CA1283760C - Process for the recovery of heat and chemicals from spent liquor - Google Patents
Process for the recovery of heat and chemicals from spent liquorInfo
- Publication number
- CA1283760C CA1283760C CA000547565A CA547565A CA1283760C CA 1283760 C CA1283760 C CA 1283760C CA 000547565 A CA000547565 A CA 000547565A CA 547565 A CA547565 A CA 547565A CA 1283760 C CA1283760 C CA 1283760C
- Authority
- CA
- Canada
- Prior art keywords
- liquor
- recovery boiler
- recovery
- chemicals
- concentrated
- 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 - Lifetime
Links
Classifications
-
- 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
Landscapes
- Paper (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
The invention relates to a process for the recovery of heat and chemicals from spent liquor by evaporating water out from it in order to concentrate the liquor and by feeding the con-centrated liquor thereby obtained and air into the recovery boiler. In order to increase the dry-matter content of the liquor to a level higher than usual, without at the same time increasing the viscosity of the liquor immoderately, at least the final concentrating of the liquor and its feeding into the recovery boiler are carried out under pressure at a tem-perature higher than the atmospheric boiling point of the li-quor.
The invention relates to a process for the recovery of heat and chemicals from spent liquor by evaporating water out from it in order to concentrate the liquor and by feeding the con-centrated liquor thereby obtained and air into the recovery boiler. In order to increase the dry-matter content of the liquor to a level higher than usual, without at the same time increasing the viscosity of the liquor immoderately, at least the final concentrating of the liquor and its feeding into the recovery boiler are carried out under pressure at a tem-perature higher than the atmospheric boiling point of the li-quor.
Description
~a37~0 A process for the recovery of heat and chemicals from spent liquor The present invention relates to a process for the recovery of heat and chemicals from spent liquor by evaporating water from the liquor in order to concentrate it and by feeding the concentrated liquor thereby obtained and air into a recovery boiler.
Spent liquor is produced in the pulping process, and for the economy of pulp production it is very important to recover the heat content and chemicals of this spent liquor as fully as possible. In order to release the thermal energy and to recover the chemicals, before the spent liquor is burned, wa-ter is evaporated out from it to such an extent that a liquor which contains water approximately 35 % or less is obtained, and this liquor is burned in the recovery boiler. ~he energy released during the combustion can be exploited in the pul-ping process, and the chemicals can be recovered from the bottom of the recovery boiler and, after regeneration, be used for preparing cooking liquor.
As the price of energy has risen continually, it has become increasingly important to make the burning of liquor in the recovery boiler as disturbance-free as possible in order to achieve good chemicals economy, low emissions, high energy efficiency, and good energy economy.
The primary function of the recovery boiler is to recover chemicals and to regenerate them for the preparation of cook-ing liquor. For this purpose a reducing zone is created in the lower part of the recovery boiler; a high temperature ~a3~760 prevails in this zone and a stack of the chemicals to be re-covered forms in the lower part of the furnace. Losses of chemicals, for their part, are used for measuring the recove-ry of the salts. Losses are incurred when gases, such as sul-fur dioxide, are emitted along with the flue gases.
It is also a function of the recovery boiler to recover heat from the flue gases. The effectiveness of the heat recovery can be measured in terms of the flue gas losses, i.e. the proportion of unburnt gases, and in terms of the usability of the furnace, for example stoppages due to the soilage of the heating surfaces.
The operation of the recovery boiler is affected by many fact-ors. The liquor fed into the recovery boiler usually contains ta~relatively high proportion of water, approximately 35-40 %.
This water amount must be caused to evaporate in the recovery boiler, and the evaporation must take place substantially from the liquor drops fal1ing towards the stack on the bottom of the recovery boiler, before the drops reach the surface of the stack. Otherwise a large proportion of the water must be evaporated from the surface of the stack, which decreases the temperature of the stack, and, in turn, increases the emis-sion of sulfur dioxide and decreases reduction.
If the content of water in the liquor decreases, also the combustion conditions improve so that the requirements set on recovery boilers are fulfilled to a greater extent, i.e.
emissions and losses of sulfur dioxide decrease, the reduc-tion improves, and the degree of heat recovery rises. At the same time the amount of flue gas decreases, whereupon the combustion capacity of the recovery boiler per volume unit increases. The usability of the boiler also improves.
~83760 In the previously known processes the spent l;quor is direc-ted, after concentration, into a storage and/or equilizing tank, from where it is pumped into the mixing tank. In the mixing tank, fly ash, and possibly make-up salt, is added to the liquor. Finally the liquor is pumped from the mixing tank into the recovery boiler. The tanks are open and are at at-mospheric pressure. To prevent vaporization, the operation must take place at temperatures which are below the boiling point of the liquor. The dry-matter content of the liquor is usually approximately 60 %, and at maximum 65-68 %, depending on the type of liquor.
At these dry-matter contents the viscosity of the liquor is still so low that the liquor can be treated and transferred at temperatures which are below its boiling point. When the dry-matter content further increases, also the viscosity in-creases, and since viscosity is dependent on the temperature, when the dry-matter content increases the temperature has to be further increased in order that the liquor could be trans-ferred and injected into the recovery boiler. Eventually, how-ever, the dry-matter content rises so high that the liquor becomes so viscous that it can no longer be treated using the equipment available.
The object of the present invention is therefore to provide a process for the recovery of heat and chemicals from spent liquor which has a dry-matter content higher than ordinary but which, nevertheless, can be transferred and injected into the recovery boiler.
The present invention thus provides a process for the recovery of heat and chemicals from spent liquor by evaporating water from the liquor to increase the concentration of solids the-rein by heating under pressure greater than atmospheric to a ~ Z83~7Ç~0 temperature above the atmospheric boiling point of the liquid, and pumping concentrated liquor into a recovery boiler while maintaining the raised pressure and temperature.
By carrying out the concentrating of the liquor and its feed-ing into the recovery boiler under pressure and at a tempe-rature higher than the atmospheric boiling point of the li-quor, in accordance with the invention, the liquor can be con-centrated to a dry-matter content higher than usual without the viscosity of the liquor being thereby raised to an unmana-geable level.
By the method according to the invention the liquor can be concentrated to a dry-matter content of over 65 /0, and even over 80 %, without insurmountable problems being yet caused by the viscosity of the liquor.
In a preferred embodiment of the invention, liquor is con-centrated and fed into the recovery boiler at a temperature of at least 115 C. Before being fed into the recovery boi-ler the liquor can be concentrated further by subiecting it to expansion evaporation, whereafter the pressure of the ex-pansion-evaporated liquor can be increased by mechanical pum-pung before it is fed into the recovery boiler.
Fly ash and/or make-up chemicals can be added to the liquor before it is concentrated. Alternatively, part of the fly ash can be blown into the combustion chamber of the recovery boil-er together with combustion air. The blowing of fly ash into the combustion chamber of the recovery boiler can also be carried out at a point below the point at which the liquor is injected.
3376(~
Water can be evaporated out from the liquor by using an eva-poration apparatus known per se, such as a falling-film type concentrator, by means of which the volume and dry-matter content of the liquor are regulated.
The invention is described below in greater detail with refe-rence to the accompanying drawings, in which Figure 1 is a flow chart of the apparatus intended for applying the process according to the invention, and Figure 2 depicts the tempera-ture dependence of the viscosity of a typical black liquor at different solids contents.
In the drawing, the mixing tank in general is indicated by reference numeral 2. A liquor which in a conventional evapor-ating plant has been evaporated to a dry-matter content of approximately 58-65 % is fed through pipe 1 into the mixing tank 2. In addition, fly ash can be fed through pipe 12 into the mixing tank 2. By means of pump 3, liquor is fed from the mixing tank 2 either directly into the recovery boiler 4 through pipe 13, or in accordance with the present invention through pipe 14 into an additional concentrator 5, in which the liquor is heated by means of steam, the condensate of the concentrator leaving through pipe 7. The concentrator 5 is closed and the evaporation of liquor in it takes place under pressure, in which case exploitable vapor 8 can be recovered from the upper part of the concentrator 5, and liquor having a dry-matter content of 65-80 % is pumped from the lower part through pipe 15 into the expansion tank 9, in which there prevails a pressure slightly lower than in the evaporator 5, so that part of the water present in the liquor is further vaporized. Vapor 10 at overpressure is recovered from the up-per part of the expansion tank 9 and liquor having a dry-matter content of over 80 ~ is removed from its lower part through pipe 16 and is pumped by means of pump 11 to the li-,.~, ~X8~3~7~0 quor nozzles of the recovery boiler 4. In the expansion tank9 the liquor can be concentrated to an even higher dry-matter content, while the temperature and pressure of the li-quor decrease, but not so much, however, that the viscosity of the liquor would rise so high that the liquor could not be pumped by means of pump 11 and be injected into the recovery boiler 4 by means of the liquor nozzles. Furthermore, by means of pump 11 the pressure of the liquor can be increased, and in order to lower the viscosity of the liquor, a less viscous liquor directly from the mixing tank 2 can be added to the liquor flowing in pipe 16. Furthermore, part of the liquor flowing in pipe 16 can be returned to the expansion tank 9.
The temperature of the liquor, and thereby its viscosity, can thus, when necessary, be adjusted by means of an expansion tank 9 placed between the concentrator and the combustion nozzles of the recovery boiler and by means of a preheater.
The temperature of the liquor can be lowered by expanding the liquor in the expansion tank 9 to the pressure corresponding to the desired temperature. When increase of the liquor tem-perature is desired, the liquor is heated by means of steam in an additional concentrator 5 serving as a preheater. When need be, the pressure of the liquor can be increased by pump 11 after the expansion tank 9.
The fly ash and the make-up chemicals 12 are fed either di-rectly into the combustion chamber of the recovery boiler 4 together with combustion air or into the mixing tank 2, which is located before the additional concentrator 5, or to both at a ratio appropriate in terms of the combustion.
, ~xa3t~0 By the method according to the invention the water content of the liquor can be lowered as much as to one-half of the pre-sent level. Thus it is clear that the combustion in the reco-very boiler will be substantially more economical. The com-bustion of liquor in the recovery boiler 4 can be regulated in, for example, the manner described in Finnish Lay-Open Print 6~409.
As is seen in greater detail in Figure 2, the viscosity of liquor is highly dependent on the temperature of the liquor, and the higher the solids content the sharper the rise of viscosity as the temperature rises. In practice, the pumping and injecting of black liquor is still possible when the ki-nematic viscosity is 200 cSt. It is seen in Figure 2 that the viscosity of liquor rises above 200 cSt when the dry-matter content of the liquor rises to approximately 69 % even if the temperature of the liquor is raised as high as possible under atmospheric pressure, i.e. to the atmospheric boiling point of the liquor. Thus the liquor must be heated in a pressure vessel if it is desired to increase the dry-matter content to above the above-mentioned value and pump it under pressure into the recovery boiler.
Spent liquor is produced in the pulping process, and for the economy of pulp production it is very important to recover the heat content and chemicals of this spent liquor as fully as possible. In order to release the thermal energy and to recover the chemicals, before the spent liquor is burned, wa-ter is evaporated out from it to such an extent that a liquor which contains water approximately 35 % or less is obtained, and this liquor is burned in the recovery boiler. ~he energy released during the combustion can be exploited in the pul-ping process, and the chemicals can be recovered from the bottom of the recovery boiler and, after regeneration, be used for preparing cooking liquor.
As the price of energy has risen continually, it has become increasingly important to make the burning of liquor in the recovery boiler as disturbance-free as possible in order to achieve good chemicals economy, low emissions, high energy efficiency, and good energy economy.
The primary function of the recovery boiler is to recover chemicals and to regenerate them for the preparation of cook-ing liquor. For this purpose a reducing zone is created in the lower part of the recovery boiler; a high temperature ~a3~760 prevails in this zone and a stack of the chemicals to be re-covered forms in the lower part of the furnace. Losses of chemicals, for their part, are used for measuring the recove-ry of the salts. Losses are incurred when gases, such as sul-fur dioxide, are emitted along with the flue gases.
It is also a function of the recovery boiler to recover heat from the flue gases. The effectiveness of the heat recovery can be measured in terms of the flue gas losses, i.e. the proportion of unburnt gases, and in terms of the usability of the furnace, for example stoppages due to the soilage of the heating surfaces.
The operation of the recovery boiler is affected by many fact-ors. The liquor fed into the recovery boiler usually contains ta~relatively high proportion of water, approximately 35-40 %.
This water amount must be caused to evaporate in the recovery boiler, and the evaporation must take place substantially from the liquor drops fal1ing towards the stack on the bottom of the recovery boiler, before the drops reach the surface of the stack. Otherwise a large proportion of the water must be evaporated from the surface of the stack, which decreases the temperature of the stack, and, in turn, increases the emis-sion of sulfur dioxide and decreases reduction.
If the content of water in the liquor decreases, also the combustion conditions improve so that the requirements set on recovery boilers are fulfilled to a greater extent, i.e.
emissions and losses of sulfur dioxide decrease, the reduc-tion improves, and the degree of heat recovery rises. At the same time the amount of flue gas decreases, whereupon the combustion capacity of the recovery boiler per volume unit increases. The usability of the boiler also improves.
~83760 In the previously known processes the spent l;quor is direc-ted, after concentration, into a storage and/or equilizing tank, from where it is pumped into the mixing tank. In the mixing tank, fly ash, and possibly make-up salt, is added to the liquor. Finally the liquor is pumped from the mixing tank into the recovery boiler. The tanks are open and are at at-mospheric pressure. To prevent vaporization, the operation must take place at temperatures which are below the boiling point of the liquor. The dry-matter content of the liquor is usually approximately 60 %, and at maximum 65-68 %, depending on the type of liquor.
At these dry-matter contents the viscosity of the liquor is still so low that the liquor can be treated and transferred at temperatures which are below its boiling point. When the dry-matter content further increases, also the viscosity in-creases, and since viscosity is dependent on the temperature, when the dry-matter content increases the temperature has to be further increased in order that the liquor could be trans-ferred and injected into the recovery boiler. Eventually, how-ever, the dry-matter content rises so high that the liquor becomes so viscous that it can no longer be treated using the equipment available.
The object of the present invention is therefore to provide a process for the recovery of heat and chemicals from spent liquor which has a dry-matter content higher than ordinary but which, nevertheless, can be transferred and injected into the recovery boiler.
The present invention thus provides a process for the recovery of heat and chemicals from spent liquor by evaporating water from the liquor to increase the concentration of solids the-rein by heating under pressure greater than atmospheric to a ~ Z83~7Ç~0 temperature above the atmospheric boiling point of the liquid, and pumping concentrated liquor into a recovery boiler while maintaining the raised pressure and temperature.
By carrying out the concentrating of the liquor and its feed-ing into the recovery boiler under pressure and at a tempe-rature higher than the atmospheric boiling point of the li-quor, in accordance with the invention, the liquor can be con-centrated to a dry-matter content higher than usual without the viscosity of the liquor being thereby raised to an unmana-geable level.
By the method according to the invention the liquor can be concentrated to a dry-matter content of over 65 /0, and even over 80 %, without insurmountable problems being yet caused by the viscosity of the liquor.
In a preferred embodiment of the invention, liquor is con-centrated and fed into the recovery boiler at a temperature of at least 115 C. Before being fed into the recovery boi-ler the liquor can be concentrated further by subiecting it to expansion evaporation, whereafter the pressure of the ex-pansion-evaporated liquor can be increased by mechanical pum-pung before it is fed into the recovery boiler.
Fly ash and/or make-up chemicals can be added to the liquor before it is concentrated. Alternatively, part of the fly ash can be blown into the combustion chamber of the recovery boil-er together with combustion air. The blowing of fly ash into the combustion chamber of the recovery boiler can also be carried out at a point below the point at which the liquor is injected.
3376(~
Water can be evaporated out from the liquor by using an eva-poration apparatus known per se, such as a falling-film type concentrator, by means of which the volume and dry-matter content of the liquor are regulated.
The invention is described below in greater detail with refe-rence to the accompanying drawings, in which Figure 1 is a flow chart of the apparatus intended for applying the process according to the invention, and Figure 2 depicts the tempera-ture dependence of the viscosity of a typical black liquor at different solids contents.
In the drawing, the mixing tank in general is indicated by reference numeral 2. A liquor which in a conventional evapor-ating plant has been evaporated to a dry-matter content of approximately 58-65 % is fed through pipe 1 into the mixing tank 2. In addition, fly ash can be fed through pipe 12 into the mixing tank 2. By means of pump 3, liquor is fed from the mixing tank 2 either directly into the recovery boiler 4 through pipe 13, or in accordance with the present invention through pipe 14 into an additional concentrator 5, in which the liquor is heated by means of steam, the condensate of the concentrator leaving through pipe 7. The concentrator 5 is closed and the evaporation of liquor in it takes place under pressure, in which case exploitable vapor 8 can be recovered from the upper part of the concentrator 5, and liquor having a dry-matter content of 65-80 % is pumped from the lower part through pipe 15 into the expansion tank 9, in which there prevails a pressure slightly lower than in the evaporator 5, so that part of the water present in the liquor is further vaporized. Vapor 10 at overpressure is recovered from the up-per part of the expansion tank 9 and liquor having a dry-matter content of over 80 ~ is removed from its lower part through pipe 16 and is pumped by means of pump 11 to the li-,.~, ~X8~3~7~0 quor nozzles of the recovery boiler 4. In the expansion tank9 the liquor can be concentrated to an even higher dry-matter content, while the temperature and pressure of the li-quor decrease, but not so much, however, that the viscosity of the liquor would rise so high that the liquor could not be pumped by means of pump 11 and be injected into the recovery boiler 4 by means of the liquor nozzles. Furthermore, by means of pump 11 the pressure of the liquor can be increased, and in order to lower the viscosity of the liquor, a less viscous liquor directly from the mixing tank 2 can be added to the liquor flowing in pipe 16. Furthermore, part of the liquor flowing in pipe 16 can be returned to the expansion tank 9.
The temperature of the liquor, and thereby its viscosity, can thus, when necessary, be adjusted by means of an expansion tank 9 placed between the concentrator and the combustion nozzles of the recovery boiler and by means of a preheater.
The temperature of the liquor can be lowered by expanding the liquor in the expansion tank 9 to the pressure corresponding to the desired temperature. When increase of the liquor tem-perature is desired, the liquor is heated by means of steam in an additional concentrator 5 serving as a preheater. When need be, the pressure of the liquor can be increased by pump 11 after the expansion tank 9.
The fly ash and the make-up chemicals 12 are fed either di-rectly into the combustion chamber of the recovery boiler 4 together with combustion air or into the mixing tank 2, which is located before the additional concentrator 5, or to both at a ratio appropriate in terms of the combustion.
, ~xa3t~0 By the method according to the invention the water content of the liquor can be lowered as much as to one-half of the pre-sent level. Thus it is clear that the combustion in the reco-very boiler will be substantially more economical. The com-bustion of liquor in the recovery boiler 4 can be regulated in, for example, the manner described in Finnish Lay-Open Print 6~409.
As is seen in greater detail in Figure 2, the viscosity of liquor is highly dependent on the temperature of the liquor, and the higher the solids content the sharper the rise of viscosity as the temperature rises. In practice, the pumping and injecting of black liquor is still possible when the ki-nematic viscosity is 200 cSt. It is seen in Figure 2 that the viscosity of liquor rises above 200 cSt when the dry-matter content of the liquor rises to approximately 69 % even if the temperature of the liquor is raised as high as possible under atmospheric pressure, i.e. to the atmospheric boiling point of the liquor. Thus the liquor must be heated in a pressure vessel if it is desired to increase the dry-matter content to above the above-mentioned value and pump it under pressure into the recovery boiler.
Claims (6)
1. A process for the recovery of heat and chemicals from spent liquor characterized by the steps of:
evaporating water from the liquor to increase the concentration of solids therein by heating under pressure greater than atmospheric to a temperature above the atmospheric boiling point of the liquid, and pumping concentrated liquor into a recovery boiler while maintaining the raised pressure and temperature.
evaporating water from the liquor to increase the concentration of solids therein by heating under pressure greater than atmospheric to a temperature above the atmospheric boiling point of the liquid, and pumping concentrated liquor into a recovery boiler while maintaining the raised pressure and temperature.
2. A process according to Claim 1, characterized in that the liquor is concentrated to a dry-matter content above 65 %.
3. A process according to Claim 1 or 2, characterized in that the liquor is concentrated and fed into the recovery boiler at a temperature of at least 115°C.
4. A process according to Claim 1, characterized in that the concentrated liquor is subjected to expansion evaporation before it is fed into the recovery boiler.
5. A process according to Claim 4, characterized in that the pressure of the expansion-evaporated liquid is increased by mechanical pumping before it is fed into the recovery boiler.
6. A process according to claim 1 or 2, characterized in that the liquor is concentrated and fed into the recovery boiler and at a temperature of at least 115°C and the liquor which is concentrated contains fly ash or make-up chemicals.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000547565A CA1283760C (en) | 1987-09-23 | 1987-09-23 | Process for the recovery of heat and chemicals from spent liquor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000547565A CA1283760C (en) | 1987-09-23 | 1987-09-23 | Process for the recovery of heat and chemicals from spent liquor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1283760C true CA1283760C (en) | 1991-05-07 |
Family
ID=4136502
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000547565A Expired - Lifetime CA1283760C (en) | 1987-09-23 | 1987-09-23 | Process for the recovery of heat and chemicals from spent liquor |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1283760C (en) |
-
1987
- 1987-09-23 CA CA000547565A patent/CA1283760C/en not_active Expired - Lifetime
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| SE9703680D0 (en) | Heat recovery from boiling liquor from a boiler | |
| IT1008172B (en) | IMPROVEMENT IN VAPOR COMPRESSION DISTILLATION PLANTS | |
| CN1130517C (en) | Combination plant with mixed-pressure boiler | |
| CA2054799C (en) | Method and arrangement for treating black liquor | |
| GB463770A (en) | An improved process for evaporating liquids | |
| US3912577A (en) | Method and apparatus for treatment of liquid wastes | |
| US5112441A (en) | Process for the recovery of heat and chemicals from spent liquor | |
| US4619732A (en) | Method for drying pulping liquor to a burnable solid | |
| CA1283760C (en) | Process for the recovery of heat and chemicals from spent liquor | |
| EP0588392A1 (en) | Steam and gas turbine power plant using moistened natural gas | |
| US2747552A (en) | Method of generating vapour from waste sulfite liquor or dregs | |
| EP0207908A1 (en) | Process for increasing the solids content of black liquour at its recovery in a sulfate pulping process | |
| CN1057360C (en) | Alkali recovery from waste liquid of grass pulp papermaking by multi-point drying and burning | |
| EP0639254B1 (en) | Method in small-power plant use | |
| CN1059165A (en) | Secondary reformer gas station phenol water treatment technique and device | |
| US1779535A (en) | Process of treating black liquors | |
| GB1558944A (en) | Treatment of waste | |
| US3780786A (en) | Direct contact evaporators | |
| US20010023750A1 (en) | Method and arrangement for combusting black liquor | |
| SU52223A1 (en) | Installation for evaporation of phenolic waters of gas generating stations | |
| JPS5895102A (en) | Deaerator | |
| RU2256124C1 (en) | Method of preparation of water-and-coal fuel for burning in power boiler plant | |
| CA1293097C (en) | Method of concentrating sludges | |
| GB2142420A (en) | De-aeration of water | |
| CN206918984U (en) | Boiler heating power deaerating type of cycles |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |