True solar time真太阳时
A BaZi chart is cast on solar time, not on the clock. The clock is a political convenience — whole countries share one time zone — and the sun does not care. This converts a birth time the way the chart requires, and shows every step of the arithmetic rather than just the answer.
What the three corrections are
Daylight saving
Removed first, because it is a clock change and nothing else. It catches people out: China ran daylight saving from 1986 to 1991, so a summer birth in those years is an hour off before any astronomy is involved.
Longitude offset
Your time zone is anchored to a standard meridian. Every degree you sit away from it is four minutes of real solar time. Ürümqi keeps Beijing's clock while sitting about 29° west of its meridian — nearly two hours of correction.
Equation of time
The Earth's orbit is elliptical and its axis is tilted, so true solar noon drifts against clock noon over the year — up to about ±16 minutes. Small, but it is the difference that decides a borderline hour pillar.
This is the raw calculation. What the resulting chart means is a different question — start with the five elements, orlook up a term.