Heat energy utilization system for sulfuric acid cooling process of phosphorus-fluorine chemical device

Abstract

The utility model discloses a heat energy utilization system for a sulfuric acid cooling process of a phosphorus-fluorine chemical device. Comprising a graphite primary heat exchanger, a graphite secondary heat exchanger and a waste heat utilization device, wherein the graphite primary heat exchanger and the graphite secondary heat exchanger are sequentially arranged on a sulfuric acid conveying pipeline according to the technological process of sulfuric acid cooling and are used for exchanging heat with the sulfuric acid conveying pipeline; the first-stage heat exchange water circulation pipeline is connected between the graphite first-stage heat exchanger and the waste heat utilization device, the environment cooling water circulation pipeline is used for providing cooling water for the waste heat utilization device, and the second-stage heat exchange water circulation pipeline is connected between the environment cooling water circulation pipeline and the graphite second-stage heat exchanger. The primary heat exchange water circulation pipeline is connected with a driving heat source input / input end of the waste heat utilization device, and the waste heat utilization device is connected with a waste heat utilization heat exchange pipeline. According to the utility model, the heat energy utilization rate of sulfuric acid cooling of the phosphorus-fluorine chemical device is improved, and full utilization of waste heat is realized.

Description

Technical Field

[0001] The utility model relates to the technical field of phosphorus and fluorine chemical industry, in particular to a heat energy utilization system used in a sulfuric acid cooling process of a phosphorus and fluorine chemical industry device. Background Art

[0002] In the phosphate and fluorine chemical industry, a sulfuric acid cooling process is involved in phosphate and fluorine chemical plants. This process requires cooling high-temperature sulfuric acid at 75% concentration. This process uses a graphite cooling heat exchanger. Specifically, sulfuric acid at 75% concentration and 130°C enters the graphite cooling heat exchanger and exchanges heat with the graphite cooling heat exchanger's circulating cooling water, ultimately cooling the sulfuric acid to 50°C.

[0003] The above-mentioned high-temperature sulfuric acid cooling process has the disadvantage that the circulating cooling water still contains a large amount of heat after heat exchange, and this part of the heat is not used as waste heat, resulting in a waste of heat source. Utility Model Content

[0004] To solve the above problems, this utility model proposes a heat energy utilization system for the sulfuric acid cooling process in a phosphorus-fluorine chemical plant, aiming to improve the heat energy utilization rate of the sulfuric acid cooling process in a phosphorus-fluorine chemical plant and fully utilize the waste heat. The specific technical solution is as follows:

[0005] A heat energy utilization system for a sulfuric acid cooling process in a phosphorus-fluorine chemical plant comprises a graphite primary heat exchanger and a graphite secondary heat exchanger, which are sequentially arranged on a sulfuric acid conveying pipeline according to the sulfuric acid cooling process flow for exchanging heat with the sulfuric acid conveying pipeline; a waste heat utilization device for utilizing waste heat during sulfuric acid cooling; a primary water exchange water circulation pipeline connected between the graphite primary heat exchanger and the waste heat utilization device; an ambient cooling water circulation pipeline for providing cooling water to the waste heat utilization device; and a secondary water exchange water circulation pipeline connected between the ambient cooling water circulation pipeline and the graphite secondary heat exchanger. The primary water exchange water circulation pipeline is connected to a driving heat source input / output end of the waste heat utilization device, and the waste heat utilization device is connected to the waste heat utilization heat exchange pipeline.

[0006] As one of the preferred solutions of the waste heat utilization device in the present invention, the waste heat utilization device is an absorption refrigeration unit.

[0007] Preferably, the absorption refrigeration unit is a lithium bromide absorption refrigeration unit, and the waste heat utilization heat exchange pipeline is a desalted water input pipeline and a low-temperature cold water output pipeline connected to the lithium bromide absorption refrigeration unit for producing low-temperature cold water.

[0008] As the second preferred solution of the waste heat utilization device in the present invention, the waste heat utilization device is an absorption steam production device.

[0009] Preferably, the absorption steam production device is a lithium bromide absorption type II heat pump, and the waste heat utilization heat exchange pipeline is a desalted water input pipeline and a steam output pipeline for producing steam connected to the lithium bromide absorption type II heat pump.

[0010] In the present invention, the first-level water exchange water circulation pipeline includes a heat extraction water supply pipeline and a heat extraction water return pipeline, and a circulation pump is provided on the first-level water exchange water circulation pipeline.

[0011] Preferably, a hot water shut-off valve is provided on the heat supply pipe and the heat return pipe of the first-level water exchange water circulation pipe.

[0012] Preferably, the pressure of the desalted water in the primary water exchange water circulation pipeline is higher than the pressure of the sulfuric acid in the sulfuric acid delivery pipeline.

[0013] In the present invention, the lithium bromide absorption refrigeration unit is equipped with a generator, a condenser, an evaporator and an absorber. The waste heat is utilized by a heat exchange pipeline connected between the graphite primary heat exchanger and the generator of the lithium bromide absorption refrigeration unit; the ambient cooling water circulation pipeline is connected to the evaporator for heat exchange; the desalted water enters the absorber and the condenser in sequence through the desalted water input pipeline for heat exchange and then comes out of the low-temperature cold water output pipeline to produce the low-temperature cold water.

[0014] The above-mentioned waste heat utilization process using lithium bromide absorption refrigeration unit is as follows:

[0015] (1) Sulfuric acid cooling process: High-temperature sulfuric acid with a concentration of 75% and a temperature of 130°C enters the graphite primary heat exchanger, cools down to 80°C after heat exchange, and then enters the graphite secondary heat exchanger, exchanges heat with the ambient cooling water in the graphite secondary heat exchanger and cools down to 50°C;

[0016] (2) Waste heat utilization process: The lithium bromide absorption refrigeration unit uses 90℃ hot water after circulating heat exchange with the graphite primary heat exchanger as the driving heat source, and uses 32℃ ambient cooling water as the working cooling water required by the lithium bromide absorption refrigeration unit; the lithium bromide absorption refrigeration unit exchanges heat between the desalted water with a return water temperature of 10℃ and the lithium bromide absorption refrigeration unit, and produces cold water with a supply water temperature of 5℃ for use in the process, thereby realizing the waste heat utilization in the sulfuric acid cooling process.

[0017] In the present invention, the lithium bromide absorption type II heat pump is equipped with a generator, a condenser, an evaporator and an absorber. The waste heat is utilized by connecting a heat exchange pipeline between the graphite primary heat exchanger and the generator of the lithium bromide absorption type II heat pump; the ambient cooling water circulation pipeline is respectively connected to the condenser for heat exchange; the desalted water enters the absorber in sequence through the desalted water input pipeline for heat exchange and then comes out of the steam output pipeline to produce the steam.

[0018] The above waste heat utilization process using lithium bromide absorption type II heat pump is as follows:

[0019] (1) Sulfuric acid cooling process: High-temperature sulfuric acid with a concentration of 75% and a temperature of 130°C enters the graphite primary heat exchanger, cools down to 80°C after heat exchange, and then enters the graphite secondary heat exchanger, exchanges heat with the ambient cooling water in the graphite secondary heat exchanger and cools down to 50°C;

[0020] (2) Waste heat utilization process: The lithium bromide absorption type II heat pump uses 90℃ hot water after circulating heat exchange with the graphite primary heat exchanger as the driving heat source, and uses 32℃ ambient cooling water as the working cooling water required by the lithium bromide absorption type II heat pump; the lithium bromide absorption type II heat pump exchanges desalted water with a return water temperature of 10℃ with the lithium bromide absorption refrigeration unit to produce high-grade steam with a temperature of 143℃ for process use, thereby realizing the waste heat utilization in the sulfuric acid cooling process.

[0021] The beneficial effects of the utility model are:

[0022] First, the utility model is a heat energy utilization system for the sulfuric acid cooling process of a phosphorus and fluorine chemical plant. By adopting a graphite primary heat exchanger and a graphite secondary heat exchanger, and being equipped with an absorption refrigeration unit for circulating heat exchange with the graphite primary heat exchanger, the waste heat after heat exchange in the graphite primary heat exchanger is used as the driving heat source of the absorption refrigeration unit, and a large amount of cold water with a water supply temperature of 5°C can be produced for use in the process, thereby realizing the waste heat utilization in the sulfuric acid cooling process.

[0023] Second, the utility model is a heat energy utilization system for the sulfuric acid cooling process of a phosphorus-fluorine chemical plant. By adopting a graphite primary heat exchanger and a graphite secondary heat exchanger, and being equipped with an absorption-type second-class heat pump for circulating heat exchange with the graphite primary heat exchanger, the waste heat after heat exchange in the graphite primary heat exchanger is used as the driving heat source of the absorption-type second-class heat pump, and high-grade steam with a temperature of 143°C can be produced for use in the process, thereby realizing the waste heat utilization in the sulfuric acid cooling process.

[0024] Third, the utility model is a heat energy utilization system for the sulfuric acid cooling process of the phosphorus and fluorine chemical plant, which adopts an absorption refrigeration unit to realize the conversion of waste heat from sulfuric acid cooling, and its refrigeration efficiency reaches more than 40%.

[0025] Fourth, the utility model is a heat energy utilization system for the sulfuric acid cooling process of the phosphorus and fluorine chemical plant, which adopts an absorption type II heat pump to realize the conversion of the waste heat of sulfuric acid cooling, and its steam production system efficiency reaches more than 20%. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1This is one of the structural diagrams of a heat energy utilization system for a sulfuric acid cooling process in a phosphorus and fluorine chemical plant of the present invention (the waste heat utilization device adopts an absorption refrigeration unit);

[0027] Figure 2 This is the second structural diagram of a heat energy utilization system for a sulfuric acid cooling process in a phosphorus and fluorine chemical plant of the present invention (the waste heat utilization device adopts an absorption steam production device);

[0028] Figure 3 This is a schematic diagram of the sulfuric acid cooling process in an existing phosphorus and fluorine chemical plant. DETAILED DESCRIPTION

[0029] The following embodiments are used to further describe the specific embodiments of the present invention in conjunction with the accompanying drawings and examples. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention.

[0030] like Figures 1 to 3 The figure shows an embodiment of a heat energy utilization system for a sulfuric acid cooling process of a phosphorus-fluorine chemical plant according to the present invention, comprising a graphite primary heat exchanger and a graphite secondary heat exchanger arranged in sequence on the sulfuric acid conveying pipeline according to the process flow of sulfuric acid cooling for heat exchange with the sulfuric acid conveying pipeline, a waste heat utilization device for realizing waste heat utilization during sulfuric acid cooling, a primary water exchange water circulation pipeline connected between the graphite primary heat exchanger and the waste heat utilization device, an ambient cooling water circulation pipeline for providing cooling water to the waste heat utilization device, and a secondary water exchange water circulation pipeline connected between the ambient cooling water circulation pipeline and the graphite secondary heat exchanger. The primary water exchange water circulation pipeline is connected to the driving heat source input / output end of the waste heat utilization device, and the waste heat utilization device is connected to the waste heat utilization heat exchange pipeline.

[0031] As one of the preferred solutions of the waste heat utilization device in this embodiment, the waste heat utilization device is an absorption refrigeration unit.

[0032] Preferably, the absorption refrigeration unit is a lithium bromide absorption refrigeration unit, and the waste heat utilization heat exchange pipeline is a desalted water input pipeline and a low-temperature cold water output pipeline connected to the lithium bromide absorption refrigeration unit for producing low-temperature cold water.

[0033] As the second preferred solution of the waste heat utilization device in this embodiment, the waste heat utilization device is an absorption steam production device.

[0034] Preferably, the absorption steam production device is a lithium bromide absorption type II heat pump, and the waste heat utilization heat exchange pipeline is a desalted water input pipeline and a steam output pipeline for producing steam connected to the lithium bromide absorption type II heat pump.

[0035] In this embodiment, the first-level water exchange water circulation pipeline includes a heat extraction water supply pipeline and a heat extraction water return pipeline, and a circulation pump is provided on the first-level water exchange water circulation pipeline.

[0036] Preferably, a hot water shut-off valve is provided on the heat supply pipe and the heat return pipe of the first-level water exchange water circulation pipe.

[0037] Preferably, the pressure of the desalted water in the primary water exchange water circulation pipeline is higher than the pressure of the sulfuric acid in the sulfuric acid delivery pipeline.

[0038] In this embodiment, the lithium bromide absorption refrigeration unit is equipped with a generator, a condenser, an evaporator and an absorber. The waste heat is utilized by a heat exchange pipeline connected between the graphite primary heat exchanger and the generator of the lithium bromide absorption refrigeration unit; the ambient cooling water circulation pipeline is connected to the evaporator for heat exchange; the desalted water enters the absorber and condenser in sequence through the desalted water input pipeline for heat exchange and then comes out of the low-temperature cold water output pipeline to produce the low-temperature cold water.

[0039] The process flow of the high-temperature sulfuric acid secondary heat recovery and conversion refrigeration device using the lithium bromide absorption refrigeration unit is described as follows:

[0040] High-temperature sulfuric acid two-stage heat recovery and conversion refrigeration technology: 130°C, 75% sulfuric acid is cooled using a two-stage graphite heat exchanger. The first stage heat recovery temperature ranges from 130°C to 80°C; the second stage heat recovery ranges from 80°C to 50°C. The first stage cold side temperature ranges from 60°C to 90°C, while the second stage cold side temperature ranges from 32°C to 37°C. Using 90°C hot water, an absorption refrigeration unit produces 5°C cold water for process use, replacing the centrifuge load. The sulfuric acid cooling waste heat conversion refrigeration efficiency exceeds 40%.

[0041] Design objectives: 1. Reduce the power load of the electric ice machine; 2. Get the 5℃ cold water required in the process for free while cooling the sulfuric acid.

[0042] Design tips: Graphite heat exchangers have a risk of leakage. To ensure that the hot desalted water in the refrigeration unit is not contaminated, the pressure of the hot desalted water in the unit is designed to be greater than the pressure on the sulfuric acid side. At the same time, a hot water shut-off valve is designed to ensure safe and stable operation.

[0043] The above-mentioned high-temperature sulfuric acid two-stage heat recovery and conversion refrigeration technology route has a wide load adjustment range, and the system is steplessly adjustable between 20% and 100%.

[0044] In this embodiment, the lithium bromide absorption type II heat pump has a built-in generator, condenser, evaporator and absorber. The waste heat utilization heat exchange pipeline is connected between the graphite primary heat exchanger and the generator of the lithium bromide absorption type II heat pump; the environmental cooling water circulation pipeline is connected to the condenser for heat exchange; the desalted water enters the absorber in turn through the desalted water input pipeline for heat exchange and then comes out of the steam output pipeline to produce the steam.

[0045] The process flow of the high-temperature sulfuric acid secondary heat recovery and conversion steam production device using the lithium bromide absorption type II heat pump is described as follows:

[0046] The high-temperature sulfuric acid two-stage heat recovery and conversion technology uses a two-stage graphite heat exchanger to cool down 75% sulfuric acid at 130°C. The first-stage heat recovery temperature ranges from 130°C to 80°C, while the second-stage heat recovery ranges from 80°C to 50°C. The first-stage cold-side temperature ranges from 60°C to 90°C, while the second-stage cold-side temperature ranges from 32°C to 37°C. Using 90°C hot water, a Class II absorption heat pump is used to generate 0.3 MPa steam for process use. The sulfuric acid cooling waste heat conversion steam production system achieves an efficiency exceeding 20%.

[0047] Design objectives: 1. Utilize waste heat to produce steam and reduce boiler load; 2. Reduce circulating water consumption while cooling sulfuric acid.

[0048] Design tips: Graphite heat exchangers have a risk of leakage. To ensure that the hot desalted water in the refrigeration unit is not contaminated, the pressure of the hot desalted water in the unit is designed to be greater than the pressure on the sulfuric acid side. At the same time, a hot water shut-off valve is designed to ensure safe and stable operation.

[0049] 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 and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A heat energy utilization system for sulfuric acid cooling process in phosphorus and fluorine chemical plant, characterized in that: It includes a graphite primary heat exchanger and a graphite secondary heat exchanger, which are sequentially arranged on the sulfuric acid delivery pipeline according to the process flow of sulfuric acid cooling and are used for heat exchange with the sulfuric acid delivery pipeline, a waste heat utilization device for realizing waste heat utilization during sulfuric acid cooling, a primary water exchange water circulation pipeline connected between the graphite primary heat exchanger and the waste heat utilization device, an ambient cooling water circulation pipeline for providing cooling water to the waste heat utilization device, and a secondary water exchange water circulation pipeline connected between the ambient cooling water circulation pipeline and the graphite secondary heat exchanger. The primary water exchange water circulation pipeline is connected to the driving heat source input / input end of the waste heat utilization device, and the waste heat utilization device is connected to the waste heat utilization heat exchange pipeline.

2. The heat energy utilization system for sulfuric acid cooling process in phosphorus and fluorine chemical plant according to claim 1, characterized in that: The waste heat utilization device is an absorption refrigeration unit.

3. The heat energy utilization system for sulfuric acid cooling process in phosphorus and fluorine chemical plant according to claim 2, characterized in that: The absorption refrigeration unit is a lithium bromide absorption refrigeration unit, and the waste heat utilization heat exchange pipeline is a desalted water input pipeline and a low-temperature cold water output pipeline connected to the lithium bromide absorption refrigeration unit for producing low-temperature cold water.

4. The heat energy utilization system for sulfuric acid cooling process in phosphorus and fluorine chemical plant according to claim 1, characterized in that: The waste heat utilization device is an absorption steam production device.

5. The heat energy utilization system for sulfuric acid cooling process in phosphorus and fluorine chemical plant according to claim 4, characterized in that: The absorption steam production device is a lithium bromide absorption type II heat pump, and the waste heat utilization heat exchange pipeline is a desalted water input pipeline and a steam output pipeline connected to the lithium bromide absorption type II heat pump for producing steam.

6. A heat energy utilization system for sulfuric acid cooling process in phosphorus and fluorine chemical plant according to claim 2 or 4, characterized in that: The first-level water exchange water circulation pipeline includes a heat-extraction water supply pipeline and a heat-extraction water return pipeline, and a circulation pump is provided on the first-level water exchange water circulation pipeline.

7. The heat energy utilization system for sulfuric acid cooling process in phosphorus and fluorine chemical plant according to claim 6, characterized in that: Hot water shut-off valves are respectively provided on the heat supply pipe and the heat return pipe of the first-level water exchange water circulation pipe.

8. The heat energy utilization system for sulfuric acid cooling process in phosphorus and fluorine chemical plant according to claim 6, characterized in that: The pressure of the desalted water in the primary water exchange water circulation pipeline is higher than the pressure of the sulfuric acid in the sulfuric acid delivery pipeline.

9. The heat energy utilization system for sulfuric acid cooling process in phosphorus and fluorine chemical plant according to claim 3, characterized in that: The lithium bromide absorption refrigeration unit is equipped with a generator, a condenser, an evaporator and an absorber. The waste heat is utilized by a heat exchange pipeline connected between the graphite primary heat exchanger and the generator of the lithium bromide absorption refrigeration unit; the ambient cooling water circulation pipeline is connected to the evaporator for heat exchange; desalted water enters the absorber and condenser in sequence through the desalted water input pipeline for heat exchange and then exits the low-temperature cold water output pipeline to produce the low-temperature cold water.

10. The heat energy utilization system for sulfuric acid cooling process in phosphorus and fluorine chemical plant according to claim 5, characterized in that: The lithium bromide absorption type II heat pump is equipped with a generator, a condenser, an evaporator and an absorber. The waste heat is utilized by connecting a heat exchange pipeline between the graphite primary heat exchanger and the generator of the lithium bromide absorption type II heat pump; the ambient cooling water circulation pipeline is respectively connected to the condenser for heat exchange; the desalted water enters the absorber in sequence through the desalted water input pipeline for heat exchange and then comes out of the steam output pipeline to produce the steam.

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