DE3904326A1 - Process for the collection and removal of harmful gases or putrefaction gases by means of hoods floating in the liquid manure - Google Patents

Abstract

The collection and removal of harmful gases above the liquid-manure surface is characterised by a gas-tight hood which floats in the liquid manure. The surface of the cover is designed so that material (faeces, urine, rain and the like) falling down onto the hood from above can slide off into the liquid manure. Under the hood, the gases generated in the liquid manure are collected and are discharged separately via a pipe/hose system. The pre-eminent object of this technique is to reduce the fraction of harmful gases in the stable air. The process can also be used for other surfaces which are liquid to pulpy and in which putrefaction gases are generated (liquid compost).

Description

Process for collecting and removing harmful gases or digester gases through hoods floating in the manure.

1. The manure and its disadvantages

Liquid manure is a mixture of urine and feces. The animals in modern stables are kept on slatted floors ( Fig. 1). The excrement (urine and faeces) they excrete falls through the slatted floor. There is a collecting basin under the slatted floor in which the excrement can be collected and stored as liquid manure. Due to the open slatted floor, the slurry is in direct contact with the barn air above it. This type of husbandry has major disadvantages for the climate, husbandry, health and the environment.

a) Pollutant gas formation

Most of the harmful gases are generated in the manure. The manure is not a dead habitat, but an ideal biotope for Microorganisms and parasites. Aerobic and anaerobic bacteria use the organic components of the manure for their Metabolic activity. As end products arise a. Gases. These gases (NH3, H2S, CH4 and others) escape from the manure and mix with the stable air. Since these gases e.g. B. on the Mucous membranes of farm animals kept in the stable are irritating (negative Effect), they are also referred to as harmful gases. The Incidence of disease and the severity of the disease increase increased proportion of harmful gas. As a result of deteriorated air quality must the warm stable air in increased Dimensions are replaced by cold fresh air. In this process However, the temperature of the house becomes a disadvantage for health and Mast output reduced. On hot summer days it is Pollutant gas formation in the manure even so strong that one Failure of the house ventilation to a mass extinction of the in the house kept farm animals can come. In the stables are therefore i. d. R. Warning systems or emergency generators installed.  

Because of the adverse effect of the harmful gases for the Animal husbandry is endeavored to eliminate these, or to Reduce. So far, this has been done by:

• - Heating the barn with the aim of increasing Fresh air supply in winter
• - Fresh air supply in large quantities in summer
• - Reduction of the slurry tank under the slatted floor and a resultant more frequent emptying of the Slurry tank
• - Extract the exhaust air below the columns so that the Pollutant gases to a lesser extent with the house air be mixed.

b) Parasite propagation

Parasites such as B. Flies multiply by laying eggs. The Eggs develop into larvae and develop via metamorphosis from this adult flies. The slurry surface is suitable as ideal habitat for these processes: it is always moist and never dries out, it is warm due to the bacterial Activity and it is protected from natural enemies. Because of of these ideal conditions is the slurry surface in the summer of a real lawn covered with flies. The ideal Propagation conditions lead to a massive occurrence of Flying in the vicinity of open manure surfaces. To Eliminating this pest infestation requires regular chemical Pesticides are used.

c) Evaporation of water on the liquid manure surface

The moist slurry surface ensures constant evaporation of water. This water evaporation removes the manure and thus the stable evaporation energy. She also wears in winter especially in poorly insulated stables that condensation builds up condensation on cold walls forms. The condensation is then responsible for the Moisturizing the wall and for the resulting still poorer insulating properties of the wall. This loss of energy  favors a wet and cold, unhealthy climate in the barn.

d) cooling of the barn

The fresh air supply in the barn ensures the exchange of Barn air and the simultaneous reduction of harmful gases. The Exchange of warm stable air for cold fresh air however always result in a loss of energy. One too fast Exchange of the stall air even has the disadvantage that the stall cools down especially in winter. A too cold stable climate calls also diseases.

e) Energy costs through continuously running fans

In summer when the weather is warm, the harmful gases are created in the manure in such a large quantity that the manure is literally bubbling. To Avoid adverse effects for animal husbandry the fans powered by electricity to maximum performance to run. The electricity costs are due to continuous operation significantly increased.

f) Environmental pollution caused by the emission of the house air

When the house air is exchanged, it is (previously) unpurified in blown the environment. A dust and smell nuisance in the The immediate vicinity of the stable is the result. The degree of Harassment is directly related to the Noxious gas generation in the manure.  

2. Methods for collecting and removing harmful gases or Digester gases through hoods floating in the manure.

The collection and removal of harmful gases above the slurry surface is characterized by a gas-tight hood that floats in the slurry at its edges ( Fig. 2). The hood can for example have the shape of a building roof ( Fig. 3), a barrel vault ( Fig. 4), a diving bell or the like. The hood lies on or in the slurry at the edges. The air space above the hood is thus separated from the air space below the hood. This prevents gases from passing under the edges of the hood.

The gases that form in the manure collect under the hood. They reach the liquid manure surface as more or less small bubbles and converge into a large bubble. The gases can then be discharged through a hose-tube system that taps into the bladder ( Fig. 8). The overpressure created by the gas formation can be used as the driving force for the removal of the gases. However, the gas can also be actively drawn off by an additional technique.

The stable is above the hood. The excrement (faeces, urine) excreted by the animals falls from above onto the hood. The hood is designed so that the excrement falling on the hood can slide to the edge of the hood and get into the manure there ( Fig. 2).

3. Requirements and embodiments of the hood and the Hose tube system

The purpose of collecting and removing in the manure emerging gases can with hoods of different shapes and Size and different materials u. a. be carried out. A few criteria are therefore discussed in more detail below will.

a) Size and shape of the base of the hood

The size and shape of the base of the hood are variable. They primarily depend on the conditions of the slurry surface and the slurry pit. (Size: e.g. 1.00 m × 0.5 m or circular with a diameter of 14.00 m. Shape: e.g. square, oval or irregular). The effect of collecting harmful gases is directly related to the manure surface covered by hoods. The goal is to cover as much of this area as possible with hoods. This is achieved when it is possible to cover almost the entire surface with a single hood, which then reaches up to the edge of the slurry surface (e.g. in the slurry tank) ( Fig. 9). In the barn under the slatted floor, however, it will be necessary to install many smaller hoods instead of one large one ( Fig. 1). Criteria for the selection of size and shape are to be assessed individually for each barn:

• - a uniform slurry pit or division into Slurry channels
• - Size of the access hatch in the manure pit or Possibility to close the gaps when inserting the hoods remove.
• - Liquid fraction of the excrement: the higher the Urine content, the better the excrement slides on the edge of the hood and the wider the hood can be be constructed
• - Inclination of the hood surface: the steeper the better  the excrements slide and the wider the hood can be be constructed.

If the slurry area is too large, it makes sense to increase the hood size divide and distribute several small hoods in the manure so that the path of the excrement on the hood is shortened.

b) Shape and angle of inclination of the hood

The shape of the hood is variable.

The goal is for the edges to float in the manure, so that the gases can collect under the hood.

The excrement falling from above, however, should be as possible can slide quickly into the manure. If there is a slope The excretion products slide faster on the hood surface to the edge of the hood and get into the Slurry.

The requirements can be met with hoods of various shapes: z. For example: barrel vaults ( Fig. 4), inverted tray, house roof ( Fig. 3), egg pallet or other irregular shapes. It is also possible to use existing forms of e.g. B. used chemical or oil containers for this purpose. A round chemical container, for example (198 liters) with a closed screw cap, only has to be divided lengthways and you have two hoods with the shape of a barrel vault.

For example, the hood can also look similar to one large range of eggs. The gases are shaped like a mountain domes looking upwards. The domes are through Foothills connected to each other and thus enable one Gas exchange. Between the domes are down open valleys that reach into the manure. The one from above falling excrement slides into these valleys. At the bottom of this Holes are attached to valleys. The excrement passes through this Holes in the manure.  

c) material

The hood can be made of different materials or Combinations of materials can be made. The following criteria should be noted:

• - gastight
• - Floating materials: for non-floating ones Materials (for metals, additional Floats are attached).
• - Resistance to decomposition in the slurry (iron rust, wood rots after some time)
• - Dimensionally stable, against mechanical stress. At Use of foils, for example, must to be under tension.
• - Hardness: resistance to eating by mice and Rats. Films do not meet this requirement.

d) floats

The hoods turn like upside down boats on the surface. Due to the very high center of gravity, the danger of capsizing is high. It is then no longer possible to collect the harmful gases due to the hood edge in the air. To prevent capsizing, it is therefore advisable to attach additional floats to the hood. These floats are intended to prevent sinking and the appearance of the hood edge at the same time. These requirements are met e.g. B. Wood ( Fig. 5): On the one hand it floats like a raft, on the other hand it is heavy like a log. The goal can also be achieved with the help of solid plastic bodies (too expensive). The specific density of many plastics results in swimming behavior. The goal can also be achieved with hollow floats of various shapes that contain air or gases ( Fig. 6). It is also possible to create cavities that are open at the bottom ( Fig. 7). These cavities then automatically fill with harmful gases and cause the hood to lift.

e) isolation

It is possible to use the hoods from below to coat insulating materials. The isolation has two  Advantages. First, the heat flow from the slurry is reduced, on an insulated hood. Second, a diminished one Energy transmission of the hoods slowed down the drying out Excrement on the hood results. This avoids that the excrements stick to the hood wall.

Eating the insulating layer of mice and rats is not To be feared as there is no oxygen for breathing under the hood is available.

f) composite hoods

Several hoods can also be rigid be connected to each other. This will increase the risk of Caps caps reduced.

g) A hose / tube system is used to drain the collected Gases.

The gas bubble is tapped by the hose-tube system ( Fig. 8). The hose - the tube can then either be led through the roof of the hood, or the hose can be led from the inside of the hood under the hood edge through the slurry. A hose has the advantage of flexibility compared to the stable tube. The hose is easier to lay and allows the hoods to be moved on the slurry surface. The tube, however, is stable and therefore resistant to mice and rats. Hose and tube can also be combined.

Several hoods on a slurry surface can either be in parallel or in series (as in electricity) through the hose Tube system (or combinations between parallel and in series).  

4. The advantages of the method of collecting and removing Pollutant and digester gases

The manure surface is largely covered by hoods and is therefore separated from the house air. From this result Benefits for climate, husbandry, health, management and the environment.

a) Pollutant gas formation:

The noxious gases are collected and discharged, but get there no longer in contact with the house climate. From this result following advantages:

• - The quality of the stable air is significantly improved.
• - Health and quality of life are improved.
• - The fresh air supply and the associated danger hypothermia is reduced.
• - On expensive warning systems and emergency generators to be dispensed with.
• - Stable heating can (with proper insulation of the stables).

b) Parasite propagation

The multiplication of parasites (especially flies) on one with Hood-covered manure surface is significantly reduced. Therefor there are the following explanations:

• - Hood parts that are not constantly excrement fall down, have no damp surface, which the Flies urgently need for their development.
• - On hood parts, on the regular excrement fall down, there is a certain flushing effect. With Parasite eggs and larvae with excrement are continuously fed into the manure, so that the Time period for the development of the parasites too short is. Once the larvae are in the manure under the hood, so is the development due to the the anaerobic environment prevailing here.

c) Evaporation of water on the liquid manure surface

The evaporation of water on the liquid manure surface is due to the Hoods reduced. The amount of evaporation energy that the stall withdrawn in this way is also reduced. In addition, in poorly insulated stables Condensation and dampening of the stable walls prevented. This creates a wet and cold, unhealthy climate avoided.

d) cooling of the barn

The exchange of a warm stable air for a cold fresh air with the consequence of the loss of energy can be reduced. In order to at the same time, the risk of hypothermia in the barn is reduced. Diseases are also prevented in this way.

e) Energy costs due to running fans

The harmful gases generated in the summer in warm weather are from the hoods collected and removed directly. You don't get more in contact with the house air. For this reason, the Fan performance and the correlating energy costs be lowered.

f) Environmental pollution caused by the emission of the house air

The amount of stall air that has to be exchanged is clear decreased. The associated smell and dust pollution for the environment is also reduced.

Reference symbol list:

Fig. 1: Scheme of a pigsty with slatted floor, liquid manure pit and hood for collecting and removing harmful gases
1 pigsty
2 slatted floors
3 slurry pit with slurry
4 hoods floating on the manure.
Fig. 2: Scheme of a hood floating in the manure for collecting and removing harmful gases
1 slatted floor
2 manure
3 slurry surface
4 roof of the hood
5 floating bodies integrated on the hood
6 gas bubble under the hood
7 Hose and tube system
8 excrements that fall between the columns.

Claims (1)

The collection and removal of harmful gases is marked by a above the manure surface gastight hood that floats in the manure at its edges. The Surface of the lid is designed so that the top of the Hood falling material (feces, urine, rain, etc.) into the Slurry can slide off. Under the hood they are in the manure resulting gases are collected and via a tube-hose system discharged separately. The gas can then escape into the environment or used as biogas. The procedure can also other liquid-pulpy surfaces can be used where Digester gases are created (liquid compost).