Plate heat exchanger in a longer period of time, the lubrication of heat transfer occupies a very large, general media are not corrosive, do not have to worry about plate heat exchanger plate corrosion and rubber gaskets to produce swelling, aging and other conditions. But the chemical plate heat exchanger application medium, in addition to water, the vast majority of poor, rich liquid and sodium hydroxide, sulfuric acid and other chemical media, easy to make plate heat exchanger plate corrosion and rubber gasket swelling, aging, so the whole process of selecting always pay attention to the plate and rubber gasket material is suitable for its medium, sealing rubber gasket material selection is particularly important.
Plate heat exchanger plate material selection
1, clean water, river water, edible oil, mineral oil and other media, plate material is usually selected stainless steel (AISI 304, AISI 316, etc.).
2, seawater, salt water, saline and other media, plate materials are generally selected titanium and titanium-palladium (Ti, TiPd).
3, dilute sulfuric acid, dilute sulfur salts aqueous solution, inorganic aqueous solution and other media, plate material selection 20Cr, 18Ni, 6Mo (254SMO) and other alloys.
4, high temperature, high concentration of caustic soda media, plate material selection of nickel Ni.
5, concentrated sulfuric acid, hydrochloric acid, phosphoric acid medium, plate material selection HASTELLOY alloy (C276, D205, B20).
Plate heat exchanger rubber gasket material selection
The vast majority of people understand the rubber sealing gasket is commonly used materials for EPDM, nitrile rubber, hydrogenated nitrile rubber, fluorine rubber and other categories.
EPDM: the use of temperature -25 ~ 180 ℃, suitable for fluid medium hot water, water vapour, atmospheric ozone, non-petroleum-based lubricants, weak acids, weak bases, ketones, alcohols, esters and so on.
Nitrile rubber NBR: the use of temperature -15 ~ 130 ℃, suitable for fluid medium light and heavy fuel oil and other types of mineral oils, lubricants, animal and vegetable oils, hot water, salt water and so on.
Hydrogenated nitrile rubber HNBR: the use temperature is -15 ~ 160 ℃, suitable for fluid medium high temperature water, crude oil, sulfur-containing oils and organic sulfur compounds, part of the heat transfer oil, the new refrigerant R134a, ozone environment.
Fluorine rubber FKM: the use of temperature -15 ~ 200 ℃, suitable for fluid medium concentrated sulfuric acid, caustic soda, heat transfer oil, alcohol-containing fuel oil, acidic fuel oil, high-temperature water vapour, chlorine water, phosphate, etc..
Chemical industry production process in the medium is more complex, especially a variety of chemical substances mixed with the fluid medium, in a certain temperature, pressure conditions will occur under the chemical reaction to generate new substances.
When the lack of rubber sealing gasket in a certain mixture of media in the use of experience, should be in advance to stand on the gasket immersion test, the rubber sealing gasket immersed in the medium to measure the expansion of the gasket, hardness and sensitivity to chemical corrosion. According to ISO 15547-1-2005 Appendix A recommendations, the test with a maximum of 8mm thick gasket material in the gasket at the temperature of the test, the minimum duration of the test for 15 days. Determine whether the rubber sealing gasket in the medium is suitable for the standard: rubber sealing gasket material hardness change does not exceed 10 IRHD (fluorine rubber gasket hardness shall not exceed 15 IRHD) (IRHD for the international rubber hardness unit), the volume change shall not exceed 15 per cent.
But because now the market demand for rubber gaskets fierce, and this year, synthetic rubber, carbon black and other raw material prices, there are some gasket manufacturers in order to better survive are not adjusted prices, only to reduce costs may not lose money, only the second best, plus some additives are likely to react with the raw materials of the chemical plant, it is the composition of the gasket and the process of performance of the stringent requirements to ensure that it reaches the chemical with the Plate heat exchanger working condition application regulations.
These are chemical plate heat exchanger selection to pay special attention to the place, must do scientific selection in order to ensure the normal use of subsequent plate heat exchanger equipment!
