. Different molecular waxes are mixed and eutectic, small crystals influence the growth of the crystals, crystal particles are smaller, more oil is contained, and phase change enthalpy is lower.

Although paraffin has many advantages as a phase change material, the use of normal paraffin as an energy storage material has disadvantages: wide boiling range, large phase change temperature difference and the like. Compared with isoparaffin and cycloparaffin, the latent heat of phase change of the normal paraffin is large, so that the production raw material of the phase change paraffin is required to have the characteristics of specific phase change temperature, high normal paraffin content, small phase change temperature difference, large phase change heat and the like. Because the crude oil in China is mostly paraffin-based crude oil and generally contains more normal paraffin, the method is very beneficial to producing the phase-change wax.

Molecular distillation is a liquid-liquid separation technique for separating substances according to different mean free paths of molecular motion of different substances at a certain temperature and vacuum degree, and is distillation in a non-equilibrium state. The molecular distillation technology has the characteristics of high vacuum degree, short heating time, low distillation temperature, good separation effect and the like, and is suitable for separating components with high boiling point, heat sensitivity and easy oxidation. The molecular distillation method can separate paraffin, microcrystalline wax and Fischer-Tropsch wax, and further obtain wax products with higher quality.

CN109988548A high temperature phase change wax and its preparation method, application date: 2017-12-29, applicants: the preparation method of the Inmunogeitai coal-based new material research institute, namely the company Limited comprises the following steps: hydrofining is carried out by taking coal-based Fischer-Tropsch wax as a raw material to obtain Fischer-Tropsch refined wax; preheating the refined wax, then carrying out short-path distillation cutting, and cutting off light fractions; cutting the residual components obtained in the previous step by multistage short-range distillation, and reducing the temperature and/or the vacuum degree step by step to enable the light fraction distilled in the current stage to enter the next stage of short-range distillation for separation; and respectively refining a plurality of heavy fractions which are left in each stage of short-path distillation in the previous steps and have boiling points of 500-650 ℃ at normal pressure and boiling ranges of 40-60 ℃ to obtain the high-temperature phase-change wax. The melting point of the high-temperature phase-change wax prepared by the preparation method is between 80 and 100 ℃, and the enthalpy value is more than 210J/g. The invention has simple production process and relatively high product yield, can realize industrial production and produce high-temperature phase-change wax products.

CN107267212A A separation technology of Fischer-Tropsch synthesis crude products, CN107325838A A separation method of Fischer-Tropsch synthesis crude products, relate to a separation technology of Fischer-Tropsch synthesis crude products, this process includes multiple process steps such as crude oil separation, oil hydrogenation, light hydrocarbon fine separation, wax hydrogenation, wax fine, etc., according to the difference of Fischer-Tropsch synthesis crude product synthesis temperature, can obtain different quantities of naphtha, n-pentane, n-hexane, n-heptane, n-octane, C50, C70, C80 series wax, H1 and H105 series wax, etc. multiple high value-added products, the invention has the advantage of improving the added value of Fischer-Tropsch synthesis crude products, the technological process is simple, easy to realize the commercial process.

CN104673383A and CN104673383B are methods for producing high-melting-point wax from Fischer-Tropsch synthesis products, and relate to a method for producing high-melting-point wax from Fischer-Tropsch synthesis products, wherein a raw material flow firstly enters a first distillation unit, is evaporated at a certain temperature and pressure, and is divided into a wax oil fraction flow and a heavy fraction flow; the heavy fraction stream enters a second distillation unit, evaporation occurs at a certain temperature and pressure, and the heavy fraction stream is divided into a medium-melting wax stream and a high-melting wax stream; the high-melting-point wax material flow and the hydrogen material flow enter a hydrofining unit, and the hydrogenated high-melting-point wax is divided into a first material flow and a hydrogenated high-melting-point wax material flow; the hydrogenated high melting wax stream enters a third distillation unit where it is vaporized at a temperature and pressure to separate the hydrogenated high melting wax stream into a first high melting wax stream and a second high melting wax stream. The invention produces various high-melting-point wax products and solves the problem of over-low color number of the products caused by heating and coking in the separation process of materials.

CN102719266A, CN102719266B heavy oil short-path distillation (molecular distillation) continuous production process, heavy oil molecular short-path distillation (molecular distillation) continuous production process, which comprises the steps of pretreating heavy oil raw materials such as residual oil, wax oil, oil slurry, fuel oil and the like; preheating raw oil, removing water and soluble gas in a degassing drying tower, continuously heating the raw oil, and feeding the raw oil into a rectifying tower to remove light oil. Then the raw material is fed into a first-stage short-path distiller, and the raw oil is heated by heat-conducting oil. Cutting and separating first-stage light phase oil and first-stage heavy phase oil. The first-stage light-phase oil enters a second-stage short-range distiller, and the first-stage light-phase oil is separated to obtain 2# mixed aromatic oil and 3# mixed aromatic oil products; and (3) allowing the first-stage heavy phase oil to enter a second-stage short-path distiller, heating, and separating the first-stage heavy phase oil to obtain 4# mixed aromatic oil and a residual superheavy aromatic product. Compared with the conventional distillation, the production process has the advantages of low operation temperature, low distillation pressure, short heating time, high separation degree, less site and equipment investment and the like.

Disclosure of Invention

The invention aims to provide a method for obtaining high-quality phase-change raw material wax by purifying paraffin through molecular distillation, and the phase-change raw material wax product with the melting point of 58-62 ℃, narrow molecular weight distribution, high quality and low price is produced.

The invention is realized by the following technical scheme:

a method for purifying paraffin wax by molecular distillation to obtain high-quality phase-change raw material wax comprises the following steps:

(1) melting paraffin with a melting point of 60-70 ℃ at 70-100 ℃ to obtain liquid paraffin;

(2) and (2) refining the liquid paraffin obtained in the step (1) by adopting thin film evaporation-molecular distillation to obtain purified high-quality phase-change raw material wax.

Preferably, the thin film evaporation of the step (2) comprises a preheater and a thin film evaporator, and dehydration and pre-fraction removal are carried out. The molecular distillation refining comprises a reheater and a molecular distiller, the light phase substance is evaporated under the condition of high vacuum by the work of a vacuum pump, so that the aim of separating the light phase substance from the heavy phase substance is fulfilled, and then the light phase substance is condensed into liquid and enters a light phase substance collecting system to be used as phase change raw material wax. The heavy phase material enters a heavy phase material collection system.

Preferably, the temperature of the thin film evaporation dehydration and pre-fraction removal is 170-250 ℃, the vacuum degree is 10-100Pa, the rotating speed of the wiped film is 100-180rpm, the condensation temperature is 70-90 ℃, and the temperature of the cold well is 10-40 ℃.

Preferably, the temperature for molecular distillation separation is 180-250 ℃, the vacuum degree is 1-15Pa, the rotating speed of a scraped film is 50-80rpm, the condensation temperature is 70-90 ℃, and the temperature of a cold well is 10-40 ℃.

Preferably, the melting point of the phase-change raw material wax is 58-62 ℃, the carbon distribution is C21-C35, and the normal content is more than or equal to 80%.

The principle of the invention is as follows: the invention creatively purifies and separates the paraffin by adopting a thin film evaporation-molecular distillation refining method to obtain a phase-change raw material wax product with high quality and low price.

Compared with the prior art, the invention has the following advantages: the invention provides a method for purifying paraffin by molecular distillation, which firstly utilizes a thin film evaporation-molecular distillation combined technology to purify paraffin, has the advantages of simple operation, narrow molecular weight distribution, low cost and the like, and can obtain high-quality phase-change raw material wax with the melting point of 58-62 ℃ and the normal content of more than or equal to 80 percent.

Through a production process of thin film evaporation-molecular distillation refining, paraffin with a melting point of 60-70 ℃ is subjected to light and heavy component separation to obtain phase-change raw material wax with narrow molecular weight distribution, and carbon distribution is narrowed from C19-C50 of the raw material to C21-C35. The normal content is improved to more than 80 percent from 60 percent of the raw material. The wax is popular with customers such as the smooth research institute and the like as a high-quality and low-cost phase-change material wax.

Detailed Description

The following examples are given for the detailed implementation and specific operation of the present invention, but the scope of the present invention is not limited to the following examples.

Example 1

The embodiment provides a method for obtaining high-quality phase-change raw material wax by molecular distillation and purification of paraffin, which comprises the following steps:

(1) heating the 68# paraffin to 80-90 ℃ for melting to obtain liquid raw material wax, and preparing to enter thin film evaporation-molecular distillation production for purification.

(2) Performing thin film evaporation-molecular distillation refining on the liquid paraffin in the step (1) by using a wiped film evaporator, wherein the method comprises the following steps:

dehydrating and removing front fraction by adopting film evaporation to obtain front fraction and heavy raw material, and collecting the heavy raw material; the temperature of film evaporation is 180 ℃, the vacuum degree is 20Pa, the rotating speed of film scraping is 150rpm, the condensation temperature is 75 ℃, and the temperature of a cold well is 25 ℃;

separating out light component-phase change raw material wax and heavy component wax by molecular distillation, wherein the molecular distillation temperature is 200 ℃, the vacuum degree is 5Pa, the film scraping rotation speed is 80rpm, the condenser temperature is 75 ℃, and the cold well temperature is 25 ℃.

After molecular distillation, collecting light component-phase change raw material wax and heavy component wax, putting into a transfer storage tank, spraying into granules by a powder spraying bin, and forming to obtain the finished product.

The powder spraying production comprises a blending tank, a temporary storage tank, a material-feeding pump, a filter, a powder spraying bin main body, a material groove and a packaging machine.

The powder spraying bin main body mainly comprises an air filter, a blower, an induced draft fan, a bin body, 100 and 300 nozzles, a sieve plate and the like;

the frequency of the knockout pump is 35Hz, the outlet pressure of the knockout pump is 0.1MPa, the frequency of the induced draft fan is 45Hz, and the frequency of the blower is 45 Hz.

Example 2

The embodiment provides a method for obtaining high-quality phase-change raw material wax by molecular distillation and purification of paraffin, which comprises the following steps:

(1) heating the No. 62 paraffin to 80-90 ℃ for melting to obtain liquid raw material wax, and preparing to enter thin film evaporation-molecular distillation production and purification.

(2) Performing thin film evaporation-molecular distillation refining on the liquid paraffin in the step (1) by using a wiped film evaporator, wherein the method comprises the following steps:

dehydrating and removing front fraction by adopting film evaporation to obtain front fraction and heavy raw material, and collecting the heavy raw material; the temperature of film evaporation is 190 ℃, the vacuum degree is 20Pa, the rotating speed of film scraping is 150rpm, the condensation temperature is 70 ℃, and the temperature of a cold well is 25 ℃;

separating out light component-phase change raw material wax and heavy component wax by molecular distillation, wherein the temperature of the molecular distillation is 220 ℃, the vacuum degree is 6Pa, the rotating speed of a film scraping is 80rpm, the temperature of a condenser is 70 ℃, and the temperature of a cold well is 25 ℃.

After molecular distillation, collecting light component-phase change raw material wax and heavy component wax, putting into a transfer storage tank, spraying into granules by a powder spraying bin, and forming to obtain the finished product.

The powder spraying production comprises a blending tank, a temporary storage tank, a material-feeding pump, a filter, a powder spraying bin main body, a material groove and a packaging machine.

The powder spraying bin main body mainly comprises an air filter, a blower, an induced draft fan, a bin body, 100 and 300 nozzles, a sieve plate and the like;

the frequency of the knockout pump is 40Hz, the outlet pressure of the knockout pump is 0.15MPa, the frequency of the induced draft fan is 50Hz, and the frequency of the blower is 50 Hz.

The invention separates light and heavy components of paraffin with a melting point of 60-70 ℃ by a production process of thin film evaporation-molecular distillation refining to obtain phase-change raw material wax with narrow molecular weight distribution, wherein the carbon distribution is narrowed from C19-C50 of the raw material to C21-C35. The normal content is increased from 60 percent of the raw material to more than 80 percent, and the wax is used as a phase-change material wax with high quality and low price.

The above is a detailed embodiment and a specific operation process of the present invention, which are implemented on the premise of the technical solution of the present invention, but the protection scope of the present invention is not limited to the above-mentioned examples.