How to store and transport combustible fuel?

Because most energy applications are limited by specific time and place conditions, combustible fuels are favored because of their convenient storage and transportation. In fact, the appearance of trains, steamboats, automobiles and airplanes, on the one hand, makes the transportation industry the largest energy consuming industry, on the other hand, it also highlights the importance of energy storage and transportation characteristics. Furthermore, whether energy can be transported to energy-intensive areas is very important to promote industrial development. In the United States, steel cities are mostly developed near coal mines, because steel mills need a lot of energy, and the amount of coal used for steel processing is more than that of iron ore itself. In this way, locating steel mills near coal mines will save a large part of fuel transportation costs. Later, with oil and natural gas occupying a major position in the energy market, its convenient transportation characteristics changed the priority of steel plant location.

Coal is solid, so special gathering and transportation technology is not needed. Centuries ago, pulling coal and even bagging it by horse-drawn carriages were carried by manpower, similar to carrying firewood or charcoal. When replacing old and new resources, the new resources must be as close as possible to the old resources in terms of performance, storage and transportation. Obviously, coal has this advantage.

After the expansion of coal mining scale, the coal dump began to be used at the entrance of coal mine. The original coal dump was just a big box, and the coal truck could pour the coal into it, so it was also called a dump. Dumps are particularly effective for coal mines dug along gables: after coal is dumped into the dump at the exit of the coal mine, it is stored there until the truck pulls it away; When the truck loads coal, the closed door at the bottom of the coal unloading yard will open, and the coal will automatically fall into the truck compartment by its own gravity. This storage and transportation technology is very important because of the railway. At present, it has become the main facility of coal storage and transportation, generally located near the entrance of coal mine. Even open-pit coal mines have large coal dumps, which unload coal onto the old railway wagons. Although it is necessary to lift the coal to the dump, the process takes a short time, and the dump is equivalent to adding another storage yard to the coal mining site.

In modern coal mining operations, before the coal enters the dump, the large coal is usually crushed to make its particle size relatively uniform. Crushing can improve the efficiency of final combustion, which may be the only treatment process needed before coal retailing. Coal usually contains a lot of sulfur and mineral ash, and it is best to remove these pollutants before sale and use. However, these pollutants are closely combined with carbon-containing components, so it is difficult to treat them (there are occasionally large pieces of pyrite in coal, mainly containing sulfur, which can be separated by mechanical methods). Modern industry usually uses pulverized coal, but in the early 20th century, lump coal was very popular in the market, because they were too big to pass the screening screen, so the price was cheap, just the cost price.

Coal is usually transported by direct freight train, and there are generally 100 cars, and the load capacity of each car is about 100 tons. At the intersection of railway and highway, a motorcyclist is waiting for a coal truck to pass by. The coal truck seems to have no end in sight. This kind of direct freight train, which is specially used to transport coal, will return immediately after transporting coal to the consumption place (empty car return), and then fill a car with coal to start the next transportation. Coal trains can transport coal to buyers 65,438+0,000 miles away or even farther away. At present, the richest coal fields in the United States are in the Rocky Mountains. Because of the low population density and moderate coal consumption, most of the coal produced here is transported to distant and more densely populated areas.

Barges and cargo ships are also used to transport coal where there are waterways. One of the purposes of the Erie Canal, an artificial canal dug along the eastern part of the Great Lakes in North America, is to transport coal. The ability to transport coal (and other bulk products) cheaply based on the huge interconnected lake transportation network has promoted the development of many metropolises in this region of the United States. Waterway transportation is more effective than land transportation, but not as direct as land transportation (natural waterway direction is not conducive to transportation, and canals are limited). In 1980s, barges were second only to railways in American coal transportation, accounting for 65,438+06% ~ 65,438+07% of coal transportation (Note 2).

There are some differences between inland river barges and ocean freighters carrying coal. The bottom of the barge is flat, not V-shaped, and it is not a motorboat. Its advantage is low cost and it can travel to and from shallow rivers. However, its disadvantage is that the flat-bottomed design can not withstand the wind and waves, and it is not suitable for ocean transportation. Even in the Great Lakes where storms often occur, its application is very limited.

In 1970s, a more effective mode of coal transportation received strong attention-pipeline transportation. In fact, pipeline transportation is a variant of artificial waterway excavation, which is more effective than any ground transportation. In general, pipeline transportation can be realized. Compared with other modes of transportation that require heavy vehicles, pipeline transportation only needs to move the goods themselves. However, coal is solid, so a carrier medium is needed. It is generally recommended to use water as this medium, so the well-known coal slurry pipeline appeared. The use of water medium will offset the saved vehicle cost, but there is still a less obvious difference between the two modes of transportation, that is, the overall efficiency of internal combustion engine driving ground vehicles is very low, and the operation efficiency of pipeline pump is much higher.

The main function of coal slurry pipeline is to grind coal into particles to form coal slurry or suspend coal in water. Because coal is basically insoluble in water, some surfactants are needed to keep it in suspension. The density of coal and water is similar, which helps to mix them. After that, the coal slurry can be pumped into the pipeline and transported to distant consumers. Finally, coal slurry must be separated from water at the place of use.

The insurmountable obstacle encountered in coal pipeline transportation is huge water consumption. The United States had planned to build a coal pipeline between the Rocky Mountain area and the eastern part of the United States, but because the Rocky Mountain area belongs to semi-arid area, local residents objected to supplying its limited water source to the more humid eastern area. Supporters of the pipeline assured residents that they would not use drinking water, but would extract salt water by drilling wells. However, residents doubt that pumping groundwater may affect the circulation of groundwater, and even cause shallow fresh water to be pumped into the confined salt water layer. Research shows that this situation is unlikely, but there is no guarantee that it will not happen, and there is not enough information on underground structure and seepage law to rule out this possibility. For example, if there is an unmonitored longitudinal fracture connecting the shallow and deep water layers, shallow fresh water may flow into the lower formation to replenish the produced salt water layer. Railway companies also oppose pipeline transportation based on economic interests, but the pipeline transportation of coal eventually died because the water medium problem could not be solved. In the end, the party opposed to pipeline transportation won by vetoing the control right of slime pipeline. The so-called dominance refers to the right of way that roads, expressway and pipelines can force landowners to rent or sell their property territory according to the law.

At present, only the Heimesa pipeline has weight. It transports 5 million tons of coal from Utah to California every year, which is equivalent to the transportation of a semi-coal train every day (Note 3). Up to now, most of the coal is still transported by rail and barge. After coal is formed, it is far away from its original plant state, and it can be stored simply and directly. It will not attract termites and similar insects, but coal dust will cause environmental problems, and the coal storage area is also a flammable and dangerous area.

Oil and gas

The transportation of fluid energy, especially on land, is much more efficient than solid fuel, and it also causes many short-term problems. In Pennsylvania, in the first decade of the oil industry, oil was transported in wooden barrels. Early barrels could hold 42 gallons of oil per barrel. Although they are no longer used, they are still used as units of measurement for oil. Derek's famous well has a daily output of 65,438+00 barrels, which undoubtedly provides good job opportunities for local barrel makers. But imagine that the first high-yield well appeared two years later, with a daily output of 3,000 barrels. How does this affect barrel manufacturers? Oil producers can't store such a high output even if they buy barrels or even build oil storage tanks. Oil overflowed from hastily built containers and flowed from mountains into streams and rivers. The increase in output exceeded the demand, and soon the container was more valuable than the black gold it contained (Note 4).

/kloc-in the second half of the 0/9th century, road design was mainly aimed at horses or two-wheeled carriages, and roads in cities were mostly paved with pebbles or bricks. In the mountains of western Pennsylvania, where the oil industry began, muddy roads hindered the transportation of oil to consumers. In order to restrain silt and facilitate the passage of heavy oil tankers, local logs were laid across the road, which reduced the probability of oil tankers falling into the quagmire, but it was not sustainable.

Oil rushed from the well to the ground and was basically out of control at the beginning. The shortage of oil drums and the slow delivery speed of oil trucks have made the development of oil industry encounter bottlenecks. A large amount of oil is blocked at the wellhead, and the oil often overflows the storage tank, because the early flowing wells have been flowing until the pressure decays. Before Derek, there was also oil production, but only oil naturally leaked from the surface of the stream. The first batch of wells after drilling greatly increased the output, and collecting oil from the ground was not much different from the early natural skimming. Some oil producers even blocked the gullies and formed an oil storage pool. Farmers downstream obviously disapprove of this technology. Although there were no environmental regulations at that time, most operators would consciously clean up their products as much as possible.

The shortage of barrels is increasing, and the storage and transportation volume is increasing rapidly. Soon, the first oil pipeline was laid. From 1863 to 1865, several oil gathering pipelines were installed and connected with a main pipeline, which transported oil to the first railway station. The first large-scale pipeline, named Tidewater, connects the western oil-producing area of Pennsylvania with the eastern border of Pennsylvania and the Reading Railway oil depot located at the east of Williamsport 109 mile. The pipeline was put into production on May 1879. The maximum diameter of the pipelines built before is 3 inches, and none of them are more than 30 miles long, and they have not passed through areas with great terrain changes. The length of the tidal pipeline tripled, reaching the longest length at that time, and the diameter of the pipeline reached 6 inches. It crossed the Appalachian Mountains in the middle of winter (Note 5).

The motive of laying such a pipeline is not to improve efficiency, protect the environment or save costs, but to break the control of J.D. Rockefeller's Standard Oil Company. After Rockefeller Standard Oil Company reached a large enough scale, it planned a notorious kickback transaction with the railway department. These transactions not only transport Standard Oil Company's oil to its refinery at a lower price, but also pay an extra fee to Standard Oil Company, which is the freight paid by its competitors (Note 6). This kind of market control enables Rockefeller Company to effectively implement buyer's monopoly-the company buys most of the total output, and then can set the price of crude oil. The first oil pipeline is mainly under the pressure of rising freight rates constantly put forward by local tanker drivers. Facing the new market pressure brought by Rockefeller, oil producers jointly built this unprecedented tidal pipeline to break through Rockefeller's control and open up new markets. Interestingly, the early Rockefeller Standard Oil Company was not an oil company, and Rockefeller firmly believed that oil refining and sales would be more profitable. Unfortunately for these small oil companies, Rockefeller quickly responded to their motives: within two years, Standard Oil Company laid pipelines to Cleveland, Buffalo, Philadelphia and new york, and regained control of the downstream. Rockefeller's practice of destroying competition made many market competitors and oil producers suffer the pain of burning their bridges, which eventually led to the introduction of anti-monopoly law by the state. The leaders of many companies tried to maintain their independence and were extremely indignant at unfair competition, but the practice of Standard Oil Company interrupted the backbone of these companies, but Rockefeller described this practice as establishing order and improving efficiency in a turbulent situation. The struggle to establish order has indeed brought unexpected results, that is, by laying pipelines, a large amount of oil can be transported, and oil leakage accidents can be reduced, thus greatly eliminating the damage to the environment.

Pipeline quickly occupied interstate transportation, and it has advantages in almost all aspects. Its product loss is small, which means less damage to the environment; Large transportation capacity, low energy and material input. Because the concern for environmental protection tends to the edge of legislation, engineering design should make pipelines safer. When the consortium under ARCO, Exxon and BP raised funds to lay Alyeska pipeline, many pressure sensors were installed on the pipeline. The pipeline starts from the northern slope of Alaska and reaches the open waters of Valdez Port. In case of leakage, the pressure of the pipeline will be reduced, and a valve upstream of the leakage point will be automatically closed to prevent more oil from flowing out of the leakage point, which may reduce the oil leakage in all accidents.

Although it was reported in the 1990s that the inspection and corrosion control of Aliyeska pipeline were inadequate, its safety was questioned. But from a technical point of view, it is feasible to improve the safety of the pipeline. As early as 20 years ago, Arie Ska Pipeline adopted a series of advanced engineering design technologies at that time, which not only reduced the risk of oil leakage, but also solved a series of environmental problems. At present, if this famous pipeline is in danger, the degree of danger is still uncertain, so as long as it has economic value, the repair technology is available.

Obviously, the larger the diameter of the pipeline, the more fluid is transported; Similarly, for a given pipeline, the greater the pressure of pumping liquid or compressing gaseous fluid, the greater the conveying capacity (the general equation used by engineers for design is given in the appendix). The pipeline cost is directly proportional to the size and strength of the selected pipeline, and the construction including pipeline laying may account for a large part of the project cost. Therefore, the installed pipeline should have sufficient transportation capacity to meet the expected transportation requirements. If there is a new oilfield development, the design size of the pipeline should meet the requirements of total throughput. In low-income countries, the output may be limited by demand, so the pipeline should be optimized to meet the expected energy demand at the delivery point.

Most modern pipes are made of steel, but now some small applications sometimes use high-density polyethylene pipes. The pressure of polyethylene is lower than that of steel pipe, so it is limited to small pipe diameter, but the installation cost is low. It does not need heavy trenching equipment and welding machine to ensure each joint. Only narrow trenches dug by plow facilities can be used to install polyethylene pipes, and simple hot-melt instruments can be used to connect the pipes, which takes less time than welding and has low technical proficiency. This technology shows a certain prospect in transporting oil and gas to small markets in low-income countries. Empresa Nacional de Hidrocarbonetos installed a medium-sized polyethylene pipeline in 199 1, which currently supplies gas to a city with a population of 50,000. The gas comes from a gas field discovered 30 years ago, but it was previously considered uneconomical and could not be put into production.

tanker

Pipeline transportation of liquid fuel is an effective method. Since the 20th century, the amount of oil transported by land pipelines has greatly increased. However, under the current economic and technical conditions, the cost of overseas pipelines is too high, so sea transportation seems to be the only feasible solution to transport products from the production place to the consumption place.

The first successful bulk tanker was the "Suo Roya Zoroaster", built by Ludwig Noble and used to transport Russian-made oil by sea. The ship was launched in 1878, which is far from the ship loaded with barrels of oil or volatile and explosive kerosene (Note 8). During World War II, the United States built 525 oil tankers to provide fuel for the Allies. The code name of these tankers is T-2, and the total weight of each tanker is 16000 tons, including crude oil, fuel and self-weight. These tankers are nearly 400 feet long, and many of them worked until the 1970s. 1962, the oil tanker Manhattan made a trial voyage with eight times the capacity of T-2, and its deadweight was 1 16000 tons, but it was only half of that of the super tanker. By the 1970s, oil tankers had become surprisingly huge, and the so-called supertankers occupied the market. These supertankers are more than 400 yards long, loaded with more than 2 million barrels of oil, and stopped driving at half speed for 65,438+0 miles (Note 9). Supertankers are not often used for ocean transportation, but large tankers and larger supertankers (VLCC and ULCC respectively) are often used.

VLCC (Large Oil Tanker), an oil tanker with a deadweight of over 200,000 tons; ULCC (Super Giant Oil Tanker), an oil tanker with a deadweight of over 300,000 tons. . The increase of tanker size is not only based on "if it is big, the bigger the better", but also because of the development of giant oil fields in the Middle East, Alaska and South Asia, the oil production capacity has increased greatly, and correspondingly, developed countries need to import a lot of oil. The international demand for oil continues to grow, which requires an unprecedented economic scale and load capacity of oil tankers in order to transport more oil to industrialized oil-consuming countries.

The impact of the accident on the supertanker was shocking. There have been several large oil tanker accidents in the past, but none of them have attracted the attention of the media (mainly American news media) like the oil spill accident of the first super tanker in American waters. The party involved in the accident was the notorious Exxon Valdez, just outside Valdez Port in Alaska. Although Valdez can't be listed as the largest supertanker (at best, it can only be regarded as VLCC), and the oil leakage is only one-sixth of that of Amoco Cadiz, a French coast1years ago, this accident has aroused great public anger against the offshore oil transportation industry (note 10).

Ironically, hostility to overseas oil transportation is mostly aimed at unrelated offshore drilling, but in fact, these hostility should be aimed at the use of supertankers. But the logic seems to be that under a certain import demand, although the use of super tankers has a great impact on accidents, the use of small tankers means increasing the number of tankers and more frequent exchanges, which in turn leads to more accidents. Countries whose domestic energy production cannot meet the demand must rely on imports, and overseas oil transportation is a high-risk activity. The discussion on environmental protection policy will be left to the chapter "Impact of energy application".

Modern supertankers reduce the possibility and severity of accidents through a series of special designs. These tankers have several completely separated cargo holds, so that the damage of a part of the hull will not endanger the whole cargo ship (so Valdes only leaked one-fifth of the cargo capacity in the early morning of the tragedy). Oil tankers are equipped with computers, navigation equipment, safety and monitoring equipment, but the early oil tankers lack mature technical equipment, so it will take several years for a truly successful oil tanker design to come out. The first transatlantic tanker put the oil in wooden barrels before loading, and even put the refined kerosene into the warehouse of a conventional cargo ship. When the barrel moves or breaks, oil overflows into the cargo hold, and kerosene smoke is ignited by an open flame lamp. Before the concept of oil tanker sealed cabin was introduced, some oil tankers didn't have any specific pathogen free at all. Waves would cause waves in the cargo tank, which increased the impulse of waves acting on the oil tanker, and then increased the possibility of oil tanker capsizing. Modern science and technology have solved this problem.

Natural gas transportation

It is convenient and efficient to transport natural gas by pipeline. Before the oil industry appeared, natural gas was transported to big cities through pipelines for home and street lighting. However, natural gas is not the best energy source. In the early days of the petroleum industry, a large number of gases were vented and burned (this practice has not been completely eradicated so far). Even if most American families switch to natural gas for cooking and heating, natural gas is still second only to oil. So the natural gas market has been depressed. 1954 The U.S. government decided to control the price of natural gas, which also aggravated this depression. The other obstacle of natural gas pipeline transportation is gas storage.

The earliest industrial gas was coal gas produced from coal seams (as mentioned above). It is generally believed that William Murdoch, a Scottish engineer, was one of the pioneers in using natural gas. He installed a gas lamp in his hometown of Cornwall on 1792. In the same period, many people also did many experiments using gas, and many of them were successful, such as the lighting installed in George Dickerson 145 years ago, but the success of Moddock provided great impetus for the development of natural gas industry. In the early days, wooden pipes were used to transport liquids. In the first 20 years of natural gas industry, the development of natural gas industry was limited, because the gas could not be stored and the excess gas was vented and burned. 18 16, Samuel Clegg developed the first gas storage tank. The water tank is sealed with water, which will pollute the gas, but it was not until the turn of the 20th century that dry gas storage tanks appeared. Before mannesmann piercing technology was used to manufacture seamless steel pipes, steel pipe lines did not occupy a major position in the market, but in England, gas transmission by pipeline was very common as early as 200 years ago, and it is said that China used bamboo pipes to transmit gas 3000 years ago (note 1 1).

Early successful wooden and steel pipelines are generally smaller and have lower working pressure. Natural gas usually only flows through local pipelines, and there are some regulators to control the natural pressure of oil wells. When the reservoir pressure drops to the point where gas can no longer be pushed to the surface at a pressure higher than the pipeline pressure, this pressure point marks the end of the production life of a well, which is also common during the writing of this book. If the gas field is large, a compressor can be installed to receive the produced gas at low pressure, and then the pressure can be increased to the pipeline pressure to maintain cost-effectiveness.

With the increase of natural gas demand, it becomes profitable to lay large-diameter high-pressure main pipeline. At present, many gas pipelines are more than 3 feet in diameter, and some even exceed 5 feet. These pipelines transport a large amount of natural gas to the natural gas market in developed countries, and they have to be pressurized by several compressor stations along the way.

In order to store a large amount of natural gas or transport it through pipelines, it is necessary to compress the gas at high pressure or liquefy it in extremely cold state. Liquefied natural gas (LNG) is a storage measure, but it can also be used as a mode of transportation. LNG cargo ships transport natural gas to Japan from all over the world. The oil storage capacity of transoceanic LNG carriers is generally 125,000 cubic meters, which can hold three quarters of 65,438 billion standard cubic meters (under atmospheric conditions) or nearly 8 billion standard cubic feet (note12).

Compressed natural gas (CNG) has attracted more and more attention as an automobile fuel. CNG can store enough energy in the limited space of automobile fuel tank. The storage efficiency of compressed gas under safe pressure is not as high as that of liquefied gas, but it is difficult to maintain the low temperature of liquefied natural gas on the road. Therefore, although the efficiency of CNG is low, it is enough to maintain a reasonable mileage range. CNG and LNG have passed the bus test, and buses in the city no longer need to find gas stations to refuel. The analysis shows that the fuel performance of natural gas is better, but its cost is still slightly higher than that of diesel (note 13).

biofuel

Most biofuels used to obtain energy are in the form of firewood or charcoal, and their transportation modes are usually trucks, trolleys or even manual handling. Firewood can be stored and piled up. In the United States and western Europe, the traditional method is to bind with ropes. 1 A bundle of firewood is usually 4 feet high, 4 feet long and 8 feet wide. The chemical energy content of 1 bundle pine is generally 27 million British thermal units. Wood can undergo many cycles of wet and dry changes, but it must be dried before it can be burned. But the main problem of firewood storage is to prevent termites, ants and other small animals from biting.

Because of the low energy density of firewood and the large collection and transportation, the energy consumed by transport trucks will offset some of the energy obtained from firewood. Suppose that starting from one point and driving 20 miles in all directions to collect firewood, the energy consumed by trucks only accounts for 65,438+00% of the chemical energy of firewood, which will fluctuate according to the condition and efficiency of trucks. In countries where fuelwood is the main fuel for residents, the quality (volume) of fuelwood itself seriously affects the economic benefits of fuelwood merchants, so fuelwood is often processed into charcoal before being transported out of the forest.

Charcoal is much lighter than logs, and most of the water volatilizes during the transformation, so the energy density of charcoal is higher. Consumers' preference for charcoal may also promote this conversion, but transportation efficiency plays a greater role (when the fuel cost of cooking can only account for one-third of their income at most, these people are unlikely to pay another fee just because of the convenience of charcoal), and the improvement of transportation efficiency is enough to offset the energy lost in the process of converting firewood into charcoal. The degree of efficiency improvement depends on the transportation distance. In low-income countries, the forest area is gradually decreasing, and the transportation distance may reach hundreds of miles. When residents (mostly women) go out, they may have to walk 20 kilometers (12- 13 miles) in all directions to collect firewood and transport it home for cooking. In some areas where firewood is scarce, firewood collection activities may take up 30% ~ 40% of women's time. From the perspective of energy conversion, manpower is more efficient than automobile transportation, but because it takes a long time, the productivity is very low (Figure 3. 1).

Figure 3. 1 Source: Mrs. Nancy Polling, Rochester, New York. The prospect of biofuel undoubtedly lies in whether it can be converted into secondary fluid fuel (ethanol or gas). Once biofuel is converted into secondary fluid fuel, it has the same transportation advantages and disadvantages as oil and natural gas. The conversion of solid biofuels is limited by collection and transportation, so it is not easy to transport them to conversion facilities; Manure is an excellent raw material for biogas production, but the fertilizer produced by free-range animals is too scattered to be collected and applied. Generally speaking, it is the best way to produce biogas on the spot where the existing waste streams are concentrated. Alcohol produced by plants is most likely to be mixed with petroleum products for internal combustion engines, and its transportation mode is the same as that of petroleum.