Calculation of soret-shifted dew points by continuous mixture thermodynamics

AIChE Journal ◽  
2005 ◽  
Vol 51 (10) ◽  
pp. 2811-2824 ◽  
Author(s):  
Daniel E. Rosner ◽  
Manuel Arias-Zugasti ◽  
Barbara LaMantia
Keyword(s):  
Continuous Mixture ◽  
Mixture Thermodynamics

scholarly journals Design of a new-concept conical positive displacement slurry pump for continuous de-clogging

2019 ◽  
Vol 287 ◽  
pp. 01017
Author(s):  
G. Vasileiou ◽  
N. Rogkas ◽  
S. Tsolakis ◽  
V. Spitas ◽  
P. Zalimidis
Keyword(s):  
Mass Flow ◽  
Aggregate Size ◽  
Axial Direction ◽  
Mixture Flow ◽  
Screw Pump ◽  
Velocity Increase ◽  
Positive Displacement ◽  
Continuous Mixture ◽  
Novel Concept ◽  
Concrete Pump

Slurry pumps are extensively used in the construction industry while positive displacement screw pumps are used in most mobile concrete pump applications. The aggregate size is known to significantly affect pump performance in terms of clogging. Large aggregates tend to be trapped against the stator-rotor interface, blocking the continuous and smooth operation of the screw pump. In order to avoid the development of excessive stress values able to damage the rotor-stator mechanism of the pump, the typical de-clogging mechanism deployed by most positive displacement screw slurry pumps includes reversing the rotation of the pump driving motor thus allowing the aggregates to be carried away with the mixture, so that the pump can soon resume its operation. This procedure causes frequent start-stops of the pump resulting in dis-continuation of the pumped mixture lasting a few seconds, that while being of little importance in most construction applications, can be of significance in applications requiring higher levels of accuracy and continuous mixture flow. In the context of this work, a novel concept of positive displacement screw slurry pump is presented, including a continuous de-clogging mechanism, without the need to reverse the rotation of the driving motor. This de-clogging operation is achieved through the modification of the geometry of both the rotor and stator introducing a conical form along the axial direction. This configuration of the rotor-stator, allows for small displacements along the axial direction, which in turn increases the size of the cavities facilitating the de-clogging of the pump. Variable pitch is also introduced to both the rotor and stator in order to ensure constant mass flow of the mixture throughout the length of the screw pump covering for the velocity increase as a result of the conical geometry. The axial movement of the rotor in relation to the fixed stator, is achieved through the elastic support of the rotor in the axial direction, that allows for small axial displacements, when stresses induced from trapped aggregates exceed the stiffness of the support. The proposed concept comprises a passive real-time de-clogging mechanism that greatly reduces pump idle time compared to the conventional mechanism described earlier, providing smoother operation and stable mass flow of the mixture.

scholarly journals Thermodynamics of combustion gases from biogas

2016 ◽  
Vol 62 (Special Issue) ◽  
pp. S8-S13 ◽  
Author(s):  
I. Vitázek ◽  
J. Klúčik ◽  
D. Uhrinová ◽  
Z. Mikulová ◽  
M. Mojžiš
Keyword(s):  
Anaerobic Fermentation ◽  
Power Production ◽  
Combined Heat And Power ◽  
Raw Material ◽  
Gas Mixture ◽  
Combustion Engines ◽  
Gas Combustion ◽  
Combustion Gases ◽  
Mixture Thermodynamics ◽  
The Mathematical Model

Biogas as a respected source of renewable energy is used in various areas for heating or in power cogeneration units. It is produced by anaerobic fermentation of biodegradable materials. The utilization of biogas is wide – from process of combustion in order to obtain thermal energy, combined heat and power production, gas combustion engines, micro turbines or fuel cells up to trigeneration. Biogas composition depends on the raw material. The aim of this paper was to develop a new methodology; according to this methodology, by means of gas mixture thermodynamics and tabular exact parameters of individual gaseous components, all the necessary thermodynamic and operating values of biogas composition were calculated. The mathematical model of biogas combustion was elaborated. For an accurate realization of calculation, a computing program was designed.  

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