Design and Analysis of Thermo-compressor for Paper Industries

Abstract

In the paper industries abundant amount of steam is used to dry the paper. After drying the paper, huge quantity of low pressure steam is not utilized in many industries and hence the energy available in the steam is wasted. Thermo-compressor is the device which can utilize such low pressure flash steam for drying of paper. There are huge scopes of utilizing such steam in the efficient manner using thermo-compressor.

M/s Marko Steam Jet Pvt. Ltd., Vatva, Ahmedabad is manufacturer of various components for paper industries like rotary joints, dosing pump, control valves, high pressure pumps, thermo-compressor etc. The company manufacture thermo-compressors in the wide range of motive steam pressure ranging from 7 to 11 bar. The existing design of thermo-compressor was not working efficiently below certain value of motive steam pressure. Hence, it was required to analyze and modify the existing design of thermo-compressor. In the present study, the thermo-compressor was designed corresponds to motive steam pressure of 7 bar (gauge) by considering it as saturated steam. In the first phase, thermo-compressor performance was analyzed with variable pressure of motive steam with constant mass flow rate. It was found that with motive steam pressure of 7 bar and flow rate of 900 kg/hr, the secondary steam flow rate was found as 686 kg/hr. accordingly, the entrainment ratio was obtained as 0.76. With decrease in motive steam pressure, the entrainment ratio decreased.

In the next phase, thermo-compressor was analyzed with variable mass flow rate of motive steam with constant inlet pressure. With decrease in the mass flow rate of motive steam, an expansion of motive steam increased. This led to decrease in suction capacity of motive steam to suck the secondary steam and hence resulted in decrease entertainment ratio. Further, 2D and 3D numerical analysis of thermo-compressor was done to validate the theoretical design. The entrainment ratio obtained from theoretical design and numerical analysis was found as 0.92 and 1.0 respectively. The numerical results were found within 10%, which showed very good agreement of two approaches.