WO1999043198A1 - Procedure for application of powdered product on agricultural land - Google Patents

Abstract

Procedure for land application of powdered and granulated/pelleted products like bioashes, dried desulphurization product (TASP) from flue gas cleaning in coal fired power plants, powdered lime, fertilizers, herbicides etc. or non-homogenous fluids (like animal slurry with straw residues) on agricultural land. The method is based on a combination of 2 known principles, namely: 1) a drag chain taking the powdered material from the hopper through a pipe past a number of outlets or a long single slit and returning excess powder back to the hopper. Controlled dosage from the outlets by the action of rotating drums, rotating discs with scraper or pulse based from outlets; 2) if a single long slit is used, controlled dosage is ensured by a dosage roller or similar dosage device having a length corresponding to the lengths of the outlet slit.

Description

1 T i t l e o f t h e i n v e n t i o n

PROCEDURE FOR APPLICATION OF POWDERED PRODUCT ON AGRICULTURAL LAND

D e s c r i p t i o n The invention relates to a procedure for land application of powdered products like bioashes, dried desulphurization product (TASP) from flue gas cleaning in coal fired power plants, powdered lime, fertilizers, herbicides etc. and further as mentioned in introductory part of claim 1.

When cleaning gasses from coal fired power plant a byproduct is obtained rich in sulphur named TASP (Tørt AfSyovlingsProdukt, Dried desulphurization product). This byproduct contains about 16% plant available sulphur.

The annual Danish production of TASP is 100.000 tons from desulphurization plants that are expected to be in operation the next 25 years.

The implementation of desulphurization of fluegas has reduced the air and precipitation based sulphur supply to agricultural fields. As a consequence, many crops are demanding application of sulphur fertilizers.

The National Committee on Plant Production estimate the demand as:

15-20 kg sulphur per ha. to cereals corresponding to about 110 kg TASP per ha. 30-40 kg sulphur per ha to rape corresponding to about 220 kg TASP per ha.

From straw fired district heat plant and from the planned use of straw as energy source on power plants, another byproduct is obtained called bioash. The plan is to use 1,2 million tons of straw for this purpose annually.

Bioash contains following plant nutrients: P: about 1 %

K: 20 to 35 %

Normally, bioash has a larger content of heavy metals than allowed according to Danish legislation for slurry application.

Exemption from the Danish Environmental Protection Agency is therefore requested for application to agricultural land.

Normally, it may only be accepted to bring back same amount as removed from the area. 2 Assuming that 5 tons of straw are removed annually per ha. with an ash content of 4%, this will correspond to an application rate of 200 kg bioash per ha.

Similarly, there is a long list of other powdered byproducts, that could be advantageously used as fertilizer on agricultural fields, provided even distribution in well controlled small rates.

Controlled application of TASP and bioash and similar byproducts as they are (not modified) open possibilities for an economic use of these byproducts as fertilizers without costly and energy demanding product modifications/treaments. As parallel to this, the use whey and other wet byproduct in wet feeding could be mentioned. The problem is the same in other countries. In the US f.ex. a lot of trials have been made to test the fertilizing/soil improving effect of products such as fly ash, FGD gypsum, FBC gypsum (Fluid Bed Combustion) especially in areas of acidified soils, where a high concentrations of aluminum inhibit the plants uptake of water and nutrients. In these investigations, the application techniques have not been considered very much. Traditional equipment for lime, fertilizers etc. have been used, giving a high uncertainty concerning the application rate of contained minerals.

Similarly there is a demand for an even and controlled application of other powdered products like fertilizers and pesticides, especially herbicides.

Known methods for application of powdered products on agricultural land are primarily rotating discs as shown on figure 1.

These systems results in an uneven distribution transversely to the driving direction and are not suitable for application of the small rates referred to above. Further, the operation will generate a lot of dust having implication on the work environment, if applied in dry form with this equipment.

To improve the distribution, there has been worked with an auger based dosing system as shown on figure 2. 3 The system is based on the displacement of the screen until an opening is reached that gives the requested dosage. Then the auger speed is adjusted to feed material to all holes plus an amount corresponding to the output from a single hole leaving the end of the auger. During the operation, the driver has to keep an eye on the dosing at both ends of the auger and if necessary just the speed of the auger. This system is difficult to adapt to small dosing rates, because the holes will have to be so small, that serious problems with clogging will occur. Adjustment is also problematic and the system does not allow regulation from driving speed.

The aim of the invention is to eliminates the disadvantages mentioned above. This can be obtained by that, which is described in the characterizing part of claim 1.

The method is based on a combination of 2 known principles, namely:

1) A drag chain taking the powdered material from the hopper through a pipe past a number of outlets and returning not spend powder back to the hopper.

2) Controlled dosage from the outlet by the action of rotating drums, rotating discs with scraper or pulse based emptying from outlets.

The invention allows a freely regulated dosing rate from very low rates. The dosing rate interval can be varied from rates that are lower that known spreading technologies for these products are able to up to rates several times higher, only limited by the transporting capacity of the drag chain. By proper selection of drag chain, the system may be adapted to application of many different types of powdered products

Dosing rate can easily be controlled electronically by varying the number of revolutions of those rollers or rotor discs, that control the dosage rate from the outlets. Within the maximum capacity of the drag chain in question, the system will secure an even distribution between each of the outlets. Depending on task, a few or several outlets can be inserted, whereby the transversal distribution can be accommodated. If an unbroken, even transversal distribution is required, 4 the outlets can be formed as one single through slit and the dosing system as on through roller.

Generation of dust from the time the powder leaves the outlet until it hits the soil surface can be prevented by the use of dragging hoses from outlets to soil surface. Alternatively, a double foil can be established from dosage pipe to the soil surface.

If dust has to be completely omitted, the system can be combined with injectors.

Wear on the drag chain can be compensated by incorporation of a sliding pipe segment in the dosage pipe.

The smaller amount of material in the distributing system, and the resulting relatively small weight of the system, make a large working breadth possible with a collapsible /foldable spreading unit.

Insertion of flexible pieces of pipe in the dosage pipe near the tank (hopper) makes it possible to construct dosage arms, that may be raised for road transport of equipment with large application breadth, which in this way obtains a suitable transport breadth

The invention is explained in greater detail in the following with reference to the drawings, where

figure 1 shows spreading method using rotating discs, figure 2 shows auger based spreading method, figure 3 shows a drawing of dosage system based on drag chain, figure 4 shows alternative methods for controlled dosage.

Fig 3 shows hopper (1), drag chain (2), dosage pipe (3) and outlets (4). Further in fig. 3 are shown adjustment possibility to tighten up the drag chain (5), hose or pipe from the outlet to soil surface (6) flexible joint (7), enabling the folding of the dosage pipe. The drag chain (2) is driven by a driving wheel (8), which again is driven by a hydraulic motor, electric motor or other driving mechanism. At the opposite end of the dosage pipe, the drag chain is supported by a not driving wheel (9) or just U-shaped pipe.

Fig 4 shows alternative systems for controlled dosage from outlets to soil surface. Rotating 5 disc (10) with scraper (14), rotating dosage roller (11), rotating disc with outlet orifice (12), and sliding lid (13).

The dimension of the dosage pipe (3) and the dimension and speed of the drag chain (2) selected so that the amount of powder transported from the hopper (1) is bigger than the maximum discharge from the outlets (4). In this way it is ensured, that there is always excess powdered material above the continuously operating dosage systems, rotating disc with scraper (10) and rotating dosage roller (11). For the pulse based dosage systems, disc with outlet orifice (12) and sliding lid (13) it is ensured that a given amount of powder is released when the outlet (4) opens.

A flexible joint (7) serving the purpose to make dosage pipes (3) foldable for road transportation is made using known technology. The same applies to adjustment device (5) for tightening up of drag chain (2).

Dosage from outlets (4) using rotating disc (10) can be regulated by changing the speed of rotation of the rotating disc (10) as well as by regulating the gearing of the scraper (14).

Dosage using rotating dosage roller (11) can be regulated by changing the speed of rotation of the dosage rollers. By making the dosage rollers (11) in a flexible material, they are affected by mechanical action, which creates vibrations in the dosage rollers (11) in a way that any attached powder is released.

By designing dosage rollers with different diameter, different opening width (a), and different opening depth (b) dosage pattern may be varied from an almost continuously dosage sequence to an almost pulse based dosage sequence.

Proper pulse based dosage systems are regulated by changing the speed of rotation of the disc (12) or the opening frequency of the lid (13).

Claims

Claims.

1. Procedure for application of powdered products granulated/pelleted products and non- homogenous fluids (like animal slurry with straw residues) on agricultural land using a drag chain, pulled transversely to the driving direction characterized by the method involving these two steps:

A) transport of product from hopper using drag chain to outlets, where any excess material are returned to the hopper.

B) dosage of material from outlets using dosage devices, comprising rotating dosage rollers, rotating discs with scraper, rotating discs with orifice or oscillating lid.

2. Procedure for application of powdered products granulated/pelleted products and non- homogenous fluids (like animal slurry with straw residues) on agricultural land according to claim 1 characterized by: discharge takes place from a unbroken discharge lid, the product from step A is transported to one single outlet covering the whole application width, and the product at step B is dosaged by a dosage roller or similar dosage device having a length corresponding to the length of the outlet slit