High salt wastewater in the realization of "zero discharge" path

3. Final evaporation technology

The discharge of brine with higher concentration will have adverse effects on the environment. There are two main reasons for this effect. First, the brine concentration is higher; Second, the composition of salt water is more.

On the one hand, the desired effect of evaporation technology is to compress the volume of higher concentration brine and crystallize the salt inside; On the other hand, it is the formation of a circular industrial economy, which provides the precipitated salt to the manufacturers who use it as a raw material, and realizes the purpose of "zero emission".

Natural evaporation

The principle of natural evaporation is to use sunlight to remove the water in the higher concentration of brine in the pool, so as to achieve the saturated crystallization point of the higher concentration of brine, so that the salt precipitation, this device is called "evaporation pond".

The energy of the device comes from sunlight, so the device is suitable for use in dry places with less annual rainfall and abundant solar radiation.

The facility has the following advantages, because the energy comes from sunlight, so the heat source has no life loss limit, daily maintenance is easier, the cost of handling higher concentration of salt water is also relatively low, and can resist the impact of load.

The disadvantage is that the "evaporation pond" device is a non-airtight device, and the volatile components in the concentrated brine can easily cause air pollution into the atmosphere.

At the same time, the seepage prevention works on the side and the bottom of the evaporation pond are also very important. If it is not properly treated, it will easily cause malignant pollution to rock and soil mass and underground water source.

Under normal circumstances, "evaporation pond" covers a large area, and the use of land resources in places will cause certain waste; During the operation of the "evaporation pond", it is difficult to use the fresh water resources evaporated, resulting in a certain waste.

Hot process

The thermal zero emission technology developed based on the thermal brine desalination system, due to its low energy consumption, multi-effect evaporation is one of the three most commonly used brine desalination technologies in contemporary times. Based on the foundation of this technology, the theory of multi-effect evaporation - evaporation crystallization has been derived, and has been more and more widely used.

Foreign scholars have explored the "no emission" system using evaporation crystallization. The evaporating steam is used to heat the water into the evaporator, and its efficiency is much higher than that of conventional evaporation crystallization facilities.

Multi-effect evaporation (MEE) is generally controlled in 3 to 6 effect evaporation, too little is not enough to save energy, too much temperature difference is not enough, and the system is too long and easy to cause problems. The first stage evaporator uses steam to heat, and the later evaporator successively uses the secondary steam generated by the previous evaporator as a heat source to achieve the reuse of multiple heat energy, that is, multi-effect evaporation.

Multi-effect evaporation is more serious than multi-stage flash evaporation.