We describe a new two-fluid model for gas-solid flows that incorporates the gas turbulence influence on the random motion of the particles via a generalised kinetic theory, as well as a new gas turbulence modulation model. Simulation results for fully developed steady vertical pipe flows are in good quantitative agreement with experimental measurements. Our results show that the influence of gas turbulence on the particle microscopic flow behaviour cannot be ignored for relatively dilute flows, especially with smaller particles. Our new turbulent model captures the essential characteristics of gas turbulence modulation in the presence of particles, and can be solved for a wide range of particle-particle restitution coefficients.