CA2054799C - Method and arrangement for treating black liquor - Google Patents
Method and arrangement for treating black liquorInfo
- Publication number
- CA2054799C CA2054799C CA002054799A CA2054799A CA2054799C CA 2054799 C CA2054799 C CA 2054799C CA 002054799 A CA002054799 A CA 002054799A CA 2054799 A CA2054799 A CA 2054799A CA 2054799 C CA2054799 C CA 2054799C
- Authority
- CA
- Canada
- Prior art keywords
- steam
- black liquor
- gas turbine
- pressure
- gas
- Prior art date
- Legal status (The legal status 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 status listed.)
- Expired - Fee Related
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01K—STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
- F01K23/00—Plants characterised by more than one engine delivering power external to the plant, the engines being driven by different fluids
- F01K23/02—Plants characterised by more than one engine delivering power external to the plant, the engines being driven by different fluids the engine cycles being thermally coupled
- F01K23/06—Plants characterised by more than one engine delivering power external to the plant, the engines being driven by different fluids the engine cycles being thermally coupled combustion heat from one cycle heating the fluid in another cycle
- F01K23/067—Plants characterised by more than one engine delivering power external to the plant, the engines being driven by different fluids the engine cycles being thermally coupled combustion heat from one cycle heating the fluid in another cycle the combustion heat coming from a gasification or pyrolysis process, e.g. coal gasification
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C11/00—Regeneration of pulp liquors or effluent waste waters
- D21C11/06—Treatment of pulp gases; Recovery of the heat content of the gases; Treatment of gases arising from various sources in pulp and paper mills; Regeneration of gaseous SO2, e.g. arising from liquors containing sulfur compounds
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C11/00—Regeneration of pulp liquors or effluent waste waters
- D21C11/10—Concentrating spent liquor by evaporation
- D21C11/103—Evaporation by direct contact with gases, e.g. hot flue gases
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C11/00—Regeneration of pulp liquors or effluent waste waters
- D21C11/12—Combustion of pulp liquors
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E20/00—Combustion technologies with mitigation potential
- Y02E20/12—Heat utilisation in combustion or incineration of waste
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E20/00—Combustion technologies with mitigation potential
- Y02E20/16—Combined cycle power plant [CCPP], or combined cycle gas turbine [CCGT]
- Y02E20/18—Integrated gasification combined cycle [IGCC], e.g. combined with carbon capture and storage [CCS]
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/10—Greenhouse gas [GHG] capture, material saving, heat recovery or other energy efficient measures, e.g. motor control, characterised by manufacturing processes, e.g. for rolling metal or metal working
Abstract
A method and arrangement for recovering black liquor chemicals and heat in a sulphate pulp process. The black liquor is concentrated in an evaporation plant, which comprises a pressure heating reactor (12), after which the black liquor is gasified or combusted in a reactor (10) for producing hot gases. The hot gases formed in the reactor (10) are introduced into a gas turbine power plant (16). The exhaust gases from the gas turbine (40) are introduced into a waste heat boiler (52), where steam is generated for a steam turbine power plant (18). Secondary steam is led from the pressure heating reactor as injection steam into the gas turbine.
Description
- 20~799 METHOD AND ARRANGEMENT FOR TREATING BLACK LIQUOR
The present invention relates to a method and arrangement for treating black liquor of sulphate pulp processes for recovering chemicals and heat therefrom. The method comprises gasifying and/or combusting black liquor in a pressurized gasification or combustion reactor. Molten and/or solid salts produced in the gasification and/or combustion are introduced into a dissolving tank for recovery of the cooking chemicals, and the gases formed in the process are conducted through a purification stage further into a gas turbine, for recovering the energy from the gases. From the gas turbine, the exhaust gases are fed into a waste heat boiler where their residual energy is recovered as high pressure steam, which is utilized in a steam turbine power plant.
Recovery of cooking chemicals and heat recovery are essential aspects of sulphate pulp production. In present pulp mills, the recovery process is usually effected by combusting black liquor in a recovery boiler. The chemical substance is recovered in a soda smelt and the organic substance, dissolved from wood, burns, thereby generating heat, which is recovered by means of heat transfer surfaces arranged in the boiler. It has also been suggested to recover chemical substance by gasifying black liquor.
Besides molten chemical substance, gas of high thermal value is generated in the gasifier, which gas may be employed, e.g., in a gas turbine.
The dry solids content of the black liquor obtained from the pulp washing stage after cooking is only about 15 to 20 %. It cannot, as such, be introduced into a recovery boiler or a gasifier to be either combusted or gasified.
P918/EM3 ~
20~79!~
The evaporation plant in the pulp mill concentrates the black liquor to such an extert that the dry solids content is high enough for combustion or gasification. To obtain as much energy as possible from the black liquor, it is concentrated to the highest possible dry solids content.
With the present technique, it is about 65 - 80%.
The thermal power required for evaporation is obtained - from the steam or hot flue gases formed in the process.
Today, evaporation is usually effected in heat exchangers by using steam from a recovery boiler.
An increase in the dry solids content adds to the heat consumption of the evaporation plant because the amount of water to be evaporated is larger. The increase in heat generation in the combustion process is, however, much higher than the additional heat required for evaporation and, therefore, more valuable. The additional heat thus generated in the recovery boiler can be recovered as high pressure steam.
Formerly, several recovery boilers were constructed so that the final concentration of liquor was effected by means of a direct flue gas evaporator or a cyclone evaporator. The reason for that was that evaporation to a dry solids content of > 50 ~ in a heat exchanger was found difficult because the heat transfer surfaces were badly fouled. Direct flue gas evaporation, however, has some drawbacks, such as - smell and emissions from evaporators, - the conversion efficiency of steam generation in the boiler decreases, - it is not possible to utilize the secondary steam exhausted from the evaporator as the evaporation takes place in one stage only.
20S~799 -Due to the drawbacks mentioned above, recovery boilers arranged with direct flue gas evaporation systems have later been modified so as to effect the final cooling of flue gases in water preheaters and the final concentration of liquor in additional evaporator units.
The above~identified drawbacks may be partly avoided by a system for final concentration of liquor as suggested in the Finnish patent application 854549. In that system, waste liquor is heated by flue gases formed in pressurized combustion, in an indirect heat exchange, utilizing the heat content of the flue gases after boiler. Flue gas heating takes place at such a concentration, at which liquor does not yet adhere to the heat transfer surfaces.
Therafter, the heated, pressurized liquor is allowed to expand to a lower pressure, whereby water evaporates from the liquor, which becomes concentrated. This concentration takes place in a separate means having no heat transfer surfaces which would become fouled. It has been suggested that the secondary steam thereby generated could replace the primary steam of the evaporation plant connected in series. In this way, liquor may be heated from the temperature of 80 - 120C to 160 - 250C and be concentrated to a dry solids content of > 55%. However, sulphur emissions of the recovery boiler and evaporation plant cannot be avoided.
Sulphur emissions of a sulphate pulp mill mainly originate from the recovery boiler, evaporation plant and cooking plant. It has been established that an increase in the black liquor dry solids content, achieved by evaporation, decreases sulphur emissions of the flue gases of the recovery boiler. The sulphur content of green liquor, on the contrary, increases as a result of increased dry solids content and, consequently, also the sulphur contents of both white liquor and black liquor increase. There is also 205~79~
reason to believe that the sulphur emissions of the evaporation plant increase due to a higher sulphur content of black liquor.
As the energy price continues to increase, it has become more and more important to have a high conversion efficiency in power generation in the recovery of chemicals.
The heat of combustion gases formed in the combustion of black liquor in the recovery boiler has to be mainly recovered as steam. To avoid corrosion of the boiler, the p and T values of the steam have to be relatively low, which means that the best possible conversion efficiency is not provided in power generation. The high pressure steam generated is introduced into a back-pressure steam turbine and the steam from the exhaust side is used for covering the heat demand of the pulp mill. The turbine and a generator connected thereto generate the electricity required by the mill. However, the conversion efficiency in electricity generation is only about 20 to 25 %. The recovery boiler has developed into a reliable regeneration and energy generation process, but the ratio of heat to electricity given thereby is disadvantageous in present sulphate pulp mills. Today, the heat generation in recovery boilers very well meets the present demand, due to lower heat consumption in the pulp mill processes, but electricity is generated with a poor conversion efficiency.
In pulp production, the trend is also such that steam consumption no longer increases, whereas electricity consumption still increases, especially in integrated pulp and paper mills.
The aspects described above have given reason for long-term studies on how the conventional recovery boiler could be replaced by new processes, such as black liquor gasification. For the time being, a large number of 20S479~
alternatives are being researched. Common to the suggested new processes is to separate regeneration of chemicals and the energy production and to adapt the fuel produced to combined power plants.
Black liquor may be gasified in many different ways. Popular methods under examination are, for example, solid phase gasification and molten phase gasification. The gas produced in gasification may be combusted either in a conventional boiler or in a pressurized combined process in order to generate steam and electricity.
Finnish patent application 841540 suggests pressurized gasification of black liquor, which offers an opportunity of applying combined power plant technology in the power generation at the pulp mill. According to that method, gasification produces combustible gas and the sulphur content of black liquor is converted substantially to sulphide. The black liquor (of 45 to 75 %) is introduced into the gasifier as an aqueous solution. The gas produced in the gasification is purified and combusted in order to receive hot flue gases, which are then utilized for electricity generation in the gas turbine. The çxhaust gases from the gas turbine are fed into a waste heat boiler, where the heat of the exhaust gases is used to generate steam for the steam turbine plant. Besides electricity, the steam turbine system generates process steam.
Aqueous black liquor is introduced into the upper section of the gasifier as fine drops. Prior to gasifying, the black liquor drops dry in the hot gas flow rising upwardly from the bottom of the gasifier. The solid or molten salt residue of the gasified black liquor accumulates on the lower section of the gasifier and is further introduced into a dissolving tank to recover cooking chemicals. The 20~799 water evaporated from the black liquor as well as other evaporating substances are entrained with the product gas, flowing out of the gasifier from the upper section thereof.
Thus, the gas from the gasifier contains both gas produced by gasification of black liquor and water evaporating from the black liquor being concentrated and/or other evaporable alkali and sulphur compounds. Harmful substances have to be separated from the gases prior to leading the gases into the gas turbine. The gases are led, for example, into an absorption tower, where sulpur compounds are removed therefrom and thereafter, e.g., into a wet scrubber for final purification.
A drawback of the black liquor gasification system suggested above is the high content of water vapor in the gases. The more water vapor the gas contains, the poorer its combustion properties and the conversion efficiency in electricity generation in the gas turbine are.
Furthermore, a large volume of exhaust gases thereby produced require extensive gas purification systems which, at the same time have to purify both the gases produced in evaporation and the gases produced in gasification in order to remove harmful substances from the gases prior to introducing them into the gas turbine. The gas purification cost will be considerable.
The conversion efflciency in electricity generation at a gas turbine is usually also lowered by a relatively large volume of air needed in the gas turbine for lowering the inlet temperature. This increases the power requirement of the compressor, thereby lowering the conversion efficiency in electricity generation at the gas turbine.
An object of the present invention is to provide an improved method of recovering chemicals and heat from black liquor 20~799 so that the above-described drawbacks relating to prior art recovery methods are minimized.
A primary object of the invention is to provide a method and an arrangement for recovering chemicals and heat from black liquor with the best possible conversion efficiency in electricity generation.
Another object of the invention is to provide an improved method of temperature regulation of the gas turbine in a black liquor heat recovery plant.
A further object of the invention is to provide a method of minimizing the harmful emissions caused by final evaporation of black liquor.
It is a main characteristic feature of the method of the invention for recovering chemicals and heat from black liquor in a sulphate pulping process, in which method black liquor is gasified (and/or combusted) and gases are expanded in a gas turbine for electricity generation, that pressurized secondary steam from a sulphate pulp process is introduced as injection steam into the gas turbine combustor to the combustion gases therein, prior to the gas turbine vanes, for regulating the gas turbine inlet temperature. This secondary steam formed in the sulphate pulp process, which is applicable to, e.g. temperature regulation, is secondary steam from, e.g., the cooking plant, expansion stage, drying section, or the evaporation plant. The secondary steams may be additionally pressurized to the pressure level of the gas turbine.
The arrangement according to the invention thereby comprises - black liquor evaporators for concentrating of black liquor;
- ~S4q99 - a pressurized reactor for gasifying or combusting the black liquor concentrated in the evaporators;
- a gas purification means for purifying the gas formed in the pressurized reactor;
- a gas turbine power plant for recovering the energy from the purified gas;
- a waste heat boiler for heat recovery from the turbine exhaust gas as pressurized steam and - a steam turbine power plant for recovering the energy from the steam generated in the waste heat boiler;
and is characterized by a pressure heating reactor, serving as an evaporator of black liquor, which evaporator is connected to a gas turbine or a gas turbine combustor with a duct, for leading the pressurized secondary steam from the pressure heating reactor as injection steam into the gas turbine.
As a considerable amount of secondary steam is generated especially in the evaporation plant and in connection with pressurized heating of black liquor prior to gasification ~or combustion), the invention will be explained in the following with reference to the arrangements where black liquor is pressure-heated prior to gasification or combustion and where the secondary steams generated in the pressure heating stage are introduced into the gas turbine for lowering its inlet temperature.
In accordance with a preferred embodiment of the invention, black liquor is evaporated by conventional evaporation and pressure heating methods to a high dry solids content, which is advantageus on the whole. Thereafter, black liquor is gasified and the energy content of the gases thereby formed is recovered in a combined gas turbine and steam turbine power plant. The secondary steams generated in the pressure heating, which contain water and other evaporable 205~799 components, are introduced into the gas turbine combustor for regulating the temperature of the combustion gases formed therein to be suitable prior to leading the combustion gases to the turbine vanes. Steam required by the black liquor pressure heating is received from the steam turbine.
The method of the invention provides an advantageous way of recovering the secondary steam exhausted from the pressure heating stage. This is effected by injecting it as injection steam into the gas turbine. Feeding of secondary steam into the gas turbine reduces the volume of excess air normally required for temperature regulation of the gas entering the gas turbine vanes. This reduces the power requirement of the compressor, and the process becomes more effective.
In the method in which the black liquor is combusted instead of being gasified, the secondary steams from pressure heating and the flue gases from combustion may be combined prior to introducing them into the gas turbine. In this way, the volume of gas passing through the gas turbine and, consequently, also electricity generation is increased also in the black liquor combustion process. Combining the secondary steams with the flue gases provides an advantageous purification system of secondary steams in a combined secondary steam and flue gas cleaner.
The pressure heating process, i.e., heat treatment of liquor may be arranged in some intermediate stage of evaporation or immediately before gasification or combustion. In pressure heating, the black liquor temperature is raised to a level above the cooking temperature, preferably to 170 - 200C for splitting the macromolecular lignin fractions contained in the black liquor. Compounds containing sulphur or alkali are easily evaporated from the black liquor in a pressure heating process. The most economic heating system may be chosen, e.g., direct or indirect steam heating or some other heating system, such as electrical heating. Reheat steam from a steam turbine power plant is preferably used as a heat source in pressure heating. The viscosity of black liquor may be lowered by pressure heating, which improves black liquor treating properties and evaporability as well as helps in transferring liquor from one stage to the other.
Thus, pressure heating enables evaporation of liquor to the highest possible dry solids content, whereby the efficient combustion value of the black liquor rises and the conversion efficiency of electricity generation in the combined gas turbine and steam turbine power plant also increases. An increase in the dry solids content of the black liquor increases the effective gas flow from the gasifier or recovery boiler. Thereby, the electricity generation in the gas turbine increases as well as the steam generation in the waste heat boiler and consequently, also the electricity generation in the steam turbine.
In a combined power plant, the excess secondary steam generated in pressure heating may be converted to electric power by injecting the secondary steam into the gas turbine as injection steam. Injection steam is fed to the combustion gases in the gas turbine combustor. The pressure of the secondary steam has to be high enough for a successful feed into the pressurized gas. The steam injection also improves the conversion efficiency of electricity generation and the efficiency of the gas turbine and reduces the need for excess air to be introduced into the gas turbine by the compressor. In a gas turbine where the excess air level has been about 1.4, it may be lowered to about 1.15 because of steam injection.
20~4799 A change in the volume of air which has to be compressed in the compressor is an important parameter for the process. As injection of secondary steam into the combustion gas entering the gas turbine according to the invention also lowers the temperature of the combustion gas, the temperature of the gas entering the gas turbine vanes can be maintained constant by means of steam injection. Thereby, the amount of excess cooling air compressed in the compressor ca`n be decreased in proportion to the injected steam. In several gas turbines, the compressor is provided with a set of adjustable guide vanes. The output from the compressor may be adjusted by means of such vanes. An economic adjustment range is rather narrow, from 80 to 100%. The gas turbine may also be operated within another adjustment range, but in that case the combustion gas temperature probably decreases when the steam injection increases.
The secondary steams introduced into the gas turbine have to be cleaned prior to leading them into the turbine. The secondary steams from pressure heating contain, e.g., sulphur and alkali compounds and possibly also other harmful substances that have to be removed from the secondary steam prior to the gas turbine. The gases from the gasification stage have to be also purified. The gas flows are purified separately, which means that it is possible to use the most suitable purification method for the different harmful compounds of the secondary steam and the gas respectively. The gas purification processes may, however, be connected so that both systems use, for example, the same absorption mass. The actual purification takes place in separate equipment, but regeneration of the absorption mass may be effected in one and the same equipment, which saves costs. Purification of the secondary steam in a separate equipment provides efficient purification of a small secondary steam flow with relatively -simple means. Sulphur compounds are easier to remove from small quantities of secondary steam than from large quantities of combined steam and gas. Further, it is advantageous to remove sulphur compounds from the secondary steam prior to the sulphur compounds coming into contact with air in the gas turbine combustor. The pressurized secondary steam flow is relatively small and therefore also the plant needed for its purification. It is advantageous for the entire process if the gases may be purified at the highest possible temperature, whereby the heat energy contained in the gas may be utilized in the gas turbine.
Pressure heating may be effected at the same pressure as gasification or combustion, e.g., at about 20 bar. However, based on the values of the steam used for the heat treatment, the heat treatment may be arranged at a pressure which is either lower or higher than the pressure of the gasifier. Before introducing the gas into the gas turbine combustor, the pressure of the secondary steam from the heat treatment has to be adjusted by a pressure relief valve or by raising the pressure.
Pressure heating of black liquor and use of secondary steam as injection steam according to the invention is especially suitable for gasification of black liquor because the high dry solids content of black liquor has a very positive effect on the gasification of liquor. Thus, lowering the viscosity of the liquor by means of pressure heating contributes to the gasification process.
Gasification of black liquor having a high dry solids content produces gas of high heat value, which may be utilized effectively in a combined gas turbine and steam turbine power plant. The gasification is preferably effected at a high temperature, whereby the inorganic substance of 205~799 the black liquor is discharged from the reactor in a molten form, and the smelt may be further treated in a conventional manner.
The invention is further described in the following, by way of example, with reference to the accompanying drawing, which is a schematic illustration of a pressure heating system according to the invention, arranged in a black liquor gasification plant.
The gasification plant of the Figure comprises a black liquor gasification reactor 10, a pressure heating means 12, gas purification means 14, gas turbine power plant 16 and a steam turbine power plant 18.
Black liquor is fed by pump 22 into the pressure heating reactor 12. In the pressure heating reactor, black liquor is heated indirectly by leading reheat steam by duct 24 from the steam turbine power plant into a heat exchanger 26. The black liquor is heated to a temperature of, e.g, 180 - 200C. The pressure is about 10 to 20 bar in the pressure heating reactor.
Concentrated black liquor is led by duct 27 from the pressure heating stage to a final evaporation stage 28 and furthèr, via duct 29, into the gasifier 10. The water evaporated from the black liquor as well as other easily gasifying components are introduced via duct 30 into a steam purification means 15, where sulphur and other substances, such as alkali compounds, which are harmful to the gas turbine power plant are preferably removed from the secondary steams.
The gases formed in the actual gasifier 10 are led via duct 11 into a gas purification plant 17, where they are cleaned separately from the secondary steams coming from _ 20~479~
the pressure heating stage. The smelt formed in the gasifier is drained off through a chute 13.
From the gas purification plant, both the purified steam and the gas flows are taken through ducts 32 and 34 into a gas turbine combustor 36 for producing hot combustion gases. The secondary steam flow from duct 32 cools combustion gases produced in the combustor. The combustion gases and the secondary steam entrained therewith are led via duct 38 from the combustor into a gas turbine 40. A
generator 42 for generating electricity and a compressor 44 for producing compressed air are mounted on the same shaft as the gas turbine. Compressed air is conducted via duct 46 from the compressor into the gasifier 10 and via duct 48 into the combustor 36.
The exhaust gases from the gas turbine are led via duct 50 into a waste heat boiler 52 for utilizing the residual heat of the gases for steam generation. The cooled gases are led from the waste heat boiler via duct 54 into the stack.
In the steam turbine system 18, feed water is led by duct 58 from a feed water tank 56 into a steam generator 60 arranged in the waste heat boiler. The high pressure steam generated in the steam generator is led via duct 62 into a steam turbine 64. A generator 66 for electricity generation is mounted on the same shaft as the steam turbine. Reheat steam is taken out of the steam turbine and led via duct 24 into the pressure heater 12. Low pressure steam and possibly reheat steam is conducted from the steam turbine via ducts 68 and 70 to means 72, wherefrom the condensate is recirculated to the feed water tank 56 via duct 74. Also the condensated steam from the heat exchanger 26 is conducted via duct 76 into the feed water tank.
205~799 The pressure in the gasifier is preferably equal to the pressure in the pressure heating plant. In the embodiment of the Figure, the pressure in the gasifier is, however, higher than the pressure in the pressure heating plant, whereby a pressure raising means 78 is arranged after the pressure heating plant 12 for increasing the pressure of the secondary steam to the level of the pressure of the gas coming from the gasifier.
The arrangement described above is only an exemplary embodiment of the invention, and the details of the invention may vary and deviate from the above arrangement within the inventive scope defined by the accompanying claims.
The present invention relates to a method and arrangement for treating black liquor of sulphate pulp processes for recovering chemicals and heat therefrom. The method comprises gasifying and/or combusting black liquor in a pressurized gasification or combustion reactor. Molten and/or solid salts produced in the gasification and/or combustion are introduced into a dissolving tank for recovery of the cooking chemicals, and the gases formed in the process are conducted through a purification stage further into a gas turbine, for recovering the energy from the gases. From the gas turbine, the exhaust gases are fed into a waste heat boiler where their residual energy is recovered as high pressure steam, which is utilized in a steam turbine power plant.
Recovery of cooking chemicals and heat recovery are essential aspects of sulphate pulp production. In present pulp mills, the recovery process is usually effected by combusting black liquor in a recovery boiler. The chemical substance is recovered in a soda smelt and the organic substance, dissolved from wood, burns, thereby generating heat, which is recovered by means of heat transfer surfaces arranged in the boiler. It has also been suggested to recover chemical substance by gasifying black liquor.
Besides molten chemical substance, gas of high thermal value is generated in the gasifier, which gas may be employed, e.g., in a gas turbine.
The dry solids content of the black liquor obtained from the pulp washing stage after cooking is only about 15 to 20 %. It cannot, as such, be introduced into a recovery boiler or a gasifier to be either combusted or gasified.
P918/EM3 ~
20~79!~
The evaporation plant in the pulp mill concentrates the black liquor to such an extert that the dry solids content is high enough for combustion or gasification. To obtain as much energy as possible from the black liquor, it is concentrated to the highest possible dry solids content.
With the present technique, it is about 65 - 80%.
The thermal power required for evaporation is obtained - from the steam or hot flue gases formed in the process.
Today, evaporation is usually effected in heat exchangers by using steam from a recovery boiler.
An increase in the dry solids content adds to the heat consumption of the evaporation plant because the amount of water to be evaporated is larger. The increase in heat generation in the combustion process is, however, much higher than the additional heat required for evaporation and, therefore, more valuable. The additional heat thus generated in the recovery boiler can be recovered as high pressure steam.
Formerly, several recovery boilers were constructed so that the final concentration of liquor was effected by means of a direct flue gas evaporator or a cyclone evaporator. The reason for that was that evaporation to a dry solids content of > 50 ~ in a heat exchanger was found difficult because the heat transfer surfaces were badly fouled. Direct flue gas evaporation, however, has some drawbacks, such as - smell and emissions from evaporators, - the conversion efficiency of steam generation in the boiler decreases, - it is not possible to utilize the secondary steam exhausted from the evaporator as the evaporation takes place in one stage only.
20S~799 -Due to the drawbacks mentioned above, recovery boilers arranged with direct flue gas evaporation systems have later been modified so as to effect the final cooling of flue gases in water preheaters and the final concentration of liquor in additional evaporator units.
The above~identified drawbacks may be partly avoided by a system for final concentration of liquor as suggested in the Finnish patent application 854549. In that system, waste liquor is heated by flue gases formed in pressurized combustion, in an indirect heat exchange, utilizing the heat content of the flue gases after boiler. Flue gas heating takes place at such a concentration, at which liquor does not yet adhere to the heat transfer surfaces.
Therafter, the heated, pressurized liquor is allowed to expand to a lower pressure, whereby water evaporates from the liquor, which becomes concentrated. This concentration takes place in a separate means having no heat transfer surfaces which would become fouled. It has been suggested that the secondary steam thereby generated could replace the primary steam of the evaporation plant connected in series. In this way, liquor may be heated from the temperature of 80 - 120C to 160 - 250C and be concentrated to a dry solids content of > 55%. However, sulphur emissions of the recovery boiler and evaporation plant cannot be avoided.
Sulphur emissions of a sulphate pulp mill mainly originate from the recovery boiler, evaporation plant and cooking plant. It has been established that an increase in the black liquor dry solids content, achieved by evaporation, decreases sulphur emissions of the flue gases of the recovery boiler. The sulphur content of green liquor, on the contrary, increases as a result of increased dry solids content and, consequently, also the sulphur contents of both white liquor and black liquor increase. There is also 205~79~
reason to believe that the sulphur emissions of the evaporation plant increase due to a higher sulphur content of black liquor.
As the energy price continues to increase, it has become more and more important to have a high conversion efficiency in power generation in the recovery of chemicals.
The heat of combustion gases formed in the combustion of black liquor in the recovery boiler has to be mainly recovered as steam. To avoid corrosion of the boiler, the p and T values of the steam have to be relatively low, which means that the best possible conversion efficiency is not provided in power generation. The high pressure steam generated is introduced into a back-pressure steam turbine and the steam from the exhaust side is used for covering the heat demand of the pulp mill. The turbine and a generator connected thereto generate the electricity required by the mill. However, the conversion efficiency in electricity generation is only about 20 to 25 %. The recovery boiler has developed into a reliable regeneration and energy generation process, but the ratio of heat to electricity given thereby is disadvantageous in present sulphate pulp mills. Today, the heat generation in recovery boilers very well meets the present demand, due to lower heat consumption in the pulp mill processes, but electricity is generated with a poor conversion efficiency.
In pulp production, the trend is also such that steam consumption no longer increases, whereas electricity consumption still increases, especially in integrated pulp and paper mills.
The aspects described above have given reason for long-term studies on how the conventional recovery boiler could be replaced by new processes, such as black liquor gasification. For the time being, a large number of 20S479~
alternatives are being researched. Common to the suggested new processes is to separate regeneration of chemicals and the energy production and to adapt the fuel produced to combined power plants.
Black liquor may be gasified in many different ways. Popular methods under examination are, for example, solid phase gasification and molten phase gasification. The gas produced in gasification may be combusted either in a conventional boiler or in a pressurized combined process in order to generate steam and electricity.
Finnish patent application 841540 suggests pressurized gasification of black liquor, which offers an opportunity of applying combined power plant technology in the power generation at the pulp mill. According to that method, gasification produces combustible gas and the sulphur content of black liquor is converted substantially to sulphide. The black liquor (of 45 to 75 %) is introduced into the gasifier as an aqueous solution. The gas produced in the gasification is purified and combusted in order to receive hot flue gases, which are then utilized for electricity generation in the gas turbine. The çxhaust gases from the gas turbine are fed into a waste heat boiler, where the heat of the exhaust gases is used to generate steam for the steam turbine plant. Besides electricity, the steam turbine system generates process steam.
Aqueous black liquor is introduced into the upper section of the gasifier as fine drops. Prior to gasifying, the black liquor drops dry in the hot gas flow rising upwardly from the bottom of the gasifier. The solid or molten salt residue of the gasified black liquor accumulates on the lower section of the gasifier and is further introduced into a dissolving tank to recover cooking chemicals. The 20~799 water evaporated from the black liquor as well as other evaporating substances are entrained with the product gas, flowing out of the gasifier from the upper section thereof.
Thus, the gas from the gasifier contains both gas produced by gasification of black liquor and water evaporating from the black liquor being concentrated and/or other evaporable alkali and sulphur compounds. Harmful substances have to be separated from the gases prior to leading the gases into the gas turbine. The gases are led, for example, into an absorption tower, where sulpur compounds are removed therefrom and thereafter, e.g., into a wet scrubber for final purification.
A drawback of the black liquor gasification system suggested above is the high content of water vapor in the gases. The more water vapor the gas contains, the poorer its combustion properties and the conversion efficiency in electricity generation in the gas turbine are.
Furthermore, a large volume of exhaust gases thereby produced require extensive gas purification systems which, at the same time have to purify both the gases produced in evaporation and the gases produced in gasification in order to remove harmful substances from the gases prior to introducing them into the gas turbine. The gas purification cost will be considerable.
The conversion efflciency in electricity generation at a gas turbine is usually also lowered by a relatively large volume of air needed in the gas turbine for lowering the inlet temperature. This increases the power requirement of the compressor, thereby lowering the conversion efficiency in electricity generation at the gas turbine.
An object of the present invention is to provide an improved method of recovering chemicals and heat from black liquor 20~799 so that the above-described drawbacks relating to prior art recovery methods are minimized.
A primary object of the invention is to provide a method and an arrangement for recovering chemicals and heat from black liquor with the best possible conversion efficiency in electricity generation.
Another object of the invention is to provide an improved method of temperature regulation of the gas turbine in a black liquor heat recovery plant.
A further object of the invention is to provide a method of minimizing the harmful emissions caused by final evaporation of black liquor.
It is a main characteristic feature of the method of the invention for recovering chemicals and heat from black liquor in a sulphate pulping process, in which method black liquor is gasified (and/or combusted) and gases are expanded in a gas turbine for electricity generation, that pressurized secondary steam from a sulphate pulp process is introduced as injection steam into the gas turbine combustor to the combustion gases therein, prior to the gas turbine vanes, for regulating the gas turbine inlet temperature. This secondary steam formed in the sulphate pulp process, which is applicable to, e.g. temperature regulation, is secondary steam from, e.g., the cooking plant, expansion stage, drying section, or the evaporation plant. The secondary steams may be additionally pressurized to the pressure level of the gas turbine.
The arrangement according to the invention thereby comprises - black liquor evaporators for concentrating of black liquor;
- ~S4q99 - a pressurized reactor for gasifying or combusting the black liquor concentrated in the evaporators;
- a gas purification means for purifying the gas formed in the pressurized reactor;
- a gas turbine power plant for recovering the energy from the purified gas;
- a waste heat boiler for heat recovery from the turbine exhaust gas as pressurized steam and - a steam turbine power plant for recovering the energy from the steam generated in the waste heat boiler;
and is characterized by a pressure heating reactor, serving as an evaporator of black liquor, which evaporator is connected to a gas turbine or a gas turbine combustor with a duct, for leading the pressurized secondary steam from the pressure heating reactor as injection steam into the gas turbine.
As a considerable amount of secondary steam is generated especially in the evaporation plant and in connection with pressurized heating of black liquor prior to gasification ~or combustion), the invention will be explained in the following with reference to the arrangements where black liquor is pressure-heated prior to gasification or combustion and where the secondary steams generated in the pressure heating stage are introduced into the gas turbine for lowering its inlet temperature.
In accordance with a preferred embodiment of the invention, black liquor is evaporated by conventional evaporation and pressure heating methods to a high dry solids content, which is advantageus on the whole. Thereafter, black liquor is gasified and the energy content of the gases thereby formed is recovered in a combined gas turbine and steam turbine power plant. The secondary steams generated in the pressure heating, which contain water and other evaporable 205~799 components, are introduced into the gas turbine combustor for regulating the temperature of the combustion gases formed therein to be suitable prior to leading the combustion gases to the turbine vanes. Steam required by the black liquor pressure heating is received from the steam turbine.
The method of the invention provides an advantageous way of recovering the secondary steam exhausted from the pressure heating stage. This is effected by injecting it as injection steam into the gas turbine. Feeding of secondary steam into the gas turbine reduces the volume of excess air normally required for temperature regulation of the gas entering the gas turbine vanes. This reduces the power requirement of the compressor, and the process becomes more effective.
In the method in which the black liquor is combusted instead of being gasified, the secondary steams from pressure heating and the flue gases from combustion may be combined prior to introducing them into the gas turbine. In this way, the volume of gas passing through the gas turbine and, consequently, also electricity generation is increased also in the black liquor combustion process. Combining the secondary steams with the flue gases provides an advantageous purification system of secondary steams in a combined secondary steam and flue gas cleaner.
The pressure heating process, i.e., heat treatment of liquor may be arranged in some intermediate stage of evaporation or immediately before gasification or combustion. In pressure heating, the black liquor temperature is raised to a level above the cooking temperature, preferably to 170 - 200C for splitting the macromolecular lignin fractions contained in the black liquor. Compounds containing sulphur or alkali are easily evaporated from the black liquor in a pressure heating process. The most economic heating system may be chosen, e.g., direct or indirect steam heating or some other heating system, such as electrical heating. Reheat steam from a steam turbine power plant is preferably used as a heat source in pressure heating. The viscosity of black liquor may be lowered by pressure heating, which improves black liquor treating properties and evaporability as well as helps in transferring liquor from one stage to the other.
Thus, pressure heating enables evaporation of liquor to the highest possible dry solids content, whereby the efficient combustion value of the black liquor rises and the conversion efficiency of electricity generation in the combined gas turbine and steam turbine power plant also increases. An increase in the dry solids content of the black liquor increases the effective gas flow from the gasifier or recovery boiler. Thereby, the electricity generation in the gas turbine increases as well as the steam generation in the waste heat boiler and consequently, also the electricity generation in the steam turbine.
In a combined power plant, the excess secondary steam generated in pressure heating may be converted to electric power by injecting the secondary steam into the gas turbine as injection steam. Injection steam is fed to the combustion gases in the gas turbine combustor. The pressure of the secondary steam has to be high enough for a successful feed into the pressurized gas. The steam injection also improves the conversion efficiency of electricity generation and the efficiency of the gas turbine and reduces the need for excess air to be introduced into the gas turbine by the compressor. In a gas turbine where the excess air level has been about 1.4, it may be lowered to about 1.15 because of steam injection.
20~4799 A change in the volume of air which has to be compressed in the compressor is an important parameter for the process. As injection of secondary steam into the combustion gas entering the gas turbine according to the invention also lowers the temperature of the combustion gas, the temperature of the gas entering the gas turbine vanes can be maintained constant by means of steam injection. Thereby, the amount of excess cooling air compressed in the compressor ca`n be decreased in proportion to the injected steam. In several gas turbines, the compressor is provided with a set of adjustable guide vanes. The output from the compressor may be adjusted by means of such vanes. An economic adjustment range is rather narrow, from 80 to 100%. The gas turbine may also be operated within another adjustment range, but in that case the combustion gas temperature probably decreases when the steam injection increases.
The secondary steams introduced into the gas turbine have to be cleaned prior to leading them into the turbine. The secondary steams from pressure heating contain, e.g., sulphur and alkali compounds and possibly also other harmful substances that have to be removed from the secondary steam prior to the gas turbine. The gases from the gasification stage have to be also purified. The gas flows are purified separately, which means that it is possible to use the most suitable purification method for the different harmful compounds of the secondary steam and the gas respectively. The gas purification processes may, however, be connected so that both systems use, for example, the same absorption mass. The actual purification takes place in separate equipment, but regeneration of the absorption mass may be effected in one and the same equipment, which saves costs. Purification of the secondary steam in a separate equipment provides efficient purification of a small secondary steam flow with relatively -simple means. Sulphur compounds are easier to remove from small quantities of secondary steam than from large quantities of combined steam and gas. Further, it is advantageous to remove sulphur compounds from the secondary steam prior to the sulphur compounds coming into contact with air in the gas turbine combustor. The pressurized secondary steam flow is relatively small and therefore also the plant needed for its purification. It is advantageous for the entire process if the gases may be purified at the highest possible temperature, whereby the heat energy contained in the gas may be utilized in the gas turbine.
Pressure heating may be effected at the same pressure as gasification or combustion, e.g., at about 20 bar. However, based on the values of the steam used for the heat treatment, the heat treatment may be arranged at a pressure which is either lower or higher than the pressure of the gasifier. Before introducing the gas into the gas turbine combustor, the pressure of the secondary steam from the heat treatment has to be adjusted by a pressure relief valve or by raising the pressure.
Pressure heating of black liquor and use of secondary steam as injection steam according to the invention is especially suitable for gasification of black liquor because the high dry solids content of black liquor has a very positive effect on the gasification of liquor. Thus, lowering the viscosity of the liquor by means of pressure heating contributes to the gasification process.
Gasification of black liquor having a high dry solids content produces gas of high heat value, which may be utilized effectively in a combined gas turbine and steam turbine power plant. The gasification is preferably effected at a high temperature, whereby the inorganic substance of 205~799 the black liquor is discharged from the reactor in a molten form, and the smelt may be further treated in a conventional manner.
The invention is further described in the following, by way of example, with reference to the accompanying drawing, which is a schematic illustration of a pressure heating system according to the invention, arranged in a black liquor gasification plant.
The gasification plant of the Figure comprises a black liquor gasification reactor 10, a pressure heating means 12, gas purification means 14, gas turbine power plant 16 and a steam turbine power plant 18.
Black liquor is fed by pump 22 into the pressure heating reactor 12. In the pressure heating reactor, black liquor is heated indirectly by leading reheat steam by duct 24 from the steam turbine power plant into a heat exchanger 26. The black liquor is heated to a temperature of, e.g, 180 - 200C. The pressure is about 10 to 20 bar in the pressure heating reactor.
Concentrated black liquor is led by duct 27 from the pressure heating stage to a final evaporation stage 28 and furthèr, via duct 29, into the gasifier 10. The water evaporated from the black liquor as well as other easily gasifying components are introduced via duct 30 into a steam purification means 15, where sulphur and other substances, such as alkali compounds, which are harmful to the gas turbine power plant are preferably removed from the secondary steams.
The gases formed in the actual gasifier 10 are led via duct 11 into a gas purification plant 17, where they are cleaned separately from the secondary steams coming from _ 20~479~
the pressure heating stage. The smelt formed in the gasifier is drained off through a chute 13.
From the gas purification plant, both the purified steam and the gas flows are taken through ducts 32 and 34 into a gas turbine combustor 36 for producing hot combustion gases. The secondary steam flow from duct 32 cools combustion gases produced in the combustor. The combustion gases and the secondary steam entrained therewith are led via duct 38 from the combustor into a gas turbine 40. A
generator 42 for generating electricity and a compressor 44 for producing compressed air are mounted on the same shaft as the gas turbine. Compressed air is conducted via duct 46 from the compressor into the gasifier 10 and via duct 48 into the combustor 36.
The exhaust gases from the gas turbine are led via duct 50 into a waste heat boiler 52 for utilizing the residual heat of the gases for steam generation. The cooled gases are led from the waste heat boiler via duct 54 into the stack.
In the steam turbine system 18, feed water is led by duct 58 from a feed water tank 56 into a steam generator 60 arranged in the waste heat boiler. The high pressure steam generated in the steam generator is led via duct 62 into a steam turbine 64. A generator 66 for electricity generation is mounted on the same shaft as the steam turbine. Reheat steam is taken out of the steam turbine and led via duct 24 into the pressure heater 12. Low pressure steam and possibly reheat steam is conducted from the steam turbine via ducts 68 and 70 to means 72, wherefrom the condensate is recirculated to the feed water tank 56 via duct 74. Also the condensated steam from the heat exchanger 26 is conducted via duct 76 into the feed water tank.
205~799 The pressure in the gasifier is preferably equal to the pressure in the pressure heating plant. In the embodiment of the Figure, the pressure in the gasifier is, however, higher than the pressure in the pressure heating plant, whereby a pressure raising means 78 is arranged after the pressure heating plant 12 for increasing the pressure of the secondary steam to the level of the pressure of the gas coming from the gasifier.
The arrangement described above is only an exemplary embodiment of the invention, and the details of the invention may vary and deviate from the above arrangement within the inventive scope defined by the accompanying claims.
Claims (16)
1. A method of treating black liquor in a sulphate pulp process, for recovering chemicals and heat therefrom, whereby - black liquor is evaporated for increasing the dry solids content thereof;
- the black liquor from the evaporator is gasified and/or combusted in a pressurized reactor for producing hot gases;
- the molten and/or solid salts formed in the reactor are introduced into a dissolving tank for recovering of cooking chemicals;
- the gases produced in the reactor are purified;
- the purified gases are introduced into a gas turbine for recovering their energy;
- the exhaust gases from the gas turbine are introduced into a waste heat boiler for generation of steam;
- energy is recovered from the generated steam in a steam turbine power plant;
wherein pressurized secondary steam from the sulphate pulp process is introduced as injection steam into the gas turbine combustor, to the combustion gases therein, prior to the gas turbine vanes, for regulating the gas turbine inlet temperature.
- the black liquor from the evaporator is gasified and/or combusted in a pressurized reactor for producing hot gases;
- the molten and/or solid salts formed in the reactor are introduced into a dissolving tank for recovering of cooking chemicals;
- the gases produced in the reactor are purified;
- the purified gases are introduced into a gas turbine for recovering their energy;
- the exhaust gases from the gas turbine are introduced into a waste heat boiler for generation of steam;
- energy is recovered from the generated steam in a steam turbine power plant;
wherein pressurized secondary steam from the sulphate pulp process is introduced as injection steam into the gas turbine combustor, to the combustion gases therein, prior to the gas turbine vanes, for regulating the gas turbine inlet temperature.
2. A method as claimed in claim 1, wherein - black liquor is pressure heated in heat exchanging contact with hot steam prior to gasification and/or combustion to concentrate the black liquor to a dry solids content, which is high in view of the whole, and - the secondary steam discharged from the black liquor in pressure heating is introduced into the gas turbine as injection steam.
3. A method as claimed in claim 1, wherein the pressure heating of black liquor is effected in an indirect heat exchanging contact with hot steam.
4. A method as claimed in claim 1, wherein the pressure heating of black liquor is effected in a direct heat exchanging contact with hot steam.
5. A method as claimed in claim 1, wherein the black liquor, which has been pressure heated and evaporated to a high dry solids content, is gasified for producing hot gases.
6. A method as claimed in claim 1, wherein black liquor is pressure heated by reheat steam coming from a steam turbine power plant.
7. A method as claimed in claim 1, wherein secondary steams are purified prior to leading them into a gas turbine.
8. A method as claimed in claim 7, wherein secondary steams are introduced into an absorbtion means for removing sulphur compounds from the gases.
9. A method as claimed in claim 7, wherein secondary steams and hot gases produced in gasification or combustion are purified in separate absorption means but with the same absorption mass.
10. A method as claimed in claim 7, wherein the secondary steams are purified for clearing them of alkali compounds.
11. A method as claimed in claim 1, wherein the final evaporation of black liquor is effected after pressure heating, prior to gasification and/or combustion.
12. A method as claimed in claim 2, wherein the pressure in pressure heating is the same as in the gasifier or in the combustion reactor.
13. A method as claimed in claim 2, wherein pressure heating is effected at a temperature of 180 to 200°C.
14. An arrangement for recovering black liquor chemicals and heat, comprising - black liquor evaporators (12, 28) for concentrating of black liquor;
- a pressurized reactor (10) for gasifying or combusting the black liquor concentrated in the evaporators;
- a gas purification means (17) for purifying the gas formed in the pressurized reactor;
- a gas turbine power plant (16) for recovering the energy from the purified gas;
- a waste heat boiler (52) for heat recovery from the turbine exhaust gas as pressurized steam and - a steam turbine power plant (18) for recovering the energy from the steam generated in the waste heat boiler, wherein the arrangement comprises a pressure heating reactor (12), serving as an evaporator of black liquor, which evaporator is connected to a gas turbine (40) or a gas turbine combus-tor (36) with a duct (30, 32), for leading the pressurized secondary steam from the pressure heating reactor as injection steam into the gas turbine.
- a pressurized reactor (10) for gasifying or combusting the black liquor concentrated in the evaporators;
- a gas purification means (17) for purifying the gas formed in the pressurized reactor;
- a gas turbine power plant (16) for recovering the energy from the purified gas;
- a waste heat boiler (52) for heat recovery from the turbine exhaust gas as pressurized steam and - a steam turbine power plant (18) for recovering the energy from the steam generated in the waste heat boiler, wherein the arrangement comprises a pressure heating reactor (12), serving as an evaporator of black liquor, which evaporator is connected to a gas turbine (40) or a gas turbine combus-tor (36) with a duct (30, 32), for leading the pressurized secondary steam from the pressure heating reactor as injection steam into the gas turbine.
15. An arrangement as claimed in claim 14, wherein a steam purification means (15) is arranged between the pressure heating reactor and the gas turbine power plant for puri-fying the secondary steam.
16. An arrangement as claimed in claim 14, wherein a pressure raising means (78) is arranged between the pressure heating reactor (12) and the gas turbine power plant for raising the pressure of the secondary steam prior to leading the secondary steam into the gas turbine power plant.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FI905507 | 1990-11-07 | ||
| FI905507A FI87092C (en) | 1990-11-07 | 1990-11-07 | FOERFARANDE FOER BEHANDLING AV SVARTLUT |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2054799A1 CA2054799A1 (en) | 1992-05-08 |
| CA2054799C true CA2054799C (en) | 1996-05-07 |
Family
ID=8531380
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002054799A Expired - Fee Related CA2054799C (en) | 1990-11-07 | 1991-11-05 | Method and arrangement for treating black liquor |
Country Status (6)
| Country | Link |
|---|---|
| US (1) | US5201172A (en) |
| JP (1) | JPH0663190B2 (en) |
| CA (1) | CA2054799C (en) |
| FI (1) | FI87092C (en) |
| FR (1) | FR2668784A1 (en) |
| SE (1) | SE9103277L (en) |
Families Citing this family (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FI84516B (en) * | 1990-04-03 | 1991-08-30 | Ahlstroem Oy | FOERFARANDE OCH ANORDNING FOER VAERME- OCH ELPRODUKTION I EN SULFATCELLULOSAFABRIK. |
| FI102395B (en) * | 1991-11-26 | 1998-11-30 | Ahlstrom Machinery Oy | Method for energy recovery from pulp process effluents |
| US5662774A (en) * | 1992-04-01 | 1997-09-02 | Tampella Power Oy | Adjusting the sulphur balance of a sulphate cellulose plant by heat treating black liquor in a last evaporation stage |
| US5439556A (en) * | 1993-08-16 | 1995-08-08 | The Boc Group, Inc. | Oxidation of white liquor using a packing column |
| TW245651B (en) * | 1994-02-24 | 1995-04-21 | Babcock & Wilcox Co | Black liquor gasifier |
| US5527427A (en) * | 1995-03-21 | 1996-06-18 | Optima Specialty Chemicals & Technology Inc. | High solids black liquor of reduced viscosity and viscosity reduction method for high solids black liquor |
| FI115229B (en) * | 1995-11-06 | 2005-03-31 | Kvaerner Power Oy | A method for reducing the corrosion of a pulp mill power boiler |
| PT1402153E (en) * | 2001-05-29 | 2013-10-10 | Andritz Oy | Method and arrangement for producing electrical energy at a pulp mill |
| US7685737B2 (en) | 2004-07-19 | 2010-03-30 | Earthrenew, Inc. | Process and system for drying and heat treating materials |
| US7024796B2 (en) * | 2004-07-19 | 2006-04-11 | Earthrenew, Inc. | Process and apparatus for manufacture of fertilizer products from manure and sewage |
| US7024800B2 (en) | 2004-07-19 | 2006-04-11 | Earthrenew, Inc. | Process and system for drying and heat treating materials |
| US7694523B2 (en) * | 2004-07-19 | 2010-04-13 | Earthrenew, Inc. | Control system for gas turbine in material treatment unit |
| US7610692B2 (en) | 2006-01-18 | 2009-11-03 | Earthrenew, Inc. | Systems for prevention of HAP emissions and for efficient drying/dehydration processes |
| US20100071370A1 (en) * | 2006-10-06 | 2010-03-25 | O'kane Pearse | Renewable energy recovery from msw and other wastes |
| DE102009043861A1 (en) * | 2009-08-26 | 2011-03-10 | Schönfelder Papierfabrik GmbH | Device for providing electrical energy and process heat in form of heat carrier medium, during manufacturing of paper, has gas turbine whose hot air serves as process heat carrier and is supplied to heat consumer |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4682985A (en) * | 1983-04-21 | 1987-07-28 | Rockwell International Corporation | Gasification of black liquor |
| FI75615C (en) * | 1985-11-29 | 1991-08-26 | Ahlstroem Oy | FOERFARANDE FOER SAENKNING AV SVARTLUTENS VISKOSITET. |
| FI81141B (en) * | 1986-09-22 | 1990-05-31 | Ahlstroem Oy | FOERFARANDE FOER KONCENTRERING AV UPPSLAMNINGAR. |
| SE462106B (en) * | 1986-11-28 | 1990-05-07 | Alf Ove Andersson | SETTING OUT EXTERNAL ENERGY AND CHEMICALS FROM PILLOW PREPARATION |
| US4878441A (en) * | 1988-08-11 | 1989-11-07 | Ahlstromforetagen Svenska Ab | Apparatus and process for generating steam from wet fuel |
| FI84516B (en) * | 1990-04-03 | 1991-08-30 | Ahlstroem Oy | FOERFARANDE OCH ANORDNING FOER VAERME- OCH ELPRODUKTION I EN SULFATCELLULOSAFABRIK. |
-
1990
- 1990-11-07 FI FI905507A patent/FI87092C/en not_active IP Right Cessation
-
1991
- 1991-11-05 US US07/787,901 patent/US5201172A/en not_active Expired - Fee Related
- 1991-11-05 CA CA002054799A patent/CA2054799C/en not_active Expired - Fee Related
- 1991-11-06 FR FR9113698A patent/FR2668784A1/en active Pending
- 1991-11-06 SE SE9103277A patent/SE9103277L/en not_active Application Discontinuation
- 1991-11-07 JP JP3350598A patent/JPH0663190B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH05186992A (en) | 1993-07-27 |
| FI905507A0 (en) | 1990-11-07 |
| SE9103277L (en) | 1992-05-08 |
| FI87092B (en) | 1992-08-14 |
| SE9103277D0 (en) | 1991-11-06 |
| FI87092C (en) | 1992-11-25 |
| US5201172A (en) | 1993-04-13 |
| FR2668784A1 (en) | 1992-05-07 |
| FI905507A (en) | 1992-05-08 |
| CA2054799A1 (en) | 1992-05-08 |
| JPH0663190B2 (en) | 1994-08-17 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US5507141A (en) | Process for recovering energy from a combustible gas | |
| CA2054799C (en) | Method and arrangement for treating black liquor | |
| US4808264A (en) | Process for chemicals and energy recovery from waste liquors | |
| EP2264287B1 (en) | Energy generating method using thermal cycles with high-pressure and moderate-temperature steam | |
| US20060048920A1 (en) | Energy reclaiming process | |
| US6647726B2 (en) | Method and arrangement for producing electrical energy at a pulp mill | |
| EP0523105B1 (en) | Method and apparatus for generating heat and electricity in a sulphate pulp mill | |
| EP0614500B1 (en) | Method of recovering energy from waste liquors from pulp processes | |
| SE527127C2 (en) | Process and apparatus for the production of thermal and electrical energy in a pulp mill | |
| EP1504154B2 (en) | Method of producing energy at a pulp mill | |
| WO1993024703A1 (en) | A process for recovering energy from a combustible gas | |
| SU1729296A3 (en) | Coal gasification method | |
| CA2512227A1 (en) | Energy reclaiming process | |
| FI73474B (en) | SAETT ATT AOTERVINNA VAERME OCH KEMIKALIER FRAON AVLUT. | |
| CA2491650C (en) | Method for treatment of spent liquor | |
| JPH06506506A (en) | Energy recovery method from waste liquid through pulp processing | |
| JPS6080002A (en) | Soda recovery boiler |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKLA | Lapsed |