Hot water as a medium is suitable for air conditioning, […]
Hot water as a medium is suitable for air conditioning, heaters, low temperature ovens, drying equipment, hot water tanks for textile printing and dyeing, and various low temperature heating, air conditioning coils and heat exchange equipment. Hot water as a medium has the following advantages:
1. Hot water medium generally has a lower heat medium temperature and a larger temperature difference from the flue gas, and the boiler exhaust temperature is relatively low, so the boiler efficiency is high.
2. The amount of make-up water in the closed hot water system is small, the blowdown rate is much smaller than that of the steam boiler, and the water waste is also small. And the boiler water quality requirements are low, and the cost of water treatment is low.
3. The specific heat capacity of water is large, the capacity of hot water in the system is large, and the heat storage capacity is strong. When thermal conditions or hydraulic conditions fail in a short time, it will not cause significant fluctuations in heating conditions.
4. The hot water heating system can be pumped for long-distance transportation, with small heat energy loss and large heating radius, which can meet the requirements of urban centralized heating planning.
The main disadvantages of hot water as a medium for heating are lower temperature, smaller heat transfer coefficient, and lower utilization rate of heat energy.
At present, the boilers in my country are mainly steam boilers. The main advantages of steam as a medium are:
1. Low cost, wide adaptability, can meet the heat requirements of multiple users with different requirements on pressure and temperature;
2. Non-toxic, can directly heat food, etc. Even if there is a running drip, it will not cause harm to the environment;
3. The steam temperature is high, the latent heat of vaporization is large, and the relative hot water can reduce the heat exchange area of the equipment and reduce the cost;
4. The thermal inertia is small, and it heats up quickly when the steam is supplied, and cools down quickly when the steam is stopped.
The steam medium is difficult to recover due to condensed water, resulting in waste of latent heat and water resources. Even if there is a condensed water recovery device, in the condensed water recovery process, the water is easy to dissolve impurities such as oxygen, and it is easy to cause damage to the boiler. Impurities such as oxygen and salt in the feed water will cause problems such as scaling and corrosion of the boiler, affecting the safety and energy saving of the boiler.