What Is a Steam Turbine?

A steam turbine, also called a steam turbine engine, is a rotary steam power device. High-temperature and high-pressure steam passes through a fixed nozzle to become an accelerated airflow and is sprayed onto the blades to rotate the rotor equipped with the blade rows and perform work at the same time. Steam turbine is the main equipment of modern thermal power plants, and is also used in metallurgical industry, chemical industry and ship power plant. ^[1]

In the 1st century,

A steam turbine is an external combustion rotary machine that can convert steam thermal energy into mechanical work. After the steam from the boiler enters the steam turbine, it passes through a series of annularly arranged nozzles and moving blades in order to convert the heat energy of the steam into

There are many types of steam turbines, and there are various classification methods according to the structure, working principle, thermal performance, use, and number of cylinders.

Steam turbines usually work under the conditions of high temperature, high pressure and high speed. They are relatively sophisticated heavy machinery. They are generally used in conjunction with boilers (or other steam generators), generators (or other driven machinery), and

It consists of two parts: the rotating part and the stationary part.

And reciprocating

The emergence of steam turbines has promoted the development of the power industry. By the beginning of the 20th century, the single power of steam turbines in power stations had reached 10 MW. With the increasing application of power, the peak load of power stations in large cities such as New York, USA, was close to 1,000 MW in the 1920s. If the power of a single machine is only 10 MW, it will require nearly 100 units to be installed, so the power of a single machine has increased in the 1920s. Up to 60 MW, 165 MW and 208 MW steam turbines appeared in the early 1930s.

The subsequent economic recession and the outbreak during World War II put a standstill on the increase in the power of single turbines. In the 1950s, with the post-war economic development, the demand for electricity increased rapidly, and the power of single units began to increase. Large steam turbines of 325 to 600 MW appeared in succession; 1,000 MW steam turbines were made in the 1960s; 1300 MW steam turbine. The stand-alone power commonly used in many countries is 300 to 600 MW.

Steam turbines are widely used in all sectors of society and economy. There are many types of steam turbines and different classification methods. The steam of the steam turbine expands from the inlet to the outlet, and the volume per unit mass of steam increases hundreds of times, or even thousands of times. Therefore, the height of the blades at all levels must be gradually increased. The exhaust area required for high-power condensing steam turbines is large, and the final stage blades must be made long.

The development of large-scale steam turbine units is an important direction for the future development of steam turbines. The development of longer last-stage blades is a key to the further development of large-scale steam turbines. Research on improving thermal efficiency is another direction of steam turbine development. Secondary reheating, development of peak shaving units, and promotion of the application of heating steam turbines are important trends in this area.

The installed capacity of geothermal turbines around the world has been 3190 MW in 1983, but the use of deeper and higher temperature geothermal resources such as lava has yet to be explored; steam turbine power stations using solar energy are already under construction, and ocean temperature difference power generation is also being studied in. All these new energy steam turbines have yet to be tested and studied.

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During the operation of the steam turbine, steam turbine leakage and cylinder deformation are the most common equipment problems. The tightness of the joint surface of the cylinder directly affects the safe and economic operation of the unit. The joint surface of the scraper is overhauled to make it tight. Important work, in the process of dealing with the leakage of the joint surface, the cause of formation must be carefully analyzed. According to the degree of deformation and the size of the gap, various methods can be comprehensively used to achieve the strict requirements of the joint surface.

Steam turbine crack leakage

Hydraulic equipment such as oil turbines of steam turbines can withstand large pressure and vibration forces during work. Because the material of the equipment is cast iron, it is inevitable that there are casting defects that are difficult to find during the casting process. In addition, long-term full-load operation, it is extremely easy for trachoma leakage or crack leakage to occur in the weak part of the casing, making the equipment unable to work properly. At the same time, the leakage of the environment at the scene caused great safety hazards, which seriously threatened the safety and continuous production of the enterprise. ^[4]

After such problems occur, companies often do not have a timely and effective solution. Due to the poor welding performance of cast iron and the high requirements for the tightness of hydraulic equipment, traditional welding repair processes cannot be repaired at all. There are generally no spare parts for such equipment on the site, and purchasing and replacing requires a lot of downtime. The above problems can be repaired on site using polymer composite materials. Its excellent mechanical properties, good adhesion and pressure resistance make this problem effectively solved. The construction process is simple and fast, which can meet the requirements of on-site construction, and can prolong the service life of equipment and increase productivity.

Turbine Cylinder Deformation

The reasons for the deformation of the cylinder are related to the thickness and structural dimensions of the cylinder wall and flange metal, and the operation of heating the flange and bolts when starting and stopping. It also has a certain relationship with the insulation of the cylinder, and also with the manufacturing process. Due to the aging problem during the casting of cylinders and the complicated stress conditions, cylinder deformation is an unavoidable problem, which usually manifests itself in the case of internal or external opening of the cylinder, and this problem is more likely to occur in low pressure cylinders. After this problem occurs, destructive repair methods such as slotting should be avoided. The more mature technology applied in western countries is to use the high-temperature flat sealant repair technology adopted by the Siemens Energy Division of Germany to directly repair the deformed joint surface gap. ^[5]