HDPE Winding Reinforced Structural Pipe
HDPE wound structural wall B-type pipe
produced by our company uses high density polyethylene (HDPE) material and is
produced in accordance with the latest Chinese standard GB / t19472.2-2017. The products are widely used in hydraulic
engineering, municipal engineering, construction engineering, communication
engineering, industrial sewage and drainage, agricultural irrigation, road
drainage, mine drainage, air supply and ventilation, etc.
HDPE Structural Pipe SN8 DN800, HDPE Structural Pipe SN12.5 DN800, HDPE Structural Pipe SN8 DN700, HDPE Structural Pipe SN12.5 DN700, HDPE Structural Pipe SN8 DN1000 Zhoushan Runchun Import & Export Co., Ltd. , https://www.en124casting.com
1. Advantages of steam as a heat transfer medium
Steam has a high heat capacity, and the steam system has a smaller pipe when delivering the same heat than a liquid heat transfer medium, which also means lower cost.
The steam line is relatively light in weight and can reduce the cost of supporting the pipe.
In the steam pipe, as long as there is a pressure drop, there is no need to circulate the pump.
The steam system is flexible and can increase or decrease the load as needed within a certain range.
Steam can be controlled using a two-way control valve to avoid the use of a three-way valve.
From the point of view of use, the heat transfer coefficient of steam to medium is usually twice that of water to medium, thus making the heat transfer equipment more compact. In addition, there is no temperature gradient on the steam heat transfer surface, and the space temperature at which the steam is filled makes the same.
2. Superheated steam
If the saturated steam passes through a higher temperature heat exchange surface, the temperature of the steam will be higher than its evaporation temperature. At this time, the steam is called superheated steam, and the temperature higher than the saturated steam is called superheat.
Superheated steam has its own application areas, such as turbines used in generator sets, which push the motor through nozzles to the motor. However, superheated steam is rarely used in the heat transfer process of industrial processes because the superheated steam must be cooled to the saturation temperature before the condensation releases the evaporating enthalpy. Obviously, the superheated steam is cooled to the saturation temperature compared with the evaporating enthalpy of the saturated steam. The amount of heat released is small, which reduces the performance of the process equipment.
3. Steam dryness
The steam generated at a boiling point temperature under a certain pressure is called dry saturated steam, and the dryness is 1. However, it is difficult to produce 100% dry steam in practical applications, usually with a certain amount of water droplets. If the steam contains 10% by mass of water, the steam is 90% dry, ie the steam dryness is 0.9. Therefore, the actual wet steam evaporation is not the hfg shown on the steam meter, but the product of the dryness x and hfg: the actual evaporation ç„“ = evaporation ç„“ x dryness
4. The concept of steam and helium
Steam is a vaporous form of water. Steam generation requires heating the water to the boiling point, and if it continues to heat, the boiling water becomes steam. These two processes involve the following energy terms:
Liquid helium or sensible heat
This part of the energy refers to the heat required to heat the water to the boiling point, where the heat of heating only changes the temperature of the water, usually indicated by the symbol hf. The heat that heats 1 kg of water from 0 °C to the boiling point can be read from the steam gauge. For example, at atmospheric pressure (0 bar g), the boiling point of water is 100 ° C, the heat required to heat 1 kg of water from 0 ° C to 100 ° C is 419 kJ.
Evaporation or latent heat of evaporation
Refers to the heat required to convert all of the water at boiling temperature into steam, usually indicated by the symbol hfg. When heat is added, the temperature of the water/steam mixture does not change, and all of the heat is used to convert the liquid (water) into a gaseous state (steam) and a phase change occurs. The heat required to evaporate water at 1 kg boiling temperature can be read from the steam gauge. For example, at atmospheric pressure (0 bar g), 2257 kJ of heat is required to evaporate 1 kg of 100 °C water into 1 kg of 100 °C steam.
Total heat
Refers to all the energy in the steam, which is the sum of liquid helium and evaporating helium, expressed in hg. Full thermal energy can also be read from the steam gauge. For example, at atmospheric pressure (0 bar g), the total heat energy required to completely convert 1 kg of 0 °C water to 100 °C is 419 + 2257 = 2676 kJ.
When steam transfers heat during the process, the first thing that is transferred is the evaporation enthalpy, which is the amount of heat that can actually be applied. At this point, the steam condenses into water at the same temperature, called condensed water.
Steam basics
Steam basics