Title of Invention	METHOD FOR PURIFYING AN EVAPORATION PRODUCT TO PRODUCE STEAM AND A DEVICE THEREFOR
Abstract	There is disclosed a method for purifying an evaporation product to produce pure steam, wherein the evaporation product is set in a spiraling rotational motion to separate droplets by centrifugal force, characterized by providing an evaporation product by means of a falling film evaporator (22) conducting said evaporation product into an annular rising channel comprising spiral fins (11) forming a spiral path (12), providing at least one opening (13) in the outer surface of said spiral path, collecting droplets and impurities on an actively cooled surface outside said opening or openings. A device for carrying out the method is also disclosed.

Title of Invention

METHOD FOR PURIFYING AN EVAPORATION PRODUCT TO PRODUCE STEAM AND A DEVICE THEREFOR

Abstract

There is disclosed a method for purifying an evaporation product to produce pure steam, wherein the evaporation product is set in a spiraling rotational motion to separate droplets by centrifugal force, characterized by providing an evaporation product by means of a falling film evaporator (22) conducting said evaporation product into an annular rising channel comprising spiral fins (11) forming a spiral path (12), providing at least one opening (13) in the outer surface of said spiral path, collecting droplets and impurities on an actively cooled surface outside said opening or openings. A device for carrying out the method is also disclosed.

Full Text	METHOD FOR PURIFYING AN EVAPORATION PRODUCT TO PRODUCE STEAM AND A DEVICE THEREFOR The invention in general relates 1o a method for purifying an evaporation product to produce steam and a device therefor, and in particular to a continuous sterilization process for biological waste and an apparatus for applying said process, the main line of which comprising, in the flow direction of a biowaste-containing liquid, a storage tank, at least one feed pump, at least one heating unit, at least one cooling unit and a circulation circuit for circulating the biowaste-containing liquid through the heating unit, as well as appropriate piping and valves. Biological waste is produced e.g. in hospitals, agricultural or biological research and production facilities, plasma fractionation facilities, etc. Biological wastes produced in such facilities cannot be directly conducted to a sewer system, as these wastes often contain micro-organisms, such as bacteria, viruses, germs and the like, which are hazardous to humans and animals. Prior to conducting to a sewer system, such biowaste must first be deactivated in a treatment plant designed for this purpose. For the treatment of biowaste, different treatment plants have been designed in which biowaste is sterilized prior to conducting to the sewer system. The sterilization of biowaste can be carried out chemically or by means of heat. The treatment plants can operate continuously or batchwise. In publication DE 40 16 116, a process is disclosed for the continuous purification of waste waters laden by micr-organisms, such as bacteria, viruses, germs and the like. In said process the waste water is heated to a disinfection temperature by means of a heat exchanger and / or a directly injected hot steam, whereafter the waste water is conducted to a swell circuit, e.g. to a pressurized vessel. In said dwell circuit, the wastewater is held at the disinfection temperature for a predetermined time. The residence time is measured by injecting an indicator into the wastewater at regular intervals, e.g. every five minutes for 5 seconds, and by measuring the presence of this indicator in the outlet of the dwell circuit. The time difference between indicator injection and detection shows the actual residence time, which can be compared with the residence time setting. In the journal Pharmaceutical Engineering, May / June 2001, pages 70 to 82, an article “Biowaste Systems" by Carl J. Carlson appears, relating to facilities for the treatment of biowaste. The article deals with biowaste treatment facilities of different type as well as with dimensioning principles and problems relating thereto. According to said article, a typical thermal continuous biowaste sterilisation apparatus comprises a separating unit for solid matter, a storage tank, a heating unit and a dwell circuit as well as a circulating circuit for circulating biowaste through said heating unit and said dwell circuit. According to the article, a typical continuous apparatus comprises the following stages : a heating stage, whereby biowaste is circulated in a heat exchanger and in a dwell circuit, until a temperature sufficient to kill the micro-organisms is reached. This is followed by an operating stage when the biowaste has reached the required temperature over the whole length of the heat exchanger. Thereby the treated biowaste is conducted through cooling equipment to a sewer system. If one or several sterilization parameters (temperature in the dwell circuit, pressure etc.) go outside the predetermined value, and the biowaste is therefore insufficiently sterilized, the process enters a hold state, where the biowaste is circulated through the heating unit and the dwell circuit until the parameter or parameters in question are again within the given limits. In case of an alarm, the apparatus enters the cooling mode, in which the operation of the heating unit is stopped, and the biowaste is recirculated back to the pump feed line until the apparatus is again in working order. According to said article, provisions for the steam sterilization of the parts downstream from the storage tank should be provided, as well as provisions for preventing the transfer of the active biowaste to the cooling circuit. In addition, steam sterilization of the storage tank, the piping, venting filters, etc, should be provided in the apparatus. Accordingly, the present invention provides a method for purifying an evaporation product to produce pure steam, wherein the evaporation product is set in a spiraling rotational motion to separate droplets by centrifugal force, characterized by providing an evaporation product by means of a falling film evaporator conducting said evaporation product into an annular rising channel comprising spiral fins forming a spiral path, providing at least one opening in the outer surface of said spiral path, collecting droplets and impurities on an actively cooled surface outside said opening or openings. The invention further provides a device having a pressure vessel shell and a rising channel and fins in said rising channel forming a spiral path, at least one opening being provided in the outer surface of the spiral path, and a temperature-regulated surface provided outside said opening(s), characterised by the device being connected to the lower end of a falling film evaporator for the purification of an evaporation product to produce pure steam. In the starting up stage of the present heat sterilization process for biowaste, conditions at the upper limits of the capacity thereof, i.e “worst case" conditions are used. Thereby a liquid is conducted through a heating unit at maximum flow rate, which liquid is subsequently cooled to a level, which corresponds to the lowest defined temperature of the feed flow. When a sufficient sterilization capacity has been reached under these extreme conditions, in other words, when the temperature in the sterilization zone can be maintained at such a high level that it corresponds to the residence time required at the flow rate in question, the process operates with great reliability under all conditions occurring during operation. Preferably, the invention farther comprises an arrangement by means of which the tightness of those valves, which are critical during startup and in exceptional situations, can be ensured, and, if necessary, the whole valve system can be sterilized for maintenance measures. In a process according to the invention, during startup the operability of the process is thus ensured, that at maximum capacity of the pump a liquid flow is conducted through the heating unit, the temperature of which flow has been lowered in the return circuit to a level corresponding to the minimum temperature of the water in the storage tank during operation. The sterilization stage following the heating stage comprises at least measurement of the temperature at the outlet end. When the residence time of the liquid in the sterilization zone has been found sufficient under the above conditions, it can also be assumed that the operability of the process can be maintained independently of variations occurring in the feed. A device according to the invention is provided with means for verifying the sterilization ability at maximum load during startup. For verifying the capacity of the device, the lowest water temperature and the greatest possible flow are used. In order to ensure that the test actually represents the worst case, the maximum flow must be limited so, that during actual operation it cannot exceed the flow used in the test. Preferably, this is achieved using a positive displacement pump, which at a constant speed of rotation (determined by the electrical motor used) always delivers a constant flow, independent of the pressures at the suction and discharge ends. When a centrifugal pump is used, the maximum flow is limited by setting standards for the suction and discharge pressures and monitoring these values in the control system. Typically, the suction side pressure is essentially constant, because the buffer tank serving as a source is at atmospheric pressure. The discharge back pressure is set to a minimum level, corresponding to the desired maximum flow rate, and the pressure is monitored by means of pressure sensors. In order to bring the liquid in the return circuit to a temperature corresponding to the minimum temperature of the feed, a heat exchanger and appropriate temperature sensors are provided in the return line. The heat exchanger is dimensioned correspondingly, and minimum limits for cooling water flow and temperature are set in the control system. A sterilization apparatus according to the present invention comprises a pump capable of a certain maximum flow rate, preferably a displacement pump, by means of which a liquid to be sterilized is conducted through a heating unit at a constant rate. Following the heating unit, a sterilization zone is arranged which is provided with temperature measurement at least at the outlet end. Since the capacity of the pump can be kept constant, it can be ensured that the residence time in the sterilization zone is sufficient to achieve the desired sterilization level. In case the residence time is insufficient, the flow leaving the sterilization zone is conducted through the return circuit back to the heating unit inlet. Because the temperature measurement is arranged downstream from the heating unit, it is ensured that the residence time is insufficient. The return circuit is provided with cooling equipment. When the return circuit is cooled essentially to the minimum temperature occurring in the liquid in the storage tank, it can be ascertained that the temperature of the input flow of the heating unit is not lower than the minimum level required by the heating means. Preferably, the apparatus according to the invention comprises an arrangement of serial valves arranged after the sterilization zone, by means of which valve arrangement it is ensured that no insufficiently sterilized liquid, which has passed the sterilization zone, can flow outside the apparatus, not even if there is a leakage in a distributing valve. An advantageous embodiment of the invention is described below with reference to the accompanying drawing. 4A The figure shows a biowaste treatment apparatus according to the invention. The main components provided in the main line of the treatment apparatus in the flow direction of a biowaste-containing liquid are a storage tank 20, a heating unit 30 and a discharge cooling unit 40. In addition, the treatment apparatus comprises a circulation circuit provided with a circuit cooling unit 50 and connected to the main line, by which circulation circuit the biowaste-containing liquid can be circulated through heating unit 30. Preferably, the biowaste water is conducted into the storage tank through a solid matter separating unit, which is not shown in the figure. Storage tank 20 is provided with a mixer 21, and a driving motor (which is not shown in the figure) connected thereto, by which the biowaste water in the storage tank 20 is mixed to prevent sedimentation in the storage tank 20. The storage tank 20 is also provided with a level measurement L. From the storage tank 20 the biowaste water is conducted into heating unit 30 through an inlet valve 13 of the main line by means of a constant capacity feed pump 31. In this embodiment, heating unit 30 consists of a heat exchanger, in which steam is used as a heat source. After the heating unit, a sterilization zone 32 is arranged, which herein is provided with two temperature measurements T1 and T2. The measurement of the outlet end T2 is essential, because at that point the lowest temperature occurs. In continuous operation, the sterilized and deactivated biowaste water is conducted from heating unit 30 into a discharge cooling unit 40 via valve group 14 and 15 which forms a barrier site. From discharge cooling unit 40, the deactivated biowaste water is conducted through main line discharge valve 17 to a sewer system at point A2. In this embodiment, discharge cooling unit 40 is a heat exchanger using water as a cooling medium. In addition to the above-described main line of the treatment apparatus, the apparatus comprises a return circuit beginning at the barrier site of the main line between sterilization zone 32 and discharge cooling unit 40 and ending at the suction inlet of feed pump 31. In front of the first valve 14 of the barrier site of the main line, a first branch is arranged to the first parallel inlet valve S3, and between the first valve 14 and the second valve 15 of the barrier site of the main line, a second outer branch is arranged to a second parallel inlet valve 54. Said serial valves 14 and 15 of the main line and said parallel valves 53, 54 of the circulation circuit together form a barrier site. After said parallel valves 53,54, the inner branch and outer branch are joined together, whereafter the joined line of the circulation circuit leads to a circuit cooling unit 50 provided in the circulation circuit. After circuit cooling unit 50, the circulation circuit is closed via circuit discharge valve 55 to a point between main line inlet valve 13 and main line feed pump 31. The tightness of the first serial valve 14 can be controlled by means of pressure measurement P coupled to the line between first serial valve 14 and second serial valve 15. By means of said main line serial valves 14,15 and said two parallel branches of the circulation circuit, it is ensured that discharge cooling unit 40 and the subsequent zones cannot under any conditions be contaminated. The cooling water needed in cooling units 40,50 is brought into circuit cooling unit 50 through cooling water inlet valve 51 at point Dl. The cooling water circulated in circuit cooling unit SO is conducted further to discharge cooling unit 40. The cooling water circulated in discharge cooling unit 40 is discharged via cooling water discharge valve 52 at point D2. The steam needed in heating unit 30 is fed from point El 30 through first main steam line inlet valve 71 and second inlet valve 72 into heating unit 30. The condensate formed in heating unit 30 is discharged at point E2. The startup of the apparatus is carried out by self-testing effected by a control system. Thereafter, biowaste is fed into tank 20, and the circulation of the biowaste is started in heating unit 30 at constant speed by means of the circuit, while the temperature of heating unit 30 is raised to the desired level. The circulating water is cooled in circuit cooling unit 50 to essentially a level corresponding to the minimum temperature of the water in the storage tank. In this way it is ensured that the load of the heating unit does not exceed its capacity at the beginning of the continuous process. In the above described startup stage, the integrity of valve 14 is also tested by means of pressure measurement P. If no pressure rise is found by pressure measurement P, valve 14 operates in the desired manner. If as a result of defective tightness of the valve, a pressure rise occurs, it is possible to safely conduct the flow further into the return circuit through the outer branch and valve 53. Thereby valves 14,15,53, 54 can be sterilized for maintenance by raising the temperature of the whole circuit to a sufficient level for a sufficient time. When the measurement of the temperature of the outlet end of the sterilization zone shows that the temperature in the sterilization zone is maintained at a sufficient level relative to the constant flow rate, the circuit can be interrupted by closing valve 53 and opening valve 14, and the deactivated biowaste water can be conducted through discharge cooling means 40 to the sewer system at point A2. Preferably, the sterilization apparatus shown in the figure is controlled by means of a control system or a computer. Information on the state and operation of all components shown in the figure are fed into the control system, and on the basis of this information the status of the components as well as of the whole apparatus can be shown on a display. In the figure, only the components necessary for understanding the invention are shown, and all other components, e.g. those relating to various measurements, have been left out. WE CLAIM : 1. A method for purifying an evaporation product to produce pure steam, wherein the evaporation product is set in a spiraling rotational motion to separate droplets by centrifugal force, characterized by providing an evaporation product by means of a falling film evaporator (22) conducting said evaporation product into an annular rising channel comprising spiral fins (11) forming a spiral path (12), providing at least one opening (13) in the outer surface of said spiral path, collecting droplets and impurities on an actively cooled surface outside said opening or openings. 2. The method as claimed in claim 1, wherein the temperature of the cooled surface is controlled by means of water used as feed water. 3. A device having a pressure vessel shell (14) and a rising channel (9) and fins (11) in said rising channel forming a spiral path (12), at least one opening (13) being provided in the outer surface of the spiral path, and a temperature-regulated surface provided outside said opening(s), characterised by the device being connected to the lower end of a falling film evaporator (22) for the purification of an evaporation product to produce pure steam. 4. The device as claimed in claim 3, wherein the openings (13) are vertical slits. 5. The device as claimed in claim 3 or 4, wherein at least one detail within the pressure vessel shell is detachable. 6. The device as claimed in any one of claims 3 to 5, wherein at least one detail within the pressure vessel shell is made from a corrosive resistant material different from that of the pressure vessel shell. There is disclosed a method for purifying an evaporation product to produce pure steam, wherein the evaporation product is set in a spiraling rotational motion to separate droplets by centrifugal force, characterized by providing an evaporation product by means of a falling film evaporator (22) conducting said evaporation product into an annular rising channel comprising spiral fins (11) forming a spiral path (12), providing at least one opening (13) in the outer surface of said spiral path, collecting droplets and impurities on an actively cooled surface outside said opening or openings. A device for carrying out the method is also disclosed.

Full Text

METHOD FOR PURIFYING AN EVAPORATION
PRODUCT TO PRODUCE STEAM AND A DEVICE THEREFOR
The invention in general relates 1o a method for purifying an evaporation product to produce
steam and a device therefor, and in particular to a continuous sterilization process for biological
waste and an apparatus for applying said process, the main line of which comprising, in the flow
direction of a biowaste-containing liquid, a storage tank, at least one feed pump, at least one heating
unit, at least one cooling unit and a circulation circuit for circulating the biowaste-containing liquid
through the heating unit, as well as appropriate piping and valves.
Biological waste is produced e.g. in hospitals, agricultural or biological research and
production facilities, plasma fractionation facilities, etc. Biological wastes produced in such facilities
cannot be directly conducted to a sewer system, as these wastes often contain micro-organisms, such
as bacteria, viruses, germs and the like, which are hazardous to humans and animals. Prior to
conducting to a sewer system, such biowaste must first be deactivated in a treatment plant designed
for this purpose. For the treatment of biowaste, different treatment plants have been designed in
which biowaste is sterilized prior to conducting to the sewer system. The sterilization of biowaste can
be carried out chemically or by means of heat. The treatment plants can operate continuously or
batchwise.
In publication DE 40 16 116, a process is disclosed for the continuous purification of waste
waters laden by micr-organisms, such as bacteria, viruses, germs and the like. In said process the
waste water is heated to a disinfection temperature by means of a heat exchanger and / or a directly
injected hot steam, whereafter the waste water is conducted to a swell circuit, e.g. to a pressurized
vessel. In said dwell circuit, the wastewater is held at the disinfection temperature for a
predetermined time. The residence time is measured by injecting an indicator into the wastewater at
regular intervals, e.g. every five minutes for 5 seconds, and by measuring the presence of this
indicator in the outlet of the dwell circuit. The time difference between indicator injection and
detection shows the actual residence time, which can be compared with the residence time setting.
In the journal Pharmaceutical Engineering, May / June 2001, pages 70 to 82, an article
“Biowaste Systems" by Carl J. Carlson appears, relating to facilities for the treatment of biowaste.
The article deals with biowaste treatment facilities of different type as well as with dimensioning
principles and problems relating thereto.
According to said article, a typical thermal continuous biowaste sterilisation apparatus
comprises a separating unit for solid matter, a storage tank, a heating unit and a dwell circuit as well
as a circulating circuit for circulating biowaste through said heating unit and said dwell circuit.
According to the article, a typical continuous apparatus comprises the following stages : a heating
stage, whereby biowaste is circulated in a heat exchanger and in a dwell circuit, until a temperature
sufficient to kill the micro-organisms is reached. This is followed by an operating stage when the
biowaste has reached the required temperature over the whole length of the heat exchanger. Thereby
the treated biowaste is conducted through cooling equipment to a sewer system. If one or several
sterilization parameters (temperature in the dwell circuit, pressure etc.) go outside the predetermined
value, and the biowaste is therefore insufficiently sterilized, the process enters a hold state, where the
biowaste is circulated through the heating unit and the dwell circuit until the parameter or parameters
in question are again within the given limits. In case of an alarm, the apparatus enters the cooling
mode, in which the operation of the heating unit is stopped, and the biowaste is recirculated back to
the pump feed line until the apparatus is again in working order. According to said article, provisions
for the steam sterilization of the parts downstream from the storage tank should be provided, as well
as provisions for preventing the transfer of the active biowaste to the cooling circuit. In addition,
steam sterilization of the storage tank, the piping, venting filters, etc, should be provided in the
apparatus.
Accordingly, the present invention provides a method for purifying an evaporation product to
produce pure steam, wherein the evaporation product is set in a spiraling rotational motion to
separate droplets by centrifugal force, characterized by providing an evaporation product by means of
a falling film evaporator conducting said evaporation product into an annular rising channel
comprising spiral fins forming a spiral path, providing at least one opening in the outer surface of
said spiral path, collecting droplets and impurities on an actively cooled surface outside said opening
or openings.
The invention further provides a device having a pressure vessel shell and a rising channel
and fins in said rising channel forming a spiral path, at least one opening being provided in the outer
surface of the spiral path, and a temperature-regulated surface provided outside said opening(s),
characterised by the device being connected to the lower end of a falling film evaporator for the
purification of an evaporation product to produce pure steam.
In the starting up stage of the present heat sterilization process for biowaste, conditions at the
upper limits of the capacity thereof, i.e “worst case" conditions are used. Thereby a liquid is
conducted through a heating unit at maximum flow rate, which liquid is subsequently cooled to a
level, which corresponds to the lowest defined temperature of the feed flow. When a sufficient
sterilization capacity has been reached under these extreme conditions, in other words, when the
temperature in the sterilization zone can be maintained at such a high level that it corresponds to the
residence time required at the flow rate in question, the process operates with great reliability under
all conditions occurring during operation. Preferably, the invention farther comprises an arrangement by
means of which the tightness of those valves, which are critical during startup and in
exceptional situations, can be ensured, and, if necessary, the whole valve system can be
sterilized for maintenance measures.
In a process according to the invention, during startup the operability of the process is thus
ensured, that at maximum capacity of the pump a liquid flow is conducted through the
heating unit, the temperature of which flow has been lowered in the return circuit to a level
corresponding to the minimum temperature of the water in the storage tank during
operation. The sterilization stage following the heating stage comprises at least
measurement of the temperature at the outlet end. When the residence time of the liquid in
the sterilization zone has been found sufficient under the above conditions, it can also be
assumed that the operability of the process can be maintained independently of variations
occurring in the feed.
A device according to the invention is provided with means for verifying the sterilization
ability at maximum load during startup. For verifying the capacity of the device, the lowest
water temperature and the greatest possible flow are used. In order to ensure that the test
actually represents the worst case, the maximum flow must be limited so, that during actual
operation it cannot exceed the flow used in the test. Preferably, this is achieved using a
positive displacement pump, which at a constant speed of rotation (determined by the
electrical motor used) always delivers a constant flow, independent of the pressures at the
suction and discharge ends. When a centrifugal pump is used, the maximum flow is limited
by setting standards for the suction and discharge pressures and monitoring these values in
the control system. Typically, the suction side pressure is essentially constant, because the
buffer tank serving as a source is at atmospheric pressure. The discharge back pressure is
set to a minimum level, corresponding to the desired maximum flow rate, and the pressure
is monitored by means of pressure sensors.
In order to bring the liquid in the return circuit to a temperature corresponding to the
minimum temperature of the feed, a heat exchanger and appropriate temperature sensors
are provided in the return line. The heat exchanger is dimensioned correspondingly, and
minimum limits for cooling water flow and temperature are set in the control system.
A sterilization apparatus according to the present invention comprises a pump capable of a
certain maximum flow rate, preferably a displacement pump, by means of which a liquid to
be sterilized is conducted through a heating unit at a constant rate. Following the heating unit, a
sterilization zone is arranged which is provided with temperature measurement at least at the outlet
end. Since the capacity of the pump can be kept constant, it can be ensured that the residence time in
the sterilization zone is sufficient to achieve the desired sterilization level. In case the residence time
is insufficient, the flow leaving the sterilization zone is conducted through the return circuit back to
the heating unit inlet. Because the temperature measurement is arranged downstream from the
heating unit, it is ensured that the residence time is insufficient.
The return circuit is provided with cooling equipment. When the return circuit is cooled essentially to
the minimum temperature occurring in the liquid in the storage tank, it can be ascertained that the
temperature of the input flow of the heating unit is not lower than the minimum level required by the
heating means.
Preferably, the apparatus according to the invention comprises an arrangement of serial valves
arranged after the sterilization zone, by means of which valve arrangement it is ensured that no
insufficiently sterilized liquid, which has passed the sterilization zone, can flow outside the
apparatus, not even if there is a leakage in a distributing valve.
An advantageous embodiment of the invention is described below with reference to the
accompanying drawing.
4A
The figure shows a biowaste treatment apparatus according to the invention. The main components
provided in the main line of the treatment apparatus in the flow direction of a biowaste-containing
liquid are a storage tank 20, a heating unit 30 and a discharge cooling unit 40. In addition, the
treatment apparatus comprises a circulation circuit provided with a circuit cooling unit 50 and
connected to the main line, by which circulation circuit the biowaste-containing liquid can be
circulated through heating unit 30.
Preferably, the biowaste water is conducted into the storage tank through a solid matter separating
unit, which is not shown in the figure. Storage tank 20 is provided with a mixer 21, and a driving
motor (which is not shown in the figure) connected thereto, by which the biowaste water in the
storage tank 20 is mixed to prevent sedimentation in the storage tank 20. The storage tank 20 is also
provided with a level measurement L.
From the storage tank 20 the biowaste water is conducted into heating unit 30 through an
inlet valve 13 of the main line by means of a constant capacity feed pump 31. In this
embodiment, heating unit 30 consists of a heat exchanger, in which steam is used as a heat
source. After the heating unit, a sterilization zone 32 is arranged, which herein is provided
with two temperature measurements T1 and T2. The measurement of the outlet end T2 is
essential, because at that point the lowest temperature occurs.
In continuous operation, the sterilized and deactivated biowaste water is conducted from
heating unit 30 into a discharge cooling unit 40 via valve group 14 and 15 which forms a
barrier site. From discharge cooling unit 40, the deactivated biowaste water is conducted
through main line discharge valve 17 to a sewer system at point A2. In this embodiment,
discharge cooling unit 40 is a heat exchanger using water as a cooling medium.
In addition to the above-described main line of the treatment apparatus, the apparatus
comprises a return circuit beginning at the barrier site of the main line between sterilization
zone 32 and discharge cooling unit 40 and ending at the suction inlet of feed pump 31. In
front of the first valve 14 of the barrier site of the main line, a first branch is arranged to
the first parallel inlet valve S3, and between the first valve 14 and the second valve 15 of
the barrier site of the main line, a second outer branch is arranged to a second parallel inlet
valve 54. Said serial valves 14 and 15 of the main line and said parallel valves 53, 54 of the
circulation circuit together form a barrier site. After said parallel valves 53,54, the inner
branch and outer branch are joined together, whereafter the joined line of the circulation
circuit leads to a circuit cooling unit 50 provided in the circulation circuit. After circuit
cooling unit 50, the circulation circuit is closed via circuit discharge valve 55 to a point
between main line inlet valve 13 and main line feed pump 31. The tightness of the first
serial valve 14 can be controlled by means of pressure measurement P coupled to the line
between first serial valve 14 and second serial valve 15.
By means of said main line serial valves 14,15 and said two parallel branches of the
circulation circuit, it is ensured that discharge cooling unit 40 and the subsequent zones
cannot under any conditions be contaminated.
The cooling water needed in cooling units 40,50 is brought into circuit cooling unit 50
through cooling water inlet valve 51 at point Dl. The cooling water circulated in circuit
cooling unit SO is conducted further to discharge cooling unit 40. The cooling water
circulated in discharge cooling unit 40 is discharged via cooling water discharge valve 52
at point D2.
The steam needed in heating unit 30 is fed from point El 30 through first main steam line
inlet valve 71 and second inlet valve 72 into heating unit 30. The condensate formed in
heating unit 30 is discharged at point E2.
The startup of the apparatus is carried out by self-testing effected by a control system.
Thereafter, biowaste is fed into tank 20, and the circulation of the biowaste is started in
heating unit 30 at constant speed by means of the circuit, while the temperature of heating
unit 30 is raised to the desired level. The circulating water is cooled in circuit cooling unit
50 to essentially a level corresponding to the minimum temperature of the water in the
storage tank. In this way it is ensured that the load of the heating unit does not exceed its
capacity at the beginning of the continuous process.
In the above described startup stage, the integrity of valve 14 is also tested by means of
pressure measurement P. If no pressure rise is found by pressure measurement P, valve 14
operates in the desired manner. If as a result of defective tightness of the valve, a pressure
rise occurs, it is possible to safely conduct the flow further into the return circuit through
the outer branch and valve 53. Thereby valves 14,15,53, 54 can be sterilized for
maintenance by raising the temperature of the whole circuit to a sufficient level for a
sufficient time.
When the measurement of the temperature of the outlet end of the sterilization zone shows
that the temperature in the sterilization zone is maintained at a sufficient level relative to
the constant flow rate, the circuit can be interrupted by closing valve 53 and opening valve
14, and the deactivated biowaste water can be conducted through discharge cooling means
40 to the sewer system at point A2.
Preferably, the sterilization apparatus shown in the figure is controlled by means of a
control system or a computer. Information on the state and operation of all components
shown in the figure are fed into the control system, and on the basis of this information the
status of the components as well as of the whole apparatus can be shown on a display. In
the figure, only the components necessary for understanding the invention are shown, and
all other components, e.g. those relating to various measurements, have been left out.
WE CLAIM :
1. A method for purifying an evaporation product to produce pure steam, wherein the
evaporation product is set in a spiraling rotational motion to separate droplets by centrifugal force,
characterized by
providing an evaporation product by means of a falling film evaporator (22)
conducting said evaporation product into an annular rising channel comprising spiral fins (11)
forming a spiral path (12),
providing at least one opening (13) in the outer surface of said spiral path,
collecting droplets and impurities on an actively cooled surface outside said opening or openings.
2. The method as claimed in claim 1, wherein the temperature of the cooled surface is controlled
by means of water used as feed water.
3. A device having a pressure vessel shell (14) and a rising channel (9) and fins (11) in said
rising channel forming a spiral path (12), at least one opening (13) being provided in the outer
surface of the spiral path, and a temperature-regulated surface provided outside said opening(s),
characterised by the device being connected to the lower end of a falling film evaporator (22) for the
purification of an evaporation product to produce pure steam.
4. The device as claimed in claim 3, wherein the openings (13) are vertical slits.
5. The device as claimed in claim 3 or 4, wherein at least one detail within the pressure vessel
shell is detachable.
6. The device as claimed in any one of claims 3 to 5, wherein at least one detail within the
pressure vessel shell is made from a corrosive resistant material different from that of the pressure
vessel shell.
There is disclosed a method for purifying an evaporation product to produce pure steam,
wherein the evaporation product is set in a spiraling rotational motion to separate droplets by
centrifugal force, characterized by providing an evaporation product by means of a falling film
evaporator (22) conducting said evaporation product into an annular rising channel comprising spiral
fins (11) forming a spiral path (12), providing at least one opening (13) in the outer surface of said
spiral path, collecting droplets and impurities on an actively cooled surface outside said opening or
openings.
A device for carrying out the method is also disclosed.

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Patent Number

225642

Indian Patent Application Number

00422/KOLNP/2004

PG Journal Number

47/2008

Publication Date

21-Nov-2008

Grant Date

19-Nov-2008

Date of Filing

31-Mar-2004

Name of Patentee

STERIS EUROPE, INC. SUOMEN SIVULIIKE

Applicant Address

TEOLLISUUSTIE 2, FIN-04300 TUUSULA

Inventors:

#	Inventor's Name	Inventor's Address
1	HALLI RIKU	TALMANKAARI 143-11, FIN-04240, TALMA
2	SALMISUO MAURI	MARSUNTIE 12-14 C11, FIN-04320, TUUSULA
3	MATTILA JUHA	KARINKUJA 16, FIN-04420 JARVENPAA
4	NURMINEN TEPPO	UURREKUJA 35, FIN-01650 VANTAA

PCT International Classification Number

C02F 1/02

PCT International Application Number

PCT/FI02/00784

PCT International Filing date

2002-10-07

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	20011952	2001-12-08	Finland