FR2698641A1 - Elimination of hemicellulose, silica and mineral salts from vegetable waste - by adding soluble nitrogen salts to opt. ground waste, anaerobically fermenting then washing and bleaching residues for use in mfg. paper pulp - Google Patents

Abstract

In a non-polluting process for eliminating hemicellulose, SiO2 and mineral salts in vegetable waste, the waste, opt. ground, is seeded, opt. after addn. of sol. N salts, fed into a non-hermetic vessel and anaerobically fermented, to produce biogas, utilisable proteins and residues. Residues are washed as completely as possible and bleached, before being used in mfr. of paper pulp, or being dried for despatch to manufacturers of paper pulp. The washed residues pref. undergo a 2nd biological operation, giving conversion into animal fodder and with the lignin joining the fibres used for paper pulp. The biogas, opt. purified, is withdrawn by gas engine, opt. with a turbo-compressor, and is transformed into mechanical and opt. then into electrical energy and the exhaust gases are used to dry the prods., e.g. residues and the slurries. Cooling water from gas engine, withdrawn at about 90 deg.C, loses heat in reheating fermentation vessel or in a other industrial process. USE - The biogas can be used for heating and for prodn. of mechanical and electrical energy. The microbial sludge can be used to feed the soil or in feeding animals.

Description

Economic and non-polluting processes and equipment
to make paper pulp by anaerobic fermentation.

 Vegetable waste is any fibrous plant product that humans and non-ruminated animals cannot digest.

 Pulp manufacturers have for many years used this waste like grain straw to make paper.

 They abandoned this production because the deliveries were irregular, the storage difficult and cumbersome and the preparation of the pulp of straw paper was twice more content and twice as polluting than the preparation of wood pulp.

 The whiteness of the pite also posed a problem that ozone bleaching has recently resolved.

 However, new machines have made it possible to replace the 40 kilog straw bales with 300 kilog straw rolls and the need for rotation forces cereal farmers to cultivate fodder and dry them to send them to breeders.

 To become less dependent on petroleum products, the forage dehydrators tried to burn the straw but, to prevent the formation of silicates in the fore hearth of conventional dryers, they were forced to add old paper to the straw.

 The upcoming introduction on the market of a steam dryer consuming, instead of 800 kWh thermal per tonne of evaporated water, only 200 kWh electric at most and the hope of soon being able to have a dryer consuming less than 100 kWh electric consider replacing the burning of straw providing approximately 3,000 kWh of heat per tonne with methane fermentation providing only 1,394 kWh of biogas transformed by a gas engine into 400 kWh electric, 600 kWh of exhaust fumes and 348 kWh of water at 900 ° C with 46 kWh losses.

 However, these days, industrialists and laboratories are starting to make straw pulp by reducing the pollution caused by hemicelluloses, by transforming them by enzymes into sugars suitable for feeding non-ruminant animals.

 Unfortunately, enzymes are not free and sugars do not carry the mineral salts found in straw.

 On the other hand, the methane fermentation of straw or other cereals is easy to carry out, if nitrogen is added in the form of soluble salts to obtain the necessary P: 5 and if for example it is sown with the selected microbes contained in the mud pond in an enclosure producing biogas.

 By maintaining the enclosure at a temperature to choose between 250 ° C and around 6 ° C (pasteurization) it facilitates the proliferation of microbes which cost only the heat lost in the cooling water of the gas engine. These microbes entail a non-negligible amount of minerals contained in the waste.

 In addition, the proteins contained in these microbes can be used to feed in particular crustaceans, fish, mammals or, for example, to restore to the soil in soluble form much of what the cultivation of cereals took him away.

 To make paper pulp, the dehydrators of fodder installed on cereal soils are therefore better off fermenting the straw rather than using expensive enzymes.

 In accordance with the present invention, they will also have an interest in fermenting the cereal waste throughout the year. and to sell methane energy to EDF in the form of electric current if it is not used otherwise, at the same time as they will put proteins and residual paper pulp on the market.

 Given their own needs and the self-sufficiency needs of the E D F, it is easy to imagine that industrialists and even paper manufacturers placed in cereal soils ahead of dehydrators.

 By contagion, small grain producers will also be able to heat or light themselves, from discontinuous fermenters.

 Finally, many governments could replace harmful deforestation in the future of their country with the intensive cultivation of cereals necessary for the survival of their population; with the direct or indirect use of biogas to heat food, instead of wood.

 The present invention therefore consists in using anaerobic fermentation to remove, in the form of usable microbial proteins and combustible gas, as much of the impurities as possible, in the absence of this fermentation, to use the fibers contained in plant waste, it would be necessary get rid of it by chemical methods, generally polluting or costly like enzymes.

 In accordance with the present invention, after extraction from the fermenter, the fermentation residues will be washed in methodical counter-current washers comprising at least two stages.

 The residues leaving fermentation will first be introduced into the first stage of the washer .; in this first stage, the outgoing liquid, in counter-current from the residues, will be introduced, all or in part, into a continuous decanter. This decanter will imperfectly separate the washing water from as much of the fermentation microbes as possible. The microbes will leave this decanter in a kind of mud as thick as possible, the liquid incompletely rid of the microbes will be reintroduced into the washer, against the current of the residues to be washed.

 Optionally, in accordance with the present invention, the residues leaving the first washing stage will enter a second washing stage in counter current with another liquid continuously freed from the fermentation microbes by passage through a second decanter.

 Part of the liquid from the second stage will be introduced into the first washing stage to compensate for the water discharged with the sludge leaving the first decanter.

 Without departing from the scope of the present invention, a third and even other washing and settling stages could also be provided.

 In accordance with the present invention, the residues leaving the last methodical washing will be washed with pure water in a counter-current washer continuously discharging the washing water in the penultimate washer.

 As a result, the residues will be discolored by known methods.

 Leaving the discoloration, the residues will advantageously be sent to the manufacture of paper pulp or, more often than not, disposed by known means, so as to form a continuous strip a few millimeters thick.

 This strip containing approximately 70 to 90% of water will pass continuously from the bleaching device until passing between pressure rollers intended to expel the highest possible quality of water, this water will be conveyed at the head of the last washer.

 In accordance with the present invention, the strips of residue leaving the dryer will be easily wound into coils or more advantageously cut into stacked sheets, as are the bundled pulp sheets like these.

 Part of the sludge will be used to sow the straws.

 Most of the sludge will be used advantageously as it is to fertilize the land, or to feed crustaceans or other animals.

but most often dehydrated on one or more dryers using, in a known manner, part of the exhaust gases of the combustion engine described below
In accordance with the present invention, the biogas produced by the fermentation of waste may, purified or not, be used for heating or for cooking food, but most often it will be, after or without purification, sucked by a gas, to produce mechanical energy with a yield between zero, three and zero, five.

 In accordance with the present invention, the cooling water of the gas engine will be used to maintain in the fermentation enclosure a temperature between approximately 150C and approximately 600C.

 In the absence of an engine, in sites where the outside temperature will be below 250C, the fermentation chambers will be insulated and the chambers will be reheated by burning a small amount of biogas.

 In accordance with the present invention, the exhaust gases from the gas engine will be used in part to dry the residue strips immediately before dispatching them, in part to dehydrate the protein sludge or for any other use.

 Most of the time, in continuous fermenters as well as in batch fermenters, the gas is prevented by various means from escaping into the atmosphere.

According to the present invention it is unnecessary. to prevent the gas from escaping because the gas is intended to be burned or to be sucked by an internal combustion engine and that the fermenters are generally in slight depression compared to atmospheric pressure is not the aspiration of the engine to internal combustion, either by the gas pump sending the biogas to a storage or in household appliances for heating or cooking food, for example
The explosion of the pure air and methane mixture is only possible within a very narrow range of methane concentration, since these are between 8 and 12 Z, which practically prevents any local explosion of spread.

 In addition, the presence of carbon dioxide in the biogas further reduces the chances of explosion; therefore, the escape of gas into the atmosphere does not present any of the explosion risks that the presence of hydrogen would represent by comparison, the mixture of which with air can explode at a hydrogen concentration of between 4 and 96%. .

 The possible presence of air in the gas burned, stored or sucked by the internal combustion engine could only influence the supply of combustion air.

By way of example only, there is shown
Figure 1 - An embodiment of six discontinuous fermenters according to the present invention.

Figure 2 - A plan view of the six fermenters.

Figure 3 - A side view of a bowl 17 and the manure tank 8.

Figure 4 - A working diagram of a nitrogen straw fermentation system intended for the production of biogas, proteins and cellulose pulp.

Figure 5 - An elevation of the fermentation enclosure.

Figure 6 - A profile of the fermentation chamber cut along Y Y '
Figure 7 - A sectional view perpendicular to its axis of the pump 36.

Figure 8 - A detail view of extractors 42 - 43 placed differently than in Figures 5 and 6.

Figure 9 - A view cut along Z Z 'of extractors 42 - 43.

At l, in FIG. 1, the circulation path of the loading and unloading apparatuses will be noted, the lateral edges 2 as flat, as smooth, as horizontal as possible, on which the lips 3, visible in the figure, will come to rest. 1 of any cover such as 5
We also notice 3 lids 4 in place on heaps of fermenting material 6, on the left a lid 5 lifted above an empty bowl 17, more to the left still, a heap 6 of aerobic closed protein material covered with manure distribution device 7 containing the fermentation microbes from the manure tank 8 by the suction line IO, by the pump 11 and the distribution line 12.

 We also note the removable cane 13 starting from gas; each removable cane 13 casts up in an advantageously sealed manner inside nozzles 14; the 6 nozzles 14, of which only the two nozzles on the left are shown, supply gas to the pipe 15 which is maintained in vacuum by the suction of the gas engine 16.

 Between each of the four. horizontal edges 2, a basin 7 has been provided, inclined from the level of the track l, going down, with a slope of 1 to 5 <, or more, from the track to the bottom of the horizontal wall 2, opposite to Track.

 According to the present invention, the rod 13 is put in place on the nozzle 14 and the materials to be fermented are piled up by means of a charger, for example of manure, progressively from the bottom of the bowl 17, so as to produce a pile having a height of approximately 2 meters.

 As soon as the pile is finished, the platform 2 is purged with manure, the manure distribution device is placed above the pile, so as to distribute the microbes as regularly as possible over the entire surface of the plant waste, then put in route the pump ll, to initiate the fermentation which, at the beginning, produces a non-combustible gas. This fermentation is advantageous to avoid the acidity of the liquid manure; finally, the cover 5 is put in place 4 and the gas is usable.

 When the fermentation becomes very slow, we remove the lid 4 by 5; with the same machine, we unload the pile of residues and the bowl is ready for a new loading.

 In FIG. 3: the slope of the bowl 17 and the trace of the pipe 9 returning the liquid manure to the pit 8 are noted.

 In FIG. 4: there is a waste ball I8, the links of which have been removed, the waste shredder 19.1st quenching device 20, the nitrification & sowing device 21.1 'waste feeder 22 in the fermentation chamber. 23.

 The materials lightened by the gas bubbles circulate from bottom to top, floating on the liquid manure and arrive in the extraction system 42. At the exit of 42, the fermented waste enters the counter-current washer 25.

 Note the protein recovery circuit 35; at the outlet of a continuous decanter 26, the water, freed from most of the proteins, enters against the current with the fermented materials, shaken in the washer 25 to facilitate the outlet of the proteins; the waters loaded with proteins leave 25 to be introduced into the continuous decanter 26, get rid of the proteins and return to 25. the proteins are recovered in the form of a kind of cream which must be consumed quickly V Dehydrate before shipment .

 To rid them of all traces of protein, the fermented materials are washed against the current in a second washer 27 with the water leaving the wringing press 29, adding in 32 the amount of pure water necessary and sufficient to moisten the straws and to ensure the reaction: (C6H1005) n + nH2O = 3nC02 + 3nCH.

 Alternatively, the two washers 25 and 27 can also form a single assembly with different inlets and outlets of liquids, without departing from the scope of the present invention.

 The water leaving 27 is sent to the quenching device 10 and, if it does not contain enough microbes, is added at 21, by the bypass 30, part of the liquid leaving the washer 25, upstream of the decanter continues 26.

 At 28, there is an arbitrary ozone bleaching device.

 If the fermentation takes place next to a paper pulp factory, the residues are continuously conveyed to the production intended to eliminate all that is not fibers, in particular lignin.

 Otherwise the materials leaving 28 are drained in the press 29 and the water from the spin is sent at 28 by a pump not shown; these fermented materials, freed from most of the mineral salts, are called residues.

The pressed residues form a sort of mat which still contains approximately 50 Z of water and is introduced into a drying oven 31, where 15 to 20 Z of water are dried by the exhaust gases of the gas engine not shown or , if the gas is used otherwise, by an electric dryer of the patent applied for on July 6, 1989, under N "8909143
In 32, we notice an introduction of pure water; at the exit of the avantaoeusemant the residues are rolled up in 33 and circles then put in tasv by a crane not represented known, or cut in sheets easy to bottalar
FIG. 5 represents an elevation view of the fermentation enclosure 23 of FIG. 4; Figure 6 shows a side view cut by the plane Y, Y 'of the same enclosure.

 At the bottom of FIGS. 5 and 6, there is a cylinder 35 in the periphery of which a powerful pump 36 plays the role of the introducer shown diagrammatically at 22 in FIG. 4. This pump mixes the liquid leaving the overflow 39 and the materials to be ferment, prepared at 21 in Figure 4.

 FIG. 7 shows one of the blades 51 of the rotor of the pump 36.

 According to the present invention, the blading 51 will include at its periphery a very hard and cutting metal knife intended to cut, gradually, the waste which could have straddled the outlet 52 of the material outlet and the 'would have obstructed.

as well
Naturally, the edge of the hole 52 is itself reinforced by a deposit of extra hard metal and as sharp as possible.

 The top of the cylinder 35 is welded to the lower part of the truncated cone 37, inside which the materials to be fermented are distributed; the large base of the cone 37 is welded to the base of a cylinder 38 which is advantageously vertical; this cylinder forms the fermentation enclosure.

 This enclosure is filled with liquid manure on which floats the materials in fermentation lightened by the gas produced; a circular overflow 39 will be placed by experience clearly below the lower part of the extraction apparatus 42.

 According to the present invention. the ferxentation cvlindre is - - cut by two planes 40 and 41 forming between them an angI * Vin inferior to 90 and sy metric, compared to the axis of the cylinder 38.

 In FIG. 6, the ellipse of intersection of the plane 40 with the cylinder 38 is noted. In FIG. 6, it can be seen that the lower part of the ellipse coincides with the lower part of the extraction device 42; this position appears preferable but it is possible, without departing from the scope of the present invention, to place the extraction device 42 lower than the lower part of the ellipse.

In accordance with the present invention. the extraction device will be, I \ rnntnoemment. for example,
V consisting of a tube of diameter, V80 to 100 mm, passing right through the
cylinder 38 and freely rotating on a thrust bearing carried by the left side
inside of cylinder 38 and on a bearing carried by cylinder 44 of large
diameter welded to the right outer part of the cylinder 38; to the party the
further from the enclosure 38, the cylinder 44 has at its lower part
and at its upper part an opening 48, of the same diameter as him, the straws
the fermented go out through these openings.

 The cylinder 44 is blocked at its right end by a plane in the center of which is fixed the bearing supporting the tube 49 of FIG. 6.

 On each of the tubes 49 and 49 bis are fixed fins; the fins located at the bottom and to the left of the enclosure 38 of FIG. 6 have a small surface area; as the fins move away from the left wall and approach the right wall their surface and their number increase so as to transport more fermented waste until it becomes a continuous conveyor screw of the entry of fermented waste into the two cylinders 44 and 44 bis.

 The cylinder 44 is blocked at its right end by a plane in the center of which is fixed the bearing supporting the tube 49 of FIG. 6.

 On the upper part of the cylinder 44 is welded a tubular section of diameter equal to the diameter of the cylinder 44.

 This section will be used to descend into the orifice 48 The materials extracted by the extraction device 43 located above the device 42.

Devices 42 and 43 are nearly identical except for the following
Each of the tubes 49 and 49a carries a conveyor screw 50; the conveyor screw 50 bis of 43 passes right through the enclosure 38 and extends to the bottom of the cylinder 44 bis, the conveyor screw of 42 stops at the start of the opening 48.

 At the connection of each cylinder 44 and 44 bis to the cylinder 38, each of the conveyor screws will be coated at its periphery with a deposit of sharpened extra-hard metal.

Likewise, the part of the cylinder 38 cut to allow the two screws 50 and 50 bis to pass is reinforced by a sharpened hard metal so that the screws cut the straw strands like scissors.

 Without departing from the scope of the present invention, one could also place only one extractor 42 or, on the contrary, place more than 2.

 Finally, on the top of the enclosure 39 is placed a biogas evacuation tube 53 maintained in slight depression by the suction of a gas engine, a pump or a compressor.

 The exchanger which uses the cooling water of the gas engine or any other source of heat has not been shown.

 Any assembly described in FIG. 4 from No. 20 to 44 is coated with a heat insulation not shown.

 All of the devices described above solve the problems of introduction, circulation, extraction and controlled fermentation of dry vegetable waste or not.

 The pump 36 introduces the materials tangentially to the cylinder 35, an air intake not shown makes it possible to prevent possible acidification of the medium, which must remain basic and non-corrosive.

 In the cone 37, the materials spread out to fill the cylinder 38 in which they ferment and rise progressively.

 In accordance with the present invention, if it is desired to quickly amortize the cost of the fermentation enclosure, the duration of stay is limited to the fermentation of hemicelluloses.

 At the end of fermentation, the materials arrive above the overflow 39 and meet the lower extractor 42. The screw 50 extracts all the materials encountered, the materials located on either side of this screw are folded back on the screw 50 bis of the upper extractor 43- through planes 40 and 41.

 This fermenter device constitutes an essential point of the present invention.

 In accordance with the present invention, the operation of the assembly represented in FIG. 4, can be continuous or discontinuous without any inconvenience, but the fermentation stops only by cooling below 11 "C the materials contained in the pregnant 38.

 It is suitable to have an asynchronous gas generator capable of delivering current on the E.D.F.

 In accordance with the present invention, moreover, provision could be made for storing gas so as to send current during the peak hours that 1'E.D.F. would pay more.

 As provided in line N of page 2, in accordance with the present invention, the residues, dried or not, wound or not, can advantageously replace the wood for making pulp.

 In accordance with the present invention, it is also necessary to use all the microbial and other means (enzymes) capable of transforming into food all that is not fiber and in particular lignin.

The present invention is applicable to any plant waste from an annual or biennial plant or from evergreen leaves or not
The aerobic fermentation mentioned in the context of the discontinuous operation is optional.

Claims (10)

 R E V E N D I C A T I O N S  pulp manufacturers.  manufacture of paper or dried pulp to be shipped to  as perfectly as possible, bleached, before entering  usable and residues; in that these residues are washed  lie anaerobically and produce biogas, proteins  tuely ventilated, then introduced into an airtight enclosure, iron  soluble, waste, ground or not, is sown and eventually  characterized in that, after or without addition of nitrogen salts  silica and mineral salts contained in plant waste  1Pjo'aé. ' polluting name for elimination of hemicelluloses, 2 Method according to claim 1, characterized in that the  washed residues enter a second biological operation  able to transform into animal feed  lignin joining the fibers intended for the dough to  paper. 3 Method according to claim l, characterized in that: organic  gas, purified or not, sucked by a gas engine with or without a  turbocharger and thus transformed into mechanical energy  then, possibly, electric and in that the exhaust gases  are used to dry products such as residues.,  sludge and the like. 4 Method according to claim 3, characterized in that the water  gas engine cooling systems maintained in the vicinity of  900 C, eliminate their heat by heating the enclosures  fermentation or for any other independent industrial application  whether or not pending. 5 Fermentation apparatus for implementing the process,  according to any one of claims 1 to 4, characterized  in that each anaerobic fermentation enclosure is hand  held in slight depression. 6 Apparatus according to claim 5, type 8 fermentation  discontinuous anaerobic, characterized in that the  garbage, crushed or not, is piled up in a bowl  slight slope, sown with methanogenic ferments and, after or  without aerobic fermentation, are covered with a kind of  hat with brim insulated or not, posed by its edge on  surfaces advantageously as flat and horizontal as pos  and  sible Surrounding the bowl completely; in that the liquid manure  containing the fermentation microbes of one or more  cuvettes, rassmbl8 in a pit is pumped and distributed on the  waste to be fermented,  7 Apparatus according to claim 5, of the fermentation type  anaerobic continua, characterized in that the waste is taught  mmented in methane fermentation microbes provided, for example  ple, by pond sludge, in that this set possibly  air-conditioned is introduced by pumping into an enclosure  insulated or not, and put in slight depression by a pump or  by the depression of the suction of a gas engine.  8 Apparatus according to claim 7, characterized in that the  materials to be fermented are finely ground, are sown  with pond sludge or with selected microbes, are  introduced by a pump, fig. 7, fitted on the rotor and on auba  ages of hard and cutting spite, for example, to avoid any blockage,  receive an upward pressure from the bubbles of the released gas  to the point of floating above the liquid, meet one or more  extractors and fall on this or these extractors  by reflection on planes 40 and 41, presenting an angle between them  in principle  V acute by forming one or two slopes above the enclosure of  fermentation 23.  9 Apparatus according to claim 8. characterized in that each  extractor consists of a shaft, carried by an internal bearing  laughing at the assembly 23 and by a second bearing carried by a small  cylinder outside the assembly 23 and driven by a geared motor  outside the enclosure; in that, as close as possible to  the wall 23 carrying the inner bearing, the rotating shaft carries  a single small propeller blade, then gradually  larger and larger surface blades as  the distance from the inner bearing to form a heli screw  complete coidale provided with cutting edges at the passage of the wall of  enclosure 23, the furthest from the inner landing.  be in the small outer cylinder and for a lower extractor  ends before extraction port 48. 10 Fermentation apparatus according to claim 9, characterized in  that it has several similar extractors, located above  or in the vicinity of each other, the neighboring extractors being agen  such that the helical screw of an upper extractor  pours beyond the end or through the end of that  of the immediately lower extractor.