Meshing the elbow including guiding vanes
 

Hi,
Members of the professional community please advice. I am engaged in meshing of the compact inlet elbow with three guiding sheet vanes. In the middle of the outflow cross-section is located a protective tube, which on the upper side penetrates the outer casing of the elbow. In the attached figures it is presented one-half of an elbow, sectioned along the plane of symmetry. I hope that every significant detail is visible.
In the central part of the elbow, with presented vanes, the mesh is designed with tetra elements, but I'm more interested in hexahedral mesh – applying ICEM CFD. I am wondering how to design the blocks with the final goal that the whole elbow is one domain with hexahedral mesh element? Is it worth or not to insist in this idea?

Thanks