Furnaces – Process – Treating fuel constituent or combustion product
Reexamination Certificate
2001-01-16
2001-11-13
Bennett, Henry (Department: 3749)
Furnaces
Process
Treating fuel constituent or combustion product
C110S219000, C110S229000, C048S127300, C048S127900
Reexamination Certificate
active
06314895
ABSTRACT:
The present invention relates to a process for treating at least one liquid fluid, and to an installation intended to implement this process.
Ever stricter antipollution standards necessitate the sorting of household and industrial waste in accordance with very precise physico-chemical criteria before it is dumped.
At the present time, one of the most commonly used method is to discard unused matter is to pack it into a cavity. This matter, considered as waste, is of varying origin. It may derive from household, industrial, agricultural environments and contain a large variety of mineral and organic products.
This waste has varying toxicity and stability from an environmental viewpoint. Some waste, considered as toxic for the environment on account of its chemical nature, may seriously disturb a natural ecosystem if it should infiltrate the latter.
Therefore, it is necessary to avoid the penetration of these components into soil structures as far as possible, and consequently it is essential for them to be retrieved for subsequent processing.
When stacked, even compressed, this waste finds itself in an anaerobic medium. Deprived of oxygen, this medium promotes the formation of organic acids during a first phase, and during a second phase the formation of a gas (biogas). Simultaneously an aqueous liquid (lixivium) is formed.
This biogas, which forms a mixture containing in particular carbon dioxide, methane, steam, hydrogen sulphide, amines and phosphines, has a relatively low energy value which nonetheless offers advantageous industrial use. In addition the biogas has the disadvantage of being corrosive and nauseating. These different disadvantages, before any industrial use is made of the potential energy of the biogas, require pre-processing which is difficult to implement owing to the high cost of biogas transport and the distance of dump sites from treatment sites and from potential users.
Also, the lixivium is generally recovered by drainage from the bottom of the cavities in which the waste is stacked. Reinforced steps to protect the environment mean that the alveoli must be made impervious to soil infiltration. This is achieved by applying clay and/or a plastic coating to the inner surface of the alveoli. This protection of the alveoli leads to an increase in the quantities of lixivium recovered compared to previously.
In addition to water, the lixivium particularly contains compounds which are toxic for the environment, containing heavy metals and/or water-soluble salts. It must therefore be given prior chemical treatment to make the pollutants it contains inert before it is discharged into the environment.
Moreover, the lixivium is known to be corrosive in respect of concrete for example.
In most of the methods used up until the present time, poor performance, high implementation costs for the treatment of this liquid and gas waste, and operating restraints form major disadvantages.
The use of conventional biological methods leads to discharging pollutants into the natural environment due to the poor yield of waste treatment.
Chemical oxidation methods require the use of additional reagents (hydrogen peroxide, ozone) whose level must be permanently adapted to the varying nature of the chemical constituents of the lixivium.
Finally, direct incineration of the lixivia requires an additional fume filtration installation to capture the particles of dried salts during incineration.
The need also subsists for a process which can be properly, easily, simultaneously, economically and therefore locally conducted without polluting the environment or nature, to treat waste of liquid type with waste of gaseous type, both being considered as polluting on account of their twofold toxic and corrosive nature, and having a high water content, which does not have the previous disadvantages.
The subject of the invention consists of a process for treating at least one non-treated liquid fluid having a high water content and containing a volatile fraction and a heavy fraction, for the purpose of separating these two fractions;
The process consists of:
a) burning at least one gaseous fluid in such manner as to produce a combustion gas, of
b) recovering the heat from the combustion gas to heat the liquid fluid, of
c) circulating the heated liquid fluid under pressure, of
d) extracting, by evaporation, the volatile fraction from the liquid fluid, of
e) oxidizing, by combustion, the components of the volatile fraction, then of
f) extracting the heavy fraction in concentrated form,
said process making it possible to simultaneously treat at least one liquid fluid and at least one gaseous fluid.
The subject of the invention has the advantage of avoiding the discharge of residues into the environment in liquid form, by using the energy contained in substantial quantity in the gaseous fluid. Through the use of this energy it is possible to vaporize discharges in the atmosphere.
A further advantage of the subject of the invention is the ability to treat waste of liquid type using other waste of gaseous type without adding any additional reagent, while permitting the evaporation of a fraction of the initial volume of liquid waste.
In addition, with the method of the invention it possible to oxidize by combustion the organic compounds present in the volatile fraction of the liquid waste without the need to use additional fuel, with the possibility of recovering by condensation all or part of this volatile fraction.
Finally, the treatment process of the invention is particularly adapted to variations in the composition of the liquid fluid between different extraction sites (dumps) and between different removal stages from one same site or from different sites. Contrary to a process of biological type, to obtain maximum performance, the process of the invention is fully insensitive to variations in biodegradability of the liquid fluid.
Also, the compactness of the equipment needed to apply this process facilitates truck transport of the treatment units and consequently reduces cost price.
A further subject of the invention is a treatment installation intended to implement the preceding process.
This installation is characterized in that it essentially comprises:
an inlet duct for at least one gaseous fluid,
a combustion chamber,
a heat recovery loop comprising at least one gas/liquid heat exchanger,
a fan intended to evacuate into the atmosphere, and adjust, the combustion gases which were cooled after passing through the heat exchanger,
an inlet duct for the liquid fluid,
an evaporator intended to vaporize the volatile fraction of liquid fluid,
a device to extract the heavy fraction.
The liquid fluid preferably circulates with the fluid that is partially rid of its volatile fraction.
The combustion of the gaseous fluid is preferably conducted at a temperature greater than approximately 900° C. and that of the volatile fraction at a temperature greater than approximately 500° C.
During recycling, the liquid fluid can preferably circulate under pressure, then be heated to a temperature greater than the evaporation temperature of the volatile fraction of the liquid fluid.
Heat recovery is made on the combustion gases preferably cooled to a temperature of less than approximately 700° C. They are preferably evacuated into the atmosphere at a temperature of approximately 200° C.
The heavy fraction particularly comprises heavy organic matter and water-soluble salts. It represents between approximately 1 and 20% of the initial volume of the liquid fluid before its treatment according to the invention.
Preferably, the fluid used in the process of the invention is biogas. This biogas may contain at least one combustible compound in gaseous form (methane for example), and may also contain in addition to this combustible compound at least one compound in gaseous form chosen from among water, air, carbon dioxide, sulphur compounds, amine compounds and their mixture.
The liquid fluid used in the process of the invention is preferably a lixivium containing water and may also contain at least one compound chosen fro
Lefebvre Bernard
Leglise Jean-Paul
Nogrette Jean-François
Notelteers Jean-Guy
Bennett Henry
Rinehart K. B.
SARP Industries
Wolf Greenfield & Sacks P.C.
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