Classifications

• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F1/00—Treatment of water, waste water, or sewage
  • C02F1/66—Treatment of water, waste water, or sewage by neutralisation; pH adjustment
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
  • C02F2103/02—Non-contaminated water, e.g. for industrial water supply
  • C02F2103/023—Water in cooling circuits
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
  • C02F2103/08—Seawater, e.g. for desalination
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F2303/00—Specific treatment goals
  • C02F2303/20—Prevention of biofouling

Definitions

• the invention relates to methods and means of reducing and/or preventing fouling on a surface of a component that is in contact with water.
• Thermoelectric power plants boil water to create steam, which then spins turbines to generate electricity.
• the heat used to produce steam can come from burning of a fuel, from nuclear reactions, or directly from the sun or geothermal heat sources underground. Once steam has passed through a turbine, it must be cooled before it can be reused to produce more electricity.
• This cooling of the primary water circuit is generally achieved by a separate cooling water system that consists of a condenser, a cooling tower, and a cooling water pump.
• the cooling water is either extracted from a nearby water source and discharged back into this source, or cooled down and recirculated for reuse as cooling water after cooling of the primary water circuit.
• a first cooling system is also termed a once-through system. Such system takes water from a nearby source (e.g., river, lake, or ocean), circulates it through pipes to absorb heat from the steam in systems called condensers, and discharges the now warmer water to the local source. Once-through systems were initially the most popular because of their simplicity, low cost, and the possibility of situating power plants in places with abundant supplies of cooling water.
• a second cooling system is a closed-loop system, also termed a wet-recirculating system. Such system reuses cooling water in a second cycle rather than
• the invention provides a method of reducing and/or preventing fouhng on a surface of a component that is in contact with water, the method comprising: transferring carbon dioxide to the water to bring the water at a pH of at most 7.5, whereby the water is not pressurized.
• Said water preferably is fresh water, for example fresh cooling water that is used in a power plant.
• fresh water includes surface water such as sea water, brackish water, river water, lake water, and ground water. Said water preferably is salt water, preferably seawater.
• Fouling is the accumulation of unwanted material on solid surfaces to the detriment of function. Fouling is distinguished from other surface-growth phenomena in that it occurs on a surface of a component, system or plant performing a defined and useful function, and that the fouling process impedes or interferes with this function.
• the fouling material can consist of either living organisms (biofouling) or non-living substances including, for example, scaling. Biofouling is the accumulation of micro-organisms (e.g. algae and diatoms), plants, and animals on surfaces. Bacteria can form biofilms or slime layers. The organisms aggregate on surfaces using colloidal hydrogels of water and extracellular polymeric substances such as polysaccharides, lipids, and nucleic acids.
• Scaling or precipitation fouling, is the undesirable accumulation of solid salts, oxides and hydroxides from water. These include, for example, calcium carbonate and calcium sulfate. Scale deposits are formed by precipitation and crystal growth at a surface in contact with water. The most common scale-forming salts that deposit on heat transfer surfaces are those that exhibit retrograde solubility with temperature. Although they may be completely soluble in the lower- temperature bulk water, these compounds (e.g., calcium carbonate, calcium phosphate, and magnesium silicate) supersaturate in the higher-temperature water adjacent to the heat transfer surface and precipitate on the surface.
• these compounds e.g., calcium carbonate, calcium phosphate, and magnesium silicate
• Delta P is calculated as:
• Delta P pN 2 + pO 2 + pH 2 O + pCO 2 - pAtm, whereby pN 2 includes argon and other trace atmospheric gasses.
• Carbon dioxide is a natural gas essential for life. Within the limits that are sufficient to reduce fouling, the elevated concentrations of carbon dioxide and consequently reduced pH levels will not result in acute killing of aquatic species, but will rather reduce propagation and reproduction.
• Said carbon dioxide is preferably transferred at an intake point of the water.
• Said water preferably is fresh water, including surface water such as sea water, river water and lake water, and ground water.
• Said fresh water preferably is salt water, preferably seawater.
• the pH of the water is preferably reduced to a pH of between 6.0 and 7.5, such as to a pH of 6.0, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, 6.95, 7.0, 7.1, 7.2, 7.3 7.4 or 7.5.
• the pH is preferably not below 6, more preferably not below 6.5 in order not to cause damage to the water system such as corrosion of metal components.
• the pH of the water is therefore preferably between 6.5 and 7.5, such as 6.5, 6.6, 6.7, 6.8, 6.9, 6.95, 7.0, 7.1, 7.2, 7.3 7.4 or 7.5.
• Sea water has, on average, a pH of about 8.5.
• a pH of about 8.5 To reduce the pH of sea water to a level of about 7.5, about 10 mgram of C02 is required per liter of water.
• a level of about 6.0 To reduce the pH of sea water to a level of about 6.0, about 150 mgram of C02 is required per liter of water.
• the amount of C02 that is required per liter of water to adjust the pH of the water to a value of between 6.0 and 7.5 is between 10 and 150 mgram.
• This amount of C02 can be transferred to water using methods and means that are known in the art.
• a pH of at most 7.5 will increase carbonate solubility and in this way effectively prevent shell fish such as cockles, mussels, and oysters, and other mollusc larvae from forming the shells necessary to settle and survive in the water system.
• shell fish such as cockles, mussels, and oysters, and other mollusc larvae
• the increased carbonate solubility of the water results in decreased scaling, while the increased carbon dioxide concentration results in deterrence of fish.
• the carbon dioxide that is transferred to the water to bring the water at a pH of at most 7.5 is produced by the industrial plant that is cooled with the water.
• An average power plant for example a NUON multifuel power plant in the Netherlands, produces about 571429 kg of CO2 per hour.
• the carbon dioxide is optionally treated, for example filtered, prior to
• the carbon dioxide that is included in the exhaust gas from a plant may contain toxic substances such as fine particulate matter and metals, for example lead and arsenic. Methods, for example filtration technologies, that are used to remove these toxic substances are known in the art and include scrubbers, such as wet and dry scrubbers.
• the invention further provides a cooling system comprising means for transferring carbon dioxide to the cooling water to bring the cooling water at a pH of at most 7.5, wherein the cooling water is not pressurized.
• Said cooling system is preferably for cooling of an industrial plant, for example a power plant, or other industrial plant such as, for example, a chemical plant including a petroleum refinery and a blast furnace.
• Said means for transferring carbon dioxide to the water, preferably cooling water include means for transferring exhaust gas from a plant, preferably filtered exhaust gas, through the water, for example by an exhaust gas discharging chamber for discharging gas in the form of gas bubbles into said water.
• Said exhaust gas discharging chamber preferably comprises a porous membrane whereby gas absorption rate is enhanced by a bubble dispersion mechanism.
• the cooling water may be recycled through a recirculating system or used in a single pass once-through cooling system.
• a preferred cooling system according to the invention is a once-through cooling system. The main advantages of a once-through system is that it is a simple type of system and very flexible.
• a preferred cooling system is a recirculating system.
• Recirculating systems may be open if they rely upon cooling towers or cooling ponds to remove heat. If heat removal is accomplished with negligible evaporative loss of cooling water, the recirculating system may be closed.
• a preferred cooling system for example for an energy plant is an open recirculating cooling system. Open recirculating cooling systems save a
• the cooling water is cooled prior to discharging the cooling water back into its source, or prior to its reuse as cooling water. Cooling of the used cooling water is accomplished, for example by a cooling tower.
• a cooling tower is designed to provide intimate air/water contact. Heat rejection is primarily by evaporation of part of the cooling water. Some sensible heat loss (direct cooling of the water by the air) also occurs, but it is only a minor portion of the total heat rejection.
• Said cooling tower preferably is a natural or mechanical draft tower and the direction of airflow, relative to the water flow is either counterflow or crossflow.
• a cooling tower may further aid in reducing the amount of carbon dioxide in the cooling water, prior to discharging the cooling water, for example back into its source.
• the invention further provides an industrial plant, for instance a power plant, and/or a chemical plant including a petroleum refinery and a blast furnace, comprising a cooling system according to the invention.
• Said plant comprises means for transferring carbon dioxide to the cooling water to bring the cooling water at a pH of at most 7.5, preferably at a pH between 6.5 and 7.5, wherein the cooling water is not pressurized.
• Figure 2 Number of juvenile bivalves (Cerastoderma edule) in sediment samples at the end of the study 69 days after the start of the CO2 application.
• FIG. 3 Biomass (measured as chlorophyll-a fluorescence, by means of a Biotek microtiter plate reader with Gen5 software) of algae settled on substrates at the end of the study 69 days after the start of the CO2 application.
• Series A and B depict substrates at two different positions in the experimental ecosystem.
• Bivalve molluscs and algae are important groups of fouling organisms.
• Figure 2 depicts the impact of increased CO2 levels on reproduction of mollusks.
• the cockle Cerastoderma edule was included in the experimental ecosystems. Although it was clear that shells became less robust at higher CO2 levels, the adults survived all treatments. Reproductive success, however, was strongly affected. At 2.6 m-atm CO2 and higher, reproduction was almost completely inhibited (Figure 2). The poor condition of the adult shells indicates erosion of the shell carbonates. The adults can withstand this situation as long as the shell maintains its protective function.

Applications Claiming Priority (2)

Publications (1)

Family

ID=48747694

Family Applications (1)

Country Status (3)

Citations (1)

Family Cites Families (9)

• 2013
  • 2013-05-29 NL NL2010885A patent/NL2010885C2/en not_active IP Right Cessation
• 2014
  • 2014-05-28 WO PCT/NL2014/050341 patent/WO2014193230A1/en active Application Filing
  • 2014-05-28 EP EP14729987.9A patent/EP3003990A1/de not_active Withdrawn

Patent Citations (1)

Non-Patent Citations (2)

Also Published As

Similar Documents

Legal Events