GB2061248A

GB2061248A - System for producing methane from sewage

Info

Publication number: GB2061248A
Application number: GB8031008A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1979-10-22
Filing date: 1980-09-25
Publication date: 1981-05-13
Also published as: FR2467530B1; IT1125547B; DE3038227C2; GB2061248B; ES8106686A1; DE3038227A1; ES495488A0; YU41947B; IT7926689A0; YU259780A; FR2467530A1

Abstract

A system for producing methane from sewage comprises a temperature controlled anaerobic vessel (1) communicating with a sewage supplying device (3) and having a gas discharge duct (10) in an upper portion thereof communicating with a gas collecting tank (13) and a treated sewage discharge duct (20) at an intermediate portion thereof. <IMAGE>

Description

SPECIFICATION A system for producing methane starting from sewages in general and the like The present invention relates to a system for producing methane starting from sewages in general and the like.

As it is known, a problem which has been felt for a long time, is that of reducing to a minimum the energy wastes and exploit as far as possible any wastes, in order to recover therefrom the potential contained energy.

Among the wastes containing amounts of exploitable energy are to be cited the sewages in general, and, more particularly, the cowshed sewages.

Presently these cowshed sewages or wastes are only used as fertilizers and, in this use, the sewages are dispensed from suitable basins, thereto the sewages are conveyed and caused to "rest" for a predetermined period of time.

This resting time is necessary in order to allow for chemical reactions to occur in said sewages, effec tire to transform the sewages into fertilizers.

However it has been found that, during this sewage resting step or period, a certain evolvement of gas occurs, which has been considered a negative phenomenon, since it is susceptible to cause pollution of the environment.

None has attempet of conveying said gases, for a possible use thereof, since the gas amount has been considered as poor with respect to an advantageous exploiting.

The present invention sets out to reduce the drawbacks thereinabove cited, by providing a system for producing methane starting from sewages in general, effective to permit a satisfactory energy recovery to be obtained, jointly to a more quick treating or processing of the sewage, thereby allowing for the sewage to be immediately available as a fertilizer.

Within that aim it is further possible to arrange that the system for producing methane starting from sewages in general is formed by few parts and of reduced size.

It is further possible to arrange that the methane producing system is greatly reliable and of high safety and not susceptible of polluting the environment.

It is furthermore possible to arrange that the methane producing system is practically devoid of maintenance, and has negligible servicing costs, thereby permitting great energy amounts to be recovered, in the form of gaseous methane.

It is furthermore possible to arrange that the methane producing system is susceptible to be easily constructed by using easily commercially available elements, while being greatly competitive from a merely economic point of view.

The task and objects thereinabove stated, as well as yet other objects which will become more apparent thereinafter, are achieved by a system for producing methane starting from sewages in gener al and the like, according to the invention, characte- rized in that it comprises an anaerobic temperature controlled vessel, in communication with a sewage supplying device.

From the top of said vessel a gas discharging duct extends, in communication with a gas collecting tank, while at an intermediate position on said vessel there is provided a duct for discharging the treated sewage.

Further characteristics and advantages will become more apparent from the following description of a preferred embodiment, though not exclusive, of a system for producing methane starting from liquid sewages in general and the like, being illustrated by way of an indicative but not limitative example in the accompanying drawing the sole figure whereof represents schematically a methane producing system according to the present invention.

Referring particularly to the drawing figure, the system for producing methane starting from sewages in general and the like, according to the present invention, comprises an anaerobic temperature controlled vessel (1), being tightly closed at the top by means of a cover (2) effective to provide a good thermal insulation.

The vessel (1 ) communicates with a sewage supplying device, indicated at (3), and connected to the vessel (1) by means of an inlet duct (4), leading to the lower portion of the vessel (1).

In the inside of the vessel (1), there is provided a stirrer (5), preferably of the radial-arm horizontalshaft type, acting to maintain in continuous movement the sewage pool collected in the vessel (1), in order to favour the gas evolvement chemical reaction.

Said stirrer (5) is rotated about its pivoting axis by an electric motor or the like means.

At the top of said vessel (1), and, more specifically through the insulating cover (2), there is provided a gas discharging duct (10), leading to a scrubbing tank or vessel (13), for the collection of the evolved gas.

The tank or vessel (13) is provided of the safety means as normally provided for a gas containing tank.

The scrubbing vessel or tank (13) provides the very important function of acting as a diaphgram on the connection between the tank and the vessel, in order to prevent possible back-fires or other potentially dangerous conditions from occurring.

At an intermediate portion of the height of said vessel (1) there is provided a treated sewage discharging duct, indicated at (20), which treated sewage discharging duct is provided with a siphon (21), leading to a collecting header (22) for collecting the treated sewage, the latter being susceptible to be directly used as a fertilizer.

The instant methane producing system operates in a very simple way.

In fact the sewage, as preferably collected from cowsheds and the like, is introduced into the vessel (1), where it is maintained under continuous movement by the stirrer (5), acting to facilitate the chemical reaction causing the evolvement of methane from the sewage, during the sewage treating.

Then the gas is conveyed or caused to flow to the tank, whence it can be collected for any uses deemed necessary.

By way of example, which is not to be considered as limitative of the invention, from practical experimental tests, the system has been realized by using an anaerobic vessel having a capacity of 9m3 and a filling coefficient of 0.85.

The used sewage contained 20% by weight of cow dry excrements, which have been treated at a temperature of 25 C, in an environment having a pH of 7.

The output gas, evolved during the anaerobic reaction in the vessel, has a gas pressure of 150mm H2O, and an average daily yield of 10m3 has been obtained.

Advantageously the gas containing or collecting tank has been realized with a capacity of 3m3.

The obtained gas has very satisfactory energetical characteristics.

In fact, from a chemical analysis it has been determined that said gas comprised: CH4(methane) 57% CO2 42.5% CO absent 2 absent other gases NH3-H2S trace amounts calorific power Kcal 5,000 Thus from an analysis of the carried out tests it should be apparent that the testing of the cow dry escrements and sewage in general permits to produce or obtain a great amount of energy, in the form of methane gas, thereby broadly justifying its use both for domestic and industrial applications.

Practically the instant methane producing systems provides two great advantages.

The first is that of producing a great energy amount and the second being that of remarkably speeding up the treating of the sewages, as collected from cowsheds, thereby permitting said sewage to be quickly, and practically directly, used as fertilizers on the fields.

Furthermore the system does not require any controlling persons, since it can be easily automatized, thereby avoiding any use problems.

The invention as described is susceptible to several modifications and variations, all falling within the invention scope.

Furthermore all of the details can be replaced by other technically equivalent elements.

In practicing the invention, the used materials as well as the specific shapes and sizes can be any according to the needs.

Claims

1. A system for producing methane starting from sewages in general and the like, characterized in that it comprises an anaerobic temperature controlled vessel, in communication with a sewage supplying device and in that, from an upper portion of said vessel, a gas discharging duct extends, being in communication with a gas collecting tank, at an intermediate portion of said vessel there being provided a duct for discharging the treated sewage.

2. A system for producing methane according to the preceding claim, characterized in that said vessel is closed at the top thereof by a cover made of an insulating material.

3. A system for producing methane according to the preceding claims, characterized in that it comprises a stirrer, in the inside of said vessel, being preferably of the radial-arm horizontal-shaft type, an electric motor being provided for rotating said horizontal shaft about the pivoting axis thereof.

4. A system for producing methane according to one or more of the preceding claims, characterized in that on said gas discharging duct there is interposed a scrubbing tank or vessel.

5. A system for producing methane according to one or more preceding claims, characterized in that said ductfordischarging said treated sewage from said vessel is provided with a siphon.

6. A system for producing methane substantially as hereinbefore described with reference to the accompanying drawings.