U.S. patent application number 14/236839 was filed with the patent office on 2014-06-12 for temperature control system.
This patent application is currently assigned to JAPAN OIL, GAS AND METALS NATIONAL CORPORATION. The applicant listed for this patent is Yuzuru Kato, Kentarou Morita, Eiichi Yamada. Invention is credited to Yuzuru Kato, Kentarou Morita, Eiichi Yamada.
Application Number | 20140157813 14/236839 |
Document ID | / |
Family ID | 47668417 |
Filed Date | 2014-06-12 |
United States Patent
Application |
20140157813 |
Kind Code |
A1 |
Kato; Yuzuru ; et
al. |
June 12, 2014 |
TEMPERATURE CONTROL SYSTEM
Abstract
A temperature control system of the invention recovers reaction
heat in a reactor in which an exothermal reaction occurs, to
control the temperature in the reactor. The temperature control
system includes: a refrigerant drum in which vapor and a liquid
refrigerant are stored in a vapor-liquid equilibrium state; a heat
removing section arranged in the reactor to evaporate a part of the
liquid refrigerant supplied from the refrigerant drum by the
reaction heat; a Return line that returns mixed phase fluid of
vapor and the liquid refrigerant generated in the heat removing
section to the refrigerant drum; a Vapor outlet line that supplies
vapor in the refrigerant drum to outside of the system; and a
Replenishing line that supplies makeup water in an amount matched
with an amount of vapor discharged to the outside of the system, to
the Return line.
Inventors: |
Kato; Yuzuru; (Tokyo,
JP) ; Yamada; Eiichi; (Tokyo, JP) ; Morita;
Kentarou; (Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Kato; Yuzuru
Yamada; Eiichi
Morita; Kentarou |
Tokyo
Tokyo
Tokyo |
|
JP
JP
JP |
|
|
Assignee: |
JAPAN OIL, GAS AND METALS NATIONAL
CORPORATION
Tokyo
JP
INPEX CORPORATION
Tokyo
JP
NIPPON STEEL & SUMIKIN ENGINEERING CO., LTD.
Tokyo
JP
JAPAN PETROLEUM EXPLORATION CO., LTD.
Tokyo
JP
COSMO OIL CO., LTD.
Tokyo
JP
JX NIPPON OIL & ENERGY CORPORATION
Tokyo
JP
|
Family ID: |
47668417 |
Appl. No.: |
14/236839 |
Filed: |
August 2, 2012 |
PCT Filed: |
August 2, 2012 |
PCT NO: |
PCT/JP2012/069692 |
371 Date: |
February 3, 2014 |
Current U.S.
Class: |
62/310 ; 165/111;
62/314 |
Current CPC
Class: |
B01J 2219/00211
20130101; B01J 2219/002 20130101; B01J 2219/00238 20130101; F28B
9/04 20130101; F22B 35/00 20130101; B01J 2208/00115 20130101; B01J
2208/00061 20130101; B01J 8/001 20130101; C10G 2/32 20130101; F25D
1/02 20130101; B01J 8/22 20130101; F25D 7/00 20130101; F28B 11/00
20130101; F28B 9/02 20130101 |
Class at
Publication: |
62/310 ; 62/314;
165/111 |
International
Class: |
F25D 7/00 20060101
F25D007/00; F28B 9/04 20060101 F28B009/04; F28B 11/00 20060101
F28B011/00; F25D 1/02 20060101 F25D001/02; F28B 9/02 20060101
F28B009/02 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 5, 2011 |
JP |
2011-171812 |
Claims
1. A temperature control system that recovers reaction heat in a
reactor in which an exothermal reaction occurs, to control the
temperature in the reactor, comprising: a refrigerant drum in which
vapor and a liquid refrigerant are stored in a vapor-liquid
equilibrium state; a heat removing section arranged in the reactor
to evaporate a part of said liquid refrigerant supplied from said
refrigerant drum by said reaction heat; a Return line that returns
mixed phase fluid of vapor and the liquid refrigerant generated in
the heat removing section to said refrigerant drum; a Vapor outlet
line that supplies vapor in said refrigerant drum to outside of the
system; and a Replenishing line that supplies makeup water in an
amount matched with an amount of vapor discharged to the outside of
the system, to said Return line.
2. A temperature control system according to claim 1, further
comprising: a control unit that determines said amount of makeup
water by dividing the reaction heat in said reactor by a unit
refrigerant heat amount determined based on a comparatively high
temperature in said refrigerant drum, a comparatively low
temperature of makeup water, and physical values (specific heat,
evaporative latent heat) of the refrigerant; and a makeup water
adjusting device that sets the amount of makeup water to be
supplied from said Replenishing line to the Return line according
to said amount of makeup water determined by said control unit.
3. A temperature control system according to claim 2, wherein the
amount of makeup water determined by said control unit is
calculated according to the following equation:
WL3=Q/{Cp.times.(t1-t3)+r} where WL3: amount of makeup water Q:
reaction heat in reactor Cp: specific heat of liquid refrigerant
t1: temperature in refrigerant drum and heat removing section of
reactor t3: temperature of makeup water r: evaporative latent heat
of liquid refrigerant.
4. A temperature control system according to claim 1, wherein said
Replenishing line is connected to said Return line at an acute
angle along a traveling direction of mixed phase fluid in said
Return line at a junction of said Return line and said Replenishing
line.
5. A temperature control system according to claim 1, wherein said
Replenishing line is provided with a seal portion that prevents
back flow of vapor.
6. A temperature control system according to claim 1, wherein a
spray nozzle that sprays makeup water into said Return line is
provided in said Replenishing line at the junction of said Return
line and said Replenishing line.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a Section 371 of International
Application No. PCT/JP2012/069692, filed Aug. 2, 2012, which was
published in the Japanese language on Feb. 14, 2013, under
International Publication No. WO 2013/021908 A1, and the disclosure
of which is incorporated herein by reference.
TECHNICAL FIELD
[0002] The present invention relates to a temperature control
system that can perform precise temperature control of a reactor by
making the temperature in a refrigerant drum such as a steam drum
uniform.
[0003] Priority is claimed on Japanese Patent Application No.
2011-171812, filed Aug. 5, 2011, the content of which is
incorporated herein by reference.
BACKGROUND ART
[0004] Conventionally, as a water supply system for a steam drum,
there are those described for example in Patent Documents 1 and 2.
The water supply system described in Patent Document 1 supplies
water to a drum via a water supply line from an economizer upon
reception of flue gas, and generates steam by vapor-liquid
separation performed by a vapor-liquid separator for an evaporator.
However, at the time of low load operation such as at startup, the
temperature at the feed water outlet of the economizer increases
and becomes higher than the saturation temperature with respect to
drum pressure. In the case in which such air water is to be
directly supplied to the drum, because the pressure thereof is
higher than the internal pressure of the drum, a vapor-liquid
separator for vapor-liquid separation is provided to perform
vapor-liquid separation in order to prevent steaming in the
drum.
[0005] Moreover, in the water supply system described in Patent
Document 2, an internal feed line is provided in the drum instead
of a vapor-liquid separator, and a small hole is formed in an upper
half thereof and a through hole having a larger diameter than that
is formed in a lower half thereof so that vapor and feed water flow
out.
[0006] However, the above-described configuration is for a general
boiler, and if the temperature of the makeup water is lower than
that of the vapor phase in the steam drum, a temperature difference
occurs between the vapor phase and the liquid phase. If the
feed-water temperature of the makeup water to the steam drum is
low, the temperature of the liquid phase becomes lower than the
saturation temperature. Hence, if this configuration is applied to
temperature control of an FT (Fisher-Tropsch) reactor, control
becomes unstable. Moreover, there is another problem in that the
amount of generated vapor becomes unstable because the temperature
of the liquid phase decreases due to the amount of water supplied
to the steam drum.
[0007] Recently, as one of the FT synthesis reaction
(Fisher-Tropsch synthesis reaction) methods used in the FT reactor,
a GTL (Gas To Liquids: liquid fuel synthesis) technique has been
developed in which natural gas is reformed to generate synthesis
gas containing carbon monoxide gas (CO) and hydrogen gas (H.sub.2)
as the main components, this synthesis gas is used for the FT
synthesis reaction (Fisher-Tropsch synthesis reaction) as a raw
material gas to synthesize liquid hydrocarbon, and the liquid
hydrocarbon is hydrogenized and refined, thereby producing liquid
fuel products such as naphtha (crude gasoline), kerosene, light
oil, and wax.
[0008] In such an FT synthesis reaction, a reactor converts
synthesis gas containing rich hydrogen gas and carbon monoxide gas
to hydrocarbon by using a catalyst. The FT synthesis reaction is an
exothermal reaction, and the temperature range for an appropriate
reaction is very narrow. Accordingly, the reaction temperature in
the reactor needs to be controlled precisely, while recovering the
generated reaction heat.
[0009] As a temperature control system using the above-described FT
reactor, for example, the one shown in FIG. 7 is known. This
temperature control system 100 supplies water accumulated in a
steam drum 101 in a vapor-liquid equilibrium state by a pump 102
from the bottom to a heat removing tube 104 in a reactor 103 in
which a Fisher-Tropsch synthesis reaction (exothermal reaction) is
performed. Water in the heat removing tube 104 is partly evaporated
and heat-recovered by reaction heat generated in the reactor 103
accompanying the exothermal reaction, and this vapor-water
two-phase fluid passes through a Return line 105 to the steam drum
101 and is returned to the steam drum 101. The vapor then passes
through a Vapor outlet line 107 and is supplied to a vapor user
outside of the system.
[0010] Meanwhile, makeup water in an amount matched with the vapor
supplied to the outside of the system is replenished to the steam
drum 101 through a Replenishing line 106. Supply of makeup water is
adjusted so that the liquid level becomes constant based on a
measurement result obtained by a level measuring section 108 that
measures the water level in the steam drum 101.
PRIOR ART DOCUMENTS
Patent Documents
[0011] [Patent Document 1] Japanese Examined Patent Application,
Second Publication No. H3-53521 [0012] [Patent Document 2] Japanese
Unexamined Patent Application, First Publication No. H6-257703
DISCLOSURE OF INVENTION
Problems to be Solved by the Invention
[0013] However, in the temperature control system 100 described
above, because an opening of the Replenishing line 106 is submerged
under the water surface in the steam drum 101, makeup water having
a large specific gravity and comparatively low temperature directly
flows to the bottom of the steam drum 101, and a temperature
difference occurs between the vapor phase and the water phase in
the steam drum 101. Then, the correlation between the vapor phase
pressure in the steam drum 101 and the temperature of the water
phase collapses, and hence control by the temperature control
system 100 may not be performed with high accuracy.
[0014] In view of the above situation, it is an object of the
present invention to provide a temperature control system that can
control the temperature with high accuracy, by maintaining the
vapor-liquid temperature in the steam drum at saturation
temperature.
Means for Solving the Problems
[0015] A temperature control system according to the present
invention recovers reaction heat in a reactor in which an
exothermal reaction occurs, to control the temperature in the
reactor. The temperature control system comprises: a refrigerant
drum in which vapor and a liquid refrigerant are stored in a
vapor-liquid equilibrium state; a heat removing section arranged in
the reactor to evaporate a part of the liquid refrigerant supplied
from the refrigerant drum by the reaction heat; a Return line that
returns mixed phase fluid of vapor and the liquid refrigerant
generated in the heat removing section to the refrigerant drum; a
Vapor outlet line that supplies vapor in the refrigerant drum to
outside of the system; and a Replenishing line that supplies makeup
water in an amount matched with an amount of vapor discharged to
the outside of the system, to the Return line.
[0016] Moreover, the temperature control system may include: a
control unit that determines the amount of makeup water by dividing
the reaction heat in the reactor by the heat capacity per unit
quantity of refrigerant determined based on a difference between a
comparatively high temperature in the refrigerant drum and a
comparatively low temperature of makeup water, and physical values
(specific heat, evaporative latent heat) of the refrigerant; and a
makeup water adjusting device that sets the amount of makeup water
to be supplied from the Replenishing line to the Return line
according to the amount of makeup water determined by the control
unit.
[0017] Moreover, it is preferred that the amount of makeup water
determined by the control unit be calculated according to the
following equation:
WL3=Q/(Cp.times.(t1-t3)+r)
where WL3: amount of makeup water
[0018] Q: reaction heat in reactor
[0019] Cp: specific heat of liquid refrigerant
[0020] t1: temperature in refrigerant drum and heat removing
section of reactor
[0021] t3: temperature of makeup water
[0022] r: evaporative latent heat of liquid refrigerant.
[0023] Moreover, the Replenishing line may be connected to the
Return line at an acute angle along a traveling direction of mixed
phase fluid in the Return line at a junction of the Return line and
the Replenishing line.
[0024] Furthermore, the Replenishing line may be provided with a
seal portion that prevents back flow of vapor.
[0025] Alternatively, a spray nozzle that sprays makeup water into
the Return line may be provided in the Replenishing line at the
junction of the Return line and the Replenishing line.
Effects of the Invention
[0026] The temperature control system according to the present
invention is provided with the Replenishing line that supplies
makeup water in an amount matched with an amount of vapor
discharged to the outside of the system, to the Return line that
returns mixed phase fluid of vapor and the liquid refrigerant
generated in the heat removing section in the reactor, to the
refrigerant drum. Accordingly, makeup water in an amount matched
with the amount of vapor discharged to the outside of the system,
is merged into the Return line and directly mixed with vapor in the
Return line at saturation temperature, thereby enabling to heat the
makeup water to saturation temperature before being supplied to the
refrigerant drum. As a result, the gas-liquid temperature in the
refrigerant drum can be maintained at saturation temperature at all
times.
[0027] Moreover, as compared with the conventional temperature
control system in which the makeup water is directly supplied to
the refrigerant drum, the complexity of the structure and
enlargement of the equipment can be avoided, and the temperature in
the refrigerant drum can be made uniform.
[0028] As a result, since the temperature in the refrigerant drum
can be made uniform efficiently, temperature control of the reactor
can be performed with high accuracy and precision.
[0029] Moreover, the temperature control system includes: the
control unit that determines the amount of makeup water by dividing
the reaction heat in the reactor by heat capacity per unit quantity
of refrigerant determined based on the difference between a
comparatively high temperature in the refrigerant drum and a
comparatively low temperature of makeup water, and physical values
(specific heat, evaporative latent heat) of the refrigerant; and
the makeup water adjusting device that sets the amount of makeup
water to be supplied from the Replenishing line to the Return line
according to the amount of makeup water determined by the control
unit. Consequently, the control unit can accurately calculate the
amount of makeup water so as to be equal to a flow rate of vapor
supplied to the outside of the system, and can accurately limit the
amount of makeup water so as not to exceed the flow rate of vapor.
As a result, hammering due to complete condensation at the junction
can be reliably prevented.
[0030] Because the amount of makeup water determined by the control
unit is specifically calculated according to the following
equation, the amount of makeup water can be accurately calculated
so as to be equal to the flow rate of vapor supplied to the outside
of the system, and can be limited so as not to exceed the flow rate
of vapor.
WL3=Q/(Cp.times.(t1-t3)+r)
where WL3: amount of makeup water
[0031] Q: reaction heat in reactor
[0032] Cp: specific heat of liquid refrigerant
[0033] t1: temperature in refrigerant drum and heat removing
section of reactor
[0034] t3: temperature of makeup water
[0035] r: evaporative latent heat of liquid refrigerant.
[0036] Moreover, in the temperature control system according to the
present invention, the Replenishing line is connected to the Return
line at an acute angle along the traveling direction of mixed phase
fluid at the junction of the Return line and the Replenishing line.
Consequently, makeup water in the Replenishing line can be supplied
along a flow direction of the mixed phase fluid at the time of
merging makeup water to the mixed phase fluid of vapor into the
liquid refrigerant in the Return line. As a result, generation of
hammering due to an impact when makeup water collides with the
mixed phase fluid at the time of joining can be prevented.
[0037] Moreover, the seal portion for preventing back flow of vapor
is provided in the Replenishing line. Consequently, when the supply
amount of makeup water is small, a situation where vapor in the
Return line flows back into the Replenishing line and condenses
causing hammering, can be prevented.
[0038] Furthermore, the spray nozzle that sprays makeup water into
the Return line is provided in the Replenishing line, at the
junction of the Return line and the Replenishing line.
Consequently, when makeup water is supplied from the Replenishing
line to the Return line at the junction, if makeup water is sprayed
by the spray nozzle and dispersed uniformly to be brought into
contact with vapor in the mixed phase fluid, rapid vapor
condensation due to an imbalance of makeup water can be suppressed,
and the occurrence of hammering can be prevented.
BRIEF DESCRIPTION OF THE DRAWINGS
[0039] FIG. 1 is a schematic configuration diagram of a temperature
control system according to a first embodiment of the present
invention,
[0040] FIG. 2 is an explanatory diagram showing circulation paths
of water and vapor, flow rates thereof, and temperatures thereof,
in the temperature control system according to the embodiment.
[0041] FIG. 3 is an explanatory diagram showing a junction of a
Return line and a Replenishing line in a reactor according to a
first modified example.
[0042] FIG. 4 is an explanatory diagram showing the junction of the
Return line and the Replenishing line in the reactor according to a
second modified example.
[0043] FIG. 5 is an explanatory diagram showing the junction of the
Return line and the Replenishing line in the reactor according to a
third modified example.
[0044] FIG. 6 is a graph showing a change in a vapor percentage at
the Return line after being joined to the outlet of the reactor in
an example.
[0045] FIG. 7 is a schematic configuration diagram of a
conventional temperature control system.
BEST MODE FOR CARRYING OUT THE INVENTION
[0046] In a temperature control system 1 shown in FIG. 1, for
example, water is accumulated at a saturation temperature as a
liquid refrigerant in a gas-liquid equilibrium state in a steam
drum 2, which is a refrigerant drum, and vapor is filled in a
saturated state on an upper side of a liquid level in the steam
drum 2. A supply line 3 is connected to the bottom of the steam
drum 2, and water is fed to a Heat removing line 7 (heat removing
section) in an FT reactor 5 (hereinafter, referred to as "reactor")
in which a Fischer-Tropsch synthesis reaction (exothermal reaction)
is performed, by a water supply pump 4 via the supply line 3. Water
is partially evaporated in the Heat removing line 7 due to reaction
heat accompanying the exothermal reaction generated by the reactor
5, and the reaction heat is recovered.
[0047] Furthermore, two-phase fluid (mixed phase fluid) containing
vapor generated by evaporation of a part of the water in the Heat
removing line 7, and water, is returned to the steam drum 2 via the
Return line 8 for the steam drum 2, and a discharge opening of the
Return line 8 is opened in an area of vapor on the upper side of
the liquid level in the steam drum 2. Then vapor is supplied to a
vapor user (not shown) outside of the system via a Vapor outlet
line 9. A vapor discharge amount measuring unit 11 that measures
the discharge amount of vapor to the outside of the system is
provided in the Vapor outlet line 9.
[0048] Moreover, there is arranged a Replenishing line 10 for
replenishing the steam drum 2 with a liquid refrigerant, for
example, makeup water, in an amount matched with the discharge
amount of vapor supplied to the outside of the system. The
Replenishing line 10 is connected at a junction 6 in the middle of
the Return line 8. Consequently, makeup water having a
comparatively low temperature (for example, a temperature t3) is
directly mixed with vapor having a comparatively high temperature
(for example, a temperature t1; t1>t3) evaporated in the reactor
5, in the Return line 8 and heated to reach saturation temperature.
A replenishing temperature measuring section 16 that measures the
temperature of the makeup water is provided in the Replenishing
line 10.
[0049] The makeup water in the Replenishing line 10 reaches
saturation temperature in the Return line 8, and is supplied to the
steam drum 2.
[0050] A reaction heat temperature measuring section 14 that
measures the temperature in the reactor 5, and a reaction heat
calculating section 15 that calculates the amount of reaction heat
Q, are provided in the reactor 5 in which the exothermal reaction
is performed.
[0051] Moreover, a pressure control section 18 that controls the
pressure in the steam drum 2 based on a measurement result of the
reaction heat temperature measuring section 14 that measures the
temperature in the reactor 5 in which the exothermal reaction is
performed, is provided to adjust the amount of vapor discharged
from the Vapor outlet line 9 to the outside of the system by
cascade control, thereby controlling the temperature in the reactor
5 in which the exothermal reaction is performed. The reaction heat
temperature measuring section 14 may include, for example, a
plurality of temperature sensors arranged away from each other in a
vertical direction in the reactor 5, so that a mean value of the
respective temperatures measured by these temperature sensors can
be designated as the temperature in the reactor 5.
[0052] A vapor phase (gas phase) and a water phase (liquid phase)
in the steam drum 2 are in the vapor-liquid equilibrium state.
Therefore the vapor phase pressure and the temperature of the water
phase in the steam drum 2 are in a certain correlation.
Consequently, when a deviation occurs in the actual temperature in
the reactor 5 measured by the reaction heat temperature measuring
section 14 with respect to a temperature set value of the reactor 5
in which the exothermal reaction is performed, the pressure control
section 18 is operated to change the vapor phase pressure in the
steam drum 2.
[0053] Here, the pressure control section 18 includes; the Vapor
outlet line 9, a pressure adjusting valve 19 provided in the Vapor
outlet line 9, and a pressure setting section 21 that controls the
pressure adjusting valve 19 to set the pressure in the steam drum 2
via the Vapor outlet line 9. The temperature measurement result of
the reaction heat temperature measuring section 14 is input to the
pressure setting section 21. The pressure setting section 21
calculates a deviation of the actual temperature in the reactor 5
with respect to the temperature set value based on the temperature
measurement result, and controls the pressure adjusting valve 19
based on the deviation to change the vapor phase pressure in the
steam drum 2.
[0054] By changing the vapor phase pressure in the steam drum 2 in
this manner, the temperature of the water phase in the steam drum 2
(that is, the temperature of the water supplied to the Heat
removing line 7 in the reactor 5 in which the exothermal reaction
is performed) is changed, thereby enabling to change the amount of
heat recovered by the Heat removing line 7, and the temperature in
the reactor 5 in which the exothermal reaction is performed can be
made to approach the temperature set value.
[0055] In the present embodiment, the temperature of the water
phase in the steam drum 2 can be measured by a water-phase
temperature measuring section 23 provided at the bottom of the
steam drum 2. In the present embodiment, the steam drum 2, the
supply line 3, the Heat removing line 7, and the Return line 8
constitute a system in which water as a liquid refrigerant
circulates. Moreover, because makeup water is supplied to the
Return line 8, the temperature in the steam drum 2 is at saturation
temperature at all times under any pressure, thereby enabling to
control the temperature in the reactor precisely and highly
accurately.
[0056] Moreover, the temperature control system 1 includes a
control unit 25 that controls the amount of makeup water so that
the amount of makeup water from the Replenishing line 10 does not
exceed the amount of vapor discharged from the Vapor outlet line 9
to the outside of the system. The control unit 25 receives
respective measurement values obtained by; the water-phase
temperature measuring section 23 that measures the water phase
temperature in the steam drum 2, the reaction heat calculating
section 15, and the replenishing temperature measuring section 16
that measures the temperature of the makeup water in the
Replenishing line 10, and calculates and determines the amount of
makeup water so that it does not exceed the amount of vapor
discharged from the Vapor outlet line 9.
[0057] Data of the calculated amount of makeup water is output to a
flow rate adjusting device 26 provided in the Replenishing line 10.
The flow rate adjusting device 26 adjusts an aperture of a flow
rate adjusting valve 13 to control the amount of makeup water. A
level measuring section 12 that measures the water level (liquid
level) in the steam drum 2, is provided in the steam drum 2. When
the valve aperture of the flow rate adjusting valve 13 output based
on a measurement result of the level measuring section 12 is
smaller than a valve aperture corresponding to the calculated
amount of makeup water, that aperture is selected in order to
prevent excessive water supply to the steam drum 2 (prevent
overflow).
[0058] Accordingly, the amount of makeup water is controlled so as
not to exceed the flow rate of vapor.
[0059] Next is a description of an example of a calculation method
of an amount of makeup water by the control unit 25.
[0060] As shown in FIG. 2, it is assumed that the vapor amount
discharged by the Vapor outlet line 9 is WV1, the temperature
thereof is t1, the flow rate of water supplied via the supply line
3 to the reactor 5 is WL4, the temperature thereof is t1, the
amount of vapor discharged from the reactor 5 to the Return line 8
is WV2, the flow rate of water is WL2, each temperature is t1, the
flow rate of water supplied from the Replenishing line 10 to the
Return line 8 is WL3, the temperature thereof is t3, the amount of
vapor returned from the Return line 8 after being merged into the
steam drum 2 is WV1, the flow rate of water is WL4, and each
temperature is t1. It is further assumed that the flow rate of
water is in units of kg/h, the flow rate of vapor is in units of
kg/h, and the temperature is .degree. C.
[0061] Moreover, it is assumed that the amount of reaction heat in
the reactor 5 is Q (kcal/h), the evaporative latent heat of water
is r (kcal/kg), and the specific heat of water is Cp
(kcal/kg/.degree. C.).
[0062] According to the material balance, the vapor generation
amount WV1 discharged by the Vapor outlet line 9 and the amount of
makeup water WL3 are equal, and hence, the following equation (1)
is established.
WV1=WL3 (1)
[0063] A procedure for deriving the above equation (1) is explained
below.
[0064] In FIG. 2, at first the flow rate WL4 of water at
temperature t1 supplied from the steam drum 2 becomes the flow rate
of vapor WV2+the flow rate of water WL2 at temperature t1, by
recovering the reaction heat in the reactor 5. Accordingly, the
material balance of input and output involving a change of phase in
the reactor 5 is expressed by the following equation (2).
WL4=WV2+WL2 (2)
[0065] Moreover, by supplying the amount of makeup water WL3 from
the Replenishing line 10, the material balance (water supply+change
of phase) at the junction 6 of the Return line 8 and the
Replenishing line 10 becomes as shown in the following equation
(3).
WV2+WL2+WL3=WV1+WL4 (3)
[0066] By substituting equation (2) into equation (3) and
rearranging, the following equation is obtained.
WV1=WL3 (1)
[0067] Furthermore, the temperature of the amount of makeup water
WL3 is the low temperature t3, and other temperatures are at the
high temperature t1 (>t3). At the junction of the Return line 8
and the Replenishing line 10, the amount of vapor
condensation=water supply preheat amount/evaporative latent heat.
Hence,
(WV2-WV1).times.r=WL3.times.Cp.times.(t1-t3) (4).
[0068] The relation between the amount of reaction heat Q and the
vapor generation amount WV2 in the reactor 5 is as described
below.
WV2=Q/r (5)
[0069] By substituting equations (1) and (5) into equation (4) and
rearranging,
WL3=Q/{Cp.times.(t1-t3)+r} (6)
[0070] Thus, the amount of makeup water WL3 can be obtained based
on the relation between the amount of reaction heat Q and the water
supply temperatures t1 and t3.
[0071] The amount of reaction heat Q can be obtained from a product
of; the reaction amount in the reactor 5 measured and calculated
separately or a temperature difference between the steam drum 2 and
the reactor 5, the heat transfer area of the Heat removing line,
and the overall heat transfer coefficient.
[0072] The temperature control system 1 according to the present
embodiment has the above-described configuration. Next is a
description of a control method thereof.
[0073] For example, by driving the water supply pump 4, water at
temperature t1 is supplied at the flow rate WL4 from the steam drum
2 to the reactor 5. A part of the water flow rate WL4 is evaporated
in the Heat removing line 7 due to reaction heat accompanying the
exothermal reaction generated in the reactor 5 to become two-phase
fluid having the vapor flow rate WV2 and the water flow rate WL2 at
temperature t1. The two-phase fluid (mixed phase fluid) is fed by
the Return line 8.
[0074] In the vapor phase and the water phase in the steam drum 2,
because the water level decreases by discharging water at the flow
rate WL4 toward the reactor 5 by the water supply pump 4, the
amount of makeup water WL3 determined by the control unit 25 is
adjusted and supplied by the flow rate adjusting valve 13.
[0075] Meanwhile, in the Replenishing line 10, the amount of makeup
water WL3 at the comparatively low temperature t3 determined by the
control unit 25, is replenished and merged into the two-phase fluid
(WV2+WL2) in the Return line 8 at the junction 6 with the Return
line 8. At the junction 6, the amount of makeup water WL3 at
temperature t3 is directly mixed with the vapor WV2 at the high
temperature t1 in the Return line 8 and heated up to saturation
temperature t1. Further, a part of the vapor is condensed at the
junction 6, and the flow rate of water in the Return line 8 becomes
the same as the flow rate WL4 of water supplied from the steam drum
2 to the supply line 3.
[0076] In the Return line 8 downstream of the junction 6, the flow
rate becomes the flow rate WV1 of vapor and the flow rate WL4 of
water at temperature t1, and the two-phase fluid is discharged to
above the water surface in the steam drum 2.
[0077] Here is a description of a control method for the amount of
makeup water WL3 performed by the control unit 25.
[0078] The temperature t1 measured by the water-phase temperature
measuring section 23 that measures the water phase temperature in
the steam drum 2, the amount of reaction heat Q calculated by the
reaction heat calculating section 15, and the temperature t3 of the
makeup water measured by the replenishing temperature measuring
section 16 in the Replenishing line 10 are input to the control
unit 25. The control unit 25 then calculates the amount of makeup
water WL3 according to the above equation (6).
[0079] The calculation value for this amount of makeup water WL3 is
output to the flow rate adjusting device 26 to operate the flow
rate adjusting valve 13 and supply makeup water in the amount of
WL3 to the Replenishing line 10 to merge into the Return line 8 at
the junction 6, and be discharged to the steam drum 2.
[0080] Then in the steam drum 2, the correlation based on the
vapor-liquid equilibrium state between the vapor phase pressure and
the temperature of the water phase is always maintained.
[0081] Moreover, vapor is supplied at the flow rate WV1 from the
steam drum 2 to the outside of the system by the Vapor outlet line
9, and makeup water in the amount of WL3 merges into to the
vapor-water two-phase fluid at the junction 6 with the Return line
8 and is supplied to the steam drum 2. Because the amount of makeup
water WL3 is controlled by the control unit 25 to be equal to the
flow rate of vapor WV1, the water level in the steam drum 2 is
maintained constant.
[0082] As described above, according to the temperature control
system 1 of the present embodiment, the amount of makeup water WL3
equal to the flow rate of vapor WV1 to be supplied to the outside
of the system by the Vapor outlet line 9 and at the comparatively
low temperature t3, can be joined to the Return line 8 from the
Replenishing line 10, and can be directly mixed with vapor at the
flow rate WV2 at saturation temperature t1 in the Return line 8.
Therefore the makeup water can be heated instantaneously to
saturation temperature.
[0083] Consequently, the vapor-liquid temperature in the steam drum
2 can be always maintained at saturation temperature. As a result,
the reactor temperature can be controlled precisely and highly
accurately.
[0084] Furthermore, the control unit 25 can calculate so that the
amount of makeup water WL3 becomes equal to the flow rate of vapor
WV1 to be supplied to the outside of the system, and can accurately
limit the amount of makeup water so that the amount of makeup water
WL3 does not exceed the flow rate of vapor WV1, thereby enabling to
prevent hammering due to complete condensation at the junction
6.
[0085] In the conventional temperature control system, the
configuration is such that makeup water is directly supplied to the
steam drum 2. Therefore, heating of the makeup water is performed
by heat transfer (condensation of vapor) in the steam drum 2. In
order to increase the temperature of the makeup water up to
saturation temperature, the amount of makeup water in the
Replenishing line 10 needs to be divided into as small an amount of
supply water as possible, or a sufficient residence time needs to
be ensured in the steam drum 2, thereby making the structure
complicated and the equipment large, which leads to a cost
increase. In this regard, with the present invention, the
complexity of the structure and enlargement of the equipment can be
avoided, and the temperature in the steam drum 2 can be made
uniform.
[0086] The present invention is not limited to the embodiment
described above, and various changes can be made without departing
from the scope of the invention.
[0087] Next is a description of a configuration for preventing
hammering when the Replenishing line 10 flow joins to the Return
line 8 flow at the junction 6, as a modified example with reference
to FIG. 3 through FIG. 5.
[0088] FIG. 3 shows a configuration of the junction 6 according to
a first modified example. In FIG. 3, the Replenishing line 10 is
connected and merged at an acute angle .alpha. with respect to the
flow direction of the two-phase fluid in the Return line 8.
Consequently, makeup water smoothly joins to the vapor-water
two-phase fluid flowing in the Return line 8, and hence, hammering
does not occur due to an impact when the makeup water collides with
the mixed phase fluid at the time of joining or rapid condensation
of the mixed phase fluid.
[0089] At the junction according to a second modified example shown
in FIG. 4, the Replenishing line 10 is connected and joined at an
acute angle with respect to the flow direction of the two-phase
fluid in the Return line 8. Further, for example, a substantially
U-shaped depression 10a is formed in the Replenishing line 10 on an
upstream side of the junction 6, and a water seal portion 27 in
which water is residually filled in the depression 10a, is provided
in the Replenishing line 10 as a seal portion.
[0090] According to this configuration, when the amount of makeup
water WL3 is small, even if vapor in the Return line 8 tries to
flow back into the Replenishing line 10, the vapor is stopped by
the water seal portion 27. Consequently, a situation where vapor in
the Return line 8 flows back into the Replenishing line 10 and
hammering occurs due to condensation can be prevented.
[0091] As the seal portion for preventing back flow of the vapor, a
check valve can be provided instead of the water seal portion
27.
[0092] FIG. 5 shows a configuration of the junction 6 according to
a third modified example. In FIG. 5, the Replenishing line 10 is
connected at an acute angle with respect to the flow direction of
the two-phase fluid in the Return line 8, and a spray nozzle 28
that disperses and sprays makeup water in the Return line 8, is
formed at the end of the Replenishing line 10. As a result, makeup
water that joins the vapor and water in the Return line 8 is widely
sprayed by the spray nozzle 28, and hence, rapid vapor condensation
is suppressed to prevent hammering.
[0093] In the temperature control system 1 according to the present
embodiment, any two or three configurations of the first to the
third modified examples can be combined.
Example
[0094] Next is a description of an example of the temperature
control system 1 according to an embodiment of the present
invention.
[0095] First, in FIG. 2, it is assumed that the temperature inside
the steam drum 2, the respective water temperatures t1 of the water
to be supplied at the flow rates WL4 and WL2 via the supply line 3,
and the temperature t1 of vapor at the flow rates WV1 and WV2 are
all a saturation temperature of 195.degree. C. It is also assumed
that the water temperature t3 of the makeup water in the amount of
WL3 is 110.degree. C.
[0096] Moreover, it is assumed that
[0097] reaction heat Q=8000000 kcal/h
[0098] evaporative latent heat of water r=470 kcal/kg (physical
property (constant))
[0099] specific heat Cp of water=1 kcal/kg/.degree. C. (physical
property (constant))
[0100] pressure in steam drum=1.3 MPaG
[0101] circulation amount WL4 of water supply pump 4=68000
kg/h.
[0102] Under the above conditions, the control unit 25 of the
temperature control system 1 determines the amount of makeup water
WL3 which becomes equal to the flow rate of vapor WV1 to the
outside of the system, according to the above equation (6), so as
to make the temperature in the steam drum 2 uniform and keep the
liquid level constant. That is to say, substituting for the
respective numerals in equation (6) gives,
WL 3 = Q / { Cp .times. ( t 1 - t 3 ) + r } = 8000000 / { 1 .times.
( 195 - 110 ) + 470 } = 14400 kg / h . ##EQU00001##
[0103] Furthermore according to equation (1), the flow rate of
vapor WV1 is equal to the amount of makeup water WL3, and hence
WV=WL3=14400 kg/h.
Moreover, obtaining the vapor generation amount WV2 in the reactor
5 according to equation (5) gives
WV 2 = Q / r = 8000000 / 470 = 17000 kg / h . ##EQU00002##
Furthermore, obtaining the flow rate of water WL2 at the outlet of
the reactor 5 according to equation (2) gives
WL 2 = WL 4 - WV 2 = 68000 - 17000 = 51000 kg / h .
##EQU00003##
[0104] Next, FIG. 6 is a graph for an example showing a change in
vapor percentage at positions before and after the junction 6
between the Return line 8 and the Replenishing line 10, in the
temperature control system 1.
[0105] In FIG. 6, the horizontal axis denotes the percentage of
vapor WV2 generated in the reactor 5 with respect to the water
circulation amount WL4 to be supplied from the steam drum 2 to the
reactor 5 (WV2/WL4), and the vertical axis denotes the percentage
of vapor content in the two-phase fluid in the Return line 8 at
positions before and after the junction 6 as a percentage of the
gas phase portion.
[0106] When the percentage of vapor WV2 generated in the reactor 5
with respect to the water circulation amount WL4 (WV2/WL4) is
changed, the percentage of vapor content (gas phase portion) in the
two-phase fluid is calculated for before and after the junction 6
in the Return line 8.
[0107] In FIG. 6, the broken line M denotes a change in the
percentage of gas phase (vapor) at the outlet (Return line 8) of
the reactor 5 (WV2/(WL2+WV2)), and the solid line N denotes a
change in the percentage of gas phase (vapor) in the Return line 8
after where the Replenishing line 10 is joined thereto
(WV1/(WV1+WL4).
[0108] In the graph shown in FIG. 6, the evaporation percentage in
the reactor 5 is 0 at the start point (WV2/WL4=0). However, the
generation amount of vapor WV2 increases with temperature rise in
the reactor 5. Normally, an operation is performed at a percentage
of the evaporation amount WV2 to the circulation flow rate WL4 in
the reactor 5 (WV2/WL4) of 30%. This is designated as the normal
operation point. In this state, if the flow rate of vapor WV1 and
the amount of makeup water WL3 are well balanced, a change from the
percentage of the amount of vapor WV2 generated at the outlet of
the reactor 5 (WV2/WL4) to the percentage of the amount of vapor
WV1 in the Return line 8 after joining the makeup water WL3
(WV1/(WV1+WL4)) is only a decrease by about 1%.
[0109] Moreover, over the entire range in which the ratio of the
evaporation amount WV2 to the circulation flow rate WL4 in the
reactor 5 (WV2/WL4) exceeds 0 and is up to 35%, even if the ratio
of the vapor amount shown by the broken line M (WV2/(WL2+WV2))
changes to the percentage of the vapor amount shown by the solid
line N in the Return line 8 after joining (WV/(WV1+WL4)), if the
flow rate of vapor WV1 and the amount of makeup water WL3 are well
balanced, the change is as low as in a range of about 1% to 30/,
and hence, hammering does not occur.
[0110] If complete condensation of the vapor WV2 in the Return line
8 occurs at the junction 6 between the Return line 8 and the
Replenishing line 10, hammering may occur. However, in the
embodiment of the present invention, if the flow rate of vapor WV1
and the amount of makeup water WL3 are well balanced, the change in
the percentage of the vapor WV1 in the Return line 8 after joining
the amount of makeup water WL3 is in the range of about 1% to 3%,
and hammering does not occur.
[0111] In the embodiment described above, the FT reactor in which
the Fischer-Tropsch synthesis reaction is performed inside the
reactor 5 is used. However, if an exothermal reaction is performed
in the reactor 5, the reaction need not be the Fischer-Tropsch
synthesis reaction.
[0112] In the present embodiment, the respective modified examples,
and the examples, water is adopted as the liquid refrigerant.
However, the liquid refrigerant need not be water.
INDUSTRIAL APPLICABILITY
[0113] The present invention relates to a temperature control
system that can perform precise temperature control in a reactor by
making the temperature in a refrigerant drum such as a steam drum
uniform.
[0114] According to the present invention, the temperature can be
controlled highly accurately by maintaining the vapor-liquid
temperature in the steam drum at saturation temperature.
DESCRIPTION OF THE REFERENCE SYMBOLS
[0115] 1 Temperature control system [0116] 2 Steam drum [0117] 3
Supply line [0118] 4 Pump [0119] 5 Reactor [0120] 6 Junction [0121]
7 Heat removing line [0122] 8 Return line [0123] 9 Vapor outlet
line [0124] 10 Replenishing line [0125] 11 Vapor discharge amount
measuring unit [0126] 12 Level measuring section [0127] 13 Flow
rate adjusting valve [0128] 14 Reaction heat temperature measuring
section [0129] 15 Reaction heat calculating section [0130] 16
Replenishing temperature measuring section [0131] 23 Water-phase
temperature measuring section [0132] 25 Control unit [0133] 26 Flow
rate adjusting device
* * * * *