Conversion failed when converting the nvarchar value 'value' to int
Since #Proc_Concat and #Proc50 only have two columns in play here, PatientID and ProcedureCodes, one of them is throwing the error. 

Guessing not ProcedureCodes as it's pipe-delimeted so must be a varchar. 

That leaves PatientId.  Numeric data types can't handle the space character '1111111 11100', so that's the first place I'd look. 

Another possibility is within your subquery, P1.PatientID = P2.LbPatientID, in case one is a varchar and one is an int, and implicit conversion won't allow the varchar value to be converted to an int to test the equality.

Good luck.