4.4 Loading/Unloading Capacity
4.4.1 The loading/unloading capacity for railway transportation shall be determined according to the agreement reached between the owner and railway transportation company.And if there is no such agreement，the loading/unloading capacity may be determined based on the following principles:
a）The number of rail cars arrived to the plant shall be calculated by Equation（5）below:
where:
Md——number of the rail cars arrived to the plant at a time，Mdis taken as the total number of rail cars（50）of a train for mega-size plant，and as 1/3-1/2 total number of rail cars（15-25）of a train for mid-size plant；
Kb——unbalance coefficient of railway transportation；Kbshall be determined in accordance with Article 4.4.4；
Qd——daily transportation volume，t/d；
Nd——arrival times of the trains per day；Ndis taken as 2 times-3 times；
Qa——average net load capacity of the rail cars，t；Qais taken as 50t.
b）The allowable net stay duration of rail cars arrived to the plant shall be 4h for unloading and loading respectively.
4.4.2 The loading/unloading capacity for waterway transportation shall be determined according to the agreement reached between the owner and the port.And if there is no such agreement，the loading/unloading capacity may be determined based on the following principles:
a）The loading/unloading capacity shall be calculated by Equation（6）below:
where:
Q——loading/unloading capacity of the wharf，t/d；
Kb——unbalance coefficient of ships arrived to port；Kbshall be determined in accordance with Article 4.4.4；
Qd——daily transportation volume，t/d；
D0——annual on-stream availability of the process plant，d；
D——annual availability of the wharf，d.
b）The number of loading/unloading berths at the port shall，according to annual cargo throughput，specialized wharf types and design ship types for petrochemical service，be calculated by Equation（7）below:
where:
N——number of the berths；
Q——annual throughput（annual operating capacity）determined based on design capacity，t；
Pt——annual throughput of one berth，t；Ptmay，depending on wharf types，be calculated in accordance with GB/T 50192 and JTJ 211.
4.4.3 For road transportation，the number of trucks arrived to the plant per day may be calculated by Equation（8）below:
where:
Md′——number of the trucks arrived to the plant per day；
Qy——annual transportation volume，t/a；
Kb——unbalance coefficient of road transportation；Kbshall be determined in accordance with Article 4.4.4；
Dy——availability of road transportation throughout a year，d/a；Dyshall be determined according to local meteorological conditions and road traffic conditions；
Pa——average load capacity of the trucks，t；Pashall be determined based on truck types selected；
Ku——utilization coefficient of the truck load capacity；Kumay be selected from Table 2.
Table 2 Utilization Coefficient of Truck Load Capacity
4.4.4 The unbalance coefficient of transportation shall be analyzed and determined on specific cases.Where no information and data are available，the unbalance coefficient of transportation may be determined based on the following principles.
a）The unbalance coefficient of railway transportation，Kb，may be selected from Table 3 below.
Table 3 Unbalance Coefficient of Railway Transportation
b）The unbalance coefficient of waterway transportation（ships arrived to port），Kb，may be selected from Table 4 below.
Table 4 Unbalance Coefficient of Ships Arrived to Port
c）The unbalance coefficient of road transportation，Kb，shall be taken as 1.10-1.30.
d）Kbshould be the lesser of those given in the tables above for large transportation volume and better transportation conditions.