At present, the concentration reduction technology is mainly divided into membrane concentration and thermal concentration. Membrane concentration includes forward osmosis (FO), reverse osmosis (RO), electrodialysis (ED), nanofiltration (NF), membrane distillation (MD), etc.; thermal concentration mainly relies on steam to realize the evaporation of wastewater, including mechanical steam Recompression (MVR), multi-effect evaporation (MED), steam dynamic compression (TVR), multi-stage flash evaporation, falling film evaporation, etc., can also rely on the waste heat of power plant flue gas to evaporate, concentrate and reduce waste water. This technology does not need to be introduced. A large amount of steam energy can save costs, and at the same time, it can achieve the expected goal and realize the reuse of waste heat in the power plant.
Reverse osmosis (RO) in membrane concentration has a wide range of applications, but it is prone to membrane fouling and fouling and blocking problems; forward osmosis (FO) is a spontaneous process, with low energy consumption, no additional pressure, simple equipment, and its membrane surface is not easy to form In the filter cake layer, the membrane fouling is reversible, but it is necessary to select a suitable extraction solution, and the regeneration of the extraction solution requires extra energy. At the same time, the forward osmosis membrane has a serious internal concentration polarization phenomenon. Electrodialysis (ED) technology has the advantages of excellent treatment effect and low operating energy consumption.
4 problems of membrane concentration
3151 flanged liquid level gauge _ technical design of concentration reduction desulfurization wastewater
To sum up, membrane concentration mainly has the following four problems:
① Cost. High investment cost and operating cost, including energy consumption cost, cleaning cost, replacement cost of membrane element, equipment repair, maintenance cost, etc.
② Easy to scale and block. System reliability is poor.
③ The pretreatment requirements are high. Membrane modules have high requirements on influent water and need to remove impurities such as suspended solids in wastewater, which increases the cost of pre-treatment of wastewater.
④ It occupies a large area. A dedicated site needs to be provided to build membrane modules and other equipment.
General principles of technical route selection for desulfurization wastewater
The principle of reliability and economy; the principle of one factory, one policy; the principle of synergy; the principle of harmlessness
Desulfurization wastewater pretreatment technology
The common pretreatment technology of desulfurization wastewater is chemical precipitation method, such as triple box technology, double alkali method, lime-flue gas method, etc. commonly used in power plants.
technical design of concentration reduction desulfurization wastewater
The steam concentration in thermal concentration is to use steam to evaporate wastewater. Common technologies include mechanical vapour recompression technology (MVR) and multiple-effect forced circulation evaporation (MED). The MVR system is relatively mature, occupies a small area, runs smoothly, and has a high degree of automation. However, in the process of brine concentration, the MVR system still has problems such as blockage in the process of salt slurry discharge and easy damage to the fan impeller. In terms of process, MVR technology is shorter than MED technology, with less equipment, small footprint, and lower steam consumption, but in terms of one-time investment cost, MVR is higher than MED. Using steam evaporation to concentrate desulfurization wastewater, using MVR or MED technology, the investment cost is high
