Showing papers by "Wen Nie published in 2021"

The control effect of 3D spiral wind-curtain generator on respirable dust pollution during tunnelling process.

Abstract: The respirable dust pollution produced in the cutting process of tunnelling machine during tunnelling process is a serious threat to the health of workers. The key to solve this problem is to build an effective ventilation system in the tunnel. In this paper, experiments were designed and implemented to obtain the temporal–spatial evolution of respirable dust pollution before and after the 3D spiral wind-curtain generator was used for tunnel auxiliary ventilation, and the CFD method was used to supplement and visualize the experimental results. Before the 3D spiral wind-curtain generator was used, the respirable dust gradually diffused from the cutting face to other spaces of the tunnel, and finally presented a stable state with time. After using the 3D spiral wind-curtain generator for auxiliary ventilation, the dust diffusion speed in the tunnel was slower than before, and the dust concentration was lower than before. When adjusting the position of the generator and installing it 20m away from the cutting face, an effective dust control wind-curtain formed within the range of 3.5 ~ 6.5m away from the cutting face. With the increase of time, the dust is stably controlled within the space of 4.5m away from the cutting face, and then pumped away by the exhaust fan, so as to purify the tunnel environment and ensure the tunnel’s cleanliness and safety and efficient excavation.

Performance evaluation of Mn-Ce/cordierite catalyst modified by green surfactant to remove NOx in underground mines at low temperatures

Abstract: An environment-friendly and low temperature performance catalyst is important to protect the working environment under the mine. We choose cordierite as the carrier of catalyst and modified by green surfactant to increase the specific surface area and catalytic activity, which also provides environmental protection for the catalyst. The most suitable surfactant is selected based on its saturated adsorption curve, surface tension, and denitration efficiency. Analyze the adsorption process of surfactant molecules on cordierite surface and the micro mechanism of improving the removal rate of NOx. In order to improve the NOx removal rate to a step further, the surfactant is used as a coating to prepare a new Mn-Ce/surfactant-cordierite monolithic catalyst, which is characterized by Fourier transform infrared spectroscopy, energy-dispersive x-ray spectroscopy, X-ray diffraction, and H2 temperature programmed reduction. Its selective catalytic reduction and denitration activity are studied. Experimental results: (1)Green surfactants can effectively improve the conversion efficiency of cordierite for NOx.(2)Among the four surfactants, cetyltrimethyl ammonium bromide (CTAB) can most significantly improve the conversion efficiency of NOx and its optimum concentration is 0.04%.(3)The NOx removal efficiency of the new Mn-Ce/CTAB-cordierite monolithic catalyst can reach 95% at 150 ℃.

Onboard air curtain dust removal method for longwall mining: Environmental pollution prevention

Abstract: Owing to the increasing production capacity of longwall mines, dust pollution has become more severe, in particular, in the working area of the shearer driver. Thus, it is urgent to improve the environment of longwall mines. A new onboard air curtain dust control method is proposed, which adopts the idea of partial closed dust control. The improved Euler-Lagrange model is conducted to simulation the dust diffusion characteristics with and without air curtain. The results show that two high-speed air curtains form on both sides of the working area of the shearer driver after the application of this control method. These air curtains can isolate the dust and reduce the dust concentration in the working area of the shearer driver by 69.40%. Simultaneously, the dust concentrations in most areas of the longwall mining section are reduced. Therefore, this paper presents a new, useful method for dust prevention at a longwall mining section.

Effects of press-in airflow rate and the distance between the pressure duct and the side wall on ventilation dust suppression performance in an excavating tunnel

Abstract: The efficiency of mine excavation has been significantly enhanced by continuing improvements in tunneling capabilities; however, this has also resulted in serious environmental pollution and greater safety risks for workers. To ensure safe production, the focus of this study is on the effect of varying the air pressure and the distance between the air pressure cylinder and the side wall settings on dust dispersion behavior and dust control in excavated tunnels. We also investigated temporal-spatial dust diffusion rules in tunnels by combining numerical simulation data with field measurement results. Through further analysis, when the pressure air volume and the exhaust air volume are both equal to 250 m3/min, the dust diffusion distance could be fitted as: $${L}_{t}=-4E-09{t}^{6}+1E-06{t}^{5}-0.0002{t}^{4}+0.0107{t}^{3}-0.3219{t}^{2}+5.018t-2.535$$ . When the exhaust air volume is equal to 250 m3/min, dust control effects were improved as the pressure air volume decreased, becoming optimal when the pressure air volume dropped to 150 m3/min. Under these conditions, areas of high dust pollution were contained within 16 m of the cutting face, and the dust diffusion distance satisfied the formula: $${L}_{s}=2E-06{q}^{3}+0.001{q}^{2}-0.0413q+5.0286$$ . When the pressure air volume is fixed, the change of the distance between the pressure air cylinder and the side wall has little effect on the dust diffusion. When the distance is 1.5 m, the dust control effect is the best, and the high dust pollution area is controlled within 14 m of the cutting surface. This alleviated dust pollution to a certain degree, thereby enhancing the air quality and ensuring safer production. This study provides a new understanding of the environmentally sustainable development of tunnels and is of great significance for clean production.

Absorption-induction convectional dust-controlling/removing air/fog curtain device of fully-mechanized working face and method thereof

Abstract: Disclosed are an absorption-induction convectional dust-controlling/removing air/fog curtain device of a fully-mechanized working face and a method thereof, belonging to the technical field of dust removal of coal mine. The device includes an extraction type dust-purifying blower, a sector deflector, a shearer external spraying device and an inter-hydraulic-support spraying device, wherein the shearer external spraying devices are mounted at both sides of a body of a shearer close to rocking arms of the shearer and the inter-hydraulic-support spraying devices are mounted at two un-advanced hydraulic supports and two hydraulic supports at a leeward side of a front drum of the shearer respectively, so that spraying is performed at a certain angle to form corresponding fog curtains so as to perform spraying precipitation for a large amount of dusts produced by support advancing and coal cutting. Two extraction type dust-purifying blowers symmetrically mounted at the body of the shearer close to the rocking arms are started simultaneously, air inlets of two blowers directly face front and rear drums of the shearer respectively, and air outlets of two blowers are connected with the sector deflector. The device and the method of the present disclosure are of great practical significance for improving a working environment of workers working at the fully-mechanized working face and ensuring safe production of coal mine.