Optimizing the structure of a dust concentration measuring device

The particle movement speed in the pipe of an existing dust measuring device is too small, and the detection in the center area of the pipe is not sufficiently sensitive. According to the intake mode of the cyclone separator, here a new side inlet pipeline is designed that is oriented from the incident mode of the straight pipe. An experimental model was established in Gambit2.4, and the numerical simulation was performed in Fluent6.3. Different dust particle diameters were simulated, and velocity cloud and pressure cloud diagrams of the middle position of the device pipe were obtained. Compared with the velocity data of the straight tube and the side tube, the velocity value of the particle passing through the side tube was better than that of the straight tube. This improved the velocity of the particles and also reduced the settling of the particles. The probability of friction collision of the dust particles in the tube increased, meaning that their induced charge also increased. MATLAB was used to calculate the electrostatic induction, revealing that the charge of the particles in the improved device increased significantly. Therefore, the improved device can effectively improve the measurement accuracy of dust at low concentrations, and for small particle sizes.

Analisa korosi pada heat exchanger e-4512 pt.arun ngl co

Heat Exchanger E-4512 adalah salah satu alat penukar panas yang digunakan pada PT. Arun yang digunakan untuk mendinginkan atau menurunkan temperature MCR (multi component refrigerant) dengan media pendingin air laut. Pada heat Exchanger E-4512 ini terjadi kerusakan yaitu korosi terutama pada bagian-bagian seperti tube side, tube sheet, channel dan channel cover. Jenis korosi yang menyerang yaitu korosi sumur (pitting corrosion). Korosi erosi (erosion corrosion) dan korosi galvanis (galvani corrosion). Kerusakan ini akan berkaibat fatal mengingat fungsi dari Heat Exchanger merupakan pendukung utama proses produksi. Makalah ini menganalisa penyebab terjadinya korosi dan membahas hal-hal yang dapat dilakukan untuk mencegah terjadinya korosi berdasarkan kasus di lapangan dan kajian teoritis.

Effect of Moisture Content on Mixing Air With Water-Liquid Flowing Through Inverted U-Tube for Power Plant Condenser Applications

Computational Fluid Dynamics (CFD) for air/water-vapor and water-liquid two-phase flow mixing with condensation in a vertical inverted U-tube is presented in this paper. This study is to investigate the flow behaviors and underlying some physical mechanisms encountered in air/water-vapor and water-liquid mixing flow when condensation is considered. Water-liquid flows upward-downward through the inverted U-tube while the air/water-vapor mixture is extracted from a side-tube just after the flow oriented downward. The CFD simulation is carried out for a side air/water-vapor mixture volume fraction (αm) of 0.2–0.7, water-vapor mass fraction (Xv) of 0.1–0.5 in the side air/water-vapor mixture and water-liquid mass flowrate (mw) of 2,4,6, and 8 kg/s. The present results reveal that, at lower air mass flow rate, no significant effect of Xv on the generated static pressure at the inverted U-tube higher part. However, by increasing the air mass flow rates, ma ≥ 0.001 at mw = 2 kg/s, and ma ≥ 0.00125 at mw = 4 kg/s, we can infer that the lowest static pressure can be attained at Xv = 0.1. This may be attributed to the increased vapor and air mass flow rates from the side tube which results in shifting the condensation from the tube highest part due to air accumulation. This leads to increasing the flow pressure and decelerating the water-liquid flow. Raising mw from 2 to 4 kg/s at the same vapor mass ratio results in a lower static pressure due to more condensation of water vapor. The turbulent intensity and kinetic energy starts to drop approximately at ma = 0.002 kg/s, and αm = 0.55–0.76 at mw = 2 kg/s for all Xv values but no noticeable change at mw = 4 kg/s occurs. These findings estimate the operational values of air and water mass flow rates for stable air entrainment from the side-tube. Increasing the air and vapor mass ratio over these values may block the evacuation process and fails the system continuance. Likewise more air entrainment from the side-tube will decelerate the water flow through the inverted U-tube and hence the flow velocity will decrease thereafter. Moreover, this study reveals that the inverted U-tube is able to generate a vacuum pressure down to 55.104 kPa for the present model when vapor condensation is considered. This generated low-pressure helps to vent an engineering system from the non-condensable gases and water vapor that fail its function if these are accumulated with time. Moreover, the water-liquid mass flow rate in the inverted U-tube can be used to sustain the required operating pressure for this system and extract the non-condensable gases with a less energy consuming system. The present CFD model provides a good physical understanding of the flow behavior for air/water-vapor and water-liquid flow for possible future application in the steam power plant.

Diagnostic Method Research on the Dirty Level of the Water Side Tube and the Tightness of Vacuum System of Condenser

The condenser vacuum influences the steam turbine’s safety and economy. The dirty level of the water side tube and the air accumulation of the steam side affect overall heat transfer coefficient .That make the condenser vacuum low and terminal temperature difference increase. It is a generally interested problem that making a distinction between fouling loss and air accumulation loss for the operating personnel and maintenance person. In this article, we judged the vacuum system work normal or not by comprehensive cleaning curve, and further calculation and curve analysis were done so as to distinguish the affection of the dirty level of the water side tube and the air accumulation of the steam side to overall heat transfer coefficient and terminal temperature difference.

A Partial Dialysate Collection Method

This study validates Ing's partial dialysate collection method, which employs proportionate collection using a side tube capped with a small-gauge plastic needle. The urea nitrogen and creatinine levels of the small representative fraction of spent dialysate collected in the above fashion are undistinguishable from those obtained from the total spent dialysate. The estimated urea nitrogen removed during hemodialysis using this approach is similar to that using the total dialysate collection method; Ing's method is simple and useful in quantifying the dialysis dosage and in its assessment of the nutritional status of patients on hemodialysis.