SU1031476A1 - Method of recuperation of solvents from gaseous mixture - Google Patents

Abstract

1. recovery of solvents from the gaseous mixture, including its absorption through the adsorbent, its vasyschev, evacuating the system, the adsorbent with sorbed paci bite, cooling the desorbed vapors for their condensation and collecting the condensation. SAT, characterized in that, in order to increase the degree of solvent recovery and reduce the cost of the process by reducing energy costs, the adsorbent filled with solvent is evacuated followed by heating it for the temperature, exceeding the condensation temperature of the vapors, dissolve by 15 ° –2 ° C ° C. 2. The method according to claim 1, o, tl and h and y and, with the fact that the adsorbent is saturated with solvent, vacuum to a residual pressure of 1 mm Hg. 3. A device for recovering solvents from a gas mixture, including a body with an adsorbent layer, inlet and outlet pipes, a condensation tube to the amp & measure in the lower part of the shell, and a heat exchanging device, in order to increase the degree removing the solvent, it is provided with a layer of packing of thermal insulation material placed under one of the Ad layers of the adsorbent. to 05

Description

The invention relates to processes for dissolving solvents from a gas mixture and can be used to protect the environment, preferably when extracting volatile solvent vapors from gas emissions from production processes. Methods are known for recuperation of solvent solutions in which the solvent is desorbed from an adsorbent layer in a stream of an inert carrier gas with subsequent condensation in a condenser condenser Til. The disadvantages of these methods are the low degree of condensation of the solvent, as well as the fact that the speed of the desorption process is determined by the speed of the carrier gas and the implementation of the process is associated with significant energy costs. Closest to the present invention is a method for recovering solvents from a gas mixture, including passing it through a layer of carbon adsorbent followed by removing the solvent from the coal layer by heating it with external heaters with a constant evacuation of air and desorbing solvent vapor, followed by cooling the desorbed vapor to condense them and the collection of Concentrate L21. A device is known for recovering solvents from a gas mixture, comprising a housing with a layer of adsorbent branch pipes for introducing and withdrawing phases, a condensing chamber in the lower part of the housing, and a heat transfer device 3. The known method and device is characterized by an insufficient degree of solvent recovery due to the difficulty of condensing volatile solvents such as methylene chloride, freon-113, etc., as well as high energy costs due to the difficulty of rapidly cooling the heat-insulated adsorne. Bera after the regeneration stage. The purpose of the invention is to increase the degree of solvent recovery and to reduce the process by reducing energy consumption. The goal is achieved by the fact that the adsorbent, saturated with solvent, is evacuated with its subsequent heating to a temperature that exceeds the condensation temperature of solvent vapors by 150-2OO C. In addition, the adsorbent, saturated, with solvent, is evacuated to an Ostache pressure of 1 mm Hg A device for carrying out the method of recovering solvents from a gas mixture, comprising a housing with an adsorbent layer, inlet and outlet connections, a condensation chamber in the lower part of the housing and a heat exchange device, is provided with a layer of thermal insulation material placed under the adsorbent layer. According to the proposed method, the evacuation of the system is carried out before the start of the solvent separation without heating the adsorbent. After creating the necessary vacuum, the vacuum pump is switched off and the adsorbent is heated. During heating, the removal of adsorbed vapors from the adsorbent is accomplished due to the difference in pressure of the solvent vapors in the heated adsorber and condenser. The process of desorption and condensation lasts until the vapor pressure of the solvent in the adsorbent becomes equal to the elasticity of its saturated vapor at the condensation temperature. When vacuuming, part of the solvent removes ira coal, but it is very insignificant, since vacuumization is performed briefly, without heat supply and to a relatively high residual pressure in the system of 1.0 mm Hg. The degree of condensation of the solvent in this method is 99%. The drawing shows the device, a general view. The device includes a housing 1 with a layer of adsorbent in the adsorption chamber 2 located above the condensation chamber 3 and separated from it by a layer of a molded nozzle 4 with low thermal conductivity. The adsorption chamber has heating elements 5, whereby the adsorbate can be directly in the housing 1, and can also be placed in cassettes. The use of cassettes is advisable in the case when there are several sources of gas emissions, while the cartridges absorb the solvent in different places and regenerate them in one. Condensation chamber 3 has a coil 6, cooled by tap water. The vacuum pump 7 and the condensate collector 8 are connected to pipelines and to valves 9-12.

The process of vapor recovery of volatile solvents is carried out as follows.

The adsorbent is placed directly in the adsorption chamber. The gaseous emissions containing solvent vapors through the pipeline through the open valve 9 are directed to the condensation chamber 3. The valve 10 is open, the valves 11 and 12 are closed. The vapor-air mixture passes through a condensation chamber 3, in which it is cooled to 5–15 ° C, and enters the aeration chamber 2, filled with activated carbon. The solvent is sorbed with activated carbon, and the purified air through the open valve 10 goes into the atmosphere. The vapor-vapor mixture is passed until a solvent vapor over the layer of coal appears. Then the valves 9 and 10 are closed, the valves 11 and 12 and the vacuum pump 7 are opened, which ensures that pressure in the chambers 2 and 3 is below OD kPa. Then the valves 11 and 12 are closed and the vacuum is switched off.

The gaseous emissions containing solvent vapors pass through the condensation chamber, the herze is cooled to a temperature, and the adsorb is filled with activated carbon. The vapor-air mixture is passed until the solvent overshoots a layer of coal. Then the supply of the vapor-air mixture is stopped and the adsorber is evacuated to a residual pressure of 1 mm Hg. Art. When the device is completely sealed, the adsorbent is heated to a temperature higher than the boiling point of the solvent by 15О2 ° C.

The stripped solvent vapors are fed to a condensation chamber, where they condense. At the same time, the systems establish the saturated vapor pressure of the solvent corresponding to the condensation temperature. At the end of the desorption, the heating of the adsorbent is stopped, the liquid condensate is removed and the coal is cooled. When the temperature drops. coal solvent remaining in the system

Ie, is again sorbed by coal. In the event that the coal is cooled by the cleaned gas-vapor mixture, the effluent must be further cleaned. Thus, in the case of continuous gaseous emissions, continuous cleaning must be provided by at least two devices.

The proposed method will be tested on a vapor-air mixture in which Chladone-113 is used as a low-boiling solvent subjected to recovery. Its concentration in the initial vapor-air mixture is 60 mg / l, the specific feed rate

5 mixture is 0.5 l / min-cm.

Coal saturation is produced up to the prospective COCOOV concentration of freon-113 O, 1 mg / l. The evacuation of the system is carried out before), the remaining pressure

0 1.0 mm Hg Art. The desorption temperature is 2OO-280 ° C.

In tab. 1 shows data on the degree of extraction of solvents from the gas mixture.

five

Comparative data of the effectiveness of the proposed and known method are given in table. 2

From the presented data it follows that the application of the proposed method

0 gives the following advantages in comparison with the known one: the operation time of the vacuum pump is significantly reduced, which provides energy savings; almost complete condensation of desorbed solvent vapors is achieved, while only 7 O% vapor is condensed by a known method | Coal consumption is reduced as there is no need to capture non-condensed

0 vapors, while by a known method an additional amount of adsorbent is required to absorb non-condensable solvent vapors.

five

Thus, the technical and economic effect of the proposed method is due to a higher degree of extraction of solvents from the gas mixture and the cheaper process by reducing

0i energy consumption for recovery.

Table

20О32076, Q 224, ОО, 7О

25О32238.7 283.3О, 88

280319.5 2O, O 299.1O, 94

 Table 2

Claims (3)

1. A method of recovering solvents from a gas mixture, including passing it through an adsorbent bed until it is saturated, evacuating the system, heating the adsorbent with an adsorbed solvent, cooling the desorbed vapors to condense them, and collecting condensate, · sate, characterized in that, for the purpose increasing the degree of extraction of the solvent and reducing the cost of the process by reducing energy consumption, the adsorbent saturated with the solvent is evacuated with its subsequent heating to a temperature higher than the vapor condensation temperature of the solution of Tell at 150-200 ° C. 2. The method according to π. 1, o.t. lichtout and st with the fact that the adsorbent saturated with a solvent is evacuated to a residual pressure of 1 mm Hg. 3. A device for recovering solvents from a gas mixture, comprising a housing with an adsorbent layer, phase inlet and outlet pipes, a condensation chamber in the lower part of the housing, and a heat exchange device, characterized in that, in order to increase the degree of solvent extraction, it is equipped with a nozzle layer of heat-insulating material, placed under the adsorbent layer.