NO770918L - PROCEDURE FOR PRECIPITATION OF THERMOUS HEATING RESINS FROM WASTE WATER. - Google Patents

Description

Procedure for precipitation of thermo-

curing resins from waste water.

The present invention relates to a method for insolubilization or precipitation of thermosetting resins from waste water from the manufacture of mineral fiber products, in particular glass fiber products.

According to the invention, the thermosetting resins are rendered insoluble in the water by heat treatment at a temperature above 100°C, preferably between 150 and 240°C.

This heat treatment can advantageously take place under pressure.

The use of this insolubilization process on at least part of the cooling water and the washing water is advantageously used to make the binder components, dissolved in the water, insoluble, so that they can then be separated in a known manner, whereby the concentration of contaminants in the washing water and cooling water can be kept at a level - level, and the water is reused in the installation.' The washing water therefore circulates in a closed circuit and all the export of pollutants is eliminated.

The accompanying figures shall illustrate the invention

closer.

In the figures, fig. 1 degree of insolubilization

as a function of treatment temperature and time.

Fig. 2 shows a device for carrying out the heat treatment of the water under pressure according to the invention. Fig. 3 shows a system for continuous operation for treating the water.

The applicant has found that if the water, which is used for cooling and washing the flue gases and which after filtration contains binder and dissolved binder components, is kept at a certain temperature for a certain time, a certain part will be converted into insoluble substances, in increasing quantity with temperature and time, and consequently pass to a suspension in water from which the solid can be separated.

The relative amount of the dissolved substances, which are made insoluble by this heat treatment, will determine the treatment's effect.

The treatment temperature has a very important effect on the effect or yield, e.g. it has been found that for water containing 1% dissolved binder compounds, the treatment's performance will be:

40% if the water is kept for 8 days at 40°C,

40% if the water is kept for 3 days at 70°C,

40% if the water is held for 3 min. at 160°C,

60% if the water is held for 3 min. at 180°C, and 95% if the water is held for 3 min. at 240°C.

Fig.l shows the precipitation effect as a function of the treatment temperature and time.

In larger factories for the production of fibreboard, the amount of water to be treated can be 50 m^/hour, and in order to avoid the construction of larger treatment plants, one must work with the shortest treatment times and higher temperatures of over 100°C. This will again require that the treatment is carried out under pressure, at a temperature that is maintained at approx. 5°C lower than the water's boiling point under the selected pressure, so that the water remains in liquid phase during treatment. This solution has, among other things, the advantage is that it only requires relatively little energy, namely, apart from the heat losses, the amount required to heat the water to the selected temperature.

Under the assumption of equal amounts of dissolved binder, the latter method is four times cheaper than the incineration process, which was previously discussed.

One of the disadvantages, which is usually noticed when heating water containing binder or dissolved binder components, even in low concentrations, is that an insoluble coating is deposited on the walls of the vessel, which very quickly acquires sufficient thickness to seal the vessel's openings.

In this connection, the applicant has found that if the necessary quantity for the heating is delivered in the water itself to be treated, and the walls of the vessel during the treatment are kept at a lower temperature than the mass of water being treated, such a deposit will not be obtained on the walls as the precipitated or insolubilized binder stays in suspension in the water. A result of

this, is that the heating is then advantageously carried out either by mixing the water with hot gases, especially superheated steam or combustion gases from submerged burners or by means of organs that release energy in the water in another way, such as e.g. by an electric arc.

A wide range of processing conditions is possible, e.g. 6-40 atmospheres pressure, 160-240°C treatment temperature and from 3-10 min. treatment duration.

The conditions below seem to be a good compromise between energy costs and installation costs:

Implementation of the method can take place in devices that work discontinuously or continuously.

Fig. 2 shows a plant for discontinuous operation. The water, which is treated, is introduced through the controlled valve 67 to the chamber 68. The introduced amount of water or charge makes up 70-80% of the tub's capacity. The heating medium, preferably superheated steam, is then let into the vessel through the nozzle 69 which is immersed in the water. The amount of steam is regulated by the controlled valve 70, via regulator 71.

The order of treatment is:

The container 68 is filled with water under atmospheric pressure. The desired treatment pressure is applied to the regulator 71, e.g. 16 atm.abs.

The valve 70 is opened, and steam flows in through the nozzle 69, mixes with the water and transfers its condensate to the water, releasing condensation heat and coolable heat.

The temperature in the pressure vessel 68 rises to approx. 200°C

under a pressure of 16 atm.abs.

The steam supply is then interrupted. The supply nozzle 69 is so large that said temperature and pressure increase is rapid, within less than 1 min. The water is kept at 200°C and 16 atm.abs. for 2-4 min.

After this period of time, the pump 7 2 is put into operation and sends a new charge of water to the container 73 through the double-walled channel 74. During the flow through the double jacket, the water, which has a temperature of approx. 40°C at the inlet, cool the treated water in the container 68. The dimensions of the heating jacket

74 is adapted so that the water reaches the collection vessel 73 at a

. temperature of approx. 80°C.

An additional cooling liquid circulates in the second double jacket 74 and further cools the water in the container 68. The cooling is considered finished when the temperature of the treated water has dropped below 100°C, preferably 40-50°C. When this point is reached, the valve 76 is progressively opened to release the pressure in the container 68.

The treated water flows to a filtration station 51 or a facility for precipitation, decantation or centrifugation,

where the precipitated binder components are separated from the water. The filtered water flows to the vessel 52 and the dry matter 56 is sent to the conveyor belt 57.

When the container 68 is empty, the valve 76 is closed and the valve 67 is opened for the preheated water in the tub 73 which flows per gravity into the container. An exhaust valve 67a is also connected to the plant.

Then a new cycle can start.

Fig. 3 shows a plant for continuous operation of it

proposed procedure.

The pump 77 sends under treatment pressure water with contaminants to the mixer 78 where a heating medium such as e.g. water vapor. The steam mixes with the water, which is to be treated, and during condensation transfers its entire amount of heat to the water. The amount of water vapor is regulated by the valve 80, which is controlled by the regulator 81, so that the water at the exit from the mixing device 78 has the desired treatment temperature. At the exit from the mixer 78, in which the water has remained for 10-20 seconds, the water goes to the reactor 82, where the insolubilization or precipitation of the binder takes place, and whose dimensions are adapted, so that the residence time for the treatment water is the desired treatment time of 2-4 min.

At the exit from the reactor, the water in the heat exchanger 83 is cooled to a temperature of below 100°C, preferably 40-50°C. Part of this cooling is achieved by the water, which should

processed, preheated in the spiral 84 from approx. 40-80°C.

The remaining cooling is effected by a cooling medium that circulates in the circuit 85.

At the exit from the heat exchanger 83, the pressure on the water is released up to atmospheric pressure through a relief valve 86 which, via a regulator 87, maintains the treatment pressure in the installation.

The water, which now has atmospheric pressure, goes to a filtration plant 51 or a similar plant for precipitation, decantation or centrifugation which separates the water from the precipitated binder components. The filtered water goes to the container 52, and the waste 56 after treatment is sent to the conveyor belt 57.

The plant in fig. 3, which is operated continuously, can be controlled in a more variable manner and is less expensive than the plant shown in fig. 2.

Claims (12)

1. Method for insolubilization (precipitation) of thermosetting resins contained in waste water from the production of mineral fiber products, in particular glass fiber products, characterized by heating the water to a temperature that is preferably above 100°C, preferably between 150 and 240°C. 2. Method as specified in claim 1, characterized in that the treatment is carried out under pressure. 3. Method as specified in claim 1, characterized in that the required amount of heat is supplied in the body of water itself. 4. Method as specified in one or more of claims 1-3, characterized in that the heat treatment is carried out in a container whose walls maintain lower temperatures than the water being treated. 5. Method as specified in one or more of claims 1-4, characterized in that the treatment is carried out 'by introducing combustion gases from a burner which is lowered into the water. 6. Method as stated in one or more of claims 1-4, characterized in that the treatment takes place by heating with an electric arc immersed in the water. 7. Method as specified in one or more of claims 1-4, characterized in that the treatment takes place by introducing preferably superheated water vapor into the water. 8. Method as specified in one or more of claims 1-7, characterized in that the methods are applied to the method in one or more of claims 1-5, for processing ling of washing water. 9. Method as specified in one or more of claims 1-8, characterized in that the water is filtered after treatment to remove solid components and precipitated compounds. 10. Method as stated in one or more of claims 1-8, characterized in that the solid substances and precipitated compounds in the treated water are separated from the water by decantation, possibly after flocculation. 11. Method as stated in one or more of claims 1-8, characterized in that the solids and precipitated compounds from the treated water are separated by centrifugation. 12. Method as stated in one or more of claims 9-11, characterized in that the precipitated substances are burned in an oven, preferably between 600 and 1000°C, and that the precipitated substances are converted by this treatment into non-polluting components.