Recovery of Water from Boiler Flue Gas Using Condensing Heat Exchangers

Most of the water used in a thermoelectric power plant is used for cooling, and DOE has been focusing on possible techniques to reduce the amount of fresh water needed for cooling. DOE has also been placing emphasis on recovery of usable water from sources not generally considered, such as mine water, water produced from oil and gas extraction, and water contained in boiler flue gas. This report deals with development of condensing heat exchanger technology for recovering moisture from flue gas from coal-fired power plants. The report describes: • An expanded data base on water and acid condensation characteristics of condensing heat exchangers in coal-fired units. This data base was generated by performing slip stream tests at a power plant with high sulfur bituminous coal and a wet FGD scrubber and at a power plant firing highmoisture, low rank coals. • Data on typical concentrations of HCl, HNO{sub 3} and H{sub 2}SO{sub 4} in low temperature condensed flue gas moisture, and mercury capture efficiencies as functions of process conditions in power plant field tests. • Theoretical predictions for sulfuric acid concentrations on tube surfaces at temperatures above the water vapor dewpoint temperature and below the sulfuric acid dew point temperature. • Data on corrosion rates of candidate heat exchanger tube materials for the different regions of the heat exchanger system as functions of acid concentration and temperature. • Data on effectiveness of acid traps in reducing sulfuric acid concentrations in a heat exchanger tube bundle. • Condensed flue gas water treatment needs and costs. • Condensing heat exchanger designs and installed capital costs for full-scale applications, both for installation immediately downstream of an ESP or baghouse and for installation downstream of a wet SO{sub 2} scrubber. • Results of cost-benefit studies of condensing heat exchangers

Use of Coal Drying to Reduce Water Consumed in Pulverized Coal Power Plants Quarterly Report

This is the twelfth Quarterly Report for this project. The background and technical justification for the project are described, including potential benefits of reducing fuel moisture using power plant waste heat, prior to firing the coal in a pulverized coal boiler. During this last Quarter, the development of analyses to determine the costs and financial benefits of coal drying was continued. The details of the model and key assumptions being used in the economic evaluation are described in this report and results are shown for a drying system utilizing a combination of waste heat from the condenser and thermal energy extracted from boiler flue gas

Recovery of Water from Boiler Flue Gas

This project dealt with use of condensing heat exchangers to recover water vapor from flue gas at coal-fired power plants. Pilot-scale heat transfer tests were performed to determine the relationship between flue gas moisture concentration, heat exchanger design and operating conditions, and water vapor condensation rate. The tests also determined the extent to which the condensation processes for water and acid vapors in flue gas can be made to occur separately in different heat transfer sections. The results showed flue gas water vapor condensed in the low temperature region of the heat exchanger system, with water capture efficiencies depending strongly on flue gas moisture content, cooling water inlet temperature, heat exchanger design and flue gas and cooling water flow rates. Sulfuric acid vapor condensed in both the high temperature and low temperature regions of the heat transfer apparatus, while hydrochloric and nitric acid vapors condensed with the water vapor in the low temperature region. Measurements made of flue gas mercury concentrations upstream and downstream of the heat exchangers showed a significant reduction in flue gas mercury concentration within the heat exchangers. A theoretical heat and mass transfer model was developed for predicting rates of heat transfer and water vapor condensation and comparisons were made with pilot scale measurements. Analyses were also carried out to estimate how much flue gas moisture it would be practical to recover from boiler flue gas and the magnitude of the heat rate improvements which could be made by recovering sensible and latent heat from flue gas

Increasing the Performance and Reliability of Power Boiler by Monitoring Thermal and Strength Parameters

The paper presents a method for determination of thermo-flow parameters for steam boilers. This method allows to perform the calculations of the boiler furnace chamber and heat flow rates absorbed by superheater stages. These parameters are important for monitoring the performance of the power unit. Knowledge of these parameters allows determining the degree of the furnace chamber slagging. The calculation can be performed in online mode and use to monitoring of steam boiler. The presented method allows to the operation of steam boiler with high efficiency

Ash deposition propensity of coals/blends combustion in boilers: a modelling analysis based on multi-slagging routes

A method that is based on the initial slagging routes and the sintered/slagging route has been developed and used for predicting the ash deposition propensities of coal combustion in utility boilers supported by the data collected from power stations. Two types of initial slagging routes are considered, namely (i) pyrite-induced initial slagging on the furnace wall, and (ii) fouling caused by the alkaline/alkali components condensation in the convection section. In addition, the sintered/slagging route is considered by the liquids temperature, which represents the melting potential of the main ash composition and is calculated using the chemical equilibrium methods. The partial least square regression (PLSR) technique, coupled with a cross validation method, is employed to obtain the correlation for the ash deposition indice. The method has been successfully applied to coals/blends combustion in boilers, ranging from low rank coals to bituminous coal. The results obtained show that the developed indice yields a higher success rate in classifying the overall slagging/fouling potential in boilers than some of the typical slagging indices. In addition, only using the SiO2/Al2O3 ratio to predict the melting behaviors and slagging potential is inaccurate since the effect of the SiO2/Al2O3 ratio is dictated by both the original ash composition and the way in which the SiO2/Al2O3 ratio is changed. Finally, the influence of the acid components (SiO2 and Al2O3) on the ash deposition prediction is investigated for guiding the mineral additives. It is noticed that the predicted ash deposition potentials of the three easy slagging coals investigated decrease more rapidly by adding Al2O3 than by adding SiO2

Investigations into air and refrigerant side heat transfer coefficients of finned-tube CO2 gas coolers

Gas coolers are heat rejection heat exchangers in vapour compression refrigeration systems that use carbon dioxide (CO2) as refrigerant. The design of gas coolers has a significant influence on the performance of CO2 refrigeration systems as it determines to a large extent the gas cooler/condenser pressure and the power consumption of the system. This paper investigates local refrigerant and air heat transfer coefficients in plain fin-and-tube gas cooler coils using Computational Fluid Dynamics (CFD) modelling. The aims were to provide insights into the variation of the local heat transfer rates in the coil and determine the influence of a) design enhancements such as the use of slit fins and b) to develop correlations for overall refrigerant and air heat transfer coefficients to be used in CO2 refrigeration component and system modelling. The results from the model which was validated against experimental measurements showed that a horizontal slit on the fin between the first and second row of tubes can lead to an increase in the heat rejection rate of the gas cooler by between 6% and 8%. This in turn can lead to smaller heat exchanger heat transfer area for a given heat rejection capacity or lower high side pressure and higher efficiency for the refrigeration system. The results and heat transfer correlations developed are a valuable resource for researchers and manufacturers of CO2 and other heat exchanger coils that experience a wide variation in refrigerant temperature during the gas cooling process.This study was supported by the RCUK National Centre for Sustainable Energy use in Food chains (CSEF) of the Research CouncilsUK Energy programme, Grant No: EP/K011820/1, GEA Searle, now Kevlion, and Directorate General for Higher Education-DIKTI–Indonesian Government for a PhD scholarship

Otokorelasyon verilerde proses kontrol tekniklerinin uygulanmasına yönelik bir araştırma

TEZ4137Tez (Yüksek Lisans) -- Çukurova Üniversitesi, Adana, 2001.Kaynakça (s. 58-60) var.viii, 64 s. ; 30 cm.

Balancing of Pulverized Coal Flows to Burners in Boilers With Pressurized Vertical Spindle Mills

Numerical modeling of a vertical spindle mill was performed using commercially available CFD software, Fluent 6.1. The results of an experimental study that had been carried out for a Stairmand cyclone were used for model development and verification since both the vertical spindle pulverizer and the cyclone have strong swirling flow and particle separation within the geometry

A research related to the applications of process control techniques for correlated processes

Çoğu istatistiksel proses kontrol teknikleri gözlemlerin birbirinden bağımsız ve normal dağıldığı varsayımına dayanır. Bununla beraber, istatistiksel proses kontrolünün uygulamalarında bu kabul, verilerin birbirlerine bağımlı olmasından dolayı gerçeklerden bir hayli uzaktır.Bu çalışma, kontrol dışı sinyallerin oto korelasyondan olup olmadığını tespit etmek için, istatistiksel proses kontrol teknikleri korelasyonla olduğunu ispatladığımız verilere uygulanmıştır Verilerin oto korelasyonla olduğu ispatlandıktan sonra oto korelasyonu yok etmek için uygun bir zaman serisi modeli, ARIMA (2,1,0), tespit edilmiştir. Tespit edilen model MINITAB-13 istatistik programı kullanılarak, orijinal verilerdeki oto korelasyon filtre edilmiştir. Shewart, CUSUM, ve EWMA kontrol şemaları rezidülere ve orijinal verilere uygulanmıştır.Most of the statistical process control (SPC) techniques are developed for the assumption that considers the measured data to be normaly and independently distributed. In real world applications of SPC, however, this assumption is very far from the truth due to the dependence of data on itself. In this study, the Statistical Process Control (SPC) techniques were applied to the auto correlated data. After proving that the data was auto correlated, a suitable time series model, ARIMA(2,1,0), for the particular set of data was adapted to remove the correlation from the observations. The predicted time series model was applied to filler out the auto correlation from the original data by using the MINITAB-13 statistical software tool

Recovery of Water from Boiler Flue Gas Using Condensing Heat Exchangers

Most of the water used in a thermoelectric power plant is used for cooling, and DOE has been focusing on possible techniques to reduce the amount of fresh water needed for cooling. DOE has also been placing emphasis on recovery of usable water from sources not generally considered, such as mine water, water produced from oil and gas extraction, and water contained in boiler flue gas. This report deals with development of condensing heat exchanger technology for recovering moisture from flue gas from coal-fired power plants. The report describes: • An expanded data base on water and acid condensation characteristics of condensing heat exchangers in coal-fired units. This data base was generated by performing slip stream tests at a power plant with high sulfur bituminous coal and a wet FGD scrubber and at a power plant firing highmoisture, low rank coals. • Data on typical concentrations of HCl, HNO{sub 3} and H{sub 2}SO{sub 4} in low temperature condensed flue gas moisture, and mercury capture efficiencies as functions of process conditions in power plant field tests. • Theoretical predictions for sulfuric acid concentrations on tube surfaces at temperatures above the water vapor dewpoint temperature and below the sulfuric acid dew point temperature. • Data on corrosion rates of candidate heat exchanger tube materials for the different regions of the heat exchanger system as functions of acid concentration and temperature. • Data on effectiveness of acid traps in reducing sulfuric acid concentrations in a heat exchanger tube bundle. • Condensed flue gas water treatment needs and costs. • Condensing heat exchanger designs and installed capital costs for full-scale applications, both for installation immediately downstream of an ESP or baghouse and for installation downstream of a wet SO{sub 2} scrubber. • Results of cost-benefit studies of condensing heat exchangers