ES1253244U - Slurry drying unit (Machine-translation by Google Translate, not legally binding) - Google Patents

Abstract

Slurry drying unit, for a plant for the treatment of liquid slurry from pigs, dairy cattle and other animal species by drying formed by a greenhouse (24), a regulated ventilation system, a homogenization tank (14) and acidification of the slurry and a natural filter (12) moistened with an acid solution, characterized in that the greenhouse (24) has a radiant floor (100) with a tube (6) made of cross-linked polyethylene, multilayer polyethylene or polybutylene, isolated from the ground with expanded polystyrene (4) or other low conductivity materials, covered with mortar or concrete (3); for having an external energy capture point; by having one or more regulation tanks in the radiant circuit that act as storage units for the excess thermal energy not transferred to the slurry mass; and because it has a heat recovery unit behind the natural filter (12) to heat the water in a heating circuit and to condense part of the evaporated water to be reused as cleaning water. (Machine-translation by Google Translate, not legally binding)

Description

DESCRIPTION

PURINE DRYING UNIT

OBJECT OF THE INVENTION

The invention, as expressed in the wording of the present specification, refers to a slurry drying unit. More specifically, a unit for drying liquid manure from pigs, dairy cattle and other animal species using underfloor heating powered by solar thermal energy and other energy sources.

The object of the invention is a high-performance unit for drying liquid slurry from pigs without ammonia emissions to the environment, equipped with a radiant floor that can be powered by renewable energies such as: thermosolar, photovoltaic, wind, biomass, etc. geothermal, or other energy supply systems such as natural gas, propane or LPG.

TECHNICAL SECTOR

The present invention belongs to the livestock sector.

BACKGROUND OF THE INVENTION

The drying units have a long history in the agricultural sector for the dehydration of different products such as vegetables, corn, coffee, etc. These units consist of greenhouses equipped with a wooden or metallic infrastructure closed with a polyethylene sheet, ethylene vinyl acetate copolymer, polyvinyl chloride (PVC), polycarbonate or glass.

To determine the energy exchange, the following are taken into account: the intensity of solar radiation, the speed and temperature of the air, the area of the greenhouse enclosure and the values of the specific heats.

There are numerous publications referring to different models of dryers, both for batch drying and continuous drying, some of them using electricity, fossil fuels, or even solar energy, but in all of them the element to be heated is the air that circulates on the product and that is saturated with the water that is extracted from it.

Existing dryers are classified into active systems, with forced ventilation, and passive systems, with natural ventilation. In all of them the main components are:

- A greenhouse that acts as a solar energy collector

- Properly insulated ducts

- A drying surface

- A chimney for the extraction of humid air

And, in addition, in active systems:

- Monitored windows

- Air impellers (fans)

The performance of these facilities is adequate for the dehydration of products of agricultural origin, but it is not sufficient for the extraction of large quantities of water.

There are those that face this problem, such as some facilities that extract salt from seawater, accelerating the evaporation process using photovoltaic energy, following the model of dryers for agricultural products, resulting in an unviable investment.

In the livestock sector, slurry dryers have been set up that essentially follow the same model, with some improvements. It must be taken into account that, in addition to the technical challenge of extracting large amounts of water in a profitable way, in the case of slurry, the emission of ammonia into the atmosphere during the process must be avoided.

The company EMA DEPURACIÓN SL located in Olot, designed in 2014 a greenhouse-dryer for cattle slurry, after concentrating them on the farm (use of drag scrapers). The distinctive elements with respect to the previous greenhouses-dryers are, in the first place, the need to acidify the input slurry until reaching a pH between 5.5 and 6 in order to fix up to 70% of the ammonium present in it, converting it into nitrate, and thus avoiding its emission in the form of ammonia. Acidification is a technique used in Denmark by the INFARM SA company since 2006, and in Spain in physical-chemical treatments (ROTECNA SA company), in drying of slurry by hot air with natural gas in companies such as TRACJUSA, in other greenhouses-dryers implemented by INNOVACC (Catalan Association for innovation in the pork meat sector), SOLARPUR etc. Second, use a stirrer, invented by the company itself, to advance the slurry mass through the dryer as it loses moisture and increases its density, until it is collected in an auger that extracts it outside. The steam emitted during the process is transported by the air entering the greenhouse, being directed by internal fans and extracted by a fan that leads it through a duct to a filter composed of tree bark moistened with an acid solution that will act as a last scavenger of the ammonia that may remain in the extracted water vapor. This technique is based on stripping or degassing, which consists of capturing a volatile component of a liquid effluent through the action of an inducing element that can be air, steam, nitrogen, etc. Widely used in leachate degassing by companies such as TECNIUM.

When wanting to transfer the experience of drying concentrated cattle slurry to slurry with a larger liquid component, such as pig slurry or dairy cattle, the poor performance of the installation required that a solid-liquid separation be previously carried out with separators already on the market and the dehydration of the solid component was carried out, while the liquid fraction had to have a second treatment or be applied to the field, with a content of 80-85% of the N of the fresh slurry. This solution for liquid manure is not very applicable because the most solid fraction of the separation can be removed by composting companies, which mix it with manure from other animal species, or add wood chips to structure it, offering standardized organic fertilizer to the market. Therefore, dehydration of this component is not very useful, and the liquid fraction continues to have the same volume, assuming the same transport and field application problem.

In this line INNOVACC has set up slurry driers with dynamic or natural ventilation, using the energy captured by the greenhouse itself through its walls and ceilings, and the thermal energy of the air that enters it, which greatly reduces their functional period, and therefore their performance, in order to solve the amount of liquid slurry generated.

The SOLARPUR company has set up slurry dryers optimizing ventilation, avoiding ammonia emissions by acidifying the slurry and a final air filtering system. Using a software that optimizes the ventilation ratios according to the incident radiation in the greenhouse, it has managed to double the evaporation rate that is achieved in natural solar evaporation, but even with this achievement, its objective is not to obtain total dehydration of the slurry, but, by eliminating part of the water, a concentration prior to its transport and application to the field.

Greenhouse drying system references:

1. SOGARI, N et al (2000). "Use of solar energy and biogas in the dehydration of horticultural products" In Scientific and Technological Communications ". National University of the Northeast (Argentina)

2. GONZÁLEZ ZÚNIGA, CE (2016). "Evolution of the performance of a dryer operated with solar energy and biogas for moisture removal in coffee beans ”Escuela Agrícola Panamericana Zamorano (Honduras). Graduation project. Environmental and Development Engineering 3. AMEER BMA et al (2010). "Design and performance evaluation of a new hybrid solar dryer for banana" In Energy Conversion and Management 51; pp: 813-820

4. MONTERO, I et al (2010). "Design, construction and performance testing of a solar dryer for agroindustrial by-products" In Energy Conversion and Management 51; pp: 1510-1521

5. EKECHUKWU OV et al (1999). “Review of solar-energy drying systems: an overview of drying principles and theory” In Energy Conversion and Management 40 (6); pp: 615-655

6. GONZÁLEZ HALCÓN, C (2018). "Viability study of annual production of salt marsh in marsh with renewable energies" Higher Technical School of Engineering (ICAI). Electromechanical Engineering Degree. Madrid

7. FERNÁNDEZ-LÓPEZ et al (2007). “Integrated system of desalination by renewable energies without emission of brine”. Conference paper. Ibero-American Congress of Mechanical Engineering

8. INNOVACC.https: //www.lavanguardia.com/local/girona/20140630/54411 429714 / olot-test-pilot-dry-manure-energy-solar.html

9. EMA DEPURACIÓN S.L https://www.innovacc.cat/2016/11/11/visita-aun-invernadero-de-secado-solar-de-purines/?lang=es

10. SOLARPUR. https://ecoinventos.com/solarpur/

EXPLANATION OF THE INVENTION

The inventors of the present application have developed a high-performance slurry drying plant in which, from elements already known, such as the use of solar energy captured through a greenhouse-type structure, the previous acidification with sulfuric acid For the control of ammonia emissions, and the final filtration of the air, a radiant floor is incorporated to increase the capture of energy from the medium and its transfer to the slurry mass.

Drying occurs as a result of the heat balance. The thermal needs are the result of adding the enthalpy of the water so that evaporation takes place, the energy necessary to raise the initial temperature of the slurry to the set temperature, and the energy necessary to heat the temperature of the air entering the greenhouse to transport the water vapor that is produced during the dehydration process.

The main novelty of the installation, for which registration as a utility model is requested, is the incorporation of underfloor heating and the use of water tanks for storing energy that could not be transferred during the day, using it at night, or on days when there is less energy input.

The fresh, non-homogenized slurry reaches a closed tank with a propeller mixer, where sulfuric acid is incorporated for acidification, and is controlled with a continuous pH meter.

Once it has been homogenized and acidified to pH 5.5-6, it is driven by a pump to the slurry greenhouse, spreading over the radiant floor surface until it forms a 3-6 cm thick layer.

The energy that we will have will be the radiation that affects the greenhouse roof, the energy from the air that we incorporate into the greenhouse, and the energy that we transfer to the slurry mass through the radiant floor.

Underfloor heating is essentially composed of several serpentine ducts that carry water. The water is driven by pump motors, whose power and number will depend on the linear meters of coil through which it must circulate. The technology for this system is widely developed in residential heating systems.

The circulating water has one or more regulation tanks that allow the storage of excess energy in the form of hot water.

The water from the underfloor heating is part of a tight closed circuit that will incorporate and transfer energy by heat exchange.

Energy capture can be in different ways:

- Thermosolar field: the solar thermal collectors can be flat or with vacuum tubes. A number of panels optimized for the volume of slurry to be dehydrated is installed in a conditioned space near the greenhouse, facing South. Solar thermal technology is widely used and proven. The water in the circuit receives the thermal energy by heat exchange, as it passes through the collectors, it is collected in the regulation tanks and pumped into the greenhouse, where it will transfer the energy to the slurry mass.

- Photovoltaic field: the photovoltaic panels will be installed optimizing their number and power to the volume of slurry to be dehydrated in a conditioned space near the greenhouse, facing South. The direct current from the photovoltaic panels is transformed into alternating current with an inverter. The water in the circuit receives the thermal energy by heat exchange with the electrical resistances placed inside the regulation tanks. In the case of photovoltaic energy, energy can also be stored with lead-acid or lithium batteries (depending on the technology currently available).

- Biomass: the biomass boiler is fed with different fuels with a neutral CO ² balance: wood pellets, olive pits, nut shells, peach pits etc. The water in the circuit acquires thermal energy as it passes through the boiler and is stored in the regulation tanks, from where it is driven into the greenhouse, where it will transfer the energy to the slurry mass.

- Natural gas, propane or LPG boilers: The water in the circuit acquires thermal energy as it passes through the boiler and is stored in the regulation tanks, from where it is driven into the greenhouse, where it will transfer the energy to the slurry mass .

- Other energy sources: water vapor from industrial processes, thermal energy from industrial process fluids. Any system that allows an energy exchange with our closed water circuit.

The design of the plant is especially oriented to slurry with a high water content. In tests carried out by the inventors in 2017 with a small 2 m2 pilot plant, this type of slurry, as it contains between 3.5 and 16% dry matter, does not generate the "crust" effect when the thickness of the sheet it does not exceed 6 cm, becoming dehydrated to humidity values of 20%.

When it reaches this humidity value, the slurry becomes a manipulable product that can be stacked in a roofed space attached to the greenhouse and can be subsequently removed by composting companies. Dehydration to these levels also allows no additional ammonia emissions to occur.

The slurry, once dehydrated, can be removed from the greenhouse manually or with agricultural machinery and a rubber drag attachment until it is evacuated from one end of the greenhouse.

Automated collection systems can also be implemented by means of a bridge crane that runs along the sides of the greenhouse with a rubber accessory and brooms that introduce it into a channel inside which a worm screw is activated, transporting the dehydrated to a covered outdoor space where it can be stacked.

Drying requires a controlled supply of air. The air acts as a transport element for the water vapor that is generated, entering with a relative humidity, determined by the inlet temperature and by the environmental humidity load of the geographical area where the greenhouse is located. Inside the greenhouse, the air will raise its temperature to the set temperature, increasing its ability to saturate with humidity.

The air supply is controlled by two low consumption forced ventilation systems synchronized with each other, one for the intake and the other for the extraction. The operating regime of both systems is controlled by software that collects outdoor temperature and relative humidity data.

The moisture-laden air outside the greenhouse passes through a filter made of biological material. This filter consists of a cylindrical or polyhedral tank with a grid below which the humid air from the greenhouse is evacuated. On top of the grid, porous material of biological origin accumulates: pine bark, coarse chipboard, wood chips, etc. This biological material is sprayed with a dilution of sulfuric acid and water, in such a way that it acts as an acid trap for the ammonia residue in the air flow. Once saturated, this material can be ground and added to the dehydrated slurry as a structuring agent.

After the biological filter, the hot steam passes through a heat exchanger which, in the case of farms, can circulate water from the heating system. We will take advantage of this heat to preheat the heating water for maternity wards, suckers, water for rehydrated milk for suckling pigs in the case of bovine cattle or other uses. The water vapor extracted from the greenhouse will partially condense, and will be collected in a basin from where it will be reused as cleaning water for the facilities.

BRIEF DESCRIPTION OF THE DRAWINGS

To complement the description that is being made and in order to help a better understanding of the characteristics of the invention, the present specification is accompanied, as an integral part thereof, by a set of drawings in which for illustrative purposes and non-limiting, the following has been represented:

Figure number 1.- Shows a schematic sectional view of the underfloor heating structure and the arrangement of the different structural elements of the entrance and perimeter of the slurry drying area.

Figure number 2-A.- Shows a schematic representation of the different radiant floor circuits, the number of which will depend on the size of the greenhouse, and of two lines of solar thermal collector panels with their conduits to the buffer tank, as an example of the energy system, also appreciating, along the route, the expansion vessels and the impulsion pumps, both for the flow and return circuits, and the collector box in which the hot water from the tank is distributed. inertia to the different circuits of the thermal floor. An enlargement is shown in Figure 2-B of detail A indicated in figure 2-A that shows the main elements of the installation shed.

And figure number 3.- Shows a representation of the unit showing the distribution of the slurry homogenization tanks and the sulfuric acid storage tank, as well as the natural filter, connected to the greenhouse air extraction tube .

PREFERRED EMBODIMENT OF THE INVENTION

Next, I will define, according to the numbering adopted in the figures, each of the parts of the unit object of the invention, which is applicable to a plant for the treatment of liquid slurry from pigs, dairy cattle and others. animal species by drying, consisting of a greenhouse (24), a regulated ventilation system (12), a homogenization tank (14) and acidification of the slurry and a natural filter moistened with an acid solution (13):

Underfloor heating (100) for the treatment of slurry (figure 1) comprising:

Base formed by a casing of bowling pins (1) between 15 and 20 cm in

thickness.

Geotextile sheet (2) to protect against possible leaks or seepage

of slurry.

Concrete base (3) "poor" for leveling the treatment room.

Expanded polystyrene plate (4) of 2.00 x 1.00 x 0.10 meters, for

thermal insulation that prevents the diffusion of heat downwards. Of the same

In this way, the perimeter of the space intended for the

slurry treatment.

Placement of mesh (5) # 20 cm, of 10 mm rod, raised 5 cm above

the insulation base.

Installation of pipe (6) Evhofelex 5 layers with oxygen barrier

for the formation of underfloor heating circuits. It will be subject to

the mesh (5) for its fixation.

- 15 cm layer of concrete type HAF-30 / F / 20 / lia + Qc with SR (sulfo-resistant) cement poured with a pump and vibrated, to be reinforced with the previous mesh.

- Perimeter concrete wall (8), in the closing formation of the space for slurry treatment, 30 cm thick, reinforced with double mesh type HAF-30 / F / 20 / lia + Qc with poured SR (sulfo-resistant) cement with pump and vibrated.

- Helicopter trowel the concrete slab.

- Completion of the base of the treatment slab with a protective layer of Expoxi (7) bicomponent resin, such as Basf, Sika, or similar.

- Greenhouse (24):

- Greenhouse (24) tunnel type, without straight walls, the structure being totally curved from the fixing point on the ground to the ridge. The shape of the arches is curved.

- It is made up of modules, with a series of arches made of hot galvanized cylindrical tubes protected with a layer of zinc to prevent corrosion. The tubes will be inserted into concrete footings that will form part of the radiant floor structure. Its shape allows it to accommodate a greater volume of air and provides resistance to rain - This type of greenhouse has a greater sealing capacity than the flat greenhouse, and facilitates operations with agricultural machinery

- Energy capture, for example thermosolar (figures 2 and 3):

- Thermal panels (22) of 24 vacuum tubes per unit with heatsinks (23)

- Panel support structure at 45 ° inclination

- 5-layer tubing with oxygen barrier

- Collector (20) for various circuits (6)

- Buffer tank (17)

- Impulse pumps (18, 19) for each of the flow and return circuits

- Solar expansion vessel (16)

- Heat transfer fluid

- Insulated tube from the thermal panels (22) to the buffer tank (17)

- Insulated tube from the buffer tank (17) to the circuits (6) of the greenhouse radiant floor (24)

- Battery kit for heat sinks

- Distribution panel

- Control unit

- In facilities booth (15)

- Deposits:

- Slurry accumulation tank (14), with inlet, outlet, connection with sulfuric acid tank (13), register for cleaning and discharge, and mixer for homogenizing the slurry and sulfuric acid.

- Tank for sulfuric acid (13)

- Sulfuric acid dilution tank for spraying the natural filter (12)

- Tank for the formation of a natural filter (25), with a stainless steel grill at the bottom and a watering system with sprinkler nozzles at the top. It is connected (26) with the greenhouse air extractor (27) (24) and with the heat exchanger.

- Air extraction system:

- Air inlet fans to the greenhouse at the end opposite the extraction system. They are low consumption fans synchronized with the extraction fans, in such a way that the inlet and outlet flow is controlled and quantified.

- Impulse fans inside the greenhouse. They are low consumption fans that help to drive the air inside the greenhouse, avoiding the formation of turbulence.

- Extraction fans. They are low consumption fans, synchronized with the inlet fans, that extract the air from the greenhouse and drive it through a flexible corrugated polyethylene duct to the natural filter

- Fan synchronization and regulation unit

- Water / air heat exchanger

- Control elements

- Equipment for continuous pH measurement in the homogenization tank and in the dilution tank for spraying the natural filter

- Outdoor weather station that measures: temperature, relative humidity, atmospheric pressure, wind speed and direction

- Indoor thermometers that measure: temperature of the slurry mass and air temperature in the greenhouse

- Continuous ammonia measurement probe, with datalogger, in the air collection duct after the natural filter

Furthermore, the drying unit has one or more regulating tanks in the radiant circuit (100) that act as storage units for the excess thermal energy not transferred to the slurry mass. And, in addition, a heat recovery unit behind the natural filter to heat the water in a heating circuit of the farm attached to the installation and to condense part of the evaporated water to be reused as cleaning water.

The preferred model of execution will be an installation with solar thermal capture.

An example would be a pig farm located in Lleida that wants to be able to treat 1000 cubic meters per year of slurry, which would be the equivalent of half of the slurry production of a 1000-place fattening farm.

Each geographical area has its characteristics. To know the contribution of radiation available we will use the PV-GIS (Photovoltaic Geographical Informatic System) software, which provides open data on solar radiation and temperature.

For the heat balance calculations we will take into account the contributions of solar radiation per m2 of greenhouse roof surface, the temperature and relative humidity of the inlet air and the efficiency of the vacuum tube collectors; On the energy consumption side, we will take into account the enthalpy of the water, the energy required for the temperature jump of the slurry mass from the inlet temperature to the set point temperature, the energy losses along the thermal circuit and the inlet air temperature when it is below the setpoint temperature.

The drying surface of the greenhouse must be sufficient to effect a total drying of a 3-6 cm thick sheet every 48 hours in winter. In this case, the greenhouse area will be 100 m2, with a roof area of 155.5 m2.

The solar thermal capture will be 222 m2 of vacuum tubes, equivalent to 74 panels of 3 m2.

There will be five circuits that will be fed from several regulation tanks that will accumulate 3000 liters of water (the equivalent of a greenhouse filling).

The installation will operate continuously: filling the homogenization tank; shake with the sulfuric acid that will be incorporated until the pH drops to 5.5 - 6; pumping to the surface of the greenhouse; adaptation of the ventilation flow to the external environmental conditions; pass through the natural filter; passage through the heat exchanger; collection of condensation water in an adjacent basin or tank.

During the night, the installation will continue to operate, taking advantage of the thermal energy accumulated in the regulation tanks.

After the drying period, which will vary depending on the month of the year, the dehydrated fraction will be collected (22.5 kg for each drying in this example), and it will be refilled with a new supply of fresh acidified slurry.

The whole process will be controlled by:

- Continuous pH meter

- Ventilation regulators according to outside temperature and relative humidity - Ammonia probes at the outlet of the natural filter

- Indoor temperature and relative humidity datalogger thermometers.

Optionally, the invention contemplates other alternative forms of embodiment where the external energy capture point of the described slurry drying unit of the plant consists of: a field of photovoltaic panels; in one or more biomass boilers; in one or more natural gas, propane or liquefied petroleum gas boilers; or in one or more heat pumps connected to a geothermal circuit that extracts energy from the air, water currents or the earth.

Claims (2)

1.- PURINES DRYING UNIT, for a plant for the treatment of liquid slurry from pigs, dairy cattle and other animal species by drying formed by a greenhouse (24), a regulated ventilation system, a homogenization tank (14) and acidification of the slurry and a natural filter (12) moistened with an acid solution, characterized in that the greenhouse (24) has a radiant floor (100) with a tube (6) of cross-linked polyethylene, multilayer polyethylene or polybutylene, isolated from the ground with polystyrene expanded (4) or other low conductivity materials, covered with mortar or concrete (3); for having an external energy capture point; by having one or more regulation tanks in the radiant circuit that act as storage units for the excess thermal energy not transferred to the slurry mass; and by having a heat recovery unit behind the natural filter (12) to heat the water in a heating circuit and to condense part of the evaporated water to be reused as cleaning water. 2.- PURINE DRYING UNIT, according to claim 1, characterized in that the external energy capture point consists of a field of thermosolar plates (22). 3 - PURINE DRYING UNIT, according to claim 1, characterized in that the external energy capture point consists of a field of photovoltaic panels. 4 - PURINE DRYING UNIT, according to claim 1, characterized in that the external energy capture point consists of one or more biomass boilers. 5 - PURINE DRYING UNIT, according to claim 1, characterized in that the external energy capture point consists of one or more natural gas, propane or liquefied petroleum gas boilers. 6 - PURINES DRYING UNIT, according to claim 1, characterized in that the external energy capture point consists of one or several heat pumps connected to a geothermal circuit that extracts energy from the air, water currents or the earth.