CN104833770A - Method for judging invalidation of alkaline liquid used to remove hydrogen sulfide - Google Patents

Abstract

The invention discloses a method for judging invalidation of alkaline liquid used to remove hydrogen sulfide and belongs to the technical field of petrochemical industry. The method is characterized by including the following steps: 1), weighing and placing G grams of a to-be-detected alkaline liquid sample into a conical flask, adding A milliliters of distilled water for dilution, adding 1-2 droplets of phenolphthalein indicator, shaking well, using C mol/L of a hydrochloric acid standard solution for titration till colorless, and recording volume V1 of the hydrochloric acid standard solution which is consumed; 2), adding methyl orange indicator, continuing titration until the solution appears to be shallow red, and recording volume V2 of the hydrochloric acid standard solution which is consumed; 3), using A milliliters of distilled water, and adding methyl orange indicator for a blank experiment, recording volume V0 of the hydrochloric acid standard solution which is consumed, and calculating according to a formula: alkali concentration (%)=C(V1-V2-V0)x0.04x100/G. A double-indicator method is adopted to detect accurate valid content of sodium hydroxide in absorbing liquid after absorbing hydrogen sulfide, and the accurate valid content is used as a basis whether the alkaline liquid is replaced or not. By the method, valid content of sodium hydroxide in the alkaline liquid can be detected effectively, a reference basis is provided for desulfuration operation of the alkaline liquid, and replacement is performed according to the valid content of sodium hydroxide in the alkaline liquid.

Description

A kind of method judging depriving hydrogen sulphide alkali lye inefficacy used

Technical field

The present invention relates to a kind of method that depriving hydrogen sulphide alkali lye used lost efficacy that judges, belong to technical field of petrochemical industry.

Background technology

Hydrogen sulfide gas is the accessory substance in petrochemical production process, has the features such as severe toxicity, stench, quantity is large, is one of important pollution source of petroleum chemical enterprise.In petroleum chemical enterprise, the tail gas containing sulfuretted hydrogen is generally by being further processed after alkali liquor absorption.

In prior art, be used for removing sulfuretted hydrogen alkali lye used use after concentration reach how much, whether lose desulfurized effect, rule of thumb can only judge at present, when alkali lye lost efficacy, change in time and also there is no clear and definite foundation and standard.Can cause waste if change too early alkali lye because of its excessive concentration, after the too low or alkali lye of concentration of lye loses efficacy, replacing can cause desulfurized effect poor, and product quality is defective.

Summary of the invention

The invention provides a kind of method that depriving hydrogen sulphide alkali lye used lost efficacy that judges, adopt double-tracer technique, detecting the accurate and effective content of NaOH in absorbing liquid after absorbing hydrogen sulphide, as determining whether the foundation changing alkali lye.Method of the present invention effectively can detect the effective content of NaOH in alkali lye, provides reference frame for alkali lye desulfurization operations.And change according to the effective content of NaOH in alkali lye, preventing because when alkali lye is changed, excessive concentration causes waste, avoiding causing the underproof situation of product quality because changing alkali lye again after inefficacy.

The technical scheme that the present invention specifically adopts is:

Judge to it is characterized in that the method that depriving hydrogen sulphide alkali lye used lost efficacy, comprise the steps:

1) take G gram of alkali lye sample to be measured in conical flask, add the dilution of A ml distilled water, add phenolphthalein indicator 1 ~ 2, shake up rear C mol/L hydrochloric acid standard solution and be titrated to colourless, write down the volume V of the hydrochloric acid standard solution of consumption ₁;

2) then add methyl orange indicator, continue to be titrated to solution and present light red, write down the volume V of the hydrochloric acid standard solution of consumption ₂;

3) add methyl orange indicator with A ml distilled water and do blank test, write down the volume V of the hydrochloric acid standard solution of consumption ₀, according to following formulae discovery:

Alkali concn (%)=C (V ₁-V ₂-V ₀) × 0.04 × 100/G.

Reaction equation in process of the present invention is:

NaOH+HCl→NaCl+H ₂O

Na ₂S+HCl→NaHS+NaCl Na ₂CO ₃+HCl→NaHCO ₃+NaCl (1)

NaHS+HCl→H ₂S+NaCl NaHCO ₃+HCl→H ₂O+CO ₂↑+NaCl (2)

Wherein, step 1) reaction end pH value is 8.0 ~ 8.5, adds the total content that phenolphthalein indicator (color change interval 8.0 ~ 9.6 becomes redness from colourless) first detects NaOH in alkali lye, sodium sulphide, sodium carbonate; Step 2) reaction end pH value is 3.0 ~ 4.0, adds the content that methyl orange indicator (color change interval 3.1 ~ 4.4, becomes yellow from redness) detects sodium sulphide and sodium carbonate.

The beneficial effect of this method is:

Can changing according to the effective content of NaOH in alkali lye, prevent from causing waste because concentration of lye is too high when changing, avoiding causing the underproof situation of product quality because changing alkali lye again after inefficacy.

Embodiment

The present invention is described in detail below.

One, preliminary work:

1. instrument:

Acid buret (25ml, calibration 0.1ml), conical flask (250ml), drop bottle (25ml), pipette (5ml, 10ml).

2. agents useful for same:

Hydrochloric acid standard solution (0.5mol/L), phenolphthalein indicator (1.0%), methyl orange indicator (0.1%), distilled water (test front acidometer and measure pH value, ensure that distilled water pH value is between 7.0 ~ 7.5).

3. sampling method

Being cleaned by plastic bottle dries up for subsequent use, gets representational alkali lye sample 100ml with plastic bottle with cover.

Two, operation steps:

1. take 2.0 grams of alkali lye samples to be measured in conical flask, add 50ml distilled water, 2 phenolphthalein indicators, shake up rear 0.5mol/L hydrochloric acid standard solution and be titrated to colourless, write down the volume V of the hydrochloric acid standard solution of consumption ₁(ml).

2. in conical flask, add 3 methyl orange indicators, continuation hydrochloric acid standard solution is titrated to solution and presents light red, writes down the volume V of the hydrochloric acid standard solution of consumption ₂(ml), add 3 methyl orange indicators with 50ml distilled water simultaneously and do blank test, write down the volume V of the hydrochloric acid standard solution of consumption ₀(ml), according to formulae discovery.

Three, calculation procedure

According to formula:

Alkali concn (%)=C (V ₁-V ₂-V ₀) × 0.04 × 100/G

The concentration of C-hydrochloric acid standard solution

V ₁the volume (ml) of the hydrochloric acid standard solution that NaOH and sodium sulphide and sodium carbonate consume in-titration alkali lye

V ₂the volume (ml) of the hydrochloric acid standard solution that NaHS and sodium bicarbonate consume in-titration alkali lye

V ₀the volume (ml) of the hydrochloric acid standard solution that-titration 50ml distilled water consumes

The quality (g) of alkali lye sample is taken in G-test

The mM mass number of constant 0.04-NaOH

The statistics of this method precision:

Alkali lye content, %	Repeatability, is not more than following numerical value	Repeatability, is not more than following numerical value
			0.5-5.0	Be not more than 2% of average result	Be not more than 4% of average result
5.0-20.0	Be not more than 3% of average result	Be not more than 4% of average result

This shows: repeatability is not more than 2% of average result, repeatability is not more than 4% of average result.

Four, advantage of the present invention

Before enforcement, change and remove sulfuretted hydrogen alkali lye used and can only rule of thumb judge, change alkali lye too early because of its excessive concentration and can cause waste, after the too low or alkali lye of concentration of lye loses efficacy, replacing can cause desulfurized effect poor, and product quality is defective.

After enforcement, effectively can detect the effective content of NaOH in alkali lye, for alkali lye desulfurization operations provides reference frame.And change according to the effective content of NaOH in alkali lye, preventing from causing waste because concentration of lye is too high when changing, avoiding causing the underproof situation of product quality because changing alkali lye again after inefficacy.

Claims (1)

1. judge to it is characterized in that the method that depriving hydrogen sulphide alkali lye used lost efficacy, comprise the steps:

1) take G gram of alkali lye sample to be measured in conical flask, add the dilution of A ml distilled water, add phenolphthalein indicator 1 ~ 2, shake up rear C mol/L hydrochloric acid standard solution and be titrated to colourless, write down the volume V of the hydrochloric acid standard solution of consumption ₁;

2) then add methyl orange indicator, continue to be titrated to solution and present light red, write down the volume V of the hydrochloric acid standard solution of consumption ₂;

3) add methyl orange indicator with A ml distilled water and do blank test, write down the volume V of the hydrochloric acid standard solution of consumption ₀, according to following formulae discovery:

Alkali concn (%)=C (V ₁-V ₂-V ₀) × 0.04 × 100/G.