Title of Invention

PLANT FOR OBTAINING METHANE GAS FROM ORGANIC WASTE

Abstract

The present invasion relates lo a prant for obtaining methane gas from organic waste, with a enunciation climber, a gas collection space and a post-fertnentation chamber, in which the gas collection space lying directly above the fermentation chamber is not separated structure Irion the fermentation chamber, and also with at least one feed duct and one discharge duct for the excess, fermented liquid from the post-fermentation chamber, wherein the chambers are heat emulated, preferably embedded at least partly in the ground and the fermentation chamber and the posifennentation chamber, arranged above the former, are connected m the manner of communicating vessels and are combined into a unit. PRICE: THIRTY RUPEES

Full Text

The'present invention relates to a plant for obtaining methane gas from organic waste, with a termentation chamber a gas collection space and a post-fermentation chamber, in which the gas collection space lying directly above the fermentation chamber is not separated structur¬ally from the fermentation chamber, and also with at least one feed duct and one discharge duct for the excess, fomented liquid from the post-termentation chamber, wherein the cham¬bers are heat insulated, preferably embedded at least partly in the ground and the fermentation chamber and the post-fermentation chamber, arranged above the former, are connected in the manner of communicating vessels and are combined into a unit. Plants of this kind are known in the art. In the construction of plants for obtaining methane gas, microbiological aspects must be taken into consideration in order to achieve utmost yield of gas, whereby it is important to ensure that only such an amount of fresh sludge is fed into the plant that the content of volatile acids in the fermentation mass remains under a deter¬mined rate, that the medium reacts alkaline, that it is provided for constant temperature avoiding sudden temperature transients and that finally escape of gases is not prevented by the formation of surface scum, in other words, efficient production of methane is above all a technical problem of charging and the design of the fermentation chambers and specifically also of elimination of the surface scum . The present invention solves this complex problem with a plant of the afore-mentioned kind in that the upper part of the post-fermentation chamber is connected, on the one hand, via a connecting duct closable by a valve to the gas collection space and, on the other hand, to at least one gas duct leading to a surge tank and the discharge duct is communicated with the post-fermentation chamber and can be opened or closed by the valve time-dependently and or depending on the level of filling in the fermentation chamber and/or gas pressure prevailing in the gas collection space. Advantageous embodiments of the invention are defined in the de¬pendent claims. Accordingly the present invention provides a plant for obtaining methane gas from organic waste, with a fermentation chamber, a gas collection space and a post-fermentation chamber, in which the gas collection space lying directly above the fermentation chamber is not separated structurally from the fermentation chamber, and also with at least one feed duct and one discharge duct for the excess, fermented liquid from the post-fermentation chamber, wherein the chambers are heat insulated and the fermentation chamber and the post-fermentation chamber situated above the former, are connected in the manner of communicating vessels and are combined into a unit, characterized in that the upper part of the post-fermentation chamber is connected via a connecting duct closable by a valve to the gas collection space and is further connected to at least one gas duct leading to a surge tank and the discharge duct is communicated with the post fermentation chamber and the connecting duct can be opened or closed by the valve time-dependently and / or dependent on the level of filling in the fermentation chamber and / or gas pressure prevailing in the gas collection space. In order to illustrate the plant and its function it is now described with reference to the accompanying drawings, in which : •Fig. 1 to 6 is a vertical section of the plant according to the present invention, wherein the various operating states are illustrated in the respective figures; Fig. 7 is a horizontal section along the line VII - VII in Fig. 1; and Fig. 8 is a horizontal section along the line VIII - VIII in Fig. 1. Fig. 1 represents a plant for obtaining methane gas in a sectional view, in fact its principal structure, wherein the plant is filled with the substrate to be fermented. A cylindrical unit 1 with vertical axis which is preferably heat insulated and/or is additionally provided with at least partially beatable wall sections, is entirely or at least partly embedded in the ground dependent on the local conditions where said unit is erected or mounted. Said unit is sepa¬rated by an inner intermediate ceiling 2 into to chambers, namely the fermentation chamber 3 and the gas collecting space 7 on the one hand, and the post-fermentation chamber 4 on the other hand. Fermentation chamber 3 and gas collection space 7 are not separated structurally from each other and form a unified space. A vertical shaft 5 centrally arranged therein con¬nects the two chambers 3 and 4 in the manner of communicating vessels. The term communi¬cating vessels is to be understood here and in the context of the following description only in such a way that the liquids contained in said two chalets have the possibility of flowing back and forth, at least partly. In its area near the bottom, the centrally arranged vertical shaft 5 merges into shovel-like arcuated channel sections 13. As fermentation chamber 3 it is to be understood here and in the fir lowing that chamber be¬ing respectively filled with the liquid to be degassed. The’ gas collection space 7 lies directly above. Said chamber and space, respectively, change their volumes during operation of the plant and it is again pointed out that they are not structurally separated from each other. Near the bottom 8 ground sludge discharge ducts 9 are provided through which sludge accu¬mulating at the bottom can be discharged. The gas collection space 7 and the upper part of the post-fermentation chamber 4 are con¬nected via a connecting duct 10. Said duct can be opened and closed by a valve 11. A further duct 12 leads from the upper part of the post-fermentation chamber 4 to a surge tank not shown here, as for instance a geometer, so that the plant always operates against a constant operating pressure. A discharge duct 18 leads the fermented liquid off the post-fermentation •chortler 4. The valve 11 of the connecting duct 10 may, in this case, be time-dependently controlled. However, it is also possible to control the valve 11 depending on the gas pressure prevailing in the gas collection space 7 or dependent on the respective level of filling. An annular dividing wall 14 separates the post-fermentation chamber 4 into an outer basin 15 and an inner basin 16. The inlet port of the discharge duct 18 lies at the bottom of the outer basin 15 between wall sections 17 forming two overflow edges (Fig. 7). Fermentation cham¬ber 3 and gas collection space 7 are connected to the outer basin 15 through mixing shafts 19. The fresh substrate to be fermented is charged through a feed duct 6. The plant operates with four to eight mixing cycles per day, dependent on the respective kind of the substrate and the process design. Each mixing cycle comprises the same six steps as described in the following: Step 1 - Start of the mixing cycle: l.v.,el 21 of the substrate 20 is equal both in the fermentation chamber 3 and the gas collec¬tion space 7 as well as in the post-fermentation chamber 4. Gas valve 11 is closed. Gas pres- in the post-fermentation chamber 4 is equal to the operating pressure of the gas reservoir connected, but not shown here, being connected to the plant via duct 42. Since no fresh substrate is fed into the plant throughout this step, it follows that no fermented substrate can flow off the system. The gas Step 2 - Increasing difference of level of substrate; Since valve 11 is closed, the gas produced in the fermentation € mixing shafts 19 which are provided here. Gas pres¬sure in the fermentation Chamber 3 is identical with the difference of level between the fer- mutation chamber 3 and the post-fermentation chamber 4 (Fig. 2). This movement is indi¬cated by the arrows in Fig. 2. Step 3 - Greatest difference of level: Fig. 3 shows the operating state of the plant wherein the difference of level D and thus the pressure difference has reached its greatest extent. The post-fermentation chamber 4 is sepa¬rated by a dividing wall 14 into an outer basin 15 and an inner basin 16. Said two basins have no direct connection. The dividing wall 14 is designed in such a way that at no time through¬out the operating process substrate can flow over the dividing wall from the inner to the outer basin. Consequently, the substrate in the inner basin 16 can only be displaced upwards from the fermentation chamber 3 through the central vertical shaft 5. The substrate in the circum¬ferential outer basin 15 can only reach the spidery zone through the mixing shafts 19. Dis¬charge duct 18 starts from the bottom of the outer basin 15. Inflow to said discharge duct 18 is separated from the outer basin 15 by an overflow edge (Fig. 7). Said overflow edge is de¬signed in such a way that even with the highest level of substrate in the post-fermentation chamber no substrate can penetrate into the outlet. Substrate can only flow off the plant from the outer basin 15, on the other hand, charging is only possible through the central vertical shaft 15. Step 5 - Charging and process (Fig. 4) When the highest pressure difference according to the different levels of substrate has been achieved (Fig. 3), charging of the plant with new substrate is started. Fresh substrate is thereby pumped into the central vertical shaft 5 of the plant via the feed duct 6. Charging time and charging quantities depend on the type of the substrate to be treated. When charging a certain quantity of fresh substrate 20 via the feed duct 6 into the central vertical shaft 5, the level in the inner basin 16 and in the surrounding annular basin 15 of the post-fermentation chamber 4 rises. Since the highest level of substrate in the post-fermentation chamber 4 has already been reached, additional rising of the level of substrate following the charging of fresh substrate results in the fact that the now fermented substrate flows over the overflow edge and hence reaches said discharge duct 18. In this way it is ensured that whenever fresh ..substrate is pumped into the plant the same volume of fermented substrates flows off via said overflow edge into the discharge duct 18 and is thus removed from the plant. The freshly charged substrate is now in the vertical contends shaft 5. Step 5 - Mixing: When the plant has been charged substrate, valve 11 is opened (Fig. 5). From this moment on, the pressurised gas accumulated in the fermentation chamber 3 and in the gas collection space 7, respectively, can flow into the post-fermentation chamber 4 and from there via the duct 12 into the connected gas reservoir not shown here. The substrate pressed up into the post-fermentation chamber 4 now flows back into the fermentation chamber 3 via two paths (Fig. 6). The content of the inner basin 16 flows through the central vertical shaft 5 downwards. Thereby, it pushes the volume of fresh substrate contained in the shaft forward, pressing it through channel sections 13 turbulently into the fermentation chamber 3. The substrate 3 contained in the fermentation chamber 3 is thereby vigorously mixed and moved predatorily due to the shovel-like shaped channel sections 13. The pre-fermented substrate is thus mixed into the bio-mass already contained in the fermentation chamber 3. The content of the outer basin 15 of the post-fermentation chamber 4 flows through the mix¬ shafts 19 back into the fermentation chamber 3 and into the gas collection space 7. Owing to the constructive design of said mixing shafts 19, the back-flowing substrate is sprayed onto the surface of the level of substrate pressed down, wets the floating matter contained therein and mixes them again through turbulent movements. A further effect of the repeated increase in the level of substrate in the fermentation chamber 3 is that the floating matters are chafed and broken up when moving along the conical intermediate ceiling 2 and are again mixed into (Fig. 6). ^ Said type of substrate flow ensures that the two essential zones of each anaerobic plant, namely the layers of suspended and settable sludge are vigorously and turbulently mixed sev¬eral times per day. When the mixing process is terminated, time valve 11 is again closed and the cycle described above starts again with step 1. WE CLAIM : 1. Plant for obtaining methane gas from organic waste, with a fermentation chamber (3), a gas collection space (7) and a post-fermentation chamber (4) in which the gas collection space (7) lying directly above the fermentation chamber (3) is not separated structurally from the fermentation chamber (3), and also with at least one feed duct (6) and one discharge duct (18) for the excess, fermented liquid from the post-fermentation chamber (4), wherein the chambers are heat insulated and the fermentation chamber (3) and the post-fermentation chamber (4) situated above the former, are connected in the manner of communicating vessels and are combined into a unit (1), characterized in that the upper part of the post-fermentation chamber (4) is connected via a connecting duct (10) closable by a valve (11) to the gas collection space (7) and is further connected to at least one gas duct (12) leading to a surge tank and the discharge duct (18) is communicated with the post fermentation chamber (4) and the connecting duct (10) can be opened or closed by the valve (11) time-dependently and / or dependent on the level of filling in the fermentation chamber (13) and / or gas pressure prevailing in the gas collection space (7). 2. Plant according to claim 1, wherein the post-fermentation chamber (4) is separated by an annular dividing wall (14) into an outer basin (15) and an inner basin (16). Plant according to claim 1 or 2, wherein the inlet port of the discharge duct (18) is arranged at the bottom of the outer basin (15) of the post-fermentation chamber (4) 4. Plant according to claim 2, wherein starting from the bottom of the post- fermentation chamber (4), in fact from the outer basin (15), mixing shafts (19) lead down into the fermentation chamber (3) and the gas collection space (7), respectively. 5. Plant according to claim 1, wherein the feed duct (6) merges into the central vertical shaft (5). 6. Plant according to claim 1, wherein the vertical shaft (5) is provided at its lower, near-to-ground area with shovel-like channel sections (13) leading into the fermentation chamber (3). 7. Plant for obtaining methane gas from organic waste substantially as herein described with reference to the accompanying drawings.

Documents:

617-mas-1996 abstract.pdf

617-mas-1996 claims.pdf

617-mas-1996 correspondence others.pdf

617-mas-1996 correspondence po.pdf

617-mas-1996 description (complete).pdf

617-mas-1996 drawings.pdf

617-mas-1996 form-1.pdf

617-mas-1996 form-4.pdf

617-mas-1996 petition.pdf