sergofedor06,
 
var flag;
    $('body').on('click', "#comments_add_form input[type='submit']", function (e) {
        e.preventDefault();
        var el = this;
        if(flag)return;
        else {flag = true;
el.setAttribute('disabled', 'disabled');
window.setTimeout(function() {
    el.removeAttribute('disabled');
    flag = false;
}, 10000)};
        var user_name = $("#comments_add_form  #user_name");