Experimental Investigation of the Ash Deposition Characteristics of Biomass Pretreated by Ash Removal during Co-Combustion with Sub-Bituminous Coal

Although replacing biomass, (e.g., wood chips and pellets), with thinning wood and herbaceous biomass is eco-friendly and economically advantageous, their direct utilization in plant boilers is associated with ash-related challenges, including slagging and fouling. The aim of this study is to determine the effects of ash removal treatment (ashless biomass (ALB)) in the context of solid fuel power plant boilers. Ash was removed via neutralization of metal ions and carboxylic acids contained in the biomass ash. The ash removal rate of K, Na, Cl was indicated by assessing the total biomass before and after ash removal treatment, via XRF analysis. Co-combustion with sub-bituminous coal and ALB-treated biomass was analyzed using a drop tube furnace and revealed that NOx and SOx values converged converge toward an approximate 10 ppm error, whereas the Unburned Carbon (UBC) data did not exhibit a specific trend. Factors associated with slagging and fouling, (capture efficiency (CE), and energy based growth rate (GRE)) were calculated. All biomass samples without pretreatment exhibited V-shaped variation. Conversely, for ashless biomass (ALB) samples, CE and GRE gradually decreased. Thus, the ALB technique may minimize slagging and fouling in a boiler, thus, reducing internal corrosion associated with ash deposition and enhancing the economic operation of boilers.

New Ash and Sulfur Dioxide Emission Limit Levels for Large Combustion Plants and Best Available Techniques of Stack Gases Treatment

In order to determine new technological parameters for reviewing ITS 38-2017, the authors analyse coal properties and techniques for sulphur and ash removal from the stack gases. The technologies of ash purification and desulphurization of gases are analyzed and recommendations for their effective use are given. New technological emission parameters for ITS 38-2017 review proposed and recommendations provided for expanding the list of the Best Available Techniques to be implemented at Russian large combustion plants.

Effect of Diesel Oil and Mixture of Alcohol-Glycol Ether on Colombian Ultrafine Coal Cleaning Using a Test-Rig Closed-Loop Flotation Column

A test-rig closed-loop flotation column was used to observe the effect of diesel oil (collector) and Flomin F-425 (frother) on mass yield and ash content for two Colombian coals: Caypa (northern zone) and Guachinte (southwestern zone). The coal samples of less than 38 µm (-400 M) were processed in a collector concentration range of 0,32 to 1,60 kg/ton of coal, as well as a frother concentration range of 10 to 50 ppm. The response surface methodology was used for the experimental test runs. The results showed that the maximum mass yield obtained by Caypa coal was 98,39% at 1,28 kg of collector/ton of coal and 40 ppm of frother concentration, whereas Guachinte coal obtained a maximum mass yield of 94,71% at 0,96 kg of collector/ton of coal and 30 ppm of frother concentration. In general, for Caypa coal, the mass yield tends to increase (low ash removal) with the collector and frother concentration increase; while the mass yield tends to decrease (high ash removal) for Guachinte coal when the collector concentration increases (low ash removal) at high frother concentrations. It is worth highlighting that the ash content of 0,65% obtained for Caypa coal is the lowest value reported in the literature while employing a test-rig loop flotation column in a single stage, which is considered to be an ultra-clean coal obtained by a physical cleaning process.

USE OF ASSEMBLY ASH IN THE COMPOSITION OF SOIL CEMENT

Іn this work, we searched for the optimal composition of soil cement containing different percentage of ash removal: from minor additives to the replacement of half the soil mass for ash. The search for the optimal composition was performed on the basis of experimental studies to determine the physical and mechanical characteristics.The use of soil cement with the addition of fly ash is proposed for the reinforcement of the bases by vertical reinforcing elements. In order to develop practical recommendations on the optimal composition of soil cement, a mathematical simulation of the work of reinforced soil cement fields was performed with the variation of the physical and mechanical characteristics of piles, depending on the ash content of the ash. . Plaxis software was used for numerical simulation. With a steady step of reinforcing elements, the properties of the soil-cement mass were studied, depending on the deformability of the piles.

The Use of Reftinskaya State District Power Plant Fly Ash in the Production of Building Materials and Products

The system of dry ash–slag removal at the Reftinskaya state district power plant which provides capture, storage and shipment of fly ash to the consumers is considered in this study. The results of determination of chemical and phase composition, physical properties, melting temperature and activity of natural radionuclides of ash which is form during burning of stone coal of Ekibastuz basin are presented. Ash is acidic, superfine and refractory one with a low content of combustible substance. As to composition and properties it satisfies the requirements of Russian Standard no. 25818 and ships to consumers under Technical Conditions 5717–004–79935691–2009. The results of laboratory tests and industrial production of building materials and products on the basis of ash of Reftinskaya state district power plant are presented. It is shown that ash is used in the production of Portland cement, heavy and cellular autoclave concrete, dry mixes and can also be used as part of fly ash non-fired and agloporite gravel, ceramic bricks. The features of their production, basic physical and mechanical properties of building materials and products are described. It is shown that the introduction of a new system of dry ash removal at the state district power plant contributes to the expansion of directions and increase in the volume of ash recycling. Keywords: Reftinskaya state district power plant, dry ash removal, fly ash, composition, properties, use, construction materials and products

Experimental constraints on volcanic ash generation and clast morphometrics in pyroclastic density currents and granular flows

Pyroclastic density currents (PDCs) are a prominent hazard of volcanic activity; however, fully quantitative observations are lacking and little direct evidence exists to constrain the parameters controlling ash production and runout. Here, we use rotary tumbling experiments to investigate ash generation efficiency and clast morphometrics in the dense basal flow of PDCs. We observe greater ash generation with periodic ash removal and with higher starting mass. By scaling to the bed height and clast diameter we obtain a general description for ash production in all experiments as a function of flow distance that we parameterise in dimensionless space. We also show that ash production correlates with clast shape changes and with the Inertial number for our experiments. This work introduces some of the first systematic and generalizable experimental parameterizations of ash production and clast evolution in PDCs and should advance the ability to understand flow mobility and associated hazards.