CN1086599C - Method, apparatus and system for monitoring sulfur dioxide in desulfuration of flue gas by sea water - Google Patents

Abstract

The present invention relates to a monitoring method, a monitoring device and a monitoring system for sulfur dioxide (SO2) in the desulfuration of smoke gas by a seawater method in industrial equipment. The overflow rate or the conversion rate of the SO2 is used as a monitoring measuring standard to measure the total equivalent weight of sulfide in the system. The monitoring device comprises an instrument for converting the total equivalent weight of the sulfide in acidulous water and an instrument for converting the total equivalent weight of the sulfide in discharge water, and is connected with a signal processing system; thus, the overflow rate of the SO2 is calculated. A control device of the present invention comprises the signal processing system and an executive element which is used for controlling the quantity of the smoke gas directly exhausted into the atmosphere and the admitting quantity of the washing seawater. The monitoring system is formed by combining the monitoring device and the control device, and has a fully automatic monitoring function.

Description

Sulfur dioxide monitoring method and supervising device and system in the desulfuration of flue gas by sea water

The present invention relates to sulfur dioxide monitoring method and supervising device and system in the desulfuration of flue gas by sea water, belong to the environmental protection technical field of commercial plant flue gas desulfurization, be specially adapted to desulfuration of flue gas by sea water workplace, coastal thermal power plant and use.

The problem in the acid rain harm whole world be well-known, control the generation of acid rain, must restriction also the minimizing commercial plant to the SO2 emissions of atmosphere, this need for commercial plant particularly large scale industry device common configuration sulfur removal technology system could realize.Common sulfur removal technology system is flue gas desulfurization process system (a FGD system), and its function is for removing the sulfur dioxide in the commercial plant smoke evacuation.High in view of traditional FGD system cost and operating cost, industrially developed country also feels can't bear the heavy load, and developing country does not dare to inquire especially.For this reason and the exploitation full sea water method flue gas desulfurization (the calling SEFGD in the following text) process that is applicable to the coastal industry device and the device applied for a patent in China, this process system can also reduce cost and operating cost significantly when having very high desulfuration efficiency.

The FGD system belongs to typical environmental project system, and it is the interface system between commercial plant process system and the big system of environment, and the interactive relation between process system, environmental system is very complicated.The SEFGD process system is especially true, its design, construction and even a series of INTERACTION PROBLEMS that must occur in service, and the problem that is occurred then certainly will cause a series of new environmental problems if can not solve properly.Wherein, control SO in the flue gas desulfurization operation ₂Effusion rate or SO ₂Conversion ratio is the problem that needs solution.And both at home and abroad some aspect with the COD value of final discharge water as SO ₂The formulation of the characterization value of conversion ratio is incorrect.

Desulfuration of flue gas by sea water is that temporary stable state material sulphite will be arranged in the SEFGD operation, particularly there is sulfurous acid to generate, and the latter is one of main distinction of SEFGD technology and other FGD technology, for when making sulfurous acid and salt thereof be oxidized into stable, harmless sulfate, also exist because of back reaction effusion gaseous state SO ₂Possibility.This will mean the SO of script to high altitude discharge ₂But transfer to ground release, the degree of its contamination hazard is even more serious.Because SO ₂Escaped quantity will depend on the reasonability of process system and choosing of technological parameter, therefore in definite process system and technological parameter, never allow it is not added restriction.

The objective of the invention is to determine SO ₂Effusion rate or SO ₂The conversion ratio index is also determined monitoring method to this index, and a kind of monitoring device and SO are provided simultaneously ₂The comprehensive monitoring system of the control device of escaped quantity or automation obtains more reliable, more perfect practicing so that realize the flue gas desulfurization with seawater process.

The technical scheme of the sulfur dioxide monitoring method in a kind of desulfuration of flue gas by sea water that the present invention relates to is: with SO ₂Effusion rate or its inverse, be SO ₂Conversion ratio is the monitoring and metering standard, and this effusion rate is that loss enters the SO of gas phase in each operation of desulphurization system ₂SO with wash-out from flue gas ₂The ratio of the equivalent of total amount; Its assay method is at the acid water that a certain amount of washing of acid water discharge side-draw of flue gas washing system is discharged, at a certain amount of discharge water of quality recovery system discharge side-draw, to measure sulfide total yield separately then respectively; The amount of the acid water of getting and discharge water, determine according to the working index of quantitative detecting instrument.

The described monitoring method of the invention described above, the sampling time point of discharge water, the sampling time point of hysteresis acid water, lag time length, flow velocity by water in the quality recovery system determines, so that the discharge water of the acid water same period behind quality recovery of the acid water that can obtain formerly to be got is as the monitoring sample of discharge water to be checked.In this monitoring method, SO ₂The monitoring time of effusion rate is determined by desulphurization system processing quality and stability under working conditions at interval, can be periodic monitor, or at-once monitor, or automatic continuous monitoring; SO ₂Effusion rate and ySO _{2 ease}Definite formula be:

Wherein, S _A: be the A of flue gas washing system (as desulfurizing tower) point, promptly acid water is discharged the total yield of side sulfide;

S _B: for the B of quality recovery system point, be the total yield of discharge water floss hole place sulfide;

SO ₂Conversion ratio ySO _{2 change}Computing formula is:

The technical scheme of the sulfur dioxide monitoring device in a kind of desulfuration of flue gas by sea water of the present invention is: this device comprises the sulfide conversion instrument that the total yield of the sulfide of the discharge water that sulfide conversion instrument that the total yield of the sulfide of the acid water that the flue gas washing system is discharged is monitored and quality recovery system discharge is monitored; The signal processing system of the output of two instrument and mensuration, calculating SO2 effusion rate links; Its sulfide conversion instrument is for measuring the chemical analysis instrument of sulfide.

A kind of technical scheme that relates to the sulfur dioxide control device in the desulfuration of flue gas by sea water of the present invention is: it comprises signal processing system and carries out the executive component of control task, and this executive component can be controlled the flue gas that burner discharges and directly enter chimney through blower fan; Or/and control enters the seawater inlet that being used in the flue gas washing system wash flue gas; Described executive component adopts the electrodynamic pump of automatically controlled or magnetic control, or valve, or electrical header.

Sulfur dioxide monitoring system in the desulfuration of flue gas by sea water of the present invention, it is by SO ₂Effusion rate monitoring device and SO ₂Effusion rate control device is formed, and is connected by signal processing system between this stream oriented device, and this signal processing system comprises SO ₂The effusion rate is measured the instruction control section of calculating section and instruction executive component control desulphurization system duty.

To theoretical foundation of the present invention, principle is as follows with relevant parameter declaration:

1, the determined SO of the present invention ₂Effusion rate and SO ₂The definition of conversion ratio index:

SO ₂The effusion rate enters the SO of gas phase for loss in each operation of SEFGD system ₂SO with wash-out from flue gas ₂The ratio of the equivalent of total amount.

SO ₂Conversion ratio is SO ₂The inverse of effusion rate, the i.e. SO of wash-out from flue gas ₂The SO of final harmless sulfate radical that transforms and discharge and remaining inferior sulfate radical sum and wash-out from flue gas in process system ₂The ratio of the equivalent of total amount.Inferior sulfate radical concentration remaining in the draining will clearly limit according to related environmental standards COD value.

2, the control criterion of Cai Yonging

Because relevant process facility is provided with, adopt the control of atmosphere quality grade III Standard, i.e. SO in the open ₂Concentration one sub-value is 0.7mg/Nm ³, that is because SO ₂Groundlevel concentration one sub-value in the process facility zone that effusion causes is by 0.70mg/Nm ³Control.The sulfur content of fuel is considered by low content in general.

3, determine SO ₂The method of effusion rate index;

Adopt Gauss's plume pattern, the face source is buried at virtual point source method place, according to the anti-source strength that pushes away of process facility ground control concentration, and then draws SO ₂Effusion rate index.Regard process facility as the face source, the upwind virtual point source of source strengths such as usefulness substitutes, and the horizontal proliferation width of cloth is identical with process facility after XO is apart from diffusion, can determine the coordinate position of virtual point source like this, so can calculate down wind direction any point concentration.Computing formula is as follows; Gauss's plume diffusion formula: $C=\frac{\mathrm{<figure-callout\; id="2"\; label="Q"\; filenames="C9611962700111.png,C9611962700121.png"\; state="\{\{state\}\}">Q</figure-callout>}}{2\mathrm{\&pi;U}{\mathrm{\&sigma;}}_y{\mathrm{\&sigma;}}_z}\exp (-\frac{{\mathrm{<figure-callout\; id="2"\; label="y"\; filenames="C9611962700111.png,C9611962700121.png"\; state="\{\{state\}\}">y</figure-callout>}}^2}{2{\mathrm{\&sigma;}}_y^2})\exp (-\frac{{\mathrm{<figure-callout\; id="2"\; label="H\; e"\; filenames="C9611962700111.png,C9611962700121.png"\; state="\{\{state\}\}">H</figure-callout>}}_e^{}}{2{\mathrm{\&sigma;}}_z^2})---\left(1\right)$ Q in the formula---SO ₂Effusion rate amount, mg/s;

C---SO ₂Groundlevel concentration, mg/Nm ³

U---mean wind speed, m/s;

σ _y---horizontal proliferation parameter, m;

σ _z---vertical proliferation parameter, m;

Y---lateral separation, m;

He---effective source height, m;

Only consider ground axis concentration, ignore anti-liter, then lateral separation and effective source height are zero.Computing formula can be reduced to: $C=\frac{\mathrm{<figure-callout\; id="2"\; label="Q"\; filenames="C9611962700111.png,C9611962700121.png"\; state="\{\{state\}\}">Q</figure-callout>}}{2\mathrm{\&pi;U}{\mathrm{\&sigma;}}_y{\mathrm{\&sigma;}}_z}---\left(2\right)$

Diffusion parameter is chosen by international GB/T13201-91.

Calculate for convenient, relevant process facility is pressed with the area square handle, as be made as 39.2 * 39.2m ²So horizontal proliferation width of cloth L=39.2m of virtual point source.Can try to achieve σ thus _y, σ _z, XO, so Q=C * 2 π σ _yσ _z(3) SO of process facility place that calculates in view of the above ₂Concentration is normal distribution, and above-mentioned axis concentration place is maximum in theory, and in fact should be accurate evenly distribution, is mean value, promptly should the SO of place ₂Actual concentrations can be greater than calculating concentration, and the effusion rate when reaching control criterion is greater than the effusion rate of calculating thus.Normal distribution plume width L=4.3 σ _y, that is the process facility width.Level item maximum is 1 in the formula (1), and mean value is $\frac{1}{L}\underset{-\&infin;}{\overset{+\&infin;}{\&Integral;}}\exp (-\frac{{\mathrm{<figure-callout\; id="2"\; label="y"\; filenames="C9611962700111.png,C9611962700121.png"\; state="\{\{state\}\}">y</figure-callout>}}^2}{2{\mathrm{\&sigma;}}_y^2})\mathrm{dy}=\frac{2}{L}\underset{0}{\overset{\&infin;}{\&Integral;}}\exp (-\frac{{\mathrm{<figure-callout\; id="2"\; label="y"\; filenames="C9611962700111.png,C9611962700121.png"\; state="\{\{state\}\}">y</figure-callout>}}^2}{2{\mathrm{\&sigma;}}_y^2})\mathrm{dy}=\frac{\sqrt{2\mathrm{\&pi;}}{\mathrm{\&sigma;}}_Y}{L}=0.58---\left(4\right)$

Be actual SO ₂Control effusion rate can be

Qs＝Q/0.58 (5)

According to above-mentioned processing, calculate process system SO respectively by atmospheric stability D and B ₂Effusion rate index, and then definite SO ₂The minimum guarantee value of conversion ratio is (with SO ₂Meter).System's desulfuration efficiency is by 90%, and result of calculation is as follows:

Atmospheric stability	D	B
			Q s	6.19kg/h	5.82kg/h
Conversion ratio	99.48％	99.51％

By aforementioned calculation and analysis, consider " Design of Industrial Enterprises sanitary standard " (TJ36-79) middle SO ₂Limit value is 15mg/Nm ³, the seawater desulfurizing process system is guaranteeing SO ₂Effusion rate index is not more than 0.5% (with SO ₂Count), or SO ₂Conversion ratio be not less than the SO of relevant process facility and peripheral region thereof at 99.5% o'clock ₂Groundlevel concentration one sub-value can be controlled in atmosphere quality grade III Standard limit value 0.7mg/Nm ³In, this all is an acceptable for plant area and factory's external environment.

Therefore, should be with 0.5% SO ₂Effusion rate index and 99.5% SO ₂The conversion ratio index is chosen as the SEFGD process system and the control index of process parameters design.

Above-mentioned numerical value calculates that only according to the embodiment that generally requires to be done, this class parameter determining at last in a certain concrete environmental project should propose according to relevant requirements and some specific factor according to the administrative department of local environment protection.

In conjunction with the accompanying drawings and embodiments, the structure to method of the present invention, Apparatus and system is described further as follows:

Fig. 1, SO ₂Effusion rate monitoring device schematic diagram.

Fig. 2, SO ₂Effusion rate control device schematic diagram.

Fig. 3, SO ₂Effusion rate monitoring system schematic diagram.

Among the figure, each label respective name is: 1, and acid water water sampling point A; 2, washing system acid water is discharged side; 3, flue gas inlet port; 4, flue gas washing system; 5, purify flue gas; 6, washing seawater inlet port; 7, acid water; 8, quality recovery system; 9, discharge side; 10, discharge water; 11, discharge water sample point B; 12.1,12.2,12.3, signal processing system; 13,14, sulfide conversion instrument; 15,16, executive component.

Fig. 1 is a kind of SO ₂Effusion rate automated watch-keeping facility schematic diagram.Discharge sample point A (1) sampling of side (2) from the flue gas washing system, as the acid water of scrubbing tower (4), through sulfide conversion instrument (13) analysis and with relevant data input signal treatment system (121), in the time that lags behind, from sample point B (11) sampling of the discharge side (9) of quality recovery system (8), analyze and with relevant data input signal treatment system (121) through sulfide conversion instrument (14).Draw SO after A point data and the treated COMPREHENSIVE CALCULATING of B point data ₂The effusion rate, then,, adjust SO by artificial, control device or automatic control system ₂The effusion rate.Till meeting standard.

Fig. 2 is a kind of SO ₂Effusion rate automaton schematic diagram.With the SO that monitors ₂In the effusion rate input signal treatment system (122), the adjustment scheme by setting provides fill order by signal processing system.If the fault of desulphurization system, perhaps other reasons causes SO ₂The effusion rate then can start executive component (15) well beyond standard, makes part or all of flue gas temporarily enter the high-altitude diffusion by chimney, avoids low latitude SO ₂Exceed standard.Work as SO ₂The effusion rate can start the seawater that executive component (16) strengthens or minimizing enters with seawater inlet port (6) from washing, so that measuring sub-standard SO in adjustable range ₂During the effusion rate, can make whole desulphurization system SO ₂The effusion rate meets the permission standard

Fig. 3 is a kind of SO that has simultaneously ₂The monitoring system of monitoring automatics and control device.Two kinds of automatic structures illustrated in figures 1 and 2 are arranged in this system.Mainly be characterised in that, make signal processing system (121) and (122) be merged into (123).Make whole SO like this ₂The monitoring of effusion rate and control become full-automatic form.

The invention has the advantages that; 1, at the SO that proposes simultaneously with the present invention₂The present invention who does on the effusion rate index basis comprises the method and apparatus invention, has solved SO in the seawer washing industrial smoke operation₂The effusion problem makes the sea water desulfuration method reliable and perfect, has application. 2, SO₂The mensuration of effusion rate and control have corrected existingly being used as SO with the COD value₂The incorrect practice of conversion ratio. 3, the inventive method is simple, stable equipment operation is reliable, small investment.

Claims (7)

1, the sulfur dioxide monitoring method in a kind of desulfuration of flue gas by sea water is characterized in that, with SO ₂Effusion rate or its inverse, be SO ₂Conversion ratio is the monitoring and metering standard, and this effusion rate is that loss enters the SO of gas phase in each operation of desulphurization system ₂SO with wash-out from flue gas ₂The ratio of the equivalent of total amount; Its assay method is at the acid water that a certain amount of washing of acid water discharge side-draw of flue gas washing system is discharged, at a certain amount of discharge water of quality recovery system discharge side-draw, to measure sulfide total yield separately then respectively; The amount of the acid water of getting and discharge water, determine according to the working index of quantitative detecting instrument.

2, monitoring method according to claim 1, it is characterized in that, the sampling time point of discharge water, the sampling time point of hysteresis acid water, lag time, length was determined by the flow velocity of water in the quality recovery system, so that the discharge water of the acid water same period behind quality recovery of the acid water that can obtain formerly to be got is as the monitoring sample of discharge water to be checked.

3, monitoring method according to claim 1 and 2 is characterized in that, SO ₂The monitoring time of effusion rate is determined by desulphurization system processing quality and stability under working conditions at interval, adopts periodic monitor or at-once monitor, or automatic continuous monitoring; SO ₂Effusion rate ySO _{2 ease}Definite formula be:

Wherein, S _AFor flue gas washing system A point is the total yield that acid water is discharged side sulfide; S _BFor the B of quality recovery system point, promptly discharge the total yield of side sulfide; SO ₂Conversion ratio ySO _{2 change}Computing formula be:

4, the sulfur dioxide monitoring device in a kind of desulfuration of flue gas by sea water, it is characterized in that, it comprises the sulfide conversion instrument that the sulfide total yield of the discharge water that sulfide conversion instrument that the sulfide total yield of the acid water that the flue gas washing system is discharged is monitored and quality recovery system discharge is monitored; The output of two instrument and mensuration, calculating SO ₂The signal processing system of effusion rate links.

5, monitoring device according to claim 4 is characterized in that, described sulfide conversion instrument is for measuring the chemical analysis instrument of sulfide.

6, the sulfur dioxide control device in a kind of desulfuration of flue gas by sea water is characterized in that, it comprises signal processing system and finish the executive component of carrying out control task, and executive component can be controlled the flue gas that burner discharges and directly enter chimney through blower fan; Or/and control enters the seawater inlet that being used in the flue gas washing system wash flue gas; Described executive component adopts electrodynamic pump or the valve or the electrical header of automatically controlled or magnetic control.

7, the sulfur dioxide monitoring system in a kind of desulfuration of flue gas by sea water is characterized in that it is by SO ₂Effusion rate monitoring device and SO ₂Effusion rate control device is formed, and is connected by signal processing system between this stream oriented device, and this signal processing system comprises SO ₂The effusion rate is measured the instruction control section of calculating section and instruction executive component control desulphurization system duty.

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