Medium-temperature tail gas waste heat recovery cold and hot water unit of diesel generating set

Abstract

The invention relates to a medium-temperature tail gas waste heat recovery cold and hot water unit of a diesel generating set. The problems of tail gas expansion noise and tail gas thermal pollution are fundamentally solved. Diesel generators are connected in parallel to form a diesel engine unit which is communicated with a high-temperature fan, the high-temperature fan is communicated with a heat conduction oil heat exchanger, the heat conduction oil heat exchanger is communicated with a high-pressure generator, lithium bromide solution is contained in the high-pressure generator, and the high-pressure generator is respectively communicated with a low-pressure generator and a low-temperature heat exchanger. The low-pressure generator is respectively communicated with the condenser, the low-temperature heat exchanger, the evaporator and the high-temperature heat exchanger, the high-temperature heat exchanger is simultaneously communicated with the collector, the heat-conducting oil heat exchanger is communicated with the heat-conducting oil intermediate oil tank through a heat-conducting oil main pipeline, and the heat-conducting oil main pipeline is provided with an air exhaust device. By means of the double-effect lithium bromide absorption technology, waste heat of the diesel engine tail gas is used for refrigeration or heat supply, and the comprehensive heat efficiency of the diesel generating set is improved.

Description

Technical Field

[0001] The present invention relates to a waste heat recovery device, in particular to a hot and cold water unit for recovering waste heat from medium-temperature tail gas of a diesel generator set. Background Art

[0002] The main principle of a diesel generator set is that diesel combustion in the cylinder generates heat energy. The expanding gas drives the piston, converting the heat energy into mechanical energy. The rotating crankshaft, through a coupling, reverses the generator, converting the mechanical energy into electrical energy. However, currently, diesel engine efficiency generally falls below 50%, and a large amount of heat energy is released into the environment with exhaust. The presence of nitrogen oxides in high-temperature exhaust gas can seriously pollute the environment. High-temperature exhaust gas also directly causes environmental thermal pollution, and the expansion of high-temperature exhaust gas indirectly causes noise pollution, seriously affecting the occupational health of operators. To utilize the large amount of heat energy contained in diesel generator exhaust, reduce exhaust pollutants, and reduce exhaust thermal and noise pollution.

[0003] CN114654995A proposes a hybrid refrigerated truck waste heat recovery system that recovers jacket water and exhaust gas waste heat to generate the required cooling capacity and electrical energy for the refrigerated truck. Its system structure and purpose differ from the present invention. CN216638962U proposes a diesel engine exhaust waste heat utilization device for heating seawater in the desalination field. Its structure and purpose differ from the present invention. Summary of the Invention

[0004] The purpose of the present invention is to construct a diesel generator set exhaust waste heat hot and cold water system based on a traditional generator set, utilize the waste heat in the diesel generator set exhaust gas to meet the needs of cooling and heating, improve the comprehensive fuel consumption rate of the diesel generator set, and fundamentally solve the problems of exhaust gas expansion noise and exhaust gas thermal pollution.

[0005] The present invention proposes a diesel generator set exhaust waste heat recovery cold and hot water system, which utilizes the diesel generator set exhaust waste heat for cooling or heating through a double-effect lithium bromide absorption process to improve the comprehensive thermal efficiency of the diesel generator set.

[0006] The present invention is achieved by the following technical solutions:

[0007] A diesel generator set with medium-temperature exhaust waste heat recovery hot and cold water unit includes a diesel generator set 1, a high-temperature fan 5, a thermal oil heat exchanger 6, a thermal oil intermediate tank 7, a high-pressure generator 8, a low-pressure generator 9, an evaporator 14, an absorber 13, a condenser 10, a high-temperature heat exchanger 12 and a low-temperature heat exchanger 11. The diesel generators are connected in parallel to form a diesel engine group connected to the high-temperature fan 5, the high-temperature fan 5 is connected to the thermal oil heat exchanger 6, the thermal oil heat exchanger 6 is connected to the high-pressure generator 8, the high-pressure generator 8 is filled with lithium bromide solution, the high-pressure generator 8 is respectively connected to the low-pressure generator 9 and the low-temperature heat exchanger 11, the low-pressure generator 9 is respectively connected to the condenser 10, the low-temperature heat exchanger 11, the evaporator 14 and the high-temperature heat exchanger 12, the high-temperature heat exchanger 12 is simultaneously connected to the absorber 13, the thermal oil heat exchanger 6 is connected to the thermal oil intermediate tank 7 through the thermal oil main line, and the thermal oil main line is provided with an air exhaust device.

[0008] This invention can provide additional cooling and heating capacity, improving the operating economy of diesel generator sets in remote areas and providing high-quality cooling and heating sources in remote, cold regions. The system uses readily available lithium bromide solution as the working medium, and the components of the diesel generator's medium-temperature exhaust waste heat power generation system are well-manufactured. The adjustment parameters of some components of the hot and cold water units are guided by national standards, ensuring reliability and low construction costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a schematic structural diagram of the present invention;

[0010] The figure shows a diesel engine unit 1, a diesel generator 2, a diesel generator exhaust manifold 3, a diesel generator exhaust main pipe 4, a high-temperature fan 5, a thermal oil heat exchanger 6, a thermal oil intermediate tank 7, a high-pressure generator 8, a low-pressure generator 9, a condenser 10, a low-temperature heat exchanger 11, a high-temperature heat exchanger 12, an absorber 13, and an evaporator 14;

[0011] Figure 2 It is a refrigeration embodiment of the present invention;

[0012] Figure 3 This is a heating embodiment of the present invention. DETAILED DESCRIPTION

[0013] like Figure 1As shown, the present invention is a diesel generator set medium-temperature exhaust waste heat recovery chiller and hot water unit, comprising a diesel generator set 1, a high-temperature fan 5, a thermal oil heat exchanger 6, a thermal oil intermediate tank 7, a high-pressure generator 8, a low-pressure generator 9, an evaporator 14, an absorber 13, a condenser 10, a high-temperature heat exchanger 12, and a low-temperature heat exchanger 11. The need for a high-temperature fan is determined based on the number of diesel generators being recovered and the exhaust back pressure. If the piping layout has a minimal impact on exhaust back pressure, a high-temperature fan is not selected; otherwise, a high-temperature fan is selected. The cooling tower can be selected as either an open or closed cooling tower depending on whether domestic hot water is required. A closed cooling tower is preferred if domestic hot water is required; otherwise, an open cooling tower is preferred. If the heat energy of the diesel generator jacket cooling water needs to be recovered, thermal oil can be used to exchange heat with the jacket water through a heat exchanger, and then be combined with the exhaust gas heat oil for reuse.

[0014] The working principle of the system is explained in the cooling mode, and the working principle of the heating mode is shown in the embodiment. The process layout is that the diesel generators 2 are connected in parallel to form a diesel engine group 1, the exhaust manifolds 3 of the diesel generator groups are connected in parallel, and the high-temperature fan 5 is connected in series through the diesel generator exhaust main pipe 4. The tail gas of the high-temperature fan 5 enters the thermal oil heat exchanger 6. In the thermal oil heat exchanger 6, the tail gas and the thermal oil are fully exchanged with each other. The heated thermal oil enters the high-pressure generator 8. When the thermal oil is heated or shut down, the thermal oil enters the thermal oil intermediate tank 7. There is an air exhaust device on the thermal oil main line. In the high-pressure generator 8, the lithium bromide solution is heated by the thermal oil to generate steam. The steam is passed to the low-pressure generator 9 as the internal heat source for heating the solution. In the low-pressure generator 9, due to the heating, part of the steam is generated and mixed with the steam from the high-pressure generator 8. The steam flows together and is used as a refrigerant to flow to the condenser 10 and evaporator 14 for cooling. As the lithium bromide solution in the high-pressure generator 8 is heated and evaporates into steam, its concentration increases and becomes an intermediate solution. The intermediate solution flows to the low-temperature heat exchanger 11 for heat exchange and cooling. The cooled intermediate solution flows to the low-pressure generator 9. Due to further steam evaporation in the low-pressure generator 9, the intermediate solution becomes a concentrated solution. The concentrated solution flows to the high-temperature heat exchanger 12. In the high-temperature heat exchanger 12, the concentrated solution is cooled and flows to the absorber 13. In the absorber 13, the concentrated solution absorbs the condensed water from the low-pressure steam to form a dilute solution. The dilute solution is pumped sequentially through the high-temperature heat exchanger 12 and the low-temperature heat exchanger 11, and flows to the high-pressure generator 8 to complete the next cycle. In the evaporator 14, the cold water used for cooling passes through the evaporator. Due to the condensation of steam, the cold water is further cooled and delivered to the user end.

[0015] The energy efficiency limit values and energy efficiency grades of lithium bromide absorption chillers should meet the requirements of the national standard GB29540-2013.

[0016] The waste heat utilization process of the unit of the present invention mainly includes the following process flow:

[0017] Step S0: Start the cooling water circulation system;

[0018] Step S1: The diesel generator set is started and the high-temperature fan is turned on as needed;

[0019] Step S2: The tail gas is heat exchanged through the thermal oil heat exchanger, the thermal oil circulation pump is turned on to circulate the thermal oil between the thermal oil heat exchanger and the high-pressure generator, and the thermal oil system exhauster is turned on.

[0020] Step S3: The cold water circulation system is put into operation, and natural circulation or forced circulation can be performed according to the user's end conditions;

[0021] Step S4: Start the automatic air extraction device on the dilute solution main pipe to remove the air mixed in the medium;

[0022] Step S5: Start the medium-temperature tail gas waste heat recovery hot and cold water unit circulation, control the steam pressure and temperature of the high-pressure generator and the low-pressure generator by the heat transfer oil circulation volume, and prevent crystallization on the concentrated solution side of the low-temperature heat exchanger.

[0023] Example:

[0024] like Figure 2 As shown in the figure, the refrigeration mode of the diesel generator set medium-temperature exhaust waste heat recovery hot and cold water unit mainly includes the following steps:

[0025] Step S0: The diesel generator set is started, and the high-temperature fan is turned on or bypassed to transport the exhaust gas according to the exhaust gas back pressure. The circulating water cooling system is started, and the cold water is circulated in the middle of the evaporator under the user-side refrigeration condition;

[0026] Step S1: Turn on the thermal oil heat exchanger and use the tail gas to heat the thermal oil. The thermal oil expands due to the heat, and part of the thermal oil enters the thermal oil intermediate tank according to the delivery pressure limit of the thermal oil circulation pump;

[0027] Step S2: When the steam pressure of the high-pressure generator reaches the target pressure, the steam is passed to the low-pressure generator for heating;

[0028] Step S3: Start the working medium circulation pump to maintain the liquid level balance of the absorber, high pressure generator, and low pressure generator;

[0029] Step S4: adjusting the cold and hot flow rates of the low-temperature heat exchanger and the high-temperature heat exchanger, and controlling the working pressures of the high-pressure generator and the low-pressure generator;

[0030] Step S5: Adjust the cold water flow rate so that the inlet and outlet temperatures of the cold water are 7-12°C.

[0031] like Figure 3 As shown in the figure, the heating mode of the diesel generator set medium-temperature exhaust waste heat recovery cold and hot water unit mainly includes the following steps:

[0032] Step S0: The diesel generator set is started, and the high-temperature fan is turned on or bypassed to transport the exhaust gas according to the exhaust gas back pressure. Under the user-side cooling condition, hot water is circulated in the middle of the evaporator;

[0033] Step S1: Turn on the thermal oil heat exchanger and use the exhaust gas to heat the thermal oil. The thermal oil expands due to the heat, and according to the delivery pressure limit of the thermal oil circulation pump, some of the thermal oil enters the thermal oil intermediate tank;

[0034] Step S2: When the steam pressure of the high-pressure generator reaches the target pressure, the steam is passed to the evaporator for heating;

[0035] Step S3: Start the working medium circulation pump to maintain the liquid level balance of the absorber, high pressure generator, and low pressure generator;

[0036] Step S4: Regulate the hot and cold flow rates of the low-temperature heat exchanger and the high-temperature heat exchanger to control the working pressures of the high-pressure generator and the low-pressure generator.

[0037] Step S5: Regulate the hot water flow rate to obtain high-quality thermal energy.

[0038] Compared with existing technologies, this invention is suitable for diesel generator set applications such as industrial plants, emergency power supply, and cooling or heating needs in remote areas. It is also suitable for diesel generator set renovation and expansion, with relatively low new construction and renovation costs. Existing systems can be retrofitted to recover exhaust heat from diesel generator sets without changing the existing process.

[0039] The above is a further detailed description of the present invention in conjunction with specific preferred embodiments, and the specific implementation of the present invention should not be considered to be limited to these descriptions. For those skilled in the art to which the present invention relates, if equivalent substitutions or obvious modifications are made without departing from the concept of the present invention and the performance or use is the same, they should be deemed to fall within the scope of protection defined by the claims submitted by the present invention.

Claims

1. A diesel generator set medium-temperature exhaust waste heat recovery hot and cold water unit, characterized by: It includes a diesel generator set, a high-temperature fan, a thermal oil heat exchanger, a thermal oil intermediate tank, a high-pressure generator, a low-pressure generator, an evaporator, an absorber, a condenser, a high-temperature heat exchanger and a low-temperature heat exchanger. The diesel generators are connected in parallel to form a diesel engine group connected to the high-temperature fan, the high-temperature fan is connected to the thermal oil heat exchanger, the thermal oil heat exchanger is connected to the high-pressure generator, the high-pressure generator is filled with lithium bromide solution, the high-pressure generator is respectively connected to the low-pressure generator and the low-temperature heat exchanger, the low-pressure generator is respectively connected to the condenser, the low-temperature heat exchanger, the evaporator and the high-temperature heat exchanger, the high-temperature heat exchanger is also connected to the receiver, the thermal oil heat exchanger is connected to the thermal oil intermediate tank through the thermal oil main line, and the thermal oil main line is equipped with an air exhaust device.

2. A diesel generator set medium-temperature exhaust waste heat recovery hot and cold water unit according to claim 1, characterized in that: The waste heat recovery cold and hot water unit waste heat utilization process includes the following process flow: Step S0: Start the cooling water circulation system; Step S1: The diesel generator set is started and the high-temperature fan is turned on as needed; Step S2: The tail gas is heat exchanged through the thermal oil heat exchanger, the thermal oil circulation pump is turned on to circulate the thermal oil between the thermal oil heat exchanger and the high-pressure generator, and the thermal oil system exhauster is turned on. Step S3: The cold water circulation system is put into operation, and natural circulation or forced circulation can be performed according to the user's end conditions; Step S4: Start the automatic air extraction device on the dilute solution main pipe to remove the air mixed in the medium; Step S5: Start the medium-temperature tail gas waste heat recovery hot and cold water unit circulation, control the steam pressure and temperature of the high-pressure generator and the low-pressure generator by the heat transfer oil circulation volume, and prevent crystallization on the concentrated solution side of the low-temperature heat exchanger.

3. The diesel generator set medium-temperature exhaust waste heat recovery hot and cold water unit according to claim 1, characterized in that: The refrigeration mode of the diesel generator set medium-temperature exhaust waste heat recovery hot and cold water unit includes the following steps: Step S0: The diesel generator set is started, and the high-temperature fan is turned on or bypassed to transport the exhaust gas according to the exhaust gas back pressure. The circulating water cooling system is started, and the cold water is circulated in the middle of the evaporator under the user-side refrigeration condition; Step S1: Turn on the thermal oil heat exchanger and use the tail gas to heat the thermal oil. The thermal oil expands due to the heat, and part of the thermal oil enters the thermal oil intermediate tank according to the delivery pressure limit of the thermal oil circulation pump; Step S2: When the steam pressure of the high-pressure generator reaches the target pressure, the steam is passed to the low-pressure generator for heating; Step S3: Start the working medium circulation pump to maintain the liquid level balance of the absorber, high pressure generator, and low pressure generator; Step S4: adjusting the cold and hot flow rates of the low-temperature heat exchanger and the high-temperature heat exchanger, and controlling the working pressures of the high-pressure generator and the low-pressure generator; Step S5: Adjust the cold water flow rate so that the inlet and outlet temperatures of the cold water are 7-12°C.

4. The diesel generator set medium-temperature exhaust waste heat recovery hot and cold water unit according to claim 1, characterized in that: The heating mode of the diesel generator set medium-temperature exhaust waste heat recovery hot and cold water unit includes the following steps: Step S0: The diesel generator set is started, and the high-temperature fan is turned on or bypassed to transport the exhaust gas according to the exhaust gas back pressure. Under the user-side cooling condition, hot water is circulated in the middle of the evaporator; Step S1: Turn on the thermal oil heat exchanger to heat the thermal oil using the tail gas. The heat transfer oil expands due to heat, and according to the delivery pressure limit of the heat transfer oil circulation pump, part of the heat transfer oil enters the heat transfer oil intermediate tank; Step S2: When the steam pressure of the high-pressure generator reaches the target pressure, the steam is passed to the evaporator for heating; Step S3: Start the working medium circulation pump to maintain the liquid level balance of the absorber, high pressure generator, and low pressure generator; Step S4: adjusting the cold and hot flow rates of the low-temperature heat exchanger and the high-temperature heat exchanger, and controlling the working pressures of the high-pressure generator and the low-pressure generator; Step S5: Regulate the hot water flow rate to obtain high-quality thermal energy.

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