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Abstract

Superheater is for generating superheated steam from the saturated steam from the evaporator outlet. In the case of pulverized coal fired boiler, a relatively small amount of ash causes problems with ash fouling on the heating surfaces, including the superheaters. In the convection pass of the boiler, the flue gas temperature is lower and ash deposits can be loose or sintered. Ash fouling not only reduces heat transfer from the flue gas to the steam, but also is the cause of a higher pressure drop on the flue gas flow path. In the case the pressure drop is greater than the power consumed by the fan increases. If the superheater surfaces are covered with ash than the steam temperature at the outlet of the superheater stages falls, and the flow rates of the water injected into attemperator should be reduced. There is also an increase in flue gas temperature after the different stages of the superheater. Consequently, this leads to a reduction in boiler efficiency. The paper presents the results of computational fluid dynamics simulations of the first stage superheater of both the boiler OP-210M using the commercial software. The temperature distributions of the steam and flue gas along the way they flow together with temperature of the tube walls and temperature of the ash deposits will be determined. The calculated steam temperature is compared with measurement results. Knowledge of these temperatures is of great practical importance because it allows to choose the grade of steel for a given superheater stage. Using the developed model of the superheater to determine its degree of ash fouling in the on-line mode one can control the activation frequency of steam sootblowers.
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Authors and Affiliations

Marcin Trojan
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Abstract

The temperature of liquid steel for continuous casting determines the casting speed and cooling conditions. The failure to meet the required casting process parameters may result in obtaining slabs of inconsistent quality. Numerical methods allow for real processes to be modelled. There are professional computer programs on the market, so the results of the simulations allow us to understand the processes that occur during casting and solidification of a slab. The study attempts to evaluate the impact of the superheat temperature on the slab structure based on the industrial operating parameters of the continuous casting machine.

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Authors and Affiliations

P. Drożdż
ORCID: ORCID
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Abstract

A mathematical model of the steam superheater exchanger with distributed parameters has been developed. Scale deposits were assumed to be present on the internal tube surfaces. It was assumed that the inner tube surfaces are covered by a thin layer of scale deposits. The finite volume method was used to solve partial differential equations describing flue gas, tube wall and steam temperature. The developed modeling technique can especially be used for modeling tube heat exchangers when detail information on the tube wall temperature distribution is needed. The numerical model of the superheater developed in the paper can be used for modeling of the superheaters with complex flow arrangement accounting scales on the internal tube surfaces. Using the model proposed the detailed steam, wall and flue gas temperature distribution over the entire superheater can be determined. The steam pressure distribution along its path flow and the total heat transfer rate can also be obtained. The calculations showed that the presence of scale on the internal surfaces of the tubes cause the steam temperature decrease and the heat flow rate transferred from the flue gas to the steam. Scale deposits on the inner surfaces of the tubes cause the tube wall temperature growth and can lead to premature wear of tubes due to overheating.

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Authors and Affiliations

Marcin Trojan
Jan Taler
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Abstract

Air pollution has a serious impact on the health of human beings and is a major cause of death worldwide every year. Out of the many sources of air pollution, the smoke generated from household combustion devices is very dangerous due to the incomplete combustion of fuel. Women from rural areas suffer a lot due to this harmful smoke. Diseases like cancer, throat, and lung infection occur in adults and children due to inhalation of this smoke. The traditional chulha used by rural women is operated by using cow dung, straw, and wood, and the air is blown manually by using small metallic pipes. This paper presents the design and development of an innovative stove to maximize flame temperature and minimize air pollution to overcome the health-related issues of rural women. A smokeless stove is presented, in which wood, straw, and cow dung are taken as primary fuel, and superheated steam as a secondary oxidizer for its operation. In this stove, a forced draft is created by the provision of a small fan, which is operated by solar power thus eliminating the need of creating a forced draft manually by the cook which makes this innovative stove superior to the traditional chulha. Owing to the provision of superheated steam, the flame temperature as well as the burning efficiency increases. The cooking time is reduced due to higher flame temperature as compared to the liquefied petroleum gas stove. The main objective of this work is to minimize air pollution and provide a smoke-free environment to the people using such devices as this innovative stove offers complete combustion of fuel. The flame temperature of the designed stove ranges from 595˚C to 700˚C and its thermal efficiency is 10–17% higher than that of the traditional chulha. The design of this stove is unique, and its maintenance cost is also much less.
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Authors and Affiliations

Ramesh Chandra Nayak
1
Manmatha K. Roul
2
Prateek Debadarsi Roul
3

  1. Synergy Institute of Technology, Bhubaneswar – 752101, Odisha, India
  2. GITA Autonomous College, Bhubaneswar – 752054, Odisha, India
  3. Odisha University of Technology and Research, Bhubaneswar – 751003, Odisha, India

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