WO1992016599A1

WO1992016599A1 - System for the treatment by thermolysis of solid products whose rejection is harmful to the environment

Info

Publication number: WO1992016599A1
Application number: PCT/FR1992/000250
Authority: WO
Inventors: Pierre Chaussonnet
Original assignee: Societe Française De Thermolyse
Priority date: 1991-03-20
Filing date: 1992-03-19
Publication date: 1992-10-01
Also published as: JPH06506246A; CA2105289C; ATE113309T1; EP0505278B1; DE69200560T2; DE69200560D1; CA2105289A1; JP2869188B2; RU2097402C1; FR2674149B1; EP0505278A1; ES2062871T3; FR2674149A1; DK0505278T3

Abstract

A system for the treatment of solid products whose rejection is harmful to the environment is comprised of a reactor integrating successively a dehydration zone (1) and a thermolysis zone (2), characterized in that said reactor has, downstream of the thermolysis zone (2), a cooling zone (3) and in that the dehydration zone is provided with a fluid-tight inlet gate, the cooling zone is provided with a fluid-tight outlet gate, and lock chambers isolate the thermolysis zone (2) from the dehydration zone (1), on one hand, and from the cooling zone (3) on the other hand, in order to limit the air entering the thermolysis zone during the introduction of the products and during the extraction of residues, said thermolysis zone (2) being provided with a gas extraction line which maintains it in negative pressure conditions.

Description

System for the thermolysis treatment of solid products the rejection of which is harmful to the environment

The present invention relates to a system for the thermolysis treatment of solid products, the rejection of which is harmful to the environment.

Traditionally these products are either stored or treated by incineration. In the first case the potential danger remains and can worsen possible pollution of the groundwater. In the second case, the temperatures of the incineration treatment are high and cause rapid wear of the equipment and a high operating cost; moreover, the gaseous products of the incineration treatment are discharged into the atmosphere before any control, which does not make it possible to give all the guarantees required as to the non-pollution of the environment. Document FR-2.106.844 discloses a garbage processing device comprising a succession of zones of increasing temperatures (up to 800-1300 ° C) which are passed through the garbage after packaging in a container. porous coating material; this garbage is gradually freed of its water vapor and then pyrolyzed. However, this solution requires still high temperatures, which again leads to rapid wear and a high operating cost.

The object of the invention is to overcome the aforementioned drawbacks by allowing treatment by thermolysis at medium temperature, around 600 ° C. for example all

IS LYING by allowing continuous monitoring of decomposition products.

The invention thus provides a system for the treatment of solid products, the rejection of which is harmful to the environment, comprising a reactor successively integrating a dehydration zone and a thermolysis zone, characterized in that this reactor comprises downstream of the thermolysis zone, a cooling zone and in that the dehydration zone is provided with a sealed entry door, the cooling zone is provided with a sealed exit door, and airlocks isolate the thermolysis area on the one hand with respect to the dehydration zone, on the other hand with respect to the cooling zone so as to limit the entry of air into the thermolysis zone during the introduction of the products and during the extraction of the residues, this thermolysis zone being provided with a gas extraction line thanks to which it is under vacuum.

The aforementioned areas are therefore separated into isolated rooms.

According to preferred arrangements of the invention which may be combined:

- the thermolysis zone is maintained without free oxygen,

- the thermolysis zone is at a temperature between 400 ° C and 750 ° C and at a pressure less than or equal to 800 millibars.

According to other preferred arrangements of the invention:

the products to be treated are introduced into the reactor in carriages which pass successively from the dehydration chamber to the thermolysis chamber and from the thermolysis chamber to the cooling chamber using a mechanical system of the pinion type, and rack for example, or even of the electromagnetic drive type. The carts are designed so that solid residues

- glasses, metals, rubble for example - remain in the carriages while being easily removed after cooling at the outlet of the cooling chamber,

- the dehydration chamber and the thermolysis chamber are heated by thermoreactors also called catalytic radiant panels supplied on the one hand with pure oxygen or air and on the other hand with pyrolysis gas originating from thermolytic decomposition as well as by resistors electrics placed inside the chambers or glued to the walls outside the chambers, - the carbon dioxide and water vapor generated in the oxidation of the pyrolysis gases in the catalytic radiant panels help to warm up by convection and radiation of products,

- the pyrolysis gases formed in the thermolytic decomposition as well as the catalytic oxidation gases formed in the catalytic radiant panels are cooled and purified at the outlet of the reactor in a gas washer where the condensation of the water, the separation of noncondensable gases and condensed heavy hydrocarbons, the halogen and sulfur compounds are eliminated in the washer by dissolution in the washing water,

- the gas flow at the outlet of the reactor entrains the coal formed in the thermolytic decomposition towards the scrubber where it is cooled,

- the heavy hydrocarbons and the coal are recovered by decantation of the washing water at the outlet of the washer in a decanter,

- the gas flow at the outlet of the washer is sucked by a vacuum pump,

- the gases at the outlet of the vacuum pump are sent to a washer containing for example an aqueous solution of potassium carbonate, where carbon dioxide is eliminated, - the pyrolysis gases purified from halogenated, sulfur-containing compounds and carbon dioxide are used in the heating the reactor and the excess is set aside for later use,

- Control of the kinetics of thermolytic transformation in the thermolysis chamber is obtained by regulating electric heating and catalytic heating by implementing conventional systems for measuring temperatures and regulating gas and Electric power.

Objects, characteristics and advantages of the invention appear from the following description, given by way of nonlimiting example, with reference to the appended drawings in which:

- Figure 1 is a plan view of a system according to the invention, - Figure 2 is an elevational view of an inlet portion of the oven of this system,

FIG. 3 is a cross-sectional view thereof along line A-A of FIG. 2, and

- Figure 4 is an enlarged view of the connection of a panel 4 to its support.

Figure 1 shows the block diagram of the system and Figures 2 to 4 show some constructive details.

The system according to the invention comprises a reactor integrating in a single device a chamber 1 for introducing the products to be treated and in which these products are undergoing dehydration, a thermolysis chamber 2 in which the products, partially or completely dehydra¬ tees, are brought to the thermal decomposition temperature, for example around 600 ° C (typically between 400 ° C and 750 ° C) and a cooling chamber 3 where the solid residues of the heat treatment are brought to an ordinary temperature.

The thermolytic transformation in the reactor is advantageously carried out in the total absence of free oxygen at an average temperature of 600 ° C. The decomposition products - incondensable gases, heavy hydrocarbons, coal - are continuously monitored at the outlet of the system and are possibly recycled for further treatment. Operation at this temperature does not induce marked wear of the system, the service life of which is thus extended and the operating cost reduced.

The chambers are insulated from one another in a substantially sealed manner, by guillotine doors 23 actuated by jacks; the door between chambers 1 and 2 and the door between chambers 2 and 3 are vertically movable in watertight housings, the crossing of the lifting cylinders being by cable gland. In addition, watertight doors are provided at the entrance to chamber 1 and at the exit from chamber 3, whereby the dehydration and cooling zones are, as desired, isolated from the outside and / or the thermolysis zone 2; they can be movable vertically or horizontally or around a joint according to the dimensions of the reactor, the space available and the free choice of the designer.

It will be appreciated that the seal provided by the entry and exit doors is between the outside and zones 1 and 3 of moderate temperatures, much lower than those of chamber 2.

The introduction of the products and the extraction of the residues are thus carried out, to avoid the entry of air into the chamber 2, by airlocks which alternately isolate the dehydration chamber from the thermolysis chamber when necessary. the products in the dehydration chamber and the thermolysis chamber of the cooling chamber when the residues from this third chamber are extracted.

Chambers 1 and 2 of the reactor are lagged (item 27) to limit heat loss. The chambers 1 and 2 are provided with heating means of all suitable known types, two examples of which are given under references 4 and 5. The temperature of the chamber 2 is for example maintained around 600 ° C. while that of the chamber 1, lower, is maintained above 100 ° C., for example around 120 ° C.

Catalytic radiant panels 4, provided with incorporated resistors 25 intended for their temperature setting to allow the phenomenon of catalytic oxidation of feed gas, are represented on the ceiling of chambers 1 and 2 but can also be placed on the walls side. These panels are placed in watertight housing vis-à-vis the outside. The detail of FIG. 4 shows the principle of fixing a panel 4 on the internal wall of the reactor and the position of a seal identified 26 put in place to force the gaseous supply mixture (preferably oxygen, pyrolysis gas) to pass through the catalytic panel 4 where it is oxidized. Chamber 3 can be equipped with a system (not shown) for cooling solid residues and recovering heat by heating the gases which supply the catalytic radiant panels.

Electric resistors 5 are supplied from a transformer 6; these resistances are shown here inside the reactor, stuck to the wall

(but can be put outside), the power supply being made using waterproof bushings.

Chamber 2 is kept under vacuum, typically at a pressure less than or equal to 800 mbar, or even 500 mbar. Preferably, the same pressure prevails in chambers 1, 2 and 3.

The gas mixture extracted from chamber 2 goes into a gas washer 9 opening into a decan¬ tation block 13 and supplied with cold water by a basin 14 where the water at the outlet of the decantation tank 13 is treated by methods classics of water chemistry. Hydrocarbons condensed and the carbon separated from the aqueous phase in the tank 13 are sent to a storage tank 17 where they will be taken up for use.

The non-condensed gases at the outlet of the tank 9 are sucked in by a pumping group 10, the discharge of which flows into a washing tank 11 where the carbon dioxide is eliminated by adding potassium carbonate, for example, in the water coming from the tank. 14. On leaving the tank 11, the purified gas is compressed by the compressor 12 and stored in a tank 16.

This compressed gas is here sent to the catalytic radiant panels 4 after passing through a mixer 15 which also receives compressed air from any source at 18, or alternatively, depending on the application, pure oxygen coming from a outdoor storage. The gas mixture passes through a recuperator 7 where it is heated in order to improve the thermodynamic balance of the catalytic oxidation. FIG. 1 indeed shows an exit of the catalysis gases from the chamber 1; these gases, essentially composed of carbon dioxide and water vapor from dehydration and catalytic oxidation, pass through the recuperator 7 where they are cooled. They are sucked up by a pumping group 8, the discharge of which flows onto a chimney 19.

FIG. 2 shows a carriage 20 in which the products to be treated are placed; the carriage passes from one room to another via a rack and pinion system 21.

A drive shaft 22 ensures the synchronized movement of the carriages. The gases are extracted from chambers 1 and 2 by flues 24 located at the end of the chambers and on the floor so as to entrain the coal in the gas flow.

Gas washers are a product of classical chemical engineering. The system described above offers the following advantages: - it is applicable to any quantity of products by varying the section of the reactor or the length of the reactor, either by placing as many reactors in parallel as necessary,

the system according to the invention makes it possible to treat the products to be eliminated under good conditions for the protection of

The environment,

- the products of thermolytic decomposition are purified of all contaminants and can be checked before any subsequent use. The waters of the aqueous phase are treated by conventional methods after decanting the hydrocarbons and coals. The various inert materials - glasses, metals, etc. - can be recycled under the best possible sanitary conditions. The heavy metals not vaporized in the thermolyser will be recovered in the trolley after cooling, the heavy metals vaporized will be recovered in the foot of the washer or in the basin for treating the settling water.

Finally, the system according to the invention allows excellent energy recovery with the possibility of storing the recovered energy in the form of coal and hydrocarbons, possibly of transporting it for consumption at the appropriate place and time.

It goes without saying that the above description has been offered only by way of nonlimiting example and that numerous variants can be proposed by those skilled in the art without departing from the scope of the invention.

Claims

CLAIMS 1. System for the treatment of solid products, the rejection of which is harmful to the environment, comprising a reactor successively integrating a dehydration zone (1) and a thermolysis zone (2), characterized in that this reactor comprises downstream of the ther¬ molyse zone (2), a cooling zone (3) and in that the dehydration zone is provided with a sealed entry door, the cooling zone is provided with a sealed exit door , and airlocks isolate the thermolysis zone (2), on the one hand with respect to the dehydration zone (1), on the other hand with respect to the cooling zone (3) so as to limit the entries of air in the thermolysis zone during the introduction of the products and during the extraction of the residues, this thermolysis zone (2) being provided with a gas extraction line thanks to which it is under vacuum.

2. System according to claim 1, characterized in that the thermolysis zone (2) is maintained without free oxygen.

3. System according to claim 1 or 2, characterized in that the thermolysis zone (2) is at a temperature between 400 ° C and 750 ° C and at a pressure less than or equal to 800 millibars.

4. System according to any one of reven¬ dications 1 to 3, characterized in that the products are carried by carriages (20) moved through the reactor by a mechanical assembly (21) such as rack and pinion.

5. System according to any one of claims 1 to 4, characterized in that the dehydration chamber (1) and the thermolysis zone (2) are heated by heating means comprising catalytic radiant panels ( 4).

6. System according to claim 5, characterized in that the catalytic radiant panels are supplied at least in part by the gases taken from the thermolysis zone.

7. System according to claims 5 and 6, characterized in that the carbon dioxide and water vapor generated in the catalytic oxidation participate in the heating of the products to be treated by convection and radiation.

8. System according to any one of reven¬ dications 1 to 7, characterized in that the thermolysis gases formed in thermolytic decomposition and the gases formed in catalytic oxidation are cooled and purified in gas washers where will be eliminated halogen, sulfur and carbon dioxide compounds.

9. System according to claim 8, characterized in that the gases at the outlet of the scrubbers are sucked by vacuum pumping groups.

10. System according to any one of Claims 1 to 9, characterized in that the control of the kinetics of the thermolytic transformation is obtained by the regulation of the electric heating and of the catalytic heating by the implementation of the conventional systems of measurement of temperatures and regulation of gas and electric current flows.