Manindra Nath Biswas

Modeling of a novel multi-stage bubble column scrubber for flue gas desulfurization

Abstract Desulfurization of flue gases from various chemical industries in a techno-econo-enviro manner is a demanding technology. The concentrations of sulfur dioxide in and around these plants overshoot the danger point. In the present investigation, an attempt has been made for wet flue gas desulfurization using water as the absorbing medium in a newly developed scrubber. Prediction of SO 2 removal efficiency is very important for selection of pollution control equipment. The present paper reports on both the modeling and detailed experimental investigations on the scrubbing of SO 2 in the modified multi-stage bubble column scrubber (MMSBCS) using water. Experimental results show that almost 100% removal efficiency of SO 2 , can be achieved in the present system without additives or pre-treatment. A comparison has been made between the predicted and experimental percentage removal efficiency of SO 2 . Experimental results are in excellent agreement with the predicted values from the model.

Fly-ash removal efficiency in a modified multi-stage bubble column scrubber

Bubble columns are being widely used in chemical process industries for its various advantages and simplicity. A pilot plant novel multi-stage bubble column wet scrubber has been conceived, designed and fabricated. This novel scrubber has been used as dust collecting wet scrubber in presence of other gaseous and vapor pollutants. This paper reports on the detailed experimental investigations carried out on the scrubbing of fly-ash in this novel wet scrubber using water as the scrubbing medium. It has been found that the present system yielded very high efficiency for the scrubbing of fly-ash. In most cases, the fly-ash removal efficiency is more than 95% and many cases approaches 99.5%. A correlation has been developed for prediction of particulate (fly-ash) removal efficiency. The scale-up of this pilot plant in Indian thermal power plant shows excellent performance and meets the stringent pollution control standards. Attempt has also been made to install the above wet scrubber in Indian Thermal Power Plants and Ceramic Industries to combat particulate pollution control and found excellent performance.

Non-newtonian liquid flow in bends

Abstract Experimental data on the pressure drop across different types of bend in the horizontal plane, for non-newtonian pseudoplastic fluid in laminar flow, h

SO2 SCRUBBING IN A TAPERED BUBBLE COLUMN SCRUBBER

SO2 emissions from various sources are found to occur in various concentrations and quantities. Abatement of SO2 emission, therefore, assumes significant importance over the decades. Wet scrubbers offer great advantage over other devices for gas cleaning. That is the reason that compliance with SO2 standards will in many cases result in the installation of scrubbing devices. This article presents results of a study on the scrubbing of SO2 (initial concentration ranging between 400 and 1780 ppm) in a tapered bubble column scrubber using water and dilute sodium alkali. Preliminary studies reveal that the tapered bubble column is capable of generating higher fractional gas holdup than a standard bubble column under similar situations. Moreover, the tapered bubble column has generated bubbles with less power consumption than the existing columns under comparable hydrodynamical conditions. Experimental results indicate that almost 100% SO2 removal (i.e., zero penetration) can be achieved in the scrubber developed in alkali scrubbing at an optimum QL/QG ratio of 3.0 m3/1000 ACM. The selection of any gas-cleaning device is based on the performance of the system. In view of this, empirical and semi-empirical correlations are put forward for the prediction of the performance of the scrubber in terms of different pertinent variables of the system for water as well as alkali scrubbing. Experimental results fit extremely well with the correlations. The removal efficiency achievable in the present tapered bubble column scrubber has been found to be higher than that of a single-stage standard bubble column with some modification. The present tapered bubble column is, therefore, hydrodynamically, energetically, and efficiency-wise much better than a standard bubble column.

A NOVEL MODIFIED MULTI-STAGE BUBBLE COLUMN SCRUBBER FOR SO2 REMOVAL FROM INDUSTRIAL OFF GASES

The emission of SO2 from various chemical industries, always occur in association with particulate and most of the time the concentrations of sulfur dioxide in and around these plants overshoot the danger point. In the present investigation, an attempt has been made for wet flue gas de-sulfurization using water as the absorbing medium in a newly designed scrubber. Prediction of SO2 removal efficiency is very important for selection of a pollution control equipment. The present paper reports on the detailed experimental investigations on the scrubbing of SO2 in the modified multi-stage bubble column scrubber (MMSBCS) using water. Experimental results show that almost 100% removal efficiency of SO2, can be achieved in the present system. A correlation has been developed for predicting the percentage removal efficiency of sulfur dioxide. Experimental results are in excellent agreement with the correlation. *Patent pending.

Separation of oil-water mixture in tank

Experimental investigations have been carried out to separate diesel oil-water mixture in unbaffled, baffled (with different inclination of baffle), and variable area baffled separators. A baffle separator with a 45° inclination to vertical has been found to be most suitable for the oil-water separation.

PRESSURE LOSSES IN TWO-PHASE GAS-NON-NEWTONIAN LIQUID FLOW IN A VERTICAL TUBE

Experimental data on pressure drop for two-phase gas-non-Newtonian ps:udoplastic liquid vertical slug flow have been analysed. Correlation have been proposed for predicting the two-phase friction factor as a function of the physical and dynamic variables of the system.

Utilization of Arachis hypogaea hull, an agricultural waste for the production of activated carbons to remove phenol from aqueous solutions

Arachis hypogaea hulls, an agricultural waste, were used to prepare activated carbon by chemical activation with zinc chloride under four different activation atmospheres. The most important parameter in chemical activation was found to be the chemical ratio (activating agent/precursor). Carbonization temperature and time are the other two important variables, which had significant effect on the pore structure of carbon. The maximum Brunquer-Emmett-Teller (BET) surface area and micropore volume of the activated carbon was found to be 418 m2/g and 0.28 cm3/g, respectively. The activated carbon developed shows substantial capability to adsorb phenol from aqueous solutions. The kinetic data were fitted to the models of intraparticle diffusion, pseudo-second-order, and Lagergren, and followed more closely the pseudo-second-order chemisorption model. The isotherm equilibrium data were well fitted by the Langmuir and Freundlich models. Solution pH has significant effect on adsorption and the maximum uptake of phenol was reported at pH 3.5.

Spray scrubbing of particulate–laden SO2 using a critical flow atomizer

The performance of a spray tower using an energy efficient two-phase critical flow atomizer on the scrubbing of particulate-laden SO2 using water and dilute NaOH is reported in this article. Experimentation revealed that SO2 removal was enhanced due to presence of particles (fly-ash) and almost 100% removal efficiency was achieved in water scrubbing. The removal efficiency is elucidated in reference to atomizing air pressure, droplet diameter and droplet velocity besides other pertinent variables of the system studied. The presence of fly-ash particles improved the removal efficiency to about 20% within the range of variables studied. Empirical and semi-empirical correlations were developed for predicting the removal efficiency in water and dilute NaOH respectively. Predicted data fitted excellently well with experimental values. The performance of the spray tower is compared with the performances of existing systems and very encouraging results are obtained.

PREDICTION OF ENERGY DISSIPATION IN A CONVERGENT-DIVERGENT MULTISTAGE BUBBLE COLUMN

An experimental investigation was carried out to evaluate energy dissipation of a divergent-convergent multistage bubble column (with convergent and divergent disks), which has been conceived, designed, and fabricated as a wet scrubber for air pollution control. In addition it has versatile use as a gas-liquid contactor in chemical and biochemical process industries. A detailed experimental investigation of pressure drop and energy dissipation has been reported by using a divergent-convergent multistage bubble column. Correlation developed for predicting energy dissipation has been found to be encouraging and highly significant from a statistical point of view. Energy consumption of the present system has been compared with other systems.