FEATURES OF WATER TREATMENT FOR BOILER ROOMS

Thousands of medium and low steam boilers and hot water boilers operate in the country's industry, municipal energy and agriculture. Their reliable operation is largely determined by the maintenance of a rational water-chemical regime. The main problems of source water are the presence of dissolved oxygen, iron ions, salts of calcium, and magnesium. The aim of the work is to analyze the existing technologies and equipment for water treatment for different types of boilers. Determination of physicochemical parameters and requirements for source and prepared water. Presentation of new multi-purpose energy-efficient and resource-saving water treatment equipment. The article considers the negative impact of dissolved iron, hardness salts, dissolved gases present in the feed water on the operation of boiler equipment. The main requirements for feed water in terms of hardness, the content of dissolved oxygen, and oils for steam and hot water boilers are given. The mechanism of scale formation is given. The main existing methods of feed water treatment are considered, namely softening on Na-cation exchange resin, liming, softening, and reduction of total salt content on reverse osmosis units, softening, and reduction of total salt content by the sequential passage of water through H, OH-ion exchange filters. A multi-purpose aeration-oxidation setup of rotor type (AORT) is presented, which implements the method of discrete-pulse energy input, on which it is possible to carry out operations to remove iron, manganese, hardness salts, increase pH and degassing from water.

Hyperspectral Prediction of Soil Total Salt Content by Different Disturbance Degree under a Fractional-Order Differential Model with Differing Spectral Transformations

Soil salinization is an ecological challenge across the world. Particularly in arid and semi-arid regions where evaporation is rapid and rainfall is scarce, both primary soil salinization and secondary salinization due to human activity pose serious concerns. Soil is subject to various human disturbances in Xinjiang in this area. Samples with a depth of 0–10 cm from 90 soils were taken from three areas: a slightly disturbed area (Area A), a moderately disturbed area (Area B), and a severely disturbed area (Area C). In this study, we first calculated the hyperspectral reflectance of five spectra (R, R, 1/R, lgR, 1/lgR, or original, root mean square, reciprocal, logarithm, and reciprocal logarithm, respectively) using different fractional-order differential (FOD) models, then extracted the bands that passed the 0.01 significance level between spectra and total salt content, and finally proposed a partial least squares regression (PLSR) model based on the FOD of the significance level band (SLB). This proposed model (FOD-SLB-PLSR) is compared with the other three PLSR models to predict with precision the total salt content. The other three models are All-PLSR, FOD-All-PLSR, and IOD-SLB-PLSR, which respectively represent PLSR models based on all bands, all fractional-order differential bands, and significance level bands of the integral differential. The simulations show that: (1) The optimal model for predicting total salt content in Area A was the FOD-SLB-PLSR based on a 1.6 order 1/lgR, which provided good predictability of total salt content with a RPD (ratio of the performance to deviation) between 1.8 and 2.0. The optimal model for predicting total salt content in Area B was a FOD-SLB-PLSR based on a 1.7 order 1/R, which showed good predictability for total salt content with RPDs between 2.0 and 2.5. The optimal model for predicting total salt content in Area C was a FOD-SLB-PLSR based on a 1.8 order lgR, which also showed good predictability for total salt content with RPDs between 2.0 and 2.5. (2) Soils subject to various disturbance levels had optimal FOD-SLB-PLSR models located in the higher fractional order between 1.6 and 1.8. This indicates that higher-order FODs have a stronger ability to extract feature data from complex information. (3) The optimal FOD-SLB-PLSR model for each area was superior to the corresponding All-PSLR, FOD-All-PLSR, and IOD-SLB-PLSR models in predicting total salt content. The RPD value for the optimal FOD-SLB-PLSR model in each area compared to the best integral differential model showed an improvement of 9%, 45%, and 22% for Areas A, B, and C, respectively. It further showed that the fractional-order differential model provides superior prediction over the integral differential. (4) The RPD values that provided an optimal FOD-SLB-PLSR model for each area were: Area A (1.9061) < Area B (2.0761) < Area C (2.2892). This indicates that the prediction effect of data processed by fractional-order differential increases with human disturbance increases and results in a higher-precision model.

Comparison of Different Interpolation Methods for Prediction of Soil Salinity in Arid Irrigation Region in Northern China

Numerous methods have been used in the spatial prediction of soil salinity. However, the most suitable method is still unknown in arid irrigation regions. In this paper, 78 locations were sampled in salt-affected land caused by irrigation in an arid area in northern China. The geostatistical characteristics of the soil pH, Sodium Adsorption Ratio (SAR), Total Salt Content (TSC), and Soil Organic Matter (SOM) of the surface (0–20 cm) and subsurface (20–40 cm) layers were analyzed. The abilities of the Inverse Distance Weighting (IDW), Ordinary Kriging (OK), and CoKriging (CK) interpolation methods were compared, and the Root Mean Square Error (RMSE) was used to justify the results of the methods. The results showed that the spatial distributions of the soil properties obtained using the different interpolation methods were similar. However, the surface layer exhibits more spatial heterogeneity than the subsurface layer. Based on the RSME, the nugget/sill value and range significantly affected which method was the most suitable. Lower nugget/sill values and lower ranges can be fitted using the IDW method, but higher nugget/sill values and higher ranges can be fitted using the OK method. These results provide a valuable reference for the prediction of soil salinity.

Purification of Cr(VI)-containing wastewater by chemical precipitation: test results of an experimental-industrial installation

We present the main results of experimental and industrial study of the developed process and pilot plant for purification of the Cr(VI)-containing rinse water by chemical precipitation. This technique implies full or partial return of treated water to rinse workpieces after chromium plating and prepare working solutions (precipitators). We characterize the manufacturing scheme of the pilot plant and the mode of its performance. Saturated aqueous solutions of Са(ОH)2 and Ва(ОH)2 were used as precipitating reagents. The tests confirmed the possibility of automatic dosing the reagents with due regard for the pH value of a medium, which can be used in both continuous and periodic rinsing. The operating conditions of rinsing the workpieces after electrochemical chromium plating were justified. We derived the equation for the calculation of the total salt content in the rinse water after its purification. We determined the duration of the rinsing without the need to renew the bath volume. The performed calculations substantiated the possibility of reducing the consumption of fresh water supplied for rinsing by the recycling of wastewater without deteriorating the quality of the rinsed workpieces. The reduction of water consumption by 35% was observed as compared with that stated by the regulations.

RESEARCH OF THE EFFICIENCY OF REAGENT-FREE ELECTROMAGNETIC TREATMENT OF SOURCE WATER AT PETROCHEMICAL ENTERPRISES

A technological scheme and technical documentation for the manufacture of a test bench with a purified water capacity of 300 l/h have been developed. Long-term tests were carried out on a test bench, as well as analysis of the quality of the sampled water before purification, with the use of an electromagnetic treatment device and without it. As a result of the tests carried out, it was found that the total salt content after the reverse osmosis unit decreased from 535.5 to 30.0 mg / l, and in water with the use of magnetic water treat- ment – from 535.5 to 12.7. Moreover, the pH in the first case varied from 8.3 to 6.2, in the second – from 8.3 to 6.44. It has been established that the use of magnetic water treatment in desalination before the reverse osmosis unit has a positive result, namely, calcium and magnesium salts do not settle on the reverse osmosis membranes, thereby prolonging the service life of the reverse osmosis membranes.

Partitioning of volatile components (Cl, F, CO2) in water-saturated fluid-magmatic systems of various composition

The results of experimental studies of the behavior of volatile components (Cl, F, CO2 and H2O) in fluid-magmatic systems are presented. The maximum chlorine content in magmatic melts mainly depends on the composition of the melt and, to a lesser extent, on pressure (10300 MPa) and temperature (8001000C). The Cl content in the melt increases from 0.20.3 to 35 wt.% with increasing in the Ca content during the transition from polymerized granitoid to depolymerized basaltic melts. The pressure dependence of solubility has a maximum at a pressure of about 100200 MPa. A tendency of increasing in the Cl content and decreasing in the F content in the melt during the transition from acidic and alkaline to basaltic melts has been established. The maximum Cl content in the melt significantly increases from rhyolitic (up to 0.25 wt.%) to phonolitic (up to 0.85 wt.%) and dacitic (up to 1.2 wt.%) at temperatures of 10001200C and pressure of 200 MPa. The addition of CO2 to the system causes an increase in the Cl content in the melt by 2025 relative %, which is apparently associated with an increase in the Cl activity in the fluid. In this case, the H2O content in the melt decreases by ~ 0.51.0 wt.%. A strong effect of hydrolysis was shown in the interaction of an alumina-rich granitic melt with ~ 0.51N chloride fluid. This effect shows that at hypabyssal magmatic conditions (P = 100 MPa, T = 750C), the fluid is acidic (the pH after the experiment is ~ 11.5) and it is characterized by high dissolving power. It was established experimentally that as a result of the interaction of aqueous Na-K-Ca-chloride fluid of variable composition with granodioritic and granitic melts in the pressure range of ~ 100200 MPa and temperatures of 8201000C and with increasing in the total salt content, the Na and K replace Ca in the silicate melt, displacing the latter into the fluid, that is enriched in CaCl2 and is depleted in NaCl. Experimental results on the joint partitioning of Cl and F provide a quantitative basis for understanding the degassing processes in the course of the evolution of alkaline and basaltic magmas. They are important for assessing the extent of the removal of Cl and F into the earths atmosphere during volcanic activity and the effects of this removal on climate change.

Simulation of Water and Salt Transport in Soil under Pipe Drainage and Drip Irrigation Conditions in Xinjiang

With the popularization and development of drip irrigation under film, the problem of secondary soil salinization in Xinjiang is becoming more and more serious. To explore water and salt transport in drip irrigation under mulch and drainpipe drainage, drainage tests of drainage ditches in saline-alkali soil in the Xinjiang 112 group were used to monitor soil salinity changes by controlling field irrigation. Then, a HYDRUS (PC-Progress, Prague, Czech Republic) numerical model was used to simulate and analyze the changes in salinity during cotton growth and the autumn salt return stage in saline-alkali soil under drainage conditions. The agreement between the simulated and measured values was high, and the model parameters were reliable. During the growth period of cotton, the salinity continued to decrease, and the salt began to return after the harvest. Compared with before planting, in the 0–80 cm soil layer, the average desalinization rate reached 43.52% under the mulching films, and the average desalinization rate reached 13.83% under and between the mulching films. After the cotton was harvested, salt returned to the upper layer of soil. However, it still showed a decrease compared with the level before sowing. The average salt content of 0–80 cm soil decreased by 5.14%, and the average salt content of 0–200 cm decreased by 2.60%. This shows that the total salt content in soil will continue to decrease after long-term use of drip irrigation and underground pipe drainage.

Improvement Effects of Different Environmental Materials on Coastal Saline-Alkali Soil in Yellow River Delta

Based on the characters of coastal saline-alkali soil in Yellow River Delta, four kinds of soil with the total salt content of 0.13%, 0.24%, 0.86%, 2.07% respectively, were used as the research objects in this study. Leaching experiment of soil improvement were operated by using flue gas desulfurization gypsum and humic acid as the soil amendments through single or combined application. After leaching, the pH values, EC and the total salt content including Na+, Ca2+ and Mg2+ of four times leachate were analyzed. Meanwhile, the sodium adsorption ratio (SAR) was also calculated in order to evaluate the amendment efficiency. The results showed that: the pH values of the leachate of flue gas desulfurization gypsum without (treat A) or with humic acid (treat C) were significantly lower than that of control group (treatment CK) and humic acid (treatment B), while the EC values were significantly higher. For the saline-alkali soil, all of treatment A, B and C could decrease soil pH, exchangeable Na+ and soil SAR. Treatment B could decrease the total salt content insignificantly, while treatment A and C could increase the total salt content significantly. By analyzing the results, it was found that treatment C had the most significant improvement effect, comparing with the treatment CK. PH was decreased respectively 0.26%, 0.83%, 1.05% and 1.83%, Na+ was decreased respectively 82.4%, 92.6%, 89.1% and 78.6%, SAR was decreased respectively 97.4%, 98.5%, 97.7% and 94.7%. The experimental results demonstrate that a combined application of flue gas desulfurization gypsum and humic acid is a potential method to improve coastal saline alkali soil in Yellow River Delta on the basis of ensuring the irrigation amount.