Short communication Application of particle plug valve in a positive dilute gas-conveying system Shan Jing a, * , Qingyuan Hu b , Jinfu Wang b , Yong Jin b a Division of Chemical Technology, Institute of Nuclear Energy Technology, Tsinghua University, P.O. Box 1021, Beijing 102201, China b Department of Chemical Engineering, Tsinghua University, Beijing 100084, China Received 30 April 2001; received in revised form 6 February 2002; accepted 6 February 2002 Abstract Based on the characteristics of particle plug valve (PPV) [Powder Technol. 115 (1), (2001) 8], a series connection of PPVs, which is used in a positive dilute gas-conveying system for feeding Geldart-D powder periodically from a low-pressurized vessel into a high-pressurized vessel is presented, and four modes of operation have been discussed and tested by experiments. D 2002 Elsevier Science B.V. All rights reserved. Keywords: Positive gas-conveying system; Particle plug valve; Geldart-D powder 1. Introduction In a positive gas-conveying system, mechanical valves are usually employed to periodically inject the powder into a pressurized fluidized blow tank. By considering the erosion of mechanical valves, many valves without mechanical parts, such as the L-valve [1], J-valve [2], V-valve [3] and the orifice valve [4], have been developed, but can’t operate when the pressure gradient in these valves is larger than that calculated from q s g(1  e mf ) for Geldart-D powder. Re- cently, a pneumatically controlled peristaltic solids feeder (PCPSF), where rubble for the gas bags is not well suited for the high-temperature condition, has been successfully used in the gas-conveying system [5]. Therefore, we should develop a new valve without mechanical parts not only to satisfy the high-temperature condition but also to decrease the erosion. Based on the characteristics of a hung-up regime in a hopper – standpipe system for Geldart-D powder, particle plug valves (PPV) have been presented to keep the pressure drop larger than q s g(1  e mf ) in the standpipe at the stopping of particles flow. The strength factor of anti-pressure, E min and E max , for Geldart-D powder is shown in Appendix B [6] and the measures for enlarging the values of E max have also been taken [7]. When the PPV is used in a positive gas- conveying system, a series connection of two PPVs, which is introduced in Sections 2 and 3, must be chosen. In this paper, we firstly introduce the setup of PPV used in the positive gas-conveying system, then theoretically analyze the modes of operation and finally test the analytical results by experiment. 2. Setup of PPV used in a positive gas-conveying system Fig. 1 presents a view of the setup, where a series of two PPVs are connected, and used in a positive gas-conveying system. Each PPV consists of a hopper, a standpipe, an orifice for controlling the particle flow rate, a pressure- equalizing tube to satisfy Dp eq < Dp lock and an electromag- netic valve installed in the middle of the pressure-equalizing tube so that gas can be cut off. In order to convey the particles from the low-pressure vessel (in PPV1) to the high- pressure one (in PPV2), the particles in PPV1 flow down- wards when valve V 1 opens while the particles in PPV2 are hung-up when valve V 2 closes, where the pressure drop of the system is concentrated on the PPV2, and vice versa. The pressure transducers P 1 , P 2 and P 3 are used to determine the pressure of the series connection of PPVs as shown in Fig. 1. The pressure drop of PPV1 is Dp 12 ¼ P 1  P 2 : ð1Þ While the pressure drop for PPV2 is Dp 23 ¼ P 2  P 3 ð2Þ 0032-5910/02/$ - see front matter D 2002 Elsevier Science B.V. All rights reserved. PII:S0032-5910(02)00043-8 * Corresponding author. Fax: +86-10-6277-2051. www.elsevier.com/locate/powtec Powder Technology 126 (2002) 96– 101