CS223394B1 - Method of passivation and inhibition of the heat exchangers - Google Patents

Abstract

Surface exchanger se after cleaning passivates passivating solution who contains 0.05 to 1 % wt. benzotriazole, 0.05 to 1 % wt. tannin and 0.1 to 2 % wt. alkanolami- ment unsaturated fatty acids, after for # led pasivaei se passivation solution nadáv # kuje to cooling circuit in concentration effective substances 5 to 50 ppm wt.

Description

The invention relates to a process for the passivation and inhibition of brass heat exchangers.

During intensive operation, various layers are formed on the surface of brass heat exchangers from the cooling water side, mostly of an incrustating and corrosive nature. In order to maintain the original efficiency of the device, it is normally carried out with mineral acid cleaning and passivation of the brass surface with various passivation solutions.

The lifetime of the protective film can be extended by using the passivation and inhibition method of the brass heat exchangers according to the invention, characterized in that the surface of the exchanger after cleaning is passivated with a passivation solution containing 0.05 to 1% by weight. % benzotriazole, 0.05 to 1 wt. % tannin and 0.1 to 2 wt. of the alkanolamides of unsaturated fatty acids, after passivation, the passivation solution is metered into the cooling circuit at an active compound concentration of 5 to 50 ppm by weight.

This process of passivation and subsequent inhibition with a substantially diluted passivation solution represents the maximum utilization of the substances used and there is no need to dispose of the passivation solution residues, as in the case of chromium salt solutions, after passivation.

The chemisorption film formed on the dewatered surface of brass exchangers does not have the character of an oxidation layer and its electrochemical potential is not as different from the parent metal as in the case of a brass-oxidation layer formed in chromate solutions. The passivating agent according to the invention, which forms a chemisorption film, guarantees, in addition to its subsequent use as an inhibitor for cooling circuits, a longer lifetime of the passivation film under the operating conditions of brass capacitors and thus greater corrosion resistance and higher thermal efficiency of the whole device.

The composition, its composition and use are further illustrated in an exemplary embodiment.

Example

The brass capacitor, after routine purification with hydrochloric acid, was passivated with a solution containing 1 kg of benzotriazole, 1 kg of tannin and 2 kg of unsaturated coconut fatty acid alkanolamides per ton of passivation solution. After passivation, the passivation solution was metered into the cooling circuit, with the active ingredient concentration in the cooling water being 20 ppm. Using the passivation solution used, 200 tonnes of additional cooling water were inhibited. This process achieved long-term passivation of the brass capacitors surface and consequent inhibition of the polymetallic system contained in the cooling circuit ensured better enthalpy gradient and higher efficiency of the whole heating system due to better heat transfer through the condenser wall. .

Claims (1)

SUBJECT Method for the passivation and inhibition of brass heat exchangers, characterized in that, after cleaning, the surface of the exchanger is passivated with a passivating solution containing 0.05 to 1% by weight. % benzotriazole, 0.05 to 1 wt. % tannin and 0.1 to 2 wt. % of alkanolamides of unsaturated fatty acids and after passivation, the passivation solution is metered into the cooling circuit, at a concentration of active substances of 5 to 50 ppm by weight.