WO2013150498A2 - Method and apparatus for dry filtering process gas - Google Patents

Method and apparatus for dry filtering process gas Download PDF

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Publication number
WO2013150498A2
WO2013150498A2 PCT/IB2013/052740 IB2013052740W WO2013150498A2 WO 2013150498 A2 WO2013150498 A2 WO 2013150498A2 IB 2013052740 W IB2013052740 W IB 2013052740W WO 2013150498 A2 WO2013150498 A2 WO 2013150498A2
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WO
WIPO (PCT)
Prior art keywords
chamber
filtering
gas
cooling
collection hopper
Prior art date
Application number
PCT/IB2013/052740
Other languages
French (fr)
Other versions
WO2013150498A3 (en
Inventor
Petrus Johannes JONKER
Original Assignee
Tenova Pyromet (Proprietary) Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Tenova Pyromet (Proprietary) Limited filed Critical Tenova Pyromet (Proprietary) Limited
Priority to CN201380029596.1A priority Critical patent/CN104349830B/en
Priority to KR1020147031140A priority patent/KR102066401B1/en
Priority to EA201401100A priority patent/EA201401100A1/en
Publication of WO2013150498A2 publication Critical patent/WO2013150498A2/en
Publication of WO2013150498A3 publication Critical patent/WO2013150498A3/en
Priority to ZA2014/08088A priority patent/ZA201408088B/en

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D46/00—Filters or filtering processes specially modified for separating dispersed particles from gases or vapours
    • B01D46/24—Particle separators, e.g. dust precipitators, using rigid hollow filter bodies
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D46/00—Filters or filtering processes specially modified for separating dispersed particles from gases or vapours
    • B01D46/42—Auxiliary equipment or operation thereof
    • B01D46/48—Removing dust other than cleaning filters, e.g. by using collecting trays
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D46/00—Filters or filtering processes specially modified for separating dispersed particles from gases or vapours
    • B01D46/42—Auxiliary equipment or operation thereof
    • B01D46/4272—Special valve constructions adapted to filters or filter elements
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D46/00—Filters or filtering processes specially modified for separating dispersed particles from gases or vapours
    • B01D46/42—Auxiliary equipment or operation thereof
    • B01D46/44—Auxiliary equipment or operation thereof controlling filtration
    • B01D46/446—Auxiliary equipment or operation thereof controlling filtration by pressure measuring
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D46/00—Filters or filtering processes specially modified for separating dispersed particles from gases or vapours
    • B01D46/66—Regeneration of the filtering material or filter elements inside the filter
    • B01D46/70—Regeneration of the filtering material or filter elements inside the filter by acting counter-currently on the filtering surface, e.g. by flushing on the non-cake side of the filter
    • B01D46/71—Regeneration of the filtering material or filter elements inside the filter by acting counter-currently on the filtering surface, e.g. by flushing on the non-cake side of the filter with pressurised gas, e.g. pulsed air
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D46/00—Filters or filtering processes specially modified for separating dispersed particles from gases or vapours
    • B01D46/66—Regeneration of the filtering material or filter elements inside the filter
    • B01D46/79—Regeneration of the filtering material or filter elements inside the filter by liquid process

Definitions

  • This invention relates to a system for dry filtering process gas.
  • this invention relates to a method and apparatus for the cooling down and dry filtering of process gas created in a ferroalloy smelting process.
  • the process gas produced thereby is generally flared, i.e. burnt off safely, or further processed as a heating medium or used in power generation system, for example.
  • the process gas is mainly carbon monoxide gas and contains solids which must be removed from the gas before it can be used in further processing applications. In some applications it is also required that the process gas be cooled down first before being useable.
  • a known method of cleaning process gas is to use a wet scrubber such as a venturi scrubber or a disintegrator where solids are removed from the gas through contact with water injected into the gas stream inside the venturi of the venturi scrubber or the rotor of the disintegrator.
  • a wet scrubber such as a venturi scrubber or a disintegrator where solids are removed from the gas through contact with water injected into the gas stream inside the venturi of the venturi scrubber or the rotor of the disintegrator.
  • the resultant process gas is a saturated gas with a solids content varying between 10 to 100 mg/Nm3. This is not sufficient when the cleaned gas is to be used in certain applications such as in internal combustion engines, for example.
  • a known system of filtering process gas is described in the specification of international patent application PCT/FI2007/000295, published under WO2008/074912.
  • the system of WO2008/074912 is a wet system in that water is introduced into the filtering chamber to facilitate the removal of the solids which have been removed from the process gas. The slurry mixture is then dispensed through the bottom of the filtering chamber under gravity.
  • the introduction of water into the filtering chamber is not ideal as it increases the water content of the filtered gas exiting the filtering apparatus.
  • a dry filtering apparatus for the dry filtering of process gas produced in a ferroalloy smelting process, the apparatus including:
  • a process gas inlet for feeding the process gas into the filtering chamber, the inlet being positioned so that the process gas is filtered through the filtering element
  • a cleaning gas inlet for feeding a cleaning gas into the filtering chamber, the cleaning gas inlet being directed at the filtering element so that, in use, the cleaning gas is blown through the filtering element in order to dislodge solids caught in the filtering element;
  • a discharge chamber positioned below the filtering chamber, in which the dry solids that have been removed from the process gas are collected;
  • a collection hopper located below the discharge chamber, in which the solids are collected before being discharged into a conveying system which transports the solids away from the filtering apparatus.
  • the filtering apparatus may include an equalisation conduit running between the filtering chamber and the collection hopper, the equalisation conduit having a sealing element therein for controlling gas flow between the filtering chamber and the collection hopper in order to control the pressure difference between the filtering chamber and collection hopper.
  • the filtering apparatus includes two sealing elements, the first being located between the discharge chamber and the collection hopper and the second between the collection hopper and the conveying system, wherein the first sealing element is operable to control the flow of solids between the discharge chamber and the collection hopper and the second sealing element is operable to control the discharge of solids from the collection hopper to the conveying system.
  • the filtering apparatus may include a gas supply line for feeding a pressurising gas into the collection hopper, the gas supply line having a sealing element for controlling the supply of pressurising gas to the collection hopper.
  • the filtering apparatus may include a vent line for venting gas from the collection hopper, the vent line having a sealing element for controlling the venting of gas from the collection hopper.
  • a cooling apparatus for cooling process gas produced in a ferroalloy smelting process including:
  • a cooling medium feed line for feeding a cooling medium into the cooling chamber
  • a collection chamber positioned below the cooling chamber, in which settled solids are collected
  • a collection hopper located below the collection chamber, in which the settled solids are collected before being discharged into a conveying system which transports the solids away from the cooling apparatus.
  • the cooling apparatus preferably includes an equalisation conduit running between the cooling chamber and the collection hopper, the equalisation conduit having a sealing element for controlling gas flow between the cooling chamber and the collection hopper in order to control the pressure difference between the cooling chamber and the collection hopper.
  • the cooling apparatus may include two sealing elements, the first being located between the collection chamber and the collection hopper and the second between the collection hopper and the conveying system, wherein the first sealing element is operable to control the flow of solids from the collection chamber and the collection hopper and the second sealing element is operable to control the discharge of solids from the collection hopper to the conveying system.
  • the cooling apparatus may also include a gas supply line for feeding pressurising gas into the collection hopper, the gas supply line having a sealing element for controlling the supply of pressurising gas to the collection hopper.
  • the cooling apparatus may include a vent line for venting gas from the collection hopper, the vent line having a sealing element for controlling the venting of gas from the collection hopper.
  • the cooling apparatus may include a cooling medium injector located in the cooling medium feed line for injecting cooling medium into the cooling chamber.
  • the cooling apparatus may further include an atomising feed line for feeding an atomising agent into the cooling chamber.
  • the atomising agent may be introduced into the cooling medium line at a location prior to the cooling medium injector.
  • the cooling chamber includes two sub-chambers which are in fluid connection by means of a series of pipes running between the sub-chambers, and wherein the process gas is fed into one of the sub-chambers while the cooled process gas is discharged from the other sub-chamber.
  • the cooling medium supplied to the cooling chamber may flow across the outer surface of the pipes connecting the sub-chambers to one another, thereby cooling down the process gas in the pipes.
  • the cooling chamber and the collection chamber form a single unit.
  • the cooling medium is preferably water.
  • a system for the cooling and dry filtering of process gas produced in a ferroalloy smelting process including a filtering apparatus according the first aspect of the invention and a cooling apparatus according to a second aspect of the invention, wherein the process gas outlet of the cooling apparatus is in fluid communication with the process gas inlet of the filtering apparatus so that the process gas entering the filtering apparatus is cooled down in the cooling apparatus prior to being introduced into the filtering apparatus.
  • a method of dry filtering process gas produced in a ferroalloy smelting process including the steps of:
  • the step of discharging the solids into the collection hopper may include the steps of:
  • pressurising the collection hopper by opening a sealing element in a gas supply line which feeds pressuring gas to the collection hopper; and opening a sealing element between the collection hopper and a conveying system in order to discharge to solids from the collection hopper.
  • the method may further include the steps of:
  • the method may be used to filter process gas produced in a ferroalloy smelting process in which high volatile reductants are used.
  • Figure 1 shows a diagrammatic illustration of a first embodiment of a system for cooling and filtering process gas produced in a ferroalloy smelting process according to the invention
  • Figure 1 shows a diagrammatic illustration of a second embodiment of a system for cooling and filtering process gas produced in a ferroalloy smelting process according to the invention.
  • the system 10 for cooling and filtering process gas, mainly carbon monoxide gas, produced in a ferroalloy smelting process according to the invention is shown in Figure 1.
  • the system 10 includes a dry filtering apparatus for removing contaminants, typically solids, from the process gas.
  • the filtering apparatus is generally indicated by the reference numeral 20.
  • dry filtering is used to describe a filtering process in which solids are removed from the process gas without the use of a liquid in the filtering chamber.
  • the filtering apparatus 20 includes a filtering chamber 22 in which at least one filtering element 24 is located.
  • the number of filtering elements 24 installed in the filtering chamber 22 depends on the process gas volumes to be cleaned. It is envisaged that due to the large volumes of process gas produced in the ferroalloy smelting process it may be advantageous to install multiple filtering elements 24.
  • Each element 24 is made of porous material, typically metal or any similar material such as a ceramic material, for example.
  • the process gas which enters the filtering chamber 22 through an inlet of a process gas feed line 26, is filtered through the filtering element 24 to remove the solids present therein.
  • the filtered gas is discharged from the filtering chamber 22 through an outlet of a process gas discharge line 28.
  • the filtering element 24 is positioned between the process gas inlet and the outlet, thereby ensuring that the process gas is filtered through the filtering element before being discharged through the line 28.
  • the filtering element covers the entire or at least a major portion of the cross-sectional area of the filtering chamber 22 to ensure that the gas flow stream passes through the filtering element when moving from the inlet to the outlet.
  • the filtering element 24 may clog up as a result of the solids present in the process gas entering the filtering chamber 22.
  • the cleaning gas which is either an inert gas, such as nitrogen, or filtered process gas, is supplied to the filtering chamber 22 by means of a supply line 30 and fed into the chamber through an inlet nozzle 32.
  • a sealing element 33 is located in the supply line and operable to control the flow of cleaning gas by opening and closing off the supply line.
  • the cleaning gas inlet nozzle 32 is positioned so that the stream of cleaning gas is directed at the filtering element. In the preferred embodiment the inlet nozzle 32 is located above the filtering element 24 and blows the gas through the filtering element in a generally downward direction.
  • sealing element is used to describe a device capable of controlling the flow of fluid by opening and closing the fluid flow path, and could be in the form of a valve, for example.
  • the opening and closing of the sealing element 33, and therefore the flow of cleaning gas into the filtering chamber 22, is controlled by a control unit (not shown in the accompanying drawing). Instead of supplying a constant stream of cleaning gas the control unit opens and closes the sealing element periodically in order to control the duration and frequency of the blasts of cleaning gas.
  • the solids that are removed from the process gas are collected in a discharge chamber 34 which is positioned below the filtering chamber 22. In this configuration the solids move from the filtering chamber 22 into the discharge chamber under gravity.
  • the filtering chamber 22 and the discharge chamber 34 form part of a single unit or chamber 36 with the top portion thereof being the filtering chamber and the bottom portion the discharge chamber. It is envisaged that the chamber 36 could be circular, square or rectangular when viewed in cross-section.
  • the solids that have been removed from the process gas are discharged into a collection hopper 38 where they are collected before being discharged into a conveying system 40 which transports the solids away from the filtering apparatus 10 to a location where they are typically stored in containers.
  • the hopper 38 is positioned below the discharge chamber 34 so that the solids move from the chamber to the hopper under gravity.
  • the conveying system 40 is positioned below the hopper for the same reason.
  • a sealing element 42 is provided between the discharge chamber and hopper.
  • a sealing element 44 is located between the hopper 38 and the conveying system 40 for controlling the flow of solids from the hopper to the conveying system.
  • the filtering apparatus 20 further includes a pressure equalisation conduit 46, running between the discharge chamber 34 and the hopper 38, which is used to control the pressure difference between the discharge chamber 34 and the hopper 38.
  • a sealing element 48 is located in the equalisation conduit. It must accordingly be clear that when the sealing element 48 is open the conduit 46 allows the pressures inside the chamber 34 and hopper 38 to equalise.
  • a gas supply line 50 is configured to supply a pressurising gas, which is typically an inert gas such as nitrogen, to the hopper 38, thereby allowing the pressure inside the hopper to be increased above that of the discharge chamber 34.
  • a sealing element 52 is located in the supply line 50 to control the flow of pressurising gas to the hopper.
  • the supply line 50 is connected to the hopper 38.
  • the pressure inside the hopper 38 may be increased by supplying pressurising gas to the hopper while the sealing element 48 in the equalisation line is closed.
  • the supply line 50 may be connected to the equalisation line 46 at a position between the hopper 38 and sealing element 48.
  • the hopper 38 also has an outlet in a vent line 54 for venting gas to reduce the internal pressure inside the hopper.
  • a sealing element 56 controls the flow of gas inside the vent line 54. In other words, the sealing element 56 controls the venting of gas from the hopper 38.
  • the process gas containing the unwanted solids is fed into the filtering chamber 22 through the inlet of line 26 whereafter it is filtered through the filtering element 24 which removes the solids present in the process gas.
  • the filtering element 24 in which the solids are caught is then cleaned in order to remove the solids. This is done by blowing the cleaning gas, which is supplied through the line 30, through the filtering element, thereby dislodging the solids in order to prevent it from clogging up.
  • the solids that have been removed from the process gas are then collected in the discharge chamber 34 while the sealing element 42 is closed in order to prevent the solids from being discharged into the collection hopper 38.
  • the sealing element 48 in the equalisation conduit 46 is opened to equalise the pressure in the hopper 38 and the discharge chamber 34.
  • the sealing element 42 between the discharge chamber 34 and hopper 38 is opened to allow the discharge of solids into the hopper.
  • the sealing element 48 in the equalisation conduit 46 and the sealing element 42 between the discharge chamber and hopper are closed following a time delay or other trigger mechanism.
  • the sealing element 52 in the gas supply line 50 is opened so that the pressurising gas flows into the hopper while the vent sealing element 56 is closed.
  • the sealing element 56 in the vent line 54 Upon confirmation of a high internal pressure inside the hopper 38 the sealing element 56 in the vent line 54 is opened to vent the gas. After a time delay the sealing element 56 in the vent line 54 is closed and upon confirmation of the internal pressure inside the hopper 38 reaching a predetermined pressure the supply of pressurising gas is cut off by closing the sealing element 52 in the supply line 50. On confirmation of the closure of the sealing element 52 the sealing element 44 between the hopper 38 and a conveying system 40 is opened in order to discharge the solids onto the conveying system to be transported away from the filtering apparatus 20.
  • the sealing element 44 between the hopper and conveying system 40 is closed and the hopper is again pressurised though the pressurising line 50 by opening the sealing element 52 following confirmation of the closure of the sealing element 44.
  • the system 10 of Figure 1 includes a cooling apparatus, which is indicated by numeral 60.
  • the process gas produced by the smelting process is delivered to a cooling chamber 62 through a line 64 connecting the smelting process to the cooling apparatus 60.
  • the line 64 terminates in a gas inlet which feeds the process gas into the cooling chamber 62.
  • a cooling medium typically in the form of a liquid such as water, is fed into the cooling chamber 62 to reduce the temperature of the process gas by means of an injector 66.
  • the design of the injector is such that the cooling medium is fed into the cooling chamber 62 as a fine spray so that the gas is cooled down through evaporation of the atomised cooling medium inside the cooling chamber.
  • an atomising agent is introduced into the cooling medium prior to it being dispensed into the cooling chamber 62 through the injector 66.
  • a pressurised cooling medium supply line 68 feeds the injector 66 and an atomising line 70 connects to the line 68 at a position upstream of the injector 66.
  • the cooling chamber 62 and the collection chamber 74 form part of a single unit or chamber 76 with the top portion thereof being the cooling chamber and the bottom portion the collection chamber. It is envisaged that the chamber 76 could be circular when viewed in cross-section.
  • the cooling apparatus 60 further includes two sealing elements 82 and 84, which are located between the collection chamber 74 and hopper 78 and the hopper and conveying system 80 respectively. The sealing elements 82 and 84 control the flow of settled solids into and out of the hopper 78.
  • the internal pressures inside the collection chamber 74 and the hopper 78 are controlled in a similar manner as in the filtering apparatus 20 in that the cooling apparatus 60 includes a pressure equalisation conduit 86 running between the collection chamber 74 and the hopper 78. To enable the hopper 78 to be closed off from the collection chamber 74, a sealing element 88 is located in the equalisation conduit.
  • a gas supply line 90 is configured to supply a pressurising gas, which is typically an inert gas such as nitrogen, to the hopper 78, thereby allowing the pressure inside the hopper to be increased above that of the collection chamber 74.
  • a sealing element 92 is located in the supply line 90 to control the flow of pressurising gas to the hopper 78.
  • the supply line 90 is connected to the hopper 78. In this configuration, the pressure inside the hopper 78 may be increased by supplying pressurising gas to the hopper while the sealing element 88 in the equalisation line is closed.
  • the supply line 90 may be connected to the equalisation line 86 at a position between the hopper 78 and sealing element 88.
  • the hopper 78 also has a vent line 94 for venting gas to reduce the internal pressure inside the hopper with a sealing element 96 again controlling the flow of gas inside the vent line 94.
  • Figure 2 shows a second embodiment of the system for cooling and filtering process gas in accordance with the invention.
  • the system of Figure 2 is generally indicated by the reference numeral 100.
  • the system 100 is similar to the system 10 described above as it includes the same filtering apparatus 20 described above with reference to the first embodiment of the system. However, the design of the process gas and cooling medium delivery mechanisms of the cooling apparatus of the second embodiment is different to that of the first embodiment.
  • the cooling apparatus is indicated by the reference numeral 110.
  • the process gas produced by the smelting process is delivered to a cooling chamber 112 through a line 114 connecting the smelting process to the cooling apparatus 110.
  • the line 114 terminates in a gas inlet which feeds the process gas into the cooling chamber 112.
  • a cooling medium typically water or air, is fed through a line 116 into the cooling chamber 112 to reduce the temperature of the process gas and exits the cooling chamber through a line 118.
  • the design of the cooling chamber 112 is such that the process gas is not in direct contact with the cooling medium.
  • the cooling chamber 112 includes two sub-chambers 120.1 and 120.2 which are in fluid connection with one another by means of a series of conduits or pipes 122 through which the process gas is conveyed from one sub-chamber to the other.
  • the process gas is delivered into the first sub-chamber 120.1 , also referred to as the gas inlet chamber, which is located before the second sub-chamber 120.2, also referred to as the gas outlet chamber.
  • the cooling chamber 112 is designed so as to allow the cooling medium to flow over the outer surfaces of the pipes 122, thereby cooling down the process gas being conveyed in the pipes.
  • the configuration of the different fluid flow paths affectively creates a heat exchanger to cool down the process gas before it exits the cooling chamber, in particular the gas outlet chamber 120.2, through an exit line 72.
  • the cooling apparatus 110 is connected to the filtering apparatus 20 so that the process gas exit line of the cooling apparatus forms the process gas inlet tine 26 of the filtering apparatus.
  • the solids which settle are collected in a collection chamber 74 located below the cooling chamber 112.
  • the cooling chamber 12 and the collection chamber 74 form a part of a single unit. It is envisaged that the single unit could be square or rectangular when viewed in cross section.
  • the sold content in the cleaned process gas discharged through the output line 28 of the filtering apparatus 20 is less than 5 mg/Nm 3 .
  • Another advantage of the system 10, 100 according to the invention is that the process gas after filtering is not saturated with moisture as a result of the filtering process being a dry process.
  • the method of controlling the pressure difference between the discharge chamber 34 and the collection hopper 38 allows for the discharging of solids which have been removed from the process gas without the use of a liquid in the filtering chamber 22. For this reason, the arrangement of the gas supply line 50, the equalisation conduit 46 and the vent line 54 plays an important role in producing dry filtered gas using the filtering apparatus 20.
  • the filtered process gas is also suitable for further processing in a de-tarring process without producing water containing either heavy of light tars when using reductants in the ferroalloy smelting process that may result in the process gas containing high levels of hydro carbons.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Waste-Gas Treatment And Other Accessory Devices For Furnaces (AREA)
  • Filtering Of Dispersed Particles In Gases (AREA)
  • Manufacture And Refinement Of Metals (AREA)

Abstract

The invention concerns a system (10, 100) for the cooling down and dry filtering of process gas produced in a ferroalloy smelting process. The system (10, 100) includes an apparatus (20) for the dry filtering of process gas which includes a filtering chamber (22) in which a filtering element (24) is located. Process gas is fed into the filtering chamber through an inlet in a supply line (26) and directed to the filtering element (24). Filtered process gas is discharged through a discharge line (28) after having been filtered through the filtering element (24). The apparatus (20) further includes a cleaning gas inlet (32) for feeding a cleaning gas into the filtering chamber (22) for dislodging solids caught in the filtering element (24). The dislodged solids are collected in a discharge chamber (34) positioned below the filtering chamber (22) before being conveyed to a collection hopper (38) located below the discharge chamber (34). An equalisation conduit (46) running between the filtering chamber (22) and the collection hopper (38) is used to control the pressure difference between the filtering chamber (22) and collection hopper (38) in order to controlling the discharging of the solids.

Description

METHOD AND APPARATUS FOR DRY FILTERING PROCESS GAS
BACKGROUND TO THE INVENTION
This invention relates to a system for dry filtering process gas. In particular, but not exclusively, this invention relates to a method and apparatus for the cooling down and dry filtering of process gas created in a ferroalloy smelting process.
In a metal smelting process such as a ferroalloy smelting process the process gas produced thereby is generally flared, i.e. burnt off safely, or further processed as a heating medium or used in power generation system, for example. In a ferroalloy smelting process the process gas is mainly carbon monoxide gas and contains solids which must be removed from the gas before it can be used in further processing applications. In some applications it is also required that the process gas be cooled down first before being useable. A known method of cleaning process gas is to use a wet scrubber such as a venturi scrubber or a disintegrator where solids are removed from the gas through contact with water injected into the gas stream inside the venturi of the venturi scrubber or the rotor of the disintegrator. When using either one of these devices the resultant process gas is a saturated gas with a solids content varying between 10 to 100 mg/Nm3. This is not sufficient when the cleaned gas is to be used in certain applications such as in internal combustion engines, for example.
A known system of filtering process gas is described in the specification of international patent application PCT/FI2007/000295, published under WO2008/074912. The system of WO2008/074912 is a wet system in that water is introduced into the filtering chamber to facilitate the removal of the solids which have been removed from the process gas. The slurry mixture is then dispensed through the bottom of the filtering chamber under gravity. The introduction of water into the filtering chamber is not ideal as it increases the water content of the filtered gas exiting the filtering apparatus.
Further problems are also experienced when using high volatile reduction agents in the ferroalloy smelting process. For example, the use of high volatile reduction agents results in unwanted water treatment problems as well as equipment maintenance problems.
It is an object of this invention to alleviate at least some of the problems experienced with existing methods and apparatus for filtering process gas.
It is a further object of this invention to provide a system, including a method and apparatus, for filtering process gas that will be a useful alternative to existing systems. SUMMARY OF THE INVENTION
According to a first aspect of the invention there is provided a dry filtering apparatus for the dry filtering of process gas produced in a ferroalloy smelting process, the apparatus including:
a filtering chamber in which a filtering element is located;
a process gas inlet for feeding the process gas into the filtering chamber, the inlet being positioned so that the process gas is filtered through the filtering element;
a process gas outlet for discharging filtered process gas from the filtering chamber;
a cleaning gas inlet for feeding a cleaning gas into the filtering chamber, the cleaning gas inlet being directed at the filtering element so that, in use, the cleaning gas is blown through the filtering element in order to dislodge solids caught in the filtering element;
a discharge chamber, positioned below the filtering chamber, in which the dry solids that have been removed from the process gas are collected; and
a collection hopper, located below the discharge chamber, in which the solids are collected before being discharged into a conveying system which transports the solids away from the filtering apparatus.
The filtering apparatus may include an equalisation conduit running between the filtering chamber and the collection hopper, the equalisation conduit having a sealing element therein for controlling gas flow between the filtering chamber and the collection hopper in order to control the pressure difference between the filtering chamber and collection hopper.
Preferably, the filtering apparatus includes two sealing elements, the first being located between the discharge chamber and the collection hopper and the second between the collection hopper and the conveying system, wherein the first sealing element is operable to control the flow of solids between the discharge chamber and the collection hopper and the second sealing element is operable to control the discharge of solids from the collection hopper to the conveying system.
The filtering apparatus may include a gas supply line for feeding a pressurising gas into the collection hopper, the gas supply line having a sealing element for controlling the supply of pressurising gas to the collection hopper.
The filtering apparatus may include a vent line for venting gas from the collection hopper, the vent line having a sealing element for controlling the venting of gas from the collection hopper.
According to a second aspect of the invention there is provided a cooling apparatus for cooling process gas produced in a ferroalloy smelting process, the apparatus including:
a cooling chamber;
a process gas inlet for feeding the process gas into the cooling chamber;
a cooling medium feed line for feeding a cooling medium into the cooling chamber;
a process gas outlet for discharging cooled process gas;
a collection chamber, positioned below the cooling chamber, in which settled solids are collected; and
a collection hopper, located below the collection chamber, in which the settled solids are collected before being discharged into a conveying system which transports the solids away from the cooling apparatus.
The cooling apparatus preferably includes an equalisation conduit running between the cooling chamber and the collection hopper, the equalisation conduit having a sealing element for controlling gas flow between the cooling chamber and the collection hopper in order to control the pressure difference between the cooling chamber and the collection hopper. The cooling apparatus may include two sealing elements, the first being located between the collection chamber and the collection hopper and the second between the collection hopper and the conveying system, wherein the first sealing element is operable to control the flow of solids from the collection chamber and the collection hopper and the second sealing element is operable to control the discharge of solids from the collection hopper to the conveying system.
The cooling apparatus may also include a gas supply line for feeding pressurising gas into the collection hopper, the gas supply line having a sealing element for controlling the supply of pressurising gas to the collection hopper.
The cooling apparatus may include a vent line for venting gas from the collection hopper, the vent line having a sealing element for controlling the venting of gas from the collection hopper.
The cooling apparatus may include a cooling medium injector located in the cooling medium feed line for injecting cooling medium into the cooling chamber.
The cooling apparatus may further include an atomising feed line for feeding an atomising agent into the cooling chamber. The atomising agent may be introduced into the cooling medium line at a location prior to the cooling medium injector.
In one embodiment of the cooling apparatus the cooling chamber includes two sub-chambers which are in fluid connection by means of a series of pipes running between the sub-chambers, and wherein the process gas is fed into one of the sub-chambers while the cooled process gas is discharged from the other sub-chamber. The cooling medium supplied to the cooling chamber may flow across the outer surface of the pipes connecting the sub-chambers to one another, thereby cooling down the process gas in the pipes. Preferably, the cooling chamber and the collection chamber form a single unit.
The cooling medium is preferably water.
According to a third aspect of the invention there is provided a system for the cooling and dry filtering of process gas produced in a ferroalloy smelting process, the system including a filtering apparatus according the first aspect of the invention and a cooling apparatus according to a second aspect of the invention, wherein the process gas outlet of the cooling apparatus is in fluid communication with the process gas inlet of the filtering apparatus so that the process gas entering the filtering apparatus is cooled down in the cooling apparatus prior to being introduced into the filtering apparatus.
According to a fourth aspect of the invention there is provided a method of dry filtering process gas produced in a ferroalloy smelting process, the method including the steps of:
feeding the process gas into a filtering chamber;
filtering the process gas in the filtering chamber through a filtering element, thereby removing solids present in the process gas entering the filtering chamber;
cleaning the filtering element using a cleaning gas;
collecting the dry solids which have been removed from the process gas in a discharge chamber;
discharging the solids collected in the discharge chamber into a collection hopper; and
discharging the solids from the collection hopper.
The step of discharging the solids into the collection hopper may include the steps of:
equalising the pressure in the discharge chamber and the collection hopper by means of an equalisation conduit running between the discharge chamber and the collection hopper; opening a sealing element between the discharge chamber and collection hopper to allow the flow of solids into the collection hopper;
closing a sealing element in the equalisation conduit;
closing the sealing element between the discharge chamber and collection hopper;
pressurising the collection hopper by opening a sealing element in a gas supply line which feeds pressuring gas to the collection hopper; and opening a sealing element between the collection hopper and a conveying system in order to discharge to solids from the collection hopper.
The method may further include the steps of:
closing the sealing element between the hopper and conveying system;
pressurising the hopper by opening the sealing element in the gas supply line;
venting the gas from the hopper by opening a sealing element in a vent line; and
pressurising the hopper again by opening the sealing element in the gas supply line.
The method may be used to filter process gas produced in a ferroalloy smelting process in which high volatile reductants are used.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described in more detail, by way of example only, with reference to the accompanying drawings in which:
Figure 1 shows a diagrammatic illustration of a first embodiment of a system for cooling and filtering process gas produced in a ferroalloy smelting process according to the invention; and shows a diagrammatic illustration of a second embodiment of a system for cooling and filtering process gas produced in a ferroalloy smelting process according to the invention.
DESCRIPTION OF THE ILLUSTRATED EMBODIMENT
Referring to the drawings, in which like numerals indicate like features, a non-limiting example of a system for cooling and filtering process gas in accordance with the invention is generally indicated by reference numeral 10.
The system 10 for cooling and filtering process gas, mainly carbon monoxide gas, produced in a ferroalloy smelting process according to the invention is shown in Figure 1. The system 10 includes a dry filtering apparatus for removing contaminants, typically solids, from the process gas. The filtering apparatus is generally indicated by the reference numeral 20. The term dry filtering is used to describe a filtering process in which solids are removed from the process gas without the use of a liquid in the filtering chamber.
The filtering apparatus 20 includes a filtering chamber 22 in which at least one filtering element 24 is located. The number of filtering elements 24 installed in the filtering chamber 22 depends on the process gas volumes to be cleaned. It is envisaged that due to the large volumes of process gas produced in the ferroalloy smelting process it may be advantageous to install multiple filtering elements 24. Each element 24 is made of porous material, typically metal or any similar material such as a ceramic material, for example. The process gas, which enters the filtering chamber 22 through an inlet of a process gas feed line 26, is filtered through the filtering element 24 to remove the solids present therein. The filtered gas is discharged from the filtering chamber 22 through an outlet of a process gas discharge line 28. In must be understood that the filtering element 24 is positioned between the process gas inlet and the outlet, thereby ensuring that the process gas is filtered through the filtering element before being discharged through the line 28. In the preferred embodiment the filtering element covers the entire or at least a major portion of the cross-sectional area of the filtering chamber 22 to ensure that the gas flow stream passes through the filtering element when moving from the inlet to the outlet.
During the filtering process the filtering element 24 may clog up as a result of the solids present in the process gas entering the filtering chamber 22. To clean the filtering element 24 automatically, a stream of cleaning gas is fed into the filtering chamber 22. The cleaning gas, which is either an inert gas, such as nitrogen, or filtered process gas, is supplied to the filtering chamber 22 by means of a supply line 30 and fed into the chamber through an inlet nozzle 32. A sealing element 33 is located in the supply line and operable to control the flow of cleaning gas by opening and closing off the supply line. As illustrated in Figure 1 , the cleaning gas inlet nozzle 32 is positioned so that the stream of cleaning gas is directed at the filtering element. In the preferred embodiment the inlet nozzle 32 is located above the filtering element 24 and blows the gas through the filtering element in a generally downward direction.
The term sealing element is used to describe a device capable of controlling the flow of fluid by opening and closing the fluid flow path, and could be in the form of a valve, for example.
The opening and closing of the sealing element 33, and therefore the flow of cleaning gas into the filtering chamber 22, is controlled by a control unit (not shown in the accompanying drawing). Instead of supplying a constant stream of cleaning gas the control unit opens and closes the sealing element periodically in order to control the duration and frequency of the blasts of cleaning gas.
The solids that are removed from the process gas are collected in a discharge chamber 34 which is positioned below the filtering chamber 22. In this configuration the solids move from the filtering chamber 22 into the discharge chamber under gravity. In the preferred embodiment the filtering chamber 22 and the discharge chamber 34 form part of a single unit or chamber 36 with the top portion thereof being the filtering chamber and the bottom portion the discharge chamber. It is envisaged that the chamber 36 could be circular, square or rectangular when viewed in cross-section.
From the discharge chamber 22 the solids that have been removed from the process gas are discharged into a collection hopper 38 where they are collected before being discharged into a conveying system 40 which transports the solids away from the filtering apparatus 10 to a location where they are typically stored in containers. The hopper 38 is positioned below the discharge chamber 34 so that the solids move from the chamber to the hopper under gravity. The conveying system 40 is positioned below the hopper for the same reason.
In order to control the flow of solids from the discharge chamber 34 to the hopper 38, a sealing element 42 is provided between the discharge chamber and hopper. Similarly, a sealing element 44 is located between the hopper 38 and the conveying system 40 for controlling the flow of solids from the hopper to the conveying system.
The filtering apparatus 20 further includes a pressure equalisation conduit 46, running between the discharge chamber 34 and the hopper 38, which is used to control the pressure difference between the discharge chamber 34 and the hopper 38. To enable the hopper 38 to be closed off from the discharge chamber 34, a sealing element 48 is located in the equalisation conduit. It must accordingly be clear that when the sealing element 48 is open the conduit 46 allows the pressures inside the chamber 34 and hopper 38 to equalise.
A gas supply line 50 is configured to supply a pressurising gas, which is typically an inert gas such as nitrogen, to the hopper 38, thereby allowing the pressure inside the hopper to be increased above that of the discharge chamber 34. Again, a sealing element 52 is located in the supply line 50 to control the flow of pressurising gas to the hopper. As shown in Figure 1 the supply line 50 is connected to the hopper 38. In this configuration, the pressure inside the hopper 38 may be increased by supplying pressurising gas to the hopper while the sealing element 48 in the equalisation line is closed. In an alternative embodiment not shown in the accompanying drawings the supply line 50 may be connected to the equalisation line 46 at a position between the hopper 38 and sealing element 48.
The hopper 38 also has an outlet in a vent line 54 for venting gas to reduce the internal pressure inside the hopper. A sealing element 56 controls the flow of gas inside the vent line 54. In other words, the sealing element 56 controls the venting of gas from the hopper 38.
The method of filtering process gas will now be described in detail.
The process gas containing the unwanted solids is fed into the filtering chamber 22 through the inlet of line 26 whereafter it is filtered through the filtering element 24 which removes the solids present in the process gas. The filtering element 24 in which the solids are caught is then cleaned in order to remove the solids. This is done by blowing the cleaning gas, which is supplied through the line 30, through the filtering element, thereby dislodging the solids in order to prevent it from clogging up. The solids that have been removed from the process gas are then collected in the discharge chamber 34 while the sealing element 42 is closed in order to prevent the solids from being discharged into the collection hopper 38.
When a sufficient amount of solids have been collected in the discharge chamber 34 the sealing element 48 in the equalisation conduit 46 is opened to equalise the pressure in the hopper 38 and the discharge chamber 34. Once the pressure has equalised, and with the sealing element 48 remaining open, the sealing element 42 between the discharge chamber 34 and hopper 38 is opened to allow the discharge of solids into the hopper. With the solids in the hopper 38 the sealing element 48 in the equalisation conduit 46 and the sealing element 42 between the discharge chamber and hopper are closed following a time delay or other trigger mechanism. Next, the sealing element 52 in the gas supply line 50 is opened so that the pressurising gas flows into the hopper while the vent sealing element 56 is closed. Upon confirmation of a high internal pressure inside the hopper 38 the sealing element 56 in the vent line 54 is opened to vent the gas. After a time delay the sealing element 56 in the vent line 54 is closed and upon confirmation of the internal pressure inside the hopper 38 reaching a predetermined pressure the supply of pressurising gas is cut off by closing the sealing element 52 in the supply line 50. On confirmation of the closure of the sealing element 52 the sealing element 44 between the hopper 38 and a conveying system 40 is opened in order to discharge the solids onto the conveying system to be transported away from the filtering apparatus 20.
Once the solids have been discharge from the hopper the sealing element 44 between the hopper and conveying system 40 is closed and the hopper is again pressurised though the pressurising line 50 by opening the sealing element 52 following confirmation of the closure of the sealing element 44.
It must be understood that as soon as the sealing element 42 between the discharge chamber and hopper is closed the build-up of solids in the discharge chamber 34 starts again and the steps of discharging the solids are repeated when a sufficient amount of solids have accumulated in the discharge hopper. The discharging of solids from the discharge chamber 34 is controlled by a timer or other trigger mechanism which periodically opens the sealing element 42. It must be understood that the time interval between two consecutive discharge cycles could be set according to the design parameters, including processing volume, of the filtering apparatus 20.
In some applications it is required that the process gas be cooled down prior to being filtered in the filtering apparatus 20. When this is required the temperature of the process gas is reduced in a cooling apparatus prior to being introduced into the filtering apparatus 20. The system 10 of Figure 1 includes a cooling apparatus, which is indicated by numeral 60.
The process gas produced by the smelting process is delivered to a cooling chamber 62 through a line 64 connecting the smelting process to the cooling apparatus 60. The line 64 terminates in a gas inlet which feeds the process gas into the cooling chamber 62. A cooling medium, typically in the form of a liquid such as water, is fed into the cooling chamber 62 to reduce the temperature of the process gas by means of an injector 66. The design of the injector is such that the cooling medium is fed into the cooling chamber 62 as a fine spray so that the gas is cooled down through evaporation of the atomised cooling medium inside the cooling chamber.
In the preferred embodiment an atomising agent is introduced into the cooling medium prior to it being dispensed into the cooling chamber 62 through the injector 66. In the cooling apparatus 60 of Figure 1 a pressurised cooling medium supply line 68 feeds the injector 66 and an atomising line 70 connects to the line 68 at a position upstream of the injector 66.
From the above description it must be clear that the interaction between the process gas and the cooling medium, which is in the form of spray in the cooling chamber, cools down the process gas before it exits the cooling chamber through an exit line 72. When the cooling apparatus 60 is connected to the filtering apparatus 20, the process gas exit line 72 of the cooling apparatus is connected to the process gas inlet line 26 of the filtering apparatus, as illustrated in Figure 1.
Apart from cooling down the process gas some solids are also removed from the process gas during this heat exchange procedure. The solids which settle in the cooling chamber 62 are collected in a collection chamber 74 located below the cooling chamber. The advantage of this configuration is that the settling solids settle in the collection chamber 74 under gravity. In the preferred embodiment the cooling chamber 62 and the collection chamber 74 form part of a single unit or chamber 76 with the top portion thereof being the cooling chamber and the bottom portion the collection chamber. It is envisaged that the chamber 76 could be circular when viewed in cross-section.
From the collection chamber 74 the settled solids are dispensed into a seal collection hopper 78, located below the collection chamber, in which the settled solids are collected before being discharged into a conveying system 80 which transports them away from the cooling apparatus 60. The cooling apparatus 60 further includes two sealing elements 82 and 84, which are located between the collection chamber 74 and hopper 78 and the hopper and conveying system 80 respectively. The sealing elements 82 and 84 control the flow of settled solids into and out of the hopper 78.
The internal pressures inside the collection chamber 74 and the hopper 78 are controlled in a similar manner as in the filtering apparatus 20 in that the cooling apparatus 60 includes a pressure equalisation conduit 86 running between the collection chamber 74 and the hopper 78. To enable the hopper 78 to be closed off from the collection chamber 74, a sealing element 88 is located in the equalisation conduit.
A gas supply line 90 is configured to supply a pressurising gas, which is typically an inert gas such as nitrogen, to the hopper 78, thereby allowing the pressure inside the hopper to be increased above that of the collection chamber 74. Again, a sealing element 92 is located in the supply line 90 to control the flow of pressurising gas to the hopper 78. In the preferred embodiment the supply line 90 is connected to the hopper 78. In this configuration, the pressure inside the hopper 78 may be increased by supplying pressurising gas to the hopper while the sealing element 88 in the equalisation line is closed. Again, it is envisaged that in an alternative embodiment not shown in the accompanying drawings the supply line 90 may be connected to the equalisation line 86 at a position between the hopper 78 and sealing element 88. The hopper 78 also has a vent line 94 for venting gas to reduce the internal pressure inside the hopper with a sealing element 96 again controlling the flow of gas inside the vent line 94.
It must be clear from the above description that the method of discharging the settled solids from the collection chamber 74 is the same as the method of discharging solids from the discharge chamber 34 of the filtering apparatus 20 and, accordingly, will not be described in any detail.
Figure 2 shows a second embodiment of the system for cooling and filtering process gas in accordance with the invention. The system of Figure 2 is generally indicated by the reference numeral 100.
The system 100 is similar to the system 10 described above as it includes the same filtering apparatus 20 described above with reference to the first embodiment of the system. However, the design of the process gas and cooling medium delivery mechanisms of the cooling apparatus of the second embodiment is different to that of the first embodiment. In Figure 2 the cooling apparatus is indicated by the reference numeral 110.
From this figure it can be seen that the process gas produced by the smelting process is delivered to a cooling chamber 112 through a line 114 connecting the smelting process to the cooling apparatus 110. The line 114 terminates in a gas inlet which feeds the process gas into the cooling chamber 112. A cooling medium, typically water or air, is fed through a line 116 into the cooling chamber 112 to reduce the temperature of the process gas and exits the cooling chamber through a line 118. The design of the cooling chamber 112 is such that the process gas is not in direct contact with the cooling medium.
The cooling chamber 112 includes two sub-chambers 120.1 and 120.2 which are in fluid connection with one another by means of a series of conduits or pipes 122 through which the process gas is conveyed from one sub-chamber to the other. In use, the process gas is delivered into the first sub-chamber 120.1 , also referred to as the gas inlet chamber, which is located before the second sub-chamber 120.2, also referred to as the gas outlet chamber. It must be clear that that process gas is conveyed from the gas inlet chamber 120.1 through the vertically oriented pipes 122 and into the gas outlet chamber 120.2. The cooling chamber 112 is designed so as to allow the cooling medium to flow over the outer surfaces of the pipes 122, thereby cooling down the process gas being conveyed in the pipes.
From the above description it must be clear that the configuration of the different fluid flow paths affectively creates a heat exchanger to cool down the process gas before it exits the cooling chamber, in particular the gas outlet chamber 120.2, through an exit line 72. Similarly to the first embodiment of the system 10, the cooling apparatus 110 is connected to the filtering apparatus 20 so that the process gas exit line of the cooling apparatus forms the process gas inlet tine 26 of the filtering apparatus.
The solids which settle are collected in a collection chamber 74 located below the cooling chamber 112. In the preferred embodiment the cooling chamber 12 and the collection chamber 74 form a part of a single unit. It is envisaged that the single unit could be square or rectangular when viewed in cross section.
From the collection chamber 74 the settled solids are dispensed into a seal collection hopper 78 in the same manner as described above. The method of discharging solids for from the collection hopper 78 will accordingly not be described in any detail.
It has been found that the sold content in the cleaned process gas discharged through the output line 28 of the filtering apparatus 20 is less than 5 mg/Nm3. Another advantage of the system 10, 100 according to the invention is that the process gas after filtering is not saturated with moisture as a result of the filtering process being a dry process. The method of controlling the pressure difference between the discharge chamber 34 and the collection hopper 38 allows for the discharging of solids which have been removed from the process gas without the use of a liquid in the filtering chamber 22. For this reason, the arrangement of the gas supply line 50, the equalisation conduit 46 and the vent line 54 plays an important role in producing dry filtered gas using the filtering apparatus 20.
By using the system 10, 100 described above the filtered process gas is also suitable for further processing in a de-tarring process without producing water containing either heavy of light tars when using reductants in the ferroalloy smelting process that may result in the process gas containing high levels of hydro carbons.

Claims

1. A dry filtering apparatus for the dry filtering of process gas produced in a ferroalloy smelting process, the apparatus including:
a filtering chamber in which a filtering element is located;
a process gas inlet for feeding the process gas into the filtering chamber, the inlet being positioned so that the process gas is filtered through the filtering element;
a process gas outlet for discharging filtered process gas from the filtering chamber;
a cleaning gas inlet for feeding a cleaning gas into the filtering chamber, the cleaning gas inlet being directed at the filtering element so that, in use, the cleaning gas is blown through the filtering element in order to dislodge solids caught in the filtering element;
a discharge chamber, positioned below the filtering chamber, in which the dry solids that have been removed from the process gas are collected; and
a collection hopper, located below the discharge chamber, in which the solids are collected before being discharged into a conveying system which transports the solids away from the filtering apparatus.
2. A filtering apparatus according to claim 1, including an equalisation conduit running between the filtering chamber and the collection hopper, the equalisation conduit having a sealing element therein for controlling gas flow between the filtering chamber and the collection hopper in order to control the pressure difference between the filtering chamber and collection hopper.
3. A filtering apparatus according to either claim 1 or 2, including two sealing elements, the first being located between the discharge chamber and the collection hopper and the second between the collection hopper and the conveying system, wherein the first sealing element is operable to control the flow of solids between the discharge chamber and the collection hopper and the second sealing element is operable to control the discharge of solids from the collection hopper to the conveying system.
A filtering apparatus according to any one of claims 1 to 3, including a gas supply line for feeding a pressurising gas into the collection hopper, the gas supply line having a sealing element for controlling the supply of pressurising gas to the collection hopper.
A filtering apparatus according to any one of claims 1 to 4, including a vent line for venting gas from the collection hopper, the vent line having a sealing element for controlling the venting of gas from the collection hopper.
A cooling apparatus for cooling process gas produced in a ferroalloy smelting process, the apparatus including:
a cooling chamber;
a process gas inlet for feeding the process gas into the cooling chamber;
a cooling medium feed line for feeding a cooling medium into the cooling chamber;
a process gas outlet for discharging cooled process gas;
a collection chamber, positioned below the cooling chamber, in which settled solids are collected; and
a collection hopper, located below the collection chamber, in which the settled solids are collected before being discharged into a conveying system which transports the solids away from the cooling apparatus.
A cooling apparatus according to any claim 6, including an equalisation conduit running between the cooling chamber and the collection hopper, the equalisation conduit having a sealing element for controlling gas flow between the cooling chamber and the collection hopper in order to control the pressure difference between the cooling chamber and the collection hopper.
8. A cooling apparatus according to either claim 6 or 7, including two sealing elements, the first being located between the collection chamber and the collection hopper and the second between the collection hopper and the conveying system, wherein the first sealing element is operable to control the flow of solids from the collection chamber and the collection hopper and the second sealing element is operable to control the discharge of solids from the collection hopper to the conveying system.
9. A cooling apparatus according any one of claims 6 to 8, including a gas supply line for feeding pressurising gas into the collection hopper, the gas supply line having a sealing element for controlling the supply of pressurising gas to the collection hopper.
10. A cooling apparatus according to any one of claim 6 to 9, including a vent line for venting gas from the collection hopper, the vent line having a sealing element for controlling the venting of gas from the collection hopper.
1 . A cooling apparatus according to any one of claims 6 to 10, including an atomising feed line for feeding an atomising agent into the cooling chamber.
12. A cooling apparatus according to any one of claims 6 to 11 , including a cooling medium injector located in the cooling medium feed line for injecting cooling medium into the cooling chamber.
13. A cooling apparatus according to claim 12, wherein an atomising agent is introduced into the cooling medium line at a location prior to the cooling medium injector.
14. A cooling apparatus according to any one of claims 6 to 10, wherein the cooling chamber includes two sub-chambers which are in fluid connection by means of a series of pipes running between the sub- chambers, and wherein the process gas is fed into one of the sub- chambers while the cooled process gas is discharged from the other sub-chamber.
15. A cooling apparatus according to claim 14, wherein the cooling medium supplied to the cooling chamber flows across the outer surface of the pipes connecting the sub-chambers to one another, thereby cooling down the process gas in the pipes.
16. A cooling apparatus according to either claim 14 or 15, wherein the cooling chamber and the collection chamber is a single unit.
17. A cooling apparatus according to any one of claims 6 to 16, wherein the cooling medium is water.
18. A system for the cooling and dry filtering of process gas produced in a ferroalloy smelting process, the system including a filtering apparatus according to any one of claims 1 to 5 and a cooling apparatus according to any one of claims 6 to 17 wherein the process gas outlet of the cooling apparatus is in fluid communication with the process gas inlet of the filtering apparatus so that the process gas entering the filtering apparatus is cooled down in the cooling apparatus prior to being introduced into the filtering apparatus.
19. A method of dry filtering process gas produced in a ferroalloy smelting process, the method including the steps of:
feeding the process gas into a filtering chamber;
filtering the process gas in the filtering chamber through a filtering element, thereby removing solids present in the process gas entering the filtering chamber;
cleaning the filtering element using a cleaning gas; collecting the dry solids which have been removed from the process gas in a discharge chamber;
discharging the solids collected in the discharge chamber into a collection hopper; and
discharging the solids from the collection hopper.
20. A method according to claim 19, wherein the step of discharging the solids into the collection hopper includes the steps of:
equalising the pressure in the discharge chamber and the collection hopper by means of an equalisation conduit running between the discharge chamber and the collection hopper;
opening a sealing element between the discharge chamber and collection hopper to allow the flow of solids into the collection hopper; closing a sealing element in the equalisation conduit; closing the sealing element between the discharge chamber and collection hopper;
pressurising the collection hopper by opening a sealing element in a gas supply line which feeds pressuring gas to the collection hopper; and
opening a sealing element between the collection hopper and a conveying system in order to discharge to solids from the collection hopper.
21. A method according to either claim 19 or 20, further including the steps of:
closing the sealing element between the hopper and conveying system;
pressurising the hopper by opening the sealing element in the gas supply line;
venting the gas from the hopper by opening a sealing element in a vent line; and
pressurising the hopper again by opening the sealing element in the gas supply line. A method according to any one of claims 19 to 21 , wherein the method is used to filter process gas produced in a ferroalloy smelting process in which high volatile reductants are used.
PCT/IB2013/052740 2012-04-05 2013-04-05 Method and apparatus for dry filtering process gas WO2013150498A2 (en)

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EA201401100A EA201401100A1 (en) 2012-04-05 2013-04-05 METHOD AND DEVICE OF DRY FILTRATION OF TECHNOLOGICAL GAS
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