A low-parameter large-flow double-split back-pressure steam turbine

Abstract

The invention discloses a low-parameter and high-flow double-shunt back-pressure steam turbine. The back-pressure steam turbine comprises a front-back bracket, a front-back radial bearing, a front-back exhaust cylinder, a cylinder, a steam inlet chamber and a rotor; the cylinder and the steam inlet chamber are integrated; a nozzle holding ring and a guide blade holding ring are symmetrically assembled in the cylinder; a static blade and a movable blade are respectively mounted on the guide blade holding ring and the rotor; and the cylinder, the steam inlet chamber, the exhaust cylinder and internal through flow adopt totally symmetric arrangement. The steam inlet chamber is connected with a steam inlet pipe; and an adjusting steam valve and a rapid closing valve are arranged on the steam inlet pipe. The back-pressure steam turbine adopts a through flow structure adjusted by a double-shunt nozzle, can guarantee gentle change of the set efficiency in acute load change process, is safe and stable in set operation, can largely reduce the width and height sizes of a steam turbine set by using the through flow structure, in addition, can reduce the size of the rotor by using the double-shunt structure, prevents welding of the robot, and can directly adopt overall forging of the rotor to reduce the manufacturing cost.

Description

technical field [0001] The invention relates to a steam turbine, in particular to a low-parameter, high-flow double-split back-pressure steam turbine. Background technique [0002] The large unit of 300MW thermal power station often has heating demand in winter in northern my country. The heating method is to draw steam with a pressure level of 0.4~0.6Mpa and a flow rate of 150~400t / h (ton / hour) from the four pumps, and convert it into The steam at about 0.2Mpa heats the water. At present, the commonly used steam grade conversion method is to reduce temperature and decompression. This conversion method will inevitably cause energy grade loss, and the most ideal and economical method is to complete the corresponding steam quality conversion through the post-installed back pressure steam turbine to generate electricity. [0003] The raw steam source of the steam turbine used for the above-mentioned steam quality conversion is main engine extraction steam, which has the charact...

AI Technical Summary

Problems solved by technology

[0005] 1. Due to the harsh and changeable operating conditions, it will have extremely adverse effects on the working efficiency, operating safety and stability of the steam turbine during the drastic load change process;

[0006] 2. Due to the low quality of new steam and large pressure loss, the steam inlet structure has high requirements on the smoothness of the flow channel, and the single-stage structure of the conventional single-cylinder back-pressure steam turbine cannot meet the requirements;

[0007] 3. The inlet steam parameter pressure is low and the flow rate is large. In order to reasonably control the pressure loss, a large-diameter quick-closing valve and a regulating steam valve are required to meet the operating requirements, so that the regulating steam valve and the cylinder cannot be designed together, and the large-diameter assembly designed and assembled separately The weight and thermal stress generated by the size adjustment steam valve and the inlet and exhaust pipes will cause potential risks to the safe operation of the unit;

[0008] 4. The steam volumetric flow rate is large and the enthalpy drop is small. Compared with the conventional parameter steam turbine, the overall structure size of the low parameter steam turbine is larger under the premise of the same output power, and the size of the generating set is relatively small, so that the arrangement of the steam turbine generating set is relatively small. bring certain difficulties;

[0009] 5. The steam turbine exhaust pressure is low, the specific volume is large, and the size of the exhaust cylinder is large. If the conventional integral casting exhaust cylinder is used, the production preparation time will be longer, the casting will be difficult, the cost will be high, and the casting quality will not be guaranteed;

[0010] 6. Due to the low steam parameters and large flow area, if a conventional single-cylinder back-pressure steam turbine is used, the diameter of the rotor will be very large, so it is inevitable to use a welded rotor, but the welding technology is complicated, and the welding of the welded rotor to the material The performance requirements are high, and the flaw detection after welding is difficult, resulting in high manufacturing costs and difficult to guarantee the quality of the rotor

Images