Difficulties in Trying To Model and Scale-Up the Bubbling Fluidized Bed (BFB) Reactor

The production of synthetic natural gas (SNG) via methanation has been demonstrated by experiments in bench scale bubbling fluidized bed reactors. In the current work, we focus on the scale-up of the methanation reactor, and a circulating fluidized bed (CFB) is designed with variable diameter according to the characteristic of methanation. The critical issue is the removal of reaction heat during the strongly exothermic process of the methanation. As a result, an interconnected bubbling fluidized bed (BFB) is utilized and connected with the reactor in order to cool the particles and to maintain system temperature. A 3D model is built, and the influences of operating temperature on H2, CO conversion and CH4 yield are evaluated by numerical simulations. The instantaneous and time-averaged flow behaviors are obtained and analyzed. It turns out that the products with high concentrations of CH4 are received at the CFB reactor outlet. The temperature of the system is kept under control by using a cooling unit, and the steady state of thermal behavior is achieved under the cooling effect of BFB reactor. The circulating rate of particles and the cooling power of the BFB reactor significantly affect the performance of reactor. This investigation provides insight into the design and operation of a scale-up methanation reactor, and the feasibility of the CFB reactor for the methanation process is confirmed.

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Scale-up of bubbling fluidized bed reactors — A review

Powder Technology ◽

10.1016/j.powtec.2011.10.004 ◽

2012 ◽

Vol 217 ◽

pp. 21-38 ◽

Cited By ~ 102

Author(s):

Martin Rüdisüli ◽

Tilman J. Schildhauer ◽

Serge M.A. Biollaz ◽

J. Ruud van Ommen

Keyword(s):

Fluidized Bed ◽

Scale Up ◽

Fluidized Bed Reactors ◽

Bubbling Fluidized Bed

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Experimental and Numerical Study of Rotating Fluidized Beds in a Static Geometry

International Journal of Chemical Reactor Engineering ◽

10.2202/1542-6580.1538 ◽

2007 ◽

Vol 5 (1) ◽

Cited By ~ 2

Author(s):

Juray De Wilde ◽

Ali Habibi ◽

Axel de Broqueville

Keyword(s):

Fluidized Bed ◽

Solid Phase ◽

Numerical Study ◽

Large Diameter ◽

Scale Up ◽

Small Diameter ◽

Polymer Particles ◽

Bubbling Fluidized Bed ◽

Particle Bed ◽

Dynamics Simulations

The new concept of a rotating fluidized bed in a static geometry was numerically and experimentally studied. The particle bed can be both tangentially and radially fluidized by injecting the fluidization gas tangentially in the static fluidization chamber via multiple gas inlet slots located in its outer cylindrical wall. The tangential fluidization of the particles induces a rotating motion of the particle bed. As a result of the particle bed rotational motion, the solids experience a radially outwards centrifugal force. A radially inwards gas-solid drag force and radial fluidization of the particle bed can be introduced by forcing the fluidization gas to leave the fluidization chamber via a chimney with one or multiple gas outlet slots, positioned at the axis of the fluidization chamber. The solids can be continuously fed and removed in and out of the fluidization chamber via solids inlet and outlet holes in the front or back ends of the fluidization chamber.The fluidization patterns of low-density polymer particles with a large diameter and of high-density salt particles with a small diameter were experimentally studied in a 24-cm diameter, 13.5-cm long non-optimized static fluidization chamber at different solids loadings. Scale-up to a 36-cm diameter fluidization chamber was also studied. With both types of particles, a rotating fluidized bed and an acceptable gas-solid separation was obtained provided that the solids loading was sufficiently high. Slugging and channeling and a non-uniform distribution of the gas over the gas inlet slots to the fluidization chamber may occur at low solids loadings and can be detected via well-chosen pressure measurements. The fluidization patterns observed in the same fluidization chamber were completely different with the polymer particles and with the salt particles. The polymer particles tend to form a dense and uniform bed, its behavior being mainly characterized by tangential fluidization. The salt particles tend to form a less dense, bubbling fluidized bed that is both tangentially and radially fluidized.Computational fluid dynamics simulations give an improved insight in the gas and solid phase flow pattern.

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