ESP Outlet Research Articles

Demonstration and application of heterogeneous agglomeration technology in a 350 MW coal-fired power plant: Removal of particulate matter and trace elements

For a domestic 350 MW coal-fired power plant, the effect of heterogeneous agglomeration technology on the migration and emission of three trace elements of arsenic, selenium and lead in tail flue gas was studied. The results show that heterogeneous agglomeration technology can promote the attachment of gaseous harmful trace elements to particulate matter effectively. The reduction rates of gaseous As, Se and Pb concentrations at the ESP outlet were 24.10%, 61.08%, and 70.38%, respectively. Under the synergistic effect of ESP, more As, Se, and Pb are enriched in fly ash, and the concentration of As, Se, and Pb in fine particles below 10 μm at the ESP outlet is reduced by 54.48%, 56.47%, and 75.17%, respectively. In addition, after spraying the agglomerating agent, the final As, Se, and Pb concentrations in the atmosphere were 1.29 μg/m3, 2.01 μg/m3, and 1.12 μg/m3, which were far lower than those of the relevant EPA emission limits.

Experimental investigation of removal of flue gas emissions exhaust from municipal solid waste incinerator using photovoltaic-based electrostatic precipitator.

For the past decades, the flue gas emitted from municipal solid waste incinerator, power plant, and various industries is a permanent problem for the environment and has been affecting human life. Many flue gas filtration devices have been emerging out over the years. Although the electrostatic precipitator was an appropriate device due to high filtration efficiency and little pressure drop and energy efficiency, the cost and design of the electrostatic precipitator is a major restriction for manufacturers and end-users. With recent advances in technology, designing a cost-effective and less complex electrostatic precipitator has become mandatory. This article aims to design and develop a solar-powered cost-effective needle-plate type electrostatic precipitator which includes a static power converters and high-voltage transformer-rectifier (T-R) set with an input voltage as 230V AC, output voltage as 80-kV direct current (DC), and output current of 40mA for mitigation of flue gas emissions exhaust from municipal solid waste incinerator. The analysis of flue gas at ESP inlet and outlet has been performed using Ecotech stack sampler and flue gas analyzer. The obtained experimental results are validated with emission standards provided in the Solid Waste Management rules book, India, 2016.

A novel criterion based on slip ratio to assess the flow behavior of W/O emulsions within centrifugal pumps

Water-in-oil emulsions usually present complex rheological behavior that depends on the physicochemical properties of both phases, the presence of surfactants, and the flow conditions. Thereby, this paper aims to propose a criterion to characterize the rheological behavior of stable and unstable water-in-oil emulsions within the centrifugal pumps. This criterion is based on the slip ratio between the dispersed and continuous phases. For this, the droplet size distribution was measured at the ESP outlet and the slip ratio was estimated based on the centrifugal buoyancy-induced flow. A new model was proposed to determine the Sauter mean diameter for different systems of the water-in-oil emulsion flows within the ESP based on operational conditions, which presents good agreement with the experimental data (12.6% of error). Finally, a new dimensionless number parameter named Slip Relevance number was proposed to separate the different emulsion flow behaviors within the ESP and its critical value was obtained.

Promoting the removal of fine particles by turbulent agglomeration with the coupling of different-scale vortexes

To improve the particle agglomeration and removal effect by turbulent agglomeration, the coupling of different-scale vortexes in turbulent flow field was proposed and a turbulent agglomerator containing different types of vortex sheets was constructed and applied. The particle agglomeration efficiency, size distribution and removal effect by ESP through it were investigated experimentally. The results demonstrated that the coupling of different-scale vortexes in turbulent flow field can further promote the agglomeration and removal of fine particles. The particle agglomeration efficiency was improved and the particle number and mass concentrations at the outlet of ESP were reduced. Besides, to explore the coupling promotion mechanism, the flow field distribution, as well as the particle motion trajectory, residence time and fluctuation range in y-axis direction in three turbulent agglomerators were simulated using CFD method, and a turbulent agglomeration model for fine particles with different sizes was put forward.

The Physicochemical Properties and the Fate of Fly Ash along the Air Pollution Control Devices in Coal-Fired Power Plant

The fly ash at the exit of inlet and outlet of No.2 ESP and outlet of No.2 FGD in San-he Power Plant were sampled. The microstructure, elemental composition, particle size distribution and other physicochemical properties of the collected ash samples were tested and analyzed by a scanning electron microscope (SEM), X-ray energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and Mastersizer2000 laser particle size analyzer. The results showed that, ESP outlet fly ash particle size distribution curve was significantly moved to the left, the proportion of the fine ash at the outlet was significantly increased compared with that of at the inlet, the morphology and composition of ash at the outlet of ESP, FGD was significantly changed compared to the ash at the inlet of ESP, indicating that air pollution control equipment (APCDs) have a great impact on physicochemical properties and the fate of fly ash.

Test and Research for Mercury Emission of Boilers in 700 MW Units

In this paper, the conversion process and the existing forms of mercury in the course of coal firing are first analyzed, and different methods to measure mercury are introduced; To assess the mercury emission levels of boilers in large power plants, through testing the mercury content in combustion products of the boiler in 700 MW unit under different loads in one power plant of Jiangxi Province, we analyzed the formation distribution of mercury emissions and the effect of low temperature economizer on the mercury concentration before and after the ESP, and acquired the mercury emission characteristics of 700 MW boiler. In study, we found that mercury in the coal burnt in 700 MW boiler was mainly discharged in the form of gas, with a small amount existing in burnt solids. The change of gaseous mercury before and after the ESP is not obvious, but the concentration of bivalent mercury is higher than that of zero-valent mercury; and more than 90% of the particulate mercury is removed. The low temperature economizer in operation can obviously reduce the concentration of mercury in flue gas at the ESP outlet by 30.8%.

Numerical Simulation of Flow Filed in ESP Outlet with Moving Electrode Type

The numerical simulation of 2-D flow filed in ESP with Moving Electrode Type was carried out, in which a 2-equation model was adopted to simulate the flow field and the computation based on the SIMPLE algorithm and the geometric model was meshed with GAMBIT. The numerical simulation of flow field with FLUENT came to the conclusion that the air flow distribution in the electro static precipitator will change when the opening ratio of the electrodes and the air flow velocity in operation have changed, so the result of numerical simulation was reasonable for the design and operation of the ESP with Moving Electrode Type.

Composition and size distribution of particules emissions from a coal-fired power plant in India

Particulate matter in fly ash from ESP inlet and outlet of a coal fired power plant in India was measured for five units of 120MW and 210MW of the power plant. Samples of the pulverised coal and bottom and fly ashes were also collected. The size distribution and chemical composition of particulate matter were determined using a laser particle analyser, an ion chromatograph (IC) and an inductively coupled plasma-atomic emission spectrometer (ICP-AES). The observed particle mass concentration at the ESP inlet was 5443–21483mgNm−3 whereas the outlet concentration was found as 12–315mgNm−3 thereby giving total removal efficiency of 95.7–99.8%. A fine particle mode appeared at the particle size of 0.4–0.9μm and coarse particle mode appeared at the particle size greater than 1μm. Magnesium and iron remained in bottom ash and showed high concentrations 99 and 2154μgg−1 (ppmw) respectively, while other elements such as lead, chromium and zinc were observed in higher concentration in ESP inlet flue gas. Relative enrichment of trace elements (except Fe) in fly ash was observed higher than that in bottom ash.

Particle precipitation efficiency in an electrostatic precipitator

In this paper, results of the measurements of the size distribution of seed particles after their precipitation in a wire-plate-type ESP with seven wire electrodes are presented. The cigarette smoke was used as a source of seed particles. The particles of sizes from 0.5 to 8 μm were counted in the 0.5 μm-wide ranges at the ESP outlet using a particle size-meter of the laser light reflection type. The particle precipitation efficiency for each size fraction was determined for various primary flow velocities at positive and negative voltage polarity. Due to the size-meter measuring range limited to the particles larger than 0.5 μm, the present measurements do not show the precipitation of the particles of sizes smaller than 0.5 μm.

Influence of the elemental composition of individual fly ash particles on the efficiency of the electrostatic precipitators

The Oxford Scanning Proton Microprobe has been used to determine the elemental composition of individual fly ash particles in the 1–5 μm geometrical size range, collected before and after a pilot electrostatic precipitator (3 MWe equivalent power) of a power plant burning South African coal (Amcoal). The electrostatic precipitator was working at high collection efficiency (99.8%) obtained by operating under semi-pulsed energization mode. Al, Si, P, S, K, Ca, Ti, Cr, Mn, Fe, Ni, Cu, Zn, Ga and Sr have been always detected in particles collected simultaneously both before and after the electrostatic precipitator. In some particles also V, Ge, As and Zr resulted above the detection limits. Both at the ESP inlet and outlet one hundred particles have been analysed. According to major element concentrations, particles can be grouped into seven classes showing some preferential associations of minor and trace elements with specific matrix compositions. Most particles (about 80%) belong to classes 1 and 2 characterized by the same aluminosilicate nature with higher concentrations of several minor (P, Ca, Ti, Fe) and trace (S, Mn, Ni, Zn, Ga) elements in class 2. Within the same particle size range, the electrostatic precipitator seems to be selective with respect to particle composition: class 2 particles show a higher penetration. This result is discussed in terms of the particle composition effects on the fly ash electrical properties, which are relevant parameters for the electrostatic precipitation process.