Process for selecting shaped particles for use in a packed bed

A process for selecting shaped particles for use in a system which comprises a tube which is capable of being packed with shaped particles to form a packed bed in the tube, wherein the process comprises:

• defining a desired value of one or more properties of the packed bed,
• calculating dimensions of the shaped particles using a computer system having a central processing unit and a computer program such that a packed bed in the tube of the shaped particles having the calculated dimensions meets the desired value(s), and
• selecting shaped particles in accordance with the calculated dimensions, wherein the said one or more properties of the packed bed comprise one or more of:
• the volume fraction which is occupied by shaped particles,
• the packing density, and
• the resistivity for a gas flowing through the packed bed causing a pressure difference between a gas inlet and a gas outlet of the packed bed, which resistivity is defined by the expression:
• ΔP=R×ρ×V2,
• wherein ΔP represents the pressure difference per unit length of the packed bed, R represents the resistivity, ρ represents the density of the gas and V represents the superficial gas velocity, wherein the density of the gas and the superficial gas velocity are as measured at the average value of gas inlet temperature and gas outlet temperature of the packed bed and the average value of gas inlet pressure and gas outlet pressure of the packed bed;
• wherein the shaped particles have a cylinder geometric configuration, which may or may not be hollow, and which is defined by a cylinder length, a cylinder diameter and a cylinder bore diameter, on the understanding that in the absence of a bore the cylinder bore diameter is deemed to be zero;
• and
• wherein dimensions are calculated using one or more relationships which can be defined by one or more of the following expressions:
• when the property is the volume fraction which is occupied by shaped particles:
• Vp=a+b×(L/Do)+c×Di+d×Do2+e×Dt, or
• Vp=a′×[(Dt/Do)2/(b′+(Dt/Do)2)]−c′×[(Di/Do)2],
• and/or
• when the property is the packing density:
• PD=De×[a+b×(L/Do)+c×Di+d×Do2+e×Dt], or
• PD=De×[a′×[(Dt/Do)2/(b′+(Dt/Do)2)]−c′×(Di/Do)2]], and/or
• when the property is the resistivity:
• R=1+m×(L/Do)+n×Do+p×Di+q×L+r×Dt,
• wherein:
• Vp represents the desired value of the volume fraction of the packed bed which is occupied by shaped particles,
• PD represents the desired value of the packing density,
• R represents the desired value of the resistivity,
• L represents the cylinder length,
• Do represents the cylinder diameter,
• Di represents the cylinder bore diameter,
• De represents the particle density,
• Dt represents the inside diameter of the tube, and
• each of a, a′, b, b′, c, c′, d, e, l, m, n, p, q and r represents a constant having a dimension accommodating the dimension of the corresponding term of the expressions.