Boiler Wastewater Treatment
Johnson Screen For Boiler Wastewater
In industry, it is still the main use to generate electricity and heat by boiler.
A large amount of water slag will be produced in the operation of the boiler. If the water slag of the boiler is discharged out of the boiler irregularly, the boiler pipe will also be blocked, resulting in tube explosion accident.
It also reduces the heat transfer effect. Boiler waste water needs pretreatment before treatment.
Boiler waste water hazard
- Hazards of boiler itself.
Sewage will form scale, and it also has corrosion and other phenomena.
The occurrence of such phenomena will lead to the relative waste of fuel and the reduction of boiler output in the process of boiler operation, which may cause the damage of metal components and the occurrence of accidents such as the water level is not clear to the water level gauge and the water transportation is not safe, which is very important for the safe operation and energy consumption of the boiler Big impact.
- Environmental hazards.
The boiler will discharge a large amount of sewage in the working state. If no corresponding treatment measures are taken, it will pollute the groundwater, rivers and other water sources, which will have a corresponding impact on the growth and production of crops. If people live in the sewage environment for a long time, they will also suffer from poisoning and physical decline.
Multi media filter
The multi-media filter adopts two layers (coarse and fine quartz sand, anthracite) filter materials, and adopts pressure filtration. It has the advantages of large sewage interception capacity, high filtration speed, good effluent quality and long filtration period.
After the filter water enters from the upper part of the filter and passes through the filter material layer from top to bottom, the impurity particles, suspended solids and colloids in the water are adhered and retained by the filter material through physical changes, so as to separate them from the water.
With the development of filtration time, more and more impurity particles are retained in the filter material layer, the porosity is smaller and smaller, and the head loss is larger and larger. At the end of the filtration cycle, when the head loss reaches the limit value, it is necessary to stop filtration and backwash.
Filtration mainly depends on the nature of the filter material to be retained and the non flow state of the water passing section.
The filtration mechanism is summarized as follows:
- Mechanical screen filtration
When the water containing suspended impurities enters into the filter layer from the upper part, some suspended matters with particle size larger than the pore of the filter material layer are intercepted by the surface of the filter layer due to adsorption and airborne screening.
At this time, the suspended particles intercepted will overlap and bridge each other. After a period of time, an additional filter membrane appears to form on the surface of the filter layer. In the later filtration process, this filter membrane plays a major role in filtration, which is called surface filtration. In the filtration of non granular filter materials, this role plays a leading role.
- Inertial sedimentation
The suspended particles in the water will be thrown to the surface of the filter material due to their own gravity or the inertia of the suspended particles when the water flow bypasses the filter material.
- Contact flocculation
When the water flow with suspended particles passes through the channel in the filter layer, under the action of water flow state and Brownian motion, there are more opportunities to contact with the sand material, attract and adhere to each other under the action of van der Waals force, electrostatic force and some adsorption force, just like the deep coagulation process in the filter material layer.
With the development of filtration time, more and more impurity particles are retained in the filter material layer, the porosity is smaller and smaller, and the head loss is larger and larger.
At the end of the filtration cycle, the head loss reaches the limit value, or the filtration layer has the maximum capacity of sewage interception, and then the continuous filtration will make the effluent quality worse. At this time, the filter has to be stopped for backwashing.
Activated carbon filter
The activated carbon filter is mainly used as the pretreatment device of water quality advanced treatment system (such as ultrafiltration, ion exchange, reverse osmosis, electrodialysis, etc.). Mainly remove residual chlorine, colloidal particles, organic matters, microorganisms, decolorization, deodorization, etc.
(resin trap filter for mixed bed)
The filter material of the activated carbon filter is activated carbon, and the type and specification depend on the water quality requirements. The filter layer height is generally 1000-1600mm, and its working state is pressure type.
The activated carbon can absorb the organic matters and residual chlorine in the solution, reduce the COD value of the water, and prevent the free chlorine in the water from damaging the ion exchange resin and the reverse osmosis membrane.
It also has certain adsorption capacity for some cations. The cycle of filtration, backwashing, positive washing and backwashing of activated carbon filter by using the pressure of raw water is generally 3-6 days, which depends on the water quality of raw water. When the filtration time reaches a certain time or the difference between the inlet and outlet water pressure of activated carbon filter (P1-P2) is greater than 0.5MPa, backwashing is required. When the adsorption capacity of high-quality coconut shell activated carbon reaches When saturated, replace the activated carbon.
The activated carbon filter is filtered by pressure. When the raw water enters from the upper part of the filter and passes through the filter material layer from top to bottom, the organic matters in the water will be absorbed by the activated carbon particles, so as to separate them from the water, and the water will be further clarified.
As the filtration time continues, more and more impurities are trapped in the adsorption layer, the porosity is smaller and smaller, and the head loss is larger and larger.
At the end of the filtration cycle, the head loss reaches the limit value, or the adsorption layer has the maximum capacity of sewage interception. The continuous filtration will make the effluent quality worse. At this time, it is necessary to stop filtering and backwash.
(Johnson Screen Lateral Assemblies for carbon filter)
Security filter
The safety filter is the last guarantee to remove the small particles and suspended matters in the water, and ensure the normal operation of the reverse osmosis system.
If the concentration of the suspended solids is too high, it is easy to block the pores of the reverse osmosis membrane; if the particle size of the suspended solids is too large, when the suspended solids pass through the membrane surface at high speed, it is easy to scratch the desalting epidermis on the membrane surface.
The filter element in the filter is a replaceable cartridge filter rod with a filtering accuracy of 5 μ M, during operation, particles larger than 5 μ m cannot pass through and are retained. Particles smaller than 5 μ m may also be retained inside the filter element. The filter element needs to be replaced when the pressure difference between the inlet and outlet water (P2-P3) is greater than 0.05Mpa for about 3 months.