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Development and application of centralized air purification system in pipe welding workshop
Jan 30, 2019

Introductions 


With the rapid development of China's economy, environmental problems are increasingly prominent and have gradually become the main factors restricting the sustainable development of enterprises.Internationally, environmental issues have become an important part of international conventions and even become a tool for developed countries to restrict market access and promote non-trade barriers.In China, due to historical and economic reasons, environmental factors have become the primary cause of occupational diseases. The prevention and treatment of occupational diseases and the rapidly developing economic level are not suitable enough. Occupational diseases have become a major public health and social problem in China.In accordance with the international and domestic conditions and development trends, China has raised environmental protection to an unprecedented level, adopted and formulated a series of environmental standards, strengthened supervision and management of enterprises, abandoned the old practice of "development first, governance later", and implemented new measures of "three simultaneous" and "digestion while developing".We will resolutely close, stop, merge, transfer and relocate enterprises that have long been found to be seriously polluting the environment.


  1. Significance of developing air purification system


At present, there are 5 sets of spiral submerged arc welding pipe production units in the headquarters of huayu steel pipe co., LTD., with an annual production capacity of more than 30 x 10 spoons.Submerged arc welding and plasma cutting are two important processes in steel pipe production. In the process of welding and cutting, a large amount of smoke and dust will be generated.According to the measurement, in the peak production period, the workshop pollution index will reach more than 300, and only the welding and cutting section of the first branch of China oil & steel pipe co., LTDThree to five kilograms of suspended particles are produced in three days.The negative impact of serious environmental pollution is mainly reflected in: (1) damage to the physical and mental health of employees, so that the cost of physical examination, health care, and so on increase;(2) erosion of equipment (such as Lincoln welder, etc.), resulting in shortened service life of equipment, and even affect the production;(3) affect the electrical system, resulting in the distribution cabinet switch, contactor and other heating, causing electrical failure;(4) it is difficult to successfully through the national environmental protection department monitoring, and may even be related to the punishment;(5) damage the enterprise good image, weakened the soft competitiveness of the enterprise. Based on the above reasons, the company determined to invest the corresponding human resources, material resources and financial resources to develop a new type of environmental protection, energy saving, economic and efficient dust removal system.


2. Development of centralized air purification system


2.1 selection of schemes


Although there are many principles and methods for dust removal, it is not easy to find an economical and efficient way for large production workshops, especially those with more pollution sources, complex pollution conditions and heavy pollution levels.


The second branch of huayu steel pipe co., ltd. has been adopting ventilated dust removal, that is, installing axial flow fans on the walls of the workshop with serious pollution to discharge smoke, dust and other pollutants from the workshop.This kind of dust removal method is simple economy, but there is a certain defect: (1) only suitable for closed loosely between the car;(2) only suitable for dust pollution concentration;(3) dust removal efficiency is not high, the purification rate is only about 40%;(4) dust removal is not complete, although reduce the pollution in the workshop, but the air pollution outside the workshop, can only be regarded as pollution transfer, can not be regarded as a complete treatment.



Obviously, this kind of ventilated dust removal method is not suitable for a branch factory which is closed tightly and has many pollution sources.After comprehensive analysis, and combined with the actual production of a branch plant, decided to adopt the centralized purification system.The working principle of the centralized purification system is to form a negative pressure inside it, and suck away the jiong dust and suspended particles in the t-position of the key smoke and dust in the workshop through the pipe, and use the efficient filtration method to separate the harmful substances from the air, so as to achieve the purpose of purifying the air.The separated dust is collected through the collection box for centralized safety treatment.


2.2 selection of suction inlet of centrifugal fan



The suction inlet of the centrifugal fan can be divided into trapped drum type, conical drum type and curve type, as shown in figure l.The suction population has the function of gas collection, which can directly extract gas in the environment and make the air flow evenly into the system.Considering that the workshop space of our company is large, the amount of air to be dedusted is large, and the suction efficiency required is high, the curvilinear suction population with the minimum air loss is selected, but the production process of this suction population is relatively complex.



2.3 design of articulated suction arm


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The suction arm consists of a parallelogram strut supported by an internal spring, a pvc-coated fiberglass tube and an internal spiral wire with five joints.The suction hood with throttle valve can be 360.Rotation, so that the suction arm can be extended to the length of its arm to any position, and can be automatically fixed in a certain state of position to absorb harmful fog and dust, no longer need other auxiliary facilities.The air suction hood is provided with a handle and a rotary throttle valve with adjustable air volume, making it convenient to use.The suction hood can be placed in the optimal absorption position regardless of the state of the smoke. The on-site use photos of the suction arm are shown in figure 2. The length of the suction arm is 2-4 m, and the actual length can be determined according to the actual location of the dust generation station.



2.4 design of suction hood


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The suction hood is equipped with a rotary throttle valve with a convenient handle and adjustable air volume, which can follow the suction arm 360.Rotation, easy to use and flexible.Whether the welding tee is located on the side or behind the suction arm, the suction cover can be placed in the optimal absorption position.