Natural gas is a kind of high grade, efficient, clean low carbon the sources of energy, reach with nuclear energy but second birth the sources of energy other low discharge the sources of energy to form benign and complementary, it is the actualest choice that the sources of energy supplies cleanness to change. 2015 consumption of apparent of countrywide natural gas 193.1 billion stere, during 925 ” of “ year all grow 12.4% , accumulative total consumption makes an appointment with 830 billion stere, it is “ 2 times of 915 ” consumption, natural gas consumed medium proportion in the sources of energy 2015 from 2010 4.4% rise 5.9% , 935 ” of “ plan this proportion increases 8-10% .
Natural gas of 1-12 month China imported an amount to be 68.57 million tons 2017, grow 26.9% compared to the same period; Import conduit natural gas among them 30.43 million tons, entrance liquefied natural gas 38.13 million tons, the liquefied natural gas imports a quantity to exceed conduit natural gas to import an amount. See figure 1; Enter after 2018, the trend that imports quantity of liquefied natural gas to be more than tolerance of inlet tube path is more outstanding. See a table 1.
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The main function that LNG receives a station is to receive, store and aerification LNG, be in charge of Xiang Ran to enrage power plant and urban user air feed through natural gas, some receives station basis to needed to still install LNG tank car to install a station, supply LNG directly to the user. When discharge boat LNG enters storage tank to cause change of bulk of the LNG inside coal tub, and environmental temperature and input of energy of bound of atmosphere change substandard, produced a large number of evaporating to enrage (the 0.5% ～ that deposit gross occupies about when BOG does not have discharge boat namely 0.6% , the amount when discharge boat is larger, but need to return LNG boat to be balanced in order to keep pressure partly among them) generation, can bring about the pressure inside storage tank to increase. To maintain force of storage tank internal pressure to stabilize, must send the evaporate of excessive gas is handled.
Evaporate is gas evolution processing system is main by BOG compressor, again condenser (use at only again condensation exports technology, evaporating right now gas again condensation) reach evaporate is gas evolution the composition such as pipeline system.
BOG compressor is the crucial equipment that BOG handles, the evaporate that its action is processing excessive is gas evolution, those who keep force of internal pressure of LNG storage tank is constant. Because price of entrance BOG compressor is very high, homebred BOG compressor compares an import about BOG compressor price is low 50% ～ 70% , after because all sorts of reasons produce plan to often procrastinate,importing BOG compressor, cause undesirable effect to project plan, and foreign engineer arrives field service cost is high, harmonious manufacturer arrives field service is very difficult, the home made product in be developed so and citing has very important real sense.
1. Compressor of the BOG in the LNG item that always includes in engineering company is homebred a key that changing type selecting is this project.
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Key of type selecting of compressor of the BOG in LNG project and difficulty: LNG medium temperature is highest 35 ℃ , lowest arrives – 157.9 ℃ , average data cannot have satisfied a requirement. Because microtherm BOG compressor operates temperature extremely low (- 157.9 ℃ ) , produce microtherm cold short as easily as the component material that microtherm medium contacts, rupture, and cold quantity is conducted come to lubricate and move the system makes compressor cannot work normally, this kinds of equipment counts an import for a long time. In recent years as Chinese compressor level rise at full speed, microtherm data is constant research and development makes BOG compressor successfully homebred change make a kind of inevitable trend.
This BOG compressor invite public bidding uses means of ask rate of exchange to undertake, china shares 4 companies to bid, among them reason of requirement of a not contented type abandons bid. (balance of semmetry of requirement of compressor of move back and forth, reject trigonometry model)
Program of A company technology: Use compressor of the symmetrical balance that two one class reduces move back and forth.
Microtherm material: Group of lid of cylinder bushing of air cylinder, gas, air cylinder, piston uses microtherm data, material of this low temperature is to mix Chinese some university is collective research and development and into move actually good.
Program of B company technology: Use compressor of the symmetrical balance that two one class reduces move back and forth.
Microtherm material: Material of low temperature of group of lid of cylinder bushing of air cylinder, gas, air cylinder, piston collects data of foreign low temperature
Program of C company technology: Use without oil-lubricated water-cooling shuts type labyrinthian structure, 3 3 crocks of 2 class are compressed, air cylinder is vertical double action.
Microtherm material: Air cylinder of one class, 2 class, piston all uses microtherm data. Company of some engineering of this manufacturer and China is developed jointly and become. Material of nodular cast iron of low temperature of — of material of the ultralow temperature that good mechanical performance has below microtherm condition, easy figuration and lie between cold structure. Come through lying between cold structure to guide cold quantity system of compressor lube refrigeration, the body in avoiding microtherm assembly cold capacity to pass delivers normal temperature part, realize Leng Nengxun annulus to use.
The option of BOG compressor type is very important, want thorough research so, to compressor of move back and forth, labyrinthian compressor its advantage and defect, dependability, economy reachs the price that the manufacturer quotes, undertake contrasting analytic making best choice thereby.
The advantage of compressor of 1.1 move back and forth
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Range of ① applicable pressure is wide. Piston compressor can design low pressure, middling pressure, high pressure and superhigh pressure, and waiting for rotate speed to fall, when exhaust pressure is fluctuant, the capacity of piston compressor keeps basically changeless.
② reduces efficiency taller. Piston compressor compresses aeriform process to belong to closed system, its reduce efficiency taller.
③ adaptability is strong. Range of piston compressor capacity is wider, and aeriform density is not as remarkable in that way as speed type compressor to the influence of compressor function, compressor often should transform the piston of same norms to be able to be applied to slightly only compress other aeriform medium.
④ one-time investment is small () of relatively centrifugal compressor, screw compressor, labyrinthian compressor.
⑤ cubage efficiency is tall (relatively labyrinthian compressor) . Efficiency of WECS: One, average efficiency of 2 class air cylinder is 91.2% .
⑥ motivation has been balanced.
The defect of reciprocating type compressor:
① gas belt is smeary. Especially oil-lubricated to having more remarkable.
② rotate speed cannot exorbitant. Because accept the restriction of reciprocate force.
③ exhaust is discontinuous. Aeriform pressure has wave motion, create air stream likely pulsatile resonance.
④ is fragile more, maintenance amount is larger.
Piston compressor is main seal by group of airframe, crankshaft, connecting rod, piston, valve, axis, the component composition such as regulating unit of oil pump, energy, oily circulatory system, it is depend on air cylinder of group or one array and the piston that reciprocate does inside its, change the compressor of its interior cubage. Piston compressor is a kind of compressor of cubage reciprocating type, can satisfy the requirement of all sorts of tolerance. Basically apply at the branch such as oil, chemical industry, mining, metallurgy, mechanical, building.
⑤ covers an area of an area bigger (relatively labyrinthian compressor, centrifugal compressor) , increase a project to build cost.
1.2 vertical are labyrinthian the advantage of compressor
① covers an area of an area less (compressor of opposite move back and forth) . Land uses cost and spot construction quantity to drop considerably, can shorten considerably at the same time the installation time of equipment.
② economy and dependability are good. . Aircrew is fragile the amount decreases in great quantities, if use labyrinthian compressor, its are sealed the principle is reduce expenditure sealed, without piston annulus, the annulus that prop up and filling are fragile leave moving unit to successive job, can maintain the reliability that run. Improved the service life of aircrew. Labyrinthian compressor not only exhaust does not have oil, and any dust do not arise to wear away inside compressor air cylinder, be opposite at the same time the foreign matter grain of the interfuse in compressing medium is not sensitive, in combustible the hydrocarbon that explodes easily kind sex of taller on the safe side is had more in gas and aerobic device.
③ efficiency is tall. Because use labyrinthian compressor, after between crock and piston weather strip, do not have block, attrition to be able to save many energy loss.
④ security is good. Labyrinthian compressor is made with the metal through all components of air current, design as far as possible simple, attrition of instrument of the inorganic inside limits is compressed to arise in gas, in compress combustible explode easily poisonous and harmful still can use the structure that shut type, enhanced the security of compressor.
⑤ pipeline is decorated concise reduce pipeline vibration greatly. Because use labyrinth compressor, it is more easy that aircrew amount reduces pipeline to decorate.
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Vertical is labyrinthian the defect of compressor
The treatment precision demand of ① sealed spare parts is high, the space between the spare parts is compact, tear open outfit is more difficult.
② oriented demand is higher. If run occurrence problem, produce attrition to wear away can reduce sealed performance, and repair cost is higher.
In process of this compressor invite public bidding, although A, B quote of business affairs of two companies is inferior, quoted price of C company business affairs is higher, but be like from integrated angle: Service life of energy-saving, environmental protection, security, dependability, machine and long-term moving cost point of view will analyse summary, choose C manufacturer type selecting finally: Labyrinthian compressor. This aircraft moves in actual production good.
2. Labyrinthian compressor develops prospect
Development of company of Swiss Su Ershou developed the first labyrinthian compressor 1953, initiated the beginning that labyrinthian compressor applies, and dominated the market outside China for a long time have rate. Labyrinthian compressor with its distinctive structure characteristic, wider and wider application will receive in petro-chemical domain of future. Especially in recent years LNG serves as a kind of cleanness, efficient the sources of energy to apply extensively in China, and BOG compressor is having crucial effect in LNG project, believe to be able to raise the utilization rate of labyrinthian compressor greatly. Go up in the energy-saving project that decrease a platoon especially, labyrinthian compressor can receive wider application.
Epilogue
Below current and sophisticated international topological features, develop ethical industry, creation China brand has extraordinary real sense. Of the country powerful and prosperous depend on abroad impossibly, this is nearly hundred years deep lesson. BOG compressor is in homebred all sorts of problems can appear necessarily in changing a course, need engineering company and manufactory give full cooperation to had made the item finally, make BOG compressor essence of life strong, innovation gives outstanding Chinese brand.