Following is my code
The converter attribute must point to either a concrete instance like #{bean.converter} or contain a string literal with the converter ID and not the fully qualified converter class name. If you click through CONVERTER_ID field constant in the standard converter's javadoc, then you'll find out that it's javax.faces.Integer for the IntegerConverter.
So, this should do:
<rich:select ... converter="javax.faces.Integer" />