GB2491085A - Transportable system for generating and injecting oxygen in situ for fish cages in the sea - Google Patents

Abstract

The invention relates to a transportable system for generating oxygen in situ and injecting industrial levels of oxygen for fish cages in the sea, said system comprising a floating pontoon-like platform having a floatability of at least 50 tons and able to be towed in the open sea, in which said system generating 93-95% purity oxygen is contained. Said transportable system also comprises a system that generates and distributes electricity, providing electrical energy to the components of the oxygen-generating system which, in turn, essentially comprises means for generating pressurised air, means for generating pressurised oxygen, means for compressing and accumulating high-pressure oxygen, and means for controlling the oxygen-generating system.

Description

V

PORTABLE ONSITE OXYGEN GENERATION AND INJECTION

SYSTEM FORFISHCAGESIN THESEA

APPLICATION OF THE INVENTION

The present invention aims to improve production yields in the cycle of fish, more specifically to a portable oxygen generation and injection system of industrial levels for fish cages in the sea, principally aimed at the aquaculture industry, storage facilities, among others.

DESCRIPTION OF PRIOR ART

Oxygen from seawater is derived mostly from air, which is why it is accompanied mostly by the gases that form part of said mixture. Because oxygen is more soluble in water than nitrogen, it is found in greater proportion than in air. The is volume of oxygen in seawater is approximately 25 to 30 times lower than the volume of the same element in the air.

The oxygen is dissolved in water by simple absorption, which is accentuated by the waves which remove the water and bring new layers in contact with the air, which favors the diffusion process. Therefore, the oxygenation of the water is directly related to the rough seas. The richness of oxygen is related to salinity, the greater the salinity, the lesser the amount of oxygen.

Another factor that influences the oxygen absorption by the water is temperature. For this reason in the open seas, the wealth of oxygen decreases from the poles to the Equator.

Oxygen is the key to life, required by fish and plants for carrying out vital processes such as oxidation of proteins, barbohydrates and fats. This allows the decay of these substances to generate a consistent release of energy used for vital functions of beings. If the oxygen level is not sufficient for the ecosystem, plants will divide fructose and glucose into carbon dioxide and alcohol, i.e.,in a short time, their cells will die.

Whenever the ecosystem demands more oxygen than the surface exchange can provide, oxygen is needed to be supplied via external means or artificial means.

Oxygen, food and water are three key parameters in fish farming. In particular, the availability of Oz in water has a direct effect on crop yields. The trend towards high fish densities result in adequate concentrations of 02 dissolved in water necessary for the development of fish. The main objective of the 02 injection is to increase the level of dissolved oxygen in fish rearing tanks. Its concentration will determine the production yield in most cases.

The greatest benefits are reflected in the increase in the feed conversion ratio, providing a more efficient use of food, improving fish growth and providing greater resistance to pathogens, reducing stress and mortality and optimizing the use of the facilities, reaching higher densities.

All the above, forces to have oxygen generating systems capable of injecting said gas into the seawater to optimize the breeding of fish, like salmon, for example.

It is known that during the production cycle of the fish there is high mortality associated with low oxygen, especially during the summer due to different factors such as algal blooms, anoxic currents, biomass of the cage, etc.. Many of these problems are undetectable because the lows occur overnight.

Currently a low in OD (OD: oxygen demand in English), is shown as specific events, as they don't use constant monitoring and online systems for OD in the culture cages and these specific events are solved by moving cylinders or thermos containers of oxygen that, from a logistical point of view, is not very operational when the centers are located far away, besides the amount of 02 to be transferred is not an industrial quantity that can solve large scale problems.

An alternative solution can be found in patent documents FR 2735463 from the holder SPIE CITRA ILE DE FRANCE, with the title "Independent or semi-independent water oxygenation system", which describes a pontoon with air compressors that feed micro ceramic diffusers which are suspended in the water by cables. However, this document is a system to produce air that is injected into the water. Here, there is clearly a substantial difference, as when injecting air having 20% oxygen and not an oxygen flow at 93%, besides, it only has air containers and not an oxygen generation system as in the case of the present invention, which provides a system of generation and injection of oxygen which is mounted on a pontoon comprising a shed, which contains diesel storage means, means for compressing air, means for drying the air, filtering means, means for generating electricity, means for generating oxygen, means to accumulate high pressure designed to contain oxygen and special high pressure compressor means for air, which operate in a synchronized manner via an internal control system that enables decision-making regarding how much to produce, storage and oxygen injection.

The patent document US 4,906,359, of the holder COX JR BERTHOLD V, bearing the title "Solar activated water aeration station" describes a water aeration station to inject air at a given depth. This station includes a floating plafform and solar panels, which are there to power up a motor and a pump; it also has means to provide a proper slope to maximize solar energy. However, the solar panel systems h,ave a natural limitation that prevents them from scaling the design on an industrial scale. A conservative estimate would suggest that the requirement for solar panels for a system like the present invention would be approximately 2,000 m2 of panels with hundreds of batteries. The batteries are not considered in both cases and only feed during daylight hours. In addition, this system, as the one above, is only to produce air that is injected into the water.

Patent JP 56073528, of the holder MIYAKE TAKAMURA, bearing the title "Oxygen supply device Used in fish farm or the like", which describes an oxygen injection system through cylindrical diffusers comprising a plurality of narrow holes.

However, oxygen is connected to an air compressor and there is no description of an oxygen generation system mounted on a pontoon.

The Oxygenation and oxygen injection system of the present invention differs from what exists in the market due to its ability to generate OD on site; it also possesses the property of injecting continuously without major logistical problems in industrial quantities.

BRIEF DESCRIPTION OF THE FiGURES

Figure 1 shows a block diagram of the system of the present invention.

Figure 2 shows a plan view of the system of the present invention with all the equipment that make up the system and a distribution mode. -3.-

Figure 3 shows a schematic layout of the present invention with respect to the connection distribution of fish cages in the sea.

DETAILED DESCRIPTION OF THE INVENTION

s The system (100) of on-site oxygen generation and injection, is arranged on a floating plattorm, called pontoon, with side walls and a roof, to house the system inside (100) the present invention. This pontoon has a buoyancy of at least 50 tons and is capable of being towed at sea.

The system (100) of generation and injection of oxygen which generates oxygen at 93 to 95% purity, comprising a generator system and a power distribution system, which provides electric power to the components of this oxygen generating system, where the latter basically comprises pressurized air generating means, pressurized oxygen generating means, high pressure oxygen accumulation and compression means and control means of the oxygen generation system.

is The generator and electricity distributor comprises fuel accumulator means, preferably diesel, from storage tanks (302) located inside the pontoon which allows the operation of the oxygen generation and injection system (100) for extended periods of time. This storage tank (302) considers at least 15,000 liters capacity, a level meter and a pump (s) to deliver the diesel to the generators.

The electricity distribution system considers a power panel (201) and switchboard (202) to distribute the energy produced by the generation system to the oxygen production line; while the electronic system contains protections and distribution system for the handling and power up of all the control electronics. it also includes a battery bank (203) and UPS (204) capable of maintaining electrophonic control systems running. for 24 hours and with an optimal and regulated level of voltage and frequency.

The generating means of pressurized air, essentially comprise compressor means (102), which in a preferred embodiment is a reciprocating compressor which generates an air flow at a pressure of about 620.5 to 792.9 KPa (90 -115 psi) drying means (103), which by cooling remove the water that may come in the compressed air; filtering media (104), which in a preferred embodiment, comprises 2 filters and a centrifuge trap that removes suspended particles, the oil drops that can be dragged from the compressor and finally the water droplets that leave the compressor as a complement of the drying action, and accumulator means (105) of air serving to act as a cushion for the pressure fluctuations that occur, since the oxygen generation process has an air consumption which is not stable over time.

The oxygen generating means essentially comprise a pressure system called "Generator by Pressure Swing Adsorption" (106) and an accumulator of low pressure oxygen (107). The system "Generator by Pressure Swing Adsorption" (106), takes pressurized air and passes it to a molecular sieve bed containing an specific adsorbent for nitrogen, which is why at the outlet of said bed there is an enriched io oxygen flow at 93 -95%. When the first bed is saturated, its air passage is closed and the second bed begins to fill up with a process identical to the first. The first bed then begins to throw the nitrogen adsorbed on the substrate out to the atmosphere.

This process is controlled by a computer's internal PLC. While, at the output of the generation of oxygen, there is a tank (or tanks) of oxygen at low pressure, in order to is buffer the pressure of the process output and thus guarantee the purity of the process. These tanks operate in a range of about 344.7 to 413.7 KPa (50 -60 psi).

The compression means and accumulation of high pressure oxygen essentially comprise an oxygen piston compressor (108) and a high pressure oxygen accumulator (109). The oxygen piston compressor (108) uses no oil in its compression; one part of the oxygen produced is compressed to store it in the high-pressure accumulator (109). The high-pressure oxygen accumulator (109) stores large amounts of oxygen in gaseous form which avoids losses by evaporation.

The control means of the oxygen generation system comprises an equipment manual board (205), a PLC (206), means for receiving dissolved oxygen signals (207), a computer (208) with HMI software (209) and control algorithms (210) and a manual valve board (21 1).

The equipment manual board (205) can individually start each of the pieces of equipment in the system via a start pushbutton. It also considers visual indicators for power, emergency buttons and indicators of electrical phases.

The PLC (206) stores the control algorithms and automatically operates constantly making decisions based on the measurements of dissolved oxygen sensors and states of the equipment to determine whether to turn the equipment on or off, valve, etc.. The reception of the dissolved oxygen signals are received wirelessly, which are measured by oxygenation sensors, which in a preferred embodiment are optical.

The computer (208) with HMI provides a user interface graphically showing all the relevant information on the status of equipment, such as on or off, open or closed valves, oxygen levels in water, oxygen flow etc. This can modify operating parameters that influence the decision of the control system or it can operate the system manually through the computer system. If the necessary connectivity is present (Internet), this interface can be operated remotely (no need to be in the pontoon) ensuring it can be operated and monitored from anywhere.

The software (209) and control algorithms (210) are stored in the PLC (206), developed exclusively for this application according to the needs and better practices established on site. These algorithms include (as an example): PlO control of dissolved oxygen levels in the cage; Routine intelligent battery charging; consider start times of equipment that optimize the useful life of said equipment, decision making in frequency time in line with the process to control and the equipment used; intelligent use of the accumulation system of oxygen such as use it as a buffer to optimize energy use, use it in case of mechanical emergency, use it in case of over consumption by the fish biomass.

Depending on the constant of the assigned PlO controller, the system considers the proportional error, the cumulative and the slope of the system to determine whether to oxygenate a cage or not (3) and for how long. The system (100) then adds the amount of oxyen that needs to be delivered to the cages (3) and determines whether to start one or more lines of generation, i.e., turn the zs solenoid valve on to oxygenate said cage (3) in particular. This decision is made for all cages (3). Then the system determines, according to how many valves are on and for how long, whether to oxygenate the cages from the accumulation (109) or if the consumption is lower and the tanks are full, whether to start one, two, three or all oxygen generation lines, turn the oxygen compressors on.

The valve manual board (211) allows controlling manually, the start or turn-off of the valves that supply oxygen to the fish.

Furthermore, the system comprises sensors such as mass flow meter for measuring delivered oxygen as wefl as control valves for delivery of oxygen to the fish cages. The oxygen injection system to the cages is done through pipes that carry oxygen to the fish cages and from there with microperforated hoses, which are s introduced into the water about 10 meters deep. Currently there are oxygenation systems on the market that use hoses or ceramic diffusers.

The oxygenation system (100) is designed so that it can operate autonomously Its main function is to always maintain oxygen levels provided or the Set Point (SP) in optimal levels, situation that, depending on the client, determines the minimum operating level in reference to the oxygen to be supplied. Likewise, the user of the system is the one that monitors the system.

For the on-site automatic generation of oxygen, the process basically starts with the measurements of the oxygen sensors, which are located at strategic points within the module. These sensors can be optical or galvanic technology that monitor is the level of dissolved oxygen in the water and transforms it into a signal 4 -20 mA which is delivered to the system of the present invention through a wired or wireless signal.

For example, if the levels of SP were scheduled at 7 ppm (parts per million), it means that any measurement greater than the oxygen sensor keep the system turned off as could be the case of 7.5 ppm (not necessary to inject oxygen in this case), otherwise, if the measurement of the oxygen sensor is lower than the specified in the SP, then the oxygenation system should turn on, an example case would be if the sensor measured 6.5 ppm.

The signals from the oxygen sensors are received by the PLC (206) of the oxygen system of the present invention and the latter checks that there is a value less than the SP to start turning on the equipment sequentially, starting with the ignition of the generator group (101), then the air blowers (103), then the ignition of the air compressors (102), afterwards the ignition of the oxygen generator (106) and finally, provided the capacity exists in accumulation tanks (109), the ignition of the high-pressure accumulator for oxygen (109), to fill or refill these accumulation tanks (109).

After switching on all the equipment, the oxygen produced can be sent to the accumulation tanks (109) or it can directly take a feed matrix to the cages. In the feed matrix (supplied by the accumulation tanks (109) and the on-site 02 production) there is a totalizer, in charge of recording the oxygen consumption being delivered to the cages (3). Each feeding matrix (4) is controlled by a solenoid valve, which when turned on, allows the passage of oxygen when the levels are low to the SP and the SP operates controfled by the PLC (206). This equipment is able to discriminate, based on sensor measurements to which cage (3), that forms a module, it feeds with oxygen independently from the cage module (2) to which it belongs.

Then oxygen that is then transported through the food matrix (4) is connected to the cage module (2) through a distribution box (5), which derives the oxygen to the cages (3) by means of distribution lines to finally deliver it through microperforated hoses.

Once the oxygen passes through the solenoid valve, it is directed to the cage (3) in question, by means of high pressure hoses, that make up the feeding matrix (4), upon arrival at the cage (3), the oxygen can be supplied to the water through various forms, among them oxygenation through ceramic diffusers or microperforated hoses. At this point the oxygen goes out through very small and uniform bubbles, thus ensuring a highly efficient oxygenation, this allows raising the levels in a case from 6.5 to 7 ppm and via sensor measurement, measurement is taken again so the PLC (206) makes the decision, thus the process begins again. The system stays on until the SP level is reached.

The system (100) of the present invention is designed so that it is always filling or refifling the oxygen high pressure accumulator tanks (109), so that the system when it detects the lack of oxygen in one or several cages, the first thing it does is to use the oxygen from the accumulator tanks (109) until it reaches a certain level (about 20% oxygen is used without the need to turn on equipment), or it uses the constant of the P1D controller when there is a difference in the type of errors or times, on the other hand, the oxygen is also used to resolve any eventuality with low oxygen levels, i.e. it can be used in parallel with the production of oxygen or it can be a reserve and used manually without the need to turn the equipment.

Additionally the system is designed so that it operates to feed the UPS (203) and thereby maintains the system power at a constant, i.e. it is designed to turn on only the generator in case the 00 levels are over the SP, so as to always keep enough energy to power equipment and components. It also has the feature to operate remotely. Furthermore, the system is designed so that every few hours it turns on to recharge the batteries of the UPS (203), the battery charge does not take s more than 2 hours and it allows energizing the system (100) for at least 17 hrs.

Claims (6)

1. CLAIMS1. Portable on-site oxygen generation and injection at industrial levels of oxygen in sea cages for fish, wherein comprising a floating platform, pontoon-type, with a s buoyancy of at least 50 tons and is capable of being towed at sea where in its interior it possesses this oxygen generating system at 93 to 95% purity, and comprises a generator and power distribution, which provides electric power to the components of this oxygen generating system, where the latter consists essentially of means for generating pressurized air, means for generating pressurized oxygen, compressing means and means for the accumulation of high pressure oxygen and system control means for oxygen generation.
2. 2. The mobile system of claim 1, wherein the generating system and electricity distributor comprises fuel accumulator means, preferably diesel, from storage tanks located inside the pontoon which allows the operation of the on-site oxygen generation and injection system for extended periods of time.
3. 3. The mobile system of claim 1, wherein the pressurized air generating means, essentially comprise compressing means, which in a preferred embodiment is a reciprocating compressor that generates an airflow at a pressure of about 620.5 to792.9 KPa (90 -115 psi); drying means, which by cooling remove the water that may come in the compressed air; filter media, which in a preferred embodiment, comprises 2 filters and a centrifuge trap to remove suspended particles, oil drops that can be dragged from the compressor and finally the water droplets that leave the compressor as a complement to the action of the dryer, and air accumulator means which serve to act as a cushion for pressure fluctuations that occur, since the oxygen generating process has an air consumption which is not stable over time.
4. 4. The mobile system of claim 1, wherein the oxygen generating means essentially comprise a pressure system called "Generator by Pressure Swing Adsorption", that takes pressurized air and passes it to a molecular sieve bed containing an -Ia-ausoroent specific for nitrogen, which is why at the output of said bed is an oxygen enriched stream at 93 to 95%, and an oxygen accumulator at low pressure.s
5. 5. The mobile system of claim 1, where the compression means and high pressure oxygen accumulation means essentially comprise an oxygen piston compressor and a high pressure oxygen accumulator that stores large amounts of oxygen in gaseous form which avoids losses due to evaporation.
6. 6. The portable system of claim 1, where the control means of the oxygen generation system comprises an equipment manual board, a PLC, reception means for dissolved oxygen signals, a computer with HM), a computer program to control algorithms and a valve manual board.