NL8004129A - METHOD FOR HEATING COOKING OVEN - Google Patents

Description

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% i VO 725

Method of heating coking furnaces

The invention relates to a method of heating coking furnaces with a distillation gas, to which is added in varying amounts of heating-weaker gas with regenerative heat exchange, only between the combustion air and the burned gases.

In metal smelting coke oven companies or near such or other installations, where in operation, in varying amounts, a heating-weak gas is obtained as the distillation gas from the coking oven, one is first of all from the distillation gas of the column for other purposes. The coking oven can be operated with a mixed gas from the appropriate strong gas "stark gas" and the heating weaker gas; the strong gas with the weak gas can be emaciated to such an extent that the mixed gas does not fall below a lower heating value of 2500, preferably 3,000 kcal / m.

A further reduction in the heating value would adversely affect the degree of heat effect; the andas in the case of preheating by the regenerator at weak gas and does not take place; the method must also be feasible with a pure strong gas oven.

The mixed gas is therefore operated in the usual manner by the strong gas heating system. However, because of the larger gas quantities and the higher gas weights, the use of higher pressures than with pure strong gas heating is required. The pressures are set as low as possible in cm to avoid the risk of gas leaks through the amputation and sealing devices. In practice, these pressures are approximately 120-150 mm of water column in the sub-distribution pipe and in the so-called nozzle line below 100 mm of water column running in interruption furnaces in the cellar. If the pressures of a mixing gas with a maximum addition to heating weaker gas are adjusted and the nozzles of a heating wall are drilled so far that a pressure of approximately 90 mm of water column in the nozzle line prevails, then a heating changeover will with a pure strong gas, the pressure drops so far that a reasonable distribution of the strong amount of gas at the individual burn spots of the heating wall becomes impossible.

8004129 -2-

The adjustment of the nozzle cross-sections each time upon changing and switching to heating with a mixed gas of another composition or heating with pure strong gas is not eligible.

Here the invention intervenes. The pressure in the distribution line is set to a value corresponding to the maximum addition of heating weaker gas to form the mixing gas and the larger amount of heat supplied to the furnace at a smaller or missing addition of heating weaker gas is introduced by heating breaks discounted within each regenerative half period.

-10 The duration of the pause should be determined longer or shorter, depending on whether the heating value of the mixed gas has a higher or lower value due to a smaller addition of heating weaker gas. By such a way of working it is possible to adapt optimally to all data of the gas combination, without changing the cross sections of the nozzles and other control elements which are important for the distribution. It is only necessary to design the switch-on device in such a way that longer or shorter heating breaks can be inserted by means of it. When the heating value of the mixed gas is changed, only a displacement of this member arranged on the autostring winch is required during operation: Either the pause or its duration must be changed.

Measures for enabling breaks in heating within each regenerative half-period are known per se. For example, before the break is started after the gas valves have been closed, it is possible to place a flue gas throttling device located in the connecting pipe between the flue gas collecting duct and the chimney, whereby only less suction is active in the flue gas collecting duct.

Another way of obtaining a heating break consists in first closing the gas taps and then centering all air valves as well as all flue gas valves.

The numerical example below explains the new heating method in more detail.

Given the heating value of the strong gas 35 Hu = 1 * 500 kcal / Mu3, the gas weights * 0, U kg / Mn. ^ The heating value of the weak gas 8004129 ^ y * -3-

Hu = TOO keal / Ifci3 the gas weights = 1.2 kg / Ιδη3,

In order to achieve a mixed gas heating rate of E = 3000 kcal / µm with the given strong and weak gas heating values and densities, approximately 60% strong gas must be mixed with 10% gas.

The gas level of the mixed gas is 0.72 kg / ηδη.

The same amount of heat must be used for the mixed gas heating as for the strong gas heating. mm water column are present. This would no longer be sufficient to ensure a rational distribution of the strong amount of gas on the individual focal points of the heating walls. To increase this pressure to 90 mm water column, the gas amount of flow should be increased approximately by the amount of about · 2, that is, double the amount of strong gas must be used to keep the nozzle string pressure constant at • 90 mm maintain water column.

With a 30 minute regenerative half period, that would correspond to using 15 minutes heating and 15 minutes heating pause for the pure strong gas heating to ensure the same heat supply in each regenerative half period as with mixed gas heating. When heating with a mixed gas of a higher heating value, i.e. less admixture of the heating weaker gas, to 2-5 of the strong gas, a correspondingly shorter time value for the heating pause appears.

8004129

Claims (2)

1. A method of heating coking with distillation gas, to which is added weaker gas in varying amounts of heating, with regenerative heat exchange only between the combustion air and the burned gases, characterized in that the 5 pressure in the distribution line is maintained at a constant value, which corresponds to the maximum additive of weaker gas heating to form the mixing gas and the greater amount of heat supplied to the furnace with smaller or missing weaker gas additive by switching on heating breaks within each regenerative half-period is discounted. Method according to claim 1, characterized in that the pause is chosen longer or shorter, depending on whether the heating value of the mixed gas has a higher or lower value due to a smaller addition of weaker gas heating. 8004129