I am salaried employee in the state of Washington and have been allowed to accumulate comp time to make up for extra hours worked.

1). I was only getting hour to hour instead of time and half
2). Our employee manual states that you lose accumulated comp time if you leave the company and will not be compensated for it.

Can I submit for the unclaimed time and half and will my employer be allowed to not pay me for the accumulated comp time when I leave the company.

Unless you work for a government entity, your employer is not required to provide you comp time (at any rate) and is not required to pay it to you at the time you leave.

FYI - The state does say that if an employer PROMISED to pay the benefit and does not, the employee can file a claim through small claims court or contact an attorney, re: filing a lawsuit. This does not apply to you so I believe that you don't have any legal stance upon which to base an appeal.