High　concentration　of　CO/H-2　mixture　may　be　formed　in　the　local　boiler　cold　hopper　area.　Then　if　there　is　other　high　temperature　coke　drops　into　this　area,　deflagration　may　be　caused.　The　influence　of　N-2,　CO2　concentration　at　different　temperatures　on　lower　deflagration　limit　(LDL)　and　deflagration　overpressure　of　CO/H-2　mixture　and　propagation　velocity　of　the　pressure　wave　are　studied.　With　the　rise　of　N-2,　CO2　concentration,　the　LDL　of　CO　will　rise　from　18.3%　to　31.0%　and　24.5%　respectively.　The　pressure　of　CO/H-2　mixture　deflagration　overpressure　will　decrease　from　111.8kPa　to　67.7kPa　and　60.4kPa　respectively.　The　propagation　velocity　of　the　pressure　wave　is　almost　linear　decrease,　and　the　inhibiting　effect　of　CO2　is　more　powerful　than　N-2.　The　higher　the　temperature,　the　lower　the　deflagration　strength　will　be,　H-2　plays　a　key　role　in　the　mixture　deflagration.　(C)　2014　The　Authors.　Published　by　Elsevier　Ltd.