CN104192803A - Sub-boiling distillation method for high-purity hydrochloric acid - Google Patents

Abstract

The invention relates to a sub-boiling distillation method of high-purity hydrochloric acid, which uses hydrochloric acid from a fluorocarbon alkane production device as a raw material, performs membrane distillation operation in a designated sub-boiling distillation device, and controls the preheating temperature, heating temperature and condensation temperature As well as process parameters such as circulation flow rate, high-purity hydrochloric acid with a concentration greater than 35.0% and a metal ion content of less than 1ppb is prepared, and its metal ion indicators meet the Semi-C8 standard proposed by the International Semiconductor Equipment and Materials Organization (SEMI). The invention can solve the problem of removing metal ions in ultra-clean and high-purity hydrochloric acid, and at the same time effectively improve the distillation rate.

Description

A kind of sub-boiling distillation method of high-purity hydrochloric acid

technical field

The invention relates to a sub-boiling distillation method of high-purity hydrochloric acid.

Background technique

Ultra-clean and high-purity reagents (Process Chemicals) are one of the key basic chemical materials in the microelectronics industry, especially in the production process of ultra-large-scale integrated circuits. They are mainly used for chip cleaning and corrosion. Yield, electrical performance and reliability all have a very important impact. Ultra-clean high-purity hydrochloric acid is one of the most demanding ultra-clean reagents and a product with high added value.

The purification technologies of ultra-clean and high-purity reagents include the following: distillation and rectification, isothermal distillation, subboiling distillation, vacuum distillation, sublimation, chemical treatment technology, gas absorption technology, particle control technology, etc. The control indicators of ultra-clean and high-purity hydrochloric acid involve many contents, including concentration, chroma, organic impurities, free chlorine content, acid radical ion content, metal ion content, particle size, etc. Up to now, the effect of no purification technology can meet the requirements of many indicators at the same time, and it is often the comprehensive utilization of multiple purification technologies to achieve the goal. As far as the removal of metal ions is concerned, sub-boiling distillation is generally adopted.

The traditional sub-boiling distillation device is generally made of high-purity quartz material or fluoropolymer material. Its structure is that a condenser tube is obliquely inserted in a large quartz tube closed at both ends, and a U-shaped quartz tube is wound below it. There is an electric furnace wire in the tube for heating. The heater does not directly heat the liquid, but relies on radiation to heat the liquid surface. There are three small holes in the lower part of the distiller, which are used for feeding, overflowing and collecting distillate respectively. The evaporation surface of this sub-boiling distillation method is small, the evaporation rate is slow, and the energy utilization rate is low. It has been reported in the literature that about 200 milliliters of refined nitric acid can be prepared in 8 hours under a heating power of 150W with a traditional sub-boiling distiller; about 1200 milliliters of high-purity water can be prepared in 8 hours under a heating power of 400W, which is mainly due to Limited by heating and evaporation methods.

Other related technologies such as: CN102874757A discloses a preparation method of high-purity hydrochloric acid, using industrial hydrochloric acid as a raw material, and preparing high-purity hydrochloric acid that meets HG/T2778-2009 industry standards through evaporation, ultrafiltration, absorption, sub-boiling distillation and other processes. Pure hydrochloric acid; Henan Chemical Industry [2010, 27 (7), 61-62] through the process improvement of industrial hydrochloric acid preparation equipment, the concentration of industrial hydrochloric acid prepared is greater than 36.0%, Fe is less than 3mg/L; Shanghai Chlor-Alkali Chemical Industry [2006, (1), 13-17] The traditional sub-boiling distillation process was optimized, and the concentration of the prepared hydrochloric acid could reach 36-38%, and the metal ion content was less than 0.1ppb, reaching the requirements proposed by the International Semiconductor Equipment and Materials Organization (SEMI). Semi-C12 standard, but the distillation rate is slower and can only reach 150-200ml/hour.

Contents of the invention

The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a sub-boiling distillation method for high-purity hydrochloric acid.

In order to solve the above technical problems, the present invention adopts the following technical solutions:

A sub-boiling distillation method of high-purity hydrochloric acid, the sub-boiling distillation method is that the hydrochloric acid from a fluorocarbon alkane production unit is preheated by a preheater and enters a distiller, and falling film evaporation is carried out in the distiller, The evaporated steam is condensed in the distiller and collected to obtain high-purity hydrochloric acid, and the unevaporated liquid is pumped into the preheater through a circulation pump, wherein the distiller includes a kettle body with a heating jacket , a seal head arranged on the top of the kettle body, a condenser arranged in the kettle body for condensing the steam, a liquid collector arranged in the kettle body and below the condenser and near the A membrane distributor is provided on the inner wall of the kettle body, and a plurality of discharge holes are opened on the side of the membrane distributor close to the inner wall of the kettle body, and the material of the preheater enters the membrane distributor, Then spray to the inside wall of the still body through the discharge hole to form a film and flow down; the concentration of the high-purity hydrochloric acid is greater than 35.0%, and the metal ion content in the high-purity hydrochloric acid is less than 1ppb, and the preheating of the preheater The temperature is 55-65°C; the heating temperature of the distiller is 65-75°C.

The membrane distributor is an annular pipe that surrounds the kettle body in a circumferential direction, and the gap between the side of the annular pipe that is close to the inner wall of the kettle body and the inner wall of the kettle body is 1-10 mm.

A plurality of discharge holes are evenly distributed on the annular pipe along the length direction of the annular pipe.

The membrane distributor is located above and close to the heating jacket.

The condenser is connected to the head, and the cooling medium inlet pipe and outlet pipe of the condenser pass through the head and extend out of the kettle body; the liquid collector is connected to the body of the kettle The bottom is connected, and the discharge pipe of the liquid collector passes through the bottom of the kettle body and protrudes out of the kettle body.

The liquid collecting port of the liquid collector is located directly below the condenser, and the cross-sectional area of the liquid collecting port of the liquid collecting device is larger than the cross-sectional area of the condenser.

The cooling temperature of the condenser is 0-15°C.

The flow rate of the circulation pump is 0.06×S˜0.3×S, and the unit is m ³ /h, wherein, S is the evaporation area of the distiller, and the unit is m ² . The evaporation area of the distiller is the area of the inner wall of the still body.

In order to ensure the concentration of the product and prevent fouling on the inner wall of the kettle body, the concentration of the hydrochloric acid from the fluorocarbon alkane production device is required to be greater than 33.0%, and the metal ion content in the hydrochloric acid from the fluorocarbon alkane production device is less than 200mg /L.

Due to the implementation of the above-mentioned technical solution, the present invention has the following advantages compared with the prior art:

In the method of the present invention, the material is evaporated in the form of dynamic film formation in the distiller, which can significantly increase the evaporation area, accelerate the volatilization of the steam, and accelerate the evaporation rate, and at the same time collect the evaporated material liquid in the distiller. The concentration of the high-purity hydrochloric acid prepared by the method of the invention is greater than 35.0%, the metal ion content is less than 1ppb, and the index of the metal ion meets the Semi-C8 standard proposed by the International Semiconductor Equipment and Materials Organization (SEMI).

Instructions attached

Fig. 1 is the process flow sheet of sub-boiling distillation method of the present invention;

Fig. 2 is the partial sectional view of the distiller in sub-boiling distillation method of the present invention;

In the figure: 1. Preheater; 2. Circulating pump; 3. Feed pipe; 4. Condenser; 5. Head; 6. Film distributor; 7. Kettle body; 8. Heating jacket; Liquid container; 10, discharge hole.

Detailed ways

The present invention will be described in further detail below in conjunction with specific examples, but the present invention is not limited to the following examples.

As shown in Figures 1 to 2, the process flow chart of the sub-boiling distillation method of the present invention, the material enters the distiller after being preheated by the preheater 1, and performs falling film evaporation in the distiller, and the steam after evaporation is in the distiller The high-purity hydrochloric acid is collected after condensation, and the unevaporated liquid is pumped into the preheater 1 for circulation through the circulation pump 2.

The distiller comprises a kettle body 7 with a heating jacket 8, a head 5 arranged at the top of the kettle body 7, a condenser 4 arranged in the kettle body 7 for condensing steam, and a condenser 4 arranged in the kettle body 7 and located at the condenser. The liquid collector 9 below the device 4, the distiller also includes a membrane distributor 6 arranged near the inner wall of the kettle body 7, and a plurality of discharge holes 10 are provided on the side of the membrane distributor 6 close to the inner wall of the kettle body 7, The material of the preheater 1 enters the film distributor 6, and then is sprayed through the discharge hole 10 to the inner wall of the kettle body 7 to form a film and flow down. The head 5 is connected to the kettle body 7 through a flange or a ground joint.

The membrane distributor 6 is an annular pipe that surrounds the kettle body 7 in the circumferential direction, and the gap between the side of the annular pipe near the inner wall of the kettle body 7 and the inner wall of the kettle body 7 is 1-10 mm. A plurality of discharge holes 10 are evenly distributed on the annular pipe along the length direction of the annular pipe. The size and distribution of the discharge holes 10 meet the requirements of uniform film distribution. The membrane distributor 6 is located above and close to the heating jacket 8 .

The condenser 4 is connected to the head 5, and the cooling medium inlet pipe and the outlet pipe of the condenser 4 pass through the head and extend out of the kettle body 7. Specifically, the condenser 4 can be a double-helical coil condenser; The liquid container 9 is connected to the bottom of the kettle body 7, and the discharge pipe of the liquid collector 9 passes through the bottom of the kettle body 7 and extends out of the kettle body 7. Specifically, the liquid collector 9 can be in the form of a triangular funnel.

Specifically, the liquid collector 9 is located directly below the condenser 4 , and the cross-sectional area of the liquid collecting port of the liquid collector 9 is larger than the cross-sectional area of the condenser 4 .

The sub-boiling distillation method of the present invention will be further described below through specific examples.

Examples 1-7

The raw material hydrochloric acid is hydrochloric acid from the production plant of fluorocarbons. The internal diameter of the still body 7 of the still used is D=500mm, the height of the heating jacket 8 is H=800mm, and the surface area of the inner wall of the still body 7 is S=1.256m ² . The surface area of the inner wall of the body 7 is the evaporation area. Relevant process parameters are controlled. After a fraction is produced, the collected liquid for the first 2 hours is collected separately, and the collected liquid after that is used as a formal product. The relevant implementation data are shown in Table 1 below:

Table 1

As can be seen from the data in the above table, heating temperature, condensation temperature, circulation all have greater influence on the quality and the flow rate of product hydrochloric acid, operate within the implementation process parameter of the present invention, can satisfy hydrochloric acid concentration greater than 35.0% and metal Ions are less than 1ppb requirement.

The sub-boiling distillation method of the present invention can simultaneously solve the contradiction between product quality control and evaporation speed in the sub-boiling, such as:

(1) By accurately controlling the preheating temperature and heating temperature of the material, the high product quality of the sub-boiling distillation is satisfied, wherein the preheating temperature is the heat source temperature of the preheater 1, and the heating temperature is the heat source temperature of the heating jacket 8, specifically Controlled, the temperature of the heat source in the preheater 1 is lower than the temperature of the heat source in the heating jacket 8, and the fluctuation of the temperature of the heat source is controlled not to exceed 0.5°C.

(2) By adding a film distributor in the kettle body equipped with a condenser and a liquid collector, the material is evaporated in the form of dynamic film formation in the kettle body, which can significantly increase its evaporation area, accelerate its steam volatilization, and speed up the evaporation rate.

(3) Through the design of the double-helix coil of the condenser 4 and the temperature control of the cooling medium, the condensation area is significantly increased, the condensation of its steam is accelerated, the condensation rate is increased, and the fluctuation of the temperature of the cooling medium is controlled not to exceed 0.5°C.

(4) By increasing the setting of the circulation pump 2, the materials can be circulated, energy can be saved, and energy utilization efficiency can be improved. The flow rate of the circulation pump 2 should be accurate and can be adjusted according to specific application conditions.

The present invention has been described in detail above, and its purpose is to allow those skilled in the art to understand and implement the content of the present invention, and cannot limit the protection scope of the present invention with this, and the present invention is not limited to the above-mentioned embodiments. All equivalent changes or modifications made according to the spirit of the present invention shall fall within the protection scope of the present invention.

Claims (9)

1. the sub-boiling distillation method of a high purity hydrochloric acid, it is characterized in that: described sub-boiling distillation method is after preheater preheating, to enter distiller from the hydrochloric acid of fluorine carbon alkane production equipment, in described distiller, carry out falling film type evaporation, steam after evaporation is collected and is obtained high purity hydrochloric acid in described distiller after condensation, the liquid not evaporated is pumped in described preheater by recycle pump, wherein, described distiller comprises the kettle with heating jacket, be arranged on the end socket at described kettle top, be arranged on the condenser for steam described in condensation in described kettle, be arranged in described kettle and be positioned at the liquid trap of described condenser below and the film applicator arranging near described kettle inner side-wall, a side near described kettle inner side-wall on described film applicator offers multiple discharge holes, the material of described preheater enters in described film applicator, being ejected into described kettle inner side-wall film forming through described discharge hole again flows down, the concentration of described high purity hydrochloric acid is greater than 35.0%, and in described high purity hydrochloric acid, metal ion content is less than 1ppb, and the preheating temperature of described preheater is 55 ~ 65 DEG C, the Heating temperature of described distiller is 65 ~ 75 DEG C.

2. the sub-boiling distillation method of high purity hydrochloric acid according to claim 1, it is characterized in that: described film applicator be along described kettle circumferential direction around ring pipe, a side of the close described kettle inner side-wall of described ring pipe and the gap of described kettle inner side-wall are 1 ~ 10mm.

3. the sub-boiling distillation method of high purity hydrochloric acid according to claim 2, is characterized in that: multiple described discharge holes length direction along described ring pipe on described ring pipe is uniformly distributed.

4. the sub-boiling distillation method of high purity hydrochloric acid according to claim 1, is characterized in that: described film applicator is positioned at top the close described heating jacket setting of described heating jacket.

5. the sub-boiling distillation method of high purity hydrochloric acid according to claim 1, is characterized in that: described condenser is connected with described end socket, and the cooling medium inlet pipe of described condenser and outlet pipe all stretch out outside described kettle through described end socket; Described liquid trap is connected with the bottom of described kettle, and the discharge nozzle of described liquid trap stretches out outside described kettle through the bottom of described kettle.

6. the sub-boiling distillation method of high purity hydrochloric acid according to claim 1, is characterized in that: the liquid collection opening of described liquid trap be positioned at described condenser under, the cross-sectional area of the liquid collection opening of described liquid trap is greater than the cross-sectional area of described condenser.

7. the sub-boiling distillation method of high purity hydrochloric acid according to claim 1, is characterized in that: the cooling temperature of described condenser is 0 ~ 15 DEG C.

8. the sub-boiling distillation method of high purity hydrochloric acid according to claim 1, is characterized in that: the flow of described recycle pump is that 0.06 × S ~ 0.3 × S, unit are m ³/ h, wherein, evaporation area, unit that S is described distiller are m ².

9. the sub-boiling distillation method of high purity hydrochloric acid according to claim 1, it is characterized in that: the concentration of the described hydrochloric acid from fluorine carbon alkane production equipment is greater than 33.0%, be describedly less than 200mg/L from the metal ion content in the hydrochloric acid of fluorine carbon alkane production equipment.