EP1986964A1 - Process for eliminating organic matter and for generating energy - Google Patents

Abstract

Process for destroying organic matter, in which said organic matter in ground form is introduced into a reactor and subjected to flameless combustion at a temperature of 240 to 400°C under a pressure of 100 to 300 bar, in the presence of an oxygen-containing oxidizer for at least 20 minutes, while stirring the medium, and process for generating energy, in which the energy generated by the combustion is furthermore recovered.

Description

 Process for removing organic matter and producing energy

The present invention relates to a new process for the removal of organic matter and energy production.

In today's society, the disposal of waste, particularly organic matter, particularly of animal origin, is of increasing importance.

In addition, the appearance of certain disease factors, such as the prion, involves a radical destruction of many organic materials.

The waste to be disposed of can be solid or non-solid.

For example, it is already possible to eliminate certain wastes by pyrolysis, that is to say by combustion at high temperature in an oven.

With particular reference for example to animal carcasses, the raw product is first transformed into a solid waste called animal meal, which is then destroyed by incineration, that is to say by combustion with the flame at temperature. higher than 850 ⁰ C. But the incineration produces dioxins, and it must be carried out on flour generating dust which can be toxic.

It would therefore be desirable to find an effective technique for the removal of organic matter, which makes it possible to work directly on the raw product, which does not produce toxins and which makes it possible to avoid the formation of potentially toxic dusts.

It would also be desirable to find a process that does not demand energy and even if possible that produces energy rather than consuming it.

After extensive research, the applicants have found a satisfactory process.

This process is essentially based on a flameless combustion at a relatively low temperature, and under pressure, in the presence of an oxidant such as air. This is why the present application relates to a method for destroying organic material, wherein is installed in a reactor said organic matter in comminuted form and is carried at its combustion without a flame at a temperature of 240-400 ⁰ C., under a pressure of 100 to 300 bar, in the presence of an oxygenated oxidant, for at least 20 minutes, while stirring the medium.

Remember that the term "organic matter" refers to the carbonaceous material from living or non living beings, plants or animals. More precisely, it is about materials able to decompose. This notion should not be confused with that of "organic compound", a family to which belong in particular plastics and polymers and more particularly PCBs (PolyChloro-Biphenyls), also called, especially in Quebec,

PCBs (Polychlorinated biphenyls) as well as polychlorinated terphenyls, monomethyl tetrachlorodiphenylmethane, monomethyl dichlorodiphenylmethane and monomethyl dibromodiphenylmethane, which are assimilated thereto.

According to the present invention, the treated organic materials do not need to be in solid form. They are obviously in a form that can be milled (that is to say minced in the case of meat or fish for example).

Under preferred conditions of implementation of the invention, raw products are processed. They are especially not degreased.

As organic materials, there may be mentioned those of animal origin (including humans) including animal by-products including poultry by-products and fisheries and animal waste.

Mention may in particular be made of organic materials of animal origin, such as those derived from cattle, pigs, goats, poultry, equines, rodents such as rabbits and hares. It is also possible to mention in particular the waste exiting the slaughterhouse or rendering animals, for example carcasses of cattle, poultry, pigs, sheep, and animal fats from the preparation of meat. Another example is slurry and fishery waste.

Some of these materials may be in the form of corpses or carcasses. It can also be animal parts like the blood, feet, head, horns, muzzle, tonsils / pharyngeal lymphatic ring, penis, tail, lungs, kidneys, esophagus, liver, heart, diaphragm, spleen, pre-stomachs, stomach, testes, trachea, larynx, extralobular bronchi, gallbladder, bile, fat, intestine, mesentery anus, female genitalia, udders, fetuses , the spinal cord and the hard mother, the spine, the sacrum, the tendons, the ligaments, the nervous tissues, the lymphatic tissues, the blood vessels, the meat not intended for food. It can also be metabolic waste. We can also treat waste of any kind from the pharmaceutical industry or veterinary hospitals or hospitals, for example as cottons, linens or compresses soiled, anatomical waste of human or animal origin as those mentioned above.

Mention may also be made in particular of organic materials in suspension or solution in wastewater (also called waste water) or washing. Domestic sewage consists of toilet flushing gates, greywater evacuation kitchens and bathrooms. Waste in these dirty waters consists of degradable organic matter and mineral matter. These substances are in dissolved or suspended form. As a reminder, the wastewater networks lead to treatment plants where the water is treated and where most of the organic matter is in the form of sludge.

It is possible to treat both primary sludge, deposits recovered by simple decantation of waste water and having high concentrations of mineral matter (sands, earth ...) but also organic matter, that physicochemical sludge, sludge-like sludge but to which a reagent (salts of iron, aluminum, or other flocculating agents) has been added to agglomerate the fine particles and to improve the settling, that the biological sludge still called secondary sludge, and coming from a biological purification of waters (activated sludge, bacterial beds ...). Mixed sludge consisting of a mixture of primary and biological sludge and prolonged aeration sludge obtained without primary settling with highly aerated pollutants can also be mentioned. We can also mention animal by-products not intended for human consumption categories 1 2 and 3 according to the regulation of October 3, 2002 establishing in France the sanitary rules applicable to animal by-products not intended for human consumption. Under preferred conditions of implementation of the invention, the waste is used in the reduced form process.

By "reduced form" is meant that the pieces of organic material or containing organic material are small. They come for example in the form of a slurry. The particle size of at least preferably 50%, preferably 80%, especially 90% of the pieces is advantageously less than 20 mm, preferably less than 15 mm, especially less than 10 mm, more particularly less than 5 mm (evaluation by sieving ).

It is advantageous to operate on a slurry of the organic material that it is desired to treat.

The condition of the products (solid, slurry, etc.) is classically indicated for normal temperature and pressure conditions.

The process of the invention can be carried out between 240 and 400 ^° C., preferably between 250 and 350 ^° C., particularly between 280 and 320 ^° C. The process of the invention is carried out under a pressure of 100 to 300 bar, preferably between 150 and 250 bar, preferably between 180 and 230 bar, particularly about 200 bar.

Oxidizing compounds that may be mentioned include oxygenates.

Under preferred conditions of implementation of the invention, oxygen is used, in particular in the form of air optionally mixed with one or more other gases.

In still other preferred conditions of implementation, oxygenates are used from waste or by-products of the industry, such as, for example, nitrous oxide. Advantageously proceed in the presence of an excess of oxidant.

For this purpose, the chemical oxygen demand (COD) of the organic material which it is desired to treat can be determined beforehand. Remember that COD expresses the amount of oxygen needed to oxidize matter organic (biodegradable or not) using an oxidant, potassium dichromate.

In still other preferred conditions of implementation of the invention, it operates in the presence of a catalyst, especially based on (Cu, Pt, Pd, Ru, Rh, Ti, especially on different supports such as oxides of aluminum, cerium or silicon.

The catalyst will for example be a metal oxide, such as selenium oxide, rhenium or hafnium, or those mentioned in the examples.

The catalyst may for example be used at a rate of approximately 2 g / l. It can especially be used at a pH of about 12.

In still other preferred conditions, a zeolite will be used.

The reaction time depends on the amount of organic material introduced initially. The reaction time can vary from 20 minutes. at 120 min. for carbon concentrations of between 5 g and 40 g per liter, preferably 20 to 120 min, preferably 60 to 100 min, most preferably 75 to 90 min.

The method of the invention being autothermal, the initial heating can be interrupted as soon as the set temperature is reached. In other preferred conditions of implementation of the invention, one or more of the inlet effluents are heated, for example the oxidizer or the additional organic materials to be treated in the case of a semi-continuous implementation. , or continuous, thanks to the energy produced by the implementation of the process. In still other preferred conditions of implementation of the invention, the heat energy produced by the reaction is removed using a particularly aqueous fluid, such as using industrial effluents, and more particularly using slaughterhouse effluents for the on-site treatment of raw animal material. The agitation system may be a conventional blade system.

Under preferred conditions of use, the oxidizer, preferably air, serves or in particular contributes to the agitation of the treated organic material. For this, it is advantageously injected under pressure in the organic material.

The process of the invention may be carried out batchwise, semi-continuously, or continuously. The reactor will be adapted to the form of implementation of the process. It is generally any suitable enclosure capable of withstanding high temperature and pressure.

At the end of the process, an aqueous suspension containing essentially minerals is obtained.

Depending on its composition, it can be reprocessed or rejected directly in the wild or transferred to a treatment plant.

The mineral phase is an ultimate waste

The process of the invention is endowed with remarkable qualities. It effectively destroys treated organic materials, especially proteins, and especially the prion. It makes it possible to transform this organic matter essentially into mineral matter, water and carbon dioxide.

The method further has the advantage of being autothermal. When the combustion is started, it is indeed no longer necessary to provide additional energy. Even an excess energy is obtained which allows, for example, to heat inlet effluents, for example the oxidant or the additional organic materials to be treated. Preferably, the effluents are brought to the reaction temperature.

The quantity of water needed to evacuate the heat energy produced by the reaction can be provided by industrial effluents, and more particularly effluents from slaughterhouses for the on-site treatment of raw animal materials. This energy produced can also be used to produce or complete district heating.

The method of the invention allows not only to work on animal meal, as is the case of incinerators, but also on raw products.

The invention can be implemented simply in a reactor capable of withstanding the above pressures, for example by using a reactor equipped with a heating system, a system for introducing the oxidizer, an organic material introduction system, a stirring system, a gas evacuation system, a low output for the mineral material, and preferably water and bath probes.

The above properties are illustrated hereinafter in the experimental section. They justify the use of the processes described above in the manufacture of energy.

This is why the present application also relates to a method for producing energy which is installed in a reactor an organic material in comminuted form, is carried at its flameless combustion at a temperature of 240-400 ⁰ C under a pressure of 100 to 300 bar, in the presence of an oxygenated oxidant, for at least 20 minutes, while stirring the medium and recovering the energy produced by the combustion.

The recovery of the energy produced by the combustion can in particular be obtained by using one or more heat exchangers, in particular brazed plate and fin exchangers.

The energy thus produced and recovered for example in the form of hot fluid, for example hot water, can be used conventionally.

The preferred conditions of implementation of the organic material destruction processes described above also apply to the other objects of the invention referred to above, especially to energy production processes.

Figure 1 describes a type of equipment and assembly used for the implementation of the invention, used for the realization of the following examples which illustrate the present application.

Example 1: Treatment of a batch of raw animal materials

A batch of (batch system) 20 grams of substrate is manually introduced into a hot oxidative treatment reactor, and sealed.

The hot oxidative treatment reactor used is a 450-mL volume autoclave made of a stainless steel crucible and a Hastelloy C276 lid, operating under subcritical conditions. The equipment is designed to withstand a maximum temperature of 400 ⁰ C and a maximum pressure of 30 MPa. The reactor is heated using an electric oven with a power of 4500W, placed around the autoclave. The system is also equipped with a mechanical stirrer and a manometer. The safety of the assembly is ensured by a solenoid valve and a rupture disc. The reactor also has two feed lines / liquid and gaseous withdrawal.

The treated substrate consists of 20 g of raw animal material (8 g dry weight), not defatted, in the form of a brown pasty slurry with a characteristic odor and a particle size less than 5 mm.

The sample composition given below was determined in relation to dry matter.

Average composition of raw animal materials:

MS = dry matter

TOC = Total Organic Carbon

Mechanical agitation is continuously maintained at 500 rpm. The oven is then turned on and the thermostat set to reach a temperature inside the reactor of 280 ^° C.

At the set temperature, air is injected and the pressure is set at 200 bar. The thermostat stops. A continuous flow of air is provided by means of a micro leak at the outlet of the reactor. Allowed to react for 60 min. The heat energy produced by the reaction is evacuated with water.

The optimal hydrothermal oxidation reaction produces a liquid effluent. This effluent contains 1.6 g / L of TOC (including 0.8 g of acetic acid) and 1.6 g / L of ammonia. The destruction of organic matter represents an abatement of more than 99%. At the end of the reaction, the solid phase contains about 400 mg of inorganic and inert material, which represents a reduction of 95% of the solids. This solid phase contains a negligible amount of organic matter. The gaseous effluents produced are separated and collected using a condenser and then trapped in an acid solution (HCl) and then basic (NaOH).

Example 2 Treatment of raw animal materials The procedure is as indicated above in Example 1, but adding 2 g / L to pH 12 of platinum catalyst on alumina. The TOC value of the outlet effluent is only 60 mg / L.

Example 3 Treatment of raw animal materials

One operates as indicated above in example 1, but adding

2 g / L at pH 12 of palladium catalyst on alumina. The value of the ammonia concentration is only 32 mg / L.

For the three examples, it was not possible to detect the presence of proteins in the final medium by the determination technique used.

The method of the invention is therefore effective to eliminate in particular the prion, both in organic materials than in animal meal.

Claims

1. A method of destroying an organic material, wherein is installed in a reactor said organic material in ground form, and proceeds to its combustion without flame at a temperature of 240 to 400 ⁰ C under a pressure of 100 to 300 bars, in the presence of an oxygenated oxidant, for at least 20 minutes, while stirring the medium. 2. A process according to claim 1, characterized in that the organic material is of animal origin. 3. A method according to claim 1 or 2, characterized in that the organic material is an organic material from those suspended or solution in wastewater (wastewater). 4. A method according to one of claims 1 to 3, characterized in that the particle size of at least 50%, pieces of the organic material is less than 20 mm. 5. A method according to one of claims 1 to 4, characterized in that it is carried out between 250 and 350 ⁰ C. 6. A process according to one of claims 1 to 5, characterized in that it is carried out between 150 and 250 bar. 7. A process according to one of claims 1 to 6, characterized in that the oxygenated oxidant comprises air. 8. A process according to one of claims 1 to 7, characterized in that it is carried out in the presence of an excess of oxidant. 9. A process according to one of claims 1 to 8, characterized in that it is carried out in the presence of a catalyst, for example based on Cu, Pt, Pd, Ru, Rh, Ti. 10. A process according to one of claims 1 to 9, characterized in that one or more of the input effluents is heated, for example the oxidant or the additional organic materials to be treated in the case of an implementation. works in semi-continuous, or continuous, thanks to the energy produced by the implementation of the process. 11. A method according to one of claims 1 to 10, characterized in that the oxidant is injected under pressure in the organic material for stirring. 12. A method of producing energy in which is installed in a reactor an organic material in milled form, it is proceeded to its combustion without flame as defined in one of claims 1 to 11 and recovering the energy produced by the combustion.