Hybrid steam plant based on boiler and molten salt thermal storage and method for regulating the same

Abstract

The present disclosure provides a mixed steam device based on a boiler and a molten salt heat storage and a regulation method thereof. The mixed steam device comprises a boiler system and a molten salt heat storage steam generation system. The first steam generated by the molten salt heat storage steam generation system is mixed with the second steam generated by the boiler system to output mixed steam. The regulation method comprises: obtaining a mixed steam pressure value of the mixed steam; using a gradient adjustment strategy to determine the numerical interval of the mixed steam pressure value, and regulating the molten salt heat storage steam generation system and the boiler system. The first steam flow corresponding to the first steam satisfies a first steam use load, and the mixed steam flow corresponding to the mixed steam satisfies a second steam use load. The present disclosure realizes automatic, efficient and intelligent regulation of the molten salt heat storage steam generation system and the boiler system, meets the use requirements of users, and makes the proportion of the first steam flow output by the molten salt heat storage steam generation system meet the design value.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of steam, in particular to a mixed steam device based on a boiler and molten salt heat storage and a regulation method thereof. BACKGROUND

[0002] With the advancement of technology, various heat storage steam generation technologies have emerged. Such technologies generally heat a certain heat storage medium, the temperature of the heat storage medium is raised or a phase change occurs, and energy is stored in the heat storage medium. When a user needs steam, water is introduced into the heat storage system to exchange heat with the heat storage medium to generate steam for the user.

[0003] The molten salt heat storage steam generation system is a heat storage steam generation technology. After heating the molten salt, the temperature of the molten salt is raised. When a user needs steam, water is exchanged with the high-temperature molten salt to generate steam for the user, and the temperature of the molten salt is lowered, waiting for the next charging.

[0004] Traditional boilers generally include coal-fired boilers and natural gas boilers, etc. fossil fuel boilers, which are currently the main boilers used by factories to generate steam. With the increasing environmental protection requirements, the use of small-capacity coal-fired boilers is basically no longer allowed, and natural gas boilers must be equipped with desulfurization and denitrification devices.

[0005] Heat storage steam generation technology is a new steam generation technology that is environmentally friendly and non-polluting. However, under current conditions, there are still the following problems:

[0006] (1) The initial investment of the system is too high. Unlike the traditional boiler investment, which is proportional to the steam flow, the investment of the heat storage steam generation system is basically proportional to the total steam consumption, which is proportional to the amount of heat storage material used. The price of heat storage material is currently quite high, resulting in a relatively high initial investment for the heat storage steam generation system.

[0007] (2) The system has a large power consumption. Considering the efficiency, approximately 800 degrees of electricity are required to generate one ton of steam. Currently, many factories do not have enough transformer capacity during off-peak hours. If power capacity is increased, it is a significant investment, and a portion of the power capacity fee must be paid to the power supply bureau every month, greatly increasing the operating cost of the heat storage steam generation system.

[0008] (3) The system occupies a large area. The heat storage density of the current heat storage technology is not very high. For example, a single-tank molten salt heat storage steam generation system requires approximately 40 m2 of land to store 5 tons of steam, which is much larger than a traditional boiler.

[0009] (4) There are technical difficulties in the use of the molten salt heat storage steam generation system with the traditional boiler. The technical difficulty lies in how to allocate the proportion of the steam output to the outside when the two systems output steam to the outside.

[0010] At present, when the boiler room exports steam, a pressure switch is usually used to control the start and stop of the boiler. When the boiler pressure reaches the set high value, the boiler is closed, and when the boiler pressure reaches the set low value, the boiler is opened again. Such a way can be completely used for traditional boilers in parallel, mainly because the traditional boiler immediately cuts off the energy supply when it stops, and the output steam immediately becomes small. The characteristics of traditional boilers are similar.

[0011] However, the molten salt heat storage steam generation system has inconsistent characteristics with the traditional boiler. The system generates steam through heat exchange between molten salt and water. Because the energy is stored in the storage tank, and there is stored water in the storage tank, the supply of energy cannot be cut off, and the stored water in the heat exchange pipe can supply steam for a relatively long time.

[0012] The steam flow of the user end (steam system use end) will affect the pressure of the steam system supply end. If the pressure reaches the set high value, all molten salt heat storage steam generation systems and traditional boilers are closed, which will cause the molten salt heat storage steam generation system to provide steam when the pressure reaches the set high value and both systems are closed, eventually resulting in the molten salt heat storage steam generation system output steam flow ratio being larger than the design value during the entire steam delivery process. SUMMARY

[0013] The technical problem to be solved by the present disclosure is to overcome the defect that the pressure control strategy used when the molten salt heat storage steam generation system is used with the traditional boiler in the prior art causes the molten salt heat storage steam generation system output steam ratio to be larger than the design value during the entire steam delivery process, and to provide a mixed steam device based on a boiler and molten salt heat storage and a control method thereof.

[0014] The present disclosure solves the above technical problems by the following technical solutions:

[0015] In a first aspect, a control method for a mixed steam device based on a boiler and molten salt heat storage is provided. The mixed steam device includes a boiler system and a molten salt heat storage steam generation system. The first steam generated by the molten salt heat storage steam generation system is mixed with the second steam generated by the boiler system to output mixed steam.

[0016] The control method includes:

[0017] Obtaining a mixed steam pressure value of the mixed steam;

[0018] Using a gradient adjustment strategy to determine the numerical interval in which the mixed steam pressure value is located, and controlling the molten salt heat storage steam generation system and the boiler system;

[0019] The first steam flow corresponding to the first steam satisfies a first steam use load, and a mixed steam flow corresponding to the mixed steam satisfies a second steam use load; the second steam use load is greater than the first steam use load.

[0020] Preferably, the gradient adjustment strategy comprises:

[0021] setting a first pressure threshold and a second pressure threshold;

[0022] determining whether the mixed steam pressure value is higher than the first pressure threshold, and if so, shutting down the boiler system;

[0023] determining whether the mixed steam pressure value is lower than the second pressure threshold, and if so, starting the boiler system;

[0024] The first pressure threshold is greater than the second pressure threshold.

[0025] Preferably, the gradient adjustment strategy further comprises:

[0026] setting a third pressure threshold and a fourth pressure threshold;

[0027] determining whether the mixed steam pressure value is higher than the third pressure threshold, and if so, shutting down the molten salt heat storage steam generation system;

[0028] determining whether the mixed steam pressure value is lower than the fourth pressure threshold, and if so, starting the molten salt heat storage steam generation system;

[0029] The third pressure threshold is higher than the first pressure threshold;

[0030] The fourth pressure threshold is higher than the second pressure threshold and lower than the first pressure threshold.

[0031] Preferably, the control method further comprises:

[0032] obtaining a mixed steam temperature of the mixed steam;

[0033] determining whether the mixed steam temperature is higher than a set first temperature threshold;

[0034] if so, lowering the mixed steam temperature so that the mixed steam temperature satisfies the first temperature threshold;

[0035] if not, increasing the mixed steam temperature so that the mixed steam temperature satisfies the first temperature threshold;

[0036] The first temperature threshold is higher than a saturation temperature corresponding to the mixed steam pressure value, and different mixed steam pressure values correspond to different saturation temperatures.

[0037] Preferably, the method further comprises:

[0038] acquiring a first steam temperature of the first steam;

[0039] determining whether the first steam temperature is lower than a second temperature threshold;

[0040] if yes, shutting down the molten salt heat storage steam generation system and charging the molten salt heat storage steam generation system;

[0041] wherein the second temperature threshold represents a temperature corresponding to the end of discharging of the molten salt heat storage steam generation system.

[0042] In a second aspect, a hybrid steam device is provided, comprising a water storage tank, a boiler system, a molten salt heat storage steam generation system, a main and branch cylinder, and a control system for implementing the above-mentioned control method, the molten salt heat storage steam generation system being connected to the boiler system in parallel through a pipeline and being arranged between the water storage tank and the main and branch cylinder.

[0043] The control system comprises:

[0044] a pressure acquisition module configured to acquire a hybrid steam pressure value of the hybrid steam;

[0045] a pressure control module configured to determine a numerical interval in which the hybrid steam pressure value is located by using a gradient adjustment strategy and to control the molten salt heat storage steam generation system and the boiler system.

[0046] Preferably, the pressure control module comprises:

[0047] a first pressure adjustment unit configured to set a first pressure threshold, to determine whether the hybrid steam pressure value is higher than the first pressure threshold, and to shut down the boiler system if yes;

[0048] a second pressure adjustment unit configured to set a second pressure threshold, to determine whether the hybrid steam pressure value is lower than the second pressure threshold, and to start the boiler system if yes;

[0049] a third pressure adjustment unit configured to set a third pressure threshold, to determine whether the hybrid steam pressure value is higher than the third pressure threshold, and to shut down the molten salt heat storage steam generation system if yes;

[0050] a fourth pressure adjustment unit configured to set a fourth pressure threshold, to determine whether the hybrid steam pressure value is lower than the fourth pressure threshold, and to start the molten salt heat storage steam generation system if yes.

[0051] Preferably, the regulation system further comprises:

[0052] a mixed steam temperature acquisition module configured to acquire a mixed steam temperature of the mixed steam;

[0053] a first preset temperature acquisition module configured to set a first temperature threshold according to a saturation temperature corresponding to the mixed steam pressure value;

[0054] a temperature regulation module configured to determine whether the mixed steam temperature is higher than the set first temperature threshold;

[0055] if yes, reduce the mixed steam temperature so that the mixed steam temperature meets the first temperature threshold;

[0056] if no, increase the mixed steam temperature so that the mixed steam temperature meets the first temperature threshold.

[0057] Preferably, the regulation system further comprises:

[0058] a first steam temperature acquisition module configured to acquire a first steam temperature of the first steam;

[0059] a second preset temperature acquisition module configured to set a second temperature threshold according to a temperature corresponding to an energy release end of the molten salt heat storage steam generation system;

[0060] the temperature regulation module is further configured to determine whether the first steam temperature is lower than the set second temperature threshold;

[0061] if yes, shut down the molten salt heat storage steam generation system and charge the molten salt heat storage steam generation system.

[0062] Preferably, the molten salt heat storage steam generation system comprises a heat storage system steam cylinder, a desuperheater, and a plurality of salt storage tanks and metering pumps;

[0063] the salt storage tanks are arranged between the water storage tank and the heat storage system steam cylinder in a parallel pipeline connection mode, and the metering pumps and the salt storage tanks are connected one by one;

[0064] the desuperheater is arranged between the heat storage system steam cylinder and the total steam cylinder, the desuperheater is provided with a branch pipeline connected to the water storage tank, and a variable frequency water pump is arranged on the branch pipeline.

[0065] On the basis of common sense in the art, the above-mentioned preferred conditions can be combined arbitrarily, that is, to obtain each preferred example of the present disclosure.

[0066] The positive progress effect of the present disclosure is that:

[0067] The boiler and molten salt heat storage based hybrid steam device and its regulation method of the present disclosure, the regulation method is applied to a hybrid steam device composed of a molten salt heat storage steam generation system and a boiler system. The first steam generated by the molten salt heat storage steam generation system is mixed with the second steam generated by the boiler system to output mixed steam, so as to provide steam for the downstream user and meet the steam use load of the user. The first steam flow corresponding to the first steam meets the first steam use load, and the mixed steam flow corresponding to the mixed steam meets the second steam use load. The second steam use load is greater than the first steam use load. By obtaining the mixed steam pressure value of the mixed steam, the gradient regulation strategy is adopted according to the steam use demand of the user, so as to automatically, efficiently and intelligently regulate the molten salt heat storage steam generation system and the boiler system, meet the use demand of the user, and make the proportion of the first steam flow output by the molten salt heat storage steam generation system meet the design value. BRIEF DESCRIPTION OF DRAWINGS

[0068] Figure 1 The first flowchart of the regulation method of the boiler and molten salt heat storage based hybrid steam device provided in Embodiment 1 of the present disclosure is provided.

[0069] Figure 2 The second flowchart of the regulation method of the boiler and molten salt heat storage based hybrid steam device provided in Embodiment 1 of the present disclosure is provided.

[0070] Figure 3 The third flowchart of the regulation method of the boiler and molten salt heat storage based hybrid steam device provided in Embodiment 1 of the present disclosure is provided.

[0071] Figure 4 The fourth flowchart of the regulation method of the boiler and molten salt heat storage based hybrid steam device provided in Embodiment 1 of the present disclosure is provided.

[0072] Figure 5 The fifth flowchart of the regulation method of the boiler and molten salt heat storage based hybrid steam device provided in Embodiment 1 of the present disclosure is provided.

[0073] Figure 6 The structure diagram of the hybrid steam device provided in Embodiment 2 of the present disclosure is provided.

[0074] Figure 7 The structure diagram of the regulation system in the hybrid steam device provided in Embodiment 2 of the present disclosure is provided. DETAILED DESCRIPTION

[0075] The present disclosure will be further described by way of examples below, but the present disclosure is not limited in the scope of the examples.

[0076] Embodiment 1

[0077] The embodiment provides a regulation method of a mixed steam device based on a boiler and a molten salt heat storage, the mixed steam device comprising a boiler system and a molten salt heat storage steam generation system, first steam generated by the molten salt heat storage steam generation system is mixed with second steam generated by the boiler system, and the mixed steam is output after mixing. Figure 1 As shown in the figure, the regulation method comprises the following steps.

[0078] S101, acquiring a mixed steam pressure value of the mixed steam.

[0079] S102, adopting a gradient regulation strategy, judging a value interval in which the mixed steam pressure value is located, and regulating the molten salt heat storage steam generation system and the boiler system.

[0080] The first steam flow corresponding to the first steam satisfies a first steam use load, the mixed steam flow corresponding to the mixed steam satisfies a second steam use load, and the second steam use load is greater than the first steam use load.

[0081] In the design stage of the mixed steam device, the steam output proportions of the molten salt heat storage steam generation system and the boiler system are generally designed, for example, the first steam flow output by the molten salt heat storage steam generation system is designed to be 1 ton per hour, the second steam flow output by the boiler system is designed to be 3 tons per hour, the proportion of the first steam flow output by the molten salt heat storage steam generation system is 1, the proportion of the second steam flow output by the boiler system is 3, and the proportion ratio of the first steam flow to the second steam flow is 1:3.

[0082] In the actual use process, water may be stored in the salt storage tank in the molten salt heat storage steam generation system, but the molten salt heat storage steam generation system is based on the chemical reaction of water and molten salt to generate steam. If the strategy of cutting off the molten salt heat storage steam generation system and the traditional boiler when the pressure reaches a set high value is adopted, when the pressure reaches the set high value and both systems are closed, the molten salt heat storage steam generation system mainly provides steam, and finally the proportion of the steam flow output by the molten salt heat storage steam generation system in the whole steam output process is larger than the designed value, for example, the proportion ratio of the first steam flow to the second steam flow is 1.3:3, which does not meet the design requirement.

[0083] The molten salt heat storage steam generation system is charged by heating molten salt, and when steam is needed, the molten salt heat storage steam generation system is discharged by chemical reaction to generate steam. After the energy is released, the molten salt heat storage steam generation system stops running and needs to be heated again to charge the molten salt. The single discharging process of the molten salt heat storage steam generation system and the steam generation process of the boiler system constitute a cycle process of the mixed steam.

[0084] In a cycle of the hybrid steam device, the first steam flow is used to meet the first steam use load of the user, so that the molten salt heat storage steam generation system is always running, and the hybrid steam pressure value of the hybrid steam is detected in real time. When the hybrid steam flow corresponding to the hybrid steam meets the second steam use load, based on the hybrid steam pressure value, a pressure gradient adjustment strategy is used to determine the numerical interval in which the hybrid steam pressure value is located, and the molten salt heat storage steam generation system and the boiler system are regulated and controlled; the hybrid steam flow is ensured to meet the user's demand, and the proportion of the first steam flow output by the molten salt heat storage steam generation system meets the design value.

[0085] The steam adjustment method of the embodiment realizes automatic, efficient and intelligent regulation and control of the molten salt heat storage steam generation system and the boiler system, meets the user's use demand, and makes the proportion of the first steam flow output by the molten salt heat storage steam generation system meet the design value.

[0086] In an optional embodiment, as shown in Figure 2 The gradient adjustment strategy in step S102 includes:

[0087] S1021, setting a first pressure threshold and a second pressure threshold.

[0088] S1022, determining whether the hybrid steam pressure value is higher than the first pressure threshold.

[0089] If yes, step S1023 is performed.

[0090] S1023, closing the boiler system.

[0091] S1024, determining whether the hybrid steam pressure value is lower than the second pressure threshold.

[0092] If yes, step S1025 is performed.

[0093] S1025, starting the boiler system.

[0094] The first pressure threshold is greater than the second pressure threshold.

[0095] For example, the first steam usage load can be the user minimum usage load, the second steam usage load can be the user real-time usage load, and generally, the user real-time usage load is greater than the user minimum usage load. If the first steam flow is 1 ton per hour, the user minimum usage load is 1 ton per hour, the second steam flow is 3 tons per hour, that is, the mixed steam flow is 4 tons per hour, and the user real-time usage load is 2.5 tons per hour in a certain period, the molten salt heat storage steam generation system and the boiler system are both in stable and continuous steam generation. Since the user real-time usage load is less than the mixed steam flow, the mixed steam pressure value of the mixed steam will continue to rise, and when the mixed steam pressure value is higher than the first pressure threshold a, the boiler system is closed, and the boiler system stops running and no longer generates the second steam. At this time, only the molten salt heat storage steam generation system is running, and the first steam flow output by the molten salt heat storage steam generation system is lower than the user real-time usage load, so the mixed steam pressure value of the mixed steam will continue to decrease. When the mixed steam pressure value decreases to the second pressure threshold b, the boiler system is started, and the boiler system starts to run to generate the second steam. The mixed steam pressure value of the mixed steam will gradually increase, and when the mixed steam pressure value is higher than the first pressure threshold a, the boiler system is closed again, and the boiler system stops running to reduce the mixed steam pressure value of the mixed steam. Through the gradient adjustment strategy, the first pressure threshold a and the second pressure threshold b are controlled in a cycle.

[0096] The user minimum usage load can be obtained based on statistics according to historical data of the user end.

[0097] For example, the start and stop of the boiler system can be controlled by a pressure switch.

[0098] The control method of the mixed steam device based on the boiler and the molten salt heat storage of the embodiment realizes automatic, efficient and intelligent control of the molten salt heat storage steam generation system and the boiler system, meets the user usage demand, and makes the proportion of the first steam flow output by the molten salt heat storage steam generation system meet the design value. The mixed steam pressure value of the mixed steam is controlled to ensure the operation safety of the steam system and continuously and stably provide steam for the user.

[0099] In an optional embodiment, as shown in Figure 3 The gradient adjustment strategy in the S102 step further includes:

[0100] S1026, determining whether the mixed steam pressure value is higher than the third pressure threshold.

[0101] If yes, step S1027 is performed.

[0102] S1027, closing the molten salt heat storage steam generation system.

[0103] S1028, determining whether the mixed steam pressure value is lower than a fourth pressure threshold.

[0104] If yes, step S1029 is performed.

[0105] S1029, starting the molten salt heat storage steam generation system.

[0106] The third pressure threshold is higher than the first pressure threshold, and the fourth pressure threshold is higher than the second pressure threshold and lower than the first pressure threshold.

[0107] Similarly, the second steam usage load is the user real-time usage load, and the user minimum usage load fluctuates in consideration of a sudden situation. For example, the user minimum usage load decreases from 1 ton per hour to 0.5 ton per hour. If the first steam flow is 1 ton per hour and the second steam flow is 3 tons per hour, that is, the mixed steam flow is 4 tons per hour, the user real-time usage load is 2.5 tons per hour in a certain period of time, and the molten salt heat storage steam generation system and the boiler system are both stable and continuous in steam generation. Since the user real-time usage load is less than the mixed steam flow, and the first steam flow is greater than the user minimum usage load, the mixed steam pressure value of the mixed steam will continue to rise and be higher than the first pressure threshold a. When the mixed steam pressure value is higher than the third pressure threshold c, the molten salt heat storage steam generation system is closed, and the molten salt heat storage steam generation system stops generating the first steam or the first steam flow gradually decreases, and then the mixed steam pressure value of the mixed steam will continue to decrease. When the mixed steam pressure value decreases to the fourth pressure threshold d, the molten salt heat storage steam generation system is started, and the molten salt heat storage steam generation system starts to generate the first steam. Since only the molten salt heat storage steam generation system is running at this time, and the user real-time usage load is greater than the user minimum usage load, the mixed steam pressure value of the mixed steam will continue to decrease. When the mixed steam pressure value decreases to the second pressure threshold b, the boiler system is started, and the boiler system starts to run to generate the second steam. The mixed steam pressure value of the mixed steam will gradually increase. When the mixed steam pressure value is higher than the first pressure threshold a, the boiler system is closed, and the boiler system stops running and no longer generates the second steam, so as to reduce the mixed steam pressure value. The control is circular between the first pressure threshold a and the second pressure threshold b.

[0108] The third pressure threshold c is higher than the first pressure threshold a, and the fourth pressure threshold d is higher than the second pressure threshold b and lower than the first pressure threshold a.

[0109] Since the molten salt heat storage steam generation system is based on the chemical reaction of water and molten salt to generate steam, a component for controlling the amount of water can be provided in the molten salt heat storage steam generation system, such as a metering pump for delivering water to the salt storage tank in the molten salt heat storage steam generation system to generate the first steam in the salt storage tank. By controlling the operation of the metering pump, the start-up and shutdown of the molten salt heat storage steam generation system can be controlled.

[0110] The control method of the mixed steam device based on the boiler and the molten salt heat storage of the steam of the embodiment realizes automatic, efficient and intelligent control of the molten salt heat storage steam generation system and the boiler system, meets the use requirements of users, and makes the proportion of the first steam flow output by the molten salt heat storage steam generation system meet the design value. The mixed steam pressure value of the mixed steam is controlled, further ensuring the safe operation of the mixed steam device, and continuously and stably providing steam for users.

[0111] In an optional embodiment, as shown in Figure 4 The control method further includes:

[0112] S201, obtaining a mixed steam temperature of the mixed steam.

[0113] S202, determining whether the mixed steam temperature is higher than a set first temperature threshold.

[0114] If yes, step S203 is performed, and if no, step S204 is performed.

[0115] S203, reducing the mixed steam temperature so that the mixed steam temperature meets the first temperature threshold.

[0116] S204, increasing the mixed steam temperature so that the mixed steam temperature meets the first temperature threshold.

[0117] The first temperature threshold is higher than the saturation temperature corresponding to the mixed steam pressure value, and different mixed steam pressure values correspond to different saturation temperatures.

[0118] Water is heated to boiling at a certain pressure, and water begins to vaporize, which gradually becomes steam. At this time, the temperature of the steam is equal to the saturation temperature, and such steam is called saturated steam. That is, the steam that has not been subjected to heat treatment is called saturated steam. If the saturated steam is continuously heated, its temperature will rise and exceed the saturation temperature at that pressure. Such steam that exceeds the saturation temperature is called superheated steam.

[0119] The temperature of saturated steam corresponds to the pressure, and the saturated steam is easy to condense. If there is heat loss in the transmission process, liquid droplets or liquid mist will be formed in the steam, which will cause the temperature and pressure to decrease. For example, at a standard atmospheric pressure, i.e. 100 kPa = 0.1 MPa (megapascal), the corresponding saturated temperature of the saturated steam at 0.1 MPa is 100 degrees, at 0.7 MPa is 165 degrees, at 0.9 MPa is 175 degrees, at 3 MPa is 234 degrees, and at 4 MPa is 250 degrees.

[0120] In the process of generating steam, the conventional boiler can only produce saturated steam, i.e. the second steam is saturated steam, and the first steam produced by the molten salt heat storage steam generation system is superheated steam, and the temperature of the superheated steam can be as high as more than 300 degrees. Since the mixed steam includes saturated steam and superheated steam, the actual temperature of the mixed steam is relatively high, and the temperature of the mixed steam needs to be controlled. Therefore, the temperature of the mixed steam can be controlled by adjusting the temperature of the superheated steam (the first steam).

[0121] When the user end does not require the temperature of the steam and only requires a certain steam flow (steam use load), the first temperature threshold can be set to be higher than the saturated temperature corresponding to the mixed steam pressure value. For example, the first temperature threshold is set to be 20-40 degrees higher than the saturated temperature corresponding to the mixed steam pressure value. When the mixed steam pressure value of the mixed steam is 0.7 MPa, the corresponding saturated temperature is 165 degrees. If the first temperature threshold is set to be 30 degrees higher than the saturated temperature corresponding to the mixed steam pressure value, the first temperature threshold is 195 degrees. If the mixed steam temperature is 200 degrees, since 200 degrees is higher than 195 degrees, the mixed steam temperature is reduced to meet the first temperature threshold of 195 degrees. If the mixed steam temperature is lower than the first temperature threshold of 195 degrees during the regulation process, the temperature of the mixed steam is increased to meet the first temperature threshold of 195 degrees.

[0122] Since the mixed steam pressure value of the mixed steam fluctuates in the circulation process, the first temperature threshold also fluctuates accordingly. However, the first temperature threshold is always set to be higher than the saturated temperature corresponding to the mixed steam pressure value, and the mixed steam temperature of the mixed steam is real-time regulated to meet the first temperature threshold.

[0123] Since the traditional boiler can only produce saturated steam, condensate water will be generated in the delivery of the rear-end steam, which reduces the efficiency and affects the production safety. Since the first steam produced by the molten salt heat storage steam production system is superheated steam, the first temperature threshold is set to be higher than the saturation temperature corresponding to the mixed steam pressure value, for example, set to be about forty degrees superheated. After the first steam and the second steam are mixed, the superheat degree of the mixed steam can be improved, thereby reducing the condensate water in the rear-end pipeline and saving the total amount of mixed steam.

[0124] When the user has special requirements for the temperature of the steam, the first temperature threshold can be set to be equal to the required steam temperature of the user. For example, if the required steam temperature of the user is 130 degrees, and the mixed steam temperature is 200 degrees, the temperature of the superheated steam can be adjusted according to the relationship between the mixed steam temperature and the first temperature threshold, and then the mixed steam temperature of the mixed steam is adjusted, so that the mixed steam temperature meets the first temperature threshold, thereby meeting the user's demand.

[0125] For example, a desuperheater and a variable frequency water pump are arranged in the molten salt heat storage steam production system. The variable frequency water pump is used to deliver water to the desuperheater. By adjusting the water pumping amount of the variable frequency water pump, the temperature of the superheated steam is regulated, so that the mixed steam temperature of the mixed steam is regulated.

[0126] When the mixed steam temperature is higher than the first temperature threshold, the water pumping amount of the variable frequency water pump is increased to reduce the mixed steam temperature to the first temperature threshold. When the mixed steam temperature is lower than the first temperature threshold, the water pumping amount of the variable frequency water pump is reduced to increase the mixed steam temperature to the first temperature threshold. Specifically, the variable frequency water pump can be adjusted based on the mixed steam temperature of the mixed steam. PID (proportion-integral-derivative) adjustment is a very widely used classical control theory. The basic idea is to compare the measured value of the production process parameter with the given value, obtain the deviation, and then perform proportional, integral and differential operations on the deviation to reduce the deviation value as much as possible, so that the parameter remains around the given value or changes according to the predetermined rule, and completes the adjustment and control of the production process.

[0127] The regulation method of the mixed steam device based on the boiler and the molten salt heat storage of the embodiment can automatically and accurately regulate the mixed steam temperature of the mixed steam, meet different control requirements and application scenarios, and automatically, efficiently and intelligently regulate the pressure and temperature of the molten salt heat storage steam production system and the boiler system, so as to meet the user's use requirements and make the proportion of the first steam flow output by the molten salt heat storage steam production system meet the design value.

[0128] In an optional embodiment, as shown in Figure 5 the regulation method further comprises:

[0129] S301, acquire a first steam temperature of the first steam.

[0130] S302, judge whether the first steam temperature is lower than a set second temperature threshold.

[0131] If yes, execute step S303.

[0132] S303, close the molten salt heat storage steam generation system, and charge the molten salt heat storage steam generation system.

[0133] The second temperature threshold represents a temperature corresponding to the end of discharging of the molten salt heat storage steam generation system.

[0134] Since the energy stored in the molten salt heat storage steam generation system is constant, the molten salt heat storage steam generation system stops outputting steam after the end of discharging (i.e. the chemical reaction stops); when the first steam temperature is lower than the second temperature threshold, the molten salt heat storage steam generation system ends discharging.

[0135] As described above, if the molten salt heat storage steam generation system is provided with a metering pump, a desuperheater and a variable frequency water pump, the metering pump is used to deliver water to the salt storage tank in the molten salt heat storage steam generation system to make the salt storage tank generate the first steam, and the start and stop of the molten salt heat storage steam generation system are controlled by controlling the operation of the metering pump; the variable frequency water pump is used to deliver water to the desuperheater, and the temperature of the superheated steam is regulated by adjusting the water pumping amount of the variable frequency water pump, so as to realize the regulation of the mixed steam temperature of the mixed steam; when the molten salt heat storage steam generation system ends discharging, water no longer needs to be delivered to the salt storage tank, and therefore the metering pump needs to be controlled to stop operating. The second temperature threshold is the temperature value measured by the desuperheater input end after the molten salt heat storage steam generation system ends discharging.

[0136] At a suitable time period, the molten salt in the salt storage tank in the molten salt heat storage steam generation system is heated to charge the molten salt heat storage steam generation system. For example, at a valley electricity time period, the molten salt in the salt storage tank is heated by using electric heating to charge the molten salt heat storage steam generation system, and the charging is basically complete at the end of the valley electricity, and the mixed steam completes a cycle.

[0137] Other heating methods can also be used to heat the molten salt in the salt storage tank to charge the molten salt heat storage steam generation system.

[0138] In an optional embodiment, the salt storage tank in the molten salt heat storage steam generation system comprises a single-tank salt storage tank.

[0139] The single-tank molten salt storage tank can not cut off the energy supply because the hot molten salt and the cold molten salt are stored in the same tank, and the stored water in the heat exchange pipe can supply steam for a relatively long time, which is easy to cause the proportion of the first steam flow output by the molten salt heat storage steam generation system to be higher than the design value. Therefore, accurate control of the steam quantity of the single-tank molten salt storage tank is particularly important.

[0140] The control method of the mixed steam device based on the boiler and the molten salt heat storage in the embodiment can accurately control the steam output by the molten salt heat storage steam generation system composed of the single-tank molten salt storage tank, ensure that the mixed steam meets the user's demand, and ensure that the proportion of the steam flow output by the molten salt heat storage steam generation system meets the design value.

[0141] Embodiment 2

[0142] The embodiment provides a mixed steam device, as shown in Figure 6 The mixed steam device includes a water storage tank 1, a boiler system 2, a molten salt heat storage steam generation system 3, a total and partial steam cylinder 4, and a control system 5 for realizing the control method in the embodiment 1. The molten salt heat storage steam generation system 3 is connected to the boiler system 2 through a parallel pipe connection mode and is arranged between the water storage tank 1 and the total and partial steam cylinder 4.

[0143] As shown in Figure 7 The control system 5 includes:

[0144] The pressure acquisition module 51 is configured to acquire a mixed steam pressure value of the mixed steam.

[0145] The pressure control module 52 is configured to adopt a gradient adjustment strategy, judge a value interval in which the mixed steam pressure value is located, and control the molten salt heat storage steam generation system and the boiler system.

[0146] The first steam flow corresponding to the first steam meets a first steam use load, and the mixed steam flow corresponding to the mixed steam meets a second steam use load. The second steam use load is greater than the first steam use load.

[0147] Specifically, the boiler system 2 generates the second steam, the molten salt heat storage steam generation system 3 generates the first steam, and the first steam and the second steam are mixed in the total and partial steam cylinder 4 to output the mixed steam.

[0148] In an optional embodiment, the pressure control module 52 includes:

[0149] The first pressure adjustment unit 521 is configured to set a first pressure threshold, judge whether the mixed steam pressure value is higher than the first pressure threshold, and if yes, close the boiler system.

[0150] The second pressure regulating unit 522 is configured to set a second pressure threshold, determine whether the mixed steam pressure value is lower than the second pressure threshold, and start the boiler system if yes;

[0151] The third pressure regulating unit 523 is configured to set a third pressure threshold, determine whether the mixed steam pressure value is higher than the third pressure threshold, and shut down the molten salt heat storage steam generation system if yes.

[0152] The fourth pressure regulating unit 524 is configured to set a fourth pressure threshold, determine whether the mixed steam pressure value is lower than the fourth pressure threshold, and start the molten salt heat storage steam generation system if yes.

[0153] In an optional embodiment, the regulating system further comprises:

[0154] The mixed steam temperature acquisition module 53 is configured to acquire a mixed steam temperature of the mixed steam.

[0155] The first preset temperature acquisition module 54 is configured to set a first temperature threshold according to a saturation temperature corresponding to the mixed steam pressure value.

[0156] The temperature regulating module 55 is configured to determine whether the mixed steam temperature is higher than the set first temperature threshold, lower the mixed steam temperature to make the mixed steam temperature meet the first temperature threshold if yes, and raise the mixed steam temperature to make the mixed steam temperature meet the first temperature threshold if no.

[0157] In an optional embodiment, the regulating system further comprises:

[0158] The first steam temperature acquisition module 56 is configured to acquire a first steam temperature of the first steam.

[0159] The second preset temperature acquisition module 57 is configured to set a second temperature threshold according to a temperature corresponding to the end of energy release of the molten salt heat storage steam generation system.

[0160] The temperature regulating module 55 is further configured to determine whether the first steam temperature is lower than the set second temperature threshold, shut down the molten salt heat storage steam generation system, and charge the molten salt heat storage steam generation system if yes.

[0161] In an optional embodiment, as shown in FIG. 1, the molten salt heat storage steam generation system 3 comprises a heat storage system steam dividing cylinder 31, a desuperheater 32, and a plurality of salt storage tanks 33 and metering pumps 34. Figure 6

[0162] The salt storage tanks 33 are arranged between the water storage tank 1 and the heat storage system steam dividing cylinder 31 through a parallel pipe connection mode, and the metering pumps 34 and the salt storage tanks 33 are connected one by one.

[0163] ​The desuperheater 32 is arranged between the heat storage system cylinder 31 and the total cylinder 4, and the desuperheater 32 is provided with a branch pipeline connected to the water storage tank 1, and the branch pipeline is provided with a variable frequency water pump 35.

[0164] The metering pump 34 is used to transport water to the molten salt storage tank 33 in the molten salt heat storage steam generation system, so that the molten salt in the molten salt storage tank 33 reacts with water to generate steam. By controlling the operation of the metering pump 34, the start and stop of the molten salt heat storage steam generation system can be controlled.

[0165] The heat storage system cylinder 31 is used to combine the steam generated by each molten salt storage tank 33.

[0166] The variable frequency water pump 35 is used to transport water to the desuperheater 32, and the desuperheater 32 is used to reduce the temperature of the superheated steam to a certain extent. By adjusting the water pumping amount of the variable frequency water pump 35, the temperature of the superheated steam can be controlled, so that the mixed steam temperature of the mixed steam can be controlled.

[0167] Figure 6 The plurality of molten salt storage tanks 33 constitute a modular molten salt heat storage steam generation system, and the steam generated by the plurality of molten salt storage tanks is mixed in the heat storage system cylinder 31 to form first steam. Each module has a rated steam output, and the number of modules used can be obtained by dividing the first steam usage load by the rated steam output of each module. These modules are used in parallel. Each module has a metering pump 34, and the metering pump 34 belongs to a volumetric pump, and the output flow is very stable, which means that the first steam output by the entire molten salt heat storage steam generation system is very stable. The first steam is used to cover the first steam usage load in the steam system.

[0168] In an optional embodiment, the molten salt heat storage steam generation system 3 further comprises a heater, and the heater is used to heat the molten salt in the molten salt storage tank 33 to charge the molten salt heat storage steam generation system.

[0169] In an optional embodiment, as shown in Figure 6 The boiler system 2 comprises a boiler 21, a feed water pump 22 and a pressure sensor 23, and the feed water pump 22 is arranged between the water storage tank 1 and the boiler 21.

[0170] The feed water pump 22 is used to supply water to the boiler 21 to maintain the normal operation of the boiler 21. The boiler system 2 further comprises a pressure switch, and the pressure switch is used to start or stop the operation of the boiler system.

[0171] In an optional embodiment, as shown in Figure 6 The mixed steam device comprises a pressure sensor 6, and the pressure sensor 6 is used to collect the mixed steam pressure value of the mixed steam. The pressure acquisition module 51 can acquire the mixed steam pressure value of the mixed steam collected by the pressure sensor 6.

[0172] In an optional embodiment, as shown in Figure 6 The mixed steam device comprises a temperature sensor A7 configured to collect a mixed steam temperature of the mixed steam, and the mixed steam temperature acquisition module 53 can acquire the mixed steam temperature collected by the temperature sensor A7.

[0173] Specifically, the pressure sensor 6 and the temperature sensor A7 are arranged at the output end of the total-steam cylinder 4 to collect a mixed steam pressure value and a mixed temperature value of the mixed steam, respectively.

[0174] In an optional embodiment, the molten salt heat storage steam generation system 3 comprises a temperature sensor B36 arranged between the desuperheater 32 and the heat storage system steam cylinder 31 and configured to collect a first steam temperature of the first steam, the first steam temperature being the temperature of the first steam before entering the desuperheater 32. The second preset temperature acquisition module 57 can acquire the first steam temperature collected by the temperature sensor B36.

[0175] In an optional embodiment, as shown in ​ The molten salt heat storage steam generation system 3 further comprises a pressure sensor 37 configured to detect a steam pressure value at the output end of the desuperheater 32.

[0176] The working principle of the control system in this embodiment is the same as that of the control method based on the boiler and the molten salt heat storage steam generation system in Embodiment 1, and thus will not be described here.

[0177] The mixed steam device of this embodiment is configured with the control system for implementing the control method in Embodiment 1, and based on the control system, the molten salt heat storage steam generation system and the boiler system are automatically, efficiently and intelligently controlled, which meets the user's use requirements and makes the proportion of the first steam flow output by the molten salt heat storage steam generation system meet the design value.

[0178] Although the specific embodiments of the present disclosure are described above, those skilled in the art should understand that this is only an example, and the protection scope of the present disclosure is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the present disclosure, and these changes and modifications all fall within the protection scope of the present disclosure.

Claims

1. A method of regulating a hybrid steam plant based on a boiler and molten salt thermal storage, characterized by, The mixed steam device comprises a boiler system and a molten salt heat storage steam generation system, and first steam generated by the molten salt heat storage steam generation system is mixed with second steam generated by the boiler system to output mixed steam; The control method comprises: obtaining a mixed steam pressure value of the mixed steam; using a gradient adjustment strategy to determine a numerical interval in which the mixed steam pressure value is located, and controlling the molten salt heat storage steam generation system and the boiler system; wherein a first steam flow corresponding to the first steam satisfies a first steam use load, and a mixed steam flow corresponding to the mixed steam satisfies a second steam use load; the second steam use load is greater than the first steam use load; the gradient adjustment strategy comprises: setting a first pressure threshold and a second pressure threshold; determining whether the mixed steam pressure value is higher than the first pressure threshold, and if so, shutting down the boiler system; determining whether the mixed steam pressure value is lower than the second pressure threshold, and if so, starting the boiler system; wherein the first pressure threshold is higher than the second pressure threshold.

2. The method of claim 1, wherein, The gradient adjustment strategy further comprises: setting a third pressure threshold and a fourth pressure threshold; determining whether the mixed steam pressure value is higher than the third pressure threshold, and if so, shutting down the molten salt heat storage steam generation system; determining whether the mixed steam pressure value is lower than the fourth pressure threshold, and if so, starting the molten salt heat storage steam generation system; wherein the third pressure threshold is higher than the first pressure threshold; the fourth pressure threshold is higher than the second pressure threshold and lower than the first pressure threshold.

3. The method of claim 1, wherein the step of modulating comprises: The control method further comprises: obtaining a mixed steam temperature of the mixed steam; determining whether the mixed steam temperature is higher than a set first temperature threshold; if so, reducing the mixed steam temperature so that the mixed steam temperature satisfies the first temperature threshold; if not, increasing the mixed steam temperature so that the mixed steam temperature satisfies the first temperature threshold; wherein the first temperature threshold is higher than a saturation temperature corresponding to the mixed steam pressure value, and different mixed steam pressure values correspond to different saturation temperatures.

4. The method of claim 1, wherein the step of modulating comprises: The control method further comprises: obtaining a first steam temperature of the first steam; determining whether the first steam temperature is lower than a set second temperature threshold; if so, shutting down the molten salt heat storage steam generation system and charging the molten salt heat storage steam generation system; wherein the second temperature threshold represents a temperature corresponding to the end of energy release of the molten salt heat storage steam generation system.

5. A hybrid steam device characterized by, The mixed steam device comprises a water storage tank, a boiler system, a molten salt heat storage steam generation system, a total and partial steam cylinder, and a control system for implementing the control method of any one of claims 1-4, the molten salt heat storage steam generation system and the boiler system being connected in parallel through a pipeline connection mode and being arranged between the water storage tank and the total and partial steam cylinder; The control system comprises: a pressure acquisition module configured to obtain a mixed steam pressure value of the mixed steam; The pressure regulation module is configured to adopt a gradient regulation strategy, determine a numerical interval in which the mixed steam pressure value is located, and regulate the molten salt heat storage steam generation system and the boiler system. The pressure regulation module comprises a first pressure regulation unit and a second pressure regulation unit. The first pressure regulation unit is configured to set a first pressure threshold, determine whether the mixed steam pressure value is higher than the first pressure threshold, and if so, shut down the boiler system. The second pressure regulation unit is configured to set a second pressure threshold, determine whether the mixed steam pressure value is lower than the second pressure threshold, and if so, start the boiler system. The first pressure threshold is greater than the second pressure threshold.

6. A hybrid steam device according to claim 5, wherein, The pressure regulation module further comprises: The third pressure regulation unit is configured to set a third pressure threshold, determine whether the mixed steam pressure value is higher than the third pressure threshold, and if so, shut down the molten salt heat storage steam generation system. The fourth pressure regulation unit is configured to set a fourth pressure threshold, determine whether the mixed steam pressure value is lower than the fourth pressure threshold, and if so, start the molten salt heat storage steam generation system.

7. A hybrid steam device according to claim 5, wherein, The regulation system further comprises: The mixed steam temperature acquisition module is configured to acquire a mixed steam temperature of the mixed steam. The first preset temperature acquisition module is configured to set a first temperature threshold according to a saturation temperature corresponding to the mixed steam pressure value. The temperature regulation module is configured to determine whether the mixed steam temperature is higher than the set first temperature threshold. If so, the mixed steam temperature is lowered to meet the first temperature threshold. If not, the mixed steam temperature is raised to meet the first temperature threshold.

8. A hybrid steam device according to claim 7, wherein, The regulation system further comprises: The first steam temperature acquisition module is configured to acquire a first steam temperature of the first steam. The second preset temperature acquisition module is configured to set a second temperature threshold according to a temperature corresponding to the end of energy release of the molten salt heat storage steam generation system. The temperature regulation module is further configured to determine whether the first steam temperature is lower than the set second temperature threshold. If so, the molten salt heat storage steam generation system is shut down and charged.

9. A hybrid steam device according to claim 5, wherein, The molten salt heat storage steam generation system comprises a heat storage system cylinder, a desuperheater, and a plurality of salt storage tanks and metering pumps. The salt storage tanks are connected between the water storage tank and the heat storage system cylinder by parallel pipeline connection, and the metering pumps and the salt storage tanks are connected one by one. The desuperheater is arranged between the heat storage system cylinder and the total and partial cylinder, and is provided with a branch pipeline connected to the water storage tank, and a variable frequency water pump is arranged on the branch pipeline.

Images