MANURE GAS PLANT FOR THE BATCH TREATMENT OF WASTE

Abstract: A manure gas plant for the batch treatment of liquid manure without stirring and circulation, which plant comprises a manure gas tank (5) whose cross-section area narrows towards both the top and the bottom thereof, characterized in that the greatest cross-section area of the tank is near the bottom thereof, so that the greater part of the sides and the end walls (6) of the tank lean inwards; that the side walls join the bottom without sharp edges, the bottom being rounded; that an inlet pipe (4) for fresh liquid manure, an outlet pipe (8) for de-gassed manure, and a heating coil (7) are provided at the bottom of the tank; and that the top of the tank is fitted with one or more outlet pipes (9) for gas.

Description: Manure Gas Plant for the Batch Treatment of Waste The present invention is concerned with a manure gas plant for the batch treatment of liquid manure without stirring and circulation. Plants for the extraction of methane (CH 4 ) and the treatment of liquid manure (livestock manure and urine) and sludge from household effluent, or manure gas plants, shall be as efficient as possible for the evolution of methane. Such plants shall, moreover, be simple, preferably without moving parts, and hence easy to maintain and more or less safe from wear. Liquid manure is a quite sticky substance which tends to cling to the sides of the manure gas tank. Other known plants and tanks for the anaerobic treatment of waste products, having a section which narrows both upwards and downwards (cf. for example British Patent No. 655 632 and German Patent Applications No 1 135386, 1 237026 and 1 246 610), are therefore equipped with large mixing screws and extra motors for the removal of the liquid manure. Further, these previously known tanks have taken the form of vertical cylinders, of capacity 3 approximately 75 , equipped with pumps which, because of the dif¬ ference in levels, operate inefficiently, and their gas yield is 3 rather poor, approx. 1/10 m per day per cubic metre of liquid manure. The manure gas plant of the present invention is characterized by the following features: that it has a self-cleaning, rounded conical profile and a simple flushing system; that the plant is arranged in horizontal tanks the cross-section area of which narrows towards both the top and the bottom thereof; that the tank has its greatest cross- section area near the bottom, so that the greater part of the sides and the end walls thereof lean inwards; that the side walls join the bottom without any sharp edges, the bottom being rounded; that a pipeline for fresh liquid manure, an outlet for de-gassed liquid manure, and a heat¬ ing coil are provided at the bottom of the tank; and that the tank is equipped with one or more gas outlet pipes at the top thereof. By this arrangement the sloping sides can be flushed with liquid manure, as they are in the immediate neighbourhood of the flushing jet, whereby an effective cleaning action is achieved (similar to the action of a stream running down a cliff), in contrast to previously known plants, in which floating solids, in the course of heating, got baked onto walls of the tank and there was no way of activating this material the British and German plants mentioned above at page 1, lines 13 a 14). Manure gas plants for the batch treatment of liquid manure wit stirring or circulating have high efficiency; liquid manure from li 3 stock yields 1 m of methane per day per cubic metre for 40 days. Provision is made for the maximum yield of gas in the material, wit 3 regard to a distribution of over the profile area in the proport 40 % high x 60 % wide, exactly the form of the invention. In the s of the manure gas plant I have taken account of the fact that the liquid manure separates into its constituents after de-gassing for 40 days, so that solids rise to the top and the urine (used as flus fluid) sinks to the bottom of the tanks. At the end of this time, one begins pumping out the flushing fluid at the bottom, the solid matter will sink and drop off the sides of the manure gas plant (th to its rounded conical profile), and by pumping continuously the sa manure consistency is obtained as when the manure was pumped in. T avoids the need for large extraction screws and heavy-duty mixing motors. In the embodiments illustrated in the drawings, a variety of materials can be used, according to the invention, such as concrete piping with airtight packings, welded 5 mm steel sheet coated with plastic on the inside of the tank, and, finally, reinforced glass fibre. The plant consists of a manure drain (1) from the cowhouse etc., leading to a holding tank (2). Mounted in the holding tank ( is a liquid manure pump (3). Liquid manure is pumped from the manu pump (3) in the holding tank (2) via a pipeline (4) to the self-cle ing manure-gas tank (5) with rounded conical profile and inward-lea ends (6). Upon heating to 36° C the liquid manure evolves gas. He ing is effected by a methane-fuelled tubular boiler, the heating me being recirculating hot water which is pumped by means of an electri water-pump to a heating coil (7). Once the evolution of gas is com pleted, after about 40 days, the liquid manure is pumped from the liquid manure tank (5) via return/flushing lines (8) back .to the hol ing tank (2), whereafter it can be transferred to a storage tank. " Mounted at the crown of each manure tank (5) there are two hinged manhole covers (9) with airtight packings. Each manure gas tank, of whatever material it may be made, is provided with a thermally insu¬ lating jacket of weather-resistant material. 3 I have two experimental plants, one of 50 m made of steel sheet, 3 the other of 18 m made of concrete piping. The use of self-cleaning concrete pipes of rounded conical profile, with airtight packings, gives a very flexible plant, as additional units can be added as ex¬ pansion is desired. The manure gas plant may further be buried in the ground, reducing its environmental effects. The dimensions of the entire plant, or of parts of it, can be increased or reduced as re¬ quired. A manure plant as in Claim 1 is already provisionally protected and disclosed to The Patent Office, 25 Southampton Buildings, London W.C.2A. IAY under Kjeld H. SjzSrensen, 28 Sept. 1977, No. 40290.

Claims: Claims Claim 1 is for a manure gas plant for the batch treatment of liquid manure without stirring and circulation, which plant comprise a manure gas tank (5) whose cross-section area narrows towards both top and the bottom thereof, characterized in that the greatest cross section area of the tank is near the bottom thereof, so that the gre er part of the sides and the end walls (6) of the tank lean inwards; that the side walls join the bottom without sharp edges, the bottom being rounded; that an inlet pipe (4) for fresh liquid manure, an outlet pipe (8) for de-gassed manure, and a heating coil (7) are pro vided at the bottom of the tank; and that the top of the tank is fit with one or more outlet pipes (9) for gas.

Inventors: SORENSEN K
Applicants: SORENSEN K
Application year: 1979
Main classification: C02C1
IPC codes: C02F3, C12M1