JPS6261693A - Method for treating boiler degreasing/washing solution - Google Patents

Abstract

PURPOSE:To decompose hydrazine, by a method wherein sodium chloride is added to and mixed with a hydrazine-containing degreasing/washing solution and the resulting mixture is subsequently electrolyzed. CONSTITUTION:1,000mg/l or more of NaCl is added to the hydrazine-containing degreasing/washing solution of a boiler. Subsequently, N2H4 is decomposed to N2 and H2O by electrolysis. By this method, the decompositional removal of N2H4, COD and an oil component can be almost perfectly performed.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for treating boiler degreasing cleaning waste liquid.

[Conventional technology]

The boiler degreasing waste liquid was treated by air packing, etc., but it took several days to process.

Water-soluble oil used for expanding the boiler tube during construction of the boiler remains in the boiler.
o o mp7z concentration of hydrazine is added,
2~s kg/cr/l pressure, 120~140°
We use a method of boiling for several hours at a temperature of about 0. Therefore, the waste liquid after cleaning contains a high concentration of hydrazine (approximately 200%
ml/l) remains. Since these waste liquids contain hydrazine and are harmful, it is necessary to decompose the hydrazine.

Previously, hydrazine was decomposed by blowing air or adding an oxidizing agent, but it took a long time to decompose,
Chemicals such as oxidizing agents were required, and hydrazine remained after treatment.

[Problem that the invention seeks to solve]

An object of the present invention is to provide a method for treating a boiler degreasing liquid that eliminates the drawbacks of the above-mentioned prior art and can almost completely decompose and remove VcNtH4, CO and oil components in a short period of time. Means for Solving the Problem] The present invention provides a boiler degreasing method characterized in that sodium chloride is added to and mixed with a hydrazine-containing degreasing liquid in an amount of 10 o o my/z or more, and then the mixed liquid is electrolyzed to decompose the hydrazine. The present invention relates to a cleaning liquid processing method.

[Effect]

Boiler degreasing cleaning waste liquid KNaOI! 1 o o a m
y/ is added, and then electrolysis is performed to decompose NtHa into N, PI, and OK.

(Electrolytic reaction) Anode: 20/-m-→O/, + 2e Cathode: 2N
a" + 2H++ 20M-+ 2 e-1 → H, ↑
+2NaOII as a whole M" + 0/-+ H, O-→Na010 + H,
↑(Hydrazine decomposition reaction) N, H, + 2NaOtO= 2NaO/ + 24
01N.

That is, the present invention provides Naozo Ic, υN, llI generated by electrolysis of Na0j aqueous solution without using a diaphragm.
Thus, in the present invention, sodium chloride may be added in an amount that produces dietary Na010 that can decompose hydrazine through the above-mentioned hydrazine decomposition reaction. When electrolyzing an IJium aqueous solution with a low solution resistance, the voltage during electrolysis is small and it is difficult to perform electrolysis, so adding sodium chloride in an amount that increases the solution resistance is necessary. It becomes necessary. In order to satisfy the need for such an amount of sodium chloride, the amount of sodium chloride is generally set at 1000 ml/l or more in the present invention, which is directed to boiler degreasing cleaning waste liquid.

〔Example〕

Degreasing cleaning waste liquid 11K containing 200 my of hydrazine
After adding Na0t21, electrolysis was performed using an electrode with an electrolytic area of 12 cII.

Degreasing cleaning waste liquid: 1 t (N, H4200rnll/!
) Nap/Additional amount: 2F (2ooomp/z) (Electrode bath conditions) Electrode area* 30x40B Cathode material: 5trss16r.

Anode material: rt + pt Distance between middle electrodes: 10 ■ Current density: 15 m/d Electrolysis time: 15 minutes Treatment result [Effects of the invention] Boiler degreasing waste liquid K Naolt- Addition and electrolysis. ), Nt Ha e 00''+ oil can be almost completely decomposed and removed in a short time.

Sub-agent: 1) Akira Sub-agent Ryo Hagi Hara - Sub-agent Atsuo Yasunishi

Claims (1)

[Claims] Add 100% sodium chloride to the hydrazine-containing degreasing cleaning solution.
A method for treating a boiler degreasing liquid, which comprises adding and mixing 0 mg/l or more, and then electrolyzing the mixed liquid to decompose hydrazine.