In the context of the era of developing a low-carbon economy, emerging technologies are developing rapidly, and natural gas is gradually becoming the main force of primary energy in the future world. However, the development of natural gas storage and transportation technology is facing many problems, waiting for the world's scientific community to explore again and again.
Several storage and transportation technologies commonly used in natural gas include: compressed natural gas (CNG) storage and transportation, natural gas pipeline (PNG) storage and transportation, liquefied natural gas (LNG) and other storage and transportation technologies.
The world's LNG industry is in a period of great development and change, since the 1980s, facing the impact of two oil crises and the gradual exploration of more natural gas resources, people have recognized that natural gas is a more efficient and clean energy source than oil, and now, LNG has become the world's fastest growing trade volume of a new energy source.
"Heavy as Taishan": A small discussion on LNG storage and transportation technology
Natural gas, oil and coal are known as the three giants of primary energy in the world today, and the average annual growth rate of world LNG consumption in the past decade has reached 8.5%, which is far ahead of other primary energy growth rates in the next 50 years.
LNG storage and transportation technology cools gas to a liquid form of minus 162 degrees Celsius, compressing the volume to about 600% of the volume of natural gas at room temperature.
The world's natural gas is mostly distributed in Qatar, Russia, Iran and the United Arab Emirates and other countries, and the liquefaction of natural gas is low temperature, the expansion ratio of enterprises is large, easier to transport and store, and because the LNG liquefaction station is generally located at the gas well, the gas price is low and the gas source is sufficient, and the LNG transportation cost is only about one-sixth to one-seventh of the pipeline transportation.
With the continuous development of LNG storage and transportation technology, its cost will only become lower and lower, and the storage and transportation technology will become more and more mature. At the same time, in addition to the cost factor, the safety of LNG storage and transportation has also become the ace advantage of the technology.
Because LNG shipping has become the main convenient way for the current ocean voyage and the development and utilization of natural gas in remote areas, and to achieve long-distance transportation of natural gas, the total amount of natural gas transported has reached 25%, sharing the pressure of pipeline transportation, greatly reducing the various risks caused by insufficient gas sources to lay pipelines.
When it comes to energy characteristics, cleanliness and safety often go hand in hand.
LNG is judged to be the purest known "green" energy source on Earth. Its sulfur content is extremely low, the emission of sulfur dioxide for LNG power generation is only one-sixth of the sulfur dioxide emissions of coal-fired power generation, but its combustion calorific value is much higher than that of petroleum, the unit calorific value of LNG is 1.7 times that of standard coal, and 1 ton of LNG power generation can produce 1350 standard cubic meters of natural gas, with a power generation capacity of 8300 degrees.
LNG has a huge role in the adjustment of the world's natural gas, in today's world, Japan is the largest LNG importer, other major LNG importers are the United States. Greece, Turkey, France, South Korea, Spain and other developed countries in the world.
Due to the large increase in the demand for LNG in various countries in the world, the FOB price of LNG has risen all the way, the heat has not decreased, and the spot market transactions have become more and more frequent, which has led to the transformation of international LNG from the buyer's market to the buyer's market.
"Three high" product manufacturing: liquefied natural gas carriers
The entire LNG industry chain can be roughly divided into three paragraphs:
The first part, that is, the upstream stage of the LNG industry chain, has several links such as exploration, development, essence, separation and liquefaction;
The second part, that is, the middle reaches of the industrial chain, includes the transportation of loading and unloading ships, storage tanks and regasification facilities, and the construction of gas supply trunk pipe networks;
The third part, the downstream stage of the industrial chain, includes end-market users, such as industrial furnace users, city gas companies, distributed energy stations for buildings with multiple cogeneration of cooling, heating and power, and so on.
The rapid increase in world LNG production and trade has promoted the birth and development of LNG ships to a certain extent.
Before 2017, whether it was China, the United States or Japan, South Korea, Australia, the LNG carriers at their receiving stations were imported from French shipbuilding technology. Among the two types of LNG carriers, independent spherical and thin-film, there are also thin-film LNG ships - the unique technology from the French GTT company is superior to independent spherical LNG ships in terms of performance and ship type.
As an internationally recognized "three high" products - high difficulty, high technology and high added value, LNG ships are known as "super refrigerated trucks at sea" and the "crown jewels" of world shipbuilding.
If you are a seller, you can have a certain number of LNG fleets, which is conducive to the seller's transportation of excess contractless capacity; as a house to buy a house, owning a fleet can effectively reduce the cost of LNG transportation, so that the buyer is in a favorable position when signing a gas purchase contract, and at the same time can regulate LNG transportation according to its own market demand.
However, the necessity of China must develop the LNG transport shipping industry is more than this, because LNG is a special dangerous goods, the requirements for transportation technology are self-evident, LNG storage and transportation technology has been monopolized by shipping powers such as Europe, america, Japan and South Korea in a certain historical period, and the manufacture of thin-film LNG marine invar alloys is monopolized by France.
Therefore, there has always been an unwritten rule in the international shipping industry: if any shipping company can carry LNG, it has the first echelon to enter the international shipping industry.
If we can develop the mainland's LNG fleet, we will be able to optimize the combination of the mainland fleet, stabilize the environment of the mainland shipping industry in the pattern of the international shipping industry, enhance the competitiveness of the mainland shipping enterprises, open up the international shipping market, and expand the market share.
However, several difficult problems in the construction of LNG ships are mainly manifested in: the difficulty of designing the installation platform of the cargo compartment enclosure system, the difficulty of controlling the temperature and humidity environment of the cabin, and the difficulty of pre-outfitting implementation process.
As the core of the construction of thin-film LNG ships, the cargo compartment enclosure system consists of low temperature insulation material, outer film, inner film, and double-layer hull. In order to transport LNG with a temperature as low as minus 163 degrees Celsius, and to prevent the hull structure from cold cracking in an ultra-low temperature environment and causing LNG leakage, the inner and outer films of the cargo compartment enclosure system are made of Invar steel with a low thermal expansion rate.
Yinwa Steel is the french GTT company to dominate the key to the film-type patent technology, not to mention the value of Invar Steel itself, in order to make the internal and external film constitute a complete limit interface for loading cryogenic liquid goods, protect the hull structure from low temperature infringement and lead to brittle damage, it is necessary to ensure that the film and insulation box are installed tightly and in line with the specifications.
Why is it difficult to install? First, in terms of material properties, Yinwa steel itself is an extremely delicate alloy, 0.7mm alloy if it is touched by empty hands, it will rust through within 24 hours, contact with water and oil, and will rust to the entire steel plate within 8 hours.
Second, as far as loading and unloading technology is concerned, before that, the strength measurement standard for the installation platform of the liquid tank enclosure system system in China has been blank.
A set of standardized strength design balance is a process of continuous testing, but the film cabin of the Inwall steel is all introduced from overseas, and a slight damage to a place during the construction process will make a large piece of adjacent Invar steel film completely damaged, and it has to be replaced and re-welded, which is expensive.
This means that the construction process requires higher requirements for the flexibility of the installation platform and the patient and careful professionalism of the highest level of welders.
The distribution of ventilation air flow in the cabin of LNG ship construction is seriously uneven, the temperature difference between the top floor space and the bottom space is as high as 5 to 7 degrees Celsius, and even the same horizontal space also has a temperature difference of 3 to 4 degrees Celsius, which seriously affects the uniformity of the ventilation air flow organization, and this air flow organization uniformity is directly related to the problem of inwall steel rust wearing the bulkhead wall and the energy-saving operation of the air conditioning system.
The walls of the inwall steel chamber contain 36% nickel, so it must be precisely stable for temperature and humidity in the cabin. The construction site of the LNG ship must be equipped with air conditioning with dehumidification function to ensure that the dryness of the entire cabin is more than 60%.
Because most of the air conditioners at home and abroad use electric heating in winter and the single cold type of refrigeration dehumidification in summer, if there are dehumidification requirements all year round, it is necessary to run refrigeration for many months, and the cost of air conditioning operation in a year is a lot of money.
From the perspective of dehumidification demand, the construction of LNG ships needs to develop a set of specialized, high-precision, energy-saving dehumidification units, after all, the dehumidification unit required in the construction of a 150,000-cubic-meter LNG ship has an annual operating cost of 12 million yuan.
From the perspective of welding process, the construction process of LNG ships is complex and difficult to weld the cargo compartment enclosure system Yinwa steel, each welder has carried out more than two years of Yinwa steel welding tests, but in an air environment with a dryness of more than 60%, it is also necessary to ensure that the builder has 25% fresh air.
This is not a very generous number, and it is a serious challenge for both senior welders and the ventilation system of LNG cabins.
The most difficult thing is that most shipbuilding companies in the mainland show little awareness or unconsciousness about the planning of modern shipbuilding models. Some shipbuilding enterprises are seriously not active, their management capabilities are relatively weak, and the division of responsibilities is not clear. In the production stage of LNG vessels, great importance needs to be paid to the promotion of the pre-outfitting of the unit modules and the preparation of the pre-planning.
Whether it is logistics support, segmented manufacturing or equipment procurement, pipe manufacturing needs integrated management, rather than excessive heavy production, around the design. Construction and marketing, etc., are directly related to the departments that pick up and hand over ships, and the logistics supporting and production management departments are treated transparently.
Once fooled around in the overall planning process, there is a high probability that there will be a problem of rework due to defects, which will lead to more than 500 times the financial and labor costs under normal circumstances.
Therefore, the difficulty of building LNG ships is not only manifested in the continuous test of installing balances, the scarcity and high cost of Inwall alloys, the high difficulty of Inwa steel welding technology, etc., but also in subjective factors such as the lack of active and innovative pioneering thinking of local shipbuilding enterprises in the mainland.
"Long winds and waves will sometimes": China has broken through the technical difficulties of "card neck"
Liquefied natural gas as an important part of the continental energy structure, its proportion of the continent and even the world's energy structure is rising year by year, the continent's LNG imports mainly rely on LNG ships ocean transportation, therefore, the localization of LNG ship construction is an inevitable requirement to ensure the energy security of the mainland.
In 2017, China Classification Society issued a certificate of recognition to Baosteel Special Steel LNG Marine Invar Alloy. It was officially announced that Baosteel Special Steel has become the first manufacturer in China and the second manufacturer in the world to obtain the approval of thin-film LNG marine invo alloy after the French GTT company.
At this time, only four years have passed since Hudong Zhonghua Shipbuilding Co., Ltd. officially launched the scientific research project of the Ministry of Industry and Information Technology and comprehensively conquered the manufacturing technology of LNG marine Invar alloy.
No one could have imagined that the "Key Technology of LNG Marine Inwa Alloy and Insulated Box Plywood" that was not optimistic at that time could achieve such remarkable achievements today, so that the industrial trial production of Inwa alloy was successfully completed, and the performance fully reached the certification certificate of China Classification Society and the French GTT Company, announcing the official arrival of the era of localization of LNG marine Invar alloy.
In 2008, the first LNG ship on the mainland, "Dapeng Hao", was successfully delivered, and although the delivery time was late, it was a new record for the world's largest thin-film LNG ship at that time. In the blink of an eye, in 2017, Hudong Zhonghua Shipbuilding Co., Ltd. officially delivered 174,000 cubic meters of LNG transport ship "Pan Asia".
The Pan Asia is still the largest and most advanced large-scale thin-film LNG vessel independently developed and built by the mainland. As the first vessel of Australia's Curtis LNG project, the "Pan Asia" adopts an efficient biaxial system tilting arrangement, dual fuel generators, electric propulsion systems, equipped with re-liquefaction devices, and has created a standard specification for domestic thin-film cabin LNG transport ships.
Outstanding achievement of "becoming a rookie in LNG shipbuilding". Because it breaks through the "card neck" problem of Yinwa Steel, the most important raw material in the construction process of LNG ships, it effectively reduces the high price of products, effectively controls the construction cost of LNG ships, and greatly improves the independent construction capacity of LNG ships of Chinese shipyards.
China has become one of the world's shipbuilding powers, and its competitiveness in obtaining LNG ship orders has greatly improved, and China's ship construction, order volume and undelivered order volume are the first in the world.
From being far behind the shipbuilding industry in Europe, the United States, Japan and South Korea, to catching up later, China has become a shipbuilding power that can build 95% of the world's existing ship types, and China is moving step by step towards a maritime power.
Outstanding achievements include breaking the energy monopoly and ensuring energy security. The mainland's natural gas imports are also divided into two major modes: pipeline transportation and LNG ocean transportation. The drawbacks of pipeline transportation are obvious, first, the intake gas source is relatively single; second, through multiple countries and regions, strategically easy to be subject to people.
However, LNG transportation is more flexible, and for a long time, the only drawback is that building LNG ships is too cumbersome and arduous. Nowadays, the autonomy of LNG marine Yinwa alloy is in China's hands, and the "national transport of domestic goods" has been truly realized, and the commodities imported and exported by the mainland are entrusted to the mainland shipping enterprises as much as possible to ensure the transportation safety of national strategic energy.
Outstanding achievements in the greening of energy consumption. The huge breakthrough in LNG ship manufacturing technology also marks that LNG energy can be expanded in China, and even conducive to promoting the development of mainland energy consumption in the direction of green environmental protection, meeting the environmental protection requirements of national energy conservation and emission reduction.
Yin Wagang broke the monopoly of France, in the early stage, it was a huge impact on China's international status in ship transportation, but in the long run, this major technological breakthrough means that the development shackles of large-scale LNG ships and related industrial chains on the mainland have been broken.
The localization of LNG marine insulation alloys and plywood is a core technology with independent intellectual property rights in the field of shipbuilding in China, and it is also a thousand-year-old achievement in the history of China's manufacturing industry, which is of great strategic significance for promoting technological innovation, supporting industrial upgrading and building a manufacturing power.
"The cutest man" – approaching the National Treasure Technician
The ice iron is ruthless and exquisite. There is such a group of people, in the dry 60% air environment, wearing special sheepskin sweat-absorbing gloves, high-intensity hard work, they determine the sailing life and safety performance of the ship to some extent, they are the most lovely people in the ship industry - welding technicians.
The development of LNG marine Yin tile steel is of great significance, but how to serve these precious treasures is still indispensable to a national treasure level technician.
Zhang Dongwei is the head of the welding class of Hudong Zhonghua Shipbuilding Co., Ltd., who was invited to participate in the program "Big Country Craftsman", as a candidate for shanghai's "Labor Model person of the year", he made outstanding contributions to the mainland in the LNG ship manufacturing industry.
The platform of the ninth floor starts from the earth. An LNG ship has 4 cabins, a cabin a total of more than 30 kilometers of welds, Zhang Dongwei has repeatedly achieved the first density test zero leakage point - but the inspection standard is not more than 10 leakage even if it is qualified.
Welding craftsmanship is like embroidery, in the face of external temptations, groups of welding workers to fight all day with hot steel plates and smoke, covered with thick overalls, how difficult. Zhang Dongwei once said: "But every time I see the big ship I participated in the construction of the water, the pride that arises spontaneously can instantly squeeze the hard work to the cloud nine." ”
Zhou Weici is the winner of the 2019 "Shanghai Craftsman", the first female welding technician in China to have the G-grade certificate of Yinwa Steel Welding, and the hero of the welding industry called "China NO.1" by GTT welding experts.
The triphedron is an important component of the LNG marine liquid cargo compartment system, before that, the owner of the ship, based on the experience of shipbuilding abroad, concluded that Hudong Zhonghua could not independently complete the production of the triphedron, and it was recommended to purchase the finished product directly.
But at this time, Zhou Weici stood up: "Chinese will definitely be able to build its own LNG ship." With this belief, she took on the burden of triphedra welding.
Each triphedron is priced at 120,000 yuan, imported from abroad seems to be labor-saving, but if it is then dependent on the shipowner, Zhou Weici sat down, Hudong Zhonghua will not be able to master the key manufacturing technology of LNG ships for a long time in the future, then the shock wave of LNG marine Yinwa alloy, it will not be possible to produce combined benefits through exquisite welding technology.
Zhou Weici led the members of the research team, consulted the data, and constantly tried, and finally completed a complete set of system triphedron production and welding process. Experts and the China Classification Society call it a "Chinese miracle."
Behind the miracle is the day and night exploration and experimentation, the tenacious and indomitable spirit of scientists and doers, and the adventurer's mind that believes that "long winds and waves will sometimes hang on the clouds and sails to the sea". "Technology Bull" and "National Treasure Technician" have made arduous efforts for the real launch and voyage of LNG marine Yinwa alloys, and have made new contributions to the construction of the LNG industrial chain.
The so-called "Made in China" to "Created in China" is still based on the manufacturing industry, and the creation department has its own core concept and cutting-edge scientific and technological connotation of the process, behind this, from the scientific research end to the practice end, the indelible is the "craftsman spirit".
It is also all this that makes Yin Wa Steel, which has long been monopolized by France and cannot even be made in the United States, successfully developed independently in China for four years.
bibliography:
(1) Research on the Development and Application of LNG Industry in Mainland China
(2) "The Difficulty of Building LNG Ships"
(3) "Rich Country by Sea, China Ship: The Pearl on the World's Ocean"