FR2605015A1 - PROCESS FOR TRANSFORMING WASTE CONTAINING ORGANIC MATTER. - Google Patents

Abstract

THE TRANSFORMATION PROCESS IS AIMED AT PRODUCING A COMBUSTIBLE FLUID WITH A HIGH CALORIFIC POWER AND CONSISTS OF TREATING WASTE IN THE PRESENCE OF A HYDROAROMATIC SOLVENT, UNDER ATMOSPHERIC PRESSURE AT A TEMPERATURE BETWEEN 200 AND 180 C. AS HYDROAROMATIC SOLVENT, ON CHETROUTAINS , NAPHTHALENES, METHYLNAPHTHALENES, CREOSOTES, ANTHRACENS, CHRYSENES AND THEIR OILS AND MIXTURES.

Description

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  PROCESS FOR TRANSFORMING WASTE

CONTAINING ORGANIC MATTER

  The present invention relates to a process for converting waste containing organic matter to produce a high calorific fuel fluid. The method applies for example, but not exclusively, to sludge treatment

  sewage treatment plants and fat.

  In processes of this type, also known as processes for "liquefaction:" sludge treatment plants, or as recovery methods ::, it is known to transform the sludge into fuel oils or waxes easily liquefiable by elevation temperature in the presence of water, carbon monoxide and alkali metal salts such as carbonates under severe conditions, ie at high pressure and high temperature. for example described in Chemical Engineering of December 14, 1984 and in Chemical and Engineering News of March 8, 1982. This kind of process, however, has the disadvantage of having limited transformation yields, especially if we try to remove carbon monoxide , and especially having to work at high pressures, of the order of 60 atm and at temperatures

  also high, of the order of 3000 C at least.

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  It is also known "hydroliquefaction" techniques, that is to say treatment with hydrogen under pressure, but the disadvantages are the same as those described above. Such a technique is described for example in the report of the US Environmental Protection Agency (Municipal Environment

  Research Laboratory Cincinnati) under the reference EPA-

  600/52 84.010 project Summary January 1984.

  We will finally mention for memory among the countless pyrolysis processes, those described in the invention EP 0 140 811, WO 85/02606 and FR 2 384 207. In the last, the solid waste is pretreated by an oily vehicle, to know heavy paraffins or engine oils, before being pyrolyzed in solid phase, a vehicle that the vehicle

oily has been separated.

  The present invention aims to overcome these drawbacks by proposing a process whose essential advantage is to work at ordinary pressure and at a relatively lower temperature, while ensuring conversion efficiencies of between 40 and 50% and up to 60%. %. The process applies to the treatment of sewage sludge referred to above, as well as to any waste containing organic matter, for example fats or meat products from slaughterhouses. The process according to the invention has the characteristic that a heat treatment of waste containing organic matter is carried out in the presence of a hydroaromatic solvent, at atmospheric pressure and at a temperature of between 200 and 280 ° C. The combustible fluid is recovered in the reaction medium after removal of the insolubles and separation of the solvent. This solvent is separated for example

by distillation.

  As indicated above, the organic material is converted into an oily or bituminous fluid product with a high heating value, of the order of 8 500 to 9 500 Kcal / kg. As wastes containing organic matter, all residues of a domestic or industrial nature may be used, in particular the doue of treatment plants or garbage treatment plants, as well as greasy or meat residues from slaughterhouses, more generally all residues of nature

  protein, lipid and / or carbohydrate.

  The hydroaromatic solvent used is chosen from the range of solvents having both an aromatic chemical nature and containing hydrogen atoms, and allowing a working temperature of between 2800 ° C. and 28 ° C. As a solvent, mention will be made in particular of tetralines, naphthalenes and methylnaphthalenes, creosotes, anthracenes, chrysenes and their oils

and mixtures.

  The solvent was thought to chemically and stoichiometrically intervene in the transformation process, acting as a hydrogen donor. This hypothesis proved to be inaccurate: indeed, systematic tests, under the same operating conditions, made it possible to obtain, with non-hydrogen donor aromatic hydrocarbons such as naphthalene and methyl-naphthalene, similar to those obtained with tetralin considered as a potential hydrogenation solvent. If the hydrogen transfer reactions do not therefore appear significantly in the course of the process as it is implemented, it is concluded that the hydro-aromatic solvents act, it seems, as heat transfer media and in as catalysts in the process of chemical transformation of organic matter. Indeed, other systematic tests have also highlighted the fact that the solvent was not consumed and could be recovered completely or almost completely at the end of the

transformation process.

  The nature of the solvent, that is to say its "nlydroaromatique" character is however decisive insofar as other non-aromatic solvents, do not lead under operating conditions similar to a suitable transformation. Thus, silicone oils and pure paraffins used as solvents give much lower results (liquefaction limited between 15 and 30%), insufficient on

the industrial plan.

  The organic matter-containing wastes used as starting materials are preferably low water-borne products, for example pre-dehydrated sludge, the minerals of which they contain are converted into ash and can be easily removed. The weight ratio. of the treated material / weight of the

  solvent is preferably chosen between 1.0 and 1.5.

  The implementation of the process according to the invention can be carried out in a simple way, especially on an industrial level, because it works at atmospheric pressure. One of the simplest ways to treat the waste is to suspend it in the hydro-aromatic solvent under reflux, provided that the solvent has a boiling point between 20 and 2800 C. For solvents with a higher boiling point such as anthracenes, work is carried out without going to reflux, keeping the temperature constant at a predetermined level between 200 and

2800 C.

  One operates in a conventional chemical reactor provided with a stirring device, for example with an anchor, and

thermoregulation.

  The treatment times are of the order of half an hour to a few hours, beyond which time the transformation yields no longer increase. At the end of the transformation, the insolubles are filtered, for example to remove the ash and the solvent is removed by any suitable means, in particular by distillation, optionally under reduced pressure if the boiling point of this solvent is greater than 2800. C. This solvent is then advantageously recycled in a

subsequent operation.

  It will be readily understood that the process, especially if the solvent is removed by distillation, can be carried out either by individual batch, that is to say by discontinuous operations, or continuously, where the solvent is recycled at

  as it was eliminated.

  The fuel fluid obtained, which appears as the case in the form of an oil or a wax or bitumen (once brought to room temperature) can be used as is, especially in boilers. For example, a portion of the resulting fluid may be burned to raise and maintain the solvent temperature between and 2800c. In addition, it is possible, in order to further improve the yields, to introduce the fuel oil obtained in a new waste suspension and hydro-aromatic solvent. In this way, the liquefaction efficiencies of the organic material are substantially improved, although these eventually stabilize at a value of between 50 to 60% of

transtormee organic matter.

  Combustible fluid analyzes carried out by means of nuclear magnetic resonance show that the hydrogen atoms belong essentially to methyl groups characteristic of the aliphatic hydrocarbon chains. The calorific value

  average of these oils varies between 8,500 and 9,500 Kcal / kg.

  The non-liquefied residue removed after filtration is a mixture of organic materials undissolved by the reaction solvent and mineral materials in respective proportions: 50 to 60% and 50 to 40%. this - 7 -

  low calorific residue concentrates almost

  all the minerals initially present in the sludge.

  The invention is illustrated hereinafter with reference

  to the examples given by way of non-limiting examples.

  In these examples and unless otherwise stated,

  percentages are expressed in weight values.

Example 1

  In a glass reactor of 500 mral g dry matter Doue purification plant (at% ash) is mixed with 100 g of tetralin. The mixture is stirred for 3 hours at 2000 ° C., a temperature close to the reflux of tetralin. At the end of this treatment, the reaction mixture is filtered while hot, the filter residue washed with the solvent; the filtrates are then combined to distill the tetralin and recover an oil (29 g) which is the organic material solubilized by tetralin. The filter residue (71 g) contains almost all of the ash (9 g) and the non-liquefied organic material (42 g). These results translate into

  liquefaction of organic matter of 40.8%.

  The fuel oil obtained has a higher heating value (SCP) of 9000 Kcal / kg (average value) and corresponds to the following elemental composition

C (%): 82.7

H (%): 10.0

N (%): 1.8

0 (%): 1.7

S (%): 3.8

Minerals: 0

Example 2

  Tetralin is replaced by 1-methyl-

  naphthalene; the liquefaction is carried out at 2300 C, for 5 hours, with the same type of sludge as that of Example 1. The quantity of liquefied oil obtained from 100 g of sludge material if a liquefaction yield of the material organic 55.2% higher than in the previous example and consequence of a heat treatment of longer duration and higher temperature. Under these conditions, there are also other organic fractions: volatile products at 2300 C (7.0 g) partially recoverable by condensation; water soluble products (7.7 g). The material

  non-liquefied organic is 16.1 g.

Example 3

  Tetralin is replaced by an AWPA creosote. The liquefaction conditions are as follows: dehydrated sludge is dispersed in 66 g of creosote. The mixture is heated to 2500 ° C. (reflux temperature of the lighter creosote fractions) for 5 hours. Under these conditions, a liquefaction yield of organic matter of 57% is obtained, ie 39.9 g of oil whose higher heating value (PCS) is 8,600 Kcal / kg. NMR analyzes show that this oil is composed only of products of aliphatic nature.

Example 4

  The treated organic material consists exclusively of waxy fat and lipids of various origins that can be recovered by

  example, sewage or sludge by settling.

  100 g of such a fat mixture (PF 450 C) were treated with 100 g of 1-methyl naphthalene under the conditions of Example 3, ie at 2300 C.

for 5 hours.

  A liquid and liquid oil is recovered at ambient temperature with a higher heating value (the PCS is 9,200 Kcal / kg). The yield of

liquefaction is 62%.

  Comparative Examples 1 to 3 The results below show that the transformation of the organic matter of the sludge is not a simple thermal conditioning and that it also involves a chemical transformation of the

  organic material by means of a "reactive solvent".

  In this respect, non-aromatic hydrocarbons (paraffin, silicone oil, oil resulting from liquefaction of sludge, etc.) constitute rather inert solvents compared with aromatic hydrocarbons and lead to fairly low liquefaction yields (less than 35%). despite

  higher reaction temperatures.

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  Temperature. Solvent Duration Solubilization rate C h of organic matter% 300 Paraffin 3 34 el 300 Silicone 3 16 300 Pure oil 3 32 from sludge

Example 4

  The procedure is carried out under the operating conditions described in the preceding comparative examples, but with

  1-methyl-naphthalene, at 2300 C only.

  Although the temperature is much lower, for an identical duration of 3 hours, the yield is 55%, compared with 16 to 34%

only comparative examples.

  Comparative Example 4 g of sludge solids are mixed with 220 g of a silicone oil. The mixture is brought to

  3000 C then stirred at this temperature for 3 hours.

  After filtration, an insoluble residue (88.8 g) which contains all the ash (ie 60 g) or a significant proportion of the organic material (58.8 g) is recovered. This residue composition reflects a rate of

  maximum liquefaction of organic matter of 16%.

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Claims (8)

  1. A process for converting waste containing organic matter to produce a high calorific fuel fluid, characterized in that it carries out a heat treatment of the waste in the presence of a hydroaromatic solvent, at atmospheric pressure and a temperature of between 200 and 2800 C, the combustible fluid being recovered in the reaction medium after removal of the insolubles and the solvent. 2. Method according to claim 1, characterized in that the hydroaromatic solvent is selected from the range comprising tetralines, naphthalenes, methylnapntalenes, creosotes, anthracenes,   chrysenes and their oils and mixtures.   3. Method according to claim 1, characterized in that the waste is selected from the group consisting of sludge treatment plants or garbage treatment plants and greasy residues or meat slaughterhouses.   4. Method according to claim 1, characterized in that the heat treatment is at reflux of hydroaromatic solvent. - 12 - 015   5. Method according to claim 1, characterized in that the duration of the treatment is between 1/2 and 5 hours.   6. Process according to claim 1, characterized in that the liquefaction yield is between and 60%.   7. Combustible fluid obtained by the process according to claim 1.   8. Combustible fluid according to claim 7, characterized by a higher calorific value included between 8,500 and 9,500 Kcal / kg.