CN114320509A - Organic Rankine cycle system of double evaporators of marine coupling desulfurizing tower - Google Patents

Abstract

The invention discloses an organic Rankine cycle system of double evaporators of a coupling desulfurizing tower for a ship, which comprises a first evaporator and a second evaporator which are arranged in parallel, wherein a working medium in the first evaporator absorbs heat in flue gas for evaporation, and a working medium in the second evaporator absorbs heat of cooling seawater in a cooling tower attached to the desulfurizing tower for evaporation to jointly generate high-temperature and high-pressure steam; the expander is connected with the first evaporator and the second evaporator, high-temperature and high-pressure steam enters the expander to do work to drive the generator to generate power, the steam after power generation enters the condenser and is condensed into low-temperature liquid by seawater, and the condenser is pressurized by the working medium pump to send the low-temperature liquid back to the first evaporator and the second evaporator; and the desulfurizing tower is connected with the marine diesel engine through a flue, and the flue gas is output to the desulfurizing tower for cooling and desulfurizing. The invention realizes the recycling of the heat of the high-temperature and low-temperature grade of the flue gas, solves the problem that the heat of the flue gas in a temperature area lower than the acid dew point is difficult to recycle, and can improve the flue gas desulfurization efficiency.

Description

A marine organic Rankine cycle system with dual evaporators coupled with desulfurization towers

technical field

The invention relates to the field of marine equipment, in particular to a marine organic Rankine cycle system with double evaporators coupled with desulfurization towers.

Background technique

The shipping industry undertakes 90% of the world's cargo transportation volume. Economic globalization has promoted trade between countries and accelerated the development of the shipping market. At present, most ships rely on carbon-based fuel internal combustion engines for power. The thermal efficiency of diesel engines can be improved. Up to 48-51%, in order to improve the combustion efficiency of the diesel engine, the structure and combustion of the diesel engine are improved, but it is difficult to achieve a major breakthrough. About 50% of the energy of the diesel engine is still wasted, and a large amount of polluting vapors such as NOx and SOx are emitted at the same time. The waste heat of the main engine is of low grade, which is inconvenient to recover. The organic Rankine cycle can convert low-grade energy into mechanical energy, and has the advantages of simple structure, high thermal efficiency and good stability, which is more efficient than power turbine power generation and thermoelectric power generation. Suitable for ship waste heat recovery;

The patent number is CN109736963B, which discloses a waste heat utilization of a marine engine and a method thereof. The technical solution of the patent includes a water vapor Rankine cycle subsystem, an organic Rankine cycle subsystem and an absorption refrigeration cycle subsystem. The system coupling realizes the cascade utilization of the waste heat of ship engine flue gas and cooling water. The system of the invention is complicated, and it only performs cascade recovery for different heat sources, and does not consider the recovery of low-temperature heat after the acid dew point of the flue gas.

Patent application number: CN113187572A discloses a marine multi-evaporator organic Rankine cycle (ORC) system, which can effectively and simultaneously recycle the waste heat of different temperature grades generated by the ship's power plant including the ship's main engine and the ship's auxiliary generator. And the structure is compact and takes up less space. The invention uses pressurized air, high-temperature water vapor, and cylinder liner cooling water circuit as heat sources, and does not recover the heat of the flue gas.

Patent application number: CN104265427A discloses a combined cycle system for flue gas desulfurization and waste heat recovery of medium-speed diesel engines in ships. The flue gas of the diesel engine is heated by a waste heat boiler to generate steam to drive a steam turbine to generate electricity, and the flue gas enters a scrubber for purification and desulfurization. The invention realizes ultra-low emission of sulfides on the basis of effectively improving the utilization efficiency of waste heat capacity. In the invention, the flue gas is heated to 170°C after being exchanged by the boiler, the flue gas is directly washed and desulfurized, and there is still a large amount of unutilized flue gas energy.

The average temperature of the flue gas of marine diesel engines is around 300-400 °C, and the flue gas temperature can generally be reduced to 160 °C after passing through the boiler. The study found that with the increase of the flue gas temperature at the inlet of the desulfurization device, the desulfurization efficiency of seawater desulfurization will decrease. Therefore, it is necessary to cool down to the optimum desulfurization temperature of about 100 ℃ first, which is beneficial to the absorption of sulfur oxides and the desulfurization efficiency is high.

The current organic Rankine cycle system still has a key bottleneck problem in the heat recovery of sulfur-containing flue gas from marine diesel engines. Corrosion, the evaporator can only recover the heat from the flue gas exhaust temperature to the acid dew point temperature range (400-160°C), and the heat below the acid dew point temperature range (≤160°C) is difficult to recover. Therefore, it is urgent to seek technological breakthroughs in the heat recovery technology in the low temperature area of flue gas to ensure that the heat recovery rate can be maximized.

However, the existing technologies and patents do not consider how to recover the heat in the low temperature area after the acid dew point of the flue gas, and how to recover the heat of the cooling seawater. The flue gas and seawater are directly discharged into the environment, causing waste of energy and environmental damage. Pollution.

At the same time, there is a lack of a related combined power generation and desulfurization system on the ship, and the energy of sulfur-containing flue gas cannot be fully utilized, and seawater cannot be recycled for many times. the goal of.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a marine organic Rankine cycle system with dual evaporators coupled with desulfurization towers, which solves the problem that the heat of flue gas in the temperature region below the acid dew point is difficult to recover, and at the same time can improve the efficiency of flue gas desulfurization.

In order to achieve the above purpose, the present invention is achieved through the following technical solutions:

A marine organic Rankine cycle system with double evaporators coupled with desulfurization towers is characterized by including:

The first evaporator, the flue gas inlet of the first evaporator is connected to the exhaust port of the marine diesel engine through the flue, and the flue gas outlet of the first evaporator is connected to the flue gas inlet of the desulfurization tower through the flue, and the first evaporator is The working medium inlet of the evaporator is connected to the outlet of the working medium pump through a pipeline, and the working medium outlet of the first evaporator is connected to the inlet of the expander through a pipeline. The liquid working medium in the first evaporator absorbs the exhaust gas temperature in the flue gas to The heat in the acid dew point temperature range evaporates, producing high temperature and high pressure steam;

A desulfurization tower, the desulfurization tower includes a cooling tower and a washing tower connected to the cooling tower, the flue gas inlet of the cooling tower is connected to the flue gas outlet of the first evaporator through the flue, and the flue gas outlet of the cooling tower passes through the flue It is connected to the flue gas inlet of the washing tower, the bottom of the cooling tower is arranged with a water outlet, and the water outlet of the cooling tower is connected to the seawater inlet of the second evaporator through the pipeline, and the first evaporator will absorb the heat through the flue. The flue gas is output to the cooling tower, and the seawater in the cooling tower is used to spray and cool the flue gas, and the flue gas is cooled to the optimum desulfurization temperature. In the second evaporator; the washing tower is used to desulfurize the flue gas cooled to the optimum desulfurization temperature;

The second evaporator, its seawater inlet is connected to the seawater drain of the cooling tower through a pipeline, its seawater outlet is connected to the inlet of the washing tower through a pipeline, its working fluid inlet is connected to the working fluid pump outlet through a pipeline, and its working fluid outlet is connected through a pipeline. At the inlet of the expander, the working medium in the second evaporator absorbs the heat of the seawater discharged from the cooling tower and evaporates, producing high-temperature and high-pressure steam;

Expander, generator, condenser, sea water pump, the expander is connected to the first evaporator and the second evaporator, the high temperature and high pressure steam enters the expander to expand and do work, and the expander drives the generator to rotate to generate Electric energy, the low-pressure steam after the power generation is completed enters the condenser and exchanges heat with the seawater in the condenser. The low-pressure steam after the power generation is completed is condensed into a low-pressure and low-temperature liquid by the seawater, and the liquid is pressurized by the working fluid pump are sent to the second evaporator and the first evaporator respectively.

The cooling seawater of the cooling tower is stored at the bottom of the cooling tower, the bottom of the cooling tower is connected to the seawater inlet of the second evaporator, the cooling tower is connected to the washing tower through a pipeline, and the flue gas enters the washing tower through a pipeline.

The washing tower is provided with a second-stage sprayer and a first-stage sprayer in order from bottom to top according to the height, and the first-stage sprayer is connected to the outlet of the first seawater pump, and the first seawater pump uses The seawater is extracted and sprayed through a primary sprayer, the secondary sprayer is connected to the outlet of the third seawater pump, and the inlet of the third seawater pump is connected to the condenser and the seawater outlet of the second evaporator.

A sprayer is arranged above the inside of the cooling tower, and the sprayer in the cooling tower is connected to the first seawater pump.

The optimal desulfurization temperature range is 95°～105°.

The seawater inlet of the condenser is connected to the inlet of the first seawater pump.

Compared with the prior art, the present invention has the following advantages:

The flue gas passes through the first evaporator, the cooling tower attached to the desulfurization tower, and the washing tower in turn. The first evaporator recovers the heat of the high temperature grade from the exhaust gas temperature of the ship's diesel engine to the acid dew point temperature. The cooling tower attached to the desulfurization tower The inner seawater absorbs the heat from the acid dew point temperature of the ship's diesel engine flue gas to the optimal desulfurization temperature range, and at the same time utilizes the alkalinity of the seawater to neutralize a small amount of acid dew in the flue gas. The second evaporator recovers the heat of the seawater discharged from the cooling tower attached to the desulfurization tower, thereby indirectly recovering the heat of low temperature taste from the acid dew point temperature of the marine diesel engine flue gas to the optimal desulfurization temperature range.

Through the invention, the heat in the flue gas of the marine diesel engine can be recovered to the maximum extent, and the desulfurization efficiency of the flue gas can be improved at the same time. The invention can make full use of the flue gas for heat exchange and power generation, while solving the problem of difficult heat recovery in the temperature region where the flue gas is lower than the acid dew point temperature, can maximize the heat recovery rate and desulfurization efficiency, and can perform heat exchange on seawater after heat exchange. It has the characteristics of energy saving and emission reduction after repeated use.

Description of drawings

Fig. 1 is the system diagram of the organic Rankine cycle system of the double evaporator of a kind of marine coupling desulfurization tower of the present invention;

Figure 2 is a schematic diagram of the working principle of the desulfurization tower.

Detailed ways

The present invention will be further elaborated below by describing a preferred specific embodiment in detail with reference to the accompanying drawings.

As shown in Figure 1, a marine organic Rankine cycle system with double evaporators coupled with desulfurization towers, the system includes:

The first evaporator 1 and the second evaporator 5, the working fluid in the first evaporator 1 is used to absorb the heat from the exhaust gas temperature to the acid dew point temperature in the marine diesel engine flue gas and evaporate, and the working fluid in the second evaporator 5 It is used to absorb the heat of the seawater discharged from the cooling tower attached to the desulfurization tower and evaporate, and together produce high temperature and high pressure steam; the expander 7, the condenser 6, the expander 7, the high temperature and high pressure steam enters the expander to expand and do work, the expander 7. Drive the generator 8 to rotate to generate electrical energy, and the steam after the power generation is completed enters the condenser 6 and is condensed into low-temperature liquid by the seawater. The condenser 6 is pressurized by the working fluid pump 9 to return the low-temperature liquid to the first evaporator 1, the second evaporator 5;

The flue 2, the cooling tower 10 attached to the desulfurization tower, the flue gas inlet of the cooling tower 10 attached to the desulfurization tower is connected to the flue gas outlet of the first evaporator 1 through the flue 2, and the first evaporator 1 passes through the flue 2 The endothermic flue gas is output to the cooling tower 10, cooled by the seawater in the cooling tower 10, and the seawater absorbing the heat in the range from the acid dew point temperature of the flue gas to the optimum desulfurization temperature is discharged into the second evaporator 5, and It exchanges heat with the working fluid in the second evaporator 5 .

The cooling tower 10 attached to the desulfurization tower is connected to the washing tower 3 attached to the desulfurization tower through pipes, and the flue gas cooled to the optimum desulfurization temperature enters the washing tower 3 attached to the desulfurization tower for desulfurization, and the washing attached to the desulfurization tower is carried out. The tower 3 is provided with a secondary sprinkler 31 and a primary sprinkler 32 in order from bottom to top according to the height. The primary sprinkler 32 is connected to the outlet of the first seawater pump 4a through a pipeline, and the secondary sprinkler 31 passes through The pipeline is connected with the condenser 6 and the second evaporator 5. When the flue gas rises upwards in the scrubbing tower 3 attached to the desulfurization tower and is discharged to the outside, the flue gas is first treated by the secondary sprayer 31, and then the flue gas is treated by the secondary sprayer 31. The sprinkler performs the spray treatment.

The washing tower 3 attached to the desulfurization tower is provided with a discharge port, and the discharge port is connected with a pipeline. The washing tower 3 is connected to the second seawater pump 4b through the pipeline, and the washing tower 3 discharges seawater through the discharge port.

The seawater pump 4a is also connected to the condenser 6 through a pipeline, and the seawater is input into the condenser 6 through the first seawater pump 4a for heat exchange with the low-temperature and low-pressure steam in the condenser 6 .

The seawater discharge ports of the condenser 6 and the second evaporator 5 are connected to the secondary sprayer in the washing tower 3 attached to the desulfurization tower through pipes, and the condenser 6 and the second evaporator 5 pass the heat-exchanged seawater through the The third seawater pump 4c is uniformly discharged to the secondary sprinkler, and sprayed by the secondary sprinkler.

The working fluid inlet of the second evaporator 5 is connected to the working fluid pump 9 through a pipeline, which is convenient for the working fluid pump 9 to pressurize the low temperature working fluid liquid to the second evaporator 5, and the working fluid outlet of the second evaporator 5 passes through The pipeline is connected with the expander 7, and the pipeline is provided with a corresponding one-way valve, which is directly output to the expander 7 after exchanging heat with seawater and heating up to facilitate its power generation. The seawater inlet of the second evaporator 5 is connected to the desulfurization tower through the pipeline. The seawater discharge port of the attached cooling tower 10 is connected, and the attached cooling tower 10 of the desulfurization tower discharges the seawater heated by heat exchange to the second evaporator 5 to facilitate the endothermic evaporation of the working medium in the second evaporator 5 .

The average temperature of the flue gas of marine diesel engines is around 300-400 °C. After passing through the first evaporator, the flue gas temperature can generally be reduced to 160 °C. With the increase of the flue gas temperature at the inlet of the desulfurization device, the desulfurization efficiency of seawater desulfurization will decrease. Therefore, it is necessary to first perform spray cooling to cool down to the optimal desulfurization temperature (95°-105°, 100° in this embodiment), which is beneficial to the absorption of sulfur oxides and the desulfurization efficiency is high.

Based on the above principles, when the marine organic Rankine cycle system with dual evaporators coupled to the desulfurization tower is in use, the exhaust gas at 350°C of the marine diesel engine is discharged to the first evaporator 1, and the pentafluoropropane in the first evaporator 1 The working fluid absorbs the heat from the exhaust gas temperature to the acid dew point temperature in the flue gas and evaporates, and the flue gas temperature drops. Due to the acid dew point limit, the flue gas temperature drops to the acid dew point temperature of 160 °C, which does not reach the optimal desulfurization temperature. The flue gas at 160°C is further discharged into the cooling tower 10 attached to the desulfurization tower to be cooled by seawater (15°C), and the seawater in the cooling tower 10 attached to the desulfurization tower absorbs the acid dew point temperature of the flue gas to the optimum desulfurization temperature. At the same time, the temperature of the seawater after absorbing the heat of the flue gas rises to 95°C and is discharged to the second evaporator 5. The high temperature and high pressure pentafluoropropane produced by the first evaporator The steam is output to the expander 7, the expander 7 uses the high-temperature and high-pressure pentafluoropropane steam to rotate to generate electricity, and the low-pressure pentafluoropropane steam after the power generation is completed enters the condenser 6, and the condenser 6 is connected to the first seawater pump 4a through a pipeline. Connected, the first seawater pump 4a can pump seawater at 15°C into the condenser 6, and the seawater in the condenser 6 exchanges heat with the low-pressure pentafluoropropane vapor after the power generation is completed, and the seawater is heated and sent to the second stage through the pipeline At the sprinkler 31, the low-pressure pentafluoropropane vapor after the power generation is completed is condensed into a low-pressure and low-temperature pentafluoropropane liquid, and the pentafluoropropane liquid is pressurized by the working fluid pump 9 and sent to the second evaporator 5 and the first In the first evaporator 1, the first evaporator 1 realizes the recovery of the heat of the flue gas in the range from the exhaust gas temperature to the acid dew point temperature. The pentafluoropropane liquid in the second evaporator 5 absorbs the heat of 95°C seawater discharged from the cooling tower 10 attached to the desulfurization tower and evaporates to generate high temperature and high pressure pentafluoropropane vapor, which is output to the expander 7, The expander 7 uses the high temperature and high pressure pentafluoropropane vapor to rotate to generate electricity, the second evaporator 5 realizes heat absorption of the seawater discharged from the cooling tower, and the seawater after the heat absorption in the second evaporator 5 is transmitted to the secondary sprayer 31 place. The cooled flue gas reaches the optimum desulfurization temperature and is further transferred to the scrubbing tower 3 attached to the desulfurization tower, and sprayed by the secondary sprayer 31 and the primary sprayer 32 to realize the desulfurization of the flue gas, and the desulfurization is completed. The latter fumes are discharged into the air (see Figure 2).

To sum up, the present invention is a marine organic Rankine cycle system with dual evaporators coupled with desulfurization towers, which can make full use of flue gas for heat exchange and power generation, and solves the problem that heat is difficult to recover in the low temperature region where the flue gas is lower than the acid dew point. It can maximize the heat recovery rate and desulfurization efficiency, and can reuse the seawater after heat exchange for many times.

While the content of the present invention has been described in detail by way of the above preferred embodiments, it should be appreciated that the above description should not be construed as limiting the present invention. Various modifications and alternatives to the present invention will be apparent to those skilled in the art upon reading the foregoing. Accordingly, the scope of protection of the present invention should be defined by the appended claims.

Claims (6)

1. A marine dual-evaporator organic Rankine cycle system of a coupled desulfurization tower, comprising:

the device comprises a first evaporator, a flue gas inlet of the first evaporator is connected with an exhaust port of a marine diesel engine through a flue, a flue gas outlet of the first evaporator is connected with a flue gas inlet of a desulfurizing tower through a flue, a working medium inlet of the first evaporator is connected with an outlet of a working medium pump through a pipeline, a working medium outlet of the first evaporator is connected with an inlet of an expansion machine through a pipeline, and a liquid working medium in the first evaporator absorbs heat of an exhaust temperature range from the exhaust temperature to an acid dew point temperature range in the flue gas for evaporation to generate high-temperature and high-pressure steam;

the desulfurization tower comprises a cooling tower and a washing tower connected with the cooling tower, a flue gas inlet of the cooling tower is connected to a flue gas outlet of a first evaporator through a flue, a flue gas outlet of the cooling tower is connected to a flue gas inlet of the washing tower through a flue, a water outlet is arranged at the bottom of the cooling tower, the water outlet of the cooling tower is connected to a seawater inlet of a second evaporator through a pipeline, the first evaporator outputs the flue gas subjected to heat absorption into the cooling tower through the flue, the seawater in the cooling tower is used for carrying out spray cooling on the flue gas, the flue gas is cooled to the optimal desulfurization temperature, and the seawater absorbs the heat of the range from the acid dew point of the flue gas to the optimal desulfurization temperature and then is discharged into the second evaporator; the washing tower is used for desulfurizing the flue gas cooled to the optimal desulfurization temperature;

the seawater inlet of the second evaporator is connected with the seawater outlet of the cooling tower through a pipeline, the seawater outlet of the second evaporator is connected with the inlet of the washing tower through a pipeline, the working medium inlet of the second evaporator is connected with the outlet of the working medium pump through a pipeline, the working medium outlet of the second evaporator is connected with the inlet of the expansion machine through a pipeline, and the working medium in the second evaporator absorbs the heat of the seawater discharged from the cooling tower and evaporates to generate high-temperature and high-pressure steam;

expander, generator, condenser, sea water pump, the expander is connected in first evaporimeter and second evaporimeter, the inflation does work in the high-temperature highly compressed steam gets into the expander, the expander drives the generator and rotates and produce the electric energy, and the low pressure steam after the electricity generation is accomplished gets into the condenser, and with sea water in the condenser carries out the heat exchange, and the low pressure steam after the electricity generation is accomplished is become low pressure microthermal liquid by the sea water condensation, and this liquid is carried respectively in second evaporimeter and the first evaporimeter through working medium pump pressurization.

2. The dual-evaporator organic Rankine cycle system of a coupled desulfurization tower for a ship as set forth in claim 1, wherein the cooling seawater of the cooling tower is stored at the bottom of the cooling tower, the cooling tower is connected with a washing tower through a pipe, the flue gas enters the washing tower through the pipe, the cooling seawater of the washing tower is stored at the bottom of the washing tower, and the bottom of the washing tower is connected to an inlet of a second seawater pump.

3. The dual-evaporator orc system of a coupled desulfurization tower for a ship of claim 2, wherein a second spray and a first spray are sequentially disposed in the scrubber from bottom to top in height, the first spray is connected to an outlet of a first seawater pump, the first seawater pump is used for pumping seawater and spraying the seawater through the first spray, the second spray is connected to an outlet of a third seawater pump, and an inlet of the third seawater pump is connected to the condenser and the seawater outlet of the second evaporator.

4. The twin evaporator orc system of a coupled desulfurization tower for a ship as set forth in claim 2, wherein a spray shower is disposed above the inside of the cooling tower, and the spray shower in the cooling tower is connected to the first seawater pump.

5. The orc system of claim 1, wherein the optimum desulfurization temperature range is 95 ° to 105 °.

6. The dual evaporator orc system of claim 1, wherein the condenser has a seawater inlet connected to an inlet of the first seawater pump.

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