EP0795594B1 - Plant for the environmentally friendly thermal treatment of industrial, hospital, domestic and the like waste - Google Patents

Description

The present invention relates to an installation implementing a process for heat treatment of industrial and hospital waste, household and similar, at low temperature and under partial vacuum, whether are in solid, liquid or gaseous form.

The techniques currently used require either a preliminary sorting products that involve risks for personnel, i.e. specific conditioning, i.e. a transfer, therefore a maneuver, in course of treatment. In addition, in a closed process, even at low temperature, the cycle time is very significantly extended by the phase cooling of the solid secondary material which penalizes all the more the profitability of the installation. On the other hand, the gases from the treatment must be vacuumed by a pumping unit and for this beforehand cooled. The equipment installed upstream of the vacuum pump can clogging or, if the gas bubbling technique is used in water, it is brought to an excessive temperature which makes it unsuitable to its rejection without further treatment. In case the products are treated by incineration, i.e. at high temperature, the products gases are discharged into the atmosphere which does not give any guarantee in terms of environmental protection. European patent EP-A-0505278 describes a system for the thermolysis treatment of solid products of which the release is harmful to the environment.

The system which is the subject of the present invention claims to remedy to these disadvantages.

The products are distilled by heat treatment, at 500 ° C and partial vacuum (100 mb). This process accelerates decomposition organic matter by facilitating molecular bursting and avoids default oxygen self-combustion. The added or substituted atoms, in ionized (gaseous) form, are treated by neutralization. At the end decomposition of organic products, due to heat treatment, the products are transformed into gas, hydrocarbons, coal.

The installation, according to the present invention, is composed of the assemblies as defined in the wording of the dependent claim.

Dependent claims 2 and 3 contain embodiments particular features of the invention.

The products to be treated are deposited, without prior sorting or packaging in a collection bucket (1/1) which is introduced into an enclosure distillation (2/1). This is closed hermetically, then purged of its atmosphere by a pumping group (9/1), the heating (board 2/3) is then put into service for a free rise up to 150 ° C. This temperature will be maintained for 30 minutes which constitutes the dehydration level and vaporization of certain products. At the end of this stage, the rise temperature is resumed up to 500 ° C, at this level it is maintained during one hour. At the end of this period the oven (3/1) is moved to put the speaker in the open air and thereby accelerate its cooling which can be improved by precipitation of water. During the thermal cycle (plate 2/3) the gases are sucked in by a group pumping (9/1) through a condenser (7/1) and discharged into a washing column (10/1) to remove halogens. They are taken back and tablets for storage for later use.

The aqueous phase of the washing column and the condensates are adjusted in "pH" and precipitated in a settling tank (15/1) to recover the hydrocarbons in suspension, then filtered. After analysis, the waters are either reused by the installation itself or discharged into the sewer (22/1) for the rest.

After release of the mobile oven (3/1), as soon as the temperature of the enclosure distillation (2/1) is lowered to a value below 80 ° C a signal warns the plant operator of the end of treatment and the possibility of unloading.

The collecting bucket (1/1) is then extracted from the enclosure (2/1) and placed on a rocker which will pour its solid stream onto a conveyor (23/1). The solids will be sorted for recovery or landfill without harm to the environment.

The installation according to the invention implements the equipment described hereinafter.

Heat treatment equipment that includes collection bins (1/1), two sealed distillation chambers (2/1) and the oven itself says (3/1).

• accélération du refroidissement des produits traités par mise à l'air libre de l'enceinte de distillation et précipitation d'eau,
• possibilité de mettre en chauffe une enceinte pendant le refroidissement de l'autre et ainsi augmenter le rendement du matériel.

The oven is of the "rolling vault" type (see plate 3/3) whose mobility represents the following advantages:

• acceleration of the cooling of the treated products by venting the distillation chamber and precipitation of water,
• possibility of heating one enclosure during the cooling of the other and thus increasing the efficiency of the equipment.

The collection bins (1/1) are bins made of stainless steel sheet can be mounted on engineered pads allowing their grip by an elevating machine, or on cast iron wheels for a manual handling when the mass of the products to be treated is low. The blanks of the bins are equipped with an axis of rotation for their tilting during unloading. The bins receive directly, without sorting or handling human, therefore without risk for the operator, the products to be treated.

The distillation chambers (2/2) are parallelepiped boxes stainless steel closed at one end by a watertight door fitted with a metal structure seal. The door pivots on an axis to come and run parallel to the facade of the enclosure on which it is pressed by a system with cleats and wedges biased. The pregnant are located face to face, separated from each other by a loading table. They rest on cradles placed on the floor of the oven. Inside, andirons in the form of raceways, rails or trays, receive the collection bucket. A stainless steel tube opening at a low point in the enclosure will connect it to the extraction system distillation gases. During precipitation cooling water will be collected in a receptacle located under the enclosure.

The oven (3/1) consists of a casing, of welded construction, in trade sheet and profiles. It circulates on rails, of an enclosure to the other, by means of two motorized rollers and free rollers. It is closed at both ends by so-called "guillotine" doors operated by winches. The high position of the doors allows the movement of the oven. In the low position the doors are pressed on the facades by a cylinder system. Plating the doors authorizes heating. The casing and the doors are thermally insulated by a lining of ceramic fibers. The electric heating of the oven is ensured by resistant elements, formed in waves, in Nickel / Chromium alloy. A turbine recirculation will ensure forced convection of ambient air. The power supply of the heating elements, the turbine and the operating devices are made by a bundle of festoon-mounted cables to follow the movements of the oven. The heating regulator is a thyristor power unit. The two oven bases are bases made of refractory concrete placed directly on the floor of the room.

According to the invention, the distillation gas treatment system contains the main elements described below.

The condenser (7/1) has two functions: trapping condensable gases and cool the incondensable gases before their aspiration.

The device consists of a waterproof stainless steel container in which plates are arranged in baffles. These plates, presenting a large heat exchange surface, are kept at low temperature by circulation of water, previously chilled (14/1), in coils soldered on.

The pumping group (9/1) consists of a rotary piston pump without lubrication and a menbran pump. Upstream of the group is installed a particle filter (8/1).

The washing column (10/1) is in the form of a sealed silo stainless steel in which a constant water level is maintained. According to the invention, the gases discharged by the pumping unit are conveyed in a sheath, comprising a washing ramp forming a film of water, which dives below the level of the water table. The gases are therefore washed by precipitation and bubbling.

At the outlet of the washing column the gases are taken up and compressed (11/1) for storage (12/1) for later use.

The different elements described above are linked together by stainless steel sheaths, large enough to avoid clogging and facilitate maintenance. Solenoid valves allow the automation of the operation of the installation from information given by measuring, control and analysis.

The water requirements of the installations are as follows: cooling water condenser plates, level maintenance in the washing column, the water precipitated on the distillation chamber to be cooled, the water from washing of premises and equipment. By cons we recover some amount of water after condensation of the vapors from the enclosure distillation. The liquids to be treated come from the condenser, the gas washing column, collection of premises clean water and materials. The condenser cooling water is clean and to the advantage to be refreshed. The enclosure cooling water is also clean but can be loaded with dust, it will be filtered (17/1) before being switched back on. The essential components water treatment system are: the tank intended to preserve the correct amount of water (13/1), the appliance for cooling the plates condenser (14/1), the washing column (10/1), the drain pan decanting of hydrocarbons (15/1), the oil storage tank (16/1), the system driven by the results of the addition analyzes of washing liquid to the waters to be neutralized. This system is classic to water chemistry and is not the subject of a particular description.

On the one hand, the residual solid elements are discharged onto a conveyor (23/1), on the other hand, for coals, sucked up (24/1) and put in silo (25/1). Heavy materials returned clean are sent to sorting (26-27-28-29 / 1) classic for the recovery industries.

The follow-up and the management of the exploitation are ensured, in a way continuous, by a set of devices whose choice and redundancy guarantee the reliability of the operation of the installation.

According to the invention, there are four types of measurements to be made: the operating measures which trigger the different phases of the security measures to protect the equipment and therefore personnel, the quality measures to guarantee and demonstrate respect for the environment, profitability measures installation.

The measurements are carried out by probes or sensors which are associated to monitoring or control apparatus. In addition, certain measures deemed essential, are archived in graphic form or in alphanumeric messages. This archiving ensures maintenance assistance of materials and the conservation of the treatment history. Management of the entire installation is entrusted to a programmable controller, real-time or delayed measurement monitoring is ensured by a system computerized visualization.

The operating measurements relate to: the internal temperature of the distillation chamber which is taken into account by a regulator / programmer which itself controls the power unit to thyristors, the value of the depression in the enclosure that triggers the start-up of the heating system, the flow of aspirated gases, the temperature upstream of the pumping unit, the level of liquids collected at the base of the condenser, the level in the washing column, the rate of filling tanks.

The safety measures concern: the temperature of the heating elements of the oven to avoid overheating detrimental to the performance of the equipment over time, the internal pressures of the condenser and the washing, the gas flow rates at the inlet and outlet of the condenser, the refrigeration temperature of the condenser plates.

Quality measures concern: analysis of noncondensable gases, analysis of recycled water, analysis of the local atmosphere, temperature and flow of water to be discharged to the sewer.

The profitability measures concern: the weight of the products to be treated, consumption of electrical energy and consumption of city water. These measures will make it possible to establish an operating balance sheet.

Claims (3)

1. Facility featuring a heat low temperature and partial vacuum treatment for industrial, hospital, household and similar waste, whether they be solid, liquid or gas, achieving higher environment protection than standard provisions.
   The facility includes the following distinctive features

   a mobile heat processing furnace moving from one sealed cell to the other (3/1)

   two sealed distillation cells (2/1)

   a distillation gas condenser (7/1)

   a vacuum unit for both sealed cells (9/1)

   a non condensable gas (10/1) cleaning column for gas from the condenser (7/1)

   a gas cleaning water processing system (15/1)

   a sorting system for solid effluent items from the heat process (24-26/1)

   automatic heat treatment cycle programming
2. Facility in accordance with the designation of claim 1, characterised in that the heat treatment furnace is mobile, made up of a rolling motorised vault moving on rails. The vault is closed at both ends by lifting doors referred to as "guillotines". The high position of the doors allows the furnace to move from one distillation cell to the other. In order to achieve convection heat, the most efficient in those temperature ranges (500 °C), the furnace has a turbine forcing room air onto the electric heaters.
3. Facility, in accordance with the designation of claims 1 and 2, characterised in that both sealed distillation cells (2/1) rest on refractory concrete bases. The stainless steel cells receive the treatment produces and depending on the position of the furnace, are subjected to the heating phase by the electric heaters located in the furnace, or to the cooling phase, by exposing the cell to open air as the furnace moves to the second cell, and to sprayed water. The cell door turns on an axis and comes to be parallel with the front side, equipped with a joint, which it is pushed up against by a system of slanting blocks and catches.

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