Jiangsu huata recently served a state-owned mould enterprise in hebei province, using HBY type closed cooling tower to cool gun drill bit. The project was successfully delivered and accepted. The closed cooling tower generally has two ways for cooling the gun drilling oil. 1st is the directly output oil into closed cooling tower for cooling, this way heat transfer efficiency is fast; Another way is to use heat exchanger for indirect heat transfer. The closed cooling water system is at the other end, providing cooling water circulation in the system below 32℃. This project has accumulated rich experience in hot oil cooling for Huata.