【Q&A Question 186】2018.07.10

Turbines can be classified in the following ways: 1) By the characteristics of the thermodynamic process: A. Condensing turbines, B. Regulated extraction turbines, C. Intermediate reheating turbines, D. Back-pressure turbines; 2) By working principle: A. Impulse turbines； B Reaction steam turbine ； C. Impulse-reaction combined steam turbines. (3) Classified by new steam pressure: A. Low-pressure steam turbines, with a new steam pressure of 1.18–1.47 MPa; B. Medium-pressure steam turbines, with a new steam pressure of 1 ； 96-1.3. 92M C high-pressure steam turbine, with a saturation steam pressure of 5.88–9.80 MP ； D. Ultra-high pressure steam turbines, with a saturation steam pressure of 11.77–13.73 MPa; E. Subcritical pressure steam turbines, with a saturation steam pressure of 15.69–17.65 MPa ； F. Supercritical pressure steam turbine, with a new steam pressure of 22.16 MP

Turbines are classified into impulse turbines and reaction turbines based on their working principle. Turbines are classified according to steam parameters (pressure and temperature): —— Low-pressure turbines: main steam pressure less than 1.47 Mpa ； —— Medium-pressure steam turbine: Main steam pressure between 1.96–3.92 Mpa ； —— High-pressure steam turbine: Main steam pressure between 5.88–9.8 Mpa ； —— Ultra-high pressure steam turbines: main steam pressure of 11.77–13.93 Mpa ； —— Subcritical pressure steam turbine: main steam pressure between 15.69–17.65 Mpa ； —— Supercritical pressure steam turbine: main steam pressure greater than 22.15 Mpa ； —— Ultra-supercritical pressure steam turbines: main steam pressure greater than 32 Mpa ；

1) Classification by the characteristics of the thermodynamic process: A. Condensing steam turbines, B. Regulated extraction steam turbines, C. Intermediate reheating steam turbines, D. Back-pressure steam turbines. 2) Classification by working principle: A. Impulse steam turbines； B Reaction steam turbine ； C. Impulse-reaction combined steam turbines. 3) Classification by new steam pressure: A. Low-pressure steam turbines, with a new steam pressure of 1.18–1.47 MPa; B. Medium-pressure steam turbines, with a new steam pressure of 1.96–3.92 MPa; C. High-pressure steam turbines, with a new steam pressure of 5.88–9.80 MPa ； D. Ultra-high pressure steam turbines, with a new steam pressure of 11.77–13.73 MPa; E. Subcritical pressure steam turbines, with a new steam pressure of 15.69–17.65 MPa ； F. Supercritical pressure steam turbine, with a new steam pressure of 22.16 MPa

1) Classification by the characteristics of the thermodynamic process: A. Condensing steam turbines, B. Regulated extraction steam turbines, C. Intermediate reheating steam turbines, D. Back-pressure steam turbines. 2) Classification by working principle: A. Impulse steam turbines； B Reaction steam turbine ； C. Impulse-reaction combined steam turbines. (3) Classified by new steam pressure: A. Low-pressure steam turbines, with a new steam pressure of 1.18–1.47 MPa; B. Medium-pressure steam turbines, with a new steam pressure of 1 ； 96-1.3. 92M C high-pressure steam turbine, with a saturation steam pressure of 5.88–9.80 MP ； D. Ultra-high pressure steam turbines, with a saturation steam pressure of 11.77–13.73 MPa; E. Subcritical pressure steam turbines, with a saturation steam pressure of 15.69–17.65 MPa ； F. Supercritical pressure steam turbine, with a new steam pressure of 22.16 MP

There are many ways to classify steam turbines. They can be classified based on their thermal characteristics, as well as by their purpose, steam parameters, working principle, and number of stages. They can also be classified according to the number of rotors. The most common classification methods are as follows:

1. Classification based on the thermal characteristics of steam turbines
(1) Condensing steam turbines: In these turbines, after the steam expands and does work inside the turbine, almost all of it goes into the condenser where it turns into water, with only a small amount leaking through the shaft seals. In order to improve the thermal efficiency of the turbine and reduce the diameter of its exhaust cylinder, the steam that has done work is drawn out of the turbine and sent to a regenerative heater, where it is used to heat the boiler feedwater. Such turbines are also referred to as condensing steam turbines.
(2) Extractive condensing steam turbines: After the steam expands and does work inside the turbine, a portion of it is extracted at one of the intermediate stages for use in industrial production or domestic heating. The remaining steam goes into the condenser to turn into water. These turbines are called single-extraction turbines. Turbines that extract steam at two different pressures from different stages, supplying it to various users or production processes, are known as double-extraction (or dual-extraction) turbines.
(3) Back-pressure steam turbines: After the steam expands and does work inside the turbine, it is discharged at a pressure higher than atmospheric pressure, and such turbines are used for industrial production or domestic heating.
(4) Extractive back-pressure steam turbines: To meet the needs of different users and production processes, some of the steam with higher pressure is extracted from these turbines for industrial use, while the remaining steam continues to do work before being discharged at a lower pressure for industrial use and domestic heating.
(5) Intermediate reheat steam turbines: For high-parameter, high-power turbines, the main steam has a high temperature and pressure. As the steam expands through the last few stages of the turbine, its humidity increases, which can pose a risk to the safe operation of the turbine. To reduce this humidity, the steam that has done part of its work is drawn out of the high-pressure cylinder and sent back to the boiler to be reheated, bringing its temperature back to near its initial level. Then it enters the low-pressure cylinder of the turbine to continue doing work. Such turbines are called intermediate reheat steam turbines.

2. Classification by purpose
(1) Power station steam turbines: Turbines that are used solely to drive generators to produce electricity are called power station steam turbines.
(2) Heat supply steam turbines: Turbines that both drive generators to produce electricity and provide heat for domestic use are called heat supply steam turbines, or cogeneration turbines.
(3) Industrial steam turbines: Turbines that are used to drive mechanical equipment such as fans, pumps, and compressors are called industrial steam turbines.
(4) Marine steam turbines: Turbines that are specifically used for propulsion in ships are called marine steam turbines.

3. Classification based on the inlet pressure of the steam turbine
(1) Low-pressure steam turbines: The inlet pressure is between 1.2–1.5 MPa.
(2) Medium-pressure steam turbines: The inlet pressure is between 2.0–4.0 MPa.
(3) Super-medium-pressure steam turbines: The inlet pressure is between 5.0–6.0 MPa.
(4) High-pressure steam turbines: The inlet pressure is between 6.0–10.0 MPa.
(5) Ultra-high-pressure steam turbines: The inlet pressure is between 12.0–14.0 MPa.
(6) Subcritical steam turbines: The inlet pressure is between 16.0–18.0 MPa.
(7) Supercritical steam turbines: The inlet pressure is greater than 22.17 MPa

1) Classification by the characteristics of the thermodynamic process: condensing steam turbines, regenerative steam turbines, intermediate-reheat steam turbines, back-pressure steam turbines. 2) Classification by working principle: impulse turbines, reaction turbines, and impulse-reaction combined turbines. 3) Classified by new steam pressure: low-pressure turbines, medium-pressure turbines, high-pressure turbines, ultra-high-pressure turbines, subcritical-pressure turbines, and supercritical-pressure turbines.

Classified by working principle: impulse, reaction, and mixed-type turbines； Classified by thermodynamic process: condensing, backpressure, regulated extraction steam, intermediate reheat condensing, extraction steam backpressure turbine ； Classified by new steam parameters: low-pressure steam turbines (steam pressure

, condensing steam turbine, extraction-type steam turbine, C intermediate reheating steam turbine, D backpressure steam turbine,

1. Classified by the inlet steam pressure of the turbine: (1) Low-pressure turbines: inlet steam pressure of 1.2–1.5 MPa; (2) Medium-pressure turbines: inlet steam pressure of 2.0–4.0 MPa; (3) Super-medium-pressure turbines: inlet steam pressure of 5.0–6.0 MPa; (4) High-pressure turbines: inlet steam pressure of 6.0–10.0 MPa; (5) Ultra-high-pressure turbines: inlet steam pressure of 12.0–14.0 MPa; (6) Subcritical turbines: inlet steam pressure of 16.0–18.0 MPa; (7) Supercritical turbines: inlet steam pressure greater than 22.17 MPa.
2. Classified by the thermal characteristics of the turbine: (1) Condensing turbines; (2) Extraction-condensing turbines; (3) Backpressure turbines; (4) Extraction-backpressure turbines; (5) Intermediate-reheat turbines.
3. Classified by purpose: (1) Power station turbines; (2) Heating turbines; (3) Industrial turbines; (4) Marine turbines

Condensing, back-pressure, extraction-type