CN-121976414-A - System and method for fully utilizing exhaust waste heat in household paper drying process

CN121976414ACN 121976414 ACN121976414 ACN 121976414ACN-121976414-A

Abstract

The invention relates to the technical field of papermaking, and discloses a full utilization system and method of exhaust waste heat in a household paper drying process. According to the invention, two-stage waste heat recovery is realized through cooperation of the heat pipe exchanger and the heat pump unit, waste heat of exhaust air in the drying process of household paper is utilized in a gradient manner, the pain point that waste heat recovery is incomplete and latent heat is wasted in the prior art is solved, high-temperature high-humidity exhaust air of 110-140 ℃ discharged by the paper machine gas hood enters the heat pump evaporator after being subjected to primary cooling by the heat pipe exchanger, sensible heat and latent heat are fully recovered and dehumidified, the temperature of the exhaust air is reduced to 40-50 ℃, two flows are distributed to participate in secondary heat exchange by the flow regulating valve, the temperature is raised to 70-80 ℃ to be converged, and the exhaust air is heated to 160-200 ℃ by the air heater and returned to the gas hood for circulation, so that steam heating is greatly replaced, steam consumption is reduced, and production cost is saved.

Inventors

KONG LINGBO
ZHANG JIFENG
YANG XING

Assignees

陕西科技大学

Dates

Publication Date: 20260505
Application Date: 20260324

Claims (9)

1. The utility model provides a full utilization system of paper drying process exhaust waste heat, its characterized in that includes paper machine gas hood, heat pipe heat exchanger, heat pump unit and the air heater that connects gradually: The heat pump unit comprises an evaporator, a compressor, a condenser, a liquid storage tank and a throttling component which are sequentially connected, wherein an outlet of the liquid storage tank is connected with a refrigerant inlet of the evaporator through the throttling component; The air outlet of the evaporator is connected with the cold end inlet of the heat pipe heat exchanger through a pipeline by a first flow regulating valve, and the cold end outlet of the heat pipe heat exchanger is connected with the air inlet of the air heater through a pipeline; the low-temperature exhaust outlet of the evaporator is connected with the low-temperature exhaust inlet of the condenser through a second flow regulating valve arranged on the pipeline, and the gas outlet of the condenser is connected with the gas inlet of the air heater through the pipeline; The air outlet of the air heater is connected with the inlet of the paper machine gas hood through a pipeline.
2. The full utilization system of waste heat of exhaust air in a drying process of household paper according to claim 1, wherein a part of low-temperature exhaust air discharged from the evaporator enters the heat pipe exchanger through the first flow regulating valve, and the other part enters the condenser through the second flow regulating valve.
3. The full utilization system of exhaust waste heat in a paper drying process for daily use according to claim 1, wherein the steam inlet of the air heater is provided with a steam flow regulating valve for regulating the amount of steam required for heating air.
4. The full utilization system of exhaust waste heat in a household paper drying process according to claim 1, wherein the heat pipe exchanger consists of a plurality of heat pipes which are arranged in a staggered manner, the shell materials of the heat pipes are aluminum, copper or stainless steel, and fins are arranged on the outer walls of the heat pipes.
5. The full utilization system of exhaust waste heat in a drying process of household paper according to claim 1, wherein the surface of the evaporator contacted with exhaust air is sprayed with an epoxy phenolic coating.
6. The full utilization system of exhaust waste heat in a paper drying process according to claim 1, wherein the compressor is a rotor compressor or a scroll compressor, and is used for compressing low-temperature low-pressure refrigerant gas discharged from the evaporator into high-temperature high-pressure vapor and delivering the high-temperature high-pressure vapor to the condenser.
7. The full utilization system of exhaust waste heat in a household paper drying process according to claim 1, wherein the heat exchange tube, the tube plate and the end socket lining of the condenser are made of stainless steel.
8. The full utilization system of exhaust waste heat in a household paper drying process according to claim 1, wherein the liquid storage tank is a steel pressure container, and is provided with a liquid inlet, a stop valve, a safety valve and a liquid outlet for storing, adjusting and purifying liquid refrigerant.
9. The method for fully utilizing exhaust waste heat in the drying process of household paper based on the system of any one of claims 1 to 8 is characterized by comprising the following steps: High-temperature sensible heat recovery, namely, feeding high-temperature high-humidity exhaust air with the temperature of 110-140 ℃ discharged by a paper machine gas hood into the hot end of a heat pipe heat exchanger, indirectly exchanging heat with low-temperature exhaust air with the temperature of 40-50 ℃ from an evaporator, reducing the exhaust air temperature to 80-100 ℃, and preheating the low-temperature exhaust air to 70-80 ℃; wen Qianre, feeding the treated medium-temperature high-humidity exhaust air with the temperature of 80-100 ℃ into an evaporator, cooling to below the dew point temperature, condensing water vapor in the wet air, releasing latent heat, and reducing the exhaust air temperature to 40-50 ℃ to become low-temperature low-humidity exhaust air; the exhaust and split flow is that the low-temperature low-humidity exhaust air with the temperature of 40 ℃ to 50 ℃ is divided into two paths, wherein the first path enters the cold end of the heat pipe heat exchanger through a first flow regulating valve to serve as a cold source, and the second path enters the condenser through a second flow regulating valve to serve as a cooling medium; The heat pump circulation, namely, the refrigerant absorbing heat in the evaporator is changed into low-pressure steam, compressed into high-temperature high-pressure steam by a compressor, enters a condenser, performs phase change heat exchange with a second path of low-temperature exhaust air, heats the low-temperature exhaust air to 70-80 ℃, condenses and liquefies the refrigerant, and returns the condensed refrigerant to the evaporator through a liquid storage tank and a throttling component; Preheating and air supply merging, namely merging the first path of air supply preheated by the cold end of the heat pipe heat exchanger with the second path of air supply heated by the condenser, and sending the first path of air supply and the second path of air supply into the air heater together; And finally heating, namely, carrying out secondary heating on the combined preheated air supply in an air heater to enable the temperature to rise to 160-200 ℃, and returning the heated air supply to the air hood of the paper machine as the air hood air supply for drying.

Description

System and method for fully utilizing exhaust waste heat in household paper drying process Technical Field The invention relates to the technical field of papermaking, in particular to a system and a method for fully utilizing exhaust waste heat in a drying process of household paper. Background The drying is the highest link of the production process of the household paper, and accounts for more than 70% of the total energy consumption of the production, in the actual recovery process, when the exhaust temperature is lower than the dew point temperature, a large amount of water vapor can condense and form condensation, and finally adhere to the surface of heat exchange equipment, so that the equipment corrosion problem is caused, in view of corrosion prevention and anti-blocking, the existing waste heat recovery scheme generally only utilizes a plate heat exchanger to recover sensible heat in the exhaust of a gas hood, the exhaust temperature of an outlet of the heat exchanger is generally maintained above the dew point, so that the latent heat in a large amount of waste heat is not effectively utilized, and in fact, in the exhaust of the gas hood in the drying process of the household paper, the latent heat contained in the water vapor generally accounts for more than 60% -70% of the total amount of the waste heat, and the sensible heat accounts for only 30% -40%, so that most of available heat is directly discharged. At present, the plate heat exchanger is often in operation because of lower heat transfer coefficient, and the flow dead zone exists in the flow field, so that partial heat transfer area can not be fully flushed by fluid, the effective heat transfer area is reduced, the heat transfer area can be increased only to meet the process heat exchange requirement, the heat transfer area is increased, the equipment structure is complicated, the occupied area is increased, the maintenance frequency is increased, the problem that the operation and maintenance cost is high is finally caused, the factors restrict the improvement of the waste heat recovery effect, and the urgent requirement of paper making enterprises on deep utilization of exhaust waste heat is also difficult to be met. Disclosure of Invention In order to solve the technical problems, the invention provides a full utilization system of exhaust waste heat in a household paper drying process. The invention provides a full utilization system of exhaust waste heat in a household paper drying process, which comprises a paper machine gas hood, a heat pipe heat exchanger, a heat pump unit and an air heater which are connected in sequence: The heat pump unit comprises an evaporator, a compressor, a condenser, a liquid storage tank and a throttling component which are sequentially connected, wherein an outlet of the liquid storage tank is connected with a refrigerant inlet of the evaporator through the throttling component; The air outlet of the evaporator is connected with the cold end inlet of the heat pipe heat exchanger through a pipeline by a first flow regulating valve, and the cold end outlet of the heat pipe heat exchanger is connected with the air inlet of the air heater through a pipeline; the low-temperature exhaust outlet of the evaporator is connected with the low-temperature exhaust inlet of the condenser through a second flow regulating valve arranged on the pipeline, and the gas outlet of the condenser is connected with the gas inlet of the air heater through the pipeline; The air outlet of the air heater is connected with the inlet of the paper machine gas hood through a pipeline. Preferably, a part of low-temperature exhaust air discharged from the evaporator enters the heat pipe exchanger through the first flow regulating valve, and the other part enters the condenser through the second flow regulating valve. Preferably, the steam inlet of the air heater is provided with a steam flow regulating valve for regulating the steam amount required for heating the air Preferably, the heat pipe exchanger is composed of a plurality of heat pipes which are arranged in a staggered mode, the shell materials of the plurality of heat pipes are aluminum, copper or stainless steel, and fins are arranged on the outer walls of the plurality of heat pipes. Preferably, the surface of the evaporator, which is in contact with the exhaust air, is sprayed with an epoxy phenolic coating. Preferably, the compressor is a rotor compressor or a scroll compressor, and is configured to compress low-temperature low-pressure refrigerant gas discharged from the evaporator into high-temperature high-pressure vapor and deliver the high-temperature high-pressure vapor to the condenser. Preferably, the heat exchange tube, the tube plate and the end socket lining of the condenser are all made of stainless steel. Preferably, the liquid storage tank is a steel pressure container and is provided with a liquid inlet, a stop valve, a safety valve and a liquid outlet for s