The Application of an Improved Fuzzy Comprehensive Evaluation in Coal Quality Rating: The Case Study of China

Coal quality rating can help reduce greenhouse gas emissions, solving the global warming problem. It becomes more important as the carbon neutrality by the mid-21st century agreement is accepted by 195 countries, including China. In this paper, an improved fuzzy comprehensive evaluation method is introduced for coal quality rating. The data used in this work are of the Hostolgoi coalfield of the Xinjiang Province of China. Six industrial analysis indicators are determined as evaluation factors by taking the coal samples of different coal seam depths in the mining area. The super-standard multiple methods and the double-weight super-standard weighting method are combined to form a comprehensive weight. The results show that most of the coal samples of this coal mine are at grades I–II, and the overall coal is with good-quality stability. The evaluation results can improve the coal utilization efficiency and provide scientific guidance for evaluating and exploiting coal resources in coal geological exploration.

Research and Design on the Coordinate Control System of Once-through Boiler Power Unit

Taking the 1000 MW ultra supercritical unit as an object of study, The nonlinear model is builded through mechanism analysis, which is linearized based on small error, the multi-variable decoupling controller is designed to achieve full decoupling of the input and output variables, and finally the three-input-three-output coordinated control system (CCS) is established. The control system is verified by coal quality and the specific enthalpy of feed water disturbance when load changing, the simulation result shows that the improved CCS has good control performance.

Energy lost in endothermic reactions in the production of clay blocks in a continuous kiln

In Ocaña, Norte de Santander, Colombia, the production of ceramic materials is done in a traditional and empirical manner, generating heat losses, low productivity and product quality, and increased emissions of polluting gases into the environment. A virtual instrument for temperature data acquisition was developed and the firing process was monitored in two loading doors of a Hoffman kiln. 29040 blocks were produced, and 1370.76 kg of pulverized charcoal were consumed. The firing process lasted sixty-two hours and the virtual instrument was programmed to record data every 5 minutes. The energy supplied to the brick kiln was 340.16x106 kJ and the heat due to loading of the products and heat lost in the endothermic reactions of the clay was 107.71x106 kJ and 105.71x106 kJ respectively, representing 31.66% and 31.08% of the energy supplied. The results have made it possible to establish trends in the temperatures and energy consumed in the endothermic reactions in the clay. This will allow the implementation of coal quality and grinding procedures, increasing energy efficiency, and reducing gas emissions into the environment, thus avoiding acute respiratory diseases.

Advantages of underground coal gasification implementation in Indonesia

Underground Coal Gasification (UCG) is an energy manufacturing process whereby coal is gasified or chemically converted into a gas, in-situ. UCG has several benefits in terms of low capital cost, lower environmental impact, high energy density and long-term production certaint y. The objective of this study is to describe the advantages of implementing UCG technology in Indonesia based on UCG gas resources, product market, coal quality and availability of regulation to support UCG projects. UCG gas resources are estimated based on data of CBM resource and coal quality was examined by heat treatment. The size of conservatively estimated potential UCG gas manufacturing volume in Indonesia based on CBM data is 160 TCF which is greater than Indonesia’s natural gas reserves, namely 142.7 TCF. UCG gas markets are available in South Sumatera and East Kalimantan since the natural gas production in the two provinces is declining significantly. UCG in Indonesia is regulated under the mineral and coal regulatory regime, which brings some benefits, including more flexibility in the type of drilling rigs that can be used for UCG, compared to oil and gas drilling.

Preparation and Properties of a New Type of Coal Dust Suppressant

A new type of water-soluble coal dust suppressant (later called MA) with excellent performance was prepared by modified starch, styrene, methyl methacrylate, Butyl acrylate (as the main monomers) and acrylic acid (as the functional monomer) via mixed the emulsifiers of Sodium dodecyl sulfate (SDS)/octylphenol polyoxyethylene(10)ether (OP-10) and ammonium persulfate served as initiator. The properties of anti-wind erosion, water retention and coal quality impact were investigated. The MA was characterized by viscosity measurements and scanning electron microscopy. The results show that the spraying of MA has no effect on coal quality, and the water loss rate of MA is slightly lower than that of water, which has certain moisture retention. After spraying MA on the surface of coal sample for 120 hours, the coal sample is swept by six-stage wind (wind speed is 10.8-13.8 m/s), and the erosion rate is only 1.8%. The MA and coal samples are closely bonded to form a dense soft film, which has a excellent dust suppression effect.