Full-Scale Investigation of Dry Sorbent Injection for NOx Emission Control and Mercury Retention

An innovative dry SNCR method realized by a sorbent injection applied to a stoker furnace is presented. The process is based on urea powder admixed with halloysite, an aluminosilicate clay mineral. Field tests were performed at an industrial stoker hot water boiler of 30 MWth capacity. A unique nozzle design for injecting powdery sorbents into the combustion zone was implemented. The base NOx emission without SNCR was determined to be 365 mg/Nm3. During the reference test, the emission was reduced to avg. 175 mg/Nm3, which produces a NOx reduction of 52%. NH3 slip in the flue gas was stable and did not exceed 2 ppm. Combining urea and halloysite powders leads to a number of positive effects; not only is NOx emission reduced to values typical for wet SNCR, but also a significant, over ten-fold increase in the concentration of adsorbed mercury in fly ash was observed. When confronted with wet SNCR, dry SNCR has no adverse effect on boiler efficiency because it does not increase the stack heat loss. The presented method can be used in any small- or medium-scale furnace, including waste-to-energy units or medical and hazardous waste incineration units.

Appraisal of SOx Emission from Flue Gas in Thermal Power Station and Dry Sorbent Injection (DSI) Method to Reduce SOx

Electrical vitality created in any nation is one of the advancement estimates happens in that nation. The vitality delivered is principally founded on the accessible assets, for example, streaming water, coal, oil, gas, atomic fills, wind, sunlight based and so forth. The accessibility of wealth coal in India had incited the influence plant organizers to introduce coal based warm influence stations. During the pre-autonomy and post-freedom period in mid fifties, the need was to produce control and consequently much consideration was not paid to the contamination perspective and this proceeded up to late seventies. Most of intensity plants in India extending from not many MW to 500 MW or more are of pummeled fuel terminated boilers using low calorific, low coal sulfur, high debris content sub-bituminous coal. Because of consuming of the coal, discharges, for example, Particulate Matter (PM), Oxides of Sulfur (SOx) and Oxides of Nitrogen (NOx) aside from CO2, CO are diverted to the climate through the vent gas. The mindfulness made by contamination impact on the general public and the tremendous measure of disintegration exposed to the gear constrained the specialists to make contamination standards increasingly stringent. In this paper, the methodology to reduce SOx from flue gas in an old lower capacity power station is discussed and the optimum and cost effective methodology adopted is Dry Sorbent Injection (DSI) by injecting sodium bicarbonate or sodium carbonate or trona in the flue gas path after furnace and before/after Air-preheater to remove SO2/SO3 from the flue gas. The removed sulphate will be collected along with ash in ESP or Fabric Filter in a Bag house

Kinetic Evaluation of Lime for Medium-Temperature Desulfurization in Oxy-Fuel Conditions by Dry Sorbent Injection

With increasing emphasis on the control of greenhouse gases, power plants may move towards oxy-fuel technologies rather than air-fired plants. This move leads to a change in the feed to the desulfurization unit, which also needs to be adapted along with the power plant. Most existing plants already have functioning desulfurization units, which need to be retrofitted for the new conditions. In the present study, three different limes have been examined as sorbents for sulfur capture in oxy-fuel conditions with varying residence times at medium temperature (150–450 ∘ C). Parameters indicative of the kinetics and competition between SO 2 and CO 2 , like SO 2 breakthrough time, total lime conversion, yield for sulfur capture and sulfur selectivity have been evaluated. The results of this study lead to the recommendation that medium temperature desulfurization should be used for moderate SO 2 capture, in combination with already existing sulfur capture systems. The effects of CO 2 and water vapor have also been analyzed. In addition, the performance of the unit irrespective of temperature strongly depends on the lime type. In addition, absence of water vapor strongly favored the desulfurization process when there was high concentration of CO 2 .