I am in Thailand with tourist visa and doing medical for my wife. I need China visa. Pls advice.

I am a marine chief engineer & Bangladeshi.
We came here with tourist visa and now my wife is under medical treatment. some more days she need to stay here.
Now company requesting me to join ship from china port.
Please advice, can I get single entry china visa from your Bangkok Thai embassy & what documents need. FYI, Earlier also I joined & sign off from china.
Please advice.