RU1778132C - Method for evacuating surplus gas from coke dry flame-quenching plant - Google Patents

Abstract

Usage: in the coke industry, namely in the processes of dry quenching of coke. SUMMARY OF THE INVENTION: Excess gas is removed from a dry coke quenching unit through an adjustable gas outlet located in the upper part of the storage chamber. During the inter-loading period, in the zone of oblique passages, a pressure equal to the sum of the hydraulic resistance of the coke column in the storage chamber, the geometric pressure of the pyrolysis gases in it and the static pressure at the place of installation of the nozzle is maintained. 1 ill., 1 tab.

Description

The invention relates to the field of coke production, namely dry quenching of coke.

The sources of excess gas in the circulation circuit of dry coke quenching (CTC) units are: pyrolysis gas evolution during thermostating of coke in the storage chamber (prechamber), burning of combustible gas components in the annular duct due to controlled air intake or replacement of a part of the circulating gas on technical nitrogen.

There is a known method of evacuating excess gases by discharging them only through a candle after a smoke exhauster. All gas from a fire extinguishing chamber and a pre-chamber (both circulating and excess) is sucked out by a smoke exhauster, passage through a gas cleaning system and a steam boiler, after which excess amounts are discharged to the atmosphere through candle after the exhaust fan

The disadvantage of this method is that due to the need for suction is not

not only circulating, but also a significant amount of excess pyrolysis gas from the volume of the prechamber through oblique passages, the system establishes a hydraulic mode in which the entire prechamber and the top of the fire chamber are under vacuum (-20-40 mm B.C. in the zone of oblique passages). In this case, air leaks through various leaks (especially when loading coke), as a result of which part of the combustible components of the gas burns out and its calorific value decreases, which, even in the absence of an organized gas survival in the annular duct, does not exceed 3270 kJ / m3 (see table .1).

It is also unlikely to use gas with such a calorie content; it is discharged into the atmosphere.

Closest to the proposed technical solution is a method of evacuating excess gases by dumping it (most often simultaneously) through a gas outlet - a candle installed in the upper part of the prechamber and a candle after

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smoke exhaust. The disadvantage of this method is the instability of the flow rate and composition of the excess gas evacuated through the candle in the upper part of the prechamber, as a result of which, like the excess gas from the candle after the smoke exhaust, it is not suitable for further use.

The aim of the method is to increase the calorific value of the excess gas while stabilizing its output and composition for its subsequent beneficial use.

The goal is achieved in that the evacuation of all excess gas is carried out only through an adjustable pipe (candle) in the upper part of the storage chamber. In this case, to create a directed flow of excess gas towards the specified pipe, the hydraulic mode in the chamber changes: the pressure in the zone of oblique passages is established positive and equal to the sum of the hydraulic resistance of the coke column in the storage chamber, the geometric pressure of the pyrolysis gases in it and the static pressure at the gas discharge bottom of a branch pipe.

At the optimum pressure at the installation site of the gas outlet of the pre-chamber + 12-15 mm B.C. (similar to the pressure in the drains and gas collector of the coke oven battery) the pressure in the zone of oblique passages should be + 55-60 mm B.C. (for a CCUT extinguishing unit with a coke capacity of 70 t / h).

For a unit with a capacity of 70 t / h, the maximum geometric height of the coke column in the prechamber (including the oblique passage zone) is 9.5 mm, and the gas column is 10 m. The total number of evacuated gases, the average temperature of the gases in the chamber and their composition It is possible, using well-known hydraulic formulas, to determine the geometric pressure of pyrolysis gases and the hydraulic resistance of the coke layer.

So, the latter for a coke column height of 9.5 m (adjusted for the diagonal of the course of evacuated gases, it should be increased to about 12 m) and taking into account the data on the amount and composition of the evacuated pyrolysis gas below, calculated by the formula is 35 mm BC

The geometric pressure of pyrolysis gases at an average temperature in the prechamber of 900 ° C is, according to calculations, about 5 mm B.C.

The optimal value of the static pressure at the place of installation of the gas outlet pipe according to practical data obtained by testing our method on

Altai coke plant. should be 15 mm B.C.

The sum of the three indicated values is 55 mm B.C., which roughly corresponds to

observed in practice (Table 1) and the recommended optimal pressure value in the zone of oblique passages (+ 55-60 mm B.C.) for a 70 t-unit of the CCPD.

With a possible change in temperature in the prechamber, gas composition and coke column height, a new optimal pressure value in the zone of oblique passages can be determined by calculation, which will ensure the stability of the composition and

Qualitative characteristics of the evacuated excess gas

For such calculations and timely adjustment of the hydraulic mode of the prechamber, it is necessary

equipping with means for measuring pressure (in the zone of oblique passages and in the region of the gas outlet pipe), temperature along its height, composition of evacuated gas and coke level in it. With a decrease in pressure in

the zone of oblique passages up to + 30-40 mm and lower, the upward gas flow in the prechamber cannot overcome the hydraulic resistance of the coke column and excess (including pyrolysis) gas will be sucked out completely or partially through oblique passages and it will need to be discharged through a candle after the smoke exhauster, similarly to the prototype and with its inherent disadvantages.

Pressure increase in the zone of oblique strokes above + 55-600 mm B.C. It does not adversely affect the outlet and composition of the excess gas evacuated through the prechamber candle. However, gas leaks through

path leaks and rising energy costs.

Thanks to the creation of an optimal hydraulic environment in the prechamber in the direction of the gas outlet

Before the chamber, not only the flow of pyrolysis gases released in its volume rises during thermostating of hot coke, but also all the excess gas that can be formed in the circulation circuit (in

in particular in the CCTV stewing chamber). In the absence of surviving combustible components in the annular duct, the amount of the latter will be insignificant.

A comparative analysis of the claimed solution with the prototype shows that the claimed method differs from the known topic. which creates a stable directed upward flow of excess gases passing through a layer of hot coke

in the prechamber and removed only through an adjustable pipe in its upper part.

The listed features were not previously described in other sources of information, therefore, the technical solution meets the criterion of significant differences.

Using the proposed method allows to obtain a positive effect compared with known methods, which boils down to the following;

An increase in the content of combustible components in the excess gas and, correspondingly, its heat of combustion, is 1.9-4.7 times.

Obtaining excess gas of a stable composition for utilization in an independent form or in a mixture with other combustible gases.

Reducing coke fumes by preventing air leaks in the prechamber and eliminating the surviving combustible gas components in the annular duct.

Example. An experimental verification of the proposed method was carried out at an industrial testing station of the Altai coke plant with a coke unit capacity of 70 t / h. The flow rate of circulating gas was 100 thousand m3 / h, gas temperature: 180 ° C at the inlet of the braising chamber, and 800 ° C in the upper annular channel.

Evacuation of excess gases of dry coke quenching was carried out in a facility (see drawing) consisting of quenching chamber 1; storage camera (prechambers) - 2; slanting moves - 3; branch pipe (one hundred) - 4; throttle valves 5, 6; gate valves 7, 8; smoke exhaust candles-9; exhaust fan 10; dust collecting bin 11; waste heat boiler - 12, cyclone - 13.

The circulating gas (1500 m3 / t of coke) moves along the usual path and is supplied to extinguish the coke by the smoke exhauster 10. During the interloading period, the above positive pressure was established and automatically maintained in the zone of oblique passages 3 and in the upper part of the prechamber 2. In this case, all excess gas was evacuated only through the pipe (one hundred to) 4 in the upper part of the pre-chamber 2. The other is equipped with a valve box and is similar in design to the coke oven stacks. In the effluent, excess gas is cooled by water to 115 ° C and sent to a common gas collector, where it is cooled to 75-80 ° C and partially cleaned of dust. The partially dedusted gas is then finally cleaned of dust to the required standards, and then served for disposal.

The required hydraulic mode of the entire tract (including in the zone of oblique moves and

in the prechamber) it was supported by the shutter 8 and the throttle valve 6 with the shutter completely closed on the candle 9 after the smoke exhaust. The combustible components of the circulating gas in the annular gas duct of the extinguishing chamber do not survive by the proposed method, although in principle it is possible provided that air is forced into the annular gas duct.

When the extinguishing unit is under loading with hot coke (loading time of 1 unit on average) - 3.75 min per 1 hour of operation) in order to avoid knocking out gas and flame from the loading funnel, a different hydraulic mode must be established in the prechamber, different from that proposed by our method , and another way to evacuate excess gases from the circuit. The pressure in the upper part of the prechamber should be within ± 01 mm w.s. In this case, the evacuation line of excess gas from the prechamber is disconnected from the gas inlet by means of a standoff valve 4 and a gate valve 8. Excess gas, which, due to possible air leaks through the pre-chamber feed opening, is depleted in combustible components, in this case, it is advisable to discharge into the atmosphere through the smoke exhauster candle 9 by opening the valve 7. although, in principle, it can be partially or completely utilized. In the latter case, however, there will be some decrease (by 15–20% of the calorific value of the total excess gas).

With hermetic loading systems capable of operating without reducing the pressure in the prechamber to 0 ± 1 mm B.C. during the loading period described above, the correction of the hydraulic mode of the circuit and the shutdown of the evacuation path of excess gases from the prechamber may not be performed.

Table 1 shows the main test results, from which it follows that when using the proposed method for evacuation of excess gas, its amount decreases while increasing the content of combustible components (CO and Na) and the heat of combustion to 6200 kJ / m3.

From Table 2 it follows that when implementing the proposed method, significantly, in comparison with the analogue and prototype, the coke fumes decreased and its strength slightly increased.

Claims (1)

SUMMARY OF THE INVENTION A method for evacuating excess gas from a dry coke quenching unit by discharging it from a circulation gas path through an adjustable gas outlet a pipe located in the upper part of the storage chamber, characterized in that, in order to reduce the coke fumes, increase the calorific value of the excess gas while stabilizing its composition, during the inter-loading period in the zone oblique strokes maintain a pressure equal to the sum of the hydraulic resistance of the coke column in the storage chamber, the geometric pressure of the pyrolysis gases in it and the static pressure at the place of installation of the pipe. Table 1 table 2 I - --4 with