Biomass drying system and method integrating air drying cycle and organic Rankine cycle

Abstract

The invention discloses an air drying cycle and organic Rankine cycle integrated biomass drying system and method, and belongs to the field of energy conservation. In the top air drying circulation, waste heat energy is adopted as a heat source to dry materials, solid impurities in obtained wet air are removed through a cyclone separator, and latent heat and sensible heat of the high-temperature wet air are recycled through a superheater and a condenser; an ammonia-water solution is adopted as a working medium of the organic Rankine cycle at the bottom, and certain net work is output to the outside under the condition that the output work of a turbine meets the power consumption of a pressure working medium pump. According to the system, low-grade heat such as terrestrial heat, sunlight heat and industrial waste heat can be used as a heat source, and the system can be used for low-temperature drying of biomass such as cereals, tobaccos and wood and meanwhile outputs certain net work to the outside; the high latent heat of evaporation of ammonia-water is utilized, heat can be more effectively converted into mechanical energy while being absorbed, the overall efficiency of heat circulation is improved, and compared with a conventional air biomass drying process, the air biomass drying device has the advantages of overall energy conservation and high efficiency.

Description

Technical Field

[0001] The invention relates to a biomass drying system and method integrating an air drying cycle and an organic Rankine cycle, and belongs to the field of energy conservation. Background Art

[0002] Most agricultural and seafood products need to be dried before storage to maintain their quality and nutrition. Air drying is one of the most popular methods today. In order to effectively dry these wet materials and avoid material deterioration due to high moisture content, traditional air drying methods often use electricity or fuel to directly heat the air to reach the required high temperature. This method has low thermal efficiency and a large amount of energy is consumed in the heating process. The air is usually discharged directly after passing through the drying chamber, and the sensible heat and latent heat therein are not recovered and reused, resulting in energy waste and thermal pollution to the environment. Traditional air drying methods have great limitations in energy utilization and drying effects, especially when processing large amounts of materials. These problems are more prominent. Therefore, how to reduce the energy consumption of the air drying process and find an efficient, energy-saving and environmentally friendly air drying technology have become the focus of research and application. Summary of the invention

[0003] The object of the present invention is to provide a biomass drying system and method integrating an air drying cycle and an organic Rankine cycle (ORC), which can fully recycle the sensible heat and latent heat of wet air, have high thermal efficiency and obvious energy-saving effect.

[0004] The present invention adopts the following technical solutions to solve the above technical problems: A biomass drying system integrating an air drying cycle and an organic Rankine cycle (ORC), characterized in that it comprises a first preheater, a heater, a cyclone separator, a fan, a superheater, a condenser, a first gas-liquid separator, a condensate pump, a condensate storage tank, a turbine, a condenser, an ammonia-water pump, and a second gas-liquid separator; The first preheater, superheater, condenser and condensate pump include a cold side inlet, a cold side outlet, a hot side inlet and a hot side outlet; The heater comprises a cold side inlet, a cold side outlet, a hot side inlet, a hot side outlet and a dry material outlet; The cyclone separator comprises an air inlet, an air outlet and an impurity outlet; The cold side inlet of the first preheater is connected to the incoming air, and the cold side outlet is connected to the cold side inlet of the heater; The cold side outlet of the heater is connected to the air inlet of the cyclone separator, the hot side inlet of the heater is connected to the heat source medium, and the hot side outlet is connected to the environment; The impurity outlet of the cyclone separator is connected to the environment, and the air outlet is connected to the inlet of the fan; The outlet of the fan is connected to the hot side inlet of the first preheater, and the hot side outlet is connected to the hot side inlet of the superheater; The hot side outlet of the superheater is connected to the hot side inlet of the condenser, and the hot side outlet of the condenser is connected to the inlet of the first gas-liquid separator; The top gas outlet of the first gas-liquid separator is connected to the incoming air, and the bottom condensate outlet is connected to the inlet of the condensate pump; The outlet of the condensate pump is connected to the inlet of the condensate storage tank; The cold side inlet of the condenser is connected to the outlet of the ammonia-water pump, and the cold side outlet is connected to the inlet of the second gas-liquid separator; The top gas outlet of the second gas-liquid separator is connected to the cold side inlet of the superheater, and the bottom ammonia-water liquid is connected to the inlet of the ammonia-water pump; The cold side outlet of the superheater is connected to the inlet of the turbine, and the outlet of the turbine is connected to the hot side inlet of the condenser; The hot side outlet of the condenser is connected to the inlet of the ammonia-water pump.

[0005] The present invention also discloses a working method of a biomass drying system integrating an air drying cycle and an organic Rankine cycle (ORC), including the following working methods: In the top air drying cycle, the incoming air with a relatively low moisture content flows through the first preheater and is preheated by the air at the fan outlet, and then enters the heater, where the heat energy of the heat source medium is used to dry the material, and the material is discharged from the dry material outlet of the heater after being dried; due to the heat and mass transfer in the heater, the moisture in the material evaporates and enters the air, and the relative moisture content of the air at the cold side outlet of the heater increases to become wet air; then the wet air enters the cyclone separator to separate the impurities mixed in the wet air after the material is dried, and the separated impurities are discharged through the impurity outlet; the air enters the fan and is compressed, and the compressed wet air enters the first preheater to preheat the incoming air, and then passes through the superheater and condenser in turn for cooling and dehumidification, removes the moisture absorbed in the heater, releases sensible heat and latent heat to the ammonia-water on the cold side of the superheater and the condenser, and the temperature is lowered, and then enters the first gas-liquid separator, the gaseous air separated at the top circulates back to the incoming air, and the condensate separated at the bottom enters the condensate pump for compression and enters the condensate storage tank for storage.

[0006] In the bottom organic Rankine cycle, the circulating working fluid ammonia-water is pressurized by the ammonia-water pump and then enters the condenser to absorb heat. After absorbing heat, it enters the second gas-liquid separator. The outlet of the second gas-liquid separator is divided into two paths: the high-temperature ammonia-water solution separated at the bottom is circulated back to the ammonia-water pump; the gaseous ammonia separated at the top enters the condenser to absorb heat, and then enters the turbine to expand and do work, driving the ammonia-water pump to do work. The exhaust gas at the turbine outlet enters the condenser and is cooled by the water entering the cold side inlet, and then is pressurized by the ammonia-water pump to start the next cycle.

[0007] Compared with the prior art, the present invention adopts the above technical solution and has the following technical effects: The drying system integrating air drying with the organic Rankine cycle can not only efficiently separate the solid powder in the air in the later stage of drying through the heater and cyclone separator, but also reuse the waste heat by releasing latent heat and sensible heat in the superheater and condenser; ammonia-water is used as the working fluid of the organic Rankine cycle, which has a high latent heat of evaporation and can effectively absorb heat under low temperature conditions, significantly improving the efficiency of the thermal cycle; ammonia-water has good heat transfer performance and can efficiently transfer heat in the heat exchanger to reduce heat loss; ammonia-water can operate efficiently in a wide temperature range and is suitable for waste heat recovery at different temperatures, including industrial waste heat, geothermal heat and solar heat; under the condition that the work of the turbine meets the power consumption of the working fluid pump and compressor, ammonia still has a certain net work output to the outside, significantly improving energy utilization efficiency and reducing operating costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 It is a schematic diagram of the structure of the present invention; In the figure, 1-first preheater, 2-heater, 3-cyclone separator, 4-fan, 5-superheater, 6-condenser, 7-first gas-liquid separator, 8-condensate pump, 9-condensate storage tank, 10-turbine, 11-condenser, 12-ammonia-water pump, 13-second gas-liquid separator. DETAILED DESCRIPTION

[0009] Combination Figure 1 As shown, the first preheater, superheater, condenser and condensate pump include a cold side inlet, a cold side outlet, a hot side inlet and a hot side outlet; The heater comprises a cold side inlet, a cold side outlet, a hot side inlet, a hot side outlet and a dry material outlet; The cyclone separator comprises an air inlet, an air outlet and an impurity outlet; The cold side inlet of the first preheater is connected to the incoming air, and the cold side outlet is connected to the cold side inlet of the heater; The cold side outlet of the heater is connected to the air inlet of the cyclone separator 3, the hot side inlet of the heater 2 is connected to the heat source medium, and the hot side outlet is connected to the environment; The impurity outlet of the cyclone separator is connected to the environment, and the air outlet is connected to the inlet of the fan; The outlet of the fan is connected to the hot side inlet of the first preheater, and the hot side outlet is connected to the hot side inlet of the superheater; The hot side outlet of the superheater is connected to the hot side inlet of the condenser, and the hot side outlet of the condenser is connected to the inlet of the first gas-liquid separator; The top gas outlet of the first gas-liquid separator is connected to the incoming air, and the bottom condensate outlet is connected to the inlet of the condensate pump; The outlet of the condensate pump is connected to the inlet of the condensate storage tank; The cold side inlet of the condenser is connected to the outlet of the ammonia-water pump, and the cold side outlet is connected to the inlet of the second gas-liquid separator (13); The top gas outlet of the second gas-liquid separator is connected to the cold side inlet of the superheater, and the bottom ammonia-water liquid is connected to the inlet of the ammonia-water pump; The cold side outlet of the superheater is connected to the inlet of the turbine, and the outlet of the turbine is connected to the hot side inlet of the condenser; The hot side outlet of the condenser is connected to the inlet of the ammonia-water pump.

[0010] The present invention also discloses a working method of a biomass drying system integrating an air drying cycle and an organic Rankine cycle (ORC), comprising the following working processes: In the top air drying cycle, the incoming air with a relatively low moisture content flows through the first preheater and is preheated by the air at the fan outlet, and then enters the heater, where the heat energy of the heat source medium is used to dry the material, and the material is discharged from the dry material outlet of the heater after being dried; due to the heat and mass transfer in the heater, the moisture in the material evaporates and enters the air, and the relative moisture content of the air at the cold side outlet of the heater increases to become wet air; then the wet air enters the cyclone separator to separate the impurities mixed in the wet air after the material is dried, and the separated impurities are discharged through the impurity outlet; the air enters the fan and is compressed, and the compressed wet air enters the first preheater to preheat the incoming air, and then passes through the superheater and condenser in turn for cooling and dehumidification, removes the moisture absorbed in the heater, releases sensible heat and latent heat to the ammonia-water on the cold side of the superheater and the condenser, and the temperature is lowered, and then enters the first gas-liquid separator, the gaseous air separated at the top circulates back to the incoming air, and the condensate separated at the bottom enters the condensate pump for compression and enters the condensate storage tank for storage.

[0011] In the bottom organic Rankine cycle, the circulating working fluid ammonia-water is pressurized by the ammonia-water pump and then enters the condenser to absorb heat. After absorbing heat, it enters the second gas-liquid separator. The outlet of the second gas-liquid separator is divided into two paths: the high-temperature ammonia-water solution separated at the bottom is circulated back to the ammonia-water pump; the gaseous ammonia separated at the top enters the condenser to absorb heat, and then enters the turbine to expand and do work, driving the ammonia-water pump to do work. The exhaust gas at the turbine outlet enters the condenser and is cooled by the water entering the cold side inlet, and then is pressurized by the ammonia-water pump to start the next cycle.

Claims

1. A biomass drying system integrating air drying cycle and organic Rankine cycle, characterized in that: It comprises a first preheater (1), a heater (2), a cyclone separator (3), a fan (4), a superheater (5), a condenser (6), a first gas-liquid separator (7), a condensate pump (8), a condensate storage tank (9), a turbine (10), a condenser (11), an ammonia-water pump (12), and a second gas-liquid separator (13); The first preheater (1), superheater (5), condenser (6) and condensate pump (8) include a cold side inlet, a cold side outlet, a hot side inlet and a hot side outlet; The heater (2) comprises a cold side inlet, a cold side outlet, a hot side inlet, a hot side outlet and a dry material outlet; The cyclone separator (3) comprises an air inlet, an air outlet and an impurity outlet; The cold side inlet of the first preheater (1) is connected to the incoming air, and the cold side outlet is connected to the cold side inlet of the heater (2); The cold side outlet of the heater (2) is connected to the air inlet of the cyclone separator (3), the hot side inlet of the heater (2) is connected to the heat source medium, and the hot side outlet is connected to the environment; The impurity outlet of the cyclone separator (3) is connected to the environment, and the air outlet is connected to the inlet of the fan (4); The outlet of the fan (4) is connected to the hot side inlet of the first preheater (1), and the hot side outlet is connected to the hot side inlet of the superheater (5); The hot side outlet of the superheater (5) is connected to the hot side inlet of the condenser (6), and the hot side outlet of the condenser (6) is connected to the inlet of the first gas-liquid separator (7); The top gas outlet of the first gas-liquid separator (7) is connected to the incoming air, and the bottom condensate outlet is connected to the inlet of the condensate pump (8); The outlet of the condensate pump (8) is connected to the inlet of the condensate storage tank (9); The cold side inlet of the condenser (6) is connected to the outlet of the ammonia-water pump (12), and the cold side outlet is connected to the inlet of the second gas-liquid separator (13); The top gas outlet of the second gas-liquid separator (13) is connected to the cold side inlet of the superheater (5), and the bottom ammonia-water liquid is connected to the inlet of the ammonia-water pump (12); The cold side outlet of the superheater (5) is connected to the inlet of the turbine (10), and the outlet of the turbine (10) is connected to the hot side inlet of the condenser (11); The hot side outlet of the condenser (11) is connected to the inlet of the ammonia-water pump (12).

2. The working method of the biomass drying system integrating air drying cycle and organic Rankine cycle according to claim 1, characterized in that: The following working methods are included: In the top air drying cycle, the incoming air with a relatively low moisture content flows through the first preheater (1) and is preheated by the air at the outlet of the fan (4), and then enters the heater (2), where the material is dried using the heat energy of the heat source medium. After the material is dried, it is discharged from the dry material outlet of the heater (2); due to the heat and mass transfer effect in the heater (2), the moisture in the material evaporates and enters the air, and the relative moisture content of the air at the outlet of the cold side of the heater (2) increases and becomes humid air; The wet air then enters the cyclone separator (3) to separate impurities mixed in the wet air after the material is dried, and the separated impurities are discharged through the impurity outlet; Air enters the fan (4) and is compressed. The compressed wet air enters the first preheater (1) to preheat the incoming air. The air is then passed through the superheater (5) and the condenser (6) in sequence for cooling and dehumidification. The air releases sensible heat and latent heat to the ammonia-water on the cold side of the superheater (5) and the condenser (6), and the temperature is lowered. The air then enters the first gas-liquid separator (7). The gaseous air separated at the top is circulated back to the incoming air. The condensate separated at the bottom enters the condensate pump (8) for compression and then enters the condensate storage tank (9) for storage.

3. In the bottom organic Rankine cycle, the circulating working fluid ammonia-water is pressurized by the ammonia-water pump (12) and enters the condenser (6) to absorb heat. After absorbing heat, it enters the second gas-liquid separator (13). The outlet of the second gas-liquid separator (13) is divided into two paths: the high-temperature ammonia-water solution separated at the bottom is circulated back to the ammonia-water pump (12); the gaseous ammonia separated at the top enters the condenser (5) to absorb heat, and then enters the turbine (10) to expand and do work, driving the ammonia-water pump (12) to do work. The exhaust gas at the outlet of the turbine (10) enters the condenser (11) and is cooled by the water entering the cold side inlet. Then, it is pressurized by the ammonia-water pump (12) to start the next cycle.

Images