ISSN 1068�364X, Coke and Chemistry, 2010, Vol. 53, No. 11, pp. 400–404. © Allerton Press, Inc., 2010.Original Russian Text © V.N. Rubchevskii, Yu.A. Chernyshov, S.S. Smeyan, I.A. Firyulin, A.L. Borisenko, A.S. Malysh, E.I. Toryanik, D.V. Belikov, 2010, published in Koks iKhimiya, 2010, No. 11, pp. 6–11.

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Coke discharge from the coking chambers into aslaking tank or rail car releases considerable quantitiesof dust into the atmosphere. On ejection of the cokecake, coke and gas emissions may be expected for peri�ods of up to 1 min at intervals of 10–20 min. Dustemissions are formed in the discharge of coke at~1000°C as a result of the creation of a strong upwardconvective air flux (initial speed 5–10 m/s), whichtransports upward the small particles formed on disin�tegration of the coke cake. On contact with the air,incompletely coked coal forms dust and soot clouds,which considerably pollute the air on account of theirvolatility. Besides the particulates, the air is pollutedwith coke�oven gas from the furnace chambers [1]. Forenvironmental protection, the Giprokoks Instituteand Slavyansk Design Bureau have developed dust�free coke�discharge modules, which have been intro�duced at a number of coke plants.

At present, two types of dust�free coke�dischargemodules are employed at Ukrainian coke shops: thosewith a stationary dust�removal system; and those witha portable system mounted on the door�openingmachine. Both types are in use in the coke shop atOAO Zaporozhkoks.

Coke batteries 1 and 2A are equipped with a dust�free coke�discharge system intended for localizationof the dust in coke discharge and its transportation toa two�stage dust�removal unit. The first stage consistsof dry inertial dust traps (TsP�2 cyclones); the secondstage consists of FRO�2500 bag filters. Dry cleaning inhigh�efficiency equipment guarantees reduction inatmospheric dust emissions to 20–40 mg/m3. Thetrapped dust is sent to specially equipped cement cars,discharged to the settling tanks of slaking tower 1, andthen added to commercial product (size class

<10 mm) that is supplied to customers in a mixturewith coke fines from coke sorting. To prevent explo�sions in the dust�removal modules, the collectors inthe first stage must be equipped with special safetyvalves.

Analysis of the operational characteristics of thedust�free coke�discharge modules for coke batteries 1and 2A shows that, on average, 80–90% of the dustemitted from the coke�chamber is captured; the effi�ciency of the dust�free coke�discharge module itself is70–80%. The main deficiency of the dust�free coke�discharge module is difficulty in assessing the effi�ciency of the first stage in trapping (localizing) thedust–air flux.

At this stage, the main method employed is visualassessment: visual assessment of the proportion (inpercent) of the dust–gas flux that is sucked into thehood and the proportion that is released into theatmosphere; and visual assessment of the gross dustemissions (concentration) from the furnace chamber,on the basis of the color of the plume. The basicsources of the emissions are as follows:

⎯the junctions between the coke�guiding door�opening machine and the coking chamber andbetween the guides and pipes of the door�openingmachine and the valves of the transportation line;

⎯insufficient coverage of the coke surface in theslaking car by the hood of the door�opening machines;

⎯points of dust discharge from the collection bun�ker to specially equipped cement cars and its deliveryto the tanks of slaking tower 1.

Unfortunately, quantitative visual assessment (inpercent) of pollutant emissions from such sources maybe very approximate. Nevertheless, in some cases, the

More Efficient Operation of the Dust�Free Coke�Discharge Modules at OAO Zaporozhkoks Coke Batteries 5 and 6

V. N. Rubchevskiia, Yu. A. Chernyshova, S. S. Smeyana, I. A. Firyulina, A. L. Borisenkob, A. S. Malyshb, E. I. Toryanikb, and D. V. Belikovb

aOAO Zaporozhkoks, Zaporozhe, Ukrainee�mail: offis@coke.zp.ua

bUkrainian State Coal�Chemistry Institute, Kharkov, Ukrainee�mail: post@ukhin.org.uaReceived February 22, 2009

Abstract—Two types of dust�free coke�discharge modules are generally employed. The modules employed atOAO Zaporozhkoks are described and analyzed. Methods are proposed for determining their operationalefficiency and testing their performance in plant conditions. Recommendations are made for improving theoperational efficiency of dust�free coke�discharge modules mounted on door�opening machines.

DOI: 10.3103/S1068364X10110025

COKE

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MORE EFFICIENT OPERATION OF THE DUST�FREE COKE�DISCHARGE MODULES 401

efficiency in reducing emissions may be determinedwith satisfactory accuracy. The development of mea�sures for more efficient dust removal requires furtherstudy.

The limiting permissible parameter values for dustremoval are developed in accordance with the opera�tional rules for safe maintenance of gas and dust trapsand are included in the dust–air flux ratings for gas�purification systems.

Coke batteries 5 and 6 at OAO Zaporozhkoks areequipped with dust�free coke�discharge modulesdeveloped by STA Tekhnika [2, 3]. The modules atbatteries 5 and 6 are completely identical and consistof two�slot hoods above the slaking car (covering morethan half of its area), suction fans for the dust and gasemissions, water sprayers for the dust emissions, and asystem for release of the purified gas to the atmo�sphere. In coke discharge, some of the emissions arelocalized by the hood and sprayed with water. Thewater with dust particles flows down into the slakingcar, while the purified waste gas is released to theatmosphere.

The system includes the following components, asshown in the figure. The external hood takes the formof a truncated pyramid (larger at the bottom than thetop) and consists of sections welded together fromrolled profiles and lined with stainless�steel sheet. Theexternal hood is suspended (by means of hinges) fromthe coke guides of the door�opening machine. Theinternal hood is of the same shape as the external hoodand is mounted inside it so as to leave an interveningchannel.

The fan intended to suck the dust–air flux from thecoke discharge zone is attached to the upper part of theexternal hood. The diffuser is attached to the fan andconsists of a housing, a pipe, and a sprayer. In theupper part of the diffuser, there is a suspension systemconsisting of a flange and welded pipes. The sprayer isattached to the vertical pipe and may rotate onaccount of the reaction forces in water supply. Thepipe is attached to the upper part of the diffuser and isintended for upward transportation of the gases.

The water tank consists of a housing, a pump, alevel indicator, a thermometer, and two electricmotors. At the top of the welded housing, there is apipe for water flow. In the lower part of the tank, thereis a flanged pipe with a valve for water runoff. Thepump in the lower part of the tank is equipped withpipes for water intake and a pipeline for water supplyto the diffuser. Access for adequate maintenance of thecomponents is provided. The basic characteristics ofthe system are as follows:

Flow rate of dust–air mixture, m3 h ≤40000

Temperature of dust–air mixture, °C 500–800

Vacuum, Pa (mm water) 12 (1.2)

Water consumption per coke discharge, m3 0.18

Installed power, kW 13.3

Before operation begins, the door�openingmachine with the dust�free coke�discharge modules isplaced in the position corresponding to filling of thetank with water. This process is monitored by means ofa float and sensor. The optical signal corresponding tofilling of the tank is sent to the operator’s cabin of thedoor�opening machine. Then the operator beginsmaintenance of the coke battery. When the coke�guidecompartment is aligned with the axis of the cokingchamber to be inspected, a command is sent from theoperator of the door�opening machines to switch onthe fan and pump drives in the system. The fans andpumps are switched off by a signal from the sensormonitoring the departure of the coke�guide compart�ment from the furnace chamber.

When the fan and pump drives are switched on, thedust�laden air above the slaking car is drawn upwardand passes through the hood, the fan, the diffuser, andthe outlet pipe. In the diffuser, rotating sprayers wetthe dust–air mixture and consequently dust is depos�ited on the walls of the diffuser and runs down into the

Fan

500

Location of samplingpressure sensor

Location of samplingpressure sensor

Diam. 1000

Diam. 1000

Sampling sensors for determining the efficiency of thedust�removal units at the door�opening machines.

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RUBCHEVSKII et al.

slaking car, together with water from the special chan�nel. The purified water is discharged to the environ�ment through the outlet pipe.

The main deficiency of the dust�free coke�dis�charge module with a mobile dust�removal unit is thatassessment of its operational efficiency by direct mea�surement is difficult. Therefore, specialists at theCoal�Chemistry Institute have developed a methodfor expert–analytical assessment of the operationalefficiency of dust�free coke�discharge modulesmounted at the door�opening machine.

The primary difficulty in assessing the operationalefficiency of dust�free coke�discharge modules hasbeen that the quantity of dust released on coke ejection

from a single coking chamber cannot be directly mea�sured. It depends mainly on the state of the coke cake,which is determined by its temperature prior to dis�charge and the yield of volatiles from the coke. Atpresent, the quantity of dust emissions from the fur�nace chamber is assumed to be 200–350 g/t [4] and isestimated visually from the color of the dust cloud thatforms on coke discharge.

Whereas the operational efficiency of dust�freecoke�discharge module with stationary dust�removalunits is simple to estimate on the basis of direct mea�surements (Table 1), only the dust concentration atdischarge after cleaning may be measured in assessingthe operational efficiency of dust�removal unitsmounted on the door�opening machine.

If a sampling unit with a dust filter is placed underthe suction hood above the hot coke in the slaking car,the measurement is difficult (the intake unit malfunc�tions) and there is extreme spread in the data (Table 2).Therefore, in assessing the operational efficiency,attention focuses on testing and adapting the methodin the coke shop at OAO Zaporozhkoks.

At OAO Zaporozhkoks, local dust�free coke�dis�charge modules are installed on the door�openingmachine of coke batteries 5 and 6. Given that it ispractically impossible to make measurements at thelocal unit—since it is mounted on the door�openingmachine, where the gas temperature at coke dischargeis more than 500°C—we propose an analyticalmethod of determining the operational efficiency ofthe dust�free coke�discharge module.

Table 1. Operational characteristics of stationary dust�removalunits

Limiting permissible values Stage I Stage II

Gas productivity, m3/h 180000 112800 × 2 = 225600

Temperature, °C 130 70

Vacuum, Pa 2500 6000

Dust content, g/m3:

at input 3.0 1.0

at output 1.0 0.05

Degree of purification, % 80 95

Compressed�air pressure, MPa – 0.4–0.6

Table 2. Results of dust analysis for dust�free coke�discharge module at door�opening machine 3 in coke battery 6

Results of Verton�Servis analysis Results of LZOS analysis

input, mg/m3

output, mg/m3

Efficiency of dust removal, %

number of fur�naces per filter

input, mg/m3

output, mg/m3

Efficiency of dust removal, %

number of fur�naces per filter

224.18 106.56 55.60 3; 3 min 190.04 105.14 34 3; 3 min

36.98 14.81 62.38 3; 3 min 339.37 159.76 44 1; 1 min

49.84 22.12 58.52 3; 3 min 203.62 147.47 14 1; 1 min

33.76 15.42 56.93 3; 3 min 17.65 28.51 – 2; 2 min

2.72 1.21 61.43 2; 2 min 16.97 11.81 17 2; 2 min

19.93 7.78 63.42 2; 2 min 40.72 20.36 40 1; 1 min

16.96 1.94 88.18 2; 2 min 541 393 30 1; 5 min

26.79 3.23 87.57 2; 2 min 54 58 – 1; 5 min

26.46 3.23 88.82 2; 2 min 509 72 86 1; 5 min

73.95 29.07 59.39 2; 2 min 2464 274 89 1; 1 min

237.57 189.28 17.83 2; 20 min 3812 119 – 1; 1 min

60.06 20.47 64.95 2; 2 min 4303 143 – 1; 1 min

35.71 10.23 70.53 2; 2 min – – – –

30 0.73 74.83 2; 2 min – – – –

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MORE EFFICIENT OPERATION OF THE DUST�FREE COKE�DISCHARGE MODULES 403

The operational efficiency of the dust�free coke�discharge module mounted on the door�openingmachine is estimated on the basis of two criteria:

⎯the localization of the dust–air emissions by thedust�trapping hood

⎯the efficiency of the gas�purification system.Therefore, the method of determining the opera�

tional efficiency consists of two successive stages. Thefirst stage is visual assessment of the flux of dust–airemissions at coke discharge; part of this flux will belocalized by the hood, while the remainder is dis�charged to the atmosphere without purification (out�side the hood).

In the second stage, we determine the total opera�tional efficiency of the dust�free coke�discharge mod�ule, taking account of the efficiency of the gas�purifi�cation system. The applicability of this method is con�firmed in that, in world practice, visual assessment isemployed to determine the volume of emissions andtheir degree of localization in environmental�protec�tion studies.

LOCALIZATION OF DUST–AIR EMISSIONS BY THE HOOD

A commission consisting of specialists fromOAO Zaporozhkoks and the Coal�Chemistry Institutehas undertaken visual assessment of the dust�freecoke�discharge module mounted at the door�openingmachine of coke battery 6.

The unorganized emissions (outside the hood) atthis dust�free coke�discharge module were assessed onJuly 10, 2006, for coke discharge from coking cham�bers 645, 647, 649, 651, 655, and 657. Each expertrecorded visual assessments (in percent) of the volumeof nonlocalized emissions (outside the hood) in areport. According to the data from all the reports, themean value for the nonlocalized emissions is 28%.Correspondingly, the degree of localization of theemissions by the local dust�free coke�discharge mod�ule at coke discharge 6 is

Kloc = 100 – 28 = 72%.

DETERMINING THE UNIT DUST EMISSIONS IN COKE DISCHARGE

The efficiency of gas purification is assessed bymeans of a theoretical–analytical method of deter�mining the unit emission of coke dust, as follows. Theinitial quantity of dust at coke discharge without envi�ronmental�protection measures is calculated from theunit emissions in accordance with the standardsadopted by the Ukrainian Ministry of the Environ�ment regarding atmospheric emissions of pollutantfrom coke plants [4]. This quantity is also determinedby expert assessment of the color of the waste gases.The unit dust emissions are 150–350 g/t of coke,according to the data in [4]. A specific value is adopted

in visual assessment of the color of the dust–air emis�sions.

Depending on the color, we select the followingvalue of the unit dust emissions (g/t of coke): 150–200 for transparent gas; 250 for gray gas; and 350 forblack gas.

According to the expert commission, the emissionsare gray, which corresponds to 250 g/t of coke (forcoke battery 6).

In determining the dust concentration, the fan isswitched on throughout coke discharge from the fur�nace; the water consumption in spraying is 250 l perfurnace. According to direct measurements, the dustconcentration after purification is 95–135 mg/m3.Samples are taken in the operator cabin of the door�opening machine. A sampling hood with a dust�col�lection pipe is mounted in a tube with a speciallyequipped area ahead of coke discharge.

On the basis of the results, we calculate the effi�ciency of the dust�free coke�discharge module. Onefurnace of coke battery 6 releases 11.9 t of coke. Thenthe mass of dust released by a single furnace is

min.du = 11.9 × 250 = 2975 g.

The quantity of dust sent for purification ismpu = 2975 × 72/100 = 2142 g/furnace.The quantity of dust that does not enter the hood is

munpu = 2975 × (100 – 72)/100 = 833 g/furnace.

The output dust concentration (C) is 0.135 g/m3.Then the emission rate after purification is

Gmdu = gv

C,

where gv is the volume flow rate of gas, which is

8.33 m3/s for coke battery 6 at OAO Zaporozhkoks (cal�culated on the basis of a fan productivity of 30000 m3/h).Then

Gmdu = 8.33 × 0.135 = 1.12 g/s.

After purification, the mass of dust for the wholedischarge period is

mdp = tmdu,

where t is the discharge period of the coke for a singlefurnace chamber (t = 50 s). For these numerical val�ues, we obtain

mdp = 1.12 × 50 = 56 g/furnace.

Taking account of localization, we write the totalefficiency of the dust�free coke�discharge module inthe form

accordingly

Kte 100 min. du 1 Kloc/100–( )([–=

+ mdp )/ min. du 100×( ) ];

Kte 100 2975 1 0.72–( )([–=

+ 56 )/ 2575 100×( ) ] 70.1%.=

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RUBCHEVSKII et al.

The design of the dust�free coke�discharge modulewith a mobile dust�removal unit is improved as fol�lows. After installation and initial operation of thedust�free coke�discharge module mounted on thedoor�opening machine, we identify the following defi�ciencies.

(1) On coke discharge, capture of the dust–airmixture by the hood for purification is incomplete, toa degree that depends on the condition of the coke.This may be attributed, first, to incomplete coverage ofthe slaking car by the hood’s surface and, second, toinadequate fan power.

(2) It is difficult to measure the dust–air emissions.(3) There is no instrument for measuring the dust–

air emissions after purification.(4) The spraying of the dust–air emissions sent for

purification is unsatisfactory and requires consider�able water consumption.

Measurement of the concentration of the dust–airmixture after purification shows that it is ~150 mg/m3

for the newly installed dust�free coke�discharge mod�ule.

Analysis of these deficiencies gives rise to recom�mendations for corresponding improvement in themobile unit for dust�free coke discharge. To increasethe capture of dust–air mixture by the hood, a systemis introduced for regulating the gap (slot) between theinternal and external hoods, in the form of an adjust�able plate. By this means, the rate of collection of thedust–air emissions may be adjusted. Increasing thecollection rate reduces the local emissions. The effi�ciency of such reconstruction may be evaluated visu�ally, in terms of the degree of localization: 30–50%before reconstruction (depending on the condition ofcoke); and 60–70% after reconstruction.

To increase the capture area above the slaking car,the sides of the external hood module are extended inthe direction of the slaking car’s axis. This increasesthe localization of dust–air emissions by 5–10%.

Analysis of sprayer operation indicates consider�able water consumption and low levels of dustremoval, on account of the inadequate sprayer design.To improve dust removal, the sprayers are redesigned.The efficiency of dust removal largely depends on thesuction of dust–air mixture from the slaking car intothe hood, which is determined by the fan power. Toimprove fan operation, the number of blades isincreased, with corresponding increase in motorpower. As a result of reconstruction, the pressure dif�ference is increased from 100 to 400 Pa (from 10 to40 mm water). The basic deficiency of the dust�freecoke�discharge module is the difficulty of assessing its

operational efficiency by direct measurements. There�fore, to facilitate air sampling from the outlet pipeafter dust removal, the system for such measurementsis improved.

CONCLUSIONS

(1) We have analyzed the design and operationalefficiency of the dust�free coke�discharge moduleswith stationary and mobile dust�removal units in thecoke shop at OAO Zaporozhkoks.

(2) We have determined the deficiencies of thedust�free coke�discharge modules with a portabledust�removal unit at batteries 5 and 6.

(3) We have adapted the expert–analytical assess�ment of the operational efficiency of mobile dust�freecoke�discharge modules (mounted at the door�open�ing machine unit) for industrial use. According to anexpert commission, this method may be adopted inpractice to determine the operational efficiency ofdust�free coke�discharge modules mounted at thedoor�opening machine.

(4) The proposed method shows that the opera�tional efficiency of the dust�free coke�discharge mod�ule is 70–80%, depending on the condition of the cokecake (its final temperature before discharge) and thedesign of the module.

(5) Recommendations for improvement in theoperational efficiency of dust�free coke�dischargemodules with a mobile dust�removal unit have beendeveloped and partially implemented, with increaseddust removal at coke batteries 5 and 6.

(6) The most efficient purification system is a dust�free coke�discharge module with a stationary dust�removal unit. Accordingly, the use of a dust�free coke�discharge module with a mobile dust�removal unitshould be regarded as a temporary measure.

REFERENCES

1. Sukhorukov, V.I., Stakheev, S.G., Stefanenko, V.T., andKukolev, Ya.B., Localization and Processing of Emis�sions in Coke Production, Koks Khim., 2006, no. 3,pp. 54–57.

2. Kaliberda, N.S., Installing a Dust�Free Coke�Dis�charge Module, Koks Khim., 2004, no. 3, pp. 37–40.

3. Tikhov, S.D., Dudarev, B.G., and Kolmakov, N.G.,Dust�Free Coke�Discharge Module: Approaches andEfficiency, Koks Khim., 2004, no. 2, pp. 14–15.

4. Pokazateli emissii (udel’nye vybrosy) zagryaznyayush�chikh veshchestv v atmosfernyi vozdukh osnovykh proiz�vodstv koksokhimicheskikh predpriyatii (AtmosphericPollutant Emissions from Coke Plants), Kharkov, 2006.