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Aiming at the problems of pressure - bearing pipes thinning and even rupture caused by the high temperature corrosion of the biomass boiler superheaters, the microstructure and properties of superheater tube wall after service were analyzed based on working environment. Research results showed that elements such as Cl and alkali metals in the flue gas underwent a series of complex physical and chemical reactions with the heating surface in the form of gas, solid and liquid phases at high temperatures, resulting in the corrosion of the superheaters pipe wall. The fly ash was deposited on the metal surface and soakably adhered to the oxide layer, which made the oxide protective layer on the pipe wall surface fell off, leading to the thinning of the pipe wall. Meanwhile, the service temperature of the high temperature superheaters was higher than that of the medium temperature superheater, and the corrosive peeling of its oxide layer was more serious. After long - term service, the micro hardness and tensile property of the pipe wall of the high temperature superheater after corrosion was decreased, compared with that of the medium temperature superheater. But, both of them still met the standard requirements and service conditions. Therefore, taking appropriate protective measures was able to prevent further corrosion and thinning of the pipe wall, which could shorten the maintenance period and reduce operating costs.

The MS 6.9 Menyuan earthquake on January 8, 2022 occurred in the Qilian Mountain fault block in the northeastern margin of the Tibetan Plateau. The instrumental epicenter is located in the Lenglongling fault zone in the west section of the Haiyuan active fault system. It is another strong earthquake with M>6.5 that occurred in the fault system after the Haiyuan M 8.5 earthquake in 1920. The preliminary conclusion of the investigation results shows that the Menyuan earthquake generated two main fracture zones in the south and north separately, which are distributed in left-step oblique arrangement with a total length of nearly 23 km, and there is a surface rupture cavity with a length of about 3.2 km and a width of nearly 2 km between them. The south branch rupture (F1) appears in the east section of the Tuolaishan fault, striking 91°, with a length of about 2.4 km. It is mainly characterized by southward thrust and sinistral strike slip, with a maximum horizontal displacement of nearly 0.4 m. The north branch main rupture (F2) appears in the west section of the Lenglongling fault, with a total length of nearly 20 km. It is mainly sinistral strike-slip deformation, and presents an overall slightly convex arc distribution to the northeast, including the west, middle and east sections of 102°, 109° and 118°, respectively. The maximum strike-slip displacement occurs in the middle section, which is 3.0±0.2 m. In addition, a new north branch secondary fault (F3) with a cumulative length of about 7.6 km, dominated by normal-dextral fault, is discovered on the north side of the middle to east section of the main fault of the north branch, with a cumulative maximum horizontal displacement of about 0.8 m and a maximum normal vertical displacement of about 1.5 m. Comprehensively, the whole coseismic rupture is mainly sinistral strike-slip and has the characteristics of bilateral rupture, whereas the macroscopic epicenter is located in the north branch of midway through the main fracture zone, thus the strike-slip displacement of the surface may be associated with the shallow rupture of the source. The normal-dextral rupture is likely to be caused by the differential movement of the north block dragged by the active south plate. The south Qilian block was extruded eastward along the Haiyuan sinistral strike-slip fault system due to the strong collision and compression between the Indian and Eurasian plates, which led to the simultaneous rupture of the Tuolaishan fault and the Lenglongling fault. This is the main dynamic mechanism leading to the strong earthquake. Under the background of continental dynamics, further attention should be paid to the future strong earthquake risk of the Qilian Mountain fault block and its surrounding area with the Haiyuan sinistral strike-slip fault system as the main boundary.

In order to realize low-carbon transformation in the energy industry and achieve the "double carbon" goal as scheduled, renewable energy represented by biomass has become increasingly attractive. Biomass gasification is a thermochemical treatment technology, which has seen rapid development in recent years. It is currently the most effective method for high-grade and efficient utilization of biomass energy. In this paper, the key units involved in the entrained flow gasification process, such as pulverization, transportation, and gasification were analyzed, and the feasibility of applying airflow bed technology to biomass gasification was demonstrated. Six typical agricultural and forestry biomasses were used as raw materials. Biomass entrained flow gasification simulation was carried out with the help of the Aspen Plus chemical process simulation software, and the coal and biomass co-gasification and biomass separate gasification processes were characterized. The carbon reduction effect of biomass gasification was analyzed. The results show that when a certain amount of biomass is added into coal, a good gasification performance is retained. With the increase of biomass blending ratio, the specific coal consumption gradually decreases, and the carbon reduction effect is apparent. Compared with traditional fixed bed and fluidized bed gasification, biomass entrained flow gasification has an advantageous calorific value of synthetic gas about 10 MJ/m³. It can be used as a surrogate for natural gas heating, which has economic value in achieving carbon reduction. This study is in line with the dual-carbon policy and also provides a reference for the efficient conversion and utilization of biomass. [ABSTRACT FROM AUTHOR]

In order to solve the problem of strengthening the broken roof of the coal seam under the direct cover of the caving zone, taking the 7228 working face of Xutuan Coal Mine as the engineering background, the paper proposes the ground grouting reinforcement plan, and studies its construction technology from four aspects of slurry selection, grouting technology, ground drilling technology and grouting effect evaluation. The cement coal ash slurry proportioning schemes with water cement ratio of 1∶1 and solid phase ratio of 2∶8 have been determined through the slurry static test, slurry water separation test and slurry proportioning test; the secondary structure drilling and secondary tunneling scheme have been designed in the drilling technology to ensure the quality of drilling and make the slurry reach the target layer smoothly; the roof of coal seam 72 has been exposed through surface drilling, underground geophysical exploration and underground mining, and the grouting effect is verified. Through the ground grouting reinforcement, the strength and integrity of the 72 coal seam roof have been significantly strengthened, and the engineering geological problems faced by the 7228 working face are solved, and the high-efficiency mining of 7228 working face is realized.

According to the characteristics of the low strength reinforcement of the coal mining broken roof under the direct cover of the caving zone, based on the influence of fly ash on the performance of the cement slurry, the indoor static test method was used to optimize the slurry with different cement fly ash ratios, and the optimal strength and liquidity ratio were obtained. The results showed that the compressive strength and fluidity of the slurry decreased with the decrease of solid ratio (the increase of fly ash content), while the setting time and the rate of stone increase with it. The early strength of the hardened body was low, and the later strength increased greatly. When the solid ratio was 2∶8, the physical and chemical reaction between cement and fly ash was good. The fluidity performance was good as a whole. The strength of stone body was above 1 MPa and the setting time was longer. The research results had achieved good application effect in the ground grouting reinforcement project under the direct cover of the caving zone in 7228 working face of Xutuan Mine.