how should i send data form my custom module to a php file after submitting?
If all you are doing in your submit handler is redirecting to result.php then you should instead make your form submit direct to there, so that all the form post values will be available in the $_POST global variable in result.php.

To do so, in your my_module_my_form() function add this:

$form['#action'] = '/result.php'


Edit:

As Clive has pointed out, you cannot post that field value as you currently have it because it is a disabled field.

To make that field post you either have to make it not disabled, or if you don't want the user to be able to edit it you can use a different field type.

You can use type value to pass a value straight through, however the user won't be able to see it before they submit as it is a type of hidden value.

If you want the user to be able to view the value but not change it you could have 2 fields, one disabled (or just an item field) one that the user can see but doesn't submit, and a second value type field that submits the value.