CN203307083U - A negative pressure ammonia distillation equipment using the waste heat of raw coal gas as a heat source - Google Patents

Abstract

A negative pressure ammonia distillation device using waste heat of raw gas as a heat source comprises an ammonia distillation tower, a reboiler, a wastewater cooler, a dephlegmator, an ammonia condensation cooler, a separator, a vacuum pump or an ejector, an ammonia distillation wastewater pump, a wastewater circulating pump and a connecting pipeline, wherein an alkali liquor inlet is arranged in the middle of the ammonia distillation tower, a circulating ammonia distillation wastewater outlet, an ammonia distillation wastewater outlet and a circulating ammonia distillation wastewater inlet are arranged at the bottom of the ammonia distillation tower, the top of the ammonia distillation tower is connected with the dephlegmator, the ammonia condensation cooler, the separator and the vacuum pump or the ejector through pipelines, and the vacuum pump or the ejector is connected with an external conveying device through a pipeline; the bottom of the ammonia still is connected with the ammonia still wastewater pump and the wastewater cooler through pipelines. Has the advantages of low equipment investment, low running cost, energy conservation, good index of ammonia distillation wastewater and the like.

Description

A negative pressure ammonia distillation equipment using the waste heat of raw coal gas as a heat source

technical field

The utility model relates to a device for steaming ammonia under negative pressure using waste heat of raw coal gas as a heat source in the recycling technology of coking chemical products.

Background technique

At present, there are two processes for residual ammonia distillation in the coking industry: positive pressure ammonia distillation and negative pressure ammonia distillation.

The positive pressure ammonia distillation process mainly includes: ① direct ammonia distillation method using steam as heat source; ② indirect ammonia distillation method using gas, steam, heat transfer oil, etc. as heat source. This type of process is operated at a high temperature of 90-110 ° C. Due to the strong corrosion of ammonia, hydrogen sulfide and other media, it results in high equipment investment and high maintenance costs. In addition, positive pressure ammonia distillation requires the consumption of primary energy (such as steam, coke oven gas, etc.), and the consumption is relatively large. The remaining ammonia water per ton consumes about 150-200kg of steam, and the operating cost is high.

Compared with positive pressure ammonia distillation, the advantage of negative pressure ammonia distillation is that vacuum distillation is adopted, the operating temperature is lowered, the medium is less corrosive, and the requirements for equipment materials are greatly reduced. Since it is operated at a lower temperature, some waste heat can be used by the heat source required for ammonia distillation to reduce energy consumption.

The temperature of the raw gas after the coke oven gas gas-liquid separator in the coking plant can be around 80°C. Usually, the circulating water and low-temperature water section are used to cool it to a certain temperature, and after preliminary purification, it is sent to the next process under pressure. In this process, the heat of the gas is not effectively utilized, and a large amount of cooling water needs to be consumed. Therefore, the effective recovery and utilization of waste heat from raw gas is of great significance for energy saving and emission reduction in the coking industry.

The current negative pressure ammonia distillation process mainly includes: ① Negative pressure ammonia distillation method heated by tube furnace (CN102336415A), ② Negative pressure ammonia distillation method using waste heat of flue gas (CN102602960A), ③ CN102351265A, ④ CN101259967A.

CN102336415A Negative-pressure ammonia distillation method with tubular furnace heating. Although this process can save a certain amount of energy compared with the positive-pressure ammonia distillation process, it still needs to consume primary energy and fails to utilize waste heat.

CN102602960A utilizes flue gas waste heat and negative pressure ammonia distillation method. This process utilizes coke oven flue gas waste heat (high-quality waste heat), high operating temperature, high investment and operating costs, and fails to utilize raw coal gas waste heat (low-quality waste heat). waste heat).

CN102351265A discloses a negative pressure ammonia distillation process and device for residual ammonia water produced by coking. The method uses desulfurization liquid to spray and suck ammonia vapor. Since the ammonia vapor is not cooled after the splitter, the flow rate is large, and the flow rate of the sprayed desulfurization liquid is large. , high equipment investment and operating costs. At the same time, a large amount of water in the ammonia vapor enters the desulfurization system, causing water imbalance in the desulfurization system, increasing the desulfurization waste liquid, and finally returning to the ammonia distillation system, resulting in increased ammonia distillation load and low ammonia distillation efficiency.

CN101259967A discloses a processing technology for residual ammonia water in the coking industry. After adding a small amount of sodium hydroxide to the residual ammonia water, the heat exchanger exchanges heat with waste water, and enters the ammonia distillation tower decompressed by a vacuum pump. The ammonia in the remaining ammonia water is volatilized, and after the ammonia vapor is cooled, it is transported to the next process by a vacuum pump under pressure. In this method, sodium hydroxide solution is directly added to the remaining ammonia water, and hydrogen cyanide in the remaining ammonia water reacts with sodium hydroxide to form a stable cyanide salt, which is difficult to distill, resulting in high cyanide content in the ammonia distillation wastewater, which seriously affects the subsequent biochemical sewage treatment. , eventually leading to the discharge of sewage that cannot meet the national environmental protection requirements. In addition, this method sends the condensed water into the mother liquor of the ammonium sulfate process for reuse. Practice has proved that this will cause the ammonium sulfate mother liquor to change color and affect the quality of ammonium sulfate.

To sum up, there are deficiencies in the current negative pressure ammonia distillation process in terms of waste heat utilization, ammonia distillation efficiency, ammonia distillation wastewater indicators, etc., which need to be resolved urgently.

Utility model content

The purpose of the utility model is to provide a negative pressure ammonia steaming equipment with low equipment investment, low operating cost, energy saving, good ammonia steam waste water index, and utilization of raw gas waste heat as a heat source.

In order to achieve the above object, the utility model is realized through the following technical solutions:

A negative pressure ammonia distillation equipment using the waste heat of raw coal gas as a heat source, including an ammonia distillation tower, a reboiler, a waste water cooler, a shrinker, an ammonia condensation cooler, a separator, a vacuum pump or ejector, an ammonia distillation waste water pump, Wastewater circulation pump and connecting pipelines, the middle part of the ammonia distillation tower is provided with a lye inlet, the bottom of the ammonia distillation tower is provided with a circulating ammonia distillation wastewater outlet, an ammonia distillation wastewater outlet and a circulation ammonia distillation wastewater inlet, and the top of the ammonia distillation tower passes through The pipes are connected to the shrinker, ammonia condensing cooler, separator and vacuum pump or ejector, and the vacuum pump or ejector is connected to the delivery device through pipes; the bottom of the ammonia distillation tower is connected to the waste water circulation pump and reboiler through pipes, and the distillation The bottom of the ammonia tower is also connected to the ammonia distilling wastewater pump and the wastewater cooler through pipelines, and the wastewater cooler is connected to the external delivery device through pipelines.

The ammonia distillation tower is provided with a broken tray, and the broken tray is located above the alkali addition position to cut off the rise of the vapor phase in the lower part; The ammonia vapor generated after the distillation of ammonia water below the tray is introduced into the ammonia distillation tower above the broken tray; the upper and lower parts of the broken tray of the ammonia distillation tower are provided with liquid-phase communication pipes, and the liquid-phase communication pipes can be arranged in the ammonia distillation tower , or outside the ammonia distillation tower, divert the ammonia water from the upper part of the ammonia distillation tower to the lower part to continue distillation.

The ammonia distillation tower can also be without a broken tray, and the ammonia distillation tower without a broken tray is a packed tower or a plate tower that meets the technological requirements of the utility model.

Compared with the prior art, the equipment of the utility model has significant advantages such as low equipment investment, low operating cost, energy saving, and good indicators of ammonia distilled wastewater. The specific features are:

1) Low investment in equipment: the utility model is operated under negative pressure, the operating temperature of the equipment is low, the corrosion performance of the medium is reduced, the requirements for the material of the equipment are reduced, and the investment in the equipment is reduced.

2) Low operating cost and energy saving: the waste heat of raw gas is used as the heat source for steaming ammonia, no other external energy is needed, and the waste heat of raw gas is turned into treasure, which saves a lot of energy; at the same time, it reduces the circulating water and water used to cool the waste heat of raw gas The consumption of low-temperature water reduces its operating cost, which kills two birds with one stone and has obvious advantages.

3) Ammonia distillation wastewater has good indicators: it has high efficiency of ammonia distillation and decyanation. Appropriate alkali addition position ensures the indicators such as ammonia nitrogen and cyanide ions in the ammonia distillation wastewater.

Description of drawings

Fig. 1 is the overall structure diagram of the utility model.

Fig. 2 is a structural schematic diagram of the ammonia distillation tower with a broken tray (built-in liquid phase communication pipe) of the utility model.

Fig. 3 is a structural schematic diagram of an ammonia distillation tower with a broken tray (external liquid phase communication pipe) of the present invention.

Fig. 4 is a structural schematic diagram of an ammonia distillation tower without a broken tray of the present invention.

Detailed ways

The specific embodiment of the utility model is described in detail below in conjunction with accompanying drawing.

As shown in Figure 1, the equipment required for the negative pressure ammonia distillation process using the waste heat of raw coal gas as the heat source includes ammonia distillation tower 1, reboiler 2, waste water cooler 3, shrinker 4, ammonia condensation cooler 5, and separator 6. Vacuum pump or injector 7, ammonia distillation waste water pump 8, waste water circulation pump 9 and connecting pipes, the middle part of the ammonia distillation tower is provided with a lye inlet 10, and the bottom of the ammonia distillation tower is provided with a circulating ammonia distillation waste water outlet 11, Ammonia distillation wastewater outlet 12 and circulating ammonia distillation wastewater inlet 13, the top of the ammonia distillation tower is connected to the splitter 4, ammonia condensation cooler 5, separator 6 and vacuum pump or ejector 7 through pipelines, and the vacuum pump or ejector 7 passes through pipelines Connected with the external delivery device; the bottom of the ammonia distillation tower is connected with the wastewater circulation pump 9 and the reboiler 2 through pipelines, and the bottom of the ammonia distillation tower is also connected with the ammonia distillation wastewater pump 8 and the wastewater cooler 3 through pipelines, and the wastewater cooler 3 Then connect to the delivery device through pipelines.

The ammonia distillation tower is divided into two forms with broken trays (Figure 2, Figure 3) and without broken trays (Figure 4). Ammonia distillation tower with a broken tray, the broken tray is located above the alkali addition position to cut off the vapor phase rise in the lower part; the upper part of the broken tray and the lower wall are provided with a gas-phase communication pipe 14, and the ammonia distillation tower is connected to the bottom of the broken tray. The ammonia vapor generated after the distillation of ammonia water is introduced into the ammonia distillation tower above the broken tray; the upper and lower parts of the broken tray of the ammonia distillation tower are provided with liquid-phase communication pipes, and the liquid-phase communication pipe 15 (shown in Figure 2) can be arranged at In the ammonia distillation tower, the liquid phase communication pipe 16 (shown in Figure 3) can also be arranged outside the ammonia distillation tower to divert the ammonia water from the upper part of the ammonia distillation tower to the lower part to continue distillation.

The working process of the utility model is as follows: as shown in Figure 1, the residual ammonia water of the raw material is directly poured into the upper part of the ammonia distillation tower 1, and distilled at a temperature of 55-70°C and a state of 15-35KPa (absolute pressure) to remove free ammonia. For ammonia and other impurities, a corresponding amount of lye is added to the lye inlet 10 in the middle of the ammonia distillation tower 1 to separate the fixed ammonia in the remaining ammonia water. Part of the ammonia distillation waste water at 55-70°C at the bottom of ammonia distillation tower 1 is drawn out by waste water circulation pump 9, and after heat exchange with 60-78°C heat medium that has absorbed the waste heat of raw gas through reboiler 2, it returns to ammonia distillation tower 1 as a distillation unit. Heat source of ammonia.

The ammonia vapor at 55-70°C from the top of the ammonia distillation tower 1 is cooled by the shrinker 4, and the liquid phase is used as reflux, and the vapor phase is cooled to 18-60°C by the ammonia condensation cooler 5, and the cooled vapor-liquid mixture enters the separator 6 Carry out gas-liquid separation, in which the non-condensable gas is pumped out by a vacuum pump or ejector 7 and sent to the ammonia absorption device or the gas precooling tower of the ammonia oxidation desulfurization device, and the separated ammonia water is sent to the desulfurization liquid of the ammonia oxidation desulfurization device system, or sent to the gas pre-cooling tower. The ammonia distillation waste water coming out from the bottom of the tower is taken out by the ammonia distillation waste water pump 8, and after being cooled by the waste water cooler 3, it is sent to the sewage treatment plant.

This equipment uses a vacuum pump or a liquid injector to suck the non-condensable gas after the ammonia condensing cooler, and sends it to the ammonia absorption device or the gas precooling tower of the ammonia oxidation desulfurization device; the ammonia water condensed after the ammonia condensing cooler is sent to the ammonia process Oxidation desulfurization device desulfurization liquid system, or sent to the gas pre-cooling tower. This method not only enables effective follow-up treatment of the ammonia distillation product, but also provides an ammonia source for the desulfurization device, maintains the balance of ammonia and water in the entire gas purification system, and ensures the normal operation of the entire gas purification system.

Claims (3)

1. one kind is utilized the negative pressure ammonia still process equipment of raw gas waste heat for thermal source, it is characterized in that, comprise ammonia still, reboiler, gaseous effluent cooler, dephlegmator, the ammonia condensing water cooler, separator, vacuum pump or injector, the distilled ammonia wastewater pump, waste water circulation pump and connecting tube, described ammonia still middle part is provided with alkali liquor inlet, at the bottom of the ammonia still tower, be provided with the outlet of circulation distilled ammonia wastewater, distilled ammonia wastewater outlet and circulation distilled ammonia wastewater entrance, the ammonia still tower top is via pipeline and dephlegmator, the ammonia condensing water cooler, separator is connected with vacuum pump or injector, vacuum pump or injector by pipeline with send device outside and be connected, at the bottom of the ammonia still tower, be connected with waste water circulation pump, reboiler via pipeline, also by pipeline, be connected with distilled ammonia wastewater pump, gaseous effluent cooler at the bottom of the ammonia still tower, gaseous effluent cooler again by pipeline with send device outside and be connected.

2. the negative pressure ammonia still process equipment of raw gas waste heat for thermal source that utilizes according to claim 1, is characterized in that, in described ammonia still, is provided with disconnected tower tray, and the disconnected tower tray risen in order to the vapour phase of blocking bottom is positioned at and adds top, alkali position; Disconnected tower tray top and bottom Ta Bi are provided with gas phase communicating pipe, and gas phase communicating pipe imports in the ammonia still of disconnected tower tray top for the ammonia vapour by generating after the ammonia distillation of the disconnected tower tray of ammonia still below; The disconnected tower tray top of described ammonia still and bottom are provided with liquid phase communicating pipe, and liquid phase communicating pipe can be arranged in ammonia still, or outside ammonia still, ammonia still top ammoniacal liquor water conservancy diversion, to bottom, are continued to distillation.

3. the negative pressure ammonia still process equipment of raw gas waste heat for thermal source that utilizes according to claim 1, is characterized in that, described ammonia still also can be with disconnected tower tray, and the ammonia still with disconnected tower tray form is not packing tower or tray column.

Images