【Q&A Question 116】April 26, 2017
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【Q&A Question 116】April 26, 2017: What are the hazards of scale formation on turbine blades? The reference answer can be seen after responding; points will be awarded for identifying the key points. (Unless otherwise specified, all questions and answers are based on hydrogenation units.) ) When the quality of steam is poor, salt deposits can form on the flow-through parts of the turbine. Scaling is more severe in the high-pressure areas of the turbine, while in the low-pressure areas, scaling is minimal due to the operation under wet steam conditions. The hazards associated with scaling in the turbine’s flow-through parts include: 1. Reduced efficiency of the turbine and increased steam consumption; 2. Due to scaling, the pressure drop as steam passes through the partitions and blades increases, which in turn increases the reaction degree of the working blades. In severe cases, this can cause overloading of the partitions and thrust bearings ； 3. Salt scale attached to the valve stem can easily cause the valve stem to stick. Scoring criteria: 2 Wealth points for incorrect attempts; 3–8 points for *incomplete* answers. 10 Wealth points for correct answers, provided with detailed explanations; 15–20 Wealth points if the answer is correct but lacks sufficient details. Please score according to these criteria. 2017 Q&A Summary Thread (updates starting now) http://bbs.hcbbs.com/thread-1657793-1-1.html 2017 Daily Question Summary Thread (updates starting now) http://bbs.hcbbs.com/thread-1657794-1-1.html 2016 Q&A Summary Thread (updates completed) http://bbs.hcbbs.com/thread-1597792-1-1.html Petrochemical Sector – “Creative Ideas for Energy Saving” Campaign (Sponsors sought; highest returns ever) http://bbs.hcbbs.com/thread-1666758-1-1.html Sponsors are being sought for this campaign; those interested can contact the campaign coordinator. Petrochemical deep processing version – the event to share pictures of chemical equipment has started! A vast amount of wealth, as well as HChuan coins, are waiting for you to claim them: http://bbs.hcbbs.com/thread-1760733-1-1.html. Notice regarding the collection of chemical engineering technical materials in the “Petroleum and Chemicals Section”: http://bbs.hcbbs.com/thread-1614796-1-1.html (Source: HChuan Chemical Forum)
1) It reduces the efficiency of the turbine and increases steam consumption; (2) Due to scaling, the pressure drop increases as the steam flows through the diaphragms and blades, which in turn increases the reaction degree of the working blades. In severe cases, this can cause overloading of the diaphragms and thrust bearings.
During normal operation, it tends to become eccentric, experiences uneven stress, and has already been damaged
(1) It reduces the efficiency of the turbine and increases steam consumption； (2) Due to scaling, the pressure drop increases as the steam flow passes through the diaphragms and blades, which in turn increases the reaction degree of the working blades; in severe cases, this can cause overloading of the diaphragms and thrust bearings.
Scaling makes the surface of turbine blades rough, increasing the frictional losses during steam flow and thereby reducing the efficiency of the turbine. Scaling on turbine blades reduces the steam flow cross-sectional area, thereby decreasing the turbine’s output power. It will increase the pressure difference before and after the diaphragm, thereby increasing the deformation stress of the diaphragm. It increases the pressure difference before and after the impeller, thereby raising the axial thrust on the turbine rotor. This leads to overloading of the thrust bearings; in severe cases, it can even cause the bearing materials to burn out, resulting in friction and collision between the moving and stationary parts. Scaling substances have a corrosive effect on the blades; this corrosion reduces the strength of the blades, and in severe cases it can cause the blades to break, leading to serious accidents. When scaling is uneven along the circumference of the turbine, it will affect the balance of the rotor, increase the vibration of the turbine, and even lead to serious accidents.
It reduces the efficiency of the turbine and increases steam consumption. Damage to the machine’s equipment.
It affects the efficiency of the turbine, increases the axial thrust on the rotor, and causes scaling on the surface of the moving blades, which in turn increases the centrifugal and bending forces acting on those blades, thereby affecting the safe operation of the unit.
1. It reduces the efficiency of the turbine and increases its steam consumption； 2. Due to scaling, the steam flow passage narrows, resulting in an increased pressure difference across the diaphragm; this in turn increases the reaction force on the blades, and in severe cases it can cause overload of the diaphragm and thrust bearings ； 3. Salt deposits adhering to the valve stem can easily cause the stem to stick and fail to function properly.
1. It reduces the efficiency of the turbine and increases steam consumption. 2. Due to scaling, the pressure drop increases as the steam flow passes through the diaphragms and blades, which in turn increases the reaction degree of the working blades; in severe cases, this can cause overloading of the diaphragms and thrust bearings.
1. Scaling can affect the rotor’s dynamic balance, leading to increased vibration. 2、Scaling reduces the steam flow area, increases flow resistance and axial thrust, leading to increased axial displacement of the rotor, overload of the thrust bearings, as well as dynamic and static friction of the rotor. 3. After scaling occurs, changes in resistance and blade geometry affect the efficiency of the unit. 4. After scaling occurs, the stress on the blades increases, leading to greater fatigue damage and affecting their service life.
When the quality of steam is poor, salt deposits can form in the flow passages of the turbine. Scaling is relatively severe in the high-pressure area of the turbine, while in the low-pressure area ； Due to operating under wet steam conditions, scaling is rare. Its hazards include the following: (1) It reduces the efficiency of the turbine and increases steam consumption ； (2) Due to scaling, the pressure drop increases as the steam flow passes through the diaphragms and blades, which in turn increases the reaction degree of the working blades; in severe cases, this can cause overloading of the diaphragms and thrust bearings.