RU2320923C2 - Sparging melting furnace for neutralization of toxic substances - Google Patents

Abstract

FIELD: metallurgy; melting furnaces.

SUBSTANCE: proposed sparging melting furnace for neutralization of toxic substance has heat resistant housing with communicating melting chamber and chamber for pyrolysis of substance to be neutralized in mineral melt, device for charging mineral base of melt and substances to be neutralized, at least one submersible gas oxygen burner and bottom part of melting chamber, burner for afterburning of gaseous products of pyrolysis connected to part in pyrolysis chamber, tap hole in near bottom part of housing and channel to discharge combustion products into atmosphere. Furnace is furnished with such vertical heat-resistant partition made of gastight material which is rigidly and hermetically secured in upper part of housing and is provided with lower and upper ports for circulation of melt between melting chamber and pyrolysis chamber. Tap hole is arranged in near bottom zone of pyrolysis chamber. Device for charging mineral base to form melt is made in form of hatch in melting chamber cover. Separate device for charging substance to be neutralized is installed in cover pyrolysis chamber.

EFFECT: increased efficiency of control of mass exchange processes at neutralization of locally accumulated toxic wastes.

7 cl, 1 dwg

Description

The invention relates to the construction of predominantly transportable collapsible bubble-type melting furnaces for the neutralization of toxic substances, at least by pyrolysis in a mineral melt and combustion of gaseous products. The furnaces are mainly intended for processing in storage places of concentrated organic and / or organoelemental chemicals, such as:

herbicides, insecticides, defoliants and other pesticides and similar pesticides in cases when their expiration date has expired,

waste transformer oils and other industrial wastes containing toxic aromatic predominantly multinuclear compounds, etc.,

waste polymers such as polyurethanes, polyvinyl chloride, teflon, etc.

Naturally, the furnaces are also suitable for the processing of other solid and pasty industrial, medical and household waste containing a substantial (usually at least 20% by weight) admixture of carbon-containing substances.

State of the art

It is well known that industrial production and consumption of pesticides is systematically increasing. As modern pesticides with reduced environmental hazard are introduced into the economy, highly toxic pesticides such as DDT (dichlorodiphenyl trichloroethane) remain in warehouses, the use of which is prohibited. Further, there are frequent cases when consumers have unused stocks of pesticides that are subject to destruction due to the expiration date. And, finally, a significant part of toxic substances due to accidents during transportation or careless storage gets into the soil in a concentrated form.

The chemical composition of pesticides and similar toxic substances is very diverse. Accordingly, their chemical neutralization using specific reagents is not economically feasible. Moreover, products of such neutralization often require reliable disposal.

Therefore, toxic substances are usually neutralized by high-temperature pyrolysis in a melt of a suitable inert material, followed by the afterburning of gaseous pyrolysis products and pyrocarbon residues (FR 2170998, US 3946680, DE 2362691 B2, US 4280417, WO 95/14885 A1, GB 2256036 A, EP 076767 A1, EP 076767 A1, EP 076767 EP 0846917 A2, RU 2104445 and many others).

The choice of the type and specific design of the device for pyrolysis depends on the mass of toxic substances that are subject to disposal, and their localization.

So, for the pyrolysis of waste tires with metal cord, household waste located in urban landfills, and waste from large organic synthesis enterprises, it is advisable to build stationary pyrolysis plants with electric furnaces, as provided, for example, in RU 2135896, and preferably with more economical large-sized mine bubble pelvic stoves according to RU 2036384.

If the mass of toxic substances or soil contaminated by them is insignificant (in particular, from several tons to several tens of tons), it is advisable to neutralize them directly in warehouses or in places of pollution.

For this we need transportable collapsible pyrolysis plants.

One of the options for such an installation is known from the Collection of scientific papers of the XIII (annual) international scientific and technical conference "Ecology and human health, protection of water and air pools, waste management", which was held June 13-17, 2005 in Alushta, Ukraine. In the theses of the report Chetverikov V.V., Grinchenko N.N., Olabina V.M. and Maksimuka A.B. “The technology of thermal neutralization of chemical plant protection products unsuitable for use” (see the indicated Collection, vol. 2, pp. 798-801) describes a bubble gas furnace for neutralizing toxic substances. This known furnace, which is closest to the further offered furnace in technical essence, has:

(1) a closed heat-resistant housing, the cavity of which is divided into communicating:

(1.1) a melting chamber (referred to in the report as the “heating zone”) and

(1.2) a chamber (“zone”) for the pyrolysis of neutralized substances in a melt of a suitable mineral or artificial mineral-like material;

(2) at least one means (“chamber”) for loading the mineral base for forming the melt and the substances to be neutralized into the furnace mounted on the housing cover;

(3) at least one immersion (usually gas-oxygen) burner, which is located in the bottom of the melting chamber and serves as a heat source for preparing said melt and maintaining its fluidity;

(4) at least one burner for afterburning gaseous products of pyrolysis (pyrogas), which is connected to a window for their output from the pyrolysis chamber (usually through at least one apparatus for cleaning pyrogas from non-combustible toxic impurities);

(5) a notch, which is located in the bottom of the hull and serves to remove the melt from the furnace (for example, into a granulator);

(6) a channel for the release of combustion products into the atmosphere (usually through at least one apparatus for their final cleaning from non-combustible toxic impurities).

The described bubbling melting furnace, which can be easily manufactured in a collapsible version, in principle provides:

preparation of an inert mineral melt and filling of these two furnace chambers with this melt until a predetermined level is reached;

at least periodically feeding the material to be neutralized into the furnace and pyrolyzing it in a high-temperature mineral melt under conditions of intensive mixing;

selection of pyrogas for subsequent disposal (with preliminary cleaning, if necessary, on additional equipment);

almost complete burning of pyrocarbon residues;

periodic drainage of excess melt, which can be formed due to the assimilation of mineral components of the neutralized material, and almost complete drainage of the melt when the furnace is stopped.

However, the possibility of circulation of the melt between the melting chamber and the pyrolysis chamber and the separation of the fluxes of pyrogas and its products of combustion, which must be removed to the atmosphere, are only mentioned in the cited report without indicating the appropriate means. This is clearly not enough for the effective regulation of mass transfer processes inside a working furnace.

SUMMARY OF THE INVENTION

The basis of the invention is the task of improving the relationship (and interaction) between the melting chamber and the pyrolysis chamber and the location of the loading and unloading means relative to the housing to create such a bubbler melting furnace that would allow more efficient regulation of mass transfer processes in the furnace space and, accordingly, would facilitate the adjustment for processing different chemical composition of toxic substances.

This problem is solved in that a bubbler smelter for the neutralization of toxic substances, having:

a closed heat-resistant casing, the cavity of which is divided into interconnected melting chamber and a pyrolysis chamber of neutralized substances in a melt of a suitable mineral or artificial mineral-like material;

at least one means of loading the mineral base for forming the melt and the neutralized substances in the furnace mounted on the housing cover,

at least one submersible gas-oxygen burner, which is located in the bottom of the melting chamber and serves as a heat source for preparing and maintaining the flow of the specified melt,

at least one burner for afterburning gaseous pyrolysis products (pyrogas), which is connected to the window for their output from the pyrolysis chamber,

a notch, which is located in the bottom of the hull and serves to remove the melt from the furnace, and

a channel for the release of combustion products into the atmosphere,

according to the invention

equipped with an almost vertical heat-resistant partition, which is made of a suitable gas-tight material, is rigidly and hermetically fixed relative to the upper part of the housing and has a lower window and an upper window for melt circulation between the melting chamber and the pyrolysis chamber,

the pyrolysis chamber is equipped with an additional upper notch, which is located below the lower overflow edge of the upper window in a vertical heat-resistant partition,

the bottom of the pyrolysis chamber is located below the bottom of the melting chamber, said tap hole for removing the melt from the furnace is located in the bottom zone of the pyrolysis chamber,

means for loading the mineral base for forming the melt is made in the form of a hatch in the lid of the melting chamber,

and for loading neutralized substances, a separate tool is provided that is installed in the cover of the pyrolysis chamber.

In such a furnace, both during periodic and continuous loading of the neutralized substance, it is possible to create such melt circulation modes that are acceptable for the neutralization of chemicals of different chemical nature. Indeed, in the presence of a vertical heat-resistant partition with two windows, it is not difficult to create a reserve of mineral melt, the mirror of which in stationary mode will be lower than the upper overflow edge of the upper window. Accordingly, each subsequent portion of the neutralized substance will initially come into contact only with the upper layer of the mineral melt, which flows through the upper window from the melting chamber into the pyrolysis chamber and is rapidly decomposed with the release of pyrogas. By adjusting the portion sizes or consumption of the neutralized substance, it is not difficult to ensure the conditions under which the breakthrough of the pyrogas through the upper window in the partition will be practically eliminated and only pyrocarbon can enter the melting chamber together with the circulating melt.

The first additional difference is that the upper window for melt circulation between the melting chamber and the pyrolysis chamber is equipped with a suitable melt flow controller. This allows you to adjust the processing time of the neutralized material in the furnace, taking into account its chemical composition and the characteristics of pyrolysis, even with continuous loading.

The second additional difference is that the specified melt flow controller is made in the form of a rotary or slide gate. This form of execution of the controller is the simplest and most reliable.

The third additional difference is that the lower window for melt circulation has the form of a constantly open gap between the lower end of the vertical heat-resistant partition and the bottom of the melting chamber. This facilitates the dismantling of the partition and the cleaning of the hearth after each next stop of the furnace.

A fourth additional difference is that at least one burner is installed in the lid of the pyrolysis chamber for heating the walls of said chamber before each subsequent start of the furnace. This eliminates the formation of accretions on the walls of the pyrolysis chamber and the deformation of its bore.

The fifth additional difference is that the indicated means for loading neutralized substances, which is installed in the cover of the pyrolysis chamber, consists of a storage hopper, an inlet pipe and a lock. These funds are sufficient for periodic feeding of the furnace with a neutralized substance.

A sixth additional difference is that the indicated means for loading neutralized substances, which is installed in the lid of the pyrolysis chamber, consists of a storage hopper, an inlet pipe and a sector feeder. These funds are sufficient for continuous feed of the furnace with a neutralized substance.

It will be appreciated by those skilled in the art that, when selecting specific embodiments of the invention, arbitrary combinations of these additional differences with the main inventive concept are possible and that the preferred examples described below do not in any way limit the scope of rights of inventors.

Brief Description of the Drawings

Further, the invention is illustrated by a detailed description of the design and operation of a bubbler smelter for the neutralization of toxic substances with reference to the attached drawing, where the proposed furnace is shown in longitudinal section in a vertical plane.

The best options for implementing the inventive concept

The bubbler melting furnace according to the invention has a closed heat-resistant casing 1, the cavity of which is divided by an almost vertical heat-resistant partition 2 into a melting chamber 3 and a chamber 4 for the pyrolysis of neutralized substances in a melt of a suitable mineral or artificial mineral-like material.

The housing 1 has in the plan, as a rule, a rectangular shape and can be equipped with not shown particularly suitable external thermal insulation and / or a water cooling jacket. The principles for selecting such products are well known to those skilled in industrial furnaces.

It is desirable that at least the bottom and walls of the pyrolysis chamber 4 are lined with removable (in cases of major repairs) masonry 5 made of refractory material such as chamotte or dinas. The height of the masonry 5 should exceed the maximum permissible melt level in a working furnace.

The vertical partition 2 is made of a gas-tight material (usually steel) in the form of a hollow box. It has well-known specialists and therefore not shown particularly:

outside - spikes or reefs for fixing the refractory coating (before starting the furnace) or skull (in the stationary mode of operation of the furnace) and

inside - a labyrinth for the circulation of the refrigerant (usually water).

The partition 2 is rigidly and hermetically fixed relative to the upper part of the housing 1 and has two windows 6 and 7 located at different heights for circulating the melt between the melting chamber 3 and the pyrolysis chamber 4.

The window 6 is located in the lower part of the partition 2, as a rule, has the form of a gap between the lower end of the partition 2 and the bottom of the melting chamber 3 and is constantly open.

The window 7 is located in the middle (in height) part of the partition 2 and is equipped with a suitable melt flow regulator, for example, in the form of a rotary (or slide) shutter 8, which is structurally similar to the partition 2.

The pyrolysis chamber 4 has two slots 9 and 10 located at different heights.

The upper notch 9 is usually located below the lower overflow edge of the specified window 7 in the partition 2 and is designed to drain excess melt, which in a stationary mode of operation can be formed in the furnace from mineral impurities to neutralized substances.

The lower notch 10 is located in the bottom zone of the pyrolysis chamber 4 and is designed to discharge the spent mineral melt before stopping the furnace for maintenance or repair or before dismantling the furnace for transportation to another place of operation (in case of exhaustion of the stock of neutralized substance).

At least one (usually gas-oxygen) burner 11 is installed in the middle part of the cover of the pyrolysis chamber 4 not specifically designated, for heating the refractory masonry 5 before each next start of the furnace. A device is mounted on the same lid for a preferably periodic (although possibly continuous) supply of the material to be neutralized into the pyrolysis chamber 4.

Typically, this device takes the form of a storage hopper 12, an inlet pipe 13, and a gateway (or sector feeder) not shown especially with appropriate seals.

One of the walls of the pyrolysis chamber 4 has in the upper part at least one window 14 for outputting gaseous products of pyrolysis (pyrogas) for afterburning directly or through means of additional purification of toxic impurities (not shown, adsorber, absorber, converter, etc.) that can be selected by specialists from among those available on the market.

It is desirable that the bottom of the pyrolysis chamber 4 is lower than the bottom of the melting chamber 3.

In the middle part of the lid of the melting chamber 3, which is not specifically designated, there is a hatch 15 for supplying the solid mineral base of the melt during each subsequent launch of the furnace. At least one (and preferably at least two) submersible gas burners 16 are mounted in the bottom of the melting chamber 3 to melt the mineral base upon starting the furnace and maintain the fluidity of the obtained melt.

The melting chamber 3 is equipped in the upper part of a predominantly one (usually gas-oxygen) burner 17 for afterburning the pyrogas removed from the pyrolysis chamber 4 through the window 14.

The upper part of the space of the melting chamber 3 communicates with the atmosphere through the channel 18 for the release of combustion products obtained during operation of the burners 16 and 17. One skilled in the art will recognize that at least one suitable apparatus for final cleaning of products can be installed, if necessary, at the outlet of this channel 18 combustion from non-combustible toxic impurities.

In a collapsible embodiment of the invention, it is advisable that the melting chamber 3 and the pyrolysis chamber 4 are detachable and have dimensions that are acceptable for road transport.

Toxic substances are neutralized in the described furnace as follows.

When starting the oven:

turn on the burner (or burners) 11 and heat the refractory masonry 5 of the pyrolysis chamber 4 to a temperature of at least 1000 ° C (and preferably at least 1250 ° C),

include immersion gas burners 16 in the bottom of the melting chamber 3,

through the hatch 15 in the lid of the melting chamber 3, as a rule, simultaneously overwhelm the mineral base (for example, blast furnace slag and the like, as a rule, artificial mineral-like silicate-containing materials capable of forming fluid melts),

the hatch 15 is hermetically closed to prevent the emission of melt splashes from the melting chamber 3,

the littered material is melted and the melting chamber 3 and the pyrolysis chamber 4 are filled with the melt to a level slightly exceeding the lower edge of the upper window 7 in the partition 2, and

turn off the burner (or burner) 11 in the cover of the pyrolysis chamber 4.

The resulting melt, the average temperature in the mass of which is usually from 1250 ° C to 1350 ° C, under the action of the gas lift created by the combustion products from the working gas immersion burners 16, begins to circulate between the melting chamber 3 and the pyrolysis chamber 4 through the upper window 7 and the lower window 6 in the baffle 2. The required temperature and melt flow are maintained by regulating the operation of submersible gas burners 16.

If the furnace is equipped with a melt flow controller (in particular, in the form of a rotary damper 8, which is installed in the opening of the upper window 7 in the partition 2), the melt circulation speed is set by changing the position of the damper 8.

In the stationary mode of the furnace, such processes occur.

The substance to be disposed of is periodically (or continuously) fed into the pyrolysis chamber 4 through the storage hopper 12, the inlet pipe 13 and the aforementioned gateway (or sector feeder).

This substance falls onto the surface of a high-temperature melt, intensively heats up to a temperature significantly higher than the temperature of thermal destruction of arbitrary organic substances, and decomposes with the release of pyrogas, the appearance of residual pyrocarbon, and in the case of neutralization of organic-mineral compositions - a mineral residue.

Pyrogas through the window 14 is removed from the pyrolysis chamber 4 and directly (or after preliminary purification from toxic non-combustible impurities) is fed to the burner 17 in the gas space of the melting chamber 3 for direct heat recovery to suppress the formation of impingement at the entrance to the channel 18.

Pyrocarbon and mineral residue are absorbed by the flow of the circulating mineral melt and (with cooling and under the pressure of the “fresh” melt pouring from the upper window 7 in the partition 2) they are entrained in the bottom zone of the pyrolysis chamber 4. Further, the melt enriched with the indicated pyrolysis products through the lower window 6 in the partition 2 flows into the melting chamber 3, where combustion products from the working submersible gas burners 16 are bubbled through it.

the excess oxidizer, which is usually used to burn gas in these burners 16, provides almost complete burning of pyrocarbon,

the heat transferred to the melt by the combustion products sparging through it provides the final melting and assimilation of the mineral residue (with a corresponding increase in the volume and mass of the circulating melt), and

The heated melt in gas-lift mode rises inside the melting chamber 3 above the level of the upper window 7 in the partition 2 and flows through this window 7 into the pyrolysis chamber 4.

Exhaust combustion products generated by submersible gas burners 16 and burner 17 through the channel 18 directly (or through additional treatment equipment) are released into the atmosphere.

As the melt accumulates, its excess can be removed from the pyrolysis chamber 4 without stopping the furnace. For this, it is preferable to use the upper notch 9, although the use of the lower notch 10 and even both notches at the same time is not excluded.

In cases of processing metal-containing toxic waste, the molten metal phase usually accumulates in the bottom of the pyrolysis chamber 4. It is for such cases that furnaces are preferred in which the bottom of the pyrolysis chamber 4 is lower than the bottom of the melting chamber 3.

When stopping the oven:

stop the flow of the neutralized substance into the pyrolysis chamber 4,

block the window 14 output of gaseous pyrolysis products,

open the lower notch 10 and gradually melt the melt from the housing 1 (for example, into a granulator to obtain artificial crushed stone),

after the exit of the melt from the recess 10 is stopped, the supply of combustible gas to the immersion gas burners 16 is stopped and the body cavity is blown out only with an oxidizing agent or other suitable non-combustible gas.

The cooled furnace is ready for maintenance, repair or disassembly for transportation to another place of operation.

The following process is repeated.

Industrial applicability

The proposed furnace can be easily manufactured industrially and in a transportable collapsible version it is effectively used to neutralize local accumulations of toxic waste.

Claims (7)

1. A bubbler melting furnace for neutralizing toxic substances, having a closed heat-resistant casing, the cavity of which is divided into communicating melting chamber and pyrolysis chamber of the neutralized substances in the melt of a suitable mineral or artificial mineral-like material, at least one means of loading a mineral base for forming a melt and neutralized substances into the furnace mounted on the cover of the housing, at least one submersible gas-oxygen burner, which is located in the bottom part the melting chamber and serves as a heat source for preparing and maintaining the fluidity of said melt, at least one burner for afterburning gaseous products of pyrolysis (pyrogas), which is connected to the window for their output from the pyrolysis chamber, a gap, which is located in the bottom part of the body and serves for outputting the melt from the furnace, and a channel for the release of combustion products into the atmosphere, characterized in that it is equipped with an almost vertical heat-resistant partition, which is made of a suitable gas-tight m terial, rigidly and tightly fixed relative to the upper part of the housing and has a lower window and an upper window for melt circulation between the melting chamber and the pyrolysis chamber, the pyrolysis chamber is equipped with an additional upper notch, which is located below the lower overflow edge of the upper window in a vertical heat-resistant partition, the bottom of the pyrolysis chamber located below the bottom of the melting chamber, said tap hole for removing the melt from the furnace is located in the bottom zone of the pyrolysis chamber, a means of loading the mineral base for forming The melt is made in the form of a hatch in the lid of the melting chamber, and a separate means is provided for loading neutralized substances, which is installed in the lid of the pyrolysis chamber. 2. The furnace according to claim 1, characterized in that the upper window for circulating the melt between the melting chamber and the pyrolysis chamber is equipped with a suitable melt flow controller. 3. The furnace according to claim 2, characterized in that said melt flow controller is made in the form of a rotary or slide gate. 4. The furnace according to claim 1 or 2, characterized in that the lower window for the circulation of the melt has the form of a constantly open gap between the lower end of the vertical heat-resistant partition and the bottom of the melting chamber. 5. The furnace according to claim 1 or 2, characterized in that at least one burner is installed in the lid of the pyrolysis chamber for heating the walls of said chamber before each subsequent launch of the furnace. 6. The furnace according to claim 1 or 2, characterized in that said means for loading neutralized substances, which is installed in the cover of the pyrolysis chamber, consists of a storage hopper, an inlet pipe and a lock. 7. The furnace according to claim 1 or 2, characterized in that said means for loading neutralized substances, which is installed in the cover of the pyrolysis chamber, consists of a storage hopper, an inlet pipe and a sector feeder.