A system for generating power using low pressure steam waste heat

Abstract

The utility model relates to a system of utilizing low pressure steam waste heat power generation belongs to the technical field of coal chemical industry. The system includes the independent setting working medium circulating system and heating system, its characterized in that, the working medium circulating system includes preheater, preheater communicates with evaporator, evaporator communicates with turbine, turbine is connected with ORC generator set through the shaft coupling, turbine communicates with preheater through working medium pump, the heating system includes high pressure deaerator and medium pressure deaerator, the exhaust pipe of high pressure deaerator communicates with the heating medium inlet of evaporator, the exhaust pipe of medium pressure deaerator communicates with the heating medium inlet of preheater, the heating medium outlet of evaporator and the heating medium outlet of preheater all communicate with the steam recovery tank. The utility model discloses through reasonable setting, eliminates high pressure deaerator and medium pressure deaerator direct to the air discharge, realizes the reuse of waste heat, reduces the heat loss.

Description

Technical Field

[0001] This utility model relates to the technical field of coal chemical industry, specifically to a system for generating electricity using waste heat from low-pressure steam. Background Technology

[0002] Thermal deaerators are the most common devices in power plant boilers. They are hybrid heaters that operate on the principle of thermal deaeration, removing dissolved gases from feedwater, storing a certain amount of feedwater to alleviate the imbalance between condensate and feedwater flow, and using the extracted steam from the regenerative cycle to heat the boiler feedwater, thus improving the thermal efficiency of the power plant units. Based on operating pressure, thermal deaerators are further divided into high-pressure deaerators and medium-pressure deaerators. High-pressure deaerators operate at 0.2~0.24 MPa and 130~135 ℃, with demineralized water as the inlet and the outlet water supplying the boiler. Medium-pressure deaerators operate at 0.1~0.15 MPa and 110~115 ℃, primarily recovering steam condensate from various workshops. After heating and deaeration, the steam condensate supplies water to the medium and low-pressure waste boilers in the shift conversion process. Both the high-pressure deaerator and the medium-pressure deaerator are supplied with 0.35 MPa saturated steam to heat the demineralized water and steam condensate to above the saturation temperature under the working pressure of the deaerator. After oxygen is released from the water, it is discharged from the exhaust ports at the top of the two deaerators, thus achieving the purpose of deoxygenation.

[0003] The existing high-pressure deaerator in the workshop has three exhaust ports on its cylinder, connected to one DN100 and two DN150 exhaust pipes. The DN100 pipe is normally open, and one of the DN150 pipes is opened when the deaerator starts, while the other is a backup exhaust pipe. All three exhaust pipes discharge exhaust steam at a pressure of 0.20 MPa and a temperature of 132 ℃, with a total discharge capacity of approximately 8 tons / hour. The medium-pressure deaerator has one exhaust port on its top, connected to a DN100 exhaust pipe that is normally open, discharging exhaust steam at a pressure of 0.10 MPa and a temperature of 110 ℃, with a total discharge capacity of approximately 10 tons / hour. In actual production, the exhaust steam from both deaerators is directly discharged into the atmosphere, which is detrimental to creating a leak-free factory and also results in heat waste and energy carbon loss. How to rationally utilize the exhaust steam generated by the high-pressure and medium-pressure deaerators is an urgent problem to be solved at this stage. Utility Model Content

[0004] To address the problem of the inefficient use of exhaust steam generated by high-pressure and medium-pressure deaerators, this invention provides a system for generating electricity using waste heat from low-pressure steam, thus solving the aforementioned problem.

[0005] The technical solution of this utility model is as follows:

[0006] A system for generating electricity using waste heat from low-pressure steam includes an independently configured working fluid circulation system and a heating system; the working fluid circulation system includes a preheater; the preheater is connected to an evaporator; the evaporator is connected to a turbine; the turbine is connected to an ORC generator set via a coupling; the turbine is connected to the preheater via a working fluid pump.

[0007] The heating system includes a high-pressure deaerator and a medium-pressure deaerator; the exhaust pipe of the high-pressure deaerator is connected to the heating medium inlet of the evaporator; the exhaust pipe of the medium-pressure deaerator is connected to the heating medium inlet of the preheater; the heating medium outlet of the evaporator and the heating medium outlet of the preheater are both connected to the exhaust steam recovery tank.

[0008] Furthermore, the waste steam recovery tank is connected to the medium-pressure deaerator via a condensate pump, which is used to transfer the recovered condensate to the medium-pressure deaerator, where it can be reused after deaeration.

[0009] Furthermore, the exhaust pipe of the high-pressure deaerator is directly connected to the waste steam recovery tank. When the steam pressure discharged from the high-pressure deaerator is too low to heat the working fluid in the evaporator to the specified minimum temperature, the low-pressure steam can be directly discharged into the waste steam recovery tank for recovery, thus avoiding steam waste.

[0010] Furthermore, a condenser is provided between the turbine and the working fluid pump; the condenser cools the working fluid through circulating water, and the condenser has circulating water inlet and outlet pipes. Some of the steam exiting the turbine will not be liquefied, and transferring the working fluid back to the preheater requires the use of a working fluid pump. Working fluid pumps are typically fluid transport devices; if the working fluid is not completely condensed and still contains some steam, the working fluid passing through the pump will cause unstable operating pressure. By installing a condenser to completely liquefy the working fluid, the aforementioned problem is avoided.

[0011] Furthermore, the waste steam recovery tank is equipped with a water replenishment pipe, which can replenish water in a timely manner when the water supply is insufficient, ensuring the stable operation of the heating system.

[0012] Furthermore, the exhaust pipe of the high-pressure deaerator is equipped with a vent valve; the vent valve is interlocked with the ORC generator set. If the ORC generator set trips due to a fault, the vent valve will automatically open to ensure safe operation.

[0013] Furthermore, the exhaust pipe of the medium-pressure deaerator is equipped with a second vent valve; the second vent valve is interlocked with the ORC generator set.

[0014] Furthermore, the waste steam recovery tank is equipped with a vent valve.

[0015] The working principle of this invention is as follows: During equipment operation, steam discharged from the high-pressure deaerator directly enters the evaporator to heat the working fluid passing through the evaporator, while steam discharged from the medium-pressure deaerator directly enters the preheater to preheat the working fluid passing through the preheater. The working fluid in the working fluid circulation system is preheated in the preheater, then vaporized in the evaporator, driving the turbine to rotate. The turbine, through a coupling, drives the ORC generator set, converting thermal energy into mechanical energy and then into electrical energy. After passing through the turbine, the steam liquefies and is transferred to the preheater for preheating via a working fluid pump, then the cycle repeats. Since the steam temperature discharged from the high-pressure deaerator is higher than that from the medium-pressure deaerator, the steam discharged from the high-pressure deaerator is used to heat the working fluid in the evaporator. The steam heated by the preheater and evaporator is liquefied and collected in the waste steam recovery tank. Because the liquefied steam contains almost no ions, it can be re-pumped into the medium-pressure deaerator for deoxygenation and then used as working water.

[0016] The beneficial effects of this utility model are as follows:

[0017] This invention provides a system for generating electricity using waste heat from low-pressure steam. Through reasonable design, it eliminates the direct discharge of waste heat from the high-pressure and medium-pressure deaerators into the air, thereby enabling the reuse of waste heat and reducing heat loss.

[0018] Calculations show that after the system is in normal operation, it will increase the power generation by 240kW per hour. Based on an annual operating time of 8,000 hours and an electricity price of 0.67 yuan / kW / hour, the annual increase in power generation benefits is 240kW × 8,000 hours × 0.67 yuan / kW / hour = 1,286,400 yuan.

[0019] The demineralized water formed by condensing the exhaust steam from the high-pressure and medium-pressure deaerators can be recovered. Based on an annual operating time of 8,000 hours, a demineralized water price of 6.8 yuan / ton, and exhaust steam discharge rates of 8 tons / hour for the high-pressure deaerator and 10 tons / hour for the medium-pressure deaerator, the production cost savings from condensing and recovering all the exhaust steam would be 6.8 yuan / ton × 8,000 hours × (8 + 10) tons / hour = 979,200 yuan.

[0020] The total power of the condensate pump and working fluid pump in the waste heat power generation system is 27.5 + 5.5 = 33 kW, and the annual electricity cost is 33 kW × 8000 hours × 0.67 yuan / kW-hour = 176,900 yuan.

[0021] Equipment depreciation expense (equipment investment / 14 years): 4.268 million yuan / 14 years ≈ 304,900 yuan / year

[0022] In summary, the system for generating electricity using waste heat from low-pressure steam provided by this utility model increases annual economic benefits by RMB 1,286,400 + RMB 979,200 - RMB 304,900 - RMB 176,900 = RMB 1,783,900. Attached Figure Description

[0023] To more clearly illustrate the technical solution of this utility model, the drawings used in the description will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the system structure of Embodiment 2 of this utility model.

[0025] In the diagram, 1-high pressure deaerator, 2-medium pressure deaerator, 3-evaporator, 4-turbine, 5-condenser, 6-preheater, 7-condensate pump, 8-working fluid pump, 9-waste steam recovery tank, 10-ORC generator set, 11-vent valve one, 12-vent valve two, 13-vent valve three. Detailed Implementation

[0026] To make the objectives, features, and advantages of this utility model more apparent and understandable, the technical solutions of this utility model will be clearly and completely described below with reference to the accompanying drawings of the specific embodiments. Obviously, the embodiments described below are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this patent, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this patent.

[0027] Example 1

[0028] A system for generating electricity using waste heat from low-pressure steam includes an independently configured working fluid circulation system and a heating system. The working fluid circulation system includes a preheater 6, which is connected to an evaporator 3. The evaporator 3 is connected to a turbine 4. The turbine 4 is connected to an ORC generator set 10 via a coupling. The turbine 4 is connected to the preheater 6 via a working fluid pump 8. The heating system includes a high-pressure deaerator 1 and a medium-pressure deaerator 2. The exhaust pipe of the high-pressure deaerator 1 is connected to the heating medium inlet of the evaporator 3. The exhaust pipe of the medium-pressure deaerator 2 is connected to the heating medium inlet of the preheater 6. The heating medium outlets of the evaporator 3 and the preheater 6 are both connected to a waste steam recovery tank 9.

[0029] Example 2

[0030] A system for generating electricity using waste heat from low-pressure steam includes an independently configured working fluid circulation system and a heating system. The working fluid circulation system includes a preheater 6, which is connected to an evaporator 3. The evaporator 3 is connected to a turbine 4. The turbine 4 is connected to an ORC generator set 10 via a coupling. The turbine 4 is connected to the preheater 6 via a working fluid pump 8. A condenser 5 is installed between the turbine 4 and the working fluid pump 8. The condenser 5 cools the working fluid using circulating water. The condenser 5 has a circulating water inlet pipe and a circulating water outlet pipe. The heating system includes a high-pressure deaerator 1 and a medium-pressure deaerator 2. The exhaust pipe of the high-pressure deaerator 1 is connected to the heating medium inlet of the evaporator 3. The exhaust pipe of the medium-pressure deaerator 2 is connected to the heating medium inlet of the preheater 6; the heating medium outlet of the evaporator 3 and the heating medium outlet of the preheater 6 are both connected to the waste steam recovery tank 9; the waste steam recovery tank 9 is connected to the medium-pressure deaerator 2 through the condensate pump 7; the waste steam recovery tank 9 is equipped with a water supply pipe; the exhaust pipe of the high-pressure deaerator 1 is directly connected to the waste steam recovery tank 9; the exhaust pipe of the high-pressure deaerator 1 is equipped with a vent valve 11; the vent valve 11 is interlocked with the ORC generator set; the exhaust pipe of the medium-pressure deaerator 2 is equipped with a vent valve 12; the vent valve 12 is interlocked with the ORC generator set 10; the waste steam recovery tank 9 is equipped with a vent valve 13.

[0031] The above description of the disclosed embodiments enables those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A system for generating electricity using waste heat from low-pressure steam, comprising an independently configured working fluid circulation system and a heating system; characterized in that, The working fluid circulation system includes a preheater; the preheater is connected to an evaporator; the evaporator is connected to a turbine; the turbine is connected to an ORC generator set via a coupling; the turbine is connected to the preheater via a working fluid pump; the heating system includes a high-pressure deaerator and a medium-pressure deaerator; the exhaust pipe of the high-pressure deaerator is connected to the heating medium inlet of the evaporator; the exhaust pipe of the medium-pressure deaerator is connected to the heating medium inlet of the preheater; the heating medium outlet of the evaporator and the heating medium outlet of the preheater are both connected to a waste steam recovery tank.

2. The system for generating electricity using low-pressure steam waste heat as described in claim 1, characterized in that, The waste steam recovery tank is connected to the medium-pressure deaerator via a condensate pump.

3. A system for generating electricity using low-pressure steam waste heat as described in claim 1, characterized in that, The exhaust pipe of the high-pressure deaerator is also directly connected to the waste steam recovery tank.

4. A system for generating electricity using low-pressure steam waste heat as described in claim 1, characterized in that, A condenser is provided between the turbine and the working fluid pump; the condenser cools the working fluid through circulating water, and the condenser is provided with a circulating water inlet pipe and a circulating water outlet pipe.

5. A system for generating electricity using low-pressure steam waste heat as described in claim 1, characterized in that, The waste steam recovery tank is equipped with a water replenishment pipeline.

6. A system for generating electricity using low-pressure steam waste heat as described in claim 1, characterized in that, The exhaust pipe of the high-pressure deaerator is equipped with a vent valve; the vent valve is interlocked with the ORC generator set.

7. A system for generating electricity using low-pressure steam waste heat as described in claim 1, characterized in that, The exhaust pipe of the medium-pressure deaerator is equipped with a second vent valve; the second vent valve is interlocked with the ORC generator set.

8. A system for generating electricity using low-pressure steam waste heat as described in claim 1, characterized in that, The waste steam recovery tank is equipped with a vent valve.

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