Dead steam recycling system

Abstract

The utility model belongs to the technical field of dilute nitric acid production, and particularly relates to a dead steam recycling system which comprises a deaerator, a process make-up water pump and a desalting water tank, and further comprises a steam exhaust energy collector, and a water outlet of the process make-up water pump is connected with a liquid phase inlet of the steam exhaust energy collector through a pipeline. A liquid phase outlet of the exhaust steam energy collector is connected with a water inlet of the deaerator, a dead steam outlet of the deaerator is connected with a gas phase inlet of the exhaust steam energy collector through a pipeline, cooled dead steam is discharged and emptied through the gas phase outlet of the exhaust steam energy collector, condensate obtained in the dead steam cooling process is discharged through a condensate outlet of the exhaust steam energy collector, and the condensate is discharged through a water inlet of the deaerator. According to the deaerator, desalted water entering the deaerator is preheated, so that the consumption of low-pressure steam in the thermal deaeration process of the deaerator is reduced.

Description

Technical Field

[0001] The utility model belongs to the technical field of dilute nitric acid production, and in particular relates to a waste steam recovery and utilization system. Background Art

[0002] At present, the production of dilute nitric acid mainly adopts the double-pressure process. The steam condensation system and boiler system in this process are briefly introduced as follows:

[0003] After the desalted water enters the deaerator for thermal deoxygenation through the process supplementary water pump, it is preheated by the boiler feed water pump and sent to the steam drum after being preheated by the economizer. The boiler circulation booster pump circulates the boiler water between the steam drum and the waste heat boiler to generate saturated steam with a pressure of 4.0MpaG.

[0004] The saturated steam from the steam drum is superheated in the steam superheater after being cooled by water spray, and then defogged in the steam separator. Most of it is used to do work in the steam turbine, and the excess is output to the boundary area.

[0005] The exhaust steam from the steam turbine is collected in the hot water well through the steam condenser, pumped out by a condensate pump, cooled by the jet condenser, and then returned to the deaerator for recovery.

[0006] Deaerator is an important equipment in the double-pressurized dilute nitric acid process. The water after thermal deoxygenation can effectively avoid oxygen corrosion in the boiler system. The thermal deoxygenation of the deaerator mainly uses the heat of low-pressure steam to increase the temperature of the desalted water in the deaerator. As the temperature of the desalted water increases, the solubility of oxygen in the desalted water will decrease, which will accelerate the speed of oxygen entering the gas phase and be discharged into the atmosphere along with the steam exhaust steam, thereby achieving the purpose of removing oxygen from the boiler feed water. It plays a vital role in the safe and stable operation of the boiler system.

[0007] The dual-pressure dilute nitric acid process absorption system is briefly introduced as follows:

[0008] On the 32nd tray of the absorption tower, the process gas NO of the nitric acid unit X After being absorbed by water, it becomes qualified nitric acid. The process water required by the absorption tower is provided by the process water pump. During the start-up phase of the device, the unqualified acid produced is stored in the start-up acid tank and can be sent to the absorption tower for recovery through the start-up acid pump.

[0009] The double-pressure dilute nitric acid production process uses low-pressure steam to thermally deoxygenate the desalted water entering the deaerator, and the exhaust steam is directly discharged into the atmosphere through the flow-limiting orifice plate. In addition, the exhaust steam from the steam turbine cylinder of the device is also directly discharged into the atmosphere. The above exhaust steam direct discharge has adverse effects on production and environmental protection, and the main problems are:

[0010] Regardless of whether the nitric acid unit is on or off, the exhaust steam from the deaerator is always discharged directly into the atmosphere, which is not only a waste of low-pressure steam, but also does not meet the environmental protection requirements for "three-no-see" factories.

[0011] In summary, the existing production process cannot effectively recycle the direct exhaust steam generated by deaerators and other equipment, and does not meet environmental protection requirements. Utility Model Content

[0012] In view of the above problems, the utility model provides a waste steam recovery and utilization system.

[0013] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0014] A waste steam recovery and utilization system comprises a deaerator, a process feed water pump and a desalted water tank, and also comprises an exhaust steam energy receiver, wherein the water outlet of the process feed water pump is connected to the liquid phase inlet of the exhaust steam energy receiver through a pipeline, the liquid phase outlet of the exhaust steam energy receiver is connected to the water inlet of the deaerator, the waste steam outlet of the deaerator is connected to the gas phase inlet of the exhaust steam energy receiver through a pipeline, the waste steam that has been cooled is discharged and vented through the gas phase outlet of the exhaust steam energy receiver, the condensate obtained in the process of cooling the waste steam is discharged through the condensate outlet of the exhaust steam energy receiver, and the condensate outlet of the exhaust steam energy receiver is connected to the inlet of the desalted water tank through a pipeline.

[0015] Furthermore, the condensate outlet of the exhaust steam energy receiver is also connected to the inlet of the start-up acid tank through a pipeline.

[0016] Furthermore, it also includes a steam turbine cylinder exhaust steam pipe, the steam turbine cylinder exhaust steam pipe is connected to the inlet of the steam trap, and the gas outlet of the steam trap is connected to the gas phase inlet of the exhaust steam receiver through a pipeline.

[0017] Furthermore, pressure relief valves are installed at the exhaust steam outlet of the deaerator and the gas outlet of the steam trap to prevent excessive pressure in the exhaust steam receiver.

[0018] Compared with the prior art, the utility model has the following advantages:

[0019] The utility model reduces the consumption of low-pressure steam in the thermal deoxidation process of the deaerator by preheating the desalted water entering the deaerator, and the condensate generated by the exhaust steam cooling in the exhaust steam receiver is recovered to the desalted water tank or the start-up acid tank, thereby reducing the system's demand for desalted water; at the same time, the impact on environmental protection caused by the exhaust steam of the deaerator and the exhaust steam of the steam turbine cylinder body exhaust steam pipe being directly discharged into the atmosphere is eliminated;

[0020] The utility model has simple process and convenient operation. The utility model only adds one exhaust steam energy receiver, does not make major changes to the original system, does not need to add additional heat exchange medium, has low use cost, and is simple and convenient to maintain. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the structure of the utility model;

[0022] In the figure, there are deaerator 1, process feed water pump 2, exhaust steam receiver 3, desalted water tank 4, start-up acid tank 5, steam turbine cylinder exhaust steam pipe 6, steam trap 7, and pressure relief valve 8. DETAILED DESCRIPTION

[0023] In order to further illustrate the technical solution of the present invention, the present invention is further described below through embodiments.

[0024] like Figure 1 As shown, a waste steam recovery and utilization system includes a deaerator 1, a process feed water pump 2, a desalted water tank 4 and a steam turbine cylinder body exhaust steam guide pipe 6, and also includes an exhaust steam receiver 3, the steam turbine cylinder body exhaust steam guide pipe 6 is connected to the inlet of a steam trap 7, the water outlet of the process feed water pump 2 is connected to the liquid phase inlet of the exhaust steam receiver 3 through a pipeline, the liquid phase outlet of the exhaust steam receiver 3 is connected to the water inlet of the deaerator 1, the waste steam outlet of the deaerator 1 and the gas outlet of the steam trap 7 are connected to the gas phase inlet of the exhaust steam receiver 3 through a pipeline, the waste steam that has been cooled is discharged and vented through the gas phase outlet of the exhaust steam receiver 3, the condensate obtained during the waste steam cooling process is discharged through the condensate outlet of the exhaust steam receiver 3, and the condensate outlet of the exhaust steam receiver 3 is connected to the inlet of the desalted water tank 4 and the inlet of the start-up acid tank 5 through a pipeline.

[0025] Pressure relief valves 8 are installed at the exhaust steam outlet of the deaerator 1 and the gas outlet of the steam trap 7 to prevent excessive pressure in the exhaust steam receiver 3.

[0026] Specific working process: the exhaust steam directly discharged from the deaerator 1 and the steam turbine cylinder exhaust steam pipe 6 is connected through a pipeline and introduced into the exhaust steam receiver 2; the condensate produced by the exhaust steam receiver 2 is introduced into the desalted water tank 4 or the start-up acid tank 5 through a pipeline as supplementary desalted water for recycling in the closed-loop circulation system; the desalted water provided by the process supplementary water pump 4 is preheated by being incorporated into the exhaust steam receiver 2 through a pipeline, and then enters the deaerator 1 for thermal deoxidation.

[0027] The above shows and describes the main features and advantages of the utility model. For those skilled in the art, it is obvious that the utility model is not limited to the details of the above exemplary embodiments, and the utility model can be implemented in other specific forms without departing from the spirit or basic features of the utility model. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the utility model is limited by the attached claims rather than the above description, and it is intended to include all changes that fall within the meaning and scope of the equivalent elements of the claims in the utility model.

[0028] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A waste steam recovery system, comprising a deaerator (1), a process feed water pump (2) and a desalted water tank (4), characterized in that: The invention also comprises an exhaust steam energy collector (3), wherein the water outlet of the process supplementary water pump (2) is connected to the liquid phase inlet of the exhaust steam energy collector (3) through a pipeline, the liquid phase outlet of the exhaust steam energy collector (3) is connected to the water inlet of the deaerator (1), the exhaust steam outlet of the deaerator (1) is connected to the gas phase inlet of the exhaust steam energy collector (3) through a pipeline, the exhaust steam after cooling is discharged through the gas phase outlet of the exhaust steam energy collector (3), and the condensate obtained in the process of cooling the exhaust steam is discharged through the condensate outlet of the exhaust steam energy collector (3), and the condensate outlet of the exhaust steam energy collector (3) is connected to the inlet of the desalted water tank (4) through a pipeline.

2. The exhaust steam recovery system according to claim 1, characterized in that: The condensate outlet of the exhaust steam receiver (3) is also connected to the inlet of the start-up acid tank (5) through a pipeline.

3. The exhaust steam recovery system according to claim 1, characterized in that: It also comprises a steam turbine cylinder exhaust steam pipe (6), the steam turbine cylinder exhaust steam pipe (6) is connected to the inlet of a steam trap (7), and the gas outlet of the steam trap (7) is connected to the gas phase inlet of the exhaust steam receiver (3) through a pipeline.

4. The exhaust steam recovery system according to claim 1, characterized in that: Pressure relief valves (8) are installed at the exhaust steam outlet of the deaerator (1) and the gas outlet of the steam trap (7) to prevent excessive pressure in the exhaust steam receiver (3).

Images