CN1938065B - Method for thermochemically neutralizing highly toxic agents - Google Patents

Abstract

The thermochemical neutralization process of the invention comprises: the neutralized reagent is subjected to a multi-stage treatment in a high temperature and high speed gas stream by thermochemical decomposition, additional oxidation and addition of chemical reagents which ensure complete completion of the chemical reactions obtaining the final non-toxic compounds. In at least one process step, the gas stream containing the neutralized reagent is accelerated to a supersonic velocity and subsequently converted to a subsonic gas stream in a shock wave.

Description

Method for Thermochemical Neutralization of Highly Toxic Agents

technical field

The present invention relates to the field of ecology and the neutralization of five toxic substances related to high-hazard categories (i.e. chemical weapons, pesticides, PCBs, cyanides) in a free-flowing state (liquid, powder and gas) reagents and can be efficiently used in technologies aimed at protecting the environment from pollution and conserving resources.

Background technique

Methods for thermochemical neutralization of highly toxic agents are known and described in RF patent 2005519, A62 D 3/00, 1994 [1]. According to this method, by treating the neutralized reagent with a transonic-supersonic gas flow of Mach number M=0.9-2.0 at a temperature ≥ 2,000°K, the neutralized reagent is mixed with a high-temperature gas, and thereafter the excess oxidant coefficient α ≤1.1, burn the resulting mixture in the reaction chamber until the final reaction product is formed, then gradually add the chemical reagent, after the chemical reagent is mixed with the final reaction product, it is discharged into the tank containing the absorbent aqueous solution.

Methods for purifying particulate pollutants from gases are also known and described in RF Patent 2198721, B01 D 47/06, 2001 [2]. The method comprises mixing water jets with a velocity of 20-25 m/s with the gas to be purified to form a supersonic two-phase equilibrium mixture, using compression shock waves obtained by decelerating said supersonic two-phase equilibrium mixture, Instead, it provides cross motion of water droplets containing submicron contaminants. Then, the gas to be purified having an excess steam content is supplied, the excess steam contained in the gas is condensed, and the condensed water is separated.

Contents of the invention

The method of the invention can significantly improve the neutralization quality. It is quantified by the Disintegration and Removal Coefficient (DRC), which requires a coefficient of 99.9 for conventional furnaces and a coefficient of 99.9999 for the destruction of chemical weapons. The method of the invention allows to achieve coefficients of at least 99.9999.

Technical effects of using the method of the present invention include reducing the dispersion of toxic agents that are thermochemically neutralized, increasing combustion efficiency, and eliminating the formation of secondary toxic chemical compounds.

The stated technical effect is achieved due to the fact that the neutralized reagent is subjected to multi-stage treatment in a high temperature and high velocity gas flow having a Mach number M=0.8-2.0 and a temperature of at least 2,000°K. Said multi-stage treatment includes steps of thermochemical decomposition, additional oxidation (combustion) and addition of chemical reagents to ensure complete completion of the chemical reaction to form the final non-toxic compound. In at least one process step, the gas flow containing the reagent to be neutralized is accelerated at least once to supersonic velocity and then transitioned to the subsonic gas flow range in a compression shock wave. According to a preferred embodiment of the method of the invention, the thermochemical decomposition step is carried out at a temperature of from 2,500°K to 3,200°K.

According to another preferred embodiment of the method according to the invention, in each step of thermochemical decomposition, additional oxidation (combustion) and chemical combination, the gas stream containing the reagent to be neutralized is once accelerated to supersonic speed and then compressed in a shock wave Change to subsonic airflow range.

The essence of the treatment method which forms the basis of the method of the present invention is the use of thermochemical methods for the decomposition of complex chemical substances and their mixtures at high temperatures, ie at temperatures ranging from 2,000°K to 3,500°K.

Depending on the nature of the physical and chemical process, thermochemical means are between conventional combustion or pyrolysis at temperatures from 1,200°K to 1,700°K and typical temperature levels of toxic agents in the range from 5,000°K to 10,000°K Moderate heat treatment between plasma neutralization. At the same time, the process of forming the combustion mixture and the mixed combustion products in the method of the present invention differs significantly from conventional methods used in furnaces and plasma reactors.

The main difference is that all physical and chemical processes for neutralizing toxic agents take place in supersonic and near-sonic (M>0.8) high-temperature airflow.

The effect by forcing the high temperature gas flow to accelerate to supersonic velocity and then decelerate to subsonic velocity in the compression shock wave is to ensure a good quality chemical interaction between the chemically active media, one of which is the agent to be neutralized.

According to the known method [2], a supersonic gas flow of a two-phase medium is obtained only due to a significant change in the acoustic properties during the formation of a two-phase mixture with a large liquid fraction, i.e. water, in which the water does not chemically interact, Just acts as a volume filter. Compression shock waves cause the water to break up into droplets and submicron films, and ensure cross-motion of water components with their submicron contaminants, which tends to trap aerosols by water.

Contrary to the known method [2], according to the method of the present invention, the velocity of the high-temperature gas flow is accelerated to the range of 200-1,000 m/s, and the neutralized reagent is destroyed down to the molecular level, while at the same time the highly balanced The deceleration of the uniform gas flow creates a zone of concentrated reaction products, which increases the completeness of combustion and virtually eliminates the formation of secondary toxic chemical compounds.

The high efficiency and thermal intensity of the process, which takes place in the reaction chamber with a heat release volume density of approximately 6,000 MW/m ³ (hundreds of times higher than that of an optimal kinetic (perfectly premixed) burner setup), ensures Very high thoroughness of physical and chemical transformation and mixing of reaction products. The temperature of the reaction product was reduced from 2000°K to 1000°K by rapid cooling (cooling rate ¹⁰⁶ °C/s), which ruled out the possibility of formation of secondary toxic chemical compounds, especially dioxins and furans. In the final step of separating the combustion gases from the less toxic acid-forming chemical compounds, the combustion products, characterized by low levels of harmful impurities, are vented to the atmosphere.

Description of drawings

The present invention will be further explained by preferred embodiments of the present invention with reference to the accompanying drawings, in which:

Figure 1 shows a block diagram for implementing the method of the invention.

Detailed ways

The invention is explained below by means of a specific embodiment of a neutralization plant, the method of the invention being characterized by a description of the operation of said plant.

This illustrative description has only one detailed embodiment of the invention, and the present embodiment should not be considered as limiting all the variations in its application.

The device for neutralizing highly toxic reagents includes: the working gas source 1 of the high-temperature gas generator, the introduction system 2 of the neutralized reagent, the mixing device 3, the reaction chamber 4, the combustion chamber 5, the chemical combination chamber 6 and the chemical reagent feed System 7.

At the outlets of the reaction chamber 4 and the combustion chamber 5 are arranged means 8 for varying the flow rate. The means 8 for varying the flow rate can structurally form part of the reaction chamber 4 or the combustion chamber 5 .

After the chemical binding chamber 6, a final purification system 9, for example in the form of a gas scrubber, a recovery system 10, a solids neutralization and removal system 11, and an exhaust gas system are arranged in sequence

12, and are standard for the technical field of the invention.

The device functions as follows.

A high temperature gas generator is used as the working gas source 1. The working gas is accelerated to supersonic velocity in the nozzle and proceeds into the mixing device 3 . The neutralized reagent introduction system 2 is used to send the container with the neutralized reagent to the mixing device 3, or to introduce the neutralized reagent into the gas flow under a certain time distribution, or to introduce the neutralized reagent Injected into the working air stream. The mixing device 3 is used to mix the reagent to be neutralized with the working gas and feed the resulting mixture into the reaction chamber 4 .

In reaction chamber 4, the gas stream containing the neutralized reagent (if not already accelerated) is at a temperature of 2,500°K to 3,500°K due to the change in the geometrical properties at the corresponding structure of the heat-mass exchange process that occurs during the chemical reaction. Accelerates to supersonic speeds, then transforms the airflow into the subsonic airflow range in a compression shock wave. During said step, the neutralized reagents are destroyed to the molecular level in the compression shock waves provided in the gas stream accelerated to high velocity.

This gas stream is then sent to combustion chamber 5 where it reacts with incoming oxidant at a temperature of approximately 2,000°K. While in the combustion chamber 5, the gas flow containing the agent to be neutralized may also be accelerated to supersonic speed and transformed into the subsonic gas flow range in a compression shock wave.

The gas flow from the combustion chamber 5 is sent to the chemical binding chamber 6 . Depending on the specific chemical composition of the mixture, additional chemical reagents are introduced into the chemical binding chamber 6 via the feed system 7 in amounts that ensure the thoroughness of the oxidation process and the formation of stable species that do not participate in side reactions during cooling.

This non-toxic or low-toxic substance is subjected to multi-stage treatment in systems 9 and 10, then the gas phase is separated from the liquid and solid phases, the latter is also passed through the multi-stage neutralization and removal system 11, and the gas phase is transferred to exhaust system 12.

The achieved technical effect is thus able to significantly improve the neutralization quality of highly toxic agents and provide the level of DRC required for the destruction of chemical weapons.

Claims (1)

1. A method of thermochemically neutralizing a highly toxic agent, according to which the neutralized agent is subjected to a multistage treatment comprising a step of thermochemical decomposition of said neutralized agent, subsequent combustion and The step of adding chemical reagents which ensure the complete completion of the chemical reaction to form the final non-toxic compound, characterized in that all the above-mentioned steps are carried out in a high temperature and high speed working gas flow, and in at least one step of said treatment During, or at each step, the gas flow containing the reagent to be neutralized is accelerated at least once to supersonic velocity and then transitioned to the subsonic gas flow range in a compression shock wave.

Images