SU1752775A1 - Method of preparing humid blast furnace gas for combustion - Google Patents

Abstract

The invention relates to ferrous metallurgy, in particular to the heating of blast furnace stoves. The aim of the invention is to increase the efficiency of using a blast furnace gas by removing a part of the moisture contained therein after a wet gas cleaning by cooling to a temperature below the dew point, 2 sludge.

Description

The invention relates to ferrous metallurgy, in particular to the heating of blast furnace stoves.

Closest to the present invention is a method for preheating a gas using an intermediate heat carrier. The blast-furnace gas in front of the stove burners is heated by the heat of the exhaust gases from the stove. For this, the two heat exchangers are combined into a common network through which the intermediate coolant circulates. This saves fuel, increases the temperature of the combustion.

However, the possibilities of increasing the efficiency of gas use by drying it are not used.

The aim of the invention is to increase the efficiency of use of moist blast furnace gas.

This goal is achieved by the fact that with the help of an intermediate heat carrier the moist gas is cooled to a temperature below the dew point (the saturation temperature of the content in the water

vapor), then dried by separating and removing the condensed moisture from the stream and thereafter the dried gas is heated with the help of an intermediate heat carrier.

It is possible that the damp blast furnace gas is mixed with water cooled to a temperature below the dew point, then drip moisture (released during cooling and supplied from the outside) is separated and removed from the stream, and the dried blast gas is heated in a surface heat exchanger with an intermediate heat carrier.

FIG. 1 and 2 show the implementation of the proposed method.

A venturi tube (or any other mixing heat exchanger) 2 is integrated into the gas pipeline 1. Next, along the gas flow, there is a moisture separator 3 with a water distributor 4, a diverter 4 is connected to an evaporator tank 5. The steam volume of the tank 5 is connected to the ejector 6, and the water volume - with a pump 7. After the gas separator 3, there is a heat exchanger 8 along the gas path. To the ejector 6, the working (sharp) steam is supplied from the outside, the mixture is working (L

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What and the secondary steam from the ejector 6 enters the heat exchanger 8.

The scheme uses two intermediate heat carriers — cooled below tp, water (apparatuses 2-3–4–5–7–2) and steam (apparatuses 6–8–5–6). Tank 5 has an overflow of excess moisture. The scheme is equipped with the necessary fittings, means of KILiA,

In addition to (instead of) the heat exchanger 8, there may be other low potential heat consumers, and the heat exchanger 8 may have another heating coolant, for example hot steam.

The method is carried out as follows.

Wet blast furnace gas is fed into the Venturi tube 2. Here, in the neck of the pipe 2, water is supplied with a temperature below the temperature of the dew point of the gas. Due to contact and interfacial heat exchange, the gas is cooled to a temperature below the dew point. A portion of the water vapor contained in the gas is condensed. The precipitated moisture, together with the irrigation water, is separated from the flow in the droplet separator 3 and drained off by the water outlet 4. The dried and cooled blast-furnace gas is fed to the heat exchanger 8, where it is heated above the initial temperature. Next, the gas is sent for combustion,

From the drainage system 4, a separate gas stream from the water and condensate of the vapor is drained into the evaporator tank 5. Here, the ejector 6 creates a vacuum. 8, tank 5 is drained of liquid (water and steam condensate) boil under vacuum and partially turn into secondary steam. By boiling, the water is cooled below tp. The cooled water is pumped into the mouth of the Venturi tube 2 by the pump 7. The mixture of working and secondary steam at the outlet of the ejector 6 has a pressure higher than the pressure in the tank 5. Due to this, the temperature of the mixed steam is higher than the initial temperature of the wet gas. Therefore, in the heat exchanger 8, heating of the dried gas is possible up to a temperature higher than the initial one.

As a result of the process, the heat of combustion of the gas increases, since

the amount of water vapor in it decreases. The calorimetric temperature of the combustion gas also increases due to the preheating of the gas. Heat losses from flue gases during burning of the dried gas are reduced as the amount of flue gases decreases. In general, the combustion efficiency of a moist blast furnace gas increases to a greater extent than by a known method.

Example. Evaluation of economic efficiency.

Blast furnace air preheaters Bitter 216 m are heated with moist blast furnace gas, to which 20% (by heat) of natural gas is added to increase the calorimetric temperature. Consumption of wet blast furnace gas 20,000 m3 / h, natural gas 500 m / h. The mixed gas has a TeMneoaTvovtr 45 ° C moisture content dr - 76 g / m. This gas} is cooled to tr 30 C, while the moisture content is reduced to ag 33.7 g / m 3, 846 kg of condensate is removed from the gas stream. The mixture of working and secondary steam of the ejector has a pressure of 0.7 this and a temperature of 90 ° C. To this temperature, gas and combustion air are heated (by condensing the vapor mixture). At the expense of drying and heating, a saving of 115 m3 / h of natural gas (22%) is obtained. For comparison, when heated without drying to 90 ° C, the economy is 64 m / h (12.8%).

Claims (1)

Invention Formula A method of preparing a moist blast furnace gas for combustion, including its heating in a surface heat exchanger using an intermediate heat carrier, characterized in that, in order to increase its further use, the blast gas is pre-cooled with an intermediate heat carrier to a temperature below the dew point, and then dried by separating and removing droplet moisture from the stream. Flue gases To Cowper /  V From cowper i /  / Blast furnace gas FIG G Phage 2.