Air mass balance for mass flow rate calculation in pneumatic conveying Cecilia Arakaki a, ⁎, Ali Ghaderi b , Arild Sæther c , Chandana Ratnayake a , Gisle G. Enstad d a Department of Powder Science and Technology (POSTEC), Telemark Technological Research and Development Centre (Tel-Tek), Porsgrunn, Norway b REC Wafer Norway AS, Porsgrunn, Norway c Norsk Hydro Aluminium AS, Årdal, Norway d Telemark University College (HiT), Porsgrunn, Norway abstract article info Article history: Received 31 August 2009 Received in revised form 24 February 2010 Accepted 7 April 2010 Available online 13 April 2010 Keywords: Pneumatic conveying Mass flow rate Mass balance Pressure Dilute phase Dense phase Mass flow rate of solids is probably the most important parameter in pneumatic conveying systems. It is a challenging task to measure this parameter in gas–solid flows. A new and simple model is presented and described to calculate the mass flow rate of solids in pneumatic conveying systems, based on air flow and pressure measurements. The principle of the model is conservation of mass, and it is applied in a horizontal straight pipe section. Two tests need to be performed on the actual conveying rig to be used for calibration of the model. Due to the kind of sensors used to carry out the necessary measurements, application of the model is rather inexpensive and non-intrusive. The model has been validated successfully with data from two different single blow tank conveying systems and in dense and dilute phase conveying. Four test materials were used for validation of the model: alumina, baryte, cement and dextrose. Provided that the requirements to apply the air mass balance model are fulfilled, its effective widespread application on real industrial systems seems plausible. © 2010 Elsevier B.V. All rights reserved. 1. Introduction Pneumatic conveying systems are used widely in a variety of industrial settings since several different types of materials can be conveyed [1]. Mass flow rate of solids is probably the most important parameter to measure in this kind of systems since it is vital for effective operation and control of the process. However, the nature of gas– solids flow makes measuring mass flow rate of solids much more complicated in relation to liquid or gas (single-phase) flows. The properties of the conveyed solids vary greatly from material to material and have a major influence in the process. In addition, as mentioned by Kost et al. [2], the varying properties of solids also cause variations from measurement system to measurement system. Throughout the years, several techniques, models and simulations have been made in order to understand the flow in conveying pipelines. They have estimated the mass flow rate directly or by two separate measurements of concentration and velocity; each one of them showing strengths and weaknesses. Several mass flow meters have been developed based on different principles such as ultrasound, capacitance, electrostatics, pressure, microwave, tomography and so on [3–5] though none of them has become a standard for mass flow rate measurement in industry. An ideal gas–solid flow meter should be non-intrusive, rugged, require little or no calibration, have a broad temperature range for operation, be independent of solids and gas types, be independent of particle size and inexpensive [3]. In addition, the flow meter should show accuracy and reproducibility. It is very challenging to achieve all these characteristics in a gas–solids flow meter, therefore, research is ongoing. Research on mass flow measurement with the use of pressure sensors has been done in the past. In 1992, a differential pressure based gas–solid flow meter was developed by Cabrejos and Klinzing [6], later on, a flow meter based on pressure drop over a standard section of piping was developed for dilute phase conveying [7].A system including a differential pressure transducer, a capacitance sensor, a pressure transducer and a temperature transducer was developed for measuring powder flow rate by Huang et al. [8].A model based on pressure drop was defined and used for mass flow rate measurement in vertical conveying [9]. In the present paper, a model based on pressure and air flow measurements was developed to calculate mass flow rate of solids in dilute and dense phase pneumatic conveying. 2. Model 2.1. Known parameters - Particle density - Gas properties Powder Technology 202 (2010) 62–70 ⁎ Corresponding author. Tel.: +47 35 57 40 71; fax: +47 35 57 41 40. E-mail address: cecilia.arakaki@tel-tek.no (C. Arakaki). 0032-5910/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.powtec.2010.04.007 Contents lists available at ScienceDirect Powder Technology journal homepage: www.elsevier.com/locate/powtec