Coking plant condensation water heat recovery system and method

Abstract

The invention relates to the technical field of energy recovery of coking plants, in particular to a coking plant condensation water heat recovery system and method. Comprising a condensed water feeding pipeline, an evaporator, a working medium storage tank, a heat engine, a condenser and a condensed water collector, the condensation water feeding pipeline is connected with a first inlet of the evaporator, a first outlet of the evaporator is connected with an inlet pipeline of the condensation water collector, and the condensation water collector is of a closed structure. An outlet of the working medium storage tank is connected with a second inlet pipeline of the evaporator, a second outlet of the evaporator is connected with an inlet pipeline of the heat engine, an outlet of the heat engine is connected with a first inlet pipeline of the condenser, and a first outlet of the condenser is connected with an inlet pipeline of the working medium storage tank. Heat contained in the high-temperature condensed water is efficiently recycled, the problem of evaporation loss of the condensed water in the evaporation process is fundamentally avoided, the manufacturing cost of heat utilization equipment is saved, and heat pollution is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of energy recovery in a coking plant, and in particular to a condensate heat recovery system and method for a coking plant. Background Art

[0002] Coking plants are key areas of steam and energy consumption within the industrial production system and are also a major contributor to carbon emissions. In traditional coking production processes, steam is used extensively as a key heating medium across all production processes. After completing its heating mission, steam condenses into condensate at approximately 85°C. This condensate is then transported through a pipeline network to a condensate recovery station. After rigorous testing and compliance with quality standards, it is then transported to desalted water stations, riser heat recovery water pump stations, or flue gas waste heat boiler rooms, achieving water recycling.

[0003] For steam heating users within coking plants, a subcooling section is typically installed on the heat-using equipment to ensure that the condensate delivered to the condensate recovery station remains within a safe and reasonable temperature range. However, this conventional technical approach inevitably increases the manufacturing cost of the heat-using equipment, thereby increasing the company's overall operating costs.

[0004] The key receiving equipment in the condensate recovery station is the condensate tank, which adopts an open structure design. In addition to the basic function of storing condensate, it is also specially equipped with a sampling device to test the water quality of the recovered condensate to ensure that it meets the various standard requirements for subsequent production use.

[0005] In recent years, with the continuous innovation and development of coking process technology, new steam users have been added to the chemical product recovery process, generating high-temperature condensate. This high-temperature condensate now accounts for a significant portion of the plant's total condensate output. The current technical solution is to transport this high-temperature condensate along with other conventional condensate through a pipeline network to a condensate tank for centralized treatment.

[0006] The above technical solution presents numerous challenges that need to be addressed. First, the influx of high-temperature condensate can easily lead to overheating in the pipes and condensate tanks, posing a serious threat to the safe and stable operation of the entire production system. Second, in the open-structured condensate tanks, a large amount of heat is lost through evaporation. This process also results in a significant loss of condensate, significantly reducing water recovery. Third, the steam generated during evaporation causes thermal pollution to the surrounding environment, negatively impacting the environmental quality of the plant and its surroundings. Summary of the Invention

[0007] To overcome the above-mentioned deficiencies of the prior art, the present invention provides a coking plant condensate heat recovery system and method, which efficiently recovers the heat contained in high-temperature condensate, avoids the problem of condensate evaporation loss from the root, saves the cost of heat-using equipment, and avoids thermal pollution.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions:

[0009] A condensate heat recovery system for a coking plant comprises a condensate feed pipe, an evaporator, a working fluid storage tank, a heat engine, a condenser and a condensate collector; the condensate feed pipe is connected to a first inlet of the evaporator, the first outlet of the evaporator is connected to an inlet pipe of a condensate collector, and the condensate collector is a closed structure; the working fluid storage tank outlet is connected to a second inlet pipe of the evaporator, the second outlet of the evaporator is connected to an inlet pipe of a heat engine, the outlet of the heat engine is connected to a first inlet pipe of a condenser, and the first outlet of the condenser is connected to an inlet pipe of a working fluid storage tank.

[0010] Furthermore, the heat engine is a screw expander.

[0011] Furthermore, a generator is included, and the heat engine is connected to the generator to drive the generator to generate electricity.

[0012] Furthermore, the condensate collector outlet is connected to a condensate delivery pipe, and a condensate pump is provided on the condensate delivery pipe.

[0013] Furthermore, a working fluid pump is provided on the pipeline connecting the working fluid storage tank outlet and the second inlet of the evaporator.

[0014] Furthermore, a first regulating valve is provided on the pipeline connecting the outlet of the working fluid storage tank and the second inlet of the evaporator.

[0015] Furthermore, the condensate water supply pipeline is provided with a second regulating valve, a pressure measuring point, a flow measuring point and a temperature measuring point.

[0016] Furthermore, it also includes a cooling water supply pipe and a cooling water return pipe, the cooling water supply pipe is connected to the second inlet of the condenser, and the cooling water return pipe is connected to the second outlet of the condenser.

[0017] A method for recovering heat from condensed water in a coking plant is implemented using the aforementioned condensed water heat recovery system in a coking plant, as follows:

[0018] 1) Condensate with a temperature higher than 100°C is sent to the evaporator through the condensate delivery pipe, and indirectly exchanges heat with the working medium as a heat medium. The cooled condensate enters the condensate collector for storage, and is then pressurized and sent out by the condensate pump.

[0019] 2) The working fluid in the working fluid storage tank is pressurized by the working fluid pump and sent to the evaporator, where it absorbs heat and evaporates into gas as a refrigerant.

[0020] The gaseous working fluid then enters the screw expander, pushing the screw to rotate and do work, converting thermal energy into mechanical energy, which in turn drives the generator to generate electricity.

[0021] The working fluid after doing work enters the condenser and is cooled into liquid, flows into the working fluid storage tank for storage, and is then pumped out by the working fluid pump and pressurized and sent to the evaporator, forming a cycle.

[0022] 3) Cooling water is supplied to the condenser through the cooling water supply pipe to cool the working medium into liquid after work, and then the cooling water is returned to the outside through the cooling water return pipe.

[0023] 4) When the flow rate and temperature of the condensate water with a temperature higher than 100°C sent from the outside fluctuate, the flow rate of the working fluid is automatically adjusted by the first regulating valve to ensure that the temperature and pressure of the gaseous working fluid entering the screw expander are stable.

[0024] When the flow rate and temperature of the condensate water with a temperature higher than 100°C sent from the outside fluctuate, the pressure of the high-temperature condensate water is automatically adjusted by the second regulating valve to ensure the stability of the pressure in the condensate water channel.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. In this invention, the condensate feed pipeline, evaporator, and condensate collector are sequentially connected by pipelines, and the condensate collector is a closed structure. The working fluid storage tank, evaporator, heat engine, and condenser are also connected by pipelines to form a circulation pipeline. High-temperature condensate flows into the evaporator, acting as a heat medium to indirectly exchange heat with the working fluid. The gaseous working fluid then enters the heat engine to perform work, achieving efficient energy utilization. The cooled condensate enters the closed condensate collector for storage and is then pressurized and delivered by a condensate pump.

[0027] In traditional processes, heat-using equipment must be equipped with a subcooling section to control the condensate temperature, which undoubtedly increases the complexity and manufacturing cost of the equipment. This invention cools the high-temperature condensate through heat exchange, eliminating the subcooling section. While ensuring that the production process is not affected, it can effectively reduce the cost of heat-using equipment and alleviate the financial pressure on enterprises to purchase equipment.

[0028] The present invention cools high-temperature condensate water through heat exchange, avoids overheating of pipelines and condensate water tanks, and ensures safe and stable operation of the entire production system.

[0029] The condensate collector of the present invention has a closed structure, which prevents large amounts of heat from being lost through evaporation, improves the recycling rate of water resources, and prevents the steam generated during the evaporation process from causing thermal pollution to the surrounding environment and having a negative impact on the environmental quality of the factory and its surroundings.

[0030] 2. The heat engine of this invention is a screw expander, which is connected after the evaporator. A gaseous working fluid enters the screw expander, where it drives the screw to rotate and produce work, converting thermal energy into mechanical energy. The generator receives the mechanical energy from the screw expander and uses it to generate electricity. This advanced energy conversion technology converts heat, which would otherwise be wasted, into electricity. This approach not only conforms to the principle of efficient energy utilization but also significantly increases the company's economic benefits, providing additional revenue growth.

[0031] 3. In the present invention, a working fluid pump is provided on the pipeline connecting the outlet of the working fluid storage tank and the second inlet of the evaporator. The working fluid pump pressurizes the working fluid and sends it to the evaporator to form a circulation.

[0032] 4. The pipeline connecting the outlet of the working fluid storage tank and the second inlet of the evaporator is provided with a first regulating valve. The pipeline for supplying condensate is provided with a second regulating valve, a pressure measuring point, a flow measuring point, and a temperature measuring point.

[0033] The flow measurement point detects the incoming condensate flow rate, and the temperature measurement point detects the incoming condensate temperature. The first control valve adjusts the flow rate of the organic working fluid delivered to the evaporator. The flow and temperature signals are linked to the first control valve to automatically adjust the flow rate of the organic working fluid entering the evaporator.

[0034] The pressure measuring point is used to detect the pressure of the incoming condensate water, and the second regulating valve is used to adjust the pressure of the high-temperature condensate water entering the evaporator. The pressure signal is linked to the second regulating valve to realize automatic adjustment of the pressure of the condensate water entering the evaporator.

[0035] 5. The present invention is provided with an adjustment process. When the flow rate and temperature of the high-temperature condensate water sent from the outside fluctuate, the flow rate of the working fluid is automatically adjusted through the first regulating valve to ensure that the temperature and pressure of the gaseous working fluid entering the screw expander are stable; when the flow rate and temperature of the high-temperature condensate water sent from the outside fluctuate, the pressure of the high-temperature condensate is automatically adjusted through the second regulating valve to ensure that the pressure in the condensate water passage is stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a schematic diagram of the structure and process principle of the present invention.

[0037] Markings in the figure: 1. Evaporator; 2. Screw expander; 3. Generator; 4. Condensator; 5. Working fluid storage tank; 6. Working fluid pump; 7. Condensate collector; 8. Condensate pump; 9. Flow measuring point; 10. Temperature measuring point; 11. First regulating valve; 12. Pressure measuring point; 13. Second regulating valve; F1. Condensate inlet pipe; F2. Condensate outlet pipe; F3. Cooling water supply pipe; F4. Cooling water return pipe. DETAILED DESCRIPTION

[0038] The embodiments of the present invention are described in detail below. In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described 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, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is in no way intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0039] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0040] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to direct connections, indirect connections through an intermediary, or internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0041] In the description of the present invention, it should be noted that the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0042] Unless otherwise specifically stated, the relative arrangement of the parts and steps, the numerical expressions and the numerical values ​​set forth in these embodiments do not limit the scope of the present invention. At the same time, it should be clear that, for ease of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship. The techniques, methods and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the techniques, methods and equipment should be considered as part of the authorization specification. In all examples shown and discussed here, any specific values ​​should be interpreted as being merely exemplary and not as limiting. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that similar numbers and letters represent similar items in the following figures, and therefore, once an item is defined in one figure, it does not need to be further discussed in subsequent figures.

[0043] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0044] like Figure 1 As shown, a condensate heat recovery system for a coking plant includes a condensate inlet pipe F1, a condensate outlet pipe F2, a cooling water supply pipe F3, a cooling water return pipe F4, an evaporator 1, a screw expander 2, a generator 3, a condenser 4, a working fluid storage tank 5, a working fluid pump 6, a condensate collector 7, a condensate pump 8, a flow measuring point 9, a temperature measuring point 10, a first regulating valve 11, a pressure measuring point 12 and a second regulating valve 13.

[0045] Condensate inlet pipe F1 is connected to the first inlet of evaporator 1 and is equipped with a second regulating valve 13, a flow measuring point 9, a temperature measuring point 10, and a pressure measuring point 12. The first outlet of evaporator 1 is connected to a pipeline of condensate collector 7. The outlet of condensate collector 7 is connected to condensate outlet pipe F2, which is equipped with a condensate pump 8.

[0046] The second outlet of evaporator 1 is connected to the inlet pipe of screw expander 2, which is connected to the first inlet pipe of condenser 4. The first outlet of condenser 4 is connected to the inlet pipe of working fluid storage tank 5, which is connected to the second inlet pipe of evaporator 1, forming a circulation pipeline. The pipeline connecting the outlet of working fluid storage tank 5 and the second inlet of evaporator 1 is equipped with a working fluid pump 6 and a first regulating valve 11.

[0047] The screw expander 2 is connected to the generator 3 to drive the generator 3 to generate electricity. The cooling water supply pipe F3 is connected to the second inlet of the condenser 4, and the second outlet of the condenser 4 is connected to the cooling water return pipe F4.

[0048] Evaporator 1 exchanges heat between high-temperature condensate and the working fluid, heating the working fluid from liquid to gas. Screw expander 2 is connected after evaporator 1. The gaseous working fluid enters screw expander 2, where it drives the screw to rotate and generate work, converting thermal energy into mechanical energy, which in turn drives generator 3. Generator 3 receives the mechanical energy from screw expander 2 and uses it to generate electricity. Condenser 4 cools the working fluid to a low liquid level after work. Working fluid storage tank 5 stores the cooled working fluid, providing a reserve for continuous and stable operation of the entire system. Working fluid pump 6 pressurizes the working fluid and delivers it to the evaporator for circulation. Condensate collector 7, a closed structure, stores the condensate after heat exchange. Condensate pump 8 pressurizes the condensate and delivers it to the outside. Flow measuring point 9 measures the incoming condensate flow rate, temperature measuring point 10 measures the incoming condensate temperature, and first regulating valve 11 adjusts the flow rate of the organic working fluid delivered to the evaporator. The flow and temperature signals are linked to the first regulating valve 11 to automatically adjust the flow of the organic working fluid entering the evaporator. A pressure measuring point 12 is used to detect the pressure of the incoming condensate. The second regulating valve 13 is used to adjust the pressure of the high-temperature condensate entering the evaporator. The pressure signal is linked to the second regulating valve 13 to automatically adjust the pressure of the condensate entering the evaporator.

[0049] A method for recovering heat from condensed water in a coking plant is implemented using the aforementioned condensed water heat recovery system in a coking plant, as follows:

[0050] 1. High temperature condensate process:

[0051] Condensate with a temperature above 100°C is sent to the evaporator 1 through the condensate delivery pipe F1, and indirectly exchanges heat with the working medium as a heat medium. The cooled condensate enters the condensate collector 7 for storage, and is then pressurized by the condensate pump 8 and delivered to the outside through the condensate delivery pipe F2.

[0052] 2. Working fluid flow:

[0053] The working medium in the working medium storage tank 5 is pressurized and sent to the evaporator 1 by the working medium pump 6, and absorbs heat and evaporates into gas in the evaporator 1 as a refrigerant.

[0054] The gaseous working medium then enters the screw expander 2, pushing the screw to rotate and do work, converting thermal energy into mechanical energy, which in turn drives the generator 3 to generate electricity.

[0055] The working fluid after doing work enters the condenser 4 and is cooled into liquid state, flows into the working fluid storage tank 5 for storage, and is then pumped out by the working fluid pump 6 and pressurized and sent to the evaporator 1, forming a cycle.

[0056] 3. Cooling water process:

[0057] Cooling water is supplied to the condenser 4 through the cooling water supply pipe F3 to cool the working medium after work into liquid state, and then the cooling water is returned to the outside through the cooling water return pipe F4.

[0058] 4. Adjustment process:

[0059] When the flow rate and temperature of the condensate water with a temperature higher than 100° C. sent from the outside fluctuate, the flow rate of the working medium is automatically adjusted by the first regulating valve 11 to ensure that the temperature and pressure of the gaseous working medium entering the screw expander are stable.

[0060] When the flow rate and temperature of the condensate water with a temperature higher than 100° C. sent from the outside fluctuate, the pressure of the high-temperature condensate water is automatically adjusted by the second regulating valve 13 to ensure the pressure in the condensate water passage is stable.

[0061] Example:

[0062] A method for recovering heat from condensate in a coking plant is provided. Taking 155°C condensate as an example, the 155°C condensate is fed into the evaporator 1 through the condensate feed pipe F1, and serves as a heat medium for indirect heat exchange with the working medium. The cooled condensate enters the condensate collector 7 for storage. After recovery, the condensate temperature is 85°C, and then the condensate is pressurized by the condensate pump 8 and fed out through the condensate feed pipe F2.

[0063] The present invention reduces water loss during condensate evaporation. For example, if 10 tons / hour of condensate at 155°C is cooled to 85°C through evaporation, 1.3 tons / hour of water is lost. With the present invention, the condensate collector 7 is closed, eliminating water loss due to evaporation. Based on an annual operating time of 8,000 hours, this saves 10,400 tons of condensate.

[0064] The working fluid in the working fluid storage tank 5 is pressurized by the working fluid pump 6 and sent to the evaporator 1. As a refrigerant, it absorbs heat and evaporates into gas in the evaporator 1. The gaseous working fluid then enters the screw expander 2, which drives the screw to rotate and do work, converting heat energy into mechanical energy, which in turn drives the generator 3 to generate electricity. After doing work, the working fluid enters the condenser 4 and is cooled into liquid state. It flows into the working fluid storage tank 5 for storage, and is then pumped out by the working fluid pump 6 and pressurized and sent to the evaporator 1, forming a cycle.

[0065] Taking the condensate volume of 10t / h as an example, the power generation capacity is about 85kW. Based on 8,000 operating hours per year, the annual power generation is about 680,000 kWh. Based on the electricity fee of 0.6 yuan, the annual electricity cost can be saved by 410,000 yuan.

[0066] This invention reduces the cost of heat-using equipment: With this solution, heat-using equipment using steam as a heat source no longer needs to meet the requirement of a uniform set temperature for discharged condensate, nor does it need to include a subcooling stage to meet this requirement. Overall, this reduces the cost of heat-using equipment by 5%. While achieving these goals, it also avoids thermal pollution.

[0067] The present invention realizes the recovery of condensed water heat and uses it for producing electric energy, reduces water loss in the evaporation process of condensed water, saves the cost of heat-using equipment and avoids the generation of thermal pollution problems.

[0068] The above description is only part of the specific implementation methods of the present invention, and the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solutions and inventive concepts of the present invention, should be covered by the protection scope of the present invention.

Claims

1. A coking plant condensate heat recovery system, characterized by: It includes condensate inlet pipeline, evaporator, working fluid storage tank, heat engine, condenser and condensate collector; The condensate feeding pipe is connected to the first inlet of the evaporator, and the first outlet of the evaporator is connected to the inlet pipe of the condensate collector, and the condensate collector is a closed structure; The working fluid storage tank outlet is connected to the second inlet pipe of the evaporator, the second evaporator outlet is connected to the heat engine inlet pipe, the heat engine outlet is connected to the first inlet pipe of the condenser, and the first condenser outlet is connected to the working fluid storage tank inlet pipe.

2. The coking plant condensate heat recovery system according to claim 1, characterized in that: The heat engine is a screw expander.

3. The coking plant condensate heat recovery system according to claim 1, characterized in that: It also includes a generator, and the heat engine is connected to the generator to drive the generator to generate electricity.

4. The coking plant condensate heat recovery system according to claim 1, characterized in that: The condensate collector outlet is connected to a condensate delivery pipe, and a condensate pump is provided on the condensate delivery pipe.

5. The coking plant condensate heat recovery system according to claim 1, characterized in that: A working fluid pump is provided on the pipeline connecting the working fluid storage tank outlet and the second inlet of the evaporator.

6. The coking plant condensate heat recovery system according to claim 1, characterized in that: A first regulating valve is provided on the pipeline connecting the outlet of the working fluid storage tank and the second inlet of the evaporator.

7. The coking plant condensate heat recovery system according to claim 1, characterized in that: The condensate water supply pipeline is provided with a second regulating valve, a pressure measuring point, a flow measuring point and a temperature measuring point.

8. The coking plant condensate heat recovery system according to claim 1, characterized in that: It also includes a cooling water supply pipe and a cooling water return pipe. The cooling water supply pipe is connected to the second inlet of the condenser, and the cooling water return pipe is connected to the second outlet of the condenser.

9. A method for recovering heat from condensed water in a coking plant, implemented by using a condensed water heat recovery system for a coking plant according to any one of claims 1 to 8, characterized in that: The details are as follows: 1) Condensate with a temperature higher than 100°C is sent to the evaporator through the condensate feed pipe, and indirectly exchanges heat with the working medium as a heat medium. The cooled condensate enters the condensate collector for storage, and is then pressurized and sent out by the condensate pump; 2) The working fluid in the working fluid storage tank is pressurized by the working fluid pump and sent to the evaporator, where it absorbs heat and evaporates into gas as a refrigerant; The gaseous working fluid then enters the screw expander, pushing the screw to rotate and do work, converting thermal energy into mechanical energy, which in turn drives the generator to generate electricity; The working fluid after doing work enters the condenser and is cooled into liquid state, flows into the working fluid storage tank for storage, and is then pumped out by the working fluid pump and pressurized and sent to the evaporator, forming a cycle; 3) Cooling water is supplied to the condenser through the cooling water supply pipe to cool the working medium into liquid after work, and then the cooling water is returned to the outside through the cooling water return pipe.

10. A coking plant condensate heat recovery method according to claim 9, characterized in that: Also includes: When the flow rate and temperature of the condensate water above 100°C sent from the outside fluctuate, the first regulating valve automatically adjusts the flow rate of the working medium to ensure the temperature and pressure of the gaseous working medium entering the screw expander are stable; When the flow rate and temperature of the condensate water with a temperature higher than 100°C sent from the outside fluctuate, the pressure of the high-temperature condensate water is automatically adjusted by the second regulating valve to ensure the stability of the pressure in the condensate water channel.

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