|
|
|
|
|
|
|
|
|
|
Clean plate heat exchanger
|
|
In recent years. Plate heat exchanger with its light weight, cover an area of an area small, less investment, high thermal efficiency, the assembly for flexible, scale is easy to remove etc. Characteristics. In all walks of life process has been gradually push
Wide use. But because of plate heat exchanger circulation section is smaller. After scaling the clogging easily, make the thermal efficiency of plate heat exchanger in exchange for reduced, which affect the equipment of security and user
Normal use. So. Solve the cleaning of plate heat exchanger, to prevent scale formation. Will become ensure the safety in production and economic operation of the subject.
Plate heat exchanger in use process. Because water treatment equipment improper operation. Water quality control is not eligible, will not qualified to soften water injection system, make water calcium, magnesium,
Carbonate encounter heat decomposition for calcium carbonate and after magnesium hydroxide sediment in the heat exchanger stick on heating, form the hard scale. Because of the scale heat conduction performance is poor, caused the heat transfer
The thermal efficiency of the change is decreased and the serious waste heat energy. Which affect the heat transfer effect.
Plate heat exchanger and scaling of the cleaning method
1, cleaning agents choice
The choice of cleaning agents, the currently used is pickling, it including organic acids and inorganic acid. Organic acid mainly has: oxalic acid, formic acid, etc. Inorganic acid mainly has: the hydrochloric acid, nitric acid, etc
. According to the heat exchanger scale and technology, material and scale composition analysis:
1) heat exchanger circulation area is small, the internal structure is complex, cleaning solution if not easily produce precipitation emissions.
2) heat exchanger for nickel titanium alloy material, use hydrochloric acid for cleaning solution. Easy to produce strong corrosion of plate, shorten service life of the heat exchanger.
Through the trial found that choose formic acid as best cleaning fluid. Add in formic acid cleaning fluid slow granule and surface active agent, cleaning effect is better, and may reduce the qing dynasty
Lotion to the corrosion of the plate. Through to the scale of the sample chemical experiment showed that formic acid can effectively remove scale. Through the acid soak experiment, discover the formic acid can effectively remove
Attached to the plate on the scale, at the same time it on the heat exchanger plate corrosion function also is very small.
2, remove scale basic principle
1) dissolve role: acid solution easily and calcium, magnesium, carbonate scale reaction, generating soluble compounds, make scale dissolve.
2) dissection of the action: acid solution can dissolve the surface of the metal oxides. The combination of destruction and scale. So that adhere to the metal oxide surface scale detachment. And fall off down
.
3) gas lift role: acid solution and calcium, magnesium, carbonate scale after the reaction, have a lot of carbon dioxide. Carbon dioxide gas in the process of overflow. For the undissolved or to dissolve
Solution a slower scale layer, has some of the lift power, make scale heat exchanger from off the surface.
4) loose role: containing silicate and sulphate mixed scale, because of calcium, magnesium, carbonate and iron oxide dissolved in acid solution, residual scale will be forgotten
Loose, it is easy to be washed down the flow of acid solution.
3, cleaning scale process requirement
1) pickling temperature: to improve pickling temperature to improve or effect. If temperature too gao will aggravate acid liquid on the heat exchanger plate corrosion, through repeated test found that pickling temperature control in 60 ~ E advisable.
2) acid liquid concentration: according to repeated test that acid liquid should press formic acid 81. O %, water 17. O %, slow granule 1.2%, 0.8% of the surfactant concentration configuration, cleaning effect is excellent.
3) pickling method and time: pickling method should be static and dynamic cycle for the method of combining the. Pickling time first static for 2 h, then dynamic circular 3 ~ 4
H. In pickling process should be often sampling test acid concentration, when two adjacent difference assay concentration below 0.2%, can think pickling response to an end.
4) passivation treatment: after pickling, plate heat exchanger surface scale and metal oxide most be dissolved fall off, exposed the new metal, extremely easy corrosion, so in pickling, on the heat exchanger plate for passivation treatment.
4, cleaning scale of the specific steps
1) blunt washing: pickling before, first to heat exchanger was off flush, make no internal heat exchanger mud, the impurities such as scale, such already can improve the pickling effect, also can reduce the consumption of acid pickling.
2) will pour cleaning person cleaning equipment, and then into the heat exchanger.
3) pickling: will fill the acid solution of the static heat exchanger for 2 h. Then continuous dynamic circular 3 ~ 4 h. Meanwhile every 0.5 h for cleaning and alternate. After pickling, if acid pH value greater than 2, acid can be duplicated, otherwise, should will dilute acid liquid and back off.
4) soda-wash: after pickling, with NaOH, Na, PO, softening water according to certain proportion good preparation, and the dynamic circle on the heat exchanger in alkaline cleaning black stain, achieve acid &alkali neutralization, make plate heat exchanger no longer corrosion.
5) water: soda-wash ended, with clean water softener. Repeated on the heat exchanger flushing 0.5 h, will be in the heat exchanger rinse clean thoroughly residue.
6) record: cleaning process, should strictly recording the steps of the time, to check for cleaning effect. In short, after cleaning, to heat exchanger was down test. After passing
Can be used.
3, prevent plate heat exchanger and scaling measures
1) in the operation of the water quality pass strictly, it is necessary to the water system and soften the tank in the middle of the softening water on the strict quality testing, qualified to note one network.
2) the new system are put into operation, we should take the heat exchanger and system apart, for a period of time after cycle, then heat exchanger and people system. To avoid the network impurities in heat exchanger.
3) in the system, decontamination, and filter on cleaning shall be outside, still should keep the pipeline network in clean, in order to prevent the blockage of the heat exchanger.
To sum up. Plate heat exchanger in strict accordance with the cleaning method for cleaning, the normal operation of production is important
|
|
|
|
|
|
|
|
|
|
|
