RU1768249C - Gas emission treatment method - Google Patents

Abstract

Usage: purification of air contaminated with vapors of organic solvents. SUMMARY OF THE INVENTION: gas emissions are passed through an adsorbent bed, the adsorbent is placed in a removable cartridge. After saturation, the cassettes are transferred to the stripper. The layer is purged with a stream of natural gas with a temperature of 250 ° C to 35 ° C and an overpressure of 0.3-3 T; I. Desbrat is burned with natural gas. 1 s.p. f-ly, 1 ill.

Description

The invention relates to the chemical treatment of exhaust gases. The method can be used in chemical and other industries to purify air contaminated with solvent vapors or other toxic substances.

A known method of adsorption purification of gas emissions, followed by high-temperature combustion of desorbate in the combustion chamber of an industrial boiler plant. According to this method, gas emissions of impregnation-varnishing equipment at a temperature of 20-30 ° C are passed through an adsorbent bed in which the adsorption of combustible impurities occurs. The purified gases are removed from the adsorber to the atmosphere. After the adsorbent layer is saturated with combustible impurities, it is desorbed. Steam is supplied to the adsorbent layer, under the influence of heat of which the adsorbed impurities are desorbed. The desorbate, consisting of combustible impurities and steam condensate (the content of non-combustible substances in the desorbate is 80%), is removed from the adsorber and fed to the boiler plant, where the combustible

impurities are used as fuel. Then, 10-15% of the total amount of flue gases from the boiler plant is fed to the adsorber, where at a temperature of 130 ° C, desorbent combustible impurities remaining in the sorbent layer and adsorbent are regenerated. Desorption and drying products are sent to the combustion chamber, where combustible impurities are burned in the main fuel flare (A. Shelygin, Fundamentals of the technology for thermal neutralization of gas emissions in closed production processes. Overview. Riga: LatNIINTI, 1985, pp. 13-16).

The disadvantages of the known method are the limited scope of application - only in enterprises with a boiler plant, as well as the use of steam for desorption of combustible impurities before burning, during which the steam serves as ballast, which reduces the efficiency of the method.

Of the known technical solutions, the closest in technical essence is the method of purification of air or gas from

, l

Xi

YU

flammable vapor or gaseous pollutants.

In this method, gas emissions are directed to an adsorption filter, after saturation of which the adsorbed impurities are desorbed. An inert gas with a temperature of 500 ° C, obtained by stoichiometric combustion of hydrocarbons, is passed through a saturated adsorbent layer. A desorbate consisting of an inert gas and desorbed combustible vapor or gaseous pollutants is burned in a combustion chamber when air is supplied.

A disadvantage of the known method is the use of an inert gas obtained by stoichiometric combustion of hydrocarbons for desorption of combustible impurities before burning, during which the inert gas serves as ballast, which negatively affects the efficiency of the method.

The aim of the invention is to reduce the content of non-combustible substances in the desorbate and expand the scope of its application.

This goal is achieved by the fact that in the method of neutralizing gas emissions containing toxic combustible substances, including passing emissions through the adsorbent bed, blowing the saturated adsorbent with hot gaseous coolant at 250-350 ° C and burning the desorbate, according to the invention, the adsorbent is placed in a removable cassette, and natural gas is used as a heat carrier. An additional difference lies in the fact that the pressure of natural gas is maintained at 0.3-3 ati.

The drawing shows an installation diagram for implementing the proposed method.

The proposed method is carried out as follows.

The adsorber A is located near the emission sources and is supplied with gas emissions and passed through a layer of adsorbent 1, which is poured into a removable cartridge 2. The purified gases are released into the atmosphere. After saturation of the adsorbent layer, the removable cartridge 2 is removed from adsorber A, immersed in a sealed capsule (not shown in the drawing) and delivered to stripper B located near gas pipeline 3 with a natural gas pressure of 0.3-3 ati.

Then, the adsorbent is regenerated. Natural gas is passed through stripper B, blowing it with an adsorbent layer to displace oxygen from the working volume of the stripper. The purge gases are released into the atmosphere through the candle 12. Purge

lead until the oxygen content in the purge gases is reduced to 2% vol. After purging is completed, heater 4 is turned on, natural gas is heated to

temperature 250 - 350 ° C and pass it through a layer of saturated adsorbent 2, desorbing combustible impurities. A desorbate consisting of natural gas and toxic combustible impurities is cooled in a cooler.

5 to the temperature of the natural gas in the gas pipeline and returned to the gas pipeline 3 intended for gas supply to the boiler unit 6. The desorption of the saturated adsorbent is carried out before being established

desorbate temperature equal to the temperature of the coolant (250 - 350 ° С without taking into account heat losses in the stripper).

Next, the adsorbent is cooled, for which the heater 4 and

continue supplying natural gas until the adsorbent is completely cooled. After the adsorbent has cooled, the gas supply is stopped. The removable cartridge 2 with the regenerated adsorbent is removed from stripper B, immersed in a sealed capsule, returned to the adsorber A located near the gas emission source, and the gas emission cleaning cycle is repeated. To perform the above operations, use pressure regulator 7, shut-off valves 8, 10 , 11, 13 and gas candles 9, 12.

So, in the initial state through the pressure regulator 7, continuous

gas supply to the boiler unit 6. At the same time, both candles 9, 12 are open, ensuring the safe shutdown of the heater 4, stripper B, cooler 5 from the gas pipeline 3, and the valves 8, 10, 11, 13 are closed.

For purging, close candle 9, open valves 8, 10, 11, direct natural gas from gas pipeline 3 to purge heater 4, stripper B and cooler 5 and discharge it into the atmosphere

purge gas through the candle 12. After the purge is completed for desorption, close the candle 12, open the valve 13 and, using the regulator 7, throttle the excess pressure of natural gas in the gas pipeline 3 by an amount that overcomes the aerodynamic drag of the working line including heater 4, stripper B, cooler 5. To implement the method, an excess pressure of natural gas of 0.3 to 3 atm is necessary. Medium and high pressure gas pipelines meet this requirement.

After regeneration of the adsorbent, the valves 8, 13 are closed, candles 9, 12 are opened,

vent the remaining natural gas into the atmosphere and close the valves 10, 11.

Example 1 (prototype). Gas emissions in an amount of 10,000 m3 / h of air containing 0.5 g / m3 of toluene are sent to an adsorption filter and passed through an activated carbon layer of the AP-3 grade. The purified gases are released into the atmosphere. Adsorption lasts 20 hours. After saturation of the activated carbon with toluene (100 kg), the adsorbed impurities are desorbed. 400 m3 / h of inert gas obtained by stoichiometric combustion of hydrocarbons is passed through an adsorbent bed at a temperature of 500 ° C. Desorption lasts 16.6 hours. A desorbate in the form of a mixture of 400 m3 / h of inert gas and 6 kg / h of toluene (the concentration of toluene in inert gas is 15 g / m3, the content of non-combustible substances in the desorbate is 99%) is burned in a combustion chamber air supply. The degree of purification in this way is -95 -98%.

Example 2 (the proposed method). The facility where the source of emissions is located does not have a boiler plant or a combustion chamber.

Gas emissions in an amount of 10,000 m3 / h of air containing 0.5 g / m3 of toluene are fed to an adsorber A located near the emission source, vi is passed through an activated carbon layer of grade AP-3, which is poured into a removable cartridge 2. The purified gases are discharged into the atmosphere. Adsorption lasts 20 hours. After saturation of activated carbon with toluene (100 kg), the removable cartridge is removed from adsorber A, immersed in a sealed capsule (not shown in the drawing) and delivered to stripper B located near gas pipeline 3 with a natural gas pressure of 1 atm. The gas pipeline is intended for gas supply to the boiler plant 6, which consumes 12000 m3 / h of natural gas.

A removable cartridge with a saturated adsorbent is installed in a stripper B equipped with a heater 4, a cooler 5, valves 8,10,11,13 and gas candles 9, 12. The desorption mode is started by purging the working line to displace oxygen from the volume of the heater, stripper and cooler. To purge, close candle 9, open valves 8, 10, 11, and direct natural gas from gas line 3 to candle 12. Purge until the oxygen content in the purge gases drops to 2% by volume.

After the purge is completed, close the candle 12, open the valve 13 and use the regulator 7 to throttle the excess pressure of natural gas by an amount

providing the consumption of natural gas through stripper B in an amount of 600 m3 / h, and equal to 1 atm. The main flow of natural gas, in this example 11400 m3 / h, continues to flow through gas line 3 directly to the boiler unit 6. Turn on the heater 4, heat natural gas in it to a temperature of 300 ° C and pass it through a layer of saturated

adsorbent. Desorption lasts 16.6 hours, after which the temperature of the desorbate at the outlet of the stripper reaches 300 ° C (excluding heat loss). During the entire desorption period, the desorbate is cooled in

cooler 5 and returned to the gas pipeline 3 after pressure regulator 7, the cooled desorbate in the form of a mixture of 600 m3 / h of natural gas and 6 kg / h of toluene (the concentration of toluene in the gas is 10 g / m, the content of non-combustible substances is less than 10%) served along with the main stream of natural gas through a gas pipeline 3 to a boiler plant 6 for combustion.

After the end of the desorption, turn off

preheater 4 and continue to supply natural gas until the adsorbent bed is completely cooled and dried. The regeneration of the adsorbent is continued for 0.5 hours. Then the valves 8, 13 are closed, open

candles 9, 12 for venting natural gas residues into the atmosphere and close the valves 10, 11. The removable cartridge 2 with the regenerated adsorbent is removed from stripper B, immersed in an airtight

capsule and returned to the adsorber A, located near the source of gas emissions. The degree of purification according to the claimed method is 99%.

The proposed method allows to expand the scope of its application in any enterprise where there are gas emissions containing toxic combustible substances, as well as reduce the content of non-combustible substances in the desorbate by more than

8 times.

Claims (2)

1. A method of neutralizing gas emissions containing toxic combustible substances, including passing emissions through an adsorbent bed, purging a saturated adsorbent with a gaseous heat carrier at a temperature of 250-350 ° C and burning desorbate, characterized in that, in order to reduce the content of non-combustible substances in the desorbate and expanding its scope, the adsorbent is placed in a removable cartridge, and natural gas is used as a heat carrier. 2, The method according to claim 1, characterized in that the overpressure is 3 of these. support equal to 0.3 2.c / 77 & tЈЈG -osse / b: Boz & a / p, C / t / Ufrsf b, f Ґ L 2 & 3 & gas height. o & ctooci, /