Kraft recovery boiler operation with splash plate and/or beer can nozzles — a case study

In this work, we study a boiler experiencing upper furnace plugging and availability issues. To improve the situation and increase boiler availability, the liquor spray system was tuned/modified by testing different combinations of splash plate and beer can nozzles. While beer cans are typically used in smaller furnaces, in this work, we considered a furnace with a large floor area for the study. The tested cases included: 1) all splash plate nozzles (original operation), 2) all beer can nozzles, and 3) splash plate nozzles on front and back wall and beer cans nozzles on side walls. We found that operating according to Case 3 resulted in improved overall boiler operation as compared to the original condition of using splash plates only. Additionally, we carried out computational fluid dynamics (CFD) modeling of the three liquor spray cases to better understand the furnace behavior in detail for the tested cases. Model predictions show details of furnace combustion characteristics such as temperature, turbulence, gas flow pattern, carryover, and char bed behavior. Simulation using only the beer can nozzles resulted in a clear reduction of carryover. However, at the same time, the predicted lower furnace temperatures close to the char bed were in some locations very low, indicating unstable bed burning. Compared to the first two cases, the model predictions using a mixed setup of splash plate and beer can nozzles showed lower carryover, but without the excessive lowering of gas temperatures close to the char bed.

A comparative approach in the utilisation of rice husk and empty palm bunch in the biomass boiler

Growing world’s population has immense contribution towards world economy and energy utilisation. The enormous usage of conventional fuel has contributed many environmental problems such as greenhouse gas emission (GHG), world climate change, and deterioration of human health. Recent study focuses on the generated power from EPB compared with methane in a typical biomass boiler. Also, there are very limited studies on the Air to Fuel (ATF) ratios value in boiler operation. In this paper, empty palm bunch (EPB) and rice husk (RH) have been selected as biomass fuel in the biomass boiler. The same recommended parameters of boiler and turbine was chosen for both EPB and RH feedstocks from previous study. Overall, the study proven to produce about 33% and 25% of energy from EPB and RH of what a methane (CH4) can produce from the same amount of feeding rate, respectively, with EPB producing 13.31% of higher turbine power than RH. This directly contributes to the technical feasibility and adaptability of environmentally friendly elements by seizing the opportunity of carbon emission of conventional fuel and replacing it with natural resources such as EPB and RH which are part of the biomass fuel replacement regime. However, ATF ratio of RH is significantly minimal of what a CH4 and EPB utilised to burn 1 kg of fuel. Therefore, EPB and RH would be suitable for future renewable biomass feedstock in comparison with conventional fuel for power generation purposes.

Rational Heat Schemes Using Condensing Boilers in Local Heat Supply Systems

Within the framework of this publication, thermal diagrams of autonomous heat supply systems using condensing heat generators are considered. The insignificant Russian experience of using small condensation boilers in residential construction shows that it is often used to simply replace traditional equipment with condensation technology in existing (or traditionally used) heat schemes, for example, with protection of the boiler from “cold return” by recirculating heat carrier or installing a hydraulic regulator. The consequence of this is almost completely lost the effect of the use of condensing boilers. At the same time, even using the heating temperature schedule of quality regulation 80-60°C and applying water heating to the DHW target up to 45°C you can achieve the effect of the boiler operation in the condensation mode, depending on the construction area, up to 75% of the total working time per year, generating about 70% of thermal energy in the annual cycle. However, it must be borne in mind that the efficiency of the condensing boiler is determined by the part of the latent heat of water vapor in the combustion products, which can be obtained with partial condensation. If this part is small, for example, when cooling the flue gases to 50-45°C (on gas), then the efficiency gain is only 1-3%.