CN101642675A - Method and system for controlling water spraying amount in semidry desulfurization process - Google Patents

Abstract

The invention relates to a method and a system for controlling the water spraying amount in a semidry desulfurization process. A traditional relative humidity or humidity probe is preserved, and meanwhile, a durable electrical conductivity probe is used for replacing the relative humidity probe on the top of a desulfurizing tower, and an additional relative humidity probe is arranged in each air chamber of a bag-type dust remover. The whole set of control system is integrally controlled by a PLC, and flue gas parameters and water spraying amount data of an inlet of the desulfurizing tower, thetop of the desulfurizing tower, an air-purifying chamber of the bag-type dust remover, an outlet of the bag-type dust remover and a water spraying subsystem, which are gathered by the PLC controlledsystem and collected by each class of sensor probes, are necessarily converted and calculated to acquire relative humidity and dew point temperature of each key point of the whole desulphurization system. By comparing two groups of measured values, a group of calculated values and a group of set values, the tower top temperature of the desulfurizing tower for controlling the water spraying amountis acquired through the logic control preset in the PLC controlled system, thereby controlling the opening of a loop water spraying valve and controlling the water spraying amount.

Description

The control method of injection flow rate and control system in the semi-dry desulfurizing process

Technical field

The present invention relates to the control method and the control system of injection flow rate in a kind of semi-dry desulfurizing process, particularly semi-dry desulphurization cooperates the control system and the method for injection flow rate in the sack cleaner desulphurizing and dust-removing integral technology, belongs to the semi-dry process flue gas desulphurization technical field.

Background technology

The semi-dry desulfurizing process device comprises: several parts such as circulating fluidized bed desulfurization tower, absorbent induction system, fresh water (FW) system, material recirculating system, dust pelletizing system and lime-ash treatment system are formed.Flue gas enters the desulfurizing tower main body through after the pre-dedusting, again with desulfurizing agent that enters desulfurizing tower respectively (being generally calcium hydroxide) and the abundant hybrid reaction of humidification water, remove the acid pollution gas in the flue gas, flue gas after being purified is discharged by the desulfurizing tower top, enter recirculating gas solid separator (being generally electric cleaner or sack cleaner), the separated loopback of most of solid particle goes in the tower to recycle, and flue gas enters atmosphere by chimney after deduster purifies.Usually in order to guarantee the desulfuration efficiency of semidry method system, at the desulfurizing agent that sprays into q.s simultaneously, suitable temperature, damp condition also was necessary when the assurance reaction was carried out.Original fresh water (FW) system all is by measuring the temperature and humidity of desulfurizing tower inlet or outlet flue gas, and calculates nearly adiabatic saturation temperature or dew-point temperature and control what of injection flow rate.But because the higher (600～1200g/Nm of desulfurizing tower exit dust concentration ³), often make a large amount of desulfurization ashes stick on the instrument probe, cause the smoke moisture deviation that records in the desulfurizing tower exit very big, thereby influence is calculated and control.

In recent years, along with the progressively strictness of Environmental Protection in China standard, the strictness of Atmospheric particulates discharge standard made increasing large-sized boiler be tending towards using the dust arrester installation of sack cleaner as its boiler back, replaced original electrostatic precipitator.Sack cleaner can reach strict environmental protection standard requirement preferably, but also exists certain deficiency.Because filtrate belongs to dry goods, the filtrate that is suitable for using behind power plant's dedusting or semi-dry desulphurization is PPS (Poly Phenylene Snlfide, polyphenylene sulfide) filtrate, but its tolerance for flue gas high humility and oxidizing atmosphere is relatively poor, surpass its suitable service condition, will seriously shorten its service life.After the PPS filtrate had been carried out certain surface treatment, it can steady in a long-term move under with interior or the condition of dew-point temperature more than 20 ℃ in flue gas relative humidity 30%.

Summary of the invention

The objective of the invention is defective that exists at the semi-dry desulfurizing process prior art and the trend that will further develop from now on, the present invention a kind of high reliability is proposed and the semi-dry desulfurizing process that is suitable for being used with sack cleaner in the control method and the control system of injection flow rate.

Technical scheme of the present invention:

The control method of injection flow rate in the semi-dry desulfurizing process of the present invention belongs to the part of whole semi-dry desulphurization system, and when desulphurization system started, the whole job step of injection flow rate control system was as follows:

When 1) desulphurization system started, flue gas entered in the desulfurizing tower via the desulfurizing tower gas approach, in the desulfurizing tower gas approach to the composition of flue gas, go into the tower flue gas volume flow Q _Fg, porch flue gas static pressure P ₁, entrance flue gas temperature T ₁Measure, and according to formula

$d_1=\frac{0.8039\×X_{H2O-1}}{{\mathrm{\ρ}}_{\mathrm{fg}\left(d\right)}\×(1-X_{H2O-1})}---\left(I\right)$

Calculate the water capacity d of the former flue gas in desulfurizing tower porch ₁, ρ wherein _{Fg (d)}Be desulfurizing tower porch mark attitude butt smoke density, X _H2O-1Be water vapour content in the desulfurizing tower inlet flue gas;

2) start before the (operating) water nozzle subsystem, manually set a cat head flue-gas temperature setting value T _SdSet desulfurizing tower water spray COEFFICIENT K simultaneously _WaterWith tower top temperature value setting value T _SdWith record go into the tower flue gas volume flow Q _Fg, the inlet flue gas density p _Fg, entrance flue gas temperature T ₁And the water temperature T in the water tank _Water, according to formula

$G_{\mathrm{sw}}=K_{\mathrm{water}}\×\frac{{\mathrm{\ρ}}_{\mathrm{fg}\left(w\right)}\×Q_{\mathrm{fg}}\×C_{p,\mathrm{fg}}\×(T_1-T_{\mathrm{sd}})}{{\mathrm{\Δ}}_{\mathrm{vap}}{H}_{\mathrm{water}}+C_{p,H2O}\×(T_{\mathrm{sd}}-T_{\mathrm{water}})}---\left(\mathrm{II}\right)$

Calculate water spray value G _Sw, ρ wherein _{Fg (w)}Be desulfurizing tower porch mark attitude wet basis smoke density, C _{P, fg}Be the enthalpy of desulfurizing tower porch flue gas, C _{P, H2O}The enthalpy of corresponding temperature water, Δ _VapH _WaterEnthalpy of phase change for corresponding temperature water;

3) by actual injection flow rate G _Sw' with the former humidity of flue gas d that calculates ₁, according to formula

${\mathrm{<figure-callout\; id="2"\; label="d"\; filenames="A2009100636450022H1.png,A2009100636450024H1.png"\; state="\{\{state\}\}">d</figure-callout>}}_2=\frac{m_{v1}+{G_{\mathrm{sw}}}^{\&prime;}}{m_{a1}}---\left(\mathrm{III}\right)$

Calculate cat head humidity of flue gas d ₂, m wherein _V1Be desulfurizing tower porch steam quality, m _A1Be desulfurizing tower porch dry flue gas quality;

4) water that sprays into desulfurizing tower in tower after atomizing with tower in flue gas and the abundant hybrid reaction of material, to the desulfurizing tower cat head; Record the flue-gas temperature T of desulfurizing tower cat head ₂, cat head flue gas static pressure P ₂With cat head humidity of flue gas d ₂, according to formula

${\mathrm{<figure-callout\; id="2"\; label="RH"\; filenames="A2009100636450022H1.png,A2009100636450024H1.png"\; state="\{\{state\}\}">RH</figure-callout>}}_2=\frac{d_2}{\frac{M_{v2}}{M_{a2}}+{\mathrm{<figure-callout\; id="2"\; label="d"\; filenames="A2009100636450022H1.png,A2009100636450024H1.png"\; state="\{\{state\}\}">d</figure-callout>}}_2}\&times;\frac{P_2}{{\mathrm{<figure-callout\; id="2"\; label="P\; S"\; filenames="A2009100636450022H1.png,A2009100636450024H1.png"\; state="\{\{state\}\}">P</figure-callout>}}_S}\&times;100\%,({\mathrm{<figure-callout\; id="2"\; label="P\; s"\; filenames="A2009100636450022H1.png,A2009100636450024H1.png"\; state="\{\{state\}\}">P</figure-callout>}}_s<P_2)---(\mathrm{IV}-a)$

Or ${\mathrm{<figure-callout\; id="2"\; label="RH"\; filenames="A2009100636450022H1.png,A2009100636450024H1.png"\; state="\{\{state\}\}">RH</figure-callout>}}_2=\frac{d_2}{\frac{M_{v2}}{M_{a2}}+{\mathrm{<figure-callout\; id="2"\; label="d"\; filenames="A2009100636450022H1.png,A2009100636450024H1.png"\; state="\{\{state\}\}">d</figure-callout>}}_2}\&times;100\%,({\mathrm{<figure-callout\; id="2"\; label="P\; s"\; filenames="A2009100636450022H1.png,A2009100636450024H1.png"\; state="\{\{state\}\}">P</figure-callout>}}_s>P_2)---(\mathrm{IV}-b)$

Calculate relative humidity RH ₂M wherein _V2Be desulfurizing tower cat head place steam amount of substance, M _A2Be desulfurizing tower cat head place dry flue gas amount of substance;

Pass through formula again

${\mathrm{<figure-callout\; id="2"\; label="T\; dp"\; filenames="A2009100636450022H1.png,A2009100636450024H1.png"\; state="\{\{state\}\}">T</figure-callout>}}_{\mathrm{dp}}=\frac{243.12\&times;\ln (\frac{{\mathrm{<figure-callout\; id="2"\; label="RH"\; filenames="A2009100636450022H1.png,A2009100636450024H1.png"\; state="\{\{state\}\}">RH</figure-callout>}}_2}{100}+\frac{17.62\&times;{\mathrm{<figure-callout\; id="2"\; label="T"\; filenames="A2009100636450022H1.png,A2009100636450024H1.png"\; state="\{\{state\}\}">T</figure-callout>}}_2}{243.12+T_2})}{17.62-\ln (\frac{{\mathrm{<figure-callout\; id="2"\; label="RH"\; filenames="A2009100636450022H1.png,A2009100636450024H1.png"\; state="\{\{state\}\}">RH</figure-callout>}}_2}{100}+\frac{17.62\&times;{\mathrm{<figure-callout\; id="2"\; label="T"\; filenames="A2009100636450022H1.png,A2009100636450024H1.png"\; state="\{\{state\}\}">T</figure-callout>}}_2}{243.12+T_2})}---\left(V\right)$

Calculate the cat head flue gas and calculate dew point T _Dp2

5) the cat head flue gas electrical conductivity λ that records at the desulfurizing tower cat head ₂Value directly enters the PLC control system, by comparing with drawing good relative humidity-conductivity relation curve, obtains corresponding cat head flue gas relative humidity check value RH ₂'; Formula rule of thumb

${{\mathrm{<figure-callout\; id="2"\; label="T\; dp"\; filenames="A2009100636450022H1.png,A2009100636450024H1.png"\; state="\{\{state\}\}">T</figure-callout>}}_{\mathrm{dp}}}^{\&prime;}=\frac{243.12\&times;\ln (\frac{{{\mathrm{<figure-callout\; id="2"\; label="RH"\; filenames="A2009100636450022H1.png,A2009100636450024H1.png"\; state="\{\{state\}\}">RH</figure-callout>}}_2}^{\&prime;}}{100}+\frac{17.62\&times;{\mathrm{<figure-callout\; id="2"\; label="T"\; filenames="A2009100636450022H1.png,A2009100636450024H1.png"\; state="\{\{state\}\}">T</figure-callout>}}_2}{243.12+T_2})}{17.62-\ln (\frac{{{\mathrm{<figure-callout\; id="2"\; label="RH"\; filenames="A2009100636450022H1.png,A2009100636450024H1.png"\; state="\{\{state\}\}">RH</figure-callout>}}_2}^{\&prime;}}{100}+\frac{17.62\&times;{\mathrm{<figure-callout\; id="2"\; label="T"\; filenames="A2009100636450022H1.png,A2009100636450024H1.png"\; state="\{\{state\}\}">T</figure-callout>}}_2}{243.12+T_2})}---\left(\mathrm{VI}\right)$

Draw cat head flue gas dew point check value T _Dp2';

6) flue gas of desulfurizing tower outlet evenly enters each air chamber of sack cleaner behind water conservancy diversion, finishes the separation of gas, solid two-phase therein, and gas phase enters air-purifying chamber; Temperature and the relative humidity measured according to each chamber in the rearmounted sack cleaner, in the PLC control system to collected flue-gas temperature T ₃And relative humidity RH ₃Carry out mean value computation, again formula rule of thumb

$T_{\mathrm{dp}3}=\frac{243.12\&times;\ln (\frac{{\mathrm{RH}}_3}{100}+\frac{17.62\&times;T_3}{243.12+T_3})}{17.62-\ln (\frac{{\mathrm{RH}}_3}{100}+\frac{17.62\&times;T_3}{243.12+T_3})}---\left(\mathrm{VII}\right)$

Draw cloth bag air-purifying chamber flue gas dew point value T _Dp3

7) will calculate cat head flue gas dew point T _Dp2, cat head checks flue gas dew point T _Dp2' and cloth bag air-purifying chamber flue gas dew point T _Dp3, after three dew-point temperatures add 20 ℃ respectively with the artificial cat head flue-gas temperature T that sets _SdRelatively, get four maximums in the value as new cat head flue-gas temperature setting value T _SdBring formula (II) into, calculate injection flow rate G _SwBe used to control injection flow rate, so circulation.

The control system of injection flow rate in a kind of semi-dry desulfurizing process comprises DATA REASONING, data computation and controls three parts:

DATA REASONING partly comprises:

(1) desulfurizing tower gas approach exhaust gas components analyzer, desulfurizing tower inlet flue gas traffic analyzer, desulfurizing tower inlet static pressure transducer, desulfurizing tower inlet temperature sensor are installed in the desulfurizing tower gas approach before entering desulfurizing tower; The outputting measurement value of these sensors and analyzer reaches the PLC control system by data signal line respectively;

(2) between desulfurizing tower aditus laryngis section and straight length, install back the streaming (operating) water nozzle, water spray subsystem under it comprises water tank, water temperature sensor is installed in the water tank, and water tank is outer by pipeline the be linked in sequence water inlet of feed pump, (operating) water nozzle inlet flow rate meter, reverse-flow type (operating) water nozzle and water return outlet, (operating) water nozzle circling water flow rate meter, backwater solenoid valve; Water temperature sensor reaches the PLC control system with the water temperature that records by data signal line, and the injection flow rate data after handling through the PLC control system feed back to electromagnetism backwater control valve through data signal line again;

(3) at the desulfurizing tower cat head desulfurizing tower tower top temperature sensor, desulfurizing tower cat head flue gas conductivity meter, desulfurizing tower cat head static pressure transducer are installed; The outputting measurement value of these sensors and conductivity meter reaches the PLC control system by data signal line respectively;

(4) mounting temperature sensor and relative humidity sensor in each cell of the deduster air-purifying chamber of sack cleaner; Outlet temperature sensor, outlet static pressure transducer, outlet exhaust gas components analyzer are installed on the exhaust pass behind the sack cleaner; Each probe all connects corresponding tester by holding wire, shows on the spot and data signal is sent to the PLC control system by data signal line.

Data computation is by the PLC control system data to be calculated; Comprise: the former humidity of flue gas d in the PLC control system ₁Computing unit, desulfurizing tower injection flow rate G _SwComputing unit, cat head humidity of flue gas d ₂Computing unit, cat head flue gas relative humidity RH ₂Computing unit, cat head flue gas dew point T _Dp2Computing unit, check cat head flue gas dew point T _Dp2' computing unit, cloth bag air-purifying chamber flue gas dew point T _Dp3Computing unit; Former humidity of flue gas d ₁Computing unit is used to calculate the water capacity d of the former flue gas in desulfurizing tower porch ₁Desulfurizing tower injection flow rate G _SwComputing unit is used for calculating water spray value G _SwCat head humidity of flue gas d ₂Computing unit is used to calculate cat head humidity of flue gas d ₂Cat head flue gas relative humidity RH ₂Computing unit is used to calculate cat head flue gas relative humidity RH ₂Cat head flue gas dew point T _Dp2Computing unit is used to calculate cat head flue gas dew point T _Dp2Check cat head flue gas dew point T _Dp2' computing unit is cat head flue gas electrical conductivity λ ₂Value compares with drawing good relative humidity-conductivity relation curve, to cat head flue gas dew point T _Dp2Check; Cloth bag air-purifying chamber flue gas dew point T _Dp3Computing unit is used to calculate cloth bag air-purifying chamber flue gas dew point T _Dp3

Control section comprises: the actual parameter that partly obtains according to part of detecting and data computation enters logic default in the PLC and controls; Main control module is a selectivity module and an adjustment module; The selectivity module places cat head to set flue-gas temperature T _SdIn the unit, the effect of selectivity module is when setting the cat head flue-gas temperature, will calculate cat head flue gas dew point T _Dp2, check cat head flue gas dew point T _Dp2', cloth bag air-purifying chamber flue gas dew point T _Dp3Respectively add a definite value, compare with artificial setting cat head flue-gas temperature, the maximum input of gained is as new cat head flue-gas temperature setting value T _SdTo desulfurizing tower injection flow rate G _SwComputing unit calculates desulfurizing tower injection flow rate G _Sw, with the G that calculates _SwControl desulfurizing tower injection flow rate; The effect of adjustment module is according to the desulfurizing tower injection flow rate that calculates backwater magnetic valve aperture to be regulated.

The control system of injection flow rate in the described semi-dry desulfurizing process, after the normal operation, the flue gas relative humidity in the sack cleaner is 25%～35%, and flue-gas temperature is higher than 15～25 ℃ of flue gas dew point temperature.

The control system of injection flow rate in the described semi-dry desulfurizing process is checked cat head flue gas dew point T _Dp2' computing unit is to draw under the simulated flue gas environment at relative humidity-conductivity relation curve, and via an experience curve of a plurality of engineering practices checks, be resulting by the relation of flue gas relative humidity and flue gas electrical conductivity.

The control system of injection flow rate in the described semi-dry desulfurizing process, control section are with calculating cat head flue gas dew point T _Dp2, check cat head flue gas dew point T _Dp2', cloth bag air-purifying chamber flue gas dew point T _Dp3Respectively add 20 ℃, with cat head flue-gas temperature setting value T _SdRelatively, the input of the maximum of gained is as new cat head flue-gas temperature setting value degree T _Sd, deliver to desulfurizing tower injection flow rate G _SwComputing unit calculates desulfurizing tower injection flow rate G _Sw

The control system of injection flow rate in the described semi-dry desulfurizing process, the score of (operating) water nozzle inlet flow rate meter and (operating) water nozzle circling water flow rate does not record actual (operating) water nozzle inlet flow rate value and actual (operating) water nozzle circling water flow rate value, the actual injection flow rate G of desulfurizing tower that calculates according to (operating) water nozzle inlet flow rate value and (operating) water nozzle circling water flow rate value _Sw', and with the desulfurizing tower injection flow rate G that calculates _SwRelatively, make the actual injection flow rate G of desulfurizing tower _Sw' near the desulfurizing tower injection flow rate G that calculates _Sw, backwater magnetic valve aperture is regulated by the adjustment module of control section; The adjustment module of control section is according to the desulfurizing tower injection flow rate G that calculates _SwAnd between limber up period, draw good back-water valve (BWV) aperture-injection flow rate relation curve and compare, draw the back-water valve (BWV) aperture of coupling, make the actual injection flow rate G of desulfurizing tower _Sw' near the desulfurizing tower injection flow rate G that calculates _Sw

Above-mentioned each sensor groups all is provided with 3～5 sensor probes according to the size of flue or equipment, and each probe all connects corresponding tester by holding wire, shows on the spot and data signal is sent to the PLC control system.After the PLC system receives signal from each sensor, signal value of averaging of every group of sensor calculated or three select two again after the average computation, compare with exhaust gas components, choosing suitable data calculates according to the principle that has set in the PLC, then by behind the flue gas dew point and relative humidity that calculate gained, compare with flue gas dew point value and the rh value set, again after comparing with the spray flow valve opening, obtain spray flow valve opening variation tendency, realize the control of injection flow rate by the switching of control magnetic valve.

In addition, at the desulfurizing tower cat head conductivity sensor group is installed, reflect the situation of smoke moisture variation tendency in the tower by the variation tendency of measuring the flue gas electrical conductivity, and pass through test good electrical conductivity and relative humidity relation curve, in time the variation tendency of relative humidity in the reaction desulfuration tower.Humiture test in relative humidity that this conductivity meter records and the sack cleaner air-purifying chamber is organized resulting relative humidity numerical value and is compared, and injection flow rate is jointly controlled.

Advantage of the present invention:

1, the relative humidity of whole process is accurately measured, monitored the procedure parameter of whole process, especially adopt the measurement of relative humidity to control, can directly reach the key point of monitoring whole process and the effect of protecting filtrate for injection flow rate.That is to say, thereby by control relative humidity and flue gas dew point temperature control injection flow rate, and reach the effect of protecting filtrate.

2, introduce durable conductivity measurement probe and substitute the relative humidity probe that can't work under high concentration flue dust environment, the flue gas electrical conductivity that conductivity probe is recorded is converted into the relative humidity of corresponding flue gas via rational conversion.Solved can be under the environment of high concentrate dust high humility for the measurement of smoke moisture, thereby the true environment in the desulfurizing tower that made reflection that the data record are more practical, and reflect the process situation (mixability and the real chemical reaction condition that comprise gas-liquid-solid three-phase) of desulphurization reaction indirectly.

3, the present invention is provided with a cover humiture measurement mechanism in each air chamber of sack cleaner.Because air-flow distributes and working conditions change in the deduster, the flue gas environment in each air chamber of sack cleaner may not be identical, and this will accomplish global monitoring.Take the method given up for the bigger relative humidity measured value of deviation, and other measured value is got arithmetic mean of instantaneous value, calculates in the closed cell of substitution control logic again, thereby participate in control.A large amount of dust in the air-purifying chamber of sack cleaner because in the flue gas are through after filtering, the working environment of relative humidity probe is no longer harsh, so the relative humidity instrument can visual and accurately be measured desired data, this is the direct monitoring to the filtrate working environment on the one hand, the data that record for desulfurizing tower cat head conductivity probe are further calibrated on the other hand, thereby guarantee accurately meticulous on the The whole control.

4, in the selectivity module in the PLC control logic, " cat head setting flue-gas temperature " unit is one four and selects one input option, here will " manually set the cat head flue-gas temperature " via theory " calculating the cat head flue gas dew point " of calculating and " checking the cat head flue gas dew point " and " cloth bag air-purifying chamber flue gas dew point " that actual measurement obtains, four values comprehensively compare in addition.Used logic is selected to be generally to get maximum or choose mean value, logic is herein selected can carry out suitable modification according to the situation of on-the-spot practical operation situation and equipment instrument, and checks by the data that cat head conductivity probe and cloth bag pure qi (oxygen) indoor relative humidity probe record.

5, in " relative humidity-electrical conductivity check " unit, the relation curve of used relative humidity and electrical conductivity is to draw under the simulated flue gas environment, and an experience curve of checking via a plurality of engineering practices.This is resulting by the relation of humidity of flue gas and flue gas electrical conductivity, and the variation that utilizes the variation of electrical conductivity to push over relative humidity also is to carry out of actual innovation successfully to attempt under this kind condition.

6, in control system, introduce the injection flow rate COEFFICIENT K _WaterAdjusting, getting under the prerequisite of certain empirical parameter, by regulating K _WaterSize can conveniently accurately injection flow rate be regulated timely.

Description of drawings

Fig. 1 is a control system schematic diagram of the present invention.

Fig. 2 is control system control principle figure.

Fig. 3 is back-water valve (BWV) aperture-injection flow rate relation curve.

Fig. 4 is relative humidity-conductivity relation curve.

The specific embodiment

As Fig. 1: control system of the present invention comprises DATA REASONING, data computation and controls three parts;

DATA REASONING partly comprises:

(1) desulfurizing tower gas approach exhaust gas components analyzer 2, desulfurizing tower inlet flue gas traffic analyzer 3, desulfurizing tower inlet static pressure transducer 4, desulfurizing tower inlet temperature sensor 5 are installed in the desulfurizing tower gas approach 1 before entering desulfurizing tower 6; The outputting measurement value of these sensors and analyzer reaches PLC control system 26 by data signal line 25 respectively;

(2) between desulfurizing tower 6 aditus laryngis sections and straight length, install back streaming (operating) water nozzle 7, the (operating) water nozzle of evenly arranging (being generally 1～4) is installed on the same plane; Water spray subsystem under it comprises water tank 12, water temperature sensor 13 is installed in the water tank 12, and water tank is outer by pipeline the be linked in sequence water inlet of feed pump 9, (operating) water nozzle inlet flow rate meter 8, reverse-flow type (operating) water nozzle 7 and water return outlet, (operating) water nozzle circling water flow rate meter 10, backwater solenoid valve 11; At the desulfurizing tower cat head desulfurizing tower tower top temperature sensor, desulfurizing tower cat head flue gas conductivity meter, desulfurizing tower cat head static pressure transducer are installed;

Water temperature sensor 13 reaches PLC control system 26 with the water temperature that records by data signal line 25, and the injection flow rate data after handling through PLC control system 26 feed back to electromagnetism backwater control valve 11 through data signal line 25 again;

(3) at the desulfurizing tower cat head desulfurizing tower tower top temperature sensor 14, desulfurizing tower cat head flue gas conductivity meter 15, desulfurizing tower cat head static pressure transducer 16 are installed; The outputting measurement value of these sensors and conductivity meter reaches PLC control system 26 by data signal line 25 respectively;

(4) mounting temperature sensor 19 and relative humidity sensor 20 in each cell 18 of the deduster air-purifying chamber of sack cleaner 17; Outlet temperature sensor 22, outlet static pressure transducer 23, outlet exhaust gas components analyzer 24 are installed on the exhaust pass behind the sack cleaner 21; Above-mentioned each sensor groups all is provided with 3～5 sensor probes according to the size of flue or equipment, and each probe all connects corresponding tester by holding wire, shows on the spot and data signal is sent to PLC control system 26 by data signal line 25.

Clean flue gas in the sack cleaner air-purifying chamber 18 enters atmosphere by sack cleaner exhaust pass 19, in sack cleaner exhaust pass 19, be provided with temperature sensor 22, static pressure transducer 23, exhaust gas components analyzer 24, the main purpose of this group analysis instrument is to check the flue gas qualified discharge whether enter atmosphere, certainly, thereby the measuring instrument of front there is an auxiliary check effect by can confirm further also to the measurement of exhaust gas components and water capacity whether the relative humidity of flue gas is too high.

The PLC control system is calculated data.Comprise: the former humidity of flue gas d in the PLC control system ₁Computing unit, desulfurizing tower injection flow rate G _SwComputing unit, cat head humidity of flue gas d ₂Computing unit, cat head flue gas relative humidity RH ₂Computing unit, cat head flue gas dew point T _Dp2Computing unit, check cat head flue gas dew point T _Dp2' computing unit, cloth bag air-purifying chamber flue gas dew point T _Dp3Computing unit; Former humidity of flue gas d ₁Computing unit is used to calculate the water capacity d of the former flue gas in desulfurizing tower porch ₁Desulfurizing tower injection flow rate G _SwComputing unit is used for calculating water spray value G _SwCat head humidity of flue gas d ₂Computing unit is used to calculate cat head humidity of flue gas d ₂Cat head flue gas relative humidity RH ₂Computing unit is used to calculate cat head flue gas relative humidity RH ₂Cat head flue gas dew point T _Dp2Computing unit is used to calculate cat head flue gas dew point T _Dp2Check cat head flue gas dew point T _Dp2' computing unit is cat head flue gas electrical conductivity λ ₂Value compares with drawing good relative humidity-conductivity relation curve, to cat head flue gas dew point T _Dp2Check; Cloth bag air-purifying chamber flue gas dew point T _Dp3Computing unit is used to calculate cloth bag air-purifying chamber flue gas dew point T _Dp3

Control section comprises: the actual parameter that partly obtains according to part of detecting and data computation enters logic default in the PLC and controls; Main control module is a selectivity module and an adjustment module; The selectivity module places cat head to set flue-gas temperature T _SdIn the unit, the effect of selectivity module is when setting the cat head flue-gas temperature, will calculate cat head flue gas dew point T _Dp2, check cat head flue gas dew point T _Dp2', cloth bag air-purifying chamber flue gas dew point T _Dp3Respectively add a definite value, compare with artificial setting cat head flue-gas temperature, the maximum of gained is as new cat head flue-gas temperature setting value T _Sd, to desulfurizing tower injection flow rate G _SwComputing unit calculates desulfurizing tower injection flow rate G _Sw, with the G that calculates _SwControl desulfurizing tower injection flow rate; The effect of adjustment module is according to the desulfurizing tower injection flow rate that calculates backwater magnetic valve aperture to be regulated.

After the normal operation, the flue gas relative humidity in the sack cleaner is 25%～35%, and flue-gas temperature is higher than 15～25 ℃ of flue gas dew point temperature.

Check cat head flue gas dew point T _Dp2' computing unit is in that " relative humidity-conductivity relation curve is to draw under the simulated flue gas environment, and via an experience curve of a plurality of engineering practices check, is resulting by the relation of flue gas relative humidity and flue gas electrical conductivity.

Control section is with calculating cat head flue gas dew point T _Dp2, check cat head flue gas dew point T _Dp2', cloth bag air-purifying chamber flue gas dew point T _Dp3Respectively add 20 ℃, compare with cat head flue-gas temperature setting value; The maximum of gained is as new cat head flue-gas temperature setting value T _Sd

Adjustment module by control section is regulated backwater magnetic valve aperture; (operating) water nozzle inlet flow rate meter 8 and (operating) water nozzle circling water flow rate meter 10 record actual (operating) water nozzle inlet flow rate value and actual (operating) water nozzle circling water flow rate value respectively, the actual injection flow rate G of desulfurizing tower that calculates according to (operating) water nozzle inlet flow rate value and (operating) water nozzle circling water flow rate value _Sw', and with the desulfurizing tower injection flow rate G that calculates _SwRelatively, make the actual injection flow rate G of desulfurizing tower _Sw' near the desulfurizing tower injection flow rate G that calculates _Sw, backwater magnetic valve aperture is regulated by the adjustment module of control section; The adjustment module of control section is according to the desulfurizing tower injection flow rate G that calculates _SwAnd between limber up period, draw good back-water valve (BWV) aperture-injection flow rate relation curve and compare, draw the back-water valve (BWV) aperture of coupling, make the actual injection flow rate G of desulfurizing tower _Sw' near the desulfurizing tower injection flow rate G that calculates _Sw

Concrete PLC control principle as shown in Figure 2, mathematic calculation is described below:

(step 1) is for former humidity of flue gas d ₁Computing unit, according to the computing formula of water capacity:

$d=\frac{m_v}{m_a}=\frac{M_v\&times;n_v}{M_a\&times;n_a}=\frac{M_v\&times;P_{H2O}}{M_a\&times;(P_{\mathrm{fg}}-P_{H2O})}---\left(1\right)$

Wherein d is a humidity of flue gas, m _vBe steam quality in the flue gas, m _aBe dry flue gas quality in the flue gas, M _vBe steam amount of substance in the flue gas, M _aBe dry flue gas amount of substance in the flue gas, n _vBe steam molal quantity in the flue gas, n _aBe dry flue gas molal quantity in the flue gas, P _FgBe flue gas static pressure, P _H2OBe steam partial pressure in the flue gas.

In order to calculate former humidity of flue gas, the quality of directly calculating steam in the flue gas gets final product with the ratio of the quality of dry flue gas.

$m_{v1}=Q_{\mathrm{fg}}\&times;X_{H2O-1}\&times;\frac{18.0152}{22.41}---\left(2\right)$

m _a1＝Q _fg×(1-X _H2O-1)×ρ _fg(d) (3)

M wherein _V1Be desulfurizing tower porch steam quality, m _A1Be desulfurizing tower porch dry flue gas quality, X _H2O-1Be water vapour content in the desulfurizing tower inlet flue gas, ρ _{Fg (d)}Be desulfurizing tower porch mark attitude butt smoke density, Q _FgBe desulfurizing tower porch flue gas volume flow.

So former humidity of flue gas is arranged:

$d_1=\frac{0.8039\&times;X_{H2O-1}}{{\mathrm{\&rho;}}_{\mathrm{fg}\left(d\right)}\&times;(1-X_{H2O-1})}---\left(I\right)$

Dry flue gas density p wherein _{Fg (d)}Can calculate by the result of coal analysis, or calculate according to the result of CEMS exhaust gas components analysis.

(step 2) is for desulfurizing tower injection flow rate G _SwComputing unit, injection flow rate is generally calculated by controlled condition in the desulfurizing tower, not taking into account system leak out and ash under the situation of water content, energy transmission and liquid-gas phase transition between desulphurization reaction and gas-liquid only take place in desulfurizing tower, also introduce the simple formula that corresponding water spray coefficient has following calculating injection flow rate according to energy balance:

$G_{\mathrm{sw}}=K_{\mathrm{water}}\&times;\frac{{\mathrm{\&rho;}}_{\mathrm{fg}\left(w\right)}\&times;Q_{\mathrm{fg}}\&times;C_{p,\mathrm{fg}}\&times;(T_1-T_{\mathrm{sd}})}{{\mathrm{\&Delta;}}_{\mathrm{vap}}{H}_{\mathrm{water}}+C_{p,H2O}\&times;(T_{\mathrm{sd}}-T_{\mathrm{water}})}---\left(\mathrm{II}\right)$

G wherein _SwBe desulfurizing tower injection flow rate, K _WaterBe water spray coefficient, ρ _{Fg (w)}Be mark attitude wet basis smoke density, C _{P, fg}Be desulfurizing tower inlet flue gas enthalpy, C _{P, H2O}For spraying into the enthalpy of water, Δ _VapH _WaterBe the enthalpy of phase change of water under the corresponding temperature, T ₁Be desulfurizing tower entrance flue gas temperature, T _WaterFor spraying into the temperature of water, Tsd is cat head flue-gas temperature setting value, T when initial _SdBe the cat head flue-gas temperature value of setting.

For the ease of the correction of fine setting and some coefficient, before calculating injection flow rate, add the water spray COEFFICIENT K _Water, set general K according to practical operation situation _WaterSetting value be 1 ± 0.20.

(this cover of step 3) process using reverse-flow type (operating) water nozzle, promptly be by adjust circling water flow rate control injection flow rate what.So backwater magnetic valve aperture adjustment unit is adjusted the aperture of nozzle backwater valve, the circling water flow rate that different apertures is corresponding different according to calculating injection flow rate.The backwater valve performance curve that provides according to equipment producer, when equipment debugging, draw back-water valve (BWV) aperture---injection flow rate curve again, regulate according to operation curve and actual motion trend when actual motion, described back-water valve (BWV) aperture---the injection flow rate curve as shown in Figure 3.In the actual moving process, the difference of water spray subsystem flow of inlet water and circling water flow rate is the actual injection flow rate G of desulfurizing tower of gained _Sw'.

(step 4) semi-dry desulphurization process can be understood as the work of water sprinkling for better material moisture process of the thermal insulation of carrying out in desulfurizing tower, flue gas has carried out sufficient hybrid reaction during to cat head, do not consider that desulfurizing tower air leak rate of air curtain and desulfurization ash absorb water this moment, then the water capacity in the flue gas is former humidity of flue gas and the water capacity sum that sprays into after the aqueous vaporization, then has:

m _v2＝m _v1+G _sw′ (4)

m _a2＝m _a1 (5)

M wherein _V2Be desulfurizing tower exit steam quality, m _A2Be desulfurizing tower exit dry flue gas quality, so cat head humidity of flue gas d ₂Calculating formula is:

${\mathrm{<figure-callout\; id="2"\; label="d"\; filenames="A2009100636450022H1.png,A2009100636450024H1.png"\; state="\{\{state\}\}">d</figure-callout>}}_2=\frac{m_{v2}}{m_{a2}}=\frac{m_{v1}+{G_{\mathrm{sw}}}^{\&prime;}}{m_{a1}}---\left(\mathrm{III}\right)$

(step 5) is for cat head flue gas relative humidity RH ₂Computing unit has according to relative humidity definition and water capacity definition:

$\mathrm{PH}\%=\frac{P_{H2O}}{P_S}\&times;100\%,(P_s<P_{\mathrm{fg}})---(6-a)$

$\mathrm{RH}\%=\frac{P_{H2O}}{P_{\mathrm{fg}}}\&times;100\%,(P_s>P_{\mathrm{fg}})---(6-b)$

Wherein RH is a relative humidity, P _sBe the adiabatic saturated vapor pressure of steam.According to empirical equation contained in the document, corresponding cat head flue-gas temperature is T ₂The time cat head flue gas saturated vapor pressure P _S2Have:

${\mathrm{<figure-callout\; id="2"\; label="P\; S"\; filenames="A2009100636450022H1.png,A2009100636450024H1.png"\; state="\{\{state\}\}">P</figure-callout>}}_S=\frac{400}{3}\&times;\exp (18.5916-\frac{399.11}{{\mathrm{<figure-callout\; id="2"\; label="T"\; filenames="A2009100636450022H1.png,A2009100636450024H1.png"\; state="\{\{state\}\}">T</figure-callout>}}_2+233.84})---\left(7\right)$

And steam partial pressure can be derived P by formula (1) _H2OCan get:

$P_{H2O}=\frac{M_a\&times;d}{M_v+M_a\&times;d}\&times;P_{\mathrm{fg}}---\left(8\right)$

Formula (8) substitution formula (6) can be obtained corresponding cat head flue gas relative humidity RH ₂:

${\mathrm{<figure-callout\; id="2"\; label="PH"\; filenames="A2009100636450022H1.png,A2009100636450024H1.png"\; state="\{\{state\}\}">PH</figure-callout>}}_2=\frac{d_2}{\frac{M_{v2}}{M_{a2}}+{\mathrm{<figure-callout\; id="2"\; label="d"\; filenames="A2009100636450022H1.png,A2009100636450024H1.png"\; state="\{\{state\}\}">d</figure-callout>}}_2}\&times;\frac{P_2}{{\mathrm{<figure-callout\; id="2"\; label="P\; S"\; filenames="A2009100636450022H1.png,A2009100636450024H1.png"\; state="\{\{state\}\}">P</figure-callout>}}_S}\&times;100\%,(P_{s2}<P_2)---(\mathrm{IV}-a)$

Or ${\mathrm{<figure-callout\; id="2"\; label="PH"\; filenames="A2009100636450022H1.png,A2009100636450024H1.png"\; state="\{\{state\}\}">PH</figure-callout>}}_2=\frac{d_2}{\frac{M_{v2}}{M_{a2}}+{\mathrm{<figure-callout\; id="2"\; label="d"\; filenames="A2009100636450022H1.png,A2009100636450024H1.png"\; state="\{\{state\}\}">d</figure-callout>}}_2}\&times;100\%,(P_{s2}>P_2)---(\mathrm{IV}-b)$

M wherein _V2Be steam amount of substance in the cat head flue gas, M _A2Be dry flue gas amount of substance in the cat head flue gas, P ₂Be cat head flue gas static pressure.

Equally, for cat head flue gas dew point T _Dp2Computing unit has according to the empirical equation in the document:

${\mathrm{<figure-callout\; id="2"\; label="T\; dp"\; filenames="A2009100636450022H1.png,A2009100636450024H1.png"\; state="\{\{state\}\}">T</figure-callout>}}_{\mathrm{dp}}=\frac{243.12\&times;\ln (\frac{{\mathrm{<figure-callout\; id="2"\; label="RH"\; filenames="A2009100636450022H1.png,A2009100636450024H1.png"\; state="\{\{state\}\}">RH</figure-callout>}}_2}{100}+\frac{17.62\&times;{\mathrm{<figure-callout\; id="2"\; label="T"\; filenames="A2009100636450022H1.png,A2009100636450024H1.png"\; state="\{\{state\}\}">T</figure-callout>}}_2}{243.12+T_2})}{17.62-\ln (\frac{{\mathrm{<figure-callout\; id="2"\; label="RH"\; filenames="A2009100636450022H1.png,A2009100636450024H1.png"\; state="\{\{state\}\}">RH</figure-callout>}}_2}{100}+\frac{17.62\&times;{\mathrm{<figure-callout\; id="2"\; label="T"\; filenames="A2009100636450022H1.png,A2009100636450024H1.png"\; state="\{\{state\}\}">T</figure-callout>}}_2}{243.12+T_2})}---\left(V\right)$

(step 6) is checked in the unit, with the flue gas electrical conductivity λ that measures by the cat head conductivity meter in relative humidity-electrical conductivity ₂" relative humidity-conductivity relation curve " (as Fig. 4) that substitution has been drawn obtains corresponding rh value, thereby obtains the actual relative humidity RH of cat head ₂', and draw by identical empirical equation and to check cat head flue gas dew point T _Dp2':

${{\mathrm{<figure-callout\; id="2"\; label="T\; dp"\; filenames="A2009100636450022H1.png,A2009100636450024H1.png"\; state="\{\{state\}\}">T</figure-callout>}}_{\mathrm{dp}}}^{\&prime;}=\frac{243.12\&times;\ln (\frac{{{\mathrm{<figure-callout\; id="2"\; label="RH"\; filenames="A2009100636450022H1.png,A2009100636450024H1.png"\; state="\{\{state\}\}">RH</figure-callout>}}_2}^{\&prime;}}{100}+\frac{17.62\&times;{\mathrm{<figure-callout\; id="2"\; label="T"\; filenames="A2009100636450022H1.png,A2009100636450024H1.png"\; state="\{\{state\}\}">T</figure-callout>}}_2}{243.12+T_2})}{17.62-\ln (\frac{{{\mathrm{<figure-callout\; id="2"\; label="RH"\; filenames="A2009100636450022H1.png,A2009100636450024H1.png"\; state="\{\{state\}\}">RH</figure-callout>}}_2}^{\&prime;}}{100}+\frac{17.62\&times;{\mathrm{<figure-callout\; id="2"\; label="T"\; filenames="A2009100636450022H1.png,A2009100636450024H1.png"\; state="\{\{state\}\}">T</figure-callout>}}_2}{243.12+T_2})}---\left(\mathrm{VI}\right)$

(step 7) cloth bag air-purifying chamber flue gas dew point T _Dp3The unit, the flue gas of desulfurizing tower outlet evenly enters each air chamber of sack cleaner behind water conservancy diversion, finish the separation of gas, solid two-phase therein, and gas phase enters air-purifying chamber; According to flue-gas temperature and the relative humidity that each chamber in the rearmounted sack cleaner is measured, in the PLC control system, collected flue-gas temperature and relative humidity are carried out mean value computation, obtain the temperature T of sack cleaner air-purifying chamber ₃And relative humidity RH ₃, by the air-purifying chamber mean temperature T that measures ₃With average relative humidity RH ₃Formula rule of thumb again

$T_{\mathrm{dp}3}=\frac{243.12\&times;\ln (\frac{{\mathrm{RH}}_3}{100}+\frac{17.62\&times;T_3}{243.12+T_3})}{17.62-\ln (\frac{{\mathrm{RH}}_3}{100}+\frac{17.62\&times;T_3}{243.12+T_3})}---\left(\mathrm{VII}\right)$

Can obtain the dew-point temperature of flue gas behind the bed of material after filtration.

(the step 8) cat head is set flue-gas temperature T _SdThe unit is comprehensively to compare according to the smoke moisture data that a plurality of measuring points obtain, and brings in constant renewal in cat head flue-gas temperature setting value T _SdIts input item has the cat head of calculating flue gas dew point T _Dp2, check cat head flue gas dew point T _Dp2', cloth bag air-purifying chamber flue gas dew point T _Dp3, current cat head flue-gas temperature setting value T _Sd, wherein first three items is respectively corresponding three and measures or the resulting flue gas dew point value of computing unit.Set flue-gas temperature T at cat head _SdIn the unit, in order to play the effect of protection filtrate, the design temperature of choosing usually is big more than 20 ℃ than sack cleaner air-purifying chamber flue gas dew point temperature or desulfurizing tower outlet flue gas dew point temperature.During actual motion, will work as first three dew point value that imports the unit and respectively add 20 ℃, and set value T with current cat head flue-gas temperature _SdRelatively, get four maximums in the value as new cat head flue-gas temperature setting value T _SdBring formula (II) into, calculate injection flow rate G _Sw, be used to control injection flow rate, so circulation.

The test of relative humidity mainly is to propose at the protection of filtrate, filtrate relative humidity below 30% or the flue gas dew point temperature can guarantee the security of operation of whole system more than 20 ℃.The maximum and the mean value of the flue gas relative humidity that is recorded by the sack cleaner air-purifying chamber have also been set a limiting value, and the usefulness as vigilant and alarm shows in the PLC system.For the assurance system obtains high desulfuration efficiency, still can introduce traditional nearly adiabatic saturation temperature Δ T control parameter, the control of subsidiary book method, in order to reference, the calculating of nearly adiabatic saturation temperature is not repeated.

Among Fig. 3, X-axis is backwater solenoid valve aperture in the water spray subsystem, and Y-axis is the actual flow of (operating) water nozzle.This curve is generally drawn when desulphurization system is debugged, in backwater magnetic valve aperture regulon, in X-axis corresponding among the injection flow rate substitution Fig. 3 that calculates, find the point in the Y-axis on the corresponding curve by this curve, the i.e. backwater magnetic valve aperture during flow for this reason of corresponding point value in the Y-axis.Draw good Fig. 3 and place the PLC control system, the adjustment module in PLC is regulated.

Among Fig. 4, X-axis is a desulfurizing tower cat head flue gas electrical conductivity, and Y-axis is for recording the flue gas relative humidity under the corresponding electrical conductivity according to test.This curve is to measure under the simulated condition, and the practice correction of a plurality of projects of process, has very high reliability, can the interior actual relative humidity situation of real reaction tower.After the cat head conductivity meter records the flue gas electrical conductivity, the X-axis corresponding points among substitution Fig. 4, and find point on the corresponding Y-axis by curve, the respective value in the Y-axis is the rh value in tower this moment.Draw good Fig. 4 as in the PLC control system, check the unit by relative humidity-electrical conductivity and carry out value.

The principle and the job step of enforcement of the present invention are as follows:

When (1) the semi-dry desulphurization system starts, flue gas enters in the desulfurizing tower via desulfurizing tower gas approach 1, the exhaust gas components analyzer 2 in desulfurizing tower gas approach 1, flue gas flow analyzer 3, static pressure transducer 4, temperature sensor 5 respectively to the composition of flue gas (comprising CO ₂, O ₂, N ₂, H ₂O, SO ₂, NO _xDeng), go into the tower flue gas volume flow Q _Fg, porch flue gas static pressure P ₁, entrance flue gas temperature T ₁Measure.

(2) the exhaust gas components data that obtain by exhaust gas components analyzer 2 are calculated smoke density ρ _Fg, import former humidity of flue gas d ₁The unit, and calculate the water capacity d of the former flue gas in desulfurizing tower 6 porch according to formula (I) ₁

(3) start before the (operating) water nozzle subsystem, set a higher tower top temperature (can be set to 80 ℃ when just starting according to the general semi-dry desulphurization of operating experience is advisable) in the cat head flue-gas temperature unit earlier artificial the setting; Set desulfurizing tower water spray COEFFICIENT K simultaneously _Water, general initial value is 1.00, looks practical operation situation and finely tunes.

(4) cat head is set flue-gas temperature T _SdThe unit obtains a cat head flue-gas temperature setting value T in view of the above _Sd, this value is introduced desulfurizing tower injection flow rate G _SwComputing unit, with record go into the tower flue gas volume flow Q _Fg, smoke density ρ _Fg, entrance flue gas temperature T ₁And the water temperature value T that records of the water temperature sensors 13 in the FGD water tank 12 _Water, calculate according to formula (II) in the lump and calculate water spray value G _Sw

When (5) in desulfurizing tower 6, possessing (operating) water nozzle subsystem entry condition, start the feed pump 9 outside the FGD water tank 12, open the water inlet and the backwater valve of reverse-flow type (operating) water nozzle 7 front and back this moment, according to calculating water spray value G _SwWith the water spray COEFFICIENT K _WaterSetting, according to the correspondence in the adjustment of backwater magnetic valve aperture curve (as Fig. 3) is set, adjust the aperture of backwater solenoid valve 11, control reverse-flow type (operating) water nozzle 7 is sprayed water in tower, (operating) water nozzle inlet flow rate meter 8 records actual (operating) water nozzle inlet flow rate value and actual (operating) water nozzle circling water flow rate value respectively with (operating) water nozzle circling water flow rate meter 10, obtains the actual injection flow rate G of (operating) water nozzle _Sw', and with the desulfurizing tower injection flow rate G that calculates _SwRelatively, make the actual injection flow rate G of desulfurizing tower _Sw' near the desulfurizing tower injection flow rate G that calculates _SwAdjustment module by control section is regulated backwater magnetic valve aperture; The adjustment module of control section is according to the desulfurizing tower injection flow rate G that calculates _SwAnd between limber up period, draw good back-water valve (BWV) aperture-injection flow rate relation curve and compare, draw the back-water valve (BWV) aperture of coupling, obtain the actual injection flow rate G of desulfurizing tower by regulating the back-water valve (BWV) aperture _Sw', make the actual injection flow rate G of desulfurizing tower _Sw' near the desulfurizing tower injection flow rate G that calculates _Sw

(6) the actual injection flow rate G of (operating) water nozzle of measurement gained _Sw' with the former humidity of flue gas d that calculates ₁, import cat head humidity of flue gas d ₂The unit obtains cat head humidity of flue gas d according to formula (III) ₂

(7) water that sprays into desulfurizing tower 6 in tower after atomizing with tower in flue gas and the abundant hybrid reaction of material, to the desulfurizing tower cat head, the temperature sensor 14 of desulfurizing tower 6 cats head, static pressure transducer 16 record the flue-gas temperature T of desulfurizing tower cat head respectively ₂With cat head flue gas static pressure P ₂, with cat head humidity of flue gas d ₂Import cat head flue gas relative humidity RH in the lump ₂Computing unit obtains the cat head flue gas according to formula (IV) and calculates relative humidity RH ₂Calculate cat head flue gas relative humidity RH ₂Enter cat head flue gas dew point T again _Dp2Computing unit obtains the cat head flue gas by formula (V) and calculates dew point T _Dp2

(8) the cat head flue gas electrical conductivity λ that records at the flue gas conductivity meter 15 of desulfurizing tower 6 cats head ₂Value directly enters the relative humidity-electrical conductivity of PLC control system 26 and checks the unit, by comparing with drawing good relative humidity-conductivity relation curve, obtains the cat head flue gas relative humidity check value RH to correspondence ₂'.This relative humidity check value RH ₂' obtain cat head flue gas dew point temperature check value T according to formula (VI) _Dp2'.

The flue gas of desulfurizing tower 6 outlet evenly enters each air chamber of sack cleaner 17 through water conservancy diversion, finishes the separation of gas, solid two-phase therein, and gas phase enters air-purifying chamber 18.Version according to rearmounted sack cleaner 17, generally independently in the air-purifying chamber 18 one group of temperature sensor 19 and relative humidity sensor 20 are set all at each, the data of each air-purifying chamber collection are reached PLC control system 26 by data signal line 25, in PLC control system 26 collected temperature and relative humidity are carried out mean value computation, the average of gained is and enters cloth bag air-purifying chamber flue gas dew point T _Dp3The air-purifying chamber flue-gas temperature T of unit ₃With air-purifying chamber relative humidity RH ₃PLC control system 26 is also monitored the maximum that records in the rh value in a plurality of air-purifying chambers in addition, and is wet excessively to prevent the local flue gas of sack cleaner.At cloth bag air-purifying chamber flue gas dew point T _Dp3In the unit, calculate cloth bag air-purifying chamber flue gas dew point T according to formula (VII) _Dp3Generally, after operation a period of time, according to different operating conditions, by comparing the difference of three dew point value, by the artificial cat head flue-gas temperature of setting, make whole desulphurization system operate under a rational temperature and the relative humidity condition again, finish the safety and stability control of whole system.After the promptly normal operation, the flue gas relative humidity in the sack cleaner is 25%～35%, and flue-gas temperature is higher than 20 ℃ of dew-point temperatures, and whole system can the continous-stable operation.

Set flue-gas temperature T at cat head _SdIn the unit, with cat head flue gas dew point T _Dp2, check cat head flue gas dew point T _Dp2', cloth bag air-purifying chamber flue gas dew point T _Dp3Three dew-point temperatures strengthen 20 ℃ respectively and set the cat head flue-gas temperature relatively with artificial, get four maximums in the value usually as new cat head flue-gas temperature setting value T _SdBring formula (II) into, calculate injection flow rate G _Sw, be used to control injection flow rate, so circulation.

(1) generally, after operation a period of time, according to different operating conditions, by comparing the difference of three dew point value, passing through the artificial cat head flue-gas temperature of setting, make whole desulphurization system operate under a rational temperature and the relative humidity condition, finish the safety and stability control of whole system.After the promptly normal operation, the flue gas relative humidity in the sack cleaner is about 30%, and flue-gas temperature is higher than 20 ℃ of dew-point temperatures, and whole system can the continous-stable operation.

(2) the clean flue gas in the sack cleaner air-purifying chamber 18, enter atmosphere by sack cleaner exhaust pass 19, in sack cleaner exhaust pass 19, be provided with temperature sensor 22, static pressure transducer 23, exhaust gas components analyzer 24, the main purpose of this group analysis instrument is to check the flue gas qualified discharge whether enter atmosphere, certainly, thereby the measuring instrument of front there is an auxiliary check effect by can confirm further also to the measurement of exhaust gas components and water capacity whether the relative humidity of flue gas is too high.

Adopt the method to control and regulate, the operation of whole system continous-stable does not find that SR increases, sticks with paste problems such as bag, for the safe and stable operation of system provides good guaranteeing role.

Claims (6)

1. the control method of injection flow rate in the semi-dry desulfurizing process belongs to the part of whole semi-dry desulphurization system, and when desulphurization system started, the whole job step of injection flow rate control system was as follows:

When 1) desulphurization system started, flue gas entered in the desulfurizing tower via the desulfurizing tower gas approach, in the desulfurizing tower gas approach to the composition of flue gas, go into the tower flue gas volume flow Q _Fg, porch flue gas static pressure P ₁, entrance flue gas temperature T ₁Measure, and calculate the water capacity d of the former flue gas in desulfurizing tower porch according to following formula ₁:

$d_1=\frac{0.8039\&times;X_{H2O-1}}{{\mathrm{\&rho;}}_{\mathrm{fg}\left(d\right)}\&times;(1-X_{H2O-1})}---\left(I\right)$

ρ wherein _{Fg (d)}Be desulfurizing tower porch mark attitude butt smoke density, X _H2O-1Be water vapour content in the desulfurizing tower inlet flue gas;

2) start before the (operating) water nozzle subsystem, manually set cat head flue-gas temperature setting value; Set desulfurizing tower water spray COEFFICIENT K simultaneously _WaterCalculate water spray value G according to following formula _Sw:

$G_{\mathrm{sw}}=K_{\mathrm{water}}\&times;\frac{{\mathrm{\&rho;}}_{\mathrm{fg}\left(w\right)}\&times;Q_{\mathrm{fg}}\&times;C_{p,\mathrm{fg}}\&times;(T_1-T_{\mathrm{sd}})}{{\mathrm{\&Delta;}}_{\mathrm{vap}}{H}_{\mathrm{water}}+C_{p,H2O}\&times;(T_{\mathrm{sd}}-T_{\mathrm{water}})}---\left(\mathrm{II}\right)$

ρ wherein _{Fg (w)}Be desulfurizing tower porch mark attitude wet basis smoke density, C _{P, fg}Be the enthalpy of desulfurizing tower porch flue gas, C _{P, H2O}Be the enthalpy of corresponding temperature water, Δ _VapH _WaterEnthalpy of phase change for corresponding temperature water; Q _FgFor going into tower flue gas volume flow, ρ _FgBe inlet flue gas density, T ₁Be the water temperature T in entrance flue gas temperature and the water tank _Water, T _SdBe cat head flue-gas temperature setting value;

3) by actual injection flow rate G _Sw' with the former humidity of flue gas d that calculates ₁, calculate cat head humidity of flue gas d according to following formula ₂:

$d_2=\frac{m_{v1}+{G_{\mathrm{sw}}}^{\&prime;}}{m_{a1}}---\left(\mathrm{III}\right)$

M wherein _V1Be desulfurizing tower porch steam quality, m _A1Be desulfurizing tower porch dry flue gas quality;

4) water that sprays into desulfurizing tower in tower after atomizing with tower in flue gas and the abundant hybrid reaction of material, to the desulfurizing tower cat head; Record the flue-gas temperature T of desulfurizing tower cat head ₂, cat head flue gas static pressure P ₂With cat head humidity of flue gas d ₂, calculate relative humidity RH according to following formula ₂:

${\mathrm{RH}}_2=\frac{d_2}{\frac{M_{v2}}{M_{a2}}+d_2}\&times;\frac{P_2}{P_{s2}}\&times;100\%(P_{s2}<P_2)---(\mathrm{IV}-a)$

Or ${\mathrm{RH}}_2=\frac{d_2}{\frac{M_{v2}}{M_{a2}}+d_2}\&times;100\%(P_{s2}>P_s)---(\mathrm{IV}-b)$

M wherein _V2Be desulfurizing tower cat head place steam amount of substance, M _A2Be desulfurizing tower cat head place dry flue gas amount of substance;

Pass through formula again

$T_{\mathrm{dp}2}=\frac{243.12\&times;\ln (\frac{{\mathrm{RH}}_2}{100}+\frac{17.62\&times;T_2}{243.12+T_2})}{17.62-\ln (\frac{{\mathrm{RH}}_2}{100}+\frac{17.62\&times;T_2}{243.12+T_2})}---\left(V\right)$

Calculate the cat head flue gas and calculate dew point T _Dp2

5) the cat head flue gas electrical conductivity λ that records at the desulfurizing tower cat head ₂Value directly enters the PLC control system, by comparing with drawing good relative humidity-conductivity relation curve, obtains corresponding cat head flue gas relative humidity check value RH ₂'; Formula rule of thumb

${T_{\mathrm{dp}2}}^{\&prime;}=\frac{243.12\&times;\ln (\frac{{{\mathrm{RH}}_2}^{\&prime;}}{100}+\frac{17.62\&times;T_2}{243.12+T_2})}{17.62-\ln (\frac{{{\mathrm{RH}}_2}^{\&prime;}}{100}+\frac{17.62\&times;T_2}{243.12+T_2})}---\left(\mathrm{VI}\right)$

Draw cat head flue gas dew point check value T _Dp2';

6) flue gas of desulfurizing tower outlet evenly enters each air chamber of sack cleaner behind water conservancy diversion, finishes the separation of gas, solid two-phase therein, and gas phase enters air-purifying chamber; According to flue-gas temperature and the relative humidity that each chamber in the rearmounted sack cleaner is measured, in the PLC control system, collected flue-gas temperature and relative humidity are carried out mean value computation, obtain the temperature T of sack cleaner air-purifying chamber ₃And relative humidity RH ₃, formula rule of thumb again

$T_{\mathrm{dp}3}=\frac{243.12\&times;\ln (\frac{{\mathrm{RH}}_3}{100}+\frac{17.62\&times;T_3}{243.12+T_3})}{17.62-\ln (\frac{{\mathrm{RH}}_3}{100}+\frac{17.62\&times;T_3}{243.12+T_3})}---\left(\mathrm{VII}\right)$

Draw cloth bag air-purifying chamber flue gas dew point value T _Dp3

7) will calculate cat head flue gas dew point T _Dp2, cat head checks flue gas dew point T _Dp2' and cloth bag air-purifying chamber flue gas dew point T _Dp3, set value T with current cat head flue-gas temperature after three dew-point temperatures add 20 ℃ respectively _SdRelatively, get four maximums in the value as new cat head flue-gas temperature setting value T _SdBring formula (II) into, calculate injection flow rate G _Sw, be used to control injection flow rate, as step 1)～7) and circulation.

2. the control method of injection flow rate in the semi-dry desulfurizing process according to claim 1 is characterized in that: after the normal operation, the flue gas relative humidity in the sack cleaner is controlled at 25%～35%, and flue-gas temperature is higher than 15～25 ℃ of flue gas dew point temperature.

3. a control system that is used for the semi-dry desulfurizing process injection flow rate of claim 1 or 2 described methods comprises DATA REASONING, data computation and controls three parts, it is characterized in that:

DATA REASONING partly comprises:

1) desulfurizing tower gas approach exhaust gas components analyzer (2), desulfurizing tower inlet flue gas traffic analyzer (3), desulfurizing tower inlet static pressure transducer (4), desulfurizing tower inlet temperature sensor (5) are installed in entering the preceding desulfurizing tower gas approach (1) of desulfurizing tower (6); The outputting measurement value of these sensors and analyzer reaches PLC control system (26) by data signal line (25) respectively;

2) between desulfurizing tower (6) aditus laryngis section and straight length, install back streaming (operating) water nozzle (7), water spray subsystem under it comprises water tank (12), water temperature sensor (13) is installed in the water tank (12), and water tank is outer by pipeline the be linked in sequence water inlet of feed pump (9), (operating) water nozzle inlet flow rate meter (8), reverse-flow type (operating) water nozzle (7) and water return outlet, (operating) water nozzle circling water flow rate meter (10), backwater solenoid valve (11); Water temperature sensor (13) reaches PLC control system (26) with the water temperature that records by data signal line (25), and the injection flow rate data after handling through PLC control system (26) are passed through data signal line (25) again and fed back to electromagnetism backwater control valve (11);

3) at the desulfurizing tower cat head desulfurizing tower tower top temperature sensor (14), desulfurizing tower cat head flue gas conductivity meter (15), desulfurizing tower cat head static pressure transducer (16) are installed; The outputting measurement value of these sensors and conductivity meter reaches PLC control system (26) by data signal line (25) respectively;

4) mounting temperature sensor (19) and relative humidity sensor (20) in each cell (18) of the deduster air-purifying chamber of sack cleaner (17); Outlet temperature sensor (22), outlet static pressure transducer (23), outlet exhaust gas components analyzer (24) are installed on the exhaust pass behind the sack cleaner (21); Each probe all connects corresponding tester by holding wire, shows on the spot and data signal is sent to PLC control system (26) by data signal line (25).

Data computation is by the PLC control system data to be calculated; Comprise: the former humidity of flue gas d in the PLC control system ₁Computing unit, desulfurizing tower injection flow rate G _SwComputing unit, cat head humidity of flue gas d ₂Computing unit, cat head flue gas relative humidity RH ₂Computing unit, cat head flue gas dew point T _Dp2Computing unit, check cat head flue gas dew point T _Dp2' computing unit, cloth bag air-purifying chamber flue gas dew point T _Dp3Computing unit; Former humidity of flue gas d ₁Computing unit is used to calculate the water capacity d of the former flue gas in desulfurizing tower porch ₁Desulfurizing tower injection flow rate G _SwComputing unit is used for calculating water spray value G _SwCat head humidity of flue gas d ₂Computing unit is used to calculate cat head humidity of flue gas d ₂Cat head flue gas relative humidity RH ₂Computing unit is used to calculate cat head flue gas relative humidity RH ₂Cat head flue gas dew point T _Dp2Computing unit is used to calculate cat head flue gas dew point T _Dp2Check cat head flue gas dew point T _Dp2' computing unit is cat head flue gas electrical conductivity λ ₂Value compares with drawing good relative humidity-conductivity relation curve, to cat head flue gas dew point T _Dp2Check; Cloth bag air-purifying chamber flue gas dew point T _Dp3Computing unit is used to calculate cloth bag air-purifying chamber flue gas dew point T _Dp3

Control section comprises: the actual parameter that partly obtains according to part of detecting and data computation enters logic default in the PLC and controls; Main control module is a selectivity module and an adjustment module; The selectivity module places cat head to set flue-gas temperature T _SdIn the unit, the effect of selectivity module is when setting the cat head flue-gas temperature, will calculate cat head flue gas dew point T _Dp2, check cat head flue gas dew point T _Dp2', cloth bag air-purifying chamber flue gas dew point T _Dp3Respectively add a definite value, compare with artificial setting cat head flue-gas temperature, the maximum of gained is as new cat head flue-gas temperature setting value T _SdInput to desulfurizing tower injection flow rate G _SwComputing unit calculates desulfurizing tower injection flow rate G _Sw, use G _SwControl desulfurizing tower injection flow rate; The effect of adjustment module is according to the desulfurizing tower injection flow rate that calculates backwater magnetic valve aperture to be regulated.

4. the control system of injection flow rate in the semi-dry desulfurizing process according to claim 3 is characterized in that: check cat head flue gas dew point T _Dp2' computing unit is in that " relative humidity-conductivity relation curve is to draw under the simulated flue gas environment, and via an experience curve of a plurality of engineering practices check, is resulting by the relation of flue gas relative humidity and flue gas electrical conductivity.

5. according to the control system of injection flow rate in claim 3 or the 4 described semi-dry desulfurizing process, it is characterized in that: control section is with calculating cat head flue gas dew point T _Dp2, check cat head flue gas dew point T _Dp2', cloth bag air-purifying chamber flue gas dew point T _Dp3Respectively add 20 ℃, compare, get four maximums in the value as new cat head flue-gas temperature setting value T with artificial setting cat head flue-gas temperature _SdInput to desulfurizing tower injection flow rate G _SwComputing unit calculates desulfurizing tower injection flow rate G _Sw

6. according to the control system of injection flow rate in claim 3 or the 4 described semi-dry desulfurizing process, it is characterized in that: (operating) water nozzle inlet flow rate meter (8) and (operating) water nozzle circling water flow rate meter (10) record actual (operating) water nozzle inlet flow rate value and actual (operating) water nozzle circling water flow rate value respectively, the actual injection flow rate G of desulfurizing tower that calculates according to (operating) water nozzle inlet flow rate value and (operating) water nozzle circling water flow rate value _Sw', and with the desulfurizing tower injection flow rate G that calculates _SwRelatively, make the actual injection flow rate G of desulfurizing tower _Sw' near the desulfurizing tower injection flow rate G that calculates _Sw, backwater magnetic valve aperture is regulated by the adjustment module of control section; The adjustment module of control section is according to the desulfurizing tower injection flow rate G that calculates _SwAnd between limber up period, draw good back-water valve (BWV) aperture-injection flow rate relation curve and compare, draw the back-water valve (BWV) aperture of coupling, make the actual injection flow rate G of desulfurizing tower _Sw' near the desulfurizing tower injection flow rate G that calculates _Sw

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