Methods of Thermal Calculations for a Condensing Waste-Heat Exchanger

Abstract

The paper presents the algorithms for a flue gas/water waste-heat exchanger with and without condensation of water vapour contained in flue gas with experimental validation of theoretical results. The algorithms were used for calculations of the area of a heat exchanger using waste heat from a pulverised brown coal fired steam boiler operating in a power unit with a capacity of 900 MW e . In calculation of the condensing part, the calculation results obtained with two algorithms were compared (Colburn-Hobler and VDI algorithms). The VDI algorithm allowed to take into account the condensation of water vapour for flue gas temperatures above the temperature of the water dew point. Thanks to this, it was possible to calculate more accurately the required heat transfer area, which resulted in its reduction by 19 %. In addition, the influence of the mass transfer on the heat transfer area was taken into account, which contributed to a further reduction in the calculated size of the heat exchanger -in total by 28% as compared with the Colburn-Hobler algorithm. The presented VDI algorithm was used to design a 312 kW pilot-scale condensing heat exchanger installed in PGE Belchatow power plant. Obtained experimental results are in a good agreement with calculated values.

Advanced Computational Methods In Component-Oriented Modelling Of Municipal Solid Waste Incineration Processes

“…The model of associated processes i.e. degasing, gasification and combustion of solid waste is an objectoriented and reactive (event driven) model [16]. It is the implementation of a mathematical model in a source code of a high-level language (RAD) environment, using design techniques and Component-oriented analysis CCA (Common Component Architecture).…”

“…The reducing gases from the central reactor and the degassing chamber (model description-as in units 1, 2, 3) -UPPER REACTOR. Due to complexity of the actual process of high -temperature fuel combustion, a number of assumptions was made, which allow to precisely define the model and ignore details of no significance for simulation calculations (e.g, an assumption that the model parameters are subject to additivity) [16,18].…”

“…Open architecture of the model allows modifying a source code of the methods defined in the class types, representing different sub-models of a decomposed global task. The decomposed global model consists of the socalled sub-models, performing partial tasks of real process simulation [9, 16,18] 9. It should be noted that in a defined library of classes, the parent class is the type TObject, with basic definitions of fields, properties, and methods of environmental Object Pascal (Delphi).…”

Thermal Calculation and Experimental Investigation of Electric Heating and Solid Thermal Storage System

“…In the aspect of TSS design, the existing research mainly focuses on the thermal calculation of parts of the TSS, such as separate heat exchangers, heat storage modules, etc. Raczka et al [13] and Fujii et al [14] introduced the design and calculation method of flue gas/waste water-heat exchanger and indirect heat exchanger, respectively. Du et al [15] also reported a design method for heat storage units.…”

Studies on the process of recovering low-temperature waste heat from a flue gas in a pilot-scale plant

“…The function purpose of the heat exchanger installed is to increase the heat flux recovered through condensation of water vapour contained in the flue gas. Mathematical modelling and designing such a heat exchanger is a difficult task due to the complex model describing the heat transfer in the presence of inert gas, a concentration of water vapour, the effect of condensation, and a limitation resulting from a large heat flux that affects the overall dimensions of the exchanger (Chaojun et al, 2012;Chaojun et al, 2014;Dexin et al, 2012;Rączka et. al., 2014;Szulc et al, 2012;Szulc et al, 2013;Xiaojun et al, 2011).…”