CN114111367A - Double-layer shell-and-tube condenser and method for recovering condensation heat - Google Patents
Double-layer shell-and-tube condenser and method for recovering condensation heat Download PDFInfo
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- CN114111367A CN114111367A CN202111489712.0A CN202111489712A CN114111367A CN 114111367 A CN114111367 A CN 114111367A CN 202111489712 A CN202111489712 A CN 202111489712A CN 114111367 A CN114111367 A CN 114111367A
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28B—STEAM OR VAPOUR CONDENSERS
- F28B1/00—Condensers in which the steam or vapour is separate from the cooling medium by walls, e.g. surface condenser
- F28B1/02—Condensers in which the steam or vapour is separate from the cooling medium by walls, e.g. surface condenser using water or other liquid as the cooling medium
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28B—STEAM OR VAPOUR CONDENSERS
- F28B9/00—Auxiliary systems, arrangements, or devices
- F28B9/08—Auxiliary systems, arrangements, or devices for collecting and removing condensate
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Abstract
The invention belongs to the technical field of refrigeration machinery, and particularly relates to a double-layer shell-and-tube condenser and a method for recovering condensation heat. The condenser comprises an external heat absorption space, a middle condensation space and a cooling water pipe; the outer heat-absorbing space being a central condensing spaceβThe exhaust gas after the work of the expansion machine flows into two spaces from pipelines with the same diameter respectively, the exhaust gas entering the external heat absorption space expands instantly to lower the temperature and the pressure, the temperature and the pressure of the exhaust gas entering the middle condensation space are unchanged, the two spaces form temperature difference, the heat of the exhaust gas absorbed by the exhaust gas in the external heat absorption space, which is heated and boosted, flows out, the exhaust gas in the middle condensation space is still in a gaseous state after being cooled and depressurized, and then the exhaust gas is condensed into a liquid working medium by cooling water in a cooling water pipe. The waste gas in the external heat absorption space absorbs the heat of the waste gas in the middle condensation space, part of condensation heat is recovered for the next circulation, and only the residual heat of the waste gas in the middle condensation space is absorbed by the cooling waterAnd energy loss is effectively reduced.
Description
Technical Field
The invention belongs to the technical field of refrigeration machinery, and particularly relates to a double-layer shell-and-tube condenser and a method for recovering condensation heat.
Background
Relative shortage of energy and a double-carbon target become important factors restricting economic and social development, and low-grade heat energy utilization becomes an important way for relieving energy and environmental problems in China. The Organic Rankine Cycle (ORC) power generation technology can convert low-grade heat energy into electric energy, has wide market application prospect, and has profound influence on sustainable development of social economy in China. But aiming at the recycling of most low-grade energy, the phenomena of low energy utilization rate, low system power generation efficiency and the like exist.
The shell-and-tube condenser is the most commonly used heat exchanger in a water-cooled condenser and is one of key equipment in the ORC power generation technology, and the shell-and-tube condenser is used for condensing medium-temperature and medium-pressure organic working medium steam into liquid. However, in the existing shell-and-tube condenser, a large amount of waste heat of exhaust gas after work is done is absorbed by cooling water, and condensation heat is dissipated to the environment to cause a large amount of energy waste, which is a root cause of low energy utilization rate and system power generation efficiency. Therefore, it is necessary to design a shell-and-tube condenser for recovering the heat of condensation to improve the efficiency of energy utilization.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides a double-layer shell-and-tube condenser and a method for recovering condensation heat, the shell-and-tube condenser can recover the condensation heat, and the loss of the condenser exergy is reduced.
In order to achieve the purpose, the invention adopts the following technical scheme:
a double-layer shell-and-tube condenser and a method for recovering condensation heat, wherein the double-layer shell-and-tube condenser comprises: an external heat absorption space, a middle condensation space and a cooling water pipe; the external heat absorption space is surrounded by an external shell, a feed inlet is formed in the upper part of the shell, and a discharge outlet is formed in the lower part of the shell; the middle condensation space is surrounded by heat conducting materials and supported inside the shell through the baffle plate, a feed inlet is formed in the left upper portion of the middle condensation space, a discharge outlet is formed in the right upper portion of the middle condensation space, and an inlet pipe and an outlet pipe of the middle condensation space extend from the inside of the shell to the outside of the shell; the cooling water pipe is composed of a plurality of cooling water heat exchange pipes, the cooling water pipe is supported inside the middle condensation space through the baffle plate, a water inlet is formed in the right lower portion of the middle condensation space, a water outlet is formed in the left lower portion of the middle condensation space, and an inlet and an outlet of the cooling pipe extend to the outside of the shell from the inside of the shell.
In particular, the outer heat-absorbing space is a central condensing spaceβThe exhaust gas after the work of the expansion machine flows into two spaces from pipelines with the same diameter respectively, the exhaust gas entering the external heat absorption space expands instantly to reduce the temperature and the pressure, the temperature and the pressure of the exhaust gas entering the middle condensation space are unchanged, so that the two spaces form temperature difference to exchange heat first, the heat of the exhaust gas absorbed by the exhaust gas in the external heat absorption space rises in temperature and pressure and then flows out of the shell, the exhaust gas in the middle condensation space is still in a gaseous state after being cooled and reduced in pressure, and cooling water in the cooling water pipe is required to absorb the residual heat of the exhaust gas and condense the residual heat into liquid working media.
Specifically, after the heat exchange between the heat absorption space and the exhaust gas of the condensation space is completed, the cooling water can enter the condensation space to absorb the residual heat. The exhaust gas in the external heat absorption space absorbs the heat of the exhaust gas in the middle condensation space, and part of condensation heat is recovered for the next circulation; meanwhile, only the residual exhaust heat of the middle condensation space is absorbed by cooling water, and the energy loss is effectively reduced.
In another aspect, the present invention provides a method for recovering condensation heat using the double-shell and tube condenser, the method comprising the steps of:
step 1, setting the total mass flow of an outlet of an expansion machine asm fThe exhaust gas is divided into a plurality of exhaust gas mass flow ratesm f1The mass flow of the exhaust gas entering the middle condensing space ism f2But the temperature and the pressure of the two exhaust gases are the same, both areT f1Andp f1(ii) a Setting the temperature at the outlet of the external heat absorption spaceT f2Pressure, pressurep f2Then, the external heat absorption space can be obtained according to the enthalpy difference between the inlet and the outletHeat absorption capacity of roomQ f1I.e., the amount of condensation heat recovered,
Q 1=m f1(h f2 -h f1)（1）
wherein the content of the first and second substances,f1、f2 are respectively the state points of the exhaust gas inlet and outlet of the external heat absorption space;
Q f 1=Q f2=m f1(h f2 -h f1)=m f2(h f4 -h f3)（2）
h f 1=h f3 （3）
Wherein the content of the first and second substances,f3 is a state point of a waste gas inlet in the middle condensing space,f4 is a state point after the first heat release;
Q f 3=m f2(h f5 -h f4)（4）
step 4, setting the temperature of the cooling water inlet, namely knowing the temperature difference between the cooling water and the exhaust gas after the exhaust gas in the middle condensation space releases heat for the first timeT 1According to equation 5, the cooling water flow is determinedMeasurement ofm w(ii) a Calculating the heat exchange area between the middle condensing space and the cooling water pipe according to the formula 6A 1，
m w=Q f3/c∆T 1（5）
A 1=Q f3/K 1∆T 1（6）
Wherein the content of the first and second substances,cthe specific heat is the specific heat,K 1is the heat transfer coefficient;
p f 1/p fz=V fz/V f1（7）
pV=m f R gT（8）
The invention has the beneficial effects that: 1. the basic principle of thermodynamics is fully utilized to enable the exhaust gas in the external heat absorption space to absorb the heat of the exhaust gas in the middle condensation space, and part of condensation heat is recycled for the next circulation; 2. the flow of the condensed working medium is reduced through shunting, so that the heat loss of condensation is reduced; 3. only the residual exhaust heat of the middle condensation space is absorbed by cooling water, and the energy loss is effectively reduced.
Drawings
FIG. 1 is a schematic diagram of a double-shell type condenser for recovering condensation heat according to the present invention
Reference numerals:
1. an external heat absorbing space; 2. a middle condensation space; 3. a cooling water pipe; 4. a housing; 5. a thermally conductive material; 6. a baffle plate; 7. an external heat absorption space feed inlet; 8. an external heat absorption space discharge port; 9. a middle condensation space feed inlet; 10. a middle condensation space feed inlet; 11. a cooling water inlet; 12. and a cooling water outlet.
Detailed Description
The preferred embodiments of the present invention will be described in conjunction with the accompanying drawings, and it will be understood that they are described herein for the purpose of illustration and explanation and not limitation. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
In the description of the present invention, it is to be understood that the terms "upper", "lower", "left", "right", "inner", "middle", "outer", and the like, indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are only for convenience of description of the present invention, and do not indicate or imply that the referred devices or elements must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention.
Referring to fig. 1, the present invention is a double shell tube condenser and a method for recovering condensation heat, the double shell tube condenser includes: an external heat absorption space 1, a middle condensation space 2 and a cooling water pipe 3; the external heat absorption space 1 is enclosed by the shell 1, a feed inlet 7 is arranged at the upper part of the shell 1, and a discharge outlet 5 is arranged at the lower part of the shell 1; the middle condensation space 2 is surrounded by heat conducting materials 5 and supported inside the shell 1 by baffle plates 6, a feed inlet 9 is arranged at the left upper part of the middle condensation space 2, a discharge outlet 10 is arranged at the right upper part of the middle condensation space 2, and an inlet, an outlet 9 and a pipe 10 of the middle condensation space extend from the inside of the shell 1 to the outside of the shell 1; the cooling water pipe 3 is composed of a plurality of cooling water heat exchange pipes, is supported inside the middle condensation space 2 by the baffle plate 6, a water inlet 11 is arranged at the right lower part of the middle condensation space 2, a water outlet 12 is arranged at the left lower part of the middle condensation space 2, and inlet and outlet 11 and 12 of the cooling pipe extend to the outside of the shell 1 from the inside of the shell 1.
The external heat-absorbing space 1 being a central condensing space 2βThe exhaust gas after the work of the expander flows into the two spaces 1 and 2 through the inlets 7 and 9 respectively from the pipelines with the same diameter, the exhaust gas entering the external heat absorption space 1 expands instantly to cause the temperature and the pressure to be reduced, the temperature and the pressure of the exhaust gas entering the middle condensation space 2 are unchanged, so that the two spaces 1 and 2 form temperature difference to exchange heat first, the exhaust gas of the external heat absorption space 1 absorbs the heat of the exhaust gas of the middle condensation space 2, the exhaust gas is heated and boosted and then flows out of the shell 1 through the outlet 8, the exhaust gas of the middle condensation space 2 is still in a gaseous state after being cooled and boosted, at the moment, cooling water flows into the cooling water pipe 3 through the inlet 11 to continuously absorb the heat of the exhaust gas, the cooling water is finally condensed into a liquid working medium and flows out of the middle condensation space through the outlet 10, and the cooling water also flows out through the outlet 12 of the cooling water pipe.
After the heat exchange between the heat absorption space 1 and the exhaust gas of the condensation space 2 is completed, the cooling water can enter the condensation space 2 to absorb the residual heat. The exhaust gas in the external heat absorption space 1 absorbs the heat of the exhaust gas in the middle condensation space 2, and part of condensation heat is recovered for the next circulation; meanwhile, only the residual exhaust gas heat of the middle condensation space 2 is absorbed by the cooling water in the cooling water pipe 3, and the energy loss is effectively reduced.
The method for recovering condensation heat by adopting the double-shell tubular condenser comprises the following steps:
step 1, setting the total mass flow of an outlet of an expansion machine asm fThe exhaust gas is divided, and the mass flow of the exhaust gas entering the external heat absorption space 1 through the inlet 7 ism f1The mass flow of the exhaust gas entering the middle condensing space 2 through the inlet 9 ism f2But the temperature and the pressure of the two exhaust gases are the same, both areT f1Andp f1(ii) a Setting the temperature at the outlet 8 of the external heat absorption space 1T f2Pressure, pressurep f2The heat absorption capacity of the external heat absorption space 1 can be obtained according to the enthalpy difference between the inlet and the outletQ f1I.e., the amount of condensation heat recovered,
Q 1=m f1(h f2 -h f1)（1）
wherein the content of the first and second substances,f1、f2 are respectively the state points of the exhaust gas inlet and outlet 7 and 8 of the external heat absorption space 1;
Q f 1=Q f2=m f1(h f2 -h f1)=m f2(h f4 -h f3)（2）
h f 1=h f3（3）
Wherein the content of the first and second substances,f3 is the state point of the exhaust gas inlet 9 in the middle condensing space 2,f4 is a state point after the first heat release;
Q f 3=m f2(h f5 -h f4)（4）
step 4, setting the temperature of the cooling water inlet 11, namely knowing the heat exchange temperature difference between the cooling water in the cooling water pipe 3 and the exhaust gas after the first heat release of the exhaust gas in the middle condensation space 2T 1Calculating the flow rate of cooling water according to equation 5m w(ii) a Calculating the heat exchange area between the middle condensing space 2 and the cooling water pipe 3 according to the formula 6A 1，
m w=Q f3/c∆T 1（5）
A 1=Q f3/K 1∆T 1（6）
Wherein the content of the first and second substances,cthe specific heat is the specific heat,K 1is the heat transfer coefficient;
p f 1/p fz=V fz/V f1（7）
pV=m f R gT（8）
Claims (4)
1. A double-layer shell-and-tube condenser and a method for recovering condensation heat, wherein the double-layer shell-and-tube condenser comprises: an external heat absorption space, a middle condensation space and a cooling water pipe; the heat-absorbing device is characterized in that the external heat-absorbing space is surrounded by an external shell, a feed port is arranged at the upper part of the shell, and a discharge port is arranged at the lower part of the shell; the middle condensation space is surrounded by heat conducting materials and supported inside the shell through the baffle plate, a feed inlet is formed in the left upper portion of the middle condensation space, a discharge outlet is formed in the right upper portion of the middle condensation space, and an inlet pipe and an outlet pipe of the middle condensation space extend from the inside of the shell to the outside of the shell; the cooling water pipe is composed of a plurality of cooling water heat exchange pipes, the cooling water pipe is supported inside the middle condensation space through the baffle plate, a water inlet is formed in the right lower portion of the middle condensation space, a water outlet is formed in the left lower portion of the middle condensation space, and an inlet and an outlet of the cooling pipe extend to the outside of the shell from the inside of the shell.
2. The double-shell-and-tube condenser and the method for recovering condensation heat according to claim 1 are characterized in that: the external heat-absorbing space being a central condensing spaceβThe exhaust gas after the work of the expansion machine flows into two spaces from pipelines with the same diameter respectively, the exhaust gas entering the external heat absorption space expands instantly to reduce the temperature and the pressure, the temperature and the pressure of the exhaust gas entering the middle condensation space are unchanged, so that the two spaces form temperature difference to exchange heat first, the heat of the exhaust gas absorbed by the exhaust gas in the external heat absorption space rises in temperature and pressure and then flows out of the shell, the exhaust gas in the middle condensation space is still in a gaseous state after being cooled and reduced in pressure, and cooling water in the cooling water pipe is required to absorb the residual heat of the exhaust gas and condense the residual heat into liquid working media.
3. A double shell and tube condenser and method for recovering heat of condensation as claimed in claims 1 and 2 wherein: after heat exchange between the exhaust gas in the heat absorption space and the exhaust gas in the condensation space is completed, cooling water can enter the condensation space to absorb residual heat, the exhaust gas in the outer heat absorption space absorbs the heat of the exhaust gas in the middle condensation space, and part of condensation heat is recovered for next circulation; meanwhile, only the residual exhaust heat of the middle condensation space is absorbed by cooling water, and the energy loss is effectively reduced.
4. A double shell and tube condenser and method for recovering heat of condensation as claimed in claims 1 and 2 wherein: the method for recovering condensation heat by adopting the condenser comprises the following steps:
step 1, setting the total mass flow of an outlet of an expansion machine asm fThe exhaust gas is divided into a plurality of exhaust gas mass flow ratesm f1The mass flow of the exhaust gas entering the middle condensing space ism f2But the temperature and the pressure of the two exhaust gases are the same, both areT f1Andp f1(ii) a Setting the temperature at the outlet of the external heat absorption spaceT f2Pressure, pressurep f2The heat absorption capacity of the external heat absorption space can be obtained according to the enthalpy difference between the inlet and the outletQ f1I.e., the amount of condensation heat recovered,
Q 1=m f1(h f2 -h f1)（1）
wherein the content of the first and second substances,f1、f2 are respectively the state points of the exhaust gas inlet and outlet of the external heat absorption space;
step 2, according to the recovered condensation heat obtained in the step 1Q f1The first heat release of the exhaust gas in the middle condensing spaceQ f2The temperature of the exhaust gas in the middle condensing space after the first heat release can be obtained according to the formulas 2 and 3T f4And pressurep f4，
Q f 1=Q f2=m f1(h f2 -h f1)=m f2(h f4 -h f3)（2）
h f 1=h f3 （3）
Wherein the content of the first and second substances,f3 is a state point of a waste gas inlet in the middle condensing space,f4 is a state point after the first heat release;
step 3, after the first heat release of the exhaust gas in the middle condensation space, the exhaust gas is still in a gaseous state and is condensed into pressure again through cooling waterp f3The corresponding saturated liquid state can know the enthalpy value when flowing out of the middle condensation spaceh f5Further, the heat quantity absorbed by the cooling water of the exhaust gas in the middle condensing space is obtainedQ f3Namely the condensation heat finally released by the condenser;
Q f 3=m f2(h f5 -h f4)（4）
step 4, setting the temperature of the cooling water inlet, namely knowing the temperature difference between the cooling water and the exhaust gas after the exhaust gas in the middle condensation space releases heat for the first timeT 1Calculating the flow rate of cooling water according to equation 5m w(ii) a Calculating the heat exchange area between the middle condensing space and the cooling water pipe according to the formula 6A 1，
m w=Q f3/c∆T 1（5）
A 1=Q f3/K 1∆T 1（6）
Wherein the content of the first and second substances,cthe specific heat is the specific heat,K 1is the heat transfer coefficient;
step 5, because the external heat absorption space is n times of the pipeline space, according to the basic thermodynamic formulas 7 and 8, the pressure of the exhaust gas entering the upper heat absorption space is reduced to bep fzThe temperature is reduced toT fzThe pressure of the exhaust gas in the middle condensing space before releasing heat isp f1Calculating that the outer heat-absorbing space is the middle condensing spaceβMultiple times，Further knowing the heat exchange area of the external heat absorption spaceA 2；
p f 1/p fz=V fz/V f1（7）
pV=m f R gT（8）
Step 6, obtaining the heat exchange area of the inner space and the outer space according to the steps 3 and 4A 1、A 2And adding the heat exchange areas to obtain the total heat exchange area of the double-shell tubular condenser.
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Application publication date: 20220301 |