Air Pollution and Control of Cargo Handling Equipments in Ports

. In order to reduce and control air pollution caused by cargo handling equipments in ports, China’s transportation authority has proposed the goal of accelerating the elimination of old high -emission cargo handling equipments. This paper studies and constructs a dynamic method based on the level of cargo handling equipments activity to estimate the emissions of atmospheric pollutants. The results show that in 2017, if the engines of cargo handling equipment are upgraded and comply with Chinese standard Tier III, the air pollution will be significantly reduced. We show the ranking of the emission of air pollution of different type of equipment in ports. The government will make a good decision on air pollution and control with our research results.


Introduction
In order to prevent and control atmospheric pollution， and improve the quality of the atmospheric environment, China is fully implementing air pollution prevention and control measures. The Department of Transportation has proposed measures to accelerate the elimination of old high-emission cargo handling equipment in ports. Dieselpowered cargo handling equipment in ports emits gases such as SO 2 , NO x , CO, HC, PM and so on during the operation process. Due to their large varieties and distributions, the calculation of pollutant emissions has become a difficult issue.
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Diesel-powered cargo handling equipment belongs to non-road mobile machinery, so it should implement pollutant discharge standards for non-road mobile machinery, namely "Limits and Measurement Methods for Diesel Exhaust Pollutants Used in Non-Road Moving Machinery" (China Tier III, IV) (GB20891-2014) [1]. From April 1st, 2016, the standard stipulates that the manufacture, import, and sales of non-road mobile machinery equipped with Tier II diesel engines shall be stopped.
At present, the United States, Switzerland and other countries have developed official emission inventory of air pollution from non-road mobile [2,3]. Some researchers in the European Union, the United States, and China have done research on emission inventory of air pollution from non-road mobile [4,5,6,7,8,9,10,11], Tan Hua studied on emission inventory of air pollution from cargo handling equipment in ports [12]. The study used fuel method to estimate air pollutions emissions and emissions sharing rates in different kinds of the port in Shanghai. The study has established magnitude for the total discharge volume of diesel-powered machine in ports. However, Tan Hua did not consider the impact of the activity level of the machine, engine power and engine type on the emission of air pollutants.
Based on the survey of the quantity and activity level of cargo handling equipment in ports, we develop a kind of dynamic method for estimating the emissions of air pollutions from cargo handling equipment and its engines. We use this method to calculate emissions for older cargo handling equipment that meets the "Limits and Measurement Methods for Diesel Exhaust Pollutants Used in Non-Road Moving Machinery" (China Tier I, II) (GB20891-2007) [13]. The estimation laid the foundation for the subsequent formulation of government policies in China.
povince, Heilongjiang and Hebei Province, in addition to Shanghai, Chongqing, and Tianjin City.

Calculate measure
Based on the survey of the quantity and activity level of cargo handling equipment in ports, we develop a kind of dynamic method for estimating the emissions of air pollutions from cargo handling equipment and its engines, as shown in formula (1).
E, pollutant emissions ( t/a) , the types of pollutants include SO 2 ,NO x ,CO,CH,PM 10 and PM 2.5 Q, equipment quantity P, engine power (kW) H, working hours in one year (hours) EF, emission factors (g/kWh).

Parameter selection
Through the investigation we have obtained the following information including equipment name, equipment power, and date of manufacture, emission standards and fuel consumption in 2017. The example of equipment information is shown in Table 1.

Equipment quantity
Through statistics on the survey data, we obtained the number of different types of equipment equipped with Tier I and II diesel engines. The number of equipment engine (Tier I or II) is shown in Table 2. According to Table 2 , the total number of equipment is 7831 .The proportion of forklifts, loaders, yard tractors, dump trucks, trailers, side handlers, top handlers, rubber tired gantry cranes (RTG), and other equipments were 33.3%, 21.3%, 11.5%, 5.2%, 9.2%, 3.7%, 3%, and 9.6%, respectively.

Engine power
The power value is an important parameter for calculating the pollutant emission. We determine that the average power in a certain power range represents the power value parameter of formula 1. In order to obtain the average power, we first divide power ranges，then calculate the ratio of the equipment in different power ranges, and finally calculate the power average value. The power interval is divided according to Chinese standard of GB 20891-2007. We counted the number of equipment to be compared with the power range and calculate the ratio of the equipment in different power ranges. The distribution of equipment in different power ranges is shown in Table 3.

Working hours
An important factor in estimating emissions is actual working hours of equipment. The working hours are related to the type of equipment and the busyness of port. At present, there are few statistical data on working hours of diesel-powered cargo handling equipment in ports. We determine the working hours is 770 one year, which originates from the "Guidelines for the Preparation of Atmospheric Pollutant Emission Inventory for Non-road Moving Sources" by the Ministry of Environmental Protection [14]. Working hours represent annual averages of equipment operation.

Emission factors
The emission factor is usually affected by the degree of equipment degradation. Wear of the engine components of the equipment ， or the use of emission control treatment equipment leads to a reduction in the efficiency of the equipment, further causing changes in the amount of equipment pollutant emissions. At present, there are few actual measurement data on cargo handling equipment's air pollutant emission factors. The emission factors of PM 10 , PM 2.5 , HC, NO x , and CO refer to the Ministry of Environmental Protection's Guide to Non-Road Mobile Source Emission Inventory [14]. For the emission factor of SO 2 , we uses the fuel balance method to calculate, assuming that all the sulfur elements in the fuel are converted to SO 2 , and the common diesel used in the cargo handling equipment has sulfur content of 10 mg/kg [15]. The SO 2 emission factor is determined to be 20mg/kg. Diesel-powered cargo handling equipment emission factors are shown in Table 5.

Cargo handling equipment's pollutant emissions
Based on the above calculations, the pollutant emissions of cargo handling eqiupment equied with engine Tier I and II in 2017 is shown in Table 6. According to the type of equipment, the pollutant emissions is ranked from largest to smallest, the loader is the largest pollutants, followed by yard tractor, trailers, forklift, dump truck handler, RTG, top handler is the smallest pollutants. It shows that the emission of a certain type of equipment is positively correlated with the quantity of equipment and the power of the engine. The more the number of equipment distributed in the high power range, the greater the pollutant emissions. The loader engine has a maximum quantity of power distribution of [130,560)kW, and the total amount of equipment retained is the second, so the pollutant emissions is the largest. In order to compare the value of emissions from equipment which engines upgraded to III, we assume that in formula except for the change of emission factor, other parameters are unchanged, and calculate the pollutant emissions, the result is shown in Table 7. According to the type of equipment, the pollutant emissions is ranked from largest to smallest, the loader is the largest pollutants, followed by forklift, trailers, dump truck, RTG, yard tractor, top handler is the smallest pollutants. Comparison of pollutant emission reduction before and after engine upgrade is shown in Table 8. Therefore, the effect of less pollutant emissions is significant through upgrading the engine of the equipment, we recommend that the government can refer to the ranking of pollutant emissions when making decisions on the elimination of old high-emission equipment in the port.