CN220601483U - Device for preparing steam by utilizing waste heat - Google Patents

Abstract

The utility model discloses a device for preparing steam by utilizing waste heat, which comprises a closed flash tank, wherein a gas phase zone at the upper part of the flash tank is connected with a first steam discharge pipe, the flash tank is connected with a purified water inlet pipe, and a waste heat exchanger for heat exchange between a heat source and purified water is arranged at the bottom in the flash tank; the first steam discharge pipe is connected with a steam heating device which exchanges heat with steam generated by the flash tank and can strip steam to a temperature, and a steam conveying device which is used for pumping negative pressure to the flash tank and preventing steam from flowing back is arranged on the first steam discharge pipe. The utility model firstly utilizes the waste heat of hot water to flash prepare low-temperature saturated steam, then utilizes a temperature raising method to prepare the low-temperature saturated steam into high-temperature steam, reduces the requirement on the temperature of the hot water, and the prepared high-temperature steam has less impurities and high quality.

Description

Device for preparing steam by utilizing waste heat

Technical Field

The utility model relates to the technical field of waste heat recovery, in particular to a device for preparing steam by using waste heat.

Background

Current industrial enterprises require large volumes of steam for industrial production, while also producing large amounts of low quality industrial waste heat emissions. In recent years, the electricity, natural gas and coal equivalent grids for producing high-temperature steam are greatly increased, so that the steam production cost is high, and the profit of enterprises is influenced. Other steam production methods also comprise electromagnetic induction steam generators, are suitable for occasions requiring small-scale steam production, and are not suitable for the field of industrial steam with larger steam consumption scale.

The cost of using low-quality waste heat to prepare steam is lower than that of primary energy, so that waste heat recycling can be realized, and environmental pollution is reduced. The existing equipment and process production of a large amount of enterprises such as air compressors, refrigerators, solar photo-thermal engines, internal combustion engines and the like also generate hot water below 100 ℃, and the heat in the equipment and process production can be used for preparing low-cost steam, so that the energy-saving effect is achieved. The existing technology for producing high-temperature steam by utilizing hot water waste heat is not more, the investment is high, the energy consumption for producing steam is high, various technologies have certain limitations, such as the use of a high-temperature steam heat pump for producing steam, the temperature of waste heat water is required to be above 60 ℃, the temperature of produced steam is 100-120 ℃, the COP value is about 3, and the part with the temperature higher than the temperature is required to be subjected to temperature and pressure raising by using a steam compressor, so that the energy consumption is high and the investment is high. If the flash evaporation method is used, the waste heat temperature is generally above 70 ℃, low-temperature saturated steam at 70 ℃ is firstly prepared, then the required high-temperature steam is prepared through multistage temperature and pressure increasing by a steam compressor, the method is slightly lower than the investment of the heat pump method, but the gas yield is lower than that of the heat pump method, and the methods for preparing the high-temperature steam by using the low-temperature steam are generally the pressure increasing method for compressing the steam. In addition, the two methods are difficult to generate steam with higher temperature, such as high temperature steam with the temperature of more than 200 ℃ obtained by using a screw steam compressor, and the steam inlet temperature is more than 170 ℃.

The existing method for preparing steam by utilizing the hot water waste heat flash evaporation is that hot water is directly connected into a flash tank, negative pressure is pumped to the flash tank, steam generated by hot water evaporation is pumped out of the flash tank and then is used as a heat source to be supplied to a user side, condensed water is generated, the quality of the steam is related to the quality of the hot water, if the impurities in the hot water are more, the generated steam also contains the impurities, the impurities can only be used as the heat source for heat exchange, the generated condensed water is complex in composition and difficult to treat, and the flash tank is generally provided with a hot water inlet pipe and a hot water outlet pipe, the hot water is led in and led out simultaneously, so that the negative pressure degree in the flash tank cannot be too high for the smooth outflow of the hot water, namely the pressure in the flash tank cannot be too low, and the evaporation rate of the hot water is influenced.

Disclosure of Invention

Aiming at the problems that the existing device for preparing steam by utilizing waste heat adopts a pressure increasing method to increase the temperature of the steam, has high requirements on the temperature of the waste heat and the prepared steam has a plurality of impurities and poor quality, the utility model provides the device for preparing the steam by utilizing the waste heat, which prepares the low-temperature saturated steam into the high-temperature steam by utilizing the temperature increasing method, and further provides the device for preparing the high-temperature steam by utilizing the low-temperature waste heat, wherein the obtained steam has less impurities.

In order to solve the technical problems, the utility model comprises a sealed flash tank, wherein a first steam discharge pipe is connected to an upper gas phase zone of the flash tank, and the structure is characterized in that: the flash tank is connected with a purified water inlet pipe, and a waste heat exchanger for heat exchange between a heat source and the purified water is arranged at the bottom in the flash tank; the first steam discharge pipe is connected with a steam heating device which performs heat exchange with steam generated by the flash tank and can strip steam to a temperature, and a steam conveying device which is used for pumping negative pressure to the flash tank and preventing steam from flowing back is arranged on the first steam discharge pipe.

After the structure is adopted, the purified water enters the flash tank through the purified water inlet pipe, the heat source for waste heat recovery is introduced into the waste heat exchanger, the purified water and the heat source exchange heat in the inner bottom area of the flash tank through the waste heat exchanger, the purified water is heated, and meanwhile, the steam conveying equipment pumps negative pressure to the flash tank. The low-temperature saturated steam generated in the flash tank is pumped out by the steam conveying equipment and then is sent into the steam heating device, the high-temperature steam is obtained after the temperature is raised by the steam heating device, and the steam conveying equipment has the functions that: and secondly, the steam is discharged into a steam heating device after being pumped out, and the steam is prevented from being heated and boosted in the steam heating device to cause backflow. The high-temperature steam is prepared from the low-temperature saturated steam by adopting a temperature raising method, the high-temperature steam is obtained by utilizing a steam heating device to raise the temperature of the steam, the high-temperature steam with the temperature of more than 200 ℃ can be prepared, the high-temperature steam heat pump or the multistage steam compressor is not required to be used for raising the pressure and the temperature of the steam, and the equipment investment is reduced. In addition, the device uses purified water as the water source of producing steam, and the steam impurity that produces is few, and the quality is good, does not have the corruption to equipment, does not scale deposit, can all volatilize in the flash tank inside, need not to discharge.

Further, the heat source inlet pipe of the waste heat exchanger is positioned outside the flash tank, the purified water inlet pipe is provided with a pre-heat exchanger which exchanges heat with the heat source inlet pipe, and the purified water inlet pipe is also provided with a water pump.

Further, the purified water inlet pipe is connected with an upper gas phase zone of the flash tank, the upper gas phase zone of the flash tank is provided with a spray pipe connected with the purified water inlet pipe, and the spray pipe is provided with a spray head.

Further, the steam conveying equipment is a vacuum air heater or a steam compressor, and the pressure of a steam outlet of the steam conveying equipment is more than 1.6 MPa.

Further, the steam heating device comprises a steam heater for heating and raising the temperature of steam generated by the flash tank or a steam mixing tank for mixing and raising the temperature of the steam generated by the flash tank, the steam heater is heated by electromagnetic heating, electric heating or a heat exchanger, and the steam mixing tank is connected with a steam inlet pipe.

Further, the steam outlet of the steam heating device is connected with a pressure stabilizing tank through a second steam discharge pipe, a steam pressure control valve for controlling steam pressure is arranged on the second steam discharge pipe, and the pressure stabilizing tank is connected with a third steam discharge pipe.

Further, the waste heat exchanger is a plate heat exchanger or a tube type heat exchanger.

The utility model utilizes the device for preparing steam by waste heat, the water for generating steam adopts purified water, the purified water firstly exchanges heat with waste heat water supply and then enters the flash tank, and the purified water is sprayed to the waste heat exchanger at the bottom of the tank from the upper part, so that the aim of preheating the purified water is to enable the temperature of the purified water entering the flash tank to be close to the temperature of the waste heat water supply, the temperature of the purified water entering the flash tank is improved, and the steam generated by the evaporation of the purified water at the bottom of the flash tank is prevented from being condensed due to low-temperature purified water in the rising process; the steam conveying equipment is used for pumping negative pressure to the flash tank, and a water outlet for continuously discharging purified water is not formed in the bottom of the flash tank, so that lower air pressure can be maintained in the flash tank, and the rate of purifying aquatic steam is improved; the steam conveying equipment extracts the steam in the flash tank and sends the steam into the steam heating device, so that the steam is prevented from being heated and boosted in the steam heating device to cause backflow; the low-temperature steam is output to the steam end through the pressure stabilizing tank after being subjected to temperature and pressure raising by the steam heating device, the steam heating device can adopt electromagnetic heating, electric heating, high-temperature steam with the temperature higher than the temperature of the produced steam, high-temperature flue gas and high-temperature liquid as heating sources, and can also adopt the low-temperature steam mixed with high-grade steam with the temperature higher than the temperature of the produced steam for temperature raising, so that the source of the heat sources is wide. The device uses waste heat to supply water to heat purified water to prepare steam, the obtained steam has few impurities and high quality, the air pressure in the flash tank is lower, the purified water can be boiled and evaporated when the temperature of the waste heat supply water is above 30 ℃, and the requirement on the temperature of the waste heat supply water is greatly reduced; the steam generated by the flash tank is heated and raised in the steam heating device to obtain high-temperature steam, a steam heat pump or a multi-stage steam compressor is not required to be used for raising the temperature and the pressure, the investment and the energy consumption for steaming and stripping the temperature are reduced, the cost for producing the steam is further reduced, and the high-temperature saturated steam with the temperature of more than 200 ℃ can be obtained after the steam is heated by the steam heating device.

Drawings

FIG. 1 is a schematic diagram of the structure of the present utility model;

FIG. 2 is a schematic diagram of a steam mixing tank as a steam heating device;

in the figure: 1-a flash tank; 11-spraying pipes; 2-a waste heat exchanger; 21-heat source inlet pipe; 22-heat source outlet pipe; 3-purifying water inlet pipe; 31-a pre-heat exchanger; 32-a water pump; 4-a first steam discharge pipe; 41-a steam delivery device; 5-a steam heater; 6-a second steam discharge pipe; 61-steam pressure control valve; 7-a surge tank; 8-a third steam discharge pipe; 9-a steam mixing tank; 91-steam inlet pipe.

Detailed Description

Referring to fig. 1, an apparatus for preparing steam using waste heat includes a sealed flash tank 1, a steam delivery device 41, and a steam heating device. The bottom in the flash tank 1 is provided with a waste heat exchanger 2, the waste heat exchanger 2 can be in the form of a plate heat exchanger or a tube array heat exchanger, and the like, a heat source inlet tube 21 and a heat source outlet tube 22 of the waste heat exchanger 2 are arranged outside the flash tank 1, the heat source inlet tube 21 and the heat source outlet tube 22 are respectively used for the heat source to enter and discharge the waste heat exchanger 2, the heat source is preferably waste heat water supply, and other liquid materials can be used as heat sources of course. The upper part of the flash tank 1 is a space for generating steam, namely a gas phase zone, the gas phase zone at the upper part of the flash tank 1 is connected with a purified water inlet pipe 3, the purified water inlet pipe 3 is provided with a pre-heat exchanger 31 and a water pump 32 which are sequentially arranged along the water flow direction, the pre-heat exchanger 31 is used for supplying water and exchanging heat for waste heat in the purified water and heat source inlet pipe 21, and the pre-heat exchanger 31 can be in the form of a plate heat exchanger or a tube type heat exchanger and the like. The purified water inlet pipe 3 is connected with a spray pipe 11 above the inside of the flash tank 1, and a spray head for spraying water downwards is arranged on the spray pipe 11.

Referring to fig. 1, a first steam discharge pipe 4 is connected to an upper gas phase region of a flash tank 1, the first steam discharge pipe 4 is connected to a steam heating device, the steam heating device is a steam heater 5, a steam conveying device 41 is arranged on the first steam discharge pipe 4, the steam conveying device 41 pumps negative pressure to the flash tank 1 and simultaneously pumps out steam, the pumped steam is sent into the steam heater 5 to prevent the steam from flowing back, the steam conveying device 41 can adopt a vacuum hot air blower or a steam compressor, and the pressure of a steam outlet of the steam conveying device 41 is above 1.6 MPa. The steam heater 5 can heat the steam generated by the flash tank 1 in electromagnetic heating, electric heating and other modes, and can also heat the steam generated by the flash tank 1 by adopting a heat exchanger, the heat source adopts high-temperature fluid with the temperature higher than the temperature of the steam, the high-temperature fluid is derived from high-temperature steam, high-temperature flue gas, high-temperature liquid and the like, such as the high-temperature flue gas generated by a fuel gas boiler and a coal-fired boiler, the high-temperature steam residual steam generated by the high-temperature steam boiler, the high-temperature liquid generated in the production process and the like, and the steam is the steam subjected to temperature and pressure increasing by the steam heater 5. The steam heater 5 is connected with the surge tank 7 through a second steam discharge pipe 6, a steam pressure control valve 61 is arranged on the second steam discharge pipe 6, the steam pressure control valve 61 is used for controlling the steam pressure discharged by the steam heater 5, and the surge tank 7 is provided with a third steam discharge pipe 8 used for making high-temperature steam discharge. The bottoms of the flash tank 1, the steam heater 5 and the pressure stabilizing tank 7 are provided with an emptying pipe and a control valve, and the control valve is in a closed state during operation.

Fig. 2 is another embodiment, substantially identical to fig. 1, except that: the steam heating device replaces the steam heater 5 in fig. 1 with the steam mixing tank 9, the steam mixing tank 9 is connected with a steam inlet pipe 91, high-grade steam (without impurities) is introduced into the steam inlet pipe 91, the temperature and pressure of the steam introduced into the steam inlet pipe 91 are higher than the temperature and pressure of the steam discharged from the steam mixing tank 9, and the low-temperature steam generated by the flash tank 1 is mixed with the steam introduced into the steam inlet pipe 91 to improve the temperature and pressure of the low-temperature steam.

It should be noted that: the actual equipment and pipelines are also provided with conventional accessories such as valves, meters, access ports and the like, such as a thermometer for detecting water and steam temperature, a pressure gauge for detecting steam pressure, a liquid level gauge for detecting water level, a valve for controlling flow rate, a safety valve on a tank body and the like, and the accessories are conventional in the field and are not shown in the drawing.

1-2, the equipment flow of the method refers to a method for preparing steam by using waste heat, the method comprises a flash tank 1, a waste heat exchanger 2 is arranged at the bottom in the flash tank 1, a heat source inlet pipe 21 and a heat source outlet pipe 22 of the waste heat exchanger 2 are positioned outside the flash tank 1, a purified water inlet pipe 3 and a first steam outlet pipe 4 are connected to an upper gas phase region of the flash tank 1, a pre-heat exchanger 31 and a water pump 32 which exchange heat with the heat source inlet pipe 21 are arranged on the purified water inlet pipe 3, the purified water inlet pipe 3 is connected with a spray pipe 11 in the flash tank 1, a spray head is arranged on the spray pipe 11, the first steam outlet pipe 4 is connected to a steam heating device, a steam conveying device 41 is arranged on the first steam outlet pipe 4, the steam conveying device 41 is used for pumping negative pressure to the flash tank 1, the pumped steam is fed into the steam heating device, and the steam is prevented from flowing back, the steam outlet pressure of the steam conveying device 41 is more than 1.6MPa, the second steam outlet pipe 6 is communicated with a pressure stabilizing tank 7 through a second steam outlet pipe 6, a steam pressure control valve 61 is arranged on the second steam outlet pipe 6, a steam pressure control valve 61 is used for controlling the pressure of the steam heater 5, and the specific method is as follows: introducing purified water at 15-20 ℃ into a purified water inlet pipe 3, introducing waste heat water at 30-120 ℃ into a heat source inlet pipe 21, preheating the purified water by the waste heat water supply when flowing through a pre-heat exchanger 31, and pumping the purified water into a flash tank 1 by a water pump 32, wherein the purified water adopts purified water or boiler soft water and the like; after entering the flash tank 1, the purified water is sprayed downwards from the spray head of the spray pipe 11 to the waste heat exchanger 2. The steam conveying device 41 pumps negative pressure to the flash tank 1, so that the internal air pressure of the flash tank 1 is kept at 0.003-0.1MPa, purified water is heated and evaporated by waste heat water supply to generate low-temperature saturated steam, the generated steam is pumped out by the steam conveying device 41 and then is sent into the steam heating device, the steam is heated to the temperature of more than 200 ℃, the pressure of a steam outlet of the steam heating device is controlled to be more than 1.5551MPa through the steam pressure control valve 61, and saturated steam discharged by the steam heating device enters the pressure stabilizing tank 7 through the second steam discharge pipe 6 and is finally output to a steam end.

In the method, the reason for using the purified water is that the impurity in the water is less, the generated steam has less impurity and high quality, the purified water cannot scale in the flash tank 1 to affect the heat exchange efficiency and corrosion equipment, the purified water at the bottom of the flash tank 1 does not need to be discharged, and finally all the purified water can generate steam under the heating effect. The purpose of the heat exchange between the purified water and the waste heat water supply outside the flash tank 1 is to enable the temperature of the purified water entering the flash tank 1 to be close to the temperature of the waste heat water supply, reduce the temperature difference, improve the temperature of the purified water entering the flash tank 1, and prevent the vapor generated at the bottom of the flash tank 1 from condensing when encountering the purified water with lower temperature in the rising process. Purified water falls in a dispersed form after being sprayed out of the spray pipe 11, the water distribution is more uniform, the contact area of the purified water and the waste heat exchanger 2 is larger, the heat exchange efficiency is improved, and the purified water can be contacted with the waste heat exchanger 2 in a water sample in the flash tank 1 without spraying, so that the purified water can be heated and evaporated to generate low-temperature saturated steam. The steam pressure control valve 61 controls the discharge of the high-temperature steam at a certain pressure value, thereby improving the quality of the steam.

Table 1 shows the pressure, temperature and enthalpy values of saturated steam, and it can be seen from the table that when the external air pressure is below 0.0042MPa, water evaporates at 30 ℃. The pipe orifice of the flash tank 1 is communicated with the outside only comprises the purified water inlet pipe 3 and the first steam outlet pipe 4, when the vacuum air heater or the steam compressor is used for pumping negative pressure to the flash tank 1, lower air pressure can be formed in the flash tank 1, when the pressure in the vacuum tank 1 is below 0.0042MPa, the purified water can be boiled and evaporated by introducing waste heat water with the temperature of more than 30 ℃, and the generated low-pressure saturated steam is pumped by the vacuum air heater or the steam compressor immediately and then is pressed into the steam heating device. The saturated steam pressure at 200 ℃ is 1.5551MPa, when the steam is heated in the steam heating device to 200 ℃, the discharge pressure of the steam heating device is 1.5551MPa through the steam pressure control valve 61, so that the saturated steam at 200 ℃ is obtained, the steam can not flow back due to the fact that the outlet pressure of the vacuum air heater or the steam compressor is above 1.6MPa, and when the heat source temperature of the steam heating device and the outlet pressure of the vacuum air heater or the steam compressor are high enough, high-temperature saturated steam with higher temperature and pressure can be produced.

Example 1

The waste heat water at 55 ℃ is supplied to the heat source inlet pipe 21 at a flow rate of 41.5t/h, the purified water at 15 ℃ is supplied to the purified water inlet pipe 3 at a flow rate of 2t/h, the purified water is heated to about 52 ℃ after passing through the pre-heat exchanger 31, and then pumped into the flash tank 1, and is sprayed downwards from the spray head of the spray pipe 11 and falls onto the waste heat exchanger 2. The flash tank 1 is pumped by a steam conveying device 41 to negative pressure, the air pressure in the tank is maintained at about 0.0042MPa, purified water boils and evaporates in the tank to obtain low-temperature saturated steam at 30 ℃, the temperature of waste heat water supply flowing out of a heat source outlet pipe 22 is about 30 ℃, the generated low-temperature saturated steam is sent into a steam heater 5 by the steam conveying device 41, the flow rate during steam conveying is 2t/h, the steam is electrically heated to 200 ℃ and 1.5551MPa in the steam heater 5 and then enters a pressure stabilizing tank 7, and then is conveyed to a steam end by a third steam discharge pipe 8.

The equipment investment of the embodiment is about 350 ten thousand, and the energy consumption for producing 1t of saturated steam at 200 ℃ is about 200kWh. If a flash evaporation+multistage vapor compressor method is adopted, the equipment investment is about 450 ten thousand, the energy consumption for producing 1t of 200 ℃ saturated steam is about 250kWh, and the temperature of waste heat water supply is more than 70 ℃; if the steam heat pump and the multistage vapor compressor method are adopted, the equipment investment is about 580 ten thousand, the energy consumption for producing 1t of 200 ℃ saturated steam is about 400kWh, the temperature of waste heat water supply is more than 60 ℃, and low-temperature saturated steam is required to be compressed, raised in temperature and pressure by the multistage vapor compressor, so that the energy consumption is very high.

According to the device for preparing steam by utilizing the waste heat, purified water and waste heat are supplied to the inside of the negative pressure flash tank for heat exchange to generate low-temperature saturated steam, and the low-temperature saturated steam is pumped out by the steam conveying equipment and is pressurized and sent into the steam heating device for heating to obtain high-temperature steam. The device is simple, the prepared steam has less impurities and high quality, a steam heat pump and a multi-stage steam compressor unit are not needed, the equipment investment is reduced, the waste heat at the temperature of as low as 30 ℃ can be utilized for supplying water, and the high-temperature saturated steam at the temperature of more than 200 ℃ can be prepared, so that the device has the characteristics of low investment and low energy consumption.

Claims (7)

1. The utility model provides a device of utilization waste heat preparation steam, includes inclosed flash tank (1), the upper portion gaseous phase district of flash tank (1) is connected with first steam discharge pipe (4), characterized by: the flash tank (1) is connected with a purified water inlet pipe (3), and a waste heat exchanger (2) for heat exchange between a heat source and purified water is arranged at the bottom in the flash tank (1); the first steam discharge pipe (4) is connected with a steam heating device which exchanges heat with steam generated by the flash tank (1) and can strip steam to a temperature, and the first steam discharge pipe (4) is provided with a steam conveying device (41) which is used for pumping negative pressure to the flash tank (1) and preventing steam from flowing back.

2. The apparatus for preparing steam using waste heat as set forth in claim 1, wherein: the heat source inlet pipe (21) of the waste heat exchanger (2) is positioned outside the flash tank (1), the purified water inlet pipe (3) is provided with a pre-heat exchanger (31) which exchanges heat with the heat source inlet pipe (21), and the purified water inlet pipe (3) is also provided with a water pump (32).

3. The apparatus for preparing steam using waste heat as set forth in claim 1, wherein: the water purification device is characterized in that the purified water inlet pipe (3) is connected with an upper gas phase zone of the flash tank (1), a spray pipe (11) connected with the purified water inlet pipe (3) is arranged in the upper gas phase zone of the flash tank (1), and a spray head is arranged on the spray pipe (11).

4. The apparatus for preparing steam using waste heat as set forth in claim 1, wherein: the steam conveying equipment (41) is a vacuum air heater or a steam compressor, and the pressure of a steam outlet of the steam conveying equipment (41) is more than 1.6 MPa.

5. The apparatus for preparing steam using waste heat as set forth in claim 1, wherein: the steam heating device comprises a steam heater (5) for heating and raising the temperature of steam generated by the flash tank (1) or a steam mixing tank (9) for mixing and raising the temperature of the steam generated by the flash tank (1), the steam heater (5) is heated by adopting electromagnetic heating, electric heating or a heat exchanger, and the steam mixing tank (9) is connected with a steam inlet pipe (91).

6. The apparatus for preparing steam using waste heat as set forth in claim 1, wherein: the steam outlet of the steam heating device is connected with a pressure stabilizing tank (7) through a second steam discharge pipe (6), a steam pressure control valve (61) for controlling steam pressure is arranged on the second steam discharge pipe (6), and the pressure stabilizing tank (7) is connected with a third steam discharge pipe (8).

7. The apparatus for preparing steam using waste heat as set forth in claim 1, wherein: the waste heat exchanger (2) is a plate heat exchanger or a tube type heat exchanger.