How to ship if Bill to address is of India and Ship to address is of abroad

This is ok but in which currency the export proceeds will come to India? Indian or Foreign?

Payment would be made in INR in India  itself by our Indian Client which is sending goods to Sri Lanka for his employees working there.

As per PARA 2.52(a) of FTP- Denomination of Export Contracts (a) All export contracts and invoices shall be denominated either in freely convertible currency or Indian rupees but export proceeds shall be realized in freely convertible currency.

Para 2.52(b) of FTP-Except specific export under which export realisation can be in INR but , provided it is through a freely convertible Vostro account of a non resident bank situated in any country other than a member country of Asian Clearing Union (ACU) or Nepal or Bhutan.

If your case is not falling in 2.52(b) it is not possible to have export realisation in INR that too from India.

There are some other way out.