RU223285U1 - DEVICE FOR PRODUCING HIGH-PURITY SULFURIC ACID BY SURFACE EVAPORATION METHOD - Google Patents

Abstract

The utility model relates to the field of isolation of high-purity substances and is intended for carrying out a continuous process for producing sulfuric acid, which can be used in various industries, for example, in micro- and nanoelectronics. A device for producing high-purity sulfuric acid by the method of surface evaporation of an azeotropic solution consists of a tubular evaporator with a feeder, a collector, drainage of the bottom residue outside the evaporator into a buffer tank and a coaxially located tubular condenser and is characterized by the fact that the feeder is a conical coupling with a core ground to each other , between which the separators are located, while the lid fixes the feeder core and the condenser, the lid also contains a filler fitting for the initial acid solution, while the condenser is a sleeve with a vapor cut-off soldered to it, in which the cooling water input-output port is fixed using a mushroom seal liquid, while the condensed liquid is removed from the evaporator into a separate buffer tank. The technical result of the utility model is to simplify the design of the device, increase the purity of the target product and increase the productivity of the device. 4 ill., 2 ave.

Description

The utility model is intended for carrying out a continuous process for producing high-purity sulfuric acid by the method of surface evaporation of an azeotropic solution; it belongs to the field of high-purity substances and can be used in various industries.

High-purity sulfuric acid is one of the main components of the chemical industry, in particular in micro- and nanoelectronics. Distillation of sulfuric acid of azeotropic composition in order to increase the degree of its purification is an important stage in the technology of its production.

A device is known [Patent RU 200426 U1, publ.: 10.23.2020] for purifying acids by distillation, consisting of a container for the distilled liquid with vertical side walls, a refrigerator body with vertical side walls, located on top of the container for the distilled liquid to form a closed container, a ring-shaped condensate collector located along the perimeter on the inner wall of a closed container between the container for the distilled liquid and the refrigerator body, a refrigerator casing covering the refrigerator body from its outer side. The supply of distilled acid is carried out through a funnel and a tube located along the axis of a known container. From below, the container for the distilled liquid is heated by an IR heater and heats the acid to boiling point. The design of the refrigerator body with vertical side walls allows the evaporated liquid after condensation to flow straight down into a ring-shaped condensate collector with its subsequent discharge into a separate tank. Common to the known and claimed devices is the presence of a separate container for collecting condensate, the elimination of metal elements and the vertical design of the device.

A significant disadvantage of the known device is that the liquid purification process is based on the volumetric boiling method, which is implemented during conventional distillation. Another disadvantage is that using the conventional distillation method does not allow for deep purification of the feedstock from impurities. It is known that one of the main reasons limiting the purity of the product during conventional distillation is aerosol entrainment [Sterman J., Williamson G. Gas purification processes for air pollution control in “Gas Purification Processes”. Ed. by G. Honhebol, London, Newnes-Butterworth, 1972, 697 p.]. One way to prevent this effect is to limit the rate of evaporation of liquid in the cube and the rate of steam through the apparatus, which brings the effective separation coefficients closer to the equilibrium ones, which, as a rule, are very high.

The solution to these requirements is surface distillation, which consists of transferring a liquid from its free surface into the vapor (vapor-gas) phase, followed by condensation of the resulting vapor. Unlike conventional distillation, during surface distillation there is no boiling of the liquid, which is accompanied by the formation and collapse of bubbles of saturated steam. The absence of bubble collapse reduces the likelihood of the formation of microscopic drops of the original liquid near the evaporation surface and, as a consequence, their physical entrainment by the steam flow and subsequent contamination of the distillate. Thus, by surface distillation, which involves the evaporation of a liquid without boiling, it is possible to obtain sulfuric acid of a higher degree of purity.

A known device [CN 107515148 A, publ.: December 26, 2017] for producing high-purity sulfuric acid by surface distillation, consisting of a vertical body containing in its upper part a condenser in the form of a cone, the top of which is located above a funnel for receiving condensed acid, condensed acid is removed outside the known device and collected in a separate container, the supply of initial sulfuric acid is carried out through a receiving hole in the lid of the known device. The supply of initial sulfuric acid into the body of the known device occurs up to a specified volume, after which it is heated to a temperature below the boiling point, evaporated and the condensate is collected. Common to the known and claimed device is the operating principle based on the method of evaporating the purified sulfuric acid without boiling, as well as collecting condensate in a separate container outside the device and the possibility of obtaining high-purity sulfuric acid; there is a container for collecting the bottoms residue.

The known device has a number of disadvantages: the area of evaporation of sulfuric acid is very limited, which leads to low productivity of the known device; when heated, a temperature gradient is created in the volume of sulfuric acid, which leads to different rates of evaporation from the surface of sulfuric acid. The text of the description of the known device does not explicitly indicate its mode of operation, but, based on the description of its design, it can be assumed that the known device operates in a periodic mode. In this case, its disadvantages should also include lower productivity compared to continuous operation, time-varying technological parameters, and the need to periodically clean the apparatus itself from accumulated impurities.

Distillers according to patent CN104958918 (published: 10/07/2015) and application US2020055745 (published: 02/20/2020) have similar disadvantages. The latter describes a gradient distiller, the operation of which is based on the surface evaporation method. The known distiller consists of a condensation pipe, an evaporation surface, a heating device, a liquid distributor, a tail liquid trough, a condensate trough, a tail liquid pipe, a liquid supply pipe, a condensate pipe and a casing. The liquid raw material is preheated in the condensation tube, flows down the evaporation surface after further heating in the heating device, and is continuously evaporated. With a constant decrease in temperature, steam condenses on the surface of the condensation tube, the heat of condensation preheats the feed liquid in the condensation tube, and the flow direction of the liquid feed in the condensation tube is opposite to the direction of flow on the surface of the evaporator tube. The performance of distillation apparatus depends on the evaporation surface area of the distilled liquid; the larger it is, the higher the performance. An increase in the surface area of liquid evaporation can be achieved by using tray or packed columns, cooling towers and other structures that distribute the liquid flow over a large solid surface and/or directly increase the free surface of the liquid. In most of these methods, the free surface of the liquid ruptures, resulting in contamination of the product with the starting material. The most promising devices for solving these problems are film-type distillation devices; laminar flow of a liquid film without breaks is technically feasible in them. Reducing the thickness of the heated layer of liquid helps to reduce temperature differences across its thickness.

Among the film-type devices that take into account the advantages of the mentioned devices for distillation, the device [CN204034298U, publ.: December 24, 2014], which is the closest analogue of the claimed device, is known. The known device is a container made of quartz glass with a capacitor in the form of a double spiral tube located along the axis of this container. A uniform supply of the source liquid is carried out using an annular pipe with inlet holes with a diameter of 1-5 mm along its entire length. An annular pipe is located along the wall of the said container, which ensures a film flow of the liquid to be cleaned along the inner surface of the container. The condensed liquid is received in its lower part, the condensate is removed outside the distillation device into a separate container and again supplied to the device for subsequent heating.

What is common to the known and claimed device is that the purification of the source liquid involves the use of the surface distillation method, the evaporation of the liquid occurs at a temperature below its boiling point, the supplied liquid in the form of a film flows down the inner wall, heats up and evaporates, the location of the condenser in the center of the device along its axes

The technical problem of the prototype is that the film mode of flow of the purified source liquid is realized at a certain distance from the inlet holes, which requires additional use of structural materials to increase the height of the known device, and as a consequence, the rise in cost of the device, and the design of the capacitor in the form of a spiral creates difficulties in its manufacturing and maintenance: cleaning and repair. The lack of selection of the bottom residue does not allow the purification process of the feedstock to be carried out in a continuous mode, since as the feedstock evaporates, the concentration of highly volatile impurities in it will increase, and their concentration in the distillate will also increase. The known device, chosen as a prototype, involves the use of a sulfuric acid solution of arbitrary concentration as a feedstock for surface distillation. This feature does not allow the process to be carried out at the optimal boiling point of the initial liquid medium, which can negatively affect both the performance of the known device and the purity of the distillate.

The purpose of a utility model is to eliminate the technical problems of the prototype.

The technical result of the utility model is to increase the achievable purity of the distillate, as well as the productivity of the device through the use of a continuous operating mode without boiling. Also, the utility model has a simpler design.

The specified technical result is achieved due to the fact that a device is claimed for producing high-purity sulfuric acid by the method of surface evaporation of an azeotropic solution, consisting of a tubular evaporator with a feeder, a collector, drainage of the bottom residue outside the evaporator into a buffer tank and a coaxially located tubular condenser, characterized in that the feeder consists of a conical coupling with a core grounded to each other, between which there are separators, while the lid fixes the feeder core and the condenser, the lid also contains a filler fitting for the initial acid solution, and the condenser is a sleeve with a vapor cut-off soldered to it, in which is secured with a mushroom seal to the coolant input/output port, while the condensed liquid is discharged from the evaporator into a separate buffer tank.

The utility model is illustrated by drawings.

In FIG. Figure 1 shows a device for producing high-purity sulfuric acid by surface evaporation of an azeotropic solution.

In FIG. Figure 2 shows the device of a capacitor.

In FIG. Figure 3 shows the arrangement of the oil port.

In FIG. Figure 4 shows the feeder device.

In the drawings: 1 - evaporator, 2 - condenser, 3 - feeder, 4 - manifold, 5 - outlet, 6 - cover, 7 - sleeve, 8 - steam cut-off, 9 - oil port, 10 - distributor, 11 - inlet pipe, 12 - outlet pipe, 13 - body, 14 - flange, 15 - outlet pipe, 16 - supply pipe, 17 - vacuum pipe, 18 - coupling, 19 - core.

Implementation of a utility model

Cleaning is carried out in a continuous stationary mode.

The initial aqueous solution of sulfuric acid of azeotropic composition is supplied to the feeder container 3 (Fig. 1), in which the specified level and temperature of the liquid are maintained. Flowing through a given gap between the core and the coupling, the solution hits the wall of evaporator 1. The speed of the flow leaving the feeder is finely regulated by the temperature of the feeder and the liquid level in the feeder container. The initial rough adjustment of the flow rate is made by changing the gap between the core and the coupling by selecting spacers of the required thickness. The film of sulfuric acid solution, flowing down the wall of evaporator 1, evaporates and gradually heats up to operating temperature. At operating temperature, the evaporation rate is maximum. As the film drains and evaporates, it decreases in thickness and, entering the cold area at the bottom of the device, collects at the bottom, forming a bottom residue. The bottom residue flows through outlet 5 into the receiving buffer tank. The evaporator is heated from its outside by a four-zone resistive heater.

The acid vapor, together with the heated air flow, rises along the wall of the evaporator 1 (Fig. 1) to the steam cutoff 8 of the condenser 2 (Fig. 2), where partial condensation occurs. Next, the vapor-gas mixture falls down with steam condensation on the surface of the sleeve 7. In the lower part of the device, the vapor-gas mixture with the remainder of the steam is heated again, and the cycle is repeated. Thus, the vapor-gas mixture forms a closed flow that transfers acid vapor from the evaporator 1 (Fig. 1) to the condenser 2. The film of purified sulfuric acid from the condenser enters the collector 4 and is removed from the device into a receiving buffer tank.

The presence of a cut-off valve 8 (Fig. 2), which provides a closed flow of the vapor-gas mixture in the claimed device, helps prevent steam condensation in the upper part of the evaporator near the feeder, as well as on the lid of the device. Steam condensation on the evaporator 1 near the feeder 3 can significantly reduce the performance of the claimed device, and condensation on the lid can lead to contamination of the condensate due to interaction with the materials of the sealing rings.

The condenser (Fig. 2) consists of a sleeve 7 with a vapor cut-off valve 8 soldered to it. In the sleeve 7, an oil port 9 is secured with a mushroom seal for coolant input/output. The oil port (Fig. 3) consists of a distributor 10, inlet 11 and outlet 12 nozzles, a housing 13 with a flange 14, outlet 15 and supply 16 pipes, as well as a vacuum nozzle 17, used during the initial filling of the coolant.

The main adjustable parameters of the process are the operating temperature of the evaporator, the temperature and flow rate of the coolant, as well as the flow rate of the initial solution of sulfuric acid of azeotropic composition, which can be regulated within narrow limits by the pump flow and within wide limits by the gap between the coupling 18 and the core 19 in the feeder (Fig. 4). Another important parameter is the angle between the axis of the device for producing high-purity sulfuric acid by surface evaporation of an azeotropic solution (Fig. 1) and the gravity vector, which should be close to zero.

Preferably, heating of the evaporator 1 (Fig. 1) is provided by a four-zone heater.

Preferably, the main material for the manufacture of parts in contact with a solution of sulfuric acid at high temperatures is optical high-purity quartz glass of the KV brand. Parts of evaporators, feeders, and condensers are made from it.

Preferably, the parts of the condenser cooling circuit are made of M1 grade copper and L63 grade brass.

Preferably, the seals of the connections in contact with the sulfuric acid solution are made of fluorine rubber and porous F-4 (POROFLEX material). Gaskets for connections operating at high temperatures are made from the same materials.

Preferably, parts in contact with a solution of sulfuric acid, or exposed to its drops, at temperatures below 250°C, are made of fluoroplastic F-4 and F-50. The connecting pipelines for acid and the reactor cover are made from these materials.

A significant difference of the claimed device for producing high-purity sulfuric acid by the method of surface evaporation of an azeotropic solution is the increase in the achievable purity of the distillate, as well as the productivity of the device through the use of a continuous mode of operation of the device and the possibility of flexible adjustment of the parameters of flow and evaporation of the film of the initial solution of the acid of azeotropic composition. Another significant difference between the claimed device is the ability to significantly simplify and reduce the cost of the technology, as well as the ability to scale.

An example of producing high-purity sulfuric acid by surface evaporation of an azeotropic solution using the claimed device is discussed in Example 1 and Example 2.

Example 1.

Set the gap between coupling 18 (Fig. 4) and core 19 in feeder 3 (Fig. 1) to 80 μm. Capacitor 2 (Fig. 1) is filled with cooling silicone oil SO-704 and argon. Set the temperature of the feeder tank 3 to 100°C, the outlet temperature of feeder 3 to 200°C, and the temperature of the evaporator working area to 1-315°C. Heat the coolant oil to a temperature of 160°C, gradually increasing its flow rate to 45 ml/s. The initial solution of sulfuric acid of azeotropic composition is fed into the feeder container 3 (Fig. 1) with a flow rate of 0.2 g/s.

After reaching a certain liquid level in the feeder tank 3, the flow of sulfuric acid solution becomes stationary. The film of the acid solution flows down the wall of the evaporator 1, gradually heats up to the operating temperature set in the heater zones of the claimed device, and evaporates. As the film of the sulfuric acid solution drains and evaporates, it decreases in thickness and, entering the cold region at the bottom of the claimed device, collects at the bottom, from where it flows through outlet 5 into the receiving vessel for the bottom residue.

The sulfuric acid vapor, together with the heated air flow, rises along the wall of the evaporator 1 to the steam cutter 8 (Fig. 2), where partial condensation occurs, cools and falls down, turning into condensate on the condenser wall. In the lower part of the device, the vapor-gas mixture with the remaining steam is heated again and the cycle is repeated. Thus, the vapor-gas mixture forms a closed flow in the claimed device, transferring acid vapor from the evaporator 1 (Fig. 1) to the condenser 2. The condensate film enters the collector 4 and is discharged from the device into the receiving vessel.

The product is an aqueous solution of high-purity sulfuric acid with a concentration of ≥ 98 wt.% and a flow rate of 0.075 ml/s.

Example 2.

Set the gap between coupling 18 (Fig. 4) and core 19 in feeder 3 (Fig. 1) to 80 μm. Capacitor 2 (Fig. 1) is filled with cooling silicone oil SO-704 and argon. Set the temperature of the feeder container to 100°C, the temperature of the outlet from the feeder to 3-250°C, the temperature of the working area of evaporator 1 (Fig. 1) to 320°C. Heat the coolant oil to a temperature of 180°C, gradually increasing its flow rate to 50 ml/s. The initial solution of sulfuric acid of azeotropic composition is fed into the feeder container 3 (Fig. 1) with a flow rate of 0.2 g/s.

After reaching a certain liquid level in the feeder tank 3, the flow of sulfuric acid solution becomes stationary. The film of the acid solution flows down the wall of the evaporator 1, gradually heats up to the operating temperature set in the heater zones of the claimed device, and evaporates. As the film of the sulfuric acid solution drains and evaporates, it decreases in thickness and, entering the cold region at the bottom of the claimed device, collects at the bottom, from where it flows through outlet 5 into the receiving vessel for the bottom residue.

The sulfuric acid vapor, together with the heated air flow, rises along the wall of the evaporator 1 (Fig. 1) to the steam cutoff 8 (Fig. 2), where partial condensation occurs, cools and falls down, turning into condensate on the condenser wall. In the lower part of the device, the vapor-gas mixture with the remaining steam is heated again and the cycle is repeated. Thus, the vapor-gas mixture forms a closed flow in the claimed device, transferring acid vapor from the evaporator 1 (Fig. 1) to the condenser 2. The condensate film enters the collector 4 and is discharged from the device into the receiving vessel.

The product is an aqueous solution of high-purity sulfuric acid with a concentration of ≥ 98 wt.% and a flow rate of 0.1 ml/s.

Claims (1)

A device for producing high-purity sulfuric acid by the method of surface evaporation of an azeotropic solution, consisting of a tubular evaporator with a feeder, a collector, drainage of the bottom residue outside the evaporator into a buffer tank and a coaxially located tubular condenser, characterized in that the feeder is a conical coupling ground to each other with core, between which the separators are located, while the lid fixes the feeder core and the capacitor, the lid also contains a filler fitting for the initial acid solution, while the capacitor is a sleeve with a vapor cut-off soldered to it, in which the input-output port is secured using a mushroom seal coolant, while the condensed liquid is removed from the evaporator into a separate buffer tank.