Different water supply temperatures choose different temperature differences. The most energy-saving industrial circulating water transportation method

Abstract

The present invention discloses a method for conveying industrial circulating water that is most energy-efficient by selecting different temperature differences for different water supply temperatures, including the following steps: S1, obtaining real-time water supply temperature, return water temperature, temperature of sensitive heat exchange area and water supply terminal pressure; S2, continuously lowering the operating frequency of the water pump at the current water supply temperature, increasing the return water temperature, until the temperature of the sensitive heat exchange area rises to the limit value, and stopping the frequency modulation; S3, obtaining the current water supply temperature, supply and return water temperature difference, and water pump operating frequency and uploading them to a database. Aiming at the technical problem that the flow in the on-site circulating water equipment cannot achieve continuous conveying control, the present invention provides a method for conveying industrial circulating water that is most energy-efficient by selecting different temperature differences for different water supply temperatures, which can control the operating frequency of the water pump by selecting different temperature differences according to different water supply temperatures, so that the output flow change can achieve continuous dynamic balance.

Description

Technical Field

[0001] The invention relates to the technical field of industrial or commercial circulating cooling water, and in particular to an industrial circulating water delivery method which is most energy-efficient when selecting different temperature differences for different water supply temperatures. Background Art

[0002] In the circulating cooling water used in industrial production such as chemical, steel, and power generation, the circulating cooling water is an open cycle. The cooling water is greatly affected by the external environment. The temperature varies greatly in each season of the year, and even the temperature difference between day and night is particularly large within a day. When the temperature is highest in summer, the water supply temperature can reach about 33°C, and when the temperature is lowest in winter, the water supply temperature can be as low as about 10 degrees. Under the same production load, because the water supply temperature is different, the effect of heat exchange is very different, so the amount of cooling water required on site is also different.

[0003] After the on-site circulating water equipment is turned on, it usually runs at a constant pressure or constant flow. When the water supply temperature drops to a certain temperature, the heat exchange efficiency increases. Enterprises usually choose to manually shut down one or two cooling water pumps to reduce the flow. For example, from April to October, 4 circulating water pumps need to be turned on. From November to March of the following year, one or two will be shut down to reduce the flow. However, when 2-3-4 pumps are turned on, the flow changes are staged, not continuous, which makes it impossible to achieve continuous flow control. Summary of the invention

[0004] 1. Technical problem to be solved by the invention

[0005] In view of the technical problem that the flow in on-site circulating water equipment cannot be continuously transported and controlled, the present invention provides an industrial circulating water transportation method that is most energy-efficient by selecting different temperature differences for different water supply temperatures. It can control the operating frequency of the water pump by selecting different temperature differences according to different water supply temperatures, so that the output flow change can achieve continuous dynamic balance.

[0006] 2. Technical solution

[0007] To solve the above problems, the technical solution provided by the present invention is:

[0008] A method for conveying industrial circulating water with the most energy saving by selecting different temperature differences for different water supply temperatures comprises the following steps: S1, obtaining real-time water supply temperature, return water temperature, temperature of a sensitive heat exchange zone and water supply terminal pressure; S2, at the current water supply temperature, continuously lowering the operating frequency of a water pump and increasing the return water temperature until the temperature of the sensitive heat exchange zone rises to a limit value, and then stopping the frequency modulation; S3, obtaining the current water supply temperature, the supply and return water temperature difference, and the operating frequency of a water pump and uploading them to a database.

[0009] Optionally, S1 also includes, using the real-time water supply temperature as a logical judgment condition to query in the database whether there is the same water supply temperature; if so, retrieving the supply and return water temperature difference and the water pump operating frequency under the water supply temperature, and performing frequency conversion control on the water pump to make the real-time supply and return water temperature difference tend to the supply and return water temperature difference in the database; if not, executing S2.

[0010] Optionally, the method further includes S4, obtaining a current circulating water flow rate, determining the number of working water pumps based on the circulating water flow rate, and uploading the result to a database.

[0011] Optionally, it includes a control system, which includes a circulation pipeline; a plurality of cooling towers connected in parallel to the circulation pipeline; a plurality of variable frequency water pumps connected in parallel to the circulation pipeline; a plurality of heat exchange equipment connected in parallel to the circulation pipeline; a first temperature sensor for detecting the water supply temperature; a second temperature sensor for detecting the return water temperature; a third temperature sensor for detecting the temperature of the heat exchange equipment in the sensitive area; the variable frequency water pump, the first temperature sensor, the second temperature sensor and the third temperature sensor are all electrically connected to the controller.

[0012] Optionally, a pressure sensor for detecting the pressure at the water supply end is also included, and the pressure sensor is electrically connected to the controller.

[0013] Optionally, it also includes a flow sensor for detecting the flow rate of circulating water in the circulation pipeline, and the flow sensor is electrically connected to the controller.

[0014] Optionally, the heat exchange equipment is a heat exchanger or a reactor.

[0015] 3. Beneficial effects

[0016] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects:

[0017] (1) The present invention solves the problem of achieving continuous flow control by selecting different supply and return water temperature differences according to different water supply temperatures through intelligent control. This can not only achieve a dynamic balance of the amount of cooling water required on site, but also save a lot of electricity through real-time intelligent control of the water pump motor.

[0018] (2) When the system is running, it is preferred to query from the database whether there is the same water supply temperature as a reference. If so, it can be directly retrieved to save calculation time and improve control efficiency. If not, the calculation is performed and the calculated data is uploaded to the database as a supplement. The same water supply temperature only needs to be calculated once to avoid repeated calculations that affect control efficiency.

[0019] (3) By judging by the flow rate, if the circulating water flow demand can still be met by reducing the operation of one or more water pumps, the corresponding number of water pumps will be automatically shut down. Compared with controlling the operating frequency of water pumps, shutting down redundant water pumps is more energy-saving. The calculated number of operating water pumps will also be synchronously uploaded to the database for subsequent control data use. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A schematic flow chart of a method for transporting industrial circulating water with the most energy-saving characteristics by selecting different temperature differences at different water supply temperatures proposed in the first embodiment of the present invention;

[0021] Figure 2 It is a schematic table of the control of the optimization process of adjusting different temperature differences at the same water supply temperature in the present invention;

[0022] Figure 3 It is a data summary table of different temperature difference control based on different water supply temperatures in the present invention;

[0023] Figure 4 A schematic flow chart of a method for transporting industrial circulating water with the highest energy efficiency by selecting different temperature differences for different water supply temperatures proposed in the second embodiment of the present invention;

[0024] Figure 5 A schematic flow chart of a method for transporting industrial circulating water with the most energy-saving characteristics by selecting different temperature differences for different water supply temperatures proposed in Embodiment 3 of the present invention;

[0025] Figure 6 This is a schematic diagram of the structure of an industrial circulating water control system that selects the most energy-efficient temperature difference for different water supply temperatures, as proposed in the fourth embodiment of the present invention;

[0026] 1. Circulation pipeline; 2. Cooling tower; 3. Variable frequency water pump; 4. Heat exchange equipment; 5. First temperature sensor; 6. Second temperature sensor; 7. Third temperature sensor; 8. Pressure sensor; 9. Flow sensor. DETAILED DESCRIPTION

[0027] To further understand the content of the present invention, Figure 1-6 The present invention is described in detail with reference to the accompanying drawings and embodiments.

[0028] Embodiment 1

[0029] Combined with Figure 1-3 , a most energy-efficient industrial circulating water delivery method for selecting different temperature differences at different water supply temperatures in this embodiment includes the following steps: S1, obtaining real-time water supply temperature, return water temperature, sensitive heat exchange zone temperature and water supply terminal pressure;

[0030] S2. Under the current water supply temperature, continuously lower the water pump operating frequency and increase the return water temperature until the temperature of the sensitive heat exchange area rises to the limit value, and stop frequency adjustment; S3. Obtain the current water supply temperature, supply and return water temperature difference, and water pump operating frequency and upload them to the database.

[0031] According to the formula Q = C*L*(T1-T2), Q: the cooling capacity required for production; L: circulating water flow; C: specific heat capacity of water; T1: return water temperature; T2: supply water temperature; it can be known that, when the cooling capacity required for production remains unchanged, the circulating water flow and the supply and return water temperature difference are inversely proportional, and the circulating water flow is proportional to the operating frequency of the water pump. When the load required for production remains unchanged, the flow can be reduced by expanding the temperature difference, and energy saving can be achieved by establishing a dynamic balance. Different water supply temperatures have different heat exchange efficiencies. Different water supply temperatures can be recorded in real time, and different temperature differences can be selected to control the operating frequency of the water pump, so that the output flow change reaches a continuous dynamic balance, and the purpose of energy saving is achieved through variable flow control. Intelligent control solves the problem of selecting different supply and return water temperature differences according to different water supply temperatures to achieve continuous flow delivery control. Not only can the dynamic balance of the cooling water required on site be achieved, but also a large amount of electricity can be saved through real-time intelligent control of the water pump.

[0032] The present industrial circulating water delivery method which selects the most energy-saving industrial circulating water delivery method with different temperature differences for different water supply temperatures realizes self-learning through the above-mentioned method, so as to add the supply and return water temperature difference and the water pump operation frequency under different water supply temperatures into the database and update them in real time to form a more complete database, so as to facilitate the subsequent direct retrieval and use for different water supply temperatures, without the need for the S1-S3 calculation process, and realize more intelligent control.

[0033] Regarding the concept of sensitive heat exchange zone temperature, for example, if the temperatures of several heat exchange zones are changing at the same time, the heat exchange zone whose temperature first reaches the limit value is the sensitive heat exchange zone, and the temperature of this sensitive heat exchange zone is the sensitive heat exchange zone temperature, thereby making the most sensitive heat exchange zone in a safe state.

[0034] When the pressure at the end of the water supply is lower than the safe value, stop adjusting the temperature difference to ensure production safety.

[0035] For example, a factory circulating water station system consists of 4 circulating water pumps and 3 cooling towers. The rated power of the pump motor is 110kw, the head is 50 meters, and the flow rate is 600m 3 / h.

[0036] Assuming that the water supply temperature is 33°C, the highest throughout the year, the circulating water flow rate is adjusted by controlling the operating frequency of the water pump, and the circulating water supply and return water temperature difference changes until the temperature difference reaches the maximum temperature difference that meets normal production. During the adjustment process, the maximum temperature difference is mainly used as a reference value. The operating frequency of the water pump will produce certain fluctuations in the actual production process to ensure that the supply and return water temperature difference reaches the ideal value as soon as possible.

[0037] Embodiment 2

[0038] Combined with Figure 4 , a most energy-saving industrial circulating water transportation method for selecting different temperature differences for different water supply temperatures in this embodiment, compared with the first embodiment, includes the following steps: S1, obtaining real-time water supply temperature, return water temperature, sensitive heat exchange zone temperature and water supply terminal pressure, and using the real-time water supply temperature as a logical judgment condition to query whether there is the same water supply temperature in the database; if so, the supply and return water temperature difference and the water pump operating frequency under the water supply temperature are retrieved, and the water pump is frequency-controlled to make the real-time supply and return water temperature difference tend to the supply and return water temperature difference in the database; if not, execute S2; S2, at the current water supply temperature, continuously reduce the water pump operating frequency and increase the return water temperature until the temperature of the sensitive heat exchange zone rises to the limit value, and stop frequency modulation; S3, obtain the current water supply temperature, supply and return water temperature difference, and water pump operating frequency and upload them to the database.

[0039] When the system is running, it is first necessary to query the database to see if there is the same water supply temperature as a reference. If so, it can be directly retrieved to save calculation time and improve control efficiency. If not, calculation is performed and the calculated data is uploaded to the database as a supplement. The same water supply temperature only needs to be calculated once to avoid repeated calculations that affect control efficiency.

[0040] For example, a factory circulating water station system consists of 4 circulating water pumps and 3 cooling towers. The rated power of the pump motor is 110kw, the head is 50 meters, and the flow rate is 600m 3 / h.

[0041] Assume that when the water supply temperature is 18°C, the system looks up the table based on the water supply temperature to make a judgment, and selects the supply and return water temperature difference and the water pump operating frequency when the water supply temperature is 18°C ​​for control.

[0042] Embodiment 3

[0043] Combined with Figure 5, a most energy-saving industrial circulating water transportation method for selecting different temperature differences for different water supply temperatures in this embodiment, compared with the second embodiment, includes the following steps: S1, obtaining real-time water supply temperature, return water temperature, sensitive heat exchange zone temperature and water supply terminal pressure, and using the real-time water supply temperature as a logical judgment condition to query whether there is the same water supply temperature in the database; if so, the supply and return water temperature difference and the water pump operating frequency under the water supply temperature are retrieved, and the water pump is frequency-controlled to make the real-time supply and return water temperature difference tend to the supply and return water temperature difference in the database; if not, S2 is executed; S2, at the current water supply temperature, the water pump operating frequency is continuously lowered and the return water temperature is increased until the temperature of the sensitive heat exchange zone rises to the limit value, and the frequency modulation is stopped; S3, the current water supply temperature, the supply and return water temperature difference, and the water pump operating frequency are obtained and uploaded to the database; S4, the current circulating water flow rate is obtained, the number of working units of the water pump is determined by the circulating water flow rate, and the number of working units of the water pump is uploaded to the database.

[0044] Judging by the flow rate, if the circulating water flow demand can still be met by reducing the operation of one or more water pumps, the corresponding number of water pumps will be automatically shut down. Compared with controlling the operating frequency of water pumps, shutting down redundant water pumps saves more energy. The calculated number of operating water pumps will also be synchronously uploaded to the database for subsequent control data use.

[0045] For example, when the water supply temperature is 18°C, the system looks up the table to make a judgment based on the water supply temperature, and selects the supply and return water temperature difference, the number of running water pumps and the running frequency of the water pumps when the water supply temperature is 18°C ​​for control.

[0046] Embodiment 4

[0047] Combined with Figure 6, an industrial circulating water control system of the present embodiment that selects different temperature differences for different water supply temperatures and is most energy-efficient, comprises a circulating pipeline 1; a plurality of cooling towers 2, connected in parallel to the circulating pipeline 1; a plurality of variable frequency water pumps 3, connected in parallel to the circulating pipeline 1; a plurality of heat exchange devices 4, connected in parallel to the circulating pipeline 1; a plurality of cooling towers 2, a plurality of variable frequency water pumps 3 and a plurality of heat exchange devices 4 are sequentially arranged along the path of the circulating pipeline 1, the variable frequency water pump 3 is used to control the circulating cooling water to enter the cooling tower 2, the heat exchange device 4 is used to perform heat exchange and cooling on the circulating cooling water coming out of the cooling tower 2 for recycling; a first temperature sensor 5 is used to detect the water supply temperature, the first The temperature sensor 5 is installed on the pipeline between the heat exchange equipment 4 and the variable frequency water pump 3; the second temperature sensor 6 is used to detect the return water temperature, and the second temperature sensor 6 is installed on the pipeline between the cooling tower 2 and the heat exchange equipment 4; the third temperature sensor 7 is used to detect the temperature of the heat exchange equipment 4, and the third temperature sensor 7 is only installed on the heat exchange equipment 4 that is most sensitive to water temperature changes (that is, the sensitive area heat exchange equipment 4), as long as the temperature of the heat exchange equipment 4 reaches the limit value, the temperature difference adjustment will be stopped; the variable frequency water pump 3, the first temperature sensor 5, the second temperature sensor 6 and the third temperature sensor 7 are all electrically connected to the controller.

[0048] In this embodiment, the heat exchange device 4 is a heat exchanger or a reactor.

[0049] The working principle of the most energy-saving industrial circulating water control system for selecting different temperature differences for different water supply temperatures is as follows: the first temperature sensor 5 obtains the real-time water supply temperature, the second temperature sensor 6 obtains the real-time return water temperature, and the third temperature sensor 7 obtains the real-time temperature of the sensitive area heat exchange equipment 4. While keeping the water supply temperature unchanged, the water pump operating frequency is continuously lowered and the return water temperature is increased until the temperature of the sensitive area heat exchange equipment 4 rises to the limit value, the frequency modulation is stopped, and the water supply temperature, the supply and return water temperature difference, and the water pump operating frequency at this time are uploaded to the controller as the standard values ​​at the water supply temperature so that they can be directly called next time.

[0050] According to the formula Q = C*L*(T1-T2), Q: the cooling capacity required for production; L: circulating water flow; C: specific heat capacity of water; T1: return water temperature; T2: supply water temperature; it can be known that, when the cooling capacity required for production remains unchanged, the circulating water flow and the supply and return water temperature difference are inversely proportional, and the circulating water flow is proportional to the operating frequency of the water pump. When the load required for production remains unchanged, the flow can be reduced by expanding the temperature difference, and energy saving can be achieved by establishing a dynamic balance. Different water supply temperatures have different heat exchange efficiencies. Different water supply temperatures can be recorded in real time, and different temperature differences can be selected to control the operating frequency of the water pump, so that the output flow change reaches a continuous dynamic balance, and the purpose of energy saving is achieved through variable flow control. Intelligent control solves the problem of selecting different supply and return water temperature differences according to different water supply temperatures to achieve continuous flow delivery control. Not only can the dynamic balance of the cooling water required on site be achieved, but also a large amount of electricity can be saved through real-time intelligent control of the water pump.

[0051] As an optional solution of the present invention, it also includes a pressure sensor 8 for detecting the pressure at the end of the water supply. The pressure sensor 8 is installed on the pipeline between the heat exchange device 4 and the variable frequency water pump 3, and can also be directly installed on the water outlet of the heat exchange device 4. The pressure sensor 8 is electrically connected to the controller. Because the lower the flow rate, the smaller the water supply pressure at the end. When the water supply temperature is the lowest, the required flow rate is also the least. In the process of adjusting the temperature difference modeling, the terminal pressure will become lower and lower. The pressure sensor 8 is used to ensure that the water supply terminal pressure does not fall below the safety value during the temperature difference adjustment process.

[0052] As an optional solution of the present invention, it also includes a flow sensor 9 for detecting the circulating water flow in the circulating pipeline 1. The flow sensor 9 is installed on the pipeline between the cooling tower 2 and the heat exchange equipment 4, and is used to detect the flow rate flowing from the cooling tower 2 to the heat exchange equipment 4. The flow sensor 9 is electrically connected to the controller. The flow sensor 9 makes a judgment based on the flow rate. If the circulating water flow demand can still be met by reducing the operation of one or more water pumps, the corresponding number of water pumps will be automatically shut down. Compared with controlling the operating frequency of the water pumps, shutting down redundant water pumps is more energy-saving. The calculated number of operating water pumps will also be synchronously uploaded to the database for use as subsequent control data.

[0053] The present invention and its embodiments are described schematically above, and the description is not restrictive. The drawings show only one embodiment of the present invention, and the actual structure is not limited thereto. Therefore, if a person skilled in the art is inspired by it and designs a structural method and an embodiment similar to the technical solution without creativity without departing from the purpose of the invention, they shall all fall within the protection scope of the present invention.

Claims

1. Different water supply temperatures select different temperature differences. The most energy-saving industrial circulating water transportation method is characterized by: The following steps are involved: S1. Obtain real-time water supply temperature, return water temperature, sensitive heat exchange area temperature and water supply terminal pressure; S2. Under the current water supply temperature, continuously lower the pump operating frequency and increase the return water temperature until the temperature of the sensitive heat exchange area rises to the limit value, and then stop frequency regulation; S3, obtain the current water supply temperature, supply and return water temperature difference, and water pump operation frequency and upload them to the database; The S1 also includes using the real-time water supply temperature as a logical judgment condition to query in the database whether there is the same water supply temperature; If yes, the supply and return water temperature difference and the water pump operating frequency under the water supply temperature are retrieved, and the water pump is frequency-controlled to make the real-time supply and return water temperature difference tend to the supply and return water temperature difference in the database; If not, execute S2.

2. The method for conveying industrial circulating water with different temperature differences for the most energy-saving method according to claim 1, characterized in that: It also includes S4, obtaining the current circulating water flow rate, determining the number of working water pumps based on the circulating water flow rate, and uploading it to the database.

3. The most energy-efficient industrial circulating water delivery method for selecting different temperature differences for different water supply temperatures according to claim 1, characterized in that: A control system is included, the control system comprising Circulation pipeline; Several cooling towers are connected in parallel to the circulation pipeline; Several variable frequency water pumps are connected in parallel on the circulation pipeline; Several heat exchange equipments are connected in parallel to the circulation pipeline; A first temperature sensor, used for detecting the water supply temperature; A second temperature sensor is used to detect the return water temperature; The third temperature sensor is used to detect the temperature of the heat exchange equipment in the sensitive area; The variable frequency water pump, the first temperature sensor, the second temperature sensor and the third temperature sensor are all electrically connected to the controller.

4. The method for conveying industrial circulating water with different temperature differences for the most energy-saving method according to claim 3, characterized in that: It also includes a pressure sensor for detecting the pressure at the water supply end, and the pressure sensor is electrically connected to the controller.

5. The most energy-efficient industrial circulating water delivery method for selecting different temperature differences for different water supply temperatures according to claim 3, characterized in that: It also includes a flow sensor for detecting the flow rate of circulating water in the circulation pipeline, and the flow sensor is electrically connected to the controller.

6. The most energy-efficient industrial circulating water delivery method for selecting different temperature differences for different water supply temperatures according to claim 3, characterized in that: The heat exchange equipment is a heat exchanger or a reactor.

Images