Improvement of water treatment at thermal power plants
TL;DR: The results obtained from laboratory investigations and industrial tests of the proposed technologies carried out at different thermal power plants are presented in this paper, where the possibilities of improving the process and environmental indicators of water treatment plants are shown.
Abstract: Prospective and existing technologies for water treatment at thermal power plants, including pretreatment, ion exchange, and membrane method are considered. The results obtained from laboratory investigations and industrial tests of the proposed technologies carried out at different thermal power plants are presented. The possibilities of improving the process and environmental indicators of water treatment plants are shown.
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01 Aug 2020
9 citations
TL;DR: In this article, a technique for utilizing the wastewater of the reverse-osmosis plants (ROPs) to prepare the make-up water for power-generating plants of combined heat and power plants and nuclear power plants is proposed and substantiated using mathematical models and full-scale experiments.
Abstract: Technologies for utilizing the wastewater of the reverse-osmosis plants (ROPs) to prepare the make-up water for power-generating plants of combined heat and power plants and nuclear power plants are proposed and substantiated using mathematical models and full-scale experiments. The ROPs use natural feedwater with a wide range of quality characteristics. For the first time, variants of the treatment of the concentrate formed in the ROP cycle have been proposed for the reuse of the latter by acidifying it in H-type cation- exchange filters charged with a weakly acidic cation-exchange resin. By admixing part of the filtrate processed in the H-type cation-exchange filters to the feedwater, the latter is acidified thus reducing the probability of formation of carbonaceous sediments and water consumption. The rest of the filtrate subjected to a conversion process is used as a constituent of the make-up feedwater of the heating system or potable water, which eliminates the discharge of the reverse-osmosis plant wastewater into the environment. Another feature of the proposed technology is that the H-type cation-exchange filters are integrated into a regenerant solution reuse circuit (RSRC). As a result, the consumption rate of sulfuric acid for regeneration equals the stoichiometric rate and the regeneration yields gypsum used to produce a binding agent for construction. The kinetics of separation of gypsum from the spent regenerant solutions with different chemical compositions was studied experimentally as applied to the RSRC conditions. The procedure of operating filters charged with the Lewatit CNP-LF cation-exchange resin was trialed under production conditions. It was established that the height of the filtering cation-exchange resin layer should be 1.0–1.5 m and the concentration of the regenerant solution should not exceed 0.8% at a rate of 10–15 m/h. The basic components of the technological scheme were trialed under production conditions on a water treatment plant in service.
6 citations
TL;DR: In this paper, partial desalination of recirculating cooling towers (CT) feed water with membrane capacitive deionization (MDCI) can improve water quality but also results in additional water loss.
Abstract: Cooling of thermal power stations requires large amounts of surface water and contributes to the increasing pressure on water resources. Water use efficiency of recirculating cooling towers (CT) is often kept low to prevent scaling. Partial desalination of CT feed water with membrane capacitive deionization (MDCI) can improve water quality but also results in additional water loss. A response surface methodology is presented in which optimal process conditions of the MCDI-CT system are determined in view of water use efficiency and cost. Maximal water use efficiency at minimal cost is found for high adsorption current (2.5 A) and short adsorption time (900 s). Estimated cost for MCDI to realize maximal MCDI-CT water use efficiency is relatively high (2.0–3.1 € m−3evap), which limits applicability to plants facing high intake water costs or water uptake limitations. MCDI-CT pilot tests show that water use efficiency strongly depends on CT operational pH. To allow comparison among pilot test runs, simulation software is used to recalculate CaCO3 scaling and acid dosage for equal operational pH. Comparison at equal pH shows that MCDI technology allows a clear reduction of CT water consumption (74%–80%) and acid dosage (63%–80%) at pH 8.5.
4 citations
Cites background from "Improvement of water treatment at t..."
...Membrane based water treatment technologies have essential advantages over ion exchange in terms of environmental indicators but produce more effluent [8]....
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...Previously explored strategies to improve water efficiency of wet cooling towers include feed pretreatment [8,9], use of alternative feed sources [10], circulation water conditioning and acidification [11] and blowdown recuperation [12–14]....
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TL;DR: In this article, temporary quality standards for the heat medium developed by the All-Russia Thermal Engineering institute (VTI) for CCP power units are presented in comparison with the IAPWS standards; preferences for the choice of a compound water chemistry (WC) type for some power units commissioned in Russia in the first decade of this century are shown; and operational data on the quality of feed, boiler water, and steam for two large CCP-450 and CCP-425 power units were given.
Abstract: Damageability of heat transfer surfaces of waste heat recovery steam generators (HRSG) of combined- cycle plants (CCP) can be reduced due to an increase in the quality of make-up and feed water, the use of phosphate-alkaline or amino compound water chemistry (WC), and improved chemical quality control of the heat carrier and make-up water preparation techniques Temporary quality standards for the heat medium developed by the All-Russia Thermal Engineering institute (VTI) for CCP power units are presented in comparison with the IAPWS standards; preferences for the choice of a WC type for some power units commissioned in Russia in the first decade of this century are shown; and operational data on the quality of feed, boiler water, and steam for two large CCP-450 and CCP-425 power units are given The state and prospects for the development of chemical-technological monitoring systems and CCP water treatment plants are noted Estimability of some CCP diagnostic parameters by measuring specific electric conductivity and pH is shown An extensive bibliography on this topic is given
3 citations
TL;DR: In this article, a software program was developed and measured the concentrations of soluble aluminum and iron sulfate at different pH values of the source water, and experiments were performed on both qualitative and quantitative analysis of the content of natural organic matters in the Volga water and their structure.
Abstract: The innovative baromembrane technologies for water demineralization were introduced at Russian TPPs more than 25 years ago. While being used in the power engineering industry of Russia, these technologies demonstrated certain advantages over the traditional ion-exchange and thermal technologies of makeup water treatment for steam boilers. Water treatment units based on the baromembrane technology are compact, easy to operate, and highly automated. The experience gained from the use of these units shows that their reliability depends directly on preliminary water treatment. The popular water pretreatment technology with coagulation by aluminum oxychloride proved to be inefficient during the seasonal changes of source water quality that occurs at some stations. The use of aluminum coagulant at pH 8 and higher does not ensure the stable and qualitative pretreatment regime: soluble aluminum forms slip on membranes of the ultrafiltration unit, thereby causing pollution and intoxication as well as leading to structural damages or worsening of mechanical properties of the membranes. The problem of increased pH and seasonal changes of the source water quality can be solved by substitution of the traditional coagulant into a new one. To find the most successful coagulant for water pretreatment, experiments have been performed on both qualitative and quantitative analysis of the content of natural organic matters in the Volga water and their structure. We have developed a software program and measured the concentrations of soluble aluminum and iron salts at different pH values of the source water. The analysis of the obtained results has indicated that iron sulfate at pH 6.0−10.2, in contrast to aluminum oxychloride, is not characterized by increased solubility. Thus, the basic process diagrams of water pretreatment based on baromembrane technologies with pretreatment through coagulation by iron salts and wastewater amount reducing from 60–40 to 5–2% have been introduced for thermal power stations.
3 citations
References
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Journal Article•
TL;DR: The results of many years of developments at the All-Russia Institute of Atomic Machine Building and the Ivanovo State Power University in the field of promising equipment for water-treatment installations are presented in this paper.
Abstract: The results of many years of developments at the All-Russia Institute of Atomic Machine Building and the Ivanovo State Power University in the field of promising equipment for water-treatment installations are presented. They comprise three directions: ion-exchange technology, thermal demineralization, and membrane technology of natural water demineralization. The results of technical and economic comparison of the above technologies are given for a general case, as well as for particular water-treatment installations.
7 citations
TL;DR: In this article, two process circuits for demineralizing makeup water for power units at thermal power stations are considered, one of them is constructed on the basis of a combined plant comprising reverse-osmosis and ion-exchange apparatuses, and the other comprises reverse-osais and electric deionization apparatus.
Abstract: Two process circuits for demineralizing makeup water for power units at thermal power stations are considered. One of them is constructed on the basis of a combined plant comprising reverse-osmosis and ion-exchange apparatuses and the other comprises reverse-osmosis and electric deionization apparatuses. The considered circuits are analyzed by way of comparing them with the traditional chemical water demineralization system. Advantages and drawbacks of the new technologies for treating natural water are pointed out.
7 citations
TL;DR: In this paper, the use of membrane water treatment technologies for deeply removing organic compounds from steam-water paths at thermal power stations is considered, and it is shown that the membrane technologies allow organic substances to be removed from water more efficiently than do the traditional technologies.
Abstract: The prospects of using the membrane water treatment technologies for deeply removing organic compounds from steam-water paths at thermal power stations are considered. It is shown that the membrane technologies allow organic substances to be removed from water more efficiently than do the traditional technologies.
2 citations
TL;DR: In this article, an analysis of the performance of the water pretreatment plant used at the TETs-5 cogeneration station operated by the Kirov Branch of OAO TGK-5 and from tests of clarifiers under the conditions of the existing technology are presented.
Abstract: Results from an analysis of the performance of the water pretreatment plant used at the TETs-5 cogeneration station operated by the Kirov Branch of OAO TGK-5 and from tests of clarifiers under the conditions of the existing technology are presented. Data obtained from laboratory studies of the properties of flocculants under local conditions are presented and their efficiency is estimated.
1 citations
TL;DR: Technological and design possibilities of improving clarifiers for coagulation treatment of water are considered and the results obtained from implementing these possibilities in real devices are presented.
Abstract: Technological and design possibilities of improving clarifiers for coagulation treatment of water are considered. The results obtained from implementing these possibilities in real devices are presented.
1 citations