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Method for detecting content of chloride in water

A determination method and chloride technology, which are applied in the direction of chemical analysis, measuring devices, and preparation of test samples, etc., can solve problems such as the inability to grasp the changes of chloride in the condensed water of the device, corrosion of low-temperature parts, and large turbidity, etc. To achieve the effect of filling chlorides that cannot be accurately detected, improving accuracy, and improving the level

Inactive Publication Date: 2017-06-30
PETROCHINA CO LTD
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  • Abstract
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  • Claims
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Problems solved by technology

[0002] In the refining unit, the inorganic chlorine and organic chlorine in the crude oil are hydrolyzed or decomposed, and the low temperature parts of the primary and secondary processing units meet with water to form a hydrochloric acid composite corrosion environment, which promotes metal corrosion and causes comprehensive corrosion of carbon steel. Stainless steel Pitting corrosion and stress corrosion cracking, etc., resulting in severe corrosion of low-temperature parts, seriously affecting the safe operation of equipment, so it is necessary to analyze and monitor the chloride in the equipment medium
[0003] However, in the actual monitoring and analysis process, due to the large turbidity and complex composition of condensed water samples from refinery units such as catalytic, coking, hydrocracking and other units, it contains a large amount of sulfide (100mg / L~50000mg / L), ammonia nitrogen (500~10000mg / L) and other interfering media, especially the sulfide content in the condensed water of the hydrogenation unit is as high as several thousand or even hundreds of thousands, which seriously interferes with the determination of chloride
The existing technical standards "GB 11896-89 Determination of Chloride in Water Quality by Silver Nitrate Titration Method" and "GB / T3050-2000 General Method for Determination of Chloride Content in Inorganic Chemical Products Potentiometric Titration Method" cannot accurately detect chlorine in it. Therefore, it is impossible to grasp the changes of chlorides in the condensed water of the device in time, and it is impossible to prevent the corrosion hazards of chlorides on the equipment, which affects the quality of corrosion monitoring of the device, the implementation of corrosion protection measures and the safe production of the device

Method used

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  • Method for detecting content of chloride in water
  • Method for detecting content of chloride in water
  • Method for detecting content of chloride in water

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0022] Take 50mL of sodium chloride standard solution with a concentration of 10mg / L and place it in a 250mL beaker, adjust the water sample to pH 8-9 with 1mol / L sodium hydroxide solution, heat it on an electric furnace until the steam generated by heating no longer Turn wet pH paper blue. Then use 10% nitric acid to adjust the water sample to a pH value of 2 to 3, and continue heating on the electric furnace until the steam generated by heating does not blacken the wet lead acetate test paper. Add 1mL of 30% hydrogen peroxide, continue heating for 2 minutes, add deionized water in time to prevent drying during heating, cool the solution to room temperature, then transfer to a titration cup, adjust the volume of the water sample to 50mL with deionized water . Add 1 drop of 0.1% bromophenol blue indicator solution to the treated water sample, the water sample is dark yellow, adjust the color of the water sample to just yellow with 1mol / L sodium hydroxide solution, shake well,...

Embodiment 2

[0024] Take 50mL of sodium chloride standard solution with a concentration of 20mg / L and put it in a 250mL beaker, adjust the water sample to a pH value of 8-9 with 1mol / L sodium hydroxide solution, and heat it on an electric furnace until the steam generated by heating no longer Turn wet pH paper blue. Then use 10% nitric acid to adjust the water sample to a pH value of 2 to 3, and continue heating on the electric furnace until the steam generated by heating does not blacken the wet lead acetate test paper. Add 1mL of 30% hydrogen peroxide, continue heating for 2 minutes, add deionized water in time to prevent drying during heating, cool the solution to room temperature, then transfer to a titration cup, adjust the volume of the water sample to 50mL with deionized water . Add 1 drop of 0.1% bromophenol blue indicator solution to the treated water sample, the water sample is dark yellow, adjust the color of the water sample to just yellow with 1mol / L sodium hydroxide solution...

Embodiment 3

[0026] Take 20mL of the water sample to be tested with a sulfide content of 20.56mg / L and place it in a 250mL beaker, add 4mL of a sodium chloride standard solution with a concentration of 100mg / L to it, and adjust the total volume to about 50mL with deionized water. Use 1mol / L sodium hydroxide solution to adjust the water sample to a pH value of 8-9, and heat it on an electric furnace until the steam generated by heating no longer turns the wet pH test paper blue. Then use 10% nitric acid to adjust the water sample to a pH value of 3 to 4, and continue heating on the electric furnace until the steam generated by heating does not blacken the wet lead acetate test paper. Add 1mL of 30% hydrogen peroxide, continue heating for 3 minutes, add deionized water in time during the heating process to prevent drying, cool the solution to room temperature, then transfer to a titration cup, adjust the volume of the water sample with deionized water 50mL. Add 1 drop of 0.1% bromophenol bl...

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Abstract

The invention relates to a method for detecting the content of chloride in water. The method comprises the following steps: heating a to-be-detected sample when the pH value is 8-9, continuing to regulate the pH value to be 2-6, and heating; adding hydrogen peroxide into the sample, and heating; regulating the pH value to be 2-3 after the sample is cooled to room temperature, and performing potentiometric titration with a silver nitrate standard solution; and calculating the content of chloride in the to-be-detected sample according to the volume of the consumed silver nitrate standard solution when the titration destination is reached. The method is applicable to detection of content of chloride in high-sulfur condensate of a refining device, fills up the blank that high-sulfur condensate of the refining device cannot be accurately detected, and provides more accurate reference basis for regulating anti-corrosion measure of the device, so that a preventive anti-corrosion measure is adopted, and potential corrosion hazard of the equipment can be found and eliminated; and a certain reference effect is achieved for detecting corrosion of chloride in condensate of similar devices in China.

Description

technical field [0001] The invention relates to a method for measuring the chloride content in water, which is especially suitable for the determination of the corrosive medium chloride in the condensed water of various refining and chemical enterprises, especially key refinery equipment (including distillation, coking, catalysis, hydrocracking and ethylene, etc.). Monitoring analysis. Background technique [0002] In the refining unit, the inorganic chlorine and organic chlorine in the crude oil are hydrolyzed or decomposed, and the low temperature parts of the primary and secondary processing units meet with water to form a hydrochloric acid composite corrosion environment, which promotes metal corrosion and causes comprehensive corrosion of carbon steel. Stainless steel Pitting corrosion and stress corrosion cracking, etc., resulting in severe corrosion of low-temperature parts, seriously affecting the safe operation of equipment, so it is necessary to analyze and monitor...

Claims

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Application Information

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IPC IPC(8): G01N31/16G01N1/44
CPCG01N1/44G01N31/164
Inventor 郝新焕
Owner PETROCHINA CO LTD
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