JPS6327395B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention utilizes sensible heat possessed by slag to produce carbonaceous materials and gasification reactants such as CO ₂ and water vapor in the process of solidifying molten slag to produce ballast. The present invention relates to a method for recovering sensible heat from slag to obtain flammable gas by reacting the same, and an apparatus therefor.

For example, blast furnace slag discharged from a blast furnace is approximately
Although the temperature is as high as 1,500°C and it has a large amount of heat, this sensible heat of slag is difficult to handle due to changes in slag properties, and currently it is not actually recovered.

The present invention has been made for the purpose of effectively recovering sensible heat from slag that possesses such a large amount of sensible heat.

Many proposals have been proposed regarding sensible heat recovery from slag. However, most of them are recovered either in a molten state or after being solidified, and most of them are generated in the form of steam or power generation using a steam turbine. Even if it were to be recovered as gasification energy, it would be limited to molten slag and the sensible heat recovery efficiency would not be high.

The present invention skillfully solves these drawbacks by comprehensively recovering the sensible heat of slag melting, solidification heat, and sensible heat after solidification as gasification energy.

The present invention will be explained in detail below.

The first stage of the slag sensible heat recovery system of the present invention utilizes the sensible heat of the molten slag to cause a carbonaceous material such as pulverized coal to react with a gasification reactant such as CO ₂ or water vapor, This is the step of controlling the reaction and controlling the temperature of the molten slag by obtaining combustible gas and controlling the amount of gasification reactant blown into the molten slag.

In the second stage, the molten slag whose temperature was controlled in the first stage is caused to flow down in a laminar flow onto a drum rotating at a predetermined speed, and is solidified on the outer peripheral surface of the rotating drum. Then, hot water, for example, is injected as a heat medium onto the inner peripheral surface of the rotating drum, and heat is removed from the slag via the drum. During this process, at least a portion of the heat transfer medium becomes vapor and is recovered. In this way, the molten slag is solidified and the sensible heat retained in the molten slag is recovered in the form of vaporization of the heat medium.

The third stage is a stage in which the carbonaceous material is reacted with CO ₂ and water vapor (H ₂ O) using the sensible heat possessed by the solidified high-temperature ballast to obtain a flammable gas. That is, in the second stage, the high-temperature ballast that has solidified into a thermal ballast is supplied to the packed bed of the thermal ballast sensible heat recovery tank, and a heat carrier gas with a high partial pressure of H ₂ O is blown into the packed bed from the bottom of the packed bed. This heat carrier gas with a high partial pressure of H ₂ O is reacted with the carbonaceous material in the carbonaceous material fluidized bed at the top of the thermal ballast sensible heat recovery tank to produce water gas. It's something you get.

The ballast whose sensible heat has been recovered as described above is cut out from the bottom of the packed bed and discharged.

The present invention will be explained below with reference to the drawings.

FIG. 1 shows the overall flow of the present invention, and FIG. 2 is a partially enlarged view.

Molten slag discharged from blast furnaces etc. is slag pot 1
It is injected into the reaction tank 2 at a constant flow rate. The reaction tank 2 is a closed storage tank having a slag receiving port 3 at the front and an outflow gutter 4 at the rear, and the slag flowing in from 3 is discharged from 4 after staying for a certain period of time. Hopper 5 to sealed reaction tank 2
For example, fine coke is supplied in an amount greater than the reaction amount by the feeder 6, and at the same time, a gasification reactant (steam) is blown in from the blowing nozzle 7 to stir the slag in the reaction tank 2 and bring it into contact with the carbon source for gasification. To carry out the reaction, the coke is brought into contact with steam at high temperature to carry out the following water gas reaction.

C+ _H2O =CO+ _H2-31900Kcal /K-mo Sensible heat of the slag is used as a heat source for this reaction, and the slag temperature decreases as the reaction progresses. As the temperature decreases, the slag becomes more viscous, its fluidity deteriorates, and it becomes impossible to discharge it from the reaction tank 2.

On the other hand, the properties of the supplied slag depend on the blast furnace operation, and the temperature entering the reaction tank 2 is not constant. However, it is preferable to discharge the discharged slag at a constant temperature in order to stabilize the slag solidification operation in the subsequent process.

The present inventors solved the problem of absorbing such changes on the supply side and maintaining constant properties on the discharge side by arbitrarily suppressing endothermic reactions. That is, while detecting the slag temperature using the temperature detection end 8, the control valve 9 is operated to control the suction amount of the gasification reactant and adjust the reaction. This method made it possible to keep the temperature of the discharged slag constant.

Next, the slag flowing out from the outflow gutter 4 temporarily stays on the straightening roll 10, becomes a laminar flow by passing through the roll gap, and flows down to the rotating drum 11. The drum 11 has a spray nozzle 12 for strongly cooling the inner surface, and hot water, for example, is sprayed from the nozzle. The inside of the drum 11 has a high-pressure sealed structure, and the injected hot water is passed from the inside of the drum to the piping 13.
It flows into the accumulator 14 through the pump 1.
It is pressurized at step 5 and injected again at step 12. The slag that has flowed down onto the drum 11 coagulates and solidifies on the drum surface. The heat of solidification is transferred to the hot water injected inside through the drum surface. The solidified slag (hereinafter referred to as thermal ballast) is cut into pieces with a predetermined particle size by a cutter roll 16, and introduced into the packed bed section 18 via a scrubber chute 17. Inert cold gas is blown into the packed bed from the lower layer by a blower 19, and heat is exchanged with the thermal ballast through solid-gas contact to produce hot gas. Further, the sensible heat recovered in the slag solidification section is blown into the packed bed as steam from the accumulator 14 via the pressure reduction control valve 20, mixed with hot gas, and superheated. After the heat exchange has been completed, the cooled ballast is discharged from the system through the lower feeder 21 of the packed tower. Coke powder is supplied to the uppermost multistage fluidized bed 22 from a coke powder hopper 23.
The coke breeze then passes through the overflow pipes 24 of each stage and sequentially moves to the lower stages. The hot gas rises to about 1000° C., fluidizes coke breeze as a fluidized bed carrier gas, and performs a water gas reaction using sensible heat as a reaction heat source. The gas after the reaction is sequentially used as a fluidization source in the upper fluidized bed and exchanges heat with coke breeze to release sensible heat. From the top, it passes through a cyclone 25 to separate dust in the gas, and a part of the gas is sent to the pipe 2.
6 and recycled, and the rest is recovered as produced gas. On the other hand, the coke powder that has completed the reaction falls as a residue from the lowest stage of the fluidized bed to the packed bed section, and is discharged from the system together with the ballast.

The gas produced by reaction in the reaction tank 2 is introduced into the steam generator 27, where sensible heat of the gas is released to generate water vapor, which is mixed with the gas produced in the fluidized bed and collected.

Example 1 The slag processing amount was 10 t/H, BFG was used as the source gas, H ₂ O was added to make the composition 10%, and sensible heat recovery was performed without circulation. The results are shown below.

Slag temperature in reaction tank 1425℃ 〃 Steam injection amount 57Kg/Hr 〃 Coke powder input amount Large amount 〃 Gas generation amount 130Nm ³ /Hr Steam generation amount in coagulation section
760Kg/Hr (P=3Kg/cm ² ) Packed bed section BFG injection amount 5450Nm ³ /Hr BFG composition (after steam addition) (%) CO ₂ CO H ₂ N ₂ H ₂ O 19 18.7 3.1 49.2 10.0 Fluidized bed section inlet Gas composition Same as above 〃 Inlet gas temperature 1015℃ 〃 Coke powder input amount Large 〃 Outlet gas amount 5760Nm ³ /Hr 〃 Outlet gas composition (%) CO ₂ CO H ₂ N ₂ H ₂ O Others 17.0 23.5 8.3 46.5 4.7 BFG increase Cal Amount: 319Kcal/Nm Increased amount of ³ gas: 580Nm/Hr, atDryBase Example 2 Heat is supplied using the same equipment at a slag processing rate of 10t/Hr to maintain a constant amount of gas generated in the fluidized reaction bed, and the gas is recirculated as a carrier gas. in the gas by adding ₂ O
The results of the reaction conducted while keeping the H ₂ O concentration at 20% are shown below.

Fluidized bed inlet gas temperature 1040℃ 〃 Circulating gas amount 5200Nm ³ /Hr 〃 Outlet gas amount 5500Nm ³ /Hr 〃 Outlet gas composition (%) CO H ₂ H ₂ O Others 43.2 43.2 15.6 Increased amount of gas 590Nm ³ /Hr

[Brief explanation of the drawing]

FIG. 1 is an overall flowchart of the present invention, FIG. 2 is a diagram showing the relationship between slag temperature and viscosity, and FIG. 3 is a flow diagram of temperature control in a reaction tank. The codes and names are as follows: 1... Molten slag pot;
2... Reaction tank, 3... Slag receiving port, 4... Outflow gutter, 5
...Hopper, 6...Cut-out feeder, 7...
Steam blowing nozzle, 8... Temperature detection end, 9... Gasifying agent control valve, 10... Rectifying roll, 11... Rotating drum, 12... Heat medium injection nozzle, 13...
Heat medium piping, 14... Accumulator, 15...
...Heat medium circulation pump, 16...Cutter roll,
17... Scrubber shoot, 18... Packed bed section, 19... Circulation blower, 20... Pressure reduction control valve, 21... Packed column lower feeder, 22...
Multi-stage fluidized bed, 23... Coke powder hopper, 24
... Overflow pipe, 25 ... Cyclone, 26 ... Gas piping, 27 ... Steam generator, 28 ... General steam, 29 ... Make-up water.

Claims (1)

[Scope of Claims] 1. In the process of solidifying molten slag to obtain a ballast, one or both of a carbonaceous material and a gasification reactant are brought into contact with the high-temperature molten slag or ballast to generate flammable gas. A method for recovering sensible heat from slag. 2. Introducing molten slag into a reaction tank, charging a carbonaceous material into the reaction tank, blowing a gasification reactant into it to produce a flammable gas, and changing the amount of gasification reactant blown into the reaction tank. A method for recovering sensible heat from slag, characterized by controlling the temperature of molten slag. 3. Introducing molten slag into a reaction tank, charging carbonaceous material into the reaction tank, blowing a gasification reactant to produce flammable gas, and varying the amount of gasification reactant blown into the reaction tank. to control the temperature of the molten slag, and then to flow the molten slag in a laminar flow onto a rotating drum, while applying a heating medium to the inner surface of said rotating drum to solidify the molten slag and at the same time to make the molten slag visible. A method for recovering sensible heat from slag, which is characterized by transferring heat to a heat medium. 4. Introducing molten slag into a reaction tank, charging a carbonaceous material into the reaction tank, blowing a gasification reactant to produce flammable gas, and varying the amount of gasification reactant blown into the reaction tank. The temperature of the molten slag is controlled by the molten slag, and the molten slag is then flowed onto a rotating drum in a laminar flow and solidified, and at the same time is formed into an appropriate size.The forming heat ballast is continuously introduced into the packed bed, and the bottom part of the packed bed is The slag is brought into contact with a heat carrier gas and water vapor blown into the slag, and heated through heat exchange to obtain a hot gas with a high partial pressure of water vapor, which is then reacted with a carbonaceous material to produce a flammable gas. Sensible heat recovery method. 5. A reaction tank that receives and stores molten slag and allows it to overflow from the other end at a predetermined temperature, a carbonaceous material supply tool that supplies carbonaceous material into the reaction tank, CO ₂ ,
A molten slag temperature control and sensible heat recovery device consisting of a gasification reactant blower that blows a gasification reactant such as H ₂ O into the molten slag in the reaction tank, A rotating drum that receives and injects a heating medium onto its inner peripheral surface, a conduit that introduces the heating medium received by the rotating drum and generated steam into the accumulator, and a cutting device that cuts the slag solidified on the outer peripheral surface of the rotating drum into appropriate sizes. A device for turning molten slag into a heat ballast, consisting of a vessel and a conveyor for supplying the cutting heat ballast to the next process, a multi-stage carbonaceous material fluidized bed on the top, a heat ballast packed bed on the bottom, and a heat ballast cutter on the bottom. a heat balance sensible heat recovery tank having an outlet;
A thermal balance sensible heat recovery device consisting of a feeder that supplies carbonaceous material to a carbonaceous fluidized bed, and a feeder that supplies heat carrier gas and gasification reactants such as CO ₂ and steam from below the packed bed. A slag sensible heat recovery device consisting of a three-stage device.