Triple DES as cryptographic hash function
It is not a secure hash. For example, it is easy to find collisions and second preimages for your hash function if the input is allowed to be longer than 24 bytes, because only the first three 64-bit blocks affect the output.

Additionally, it should not even work with a typical DES implementation. DES keys are 56 bits, encoded as 64-bit values where 8 bits are for parity. Arbitrary inputs will not produce a well formatted key.