At present, the washing of fabrics such as hotels, social catering and large baths is gradually completed by professional washing companies.
With more and more business competition, improving service models and reducing washing costs have become the core of corporate competition. Steam, a major energy source in the washing industry, plays a key role in reducing washing costs.
The pressure of various equipment in the laundry room varies. For example, the ironing machine, the pressure is lower than 6gar g, the effect will not work, and the steam pressure of the dryer is preferably kept at about 4bar g. However, when the condensed water produced by the dryer and the ironing machine is discharged to atmospheric pressure, a large amount of secondary steam is generated. If it is directly discharged, it not only pollutes the environment, but also causes huge energy waste.
How to use this part of the steam to the low-voltage equipment (such as ironing table or imaging machine) is necessary. At the same time, the remaining condensate is recovered to the soft water tank of the boiler. Rick has been committed to effective solutions and practical applications in this area.
The following are the technical solutions and engineering cases we have done for a washing company in Shanghai. The customer's ironing machine uses a pressure of 13barg and a flow rate of 3000kg/hr.
1, flash tank selection
Flash tank steam calculation:
Inlet steam pressure: 13barg
Flow rate: =3000kg/h
Take the steam pressure 2barg required by the washing machine as an example.
13barg saturated water enthalpy value: 830kJ/kg
3barg saturated water enthalpy value: 605kJ/kg
3barg saturated water evaporation latent heat: 2133kJ/kg
and so:
The secondary steam ratio is: (830-605)/2133=10.5%
The amount of flash steam is: 3000*10.5%=323kg/h
2, decompression station selection
Replenishing steam through a decompression station
400+19.8+9.9-380=50kg/h
Therefore, the DN25 PRV2000 pressure reducing valve meets the requirements.
I. Investment recovery period, taking oil-fired boiler as an example of energy-saving calculation
1. Fuel saved by condensate recovery
Assume that the temperature of the recovered condensate is 90 ° C (the trap outlet temperature)
Boiler feed water temperature 10 °C (tap water temperature)
Temperature difference 80 ° C
For condensed water not recycled to the boiler system, for every 1 kg of cold feed water to 90, the energy required for 80* is
1*80*4.1868=335KJ
4.1868kJ/kg °C is the specific heat of water
The amount of condensate recovered in the laundry room is 2980kg/hr. The required energy is:
335*2980=998300kJ/h
Assume that the laundry room runs 12 hours a day, 7 days a week, 50 weeks a year, and the energy required to heat the cold make-up water every year.
998300*12*50*7=4.2*109KJ
Assuming that the diesel heat value is 41000 KJ/L and the actual boiler efficiency is 80%, the fuel required to heat the cold feed water is 4.2*109/41000/0.8=1.28*105L per year.
Assume that the fuel cost is 3.5 yuan / L. Then the required RMB:
1.28*105 *3.5=448000 yuan
2, the cost of water
Annual water consumption 12*7*50*2980/1000=12516 tons
Assume that the water cost is 2.5 yuan / ton. Then the required RMB
2.5*12516=31290 yuan
3, water treatment costs
Assume that the water treatment is 1.1 yuan / ton. The total water treatment fee is:
1.1*12516=13768 yuan
4. The cost of discharging high temperature hot water into the urban pipe network (cost required to reduce the temperature to allow the discharge temperature - omitted)
5, boiler sewage charges (because the condensed water is very clean, it can reduce the amount of boiler blowdown, thus saving boiler heat loss)
The total cost savings from condensate recovery is
448000+31290+13768=493058 yuan
6. Secondary steam recovery energy saving calculation
The latent heat of 3barg steam is 2133KJ/kg, the heat value of diesel is 41000KJ/L, and the boiler efficiency is calculated as 80%. The secondary steam is 323kg/h.
323*2133/41000/0.8=21L/h
Assuming that the laundry room runs 12 hours a day, 7 days a week, 50 weeks a year, the amount of oil required for the secondary steam generated each year is:
21*12*50*7=88200L/YEAR
Assume that the fuel cost is 3.5 yuan / L. Then the required RMB:
88200*3.5=308700 yuan
In total, the total savings of RMB: 493058+308700=801759 yuan
The investment cost of equipment such as Rick flash tank, condensate recovery pump and pressure reducing valve is about 100,000 yuan. In addition to pipeline construction projects, the payback period is less than six months.
First, the system benefits
1. The recovery of high-temperature condensed water reduces the amount of oxygen and carbon dioxide in the cold water of the boiler from 10% to 2% (the oxygen and water temperature dissolution curve is known, and the weak acid formed by oxygen and carbon dioxide and condensed water is the boiler, The main reason for corrosion of pipes, valves and heat exchangers is the importance of condensate recovery for boiler systems without deaerators, not only for energy savings, but also for reducing system corrosion.
2. The normal temperature boiler feed water will cause the boiler water pipe to explode frequently and cause the boiler life to be shortened.
3. The heat capacity of the high-temperature make-up water will play a buffering role when the steam load fluctuates greatly, improve the boiler efficiency, reduce the pressure fluctuation, and at the same time reduce the steam quality caused by the boiler soda water coexisting due to avoiding the load fluctuation.
4. Since the condensate itself is pure water, it does not need to be chemically treated. In this way, the overall chemical corrosion will also be reduced, and the boiler discharge amount will be reduced to save energy.
5. Avoid high temperature and high pressure condensate directly discharged into the atmosphere. The secondary steam generated by flashing is beneficial to the environment.
Second, the effect after use
1. It avoids the phenomenon that steam is seen everywhere in the laundry room (to prevent the steam from leaking, reducing heat loss and heat pollution and being more environmentally friendly).
2. Reduce the cost of water treatment, reduce the amount of boiler blowdown, and reduce the oxygen content.
3. The working environment of workers has been greatly improved.
4, the system application is very stable, and save more than 20% of fuel than before.