Papers by Keyword: Chemical Cleaning

Abstract: Each machine and energetic equipment needs maintenance or cleaning time. Energetic equipment needs more regular cleaning so it works well and reliably, and the heat transfer is permanent and there is no energy loss. The inner surface of heating systems are successively covering during their operation, due to the chemical and physico-chemical reactions, solid, some dirt, minerals and corrosion products. It is therefore advisable to regularly clean and service these devices. The article deals with the distribution of exchangers, formation of sediments and corrosion products associated with their operation. In addition, the article describes the types of internal surface cleaning methods. The whole article ends with a chemical cleaning experiment, where the heat exchanger clogged with mineral deposits was cleaned. The defectoscopic images show how the chemical can remove all deposits and restore the exchanger flow to its original state.

Abstract: A kind of multifunctional environmentally friendly corrosion inhibitor (DHS) was prepared in order to protect many kinds materials from corrosion in iron and steel enterprise. The corrosion inhibition performance was studied by rotary hanging-piece corrosion tests . And biodegradability was investigated by biodegradation experiments . The experimental results showed that DHS has good performance both on corrosion inhibition and biologic degradable. It was suitable for the serious of materials and presense in iron and steel enterprise when the concentration of DHS was 0.4%. And the efficiency of biodegradability was 52.45% in 28d .

Abstract: Insufficient output and rising pressure after governing stage of a 630 MW supercritical unit occurred only 18 month after the first outage. Though analysis based on measured parameters, fouling existed in governing stage and the first stage group. By virtue of linearization of formula and decoupling the impacts to thermal characteristic parameters, the quantified deposition degree was obtained. The fouling reason was determined by scale sample analysis, and the solution was proposed by quantitative calculation. The problem was successfully solved with boiler pickling, turbine cascade jet-beading and pulsing minimum oxygen to inhibit flow accelerated corrosion. A steam quality detection method was also proposed as the installation of measurement point after governing stage of supercritical unit. These treatments provided building and operation experience for 1000MW ultra-supercritical turbine and the same type of equipments.

Abstract: The main objective of this study was to investigate foulants in chemical cleaning solutions of membrane (CCSM). Sodium hydroxide (NaOH), sodium hypochlorite (NaOCl), hydrochloric acid (HCl) were used as chemical agents respectively. Hydrophobicity, molecular weight distribution and metal ions of foulants in CCSM were analyzed as the major characters for membrane fouling. Results reveal that alkali cleaning can remove both hydrophobic and hydrophilic fractions of natural organic matters (NOM), and acid cleaning mainly removes hydrophilic organic matters. Medium molecular weight of very hydrophobic acids (1-10 kDa) and different molecular weight of neutral hydrophilic acids (100-1000 Da & >300kDa) in NOM can lead to membrane irreversible fouling. Acid cleaning is relatively effective for the reduction of inorganic foulants. The main metal ions in acid cleaning solutions are K ,Ca, Al and Mn, which are responsible for membrane inorganic fouling.