초록 ▼

A direct reduction process for producing direct reduced iron (DRI) in a reduction reactor having a reduction zone for reducing iron-oxides-containing particles, such as iron ore pellets, to DRI by reaction of said iron oxides with a high temperature reducing gas, and a cooling zone for lowering the

A direct reduction process for producing direct reduced iron (DRI) in a reduction reactor having a reduction zone for reducing iron-oxides-containing particles, such as iron ore pellets, to DRI by reaction of said iron oxides with a high temperature reducing gas, and a cooling zone for lowering the temperature of the DRI produced in said reduction zone, wherein a stream of cooling gas, usually natural gas, is circulated through said cooling zone, a portion of said cooling gas is withdrawn from the cooling zone, cooled and cleaned in a gas cooler and a portion of the cooled gas is recycled to said reduction zone by means of an ejector utilizing the high-pressure natural gas make-up feed as the ejector's motive fluid. Using an ejector for recycling the cooling gas instead of using a mechanical compressor provides significant savings in electricity and in capital, operational and maintenance costs. A direct reduction plant having a DRI cooling zone which uses at least one ejector in recycling at least a portion of cooling gas to the cooling zone.

대표청구항 ▼

What is claimed is: 1. An apparatus for producing DRI comprising a reduction reactor having a reduction zone in its upper part and a cooling zone in its lower part; means for charging iron-oxide-containing particles to said reduction zone, a reducing gas recycle loop including as elements thereof

What is claimed is: 1. An apparatus for producing DRI comprising a reduction reactor having a reduction zone in its upper part and a cooling zone in its lower part; means for charging iron-oxide-containing particles to said reduction zone, a reducing gas recycle loop including as elements thereof said reducing zone, means for circulating a high-temperature reducing gas comprising H2 and CO through said reduction zone to reduce iron oxide particles therein to produce hot DRI and a depleted residual reducing gas with H2O and CO2 by-products, a cooler scrubber for removing H2O from the residual reducing gas, a CO2 removal system for removing CO2 from the residual reducing gas for yielding an upgraded recycle reducing gas, a heater for the upgraded recycle reducing gas, a source of free-oxygen-containing gas for feeding to said upgraded recycle reducing gas to further raise the temperature of such recycle gas and to react at least with hydrocarbons present in the recycle gas, and piping to join these cooling gas recycle loop elements; a cooling gas recycle loop including as elements thereof said cooling zone for cooling down said hot DRI, a cooler scrubber for cooling gas effluent piped from the cooling zone along said loop, one or more ejectors connected into said cooling gas recycle loop capable of functioning as the sole means for driving cooling gas through the cooling gas recycle loop and for mixing the motive gas with the cooled and scrubbed cooling gas upon being recycled to back to said cooling zone, a high-pressure natural gas supply from outside merchant source piped to each such ejector so as to serve as the motive gas for each such ejector, and piping to join these cooling gas recycle loop elements; and means for discharging cooled DRI from said cooling zone. 2. An apparatus according to claim 1, wherein at least one ejector and a compressor are arranged in parallel, with the compressor and any ejector being capable to be used exclusive of the compressor in the recycling of the cooling gas. 3. An apparatus according to claim 1, further comprising a plurality of ejectors with each ejector being appropriately connected to said source of said motive fluid. 4. An apparatus according to claim 3, wherein said ejectors are a pair arranged in parallel. 5. An apparatus according to claim 4, wherein said ejectors have different flow rate capacities. 6. An apparatus according to claim 4, wherein said ejectors are valved to enable the ejectors to be operated simultaneously or alternatively. 7. An apparatus according to claim 1, comprising only a single ejector in the cooling loop. 8. The process of claim 7, wherein said recycling of cooling gas is wholly by means of a plurality of ejectors arranged in parallel. 9. The process of claim 8, wherein said ejectors are a pair operating simultaneously. 10. The process of claim 8, wherein the recycling of cooling gas is performed by one of a pair of ejectors while the other ejector is on stand-by. 11. The process of claim 8, wherein the recycling of cooling gas is performed by a plurality of ejectors having different flow rate capacities. 12. In a process of reducing iron oxide-containing particles in a moving bed reduction reactor with a reducing gas formed therein from make-up gases mainly composed of gaseous hydrocarbon and H2O to produce direct reduced iron, DRI, said reactor having an upper reduction zone and a lower cooling zone, a reducing gas recycle loop including said reduction zone and a cooling gas recycle loop including said cooling zone, which process comprises: feeding into the reduction zone iron oxide-containing particles, feeding into said reduction zone a hot enhanced recycle reducing gas and make-up gases largely comprised of H2, CO, gaseous hydrocarbon, and H2O, causing said gases to flow through the portion of the moving bed in the reduction zone to effect reduction of such particles therein and to effect reformation of gaseous hydrocarbon with H2O and any CO2 therein to yield a resulting depleted residual reducing gas, said H2 and CO being mainly derived by said reformation within said reactor, withdrawing the depleted residual reducing gas from said reduction zone for conditioning and recycling, depleting the H2O and CO2 reduction reaction by-products from the depleted residual reducing gas to yield a resulting upgraded recycle reducing gas, re-heating the upgraded recycle reducing gas in a heater to above about 850° C., feeding make-up gases substantially comprised of gaseous hydrocarbon and H2O to said upgraded recycle reducing gas in said loop, feeding free-O2-containing gas to said re-heated upgraded recycle reducing gas to further raise the temperature of such recycle gas to above about 1000° C. by partial combustion of at least the gaseous hydrocarbon to yield the hot enhanced recycle reducing gas used to feed the reduction zone and thereby complete the reducing gas recycle loop, flowing still-hot DRI from the reduction zone down into said cooling zone, circulating a cooling gas in said cooling gas recycle loop including through said cooling zone to cool-down said DRI, withdrawing from said cooling zone for recycling along said cooling loop at least a portion of said cooling gas warmed up after having cooled said DRI, cooling and scrubbing said withdrawn portion, mixing such withdrawn portion with a compatible pressurized make-up cooling gas, and thereafter recycling along the cooling gas including the make-up cooling gas back into said cooling zone thereby completing the cooling gas recycle loop, and discharging the cooled DRI from said cooling zone; the improvement comprising the recycling of the cooling gas in said cooling gas recycle loop is wholly by means of one or more ejectors driven by the stream of cooling gas make up in the form of high pressure merchant-supplied natural gas as the motive power for each such ejector.