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Преимущества оптимизации путешествие
Преимущества оптимизации маршрута является:
- Оценка конструктивных особенностей судов и таких критериев, как скорость, изменение состояния моря, максимальный судовой ход и изгибающие моменты, неоднократно имитируя путешествия с помощью базы данных о ветре и волнах.
- Оптимизации развертывания и распределения судов для торгового пути, принимая во внимание расписание, безопасность, стоимость топлива и мореходные возможности.
- Оценки вероятного времени прибытия, чтобы терминалы могли более эффективно запланировать средства для выгрузки перевозимого груза.
- Продлить жизнь корпуса судна снижая стрессовые нагрузки на него.
Список литературы:
1. Журнал Digital Shipping. - 2013. - Январь. - С. 16-26.
2. Журнал Tankers Operators. - 2013. - Сентябрь. - С. 28.
3. Columbia Shipmanagment Operation Manual Part Navigation. - С. 17.
4. http://www.metoffice.gov.uk/marine/safesee.
5. http ://www.j ma. go .jp/j ma/en/Activities/pws.
6. SOLAS 74 Chapter II-1.
THE IMPROVEMENT OF STEEL DURABILITY FOR DREDGING OPERATIONS IN THE ASTRAKHAN REGION
© Шеленков А.А.*, Дементьева А.С.4
Астраханский государственный технический университет, г. Астрахань
Today Astrakhan is an important industrial and commercial centre, so we can see that not only roads and airports are necessary for trade and transportation resources, but also ports with their ships. Our region has got them, but there is a problem for large ships, that cannot sail in the Volga River, if depth of the river is not enough for it. Every year rivers and canals are buried in sand and mud during the spring flood, and therefore is an issue of their cleaning and dredging. Our river industry uses dredgers made of steel to
* Кафедра «Машины и аппараты химических производств». Научный руководитель: Дементьева А.С.
* Старший преподаватель кафедры «Иностранные языки в инженерно-техническом образовании».
control this situation, but steel can not remain durable in the water during long time. At present time only dredgers can deepen rivers in our region, but there are not effective ones at the moment.
Key words: dredger, bucket dredger, river, steel, repair, ship, navigable, bottom, mechanical, the most durable.
Dredger is a special boat with equipment for removing dirt and sand from the bottom of a river. This technology is often used to keep rivers and channels navigable. Dredgers may be classified into two basic groups depending upon the method used to transport grounds from the bottom to the water surface. There are many types of dredgers. For example:
Trailing suction. A trailing suction hopper dredger trails its suction pipe when working, and loads the dredge spoil into one or more hoppers in the vessel. When the hoppers are full, it is sails to a disposal area and either dumps the material through doors in the hull or pumps the material out of the hoppers. Some dredges also self-offload using drag buckets and conveyors.
Cutter-suction. A cutter-suction dredger's suction tube has a cutting mechanism at the suction inlet. The cutting mechanism loosens the bed material and transports it to the suction mouth. The dredged material is usually sucked up by a wear-resistant centrifugal pump and discharged either through a pipe line or to a barge. Cutter-suction dredgers are most often used in geological areas consisting of hard surface materials (for example gravel deposits or surface bedrock) where a standard suction dredger would be ineffective. In recent years, dredgers with more powerful cutters have been built in order to excavate harder rock without the need for blasting.
Auger suction. It looks like like a cutter suction dredger, but the cutting tool is a rotating Archimedean screw set at right angles to the suction pipe.
Jet-lift. These use the Venturi effect of a concentrated high-speed stream of water to pull the nearby water, together with bed material, into a pipe.
Air-lift. An airlift is a type of small suction dredge. It is sometimes used like other dredges. At other times, an airlift is used, handheld underwater by a diver. It works by blowing air into the pipe, and that air, being lighter than water, rises inside the pipe, dragging water with it.
Clamshell. A grab dredger picks up seabed material with a clam shell bucket, which hangs from an onboard crane or a crane barge, or is carried by a hydraulic arm, or is mounted like on a dragline. This technique is often used in excavation of bay mud. Most of these dredges are crane barges with spuds.
Backhoe/dipper. A backhoe/dipper dredge has a backhoe like on some excavators. A crude but usable backhoe dredger can be made by mounting a land-type backhoe excavator on a pontoon. A backhoe dredger is equipped with a half-open shell. The shell is filled moving towards the machine. Usually dredges material is loaded in barges. This machine is mainly used in harbors and other shallow water.
Pneumatic. These dredgers use a chamber with inlets, out of which the water is pumped with the inlets closed. It is usually suspended from a crane on land or from a small pontoon or barge. Its effectiveness depends on depth pressure.
Bed leveler. This is a bar or blade which is pulled over the seabed behind any suitable ship or boat. It has an effect similar to that of a bulldozer on land.
Krabbelaar. This is an early type of dredger which was formerly used in shallow water in the Netherlands. It was a flat-bottomed boat with spikes sticking out of its bottom.
Snagboat. A snagboat is designed to remove big debris such as dead trees and parts of trees from rivers and canals.
Bucket. A bucket dredger [Figure 1] is equipped with a bucket dredge, which is a device that picks up sediment by mechanical means, often with many circulating buckets attached to a wheel or chain. Some bucket dredgers and grab dredgers are powerful enough to rip out coral to make a shipping channel through coral reefs [1].
Fig. 1. Bucket dredger
Nowadays world industry produces mechanical and hydraulic dredgers. Astrakhan river industry uses only mechanical bucket dredgers, because they are the most suited for our bottom, which consists of solid ground. Currently there are seven bucket dredgers in the Astrakhan region.
Bucket dredgers are one of the oldest types of dredgers. They usually comprise a pontoon with a big central well. A bucket is a round open container with a handle, used for carrying ground such as sand. Dredger has got many buckets, which are located on the special scoop chain.
The process of dredging creates spoils (excess material), which are carried away from the dredged area. Dredging can produce materials for land reclamation
or other purposes (usually construction-related), and has also historically played a significant role in gold mining. Dredging can create disturbance in aquatic ecosystems, often with adverse impacts.
The dredging action starts, when a bucket reaches the bottom of the chain, where it loosens and scoops up the ground. It is carried in the bucket to the top, where at the highest point of the scoop chain, the bucket overturns and the contents are offloaded. Buckets are fixed with the help of pins and bushings [Figure 3], which are made of Hadfields steel. This kind of steel was developed by Sir Robert Abbott Hadfield, Baronet. He was a British metallurgist who developed manganese steel, an alloy of exceptional durability that found uses in the construction of railroad rails and rock-crushing machinery [2].
Buckets are attached to a chain with four fingers. Scoop fingers mate with bushes and pressed into the holes of the brackets. Material sleeves and thermo-treatment are the same as for the fingers. The mount is a swivel pins and bushings with the formation landings with gap ranges from 1.5 to 4 mm. In such a gap easily penetrate abrasives any faction. In operation dredger fingers and bushings are subjected to intense wear of the mutual friction through a layer of abrasive, so durability of these pins and bushings limited usually one season, after which the fingers and the repair sleeve is replaced by new ones.
Hadfield steel has two major features: first, the greater the external impact load, the higher the wear resistance of its surface; second, with the gradual wear of the hardened surface layer, new work-hardening layers will be formed continuously. It is suitable for wear applications, severe impact, abrasion and hadfield steel is needed. Serving the shot blast industry, mining, railroad, foundries, quarries and steel mills.
Hadfield steel has excellent wear resistance to strong shock and great pressure, they are easy to be cut and welded, but difficult to be machined, and although they have high hardness, their toughness is still very excellent and they can be bent to needed shapes such as cylinders.
Hadfield Steel is used wherever is required resistance to severe impact or high abrasion. This type of steel is one of the most durable in the world, but even pins and bushings made of this steel can not operate for more than two weeks in the water. Pins and Bushings scoop are shock-abrasion, in connection with which the performance of the metal should be considered, depending on three factors:
1. Internal defined properties and change the properties of the metal in the process;
2. External appearance characterizing friction mode, speed, load, the nature of force application;
3. Work environment.
The second and third factors require special analysis of more parameters dredge operation in abrasive wear resistance of steel. Wear resistance of steel in abrasive wear is proportional to its hardness [3].
So it is necessary to repair pins and bushings every two weeks. It is technically complex and very expensive operation. Therefore to solve problem of operation it is essential to carry out experiments on steel to search for the most durable steel grade.
We need to understand all the processes that occur during the operation, to carry out experiments and search for the most suitable steel for pins and bushings. It is impossible to simulate all the energies and factors in the laboratory, the same as in real conditions, because there is no machine that can simulate the abrasive and impact wear together. So it is very essential to create such machine. It can help us to increase in efficiency of the operation of the dredgers. In order to create a simple model of this machine it is necessary to reproduce in the laboratory smaller load than during the real working conditions. Real load is amazing.
In the conclusion, I would like to say, that Astrakhan region has not enough capabilities for experiments. Of course, there are a lot of smart people in our region, who can carry out experiments, for instance in Astrakhan state technical university, but there is no funding at all. It seems to me, government must understand, that this problem needs their attention, then we can solve it.
Список литературы:
1. http://en.wikipedia.org/wiki/Dredging.
2. http://global.britannica.com/EBchecked/topic/251104/Sir-Robert-Abbott-Hadfield-Baronet.
3. http://www.hadfield-steel.com.
