CA1204063A - Method for draining a peat-bath suspension - Google Patents
Method for draining a peat-bath suspensionInfo
- Publication number
- CA1204063A CA1204063A CA000427941A CA427941A CA1204063A CA 1204063 A CA1204063 A CA 1204063A CA 000427941 A CA000427941 A CA 000427941A CA 427941 A CA427941 A CA 427941A CA 1204063 A CA1204063 A CA 1204063A
- Authority
- CA
- Canada
- Prior art keywords
- suspension
- water
- separated
- fibres
- stage
- 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
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10F—DRYING OR WORKING-UP OF PEAT
- C10F5/00—Drying or de-watering peat
- C10F5/04—Drying or de-watering peat by using presses, handpresses, rolls, or centrifuges
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D36/00—Filter circuits or combinations of filters with other separating devices
- B01D36/02—Combinations of filters of different kinds
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B30—PRESSES
- B30B—PRESSES IN GENERAL
- B30B9/00—Presses specially adapted for particular purposes
- B30B9/02—Presses specially adapted for particular purposes for squeezing-out liquid from liquid-containing material, e.g. juice from fruits, oil from oil-containing material
- B30B9/24—Presses specially adapted for particular purposes for squeezing-out liquid from liquid-containing material, e.g. juice from fruits, oil from oil-containing material using an endless pressing band
- B30B9/246—The material being conveyed around a drum between pressing bands
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Organic Chemistry (AREA)
- Treatment Of Sludge (AREA)
- Filtration Of Liquid (AREA)
Abstract
ABSTRACT
For the purpose of recovering and transporting in a non-environ-mentally polluting economical manner the solid substance of a peat bath suspension or of a similar aqueous, homogeneous suspension having a low 2 to 5%
solid content principally of organic fibres, the present invention provides a method for draining the said suspension by passing it continuously through a static filtration stage having curved or inclined screens where at least a part of the present free water is separated from the suspension to a resulting water content of 90 to 94% therein; a first mechanical double belt screen pressure stage where the remainder of the free water and some of the combined water which is bound and latent in the fibres is separated from the suspension to a result-ing water content of less than 90% merely by the pressure arising from the tension of the belt screens; and a second double belt screen pressure stage where the belt screens pass between pressure rollers and where more of the combined water of the fibres is separated from the material to a water content of 80.%, the filtrate arising in the first stage being first purified and then fed to a sewage system with a solid content of at the most 1 gram per litre of water. The fraction still containing fines, separated during purification, is returned to the process for draining.
For the purpose of recovering and transporting in a non-environ-mentally polluting economical manner the solid substance of a peat bath suspension or of a similar aqueous, homogeneous suspension having a low 2 to 5%
solid content principally of organic fibres, the present invention provides a method for draining the said suspension by passing it continuously through a static filtration stage having curved or inclined screens where at least a part of the present free water is separated from the suspension to a resulting water content of 90 to 94% therein; a first mechanical double belt screen pressure stage where the remainder of the free water and some of the combined water which is bound and latent in the fibres is separated from the suspension to a result-ing water content of less than 90% merely by the pressure arising from the tension of the belt screens; and a second double belt screen pressure stage where the belt screens pass between pressure rollers and where more of the combined water of the fibres is separated from the material to a water content of 80.%, the filtrate arising in the first stage being first purified and then fed to a sewage system with a solid content of at the most 1 gram per litre of water. The fraction still containing fines, separated during purification, is returned to the process for draining.
Description
The invention relates to a method for draining a peat bath suspension or a similar aqueous, homogeneous suspension having a low 2 to 5% solid content of principally organic fibres.
The term "peat bath suspension" is intended to mean an aqueous sus-pension of na~ural peat containing a small proportion (2 to 5%) of fine peat fibres. In the peat bath, the natural peat is mixed with water and the suspen-sion is homogenized, the peat being broken down into fibres thereby producing a thin sludge used for therapeutical purposes in temperature controlled bath tubs. Disposal of the used suspension :Erom the bath presents a technical pro-blem. If the bath is close to a peat deposit, the peat suspension is usually pumped back into the deposit and allowed to regenerate naturally. Even in such localities, however, the excess water in the suspension impairs the sub-soil to surface water ratio.
The problem is more serious in urban areas, for example, in ortho-ped:ic clinics which prepare suspensions of this nature for baths from fresh peat delivered in dewatered and compacted condition. On the one hand, the suspension cannot be drained into the communal sewage system and, on the other hancl, the valuable peat material is worth recovering for recycling.
There has so far been no satisfactory solution to the problem. A
satisfactory solution, whereby the suspension is drained so that the drained peat product may be transported by truck and the separated filtrate can be drain-ed into, for example, a public sewage system is one object o:E the invention.
~'urthermore, it is desired to carry out the draining process as inexpensively as possible, with simple means, and without flocculants added. It is also desirable to process between 6 and 10 m3/h of suspension.
This purpose is accomplished by the present invention which provides a method for draining a peat bath suspension or a similar aqueous, homogeneous suspension having a low 2 to 5% solid content mainly of organic fibres, char-acterized in that the suspension to be drained is passed continuously through the following processing stages:
a) a static filtration stage where at least some of the present free water is separated from the suspension by means of curved or inclined screens to a water content of 90 to 94%:
b) a first mechanical double belt screen pressure stage where the remainder of the free water, and some of the combined water which is bound and latent in the fibres is separated from the suspension to a resulting water content of less than 90% merely by the pressure arising from -the tension of the belt screens;
c) a second double belt screen stage where the belt scree~ are passed between pressure rollers and where more of the combined water of -the fibres is separated from the material to a water content of 80%, the separated filtrate being first purified and then fed to a sewage system with a solid content of at the most 1 gram per litre of water.
The method according to the invention and the means whereby the said method is implemented ar0 described in greater detail and explained hereinafter.
The description relates to the installation for the implementation of the method which is illustrated diagrammatically in the figure attached hereto.
The peat bath suspension to be drained is a homogeneously prepared thin sludge made of comminuted peat and wa-ter. The solid content of -this suspension amounts to between 2 and 5%, the remainder being water.
The solid is mainly finely divided peat fibre swollen with and sur-rounded by water. Most of the water, about 95%, is combined in the fibres, i.e. is contained, bound and latent in the swollen structure of the fibres.
The remainder of the water is the present f:ree water surrounding the fibres.
The said combined water can be s~ueezed out oE the fibres with only a certain amount of external pressure.
Ihe peat suspension to be drained is passed through a line 1 into a container 2. Other components which are also fed into this container are men-tioned hereinafter. The suspension mixed in the container overflows into a vertical box 3, passing through the outlet therefrom to a sta-tic filtration stage consisting of an inclined filter 4 or of one or more sloping filter sur-faces S arranged one behind or one above the other. The second of these filter surfaces is shown in dotted lines in the drawing. The solid material remains on the top of the filter sur-faces, while the filtrate, mainly the free water separated from the suspension, passes through the filter surfaces to the collec--tor tank thereunder 6, where it is removed through a line 7. The solid material which remains on the fil~er surface gradually slides to the bottom of the sloping filter surface.
In this static filtration stage~ use may be made of an inclined filter known as the "Kenfill"* but units having curved screen surfaces, so-called curved filters, may also be used.
In the static filtration stage at least some of the free water is separated from the suspension and the material thereafter contains, after filter-ing device 4, a water content of 92 to 94%. In this partly drained condition, the material 8 falls from filter ~ onto lower belt screen 9 of a double belt screen press. Between the lower belt 9 and the upper belt 10 of the press, the material enters a first double belt screen pressure stage where both belts form a loop around a deflecting roller 11. Thus, the suspension material between the belts is subjected as it passes around the deflecting roller, only to the pressure produced by the tension of the belt screens. The pressure in this first *Irade mark 3 pressure stage is enough to separate any residual -free water from the suspension as well as some of the combined water of the fibres which passes through the screen belts.
After this stage the material between the belt screens contains less than 90% water and is well distributed over the surface between the belts. It is now in a so-called stabilized condition so that the layer of material no longer floats between the bel~ screens and is not milled. The material is no longer displaced laterally out of the space between belt screens 9, 10 under the influence of the squeezed out filtrate.
In this condition the material passes between belt screens 9, 10 into a second pressure stage consisting of at least one pair of pressure rollers.
The pressure stage shown in the figure comprises a deflecting roller 12 and two pressure rollers 13, 14. The mutual pressure from these rollers separates more o:E the combined water from the material between the belt screens so that the product emerging at 15 has the desired residual moisture, that is, a water con-tent of 78 to 8~%. In this condition, the recovered peat product, may be transported loose in open trucks and may be delivered to a peat deposit, for exatnple~ for natural regeneration.
The filtrate arising in the first and second stage is passed by a
The term "peat bath suspension" is intended to mean an aqueous sus-pension of na~ural peat containing a small proportion (2 to 5%) of fine peat fibres. In the peat bath, the natural peat is mixed with water and the suspen-sion is homogenized, the peat being broken down into fibres thereby producing a thin sludge used for therapeutical purposes in temperature controlled bath tubs. Disposal of the used suspension :Erom the bath presents a technical pro-blem. If the bath is close to a peat deposit, the peat suspension is usually pumped back into the deposit and allowed to regenerate naturally. Even in such localities, however, the excess water in the suspension impairs the sub-soil to surface water ratio.
The problem is more serious in urban areas, for example, in ortho-ped:ic clinics which prepare suspensions of this nature for baths from fresh peat delivered in dewatered and compacted condition. On the one hand, the suspension cannot be drained into the communal sewage system and, on the other hancl, the valuable peat material is worth recovering for recycling.
There has so far been no satisfactory solution to the problem. A
satisfactory solution, whereby the suspension is drained so that the drained peat product may be transported by truck and the separated filtrate can be drain-ed into, for example, a public sewage system is one object o:E the invention.
~'urthermore, it is desired to carry out the draining process as inexpensively as possible, with simple means, and without flocculants added. It is also desirable to process between 6 and 10 m3/h of suspension.
This purpose is accomplished by the present invention which provides a method for draining a peat bath suspension or a similar aqueous, homogeneous suspension having a low 2 to 5% solid content mainly of organic fibres, char-acterized in that the suspension to be drained is passed continuously through the following processing stages:
a) a static filtration stage where at least some of the present free water is separated from the suspension by means of curved or inclined screens to a water content of 90 to 94%:
b) a first mechanical double belt screen pressure stage where the remainder of the free water, and some of the combined water which is bound and latent in the fibres is separated from the suspension to a resulting water content of less than 90% merely by the pressure arising from -the tension of the belt screens;
c) a second double belt screen stage where the belt scree~ are passed between pressure rollers and where more of the combined water of -the fibres is separated from the material to a water content of 80%, the separated filtrate being first purified and then fed to a sewage system with a solid content of at the most 1 gram per litre of water.
The method according to the invention and the means whereby the said method is implemented ar0 described in greater detail and explained hereinafter.
The description relates to the installation for the implementation of the method which is illustrated diagrammatically in the figure attached hereto.
The peat bath suspension to be drained is a homogeneously prepared thin sludge made of comminuted peat and wa-ter. The solid content of -this suspension amounts to between 2 and 5%, the remainder being water.
The solid is mainly finely divided peat fibre swollen with and sur-rounded by water. Most of the water, about 95%, is combined in the fibres, i.e. is contained, bound and latent in the swollen structure of the fibres.
The remainder of the water is the present f:ree water surrounding the fibres.
The said combined water can be s~ueezed out oE the fibres with only a certain amount of external pressure.
Ihe peat suspension to be drained is passed through a line 1 into a container 2. Other components which are also fed into this container are men-tioned hereinafter. The suspension mixed in the container overflows into a vertical box 3, passing through the outlet therefrom to a sta-tic filtration stage consisting of an inclined filter 4 or of one or more sloping filter sur-faces S arranged one behind or one above the other. The second of these filter surfaces is shown in dotted lines in the drawing. The solid material remains on the top of the filter sur-faces, while the filtrate, mainly the free water separated from the suspension, passes through the filter surfaces to the collec--tor tank thereunder 6, where it is removed through a line 7. The solid material which remains on the fil~er surface gradually slides to the bottom of the sloping filter surface.
In this static filtration stage~ use may be made of an inclined filter known as the "Kenfill"* but units having curved screen surfaces, so-called curved filters, may also be used.
In the static filtration stage at least some of the free water is separated from the suspension and the material thereafter contains, after filter-ing device 4, a water content of 92 to 94%. In this partly drained condition, the material 8 falls from filter ~ onto lower belt screen 9 of a double belt screen press. Between the lower belt 9 and the upper belt 10 of the press, the material enters a first double belt screen pressure stage where both belts form a loop around a deflecting roller 11. Thus, the suspension material between the belts is subjected as it passes around the deflecting roller, only to the pressure produced by the tension of the belt screens. The pressure in this first *Irade mark 3 pressure stage is enough to separate any residual -free water from the suspension as well as some of the combined water of the fibres which passes through the screen belts.
After this stage the material between the belt screens contains less than 90% water and is well distributed over the surface between the belts. It is now in a so-called stabilized condition so that the layer of material no longer floats between the bel~ screens and is not milled. The material is no longer displaced laterally out of the space between belt screens 9, 10 under the influence of the squeezed out filtrate.
In this condition the material passes between belt screens 9, 10 into a second pressure stage consisting of at least one pair of pressure rollers.
The pressure stage shown in the figure comprises a deflecting roller 12 and two pressure rollers 13, 14. The mutual pressure from these rollers separates more o:E the combined water from the material between the belt screens so that the product emerging at 15 has the desired residual moisture, that is, a water con-tent of 78 to 8~%. In this condition, the recovered peat product, may be transported loose in open trucks and may be delivered to a peat deposit, for exatnple~ for natural regeneration.
The filtrate arising in the first and second stage is passed by a
2() trapping device 161 to a collector trough 16 and, si.nce it contains fine peat fibres, is fed by a pump 1~ through a line 18 back to container 2 where it is mixed with the incoming suspension to be drained. The fibres which floated away with the filtrate a.re thus returned to the process. Almost no peat substance is lost.
The flushing water, which also carries fibres, is treated in a similar manner, being passed to a shower 19 for upper belt screen 10 and to a shower 20 for lower belt screen ~. The collected water passes from shower 19 through a line 21 also to container 2 where it mixes with the incoming fresh suspension while the water from shower 20 flows into collector trough 16 and is returned, with the filtrate therei.n to container 2 as described above The filtrate arising in the second pressure stage comprising rollers 12, 13, 14, is collected in a manner si.milar to that described for the first stage and is also passed to contai.ner 2. For the sake of simplicity, the relevant devices are not shown in the figure.
The filtrate arising at inclined filter 4 carried away through line 7 is treated by means of a sand filter 22, for example as in the figure, and is purified. A suitable device for this purpose would be a se].f cleaning "Dynasand" filter which is commercially available. The purified fraction which after leaving filter 22 contains at the most 1 gram of so].id material per litre of water, passes through a line 23 to a water tank 24. The remaining fraction containing fines is passed by a pump 25 through a line 26 to container 2 where it is mixed with fresh suspension.
According to the method, all filtrates and fractions still containing an appreciable amount of fibre are returned to the process thereby resulting in very l:ittle peat substance loss.
The purified water from tank 2~ passes through pump 27 and lines 28, 29 and is used to clean the belt screens by means of showers 19 and 20. Excess water from tank 2~ flows over a weir 30 to a sewage system 31.
It is an advantage for pressure rollers 12, 13~ 14 which constitute the second belt screen pressure stage to have chequered or waffle pattern sur-faces since these allow the filtrate flowing through belt screens 9, 10 to be more satisfactorily trapped and carried away, a.nd the peat cake to be better fixed.
The method described is inexpensive since the installation described *Trade mark 5 hereinbefore may be designed to be highly compact with short paths and belt screen tracks. Operating costs are low si.nce a part of the draining is carried out by means of static equi.pment which incur no power costs. The compact in-stallation welghs about 1.5 t and, in spite of its small dimensions, is capable of processing between 6 and 10 m3/h of suspension.
This method is not limited to the draining of peat bath suspensions, but may also be used to drain other thin suspensions of the same type, for ex-ample, an aqueous suspension containing small amounts of wood .fibres, wood flour or saw dust suspencled in water, or the like.
The method is also not limited to a product having a residual mois-ture oE above 80%. Should it be desirable or necessary, it is a simple matter to achieve residual moistures ofless than 80~ with a similarly compa.ct installation, for example, by increasing the pressure in the second double belt screen pressure stage, or by adding to this stage another pair of pressure rollers.
One particular advantage of the method is that drai.ning may be carried out without any chemical, organic or inorganic additives such as so-called :flocculating agents or flocculants and this is essential from the medi.cinal point o:E view if the peat bath suspension is to be reused.
The flushing water, which also carries fibres, is treated in a similar manner, being passed to a shower 19 for upper belt screen 10 and to a shower 20 for lower belt screen ~. The collected water passes from shower 19 through a line 21 also to container 2 where it mixes with the incoming fresh suspension while the water from shower 20 flows into collector trough 16 and is returned, with the filtrate therei.n to container 2 as described above The filtrate arising in the second pressure stage comprising rollers 12, 13, 14, is collected in a manner si.milar to that described for the first stage and is also passed to contai.ner 2. For the sake of simplicity, the relevant devices are not shown in the figure.
The filtrate arising at inclined filter 4 carried away through line 7 is treated by means of a sand filter 22, for example as in the figure, and is purified. A suitable device for this purpose would be a se].f cleaning "Dynasand" filter which is commercially available. The purified fraction which after leaving filter 22 contains at the most 1 gram of so].id material per litre of water, passes through a line 23 to a water tank 24. The remaining fraction containing fines is passed by a pump 25 through a line 26 to container 2 where it is mixed with fresh suspension.
According to the method, all filtrates and fractions still containing an appreciable amount of fibre are returned to the process thereby resulting in very l:ittle peat substance loss.
The purified water from tank 2~ passes through pump 27 and lines 28, 29 and is used to clean the belt screens by means of showers 19 and 20. Excess water from tank 2~ flows over a weir 30 to a sewage system 31.
It is an advantage for pressure rollers 12, 13~ 14 which constitute the second belt screen pressure stage to have chequered or waffle pattern sur-faces since these allow the filtrate flowing through belt screens 9, 10 to be more satisfactorily trapped and carried away, a.nd the peat cake to be better fixed.
The method described is inexpensive since the installation described *Trade mark 5 hereinbefore may be designed to be highly compact with short paths and belt screen tracks. Operating costs are low si.nce a part of the draining is carried out by means of static equi.pment which incur no power costs. The compact in-stallation welghs about 1.5 t and, in spite of its small dimensions, is capable of processing between 6 and 10 m3/h of suspension.
This method is not limited to the draining of peat bath suspensions, but may also be used to drain other thin suspensions of the same type, for ex-ample, an aqueous suspension containing small amounts of wood .fibres, wood flour or saw dust suspencled in water, or the like.
The method is also not limited to a product having a residual mois-ture oE above 80%. Should it be desirable or necessary, it is a simple matter to achieve residual moistures ofless than 80~ with a similarly compa.ct installation, for example, by increasing the pressure in the second double belt screen pressure stage, or by adding to this stage another pair of pressure rollers.
One particular advantage of the method is that drai.ning may be carried out without any chemical, organic or inorganic additives such as so-called :flocculating agents or flocculants and this is essential from the medi.cinal point o:E view if the peat bath suspension is to be reused.
Claims (5)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method for draining a peat bath suspension or a similar aqueous, homogeneous suspension having a low 2 to 5% solid content mainly of organic fibres, characterized in that the suspension to be drained is passed continuously through the following processing stages:
a) a static filtration stage where at least some of the present free water is separated from the suspension by means of curved or inclined screens to a resulting water content of 90 to 94%;
b) a first mechanical double belt screen pressure stage where the remainder of the free water and some of the combined water which is bound and latent in the fibres is separated from the suspension to a resulting water con-tent of less than 90% merely by the pressure arising from the tension of the belt screens;
c) a second double belt screen pressure stage where the belt screens are passed between pressure rollers and where more of the combined water in the fibres is separated from the material to a water content of 80%, the separated filtrate being first purified and then fed to a sewage system with a solid content of at the most 1 gram per litre of water.
a) a static filtration stage where at least some of the present free water is separated from the suspension by means of curved or inclined screens to a resulting water content of 90 to 94%;
b) a first mechanical double belt screen pressure stage where the remainder of the free water and some of the combined water which is bound and latent in the fibres is separated from the suspension to a resulting water con-tent of less than 90% merely by the pressure arising from the tension of the belt screens;
c) a second double belt screen pressure stage where the belt screens are passed between pressure rollers and where more of the combined water in the fibres is separated from the material to a water content of 80%, the separated filtrate being first purified and then fed to a sewage system with a solid content of at the most 1 gram per litre of water.
2. A method according to claim 1, characterized in that in the static filtration stage, use is made of an inclined screen device comprising two fil-tration surfaces arranged one behind the other.
3. A method according to claim 1, characterized in that the purified filtrate is returned to the process for cleaning the belt screens.
4. A method according to claim 1, characterized in that a sand filter is used to purify the filtrate.
5. A method according to claim 1, characterized in that in the second double belt screen pressure stage, use is made of pressure rollers, the surfacesof which have a chequered or waffle pattern.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CH2951/82-5 | 1982-05-12 | ||
| CH295182A CH657280A5 (en) | 1982-05-12 | 1982-05-12 | METHOD FOR DRAINING A SUSPENSION. |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1204063A true CA1204063A (en) | 1986-05-06 |
Family
ID=4245311
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000427941A Expired CA1204063A (en) | 1982-05-12 | 1983-05-11 | Method for draining a peat-bath suspension |
Country Status (4)
| Country | Link |
|---|---|
| AT (1) | ATA107483A (en) |
| CA (1) | CA1204063A (en) |
| CH (1) | CH657280A5 (en) |
| DE (1) | DE3311961A1 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4365934A (en) * | 1981-06-15 | 1982-12-28 | Mason H Carl | Wind machine |
| CN104924149B (en) * | 2015-05-22 | 2017-10-31 | 蚌埠市金林数控机床制造有限公司 | A kind of lathe that function is reclaimed with lubricating oil |
-
1982
- 1982-05-12 CH CH295182A patent/CH657280A5/en not_active IP Right Cessation
-
1983
- 1983-03-28 AT AT107483A patent/ATA107483A/en not_active IP Right Cessation
- 1983-03-31 DE DE19833311961 patent/DE3311961A1/en not_active Withdrawn
- 1983-05-11 CA CA000427941A patent/CA1204063A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| ATA107483A (en) | 1987-08-15 |
| CH657280A5 (en) | 1986-08-29 |
| DE3311961A1 (en) | 1983-11-17 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |