Blowdown Water Research Articles

Development of stacking type thermoelectric power generation unit for potential waste heat recovery applications

A 10 W class thermoelectric power generation unit is designed and prototyped. The power unit is designed based on a concept of a compact heat exchanger integrated with thermoelectric module. The power unit specifically targeted hot water waste heat of which temperature is below 100 °C. The preliminary lab testing of the unit showed maximum power output of 10.6 W under conditions of Th = 95 °C, Tc = 10 °C, the flow rate = 7 L/min. The size of unit is 5.4 × 11.2 × 14.4 cm and the calculated specific power of the unit is 12.1 W/L or 12 kW/m3 which is much higher than a value ever reported. We conducted long term stability tests in three different sites; 1) hot spring, 2) waste heat from inductive heating furnace and 3) boiler blowdown water in addition to one preliminary test at other hot spring site. All collected data in the demonstrations described above proved good stability of the performance of the power unit. On-site, self-powered remote sensing is also demonstrated at the hot spring site and successful data acquisition of temperatures and water flow rates at every seconds were confirmed.

Energy, Exergy analysis and optimization of solar thermal power plant with adding heat and water recovery system

Water scarcity and environmental impacts of the steam power plants blow down, is one of the growing concerns. During the evaporation of water in the steam cycle of the power plant, most of the impurities of water and vapor do not evaporate and remain in the boiler. By increasing the concentration of these impurities, boiler tubes are corroded. To adjust the concentration of these impurities, some of the water in the cycle is drained, which is called blowdown. Blowdown water has a high exergy content that is going to be wasted. In this study, by recovering a great amount of contained water and heat of power plant blow down, the entering wastewater to the environment is decreased and the total power of power plant is increased. This recovery system includes Evaporator and Vacuum pump. In this system a vacuum is created in the vaccum tank by vacuum pump which causes the water to evaporate and is injected into the steam cycle. The results show that by adding the recovery system, the amount of drained wastewater from the plant to the surrounding environment decreases from 3.118 kg/s to 1.799 kg/s. After Energy and Exergy analysis, it is shown that the output power increases by 0.53%, and the exergy returns from 20.73% to 20.84%. Also, the effect of the Evaporator vacuum on the output power and the amount of recovered water indicates that with the reduction of the Evaporator vaccum pressure, the amount of the output power is reduced, but instead due to further evaporation of the water, the amount of recovered water in the Evaporator will increase. After Energy and Exergy analysis, the results are optimized by the Genetic Algorithm. The inlet temperature of HPT1, inlet pressure of HPT1, outlet pressure from each turbine, and pinch point for the first heat exchanger are considered as decision variables. Optimization results show that by obtaining suitable decisions variable amounts, output power is increased from 34.01 MW to 34.92 MW. For evaluating the results on the power plant operation, SEGS VI power plant in the US (California) is used.

Removal of scale forming species from cooling tower blowdown water by electrocoagulation using different electrodes

This work investigates the effect of electrocoagulation (EC) using Al, Fe, and Zn electrodes for removing hardness ions and dissolved silica from cooling tower blowdown (CTB) water. The real samples were collected from urea fertilizer factory (Helwan Fertilizer Company), Cairo, Egypt. The effect of operational parameters, such as current density, electrolysis time, inter-electrode distance and stirring rate were studied and evaluated for the maximum efficiency. At the optimum operational conditions, Al-electrode removed the scale forming species from CTB water more efficiently than Zn and Fe electrodes. Al, Fe, and Zn electrodes removed 55.36% and 99.54%, 36.99% and 98.93% as well as 38.63% and 95.62% for the total hardness and silica ions, respectively. In order to rationalize the removal mechanism, the EC generated sludge was characterized by SEM-EDX, XRD, and FTIR. The present investigation inferred that Al-EC generates amorphous nature crystalline and other anode materials (Fe and Zn) forms definite crystalline particles. EDX showed the presence of Ca2+, Mg2+, and silica ions in the sludge which proved the removal of these scale species from CTB water. As a conclusion, this study revealed that EC process using Al-electrode is a promising technology for the removal of scale forming species from CTB water.

Energy and exergy analyses of a mass-fired boiler for a proposed waste-to-energy power plant in Tehran

Thermodynamic analysis of a municipal solid waste-to-energy boiler was thoroughly conducted. For this purpose, mass, energy, and exergy balance equations were formed over the entire boiler and its components. This study aimed to report the first and second law efficiencies to identify the main sources of irreversibility within the boiler. Three districts of Tehran mega city were selected, and the fictive molecule C26.75H3.58O15.79N1.08S0.11 was obtained from the average chemical composition of the aggregated waste. Moreover, the zonal method was applied to design the furnace, following by a simpler approach to design heat recovery steam generator. The energy and exergy analysis was then performed for all components and the entire boiler, followed by a sensitivity analysis on the blow-down water ratio effects. Results indicated that the irreversibility in furnace, with 52,617.3 kJs-1, was the main source of the exergy destruction. In addition, the overall energetic and exergetic efficiency of the studied boiler were reported as 78.7 and 16.0%, respectively.It appears that as a consequence of relatively small lower heating value of the utilized waste and considering the heat loss due to the bottom ash and blow-down water, a considerable reduction in the boiler efficiency occurred.

Power Plant Output Augmentation by Evaporative Cooling Based on HRSG Blowdown Water Recycling in the Kingdom of Saudi Arabia: A Novel Approach

Water is a scarce natural resource fundamental for human life. Power plant architects, engineers, and power utilities owners must do everything within their hands and technical capabilities to decrease the usage of water in power plants. This paper illustrates the research carried out by Pöyry Switzerland to reduce the water consumption on power and desalination combined cycle power plants, on which there are gas turbine evaporative cooling systems in operation. The present study analyzed the potential re-utilization and integration of the heat recovery steam generator (HRSG) blowdown into the evaporative cooling system. Relatively clean demineralized water, coming from the HRSG blowdown, is routed to a large water tank, where it is blended with distillate water to achieve the required water quality, before being used on the gas turbine evaporative cooling system. To prove the feasibility of the HRSG blowdown recycling concept, the Ras Al Khair Power and Desalination Plant owned and operated by the Saline Water Conversion Corporation (SWCC), located in the Eastern Province of the Kingdom of Saudi Arabia, was used as case study. Nevertheless, it is important to mention that the principles and methodology presented on this paper are applicable to every power and desalination combined cycle power plant making use of evaporative cooling. Sea water desalination is the primary source for potable water production on Saudi Arabia, with secondary sources being surface water and groundwater extracted from deep wells and aquifers. Saving water is of utmost importance for power plants located in locations where water is scarce, and as such, this paper aims to demonstrate that it is possible to decrease the water consumption of power and desalination combined cycle plants, on which evaporative cooling is used as gas turbine power booster, without having to curtail power production. The outcome of the study indicates that during the summer season, recycling the HRSG water blowdown into the gas turbine evaporative cooling systems would result on the internal water consumption for the gas turbine evaporative coolers decreasing by 545 ton/day, or 23.79%, compared with the original plant design which does not contemplate blowdown re-use. Using evaporative cooling results on an overall gain of 186 MW, or 10.27%, on gross power output, while CO2 emissions decrease by 46.8 ton CO2/h, which represents a 13.8% reduction compared with the case on which the evaporative cooling system is not in operation. A brief cost analysis demonstrated that implementation of the changes would result in a negligible increase of the operational expenses (OPEX) of the plant, i.e., implementation of the suggested modification has an unnoticeable impact on the cost of electricity (CoE). The payback of the project, due to limited operating hours on evaporative cooling every year, is of 12 years for a 30 year plant lifetime, while 2.22 M USD of extra-revenue on potable water sales are generated as a result of implementing the proposed solution. Although in principle this value is modest, the effect of government subsidies on water tariffs as well as political and strategic cost of water is not included on the calculations. In conclusion, the study results indicate that water recycling, and reduction of plant's water footprint for power and desalination combined cycle plants using evaporative cooling, is not only technically possible but commercially feasible.

Разработка методики прогнозирования глушения теплообменных трубок парогенератора атомных электростанций с водо-водяным энергетическим реактором

The main feature of an NPP steam generator (SG) is that in addition to steam generation, it shall reliably and constantly cool the NPP reactor’s core. The SG shall also comply with a stringent requirement of ensuring tightness of the primary and secondary circuits with respect to each other; i.e., its design shall exclude the possibility of damage to the heat-transfer and other elements loss of tightness of which entails ingress of radioactive primary coolant into the NPP steam--water circuit with the subsequent possibility of radioactive products releasing into the environment. Thus, ensuring reliable operation and design life of SG heat-transfer tubes (HTTs) is among top-priority objectives for different types of NPPs used both in the domestic nuclear power industry and abroad. Thin-walled SG HTTs constitute an important part of the primary circuit boundary, and in order to perform the function of an efficient barrier, HTTs shall not have through defects or defects generating the need to blank off them. The article describes methods used to predict blanking off heat-transfer tubes and the residual technical life of the SG tube bundle used at an NPP equipped with a water-cooled water-moderated power-generating reactor (VVER) and presents the results from calculating the permissible average value of chloride ion concentration during the operation. To assess the SG operation time to failure, a computer program has been written in the MathCad environment, using which the above-mentioned assessment can be performed within an acceptable timeframe and with sufficient accuracy. A conclusion has been drawn about the need to adopt more stringent requirements for the chloride ion concentration in the SG blowdown water to avoid the need of blanking off leaky tubes damaged as a result of stress corrosion cracking.

Electromembrane recycling of highly mineralized alkaline blowdown water from evaporative water treatment plants at thermal power stations

Thermal power stations (TPS) are the main source of highly mineralized effluents affecting the environment. An analysis of their water systems demonstrates that alkaline effluents prevail at TPSs. Extraction of an alkali from highly mineralized effluents can make the recycling of effluents economically feasible. A method is proposed of electromembrane recycling of liquid alkaline highly mineralized wastes from TPSs. The process includes electromembrane apparatuses of two types, namely, a diffusion dialysis extractor (DDE) intended for extraction of the alkali from a highly mineralized solution having a complex composition and an electrodialysis concentrator for increasing the concentration of the extracted solution to a value suitable for use in water treatment plants at TPSs. For implementation of the first process (i.e. the extraction of alkali from alkaline-salt solution) various membranes from various manufacturers were studied: CM-PAD and AM-PAD (Ralex, Czechia), MK-40, MA-40, MA-41, MA-414, and MB-2 (OOO OKhK “Shchekinoazot”, Russia), AR103-QDF and СR61-CMP (Ionies Inc., USA). The experiments demonstrate that the acceptable degree of separation of the alkali and the salt is achieved in a pair of cation-exchange membranes with the efficiency of separation being higher without an electric field. The highest efficiency was attained with Russian-made membranes (MK-40, OOO OKhK “Shchekinoazot”). A full scale experiment on recycling of highly-mineralized blowdown water from the evaporating water treatment system at the Kazan cogeneration power station No. 3 (TETs-3) was performed in a pilot unit consisting of two electromembrane apparatuses made by UAB “Membraninės Technologijos LT”. In the experiments every ton of blowdown water yielded 0.1 t of concentrated alkaline solution with an alkali content of up to 4 wt % and 0.9 t of the softened salt solution suitable for the reuse in the TPS cycle. The power rate is 6 kWh / ton of blowdown water.

Membrane distillation of industrial cooling tower blowdown water

The potential of membrane distillation for desalination of cooling tower blowdown water (CTBD) is investigated. Technical feasibility is tested on laboratory and pilot scale using real cooling tower blowdown water from Dow Benelux in Terneuzen (Netherlands). Two types of membranes, polytetrafluorethylene and polyethylene showed good performance regarding distillate quality and fouling behavior. Concentrating CTBD by a factor 4.5 while maintaining a flux of around 2l/m2*h was possible with a water recovery of 78% available for reuse. Higher concentration factors lead to severe decrease in flux which was caused by scaling. Membrane distillation could use the thermal energy that would otherwise be discharged of in a cooling tower and function as a heat exchanger. This reduces the need for cooling capacity and could lead to a total reduction of 37% water intake for make-up water, as well as reduced energy and chemicals demands and greenhouse gas emissions.

Recovery of cooling tower blowdown water for reuse: The investigation of different types of pretreatment prior nanofiltration and reverse osmosis

The suitability of two different pretreatment methods, i.e., coagulation-filtration and ultrafiltration (UF), and two final membrane treatment technologies, namely nanofiltration (NF) and reverse osmosis (RO), for desalination of a cooling tower blowdown (CTBD) was investigated. Particular attention was paid to ensuring that the best pretreatment method could enhance the permeate flux and lifespan of the NF and RO membranes and decrease the membranes' fouling characteristics. Furthermore, the difference of NF and RO performances in CTBD treatment was investigated.In order to find the most appropriate type of coagulant, coagulant dosage, pH and co-coagulant dosage, 21 jar tests were performed. The results showed that 50mg/L of Polyaluminium chloride (PACl) in the presence of 0.5ppm co-coagulant in pH of 6.5–7.5 has the best treatment performance. Silt density index (SDI), chemical oxygen demand (COD), turbidity, electrical conductivity, and membrane permeate flux tests were performed for both pretreatment and treatment stages. Both pretreatment methods produced appropriate feed for NF and RO in terms of SDI and turbidity. Using the coagulation–filtration pretreated water instead of raw water as a feed for NF and RO membranes showed about a 25 and 33 percent improvement in permeate flux after 100min in 10 and 15bar applied pressure for NF and RO, respectively.

Fabrication and evaluation of an attapulgite membrane as the filter for recycling blowdown water from industrial boilers

Continuous blowdown water (CBW) from industrial boilers is of great quantity and energy, and therefore worth recycling. According to the data from a long period of monitoring, carbonate and sulfate were documented as the main contaminants in CBW. Herein, an attapulgite (ATP) membrane was prepared on a macroporous Al2O3 support through solid state sintering. The prepared membrane (attapulgite membrane (ATM)) was characterized by mercury porosimetry, scanning electron microscope, X-ray diffraction, and permselectivity analysis in dead-end mode. The optimal sintering temperature was 800 °C based on the morphology of the sintered active layer and its adhesive strength with support. The active layer exhibited a pore size distribution concentrated on 12.7nm with a thickness of about 80μm. In addition, crystal structures of ATP were retained in powder form after sintering. ATM obtained a pure water permeability of 1,411.87Lm–2h–1MPa–1 with the effective retention of carbonate and sulfate through electrical-related interactions. Several ATM filters were also developed and mounted on the boiler blowdown pipe, which had a high rejection rate of alkalinity and dissolved solids in CBW. The volume of wastewater emitted from the low-pressure boiler was reduced, since the filtrate could be recycled as part of the make-up water.

Carbon Nanotube–Based Electrodes for Detection of Low–ppb Level Hexavalent Chromium Using Amperometry

Carbon nanotube (CNT)-based electrodes, prepared using a printable technique, were investigated for the electrochemical detection of hexavalent chromium (Cr(VI)). CNT pastes were coated onto paper substrates and commercially available screen-printed electrodes and used as amperometric sensors for Cr(VI). The CNT electrodes showed electrochemical current responses as high as 500 nA/ppb Cr(VI) and limit of detection as low as 5 ppb when a large area electrode was used. The CNT-modified, screen-printed electrodes showed good selectivity to Cr(VI) and were effective for quantifying the Cr(VI) levels in cooling tower blowdown water. A selective H2O2 reduction technique was also applied to Cr(VI) detection and integrated into amperometric detection in a flow cell. These studies show that CNT-based electrodes can be promising for field applications and real-time monitoring of low-level Cr(VI) in power plant waters.

An integrated approach for incorporating thermal membrane distillation in treating water in heavy oil recovery using SAGD

The production of heavy oil and bitumen requires unconventional methods. One such approach is steam-assisted gravity drainage (SAGD). This technology has key advantages but is characterized with substantial levels of water consumption and discharge. Therefore, there is a need for effective water treatment and reuse methods in SAGD. This paper examines the use of an emerging technology: thermal membrane distillation (TMD) as an integral part of water treatment for SAGD. Synergistic effects are exploited from heat and mass integration of SAGD and TMD. Specifically, the hot produced water and blowdown water are evaluated for treatment using TMD because of their thermal content and because of the need for high levels of purity which can be achieved by TMD. Several design configurations and scenarios are proposed and evaluated to assess the technical and economic viability of including TMD as a process in water-management systems for SAGD.

Hexavalent Chromium Removal in Industrial Relevant Water Matrices Using Metal Oxide Photocatalysts

Photocatalysis is an attractive treatment method for removing hexavalent chromium, Cr(VI), from water. Thus far, photocatalytic reduction of Cr(VI) has been investigated mostly using TiO2 photocatalysts in acidic water solutions. Here we investigate Cr(VI) removal using zinc oxide (ZnO), tungsten trioxide (WO3), and sodium tantalate (NaTaO3), metal oxides that display good activity for other photocatalytic reactions such as water splitting, as well as the P90 form of TiO2 . The efficiency for Cr(VI) removal using these photocatalysts was investigated in synthetic neutral and alkaline water, as well as in cooling tower blowdown water. A few common industrial additives were examined and the improvement on Cr(VI) removal using NaTaO3 from high to low was: sodium sulfite > ammonium chloride > sodium formate. At neutral pH, citric acid was found to inhibit Cr(VI) reduction with NaTaO3. Sulfite alone could remove Cr(VI) by chemical reduction, but required large quantities in excess. The combination of sulfite and photocatalyst greatly improved the Cr(VI) removal. Cr(VI) removal using photocatalysts was only slightly affected by other constituents in cooling tower blowdown and had similar removal rates as those observed in pH 7 DI water. NaTaO3 was found to display the highest Cr(VI) removal rates on a photon basis at pH = 3 and in the presence of sodium sulfite, while ZnO and TiO2 showed the best performance in pH = 7 and cooling tower blowdown water. Different regeneration protocols were applied to the used photocatalysts. The alkaline treatment was more effective for removing adsorbed Cr(III) compared to nitric acid treatment, but acid treated TiO2 had better subsequent Cr(VI) reduction capabilities due to surface modifications that enhanced Cr(VI) adsorption. Both acid regenerated TiO2 and NaTaO3 demonstrated comparable Cr(VI) reduction rates with the pristine forms, indicating that these photocatalysts could be stable during regeneration and recycled for multiple uses. These results show that large scale wastewater treatment using metal oxide photocatalysts to remove Cr(VI) may be possible.

Hexavalent chromium removal using metal oxide photocatalysts

Photocatalysis is an attractive treatment method for removing hexavalent chromium (Cr(VI)) from water. Thus far, photocatalytic reduction of Cr(VI) has been investigated mostly using TiO2 photocatalysts in acidic water solutions. Here we investigate Cr(VI) removal using zinc oxide (ZnO), tungsten trioxide (WO3), and sodium tantalate (NaTaO3), metal oxides that display good activity for other photocatalytic reactions such as water splitting, as well as titanium oxide (TiO2, Evonik P90). The efficiency for Cr(VI) removal using these photocatalysts was investigated in synthetic neutral and alkaline water, as well as in cooling tower blowdown water. The effect of several additives used in water treatment processes on the Cr(VI) removal rate was also studied. For NaTaO3, citric acid was found to have a detrimental effect to Cr(VI) removal, while sodium formate, ammonium chloride, and sodium sulfite were beneficial. While sulfite alone could chemically reduce Cr(VI), sulfite in combination with a photocatalyst resulted in faster and complete removal of Cr(VI) in 10min using a SO32−/Cr(VI) ratio >35 in pH∼8 solutions. NaTaO3 was found to display the highest Cr(VI) removal rates on a photon basis at pH 3 and in the presence of sodium sulfite, while ZnO and TiO2 showed the best performance in pH 7 and cooling tower blowdown water.

Rationale for blowdown water conditioning circuits of zero-discharge recirculating cooling systems at NPP

Приведены результаты расчетов физико-химических показателей продувочной воды по этапам обработки. Обоснован принцип построения бессточных схем производства воды различного качества для питания циклов АЭС из продувочных вод оборотных систем охлаждения путем разделения массово-солевого потока продувочной воды на два, каждый из которых по своему составу соответствует нормативам, предъявляемым к питательной воде циклов станции.

Dissolved Organic Matter in Steam Assisted Gravity Drainage Boiler Blow-Down Water

Steam assisted gravity drainage (SAGD) boiler blow-down (BBD) water contains high concentrations of dissolved organic matter (DOM) and total dissolved solids (TDS). A detailed understanding of the BBD chemistry, particularly the DOM composition, is important for better management and recycle of this water. In this study, we fractionated the dissolved organic matter in the BBD using DAX-8, Dowex, and Duolite resins into hydrophobic and hydrophilic fractions of acid, base, and neutral compounds. Additionally, the DOM was fractionated on the basis of size by filtering the BBD through a series of membranes with progressively tighter molecular weight cutoffs of 10, 3, and 0.5 kDa. Fluorescence excitation–emission matrix spectroscopy (EEMs), specific UV absorbance (SUVA), and FTIR were used to characterize the water samples and the different fractions. The ion exchange fractionation revealed that the DOM contained a high percentage of hydrophobic acids (39%) and hydrophilic neutrals (28.5%). The different ion e...

A fuzzy approach for modelling radionuclide in lake system

Radioactive liquid waste is generated during operation and maintenance of Pressurised Heavy Water Reactors (PHWRs). Generally low level liquid waste is diluted and then discharged into the near by water-body through blowdown water discharge line as per the standard waste management practice. The effluents from nuclear installations are treated adequately and then released in a controlled manner under strict compliance of discharge criteria.An attempt was made to predict the concentration of 3H released from Kakrapar Atomic Power Station at Ratania Regulator, about 2.5 km away from the discharge point, where human exposure is expected. Scarcity of data and complex geometry of the lake prompted the use of Heuristic approach. Under this condition, Fuzzy rule based approach was adopted to develop a model, which could predict 3H concentration at Ratania Regulator. Three hundred data were generated for developing the fuzzy rules, in which input parameters were water flow from lake and 3H concentration at discharge point. The Output was 3H concentration at Ratania Regulator. These data points were generated by multiple regression analysis of the original data. Again by using same methodology hundred data were generated for the validation of the model, which were compared against the predicted output generated by using Fuzzy Rule based approach. Root Mean Square Error of the model came out to be 1.95, which showed good agreement by Fuzzy model of natural ecosystem.

Experimental evaluation on concentrating cooling tower blowdown water by direct contact membrane distillation

Concentration of simulated cooling tower blowdown water (CTBD) by the desalination process of direct contact membrane distillation (DCMD) has been evaluated. A bench-scale DCMD setup was used to test the desalination performance. Both silica-free and silica-containing simulated CTBD water were prepared and concentrated. The concentration process using DCMD produced a permeate flux of about 30L/m2·h and a salt rejection of more than 99.95% under feed side temperature of about 60°C. Membrane scaling was examined for the simulated feeds. It was exhibited that insoluble calcium carbonate scale formed on membrane under concentration factor of about 3.7–4.0 for silica-free simulated CTBD water. Silica, calcium carbonate and sulfate scaling precipitated together under concentration factor of about 3.2–5.0 for silica-containing simulated CTBD water. The scales resulted in the drop of both permeate flux and salt rejection, while the performance was recovered after membrane cleaning. The addition of antiscalant enhanced the concentration factor to about 8.0 and the corresponding water recovery to about 87%. The experimental results indicated that MD is a potential feasible technology for the water recovery of CTBD water.

New corrosion inhibitors for evaporative cooling systems

Corrosion of heat exchangers and installations in evaporative cooling systems is a serious problem of industry, as it may lead to increased maintenance effort, damages, up to plant shut-down causing high cost. Furthermore, there may be a high environmental impact due to the discharge of blow-down water containing heavy metals or hazardous compounds, which may enter the water system via leakages.State of the art corrosion inhibitor programs are based on phosphate, phosphonates, zinc and combinations thereof. Although generally satisfying control of corrosion can be achieved, all programs suffer more or less severe drawbacks, such as lack of biodegradability, content of heavy metals or necessity of pH control combined with acid dosage. Consequently, there is a need of corrosion inhibitors having an improved environmental profile and/or an improved performance. This paper shows the first results of two newly developed corrosion inhibitors. Both molecules are based on modified organic acids, free of heavy metals, one additionally doesn’t contain phosphorous.Corrosion tests have been carried out with carbon steel specimen in dependence of inhibitor concentration, water composition and water temperature. Electrochemical methods, e.g. voltammetrie and polarization resistance, were applied as well as beaker tests and long term tests in cooling circuit simulating devices. Furthermore, the anti-scaling efficiency of the new inhibitors was studied.The results of the corrosion tests clearly show an excellent efficiency of both substances, that meets the performance of commercially available corrosion inhibitors. In addition to this the phosphorous containing molecule shows a very good inhibition of calcium carbonate scaling, similar or even better compared to the performance of modern polycarboxylates. Thus, it could be the backbone of a complete treatment program for cooling systems. The second corrosion inhibitor could be applied in phosphorous and heavy metal free corrosion inhibition programs.

Characterization of Boiler Blowdown Water from Steam-Assisted Gravity Drainage and Silica–Organic Coprecipitation during Acidification and Ultrafiltration

In thermally enhanced oil recovery operations, particularly in steam-assisted gravity drainage (SAGD), boiler blowdown (BBD) containing high concentrations of dissolved organic matter (DOM), dissolved silica, and total dissolved solids (TDS) is generated. To develop efficient tools for managing this blowdown, a detailed understanding of its chemistry is required. In this study, BBD was evaporated to yield ∼66% condensate and ∼33% concentrate blowdown (CBD). Detailed characterization of the BBD and CBD water was conducted. The effect of acidification was also studied. The acidification coprecipitates the silica and DOM, with over 90% of the silica and over 40% of the DOM precipitating at pH 4. Ultrafiltration treatment was also examined, and a major fraction of the silica and DOM in the CBD was found to foul a 100 kDa ultrafiltration membrane in the pH range of 7.5 to 9. The analysis revealed that the dominant fouling mechanism was cake filtration, indicating the formation of a silica–DOM precipitate layer on the membrane surface. These studies can provide insight regarding management options for SAGD disposal water.