Is there any time limit for sanctioning of refund?

Yes, it is 90 days in all cases, excepting in a case
where the refund to the extent of 80% of the total amount
claimed is refundable to certain categories of exporters
referred to in sub-section (4A) of section 38. If refund is
not sanctioned within the period of three months, interest
will have to be paid by the department.