CN104931593A - Method and system for analyzing trace hydrogen sulfide and total chloride in methanation feed gas - Google Patents

Abstract

The invention provides a method for analyzing trace hydrogen sulfide and total chloride in a methanation feed gas by ion chromatography. The method comprises the following steps: (1) carrying out absorption treatment on the methanation feed gas to obtain a strong alkaline aqueous solution which has absorbed sulfur ion and chloride ion, and recording flow of the methanation feed gas; and (2) adding hydrogen peroxide into the strong alkaline aqueous solution obtained from the step (1), heating at 65-70 DEG C for 10-20 min, cooling, reaching to a constant volume, filtering and analyzing a filtrate by ion chromatography. The method provided by the invention has advantages of low toxicity, high efficiency, accurate analysis and high sensitivity. In addition, instrument operation is convenient, and degree of automation is high. Work efficiency of operators is raised.

Description

Analyze the method and system of trace sulfuretted hydrogen and total chloride in methanation unstripped gas

Technical field

The present invention relates to methanation technology field.Particularly, the present invention relates to a kind of trace analysis methods and system, particularly a kind ofly utilize the method for trace sulfuretted hydrogen and total chloride in ion chromatography analysis methanation unstripped gas and realize absorbing in this analytical approach the system for the treatment of step.

Background technology

China's coal preparing natural gas, olefin hydrocarbon making by coal, ammonia from coal are flourish, most Coal Chemical Industry technique adopts Coal Gasification producing synthesis gas and then is converted into produce clear energy sources and alternative petrochemicals are master, as diesel oil, gasoline, aviation kerosene, liquefied petroleum gas (LPG), polyethylene raw material, pp material, methyl alcohol, dimethyl ether, and the peculiar chemical products of the unique advantage of Coal Chemical Industry, as arene product.

In coal preparing natural gas production run to methanation unstripped gas in each component concentration require more and more stricter, especially effective catalyst is produced to the chloride (such as hydrogen chloride and chlorohydrocarbon (C1 ~ C4)) and ultratrace sulfuretted hydrogen of poisoning.Organochlorine is converted into inorganic chlorine through methanation device hydrogenation reaction, and its content height directly affects the corrosion of methanation device equipment and the serviceable life of catalyzer.

At present, the method analyzing trace sulfuretted hydrogen and total chloride in methanation unstripped gas adopts mercuric thiocyanate spectrophotometric method, but the method need use hypertoxic chemicals mercuric thiocyanate when sample pre-treatments, and this is very serious to the murder by poisoning of analytical work person.Therefore, the analytical approach developing a kind of effective, low murder by poisoning is necessary.

Summary of the invention

For above-mentioned technological deficiency, the object of this invention is to provide and a kind ofly utilize the method for trace sulfuretted hydrogen and total chloride in ion chromatography analysis methanation unstripped gas and realize absorbing in this analytical approach the system of process, thus the working environment of analytical work person is improved, significantly alleviate toxic action.

Above-mentioned purpose of the present invention is achieved through the following technical solutions:

On the one hand, the invention provides a kind of method utilizing trace sulfuretted hydrogen and total chloride in ion chromatography analysis methanation unstripped gas, the method comprises the following steps:

(1) absorption process is carried out to methanation unstripped gas, sulfuretted hydrogen and muriatic strong base solution in the described methanation unstripped gas that has been absorbed with strong base solution, and record the flow of described methanation unstripped gas;

(2) add hydrogen peroxide in the strong base solution obtained to step (1), then heat 10 ~ 20 minutes at 65 ~ 70 DEG C, cooling, constant volume, filter the solution after constant volume, obtain filtrate, the recycling chromatography of ions is analyzed filtrate.

In method of the present invention, described absorption process comprises the following steps:

(a) methanation unstripped gas is passed at least one of connecting successively be equipped with the Drexel bottle of strong base solution, at least one empty Drexel bottle and at least one the Drexel bottle of deionized water is housed;

B (), with empty Drexel bottle described in washed with de-ionized water, obtains cleaning fluid;

C the cleaning fluid obtained in the strong base solution obtained in step (a) and deionized water, step (b) joins in container such as beaker by (), sulfuretted hydrogen and muriatic strong base solution in the described methanation unstripped gas that has been absorbed.

Preferably, the Drexel bottle that strong base solution is housed described in is 2.

Preferably, described empty Drexel bottle is 1.

Preferably, the Drexel bottle that deionized water is housed described in is 1.

In method of the present invention, described strong base solution is sodium hydrate aqueous solution or potassium hydroxide aqueous solution.

In method of the present invention, described filtration comprises: draw the solution after constant volume, is first passed through 0.22 μm of millipore filter and filters, then filtered by C18 solid-phase extraction column (i.e. SPE post).

On the other hand, the present invention also provides a kind of system realizing above-mentioned absorption process, this system comprise at least one of connecting successively be equipped with the Drexel bottle of strong base solution, at least one empty Drexel bottle and at least one the Drexel bottle of deionized water is housed.

Preferably, the Drexel bottle that strong base solution is housed described in is 2.

Preferably, described empty Drexel bottle is 1.

Preferably, the Drexel bottle that deionized water is housed described in is 1.

In the systems described in the present invention, described strong base solution is sodium hydrate aqueous solution or potassium hydroxide aqueous solution.

Should be understood that, conventional method can be adopted to record the flow of methanation unstripped gas, such as, can adopt gas meter.Such as, but the present invention is not by the restriction of gas meter, and every gas meter that can measure methanation feed gas volume all can be used for the present invention, can adopt the LMF-2 wet test meter purchased from Beijing Jin Zhiye instrument and equipment Ltd.

Without being limited by theory, should be appreciated that 0.22 μm of millipore filter common in this area and C18 solid-phase extraction column all can be used for the present invention.Such as, 0.22 μm of millipore filter can be 0.22 μm of nylon pin type millipore filter, and C18 solid-phase extraction column can be On Guard II RPSPE post.

The present inventor finds, under highly basic existent condition, the chlorohydrocarbon in methanation unstripped gas can be hydrolyzed to alcohols and chlorion, and inorganic chlorine ion is also ionized, and adds hydrogen peroxide and sulphion can be oxidized to sulfate ion under basic conditions.In order to make sulphion be oxidized fully, reducing the impact of excessive hydrogen peroxide on sample blank, selecting under 65 ~ 70 DEG C of conditions, heat 10 ~ 20 minutes (such as 15min) left and right and making decomposing hydrogen dioxide solution.Filter molecule through 0.22 μm of millipore filter, chromatographic column can be avoided to block, then filter hydrophobic organic compound with C18 solid-phase extraction column, avoid organism to the infringement of chromatographic column.Sample after process directly can enter ion chromatography, its accuracy of analysis and precision higher.

Compared with prior art, the present invention at least has following beneficial effect: do not adopt mercuric thiocyanate etc. to produce to analysis the solvent disturbed, accuracy of analysis and precision high, instrumentation is convenient, automaticity is high, improve operator's work efficiency, and the working environment of operator is improved, significantly alleviate toxic action.

Accompanying drawing explanation

Below, describe embodiment of the present invention in detail by reference to the accompanying drawings, wherein:

Fig. 1 is the structural representation of absorption disposal system of the present invention.

description of reference numerals:

1 – needle valve, 2 – sodium hydroxide solution Drexel bottles, 3 – sodium hydroxide solution Drexel bottles, the empty Drexel bottle of 4 –, 5 – deionized water Drexel bottles, 6 – wet test meters, 7 – methanation unstripped gas outlets.

Embodiment

The present invention is further illustrated below by specific embodiment, but, should be understood to the use that these embodiments are only used for specifically describing more in detail, and should not be construed as limiting the present invention in any form.

As shown in Figure 1, absorption disposal system of the present invention comprise connect successively needle valve 1, sodium hydroxide solution Drexel bottle 2, sodium hydroxide solution Drexel bottle 3, empty Drexel bottle 4, deionized water Drexel bottle 5 and wet test meter 6.

When analyzing, first 2mL0.1mol/L sodium hydroxide solution is joined in sodium hydroxide solution Drexel bottle 2 and 3, then be diluted to 20mL with deionized water, then in deionized water Drexel bottle 5, add 20mL deionized water, read the initial number of degrees of wet test meter 6, be designated as M ₁, by sample line needle-valve, sample flow is controlled between 25 ~ 30L/h, prolongs in the Drexel bottle flow to subsequently to avoid sodium hydroxide solution.Passed into the methanation unstripped gas of about 100L by needle valve 1, carry out absorption process to it, the gas discharging of simultaneously methanation unstripped gas outlet 7 being discharged is to safety area.Stop ventilation, read the final number of degrees and the temperature of wet gas meter 6, be designated as M respectively ₂and T.

Then, deionized water in sodium hydroxide solution Drexel bottle 2 and 3 and deionized water Drexel bottle 5 is joined in the beaker of 400mL, joined in described beaker by cleaning fluid with the empty Drexel bottle 4 of a small amount of washed with de-ionized water, be absorbed the sodium hydroxide solution of sulphion and chlorion again.

Then, add hydrogen peroxide until the solution in beaker is become colorless by yellow muddiness, heat 15 minutes at 65 ~ 70 DEG C, constant volume 100mL after cooling.Draw the solution after 10mL constant volume with needle tubing, it is filtered through 0.22 μm of nylon pin type millipore filter and On Guard II RPSPE post successively.Finally, by the chromatography of ions, filtrate is analyzed.Concrete analytical procedure is:

Instrument and reagent

ICS-1100 type ion chromatograph (Sai Mo flies generation that science and technology (China) company limited), is furnished with DS6 conductance cell detecting device, ASRS300 rejector, RFC30 leacheate automatic generating apparatus and EGC III KOH tank.Cl-and SO ₄ ^2-standard solution (1000 μ g/mL, purchased from China National Measuring Science Research Inst.), ultrapure water conductivity is 17.82M Ω.0.22 μm of nylon pin type millipore filter, On Guard II RP SPE post.NaOH (GR level, 100g/ bottle, Ke Miou chemical reagent) is mixed with 0.01mol/L solution, hydrogen peroxide (GR level, 500ml/ bottle, Ke Miou chemical reagent).Wet test meter, Drexel bottle.

Chromatographic condition

Dionex IonPac AG11-HC(4mm × 50mm) negative ion guard column, Dionex IonPacAS11-HC(4mm × 250mm) anion separation column; Leacheate is the degree drip washing such as 30mmol/L KOH, and flow velocity is 1.0ml/min, and suppression electric current is 75mA; Column oven temperature is 30 DEG C, and conductance cell temperature is 30 DEG C.Quantitative loop is 200 μ L.

Experimental principle

Under NaOH existence condition, chlorohydrocarbon is hydrolyzed to alcohols and chlorion, and inorganic chlorine ion is also ionized.

NaOH+Cl ^-=NaCl+OH ^-；C _nH _mCl+NaOH=C _nH _mOH+NaCl

2NaOH+S ^2-=Na ₂S+2OH ^-；

Add subsequently hydrogen peroxide in the basic conditions sulfur oxide ion be sulfate ion.

2Na ₂s+H ₂o ₂=Na ₂s ₂+ 2NaOH (Na ₂s ₂for yellow):

Na ₂s ₂+ H ₂o ₂=2S+2NaOH (solution turned cloudy)

S+3H ₂o ₂+ 2NaOH=Na ₂sO ₄+ 4H ₂o (solution becomes colorless)

In order to make sulphion be oxidized fully, reducing the impact of excessive hydrogen peroxide on sample blank, under 65 ~ 70 DEG C of conditions, heating 15min make it to decompose.

2H ₂O ₂=2H ₂O+O ₂

Again through 0.22 _μm millipore filter filters molecule, avoids chromatographic column to block, then filters hydrophobic organic compound with C18 solid-phase extraction column, avoids organism to the infringement of chromatographic column.The sample handled well enters chromatography of ions Direct Analysis.

Standard model is analyzed

By Cl-1000 μ g/mL standard solution, SO ₄ ²-1000 μ g/mL standard solution 17.82M Ω high purity waters are diluted to hybrid standard liquid, 0.2 μ g/mL, 0.5 μ g/mL, 1 μ g/mL, 2 μ g/mL, 5 μ g/mL.Then add 0.01mol/L sodium hydroxide solution and hydrogen peroxide at mixed standard solution and blank, heat 15min, directly enter ion chromatography under 65 ~ 70 DEG C of conditions, experimental result can see table 1.

Table 1 chlorion and sulfate ion content analysis result

Calculate each ion detection limit according to being three times in baseline noise, chlorion detection limit concentration is 0.006mg/L, sulfate ion detection limit concentration is 0.009mg/L.

Result calculates

By gas sample amount (V ₀) be corrected to 0 DEG C and 101.325kPa(760mmHg) and time volume, and calculate trace sulfuretted hydrogen and total chloride in methanation unstripped gas according to following formula.

$V_0=\frac{(M_2-M_1)\×P_1\×273}{101.325\×(273+T)}$

Wherein: M ₂represent the final number of degrees of gasometer, L

M ₁represent gasometer initial reading, L

P ₁represent atmospheric pressure, kPa

T represents gasometer temperature, DEG C

Total chlorine, $\mathrm{vpm}=\frac{C_1\×V\×22.414}{1000\×V_0\×35.45}$

Sulfuretted hydrogen, $\mathrm{vpm}=\frac{C2\×V\×22.414}{1000\×V0\×34.076}$

Wherein: C ₁represent the concentration of the total chlorine in the solution after constant volume, mg/L

C ₂represent the concentration of the sulfuretted hydrogen in the solution after constant volume, mg/L

V represents the volume of the solution after constant volume, L

V ₀represent the volume by gas, L

Although present invention has been description to a certain degree, significantly, under the condition not departing from the spirit and scope of the present invention, can carry out the suitable change of each condition.Be appreciated that and the invention is not restricted to described embodiment, and be attributed to the scope of claim, it comprises the equivalent replacement of described each factor.

Claims (9)

1. utilize a method for trace sulfuretted hydrogen and total chloride in ion chromatography analysis methanation unstripped gas, the method comprises the following steps:

(1) carry out absorption process with strong base solution to methanation unstripped gas, be absorbed sulfuretted hydrogen in described methanation unstripped gas and muriatic strong base solution, and record the flow of described methanation unstripped gas;

(2) add hydrogen peroxide in the strong base solution obtained to step (1), then heat 10 ~ 20 minutes at 65 ~ 70 DEG C, cooling, constant volume, filter the solution after constant volume, obtain filtrate, the recycling chromatography of ions is analyzed filtrate.

2. method according to claim 1, is characterized in that, described absorption process comprises the following steps:

(a) methanation unstripped gas is passed at least one of connecting successively be equipped with the Drexel bottle of strong base solution, at least one empty Drexel bottle and at least one the Drexel bottle of deionized water is housed;

B (), with the empty Drexel bottle in step (a) described in washed with de-ionized water, obtains cleaning fluid;

C the cleaning fluid obtained in the strong base solution obtained in step (a) and deionized water, step (b) joins in container by (), be absorbed sulfuretted hydrogen in described methanation unstripped gas and muriatic strong base solution.

3. method according to claim 2, is characterized in that, described in strong base solution is housed Drexel bottle be 2.

4. method according to claim 2, is characterized in that, described empty Drexel bottle is 1.

5. method according to claim 2, is characterized in that, described in deionized water is housed Drexel bottle be 1.

6. method according to any one of claim 1 to 5, is characterized in that, described strong base solution is sodium hydrate aqueous solution or potassium hydroxide aqueous solution.

7. method according to any one of claim 1 to 6, is characterized in that, described filtration comprises: draw the solution after constant volume, first it filtered by 0.22 μm of millipore filter, then filtered by C18 solid-phase extraction column.

8. realize the system absorbing process according to any one of claim 1 to 7, this system comprise at least one of connecting successively be equipped with the Drexel bottle of strong base solution, at least one empty Drexel bottle and at least one the Drexel bottle of deionized water is housed.

9. system according to claim 8, is characterized in that, described in strong base solution is housed Drexel bottle be 2, preferably, described empty Drexel bottle is 1, more preferably, described in deionized water is housed Drexel bottle be 1.