sess_expire_on_close

Hello everyone...
I know, what in 3 version this param sess_expire_on_close was delete.
How remove session after close browser?
Okay. I know if set config sess_expiration = 0 session close ...

but if I make

PHP Code:

$this->config->set_item('sess_expiration', 0);
$this->load->library('session'); 


not work, load only 

PHP Code:

$config['sess_expiration'] = 600; --> config.php 


config.php



but when I show var_dump($this->config->item('sess_expiration')); I see = 0, but if I close browser and open again session live..., if I change sess_expiration = 0 in config.php file - session die after close browser.