The water circulation system is as follows:
Water generates saturated steam in the boiler furnace. Passing through the superheater, it continues to be heated by the fumes and becomes superheated steam. to the steam turbine via the main steam pipe and is heated in the steam turbine. After internal expansion occurs, it enters the condenser and condenses into water. The condensate enters the deaerator via the low pressure regenerative heater, then is sent to the boiler via the feed water pump and the high pressure heater. Part of the steam is extracted from an intermediate stage of the steam turbine and sent to the recovery heater and deaerator respectively to provide recovery water as well as heating and deaeration. In order to compensate for the loss of steam and water, additional chemically treated water must be added to the degasser, and the water from the degasser can bee supplied to the boiler. For the steam to condense into water in the condenser, a circulating water pump must be used continuously to send cooling water into the condensing tube of the condenser for heat exchange, which forms another d cooling water. The cooling water can be sourced directly from rivers, streams and lakes and discharged into rivers, streams and lakes, or it can be reused by heat exchange with the atmosphere in a tower type spray pool. cooling.
Once the superheated steam enters the steam turbine, it turns the rotor, causing the generator to rotate and produce electricity, which is then sent to the user through a series of electrical equipment and transmission lines. This is the production process of large and medium-sized coal-fired condensing power plants.th size.
For more professional parts, please refer to the manual “Electrical Parts of Power Plants (Third Edition)” edited by Xiong Xinyin
Essential inspection items and guide to avoid pitfalls for 100,000 kilometers of maintenance h3>
Diagram of working principle of solar water heater 1. Cold water enters the solar water heater through the pipe, passes through the collector plate heat and the heat collector plate can collect solar energy, convert solar energy into thermal energy, and then heat cold water. Since the density of cold water is higher than that of hot water, the hot water will automatically increase and then form circulating power. The water will gradually heat up on the heat collecting plate. After reaching a certain temperature, it can enter. the hot water tank. Those who need hot water tohave get hot water at any time. Heating Figure 2. In fact, the principle of solar water heaters mainly includes the following two principles: (1) The principle of water circulation, that is, the water flows automatically. This is based on the fact that cold water is denser than hot water. Cold water flows and hot water rises, forming natural convection that gradually heats the water in the water tank until it reaches the set water temperature. When the intensity of the sun is not sufficient to meet circulation needs, a water pump can be added to the closed water circulation circuit to obtain forced circulation. (2) Collector heat absorption principle: There is a special coating on the collector surface of the solar water heater. This coating has a high absorption rate in the visible range of solar energy. After absorbing it in the form of heat, theheat. the radiation from the collector will have the wavelength in the longwave range and the coating has low longwave emissivity, thus effectively retaining solar heat. This heat is then used to gradually heat the cold water into hot water. Solar collector tube Let's talk in detail about the collector tube on this collector. The collector tube is actually like an elongated hot water kettle liner. It is made of two glass tubes, one large and one small. the inner layer is covered with a spectrum-selective absorption coating, and a straight space is drawn between the inner and outer tubes. This is the core of the solar water heater and is used to maximize the absorption of thermal energy after solar radiation; The empty glass tube is round and has the particularity of naturally following the broad source of the sun. Coupled with the reflection principle of the reflector, the glass tube can receiver light from all sides, the heat collection effect lasts longer and the water temperature. is higher, even in alpine areas for a year. It can also work normally in all seasons.
Regarding air-cooled and internally cooled hydrogenerators, the following statements are correct ( ).
Items to absolutely check and guide to avoiding pitfalls for 100,000 kilometer maintenance
Some time ago, a friend's car crossed the 100,000 kilometers mark (more than 6 years ago), complained that 100,000 kilometers maintenance cost the 4S store more than 4,000 yuan. And this price does not include the price of tire replacement. As soon as he heard it, he knew he had been deceived. After buying a car, many people don't know when to maintain it, or even over-maintain it. Money is spent but the effect is not achieved. When a car reaches one milerage of 10 W kilometers, it can be said that it is the turning point between youth and middle age. Serious maintenance and inspections must be carried out at this turning point. Below we'll talk specifically about the must-have inspection items for 10W of maintenance miles as well as some unnecessary digging items.
1. Essential items for 100,000 kilometers of maintenance
(1) The engine oil change and the three filters are essential items for each maintenance in order to lubricate the main power train and the cooling of the Engine oil is certainly one of the essential elements of maintenance at the 10w mileage level. Almost every car owner knows this.
(2) Change the engine oil. However, many novice car owners are unaware of the mileage intervals for oil changes. To put it simply, the mileage interval betweenEngine oil changes can be changed every 5,000 to 10,000 kilometers. Time intervals vary depending on the quality of engine oil used. For example, regular mineral oil can be replaced every 5,000 kilometers and semi-synthetic oil every 7,500 kilometers. Full synthetic motor oil can be replaced every 10,000 miles. If the mileage is particularly low (less than 5,000 kilometers per year), the principle of replacement once a year should also be followed.
A little tip: changing the engine oil and oil filter on time and as needed is one of the most important keys to ensuring the good life of your car.
(3) Replace the transmission oil. No matter what type of transmission your car uses, manual, automatic, AT, dual clutch, CVT, AMT, etc. When the mileage is 10W kilometers, it is a must-have item.
BieAlthough they are both lubricants, the replacement intervals for transmission oil and engine oil are very different. The working environment of engine oil is much worse than that of transmission oil (part of the burned oil and gas will escape into the engine oil), so the replacement cycle is shorter . Gearbox oil is mainly recycled in a closed space. It is rarely affected by external factors and can be maintained in a relatively stable operating state for a long time. The replacement mileage is much longer than that of engine oil. There are even service manuals for some models stating that the transmission oil is maintenance-free and does not need to be replaced (such as Nissan's CVT transmission and BMW's ZF 8AT transmission).
However, the movement characteristics of the metal and gears determineent durationThere will be wear over time, so when the transmission oil reaches 10 W kilometers, the transmission oil already contains a large number of metal particles, and the lubrication effect is greatly reduced. Continued use will accelerate wear of the internal parts of the. transmission, and in some serious cases, it will even block the solenoid valve and oil line, etc. Regardless of safety or fuel economy, replacement is the best choice.
A little tip: use a circulation machine or remove the oil pan to put it back deeper. It is best to replace it with the transmission filter element.
(4) Replace the generator and fan belt. The generator and fan belts are elastic rubber parts. After working for 10 W kilometers, they will become longer and extend many small cracks,essentially reaching the state of replacement fatigue, so they must be replaced.
In general, the ultimate life of a belt is 12 to 15 W kilometers. A belt after 10 W kilometers is like a time bomb. Once it breaks on the road, the engine can stall and fail (the battery can't do this). meet power demand once the battery runs out of power). More serious, the water temperature is too high, causing abnormal wear inside the engine (the water tank fan cannot work properly to dissipate heat).
A little tip: if the tensioner working with the belt is working correctly, it does not need to be replaced, otherwise it must be replaced together with the belt.
(5) Replace the spark plug. Depending on the engine fuel injection method and spark plug type, the replacement mileage ofs spark plugs for different cars is different. Some need to be replaced every 4 W kilometers, and some need to be replaced every 6 W kilometers. Regardless of the fuel supply method (multiple injection, direct injection, mixed injection) and the type of spark plug used (nickel, platinum, iridium alloy, single head, double head, etc.), in the existing technical conditions, 10 W kilometers is the best spark plug watershed, it is recommended to replace it.
Even if the car idles normally after driving 10 kilometers and does not vibrate when accelerating, it is recommended to replace it. Since ablation and wear of the spark plug electrode tip is an irreversible process, the likelihood of flashover, misfires, or even burnout is significantly increased after 10w miles. Once the prabove problems occurred, it can range from the absence of a cylinder to damage to the engine piston. . When replacing spark plugs, you can choose the original model, or you can choose an upgraded model with the same calorific value, such as single platinum to double platinum, which is more durable.
(6) Replace the brake fluid. Brake oil is an important part of the braking system. The replacement principle is mainly whether its water content exceeds the standard. When the water content exceeds the standard, the boiling point of the brake fluid decreases. Under certain conditions such as continuous braking, the water boils first, resulting in poor braking effect or failure. After the car has traveled 10 kilometers, the water content of most brake fluids will exceed the standard. Additionally, impurities present in the brake pump will also enter the brake fluid.brake, it is therefore recommended to replace it.
A little tip: the formal way to change the brake fluid is to drain the oil in the brake pumps of all four wheels, and it should be bled, rather than pumping the oil from the reservoir brake oil.
(7) Replace the power steering oil. Most modern car steering wheels have adopted electrical assistance, but a small number of cars still use mechanical steering wheels.Mechanical hydraulic assistance. If it is a car with mechanical-hydraulic assistance, the booster oil must be replaced. The electronic booster has no booster oil and does not need to be replaced.
(8) Replace the fuel filter element. The location of the fuel filter element is different in different cars. The replacement mileage cycle is also different. Most are divided into two types. One is installed on the chassis of the cariture, then somewhere in the pipeline. There is also a unit installed directly in the fuel tank and combined with the fuel pump. Whatever it is, it is recommended to replace it (or disassemble and clean it) when the mileage reaches 10W kilometers. The one built into the fuel tank can be disassembled and cleaned due to the high replacement cost.
2. Items to absolutely check for 100,000 kilometers of maintenance
(1) Tire inspection and replacement. Tires are a relatively important part of the vehicle and are also a key inspection item during 10 W-kilometer maintenance. If the tire wear reaches the wear mark, a large number of cracks appear due to aging or the sidewall is damaged, it must be replaced. It can still be used in other situations, and nothing says that the tires need to be replaced after 10 kilometerss.
(2) Inspection and cleaning of the throttle valve. When replacing the spark plug after 10W miles, the throttle valve should be inspected. If there is a lot of dirt and mud, it is recommended to clean it. Otherwise, in later use, it is easy to block the throttle valve or make the air intake quantity inaccurate, resulting in engine jitter and uneven acceleration.
(3) Antifreeze inspection. Car antifreeze is an important part of the engine cooling system. These days, cars are often filled with long-lasting antifreeze (more than 10 years and 20 kilometers) when they leave the factory. However, antifreeze will be consumed (evaporated and leaked) under normal circumstances. to use.
After 10 w kilometers you should check the antifreeze and the water tank. If they are missing, add them. If they leak, they need to be repaired. If water has been added during use, itIt is recommended to replace the antifreeze. Since the working temperature of antifreeze is relatively high, it will scale and clog the water path of the water pump, or cause corrosion and rust of the water pump when used for a long time. long period. Therefore, it is recommended to replace and clean the water. reservoir.
(4) Inspection and replacement of the timing belt. There are two types of modern motors that drive timing cams: chains and belts. Timing chains are often maintenance-free and do not need to be replaced. The lifespan of the timing belt is generally 10 to 15 kilometers, so it is necessary to replace it. check if the official belt needs to be replaced. Timing belt replacement mileage can be determined according to the service manual.
(5) Chassis inspection. Assholefocus on checking if the shock absorber system struts are leaking oil, ball cage ball joints are deformed or cracked, motor legs and other shock absorber washers are cracked and damaged, etc. Repair and replace according to actual situation.
(6) Inspection and cleaning of the fuel injector. After the engine has traveled 10 W kilometers, due to carbon deposits and other reasons, the atomization effect of the fuel injector has been greatly reduced during most of the operation, and the quality of the he atomization effect directly determines fuel economy and engine power. . If the car has a significant increase in fuel consumption and a decrease in power performance, it is recommended to add cleaning and maintenance of fuel injectors during maintenance of 10 W km.keep. For pre enginesSensing less carbon deposits on the injector, you may choose to add fuel additives as a cleaning method when refueling.
(7) Battery inspection. As the power source for the whole vehicle, the capacity and rated voltage of the battery will change after 10W mileage test. At this time, it is necessary to judge whether the battery needs to be replaced according to the test results. If the capacity and rated voltage are greatly reduced and there is a lack of electricity such as difficulty starting in the morning, it should be replaced in time.
A common digging project in 3.4S shops and garages
As mentioned at the beginning of this article, my friend spent over 4,000 yuan on major maintenance, and a lot of 'among them were useless. . Excavation project. There are mainly the following types.
(1) Internal cleaning of the engine is generally donet refers to adding a special cleaning oil to the engine oil and then draining it after a short period of operation. This is called internal engine cleaning, but it is actually one of the internal engine cleanings. digging projects. As long as your engine is maintained normally within 100,000 miles, every time you change the oil, it is actually a process of cleaning the inside of the engine. There is no need to complete this project separately. Only certain special circumstances require cleaning the interior of the engine, such as the engine oil has not been changed for a long time (more than 2W kilometers), the engine oil is particularly emulsified, the engine oil is coked. , etc.
(2) Fuel system maintenance. When the engine is idling, the additive is mixed with the fuel by pumping a bottle, and finally reaches the combustion chamber in.ur combustion, which plays a role in cleaning the fuel system.
In fact, the effect of such cleaning of fuel oil pipes is minimal, and it is also one of the digging projects. The method we mentioned earlier for specifically cleaning the throttle injector is effective and feasible.
(3) Brake disc polishing and maintenance package refers to polishing the brake disc by disassembling it to remove the marks on it. As we all know, after a long ride of 10 kilometers, the brake disc has more or less marks. This is due to friction between the brake disc and brake pads during operation, provided there are no particularly deep stress marks. . , no special maintenance is required. And if there are signs of stress, polishing the brake disc alone will not work. You must also inspect a series of placests such as brake pads, brake pump and mounting bolts.
(4) The general cleaning and maintenance method of the air conditioning system is to use air conditioning cleaning foaming agent to enter the air conditioning system ducts through the air inlet, and finally dry with hot air for cleaning and maintenance.
This project can be selected according to the actual situation. If the car air conditioning system has a relatively obvious odor and there is still no major improvement after replacing the air conditioning filter element, you can try this method. If this method still fails to eliminate the odor, you will need to disassemble and clean the fan, condenser, etc. of the air conditioning system, which constitutes a major project. Normally, regular replacement of the air conditioning filter is the best way to eliminate odors.s and ensure the quality of the air in the car.
(5) Fine cleaning of the engine compartment. Many people will frown when they open the engine compartment and see the dusty cabin, especially after 10W kilometers of wind and frost, the engine compartment was even more miserable. Fine cleaning of the engine compartment is a process in which the surface of the engine compartment is rinsed at high pressure using a special cleaning fluid and then dried with a high pressure gas.
After washing, the engine compartment can be considered new, but personally I do not recommend this method. First, the cleaning solution can easily corrode parts. Secondly, if you are not careful with the high pressure water gun, it may damage the electrical system of the engine room. You can choose to use compressed air to blow away the dust floating on the surface.face after each maintenance to ensure that it is dry.
Don't be careless when performing major maintenance on a car with a mileage of 100,000 kilometers. Regardless of the specific driving environment, you cannot be careless when performing major maintenance on a car with a mileage of 100,000 kilometers. mileage of 10W kilometers. You can't save money on the must-have items and you can't ignore the important inspection items. Other recommended products often have more pitfalls than meat, and consumers must make rational judgments.
In addition, for out-of-warranty cars, you can choose a more powerful repair shop instead of a 4S workshop. The transparency and cost of repairs will be much lower.
Answers: A, B, D
Hydraulic generators can be divided into methodCooling s: ① Air cooling type. The heat generated inside the generator is cooled by circulating air. Generally, a closed type with automatic circulation is used. The cooled and then heated air is forced to pass through a water-cooled air cooler to be cooled and participate in repeated cycles. ②Internal cooling type. When the capacity of the generator is too large and air cooling cannot achieve the desired effect, internal cooling is used for the generator. When the stator and rotor are directly supplied with cooling water for cooling, it is called a fully water-cooled hydrogenerator. When the rotor excitation winding and the iron core are still cooled by air, it is called a semi-water internally cooled hydrogenerator.