Ammonia still tower top waste heat recovery and ammonium sulfate mother liquor heat exchange or coal gas preheating heat exchange system

Abstract

The utility model discloses an ammonia still top waste heat recovery and ammonium sulfate mother liquor heat exchange or coal gas preheating heat exchange system, and particularly relates to a heat source for recovering ammonia gas waste heat at the top of an ammonia still in the coal chemical industry to be used for ammonium sulfate saturator mother liquor heating or ammonium sulfate coal gas preheating and other various low-grade heat users. An ammonia still top waste heat recovery and ammonium sulfate saturator heat exchange system comprises an ammonia still, a dephlegmator, a condensation cooler, a mother liquor circulating pump, a heat recovery pump, a saturator, an ammonium sulfate mother liquor heater, an auxiliary heater and the like. Waste heat of mixed fluid of ammonia gas and water vapor discharged from a dephlegmator at the top of an ammonia still tower is recovered, and a specially designed heat exchanger group is used for heating circulating mother liquor of a spray type saturator for producing ammonium sulfate to reach a set temperature; the traditional heat supply mode of heating ammonium sulfate mother liquor by using new steam as a heat source and preheating coal gas by using new steam, which is widely used at present, is replaced; and a heat exchange network for gradient utilization of energy is established, so that the purpose of energy-saving, low-carbon, environment-friendly and knotting-clearing production is achieved.

Description

Technical Field

[0001] The utility model belongs to the technical field of waste heat recovery systems and can be applied to process flows such as coal chemical ammonia distillation, as well as to waste heat recovery systems at the top of evaporation towers and distillation towers in the fields of light industry and chemical industry. The utility model specifically relates to a waste heat recovery system at the top of an ammonia distillation tower and a heat exchange system for ammonium sulfate mother liquor or coal gas preheating. Background Art

[0002] Currently, the low-grade heat energy of the two-phase fluids, such as ammonia gas and water vapor, discharged from the top fractionator of the coal chemical ammonia distillation tower is not typically recycled. Instead, circulating water or low-temperature water is used to cool the fluid through a heat exchanger into ammonia gas, which is then introduced into a saturator or further cooled into ammonia water for delivery to the desulfurization system. Due to the lack of a sound heat exchange network, this wastes heat energy and consumes a large amount of circulating water or low-temperature water. In current coal chemical production, steam is often used to heat the mother liquor or coal gas. Neither method utilizes this low-grade heat energy, increases carbon emissions, and worsens atmospheric pollution.

[0003] Currently, while some have designed a Class II absorption heat pump technology to recover waste heat from the overhead steam and use it to heat the ammonia still kettle, this system has significant drawbacks. While using a Class II absorption heat pump, the heat it supplies must also dissipate a portion of its low-grade heat into the environment, resulting in a heating system efficiency of less than 1. Fluctuations in ambient temperature significantly impact the reliability of the Class II absorption heat pump. In winter, the Class II absorption heat pump can become unstable or even cease operation, making it impossible to ensure safe production in the ammonia still. Summary of the Invention

[0004] To address the aforementioned issues, the present invention discloses a system for recovering waste heat from the top of an ammonia distillation tower and for exchanging heat for ammonium sulfate mother liquor or preheating coal gas. This system recovers waste heat from the ammonia and water vapor mixture discharged from the ammonia distillation tower's top fractionator. This heat is then used to heat the circulating mother liquor in the ammonium sulfate production spray saturator to a desired temperature via a specially designed heat exchanger. This replaces the currently widely used steam-based ammonium sulfate mother liquor heaters or the traditional heating methods of using steam as a heat medium to heat coal gas via heat exchangers. This achieves energy-saving, low-carbon, environmentally friendly, and clean production.

[0005] In order to achieve the above-mentioned purpose, the technical solution of the present utility model is as follows:

[0006] A system for recovering waste heat from the top of an ammonia still tower and exchanging heat for ammonium sulfate mother liquor or coal gas preheating comprises an ammonia still tower, a fractionator, a condenser cooler, a mother liquor circulation pump, a saturator, an ammonium sulfate mother liquor heater or coal gas preheater, and an auxiliary heater. The mother liquor circulation pump is connected to the saturator, the output port of the ammonium sulfate mother liquor heater or coal gas preheater is connected to the inlet of the auxiliary heater, and the output port of the auxiliary heater is connected to the inlet of the saturator. The shell-side inlet of the ammonium sulfate mother liquor heater or coal gas preheater is connected to the fractionator, the shell-side output port F of the ammonium sulfate mother liquor heater or coal gas preheater is connected to the inlet of the condenser cooler, and the condenser cooler output port is connected to the desulfurization system. The fractionator is placed at the top of the ammonia still tower. When the shell-side inlet of the ammonium sulfate mother liquor heater is connected to the fractionator, the suction port of the mother liquor circulation pump is connected to the suction port of a heat recovery pump via a pipeline, and the output port of the heat recovery pump is connected to the inlet of the ammonium sulfate mother liquor heater.

[0007] Furthermore, the mother liquor circulation pump suction port is connected to the upper portion of the lower section (crystallization chamber) of the saturator, and the mother liquor circulation pump output port is respectively connected to the upper annular chamber, the middle side inlet and the bottom of the saturator.

[0008] Furthermore, the output port of the ammonium sulfate mother liquor heater is also connected to the inlet port of the saturator.

[0009] Furthermore, the auxiliary heater has a heat source of steam, and is used to adapt to the influence of factors such as the change of raw water treatment capacity of the steam tower and seasonal load on the heating load of the spray saturator.

[0010] Furthermore, the splitter is also connected to the condenser cooler inlet.

[0011] Furthermore, the inlet of the gas preheater is connected to the gas from the desulfurization process, and the output port of the gas preheater is connected to the inlet of the saturator.

[0012] Furthermore, the output port of the gas preheater can be connected to the inlet of the saturator across the auxiliary heater, and the inlet is located in the upper annular chamber of the saturator.

[0013] The coal gas from the desulfurization process enters the coal gas preheater (traditionally, live steam is used for preheating; this method uses ammonia from the fractionator). After preheating, it enters the saturator, where the acidic mother liquor spray absorbs the ammonia. The acid mist is then removed by the cyclone deacidifier built into the saturator before being sent to the final cooling and benzene washing process. At one coking plant, coal gas preheating and ammonium sulfate mother liquor heating are not used simultaneously.

[0014] The beneficial effects of the utility model are:

[0015] (1) The amount of waste heat recovered from the top of the ammonia distillation tower is large. After passing through the ammonia and water vapor two-phase flow, a large amount of heat is entrained. In current production, all of this heat is usually condensed by a condenser cooler. In the present utility model technology, a feasible heat exchange network is established, and the above waste heat can be used to heat low-grade users such as ammonium sulfate mother liquor using the present utility model technology, and the consumption of cooling water in the condenser cooler and the ammonia distillation tower top condenser is reduced.

[0016] (2) Through the designed process, the mixed fluid of ammonia and water vapor discharged from the top reducer of the ammonia distillation tower is used as a heat carrier and enters the shell side of the ammonium sulfate mother liquor heater. After releasing heat, it relies on the residual pressure to enter the condenser cooler usually provided in the process flow. It does not require cooling water or power consumption. After cooling, it enters the desulfurization system through the pipeline.

[0017] (3) An auxiliary heater is set up. After passing through the ammonium sulfate mother liquor heater, the ammonium sulfate mother liquor enters the auxiliary heater of the ammonium sulfate mother liquor in series to adapt to the changes in the raw water treatment capacity of the ammonia distillation tower and the seasonal load in different seasons, and to ensure that the ammonium sulfate mother liquor in the saturator reaches the set temperature.

[0018] (4) The present invention can be equipped with a heat recovery pump separately. When the mother liquor circulation pump has sufficient head, the mother liquor pump can be used to achieve both mother liquor circulation and stirring of the mother liquor in the saturator.

[0019] (5) The utility model uses the waste heat of ammonia gas and water vapor discharged from the ammonia tower decondenser as the main heat source to preheat the coal gas or heat the mother liquor, which can achieve the temperature control of the mother liquor of the spray saturator within the set range of 50℃~60℃. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a flow chart of the waste heat recovery system at the top of the ammonia distillation tower and the ammonium sulfate mother liquor heat exchange system of the utility model;

[0021] Figure 2 This is a flow chart of the waste heat recovery and gas preheating heat exchange system at the top of the ammonia distillation tower of the utility model;

[0022] List of Figure Symbols:

[0023] Mother liquor circulation pumps P-102A, P-102B; saturators T-102A, T-102B; heat recovery pumps P-101A, P-101B; mother liquor circulation pumps P-102A, P-102B; ammonium sulfate mother liquor heater W-103; auxiliary heater W-104; fractionator W-101A, W-101B; condenser cooler W-102; ammonia distillation towers T-101A, T-101B; gas preheater W-105. DETAILED DESCRIPTION

[0024] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention. Example 1

[0025] like Figure 1 As shown, a network for recovering waste heat from the top of an ammonia still and exchanging heat with an ammonium sulfate mother liquor is provided, comprising an ammonia still T-101A, T-101B, a fractionator W-101A, W-101B, a condenser cooler W-102, a mother liquor circulation pump P-102A, P-102B, a heat recovery pump P-101A, P-101B, a saturator T-102A, T-102B, an ammonium sulfate mother liquor heater W-103 and an auxiliary heater W-104; the mother liquor circulation pump P-102A, P-102B is connected to the saturator T-102A, T-102B, the suction port of the heat recovery pump P-101A, P-101B is connected to the suction port A1, A2 of the mother liquor circulation pump P-102A, P-102B through a pipeline, and the heat recovery pump P-101A, P-101B is connected to the suction port A1, A2 of the mother liquor circulation pump P-102A, P-102B through a pipeline. The output ports of pumps P-101A and P-101B are connected to the inlet B of the ammonium sulfate mother liquor heater W-103, the output port of the ammonium sulfate mother liquor heater W-103 is connected to the inlet C of the auxiliary heater W-104, and the output port D of the auxiliary heater W-104 is connected to the inlets E1 and E2 of the saturators T-102A and T-102B; the shell-side inlet of the ammonium sulfate mother liquor heater W-103 is connected to the expanders W-101A and W-101B, the shell-side output port F of the ammonium sulfate mother liquor heater W-103 is connected to the inlet G of the condenser cooler W-102, the output port of the condenser cooler W-102 is connected to the desulfurization system, and the expanders W-101A and W-101B are placed on the top of the ammonia distillation towers T-101A and T-101B.

[0026] As a specific embodiment of the present invention, the suction ports A1 and A2 of the mother liquor circulation pumps P-102A and P-102B are connected to the lower part of the saturators T-102A and T-102B, and the output ports of the mother liquor circulation pumps P-102A and P-102B are connected to the upper part and the bottom part of the saturators T-102A and T-102B, respectively.

[0027] As a specific embodiment of the present invention, the output port of the ammonium sulfate mother liquor heater W-103 is also connected to the inlets E1 and E2 of the saturators T-102A and T-102B.

[0028] As a specific embodiment of the present invention, the heat source of the auxiliary heater W-104 is steam.

[0029] As a specific embodiment of the present invention, the splitters W-101A and W-101B are also connected to the inlet G of the condenser cooler W-102. Example 2

[0030] like Figure 2 As shown, a network for recovering waste heat from the top of an ammonia still and exchanging heat with ammonium sulfate mother liquor is provided, including ammonia still towers T-101A and T-101B, fractionators W-101A and W-101B, condenser cooler W-102, mother liquor circulation pumps P-102A and P-102B, saturators T-102A and T-102B, gas preheater W-105 and auxiliary heater W-104; mother liquor circulation pumps P-102A and P-102B are connected to saturators T-102A and T-102B, and the output port of gas preheater W-105 is connected to auxiliary heater W-104; The inlet C of the auxiliary heater W-104 and the output D of the auxiliary heater W-104 are connected to the inlets E1 and E2 of the saturators T-102A and T-102B; the shell-side inlet of the gas preheater W-105 is connected to the expanders W-101A and W-101B, the shell-side output F of the gas preheater W-105 is connected to the inlet G of the condenser cooler W-102, and the output of the condenser cooler W-102 is connected to the desulfurization system. The expanders W-101A and W-101B are placed on the top of the ammonia distillation towers T-101A and T-101B.

[0031] As a specific embodiment of the present invention, the suction ports A1 and A2 of the mother liquor circulation pumps P-102A and P-102B are connected to the lower part of the saturators T-102A and T-102B, and the output ports of the mother liquor circulation pumps P-102A and P-102B are connected to the upper part and the bottom part of the saturators T-102A and T-102B, respectively.

[0032] In one embodiment of the present invention, the inlet of gas preheater W-105 is connected to the gas from the desulfurization process, and the outlet of gas preheater W-105 is also connected to inlets E1 and E2 of saturators T-102A and T-102B. In another embodiment of the present invention, the heat source of auxiliary heater W-104 is steam.

[0033] As a specific embodiment of the present invention, the splitters W-101A and W-101B are also connected to the inlet G of the condenser cooler W-102.

[0034] Working principle:

[0035] Heat recovery pumps P-101A and P-101B are set up and connected to the suction ports A1 and A2 of the mother liquor circulation pumps P-102A and P-102B respectively through pipelines to pump the ammonium sulfate mother liquor into the interface B of the specially designed circulating mother liquor heat exchanger group W-103 to recover and utilize the waste heat from the discharge pipe of the ammonia distillation tower top expander. The released heat is used to heat the ammonium sulfate mother liquor. After the temperature is raised, the ammonium sulfate mother liquor enters the interface C of the auxiliary heater W-104 and is discharged from the outlet D to the interfaces E1 and E2 of the saturators T-102A and T-102B respectively and enter the saturators T-102A and T-102B (or the output port of the ammonium sulfate mother liquor heater W-103 is directly connected to the interfaces E1 and E2 of the saturators T-102A and T-102B and enters the saturators T-102A and T-102B).

[0036] After the steam and water vapor mixed fluid discharged from the fractionator releases heat, it is discharged from the shell side of the specially designed mother liquid heater through the outlet F to the interface G of the commonly installed condenser cooler W-102 by relying on the residual pressure, and then discharged from the outlet H to the desulfurization system.

[0037] The inlet of the gas preheater W-105 is connected to the gas from the desulfurization process, and the waste heat from the discharge pipe of the ammonia distillation tower top reducer is recovered and utilized. The heated gas enters the interface C of the auxiliary heater W-104 through the output port of the gas preheater W-105, and is discharged from the outlet D to the interfaces E1 and E2 of the saturators T-102A and T-102B respectively (or the output port of the gas preheater W-105 is directly connected to the interfaces E1 and E2 of the upper annular chamber (divided into two streams) of the saturators T-102A and T-102B, and enters the saturators T-102A and T-102B). After the ammonia in the acidic mother liquor is sprayed and absorbed, the acid mist is separated by the built-in cyclone deacidifier of the saturator, and finally sent to the final cold benzene washing process.

[0038] It should be noted that the above content only illustrates the technical ideas of the present utility model and cannot be used to limit the protection scope of the present utility model. Several improvements and modifications can be made to this technology without departing from the principles of the present utility model. These improvements and modifications are all within the protection scope of the claims of the present utility model.

Claims

1. A system for recovering waste heat from the top of an ammonia distillation tower and exchanging heat with ammonium sulfate mother liquor or preheating gas, characterized in that: It includes an ammonia still, a fractionator, a condenser cooler, a mother liquor circulation pump, a saturator, an ammonium sulfate mother liquor heater or a gas preheater and an auxiliary heater; the mother liquor circulation pump is connected to the saturator, the output port of the ammonium sulfate mother liquor heater or the gas preheater is connected to the inlet of the auxiliary heater, and the output port of the auxiliary heater is connected to the inlet of the saturator; the shell-side inlet of the ammonium sulfate mother liquor heater or the gas preheater is connected to the fractionator, the shell-side output port of the ammonium sulfate mother liquor heater or the gas preheater is connected to the inlet of the condenser cooler, the output port of the condenser cooler is connected to the desulfurization system, and the fractionator is placed on the top of the ammonia still; when the shell-side inlet of the ammonium sulfate mother liquor heater is connected to the fractionator, the suction port of the mother liquor circulation pump is connected to the suction port of the heat recovery pump through a pipeline, and the output port of the heat recovery pump is connected to the inlet of the ammonium sulfate mother liquor heater.

2. The system for recovering waste heat from the top of an ammonia distillation tower and exchanging heat with ammonium sulfate mother liquor or preheating gas according to claim 1, characterized in that: The mother liquid circulation pump suction port is connected to the upper part of the lower section of the saturator, and the mother liquid circulation pump output port is respectively connected to the upper annular chamber, the middle side inlet and the bottom of the saturator.

3. The system for recovering waste heat from the top of an ammonia distillation tower and exchanging heat for ammonium sulfate mother liquor or preheating gas according to claim 1, characterized in that: The output port of the ammonium sulfate mother liquor heater can be connected to the inlet port of the saturator across the auxiliary heater.

4. The system for recovering waste heat from the top of an ammonia distillation tower and exchanging heat for ammonium sulfate mother liquor or preheating gas according to claim 1, characterized in that: The heat source of the auxiliary heater is steam.

5. The system for recovering waste heat from the top of an ammonia distillation tower and exchanging heat with ammonium sulfate mother liquor or preheating gas according to claim 1, characterized in that: The splitter is also connected to the condenser cooler inlet.

6. The system for recovering waste heat from the top of an ammonia distillation tower and exchanging heat for ammonium sulfate mother liquor or preheating gas according to claim 1, characterized in that: The inlet of the gas preheater is connected to the gas from the desulfurization process, and the output port of the gas preheater is connected to the inlet of the saturator.

7. The system for recovering waste heat from the top of an ammonia distillation tower and exchanging heat for ammonium sulfate mother liquor or preheating gas according to claim 1, characterized in that: The output of the gas preheater can be connected to the inlet of the saturator across the auxiliary heater.

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