Zero-emission drying system for multi-stage waste heat recovery

Abstract

The utility model relates to the field of drying devices, and provides a multistage waste heat recovery zero-emission drying system which comprises a hot air type dryer, a gas-gas heat exchanger, a circulating fan, a spray tower, a circulating water pump, a preheater, a condenser, a heater, a condensate pump, a cooling tower, a cooler and an evaporator. An exhaust port of the hot air dryer is communicated with air inlets of the gas-gas heat exchanger and the spray tower in sequence; the exhaust port of the spray tower is sequentially communicated with the preheater, the condenser, the gas-gas heat exchanger, the heater and the air inlet of the dryer, and the temperature is increased step by step; and a water outlet of the spray tower is sequentially communicated with the preheater, the evaporator and the cooler for cooling step by step. A dust remover is arranged on a pipeline between the hot air dryer and the gas-gas heat exchanger; and solid-liquid separation equipment is arranged on a pipeline from the spray tower to the cooling tower. And dust discharged by the dust remover and solid materials discharged by the solid-liquid separation equipment are circulated back to the dryer. The system can realize full recovery and zero emission of waste heat.

Description

Technical Field

[0001] The utility model relates to the field of drying equipment, and in particular to a zero-emission drying system with multi-stage waste heat recovery. Background Art

[0002] Current drying equipment can be broadly classified into two types: direct type and partition type. The partition type generally uses steam to indirectly heat the material to be dried, while the direct type uses hot dry air with low humidity and high temperature to directly contact the material to remove moisture from the material.

[0003] Direct contact drying equipment is generally low in cost and simple to operate, but there are two main problems: one is that the heat dissipated by the exhaust is high, and the other is that the pollutants in the exhaust are difficult to treat. In response to this, closed or semi-closed systems have gradually emerged in the hope of recovering the exhaust heat of the dryer to heat the intake air, such as CN210922135U, CN211717126U, etc. However, the conventional drying gas waste heat recovery method causes a serious blockage problem. During the condensation process, the mixture of drying material particles and water will stick to the heat exchange equipment; and secondary pollution such as sewage or sludge will be generated.

[0004] In view of this, the present utility model is proposed. Utility Model Content

[0005] The purpose of the utility model is to provide a zero-emission drying system with multi-stage waste heat recovery, aiming to establish a closed hot air cycle, deeply recover waste heat, set the order of system equipment in consideration of anti-blocking, and comprehensively consider the treatment of pollutants to achieve zero emission of system pollutants.

[0006] The embodiment of the utility model is achieved as follows:

[0007] In a first aspect, the utility model provides a zero-emission drying system with multi-stage waste heat recovery, comprising:

[0008] Hot air dryer, air-to-air heat exchanger, circulating fan, spray tower, circulating water pump, preheater, condenser, heater, condensate pump, cooling tower, cooler and evaporator;

[0009] The exhaust port of the hot air dryer is connected to one end of the heat source channel of the air-to-air heat exchanger, and the other end of the heat source channel of the air-to-air heat exchanger is connected to the air inlet at the bottom of the spray tower;

[0010] The exhaust port at the top of the spray tower is connected to one end of the cold source channel of the preheater, the other end of the cold source channel of the preheater is connected to one end of the cold source channel of the condenser, the other end of the cold source channel of the condenser is connected to one end of the cold source channel of the air-to-air heat exchanger, the other end of the cold source channel of the air-to-air heat exchanger is connected to one end of the cold source channel of the heater, and the other end of the cold source channel of the heater is connected to the air inlet of the hot air dryer;

[0011] The drain outlet at the bottom of the spray tower is connected to one end of the heat source channel of the preheater, the other end of the heat source channel of the preheater is connected to one end of the heat source channel of the evaporator, the other end of the heat source channel of the evaporator is connected to one end of the heat source channel of the cooler, and the other end of the heat source channel of the cooler is connected to the upper spray water inlet of the spray tower;

[0012] The drain outlet at the bottom of the spray tower is connected to the water inlet of the cooling tower, the drain outlet at the bottom of the cooling tower is connected to one end of the cold source channel of the cooler, and the other end of the cold source channel of the cooler is connected to the water inlet of the cooling tower;

[0013] The outlet of the cold source channel of the evaporator is connected to the inlet of the heat source channel of the condenser, and a compressor is arranged on the pipeline connecting the outlet of the cold source channel of the evaporator and the inlet of the heat source channel of the condenser; the outlet of the heat source channel of the condenser is connected to the inlet of the cold source channel of the evaporator;

[0014] The circulating fan is arranged on the pipeline between the hot air dryer and the spray tower;

[0015] A dust collector is provided on the pipeline between the hot air dryer and the air-to-air heat exchanger, and the ash outlet at the bottom of the dust collector is connected to the inlet of the hot air dryer through an ash circulation pipe;

[0016] A solid-liquid separation device is arranged on the pipeline from the spray tower to the cooling tower, and the solid material outlet of the solid-liquid separation device is connected with the ash circulation pipe.

[0017] In an optional embodiment, the heat exchange medium flowing between the evaporator and the condenser is a refrigerant.

[0018] In an optional embodiment, a throttle valve is provided on a pipeline connecting the outlet of the heat source channel of the condenser and the inlet of the cold source channel of the evaporator.

[0019] In an optional embodiment, the circulation fan is arranged on the pipeline between the air-to-air heat exchanger and the spray tower.

[0020] In an optional embodiment, a condensate pump is provided on the pipeline between the spray tower and the cooling tower, and the condensate pump is used to pump the spray water at the bottom of the spray tower to the cooling tower.

[0021] In an optional embodiment, a circulating water pump is provided on the pipeline from the spray tower to the preheater, and the circulating water pump is used to pump the spray water at the bottom of the spray tower to the preheater.

[0022] In an optional embodiment, a cooling water pump is provided on the pipe connecting the drain outlet at the bottom of the cooling tower with the cold source channel of the cooler. The cooling water pump is used to pump the cooling water at the bottom of the cooling tower to the cooler and circulate it back into the cooling tower.

[0023] The zero-emission drying system with multi-stage waste heat recovery provided by the embodiment of the utility model can achieve the following beneficial effects due to the arrangement of multi-stage heat exchange / heater and dust collector, etc.:

[0024] 1. Use gas-to-gas heat exchanger to recover sensible heat, and use spraying for latent heat, which avoids the problem of blockage caused by exhaust gas condensation in the heat exchanger;

[0025] 2. Multi-stage cooling and multi-stage heating are adopted to optimize the thermal gradient;

[0026] 3. The water at the bottom of the tower with high solid content is separated into gas and liquid, and the liquid phase enters the cooling tower to evaporate, while the solid phase and dust removal ash are fed into the dryer, saving water and materials and achieving zero emission of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the utility model, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the utility model and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying creative work.

[0028] Figure 1 A zero-emission drying system with multi-stage waste heat recovery is provided in an embodiment of the utility model.

[0029] Icons: 101-hot air dryer; 102-dust collector; 103-gas-to-gas heat exchanger; 104-circulating fan; 105-spray tower; 106-solid-liquid separation equipment; 107-cooling tower; 111-preheater; 112-condenser; 113-heater; 121-evaporator; 122-cooler; 131-condensate pump; 132-cooling water pump; 133-circulating water pump; 141-compressor; 142-throttle valve; 151-material inlet; 152-material outlet; 153-ash circulation pipe. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical scheme and advantages of the embodiments of the utility model clearer, the technical scheme in the embodiments of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Generally, the components of the embodiments of the utility model described and shown in the drawings here can be arranged and designed in various different configurations.

[0031] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the present invention to be protected, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0033] In the description of the present utility model, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate the orientation or position relationship based on the orientation or position relationship shown in the accompanying drawings, or the orientation or position relationship in which the utility model product is usually placed when in use, which is only for the convenience of describing the utility model and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present utility model. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0034] In addition, the terms "horizontal", "vertical" and the like do not mean that the components are required to be absolutely horizontal or suspended, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0035] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0036] Please refer to Figure 1 As shown, the utility model provides a zero-emission drying system with multi-stage waste heat recovery, comprising:

[0037] Hot air dryer 101 , air-to-air heat exchanger 103 , circulating fan 104 , spray tower 105 , circulating water pump 133 , preheater 111 , condenser 112 , heater 113 , condensate pump 131 , cooling tower 107 , cooler 122 and evaporator 121 .

[0038] The exhaust port of the hot air dryer 101 is connected to one end of the heat source channel of the air-to-air heat exchanger 103, and the other end of the heat source channel of the air-to-air heat exchanger 103 is connected to the air inlet at the bottom of the spray tower 105;

[0039] The exhaust port at the top of the spray tower 105 is connected to one end of the cold source channel of the preheater 111, the other end of the cold source channel of the preheater 111 is connected to one end of the cold source channel of the condenser 112, the other end of the cold source channel of the condenser 112 is connected to one end of the cold source channel of the air-to-air heat exchanger 103, the other end of the cold source channel of the air-to-air heat exchanger 103 is connected to one end of the cold source channel of the heater 113, and the other end of the cold source channel of the heater 113 is connected to the air inlet of the hot air dryer 101.

[0040] The hot air dryer 101 has a material inlet 151 and a material outlet 152. The material is fed into the hot air dryer 101 through the material inlet 151 and is discharged from the material outlet 152 after being dried by the hot air. The drying exhaust gas still has a certain degree of superheat after being discharged from the hot air dryer 101. The high-quality sensible heat is used to release heat once through the gas-to-gas heat exchanger 103 (no condensation in this process), and then enters the spray tower 105 for spray cooling. The cooled gas is heated by the preheater 111, the condenser 112, the gas-to-gas heat exchanger 103 and the heater 113 in four stages in sequence and then returns to the hot air dryer 101, and the cycle repeats.

[0041] Specifically, the heat source channel of the heater 113 is connected to an external heat source, and the external heat source provides heat again to the gas heated by the gas-to-gas heat exchanger 103 to increase its temperature.

[0042] The drain outlet at the bottom of the spray tower 105 is connected to one end of the heat source channel of the preheater 111, the other end of the heat source channel of the preheater 111 is connected to one end of the heat source channel of the evaporator 121, the other end of the heat source channel of the evaporator 121 is connected to one end of the heat source channel of the cooler 122, and the other end of the heat source channel of the cooler 122 is connected to the upper spray water inlet of the spray tower 105.

[0043] The exhaust temperature of the spray tower 105 is slightly lower than the drainage temperature at the bottom of the spray tower 105. The spray water path preheater 111 at the bottom of the spray tower 105 is cooled by the exhaust gas of the spray tower 105, and then cooled by the evaporator 121 and the cooler 122 in turn. After three levels of cooling, the spray water returns to the top of the tower and is used again to spray and cool the gas entering the spray tower 105.

[0044] Optionally, a cooling water pump 132 is provided on a pipe connecting the drain outlet at the bottom of the cooling tower 107 with the cold source channel of the cooler 122 , and the cooling water pump 132 is used to pump the cooling water at the bottom of the cooling tower 107 to the cooler 122 and circulate it back into the cooling tower 107 .

[0045] The drain outlet at the bottom of the spray tower 105 is connected to the water inlet of the cooling tower 107, the drain outlet at the bottom of the cooling tower 107 is connected to one end of the cold source channel of the cooler 122, and the other end of the cold source channel of the cooler 122 is connected to the water inlet of the cooling tower 107.

[0046] Optionally, a condensate pump 131 is provided on the pipeline between the spray tower 105 and the cooling tower 107 , and the condensate pump 131 is used to pump the spray water at the bottom of the spray tower 105 to the cooling tower 107 .

[0047] Optionally, a circulating water pump 133 is provided on the pipeline from the spray tower 105 to the preheater 111 , and the circulating water pump 133 is used to pump the spray water at the bottom of the spray tower 105 to the preheater 111 .

[0048] During the spraying process, the spray circulating water continuously condenses the moisture in the drying exhaust gas, so its liquid holding capacity will gradually increase. At this time, the excess moisture is pumped out from the bottom of the tower and added to the cooling tower 107. This process solves the water balance problem.

[0049] The outlet of the cold source channel of the evaporator 121 is connected to the inlet of the hot source channel of the condenser 112, and a compressor 141 is arranged on the pipeline connecting the outlet of the cold source channel of the evaporator 121 and the inlet of the hot source channel of the condenser 112; the outlet of the hot source channel of the condenser 112 is connected to the inlet of the cold source channel of the evaporator 121.

[0050] The heat exchange medium flowing between the evaporator 121 and the condenser 112 increases in temperature as a cold source when passing through the evaporator 121. In the process of flowing to the condenser 112, the heat continues to increase under the action of the compressor 141. After reaching the condenser 112, the temperature of the heat source decreases. The cooled medium returns to the evaporator 121 again, and the cycle continues.

[0051] Optionally, the heat exchange medium flowing between the evaporator 121 and the condenser 112 is a refrigerant. The refrigerant evaporates in the evaporator 121, then is pressurized by the compressor 141, and condenses and releases heat in the condenser 112. The condensation temperature of this process is higher than the evaporation temperature, which plays the role of a heat pump.

[0052] Optionally, a throttle valve 142 is provided on a pipeline connecting the outlet of the heat source channel of the condenser 112 and the inlet of the cold source channel of the evaporator 121. The refrigerant after releasing heat in the condenser 112 is depressurized through the throttle valve 142 and returns to the evaporator 121.

[0053] The circulating fan 104 is disposed on the pipeline between the hot air drying machine 101 and the spray tower 105 .

[0054] The circulating fan 104 provides circulating power for the drying exhaust gas. Optionally, the circulating fan 104 can be specifically arranged on the pipeline between the air-to-air heat exchanger 103 and the spray tower 105 .

[0055] A dust collector 102 is provided on the pipeline between the hot air dryer 101 and the air-to-air heat exchanger 103 , and the ash outlet at the bottom of the dust collector 102 is connected to the inlet of the hot air dryer 101 through an ash circulation pipe 153 .

[0056] The drying exhaust gas carries dust, and most of the dust in the exhaust gas can be removed after the dust collector 102 removes the dust, and the separated dust returns to the hot air dryer 101 without being discharged; and because the dust carried by the exhaust gas is also part of the material, returning the dust to the hot air dryer 101 saves materials and avoids waste.

[0057] A solid-liquid separation device 106 is provided on the pipeline from the spray tower 105 to the cooling tower 107 , and a solid material outlet of the solid-liquid separation device 106 is connected to the ash circulation pipe 153 .

[0058] The setting of the solid-liquid separation equipment 106 can separate the dust that has not been completely removed in the exhaust gas again. The solid material separated by the solid-liquid separation equipment 106 is transported to the hot air dryer 101 and mixed with the ash from the dust collector 102, which can effectively solve the problem that the dust in the drying exhaust gas cannot be completely removed; and returning the solid material to the hot air dryer 101 also plays a role in avoiding material waste.

[0059] Optionally, the solid material outlet of the solid-liquid separation device 106 can be connected to a pneumatic device, and the solid material is transported through a pipeline to the hot air dryer 101 together with the ash by pneumatic transport. Since the pneumatic device is a common technology at present, it will not be described in detail here.

[0060] In summary, the zero-emission drying system provided by the embodiment of the utility model has the following characteristics:

[0061] 1. The sensible heat is recovered by the gas-to-gas heat exchanger 103, and the latent heat is recovered by spraying, thereby avoiding the problem of blockage caused by condensation of exhaust gas in the heat exchanger.

[0062] 2. Multi-stage cooling and multi-stage heating are adopted to optimize the utilization of heat gradient.

[0063] 3. The water at the bottom of the tower with high solid content undergoes vapor-liquid separation, and the liquid phase enters the cooling tower 107 to evaporate, while the solid phase and dust removal ash are fed into the dryer, saving water and materials and achieving zero emission of the system.

[0064] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may be subject to various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A zero-emission drying system with multi-stage waste heat recovery, characterized in that: include: Hot air dryer, air-to-air heat exchanger, circulating fan, spray tower, circulating water pump, preheater, condenser, heater, condensate pump, cooling tower, cooler and evaporator; The exhaust port of the hot air dryer is connected to one end of the heat source channel of the air-to-air heat exchanger, and the other end of the heat source channel of the air-to-air heat exchanger is connected to the air inlet at the bottom of the spray tower; The exhaust port at the top of the spray tower is connected to one end of the cold source channel of the preheater, the other end of the cold source channel of the preheater is connected to one end of the cold source channel of the condenser, the other end of the cold source channel of the condenser is connected to one end of the cold source channel of the air-to-air heat exchanger, the other end of the cold source channel of the air-to-air heat exchanger is connected to one end of the cold source channel of the heater, and the other end of the cold source channel of the heater is connected to the air inlet of the hot air dryer; The drain outlet at the bottom of the spray tower is connected to one end of the heat source channel of the preheater, the other end of the heat source channel of the preheater is connected to one end of the heat source channel of the evaporator, the other end of the heat source channel of the evaporator is connected to one end of the heat source channel of the cooler, and the other end of the heat source channel of the cooler is connected to the upper spray water inlet of the spray tower; The drain outlet at the bottom of the spray tower is connected to the water inlet of the cooling tower, the drain outlet at the bottom of the cooling tower is connected to one end of the cold source channel of the cooler, and the other end of the cold source channel of the cooler is connected to the water inlet of the cooling tower; The outlet of the cold source channel of the evaporator is connected to the inlet of the heat source channel of the condenser, and a compressor is arranged on the pipeline connecting the outlet of the cold source channel of the evaporator and the inlet of the heat source channel of the condenser; the outlet of the heat source channel of the condenser is connected to the inlet of the cold source channel of the evaporator; The circulating fan is arranged on the pipeline between the hot air drying machine and the spray tower; A dust collector is provided on the pipeline between the hot air dryer and the air-to-air heat exchanger, and the ash outlet at the bottom of the dust collector is connected to the inlet of the hot air dryer through an ash circulation pipe; A solid-liquid separation device is provided on the pipeline from the spray tower to the cooling tower, and the solid material outlet of the solid-liquid separation device is connected to the ash circulation pipe.

2. The zero emission drying system according to claim 1, characterized in that: The heat exchange medium flowing between the evaporator and the condenser is a refrigerant.

3. The zero emission drying system according to claim 2, characterized in that: A throttle valve is arranged on a pipeline connecting the outlet of the heat source channel of the condenser and the inlet of the cold source channel of the evaporator.

4. The zero emission drying system according to claim 1, characterized in that: The circulating fan is arranged on the pipeline between the air-to-air heat exchanger and the spray tower.

5. The zero emission drying system according to claim 1, characterized in that: A condensate pump is provided on the pipeline between the spray tower and the cooling tower, and the condensate pump is used to pump the spray water at the bottom of the spray tower to the cooling tower.

6. The zero emission drying system according to claim 1, characterized in that: A circulating water pump is provided on the pipeline from the spray tower to the preheater, and the circulating water pump is used to pump the spray water at the bottom of the spray tower to the preheater.

7. The zero emission drying system according to claim 1, characterized in that: A cooling water pump is provided on a pipe connecting the drain outlet at the bottom of the cooling tower with the cold source channel of the cooler. The cooling water pump is used to pump the cooling water at the bottom of the cooling tower to the cooler and circulate it back into the cooling tower.

Images