Abstrict A steam flow meter provided with a steam flow rate detecting device
and a steam pressure and temperature detecting device. In order
to accurately maintain the heating temperature of the material to
be heated without provision of any further measuring device, and
detect a change in the efficiency of heat transmission of the steam
heating apparatus with a low-priced and simple construction, the
flow meter is further provided with a device for detecting the temperature
of the material to be heated and an arithmetic unit which connects
the material temperature detecting device, the steam flow rate detecting
device and the steam pressure and temperature detecting device,
whereby the efficiency of the heat transmission of the apparatus
to be measured is calculated from the temperature of the material
measured by the material temperature detecting device and from the
quantity of heat of the steam which has passed through calculated
on the basis of the signals from the steam flow rate detecting device
and the steam pressure and temperature detecting device.
Claims What is claimed is:
1. A steam flow meter having a steam flow rate detecting means
and a steam pressure and temperature detecting means for detecting
pressure and temperature of steam, further comprising:
a means for inputting a reference quantity of heat;
said steam flow rate detecting means and said steam pressure and
temperature detecting means being operatively connected and being
capable of producing signals; and
an arithmetic unit being operatively connected to said reference
heat quantity inputting means, said steam flow rate detecting means
and said steam pressure and temperature detecting means,
said arithmetic unit being capable of calculating a quantity of
heat of an amount of steam which has passed through an apparatus
from signals received from said steam flow rate detecting means
and said steam pressure and temperature detecting means, said quantity
of heat of the steam and said reference quantity of heat are compared
and calculated.
2. A steam flow meter having a steam flow rate detecting means
and a steam pressure and temperature detecting means for detecting
pressure and temperature of steam, said steam flow meter further
comprising:
a means for detecting temperature of a material to be heated;
said steam flow rate detecting means and said steam pressure and
temperature detecting means being operatively connected and being
capable of producing signals; and
an arithmetic unit being operatively connected to said material
temperature detecting means and receiving said signals from said
steam flow rate detecting means and said steam pressure and temperature
detecting means,
said arithmetic unit being capable of calculating an efficiency
of the heat transmission of an apparatus to be measured from a temperature
detected by said material temperature detecting means and from a
quantity of heat of an amount of steam which has passed through
the apparatus, the quantity of heat of the steam being calculated
from the signals received from said steam flow rate detecting means
and said steam pressure and temperature detecting means.
Description BACKGROUND OF THE INVENTION
This invention relates to a steam flow meter for measuring a flow
rate of steam which performs heating or drying in various kinds
of apparatuses.
A steam heating apparatus is generally provided with a steam flow
meter at the inlet side of the apparatus. The flow meters are based
on different principles, however, at any rate, each of them allows
the amount of steam consumed to be grasped and, at the same time,
allows a proper amount of steam for the material to be heated to
be supplied to the apparatus. Furthermore, it is important to correctly
understand the property of steam in question to supply a proper
amount of steam.
In a conventional manner, for example, a corresponding flow rate
is determined by measuring a differential pressure to correspond
to the steam flowing through a supply tube, and separately the actual
temperature and pressure of the steam in question are measured,
and in the end, the flow rate to the correct flow rate of the steam
is revised on the basis of the measurements of the temperature and
pressure. However, since a conventional flow meter based on the
measurement of a differential pressure only has a function of measuring
an actual differential pressure, in addition to the flow meter,
a thermometer and a pressure gauge are provided to carry out a required
revision in the case where a correct amount of steam is determined.
This increases the cost of equipment and construction. In order
to solve such a problem, JP-A Hei-4(1992)-50620 discloses a flow
meter which, in addition to measuring the differential pressure
of flow rates in the measuring process, simultaneously measures
the static pressure and the temperature to carry out the revision
of the temperature and pressure of the flow rate in the measuring
Process. This provides an added value to the flow meter per se,
and at the same time, dispenses with the separate provision of any
measuring means or arithmetic correction unit, thereby allowing
the reduction in cost of both the equipment and construction to
be planned.
Furthermore, separately providing a means for detection of an amount
of material to be heated, such as a flow meter or the like, at the
supply side of the material to be heated, and grasping the amount
of supply of the material to be heated so as to rationalize the
amount of supply, are also widely carried out.
For most of the materials to be heated, by such a rationalization
of both the amounts of the supply of steam and the material to be
heated, the quantity of heat given from the steam is controlled
in a predetermined range with respect to the constant amount of
material to be heated, so that the degree of heating of the material
to be heated is adjusted.
However, there is a problem in that dust, scales, rust and the
like contained within the steam adhere to the heating surface of
the steam heating apparatus over time, and therefore, the efficiency
of heat transmission to the material to be heated is lowered. A
large quantity of heat of the steam exceeding a theoretical quantity
is required to carry out a required heating, thus lowering the productivity
per unit energy. Moreover, in the case where the lowering of the
efficiency of heat transmission can not be correctly grasped, unevenness
in heat transmission to the material to be heated occurs, resulting
in the lowering of the quality of the products.
Depending upon the kinds of materials to be heated, it is required
to maintain a heating temperature which changes little and is highly
accurate. For example, food stuffs, medical supplies, chemical articles
or the like are deteriorated in quality due to changes in temperature
during heating, and therefore, prevention of such deterioration
is required.
Accordingly, in the steam heating apparatus in the prior art, measurements
of the pressure, temperature and flow rate of steam supplied to
the steam heating apparatus, and measurements of the temperatures
of the material to be heated before and after heating are carried
out in order to precisely detect the lowering of the efficiency
of heat transmission. That is, a quantity of heat which can be supplied
to the material to be heated is calculated from the pressure, temperature
and flow rate of the supplied steam, and then the lowering of the
efficiency of heat transmission is detected from a rise in the temperature
of the material due to the quantity of the supplied heat.
To that end, even if the flow meter disclosed in the above-described
JP-A Hei-4(1992)-50620 is used in order to precisely detect the
lowering of the efficiency of heat transmission and to maintain
the heating temperature of the material more correctly, the separate
provision of a thermometer for measuring temperatures before and
after heating of the material to be heated is necessary, and furthermore,
operations for performing calculations from their measuring data
and adjusting the quantity of supply of the steam or material to
be heated are indispensable.
In the prior art described above, since it is necessary to separately
provide a measuring unit or arithmetic unit in addition to the steam
flow meter, there is a problem in that the total expense for the
apparatus using steam is increased, and further, the construction
of the apparatus becomes complicated.
SUMMARY OF THE INVENTION
It is therefore an object to provide a steam flow meter which is
capable of accurately maintaining a heating temperature of the material
to be heated without providing any separate measuring units or the
like.
It is another object to provide a steam flow meter which is capable
of detecting a change in efficiency of heat transmission of a steam
heating apparatus at a moderate price and with a simple construction.
In order to is achieve the above-mentioned objects, there is provided
a steam flow meter having a steam flow rate detecting means and
a steam pressure and temperature detecting means for detecting pressure
and temperature of steam. The steam flow meter according to the
invention includes: a means for detecting temperature of the material
to be heated and an arithmetic unit which connects said material
temperature detecting means, said steam flow rate detecting means
and said steam pressure and temperature detecting means.
Efficiency of heat transmission of an apparatus to be measured
may be calculated from the temperature of said material to be heated
measured by said material temperature detecting means and from the
quantity of heat of the steam which has passed through calculated
on the basis of signals from said steam flow rate detecting means
and said steam pressure and temperature detecting means.
The operation of the above-described flow meter is as follows:
The quantity of heat supplied to the steam heating apparatus is
calculated from the pressure, temperature and flow rate of steam.
Furthermore, the temperature at the inlet and the temperature at
the outlet of the apparatus for the material to be heated are detected
by the material temperature detecting means. In the case where the
amount of supply of the material to be heated is constant, the efficiency
of heat transmission can simply be converted by dividing the difference
between the temperature at the outlet and the temperature at the
inlet of the above-described material to be heated, by the quantity
of the supplied heat. Moreover, the efficiency of heat transmission
can also be calculated by dividing the quantity of the supplied
heat by the value obtained by subtracting the average value of both
temperatures of the material to be heated at the outlet and inlet,
from the temperature of steam. The regular measurements of the flow
rate of steam, and, at the same time, the measurements of change
in the efficiency of the heat transmission in the case of a constant
amount of supply of the material to be heated, allow the situation
where foreign materials attached to the heating surface of the steam
heating apparatus or the like can be detected, in other words, the
efficiency of the heat transmission of the apparatus in question
can always be detected. Accordingly, if cleaning is carried out
at a suitable time, the efficiency of the heat transmission of the
apparatus can be maintained in a desired range.
Furthermore, the above-described object is also achieved by a steam
flow meter having a steam flow rate detecting means and a steam
pressure and temperature detecting means for detecting pressure
and temperature of steam. The steam flow meter includes a means
for inputting a reference quantity of heat and an arithmetic unit
which connects said reference heat quantity inputting means, said
steam flow rate detecting means and said steam pressure and temperature
detecting means.
The quantity of the heat of the steam which has passed through
is calculated from signals from said steam flow rate detecting means
and said steam pressure and temperature detecting means, and the
quantity of heat of the steam and the reference quantity of heat
are compared and calculated. By calculating a proportion of the
quantity of heat of the steam and the reference quantity of heat,
it can be grasped whether the quantity of the heat of the supplied
steam is proper or not with the reference quantity of the heat as
a reference. At the same time, if, for example, a required quantity
of heat in a steam using apparatus in the case where the amount
of the material to be heated is a predetermined amount, is selected
as a reference quantity of heat, it can be grasped whether the amount
of material to be heated exceeds the predetermined amount or not,
that is, whether the amount of the supply of the material to be
heated is proper or not. Accordingly, the amount of the steam and
the amount of the material to be heated can properly be supplied.
In addition, change in the efficiency of heat transmission of the
apparatus can be measured.
BRIEF DESCRIPTION OF THE DRAWINGS
Other objects and aspects of the invention will become apparent
from the following description of embodiments with reference to
the accompanying drawings in which:
FIG. 1 is a schematic view of a device for measuring the flow rate
of the steam passing through a steam heating apparatus using a steam
flow meter of an embodiment of the present invention; and
FIG. 2 is a schematic view of a device for measuring the flow rate
of steam using a steam flow meter of another embodiment of the invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENT
Now, the present invention will be explained in detail with reference
to the drawings showing embodiments of the invention.
Referring to FIG. 1 which shows an example in which a steam flow
meter according to the invention is applied to a steam heating apparatus,
a steam supply tube 10 is connected to the steam heating apparatus
1. A steam flow meter 3 is attached to the steam supply tube 10.
The steam flow meter 3 is provided with a flow rate measuring part
4 a steam pressure measuring part 5 a steam temperature measuring
part 6 and a measuring part 7 of temperature difference of material
to be heated. For the flow rate measuring part 4 the constructions
of the known flow meters based on any measuring principle may be
applied: for example, an orifice plate is disposed in the supply
tube 10 and a flow rate of steam may be determined from the pressure
difference before and after the orifice plate. Similarly, any widely
known, conventional technique may be used for the pressure measuring
part 5 and the temperature measuring part 6. The steam flow meter
3 is further provided with an arithmetic unit 8 connected to the
flow rate measuring part 4 steam pressure measuring part 5 steam
temperature measuring part 6 and measuring part 7 of the temperature
difference of the material to be heated.
At the primary side of the steam flow meter 3 there are provided
an adjusting valve 11 for adjusting the amount of the supply of
steam and a separator 22 for separating steam and condensate within
the steam supply tube 10. The separator 22 is provided with a steam
trap 23 for discharging the separated condensate out of the system.
At the secondary side of the steam heating apparatus 1 there is
connected a condensate discharging tube 20 for discharging the condensate
produced in the steam heating apparatus 1 as a result of heat exchange.
A steam trap 9 for forcibly discharging the condensate which is
flowing downwards is attached to the condensate discharging tube
20; however such a steam trap is not always necessary if the amount
of condensate produced within the steam heating apparatus 1 is constant.
A tube 12 for supplying the material to be heated is further connected
to the steam heating apparatus 1 together with a valve 14 and similarly,
a tube 13 for removing the material to be heated is also connected
to the steam heating apparatus 1. A temperature sensor 17 as a means
for detecting the temperature of the material at the inlet side
is arranged on the material supply tube 12 in the vicinity of the
steam heating apparatus 1 and a temperature sensor 18 as a means
for detecting the temperature of the material at the outlet side
is arranged on the material removing tube 13 in the vicinity of
the steam heating apparatus 1. Both the temperature sensors 17 and
18 are connected to the material temperature difference measuring
part 7 of the steam flow meter 3.
Now, the operation will be explained.
The material to be heated within the steam heating apparatus 1
is heated by the steam supplied from the steam supply tube 10 and
removed by the material removing tube 13. The amount of the supplied
steam is measured by the steam flow meter 3. The steam, of which
heat is derived by the heating of the material, condenses and is
discharged out of the system through the steam trap 9 attached to
the secondary side of the steam heating apparatus 1. The respective
signals from the flow rate measuring part 4 steam pressure measuring
part 5 and steam temperature measuring part 6 in the steam flow
meter 3 are inputted into the arithmetic unit 8. In the unit 8
the quantity of the heat of the steam supplied to the steam heating
apparatus 1 is calculated from the data of the steam flow rate,
steam pressure and temperature. Furthermore, the mean value of the
temperatures of the material to be heated at the inlet and outlet
sides of the steam heating apparatus 1 or the difference between
the temperatures at the inlet and outlet sides, which are detected
by the temperature sensors 17 and 18 are derived in the material
temperature difference measuring part 7. The arithmetic unit 8 can
further simply determine the efficiency of the heat transmission
of the steam-heating apparatus 1 from such data. That is, in the
case where the amount of the supply of the material to be heated
is grasped as a constant value, the efficiency of the heat transmission
can be calculated by dividing the temperature difference of the
material at the inlet and outlet by the calculated amount of steam,
or by dividing the quantity of heat of steam by the value obtained
by subtracting the mean value of the temperatures at the inlet and
outlet of the material from the measured temperature of the steam.
Accordingly, detection of the flow rate of the supplied steam at
all times allows changes in the efficiency of the heat transmission
to be grasped precisely, and adjustment of the amount of the supply
of the steam or the like enables the heating temperature of the
material to be maintained accurately. The provision of a control
means connected to the arithmetic unit 8 allows the adjustment in
question to be automated.
FIG. 2 shows another embodiment, in which a steam flow meter of
the construction different from the above-mentioned embodiment is
applied to the steam heating apparatus. A steam supply tube 10 is
connected to a steam heating apparatus 1. A steam flow meter 3 is
attached to the seam supply tube 10. The flow meter 3 is provided
with a flow rate measuring part 4 steam pressure measuring part
5 steam temperature measuring part 6 and arithmetic unit 8. The
arithmetic unit 8 is connected to the flow rate measuring part 4
steam pressure measuring part 5 and steam temperature measuring
part 6 and further connected to a means for inputting a reference
quantity of heat 24. For example, this means corresponds to one
or more keys in a keyboard for inputting data of a reference quantity
of heat with numerical values.
In the construction of the present embodiment, the flow rate measuring
part 4 steam temperature measuring part 5 steam pressure measuring
part 6 in the flow meter 3 and the adjusting valves 11 14 steam
traps 9 23 and the like are fundamentally the same as the above-mentioned
embodiment, for example, the construction of a differential pressure
type measuring system of flow meter is preferable for the flow rate
measuring part 4. The parts which are common with the above mentioned-embodiment
are affixed with the same reference numerals and the explanation
of the construction thereof is omitted.
The operation of the present embodiment is as follows:
The material to be heated within the steam heating apparatus 1
is heated by the steam supplied from the steam supply tube 10 and
is removed by the material removing tube 13. The amount of supplied
steam is measured by the steam flow meter 3. The respective signals
from the flow rate measuring part 4 steam pressure measuring part
5 and steam temperature measuring part 6 are input into the arithmetic
unit 8 in which the quantity of heat of the steam supplied to the
steam heating apparatus 1 is calculated from the data of the flow
rate, temperature and pressure of the steam. The proportion of the
quantity of heat of the supplied steam with the reference quantity
of heat is calculated by dividing the calculated quantity of heat
of the steam in question by the data of the reference quantity of
heat inputted from a reference heat quantity inputting means 24
which is connected to the arithmetic unit 8. It can be grasped from
the result whether the quantity of heat of the steam actually supplied
is less or larger than the reference quantity of heat, or is a proper
value. In addition, if the quantity of the heat required in the
case where the amount of the material to be heated is a predetermined
amount, that is, the designed quantity of heat determined when the
apparatus was designed, is selected as a reference quantity of heat,
changes in the efficiency of the heat transmission can be grasped
from the comparison of the calculated quantity of heat of the steam
with the designed quantity of heat. Moreover, from the above-mentioned
comparison, it is possible to theoretically grasp whether the amount
of the material to be heated is larger or smaller, and adjustment
of the valve 14 in the material supply tube 12 allows the amount
of the material to be adjusted. Accordingly, the degree of heating
against the material to be heated can be adjusted by grasping the
quantity of heat of the supplied steam and the amount of the material
to be heated only by the steam flow meter 3 and adjusting them. |