The difference between steam boilers and hot water boilers:
Hot water is used as a heat medium for air conditioners, 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 heat medium has the following advantages:
- Hot water heat medium Generally speaking, the temperature of the heat medium is relatively low, and the temperature difference with the flue gas is relatively large, and the exhaust temperature of the boiler is relatively low, so that the boiler efficiency is high.
- The closed hot water system has a small amount of recharge water, and the sewage discharge rate is much smaller than that of the steam boiler, and the water waste is also small. Moreover, the boiler water quality requirements are low, and the water treatment cost is small.
- The specific heat capacity of water is large, the hot water capacity in the system is large, and the heat storage capacity is strong. When a thermal or hydraulic condition fails for a short period of time, it does not significantly cause fluctuations in the heating condition.
- The hot water heating system can be transported by long-distance pump with small heat loss and large heating radius, which can meet the requirements of urban central heating planning.
The main disadvantage of hot water as heat medium is that the temperature is lower, the heat transfer coefficient is smaller, and the heat energy utilization rate is lower.
At present, China’s boilers are mainly steam boilers. The main advantages of steam as a heat medium are: - Low cost and wide adaptability, which can meet the heat requirements of many users who have different requirements for pressure and temperature.
- Non-toxic, can directly heat food, etc., even if there is a leak, it will not cause harm to the environment;
- The steam temperature is higher, 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;
- The heat inertia is small, the heat is fast when steam is supplied, and it is cold when it stops steaming.
Steam heat medium is difficult to recycle due to condensed water, resulting in waste of latent heat and water resources. Even if there is a condensate recovery device, it is easy to cause damage to the boiler during the condensed water recovery process because the water easily dissolves impurities such as oxygen. Impurities such as oxygen and salt in the feed water may cause problems such as scaling and corrosion of the boiler, affecting the safety and energy saving of the boiler.
