scholarly journals Operating parameters affecting the thermal performance of biomass boilers

TAPPI Journal ◽  
2017 ◽  
Vol 16 (08) ◽  
pp. 453-461
Author(s):  
Naz Orang ◽  
Honghi Tran ◽  
Andy Jones ◽  
F. Donald Jones
Keyword(s):  
Moisture Content ◽  
Thermal Performance ◽  
Excess Oxygen ◽  
Operating Parameters ◽  
Pulp Mills ◽  
Furnace Temperature ◽  
Bubbling Fluidized Bed ◽  
Oil Flow ◽  
Induced Draft Fan ◽  
Content Range

Operating data of a bubbling fluidized bed (BFB) boiler and three stoker grate (SG) biomass boilers from different pulp mills were analyzed over a 2-year period. The results show that in all cases, the thermal performance decreases markedly from 5.5 to 4 lb steam/lb dry biomass as the feedstock moisture content increases from 40% to 60%. The BFB boiler had better thermal performance, although it operated in a higher moisture content range compared with the SG boilers. Multivariate analysis was also performed on one of the SG boilers to determine operating parameters that affect thermal performance. The results show that furnace temperature, oil flow rate, and induced draft fan current positively correlate with thermal performance, while the feedstock moisture content, total air flow, and excess oxygen (O2) negatively correlate with thermal performance. This implies that when making modifications to improve thermal performance, it is important to take into account correlations among various parameters. In some cases, one positively correlated parameter might cause an increase in a negatively correlated parameter. The net effect might be a decrease in thermal performance.

scholarly journals Effect of feedstock moisture content on biomass boiler operation

TAPPI Journal ◽  
2015 ◽  
Vol 14 (10) ◽  
pp. 629-637 ◽  
Author(s):  
NAZ ORANG ◽  
HONGHI TRAN
Keyword(s):  
Moisture Content ◽  
Fuel Oil ◽  
Furnace Temperature ◽  
Fundamental Study ◽  
Drying Time ◽  
Paper Mills ◽  
Biomass Boiler ◽  
Oil Flow ◽  
Boiler Operation ◽  
Downward Spiral

Burning feedstock with high and constantly varying moisture content is a challenge in the operationof the stoker-grate type biomass boilers in pulp and paper mills. A fundamental study was performed, using a thermogravimetric combustor controlled at different temperatures, to systematically investigate the effect of moisture content on the combustion behavior of several woody biomasses. The results show that combustion occurred through three stages: drying, devolatilization, and char burning. Increasing the moisture content of the sample above 30% significantly increased the drying time and the time to ignition of the sample. Moisture content, however, had only a small effect on the devolatilization rate and virtually no effect on the char burning rate. Furnace temperature had a great effect on combustion. Samples containing 40% moisture could still ignite and burn readily at 800°C, but they took a much longer time to ignite at 500°C and did not ignite at 400°C. These results imply that in biomass boiler operation, the high moisture content in feedstock delays combustion and causes the furnace temperature to decrease. The low temperature, in turn, suppresses combustion, further decreasing the furnace temperature and causing more delay in combustion. This downward spiral will eventually lead to a boiler blackout unless the biomass feed rate is significantly reduced or the auxiliary fuel (natural gas and fuel oil) flow rate cofired in the boiler is increased to keep the furnace temperature high.

scholarly journals Study on the Moisture Absorption and Thermal Properties of Hygroscopic Exothermic Fibers and Related Interactions with Water Molecules

Polymers ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 98 ◽  
Author(s):  
Yi Cui ◽  
Shuyi Gao ◽  
Ruiyun Zhang ◽  
Longdi Cheng ◽  
Jianyong Yu
Keyword(s):  
Moisture Content ◽  
Thermal Performance ◽  
Water Sorption ◽  
Moisture Absorption ◽  
Bound Water ◽  
Absorption Process ◽  
Heating Performance ◽  
Hygroscopic Behavior ◽  
Water Sorption Capacity ◽  
Main Factor

The aim of this paper is to study the hygroscopic behavior of hygroscopic exothermic fiber-based materials and to obtain a better understanding of the thermal performance of these fibers during the moisture absorption process. The temperature distribution of different kinds of hygroscopic exothermic fibers in the process of moisture absorption, observed by infrared camera, demonstrated two types of heating performance of these fibers, which might be related to its hygroscopic behavior. Based on the sorption isotherms, a Guggenheim-Anderson-de Boer (GAB) multi-layer adsorption model was selected as the optimal moisture absorption fitting model to describe the moisture absorption process of these fibers, which illustrated that water sorption capacity and the water–fiber/water–water interaction had a significant influence on its heating performance. The net isosteric heats of sorption decreased with an increase of moisture content, which further explained the main factor affecting the heat dissipation of fibers under different moisture contents. The state of adsorbed water and water vapor interaction on the fiber surface were studied by simultaneous thermal analysis (TGA-DSC) measurement. The percentage of bound and unbound water formation at low and high humidity had a profound effect on the thermal performance of fibers. It can therefore be concluded that the content of tightly bound water a strong water–fiber interaction was the main factor affecting the heating performance of fibers at low moisture content, and the content of loosely bound water reflected that water sorption capacity was the main factor affecting the heating performance of fibers at high moisture content. This was further proven by the heat of desorption.

Nutrient composition of pastoralist's raw milk of different breeds of cattle in Adamawa and Taraba states, Northeastern Nigeria

2020 ◽  
Vol 47 (2) ◽  
pp. 217-223
Author(s):  
Z. Adamu ◽  
M. B. Ardo ◽  
Y. H. Aliyara
Keyword(s):  
Moisture Content ◽  
Local Governments ◽  
Management Practices ◽  
Raw Milk ◽  
Fat Content ◽  
Ash Content ◽  
Milk Samples ◽  
Moisture Contents ◽  
Significant Difference ◽  
Content Range

This study was carried out to determine the proximate composition of raw milk produced in pastoral settlements. Six hundred pastoralists' raw milk samples were collected from 20 local governments in Adamawa and Taraba states, Nigeria. Milk samples were collected from White Fulani (WF), Red Bororo (RB) and Sokoto Gudali (SG) breeds of cattle and were analyzed for protein, fat, ash and moisture contents. The protein content ranged between 3.62±0.38% -3.95±0.11% in WF, 3.29±0.8% - 3.94±0.10% in RB and 3.31±0.27%- 3.95±0.09% in SG in Adamawa and Taraba states. The fat content ranged between 3.55±0.47% - 3.99±0.03% in WF, 3.98±0.04% - 3.98±0.06% in RB and 3.32±0.20% - 3.45±0.27% in SG. The ash content recorded was between 0.40±0.06% -0.41±0.04% in WF, 0.40±0.06% - 0.43±0.07% in RB and0.39±0.06% - 0.41±0.08% in SG, and the moisture content in Adamawa and Taraba states were between 83.52±2.07% - 84.00±0.57% in WF, 82.28±1.05% - 83.73±0.63% in RB and 82.90±1.48% - 83.56±1.35%in SG. The study from the two states revealed protein value between 3.29± 0.8% - 3.95±0.11%, fat content range of3.32±0.20% - 3.99±0.03%, ash content of between 0.39± 0.06% - 0.43±0.07% and moisture content that ranged between 82.28± 1.05% - 84.00±0.57%. Constituents of milkfrom Taraba state were higher in values than those from Adamawa sate. The statistical analysis of the results at95% confidence level showed significant difference among breeds and states. In comparison, the three breeds that resided in Adamawa state had least values, which could be attributed to herd management practices. This study showed that all the three pastoralists' breeds indicated desirable components in their milk Cross breeding with higher breeds and provision of quality feed and water may lead to better yield in all the breeds in this study.

Mathematical Modeling of the Process of Operation of the Drying Chamber of a Tower Grain Dryer With a Suction Air Flow

2020 ◽  
pp. 114-121
Author(s):  
Viktor Shvidia ◽  
◽  
Serhii Stepanenko ◽  
Keyword(s):  
Moisture Content ◽  
Air Flow ◽  
Initial Moisture Content ◽  
Material Balance ◽  
Operating Parameters ◽  
Conservation Of Energy ◽  
Grain Moisture ◽  
Optimal Mode ◽  
Drying Chamber ◽  
Main Operating

In the article, a drying scheme in a tower grain dryer has been developed, equations for the conservation of energy and material balance for grain, equations for mass transfer and heat transfer between the drying agent and grain have been drawn up. On their basis, analytical dependences of changes in the temperature and moisture content of grain, moisture content and temperature of the drying agent along and in the width of the drying channel were obtained, depending on the operating parameters (the value of rarefaction in the drying channel, the speed of grain movement along the drying channel, the speed of movement of the drying agent, the initial temperatures of the grain and drying agent, initial moisture content of grain, as well as initial moisture content of drying agent). Their analysis facilitates the work in choosing the optimal mode. The developed analytical dependences of changes in the main drying parameters (moisture and temperature of grain, moisture content and temperature of the drying agent) along the length and width of the drying channel in tower dryers with suction air flow make it possible to link the main operating parameters, which facilitate the choice of rational drying modes.

scholarly journals Sensitivity Analysis and Optimization of Operating Parameters of an Oxyfuel Combustion Power Generation System Based on Single-Factor and Orthogonal Design Methods

Energies ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 998
Author(s):  
Zhiyu Zhang ◽  
Rongrong Zhai ◽  
Xinwei Wang ◽  
Yongping Yang
Keyword(s):  
Power Generation ◽  
Flue Gas ◽  
Consumption Rate ◽  
Orthogonal Design ◽  
Excess Oxygen ◽  
Operating Parameters ◽  
Generation System ◽  
Coal Consumption ◽  
Oxygen Coefficient ◽  
Power Generation System

The main purpose of this paper is to quantitatively analyze the sensitivity of operating parameters of the system to the thermodynamic performance of an oxyfuel combustion (OC) power generation system. Therefore, the thermodynamic model of a 600 MW subcritical OC power generation system with semi-dry flue gas recirculation was established. Two energy consumption indexes of the system were selected, process simulation was adopted, and orthogonal design, range analysis, and variance analysis were used for the first time on the basis of single-factor analysis to conduct a comprehensive sensitivity analysis and optimization research on the changes of four operating parameters. The results show that with increasing oxygen purity, the net standard coal consumption rate first decreases and then increases. With decreasing oxygen concentration, the recirculation rate of dry flue gas in boiler flue gas ( χ 1 ) and an increasing excess oxygen coefficient, the net standard coal consumption rate increases. The net electrical efficiency was just the opposite. The sensitivity order of two factors for four indexes is obtained: the excess oxygen coefficient was the main factor that affects the net standard coal consumption rate and the net electrical efficiency. The influence of oxygen concentration and oxygen purity was lower than that of excess oxygen coefficient, and χ 1 has almost no effect.

An Experimental Study on the Thermal Performance Evaluation of SCW Ground Heat Exchanger

2017 ◽  
Vol 25 (01) ◽  
pp. 1750006 ◽  
Author(s):  
Keun Sun Chang ◽  
Min Jun Kim ◽  
Young Jae Kim
Keyword(s):  
Thermal Conductivity ◽  
Performance Evaluation ◽  
Heat Exchanger ◽  
Effective Thermal Conductivity ◽  
Thermal Performance ◽  
Thermal Response ◽  
High Heat ◽  
Injection Rate ◽  
Operating Parameters ◽  
Ground Heat Exchanger

In recent years, application of the standing column well (SCW) ground heat exchanger (GHX) has been noticeably increased as a heat transfer mechanism of ground source heat pump (GSHP) systems with its high heat capacity and efficiency. Determination of the ground thermal properties is an important task for sizing and estimating cost of the GHX. In this study, an in situ thermal response test (TRT) is applied to the thermal performance evaluation of SCW. Two SCWs with different design configurations are installed in sequence to evaluate their effects on the thermal performance of SCW using a single borehole. A line source method is used to derive the effective thermal conductivity and borehole thermal resistance. Effects of operating parameters are also investigated including bleed, heat injection rate, flow rate and filler height. Results show that the effective thermal conductivity of top drawn SCW (Type A) is 11.7% higher than that of bottom drawn SCW (Type B) and of operating parameters tested bleed is the most significant one for the improvement of the thermal performance (40.4% enhanced in thermal conductivity with 10.9% bleed).

Preliminary Study on CO2 Processing in CO2 Capture From Oxy-Fuel Combustion

2007 ◽  
Author(s):  
H. Li ◽  
J. Yan
Keyword(s):  
Energy Consumption ◽  
Co2 Capture ◽  
Minimum Energy ◽  
High Energy ◽  
Fuel Combustion ◽  
Energy Utilization ◽  
Excess Oxygen ◽  
Operating Parameters ◽  
Gas Processing ◽  
Minimum Energy Consumption

Oxy-fuel combustion is one of promising technologies for CO2 capture, which uses simple flue gas processing normally including compression, dehydration and purification/liquefaction (non-condensable gas separation). However relatively high levels of impurities in the flu gas present more challenges for the gas processing procedure. This paper studied the sensitivity of operating parameters to inlet composition, the effects of impurities on energy consumption, and the relationship between energy consumption and operating parameters. Results show that comparatively the total compression work is more sensitive to the composition of SO2 if the total mass flow is constant; while the operating temperature of purification is more sensitive to N2. To pursue the minimum energy consumption, from the viewpoint of impurity, the content of O2, N2, Ar and H2O should be lowered as much as possible, which means the amount of air leakage into the system and excess oxygen should be controlled at a low level in the combustion; as to SO2, if it is possible to co-deposit with CO2, its existence may be helpful to decrease compression work. From the viewpoint of operating parameters, low intermediate pressure, high intercooling temperature and high outlet pressure are favorable to achieve high energy utilization, if heat recovery is considered.

scholarly journals Aerodynamic Properties of Makhobeli, Triticale and Wheat Seeds

2014 ◽  
Vol 28 (3) ◽  
pp. 389-394 ◽  
Author(s):  
Feizollah Shahbazi ◽  
Saman Valizadeh ◽  
Ali Dowlatshah
Keyword(s):  
Moisture Content ◽  
Drag Coefficient ◽  
Terminal Velocity ◽  
Mean Value ◽  
Probability Level ◽  
Mean Values ◽  
Aerodynamic Properties ◽  
The Mean ◽  
Content Range ◽  
Wheat Seeds

Abstract The objective of this study was the evaluation of the aerodynamic properties of Makhobeli, triticale and wheat seeds as a function of moisture content from 7 to 27% (w.b). The results showed that the terminal velocity of triticale and wheat seeds increased linearly from 5.37 to 6.42 and from 6.31 to 8.02 m s-1, respectively, as the moisture content increased from 7 to 27%. Over this same moisture content range, the terminal velocity of Makhobeli seeds varied following a polynomial relationship from 4.52 to 5.07 m s-1. Makhobeli seeds had terminal velocities with a mean value of 4.73 m s-1, at different moisture contents, compared to the mean values of 5.89 and 7.13 m s-1 for triticale and wheat seeds, respectively. The mean value of drag coefficient was 1.12 for Makhobeli compared to the values of 0.92 and 0.85 for triticale and wheat, respectively. The analysis of variance showed that there were significant differences between the terminal velocity (at 1 % probability level) and drag coefficient (at 5% probability level) of Mak-hobeli with triticale and wheat seeds, which suggests that aerodynamic separation of Makhobeli from triticale and wheat is possible.

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