System for coupling low-temperature coal gas waste heat utilization with ammonia-containing wastewater purification

Abstract

The utility model discloses a system for coupling low-temperature coal gas waste heat utilization with ammonia-containing wastewater purification, which relates to the technical field of low-temperature coal gas waste heat utilization and comprises an evaporator, a separation tank, a steam turbine, a generator, a cooler, an ejector, a condenser, a pressure pump, a booster pump, a deamination device, a gas-liquid separator, a cooling device, a preheater and a circulating water preparation device. The evaporator is provided with a hot gas inlet and a cold gas outlet, a first working medium inlet of the evaporator is connected with a first working medium outlet of the booster pump, a second working medium outlet of the evaporator is connected with a second working medium inlet of the separation tank, and an ammonia-rich steam inlet of the steam turbine is connected with an ammonia-rich steam outlet of the separation tank. According to the Kalina cycle principle, ammonia-containing wastewater purification and utilization are coupled, 60%-80% of ammonia water is adopted as a working medium, ammonia-rich steam is used for expansion acting, output work is converted into electric energy for self-use, the rest part can be output outwards, and the energy utilization rate is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of low-temperature coal gas waste heat utilization, in particular to a system for low-temperature coal gas waste heat utilization coupled with ammonia-containing waste water purification. Background Art

[0002] Industrial production is the main body of energy consumption, and the emission of most industrial waste heat has become the main reason for energy waste and low utilization rate. Waste heat is divided into three categories: high temperature, medium temperature and low temperature. Waste heat resources with a temperature higher than 500℃ are called high-temperature waste heat, waste heat resources with a temperature between 200 and 500℃ are called medium-temperature waste heat, and waste heat resources with a temperature less than 200℃ are low-temperature waste heat. The low-temperature waste heat has a wide range and a large amount of heat. Due to technical limitations, most of this heat is directly discharged and wasted. The atmospheric pressure circulating fluidized bed gasification technology is used to produce fuel gas with medium and low calorific value, which can be used as raw gas in building materials, metallurgy, glass and other industries and is widely used.

[0003] In order to meet the requirements of pressurization and desulfurization devices, the existing gasification device outlet gas needs to reduce the 150-200℃ gas to below 50℃. A large amount of sensible heat and latent heat are released during the gas cooling process, and some condensed water is generated. However, due to the low temperature of this part of the heat source and the small heat transfer temperature difference, heat recovery is difficult. At present, circulating cooling water is mainly used for indirect cooling, and this part of the heat is taken away by the circulating water, resulting in a waste of this part of energy and an increase in the energy consumption of the circulating water system. In addition, the generated condensed water contains a certain amount of ammonia nitrogen, which needs to be purified to meet the requirements of standard emissions. At present, low-pressure steam is mainly used for ammonia evaporation treatment, which consumes a lot of steam and discharges a lot of wastewater. Therefore, a system for coupling the utilization of low-temperature gas waste heat with the purification of ammonia-containing wastewater is proposed. Utility Model Content

[0004] The purpose of the utility model is to solve the problems mentioned in the above background technology, and to propose a system for utilizing waste heat of low-temperature coal gas coupled with purification of ammonia-containing wastewater.

[0005] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0006] A system for utilizing waste heat of low-temperature coal gas coupled with purification of ammonia-containing wastewater, comprising an evaporator, a separation tank, a steam turbine, a generator, a cooler, an ejector, a condenser, a pressure pump, a booster pump, a deammoniation device, a gas-liquid separator, a cooling device, a preheater and a circulating water preparation device;

[0007] The evaporator is provided with a hot gas inlet and a cold gas outlet, the first working fluid inlet of the evaporator is connected to the first working fluid outlet of the booster pump, the second working fluid outlet of the evaporator is connected to the second working fluid inlet of the separation tank, the ammonia-rich steam inlet of the turbine is connected to the ammonia-rich steam outlet of the separation tank, the generator is connected to the turbine, the first condensate inlet and the first lean ammonia solution inlet of the cooler are respectively connected to the first condensate outlet of the evaporator and the first lean ammonia solution outlet of the separation tank, the second lean ammonia solution inlet and the rich ammonia condensate inlet of the ejector are respectively connected to the second lean ammonia solution outlet of the cooler and the rich ammonia condensate outlet of the turbine, the mixed ammonia solution inlet of the condenser is connected to the mixed ammonia solution outlet of the ejector, the mixed working fluid inlet of the booster pump is connected to the mixed working fluid outlet of the condenser, and the first working fluid outlet of the booster pump is connected to the first working fluid inlet of the evaporator.

[0008] Preferably, the second condensate inlet of the boost pump is connected to the second condensate outlet of the cooler, the third condensate outlet of the boost pump is connected to the third condensate inlet of the deamination device, the third condensate of the boost pump is divided into two paths, one path is directly connected to the upper part of the deamination device, and the other path enters the preheater for preheating and then is connected to the lower part of the deamination device, and the fourth condensate inlet of the preheater is connected to the fourth condensate outlet of the deamination device.

[0009] Preferably, the first ammonia vapor inlet of the gas-liquid separator is connected to the first ammonia vapor outlet of the deammoniation device, the first reflux outlet of the gas-liquid separator is connected to the first reflux inlet of the deammoniation device, the second ammonia vapor outlet of the gas-liquid separator is connected to the second ammonia vapor inlet of a cooling device, and the cooling device is used to cool the second ammonia vapor to obtain dilute ammonia water.

[0010] Preferably, the fifth condensed water inlet of the circulating water preparation device is connected to the fifth condensed water outlet of the preheater, and the circulating water preparation device is connected to the condenser and the cooling device through independent circulation pipelines respectively.

[0011] Preferably, the first working fluid in the evaporator is ammonia water with a concentration of 60% to 80%, the outlet pressure of the first working fluid of the booster pump is 1.5 to 2.5 MPaG, the concentration of dilute ammonia water at the outlet of the cooling device is 15% to 20%, and the ammonia content of the fifth condensed water in the preheater is less than 50 ppm, which is directly used as water replenishment for the circulating water preparation device.

[0012] Compared with the prior art, the utility model has the following advantages:

[0013] 1. The utility model is based on the Kalina cycle principle, coupled with the purification and utilization of ammonia-containing wastewater, adopts 60% to 80% ammonia water as the working fluid, and the ammonia-rich steam is expanded to do work. The output work is converted into electrical energy for self-use, and the remaining part can be exported to the outside, thereby improving the energy utilization rate.

[0014] 2. Compared with the organic Rankine cycle (ORC), the utility model uses ammonia water as a natural working fluid, which is cheap and has better environmental protection performance than organic working fluids. In addition, the evaporation of ammonia water is a temperature-changing process, which can reduce the irreversible loss of the heat exchange process and improve the utilization rate of thermal energy. The lean ammonia solution is used to preheat the condensed water, which reduces the steam consumption in the deammoniation process and reduces energy consumption.

[0015] 2. The condensed water of the utility model is preheated and deammonified to obtain dilute ammonia water with a concentration of 15% to 20% for external delivery, or it can be concentrated as a supplement to the first working fluid. The purified condensed water can be directly sent to the circulating water preparation device as make-up water. The system has no external wastewater and is more environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural system diagram of the utility model.

[0017] Figure 2 It is a method diagram of the utility model.

[0018] In the figure: 1 evaporator, 2 separation tank, 3 turbine, 4 generator, 5 cooler, 6 ejector, 7 condenser, 8 pressure pump, 9 booster pump, 10 deammonification device, 11 gas-liquid separator, 12 cooling device, 13 preheater, 14 circulating water preparation device. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments.

[0020] Reference Figure 1-2 As shown, a system for utilizing waste heat of low-temperature coal gas coupled with purification of ammonia-containing wastewater comprises an evaporator 1, a separation tank 2, a steam turbine 3, a generator 4, a cooler 5, an ejector 6, a condenser 7, a pressure pump 8, a booster pump 9, a deammoniation device 10, a gas-liquid separator 11, a cooling device 12, a preheater 13 and a circulating water preparation device 14;

[0021] The evaporator 1 is provided with a hot gas inlet and a cold gas outlet. The first working medium inlet of the evaporator 1 is connected to the first working medium outlet of the booster pump 8, the second working medium outlet of the evaporator 1 is connected to the second working medium inlet of the separation tank 2, the ammonia-rich steam inlet of the turbine 3 is connected to the ammonia-rich steam outlet of the separation tank 2, the generator 4 is connected to the turbine 3, the first condensed water inlet and the first lean ammonia solution inlet of the cooler 5 are respectively connected to the first condensed water outlet of the evaporator 1 and the first lean ammonia solution outlet of the separation tank 2, and the second lean ammonia solution of the ejector 6 is connected to the first condensed water outlet of the evaporator 1 and the first lean ammonia solution outlet of the separation tank 2. The inlet of the condenser 7 is connected to the outlet of the mixed ammonia solution of the ejector 6, the mixed working fluid inlet of the booster pump 8 is connected to the mixed working fluid outlet of the condenser 7, and the first working fluid outlet of the booster pump 8 is connected to the first working fluid inlet of the evaporator 1.

[0022] In this embodiment, the second condensate inlet of the boost pump 9 is connected to the second condensate outlet of the cooler 5, and the third condensate outlet of the boost pump 9 is connected to the third condensate inlet of the deamination device 10. The third condensate of the boost pump 9 is divided into two paths, one path is directly connected to the upper part of the deamination device 10, and the other path enters the preheater 13 for preheating and is connected to the lower part of the deamination device 10. The fourth condensate inlet of the preheater 13 is connected to the fourth condensate outlet of the deamination device 10. The deamination device 10 adopts a combined tower, which is divided into a sieve plate section and a packing section.

[0023] The first ammonia vapor inlet of the gas-liquid separator 11 is connected to the first ammonia vapor outlet of the deammoniation device 10, the first reflux outlet of the gas-liquid separator 11 is connected to the first reflux inlet of the deammoniation device 10, the second ammonia vapor outlet of the gas-liquid separator 11 is connected to the second ammonia vapor inlet of the cooling device 12, and the cooling device 12 is used to cool the second ammonia vapor to obtain dilute ammonia water.

[0024] In this embodiment, the fifth condensate inlet of the circulating water preparation device 14 is connected to the fifth condensate outlet of the preheater 13, and the circulating water preparation device 14 is connected to the condenser 7 and the cooling device 12 through independent circulation pipes respectively. The circulating water preparation device 14 adopts one of a closed cooling tower or an open cooling tower.

[0025] In this embodiment, the first working medium in the evaporator 1 is ammonia water with a concentration of 60% to 80%, the first working medium outlet pressure of the booster pump 8 is 1.5 to 2.5 MPaG, and the concentration of dilute ammonia water at the outlet of the cooling device 12 is 15% to 20%.

[0026] Among them, the ammonia content of the fifth condensed water in the preheater 13 is less than 50ppm, and it is directly used as water replenishment for the circulating water preparation device 14 without external discharge. The circulating water inlet temperature of the circulating water preparation device 14 is 5-8°C higher than the local wet-bulb temperature, and the circulating water return temperature is 10°C higher than the circulating water inlet temperature.

[0027] Working process and principle:

[0028] The coal gas and the first working medium are heat exchanged in the evaporator 1 to obtain clean coal gas at 40-50°C, the first condensed water and the second working medium. The second working medium is separated in the separation tank 2 to obtain ammonia-rich steam and a first ammonia-lean solution. The ammonia-rich steam is expanded in the turbine 3 to do work, and the electrical energy is output through the generator 4, part of which is used within the system and the rest is output externally.

[0029] The first ammonia-lean solution and the first condensed water are heat exchanged in the cooler 5 to obtain the second condensed water and the second ammonia-lean solution. The second ammonia-lean solution is cooled and depressurized in the ejector 6. The ammonia-rich condensate obtained after the expansion of the turbine 3 is ejected into the ejector 6 to obtain a mixed ammonia solution. The mixed ammonia solution is condensed in the condenser 7 to obtain a mixed working medium. The mixed working medium is pressurized by the booster pump 8 to obtain the first working medium. The first working medium is continuously circulated back to the evaporator 1 to exchange heat with the hot coal gas. The first working medium is ammonia water with a concentration of 60% to 80%. The second condensed water is pressurized to obtain the third condensed water. The degassing is carried out in two ways. Ammonia treatment, one way is sent directly to the deammonification device 10, and the other way is sent to the deammonification device 10 after preheating through the fourth condensed water at the bottom of the deammonification device 10, to obtain the first ammonia vapor and the fifth condensed water, and the fifth condensed water is used as the make-up water of the circulating water preparation device 14, the first ammonia vapor is subjected to gas-liquid separation treatment to obtain the second ammonia vapor and the first reflux, the first reflux is directly returned to the deammonification device 10 for deammonification treatment, the second ammonia vapor is cooled to obtain the dilute ammonia water with a concentration of 15% to 20% for external output, and the circulating water preparation device 14 adopts an open cooling tower to provide circulating water for the condenser 7 and the cooling device 12.

[0030] The system of the present invention can efficiently utilize medium and low temperature waste heat, solve the problems of waste of low temperature coal gas waste heat, high circulation water consumption, high energy consumption for purification of ammonia-containing wastewater, large wastewater discharge, etc. in the prior art. While efficiently utilizing medium and low temperature waste heat, it provides electricity and 15% to 20% dilute ammonia water to the outside world, and has no wastewater, waste solid, or waste gas emissions, which is more green and environmentally friendly.

[0031] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes within the technical scope disclosed by the present invention according to the technical scheme and the utility model concept of the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A system for low-temperature coal gas waste heat utilization coupled with ammonia-containing wastewater purification, characterized in that: It comprises an evaporator (1), a separation tank (2), a steam turbine (3), a generator (4), a cooler (5), an ejector (6), a condenser (7), a pressure pump (8), a booster pump (9), a deammoniation device (10), a gas-liquid separator (11), a cooling device (12), a preheater (13) and a circulating water preparation device (14); The evaporator (1) is provided with a hot gas inlet and a cold gas outlet. The first working medium inlet of the evaporator (1) is connected to the first working medium outlet of the booster pump (8). The second working medium outlet of the evaporator (1) is connected to the second working medium inlet of the separation tank (2). The ammonia-rich steam inlet of the steam turbine (3) is connected to the ammonia-rich steam outlet of the separation tank (2). The generator (4) is connected to the steam turbine (3). The first condensed water inlet and the first lean ammonia solution inlet of the cooler (5) are respectively connected to the first cooling medium outlet of the evaporator (1). The condensate outlet is connected to the first lean ammonia solution outlet of the separation tank (2); the second lean ammonia solution inlet and the rich ammonia condensate inlet of the ejector (6) are respectively connected to the second lean ammonia solution outlet of the cooler (5) and the rich ammonia condensate outlet of the turbine (3); the mixed ammonia solution inlet of the condenser (7) is connected to the mixed ammonia solution outlet of the ejector (6); the mixed working fluid inlet of the booster pump (8) is connected to the mixed working fluid outlet of the condenser (7); and the first working fluid outlet of the booster pump (8) is connected to the first working fluid inlet of the evaporator (1).

2. A system for low-temperature coal gas waste heat utilization coupled with ammonia-containing wastewater purification according to claim 1, characterized in that: The second condensate inlet of the booster pump (9) is connected to the second condensate outlet of the cooler (5), and the third condensate outlet of the booster pump (9) is connected to the third condensate inlet of the deamination device (10). The third condensate of the booster pump (9) is divided into two paths, one path is directly connected to the upper part of the deamination device (10), and the other path enters the preheater (13) for preheating and is then connected to the lower part of the deamination device (10). The fourth condensate inlet of the preheater (13) is connected to the fourth condensate outlet of the deamination device (10).

3. The system for low-temperature coal gas waste heat utilization coupled with ammonia-containing wastewater purification according to claim 2 is characterized in that: The first ammonia vapor inlet of the gas-liquid separator (11) is connected to the first ammonia vapor outlet of the deammonification device (10), the first reflux outlet of the gas-liquid separator (11) is connected to the first reflux inlet of the deammonification device (10), the second ammonia vapor outlet of the gas-liquid separator (11) is connected to the second ammonia vapor inlet of the cooling device (12), and the cooling device (12) is used to cool the second ammonia vapor to obtain dilute ammonia water.

4. A system for low-temperature coal gas waste heat utilization coupled with ammonia-containing wastewater purification according to claim 3, characterized in that: The fifth condensate inlet of the circulating water preparation device (14) is connected to the fifth condensate outlet of the preheater (13), and the circulating water preparation device (14) is connected to the condenser (7) and the cooling device (12) through independent circulation pipelines.

5. The system for low-temperature coal gas waste heat utilization coupled with ammonia-containing wastewater purification according to claim 4 is characterized in that: The first working fluid in the evaporator (1) is ammonia water with a concentration of 60% to 80%. The outlet pressure of the first working fluid of the booster pump (8) is 1.5 to 2.5 MPaG. The concentration of dilute ammonia water at the outlet of the cooling device (12) is 15 to 20%. The ammonia content of the fifth condensed water in the preheater (13) is less than 50 ppm and is directly used as water replenishment for the circulating water preparation device (14).

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