FR2587693A1 - EVAPORATION OF INFILTRATION WATER FROM GARBAGE DEPOSITS - Google Patents

Abstract

THE INVENTION CONCERNS A PROCESS AND A PLANT FOR EVAPORATING INFILTRATION WATER FROM GARBAGE DEPOSITS USING THE GAS FROM THESE DEPOSITS. THE PUTREFACTION GAS IS USED FOR THE GENERATION OF CURRENT, THE CURRENT PRODUCED IS ON THE ONE PART USED TO OPERATE THE MACHINES OF THE EVAPORATION PLANT AND ON THE OTHER HAND SUPPLIED TO THE NETWORK OF CURRENT SUPPLY UNDERTAKINGS; THE HEAT PRODUCED DURING THE GENERATION OF CURRENT IS USED FOR THE EVAPORATION OF THE INFILTRATION WATER; AN ENGINE 2 OPERATES BY COMBUSTION OF PUTREFACTION GAS 1 AND IS PROVIDED FOR A GENERATOR 2 SERVING FOR THE PRODUCTION OF CURRENT AND THE COOLING CIRCUIT 4 OF THE ENGINE IS CONNECTED TO A HEAT EXCHANGER 5 WHICH IS ITSELF IN COMMUNICATION WITH VAPORIZATION CHAMBER 8 WHERE THE INFILTRATION WATER IS VAPORIZED BY RELAXATION AT LOW TEMPERATURE VACUUM. APPLICATION TO THE TREATMENT OF GARBAGE.

Description

The present invention relates to a method for evaporating water

  infiltration from garbage deposits using the putrefaction gas of these deposits, and an installation for the implementation of this method. Infiltration water from garbage dumps is a waste water that needs attention

  particular because of the protection of the environment.

  For the most part, seepage water is rainwater that has seeped through the deposit, which has received soluble components from the garbage to remove it from the deposit at its base. The components dissolved from the garbage are mostly harmful to the bottom water so that the seepage water must not enter the ground as it might otherwise endanger the bottom water. For this reason, water

  infiltration of garbage deposits is captured and generally

  it is transferred for purification to clarification facilities. Due to the relative positions of garbage dumps and clarification facilities, it is not possible in most cases to channel seepage water directly into clarification facilities. It would be even more expensive to build a special clarification facility for garbage dumps. For these reasons, seepage water that is captured from garbage dumps is transported in tank cars to clarification facilities, which is a process

complicated and expensive.

  From the garbage dumps, in addition to the seepage water, there are also gases that are generated during the putrefaction and the decomposition of the waste. These gases mainly contain CO2 and CH4. Because of their methane content, the gases thus have a calorific value that can be exploited for the evaporation of the infiltration water. This has already been achieved, in which case the gas from the waste deposit is burned directly for the evaporation of the infiltration water. Methods are also known according to which the infiltration water is injected into the combustion volume ("Considerations on the evaporation of infiltration water from garbage deposits using a putrefaction gas, waste and refuse ", 11/82, pages 314 to 320). The profitability of such facilities is therefore not guaranteed because the infiltration water is produced in different quantities during the year while the putrefaction gas is available at

  about constant amount. In addition, during the evaporation

  heating, for example in evaporation

  thin film or falling film, there are problems caused by encrustations caused by

salts that crystallize.

  It is therefore an object of this invention to simplify and make less costly the transport of evaporative infiltration water by optimally utilizing

putrefaction gas.

  This problem is solved in that the putrefaction gas is used for a current generation, the product current being used on the one hand to operate the machines of the evaporation plant and on the other hand to be distributed to the network power supply companies and in that heat produced

  during current generation is used for evaporation

infiltration water.

  The invention offers the possibility of optimally utilizing the putrefactive gas independently of the existing amount of infiltration water. For this purpose, the putrefaction gas is initially used for current generation. The produced current is used to operate the machines of the evaporation plant and the excess part is distributed to the network of power supply companies. The heat generated during the current generation is used for the evaporation of

  infiltration water. The putrefactive gas is advantageous

  It is used completely according to this process and, in the current generation process, it provides a constant amount of heat. This amount of heat is always available constantly for evaporation of infiltration water, regardless of the existing quantity

infiltration water. -

  According to an advantageous feature of the invention, the heat produced during the current generation is transmitted to a heat-carrying medium which is channeled in a circuit passing through a heat exchanger. The medium carrying heat, for example water or oil, does not reach such a high temperature

  it causes evaporation of the infiltration water.

  As a result no incrustation occurs in the heat exchanger. The heat of the heat carrier medium heats the infiltration water sufficiently to be evaporated in the vapor chamber.

  vaporization under the effect of the vacuum prevailing in it.

  According to this procedure, the use of gas

  putrefaction is better than when this putrefaction gas

  faction is used directly for the evaporation of infiltration water.

  The method further provides that the infiltration water

  It is vaporized under vacuum in a vaporization chamber by a low temperature expansion flashing effect. The concentration of evaporative underpressure infiltration water at temperatures lower than the normal pressure boiling point, compared to known evaporation at normal pressure and corresponding boiling point, the great advantage of being able to use heat also at a low temperature level. Thus the heat produced during the generation of current using putrefactive gas is sufficient to ensure the evaporation of the infiltration water. In addition, the vaporization by low temperature expansion has the advantage, compared to the known vaporization in descending or thin film, of preventing an incrustation by salts crystallizing

on the warm walls.

  The method further provides that the infiltration water

  If it has not been evaporated in the vaporization chamber, it must be channeled into a circuit through the heat exchanger. Seepage water from the garbage dump

  is sprayed directly into the spray chamber.

  For this purpose, already a part of the injected water is vaporized under the effect of the vacuum prevailing in the chamber. The impurities of the concentrated infiltration water collect in a collecting bottom. The infiltration water, already pre-purified and located above the impurities that have settled, is pumped out and channeled through the heat exchanger. This avoids the risk of obstruction of the heat exchanger by already separated impurities. The evacuation of infiltration water by

  pumping from the bottom collector of the steam chamber

  Furthermore, it furthermore ensures a continuous supply of infiltration water, in an always constant quantity.

at the heat exchanger.

  According to another aspect of the invention, it is provided that the concentrated infiltration water is channeled from the vaporization chamber in a circuit to thereby separate the concentrate. It is thus advantageously ensured that the infiltration water already pre-concentrated in the bottom collector is once again released from a significant proportion of liquid which is recycled in the chamber of

  vaporization. Only infiltration water is thus obtained.

  concentrate, namely the concentrate, which is intended

  to be transported to the clarification facilities.

  In an advantageous embodiment of the invention,

  It is expected that the vapors occurring during the vaporization of the infiltration water are cooled in a condenser sufficiently that the condensable gases are separated from the non-condensable gases. The condensable gases are cooled in the condenser by injection of water and are precipitated in the form of a condensate while the non-condensable gases are evacuated via the vacuum pump. Since the non-condensable gases contain odorous substances, these gases can be mixed with the

  putrefaction gas either recycle it to the garbage dump.

  The condensate is pumped into a circuit and is channeled into a cooling tower of which part is

evacuated continuously.

  Other features and advantages of the invention will be highlighted later in the

  description, given by way of non-limiting example, in

  reference to the attached single drawing which

  an installation for carrying out the process

according to the invention.

  The figure shows in a simplified form a diagram of the installation according to the invention. In

  correspondence to this installation scheme, putrefaction gas

  fraction 1 is sucked from a garbage waste and is introduced into an internal combustion engine 2. This internal combustion engine may be a piston engine or a gas turbine. The internal combustion engine is coupled to a generator 2 'which produces current. The current is used to operate the machines of the evaporation plant while the excess current is distributed to the

  network of power supply companies.

  Because the internal combustion engine must be cooled, cooling water is used

  hot, which is pumped by means of a cooling water pump

  3 through the cooling circuit

  4. In place of cooling water, it is also possible to

  use any other medium carrying heat, for example oil. In the cooling circuit 4, there is provided a heat exchanger 5 in which one makes

  pass the infiltration water to heat.

  The infiltration water 6 from the garbage deposit is introduced by means of a pump 7 into the vaporization chamber 8. By means of a control apparatus 9 ', it is ensured, in correspondence with the level of water in the vaporization chamber 8, a regulation of the introduction of the infiltration water 6 into the vaporization chamber

  via a dispensing valve 9.

  Under the effect of the vacuum prevailing in the vaporization chamber, already part of the infiltration water 6 introduced by pumping is vaporized but most of it is however collected in a bottom 24 of the collection chamber vaporization. From the bottom 24, the infiltration water which has collected in it is pumped through a conduit 10 and by means of a pump 11 in the heat exchanger 5. In the the cooling water which reaches a temperature of 90 gives up its heat and is recycled at a temperature below the boiling point and at the normal pressure in the vaporization chamber 8, where it is discharged by special nozzles and o it is vaporized by the sudden expansion occurring in the vacuum prevailing in said chamber. The void required for evaporation during expansion in the nozzles is controlled through the temperature of the cooling water from the cooling tower 17

  153 and which is injected - d-years-a-c-ondender-mixer 14.

  Impurities in the infiltration water

  as well as concentrated infiltration water

  in the bottom collector 24 of the vaporization chamber 8.

  Despite the emptiness in it, it does not happen

Spraying.

  After the vaporization-relaxation, the steams

  saturated with water vapor are coming out of the steam chamber

  8 passing through a droplet separator 12 and they are channeled through the conduit of

  discharge of steam 13 into the condenser-mixer 14.

  There is a separation of the condensing gases in the

  with respect to non-condensable gases. Condensing gases

  They are cooled by water injected sufficiently strongly to liquefy by condensation. Condensate

  which is however still hot is introduced through

  of a conduit 15 and by means of a pump 16 in a

  cooling tower 17. By means of a

  30, the quantity of condensate introduced into the cooling tower 19 is regulated and the excess condensate can be transferred via a

  valve 30 and duct 18 into the pipe.

  The condensate is cooled in the cooling tower 17 sufficiently to be able to be used

  as cooling water in the condenser-mixer 14.

  By means of a pump 19, the cooled condensate is introduced into the condenser-mixer 14 via a

return pipe 20.

  The non-condensable gases are discharged via the air discharge duct 21 by means of a vacuum pump 22. Since the non-condensable gases generally contain smelly materials, they are recycled by the intermediate of a conduit 23 again in the garbage deposit or they are mixed with the putrefaction gas for combustion. Consequently, it does not leave the installation of materials likely to

pollute the environment.

  The infiltration water concentrate collecting in the bottom collector 24 of the vaporization chamber 8 is transferred by means of a pump 25 and via

  of a conduit 26 in a hydrocyclone 27. In this

  cyclone 27, the infiltration water concentrate is even more concentrated. The overflow is returned via a conduit 29 into the vaporization chamber 8. The concentrated infiltration water and the deposited impurities flow out of the bottom collector continuously via This effluent can be transferred to tanks kept available for transport to the clarification plant or it can be placed in other containers or collecting bins. The concentration carried out in cyclone 27 can also be carried out by any other device of

  concentration of fluid sludge, for example by separations

or centrifuges.

  Pretreatment of the infiltration water concentrate, for example in view of a concentration

  additional treatment or chemical treatment, may be

  killed independently of this facility in another step.

Claims (9)

  1. Process of evaporation of infiltration water   from garbage dumps using putrefaction gas   fraction of these deposits, characterized in that the putrefaction gas is used for the generation of current, the   produced current being used on the one hand to   the machines of the evaporation plant and on the other hand is supplied to the network of   in current and in that the heat produced during the gen-   Current ration is used for the evaporation of infiltration water. 2. Method according to claim 1, characterized in that the heat generated during the generation of current is transmitted to a heat carrier medium which is channeled   in a circuit passing through a heat exchanger.   3. Method according to one of claims 1 or 2,   characterized in that the heat carrying medium transmits   its heat to the seepage water in the heat exchanger.   4. Method according to any of the claims   1 to 3, characterized in that the infiltration water is vaporised under vacuum in a spray chamber by relaxing at low temperature.   5. Method according to any one of the claims   1 to 4, characterized in that the infiltration water which has not been vaporized in the vaporization chamber is channeled   in a circuit passing through the heat exchanger.   6. Process according to any one of the claims   1 to 5, characterized in that the concentrated infiltration water   is channeled in circuit at the exit of the steam chamber   tion and is then separated from the concentrate.   7. Process according to any one of the claims   1 to 6, characterized in that the fumes produced during the vaporization of the infiltration water are cooled in a condenser sufficiently that the condensable gases are separated from non-condensable gases.   8. Intallation for the implementation of the method according to claim 1, characterized in that an internal combustion engine (2) for combustion to putrefaction gas (1) is accouDle to a generator (2) serving   power generation and in that the cooling circuit   (4) of the internal combustion engine is connected to a heat exchanger (5) which is itself in communication with the vaporization chamber (8) via ducts (10).   9. Installation for the implementation of the process   according to one of claims 1 to 8, characterized in that the   vaporization chamber (8) has a bottom (24)   which is connected to a device (27) for separating   trat, preferably a hydrocyclone.   o10. Installation for the implementation of the method   according to any one of claims 1 to 9, characterized   in that the vaporization chamber (8) has a vapor discharge duct (13) which is connected to a vacuum pump   (22) via a condenser (14).