Comprehensive utilization system of low-grade heat source

Abstract

The utility model relates to the field of environmental protection, and discloses a comprehensive utilization system of a low-grade heat source, which comprises a urea ammonia preparation workshop, a urea hydrolyzer, a steam supply pipe, a drain tank, an ammonia-air mixer, a heating fan and a water heating type air curtain, the steam trap is connected to a drain tank through three switchable pipelines; one pipeline is connected with the water heating type air curtain, and the other pipeline is directly communicated with a drain tank; a heat exchanger is arranged on one pipeline; and the heat exchanger is used for carrying out heat exchange on air and condensed water and taking the heated air as inlet air of the heating fan. According to the system, high-temperature condensed water serves as a heat source of the water heating type air curtain and an air inlet heat source of the heating fan, comprehensive utilization of energy of a low-grade heat source is achieved, and the rime fog phenomenon of a drainage tank in winter is eradicated or relieved.

Description

Technical Field

[0001] The utility model relates to the technical field of environmental protection equipment, in particular to a comprehensive utilization system of low-grade heat sources. Background Art

[0002] Currently, urea hydrolysis to produce ammonia has become the main ammonia production process in thermal power plants.

[0003] The hydrolysis of urea to produce ammonia requires steam to provide the heat required for the reaction. After the steam is used up, it will turn into condensed water, which will be collected in the drain tank. Since the temperature of the condensed water is 90-95℃, a large amount of white mist (water vapor) will appear at the exhaust port of the drain tank, which is more obvious in winter and seriously affects the visibility of the relevant area.

[0004] The technical problem that needs to be solved in this case is: to achieve comprehensive energy utilization of low-grade heat sources and to eliminate or alleviate the occurrence of white fog in the drain tank in winter. Utility Model Content

[0005] The purpose of the utility model is to solve the above problems and provide a comprehensive utilization system of low-grade heat sources. The system uses condensed water with a higher temperature as the heat source of the water-heating air curtain and the air inlet heat source of the heating fan, thereby realizing the comprehensive utilization of the energy of the low-grade heat source and eliminating or alleviating the occurrence of white fog in the drain tank in winter.

[0006] To achieve the above objectives, the present invention provides the following technical solutions:

[0007] A comprehensive utilization system for low-grade heat sources, comprising a urea ammonia production workshop, a urea hydrolyzer located in the urea ammonia production workshop, a steam supply pipe for heating liquid in the urea hydrolyzer, and a drain tank, wherein the steam supply pipe is provided with a drain tank, an ammonia-air mixer, and a heating fan. The heating fan is used to provide hot air to the ammonia-air mixer, and the urea hydrolyzer is used to provide ammonia gas to the ammonia-air mixer.

[0008] It also includes a water-heated air curtain for providing hot air to the urea ammonia production plant;

[0009] The steam trap is connected to the steam trap tank through three switchable pipelines; one of the pipelines is connected to the water-heated air curtain, and one of the pipelines is directly connected to the steam trap tank; a heat exchanger is provided on one of the pipelines; the heat exchanger is used to exchange heat between air and condensate and use the heated air as the inlet air of the heating fan.

[0010] Compared with the prior art, the beneficial effects of the present invention are:

[0011] The utility model uses the low-grade heat of condensed water as the heat source of the water-heating air curtain and the air inlet heat source of the heating fan. After the energy is utilized, the temperature is reduced to 70°C or below, which can effectively prevent or alleviate the occurrence of white fog. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 is a schematic structural diagram of Example 1;

[0013] Figure 2 It is a cross-sectional view of the conveying pipeline and the inner tube of Example 1 in a direction perpendicular to the axial direction. DETAILED DESCRIPTION

[0014] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0015] Example 1

[0016] refer to Figures 1-2 A comprehensive utilization system for low-grade heat sources includes a urea ammonia production workshop, a urea hydrolyzer 1 located in the urea ammonia production workshop, a steam supply pipe 2 for heating the liquid in the urea hydrolyzer 1, and a steam trap 3. The steam supply pipe 2 is provided with a steam trap 4. The system also includes an ammonia-air mixer 5 and a heating fan 6. The heating fan 6 is used to provide hot air to the ammonia-air mixer 5. The urea hydrolyzer 1 is used to provide ammonia gas to the ammonia-air mixer 5.

[0017] It also includes a water-heated air curtain 7 for providing hot air to the urea ammonia production workshop;

[0018] The steam trap 4 is connected to the steam trap 3 through three switchable pipelines; one of the pipelines is connected to the water-heated air curtain 7, and one of the pipelines is directly connected to the steam trap 3; a heat exchanger 15 is provided on one of the pipelines; the heat exchanger 15 is used to exchange heat between air and condensate and use the heated air as the inlet air of the heating fan 6.

[0019] During the winter production process, especially in the northern region, the urea ammonia production workshop requires separate heating. The existing workshop heating method is achieved through centralized heating.

[0020] To prevent the occurrence of white mist in the drain tank 3, the present invention uses condensate as the heat source for the water-heating air curtain 7 and the heat exchanger 15. During the production process, due to fluctuations in production load, three switchable pipelines are used to ensure that the condensate reaches the drain tank 3 through different pipelines. During normal operation, the heat source supply to the heating fan 6 must be ensured first, and the heat source supply to the water-heating air curtain 7 must be ensured secondly. If the amount of condensate generated is small, only the pipeline to the heat exchanger 15 is kept unobstructed. If the amount of condensate generated is appropriate, the pipeline directly to the drain tank 3 can be kept disconnected.

[0021] In non-winter, at least the pipeline to the water-heating air curtain 7 is kept in a disconnected state, and the other two pipelines are flexibly adjusted according to the production load.

[0022] In this embodiment, control valves 8 are implicitly installed on all three pipes. Preferably, the heat exchanger 15 includes an outer pipe 9 and an inner pipe 10 inserted into the outer pipe 9. The space between the outer and inner pipes 9 and 10 provides a passage for condensed water to pass through. One end of the inner pipe 10 is connected to the atmosphere; the other end of the inner pipe 10 is connected to the inlet of the heating fan 6. A bypass pipe 11 with a smooth inner wall can also be provided at the inlet of the heating fan 6 to directly connect to the atmosphere.

[0023] This heat exchanger 15 structure can be manufactured by self-processing using excess pipes within the factory, and has low manufacturing cost and is easy to use and maintain.

[0024] During the production process below 0°C in winter, actual measurements show that after the condensate heats the water-heating air curtain 7, the water temperature discharged to the drain tank 3 is 65-70°C. After the condensate heats the above-mentioned simplified structure heat exchanger 15, the water temperature discharged to the drain tank 3 is 75-80°C. In order to further improve the heat exchange effect of the above-mentioned heat exchanger 15, 10 heat exchange fins 12 extending along the axis of the inner tube 10 are provided inside the inner tube 10. After this optimization, the water temperature discharged to the drain tank 3 is 70-75°C, and can be reduced to 65-70°C under some working conditions.

[0025] When the condensate production is low, priority is given to maintaining the heat source supply of the heat exchanger 15. In this case, if the water-heated air curtain 7 is to maintain normal operation, the following optimized pipeline structure can be adopted: a return pipe 13 is provided at the lower part of the drain tank 3; a pump 14 is provided on the return pipe 13; the return pipe 13 is connected to the heat exchanger 15 and the water-heated air curtain 7.

[0026] At this time, the condensate is used as the heat source of the heat exchanger 15, the second pump 14 is started, and the delivery volume is increased. The warm water in the drain tank 3 is used as the heat source of the water-heated air curtain 7. In this way, the workshop heating can be maintained when the working conditions are temporarily reduced. When the working conditions return to normal, the condensate is used as the heat source of the heat exchanger 15 and the water-heated air curtain 7.

[0027] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements or modifications can be made without departing from the principles of the present invention. These improvements or modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A comprehensive utilization system for low-grade heat sources, comprising a urea ammonia production workshop, a urea hydrolyzer located in the urea ammonia production workshop, a steam supply pipe for heating the liquid in the urea hydrolyzer, and a steam trap, wherein the steam supply pipe is provided with a steam trap, characterized in that: It also includes an ammonia-air mixer and a heating fan, wherein the heating fan is used to provide hot air to the ammonia-air mixer, and the urea hydrolyzer is used to provide ammonia gas to the ammonia-air mixer; It also includes a water-heated air curtain for providing hot air to the urea ammonia production plant; The steam trap is connected to the steam trap tank through three switchable pipelines; one of the pipelines is connected to the water-heated air curtain, and one of the pipelines is directly connected to the steam trap tank; a heat exchanger is provided on one of the pipelines; the heat exchanger is used to exchange heat between air and condensate and use the heated air as the inlet air of the heating fan.

2. The comprehensive utilization system of low-grade heat source according to claim 1, characterized in that: There are control valves on all three pipelines.

3. The comprehensive utilization system of low-grade heat sources according to claim 1, characterized in that: The heat exchanger includes an outer tube and an inner tube inserted into the outer tube; the space between the outer tube and the inner tube is a passage for condensed water to pass through; one end of the inner tube is connected to the atmosphere; and the other end of the inner tube is connected to the inlet of the heating fan.

4. The comprehensive utilization system of low-grade heat sources according to claim 3, characterized in that: A plurality of heat exchange fins extending along the axis of the inner tube are provided inside the inner tube.

5. The comprehensive utilization system of low-grade heat sources according to any one of claims 1 to 4, characterized in that: A return pipe is provided at the lower part of the drain tank; a pump is provided on the return pipe; and the return pipe is connected to a heat exchanger and / or a water-heating air curtain.

Images