HXD-02超临界细微粒子干燥设备

一、设备简介：
    超临界干燥技术是在干燥介质临界和临界压力条件下进行的干燥,它可以避免物料在干燥过程中的收缩和碎裂, 从而保持物料原有的结构与状态, 防止初级纳米粒子的团聚和凝并, 这对于各种纳米材料的制备极具意义。

    超细微粒，特别是纳米级粒子的研制，在材料、化工、轻工、冶金、电子、生物医学领域得到广泛研究和应用，利用超临界流体制备细微粒子这一技术，可以进行颗粒、微球、微胶囊、多孔材料、脂质体及其它微细材料的加工和制备。
    超细粒子的制备有多种方法，超临界流体沉积技术作为一种高新技术，能够更准确的控制结晶过程，能够生产出平均粒径很小的细微粒子，而且还可控制其粒度尺寸的分布。
    超临界流体沉积技术有以下两种：RESS（超临界溶液快速膨胀）法和GAS（气体抗溶剂结晶）法，由GAS法派生而来的过程有SAS、ASES（PCA）、SEDS等，本设备可进行下列过程的实验：GAS法、ASES法（即PCA法）、SEDS法。
二、原理介绍：
2-1、GAS法主要原理
    当高压气体溶入含有溶质的溶液相内，使其中的溶剂发生膨胀，于是降低了溶质在其中的溶解度，导致该溶质的结晶析出。
2-2、SAS法主要原理
    SAS法工作原理及影响因素与GAS几乎完全一样，只是喷射入溶液中的是超临界二氧化碳，而不是气态CO2。
2-3、ASES法主要原理
    ASES过程即气溶胶溶剂萃取过程，又叫PCA过程，GAS法是将气态CO2喷射入溶液中，ASES过程则与其过程相反，它是将溶液喷射到超临界二氧化碳中。在结晶釜中预先充入一定压力的CO2流体，待结晶釜的压力和温度达到稳定并形成超临界状态后，将一定浓度的溶液通过一喷嘴喷入结晶釜中，形成细小的液滴。
    由于高压CO2与有机溶剂能够互相混溶，一方面CO2迅速地溶入液滴，使之发生膨胀，溶剂的溶解能力迅速降低，另一方面液滴中的有机溶剂也迅速地溶入高压CO2，极短时间内形成极高的过饱和度，使溶质快速地析出，形成极细的均匀的颗粒。如果在有机溶液中预先加入少量的CO2则喷射后会产生多孔性的颗粒。形成的颗粒过滤在结晶釜底部过滤器上，二氧化碳和溶剂的混合流体流出结晶器，进入减压釜进行气液分离。
    在ASES过程中,影响颗粒形态、粒度与粒度分布的操作参数除了温度、压力和溶液初始浓度之外，与RESS过程一样，喷嘴的结构和尺寸对结果有着重要的影响。
    ASES过程与GAS过程不同之处：在ASES过程中颗粒形成与干燥同时进行，形成的颗粒中残余的有机溶剂含量少。而GAS过程的结晶沉淀过程都是在液相中发生的，需要经过长时间的洗涤操作才能得到干燥的固体颗粒。GAS过程操作压力远低于RESS过程，大约10MPa左右。
2-4、SEDS法主要原理
    SEDS过程（超临界流体强化溶液分散的沉淀过程）是将超临界CO2、含有溶质的水溶液和有机溶剂一起喷入结晶器，并经短暂的接触和混合过程。由于有机溶剂大大高于溶质水溶液的流量，使二者接触混合后溶质迅速析出，而高压CO2的流量又大大高于有机溶剂的流量，使溶液和有机溶剂混合后立即被高速喷射的CO2冲散为液滴，与此同时液滴中少量的有机溶剂和水迅速溶于CO2之中，使析出的溶质颗粒得以快速干燥。
三、主要技术参数：
    结晶器工作压力：30MPa
    工作温度：室温～150℃
    结晶器容积：1000mL
    分离器工作压力：10MPa
    分离器容积：1000mL
    制冷量：3300kcal/h
    电源：AC380V    10kW
四、各主要部件性能：
    该装置由以下几部分组成：CO2供应系统、内含溶质的溶液进料系统、有机溶剂进料系统、结晶器、卸压装置、控温系统(采用恒温箱空气浴加热)、安全保护系统组成。
4-1、CO2供应系统
    由CO2钢瓶、净化器、制冷系统、CO2柱塞泵、缓冲罐、预热盘管及相应管阀件组成。
    净化器容积200mL，设计压力8MPa，内部充满分子筛或硅胶，可过滤杂质及水分，内部过滤网目数为400目（相当于38μm）。
4-2、制冷系统
    用于将气态CO2制冷变成液态CO2。便于高压注入和稳定增压，制冷量为3300kcal/h，风冷水循环系统，静音操作。
4-3、CO2柱塞泵
    排出压力为32MPa，流量为10L/h，三柱塞变频调节，合理降低高压输入的脉冲影响，保证产品质量。
4-4、缓冲罐
    主要用于结晶器前CO2的缓冲，降低脉冲影响。容积500mL,工作压力32MPa。
4-5、预热器
    主要用于结晶器前CO2的预热，置于恒温箱中。
4-6、内含溶质的溶液进料系统
    由玻璃杯、柱塞泵及相应管阀件组成。其中柱塞泵：流量为400mL/h,排出压力为32MPa。
4-7、有机溶剂进料系统
    由玻璃杯、柱塞泵及相应管阀件组成，这是为SEDS过程特殊设计。其中柱塞泵：流量为4L/h,排出压力为32MPa。
4-8、结晶器
    容积为1L，入口接有喷嘴，喷嘴用不锈钢制作，激光穿孔，长度与内径之比为15：1，喷嘴内径规格有60μm、80μm、100μm，120μm可根据实验需要选用。
    结晶器内部配置单头喷嘴。单头喷嘴可换不同细微内径的喷嘴。单头喷头结构形式主要在GAS法、ASES法（即PCA法）使用。
4-9、分离器
    容积为1000mL，设计压力10MPa，主要用于气液分离。结构为细长型，便于分离和对液态溶剂的回收。
4-10、恒温箱
    工作室尺寸为500（长）×500（宽）×600（深），采用温控仪控温，恒温箱内装加热器及循环风扇，热交换采用对流和辐射传热，工作室均为不锈钢内胆，设计新颖，外形美观，结构紧凑合理。
4-11、安全保护系统
    为保证系统的安全，我们设计了安全保护系统，主要由电接点压力表和安全阀组成，电接点压力表控制压力源（柱塞泵）的压力，可设定上限压力，可避免超压现象。另外结晶器上安装有安全阀，可实施溢流保护。

I. Brief introduction of equipment:

Supercritical drying technology is drying under the critical and critical pressure conditions of drying medium, which can avoid the shrinkage and fragmentation of materials during drying, thus maintaining the original structure and state of materials and preventing the agglomeration and coagulation of primary nanoparticles, which is of great significance for the preparation of various nano-materials.

The development of ultrafine particles, especially nanometer particles, has been widely studied and applied in the fields of materials, chemical industry, light industry, metallurgy, electronics and biomedicine. The technology of preparing ultrafine particles by supercritical fluid can be used to process and prepare particles, microspheres, microcapsules, porous materials, liposomes and other fine materials.

There are many methods to prepare ultrafine particles. As a high-tech technology, supercritical fluid deposition technology can control the crystallization process more accurately, produce fine particles with very small average particle size, and control their particle size distribution.

There are two kinds of supercritical fluid deposition technologies: RESS (Rapid Expansion of Supercritical Solution) method and GAS (GAS Anti-solvent Crystallization) method. The processes derived from GAS method include SAS, ASES(PCA), SEDS, etc. This equipment can carry out experiments on the following processes: GAS method, ASES method (namely PCA method) and SEDS method.

Second, the principle introduction:

2-1, the main principle of GAS method

When high-pressure gas is dissolved into the solution phase containing solute, the solvent in it expands, which reduces the solubility of solute in it and leads to the crystallization of the solute.

2-2, the main principle of SAS method

The working principle and influencing factors of SAS method are almost the same as those of GAS, except that supercritical carbon dioxide is injected into the solution instead of gaseous carbon dioxide.

2-3, the main principle of ASES method

ASES process is aerosol solvent extraction process, also known as PCA process. GAS method is to inject gaseous CO2 into solution, while ASES process is opposite to its process, which is to inject solution into supercritical carbon dioxide. The crystallization kettle is pre-filled with CO2 fluid with a certain pressure, and after the pressure and temperature of the crystallization kettle reach a stable state and form a supercritical state, a solution with a certain concentration is sprayed into the crystallization kettle through a nozzle to form fine droplets.

Because high-pressure CO2 and organic solvents can be miscible with each other, on the one hand, CO2 quickly dissolves into the droplet, causing it to expand, and the solubility of the solvent is rapidly reduced; on the other hand, the organic solvent in the droplet also quickly dissolves into high-pressure CO2, forming extremely high supersaturation in a very short time, so that the solute can be rapidly precipitated and form extremely fine and uniform particles. If a small amount of CO2 is added to the organic solution in advance, porous particles will be produced after spraying. The formed particles are filtered on the filter at the bottom of the crystallization kettle, and the mixed fluid of carbon dioxide and solvent flows out of the crystallizer and enters the decompression kettle for gas-liquid separation.

In ASES process, besides temperature, pressure and initial concentration of solution, the operating parameters that affect particle morphology, particle size and particle size distribution, like RESS process, the structure and size of nozzle have an important influence on the results.

The difference between ASES process and GAS process is that particle formation and drying are carried out at the same time in ASES process, and the residual organic solvent content in the formed particles is less. However, the crystallization and precipitation process in GAS process takes place in liquid phase, and it takes a long time to get dry solid particles. The operating pressure of GAS process is much lower than that of RESS process, about 10MPa.

2-4, the main principle of SEDS method

SEDS process (precipitation process of enhanced solution dispersion by supercritical fluid) is a process of spraying supercritical CO2, aqueous solution containing solute and organic solvent into crystallizer together, and then contacting and mixing them for a short time. Because the flow rate of organic solvent is much higher than that of solute aqueous solution, the solute is rapidly precipitated after the two are mixed, and the flow rate of high-pressure CO2 is much higher than that of organic solvent, so that the solution and organic solvent are immediately dispersed into droplets by CO2 sprayed at high speed after mixing, and at the same time, a small amount of organic solvent and water in the droplets are quickly dissolved in CO2, so that the precipitated solute particles can be quickly dried.

III. Main technical parameters:

Working pressure of crystallizer: 30MPa

Working temperature: room temperature ~ 150℃

Crystallizer volume: 1000mL

Working pressure of separator: 10MPa

Separator volume: 1000mL.

Refrigeration capacity: 3300kcal/h

Power supply: AC380V 10kW

Four, the main components performance:

The device consists of the following parts: CO2 supply system, solution feeding system containing solute, organic solvent feeding system, crystallizer, pressure relief device, temperature control system (heated by air bath in constant temperature box) and safety protection system.

4-1, CO2 supply system

It consists of a CO2 steel cylinder, a purifier, a refrigeration system, a CO2 plunger pump, a buffer tank, a preheating coil and corresponding pipe valves.

The volume of the purifier is 200mL, the design pressure is 8MPa, the inside of the purifier is filled with molecular sieve or silica gel, which can filter impurities and moisture, and the mesh number of the internal filter screen is 400 meshes (equivalent to 38μm).

4-2, refrigeration system

Which is used for refrigerating gaseous CO2 into liquid CO2. It is convenient for high-pressure injection and stable pressurization, with refrigeration capacity of 3300kcal/h, air-cooling water circulation system and silent operation.

4-3, CO2 piston pump

The discharge pressure is 32MPa, the flow rate is 10L/h, and the three-plunger frequency conversion adjustment can reasonably reduce the pulse influence of high-voltage input and ensure the product quality.

4-4, buffer tank

It is mainly used for buffering CO2 in front of crystallizer to reduce the impact of pulse. The volume is 500mL, and the working pressure is 32MPa.

4-5. Preheater

It is mainly used for preheating CO2 before crystallizer, and placed in a constant temperature box.

4-6. Solution feeding system containing solute

It consists of glass, plunger pump and corresponding pipe valves. Among them, the piston pump: the flow rate is 400mL/h, and the discharge pressure is 32MPa.

4-7, organic solvent feeding system

It consists of glass, plunger pump and corresponding pipe valves, which is specially designed for SEDS process. Among them, the piston pump: the flow rate is 4L/h, and the discharge pressure is 32MPa.

4-8. Crystallizer

The volume is 1L, and the inlet is connected with a nozzle. The nozzle is made of stainless steel and perforated by laser. The ratio of length to inner diameter is 15: 1. The specifications of inner diameter of the nozzle are 60μm, 80μm and 100μm, and 120μm can be selected according to the experimental needs.

A single nozzle is arranged inside the crystallizer. Single-head nozzles can be replaced with nozzles with different fine inner diameters. The structure of single-head nozzle is mainly used in GAS method and ASES method (PCA method).

4-9, separator

The volume is 1000mL and the design pressure is 10MPa, which is mainly used for gas-liquid separation. The structure is slender, which is convenient for separation and recovery of liquid solvent.

4-10, incubator

The size of the working room is 500 (length) ×500 (width) ×600 (depth). The temperature is controlled by a thermostat. The thermostat is equipped with a heater and a circulating fan. The heat exchange adopts convection and radiation heat transfer. The working rooms are all stainless steel liners, which are novel in design, beautiful in appearance and compact and reasonable in structure.

4-11, safety protection system

In order to ensure the safety of the system, we designed a safety protection system, which mainly consists of an electric contact pressure gauge and a safety valve. The electric contact pressure gauge controls the pressure of the pressure source (plunger pump), and can set the upper limit pressure to avoid overpressure. In addition, a safety valve is installed on the crystallizer to implement overflow protection.

南通立凯机电工程有限公司专业设计、制造、销售超临界流体设备和石油科研仪器。产品主要包括：
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