Technical performance comparison between mixed bed and EDI process
Technical and economic performance comparison between EDI and mixed bed process in a 60t/h desalinated water project:
1. Operation comparison
(1) Mixed bed
In
the effective exchanger, the effluent water quality is stable, and once
the failure end point is reached, the effluent conductivity will rise
sharply. Factors such as worker operation level, regenerant quality,
resin quality, and pretreatment water quality will affect the
regeneration cycle.
At least one mixed bed should be spared in the system to reduce the risk of mixed bed failure.
(2) EDI
EDI operation does not require additional acid-base regeneration, which can save a lot of labor. No waste water treatment system is required, and the operating current can be adjusted if the effluent conductance increases.
2. Operation comparison
(1) Mixed bed
Mixed bed regeneration takes a long time, and needs to be exposed to acid and alkali during regeneration, which has certain dangers. Although fully automatic regeneration is possible, manual intervention is required.
(2) EDI
EDI is composed of several identical modules. The EDI module is turned on or off according to the actual use of pure water. The manual operation is relatively frequent, but the valve is relatively simple. It only needs to open the EDI water inlet valve, the extreme water valve and the concentrated water valve, and Turn on the power and adjust the electrolysis voltage and current according to the water quality.
3. Cost comparison
(1) One-time investment comparison
mixed bed
Adopt 60t/h ultrafiltration + reverse osmosis + mixed bed
The full set of equipment includes: equipment configuration +
transportation + pipe fittings + electronic control + debugging +
installation ≈ 3.15 million
Workshop area: 1450m2
A 100m3 acid-base neutralization pool needs to be set up outdoors
EDI
Adopt 60t/h ultrafiltration + reverse osmosis + EDI
The full set of equipment includes: equipment configuration +
transportation + pipe fittings + electronic control + debugging +
installation ≈ 3.8 million
Workshop area: 1150m2
(2) Comparison of operating costs
mixed bed
Mixed bed regeneration cycle is 24h
The cost of each regeneration of acid and alkali is about 752 yuan, and the annual cost is about 270,000 yuan
Labor costs 8 people * December * 4,000 yuan / month = 384,000
Renewable electricity fee 15kW*360 days*0.65 yuan/kWh=03,500 yuan
The total annual operating cost is 657,500 yuan
EDI
Electricity fee 0.24 kWh/ton*720 ton*0.65 yuan/kWh*360=40,000 yuan
Labor costs 8 people * December * 4,000 yuan / month = 384,000
The total annual operating cost is 424,000 yuan
(3) Comparison of maintenance costs
mixed bed
The diameter of the mixed bed is 1.6m, and the resin replacement cycle is 3 years
The quantity of cation resin is 5.2t, the quantity of anion resin is
2.6t, and the replacement price of resin is
5.2t*17,000/ton+2.6t*08,000/ton=109,000 yuan
The average annual maintenance cost is 109,000 yuan / 3 years = 36,400 yuan
EDI
The number of EDI modules is 12, and the service life is 3 years
The module replacement price is 12 yuan * 30,000 yuan / block = 360,000 yuan
The average annual maintenance cost is 420,000 yuan / 3 years = 120,000 yuan
Fourth, the comparative analysis summary
(1)
Advantages of mixed bed: low initial investment in equipment; stable
effluent quality; simple pretreatment requirements; high water
utilization rate
(2) Disadvantages of mixed bed: low utilization
rate of resin exchange capacity and large loss; acid-base regeneration
has hazardous waste liquid discharge; bacteria are easy to multiply in
the bed; there are many valves, and the operation is complicated; the
operation weight is high and the occupied area is large
(3) EDI
advantages: stable effluent quality; no acid-base regeneration, no
hazardous waste liquid discharge; continuous operation, simple
operation; low operating cost; small footprint; easy installation and
maintenance
(4) Disadvantages of EDI: large initial investment; high requirements for preprocessing
